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| -rw-r--r-- | gc/doc/README | 618 | ||||
| -rw-r--r-- | gc/doc/README.DGUX386 | 215 | ||||
| -rw-r--r-- | gc/doc/README.Mac | 385 | ||||
| -rw-r--r-- | gc/doc/README.MacOSX | 27 | ||||
| -rw-r--r-- | gc/doc/README.OS2 | 6 | ||||
| -rw-r--r-- | gc/doc/README.amiga | 322 | ||||
| -rwxr-xr-x | gc/doc/README.arm.cross | 68 | ||||
| -rw-r--r-- | gc/doc/README.autoconf | 59 | ||||
| -rw-r--r-- | gc/doc/README.changes | 1653 | ||||
| -rw-r--r-- | gc/doc/README.contributors | 57 | ||||
| -rw-r--r-- | gc/doc/README.cords | 53 | ||||
| -rw-r--r-- | gc/doc/README.dj | 12 | ||||
| -rw-r--r-- | gc/doc/README.environment | 101 | ||||
| -rw-r--r-- | gc/doc/README.ews4800 | 81 | ||||
| -rw-r--r-- | gc/doc/README.hp | 18 | ||||
| -rw-r--r-- | gc/doc/README.linux | 135 | ||||
| -rw-r--r-- | gc/doc/README.macros | 78 | ||||
| -rw-r--r-- | gc/doc/README.rs6000 | 9 | ||||
| -rw-r--r-- | gc/doc/README.sgi | 41 | ||||
| -rw-r--r-- | gc/doc/README.solaris2 | 62 | ||||
| -rw-r--r-- | gc/doc/README.uts | 2 | ||||
| -rw-r--r-- | gc/doc/README.win32 | 164 |
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diff --git a/gc/doc/README b/gc/doc/README deleted file mode 100644 index 09ae43b..0000000 --- a/gc/doc/README +++ /dev/null @@ -1,618 +0,0 @@ -Copyright (c) 1988, 1989 Hans-J. Boehm, Alan J. Demers -Copyright (c) 1991-1996 by Xerox Corporation. All rights reserved. -Copyright (c) 1996-1999 by Silicon Graphics. All rights reserved. -Copyright (c) 1999-2001 by Hewlett-Packard Company. All rights reserved. - -The file linux_threads.c is also -Copyright (c) 1998 by Fergus Henderson. All rights reserved. - -The files Makefile.am, and configure.in are -Copyright (c) 2001 by Red Hat Inc. All rights reserved. - -Several files supporting GNU-style builds are copyrighted by the Free -Software Foundation, and carry a different license from that given -below. - -THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED -OR IMPLIED. ANY USE IS AT YOUR OWN RISK. - -Permission is hereby granted to use or copy this program -for any purpose, provided the above notices are retained on all copies. -Permission to modify the code and to distribute modified code is granted, -provided the above notices are retained, and a notice that the code was -modified is included with the above copyright notice. - -A few of the files needed to use the GNU-style build procedure come with -slightly different licenses, though they are all similar in spirit. A few -are GPL'ed, but with an exception that should cover all uses in the -collector. (If you are concerned about such things, I recommend you look -at the notice in config.guess or ltmain.sh.) - -This is version 6.1alpha5 of a conservative garbage collector for C and C++. - -You might find a more recent version of this at - -http://www.hpl.hp.com/personal/Hans_Boehm/gc - -OVERVIEW - - This is intended to be a general purpose, garbage collecting storage -allocator. The algorithms used are described in: - -Boehm, H., and M. Weiser, "Garbage Collection in an Uncooperative Environment", -Software Practice & Experience, September 1988, pp. 807-820. - -Boehm, H., A. Demers, and S. Shenker, "Mostly Parallel Garbage Collection", -Proceedings of the ACM SIGPLAN '91 Conference on Programming Language Design -and Implementation, SIGPLAN Notices 26, 6 (June 1991), pp. 157-164. - -Boehm, H., "Space Efficient Conservative Garbage Collection", Proceedings -of the ACM SIGPLAN '91 Conference on Programming Language Design and -Implementation, SIGPLAN Notices 28, 6 (June 1993), pp. 197-206. - -Boehm H., "Reducing Garbage Collector Cache Misses", Proceedings of the -2000 International Symposium on Memory Management. - - Possible interactions between the collector and optimizing compilers are -discussed in - -Boehm, H., and D. Chase, "A Proposal for GC-safe C Compilation", -The Journal of C Language Translation 4, 2 (December 1992). - -and - -Boehm H., "Simple GC-safe Compilation", Proceedings -of the ACM SIGPLAN '96 Conference on Programming Language Design and -Implementation. - -(Some of these are also available from -http://www.hpl.hp.com/personal/Hans_Boehm/papers/, among other places.) - - Unlike the collector described in the second reference, this collector -operates either with the mutator stopped during the entire collection -(default) or incrementally during allocations. (The latter is supported -on only a few machines.) On the most common platforms, it can be built -with or without thread support. On a few platforms, it can take advantage -of a multiprocessor to speed up garbage collection. - - Many of the ideas underlying the collector have previously been explored -by others. Notably, some of the run-time systems developed at Xerox PARC -in the early 1980s conservatively scanned thread stacks to locate possible -pointers (cf. Paul Rovner, "On Adding Garbage Collection and Runtime Types -to a Strongly-Typed Statically Checked, Concurrent Language" Xerox PARC -CSL 84-7). Doug McIlroy wrote a simpler fully conservative collector that -was part of version 8 UNIX (tm), but appears to not have received -widespread use. - - Rudimentary tools for use of the collector as a leak detector are included -(see http://www.hpl.hp.com/personal/Hans_Boehm/gc/leak.html), -as is a fairly sophisticated string package "cord" that makes use of the -collector. (See doc/README.cords and H.-J. Boehm, R. Atkinson, and M. Plass, -"Ropes: An Alternative to Strings", Software Practice and Experience 25, 12 -(December 1995), pp. 1315-1330. This is very similar to the "rope" package -in Xerox Cedar, or the "rope" package in the SGI STL or the g++ distribution.) - -Further collector documantation can be found at - -http://www.hpl.hp.com/personal/Hans_Boehm/gc - - -GENERAL DESCRIPTION - - This is a garbage collecting storage allocator that is intended to be -used as a plug-in replacement for C's malloc. - - Since the collector does not require pointers to be tagged, it does not -attempt to ensure that all inaccessible storage is reclaimed. However, -in our experience, it is typically more successful at reclaiming unused -memory than most C programs using explicit deallocation. Unlike manually -introduced leaks, the amount of unreclaimed memory typically stays -bounded. - - In the following, an "object" is defined to be a region of memory allocated -by the routines described below. - - Any objects not intended to be collected must be pointed to either -from other such accessible objects, or from the registers, -stack, data, or statically allocated bss segments. Pointers from -the stack or registers may point to anywhere inside an object. -The same is true for heap pointers if the collector is compiled with - ALL_INTERIOR_POINTERS defined, as is now the default. - -Compiling without ALL_INTERIOR_POINTERS may reduce accidental retention -of garbage objects, by requiring pointers from the heap to to the beginning -of an object. But this no longer appears to be a significant -issue for most programs. - -There are a number of routines which modify the pointer recognition -algorithm. GC_register_displacement allows certain interior pointers -to be recognized even if ALL_INTERIOR_POINTERS is nor defined. -GC_malloc_ignore_off_page allows some pointers into the middle of large objects -to be disregarded, greatly reducing the probablility of accidental -retention of large objects. For most purposes it seems best to compile -with ALL_INTERIOR_POINTERS and to use GC_malloc_ignore_off_page if -you get collector warnings from allocations of very large objects. -See README.debugging for details. - - WARNING: pointers inside memory allocated by the standard "malloc" are not -seen by the garbage collector. Thus objects pointed to only from such a -region may be prematurely deallocated. It is thus suggested that the -standard "malloc" be used only for memory regions, such as I/O buffers, that -are guaranteed not to contain pointers to garbage collectable memory. -Pointers in C language automatic, static, or register variables, -are correctly recognized. (Note that GC_malloc_uncollectable has semantics -similar to standard malloc, but allocates objects that are traced by the -collector.) - - WARNING: the collector does not always know how to find pointers in data -areas that are associated with dynamic libraries. This is easy to -remedy IF you know how to find those data areas on your operating -system (see GC_add_roots). Code for doing this under SunOS, IRIX 5.X and 6.X, -HP/UX, Alpha OSF/1, Linux, and win32 is included and used by default. (See -README.win32 for win32 details.) On other systems pointers from dynamic -library data areas may not be considered by the collector. -If you're writing a program that depends on the collector scanning -dynamic library data areas, it may be a good idea to include at least -one call to GC_is_visible() to ensure that those areas are visible -to the collector. - - Note that the garbage collector does not need to be informed of shared -read-only data. However if the shared library mechanism can introduce -discontiguous data areas that may contain pointers, then the collector does -need to be informed. - - Signal processing for most signals may be deferred during collection, -and during uninterruptible parts of the allocation process. -Like standard ANSI C mallocs, by default it is unsafe to invoke -malloc (and other GC routines) from a signal handler while another -malloc call may be in progress. Removing -DNO_SIGNALS from Makefile -attempts to remedy that. But that may not be reliable with a compiler that -substantially reorders memory operations inside GC_malloc. - - The allocator/collector can also be configured for thread-safe operation. -(Full signal safety can also be achieved, but only at the cost of two system -calls per malloc, which is usually unacceptable.) -WARNING: the collector does not guarantee to scan thread-local storage -(e.g. of the kind accessed with pthread_getspecific()). The collector -does scan thread stacks, though, so generally the best solution is to -ensure that any pointers stored in thread-local storage are also -stored on the thread's stack for the duration of their lifetime. -(This is arguably a longstanding bug, but it hasn't been fixed yet.) - -INSTALLATION AND PORTABILITY - - As distributed, the macro SILENT is defined in Makefile. -In the event of problems, this can be removed to obtain a moderate -amount of descriptive output for each collection. -(The given statistics exhibit a few peculiarities. -Things don't appear to add up for a variety of reasons, most notably -fragmentation losses. These are probably much more significant for the -contrived program "test.c" than for your application.) - - Note that typing "make test" will automatically build the collector -and then run setjmp_test and gctest. Setjmp_test will give you information -about configuring the collector, which is useful primarily if you have -a machine that's not already supported. Gctest is a somewhat superficial -test of collector functionality. Failure is indicated by a core dump or -a message to the effect that the collector is broken. Gctest takes about -35 seconds to run on a SPARCstation 2. It may use up to 8 MB of memory. (The -multi-threaded version will use more. 64-bit versions may use more.) -"Make test" will also, as its last step, attempt to build and test the -"cord" string library. This will fail without an ANSI C compiler, but -the garbage collector itself should still be usable. - - The Makefile will generate a library gc.a which you should link against. -Typing "make cords" will add the cord library to gc.a. -Note that this requires an ANSI C compiler. - - It is suggested that if you need to replace a piece of the collector -(e.g. GC_mark_rts.c) you simply list your version ahead of gc.a on the -ld command line, rather than replacing the one in gc.a. (This will -generate numerous warnings under some versions of AIX, but it still -works.) - - All include files that need to be used by clients will be put in the -include subdirectory. (Normally this is just gc.h. "Make cords" adds -"cord.h" and "ec.h".) - - The collector currently is designed to run essentially unmodified on -machines that use a flat 32-bit or 64-bit address space. -That includes the vast majority of Workstations and X86 (X >= 3) PCs. -(The list here was deleted because it was getting too long and constantly -out of date.) - It does NOT run under plain 16-bit DOS or Windows 3.X. There are however -various packages (e.g. win32s, djgpp) that allow flat 32-bit address -applications to run under those systemsif the have at least an 80386 processor, -and several of those are compatible with the collector. - - In a few cases (Amiga, OS/2, Win32, MacOS) a separate makefile -or equivalent is supplied. Many of these have separate README.system -files. - - Dynamic libraries are completely supported only under SunOS -(and even that support is not functional on the last Sun 3 release), -Linux, IRIX 5&6, HP-PA, Win32 (not Win32S) and OSF/1 on DEC AXP machines. -On other machines we recommend that you do one of the following: - - 1) Add dynamic library support (and send us the code). - 2) Use static versions of the libraries. - 3) Arrange for dynamic libraries to use the standard malloc. - This is still dangerous if the library stores a pointer to a - garbage collected object. But nearly all standard interfaces - prohibit this, because they deal correctly with pointers - to stack allocated objects. (Strtok is an exception. Don't - use it.) - - In all cases we assume that pointer alignment is consistent with that -enforced by the standard C compilers. If you use a nonstandard compiler -you may have to adjust the alignment parameters defined in gc_priv.h. - - A port to a machine that is not byte addressed, or does not use 32 bit -or 64 bit addresses will require a major effort. A port to plain MSDOS -or win16 is hard. - - For machines not already mentioned, or for nonstandard compilers, the -following are likely to require change: - -1. The parameters in gcconfig.h. - The parameters that will usually require adjustment are - STACKBOTTOM, ALIGNMENT and DATASTART. Setjmp_test - prints its guesses of the first two. - DATASTART should be an expression for computing the - address of the beginning of the data segment. This can often be - &etext. But some memory management units require that there be - some unmapped space between the text and the data segment. Thus - it may be more complicated. On UNIX systems, this is rarely - documented. But the adb "$m" command may be helpful. (Note - that DATASTART will usually be a function of &etext. Thus a - single experiment is usually insufficient.) - STACKBOTTOM is used to initialize GC_stackbottom, which - should be a sufficient approximation to the coldest stack address. - On some machines, it is difficult to obtain such a value that is - valid across a variety of MMUs, OS releases, etc. A number of - alternatives exist for using the collector in spite of this. See the - discussion in gcconfig.h immediately preceding the various - definitions of STACKBOTTOM. - -2. mach_dep.c. - The most important routine here is one to mark from registers. - The distributed file includes a generic hack (based on setjmp) that - happens to work on many machines, and may work on yours. Try - compiling and running setjmp_t.c to see whether it has a chance of - working. (This is not correct C, so don't blame your compiler if it - doesn't work. Based on limited experience, register window machines - are likely to cause trouble. If your version of setjmp claims that - all accessible variables, including registers, have the value they - had at the time of the longjmp, it also will not work. Vanilla 4.2 BSD - on Vaxen makes such a claim. SunOS does not.) - If your compiler does not allow in-line assembly code, or if you prefer - not to use such a facility, mach_dep.c may be replaced by a .s file - (as we did for the MIPS machine and the PC/RT). - At this point enough architectures are supported by mach_dep.c - that you will rarely need to do more than adjust for assembler - syntax. - -3. os_dep.c (and gc_priv.h). - Several kinds of operating system dependent routines reside here. - Many are optional. Several are invoked only through corresponding - macros in gc_priv.h, which may also be redefined as appropriate. - The routine GC_register_data_segments is crucial. It registers static - data areas that must be traversed by the collector. (User calls to - GC_add_roots may sometimes be used for similar effect.) - Routines to obtain memory from the OS also reside here. - Alternatively this can be done entirely by the macro GET_MEM - defined in gc_priv.h. Routines to disable and reenable signals - also reside here if they are need by the macros DISABLE_SIGNALS - and ENABLE_SIGNALS defined in gc_priv.h. - In a multithreaded environment, the macros LOCK and UNLOCK - in gc_priv.h will need to be suitably redefined. - The incremental collector requires page dirty information, which - is acquired through routines defined in os_dep.c. Unless directed - otherwise by gcconfig.h, these are implemented as stubs that simply - treat all pages as dirty. (This of course makes the incremental - collector much less useful.) - -4. dyn_load.c - This provides a routine that allows the collector to scan data - segments associated with dynamic libraries. Often it is not - necessary to provide this routine unless user-written dynamic - libraries are used. - - For a different version of UN*X or different machines using the -Motorola 68000, Vax, SPARC, 80386, NS 32000, PC/RT, or MIPS architecture, -it should frequently suffice to change definitions in gcconfig.h. - - -THE C INTERFACE TO THE ALLOCATOR - - The following routines are intended to be directly called by the user. -Note that usually only GC_malloc is necessary. GC_clear_roots and GC_add_roots -calls may be required if the collector has to trace from nonstandard places -(e.g. from dynamic library data areas on a machine on which the -collector doesn't already understand them.) On some machines, it may -be desirable to set GC_stacktop to a good approximation of the stack base. -(This enhances code portability on HP PA machines, since there is no -good way for the collector to compute this value.) Client code may include -"gc.h", which defines all of the following, plus many others. - -1) GC_malloc(nbytes) - - allocate an object of size nbytes. Unlike malloc, the object is - cleared before being returned to the user. Gc_malloc will - invoke the garbage collector when it determines this to be appropriate. - GC_malloc may return 0 if it is unable to acquire sufficient - space from the operating system. This is the most probable - consequence of running out of space. Other possible consequences - are that a function call will fail due to lack of stack space, - or that the collector will fail in other ways because it cannot - maintain its internal data structures, or that a crucial system - process will fail and take down the machine. Most of these - possibilities are independent of the malloc implementation. - -2) GC_malloc_atomic(nbytes) - - allocate an object of size nbytes that is guaranteed not to contain any - pointers. The returned object is not guaranteed to be cleared. - (Can always be replaced by GC_malloc, but results in faster collection - times. The collector will probably run faster if large character - arrays, etc. are allocated with GC_malloc_atomic than if they are - statically allocated.) - -3) GC_realloc(object, new_size) - - change the size of object to be new_size. Returns a pointer to the - new object, which may, or may not, be the same as the pointer to - the old object. The new object is taken to be atomic iff the old one - was. If the new object is composite and larger than the original object, - then the newly added bytes are cleared (we hope). This is very likely - to allocate a new object, unless MERGE_SIZES is defined in gc_priv.h. - Even then, it is likely to recycle the old object only if the object - is grown in small additive increments (which, we claim, is generally bad - coding practice.) - -4) GC_free(object) - - explicitly deallocate an object returned by GC_malloc or - GC_malloc_atomic. Not necessary, but can be used to minimize - collections if performance is critical. Probably a performance - loss for very small objects (<= 8 bytes). - -5) GC_expand_hp(bytes) - - Explicitly increase the heap size. (This is normally done automatically - if a garbage collection failed to GC_reclaim enough memory. Explicit - calls to GC_expand_hp may prevent unnecessarily frequent collections at - program startup.) - -6) GC_malloc_ignore_off_page(bytes) - - identical to GC_malloc, but the client promises to keep a pointer to - the somewhere within the first 256 bytes of the object while it is - live. (This pointer should nortmally be declared volatile to prevent - interference from compiler optimizations.) This is the recommended - way to allocate anything that is likely to be larger than 100Kbytes - or so. (GC_malloc may result in failure to reclaim such objects.) - -7) GC_set_warn_proc(proc) - - Can be used to redirect warnings from the collector. Such warnings - should be rare, and should not be ignored during code development. - -8) GC_enable_incremental() - - Enables generational and incremental collection. Useful for large - heaps on machines that provide access to page dirty information. - Some dirty bit implementations may interfere with debugging - (by catching address faults) and place restrictions on heap arguments - to system calls (since write faults inside a system call may not be - handled well). - -9) Several routines to allow for registration of finalization code. - User supplied finalization code may be invoked when an object becomes - unreachable. To call (*f)(obj, x) when obj becomes inaccessible, use - GC_register_finalizer(obj, f, x, 0, 0); - For more sophisticated uses, and for finalization ordering issues, - see gc.h. - - The global variable GC_free_space_divisor may be adjusted up from its -default value of 4 to use less space and more collection time, or down for -the opposite effect. Setting it to 1 or 0 will effectively disable collections -and cause all allocations to simply grow the heap. - - The variable GC_non_gc_bytes, which is normally 0, may be changed to reflect -the amount of memory allocated by the above routines that should not be -considered as a candidate for collection. Careless use may, of course, result -in excessive memory consumption. - - Some additional tuning is possible through the parameters defined -near the top of gc_priv.h. - - If only GC_malloc is intended to be used, it might be appropriate to define: - -#define malloc(n) GC_malloc(n) -#define calloc(m,n) GC_malloc((m)*(n)) - - For small pieces of VERY allocation intensive code, gc_inl.h -includes some allocation macros that may be used in place of GC_malloc -and friends. - - All externally visible names in the garbage collector start with "GC_". -To avoid name conflicts, client code should avoid this prefix, except when -accessing garbage collector routines or variables. - - There are provisions for allocation with explicit type information. -This is rarely necessary. Details can be found in gc_typed.h. - -THE C++ INTERFACE TO THE ALLOCATOR: - - The Ellis-Hull C++ interface to the collector is included in -the collector distribution. If you intend to use this, type -"make c++" after the initial build of the collector is complete. -See gc_cpp.h for the definition of the interface. This interface -tries to approximate the Ellis-Detlefs C++ garbage collection -proposal without compiler changes. - -Cautions: -1. Arrays allocated without new placement syntax are -allocated as uncollectable objects. They are traced by the -collector, but will not be reclaimed. - -2. Failure to use "make c++" in combination with (1) will -result in arrays allocated using the default new operator. -This is likely to result in disaster without linker warnings. - -3. If your compiler supports an overloaded new[] operator, -then gc_cpp.cc and gc_cpp.h should be suitably modified. - -4. Many current C++ compilers have deficiencies that -break some of the functionality. See the comments in gc_cpp.h -for suggested workarounds. - -USE AS LEAK DETECTOR: - - The collector may be used to track down leaks in C programs that are -intended to run with malloc/free (e.g. code with extreme real-time or -portability constraints). To do so define FIND_LEAK in Makefile -This will cause the collector to invoke the report_leak -routine defined near the top of reclaim.c whenever an inaccessible -object is found that has not been explicitly freed. Such objects will -also be automatically reclaimed. - Productive use of this facility normally involves redefining report_leak -to do something more intelligent. This typically requires annotating -objects with additional information (e.g. creation time stack trace) that -identifies their origin. Such code is typically not very portable, and is -not included here, except on SPARC machines. - If all objects are allocated with GC_DEBUG_MALLOC (see next section), -then the default version of report_leak will report the source file -and line number at which the leaked object was allocated. This may -sometimes be sufficient. (On SPARC/SUNOS4 machines, it will also report -a cryptic stack trace. This can often be turned into a sympolic stack -trace by invoking program "foo" with "callprocs foo". Callprocs is -a short shell script that invokes adb to expand program counter values -to symbolic addresses. It was largely supplied by Scott Schwartz.) - Note that the debugging facilities described in the next section can -sometimes be slightly LESS effective in leak finding mode, since in -leak finding mode, GC_debug_free actually results in reuse of the object. -(Otherwise the object is simply marked invalid.) Also note that the test -program is not designed to run meaningfully in FIND_LEAK mode. -Use "make gc.a" to build the collector. - -DEBUGGING FACILITIES: - - The routines GC_debug_malloc, GC_debug_malloc_atomic, GC_debug_realloc, -and GC_debug_free provide an alternate interface to the collector, which -provides some help with memory overwrite errors, and the like. -Objects allocated in this way are annotated with additional -information. Some of this information is checked during garbage -collections, and detected inconsistencies are reported to stderr. - - Simple cases of writing past the end of an allocated object should -be caught if the object is explicitly deallocated, or if the -collector is invoked while the object is live. The first deallocation -of an object will clear the debugging info associated with an -object, so accidentally repeated calls to GC_debug_free will report the -deallocation of an object without debugging information. Out of -memory errors will be reported to stderr, in addition to returning -NIL. - - GC_debug_malloc checking during garbage collection is enabled -with the first call to GC_debug_malloc. This will result in some -slowdown during collections. If frequent heap checks are desired, -this can be achieved by explicitly invoking GC_gcollect, e.g. from -the debugger. - - GC_debug_malloc allocated objects should not be passed to GC_realloc -or GC_free, and conversely. It is however acceptable to allocate only -some objects with GC_debug_malloc, and to use GC_malloc for other objects, -provided the two pools are kept distinct. In this case, there is a very -low probablility that GC_malloc allocated objects may be misidentified as -having been overwritten. This should happen with probability at most -one in 2**32. This probability is zero if GC_debug_malloc is never called. - - GC_debug_malloc, GC_malloc_atomic, and GC_debug_realloc take two -additional trailing arguments, a string and an integer. These are not -interpreted by the allocator. They are stored in the object (the string is -not copied). If an error involving the object is detected, they are printed. - - The macros GC_MALLOC, GC_MALLOC_ATOMIC, GC_REALLOC, GC_FREE, and -GC_REGISTER_FINALIZER are also provided. These require the same arguments -as the corresponding (nondebugging) routines. If gc.h is included -with GC_DEBUG defined, they call the debugging versions of these -functions, passing the current file name and line number as the two -extra arguments, where appropriate. If gc.h is included without GC_DEBUG -defined, then all these macros will instead be defined to their nondebugging -equivalents. (GC_REGISTER_FINALIZER is necessary, since pointers to -objects with debugging information are really pointers to a displacement -of 16 bytes form the object beginning, and some translation is necessary -when finalization routines are invoked. For details, about what's stored -in the header, see the definition of the type oh in debug_malloc.c) - -INCREMENTAL/GENERATIONAL COLLECTION: - -The collector normally interrupts client code for the duration of -a garbage collection mark phase. This may be unacceptable if interactive -response is needed for programs with large heaps. The collector -can also run in a "generational" mode, in which it usually attempts to -collect only objects allocated since the last garbage collection. -Furthermore, in this mode, garbage collections run mostly incrementally, -with a small amount of work performed in response to each of a large number of -GC_malloc requests. - -This mode is enabled by a call to GC_enable_incremental(). - -Incremental and generational collection is effective in reducing -pause times only if the collector has some way to tell which objects -or pages have been recently modified. The collector uses two sources -of information: - -1. Information provided by the VM system. This may be provided in -one of several forms. Under Solaris 2.X (and potentially under other -similar systems) information on dirty pages can be read from the -/proc file system. Under other systems (currently SunOS4.X) it is -possible to write-protect the heap, and catch the resulting faults. -On these systems we require that system calls writing to the heap -(other than read) be handled specially by client code. -See os_dep.c for details. - -2. Information supplied by the programmer. We define "stubborn" -objects to be objects that are rarely changed. Such an object -can be allocated (and enabled for writing) with GC_malloc_stubborn. -Once it has been initialized, the collector should be informed with -a call to GC_end_stubborn_change. Subsequent writes that store -pointers into the object must be preceded by a call to -GC_change_stubborn. - -This mechanism performs best for objects that are written only for -initialization, and such that only one stubborn object is writable -at once. It is typically not worth using for short-lived -objects. Stubborn objects are treated less efficiently than pointerfree -(atomic) objects. - -A rough rule of thumb is that, in the absence of VM information, garbage -collection pauses are proportional to the amount of pointerful storage -plus the amount of modified "stubborn" storage that is reachable during -the collection. - -Initial allocation of stubborn objects takes longer than allocation -of other objects, since other data structures need to be maintained. - -We recommend against random use of stubborn objects in client -code, since bugs caused by inappropriate writes to stubborn objects -are likely to be very infrequently observed and hard to trace. -However, their use may be appropriate in a few carefully written -library routines that do not make the objects themselves available -for writing by client code. - - -BUGS: - - Any memory that does not have a recognizable pointer to it will be -reclaimed. Exclusive-or'ing forward and backward links in a list -doesn't cut it. - Some C optimizers may lose the last undisguised pointer to a memory -object as a consequence of clever optimizations. This has almost -never been observed in practice. Send mail to boehm@acm.org -for suggestions on how to fix your compiler. - This is not a real-time collector. In the standard configuration, -percentage of time required for collection should be constant across -heap sizes. But collection pauses will increase for larger heaps. -(On SPARCstation 2s collection times will be on the order of 300 msecs -per MB of accessible memory that needs to be scanned. Your mileage -may vary.) The incremental/generational collection facility helps, -but is portable only if "stubborn" allocation is used. - Please address bug reports to boehm@acm.org. If you are -contemplating a major addition, you might also send mail to ask whether -it's already been done (or whether we tried and discarded it). - diff --git a/gc/doc/README.DGUX386 b/gc/doc/README.DGUX386 deleted file mode 100644 index 9d6d847..0000000 --- a/gc/doc/README.DGUX386 +++ /dev/null @@ -1,215 +0,0 @@ - Garbage Collector (parallel iversion) for ix86 DG/UX Release R4.20MU07 - - - *READ* the file README.QUICK. - - You need the GCC-3.0.3 rev (DG/UX) compiler to build this tree. - This compiler has the new "dgux386" threads package implemented. - It also supports the switch "-pthread" needed to link correctly - the DG/UX's -lrte -lthread with -lgcc and the system's -lc. - Finally we support parralleli-mark for the SMP DG/UX machines. - To build the garbage collector do: - - ./configure --enable-parallel-mark - make - make gctest - - Before you run "gctest" you need to set your LD_LIBRARY_PATH - correctly so that "gctest" can find the shared library libgc. - Alternatively you can do a configuration - - ./configure --enable-parallel-mark --disable-shared - - to build only the static version of libgc. - - To enable debugging messages please do: - 1) Add the "--enable-full-debug" flag during configuration. - 2) Edit the file linux-threads.c and uncommnect the line: - - /* #define DEBUG_THREADS 1 */ to ---> - - #define DEBUG_THREADS 1 - - Then give "make" as usual. - - In a machine with 4 CPUs (my own machine) the option parallel - mark (aka --enable-parallel-mark) makes a BIG difference. - - Takis Psarogiannakopoulos - University of Cambridge - Centre for Mathematical Sciences - Department of Pure Mathematics - Wilberforce Road - Cambridge CB3 0WB ,UK , <takis@XFree86.Org> - January 2002 - - -Note (HB): - The integration of this patch is currently not complete. - The following patches against 6.1alpha3 where hard to move - to alpha4, and are not integrated. There may also be minor - problems with stylistic corrections made by me. - - ---- ltconfig.ORIG Mon Jan 28 20:22:18 2002 -+++ ltconfig Mon Jan 28 20:44:00 2002 -@@ -689,6 +689,11 @@ - pic_flag=-Kconform_pic - fi - ;; -+ dgux*) -+ pic_flag='-fPIC' -+ link_static='-Bstatic' -+ wl='-Wl,' -+ ;; - *) - pic_flag='-fPIC' - ;; -@@ -718,6 +723,12 @@ - # We can build DLLs from non-PIC. - ;; - -+ dgux*) -+ pic_flag='-KPIC' -+ link_static='-Bstatic' -+ wl='-Wl,' -+ ;; -+ - osf3* | osf4* | osf5*) - # All OSF/1 code is PIC. - wl='-Wl,' -@@ -1154,6 +1165,22 @@ - fi - ;; - -+ dgux*) -+ ld_shlibs=yes -+ # For both C/C++ ommit the deplibs. This is because we relying on the fact -+ # that compilation of execitables will put them in correct order -+ # in any case and sometimes are wrong when listed as deplibs (or missing some deplibs) -+ # However when GNU ld and --whole-archive needs to be used we have the problem -+ # that if the -fPIC *_s.a archive is linked through deplibs list we ommiting crucial -+ # .lo/.o files from the created shared lib. This I think is not the case here. -+ archive_cmds='$CC -shared -h $soname -o $lib $libobjs $linkopts' -+ thread_safe_flag_spec='-pthread' -+ wlarc= -+ hardcode_libdir_flag_spec='-L$libdir' -+ hardcode_shlibpath_var=no -+ ac_cv_archive_cmds_needs_lc=no -+ ;; -+ - cygwin* | mingw*) - # hardcode_libdir_flag_spec is actually meaningless, as there is - # no search path for DLLs. -@@ -1497,7 +1524,7 @@ - ;; - - dgux*) -- archive_cmds='$LD -G -h $soname -o $lib $libobjs $deplibs $linkopts' -+ archive_cmds='$CC -shared -h $soname -o $lib $libobjs $linkopts' - hardcode_libdir_flag_spec='-L$libdir' - hardcode_shlibpath_var=no - ;; -@@ -2092,12 +2119,17 @@ - ;; - - dgux*) -- version_type=linux -+ version_type=dgux - need_lib_prefix=no - need_version=no -- library_names_spec='${libname}${release}.so$versuffix ${libname}${release}.so$major $libname.so' -- soname_spec='${libname}${release}.so$major' -+ library_names_spec='$libname.so$versuffix' -+ soname_spec='$libname.so$versuffix' - shlibpath_var=LD_LIBRARY_PATH -+ thread_safe_flag_spec='-pthread' -+ wlarc= -+ hardcode_libdir_flag_spec='-L$libdir' -+ hardcode_shlibpath_var=no -+ ac_cv_archive_cmds_needs_lc=no - ;; - - sysv4*MP*) - - ---- ltmain.sh.ORIG Mon Jan 28 20:31:18 2002 -+++ ltmain.sh Tue Jan 29 00:11:29 2002 -@@ -1072,11 +1072,38 @@ - esac - ;; - -+ -thread*) -+ # DG/UX GCC 2.95.x, 3.x.x rev (DG/UX) links -lthread -+ # with the switch -threads -+ if test "$arg" = "-threads"; then -+ case "$host" in -+ i[3456]86-*-dgux*) -+ deplibs="$deplibs $arg" -+ continue -+ ;; -+ esac -+ fi -+ ;; -+ -+ -pthread*) -+ # DG/UX GCC 2.95.x, 3.x.x rev (DG/UX) links -lthread -+ # with the switch -pthread -+ if test "$arg" = "-pthread"; then -+ case "$host" in -+ i[3456]86-*-dgux*) -+ deplibs="$deplibs $arg" -+ continue -+ ;; -+ esac -+ fi -+ ;; -+ - -l*) - if test "$arg" = "-lc"; then - case "$host" in -- *-*-cygwin* | *-*-mingw* | *-*-os2* | *-*-beos*) -+ *-*-cygwin* | *-*-mingw* | *-*-os2* | *-*-beos* | i[3456]86-*-dgux*) - # These systems don't actually have c library (as such) -+ # It is wrong in DG/UX to add -lc when creating shared/dynamic objs/libs - continue - ;; - esac -@@ -1248,6 +1275,12 @@ - temp_deplibs= - for deplib in $dependency_libs; do - case "$deplib" in -+ -thread*) -+ temp_deplibs="$temp_deplibs $deplib" -+ ;; -+ -pthread) -+ temp_deplibs="$temp_deplibs $deplib" -+ ;; - -R*) temp_xrpath=`$echo "X$deplib" | $Xsed -e 's/^-R//'` - case " $rpath $xrpath " in - *" $temp_xrpath "*) ;; -@@ -1709,6 +1742,13 @@ - done - ;; - -+ dgux) -+ # Leave mostly blank for DG/UX -+ major= -+ versuffix=".$current.$revision"; -+ verstring= -+ ;; -+ - linux) - major=.`expr $current - $age` - versuffix="$major.$age.$revision" -@@ -1792,8 +1832,9 @@ - - dependency_libs="$deplibs" - case "$host" in -- *-*-cygwin* | *-*-mingw* | *-*-os2* | *-*-beos*) -+ *-*-cygwin* | *-*-mingw* | *-*-os2* | *-*-beos* | i[3456]86-*-dgux*) - # these systems don't actually have a c library (as such)! -+ # It is wrong in DG/UX to add -lc when creating shared/dynamic objs/libs - ;; - *) - # Add libc to deplibs on all other systems. diff --git a/gc/doc/README.Mac b/gc/doc/README.Mac deleted file mode 100644 index 04f4682..0000000 --- a/gc/doc/README.Mac +++ /dev/null @@ -1,385 +0,0 @@ -Patrick Beard's Notes for building GC v4.12 with CodeWarrior Pro 2: ----------------------------------------------------------------------------- -The current build environment for the collector is CodeWarrior Pro 2. -Projects for CodeWarrior Pro 2 (and for quite a few older versions) -are distributed in the file Mac_projects.sit.hqx. The project file -:Mac_projects:gc.prj builds static library versions of the collector. -:Mac_projects:gctest.prj builds the GC test suite. - -Configuring the collector is still done by editing the files -:Mac_files:MacOS_config.h and :Mac_files:MacOS_Test_config.h. - -Lars Farm's suggestions on building the collector: ----------------------------------------------------------------------------- -Garbage Collection on MacOS - a manual 'MakeFile' -------------------------------------------------- - -Project files and IDE's are great on the Macintosh, but they do have -problems when used as distribution media. This note tries to provide -porting instructions in pure TEXT form to avoid those problems. A manual -'makefile' if you like. - - GC version: 4.12a2 - Codewarrior: CWPro1 - date: 18 July 1997 - -The notes may or may not apply to earlier or later versions of the -GC/CWPro. Actually, they do apply to earlier versions of both except that -until recently a project could only build one target so each target was a -separate project. The notes will most likely apply to future versions too. -Possibly with minor tweaks. - -This is just to record my experiences. These notes do not mean I now -provide a supported port of the GC to MacOS. It works for me. If it works -for you, great. If it doesn't, sorry, try again...;-) Still, if you find -errors, please let me know. - - mailto: lars.farm@ite.mh.se - - address: Lars Farm - Krönvägen 33b - 856 44 Sundsvall - Sweden - -Porting to MacOS is a bit more complex than it first seems. Which MacOS? -68K/PowerPC? Which compiler? Each supports both 68K and PowerPC and offer a -large number of (unique to each environment) compiler settings. Each -combination of compiler/68K/PPC/settings require a unique combination of -standard libraries. And the IDE's does not select them for you. They don't -even check that the library is built with compatible setting and this is -the major source of problems when porting the GC (and otherwise too). - -You will have to make choices when you configure the GC. I've made some -choices here, but there are other combinations of settings and #defines -that work too. - -As for target settings the major obstacles may be: -- 68K Processor: check "4-byte Ints". -- PPC Processor: uncheck "Store Static Data in TOC". - -What you need to do: -=================== - -1) Build the GC as a library -2) Test that the library works with 'test.c'. -3) Test that the C++ interface 'gc_cpp.cc/h' works with 'test_cpp.cc'. - -1) The Libraries: -================= -I made one project with four targets (68K/PPC tempmem or appheap). One target -will suffice if you're able to decide which one you want. I wasn't... - -Codewarrior allows a large number of compiler/linker settings. I used these: - -Settings shared by all targets: ------------------------------- -o Access Paths: - - User Paths: the GC folder - - System Paths: {Compiler}:Metrowerks Standard Library: - {Compiler}:MacOS Support:Headers: - {Compiler}:MacOS Support:MacHeaders: -o C/C++ language: - - inlining: normal - - direct to SOM: off - - enable/check: exceptions, RTTI, bool (and if you like pool strings) - -PowerPC target settings ------------------------ -o Target Settings: - - name of target - - MacOS PPC Linker -o PPC Target - - name of library -o C/C++ language - - prefix file as described below -o PPC Processor - - Struct Alignment: PowerPC - - uncheck "Store Static Data in TOC" -- important! - I don't think the others matter, I use full optimization and its ok -o PPC Linker - - Factory Settings (SYM file with full paths, faster linking, dead-strip - static init, Main: __start) - - -68K target settings -------------------- -o Target Settings: - - name of target - - MacOS 68K Linker -o 68K Target - - name of library - - A5 relative data -o C/C++ language - - prefix file as described below -o 68K Processor - - Code model: smart - - Struct alignment: 68K - - FP: SANE - - enable 4-Byte Ints -- important! - I don't think the others matter. I selected... - - enable: 68020 - - enable: global register allocation -o IR Optimizer - - enable: Optimize Space, Optimize Speed - I suppose the others would work too, but haven't tried... -o 68K Linker - - Factory Settings (New Style MacsBug,SYM file with full paths, - A6 Frames, fast link, Merge compiler glue into segment 1, - dead-strip static init) - -Prefix Files to configure the GC sources ----------------------------------------- -The Codewarrior equivalent of commandline compilers -DNAME=X is to use -prefix-files. A TEXT file that is automatically #included before the first byte -of every source file. I used these: - ----- ( cut here ) ---- gc_prefix_tempmem.h -- 68K and PPC ----- - #include "gc_prefix_common.h" - #undef USE_TEMPORARY_MEMORY - #define USE_TEMPORARY_MEMORY ----- ( cut here ) ---- gc_prefix_appmem.h -- 68K and PPC ----- - #include "gc_prefix_common.h" - #undef USE_TEMPORARY_MEMORY -// #define USE_TEMPORARY_MEMORY - ----- ( cut here ) ---- gc_prefix_common.h -------------------- -// gc_prefix_common.h -// ------------------ -// Codewarrior prefix file to configure the GC libraries -// -// prefix files are the Codewarrior equivalent of the -// command line option -Dname=x frequently seen in makefiles - -#if !__MWERKS__ - #error only tried this with Codewarrior -#endif - -#if macintosh - #define MSL_USE_PRECOMPILED_HEADERS 0 - #include <ansi_prefix.mac.h> - #ifndef __STDC__ - #define __STDC__ 0 - #endif - - // See list of #defines to configure the library in: 'MakeFile' - // see also README - - #define SILENT // no collection messages. In case - // of trouble you might want this off - #define ALL_INTERIOR_POINTERS // follows interior pointers. -//#define DONT_ADD_BYTE_AT_END // disables the padding if defined. -//#define SMALL_CONFIG // whether to use a smaller heap. - #define NO_SIGNALS // signals aren't real on the Macintosh. - #define ATOMIC_UNCOLLECTABLE // GC_malloc_atomic_uncollectable() - - // define either or none as per personal preference - // used in malloc.c - #define REDIRECT_MALLOC GC_malloc -//#define REDIRECT_MALLOC GC_malloc_uncollectable - // if REDIRECT_MALLOC is #defined make sure that the GC library - // is listed before the ANSI/ISO libs in the Codewarrior - // 'Link order' panel -//#define IGNORE_FREE - - // mac specific configs -//#define USE_TEMPORARY_MEMORY // use Macintosh temporary memory. -//#define SHARED_LIBRARY_BUILD // build for use in a shared library. - -#else - // could build Win32 here too, or in the future - // Rhapsody PPC-mach, Rhapsody PPC-MacOS, - // Rhapsody Intel-mach, Rhapsody Intel-Win32,... - // ... ugh this will get messy ... -#endif - -// make sure ints are at least 32-bit -// ( could be set to 16-bit by compiler settings (68K) ) - -struct gc_private_assert_intsize_{ char x[ sizeof(int)>=4 ? 1 : 0 ]; }; - -#if __powerc - #if __option(toc_data) - #error turn off "store static data in TOC" when using GC - // ... or find a way to add TOC to the root set...(?) - #endif -#endif ----- ( cut here ) ---- end of gc_prefix_common.h ----------------- - -Files to build the GC libraries: --------------------------------- - allchblk.c - alloc.c - blacklst.c - checksums.c - dbg_mlc.c - finalize.c - headers.c - mach_dep.c - MacOS.c -- contains MacOS code - malloc.c - mallocx.c - mark.c - mark_rts.c - misc.c - new_hblk.c - obj_map.c - os_dep.c -- contains MacOS code - ptr_chck.c - reclaim.c - stubborn.c - typd_mlc.c - gc++.cc -- this is 'gc_cpp.cc' with less 'inline' and - -- throw std::bad_alloc when out of memory - -- gc_cpp.cc works just fine too - -2) Test that the library works with 'test.c'. -============================================= - -The test app is just an ordinary ANSI-C console app. Make sure settings -match the library you're testing. - -Files ------ - test.c - the GC library to test -- link order before ANSI libs - suitable Mac+ANSI libraries - -prefix: ------- ----- ( cut here ) ---- gc_prefix_testlib.h -- all libs ----- -#define MSL_USE_PRECOMPILED_HEADERS 0 -#include <ansi_prefix.mac.h> -#undef NDEBUG - -#define ALL_INTERIOR_POINTERS /* for GC_priv.h */ ----- ( cut here ) ---- - -3) Test that the C++ interface 'gc_cpp.cc/h' works with 'test_cpp.cc'. - -The test app is just an ordinary ANSI-C console app. Make sure settings match -the library you're testing. - -Files ------ - test_cpp.cc - the GC library to test -- link order before ANSI libs - suitable Mac+ANSI libraries - -prefix: ------- -same as for test.c - -For convenience I used one test-project with several targets so that all -test apps are build at once. Two for each library to test: test.c and -gc_app.cc. When I was satisfied that the libraries were ok. I put the -libraries + gc.h + the c++ interface-file in a folder that I then put into -the MSL hierarchy so that I don't have to alter access-paths in projects -that use the GC. - -After that, just add the proper GC library to your project and the GC is in -action! malloc will call GC_malloc and free GC_free, new/delete too. You -don't have to call free or delete. You may have to be a bit cautious about -delete if you're freeing other resources than RAM. See gc_cpp.h. You can -also keep coding as always with delete/free. That works too. If you want, -"include <gc.h> and tweak it's use a bit. - -Symantec SPM -============ -It has been a while since I tried the GC in SPM, but I think that the above -instructions should be sufficient to guide you through in SPM too. SPM -needs to know where the global data is. Use the files 'datastart.c' and -'dataend.c'. Put 'datastart.c' at the top of your project and 'dataend.c' -at the bottom of your project so that all data is surrounded. This is not -needed in Codewarrior because it provides intrinsic variables -__datastart__, __data_end__ that wraps all globals. - -Source Changes (GC 4.12a2) -========================== -Very few. Just one tiny in the GC, not strictly needed. -- MacOS.c line 131 in routine GC_MacFreeTemporaryMemory() - change # if !defined(SHARED_LIBRARY_BUILD) - to # if !defined(SILENT) && !defined(SHARED_LIBRARY_BUILD) - To turn off a message when the application quits (actually, I faked - this change by #defining SHARED_LIBRARY_BUILD in a statically linked - library for more than a year without ill effects but perhaps this is - better). - -- test_cpp.cc - made the first lines of main() look like this: - ------------ - int main( int argc, char* argv[] ) { - #endif - #if macintosh // MacOS - char* argv_[] = {"test_cpp","10"}; // doesn't - argv=argv_; // have a - argc = sizeof(argv_)/sizeof(argv_[0]); // commandline - #endif // - - int i, iters, n; - # ifndef __GNUC__ - alloc dummy_to_fool_the_compiler_into_doing_things_it_currently_cant_handle; - ------------ - -- config.h [now gcconfig.h] - __MWERKS__ does not have to mean MACOS. You can use Codewarrior to - build a Win32 or BeOS library and soon a Rhapsody library. You may - have to change that #if... - - - - It worked for me, hope it works for you. - - Lars Farm - 18 July 1997 ----------------------------------------------------------------------------- - - -Patrick Beard's instructions (may be dated): - -v4.3 of the collector now runs under Symantec C++/THINK C v7.0.4, and -Metrowerks C/C++ v4.5 both 68K and PowerPC. Project files are provided -to build and test the collector under both development systems. - -Configuration -------------- - -To configure the collector, under both development systems, a prefix file -is used to set preprocessor directives. This file is called "MacOS_config.h". -Also to test the collector, "MacOS_Test_config.h" is provided. - -Testing -------- - -To test the collector (always a good idea), build one of the gctest projects, -gctest.¹ (Symantec C++/THINK C), mw/gctest.68K.¹, or mw/gctest.PPC.¹. The -test will ask you how many times to run; 1 should be sufficient. - -Building --------- - -For your convenience project files for the major Macintosh development -systems are provided. - -For Symantec C++/THINK C, you must build the two projects gclib-1.¹ and -gclib-2.¹. It has to be split up because the collector has more than 32k -of static data and no library can have more than this in the Symantec -environment. (Future versions will probably fix this.) - -For Metrowerks C/C++ 4.5 you build gc.68K.¹/gc.PPC.¹ and the result will -be a library called gc.68K.lib/gc.PPC.lib. - -Using ------ - -Under Symantec C++/THINK C, you can just add the gclib-1.¹ and gclib-2.¹ -projects to your own project. Under Metrowerks, you add gc.68K.lib or -gc.PPC.lib and two additional files. You add the files called datastart.c -and dataend.c to your project, bracketing all files that use the collector. -See mw/gctest.¹ for an example. - -Include the projects/libraries you built above into your own project, -#include "gc.h", and call GC_malloc. You don't have to call GC_free. - - -Patrick C. Beard -January 4, 1995 diff --git a/gc/doc/README.MacOSX b/gc/doc/README.MacOSX deleted file mode 100644 index 2abf0b4..0000000 --- a/gc/doc/README.MacOSX +++ /dev/null @@ -1,27 +0,0 @@ -While the GC should work on MacOS X Server, MacOS X and Darwin, I only tested -it on MacOS X Server. -I've added a PPC assembly version of GC_push_regs(), thus the setjmp() hack is -no longer necessary. Incremental collection is supported via mprotect/signal. -The current solution isn't really optimal because the signal handler must decode -the faulting PPC machine instruction in order to find the correct heap address. -Further, it must poke around in the register state which the kernel saved away -in some obscure register state structure before it calls the signal handler - -needless to say the layout of this structure is no where documented. -Threads and dynamic libraries are not yet supported (adding dynamic library -support via the low-level dyld API shouldn't be that hard). - -The original MacOS X port was brought to you by Andrew Stone. - - -June, 1 2000 - -Dietmar Planitzer -dave.pl@ping.at - -Note from Andrew Begel: - -One more fix to enable gc.a to link successfully into a shared library for -MacOS X. You have to add -fno-common to the CFLAGS in the Makefile. MacOSX -disallows common symbols in anything that eventually finds its way into a -shared library. (I don't completely understand why, but -fno-common seems to -work and doesn't mess up the garbage collector's functionality). diff --git a/gc/doc/README.OS2 b/gc/doc/README.OS2 deleted file mode 100644 index 5345bbd..0000000 --- a/gc/doc/README.OS2 +++ /dev/null @@ -1,6 +0,0 @@ -The code assumes static linking, and a single thread. The editor de has -not been ported. The cord test program has. The supplied OS2_MAKEFILE -assumes the IBM C Set/2 environment, but the code shouldn't. - -Since we haven't figured out hoe to do perform partial links or to build static -libraries, clients currently need to link against a long list of executables. diff --git a/gc/doc/README.amiga b/gc/doc/README.amiga deleted file mode 100644 index 730dce3..0000000 --- a/gc/doc/README.amiga +++ /dev/null @@ -1,322 +0,0 @@ -=========================================================================== - Kjetil S. Matheussen's notes (28-11-2000) -=========================================================================== -Compiles under SAS/C again. Should allso still compile under other -amiga compilers without big changes. I haven't checked if it still -works under gcc, because I don't have gcc for amiga. But I have -updated 'Makefile', and hope it compiles fine. - - -WHATS NEW: - -1. - Made a pretty big effort in preventing GCs allocating-functions from returning - chip-mem. - - The lower part of the new file AmigaOS.c does this in various ways, mainly by - wrapping GC_malloc, GC_malloc_atomic, GC_malloc_uncollectable, - GC_malloc_atomic_uncollectable, GC_malloc_stubborn, GC_malloc_ignore_off_page - and GC_malloc_atomic_ignore_off_page. GC_realloc is allso wrapped, but - doesn't do the same effort in preventing to return chip-mem. - Other allocating-functions (f.ex. GC_*_typed_) can probably be - used without any problems, but beware that the warn hook will not be called. - In case of problems, don't define GC_AMIGA_FASTALLOC. - - Programs using more time actually using the memory allocated - (instead of just allocate and free rapidly) have - the most to earn on this, but even gctest now normally runs twice - as fast and uses less memory, on my poor 8MB machine. - - The changes have only effect when there is no more - fast-mem left. But with the way GC works, it - could happen quite often. Beware that an atexit handler had to be added, - so using the abort() function will make a big memory-loss. - If you absolutely must call abort() instead of exit(), try calling - the GC_amiga_free_all_mem function before abort(). - - New amiga-spesific compilation flags: - - GC_AMIGA_FASTALLOC - By NOT defining this option, GC will work like before, - it will not try to force fast-mem out of the OS, and - it will use normal calloc for allocation, and the rest - of the following flags will have no effect. - - GC_AMIGA_ONLYFAST - Makes GC never to return chip-mem. GC_AMIGA_RETRY have - no effect if this flag is set. - - GC_AMIGA_GC - If gc returns NULL, do a GC_gcollect, and try again. This - usually is a success with the standard GC configuration. - It is allso the most important flag to set to prevent - GC from returning chip-mem. Beware that it slows down a lot - when a program is rapidly allocating/deallocating when - theres either very little fast-memory left or verly little - chip-memory left. Its not a very common situation, but gctest - sometimes (very rare) use many minutes because of this. - - GC_AMIGA_RETRY - If gc succeed allocating memory, but it is chip-mem, - try again and see if it is fast-mem. Most of the time, - it will actually return fast-mem for the second try. - I have set max number of retries to 9 or size/5000. You - can change this if you like. (see GC_amiga_rec_alloc()) - - GC_AMIGA_PRINTSTATS - Gather some statistics during the execution of a - program, and prints out the info when the atexit-handler - is called. - - My reccomendation is to set all this flags, except GC_AMIGA_PRINTSTATS and - GC_AMIGA_ONLYFAST. - - If your program demands high response-time, you should - not define GC_AMIGA_GC, and possible allso define GC_AMIGA_ONLYFAST. - GC_AMIGA_RETRY does not seem to slow down much. - - Allso, when compiling up programs, and GC_AMIGA_FASTALLOC was not defined when - compilling gc, you can define GC_AMIGA_MAKINGLIB to avoid having these allocation- - functions wrapped. (see gc.h) - - Note that GC_realloc must not be called before any of - the other above mentioned allocating-functions have been called. (shouldn't be - any programs doing so either, I hope). - - Another note. The allocation-function is wrapped when defining - GC_AMIGA_FASTALLOC by letting the function go thru the new - GC_amiga_allocwrapper_do function-pointer (see gc.h). Means that - sending function-pointers, such as GC_malloc, GC_malloc_atomic, etc., - for later to be called like f.ex this, (*GC_malloc_functionpointer)(size), - will not wrap the function. This is normally not a big problem, unless - all allocation function is called like this, which will cause the - atexit un-allocating function never to be called. Then you either - have to manually add the atexit handler, or call the allocation- - functions function-pointer functions like this; - (*GC_amiga_allocwrapper_do)(size,GC_malloc_functionpointer). - There are probably better ways this problem could be handled, unfortunately, - I didn't find any without rewriting or replacing a lot of the GC-code, which - I really didn't want to. (Making new GC_malloc_* functions, and just - define f.ex GC_malloc as GC_amiga_malloc should allso work). - - - New amiga-spesific function: - - void GC_amiga_set_toany(void (*func)(void)); - - 'func' is a function that will be called right before gc has to change - allocation-method from MEMF_FAST to MEMF_ANY. Ie. when it is likely - it will return chip-mem. - - -2. A few small compiler-spesific additions to make it compile with SAS/C again. - -3. Updated and rewritten the smakefile, so that it works again and that - the "unnecesarry" 'SCOPTIONS' files could be removed. Allso included - the cord-smakefile stuff in the main smakefile, so that the cord smakefile - could be removed too. By writing smake -f Smakefile.smk, both gc.lib and - cord.lib will be made. - - - -STILL MISSING: - -Programs can not be started from workbench, at least not for SAS/C. (Martin -Tauchmanns note about that it now works with workbench is definitely wrong -when concerning SAS/C). I guess it works if you use the old "#if 0'ed"-code, -but I haven't tested it. I think the reason for MT to replace the -"#if 0'ed"-code was only because it was a bit to SAS/C-spesific. But I -don't know. An iconx-script solves this problem anyway. - - -BEWARE! - --To run gctest, set the stack to around 200000 bytes first. --SAS/C-spesific: cord will crash if you compile gc.lib with - either parm=reg or parm=both. (missing legal prototypes for - function-pointers someplace is the reason I guess.). - - -tested with software: Radium, http://www.stud.ifi.uio.no/~ksvalast/radium/ - -tested with hardware: MC68060 - - --ksvalast@ifi.uio.no - - -=========================================================================== - Martin Tauchmann's notes (1-Apr-99) -=========================================================================== - -Works now, also with the GNU-C compiler V2.7.2.1. <ftp://ftp.unina.it/pub/amiga/geekgadgets/amiga/m68k/snapshots/971125/amiga-bin/> -Modify the `Makefile` -CC=cc $(ABI_FLAG) -to -CC=gcc $(ABI_FLAG) - -TECHNICAL NOTES - -- `GC_get_stack_base()`, `GC_register_data_segments()` works now with every - C compiler; also Workbench. - -- Removed AMIGA_SKIP_SEG, but the Code-Segment must not be scanned by GC. - - -PROBLEMS -- When the Linker, does`t merge all Code-Segments to an single one. LD of GCC - do it always. - -- With ixemul.library V47.3, when an GC program launched from another program - (example: `Make` or `if_mach M68K AMIGA gctest`), `GC_register_data_segments()` - found the Segment-List of the caller program. - Can be fixed, if the run-time initialization code (for C programs, usually *crt0*) - support `__data` and `__bss`. - -- PowerPC Amiga currently not supported. - -- Dynamic libraries (dyn_load.c) not supported. - - -TESTED WITH SOFTWARE - -`Optimized Oberon 2 C` (oo2c) <http://cognac.informatik.uni-kl.de/download/index.html> - - -TESTED WITH HARDWARE - -MC68030 - - -CONTACT - -Please, contact me at <martintauchmann@bigfoot.com>, when you change the -Amiga port. <http://martintauchmann.home.pages.de> - -=========================================================================== - Michel Schinz's notes -=========================================================================== -WHO DID WHAT - -The original Amiga port was made by Jesper Peterson. I (Michel Schinz) -modified it slightly to reflect the changes made in the new official -distributions, and to take advantage of the new SAS/C 6.x features. I also -created a makefile to compile the "cord" package (see the cord -subdirectory). - -TECHNICAL NOTES - -In addition to Jesper's notes, I have the following to say: - -- Starting with version 4.3, gctest checks to see if the code segment is - added to the root set or not, and complains if it is. Previous versions - of this Amiga port added the code segment to the root set, so I tried to - fix that. The only problem is that, as far as I know, it is impossible to - know which segments are code segments and which are data segments (there - are indeed solutions to this problem, like scanning the program on disk - or patch the LoadSeg functions, but they are rather complicated). The - solution I have chosen (see os_dep.c) is to test whether the program - counter is in the segment we are about to add to the root set, and if it - is, to skip the segment. The problems are that this solution is rather - awkward and that it works only for one code segment. This means that if - your program has more than one code segment, all of them but one will be - added to the root set. This isn't a big problem in fact, since the - collector will continue to work correctly, but it may be slower. - - Anyway, the code which decides whether to skip a segment or not can be - removed simply by not defining AMIGA_SKIP_SEG. But notice that if you do - so, gctest will complain (it will say that "GC_is_visible produced wrong - failure indication"). However, it may be useful if you happen to have - pointers stored in a code segment (you really shouldn't). - - If anyone has a good solution to the problem of finding, when a program - is loaded in memory, whether a segment is a code or a data segment, - please let me know. - -PROBLEMS - -If you have any problem with this version, please contact me at -schinz@alphanet.ch (but do *not* send long files, since we pay for -every mail!). - -=========================================================================== - Jesper Peterson's notes -=========================================================================== - -ADDITIONAL NOTES FOR AMIGA PORT - -These notes assume some familiarity with Amiga internals. - -WHY I PORTED TO THE AMIGA - -The sole reason why I made this port was as a first step in getting -the Sather(*) language on the Amiga. A port of this language will -be done as soon as the Sather 1.0 sources are made available to me. -Given this motivation, the garbage collection (GC) port is rather -minimal. - -(*) For information on Sather read the comp.lang.sather newsgroup. - -LIMITATIONS - -This port assumes that the startup code linked with target programs -is that supplied with SAS/C versions 6.0 or later. This allows -assumptions to be made about where to find the stack base pointer -and data segments when programs are run from WorkBench, as opposed -to running from the CLI. The compiler dependent code is all in the -GC_get_stack_base() and GC_register_data_segments() functions, but -may spread as I add Amiga specific features. - -Given that SAS/C was assumed, the port is set up to be built with -"smake" using the "SMakefile". Compiler options in "SCoptions" can -be set with "scopts" program. Both "smake" and "scopts" are part of -the SAS/C commercial development system. - -In keeping with the porting philosophy outlined above, this port -will not behave well with Amiga specific code. Especially not inter- -process comms via messages, and setting up public structures like -Intuition objects or anything else in the system lists. For the -time being the use of this library is limited to single threaded -ANSI/POSIX compliant or near-complient code. (ie. Stick to stdio -for now). Given this limitation there is currently no mechanism for -allocating "CHIP" or "PUBLIC" memory under the garbage collector. -I'll add this after giving it considerable thought. The major -problem is the entire physical address space may have to me scanned, -since there is no telling who we may have passed memory to. - -If you allocate your own stack in client code, you will have to -assign the pointer plus stack size to GC_stackbottom. - -The initial stack size of the target program can be compiled in by -setting the __stack symbol (see SAS documentaion). It can be over- -ridden from the CLI by running the AmigaDOS "stack" program, or from -the WorkBench by setting the stack size in the tool types window. - -SAS/C COMPILER OPTIONS (SCoptions) - -You may wish to check the "CPU" code option is appropriate for your -intended target system. - -Under no circumstances set the "StackExtend" code option in either -compiling the library or *ANY* client code. - -All benign compiler warnings have been suppressed. These mainly -involve lack of prototypes in the code, and dead assignments -detected by the optimizer. - -THE GOOD NEWS - -The library as it stands is compatible with the GigaMem commercial -virtual memory software, and probably similar PD software. - -The performance of "gctest" on an Amiga 2630 (68030 @ 25Mhz) -compares favourably with an HP9000 with similar architecture (a 325 -with a 68030 I think). - ------------------------------------------------------------------------ - -The Amiga port has been brought to you by: - -Jesper Peterson. - -jep@mtiame.mtia.oz.au (preferred, but 1 week turnaround) -jep@orca1.vic.design.telecom.au (that's orca<one>, 1 day turnaround) - -At least one of these addresses should be around for a while, even -though I don't work for either of the companies involved. - diff --git a/gc/doc/README.arm.cross b/gc/doc/README.arm.cross deleted file mode 100755 index 96744ed..0000000 --- a/gc/doc/README.arm.cross +++ /dev/null @@ -1,68 +0,0 @@ -From: Margaret Fleck - -Here's the key details of what worked for me, in case anyone else needs them. -There may well be better ways to do some of this, but .... - -- Margaret - - -The badge4 has a StrongArm-1110 processor and a StrongArm-1111 coprocessor. - -Assume that the garbage collector distribution is unpacked into /home/arm/gc6.0, -which is visible to both the ARM machine and a linux desktop (e.g. via NFS mounting). - -Assume that you have a file /home/arm/config.site with contents something like the -example attached below. Notice that our local ARM toolchain lives in -/skiff/local. - -Go to /home/arm/gc6.0 directory. Do - CONFIG_SITE=/home/arm/config.site ./configure --target=arm-linux ---prefix=/home/arm/gc6.0 - -On your desktop, do: - make - make install -The main garbage collector library should now be in ../gc6.0/lib/libgc.so. - -To test the garbage collector, first do the following on your desktop - make gctest - ./gctest -Then do the following on the ARM machine - cd .libs - ./lt-gctest - -Do not try to do "make test" (the usual way of running the test -program). This does not work and seems to erase some of the important -files. - -The gctest program claims to have succeeded. Haven't run any further tests -with it, though I'll be doing so in the near future. - -------------------------------- -# config.site for configure - -# Modified from the one provided by Bradley D. LaRonde -# Edited by Andrej Cedilnik <acedil1@csee.umbc.edu> -# Used some of solutions by Tilman Vogel <Tilman.Vogel@web.de> -# Ported for iPAQ Familiar by Oliver Kurth <oliver.kurth@innominate.com> -# Further modified by Margaret Fleck for the badge4 - -HOSTCC=gcc - -# Names of the cross-compilers -CC=/skiff/local/bin/arm-linux-gcc -CXX=/skiff/local/bin/arm-linux-gcc - -# The cross compiler specific options -CFLAGS="-O2 -fno-exceptions" -CXXFLAGS="-O2 -fno-exceptions" -CPPFLAGS="-O2 -fno-exceptions" -LDFLAGS="" - -# Some other programs -AR=/skiff/local/bin/arm-linux-ar -RANLIB=/skiff/local/bin/arm-linux-ranlib -NM=/skiff/local/bin/arm-linux-nm -ac_cv_path_NM=/skiff/local/bin/arm-linux-nm -ac_cv_func_setpgrp_void=yes -x_includes=/skiff/local/arm-linux/include/X11 -x_libraries=/skiff/local/arm-linux/lib/X11 diff --git a/gc/doc/README.autoconf b/gc/doc/README.autoconf deleted file mode 100644 index 53fcf5a..0000000 --- a/gc/doc/README.autoconf +++ /dev/null @@ -1,59 +0,0 @@ -As of GC6.0alpha8, we attempt to support GNU-style builds based on automake, -autoconf and libtool. This is based almost entirely on Tom Tromey's work -with gcj. - -To build and install libraries use - -configure; make; make install - -The advantages of this process are: - -1) It should eventually do a better job of automatically determining the -right compiler to use, etc. It probably already does in some cases. - -2) It tries to automatically set a good set of default GC parameters for -the platform (e.g. thread support). It provides an easier way to configure -some of the others. - -3) It integrates better with other projects using a GNU-style build process. - -4) It builds both dynamic and static libraries. - -The known disadvantages are: - -1) The build scripts are much more complex and harder to debug (though largely -standard). I don't understand them all, and there's probably lots of redundant -stuff. - -2) It probably doesn't work on all Un*x-like platforms yet. It probably will -never work on the rest. - -3) The scripts are not yet complete. Some of the standard GNU targets don't -yet work. (Corrections/additions are very welcome.) - -The distribution should contain all files needed to run "configure" and "make", -as well as the sources needed to regenerate the derived files. (If I missed -some, please let me know.) - -Note that the distribution comes with a "Makefile" which will be overwritten -by "configure" with one that is not at all equiavelent to the original. The -distribution contains a copy of the original "Makefile" in "Makefile.direct". - -Important options to configure: - - --prefix=PREFIX install architecture-independent files in PREFIX - [/usr/local] - --exec-prefix=EPREFIX install architecture-dependent files in EPREFIX - [same as prefix] - --enable-threads=TYPE choose threading package - --enable-parallel-mark parallelize marking and free list construction - --enable-full-debug include full support for pointer backtracing etc. - -Unless --prefix is set (or --exec-prefix or one of the more obscure options), -make install will install libgc.a and libgc.so in /usr/local/bin, which -would typically require the "make install" to be run as root. - -Most commonly --enable-threads=posix or will be needed. --enable-parallel-mark -is recommended for multiprocessors if it is supported on the platform. - - diff --git a/gc/doc/README.changes b/gc/doc/README.changes deleted file mode 100644 index 3b2925a..0000000 --- a/gc/doc/README.changes +++ /dev/null @@ -1,1653 +0,0 @@ -This is a rough history of garbage collector bugs and versions. - -This has been maintained with varying diligence over the years. - -I made an attempt to include recent contributors here. I apologize for any -omissions. - -------------------------- - - Version 1.3 and immediately preceding versions contained spurious -assembly language assignments to TMP_SP. Only the assignment in the PC/RT -code is necessary. On other machines, with certain compiler options, -the assignments can lead to an unsaved register being overwritten. -Known to cause problems under SunOS 3.5 WITHOUT the -O option. (With --O the compiler recognizes it as dead code. It probably shouldn't, -but that's another story.) - - Version 1.4 and earlier versions used compile time determined values -for the stack base. This no longer works on Sun 3s, since Sun 3/80s use -a different stack base. We now use a straightforward heuristic on all -machines on which it is known to work (incl. Sun 3s) and compile-time -determined values for the rest. There should really be library calls -to determine such values. - - Version 1.5 and earlier did not ensure 8 byte alignment for objects -allocated on a sparc based machine. - - Version 1.8 added ULTRIX support in gc_private.h. - - Version 1.9 fixed a major bug in gc_realloc. - - Version 2.0 introduced a consistent naming convention for collector -routines and added support for registering dynamic library data segments -in the standard mark_roots.c. Most of the data structures were revamped. -The treatment of interior pointers was completely changed. Finalization -was added. Support for locking was added. Object kinds were added. -We added a black listing facility to avoid allocating at addresses known -to occur as integers somewhere in the address space. Much of this -was accomplished by adapting ideas and code from the PCR collector. -The test program was changed and expanded. - - Version 2.1 was the first stable version since 1.9, and added support -for PPCR. - - Version 2.2 added debugging allocation, and fixed various bugs. Among them: -- GC_realloc could fail to extend the size of the object for certain large object sizes. -- A blatant subscript range error in GC_printf, which unfortunately - wasn't exercised on machines with sufficient stack alignment constraints. -- GC_register_displacement did the wrong thing if it was called after - any allocation had taken place. -- The leak finding code would eventually break after 2048 byte - byte objects leaked. -- interface.c didn't compile. -- The heap size remained much too small for large stacks. -- The stack clearing code behaved badly for large stacks, and perhaps - on HP/PA machines. - - Version 2.3 added ALL_INTERIOR_POINTERS and fixed the following bugs: -- Missing declaration of etext in the A/UX version. -- Some PCR root-finding problems. -- Blacklisting was not 100% effective, because the plausible future - heap bounds were being miscalculated. -- GC_realloc didn't handle out-of-memory correctly. -- GC_base could return a nonzero value for addresses inside free blocks. -- test.c wasn't really thread safe, and could erroneously report failure - in a multithreaded environment. (The locking primitives need to be - replaced for other threads packages.) -- GC_CONS was thoroughly broken. -- On a SPARC with dynamic linking, signals stayed diabled while the - client code was running. - (Thanks to Manuel Serrano at INRIA for reporting the last two.) - - Version 2.4 added GC_free_space_divisor as a tuning knob, added - support for OS/2 and linux, and fixed the following bugs: -- On machines with unaligned pointers (e.g. Sun 3), every 128th word could - fail to be considered for marking. -- Dynamic_load.c erroneously added 4 bytes to the length of the data and - bss sections of the dynamic library. This could result in a bad memory - reference if the actual length was a multiple of a page. (Observed on - Sun 3. Can probably also happen on a Sun 4.) - (Thanks to Robert Brazile for pointing out that the Sun 3 version - was broken. Dynamic library handling is still broken on Sun 3s - under 4.1.1U1, but apparently not 4.1.1. If you have such a machine, - use -Bstatic.) - - Version 2.5 fixed the following bugs: -- Removed an explicit call to exit(1) -- Fixed calls to GC_printf and GC_err_printf, so the correct number of - arguments are always supplied. The OS/2 C compiler gets confused if - the number of actuals and the number of formals differ. (ANSI C - doesn't require this to work. The ANSI sanctioned way of doing things - causes too many compatibility problems.) - - Version 3.0 added generational/incremental collection and stubborn - objects. - - Version 3.1 added the following features: -- A workaround for a SunOS 4.X SPARC C compiler - misfeature that caused problems when the collector was turned into - a dynamic library. -- A fix for a bug in GC_base that could result in a memory fault. -- A fix for a performance bug (and several other misfeatures) pointed - out by Dave Detlefs and Al Dosser. -- Use of dirty bit information for static data under Solaris 2.X. -- DEC Alpha/OSF1 support (thanks to Al Dosser). -- Incremental collection on more platforms. -- A more refined heap expansion policy. Less space usage by default. -- Various minor enhancements to reduce space usage, and to reduce - the amount of memory scanned by the collector. -- Uncollectable allocation without per object overhead. -- More conscientious handling of out-of-memory conditions. -- Fixed a bug in debugging stubborn allocation. -- Fixed a bug that resulted in occasional erroneous reporting of smashed - objects with debugging allocation. -- Fixed bogus leak reports of size 4096 blocks with FIND_LEAK. - - Version 3.2 fixed a serious and not entirely repeatable bug in - the incremental collector. It appeared only when dirty bit info - on the roots was available, which is normally only under Solaris. - It also added GC_general_register_disappearing_link, and some - testing code. Interface.c disappeared. - - Version 3.3 fixes several bugs and adds new ports: -- PCR-specific bugs. -- Missing locking in GC_free, redundant FASTUNLOCK - in GC_malloc_stubborn, and 2 bugs in - GC_unregister_disappearing_link. - All of the above were pointed out by Neil Sharman - (neil@cs.mu.oz.au). -- Common symbols allocated by the SunOS4.X dynamic loader - were not included in the root set. -- Bug in GC_finalize (reported by Brian Beuning and Al Dosser) -- Merged Amiga port from Jesper Peterson (untested) -- Merged NeXT port from Thomas Funke (significantly - modified and untested) - - Version 3.4: -- Fixed a performance bug in GC_realloc. -- Updated the amiga port. -- Added NetBSD and 386BSD ports. -- Added cord library. -- Added trivial performance enhancement for - ALL_INTERIOR_POINTERS. (Don't scan last word.) - - Version 3.5 -- Minor collections now mark from roots only once, if that - doesn't cause an excessive pause. -- The stack clearing heuristic was refined to prevent anomalies - with very heavily recursive programs and sparse stacks. -- Fixed a bug that prevented mark stack growth in some cases. - GC_objects_are_marked should be set to TRUE after a call - to GC_push_roots and as part of GC_push_marked, since - both can now set mark bits. I think this is only a performance - bug, but I wouldn't bet on it. It's certainly very hard to argue - that the old version was correct. -- Fixed an incremental collection bug that prevented it from - working at all when HBLKSIZE != getpagesize() -- Changed dynamic_loading.c to include gc_priv.h before testing - DYNAMIC_LOADING. SunOS dynamic library scanning - must have been broken in 3.4. -- Object size rounding now adapts to program behavior. -- Added a workaround (provided by Manuel Serrano and - colleagues) to a long-standing SunOS 4.X (and 3.X?) ld bug - that I had incorrectly assumed to have been squished. - The collector was broken if the text segment size was within - 32 bytes of a multiple of 8K bytes, and if the beginning of - the data segment contained interesting roots. The workaround - assumes a demand-loadable executable. The original may have - have "worked" in some other cases. -- Added dynamic library support under IRIX5. -- Added support for EMX under OS/2 (thanks to Ari Huttunen). - -Version 3.6: -- fixed a bug in the mark stack growth code that was introduced - in 3.4. -- fixed Makefile to work around DEC AXP compiler tail recursion - bug. - -Version 3.7: -- Added a workaround for an HP/UX compiler bug. -- Fixed another stack clearing performance bug. Reworked - that code once more. - -Version 4.0: -- Added support for Solaris threads (which was possible - only by reimplementing some fraction of Solaris threads, - since Sun doesn't currently make the thread debugging - interface available). -- Added non-threads win32 and win32S support. -- (Grudgingly, with suitable muttering of obscenities) renamed - files so that the collector distribution could live on a FAT - file system. Files that are guaranteed to be useless on - a PC still have long names. Gc_inline.h and gc_private.h - still exist, but now just include gc_inl.h and gc_priv.h. -- Fixed a really obscure bug in finalization that could cause - undetected mark stack overflows. (I would be surprised if - any real code ever tickled this one.) -- Changed finalization code to dynamically resize the hash - tables it maintains. (This probably does not matter for well- - -written code. It no doubt does for C++ code that overuses - destructors.) -- Added typed allocation primitives. Rewrote the marker to - accommodate them with more reasonable efficiency. This - change should also speed up marking for GC_malloc allocated - objects a little. See gc_typed.h for new primitives. -- Improved debugging facilities slightly. Allocation time - stack traces are now kept by default on SPARC/SUNOS4. - (Thanks to Scott Schwartz.) -- Added better support for small heap applications. -- Significantly extended cord package. Fixed a bug in the - implementation of lazily read files. Printf and friends now - have cord variants. Cord traversals are a bit faster. -- Made ALL_INTERIOR_POINTERS recognition the default. -- Fixed de so that it can run in constant space, independent - of file size. Added simple string searching to cords and de. -- Added the Hull-Ellis C++ interface. -- Added dynamic library support for OSF/1. - (Thanks to Al Dosser and Tim Bingham at DEC.) -- Changed argument to GC_expand_hp to be expressed - in units of bytes instead of heap blocks. (Necessary - since the heap block size now varies depending on - configuration. The old version was never very clean.) -- Added GC_get_heap_size(). The previous "equivalent" - was broken. -- Restructured the Makefile a bit. - -Since version 4.0: -- Changed finalization implementation to guarantee that - finalization procedures are called outside of the allocation - lock, making direct use of the interface a little less dangerous. - MAY BREAK EXISTING CLIENTS that assume finalizers - are protected by a lock. Since there seem to be few multithreaded - clients that use finalization, this is hopefully not much of - a problem. -- Fixed a gross bug in CORD_prev. -- Fixed a bug in blacklst.c that could result in unbounded - heap growth during startup on machines that do not clear - memory obtained from the OS (e.g. win32S). -- Ported de editor to win32/win32S. (This is now the only - version with a mouse-sensitive UI.) -- Added GC_malloc_ignore_off_page to allocate large arrays - in the presence of ALL_INTERIOR_POINTERS. -- Changed GC_call_with_alloc_lock to not disable signals in - the single-threaded case. -- Reduced retry count in GC_collect_or_expand for garbage - collecting when out of memory. -- Made uncollectable allocations bypass black-listing, as they - should. -- Fixed a bug in typed_test in test.c that could cause (legitimate) - GC crashes. -- Fixed some potential synchronization problems in finalize.c -- Fixed a real locking problem in typd_mlc.c. -- Worked around an AIX 3.2 compiler feature that results in - out of bounds memory references. -- Partially worked around an IRIX5.2 beta problem (which may - or may not persist to the final release). -- Fixed a bug in the heap integrity checking code that could - result in explicitly deallocated objects being identified as - smashed. Fixed a bug in the dbg_mlc stack saving code - that caused old argument pointers to be considered live. -- Fixed a bug in CORD_ncmp (and hence CORD_str). -- Repaired the OS2 port, which had suffered from bit rot - in 4.0. Worked around what appears to be CSet/2 V1.0 - optimizer bug. -- Fixed a Makefile bug for target "c++". - -Since version 4.1: -- Multiple bug fixes/workarounds in the Solaris threads version. - (It occasionally failed to locate some register contents for - marking. It also turns out that thr_suspend and friends are - unreliable in Solaris 2.3. Dirty bit reads appear - to be unreliable under some weird - circumstances. My stack marking code - contained a serious performance bug. The new code is - extremely defensive, and has not failed in several cpu - hours of testing. But no guarantees ...) -- Added MacOS support (thanks to Patrick Beard.) -- Fixed several syntactic bugs in gc_c++.h and friends. (These - didn't bother g++, but did bother most other compilers.) - Fixed gc_c++.h finalization interface. (It didn't.) -- 64 bit alignment for allocated objects was not guaranteed in a - few cases in which it should have been. -- Added GC_malloc_atomic_ignore_off_page. -- Added GC_collect_a_little. -- Added some prototypes to gc.h. -- Some other minor bug fixes (notably in Makefile). -- Fixed OS/2 / EMX port (thanks to Ari Huttunen). -- Fixed AmigaDOS port. (thanks to Michel Schinz). -- Fixed the DATASTART definition under Solaris. There - was a 1 in 16K chance of the collector missing the first - 64K of static data (and thus crashing). -- Fixed some blatant anachronisms in the README file. -- Fixed PCR-Makefile for upcoming PPCR release. - -Since version 4.2: -- Fixed SPARC alignment problem with GC_DEBUG. -- Fixed Solaris threads /proc workaround. The real - problem was an interaction with mprotect. -- Incorporated fix from Patrick Beard for gc_c++.h (now gc_cpp.h). -- Slightly improved allocator space utilization by - fixing the GC_size_map mechanism. -- Integrated some Sony News and MIPS RISCos 4.51 - patches. (Thanks to Nobuyuki Hikichi of - Software Research Associates, Inc. Japan) -- Fixed HP_PA alignment problem. (Thanks to - xjam@cork.cs.berkeley.edu.) -- Added GC_same_obj and friends. Changed GC_base - to return 0 for pointers past the end of large objects. - Improved GC_base performance with ALL_INTERIOR_POINTERS - on machines with a slow integer mod operation. - Added GC_PTR_ADD, GC_PTR_STORE, etc. to prepare - for preprocessor. -- changed the default on most UNIX machines to be that - signals are not disabled during critical GC operations. - This is still ANSI-conforming, though somewhat dangerous - in the presence of signal handlers. But the performance - cost of the alternative is sometimes problematic. - Can be changed back with a minor Makefile edit. -- renamed IS_STRING in gc.h, to CORD_IS_STRING, thus - following my own naming convention. Added the function - CORD_to_const_char_star. -- Fixed a gross bug in GC_finalize. Symptom: occasional - address faults in that function. (Thanks to Anselm - Baird-Smith (Anselm.BairdSmith@inria.fr) -- Added port to ICL DRS6000 running DRS/NX. Restructured - things a bit to factor out common code, and remove obsolete - code. Collector should now run under SUNOS5 with either - mprotect or /proc dirty bits. (Thanks to Douglas Steel - (doug@wg.icl.co.uk)). -- More bug fixes and workarounds for Solaris 2.X. (These were - mostly related to putting the collector in a dynamic library, - which didn't really work before. Also SOLARIS_THREADS - didn't interact well with dl_open.) Thanks to btlewis@eng.sun.com. -- Fixed a serious performance bug on the DEC Alpha. The text - segment was getting registered as part of the root set. - (Amazingly, the result was still fast enough that the bug - was not conspicuous.) The fix works on OSF/1, version 1.3. - Hopefully it also works on other versions of OSF/1 ... -- Fixed a bug in GC_clear_roots. -- Fixed a bug in GC_generic_malloc_words_small that broke - gc_inl.h. (Reported by Antoine de Maricourt. I broke it - in trying to tweak the Mac port.) -- Fixed some problems with cord/de under Linux. -- Fixed some cord problems, notably with CORD_riter4. -- Added DG/UX port. - Thanks to Ben A. Mesander (ben@piglet.cr.usgs.gov) -- Added finalization registration routines with weaker ordering - constraints. (This is necessary for C++ finalization with - multiple inheritance, since the compiler often adds self-cycles.) -- Filled the holes in the SCO port. (Thanks to Michael Arnoldus - <chime@proinf.dk>.) -- John Ellis' additions to the C++ support: From John: - -* I completely rewrote the documentation in the interface gc_c++.h -(later renamed gc_cpp.h). I've tried to make it both clearer and more -precise. - -* The definition of accessibility now ignores pointers from an -finalizable object (an object with a clean-up function) to itself. -This allows objects with virtual base classes to be finalizable by the -collector. Compilers typically implement virtual base classes using -pointers from an object to itself, which under the old definition of -accessibility prevented objects with virtual base classes from ever -being collected or finalized. - -* gc_cleanup now includes gc as a virtual base. This was enabled by -the change in the definition of accessibility. - -* I added support for operator new[]. Since most (all?) compilers -don't yet support operator new[], it is conditionalized on --DOPERATOR_NEW_ARRAY. The code is untested, but its trivial and looks -correct. - -* The test program test_gc_c++ (later renamed test_cpp.cc) -tries to test for the C++-specific functionality not tested by the -other programs. -- Added <unistd.h> include to misc.c. (Needed for ppcr.) -- Added PowerMac port. (Thanks to Patrick Beard again.) -- Fixed "srcdir"-related Makefile problems. Changed things so - that all externally visible include files always appear in the - include subdirectory of the source. Made gc.h directly - includable from C++ code. (These were at Per - Bothner's suggestion.) -- Changed Intel code to also mark from ebp (Kevin Warne's - suggestion). -- Renamed C++ related files so they could live in a FAT - file system. (Charles Fiterman's suggestion.) -- Changed Windows NT Makefile to include C++ support in - gc.lib. Added C++ test as Makefile target. - -Since version 4.3: - - ASM_CLEAR_CODE was erroneously defined for HP - PA machines, resulting in a compile error. - - Fixed OS/2 Makefile to create a library. (Thanks to - Mark Boulter (mboulter@vnet.ibm.com)). - - Gc_cleanup objects didn't work if they were created on - the stack. Fixed. - - One copy of Gc_cpp.h in the distribution was out of - synch, and failed to document some known compiler - problems with explicit destructor invocation. Partially - fixed. There are probably other compilers on which - gc_cleanup is miscompiled. - - Fixed Makefile to pass C compiler flags to C++ compiler. - - Added Mac fixes. - - Fixed os_dep.c to work around what appears to be - a new and different VirtualQuery bug under newer - versions of win32S. - - GC_non_gc_bytes was not correctly maintained by - GC_free. Fixed. Thanks to James Clark (jjc@jclark.com). - - Added GC_set_max_heap_size. - - Changed allocation code to ignore blacklisting if it is preventing - use of a very large block of memory. This has the advantage - that naive code allocating very large objects is much more - likely to work. The downside is you might no - longer find out that such code should really use - GC_malloc_ignore_off_page. - - Changed GC_printf under win32 to close and reopen the file - between calls. FAT file systems otherwise make the log file - useless for debugging. - - Added GC_try_to_collect and GC_get_bytes_since_gc. These - allow starting an abortable collection during idle times. - This facility does not require special OS support. (Thanks to - Michael Spertus of Geodesic Systems for suggesting this. It was - actually an easy addition. Kumar Srikantan previously added a similar - facility to a now ancient version of the collector. At the time - this was much harder, and the result was less convincing.) - - Added some support for the Borland development environment. (Thanks - to John Ellis and Michael Spertus.) - - Removed a misfeature from checksums.c that caused unexpected - heap growth. (Thanks to Scott Schwartz.) - - Changed finalize.c to call WARN if it encounters a finalization cycle. - WARN is defined in gc_priv.h to write a message, usually to stdout. - In many environments, this may be inappropriate. - - Renamed NO_PARAMS in gc.h to GC_NO_PARAMS, thus adhering to my own - naming convention. - - Added GC_set_warn_proc to intercept warnings. - - Fixed Amiga port. (Thanks to Michel Schinz (schinz@alphanet.ch).) - - Fixed a bug in mark.c that could result in an access to unmapped - memory from GC_mark_from_mark_stack on machines with unaligned - pointers. - - Fixed a win32 specific performance bug that could result in scanning of - objects allocated with the system malloc. - - Added REDIRECT_MALLOC. - -Since version 4.4: - - Fixed many minor and one major README bugs. (Thanks to Franklin Chen - (chen@adi.com) for pointing out many of them.) - - Fixed ALPHA/OSF/1 dynamic library support. (Thanks to Jonathan Bachrach - (jonathan@harlequin.com)). - - Added incremental GC support (MPROTECT_VDB) for Linux (with some - help from Bruno Haible). - - Altered SPARC recognition tests in gc.h and config.h (mostly as - suggested by Fergus Henderson). - - Added basic incremental GC support for win32, as implemented by - Windows NT and Windows 95. GC_enable_incremental is a noop - under win32s, which doesn't implement enough of the VM interface. - - Added -DLARGE_CONFIG. - - Fixed GC_..._ignore_off_page to also function without - -DALL_INTERIOR_POINTERS. - - (Hopefully) fixed RS/6000 port. (Only the test was broken.) - - Fixed a performance bug in the nonincremental collector running - on machines supporting incremental collection with MPROTECT_VDB - (e.g. SunOS 4, DEC AXP). This turned into a correctness bug under - win32s with win32 incremental collection. (Not all memory protection - was disabled.) - - Fixed some ppcr related bit rot. - - Caused dynamic libraries to be unregistered before reregistering. - The old way turned out to be a performance bug on some machines. - - GC_root_size was not properly maintained under MSWIN32. - - Added -DNO_DEBUGGING and GC_dump. - - Fixed a couple of bugs arising with SOLARIS_THREADS + - REDIRECT_MALLOC. - - Added NetBSD/M68K port. (Thanks to Peter Seebach - <seebs@taniemarie.solon.com>.) - - Fixed a serious realloc bug. For certain object sizes, the collector - wouldn't scan the expanded part of the object. (Thanks to Clay Spence - (cds@peanut.sarnoff.com) for noticing the problem, and helping me to - track it down.) - -Since version 4.5: - - Added Linux ELF support. (Thanks to Arrigo Triulzi <arrigo@ic.ac.uk>.) - - GC_base crashed if it was called before any other GC_ routines. - This could happen if a gc_cleanup object was allocated outside the heap - before any heap allocation. - - The heap expansion heuristic was not stable if all objects had finalization - enabled. Fixed finalize.c to count memory in finalization queue and - avoid explicit deallocation. Changed alloc.c to also consider this count. - (This is still not recommended. It's expensive if nothing else.) Thanks - to John Ellis for pointing this out. - - GC_malloc_uncollectable(0) was broken. Thanks to Phong Vo for pointing - this out. - - The collector didn't compile under Linux 1.3.X. (Thanks to Fred Gilham for - pointing this out.) The current workaround is ugly, but expected to be - temporary. - - Fixed a formatting problem for SPARC stack traces. - - Fixed some '=='s in os_dep.c that should have been assignments. - Fortunately these were in code that should never be executed anyway. - (Thanks to Fergus Henderson.) - - Fixed the heap block allocator to only drop blacklisted blocks in small - chunks. Made BL_LIMIT self adjusting. (Both of these were in response - to heap growth observed by Paul Graham.) - - Fixed the Metrowerks/68K Mac code to also mark from a6. (Thanks - to Patrick Beard.) - - Significantly updated README.debugging. - - Fixed some problems with longjmps out of signal handlers, especially under - Solaris. Added a workaround for the fact that siglongjmp doesn't appear to - do the right thing with -lthread under Solaris. - - Added MSDOS/djgpp port. (Thanks to Mitch Harris (maharri@uiuc.edu).) - - Added "make reserved_namespace" and "make user_namespace". The - first renames ALL "GC_xxx" identifiers as "_GC_xxx". The second is the - inverse transformation. Note that doing this is guaranteed to break all - clients written for the other names. - - descriptor field for kind NORMAL in GC_obj_kinds with ADD_BYTE_AT_END - defined should be -ALIGNMENT not WORDS_TO_BYTES(-1). This is - a serious bug on machines with pointer alignment of less than a word. - - GC_ignore_self_finalize_mark_proc didn't handle pointers to very near the - end of the object correctly. Caused failures of the C++ test on a DEC Alpha - with g++. - - gc_inl.h still had problems. Partially fixed. Added warnings at the - beginning to hopefully specify the remaining dangers. - - Added DATAEND definition to config.h. - - Fixed some of the .h file organization. Fixed "make floppy". - -Since version 4.6: - - Fixed some compilation problems with -DCHECKSUMS (thanks to Ian Searle) - - Updated some Mac specific files to synchronize with Patrick Beard. - - Fixed a serious bug for machines with non-word-aligned pointers. - (Thanks to Patrick Beard for pointing out the problem. The collector - should fail almost any conceivable test immediately on such machines.) - -Since version 4.7: - - Changed a "comment" in a MacOS specific part of mach-dep.c that caused - gcc to fail on other platforms. - -Since version 4.8 - - More README.debugging fixes. - - Objects ready for finalization, but not finalized in the same GC - cycle, could be prematurely collected. This occasionally happened - in test_cpp. - - Too little memory was obtained from the system for very large - objects. That could cause a heap explosion if these objects were - not contiguous (e.g. under PCR), and too much of them was blacklisted. - - Due to an improper initialization, the collector was too hesitant to - allocate blacklisted objects immediately after system startup. - - Moved GC_arrays from the data into the bss segment by not explicitly - initializing it to zero. This significantly - reduces the size of executables, and probably avoids some disk accesses - on program startup. It's conceivable that it might break a port that I - didn't test. - - Fixed EMX_MAKEFILE to reflect the gc_c++.h to gc_cpp.h renaming which - occurred a while ago. - -Since 4.9: - - Fixed a typo around a call to GC_collect_or_expand in alloc.c. It broke - handling of out of memory. (Thanks to Patrick Beard for noticing.) - -Since 4.10: - - Rationalized (hopefully) GC_try_to_collect in an incremental collection - environment. It appeared to not handle a call while a collection was in - progress, and was otherwise too conservative. - - Merged GC_reclaim_or_delete_all into GC_reclaim_all to get rid of some - code. - - Added Patrick Beard's Mac fixes, with substantial completely untested - modifications. - - Fixed the MPROTECT_VDB code to deal with large pages and imprecise - fault addresses (as on an UltraSPARC running Solaris 2.5). Note that this - was not a problem in the default configuration, which uses PROC_VDB. - - The DEC Alpha assembly code needed to restore $gp between calls. - Thanks to Fergus Henderson for tracking this down and supplying a - patch. - - The write command for "de" was completely broken for large files. - I used the easiest portable fix, which involved changing the semantics - so that f.new is written instead of overwriting f. That's safer anyway. - - Added README.solaris2 with a discussion of the possible problems of - mixing the collector's sbrk allocation with malloc/realloc. - - Changed the data segment starting address for SGI machines. The - old code failed under IRIX6. - - Required double word alignment for MIPS. - - Various minor fixes to remove warnings. - - Attempted to fix some Solaris threads problems reported by Zhiying Chen. - In particular, the collector could try to fork a thread with the - world stopped as part of GC_thr_init. It also failed to deal with - the case in which the original thread terminated before the whole - process did. - - Added -DNO_EXECUTE_PERMISSION. This has a major performance impact - on the incremental collector under Irix, and perhaps under other - operating systems. - - Added some code to support allocating the heap with mmap. This may - be preferable under some circumstances. - - Integrated dynamic library support for HP. - (Thanks to Knut Tvedten <knuttv@ifi.uio.no>.) - - Integrated James Clark's win32 threads support, and made a number - of changes to it, many of which were suggested by Pontus Rydin. - This is still not 100% solid. - - Integrated Alistair Crooks' support for UTS4 running on an Amdahl - 370-class machine. - - Fixed a serious bug in explicitly typed allocation. Objects requiring - large descriptors where handled in a way that usually resulted in - a segmentation fault in the marker. (Thanks to Jeremy Fitzhardinge - for helping to track this down.) - - Added partial support for GNU win32 development. (Thanks to Fergus - Henderson.) - - Added optional support for Java-style finalization semantics. (Thanks - to Patrick Bridges.) This is recommended only for Java implementations. - - GC_malloc_uncollectable faulted instead of returning 0 when out of - memory. (Thanks to dan@math.uiuc.edu for noticing.) - - Calls to GC_base before the collector was initialized failed on a - DEC Alpha. (Thanks to Matthew Flatt.) - - Added base pointer checking to GC_REGISTER_FINALIZER in debugging - mode, at the suggestion of Jeremy Fitzhardinge. - - GC_debug_realloc failed for uncollectable objects. (Thanks to - Jeremy Fitzhardinge.) - - Explicitly typed allocation could crash if it ran out of memory. - (Thanks to Jeremy Fitzhardinge.) - - Added minimal support for a DEC Alpha running Linux. - - Fixed a problem with allocation of objects whose size overflowed - ptrdiff_t. (This now fails unconditionally, as it should.) - - Added the beginning of Irix pthread support. - - Integrated Xiaokun Zhu's fixes for djgpp 2.01. - - Added SGI-style STL allocator support (gc_alloc.h). - - Fixed a serious bug in README.solaris2. Multithreaded programs must include - gc.h with SOLARIS_THREADS defined. - - Changed GC_free so it actually deallocates uncollectable objects. - (Thanks to Peter Chubb for pointing out the problem.) - - Added Linux ELF support for dynamic libararies. (Thanks again to - Patrick Bridges.) - - Changed the Borland cc configuration so that the assembler is not - required. - - Fixed a bug in the C++ test that caused it to fail in 64-bit - environments. - -Since 4.11: - - Fixed ElfW definition in dyn_load.c. (Thanks to Fergus Henderson.) - This prevented the dynamic library support from compiling on some - older ELF Linux systems. - - Fixed UTS4 port (which I apparently mangled during the integration) - (Thanks to again to Alistair Crooks.) - - "Make C++" failed on Suns with SC4.0, due to a problem with "bool". - Fixed in gc_priv.h. - - Added more pieces for GNU win32. (Thanks to Timothy N. Newsham.) - The current state of things should suffice for at least some - applications. - - Changed the out of memory retry count handling as suggested by - Kenjiro Taura. (This matters only if GC_max_retries > 0, which - is no longer the default.) - - If a /proc read failed repeatedly, GC_written_pages was not updated - correctly. (Thanks to Peter Chubb for diagnosing this.) - - Under unlikely circumstances, the allocator could infinite loop in - an out of memory situation. (Thanks again to Kenjiro Taura for - identifying the problem and supplying a fix.) - - Fixed a syntactic error in the DJGPP code. (Thanks to Fergus - Henderson for finding this by inspection.) Also fixed a test program - problem with DJGPP (Thanks to Peter Monks.) - - Atomic uncollectable objects were not treated correctly by the - incremental collector. This resulted in weird log statistics and - occasional performance problems. (Thanks to Peter Chubb for pointing - this out.) - - Fixed some problems resulting from compilers that dont define - __STDC__. In this case void * and char * were used inconsistently - in some cases. (Void * should not have been used at all. If - you have an ANSI superset compiler that does not define __STDC__, - please compile with -D__STDC__=0. Thanks to Manuel Serrano and others - for pointing out the problem.) - - Fixed a compilation problem on Irix with -n32 and -DIRIX_THREADS. - Also fixed some other IRIX_THREADS problems which may or may not have - had observable symptoms. - - Fixed an HP PA compilation problem in dyn_load.c. (Thanks to - Philippe Queinnec.) - - SEGV fault handlers sometimes did not get reset correctly. (Thanks - to David Pickens.) - - Added a fix for SOLARIS_THREADS on Intel. (Thanks again to David - Pickens.) This probably needs more work to become functional. - - Fixed struct sigcontext_struct in os_dep.c for compilation under - Linux 2.1.X. (Thanks to Fergus Henderson.) - - Changed the DJGPP STACKBOTTOM and DATASTART values to those suggested - by Kristian Kristensen. These may still not be right, but it is - it is likely to work more often than what was there before. They may - even be exactly right. - - Added a #include <string.h> to test_cpp.cc. This appears to help - with HP/UX and gcc. (Thanks to assar@sics.se.) - - Version 4.11 failed to run in incremental mode on recent 64-bit Irix - kernels. This was a problem related to page unaligned heap segments. - Changed the code to page align heap sections on all platforms. - (I had mistakenly identified this as a kernel problem earlier. - It was not.) - - Version 4.11 did not make allocated storage executable, except on - one or two platforms, due to a bug in a #if test. (Thanks to Dave - Grove for pointing this out.) - - Added sparc_sunos4_mach_dep.s to support Sun's compilers under SunOS4. - - Added GC_exclude_static_roots. - - Fixed the object size mapping algorithm. This shouldn't matter, - but the old code was ugly. - - Heap checking code could die if one of the allocated objects was - larger than its base address. (Unsigned underflow problem. Thanks - to Clay Spence for isolating the problem.) - - Added RS6000 (AIX) dynamic library support and fixed STACK_BOTTOM. - (Thanks to Fred Stearns.) - - Added Fergus Henderson's patches for improved robustness with large - heaps and lots of blacklisting. - - Added Peter Chubb's changes to support Solaris Pthreads, to support - MMAP allocation in Solaris, to allow Solaris to find dynamic libraries - through /proc, to add malloc_typed_ignore_off_page, and a few other - minor features and bug fixes. - - The Solaris 2 port should not use sbrk. I received confirmation from - Sun that the use of sbrk and malloc in the same program is not - supported. The collector now defines USE_MMAP by default on Solaris. - - Replaced the djgpp makefile with Gary Leavens' version. - - Fixed MSWIN32 detection test. - - Added Fergus Henderson's patches to allow putting the collector into - a DLL under GNU win32. - - Added Ivan V. Demakov's port to Watcom C on X86. - - Added Ian Piumarta's Linux/PowerPC port. - - On Brian Burton's suggestion added PointerFreeGC to the placement - options in gc_cpp.h. This is of course unsafe, and may be controversial. - On the other hand, it seems to be needed often enough that it's worth - adding as a standard facility. - -Since 4.12: - - Fixed a crucial bug in the Watcom port. There was a redundant decl - of GC_push_one in gc_priv.h. - - Added FINALIZE_ON_DEMAND. - - Fixed some pre-ANSI cc problems in test.c. - - Removed getpagesize() use for Solaris. It seems to be missing in one - or two versions. - - Fixed bool handling for SPARCCompiler version 4.2. - - Fixed some files in include that had gotten unlinked from the main - copy. - - Some RS/6000 fixes (missing casts). Thanks to Toralf Foerster. - - Fixed several problems in GC_debug_realloc, affecting mostly the - FIND_LEAK case. - - GC_exclude_static_roots contained a buggy unsigned comparison to - terminate a loop. (Thanks to Wilson Ho.) - - CORD_str failed if the substring occurred at the last possible position. - (Only affects cord users.) - - Fixed Linux code to deal with RedHat 5.0 and integrated Peter Bigot's - os_dep.c code for dealing with various Linux versions. - - Added workaround for Irix pthreads sigaction bug and possible signal - misdirection problems. -Since alpha1: - - Changed RS6000 STACKBOTTOM. - - Integrated Patrick Beard's Mac changes. - - Alpha1 didn't compile on Irix m.n, m < 6. - - Replaced Makefile.dj with a new one from Gary Leavens. - - Added Andrew Stitcher's changes to support SCO OpenServer. - - Added PRINT_BLACK_LIST, to allow debugging of high densities of false - pointers. - - Added code to debug allocator to keep track of return address - in GC_malloc caller, thus giving a bit more context. - - Changed default behavior of large block allocator to more - aggressively avoid fragmentation. This is likely to slow down the - collector when it succeeds at reducing space cost. - - Integrated Fergus Henderson's CYGWIN32 changes. They are untested, - but needed for newer versions. - - USE_MMAP had some serious bugs. This caused the collector to fail - consistently on Solaris with -DSMALL_CONFIG. - - Added Linux threads support, thanks largely to Fergus Henderson. -Since alpha2: - - Fixed more Linux threads problems. - - Changed default GC_free_space_divisor to 3 with new large block allocation. - (Thanks to Matthew Flatt for some measurements that suggest the old - value sometimes favors space too much over time.) - - More CYGWIN32 fixes. - - Integrated Tyson-Dowd's Linux-M68K port. - - Minor HP PA and DEC UNIX fixes from Fergus Henderson. - - Integrated Christoffe Raffali's Linux-SPARC changes. - - Allowed for one more GC fixup iteration after a full GC in incremental - mode. Some quick measurements suggested that this significantly - reduces pause times even with smaller GC_RATE values. - - Moved some more GC data structures into GC_arrays. This decreases - pause times and GC overhead, but makes debugging slightly less convenient. - - Fixed namespace pollution problem ("excl_table"). - - Made GC_incremental a constant for -DSMALL_CONFIG, hopefully shrinking - that slightly. - - Added some win32 threads fixes. - - Integrated Ivan Demakov and David Stes' Watcom fixes. - - Various other minor fixes contributed by many people. - - Renamed config.h to gcconfig.h, since config.h tends to be used for - many other things. - - Integrated Matthew Flatt's support for 68K MacOS "far globals". - - Fixed up some of the dynamic library Makefile targets for consistency - across platforms. - - Fixed a USE_MMAP typo that caused out-of-memory handling to fail - on Solaris. - - Added code to test.c to test thread creation a bit more. - - Integrated GC_win32_free_heap, as suggested by Ivan Demakov. - - Fixed Solaris 2.7 stack base finding problem. (This may actually - have been done in an earlier alpha release.) -Since alpha3: - - Fixed MSWIN32 recognition test, which interfered with cygwin. - - Removed unnecessary gc_watcom.asm from distribution. Removed - some obsolete README.win32 text. - - Added Alpha Linux incremental GC support. (Thanks to Philipp Tomsich - for code for retrieving the fault address in a signal handler.) - Changed Linux signal handler context argument to be a pointer. - - Took care of some new warnings generated by the 7.3 SGI compiler. - - Integrated Phillip Musumeci's FreeBSD/ELF fixes. - - -DIRIX_THREADS was broken with the -o32 ABI (typo in gc_priv.h> - -Since 4.13: - - Fixed GC_print_source_ptr to not use a prototype. - - generalized CYGWIN test. - - gc::new did the wrong thing with PointerFreeGC placement. - (Thanks to Rauli Ruohonen.) - - In the ALL_INTERIOR_POINTERS (default) case, some callee-save register - values could fail to be scanned if the register was saved and - reused in a GC frame. This showed up in verbose mode with gctest - compiled with an unreleased SGI compiler. I vaguely recall an old - bug report that may have been related. The bug was probably quite old. - (The problem was that the stack scanning could be deferred until - after the relevant frame was overwritten, and the new save location - might be outside the scanned area. Fixed by more eager stack scanning.) - - PRINT_BLACK_LIST had some problems. A few source addresses were garbage. - - Replaced Makefile.dj and added -I flags to cord make targets. - (Thanks to Gary Leavens.) - - GC_try_to_collect was broken with the nonincremental collector. - - gc_cleanup destructors could pass the wrong address to - GC_register_finalizer_ignore_self in the presence of multiple - inheritance. (Thanks to Darrell Schiebel.) - - Changed PowerPC Linux stack finding code. - -Since 4.14alpha1 - - -DSMALL_CONFIG did not work reliably with large (> 4K) pages. - Recycling the mark stack during expansion could result in a size - zero heap segment, which confused things. (This was probably also an - issue with the normal config and huge pages.) - - Did more work to make sure that callee-save registers were scanned - completely, even with the setjmp-based code. Added USE_GENERIC_PUSH_REGS - macro to facilitate testing on machines I have access to. - - Added code to explicitly push register contents for win32 threads. - This seems to be necessary. (Thanks to Pierre de Rop.) - -Since 4.14alpha2 - - changed STACKBOTTOM for DJGPP (Thanks to Salvador Eduardo Tropea). - -Since 4.14 - - Reworked large block allocator. Now uses multiple doubly linked free - lists to approximate best fit. - - Changed heap expansion heuristic. Entirely free blocks are no longer - counted towards the heap size. This seems to have a major impact on - heap size stability; the old version could expand the heap way too - much in the presence of large block fragmentation. - - added -DGC_ASSERTIONS and some simple assertions inside the collector. - This is mainlyt for collector debugging. - - added -DUSE_MUNMAP to allow the heap to shrink. Suupported on only - a few UNIX-like platforms for now. - - added GC_dump_regions() for debugging of fragmentation issues. - - Changed PowerPC pointer alignment under Linux to 4. (This needs - checking by someone who has one. The suggestions came to me via a - rather circuitous path.) - - Changed the Linux/Alpha port to walk the data segment backwards until - it encounters a SIGSEGV. The old way to find the start of the data - segment broke with a recent release. - - cordxtra.c needed to call GC_REGISTER_FINALIZER instead of - GC_register_finalizer, so that it would continue to work with GC_DEBUG. - - allochblk sometimes cleared the wrong block for debugging purposes - when it dropped blacklisted blocks. This could result in spurious - error reports with GC_DEBUG. - - added MACOS X Server support. (Thanks to Andrew Stone.) - - Changed the Solaris threads code to ignore stack limits > 8 MB with - a warning. Empirically, it is not safe to access arbitrary pages - in such large stacks. And the dirty bit implementation does not - guarantee that none of them will be accessed. - - Integrated Martin Tauchmann's Amiga changes. - - Integrated James Dominy's OpenBSD/SPARC port. - -Since 5.0alpha1 - - Fixed bugs introduced in alpha1 (OpenBSD & large block initialization). - - Added -DKEEP_BACK_PTRS and backptr.h interface. (The implementation - idea came from Al Demers.) - -Since 5.0alpha2 - - Added some highly incomplete code to support a copied young generation. - Comments on nursery.h are appreciated. - - Changed -DFIND_LEAK, -DJAVA_FINALIZATION, and -DFINALIZE_ON_DEMAND, - so the same effect could be obtained with a runtime switch. This is - a step towards standardizing on a single dynamic GC library. - - Significantly changed the way leak detection is handled, as a consequence - of the above. - -Since 5.0 alpha3 - - Added protection fault handling patch for Linux/M68K from Fergus - Henderson and Roman Hodek. - - Removed the tests for SGI_SOURCE in new_gc_alloc.h. This was causing that - interface to fail on nonSGI platforms. - - Changed the Linux stack finding code to use /proc, after changing it - to use HEURISTIC1. (Thanks to David Mossberger for pointing out the - /proc hook.) - - Added HP/UX incremental GC support and HP/UX 11 thread support. - Thread support is currently still flakey. - - Added basic Linux/IA64 support. - - Integrated Anthony Green's PicoJava support. - - Integrated Scott Ananian's StrongARM/NetBSD support. - - Fixed some fairly serious performance bugs in the incremental - collector. These have probably been there essentially forever. - (Mark bits were sometimes set before scanning dirty pages. - The reclaim phase unnecessarily dirtied full small object pages.) - - Changed the reclaim phase to ignore nearly full pages to avoid - touching them. - - Limited GC_black_list_spacing to roughly the heap growth increment. - - Changed full collection triggering heuristic to decrease full GC - frequency by default, but to explicitly trigger full GCs during - heap growth. This doesn't always improve things, but on average it's - probably a win. - - GC_debug_free(0, ...) failed. Thanks to Fergus Henderson for the - bug report and fix. - -Since 5.0 alpha4 - - GC_malloc_explicitly_typed and friends sometimes failed to - initialize first word. - - Added allocation routines and support in the marker for mark descriptors - in a type structure referenced by the first word of an object. This was - introduced to support gcj, but hopefully in a way that makes it - generically useful. - - Added GC_requested_heapsize, and inhibited collections in nonincremental - mode if the actual used heap size is less than what was explicitly - requested. - - The Solaris pthreads version of GC_pthread_create didn't handle a NULL - attribute pointer. Solaris thread support used the wrong default thread - stack size. (Thanks to Melissa O'Neill for the patch.) - - Changed PUSH_CONTENTS macro to no longer modify first parameter. - This usually doesn't matter, but it was certainly an accident waiting - to happen ... - - Added GC_register_finalizer_no_order and friends to gc.h. They're - needed by Java implementations. - - Integrated a fix for a win32 deadlock resulting from clock() calling - malloc. (Thanks to Chris Dodd.) - - Integrated Hiroshi Kawashima's port to Linux/MIPS. This was designed - for a handheld platform, and may or may not be sufficient for other - machines. - - Fixed a va_arg problem with the %c specifier in cordprnt.c. It appears - that this was always broken, but recent versions of gcc are the first to - report the (statically detectable) bug. - - Added an attempt at a more general solution to dlopen races/deadlocks. - GC_dlopen now temporarily disables collection. Still not ideal, but ... - - Added -DUSE_I686_PREFETCH, -DUSE_3DNOW_PREFETCH, and support for IA64 - prefetch instructions. May improve performance measurably, but I'm not - sure the code will run correctly on processors that don't support the - instruction. Won't build except with very recent gcc. - - Added caching for header lookups in the marker. This seems to result - in a barely measurable performance gain. Added support for interleaved - lookups of two pointers, but unconfigured that since the performance - gain is currently near zero, and it adds to code size. - - Changed Linux DATA_START definition to check both data_start and - __data_start, since nothing else seems to be portable. - - Added -DUSE_LD_WRAP to optionally take advantage of the GNU ld function - wrapping mechanism. Probably currently useful only on Linux. - - Moved some variables for the scratch allocator into GC_arrays, on - Martin Hirzel's suggestion. - - Fixed a win32 threads bug that caused the collector to not look for - interior pointers from one of the thread stacks without - ALL_INTERIOR_POINTERS. (Thanks to Jeff Sturm.) - - Added Mingw32 support. (Thanks again to Jeff Sturm for the patch.) - - Changed the alpha port to use the generic register scanning code instead - of alpha_mach_dep.s. Alpha_mach_dep.s doesn't look for pointers in fp - registers, but gcc sometimes spills pointers there. (Thanks to Manuel - Serrano for helping me debug this by email.) Changed the IA64 code to - do something similar for similar reasons. - -[5.0alpha5 doesn't really exist, but it may have escaped.] - -Since 5.0alpha6: - - -DREDIRECT_MALLOC was broken in alpha6. Fixed. - - Cleaned up gc_ccp.h slightly, thus also causing the HP C++ compiler to - accept it. - - Removed accidental reference to dbg_mlc.c, which caused dbg_mlc.o to be - linked into every executable. - - Added PREFETCH to bitmap marker. Changed it to use the header cache. - - GC_push_marked sometimes pushed one object too many, resulting in a - segmentation fault in GC_mark_from_mark_stack. This was probably an old - bug. It finally showed up in gctest on win32. - - Gc_priv.h erroneously #defined GC_incremental to be TRUE instead of FALSE - when SMALL_CONFIG was defined. This was no doubt a major performance bug for - the default win32 configuration. - - Removed -DSMALL_CONFIG from NT_MAKEFILE. It seemed like an anchronism now - that the average PC has 64MB or so. - - Integrated Bryce McKinley's patches for linux threads and dynamic loading - from the libgcj tree. Turned on dynamic loading support for Linux/PPC. - - Changed the stack finding code to use environ on HP/UX. (Thanks - to Gustavo Rodriguez-Rivera for the suggestion.) This should probably - be done on other platforms, too. Since I can't test those, that'll - wait until after 5.0. - -Since 5.0alpha7: - - Fixed threadlibs.c for linux threads. -DUSE_LD_WRAP was broken and - -ldl was omitted. Fixed Linux stack finding code to handle - -DUSE_LD_WRAP correctly. - - Added MSWIN32 exception handler around marker, so that the collector - can recover from root segments that are unmapped during the collection. - This caused occasional failures under Windows 98, and may also be - an issue under Windows NT/2000. - -Since 5.0 - - Fixed a gc.h header bug which showed up under Irix. (Thanks to - Dan Sullivan.) - - Fixed a typo in GC_double_descr in typd_mlc.c. - This probably could result in objects described by array descriptors not - getting traced correctly. (Thanks to Ben Hutchings for pointing this out.) - - The block nearly full tests in reclaim.c were not correct for 64 bit - environments. This could result in unnecessary heap growth under unlikely - conditions. - -Since 5.1 - - dyn_load.c declared GC_scratch_last_end_ptr as an extern even if it - was defined as a macro. This prevented the collector from building on - Irix. - - We quietly assumed that indirect mark descriptors were never 0. - Our own typed allocation interface violated that. This could result - in segmentation faults in the marker with typed allocation. - - Fixed a _DUSE_MUNMAP bug in the heap block allocation code. - (Thanks to Ben Hutchings for the patch.) - - Taught the collector about VC++ handling array operator new. - (Thanks again to Ben Hutchings for the patch.) - - The two copies of gc_hdrs.h had diverged. Made one a link to the other - again. - -Since 5.2 (A few 5.2 patches are not in 6.0alpha1) - - Fixed _end declaration for OSF1. - - There were lots of spurious leak reports in leak detection mode, caused - by the fact that some pages were not being swept, and hence unmarked - objects weren't making it onto free lists. (This bug dated back to 5.0.) - - Fixed a typo in the liblinuxgc.so Makefile rule. - - Added the GetExitCodeThread to Win32 GC_stop_world to (mostly) work - around a Windows 95 GetOpenFileName problem. (Thanks to Jacob Navia.) - -Since 5.3 - - Fixed a typo that prevented compilation with -DUSE_3DNOW_PREFETCH. - (Thanks to Shawn Wagner for actually testing this.) - - Fixed GC_is_thread_stack in solaris_threads.c. It forgot to return a value - in the common case. I wonder why nobody noticed? - - Fixed another silly syntax problem in GC_double_descr. (Thanks to - Fergus Henderson for finding it.) - - Fixed a GC_gcj_malloc bug: It tended to release the allocator lock twice. - -Since 5.4 (A few 5.3 patches are not in 6.0alpha2) - - Added HP/PA prefetch support. - - Added -DDBG_HDRS_ALL and -DSHORT_DBG_HDRS to reduce the cost and improve - the reliability of generating pointer backtrace information, e.g. in - the Bigloo environment. - - Added parallel marking support (-DPARALLEL_MARK). This currently - works only under IA32 and IA64 Linux, but it shouldn't be hard to adapt - to other platforms. This is intended to be a lighter-weight (less - new code, probably not as scalable) solution than the work by Toshio Endo - et al, at the University of Tokyo. A number of their ideas were - reused, though the code wasn't, and the underlying data structure - is significantly different. In particular, we keep the global mark - stack as a single shared data structure, but most of the work is done - on smaller thread-local mark stacks. - - Changed GC_malloc_many to be cheaper, and to require less mutual exclusion - with -DPARALLEL_MARK. - - Added full support for thread local allocation under Linux - (-DTHREAD_LOCAL_ALLOC). This is a thin veneer on GC_malloc_many, and - should be easily portable to other platforms, especially those that - support pthreads. - - CLEAR_DOUBLE was not always getting invoked when it should have been. - - GC_gcj_malloc and friends used different out of memory handling than - everything else, probably because I forgot about one when I implemented - the other. They now both call GC_oom_fn(), not GC_oom_action(). - - Integrated Jakub Jelinek's fixes for Linux/SPARC. - - Moved GC_objfreelist, GC_aobjfreelist, and GC_words_allocd out of - GC_arrays, and separately registered the first two as excluded roots. - This makes code compiled with gc_inl.h less dependent on the - collector version. (It would be nice to remove the inclusion of - gc_priv.h by gc_inl.h completely, but we're not there yet. The - locking definitions in gc_priv.h are still referenced.) - This change was later coniditoned on SEPARATE_GLOBALS, which - is not defined by default, since it involves a performance hit. - - Register GC_obj_kinds separately as an excluded root region. The - attempt to register it with GC_arrays was usually failing. (This wasn't - serious, but seemed to generate some confusion.) - - Moved backptr.h to gc_backptr.h. - -Since 6.0alpha1 - - Added USE_MARK_BYTES to reduce the need for compare-and-swap on platforms - for which that's expensive. - - Fixed a locking bug ib GC_gcj_malloc and some locking assertion problems. - - Added a missing volatile to OR_WORD and renamed the parameter to - GC_compare_and_swap so it's not a C++ reserved word. (Thanks to - Toshio Endo for pointing out both of those.) - - Changed Linux dynamic library registration code to look at /proc/self/maps - instead of the rld data structures when REDIRECT_MALLOC is defined. - Otherwise some of the rld data data structures may be prematurely garbage - collected. (Thanks to Eric Benson for helping to track this down.) - - Fixed USE_LD_WRAP a bit more, so it should now work without threads. - - Renamed XXX_THREADS macros to GC_XXX_THREADS for namespace correctness. - Tomporarily added some backward compatibility definitions. Renamed - USE_LD_WRAP to GC_USE_LD_WRAP. - - Many MACOSX POWERPC changes, some additions to the gctest output, and - a few minor generic bug fixes. (Thanks to Dietmar Planitzer.) - -Since 6.0 alpha2 - - Fixed the /proc/self/maps code to not seek, since that apparently is not - reliable across all interesting kernels. - - Fixed some compilation problems in the absence of PARALLEL_MARK - (introduced in alpha2). - - Fixed an algorithmic problem with PARALLEL_MARK. If work needs to - be given back to the main mark "stack", the BOTTOM entries of the local - stack should be given away, not the top ones. This has substantial - performance impact, especially for > 2 processors, from what I can tell. - - Extracted gc_lock.h from gc_priv.h. This should eventually make it a - bit easier to avoid including gc_priv.h in clients. - - Moved all include files to include/ and removed duplicate links to the - same file. The old scheme was a bad idea because it was too easy to get the - copies out of sync, and many systems don't support hard links. - Unfortunately, it's likely that I broke some of the non-Unix Makefiles in - the process, although I tried to update them appropriately. - - Removed the partial support for a copied nursery. It's not clear that - this would be a tremendous win, since we don't consistently lose to - generational copying collectors. And it would significantly complicate - many things. May be reintroduced if/when it really turns out to win. - - Removed references to IRIX_JDK_THREADS, since I believe there never - were and never will be any clients. - - Added some code to linux_threads.c to possibly support HPUX threads - using the Linux code. Unfortunately, it doesn't work yet, and is - currently disabled. - - Added support under Linux/X86 for saving the call chain, both in (debug) - objects for client debugging, and in GC_arrays._last_stack for GC - debugging. This was previously supported only under Solaris. It is - not enabled by default under X86, since it requires that code be compiled - to explicitly dave frame pointers on the call stack. (With gcc this - currently happens by default, but is often turned off explicitly.) - To turn it on, define SAVE_CALL_CHAIN. - -Since 6.0 alpha3 - - Moved up the detection of mostly full blocks to the initiatiation of the - sweep phase. This eliminates some lock conention in the PARALLEL_MARK case, - as multiple threads try to look at mostly full blocks concurrently. - - Restored the code in GC_malloc_many that grabs a prefix of the global - free list. This avoids the case in which every GC_malloc_many call - tries and fails to allocate a new heap block, and the returns a single - object from the global free list. - - Some minor fixes in new_hblk.c. (Attempted to build free lists in order - of increasing addresses instead of decreasing addresses for cache performance - reasons. But this seems to be only a very minor gain with -DEAGER_SWEEP, - and a loss in other cases. So the change was backed out.) - - Fixed some of the documentation. (Thanks in large part to Fergus - Henderson.) - - Fixed the Linux USE_PROC_FOR_LIBRARIES code to deal with apps that perform - large numbers of mmaps. (Thanks to Eric Benson.) Also fixed that code to - deal with short reads. - - Added GC_get_total_bytes(). - - Fixed leak detection mode to avoid spurious messages under linuxthreads. - (This should also now be easy for the other supported threads packages. - But the code is tricky enough that I'm hesitant to do it without being able - to test. Everything allocated in the GC thread support itself should be - explicitly deallocated.) - - Made it possible (with luck) to redirect malloc to GC_local_malloc. - -Since 6.0 alpha4 - - Changed the definition of GC_pause in linux_threads.c to use a volatile - asm. Some versions of gcc apparently optimize away writes to local volatile - variables. This caused poor locking behaviour starting at about - 4 processors. - - Added GC_start_blocking(), GC_end_blocking() calls and wrapper for sleep - to linux_threads.c. - The first two calls could be used to generally avoid sending GC signals to - blocked threads, avoiding both premature wakeups and unnecessary overhead. - - Fixed a serious bug in thread-local allocation. At thread termination, - GC_free could get called on small integers. Changed the code for thread - termination to more efficiently return left-over free-lists. - - Integrated Kjetil Matheussen's BeOS support. - - Rearranged the directory structure to create the doc and tests - subdirectories. - - Sort of integrated Eric Benson's patch for OSF1. This provided basic - OSF1 thread support by suitably extending hpux_irix_threads.c. Based - on earlier email conversations with David Butenhof, I suspect that it - will be more reliable in the long run to base this on linux_threads.c - instead. Thus I attempted to patch up linux_threads.c based on Eric's code. - The result is almost certainly broken, but hopefully close enough that - someone with access to a machine can pick it up. - - Integrated lots of minor changes from the NetBSD distribution. (These - were supplied by David Brownlee. I'm not sure about the original - authors.) - - Hacked a bit more on the HP/UX thread-support in linux_threads.c. It - now appears to work in the absence of incremental collection. Renamed - hpux_irix_threads.c back to irix_threads.c, and removed the attempt to - support HPUX there. - - Changed gc.h to define _REENTRANT in cases in which it should already - have been defined. It is still safer to also define it on the command - line. - -Since 6.0alpha5: - - Changed the definition of DATASTART on ALPHA and IA64, where data_start - and __data_start are not defined by earlier versions of glibc. This might - need to be fixed on other platforms as well. - - Changed the way the stack base and backing store base are found on IA64. - This should now remain reliable on future kernels. But since it relies - on /proc, it will no longer work in the simulated NUE environment. - - Made the call to random() in dbg_mlc.c with -DKEEP_BACK_PTRS dependent - on the OS. On non-Unix systems, rand() should be used instead. Handled - small RAND_MAX. (Thanks to Peter Ross for pointing this out.) - - Fixed the cord make rules to create the cord subdirectory, if necessary. - (Thanks to Doug Moen.) - - Changed fo_object_size calculation in finalize.c. Turned finalization - of nonheap object into a no-op. Removed anachronism from GC_size() - implementation. - - Changed GC_push_dirty call in solaris_threads.c to GC_push_selected. - It was missed in a previous renaming. (Thanks to Vladimir Tsichevski - for pointing this out.) - - Arranged to not not mask SIGABRT in linux_threads.c. (Thanks to Bryce - McKinlay.) - - Added GC_no_dls hook for applications that want to register their own - roots. - - Integrated Kjetil Matheussen's Amiga changes. - - Added FREEBSD_STACKBOTTOM. Changed the X86/FreeBSD port to use it. - (Thanks to Matthew Flatt.) - - Added pthread_detach interception for platforms supported by linux_threads.c - and irix_threads.c. Should also be added for Solaris? - - Changed the USE_MMAP code to check for the case in which we got the - high end of the address space, i.e. mem_ptr + mem_sz == 0. It appears - that this can happen under Solaris 7. It seems to be allowed by what - I would claim is an oversight in the mmap specification. (Thanks to Toshio - Endo for pointing out the problem.) - - Cleanup of linux_threads.c. Some code was originally cloned from - irix_threads.c and now unnecessary. Some comments were obviously wrong. - - (Mostly) fixed a longstanding problem with setting of dirty bits from - a signal handler. In the presence of threads, dirty bits could get lost, - since the etting of a bit in the bit vector was not atomic with respect - to other updates. The fix is 100% correct only for platforms for which - GC_test_and_set is defined. The goal is to make that all platforms with - thread support. Matters only if incremental GC and threads are both - enabled. - - made GC_all_interior_pointers (a.k.a. ALL_INTERIOR_POINTERS) an - initialization time, instead of build-time option. This is a - nontrivial, high risk change. It should slow down the code measurably - only if MERGE_SIZES is not defined, which is a very nonstandard - configuration. - - Added doc/README.environment, and implemented what it describes. This - allows a number of additional configuration options to be set through - the environment. It documents a few previously undocumented options. - - Integrated Eric Benson's leak testing improvements. - - Removed the option to throw away the beginning of each page (DISCARD_WORDS). - This became less and less useful as processors enforce stricter alignment. - And it hadn't been tested in ages, and was thus probably broken anyway. - -Since 6.0alpha6: - - Added GC_finalizer_notifier. Fixed GC_finalize_on_demand. (The variable - actually wasn't being tested at the right points. The build-time flag - was.) - - Added Tom Tromey's S390 Linux patch. - - Added code to push GC_finalize_now in GC_push_finalizer_structures. - (Thanks to Matthew Flatt.) - - Added GC_push_gc_structures() to push all GC internal roots. - - Integrated some FreeBSD changes from Matthew Flatt. - - It looks like USRSTACK is not always correctly defined under Solaris. - Hacked gcconfig.h to attempt to work around the problem. The result - is not well tested. (Thanks again to Matthew Flatt for pointing this - out. The gross hack is mine. - HB) - - Added Ji-Yong Chung's win32 threads and C++ fixes. - - Arranged for hpux_test_and_clear.s to no longer be needed or built. - It was causing build problems with gas, and it's not clear this is - better than the pthreads alternative on this platform. - - Some MINGW32 fixes from Hubert Garavel. - - Added Initial Hitachi SH4 port from Kaz Kojima. - - Ported thread-local allocation and parallel mark code to HP/UX on PA_RISC. - - Made include/gc_mark.h more public and separated out the really private - pieces. This is probably still not quite sufficient for clients that - want to supply their own kind of type information. But it's a start. - This involved lots of identifier renaming to make it namespace clean. - - Added GC_dont_precollect for clients that need complete control over - the root set. - - GC_is_visible didn't do the right thing with gcj objects. (Not that - many people are likely to care, but ...) - - Don't redefine read with GC_USE_LD_WRAP. - - Initial port to LINUX/HP_PA. Incremental collection and threads are not - yet supported. (Incremental collection should work if you have the - right kernel. Threads may work with a sufficiently patched pthread - library.) - - Changed gcconfig.h to recognize __i386__ as an alternative to i386 in - many places. (Thanks to Benjamin Lerman.) - - Made win32_threads.c more tolerant of detaching a thread that it didn't - know about. (Thanks to Paul Nash.) - - Added Makefile.am and configure.in from gcc to the distribution, with - minimal changes. For the moment, those are just placeholders. In the - future, we're planning to switch to a GNU-style build environment for - Un*x-like systems, though the old Makefile will remain as a backup. - - Turned off STUBBORN_ALLOC by default, and added it back as a Makefile - option. - - Redistributed some functions between malloc.c and mallocx.c, so that - simple statically linked apps no longer pull in mallocx.o. - - Changed large object allocation to clear the first and last few words - of each block before releassing the lock. Otherwise the marker could see - objects with nonsensical type descriptors. - - Fixed a couple of subtle problems that could result in not recognizing - interior pointers from the stack. (I believe these were introduced - in 6.0alpha6.) - - GC_debug_free_inner called GC_free, which tried to reacquire the - allocator lock, and hence deadlocked. (DBG_HDRS_ALL probably never worked - with threads?) - - Fixed several problems with back traces. Accidental references to a free - list could cause the free list pointer to be overwritten by a back pointer. - There seemed to be some problems with the encoding of root and finalizer - references. - -Since 6.0alpha7: - - Changed GC_debug_malloc_replacement and GC_debug_realloc_replacement - so that they compile under Irix. (Thanks to Dave Love.) - - Updated powerpc_macosx_mach_dep.s so that it works if the collector - is in a dynamic library. (Thanks to Andrew Begel.) - - Transformed README.debugging into debugging.html, updating and - expanding it in the process. Added gcdescr.html and tree.html - from the web site to the GC distribution. - - Fixed several problems related to PRINT_BLACK_LIST. This involved - restructuring some of the marker macros. - - Fixed some problems with the sizing of objects with debug information. - Finalization was broken KEEP_BACK_PTRS or PRINT_BLACK_LIST. Reduced the - object size with SHORT_DEBUG_HDRS by another word. - - The "Needed to allocate blacklisted ..." warning had inadvertently - been turned off by default, due to a buggy test in allchblk.c. Turned - it back on. - - Removed the marker macros to deal with 2 pointers in interleaved fashion. - They were messy and the performance improvement seemed minimal. We'll - leave such scheduling issues to the compiler. - - Changed Linux/PowerPC test to also check for __powerpc__ in response - to a discussion on the gcc mailing list. - - On Matthew Flatt's suggestion removed the "static" from the jmp_buf - declaration in GC_generic_push_regs. This was causing problems in - systems that register all of their own roots. It looks far more correct - to me without the "static" anyway. - - Fixed several problems with thread local allocation of pointerfree or - typed objects. The collector was reclaiming thread-local free lists, since - it wasn't following the link fields. - - There was apparently a long-standing race condition related to multithreaded - incremental collection. A collection could be started and a thread stopped - between the memory unprotect system call and the setting of the - corresponding dirt bit. I believe this did not affect Solaris or PCR, which - use a different dirty-bit implementation. Fixed this by installing - signal handlers with sigaction instead of signal, and disabling the thread - suspend signal while in the write-protect handler. (It is unclear - whether this scenario ever actually occurred. I found it while tracking - down the following:) - - Incremental collection did not cooperate correctly with the PARALLEL_MARK - implementation of GC_malloc_many or the local_malloc primitves. It still - doesn't work well, but it shouldn't lose memory anymore. - - Integrated some changes from the gcc source tree that I had previously - missed. (Thanks to Bryce McKinley for the reminder/diff.) - - Added Makefile.direct as a copy of the default Makefile, which would - normally be overwritten if configure is run. - - Changed the gc.tar target in Makefile.direct to embed the version number - in the gc directory name. This will affect future tar file distributions. - - Changed the Irix dynamic library finding code to no longer try to - eliminate writable text segments under Irix6.x, since that is probably no - longer necessary, and can apparently be unsafe on occasion. (Thanks to - Shiro Kawai for pointing this out.) - - GC_cleanup with GC_DEBUG enabled passed a real object base address to - GC_debug_register_finalizer_ignore_self, which expected a pointer past the - debug header. Call GC_register_finalizer_ignore_self instead, even with - debugging enabled. (Thanks to Jean-Daniel Fekete for catching this.) - - The collector didn't build with call chain saving enabled but NARGS=0. - (Thanks to Maarten Thibaut.) - - Fixed up the GNU-style build files enough so that they work in some - obvious cases. - - Added initial port to Digital Mars compiler for win32. (Thanks to Walter - Bright.) - -Since 6.0alpha8: - - added README.macros. - - Made gc.mak a symbolic link to work around winzip's tendency to ignore - hard links. - - Simplified the setting of NEED_FIND_LIMIT in os_dep.c, possibly breaking - it on untested platforms. - - Integrated initial GNU HURD port. (Thanks to Chris Lingard and Igor - Khavkine.) - - A few more fixes for Digital Mars compiler (Walter Bright). - - Fixed gcc version recognition. Renamed OPERATOR_NEW_ARRAY to - GC_OPERATOR_NEW_ARRAY. Changed GC_OPERATOR_NEW_ARRAY to be the default. - It can be overridden with -DGC_NO_OPERATOR_NEW_ARRAY. (Thanks to - Cesar Eduardo Barros.) - - Changed the byte size to free-list mapping in thread local allocation - so that size 0 allocations are handled correctly. - - Fixed Linux/MIPS stackbottom for new toolchain. (Thanks to Ryan Murray.) - - Changed finalization registration to invoke GC_oom_fn when it runs out - of memory. - - Removed lvalue cast in finalize.c. This caused some debug configurations - not to build with some non-gcc compilers. - -Since 6.0alpha9: - - Two more bug fixes for KEEP_BACK_PTRS and DBG_HDRS_ALL. - - Fixed a stack clearing problem that resulted in SIGILL with a - misaligned stack pointer for multithreaded SPARC builds. - - Integrated another HURD patch (thanks to Igor Khavkine). - -Since 6.0: - - Non-debug, atomic allocations could result in bogus smashed object - reports with debugging on. (Thanks to Patrick Doyle for the small - test case.) - - Fixed GC_get_register_stack_base (Itanium only) to work around a glibc - 2.2.4 bug. - - Initial port to HP/UX on Itanium. Thread support and both 32 and 64 - bit ABIs appear to work. Parallel mark support doesn't yet, due to - some inline assembly code issues. Thread local allocation does appear - to work. - - ifdef'ed out glibc2.1/Itanium workaround. I suspect nobody is using - that combination anymore. - - Added a patch to make new_gc_alloc.h usable with gcc3.0. (Thanks to - Dimitris Vyzovitis for the patch.) - - Debugged 64-bit support on HP/UX PA-RISC. - - Turned on dynamic loading support for FreeBSD/ELF. (Thanks to Peter - Housel.) - - Unregistering of finalizers with debugging allocation was broken. - (Thanks to Jani Kajala for the test case.) - - Old finalizers were not returned correctly from GC_debug_register_finalizer. - - Disabled MPROTECT_VDB for Linux/M68K based on a report that it doesn't work. - - Cleaned up some statistics gathering code in reclaim.c (Thanks to Walter - Bright.) - - Added some support for OpenBSD/ELF/Linux. (Thanks to Suzuki Toshiya.) - - Added Jakub Jelinek's patch to use dl_iterate_phdr for dynamic library - traversal to dyn_load.c. Changed it to weakly reference dl_iterate_phdr, - so that the old code is stilll used with old versions of glibc. - - Cleaned up feature test macros for various threads packages and - integrated (partially functional) FreeBSD threads code from Loren Rittle. - It's likely that the cleanup broke something, since it touched lots of - code. It's also likelly that it fixed some unreported bugs in the - less common thread implementations, since some of the original code - didn't stand up to close scrutiny. Support for the next pthreads - implementation should be easier to add. - -Since 6.1alpha1: - - No longer wrap read by default in multithreaded applications. It was - pointed out on the libgcj list that this holds the allocation lock for - way too long if the read blocks. For now, reads into the heap are - broken with incremental collection. It's possible to turn this back on - if you make sure that read calls don't block (e.g. by calling select - first). - - Fix ifdef in Solaris_threads.h to refer to GC_SOLARIS_THREADS. - - Added check for environment variable GC_IGNORE_GCJ_INFO. - - Added printing of stop-the-world GC times if GC_PRINT_STATS environment - variable is set. - - The calloc definition in leak_detector.h was missing parentheses, and - realloc was missing a second argument to GC_REALLOC. - (Thanks to Elrond (elrond<at>samba-tng.org).) - - Added GC_PRINT_BACK_HEIGHT environment variable and associated - code, mostly in the new file backgraph.c. See doc/README.environment. - - Added -DUSE_GLOBAL_ALLOC to work around a Windows NT issue. (Thanks to - Jonathan Clark.) - - Integrated port to NEC EWS4800 (MIPS-based workstation, with somewhat - different address-space layout). This may help for other machines with - holes in the data segment. (Thanks to Hironori Sakamoto.) - - Changed the order in which GC_push_roots and friends push things onto - the mark stack. GC_push_all calls need to come first, since we can't - necessarily recovere if those overflow the mark stack. (Thanks to - Matthew Flatt for tracking down the problem.) - - Some minor cleanups to mostly support the Intel compiler on Linux/IA64. - -Since 6.1 alpha2: - - Minor cleanup on the gcconfig.h section for SPARC. - - Minor fix to support Intel compiler for I386/Linux. (Thanks to Sven - Hartrumpf.) - - Added SPARC V9 (64-bit) support. (Thanks to Jeff Sturm.) - - Restructured the way in which we determine whether or not to keep - call stacks for debug allocation. By default SAVE_CALL_COUNT is - now zero on all platforms. Added SAVE_CALL_NARGS parameters. - If possible, use execinfo.h to capture call stack. (This should - add support for a number of new platforms, though often at - considerable runtime expense.) - - Try to print symbolic information for call stacks. On Linux, we - do this with a combination of execinfo.h and running addr2line in - a separate process. This is both much more expensive and much more - useful. Amazingly, it seems to be fast enough for most purposes. - - Redefined strdup if -DREDIRECT_MALLOC is given. - - Changed incremental collector and MPROTECT_VDB implementation so that, - under favorable conditions, pointerfree objects are not protected. - Added GC_incremental_protection_needs() to determine ahead of time whether - pointerfree objects may be protected. Replaced GC_write_hint() with - GC_remove_protection(). - - Added test for GC_ENABLE_INCREMENTAL environment variable. - - Made GC_time_limit runtime configurable. Added GC_PAUSE_TIME_TARGET - environment variable. - - Eliminated GC_page_sz, a duplicate of GC_page_size. - - Caused the Solaris and Irix thread creation primitives to call - GC_init_inner(). - -Since 6.1alpha3: - - Fixed typo in sparc_mach_dep.S, preventing the 64-bit version from - building. Increased 64-bit heap size limit in test.c slightly, since - a functional SPARC collector seems to slightly exceed the old limits. - (Thanks again to Jeff Sturm.) - - Use NPRGREG in solaris_threads.c, thus printing all registers if things - go wrong. - - Added GC_MARKERS environment variable to allow use of a single marker - thread on an MP without confusing the lock implementation. - - Collect much less aggressively in incremental mode with GC_TIME_UNLIMITED. - This is really a purely generational mode, and we can afford to - postpone the collection until the heap is (nearly) full. - - Remove read() wrapper for MPROTECT_VDB. It was causing more harm than - good. It is often no longer needed if system calls avoid writing to - pointerfull heap objects. - - Fix MACOSX test in gcconfig.h. (Thanks to John Clements.) - - Change GC_test_and_set so that it consistently has one argument. - Add spaces to ::: in powerpc assembly code in gc_locks.h. - (Thanks to Ryan Murray.) - - Fixed a formatting error in dbg_mlc.c. Added prototype to GC_abort() - declaration. (Thanks to Michael Smith.) - - Removed "source" argument to GC_find_start(). Eliminate GC_FIND_START(). - - Added win32 recognition code in configure.in. Changed some of the - dllimport/export defines in gc.h. (Thanks to Adam Megacz.) - - GC_malloc_many didn't set hb_last_reclaimed when it called - GC_reclaim_generic. (I'm not sure this matters much, but ...) - - Allocating uncollectable objects with debug information sometimes - allocated objects that were one byte too small, since uncollectable - objects don't have the extra byte added at the end. (Thanks to - Wink Saville for pointing this out.) - - Added a bit more assertion checking to make sure that gcj objects - on free lists never have a nonzero second word. - - Replaced BCC_MAKEFILE with an up-to-date one. (Thanks to - Andre Leiradella.) - - Upgraded libtool, cinfigure.in and some related files to hopefully - support NetBSD/SPARC. (Thanks to Adrian Bunk.) Unfortunately, - libtool 1.4.2 seemed to be buggy due to missing quotes in several - "test" invocations. Fixed those in the ltmain.sh script. - - Some win32-specific patches, including the introduction of - GC_CreateThread. (Thanks to Adam Megacz.) - - Merged in gcj changes from Anthony Green to support embedded systems. - - Tried to consistently rename preprocessed assembly files with a capital - .S extension. - - Use alpha_mach_dep.S on ALPHA again. It doesn't really matter, but this - makes our distribution consistent with the gcc one, avoiding future merge - problems. - - Move GET_MEM definition into gcconfig.h. Include gcconfig.h slightly - later in gc_priv.h to avoid forward references to ptr_t. - - Add some testing of local allocation to test.c. - - Change definition of INVALID_QTID in specific.h. The -1 value was used - inconsistently, and too likely to collide with a valid stack address. - Some general clean-up of specific.[ch]. Added assertions. (Thanks - to Michael Smith for tracking down an intermittent bug to this - general area. I'm not sure it has been squashed yet, however.) - - On Pthread systems it was not safe to call GC_malloc() between fork() - and exec(). According to the applicable standards, it doesn't appear - to be safe to call malloc() or many other libc functions either, thus - it's not clear this is fixable. Added experimental support for - -DHANDLE_FORK in linux_threads.c which tries to support it. It may - succeed if libc does the right thing. I'm not sure whether it does. - (Thanks to Kenneth Schalk for pointing out this issue.) - - Documented thread local allocation primitives to require an - explicit GC_init call. GC_init_parallel is no longer declared to - be a constructor function, since that isn't portable and often - seems to lead to initialization order problems. - - Changed gc_cpp.cc and gc_cpp.h in one more attempt to make them - compatible with Visual C++ 6. (Thanks to Wink Saville for the - patch.) - - Some more patches for Linux on HP PA-RISC. - - Added include/gc_allocator.h. It implements (hopefully) standard - conforming (as opposed to SGI-style) allocators that allocate - collectable (gc_allocator) or GC-traceable, but not collectable - (traceable_allocator) objects. This borrows heavily from libstc++, - which borrows heavily from the SGI implementation, this part of - which was written by Matt Austern. Changed test_cpp.cc to very - minimally test this. - - On Linux/X86, retry mmap with a different start argument. That should - allow the collector to use more (closer to 3GB) of the address space. - (Thanks to Jeffrey Mark Siskind for tracking this down.) - - Force 64 bit alignment with GCJ support. (Reflects Bryce McKinley's - patch to the gcc tree.) - - Refined the choice of sa_handler vs. sa_sigaction in GC_dirty_init - to accomodate some glibc5 systems. (Thanks to Dan Fandrich for the - patch.) - - Compensated for the fact that current versions of glibc set - __libc_stack_end incorrectly on Linux/IA64 while initialization code - is running. This could cause the collector to miss 16 bytes of - the memory stack if GC_malloc or friends where called before main(). - - Mostly integrated Takis Psarogiannakopoulos' port to DG/UX Inix 86. - This will probably take another iteration to work, since his - patch conflicted with the libtool upgrade. - - Added README.arm.cross containing some information about cross- - compiling to an ARM processor from Margaret Fleck. - -Since 6.1alpha4: - - Added GC_finalizer_mem_freed, and changed some of the code that - decided on heap expansion to look at it. Memory explicitly - deallocated by finalizers essentially needs to be counted as reclaimed - by the GC. Otherwise there are cases in which the heap can grow - unboundedly. (Thanks to Mark Reichert for the test case.) - - Integrated Adam Megacz patches to not scan dynamic libraries if - we are compiling with gcc on win32. Otherwise we need structured - exception handling to deal with asynchronously unmapped root - segments, and gcc doesn't directly support that. - - Integrated Anthony Green's patch to support Wine. - - GC_OPERATOR_NEW_ARRAY was misspelled OPERATOR_NEW_ARRAY in several - places, including gc_cpp.cc. (Thanks to Wink Saville for pointing - this out.) - - Integrated Loren James Rittle's Alpha FreeBSD patches. In - response to Richard Henderson's suggestion, these also - changed the declarations of symbols like _end on many platforms to - that they wouldn't mistakenly be declared as short data symbols. - - Integrated changes from the Debian distribution. (Thanks to Ryan Murray - for pointing these out.) Fix C++ comments in POWERPC port. Add ARM32 - incremental GC support. Get rid of USE_GENERIC_PUSH_REGS for alpha/Linux, - this time for real. Use va_copy to get rid of cord printf problems - (finally). - - Close file descriptor used to count cpus. Thanks to Jeff Sturm for - pointing out the omission. - - Don't just drop gcj free lists in GC_start_reclaim, since that can - eventually cause the marker to see a bogus mark descriptor in the - dropped objects. The usual symptom was a very intermittent segmentation - fault in the marker. This mattered only if one of the GC_gcj_malloc - variants was used. (Thanks to Michael Smith, Jeff Sturm, Bryce - McKinley and Tom Tromey for helping to track this down.) - - Fixed Linux and Solaris/64 SPARC configuration. (Thanks to David Miller, - Jeff Sturm, Tom Tromey, and Christian Joensson.) - - Fixed a typo in strdup definition. (Thanks to Gerard A Allan.) - - Changed Makefile.direct to invoke $(CC) to assemble alpha_mach_dep.S. - This is needed on Linux. I'm not sure whether it's better or worse - on Tru64. - - Changed gc_cpp.h once more to declare operator new and friends only in - a Microsoft environment. This may need further fine tuning. (Thanks to - Johannes Schmidt for pointing out that the older code breaks on gcc3.0.4.) - - Don't ever override strdup if it's already macro defined. (Thanks to - Adnan Ali for pointing out the problem.) - - Changed gc_cpp.h yet again to also overload placement new. Due to the - C++ overloading rules, the other overloaded new operations otherwise hide - placement new, which causes many STL uses to break. (Thanks to Reza - Shahidi for reporting this, and to Matt Austern for proposing a fix.) - - Integrated cygwin pthreads support from Dan Bonachea. - - Turn on DYNAMIC_LOADING for NetBSD. (Thanks to Krister Walfridsson.) - - Changed printing code to print more complete GC times. - - Applied Mark Mitchell's Irix patch to correct some bitrot. - - Clarified which object-printing routines in dbg_mlc.c should hold - the allocation lock. Restructured the code to allow reasonable object - printing with -DREDIRECT_MALLOC. - - Fix the Linux mmap code to always start with 0x1000 as the initial hint. - Minor patches for 64-bit AIX, particularly to STACKBOTTOM. - (Thanks again to Jeffrey Mark Siskind.) - - Renamed "SUSPENDED" flag for Solaris threads support to avoid a conflict - with a system header. (Thanks to Philp Brown.) - - -To do: - - --enable-redirect-malloc is mostly untested and known not to work - on some platforms. - - The win32 collector ends up tracing some (most?) objects allocated with - the system allocator, in spite if the fact that it tries not to. - This costs time and space, though it remains correct. - We need a way to identify memory regions used by the system malloc(), - or an alternate way to locate dll data areas. A very partial - workaround is to use GC_malloc_atomic_uncollectable() instead of - the system malloc() for most allocation. - - There seem to be outstanding issues on Solaris/X86, possibly with - finding the data segment starting address. Information/patches would - be appreciated. - - Very large root set sizes (> 16 MB or so) could cause the collector - to abort with an unexpected mark stack overflow. (Thanks again to - Peter Chubb.) NOT YET FIXED. Workaround is to increase the initial - size. - - The SGI version of the collector marks from mmapped pages, even - if they are not part of dynamic library static data areas. This - causes performance problems with some SGI libraries that use mmap - as a bitmap allocator. NOT YET FIXED. It may be possible to turn - off DYNAMIC_LOADING in the collector as a workaround. It may also - be possible to conditionally intercept mmap and use GC_exclude_static_roots. - The real fix is to walk rld data structures, which looks possible. - - Incremental collector should handle large objects better. Currently, - it looks like the whole object is treated as dirty if any part of it - is. - diff --git a/gc/doc/README.contributors b/gc/doc/README.contributors deleted file mode 100644 index fd5c95f..0000000 --- a/gc/doc/README.contributors +++ /dev/null @@ -1,57 +0,0 @@ -This is an attempt to acknowledge early contributions to the garbage -collector. Later contributions should instead be mentioned in -README.changes. - -HISTORY - - - Early versions of this collector were developed as a part of research -projects supported in part by the National Science Foundation -and the Defense Advance Research Projects Agency. - -The garbage collector originated as part of the run-time system for -the Russell programming language implementation. The first version of the -garbage collector was written primarily by Al Demers. It was then refined -and mostly rewritten, primarily by Hans-J. Boehm, at Cornell U., -the University of Washington, Rice University (where it was first used for -C and assembly code), Xerox PARC, SGI, and HP Labs. However, significant -contributions have also been made by many others. - -Some other contributors: - -More recent contributors are mentioned in the modification history in -README.changes. My apologies for any omissions. - -The SPARC specific code was originally contributed by Mark Weiser. -The Encore Multimax modifications were supplied by -Kevin Kenny (kenny@m.cs.uiuc.edu). The adaptation to the IBM PC/RT is largely -due to Vernon Lee, on machines made available to Rice by IBM. -Much of the HP specific code and a number of good suggestions for improving the -generic code are due to Walter Underwood. -Robert Brazile (brazile@diamond.bbn.com) originally supplied the ULTRIX code. -Al Dosser (dosser@src.dec.com) and Regis Cridlig (Regis.Cridlig@cl.cam.ac.uk) -subsequently provided updates and information on variation between ULTRIX -systems. Parag Patel (parag@netcom.com) supplied the A/UX code. -Jesper Peterson(jep@mtiame.mtia.oz.au), Michel Schinz, and -Martin Tauchmann (martintauchmann@bigfoot.com) supplied the Amiga port. -Thomas Funke (thf@zelator.in-berlin.de(?)) and -Brian D.Carlstrom (bdc@clark.lcs.mit.edu) supplied the NeXT ports. -Douglas Steel (doug@wg.icl.co.uk) provided ICL DRS6000 code. -Bill Janssen (janssen@parc.xerox.com) supplied the SunOS dynamic loader -specific code. Manuel Serrano (serrano@cornas.inria.fr) supplied linux and -Sony News specific code. Al Dosser provided Alpha/OSF/1 code. He and -Dave Detlefs(detlefs@src.dec.com) also provided several generic bug fixes. -Alistair G. Crooks(agc@uts.amdahl.com) supplied the NetBSD and 386BSD ports. -Jeffrey Hsu (hsu@soda.berkeley.edu) provided the FreeBSD port. -Brent Benson (brent@jade.ssd.csd.harris.com) ported the collector to -a Motorola 88K processor running CX/UX (Harris NightHawk). -Ari Huttunen (Ari.Huttunen@hut.fi) generalized the OS/2 port to -nonIBM development environments (a nontrivial task). -Patrick Beard (beard@cs.ucdavis.edu) provided the initial MacOS port. -David Chase, then at Olivetti Research, suggested several improvements. -Scott Schwartz (schwartz@groucho.cse.psu.edu) supplied some of the -code to save and print call stacks for leak detection on a SPARC. -Jesse Hull and John Ellis supplied the C++ interface code. -Zhong Shao performed much of the experimentation that led to the -current typed allocation facility. (His dynamic type inference code hasn't -made it into the released version of the collector, yet.) - diff --git a/gc/doc/README.cords b/gc/doc/README.cords deleted file mode 100644 index 3485e01..0000000 --- a/gc/doc/README.cords +++ /dev/null @@ -1,53 +0,0 @@ -Copyright (c) 1993-1994 by Xerox Corporation. All rights reserved. - -THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED -OR IMPLIED. ANY USE IS AT YOUR OWN RISK. - -Permission is hereby granted to use or copy this program -for any purpose, provided the above notices are retained on all copies. -Permission to modify the code and to distribute modified code is granted, -provided the above notices are retained, and a notice that the code was -modified is included with the above copyright notice. - -Please send bug reports to Hans-J. Boehm (Hans_Boehm@hp.com or -boehm@acm.org). - -This is a string packages that uses a tree-based representation. -See cord.h for a description of the functions provided. Ec.h describes -"extensible cords", which are essentially output streams that write -to a cord. These allow for efficient construction of cords without -requiring a bound on the size of a cord. - -More details on the data structure can be found in - -Boehm, Atkinson, and Plass, "Ropes: An Alternative to Strings", -Software Practice and Experience 25, 12, December 1995, pp. 1315-1330. - -A fundamentally similar "rope" data structure is also part of SGI's standard -template library implementation, and its descendents, which include the -GNU C++ library. That uses reference counting by default. -There is a short description of that data structure at -http://reality.sgi.com/boehm/ropeimpl.html . (The more official location -http://www.sgi.com/tech/stl/ropeimpl.html is missing a figure.) - -All of these are descendents of the "ropes" in Xerox Cedar. - -de.c is a very dumb text editor that illustrates the use of cords. -It maintains a list of file versions. Each version is simply a -cord representing the file contents. Nonetheless, standard -editing operations are efficient, even on very large files. -(Its 3 line "user manual" can be obtained by invoking it without -arguments. Note that ^R^N and ^R^P move the cursor by -almost a screen. It does not understand tabs, which will show -up as highlighred "I"s. Use the UNIX "expand" program first.) -To build the editor, type "make cord/de" in the gc directory. - -This package assumes an ANSI C compiler such as gcc. It will -not compile with an old-style K&R compiler. - -Note that CORD_printf iand friends use C functions with variable numbers -of arguments in non-standard-conforming ways. This code is known to -break on some platforms, notably PowerPC. It should be possible to -build the remainder of the library (everything but cordprnt.c) on -any platform that supports the collector. - diff --git a/gc/doc/README.dj b/gc/doc/README.dj deleted file mode 100644 index 613bc42..0000000 --- a/gc/doc/README.dj +++ /dev/null @@ -1,12 +0,0 @@ -[Original version supplied by Xiaokun Zhu <xiaokun@aero.gla.ac.uk>] -[This version came mostly from Gary Leavens. ] - -Look first at Makefile.dj, and possibly change the definitions of -RM and MV if you don't have rm and mv installed. -Then use Makefile.dj to compile the garbage collector. -For example, you can do: - - make -f Makefile.dj test - -All the tests should work fine. - diff --git a/gc/doc/README.environment b/gc/doc/README.environment deleted file mode 100644 index dc17209..0000000 --- a/gc/doc/README.environment +++ /dev/null @@ -1,101 +0,0 @@ -The garbage collector looks at a number of environment variables which are -then used to affect its operation. These are examined only on Un*x-like -platforms. - -GC_INITIAL_HEAP_SIZE=<bytes> - Initial heap size in bytes. May speed up - process start-up. - -GC_LOOP_ON_ABORT - Causes the collector abort routine to enter a tight loop. - This may make it easier to debug, such a process, especially - for multithreaded platforms that don't produce usable core - files, or if a core file would be too large. On some - platforms, this also causes SIGSEGV to be caught and - result in an infinite loop in a handler, allowing - similar debugging techniques. - -GC_PRINT_STATS - Turn on as much logging as is easily feasible without - adding signifcant runtime overhead. Doesn't work if - the collector is built with SMALL_CONFIG. Overridden - by setting GC_quiet. On by default if the collector - was built without -DSILENT. - -GC_PRINT_ADDRESS_MAP - Linux only. Dump /proc/self/maps, i.e. various address - maps for the process, to stderr on every GC. Useful for - mapping root addresses to source for deciphering leak - reports. - -GC_NPROCS=<n> - Linux w/threads only. Explicitly sets the number of processors - that the GC should expect to use. Note that setting this to 1 - when multiple processors are available will preserve - correctness, but may lead to really horrible performance, - since the lock implementation will immediately yield without - first spinning. - -GC_MARKERS=<n> - Linux w/threads and parallel marker only. Set the number - of marker threads. This is normaly set to the number of - processors. It is safer to adjust GC_MARKERS than GC_NPROCS, - since GC_MARKERS has no impact on the lock implementation. - -GC_NO_BLACKLIST_WARNING - Prevents the collector from issuing - warnings about allocations of very large blocks. - Deprecated. Use GC_LARGE_ALLOC_WARN_INTERVAL instead. - -GC_LARGE_ALLOC_WARN_INTERVAL=<n> - Print every nth warning about very large - block allocations, starting with the nth one. Small values - of n are generally benign, in that a bounded number of - such warnings generally indicate at most a bounded leak. - For best results it should be set at 1 during testing. - Default is 5. Very large numbers effectively disable the - warning. - -GC_IGNORE_GCJ_INFO - Ignore the type descriptors implicitly supplied by - GC_gcj_malloc and friends. This is useful for debugging - descriptor generation problems, and possibly for - temporarily working around such problems. It forces a - fully conservative scan of all heap objects except - those known to be pointerfree, and may thus have other - adverse effects. - -GC_PRINT_BACK_HEIGHT - Print max length of chain through unreachable objects - ending in a reachable one. If this number remains - bounded, then the program is "GC robust". This ensures - that a fixed number of misidentified pointers can only - result in a bounded space leak. This currently only - works if debugging allocation is used throughout. - It increases GC space and time requirements appreciably. - This feature is still somewhat experimental, and requires - that the collector have been built with MAKE_BACK_GRAPH - defined. For details, see Boehm, "Bounding Space Usage - of Conservative Garbage Collectors", POPL 2001, or - http://lib.hpl.hp.com/techpubs/2001/HPL-2001-251.html . - -The following turn on runtime flags that are also program settable. Checked -only during initialization. We expect that they will usually be set through -other means, but this may help with debugging and testing: - -GC_ENABLE_INCREMENTAL - Turn on incremental collection at startup. Note that, - depending on platform and collector configuration, this - may involve write protecting pieces of the heap to - track modifications. These pieces may include pointerfree - objects or not. Although this is intended to be - transparent, it may cause unintended system call failures. - Use with caution. - -GC_PAUSE_TIME_TARGET - Set the desired garbage collector pause time in msecs. - This only has an effect if incremental collection is - enabled. If a collection requires appreciably more time - than this, the client will be restarted, and the collector - will need to do additional work to compensate. The - special value "999999" indicates that pause time is - unlimited, and the incremental collector will behave - completely like a simple generational collector. If - the collector is configured for parallel marking, and - run on a multiprocessor, incremental collection should - only be used with unlimited pause time. - -GC_FIND_LEAK - Turns on GC_find_leak and thus leak detection. - -GC_ALL_INTERIOR_POINTERS - Turns on GC_all_interior_pointers and thus interior - pointer recognition. - -GC_DONT_GC - Turns off garbage collection. Use cautiously. diff --git a/gc/doc/README.ews4800 b/gc/doc/README.ews4800 deleted file mode 100644 index 80bca2b..0000000 --- a/gc/doc/README.ews4800 +++ /dev/null @@ -1,81 +0,0 @@ -GC on EWS4800 -------------- - -1. About EWS4800 - EWS4800 is 32bit/64bit workstation. - - Vender: NEC Corporation - OS: UX/4800 R9.* - R13.* (SystemV R4.2) - CPU: R4000, R4400, R10000 (MIPS) - -2. Compiler - - 32bit: - Use ANSI C compiler. - CC = /usr/abiccs/bin/cc - - 64bit: - Use 64bit ANSI C compiler. - CC = /usr/ccs64/bin/cc - AR = /usr/ccs64/bin/ar - -3. ELF file format - *** Caution: The following infomation is empirical. *** - - 32bit: - ELF file has an unique format. (See a.out(4) and end(3C).) - - &_start - : text segment - &etext - DATASTART - : data segment (initialized) - &edata - DATASTART2 - : data segment (uninitialized) - &end - - Here, DATASTART and DATASTART2 are macros of GC, and are defined as - the following equations. (See include/private/gcconfig.h.) - The algorithm for DATASTART is similar with the function - GC_SysVGetDataStart() in os_dep.c. - - DATASTART = ((&etext + 0x3ffff) & ~0x3ffff) + (&etext & 0xffff) - - Dynamically linked: - DATASTART2 = (&_gp + 0x8000 + 0x3ffff) & ~0x3ffff - - Statically linked: - DATASTART2 = &edata - - GC has to check addresses both between DATASTART and &edata, and - between DATASTART2 and &end. If a program accesses between &etext - and DATASTART, or between &edata and DATASTART2, the segmentation - error occurs and the program stops. - - If a program is statically linked, there is not a gap between - &edata and DATASTART2. The global symbol &_DYNAMIC_LINKING is used - for the detection. - - 64bit: - ELF file has a simple format. (See end(3C).) - - _ftext - : text segment - _etext - _fdata = DATASTART - : data segment (initialized) - _edata - _fbss - : data segment (uninitialized) - _end = DATAEND - --- -Hironori SAKAMOTO <hsaka@mth.biglobe.ne.jp> - - -When using the new "configure; make" build process, please -run configure with the --disable-shared option. "Make check" does not -yet pass with dynamic libraries. Ther reasons for that are not yet -understood. (HB, paraphrasing message from Hironori SAKAMOTO.) - diff --git a/gc/doc/README.hp b/gc/doc/README.hp deleted file mode 100644 index caa8bdd..0000000 --- a/gc/doc/README.hp +++ /dev/null @@ -1,18 +0,0 @@ -Dynamic loading support requires that executables be linked with -ldld. -The alternative is to build the collector without defining DYNAMIC_LOADING -in gcconfig.h and ensuring that all garbage collectable objects are -accessible without considering statically allocated variables in dynamic -libraries. - -The collector should compile with either plain cc or cc -Ae. Cc -Aa -fails to define _HPUX_SOURCE and thus will not configure the collector -correctly. - -Incremental collection support was reccently added, and should now work. - -In spite of past claims, pthread support under HP/UX 11 should now work. -Define GC_HPUX_THREADS for the build. Incremental collection still does not -work in combination with it. - -The stack finding code can be confused by putenv calls before collector -initialization. Call GC_malloc or GC_init before any putenv calls. diff --git a/gc/doc/README.linux b/gc/doc/README.linux deleted file mode 100644 index efd0a26..0000000 --- a/gc/doc/README.linux +++ /dev/null @@ -1,135 +0,0 @@ -See README.alpha for Linux on DEC AXP info. - -This file applies mostly to Linux/Intel IA32. Ports to Linux on an M68K -and PowerPC are also integrated. They should behave similarly, except that -the PowerPC port lacks incremental GC support, and it is unknown to what -extent the Linux threads code is functional. See below for M68K specific -notes. - -Incremental GC is supported on Intel IA32 and M68K. - -Dynamic libraries are supported on an ELF system. A static executable -should be linked with the gcc option "-Wl,-defsym,_DYNAMIC=0". - -The collector appears to work with Linux threads. We have seen -intermittent hangs in sem_wait. So far we have been unable to reproduce -these unless the process was being debugged or traced. Thus it's -possible that the only real issue is that the debugger loses -signals on rare occasions. - -The garbage collector uses SIGPWR and SIGXCPU if it is used with -Linux threads. These should not be touched by the client program. - -To use threads, you need to abide by the following requirements: - -1) You need to use LinuxThreads (which are included in libc6). - - The collector relies on some implementation details of the LinuxThreads - package. It is unlikely that this code will work on other - pthread implementations (in particular it will *not* work with - MIT pthreads). - -2) You must compile the collector with -DGC_LINUX_THREADS and -D_REENTRANT - specified in the Makefile. - -3a) Every file that makes thread calls should define GC_LINUX_THREADS and - _REENTRANT and then include gc.h. Gc.h redefines some of the - pthread primitives as macros which also provide the collector with - information it requires. - -3b) A new alternative to (3a) is to build the collector and compile GC clients - with -DGC_USE_LD_WRAP, and to link the final program with - - (for ld) --wrap read --wrap dlopen --wrap pthread_create \ - --wrap pthread_join --wrap pthread_detach \ - --wrap pthread_sigmask --wrap sleep - - (for gcc) -Wl,--wrap -Wl,read -Wl,--wrap -Wl,dlopen -Wl,--wrap \ - -Wl,pthread_create -Wl,--wrap -Wl,pthread_join -Wl,--wrap \ - -Wl,pthread_detach -Wl,--wrap -Wl,pthread_sigmask \ - -Wl,--wrap -Wl,sleep - - In any case, _REENTRANT should be defined during compilation. - -4) Dlopen() disables collection during its execution. (It can't run - concurrently with the collector, since the collector looks at its - data structures. It can't acquire the allocator lock, since arbitrary - user startup code may run as part of dlopen().) Under unusual - conditions, this may cause unexpected heap growth. - -5) The combination of GC_LINUX_THREADS, REDIRECT_MALLOC, and incremental - collection fails in seemingly random places. This hasn't been tracked - down yet, but is perhaps not completely astonishing. The thread package - uses malloc, and thus can presumably get SIGSEGVs while inside the - package. There is no real guarantee that signals are handled properly - at that point. - -6) Thread local storage may not be viewed as part of the root set by the - collector. This probably depends on the linuxthreads version. For the - time being, any collectable memory referenced by thread local storage should - also be referenced from elsewhere, or be allocated as uncollectable. - (This is really a bug that should be fixed somehow.) - - -M68K LINUX: -(From Richard Zidlicky) -The bad news is that it can crash every linux-m68k kernel on a 68040, -so an additional test is needed somewhere on startup. I have meanwhile -patches to correct the problem in 68040 buserror handler but it is not -yet in any standard kernel. - -Here is a simple test program to detect whether the kernel has the -problem. It could be run as a separate check in configure or tested -upon startup. If it fails (return !0) than mprotect can't be used -on that system. - -/* - * test for bug that may crash 68040 based Linux - */ - -#include <sys/mman.h> -#include <signal.h> -#include <unistd.h> -#include <stdio.h> -#include <stdlib.h> - - -char *membase; -int pagesize=4096; -int pageshift=12; -int x_taken=0; - -int sighandler(int sig) -{ - mprotect(membase,pagesize,PROT_READ|PROT_WRITE); - x_taken=1; -} - -main() -{ - long l; - - signal(SIGSEGV,sighandler); - l=(long)mmap(NULL,pagesize,PROT_READ,MAP_PRIVATE | MAP_ANON,-1,0); - if (l==-1) - { - perror("mmap/malloc"); - abort(); - } - membase=(char*)l; - *(long*)(membase+sizeof(long))=123456789; - if (*(long*)(membase+sizeof(long)) != 123456789 ) - { - fprintf(stderr,"writeback failed !\n"); - exit(1); - } - if (!x_taken) - { - fprintf(stderr,"exception not taken !\n"); - exit(1); - } - fprintf(stderr,"vmtest Ok\n"); - exit(0); -} - - diff --git a/gc/doc/README.macros b/gc/doc/README.macros deleted file mode 100644 index d9df8dd..0000000 --- a/gc/doc/README.macros +++ /dev/null @@ -1,78 +0,0 @@ -The collector uses a large amount of conditional compilation in order to -deal with platform dependencies. This violates a number of known coding -standards. On the other hand, it seems to be the only practical way to -support this many platforms without excessive code duplication. - -A few guidelines have mostly been followed in order to keep this manageable: - -1) #if and #ifdef directives are properly indented whenever easily possible. -All known C compilers allow whitespace between the "#" and the "if" to make -this possible. ANSI C also allows white space before the "#", though we -avoid that. It has the known disadvantages that it differs from the normal -GNU conventions, and that it makes patches larger than otherwise necessary. -In my opinion, it's still well worth it, for the same reason that we indent -ordinary "if" statements. - -2) Whenever possible, tests are performed on the macros defined in gcconfig.h -instead of directly testing patform-specific predefined macros. This makes it -relatively easy to adapt to new compilers with a different set of predefined -macros. Currently these macros generally identify platforms instead of -features. In many cases, this is a mistake. - -3) The code currently avoids #elif, eventhough that would make it more -readable. This was done since #elif would need to be understood by ALL -compilers used to build the collector, and that hasn't always been the case. -It makes sense to reconsider this decision at some point, since #elif has been -standardized at least since 1989. - -Many of the tested configuration macros are at least somewhat defined in -either include/private/gcconfig.h or in Makefile.direct. Here is an attempt -at defining some of the remainder: (Thanks to Walter Bright for suggesting -this. This is a work in progress) - -MACRO EXPLANATION ------ ----------- - -__DMC__ Always #define'd by the Digital Mars compiler. Expands - to the compiler version number in hex, i.e. 0x810 is - version 8.1b0 - -_ENABLE_ARRAYNEW - #define'd by the Digital Mars C++ compiler when - operator new[] and delete[] are separately - overloadable. Used in gc_cpp.h. - -_MSC_VER Expands to the Visual C++ compiler version. Assumed to - not be defined for other compilers (at least if they behave - appreciably differently). - -_DLL Defined by Visual C++ if dynamic libraries are being built - or used. Used to test whether __declspec(dllimport) or - __declspec(dllexport) needs to be added to declarations - to support the case in which the collector is in a dll. - -GC_DLL User-settable macro that forces the effect of _DLL. - -GC_NOT_DLL User-settable macro that overrides _DLL, e.g. if dynamic - libraries are used, but the collector is in a static library. - -__STDC__ Assumed to be defined only by compilers that understand - prototypes and other C89 features. Its value is generally - not used, since we are fine with most nonconforming extensions. - -SUNOS5SIGS Solaris-like signal handling. This is probably misnamed, - since it really doesn't guarantee much more than Posix. - Currently set only for Solaris2.X, HPUX, and DRSNX. Should - probably be set for some other platforms. - -PCR Set if the collector is being built as part of the Xerox - Portable Common Runtime. - -SRC_M3 Set if the collector is being built as a replacement of the - one in the DEC/Compaq SRC Modula-3 runtime. I suspect this - was last used around 1994, and no doubt broke a long time ago. - It's there primarily incase someone wants to port to a similar - system. - - - diff --git a/gc/doc/README.rs6000 b/gc/doc/README.rs6000 deleted file mode 100644 index f5630b2..0000000 --- a/gc/doc/README.rs6000 +++ /dev/null @@ -1,9 +0,0 @@ -We have so far failed to find a good way to determine the stack base. -It is highly recommended that GC_stackbottom be set explicitly on program -startup. The supplied value sometimes causes failure under AIX 4.1, though -it appears to work under 3.X. HEURISTIC2 seems to work under 4.1, but -involves a substantial performance penalty, and will fail if there is -no limit on stack size. - -There is no thread support. (I assume recent versions of AIX provide -pthreads? I no longer have access to a machine ...) diff --git a/gc/doc/README.sgi b/gc/doc/README.sgi deleted file mode 100644 index 7bdb50a..0000000 --- a/gc/doc/README.sgi +++ /dev/null @@ -1,41 +0,0 @@ -Performance of the incremental collector can be greatly enhanced with --DNO_EXECUTE_PERMISSION. - -The collector should run with all of the -32, -n32 and -64 ABIs. Remember to -define the AS macro in the Makefile to be "as -64", or "as -n32". - -If you use -DREDIRECT_MALLOC=GC_malloc with C++ code, your code should make -at least one explicit call to malloc instead of new to ensure that the proper -version of malloc is linked in. - -Sproc threads are not supported in this version, though there may exist other -ports. - -Pthreads support is provided. This requires that: - -1) You compile the collector with -DGC_IRIX_THREADS specified in the Makefile. - -2) You have the latest pthreads patches installed. - -(Though the collector makes only documented pthread calls, -it relies on signal/threads interactions working just right in ways -that are not required by the standard. It is unlikely that this code -will run on other pthreads platforms. But please tell me if it does.) - -3) Every file that makes thread calls should define IRIX_THREADS and then -include gc.h. Gc.h redefines some of the pthread primitives as macros which -also provide the collector with information it requires. - -4) pthread_cond_wait and pthread_cond_timed_wait should be prepared for -premature wakeups. (I believe the pthreads and realted standards require this -anyway. Irix pthreads often terminate a wait if a signal arrives. -The garbage collector uses signals to stop threads.) - -5) It is expensive to stop a thread waiting in IO at the time the request is -initiated. Applications with many such threads may not exhibit acceptable -performance with the collector. (Increasing the heap size may help.) - -6) The collector should not be compiled with -DREDIRECT_MALLOC. This -confuses some library calls made by the pthreads implementation, which -expect the standard malloc. - diff --git a/gc/doc/README.solaris2 b/gc/doc/README.solaris2 deleted file mode 100644 index 6ed61dc..0000000 --- a/gc/doc/README.solaris2 +++ /dev/null @@ -1,62 +0,0 @@ -The collector supports both incremental collection and threads under -Solaris 2. The incremental collector normally retrieves page dirty information -through the appropriate /proc calls. But it can also be configured -(by defining MPROTECT_VDB instead of PROC_VDB in gcconfig.h) to use mprotect -and signals. This may result in shorter pause times, but it is no longer -safe to issue arbitrary system calls that write to the heap. - -Under other UNIX versions, -the collector normally obtains memory through sbrk. There is some reason -to expect that this is not safe if the client program also calls the system -malloc, or especially realloc. The sbrk man page strongly suggests this is -not safe: "Many library routines use malloc() internally, so use brk() -and sbrk() only when you know that malloc() definitely will not be used by -any library routine." This doesn't make a lot of sense to me, since there -seems to be no documentation as to which routines can transitively call malloc. -Nonetheless, under Solaris2, the collector now (since 4.12) allocates -memory using mmap by default. (It defines USE_MMAP in gcconfig.h.) -You may want to reverse this decisions if you use -DREDIRECT_MALLOC=... - - -SOLARIS THREADS: - -The collector must be compiled with -DGC_SOLARIS_THREADS (thr_ functions) -or -DGC_SOLARIS_PTHREADS (pthread_ functions) to be thread safe. -It is also essential that gc.h be included in files that call thr_create, -thr_join, thr_suspend, thr_continue, or dlopen. Gc.h macro defines -these to also do GC bookkeeping, etc. Gc.h must be included with -one or both of these macros defined, otherwise -these replacements are not visible. -A collector built in this way way only be used by programs that are -linked with the threads library. - -In this mode, the collector contains various workarounds for older Solaris -bugs. Mostly, these should not be noticeable unless you look at system -call traces. However, it cannot protect a guard page at the end of -a thread stack. If you know that you will only be running Solaris2.5 -or later, it should be possible to fix this by compiling the collector -with -DSOLARIS23_MPROTECT_BUG_FIXED. - -Since 5.0 alpha5, dlopen disables collection temporarily, -unless USE_PROC_FOR_LIBRARIES is defined. In some unlikely cases, this -can result in unpleasant heap growth. But it seems better than the -race/deadlock issues we had before. - -If solaris_threads are used on an X86 processor with malloc redirected to -GC_malloc, it is necessary to call GC_thr_init explicitly before forking the -first thread. (This avoids a deadlock arising from calling GC_thr_init -with the allocation lock held.) - -It appears that there is a problem in using gc_cpp.h in conjunction with -Solaris threads and Sun's C++ runtime. Apparently the overloaded new operator -is invoked by some iostream initialization code before threads are correctly -initialized. As a result, call to thr_self() in garbage collector -initialization segfaults. Currently the only known workaround is to not -invoke the garbage collector from a user defined global operator new, or to -have it invoke the garbage-collector's allocators only after main has started. -(Note that the latter requires a moderately expensive test in operator -delete.) - -Hans-J. Boehm -(The above contains my personal opinions, which are probably not shared -by anyone else.) diff --git a/gc/doc/README.uts b/gc/doc/README.uts deleted file mode 100644 index 6be4966..0000000 --- a/gc/doc/README.uts +++ /dev/null @@ -1,2 +0,0 @@ -Alistair Crooks supplied the port. He used Lexa C version 2.1.3 with --Xa to compile. diff --git a/gc/doc/README.win32 b/gc/doc/README.win32 deleted file mode 100644 index dcccec3..0000000 --- a/gc/doc/README.win32 +++ /dev/null @@ -1,164 +0,0 @@ -The collector has at various times been compiled under Windows 95 & NT, -with the original Microsoft SDK, with Visual C++ 2.0, 4.0, and 6, with -the GNU win32 environment, with Borland 4.5, with Watcom C, and recently -with the Digital Mars compiler. It is likely that some of these have been -broken in the meantime. Patches are appreciated. - -It runs under both win32s and win32, but with different semantics. -Under win32, all writable pages outside of the heaps and stack are -scanned for roots. Thus the collector sees pointers in DLL data -segments. Under win32s, only the main data segment is scanned. -(The main data segment should always be scanned. Under some -versions of win32s, other regions may also be scanned.) -Thus all accessible objects should be accessible from local variables -or variables in the main data segment. Alternatively, other data -segments (e.g. in DLLs) may be registered with the collector by -calling GC_init() and then GC_register_root_section(a), where -a is the address of some variable inside the data segment. (Duplicate -registrations are ignored, but not terribly quickly.) - -(There are two reasons for this. We didn't want to see many 16:16 -pointers. And the VirtualQuery call has different semantics under -the two systems, and under different versions of win32s.) - -Win32 applications compiled with some flavor of gcc currently behave -like win32s applications, in that dynamic library data segments are -not scanned. (Gcc does not directly support Microsoft's "structured -exception handling". It turns out that use of this feature is -unavoidable if you scan arbirtray memory segments obtained from -VirtualQuery.) - -The collector test program "gctest" is linked as a GUI application, -but does not open any windows. Its output appears in the file -"gc.log". It may be started from the file manager. The hour glass -cursor may appear as long as it's running. If it is started from the -command line, it will usually run in the background. Wait a few -minutes (a few seconds on a modern machine) before you check the output. -You should see either a failure indication or a "Collector appears to -work" message. - -The cord test program has not been ported (but should port -easily). A toy editor (cord/de.exe) based on cords (heavyweight -strings represented as trees) has been ported and is included. -It runs fine under either win32 or win32S. It serves as an example -of a true Windows application, except that it was written by a -nonexpert Windows programmer. (There are some peculiarities -in the way files are displayed. The <cr> is displayed explicitly -for standard DOS text files. As in the UNIX version, control -characters are displayed explicitly, but in this case as red text. -This may be suboptimal for some tastes and/or sets of default -window colors.) - -In general -DREDIRECT_MALLOC is unlikely to work unless the -application is completely statically linked. - -The collector normally allocates memory from the OS with VirtualAlloc. -This appears to cause problems under Windows NT and Windows 2000 (but -not Windows 95/98) if the memory is later passed to CreateDIBitmap. -To work around this problem, build the collector with -DUSE_GLOBAL_ALLOC. -This is currently incompatible with -DUSE_MUNMAP. (Thanks to Jonathan -Clark for tracking this down. There's some chance this may be fixed -in 6.1alpha4, since we now separate heap sections with an unused page.) - -For Microsoft development tools, rename NT_MAKEFILE as -MAKEFILE. (Make sure that the CPU environment variable is defined -to be i386.) In order to use the gc_cpp.h C++ interface, all -client code should include gc_cpp.h. - -Clients may need to define GC_NOT_DLL before including gc.h, if the -collector was built as a static library (as it normally is in the -absence of thread support). - -For GNU-win32, use the regular makefile, possibly after uncommenting -the line "include Makefile.DLLs". The latter should be necessary only -if you want to package the collector as a DLL. The GNU-win32 port is -believed to work only for b18, not b19, probably due to linker changes -in b19. This is probably fixable with a different definition of -DATASTART and DATAEND in gcconfig.h. - -For Borland tools, use BCC_MAKEFILE. Note that -Borland's compiler defaults to 1 byte alignment in structures (-a1), -whereas Visual C++ appears to default to 8 byte alignment (/Zp8). -The garbage collector in its default configuration EXPECTS AT -LEAST 4 BYTE ALIGNMENT. Thus the BORLAND DEFAULT MUST -BE OVERRIDDEN. (In my opinion, it should usually be anyway. -I expect that -a1 introduces major performance penalties on a -486 or Pentium.) Note that this changes structure layouts. (As a last -resort, gcconfig.h can be changed to allow 1 byte alignment. But -this has significant negative performance implications.) -The Makefile is set up to assume Borland 4.5. If you have another -version, change the line near the top. By default, it does not -require the assembler. If you do have the assembler, I recommend -removing the -DUSE_GENERIC. - -There is some support for incremental collection. This is -currently pretty simple-minded. Pages are protected. Protection -faults are caught by a handler installed at the bottom of the handler -stack. This is both slow and interacts poorly with a debugger. -Whenever possible, I recommend adding a call to -GC_enable_incremental at the last possible moment, after most -debugging is complete. Unlike the UNIX versions, no system -calls are wrapped by the collector itself. It may be necessary -to wrap ReadFile calls that use a buffer in the heap, so that the -call does not encounter a protection fault while it's running. -(As usual, none of this is an issue unless GC_enable_incremental -is called.) - -Note that incremental collection is disabled with -DSMALL_CONFIG. - -James Clark has contributed the necessary code to support win32 threads. -Use NT_THREADS_MAKEFILE (a.k.a gc.mak) instead of NT_MAKEFILE -to build this version. Note that this requires some files whose names -are more than 8 + 3 characters long. Thus you should unpack the tar file -so that long file names are preserved. To build the garbage collector -test with VC++ from the command line, use - -nmake /F ".\gc.mak" CFG="gctest - Win32 Release" - -This requires that the subdirectory gctest\Release exist. -The test program and DLL will reside in the Release directory. - -This version relies on the collector residing in a dll. - -This version currently supports incremental collection only if it is -enabled before any additional threads are created. -Version 4.13 attempts to fix some of the earlier problems, but there -may be other issues. If you need solid support for win32 threads, you -might check with Geodesic Systems. Their collector must be licensed, -but they have invested far more time in win32-specific issues. - -Hans - -Ivan V. Demakov's README for the Watcom port: - -The collector has been compiled with Watcom C 10.6 and 11.0. -It runs under win32, win32s, and even under msdos with dos4gw -dos-extender. It should also run under OS/2, though this isn't -tested. Under win32 the collector can be built either as dll -or as static library. - -Note that all compilations were done under Windows 95 or NT. -For unknown reason compiling under Windows 3.11 for NT (one -attempt has been made) leads to broken executables. - -Incremental collection is not supported. - -cord is not ported. - -Before compiling you may need to edit WCC_MAKEFILE to set target -platform, library type (dynamic or static), calling conventions, and -optimization options. - -To compile the collector and testing programs use the command: - wmake -f WCC_MAKEFILE - -All programs using gc should be compiled with 4-byte alignment. -For further explanations on this see comments about Borland. - -If gc compiled as dll, the macro ``GC_DLL'' should be defined before -including "gc.h" (for example, with -DGC_DLL compiler option). It's -important, otherwise resulting programs will not run. - -Ivan Demakov (email: ivan@tgrad.nsk.su) - - |