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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. - |