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Diffstat (limited to '')
| -rw-r--r-- | gc/gc_mark.h | 280 |
1 files changed, 280 insertions, 0 deletions
diff --git a/gc/gc_mark.h b/gc/gc_mark.h new file mode 100644 index 0000000..4628323 --- /dev/null +++ b/gc/gc_mark.h @@ -0,0 +1,280 @@ +/* + * Copyright (c) 1991-1994 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. + * + */ +/* Boehm, November 7, 1994 4:56 pm PST */ + +/* + * Declarations of mark stack. Needed by marker and client supplied mark + * routines. To be included after gc_priv.h. + */ +#ifndef GC_MARK_H +# define GC_MARK_H + +/* A client supplied mark procedure. Returns new mark stack pointer. */ +/* Primary effect should be to push new entries on the mark stack. */ +/* Mark stack pointer values are passed and returned explicitly. */ +/* Global variables decribing mark stack are not necessarily valid. */ +/* (This usually saves a few cycles by keeping things in registers.) */ +/* Assumed to scan about PROC_BYTES on average. If it needs to do */ +/* much more work than that, it should do it in smaller pieces by */ +/* pushing itself back on the mark stack. */ +/* Note that it should always do some work (defined as marking some */ +/* objects) before pushing more than one entry on the mark stack. */ +/* This is required to ensure termination in the event of mark stack */ +/* overflows. */ +/* This procedure is always called with at least one empty entry on the */ +/* mark stack. */ +/* Currently we require that mark procedures look for pointers in a */ +/* subset of the places the conservative marker would. It must be safe */ +/* to invoke the normal mark procedure instead. */ +# define PROC_BYTES 100 +/* The real declarations of the following are in gc_priv.h, so that */ +/* we can avoid scanning the following table. */ +/* +typedef struct ms_entry * (*mark_proc)( word * addr, mark_stack_ptr, + mark_stack_limit, env ); + +# define LOG_MAX_MARK_PROCS 6 +# define MAX_MARK_PROCS (1 << LOG_MAX_MARK_PROCS) +extern mark_proc GC_mark_procs[MAX_MARK_PROCS]; +*/ + +extern word GC_n_mark_procs; + +/* Object descriptors on mark stack or in objects. Low order two */ +/* bits are tags distinguishing among the following 4 possibilities */ +/* for the high order 30 bits. */ +#define DS_TAG_BITS 2 +#define DS_TAGS ((1 << DS_TAG_BITS) - 1) +#define DS_LENGTH 0 /* The entire word is a length in bytes that */ + /* must be a multiple of 4. */ +#define DS_BITMAP 1 /* 30 bits are a bitmap describing pointer */ + /* fields. The msb is 1 iff the first word */ + /* is a pointer. */ + /* (This unconventional ordering sometimes */ + /* makes the marker slightly faster.) */ + /* Zeroes indicate definite nonpointers. Ones */ + /* indicate possible pointers. */ + /* Only usable if pointers are word aligned. */ +# define BITMAP_BITS (WORDSZ - DS_TAG_BITS) +#define DS_PROC 2 + /* The objects referenced by this object can be */ + /* pushed on the mark stack by invoking */ + /* PROC(descr). ENV(descr) is passed as the */ + /* last argument. */ +# define PROC(descr) \ + (GC_mark_procs[((descr) >> DS_TAG_BITS) & (MAX_MARK_PROCS-1)]) +# define ENV(descr) \ + ((descr) >> (DS_TAG_BITS + LOG_MAX_MARK_PROCS)) +# define MAX_ENV \ + (((word)1 << (WORDSZ - DS_TAG_BITS - LOG_MAX_MARK_PROCS)) - 1) +# define MAKE_PROC(proc_index, env) \ + (((((env) << LOG_MAX_MARK_PROCS) | (proc_index)) << DS_TAG_BITS) \ + | DS_PROC) +#define DS_PER_OBJECT 3 /* The real descriptor is at the */ + /* byte displacement from the beginning of the */ + /* object given by descr & ~DS_TAGS */ + +typedef struct ms_entry { + word * mse_start; /* First word of object */ + word mse_descr; /* Descriptor; low order two bits are tags, */ + /* identifying the upper 30 bits as one of the */ + /* following: */ +} mse; + +extern word GC_mark_stack_size; + +extern mse * GC_mark_stack_top; + +extern mse * GC_mark_stack; + +word GC_find_start(); + +mse * GC_signal_mark_stack_overflow(); + +# ifdef GATHERSTATS +# define ADD_TO_ATOMIC(sz) GC_atomic_in_use += (sz) +# define ADD_TO_COMPOSITE(sz) GC_composite_in_use += (sz) +# else +# define ADD_TO_ATOMIC(sz) +# define ADD_TO_COMPOSITE(sz) +# endif + +/* Push the object obj with corresponding heap block header hhdr onto */ +/* the mark stack. */ +# define PUSH_OBJ(obj, hhdr, mark_stack_top, mark_stack_limit) \ +{ \ + register word _descr = (hhdr) -> hb_descr; \ + \ + if (_descr == 0) { \ + ADD_TO_ATOMIC((hhdr) -> hb_sz); \ + } else { \ + ADD_TO_COMPOSITE((hhdr) -> hb_sz); \ + mark_stack_top++; \ + if (mark_stack_top >= mark_stack_limit) { \ + mark_stack_top = GC_signal_mark_stack_overflow(mark_stack_top); \ + } \ + mark_stack_top -> mse_start = (obj); \ + mark_stack_top -> mse_descr = _descr; \ + } \ +} + +#ifdef PRINT_BLACK_LIST +# define GC_FIND_START(current, hhdr, source) \ + GC_find_start(current, hhdr, source) +#else +# define GC_FIND_START(current, hhdr, source) \ + GC_find_start(current, hhdr) +#endif + +/* Push the contents of current onto the mark stack if it is a valid */ +/* ptr to a currently unmarked object. Mark it. */ +/* If we assumed a standard-conforming compiler, we could probably */ +/* generate the exit_label transparently. */ +# define PUSH_CONTENTS(current, mark_stack_top, mark_stack_limit, \ + source, exit_label) \ +{ \ + register int displ; /* Displacement in block; first bytes, then words */ \ + register hdr * hhdr; \ + register map_entry_type map_entry; \ + \ + GET_HDR(current,hhdr); \ + if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) { \ + current = GC_FIND_START(current, hhdr, (word)source); \ + if (current == 0) goto exit_label; \ + hhdr = HDR(current); \ + } \ + displ = HBLKDISPL(current); \ + map_entry = MAP_ENTRY((hhdr -> hb_map), displ); \ + if (map_entry == OBJ_INVALID) { \ + GC_ADD_TO_BLACK_LIST_NORMAL(current, source); goto exit_label; \ + } \ + displ = BYTES_TO_WORDS(displ); \ + displ -= map_entry; \ + \ + { \ + register word * mark_word_addr = hhdr -> hb_marks + divWORDSZ(displ); \ + register word mark_word = *mark_word_addr; \ + register word mark_bit = (word)1 << modWORDSZ(displ); \ + \ + if (mark_word & mark_bit) { \ + /* Mark bit is already set */ \ + goto exit_label; \ + } \ + GC_STORE_BACK_PTR((ptr_t)source, (ptr_t)HBLKPTR(current) \ + + WORDS_TO_BYTES(displ)); \ + *mark_word_addr = mark_word | mark_bit; \ + } \ + PUSH_OBJ(((word *)(HBLKPTR(current)) + displ), hhdr, \ + mark_stack_top, mark_stack_limit) \ + exit_label: ; \ +} + +#ifdef PRINT_BLACK_LIST +# define PUSH_ONE_CHECKED(p, ip, source) \ + GC_push_one_checked(p, ip, (ptr_t)(source)) +#else +# define PUSH_ONE_CHECKED(p, ip, source) \ + GC_push_one_checked(p, ip) +#endif + +/* + * Push a single value onto mark stack. Mark from the object pointed to by p. + * P is considered valid even if it is an interior pointer. + * Previously marked objects are not pushed. Hence we make progress even + * if the mark stack overflows. + */ +# define GC_PUSH_ONE_STACK(p, source) \ + if ((ptr_t)(p) >= GC_least_plausible_heap_addr \ + && (ptr_t)(p) < GC_greatest_plausible_heap_addr) { \ + PUSH_ONE_CHECKED(p, TRUE, source); \ + } + +/* + * As above, but interior pointer recognition as for + * normal for heap pointers. + */ +# ifdef ALL_INTERIOR_POINTERS +# define AIP TRUE +# else +# define AIP FALSE +# endif +# define GC_PUSH_ONE_HEAP(p,source) \ + if ((ptr_t)(p) >= GC_least_plausible_heap_addr \ + && (ptr_t)(p) < GC_greatest_plausible_heap_addr) { \ + PUSH_ONE_CHECKED(p,AIP,source); \ + } + +/* + * Mark from one finalizable object using the specified + * mark proc. May not mark the object pointed to by + * real_ptr. That is the job of the caller, if appropriate + */ +# define GC_MARK_FO(real_ptr, mark_proc) \ +{ \ + (*(mark_proc))(real_ptr); \ + while (!GC_mark_stack_empty()) GC_mark_from_mark_stack(); \ + if (GC_mark_state != MS_NONE) { \ + GC_set_mark_bit(real_ptr); \ + while (!GC_mark_some((ptr_t)0)); \ + } \ +} + +extern GC_bool GC_mark_stack_too_small; + /* We need a larger mark stack. May be */ + /* set by client supplied mark routines.*/ + +typedef int mark_state_t; /* Current state of marking, as follows:*/ + /* Used to remember where we are during */ + /* concurrent marking. */ + + /* We say something is dirty if it was */ + /* written since the last time we */ + /* retrieved dirty bits. We say it's */ + /* grungy if it was marked dirty in the */ + /* last set of bits we retrieved. */ + + /* Invariant I: all roots and marked */ + /* objects p are either dirty, or point */ + /* to objects q that are either marked */ + /* or a pointer to q appears in a range */ + /* on the mark stack. */ + +# define MS_NONE 0 /* No marking in progress. I holds. */ + /* Mark stack is empty. */ + +# define MS_PUSH_RESCUERS 1 /* Rescuing objects are currently */ + /* being pushed. I holds, except */ + /* that grungy roots may point to */ + /* unmarked objects, as may marked */ + /* grungy objects above scan_ptr. */ + +# define MS_PUSH_UNCOLLECTABLE 2 + /* I holds, except that marked */ + /* uncollectable objects above scan_ptr */ + /* may point to unmarked objects. */ + /* Roots may point to unmarked objects */ + +# define MS_ROOTS_PUSHED 3 /* I holds, mark stack may be nonempty */ + +# define MS_PARTIALLY_INVALID 4 /* I may not hold, e.g. because of M.S. */ + /* overflow. However marked heap */ + /* objects below scan_ptr point to */ + /* marked or stacked objects. */ + +# define MS_INVALID 5 /* I may not hold. */ + +extern mark_state_t GC_mark_state; + +#endif /* GC_MARK_H */ + |