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