511 lines
21 KiB
C
511 lines
21 KiB
C
/*
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* Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
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* Copyright (c) 2001 by Hewlett-Packard Company. 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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/* Private declarations of GC marker data structures and macros */
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/*
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* Declarations of mark stack. Needed by marker and client supplied mark
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* routines. Transitively include gc_priv.h.
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*/
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#ifndef GC_PMARK_H
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#define GC_PMARK_H
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#if defined(HAVE_CONFIG_H) && !defined(GC_PRIVATE_H)
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# include "config.h"
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#endif
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#ifndef GC_BUILD
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# define GC_BUILD
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#endif
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#if (defined(__linux__) || defined(__GLIBC__) || defined(__GNU__)) \
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&& !defined(_GNU_SOURCE) && defined(GC_PTHREADS) \
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&& !defined(GC_NO_PTHREAD_SIGMASK)
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# define _GNU_SOURCE 1
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#endif
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#if defined(KEEP_BACK_PTRS) || defined(PRINT_BLACK_LIST)
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# include "dbg_mlc.h"
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#endif
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#ifndef GC_MARK_H
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# include "../gc_mark.h"
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#endif
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#ifndef GC_PRIVATE_H
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# include "gc_priv.h"
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#endif
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EXTERN_C_BEGIN
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/* The real declarations of the following is in gc_priv.h, so that */
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/* we can avoid scanning the following table. */
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/*
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mark_proc GC_mark_procs[MAX_MARK_PROCS];
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*/
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#ifndef MARK_DESCR_OFFSET
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# define MARK_DESCR_OFFSET sizeof(word)
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#endif
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/*
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* Mark descriptor stuff that should remain private for now, mostly
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* because it's hard to export WORDSZ without including gcconfig.h.
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*/
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#define BITMAP_BITS (WORDSZ - GC_DS_TAG_BITS)
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#define PROC(descr) \
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(GC_mark_procs[((descr) >> GC_DS_TAG_BITS) & (GC_MAX_MARK_PROCS-1)])
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#define ENV(descr) \
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((descr) >> (GC_DS_TAG_BITS + GC_LOG_MAX_MARK_PROCS))
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#define MAX_ENV \
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(((word)1 << (WORDSZ - GC_DS_TAG_BITS - GC_LOG_MAX_MARK_PROCS)) - 1)
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GC_EXTERN unsigned GC_n_mark_procs;
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/* Number of mark stack entries to discard on overflow. */
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#define GC_MARK_STACK_DISCARDS (INITIAL_MARK_STACK_SIZE/8)
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GC_EXTERN size_t GC_mark_stack_size;
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#ifdef PARALLEL_MARK
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/*
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* Allow multiple threads to participate in the marking process.
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* This works roughly as follows:
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* The main mark stack never shrinks, but it can grow.
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*
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* The initiating threads holds the GC lock, and sets GC_help_wanted.
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*
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* Other threads:
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* 1) update helper_count (while holding mark_lock.)
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* 2) allocate a local mark stack
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* repeatedly:
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* 3) Steal a global mark stack entry by atomically replacing
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* its descriptor with 0.
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* 4) Copy it to the local stack.
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* 5) Mark on the local stack until it is empty, or
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* it may be profitable to copy it back.
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* 6) If necessary, copy local stack to global one,
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* holding mark lock.
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* 7) Stop when the global mark stack is empty.
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* 8) decrement helper_count (holding mark_lock).
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*
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* This is an experiment to see if we can do something along the lines
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* of the University of Tokyo SGC in a less intrusive, though probably
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* also less performant, way.
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*/
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/* GC_mark_stack_top is protected by mark lock. */
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/*
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* GC_notify_all_marker() is used when GC_help_wanted is first set,
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* when the last helper becomes inactive,
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* when something is added to the global mark stack, and just after
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* GC_mark_no is incremented.
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* This could be split into multiple CVs (and probably should be to
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* scale to really large numbers of processors.)
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*/
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#endif /* PARALLEL_MARK */
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GC_INNER mse * GC_signal_mark_stack_overflow(mse *msp);
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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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do { \
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word _descr = (hhdr) -> hb_descr; \
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GC_ASSERT(!HBLK_IS_FREE(hhdr)); \
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if (_descr != 0) { \
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mark_stack_top++; \
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if ((word)mark_stack_top >= (word)(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.w = _descr; \
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} \
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} while (0)
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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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#define PUSH_CONTENTS(current, mark_stack_top, mark_stack_limit, source) \
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do { \
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hdr * my_hhdr; \
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HC_GET_HDR(current, my_hhdr, source); /* contains "break" */ \
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PUSH_CONTENTS_HDR(current, mark_stack_top, mark_stack_limit, \
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source, my_hhdr, TRUE); \
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} while (0)
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/* Set mark bit, exit (using "break" statement) if it is already set. */
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#ifdef USE_MARK_BYTES
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# if defined(PARALLEL_MARK) && defined(AO_HAVE_char_store) \
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&& !defined(AO_USE_PTHREAD_DEFS)
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/* There is a race here, and we may set the bit twice in the */
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/* concurrent case. This can result in the object being pushed */
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/* twice. But that is only a performance issue. */
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# define SET_MARK_BIT_EXIT_IF_SET(hhdr, bit_no) \
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{ /* cannot use do-while(0) here */ \
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volatile unsigned char * mark_byte_addr = \
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(unsigned char *)(hhdr)->hb_marks + (bit_no); \
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/* Unordered atomic load and store are sufficient here. */ \
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if (AO_char_load(mark_byte_addr) != 0) \
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break; /* go to the enclosing loop end */ \
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AO_char_store(mark_byte_addr, 1); \
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}
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# else
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# define SET_MARK_BIT_EXIT_IF_SET(hhdr, bit_no) \
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{ /* cannot use do-while(0) here */ \
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char * mark_byte_addr = (char *)(hhdr)->hb_marks + (bit_no); \
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if (*mark_byte_addr != 0) break; /* go to the enclosing loop end */ \
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*mark_byte_addr = 1; \
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}
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# endif /* !PARALLEL_MARK */
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#else
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# ifdef PARALLEL_MARK
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/* This is used only if we explicitly set USE_MARK_BITS. */
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/* The following may fail to exit even if the bit was already set. */
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/* For our uses, that's benign: */
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# ifdef THREAD_SANITIZER
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# define OR_WORD_EXIT_IF_SET(addr, bits) \
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{ /* cannot use do-while(0) here */ \
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if (!((word)AO_load((volatile AO_t *)(addr)) & (bits))) { \
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/* Atomic load is just to avoid TSan false positive. */ \
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AO_or((volatile AO_t *)(addr), (AO_t)(bits)); \
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} else { \
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break; /* go to the enclosing loop end */ \
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} \
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}
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# else
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# define OR_WORD_EXIT_IF_SET(addr, bits) \
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{ /* cannot use do-while(0) here */ \
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if (!(*(addr) & (bits))) { \
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AO_or((volatile AO_t *)(addr), (AO_t)(bits)); \
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} else { \
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break; /* go to the enclosing loop end */ \
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} \
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}
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# endif /* !THREAD_SANITIZER */
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# else
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# define OR_WORD_EXIT_IF_SET(addr, bits) \
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{ /* cannot use do-while(0) here */ \
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word old = *(addr); \
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word my_bits = (bits); \
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if ((old & my_bits) != 0) \
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break; /* go to the enclosing loop end */ \
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*(addr) = old | my_bits; \
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}
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# endif /* !PARALLEL_MARK */
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# define SET_MARK_BIT_EXIT_IF_SET(hhdr, bit_no) \
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{ /* cannot use do-while(0) here */ \
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word * mark_word_addr = (hhdr)->hb_marks + divWORDSZ(bit_no); \
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OR_WORD_EXIT_IF_SET(mark_word_addr, \
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(word)1 << modWORDSZ(bit_no)); /* contains "break" */ \
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}
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#endif /* !USE_MARK_BYTES */
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#ifdef PARALLEL_MARK
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# define INCR_MARKS(hhdr) \
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AO_store(&hhdr->hb_n_marks, AO_load(&hhdr->hb_n_marks) + 1)
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#else
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# define INCR_MARKS(hhdr) (void)(++hhdr->hb_n_marks)
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#endif
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#ifdef ENABLE_TRACE
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# define TRACE(source, cmd) \
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if (GC_trace_addr != 0 && (ptr_t)(source) == GC_trace_addr) cmd
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# define TRACE_TARGET(target, cmd) \
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if (GC_trace_addr != 0 && (target) == *(ptr_t *)GC_trace_addr) cmd
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#else
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# define TRACE(source, cmd)
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# define TRACE_TARGET(source, cmd)
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#endif
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#if defined(I386) && defined(__GNUC__) && !defined(NACL)
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# define LONG_MULT(hprod, lprod, x, y) \
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do { \
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__asm__ __volatile__("mull %2" : "=a"(lprod), "=d"(hprod) \
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: "g"(y), "0"(x)); \
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} while (0)
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#else
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# if defined(__int64) && !defined(__GNUC__) && !defined(CPPCHECK)
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# define ULONG_MULT_T unsigned __int64
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# else
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# define ULONG_MULT_T unsigned long long
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# endif
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# define LONG_MULT(hprod, lprod, x, y) \
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do { \
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ULONG_MULT_T prod = (ULONG_MULT_T)(x) * (ULONG_MULT_T)(y); \
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GC_STATIC_ASSERT(sizeof(x) + sizeof(y) <= sizeof(prod)); \
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hprod = prod >> 32; \
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lprod = (unsigned32)prod; \
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} while (0)
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#endif /* !I386 */
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/* If the mark bit corresponding to current is not set, set it, and */
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/* push the contents of the object on the mark stack. Current points */
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/* to the beginning of the object. We rely on the fact that the */
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/* preceding header calculation will succeed for a pointer past the */
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/* first page of an object, only if it is in fact a valid pointer */
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/* to the object. Thus we can omit the otherwise necessary tests */
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/* here. Note in particular that the "displ" value is the displacement */
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/* from the beginning of the heap block, which may itself be in the */
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/* interior of a large object. */
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#ifdef MARK_BIT_PER_GRANULE
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# define PUSH_CONTENTS_HDR(current, mark_stack_top, mark_stack_limit, \
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source, hhdr, do_offset_check) \
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do { \
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size_t displ = HBLKDISPL(current); /* Displacement in block; in bytes. */\
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/* displ is always within range. If current doesn't point to */ \
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/* first block, then we are in the all_interior_pointers case, and */ \
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/* it is safe to use any displacement value. */ \
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size_t gran_displ = BYTES_TO_GRANULES(displ); \
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size_t gran_offset = hhdr -> hb_map[gran_displ]; \
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size_t byte_offset = displ & (GRANULE_BYTES - 1); \
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ptr_t base = (ptr_t)(current); \
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/* The following always fails for large block references. */ \
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if (EXPECT((gran_offset | byte_offset) != 0, FALSE)) { \
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if ((hhdr -> hb_flags & LARGE_BLOCK) != 0) { \
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/* gran_offset is bogus. */ \
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size_t obj_displ; \
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base = (ptr_t)(hhdr -> hb_block); \
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obj_displ = (ptr_t)(current) - base; \
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if (obj_displ != displ) { \
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GC_ASSERT(obj_displ < hhdr -> hb_sz); \
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/* Must be in all_interior_pointer case, not first block */ \
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/* already did validity check on cache miss. */ \
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} else { \
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if (do_offset_check && !GC_valid_offsets[obj_displ]) { \
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GC_ADD_TO_BLACK_LIST_NORMAL(current, source); \
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break; /* go to the end of PUSH_CONTENTS_HDR */ \
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} \
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} \
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gran_displ = 0; \
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GC_ASSERT(hhdr -> hb_sz > HBLKSIZE || \
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hhdr -> hb_block == HBLKPTR(current)); \
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GC_ASSERT((word)hhdr->hb_block <= (word)(current)); \
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} else { \
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size_t obj_displ = GRANULES_TO_BYTES(gran_offset) \
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+ byte_offset; \
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if (do_offset_check && !GC_valid_offsets[obj_displ]) { \
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GC_ADD_TO_BLACK_LIST_NORMAL(current, source); \
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break; \
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} \
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gran_displ -= gran_offset; \
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base -= obj_displ; \
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} \
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} \
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GC_ASSERT(hhdr == GC_find_header(base)); \
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GC_ASSERT(gran_displ % BYTES_TO_GRANULES(hhdr -> hb_sz) == 0); \
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TRACE(source, GC_log_printf("GC #%u: passed validity tests\n", \
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(unsigned)GC_gc_no)); \
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SET_MARK_BIT_EXIT_IF_SET(hhdr, gran_displ); \
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TRACE(source, GC_log_printf("GC #%u: previously unmarked\n", \
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(unsigned)GC_gc_no)); \
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TRACE_TARGET(base, \
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GC_log_printf("GC #%u: marking %p from %p instead\n", \
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(unsigned)GC_gc_no, (void *)base, (void *)(source))); \
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INCR_MARKS(hhdr); \
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GC_STORE_BACK_PTR((ptr_t)(source), base); \
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PUSH_OBJ(base, hhdr, mark_stack_top, mark_stack_limit); \
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} while (0)
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#endif /* MARK_BIT_PER_GRANULE */
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#ifdef MARK_BIT_PER_OBJ
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# define PUSH_CONTENTS_HDR(current, mark_stack_top, mark_stack_limit, \
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source, hhdr, do_offset_check) \
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do { \
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size_t displ = HBLKDISPL(current); /* Displacement in block; in bytes. */\
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unsigned32 low_prod, high_prod; \
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unsigned32 inv_sz = hhdr -> hb_inv_sz; \
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ptr_t base = (ptr_t)(current); \
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LONG_MULT(high_prod, low_prod, (unsigned32)displ, inv_sz); \
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/* product is > and within sz_in_bytes of displ * sz_in_bytes * 2**32 */ \
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if (EXPECT(low_prod >> 16 != 0, FALSE)) { \
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/* FIXME: fails if offset is a multiple of HBLKSIZE which becomes 0 */ \
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if (inv_sz == LARGE_INV_SZ) { \
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size_t obj_displ; \
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base = (ptr_t)(hhdr -> hb_block); \
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obj_displ = (ptr_t)(current) - base; \
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if (obj_displ != displ) { \
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GC_ASSERT(obj_displ < hhdr -> hb_sz); \
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/* Must be in all_interior_pointer case, not first block */ \
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/* already did validity check on cache miss. */ \
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} else { \
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if (do_offset_check && !GC_valid_offsets[obj_displ]) { \
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GC_ADD_TO_BLACK_LIST_NORMAL(current, source); \
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break; /* go to the end of PUSH_CONTENTS_HDR */ \
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} \
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} \
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GC_ASSERT(hhdr -> hb_sz > HBLKSIZE || \
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hhdr -> hb_block == HBLKPTR(current)); \
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GC_ASSERT((word)hhdr->hb_block < (word)(current)); \
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} else { \
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size_t obj_displ; \
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/* Accurate enough if HBLKSIZE <= 2**15. */ \
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GC_STATIC_ASSERT(HBLKSIZE <= (1 << 15)); \
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obj_displ = (((low_prod >> 16) + 1) * (size_t)hhdr->hb_sz) >> 16; \
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if (do_offset_check && !GC_valid_offsets[obj_displ]) { \
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GC_ADD_TO_BLACK_LIST_NORMAL(current, source); \
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break; \
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} \
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base -= obj_displ; \
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} \
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} \
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/* May get here for pointer to start of block not at */ \
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/* beginning of object. If so, it's valid, and we're fine. */ \
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GC_ASSERT(high_prod <= HBLK_OBJS(hhdr -> hb_sz)); \
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TRACE(source, GC_log_printf("GC #%u: passed validity tests\n", \
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(unsigned)GC_gc_no)); \
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SET_MARK_BIT_EXIT_IF_SET(hhdr, high_prod); \
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TRACE(source, GC_log_printf("GC #%u: previously unmarked\n", \
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(unsigned)GC_gc_no)); \
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TRACE_TARGET(base, \
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GC_log_printf("GC #%u: marking %p from %p instead\n", \
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(unsigned)GC_gc_no, (void *)base, (void *)(source))); \
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INCR_MARKS(hhdr); \
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GC_STORE_BACK_PTR((ptr_t)(source), base); \
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PUSH_OBJ(base, hhdr, mark_stack_top, mark_stack_limit); \
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} while (0)
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#endif /* MARK_BIT_PER_OBJ */
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#if defined(PRINT_BLACK_LIST) || defined(KEEP_BACK_PTRS)
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# define PUSH_ONE_CHECKED_STACK(p, source) \
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GC_mark_and_push_stack((ptr_t)(p), (ptr_t)(source))
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#else
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# define PUSH_ONE_CHECKED_STACK(p, source) \
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GC_mark_and_push_stack((ptr_t)(p))
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#endif
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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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* Invoke FIXUP_POINTER(p) before any further processing.
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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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#ifdef NEED_FIXUP_POINTER
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/* Try both the raw version and the fixed up one. */
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# define GC_PUSH_ONE_STACK(p, source) \
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do { \
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if ((word)(p) >= (word)GC_least_plausible_heap_addr \
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&& (word)(p) < (word)GC_greatest_plausible_heap_addr) { \
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PUSH_ONE_CHECKED_STACK(p, source); \
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} \
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FIXUP_POINTER(p); \
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if ((word)(p) >= (word)GC_least_plausible_heap_addr \
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&& (word)(p) < (word)GC_greatest_plausible_heap_addr) { \
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PUSH_ONE_CHECKED_STACK(p, source); \
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} \
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} while (0)
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#else /* !NEED_FIXUP_POINTER */
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# define GC_PUSH_ONE_STACK(p, source) \
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do { \
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if ((word)(p) >= (word)GC_least_plausible_heap_addr \
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&& (word)(p) < (word)GC_greatest_plausible_heap_addr) { \
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PUSH_ONE_CHECKED_STACK(p, source); \
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} \
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} while (0)
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#endif
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/* As above, but interior pointer recognition as for normal heap pointers. */
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#define GC_PUSH_ONE_HEAP(p,source,mark_stack_top) \
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do { \
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FIXUP_POINTER(p); \
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if ((word)(p) >= (word)GC_least_plausible_heap_addr \
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&& (word)(p) < (word)GC_greatest_plausible_heap_addr) \
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mark_stack_top = GC_mark_and_push((void *)(p), mark_stack_top, \
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GC_mark_stack_limit, (void * *)(source)); \
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} while (0)
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|
|
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/* Mark starting at mark stack entry top (incl.) down to */
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/* mark stack entry bottom (incl.). Stop after performing */
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|
/* about one page worth of work. Return the new mark stack */
|
|
/* top entry. */
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GC_INNER mse * GC_mark_from(mse * top, mse * bottom, mse *limit);
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|
|
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#define MARK_FROM_MARK_STACK() \
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GC_mark_stack_top = GC_mark_from(GC_mark_stack_top, \
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GC_mark_stack, \
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|
GC_mark_stack + GC_mark_stack_size);
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|
|
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#define GC_mark_stack_empty() ((word)GC_mark_stack_top < (word)GC_mark_stack)
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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
|
|
* real_ptr. That is the job of the caller, if appropriate.
|
|
* Note that this is called with the mutator running, but
|
|
* with us holding the allocation lock. This is safe only if the
|
|
* mutator needs the allocation lock to reveal hidden pointers.
|
|
* FIXME: Why do we need the GC_mark_state test below?
|
|
*/
|
|
#define GC_MARK_FO(real_ptr, mark_proc) \
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|
do { \
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|
(*(mark_proc))(real_ptr); \
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|
while (!GC_mark_stack_empty()) MARK_FROM_MARK_STACK(); \
|
|
if (GC_mark_state != MS_NONE) { \
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|
GC_set_mark_bit(real_ptr); \
|
|
while (!GC_mark_some((ptr_t)0)) { /* empty */ } \
|
|
} \
|
|
} while (0)
|
|
|
|
GC_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 */
|
|
/* uncollectible 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 */
|
|
/* the mark stack overflow. However */
|
|
/* marked heap objects below scan_ptr */
|
|
/* point to marked or stacked objects. */
|
|
|
|
#define MS_INVALID 5 /* "I" may not hold. */
|
|
|
|
GC_EXTERN mark_state_t GC_mark_state;
|
|
|
|
EXTERN_C_END
|
|
|
|
#endif /* GC_PMARK_H */
|