390 lines
13 KiB
C
390 lines
13 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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* (Note that gc_priv.h should not be included before this, since this
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* includes dbg_mlc.h, which wants to include gc_priv.h AFTER defining
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* I_HIDE_POINTERS.)
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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(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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/* 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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extern mark_proc GC_mark_procs[MAX_MARK_PROCS];
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*/
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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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extern word 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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typedef struct GC_ms_entry {
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GC_word * mse_start; /* First word of object */
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GC_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_limit;
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#ifdef PARALLEL_MARK
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extern mse * VOLATILE GC_mark_stack_top;
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#else
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extern mse * GC_mark_stack_top;
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#endif
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extern mse * GC_mark_stack;
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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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void GC_do_parallel_mark();
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/* inititate parallel marking. */
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extern GC_bool GC_help_wanted; /* Protected by mark lock */
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extern unsigned GC_helper_count; /* Number of running helpers. */
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/* Protected by mark lock */
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extern unsigned GC_active_count; /* Number of active helpers. */
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/* Protected by mark lock */
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/* May increase and decrease */
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/* within each mark cycle. But */
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/* once it returns to 0, it */
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/* stays zero for the cycle. */
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/* GC_mark_stack_top is also protected by mark lock. */
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extern mse * VOLATILE GC_first_nonempty;
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/* Lowest entry on mark stack */
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/* that may be nonempty. */
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/* Updated only by initiating */
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/* thread. */
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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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/* Return a pointer to within 1st page of object. */
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/* Set *new_hdr_p to corr. hdr. */
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#ifdef __STDC__
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# ifdef PRINT_BLACK_LIST
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ptr_t GC_find_start(ptr_t current, hdr *hhdr, hdr **new_hdr_p,
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ptr_t source);
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# else
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ptr_t GC_find_start(ptr_t current, hdr *hhdr, hdr **new_hdr_p);
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# endif
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#else
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ptr_t GC_find_start();
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#endif
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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, new_hdr_p, source) \
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GC_find_start(current, hhdr, new_hdr_p, source)
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#else
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# define GC_FIND_START(current, hhdr, new_hdr_p, source) \
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GC_find_start(current, hhdr, new_hdr_p)
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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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hdr * my_hhdr; \
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ptr_t my_current = current; \
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\
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GET_HDR(my_current, my_hhdr); \
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if (IS_FORWARDING_ADDR_OR_NIL(my_hhdr)) { \
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hdr * new_hdr = GC_invalid_header; \
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my_current = GC_FIND_START(my_current, my_hhdr, \
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&new_hdr, (word)source); \
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my_hhdr = new_hdr; \
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} \
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PUSH_CONTENTS_HDR(my_current, mark_stack_top, mark_stack_limit, \
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source, exit_label, my_hhdr); \
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exit_label: ; \
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}
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/* As above, but use header cache for header lookup. */
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# define HC_PUSH_CONTENTS(current, mark_stack_top, mark_stack_limit, \
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source, exit_label) \
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{ \
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hdr * my_hhdr; \
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ptr_t my_current = current; \
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\
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HC_GET_HDR(my_current, my_hhdr, source); \
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PUSH_CONTENTS_HDR(my_current, mark_stack_top, mark_stack_limit, \
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source, exit_label, my_hhdr); \
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exit_label: ; \
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}
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/* Set mark bit, exit if it was already set. */
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# ifdef USE_MARK_BYTES
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/* Unlike the mark bit case, there is a race here, and we may set */
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/* the bit twice in the concurrent case. This can result in the */
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/* object being pushed twice. But that's only a performance issue. */
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# define SET_MARK_BIT_EXIT_IF_SET(hhdr,displ,exit_label) \
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{ \
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register VOLATILE char * mark_byte_addr = \
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hhdr -> hb_marks + ((displ) >> 1); \
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register char mark_byte = *mark_byte_addr; \
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\
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if (mark_byte) goto exit_label; \
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*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,displ,exit_label) \
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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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\
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OR_WORD_EXIT_IF_SET(mark_word_addr, (word)1 << modWORDSZ(displ), \
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exit_label); \
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}
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# endif /* USE_MARK_BYTES */
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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. For a small */
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/* object we assume that current is the (possibly interior) pointer */
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/* to the object. For large objects we assume that current points */
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/* to somewhere inside the first page of the object. If */
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/* GC_all_interior_pointers is set, it may have been previously */
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/* adjusted to make that true. */
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# define PUSH_CONTENTS_HDR(current, mark_stack_top, mark_stack_limit, \
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source, exit_label, hhdr) \
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{ \
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int displ; /* Displacement in block; first bytes, then words */ \
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int map_entry; \
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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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displ = BYTES_TO_WORDS(displ); \
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if (map_entry > CPP_MAX_OFFSET) { \
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if (map_entry == OFFSET_TOO_BIG) { \
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map_entry = displ % (hhdr -> hb_sz); \
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displ -= map_entry; \
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if (displ + (hhdr -> hb_sz) > BYTES_TO_WORDS(HBLKSIZE)) { \
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GC_ADD_TO_BLACK_LIST_NORMAL((word)current, source); \
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goto exit_label; \
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} \
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} else { \
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GC_ADD_TO_BLACK_LIST_NORMAL((word)current, source); goto exit_label; \
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} \
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} else { \
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displ -= map_entry; \
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} \
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GC_ASSERT(displ >= 0 && displ < MARK_BITS_PER_HBLK); \
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SET_MARK_BIT_EXIT_IF_SET(hhdr, displ, exit_label); \
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GC_STORE_BACK_PTR((ptr_t)source, (ptr_t)HBLKPTR(current) \
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+ WORDS_TO_BYTES(displ)); \
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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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}
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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(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(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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* 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, source) \
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if ((ptr_t)(p) >= (ptr_t)GC_least_plausible_heap_addr \
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&& (ptr_t)(p) < (ptr_t)GC_greatest_plausible_heap_addr) { \
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PUSH_ONE_CHECKED_STACK(p, source); \
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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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# define GC_PUSH_ONE_HEAP(p,source) \
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if ((ptr_t)(p) >= (ptr_t)GC_least_plausible_heap_addr \
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&& (ptr_t)(p) < (ptr_t)GC_greatest_plausible_heap_addr) { \
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GC_mark_stack_top = GC_mark_and_push( \
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(GC_PTR)(p), GC_mark_stack_top, \
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GC_mark_stack_limit, (GC_PTR *)(source)); \
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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 */
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/* top entry. */
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mse * GC_mark_from GC_PROTO((mse * top, mse * bottom, mse *limit));
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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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* 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()) 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((ptr_t)0)) {} \
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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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/* to objects q that are either marked */
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/* or 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_PMARK_H */
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