/*
* Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
* Copyright (c) 2001 by Hewlett-Packard Company. 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.
*
*/
/* Private declarations of GC marker data structures and macros */
/*
* Declarations of mark stack. Needed by marker and client supplied mark
* routines. Transitively include gc_priv.h.
* (Note that gc_priv.h should not be included before this, since this
* includes dbg_mlc.h, which wants to include gc_priv.h AFTER defining
* I_HIDE_POINTERS.)
*/
#ifndef GC_PMARK_H
# define GC_PMARK_H
# if defined(KEEP_BACK_PTRS) || defined(PRINT_BLACK_LIST)
# include "dbg_mlc.h"
# endif
# ifndef GC_MARK_H
# include "../gc_mark.h"
# endif
# ifndef GC_PRIVATE_H
# include "gc_priv.h"
# endif
/* The real declarations of the following is in gc_priv.h, so that */
/* we can avoid scanning the following table. */
/*
extern mark_proc GC_mark_procs[MAX_MARK_PROCS];
*/
/*
* Mark descriptor stuff that should remain private for now, mostly
* because it's hard to export WORDSZ without including gcconfig.h.
*/
# define BITMAP_BITS (WORDSZ - GC_DS_TAG_BITS)
# define PROC(descr) \
(GC_mark_procs[((descr) >> GC_DS_TAG_BITS) & (GC_MAX_MARK_PROCS-1)])
# define ENV(descr) \
((descr) >> (GC_DS_TAG_BITS + GC_LOG_MAX_MARK_PROCS))
# define MAX_ENV \
(((word)1 << (WORDSZ - GC_DS_TAG_BITS - GC_LOG_MAX_MARK_PROCS)) - 1)
extern word GC_n_mark_procs;
/* Number of mark stack entries to discard on overflow. */
#define GC_MARK_STACK_DISCARDS (INITIAL_MARK_STACK_SIZE/8)
typedef struct GC_ms_entry {
GC_word * mse_start; /* First word of object */
GC_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_limit;
#ifdef PARALLEL_MARK
extern mse * VOLATILE GC_mark_stack_top;
#else
extern mse * GC_mark_stack_top;
#endif
extern mse * GC_mark_stack;
#ifdef PARALLEL_MARK
/*
* Allow multiple threads to participate in the marking process.
* This works roughly as follows:
* The main mark stack never shrinks, but it can grow.
*
* The initiating threads holds the GC lock, and sets GC_help_wanted.
*
* Other threads:
* 1) update helper_count (while holding mark_lock.)
* 2) allocate a local mark stack
* repeatedly:
* 3) Steal a global mark stack entry by atomically replacing
* its descriptor with 0.
* 4) Copy it to the local stack.
* 5) Mark on the local stack until it is empty, or
* it may be profitable to copy it back.
* 6) If necessary, copy local stack to global one,
* holding mark lock.
* 7) Stop when the global mark stack is empty.
* 8) decrement helper_count (holding mark_lock).
*
* This is an experiment to see if we can do something along the lines
* of the University of Tokyo SGC in a less intrusive, though probably
* also less performant, way.
*/
void GC_do_parallel_mark();
/* inititate parallel marking. */
extern GC_bool GC_help_wanted; /* Protected by mark lock */
extern unsigned GC_helper_count; /* Number of running helpers. */
/* Protected by mark lock */
extern unsigned GC_active_count; /* Number of active helpers. */
/* Protected by mark lock */
/* May increase and decrease */
/* within each mark cycle. But */
/* once it returns to 0, it */
/* stays zero for the cycle. */
/* GC_mark_stack_top is also protected by mark lock. */
extern mse * VOLATILE GC_first_nonempty;
/* Lowest entry on mark stack */
/* that may be nonempty. */
/* Updated only by initiating */
/* thread. */
/*
* GC_notify_all_marker() is used when GC_help_wanted is first set,
* when the last helper becomes inactive,
* when something is added to the global mark stack, and just after
* GC_mark_no is incremented.
* This could be split into multiple CVs (and probably should be to
* scale to really large numbers of processors.)
*/
#endif /* PARALLEL_MARK */
/* Return a pointer to within 1st page of object. */
/* Set *new_hdr_p to corr. hdr. */
#ifdef __STDC__
# ifdef PRINT_BLACK_LIST
ptr_t GC_find_start(ptr_t current, hdr *hhdr, hdr **new_hdr_p,
word source);
# else
ptr_t GC_find_start(ptr_t current, hdr *hhdr, hdr **new_hdr_p);
# endif
#else
ptr_t GC_find_start();
#endif
mse * GC_signal_mark_stack_overflow GC_PROTO((mse *msp));
# 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; \
} \
}
/* 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) \
{ \
hdr * my_hhdr; \
ptr_t my_current = current; \
\
GET_HDR(my_current, my_hhdr); \
if (IS_FORWARDING_ADDR_OR_NIL(my_hhdr)) { \
hdr * new_hdr = GC_invalid_header; \
my_current = GC_find_start(my_current, my_hhdr, &new_hdr); \
my_hhdr = new_hdr; \
} \
PUSH_CONTENTS_HDR(my_current, mark_stack_top, mark_stack_limit, \
source, exit_label, my_hhdr); \
exit_label: ; \
}
/* As above, but use header cache for header lookup. */
# define HC_PUSH_CONTENTS(current, mark_stack_top, mark_stack_limit, \
source, exit_label) \
{ \
hdr * my_hhdr; \
ptr_t my_current = current; \
\
HC_GET_HDR(my_current, my_hhdr, source); \
PUSH_CONTENTS_HDR(my_current, mark_stack_top, mark_stack_limit, \
source, exit_label, my_hhdr); \
exit_label: ; \
}
/* Set mark bit, exit if it was already set. */
# ifdef USE_MARK_BYTES
/* Unlike the mark bit case, there is a race here, and we may set */
/* the bit twice in the concurrent case. This can result in the */
/* object being pushed twice. But that's only a performance issue. */
# define SET_MARK_BIT_EXIT_IF_SET(hhdr,displ,exit_label) \
{ \
register VOLATILE char * mark_byte_addr = \
hhdr -> hb_marks + ((displ) >> 1); \
register char mark_byte = *mark_byte_addr; \
\
if (mark_byte) goto exit_label; \
*mark_byte_addr = 1; \
}
# else
# define SET_MARK_BIT_EXIT_IF_SET(hhdr,displ,exit_label) \
{ \
register word * mark_word_addr = hhdr -> hb_marks + divWORDSZ(displ); \
\
OR_WORD_EXIT_IF_SET(mark_word_addr, (word)1 << modWORDSZ(displ), \
exit_label); \
}
# endif /* USE_MARK_BYTES */
/* If the mark bit corresponding to current is not set, set it, and */
/* push the contents of the object on the mark stack. For a small */
/* object we assume that current is the (possibly interior) pointer */
/* to the object. For large objects we assume that current points */
/* to somewhere inside the first page of the object. If */
/* GC_all_interior_pointers is set, it may have been previously */
/* adjusted to make that true. */
# define PUSH_CONTENTS_HDR(current, mark_stack_top, mark_stack_limit, \
source, exit_label, hhdr) \
{ \
int displ; /* Displacement in block; first bytes, then words */ \
int map_entry; \
\
displ = HBLKDISPL(current); \
map_entry = MAP_ENTRY((hhdr -> hb_map), displ); \
displ = BYTES_TO_WORDS(displ); \
if (map_entry > CPP_MAX_OFFSET) { \
if (map_entry == OFFSET_TOO_BIG) { \
map_entry = displ % (hhdr -> hb_sz); \
displ -= map_entry; \
if (displ + (hhdr -> hb_sz) > BYTES_TO_WORDS(HBLKSIZE)) { \
GC_ADD_TO_BLACK_LIST_NORMAL((word)current, source); \
goto exit_label; \
} \
} else { \
GC_ADD_TO_BLACK_LIST_NORMAL((word)current, source); goto exit_label; \
} \
} else { \
displ -= map_entry; \
} \
GC_ASSERT(displ >= 0 && displ < MARK_BITS_PER_HBLK); \
SET_MARK_BIT_EXIT_IF_SET(hhdr, displ, exit_label); \
GC_STORE_BACK_PTR((ptr_t)source, (ptr_t)HBLKPTR(current) \
+ WORDS_TO_BYTES(displ)); \
PUSH_OBJ(((word *)(HBLKPTR(current)) + displ), hhdr, \
mark_stack_top, mark_stack_limit) \
}
#if defined(PRINT_BLACK_LIST) || defined(KEEP_BACK_PTRS)
# define PUSH_ONE_CHECKED_STACK(p, source) \
GC_mark_and_push_stack(p, (ptr_t)(source))
#else
# define PUSH_ONE_CHECKED_STACK(p, source) \
GC_mark_and_push_stack(p)
#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) >= (ptr_t)GC_least_plausible_heap_addr \
&& (ptr_t)(p) < (ptr_t)GC_greatest_plausible_heap_addr) { \
PUSH_ONE_CHECKED_STACK(p, source); \
}
/*
* As above, but interior pointer recognition as for
* normal for heap pointers.
*/
# define GC_PUSH_ONE_HEAP(p,source) \
if ((ptr_t)(p) >= (ptr_t)GC_least_plausible_heap_addr \
&& (ptr_t)(p) < (ptr_t)GC_greatest_plausible_heap_addr) { \
GC_mark_stack_top = GC_mark_and_push( \
(GC_PTR)(p), GC_mark_stack_top, \
GC_mark_stack_limit, (GC_PTR *)(source)); \
}
/* Mark starting at mark stack entry top (incl.) down to */
/* mark stack entry bottom (incl.). Stop after performing */
/* about one page worth of work. Return the new mark stack */
/* top entry. */
mse * GC_mark_from GC_PROTO((mse * top, mse * bottom, mse *limit));
#define MARK_FROM_MARK_STACK() \
GC_mark_stack_top = GC_mark_from(GC_mark_stack_top, \
GC_mark_stack, \
GC_mark_stack + GC_mark_stack_size);
/*
* 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()) 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_PMARK_H */
