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