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/*
* 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.
*/
#ifndef GC_PMARK_H
#define GC_PMARK_H
#if defined(HAVE_CONFIG_H) && !defined(GC_PRIVATE_H)
/* When gc_pmark.h is included from gc_priv.h, some of macros might */
/* be undefined in gcconfig.h, so skip config.h in this case. */
# include "config.h"
#endif
#ifndef GC_BUILD
# define GC_BUILD
#endif
#if (defined(__linux__) || defined(__GLIBC__) || defined(__GNU__)) \
&& !defined(_GNU_SOURCE) && defined(GC_PTHREADS) \
&& !defined(GC_NO_PTHREAD_SIGMASK)
# define _GNU_SOURCE 1
#endif
#if defined(KEEP_BACK_PTRS) || defined(PRINT_BLACK_LIST)
# include "dbg_mlc.h"
#endif
#include "../gc_mark.h"
#include "gc_priv.h"
EXTERN_C_BEGIN
/* The real declarations of the following is in gc_priv.h, so that */
/* we can avoid scanning the following table. */
/*
mark_proc GC_mark_procs[MAX_MARK_PROCS];
*/
#ifndef MARK_DESCR_OFFSET
# define MARK_DESCR_OFFSET sizeof(word)
#endif
/*
* 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)
GC_EXTERN unsigned GC_n_mark_procs;
/* Number of mark stack entries to discard on overflow. */
#define GC_MARK_STACK_DISCARDS (INITIAL_MARK_STACK_SIZE/8)
#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.
*/
/* GC_mark_stack_top is protected by mark lock. */
/*
* 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 */
GC_INNER mse * GC_signal_mark_stack_overflow(mse *msp);
/* Push the object obj with corresponding heap block header hhdr onto */
/* the mark stack. Returns the updated mark_stack_top value. */
GC_INLINE mse * GC_push_obj(ptr_t obj, hdr * hhdr, mse * mark_stack_top,
mse * mark_stack_limit)
{
word descr = hhdr -> hb_descr;
GC_ASSERT(!HBLK_IS_FREE(hhdr));
if (descr != 0) {
mark_stack_top++;
if ((word)mark_stack_top >= (word)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.w = descr;
}
return mark_stack_top;
}
/* Push the contents of current onto the mark stack if it is a valid */
/* ptr to a currently unmarked object. Mark it. */
#define PUSH_CONTENTS(current, mark_stack_top, mark_stack_limit, source) \
do { \
hdr * my_hhdr; \
HC_GET_HDR(current, my_hhdr, source); /* contains "break" */ \
mark_stack_top = GC_push_contents_hdr(current, mark_stack_top, \
mark_stack_limit, \
source, my_hhdr, TRUE); \
} while (0)
/* Set mark bit, exit (using "break" statement) if it is already set. */
#ifdef USE_MARK_BYTES
# if defined(PARALLEL_MARK) && defined(AO_HAVE_char_store) \
&& !defined(BASE_ATOMIC_OPS_EMULATED)
/* 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 is only a performance issue. */
# define SET_MARK_BIT_EXIT_IF_SET(hhdr, bit_no) \
{ /* cannot use do-while(0) here */ \
volatile unsigned char * mark_byte_addr = \
(unsigned char *)(hhdr)->hb_marks + (bit_no); \
/* Unordered atomic load and store are sufficient here. */ \
if (AO_char_load(mark_byte_addr) != 0) \
break; /* go to the enclosing loop end */ \
AO_char_store(mark_byte_addr, 1); \
}
# else
# define SET_MARK_BIT_EXIT_IF_SET(hhdr, bit_no) \
{ /* cannot use do-while(0) here */ \
char * mark_byte_addr = (char *)(hhdr)->hb_marks + (bit_no); \
if (*mark_byte_addr != 0) break; /* go to the enclosing loop end */ \
*mark_byte_addr = 1; \
}
# endif /* !PARALLEL_MARK */
#else
# ifdef PARALLEL_MARK
/* This is used only if we explicitly set USE_MARK_BITS. */
/* The following may fail to exit even if the bit was already set. */
/* For our uses, that's benign: */
# ifdef THREAD_SANITIZER
# define OR_WORD_EXIT_IF_SET(addr, bits) \
{ /* cannot use do-while(0) here */ \
if (!((word)AO_load((volatile AO_t *)(addr)) & (bits))) { \
/* Atomic load is just to avoid TSan false positive. */ \
AO_or((volatile AO_t *)(addr), (AO_t)(bits)); \
} else { \
break; /* go to the enclosing loop end */ \
} \
}
# else
# define OR_WORD_EXIT_IF_SET(addr, bits) \
{ /* cannot use do-while(0) here */ \
if (!(*(addr) & (bits))) { \
AO_or((volatile AO_t *)(addr), (AO_t)(bits)); \
} else { \
break; /* go to the enclosing loop end */ \
} \
}
# endif /* !THREAD_SANITIZER */
# else
# define OR_WORD_EXIT_IF_SET(addr, bits) \
{ /* cannot use do-while(0) here */ \
word old = *(addr); \
word my_bits = (bits); \
if ((old & my_bits) != 0) \
break; /* go to the enclosing loop end */ \
*(addr) = old | my_bits; \
}
# endif /* !PARALLEL_MARK */
# define SET_MARK_BIT_EXIT_IF_SET(hhdr, bit_no) \
{ /* cannot use do-while(0) here */ \
word * mark_word_addr = (hhdr)->hb_marks + divWORDSZ(bit_no); \
OR_WORD_EXIT_IF_SET(mark_word_addr, \
(word)1 << modWORDSZ(bit_no)); /* contains "break" */ \
}
#endif /* !USE_MARK_BYTES */
#ifdef PARALLEL_MARK
# define INCR_MARKS(hhdr) \
AO_store(&hhdr->hb_n_marks, AO_load(&hhdr->hb_n_marks) + 1)
#else
# define INCR_MARKS(hhdr) (void)(++hhdr->hb_n_marks)
#endif
#ifdef ENABLE_TRACE
# define TRACE(source, cmd) \
if (GC_trace_addr != 0 && (ptr_t)(source) == GC_trace_addr) cmd
# define TRACE_TARGET(target, cmd) \
if (GC_trace_addr != 0 && (target) == *(ptr_t *)GC_trace_addr) cmd
#else
# define TRACE(source, cmd)
# define TRACE_TARGET(source, cmd)
#endif
#if defined(I386) && defined(__GNUC__) && !defined(NACL)
# define LONG_MULT(hprod, lprod, x, y) \
do { \
__asm__ __volatile__("mull %2" : "=a"(lprod), "=d"(hprod) \
: "g"(y), "0"(x)); \
} while (0)
#else
# if defined(__int64) && !defined(__GNUC__) && !defined(CPPCHECK)
# define ULONG_MULT_T unsigned __int64
# else
# define ULONG_MULT_T unsigned long long
# endif
# define LONG_MULT(hprod, lprod, x, y) \
do { \
ULONG_MULT_T prod = (ULONG_MULT_T)(x) * (ULONG_MULT_T)(y); \
GC_STATIC_ASSERT(sizeof(x) + sizeof(y) <= sizeof(prod)); \
hprod = prod >> 32; \
lprod = (unsigned32)prod; \
} while (0)
#endif /* !I386 */
/* If the mark bit corresponding to current is not set, set it, and */
/* push the contents of the object on the mark stack. Current points */
/* to the beginning of the object. We rely on the fact that the */
/* preceding header calculation will succeed for a pointer past the */
/* first page of an object, only if it is in fact a valid pointer */
/* to the object. Thus we can omit the otherwise necessary tests */
/* here. Note in particular that the "displ" value is the displacement */
/* from the beginning of the heap block, which may itself be in the */
/* interior of a large object. */
GC_INLINE mse * GC_push_contents_hdr(ptr_t current, mse * mark_stack_top,
mse * mark_stack_limit, ptr_t source,
hdr * hhdr, GC_bool do_offset_check)
{
do {
size_t displ = HBLKDISPL(current); /* Displacement in block; in bytes. */
/* displ is always within range. If current doesn't point to the */
/* first block, then we are in the all_interior_pointers case, and */
/* it is safe to use any displacement value. */
ptr_t base = current;
# ifdef MARK_BIT_PER_GRANULE
size_t gran_displ = BYTES_TO_GRANULES(displ);
size_t gran_offset = hhdr -> hb_map[gran_displ];
size_t byte_offset = displ & (GRANULE_BYTES - 1);
/* The following always fails for large block references. */
if (EXPECT((gran_offset | byte_offset) != 0, FALSE))
# else
unsigned32 gran_displ; /* high_prod */
unsigned32 inv_sz = hhdr -> hb_inv_sz;
# endif /* MARK_BIT_PER_OBJ */
{
# ifdef MARK_BIT_PER_GRANULE
if ((hhdr -> hb_flags & LARGE_BLOCK) != 0)
# else
if (EXPECT(inv_sz == LARGE_INV_SZ, FALSE))
# endif /* MARK_BIT_PER_OBJ */
{
/* gran_offset is bogus. */
size_t obj_displ;
base = (ptr_t)hhdr->hb_block;
obj_displ = current - base;
if (obj_displ != displ) {
GC_ASSERT(obj_displ < hhdr -> hb_sz);
/* Must be in all_interior_pointer case, not first block */
/* already did validity check on cache miss. */
} else if (do_offset_check && !GC_valid_offsets[obj_displ]) {
GC_ADD_TO_BLACK_LIST_NORMAL(current, source);
break;
}
GC_ASSERT(hhdr -> hb_sz > HBLKSIZE
|| hhdr -> hb_block == HBLKPTR(current));
GC_ASSERT((word)hhdr->hb_block <= (word)current);
gran_displ = 0;
} else {
# ifdef MARK_BIT_PER_GRANULE
size_t obj_displ = GRANULES_TO_BYTES(gran_offset) + byte_offset;
# else
unsigned32 low_prod;
LONG_MULT(gran_displ, low_prod, (unsigned32)displ, inv_sz);
if ((low_prod >> 16) != 0)
# endif /* MARK_BIT_PER_OBJ */
{
# if defined(MARK_BIT_PER_OBJ) \
&& !defined(MARK_BIT_PER_GRANULE) /* for cppcheck */
size_t obj_displ;
/* Accurate enough if HBLKSIZE <= 2**15. */
GC_STATIC_ASSERT(HBLKSIZE <= (1 << 15));
obj_displ = (((low_prod >> 16) + 1) * (size_t)hhdr->hb_sz) >> 16;
# endif
if (do_offset_check && !GC_valid_offsets[obj_displ]) {
GC_ADD_TO_BLACK_LIST_NORMAL(current, source);
break;
}
# ifdef MARK_BIT_PER_GRANULE
gran_displ -= gran_offset;
# endif
base -= obj_displ;
}
}
}
# ifdef MARK_BIT_PER_GRANULE
GC_ASSERT(hhdr == GC_find_header(base));
GC_ASSERT(gran_displ % BYTES_TO_GRANULES(hhdr -> hb_sz) == 0);
# else
/* May get here for pointer to start of block not at the */
/* beginning of object. If so, it is valid, and we are fine. */
GC_ASSERT(gran_displ <= HBLK_OBJS(hhdr -> hb_sz));
# endif /* MARK_BIT_PER_OBJ */
TRACE(source, GC_log_printf("GC #%lu: passed validity tests\n",
(unsigned long)GC_gc_no));
SET_MARK_BIT_EXIT_IF_SET(hhdr, gran_displ); /* contains "break" */
TRACE(source, GC_log_printf("GC #%lu: previously unmarked\n",
(unsigned long)GC_gc_no));
TRACE_TARGET(base, GC_log_printf("GC #%lu: marking %p from %p instead\n",
(unsigned long)GC_gc_no, (void *)base,
(void *)source));
INCR_MARKS(hhdr);
GC_STORE_BACK_PTR(source, base);
mark_stack_top = GC_push_obj(base, hhdr, mark_stack_top,
mark_stack_limit);
} while (0);
return mark_stack_top;
}
#if defined(PRINT_BLACK_LIST) || defined(KEEP_BACK_PTRS)
# define PUSH_ONE_CHECKED_STACK(p, source) \
GC_mark_and_push_stack((ptr_t)(p), (ptr_t)(source))
#else
# define PUSH_ONE_CHECKED_STACK(p, source) \
GC_mark_and_push_stack((ptr_t)(p))
#endif
/*
* Push a single value onto mark stack. Mark from the object pointed to by p.
* Invoke FIXUP_POINTER(p) before any further processing.
* 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.
*/
#ifdef NEED_FIXUP_POINTER
/* Try both the raw version and the fixed up one. */
# define GC_PUSH_ONE_STACK(p, source) \
do { \
if ((word)(p) >= (word)GC_least_plausible_heap_addr \
&& (word)(p) < (word)GC_greatest_plausible_heap_addr) { \
PUSH_ONE_CHECKED_STACK(p, source); \
} \
FIXUP_POINTER(p); \
if ((word)(p) >= (word)GC_least_plausible_heap_addr \
&& (word)(p) < (word)GC_greatest_plausible_heap_addr) { \
PUSH_ONE_CHECKED_STACK(p, source); \
} \
} while (0)
#else /* !NEED_FIXUP_POINTER */
# define GC_PUSH_ONE_STACK(p, source) \
do { \
if ((word)(p) >= (word)GC_least_plausible_heap_addr \
&& (word)(p) < (word)GC_greatest_plausible_heap_addr) { \
PUSH_ONE_CHECKED_STACK(p, source); \
} \
} while (0)
#endif
/* As above, but interior pointer recognition as for normal heap pointers. */
#define GC_PUSH_ONE_HEAP(p,source,mark_stack_top) \
do { \
FIXUP_POINTER(p); \
if ((word)(p) >= (word)GC_least_plausible_heap_addr \
&& (word)(p) < (word)GC_greatest_plausible_heap_addr) \
mark_stack_top = GC_mark_and_push((void *)(p), mark_stack_top, \
GC_mark_stack_limit, (void * *)(source)); \
} while (0)
/* 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. */
GC_INNER mse * GC_mark_from(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);
#define GC_mark_stack_empty() ((word)GC_mark_stack_top < (word)GC_mark_stack)
/*
* 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.
* 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) \
do { \
(*(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)) { /* empty */ } \
} \
} while (0)
/* Current state of marking, as follows.*/
/* 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 GC_scan_ptr. */
#define MS_PUSH_UNCOLLECTABLE 2 /* "I" holds, except that marked */
/* uncollectible objects above */
/* GC_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 */
/* GC_scan_ptr point to marked or */
/* stacked objects. */
#define MS_INVALID 5 /* "I" may not hold. */
EXTERN_C_END
#endif /* GC_PMARK_H */
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