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gnu / gcc / 14bc1c0e15633ea781d76d0ae4274b2e27d51db5 / . / boehm-gc / mark.c
blob: 36c0b69317e055ce1fa976a7531d2c18802e0d7d [file] [log] [blame]
/*
* Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
* Copyright (c) 1991-1995 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.
*
*/
# include <stdio.h>
# include "gc_priv.h"
# include "gc_mark.h"
/* We put this here to minimize the risk of inlining. */
/*VARARGS*/
#ifdef __WATCOMC__
void GC_noop(void *p, ...) {}
#else
void GC_noop() {}
#endif
/* Single argument version, robust against whole program analysis. */
void GC_noop1(x)
word x;
{
static VOLATILE word sink;
sink = x;
}
/* mark_proc GC_mark_procs[MAX_MARK_PROCS] = {0} -- declared in gc_priv.h */
word GC_n_mark_procs = GC_RESERVED_MARK_PROCS;
/* Initialize GC_obj_kinds properly and standard free lists properly. */
/* This must be done statically since they may be accessed before */
/* GC_init is called. */
/* It's done here, since we need to deal with mark descriptors. */
struct obj_kind GC_obj_kinds[MAXOBJKINDS] = {
/* PTRFREE */ { &GC_aobjfreelist[0], 0 /* filled in dynamically */,
0 | DS_LENGTH, FALSE, FALSE },
/* NORMAL */ { &GC_objfreelist[0], 0,
# if defined(ADD_BYTE_AT_END) && ALIGNMENT > DS_TAGS
(word)(-ALIGNMENT) | DS_LENGTH,
# else
0 | DS_LENGTH,
# endif
TRUE /* add length to descr */, TRUE },
/* UNCOLLECTABLE */
{ &GC_uobjfreelist[0], 0,
0 | DS_LENGTH, TRUE /* add length to descr */, TRUE },
# ifdef ATOMIC_UNCOLLECTABLE
/* AUNCOLLECTABLE */
{ &GC_auobjfreelist[0], 0,
0 | DS_LENGTH, FALSE /* add length to descr */, FALSE },
# endif
# ifdef STUBBORN_ALLOC
/*STUBBORN*/ { &GC_sobjfreelist[0], 0,
0 | DS_LENGTH, TRUE /* add length to descr */, TRUE },
# endif
};
# ifdef ATOMIC_UNCOLLECTABLE
# ifdef STUBBORN_ALLOC
int GC_n_kinds = 5;
# else
int GC_n_kinds = 4;
# endif
# else
# ifdef STUBBORN_ALLOC
int GC_n_kinds = 4;
# else
int GC_n_kinds = 3;
# endif
# endif
# ifndef INITIAL_MARK_STACK_SIZE
# define INITIAL_MARK_STACK_SIZE (1*HBLKSIZE)
/* INITIAL_MARK_STACK_SIZE * sizeof(mse) should be a */
/* multiple of HBLKSIZE. */
/* The incremental collector actually likes a larger */
/* size, since it want to push all marked dirty objs */
/* before marking anything new. Currently we let it */
/* grow dynamically. */
# endif
/*
* Limits of stack for GC_mark routine.
* All ranges between GC_mark_stack(incl.) and GC_mark_stack_top(incl.) still
* need to be marked from.
*/
word GC_n_rescuing_pages; /* Number of dirty pages we marked from */
/* excludes ptrfree pages, etc. */
mse * GC_mark_stack;
word GC_mark_stack_size = 0;
mse * GC_mark_stack_top;
static struct hblk * scan_ptr;
mark_state_t GC_mark_state = MS_NONE;
GC_bool GC_mark_stack_too_small = FALSE;
GC_bool GC_objects_are_marked = FALSE; /* Are there collectable marked */
/* objects in the heap? */
/* Is a collection in progress? Note that this can return true in the */
/* nonincremental case, if a collection has been abandoned and the */
/* mark state is now MS_INVALID. */
GC_bool GC_collection_in_progress()
{
return(GC_mark_state != MS_NONE);
}
/* clear all mark bits in the header */
void GC_clear_hdr_marks(hhdr)
register hdr * hhdr;
{
BZERO(hhdr -> hb_marks, MARK_BITS_SZ*sizeof(word));
}
/* Set all mark bits in the header. Used for uncollectable blocks. */
void GC_set_hdr_marks(hhdr)
register hdr * hhdr;
{
register int i;
for (i = 0; i < MARK_BITS_SZ; ++i) {
hhdr -> hb_marks[i] = ONES;
}
}
/*
* Clear all mark bits associated with block h.
*/
/*ARGSUSED*/
static void clear_marks_for_block(h, dummy)
struct hblk *h;
word dummy;
{
register hdr * hhdr = HDR(h);
if (IS_UNCOLLECTABLE(hhdr -> hb_obj_kind)) return;
/* Mark bit for these is cleared only once the object is */
/* explicitly deallocated. This either frees the block, or */
/* the bit is cleared once the object is on the free list. */
GC_clear_hdr_marks(hhdr);
}
/* Slow but general routines for setting/clearing/asking about mark bits */
void GC_set_mark_bit(p)
ptr_t p;
{
register struct hblk *h = HBLKPTR(p);
register hdr * hhdr = HDR(h);
register int word_no = (word *)p - (word *)h;
set_mark_bit_from_hdr(hhdr, word_no);
}
void GC_clear_mark_bit(p)
ptr_t p;
{
register struct hblk *h = HBLKPTR(p);
register hdr * hhdr = HDR(h);
register int word_no = (word *)p - (word *)h;
clear_mark_bit_from_hdr(hhdr, word_no);
}
GC_bool GC_is_marked(p)
ptr_t p;
{
register struct hblk *h = HBLKPTR(p);
register hdr * hhdr = HDR(h);
register int word_no = (word *)p - (word *)h;
return(mark_bit_from_hdr(hhdr, word_no));
}
/*
* Clear mark bits in all allocated heap blocks. This invalidates
* the marker invariant, and sets GC_mark_state to reflect this.
* (This implicitly starts marking to reestablish the invariant.)
*/
void GC_clear_marks()
{
GC_apply_to_all_blocks(clear_marks_for_block, (word)0);
GC_objects_are_marked = FALSE;
GC_mark_state = MS_INVALID;
scan_ptr = 0;
# ifdef GATHERSTATS
/* Counters reflect currently marked objects: reset here */
GC_composite_in_use = 0;
GC_atomic_in_use = 0;
# endif
}
/* Initiate a garbage collection. Initiates a full collection if the */
/* mark state is invalid. */
/*ARGSUSED*/
void GC_initiate_gc()
{
if (GC_dirty_maintained) GC_read_dirty();
# ifdef STUBBORN_ALLOC
GC_read_changed();
# endif
# ifdef CHECKSUMS
{
extern void GC_check_dirty();
if (GC_dirty_maintained) GC_check_dirty();
}
# endif
# ifdef GATHERSTATS
GC_n_rescuing_pages = 0;
# endif
if (GC_mark_state == MS_NONE) {
GC_mark_state = MS_PUSH_RESCUERS;
} else if (GC_mark_state != MS_INVALID) {
ABORT("unexpected state");
} /* else this is really a full collection, and mark */
/* bits are invalid. */
scan_ptr = 0;
}
static void alloc_mark_stack();
/* Perform a small amount of marking. */
/* We try to touch roughly a page of memory. */
/* Return TRUE if we just finished a mark phase. */
/* Cold_gc_frame is an address inside a GC frame that */
/* remains valid until all marking is complete. */
/* A zero value indicates that it's OK to miss some */
/* register values. */
GC_bool GC_mark_some(cold_gc_frame)
ptr_t cold_gc_frame;
{
#ifdef MSWIN32
/* Windows 98 appears to asynchronously create and remove writable */
/* memory mappings, for reasons we haven't yet understood. Since */
/* we look for writable regions to determine the root set, we may */
/* try to mark from an address range that disappeared since we */
/* started the collection. Thus we have to recover from faults here. */
/* This code does not appear to be necessary for Windows 95/NT/2000. */
/* Note that this code should never generate an incremental GC write */
/* fault. */
__try {
#endif
switch(GC_mark_state) {
case MS_NONE:
return(FALSE);
case MS_PUSH_RESCUERS:
if (GC_mark_stack_top
>= GC_mark_stack + GC_mark_stack_size
- INITIAL_MARK_STACK_SIZE/2) {
/* Go ahead and mark, even though that might cause us to */
/* see more marked dirty objects later on. Avoid this */
/* in the future. */
GC_mark_stack_too_small = TRUE;
GC_mark_from_mark_stack();
return(FALSE);
} else {
scan_ptr = GC_push_next_marked_dirty(scan_ptr);
if (scan_ptr == 0) {
# ifdef PRINTSTATS
GC_printf1("Marked from %lu dirty pages\n",
(unsigned long)GC_n_rescuing_pages);
# endif
GC_push_roots(FALSE, cold_gc_frame);
GC_objects_are_marked = TRUE;
if (GC_mark_state != MS_INVALID) {
GC_mark_state = MS_ROOTS_PUSHED;
}
}
}
return(FALSE);
case MS_PUSH_UNCOLLECTABLE:
if (GC_mark_stack_top
>= GC_mark_stack + INITIAL_MARK_STACK_SIZE/4) {
GC_mark_from_mark_stack();
return(FALSE);
} else {
scan_ptr = GC_push_next_marked_uncollectable(scan_ptr);
if (scan_ptr == 0) {
GC_push_roots(TRUE, cold_gc_frame);
GC_objects_are_marked = TRUE;
if (GC_mark_state != MS_INVALID) {
GC_mark_state = MS_ROOTS_PUSHED;
}
}
}
return(FALSE);
case MS_ROOTS_PUSHED:
if (GC_mark_stack_top >= GC_mark_stack) {
GC_mark_from_mark_stack();
return(FALSE);
} else {
GC_mark_state = MS_NONE;
if (GC_mark_stack_too_small) {
alloc_mark_stack(2*GC_mark_stack_size);
}
return(TRUE);
}
case MS_INVALID:
case MS_PARTIALLY_INVALID:
if (!GC_objects_are_marked) {
GC_mark_state = MS_PUSH_UNCOLLECTABLE;
return(FALSE);
}
if (GC_mark_stack_top >= GC_mark_stack) {
GC_mark_from_mark_stack();
return(FALSE);
}
if (scan_ptr == 0 && GC_mark_state == MS_INVALID) {
/* About to start a heap scan for marked objects. */
/* Mark stack is empty. OK to reallocate. */
if (GC_mark_stack_too_small) {
alloc_mark_stack(2*GC_mark_stack_size);
}
GC_mark_state = MS_PARTIALLY_INVALID;
}
scan_ptr = GC_push_next_marked(scan_ptr);
if (scan_ptr == 0 && GC_mark_state == MS_PARTIALLY_INVALID) {
GC_push_roots(TRUE, cold_gc_frame);
GC_objects_are_marked = TRUE;
if (GC_mark_state != MS_INVALID) {
GC_mark_state = MS_ROOTS_PUSHED;
}
}
return(FALSE);
default:
ABORT("GC_mark_some: bad state");
return(FALSE);
}
#ifdef MSWIN32
} __except (GetExceptionCode() == EXCEPTION_ACCESS_VIOLATION ?
EXCEPTION_EXECUTE_HANDLER : EXCEPTION_CONTINUE_SEARCH) {
# ifdef PRINTSTATS
GC_printf0("Caught ACCESS_VIOLATION in marker. "
"Memory mapping disappeared.\n");
# endif /* PRINTSTATS */
/* We have bad roots on the stack. Discard mark stack. */
/* Rescan from marked objects. Redetermine roots. */
GC_invalidate_mark_state();
scan_ptr = 0;
return FALSE;
}
#endif /* MSWIN32 */
}
GC_bool GC_mark_stack_empty()
{
return(GC_mark_stack_top < GC_mark_stack);
}
#ifdef PROF_MARKER
word GC_prof_array[10];
# define PROF(n) GC_prof_array[n]++
#else
# define PROF(n)
#endif
/* Given a pointer to someplace other than a small object page or the */
/* first page of a large object, return a pointer either to the */
/* start of the large object or NIL. */
/* In the latter case black list the address current. */
/* Returns NIL without black listing if current points to a block */
/* with IGNORE_OFF_PAGE set. */
/*ARGSUSED*/
# ifdef PRINT_BLACK_LIST
ptr_t GC_find_start(current, hhdr, source)
word source;
# else
ptr_t GC_find_start(current, hhdr)
# define source 0
# endif
register ptr_t current;
register hdr * hhdr;
{
# ifdef ALL_INTERIOR_POINTERS
if (hhdr != 0) {
register ptr_t orig = current;
current = (ptr_t)HBLKPTR(current) + HDR_BYTES;
do {
current = current - HBLKSIZE*(word)hhdr;
hhdr = HDR(current);
} while(IS_FORWARDING_ADDR_OR_NIL(hhdr));
/* current points to the start of the large object */
if (hhdr -> hb_flags & IGNORE_OFF_PAGE) return(0);
if ((word *)orig - (word *)current
>= (ptrdiff_t)(hhdr->hb_sz)) {
/* Pointer past the end of the block */
GC_ADD_TO_BLACK_LIST_NORMAL(orig, source);
return(0);
}
return(current);
} else {
GC_ADD_TO_BLACK_LIST_NORMAL(current, source);
return(0);
}
# else
GC_ADD_TO_BLACK_LIST_NORMAL(current, source);
return(0);
# endif
# undef source
}
void GC_invalidate_mark_state()
{
GC_mark_state = MS_INVALID;
GC_mark_stack_top = GC_mark_stack-1;
}
mse * GC_signal_mark_stack_overflow(msp)
mse * msp;
{
GC_mark_state = MS_INVALID;
GC_mark_stack_too_small = TRUE;
# ifdef PRINTSTATS
GC_printf1("Mark stack overflow; current size = %lu entries\n",
GC_mark_stack_size);
# endif
return(msp-INITIAL_MARK_STACK_SIZE/8);
}
/*
* Mark objects pointed to by the regions described by
* mark stack entries between GC_mark_stack and GC_mark_stack_top,
* inclusive. Assumes the upper limit of a mark stack entry
* is never 0. A mark stack entry never has size 0.
* We try to traverse on the order of a hblk of memory before we return.
* Caller is responsible for calling this until the mark stack is empty.
* Note that this is the most performance critical routine in the
* collector. Hence it contains all sorts of ugly hacks to speed
* things up. In particular, we avoid procedure calls on the common
* path, we take advantage of peculiarities of the mark descriptor
* encoding, we optionally maintain a cache for the block address to
* header mapping, we prefetch when an object is "grayed", etc.
*/
void GC_mark_from_mark_stack()
{
mse * GC_mark_stack_reg = GC_mark_stack;
mse * GC_mark_stack_top_reg = GC_mark_stack_top;
mse * mark_stack_limit = &(GC_mark_stack[GC_mark_stack_size]);
int credit = HBLKSIZE; /* Remaining credit for marking work */
register word * current_p; /* Pointer to current candidate ptr. */
register word current; /* Candidate pointer. */
register word * limit; /* (Incl) limit of current candidate */
/* range */
register word descr;
register ptr_t greatest_ha = GC_greatest_plausible_heap_addr;
register ptr_t least_ha = GC_least_plausible_heap_addr;
DECLARE_HDR_CACHE;
# define SPLIT_RANGE_WORDS 128 /* Must be power of 2. */
GC_objects_are_marked = TRUE;
INIT_HDR_CACHE;
# ifdef OS2 /* Use untweaked version to circumvent compiler problem */
while (GC_mark_stack_top_reg >= GC_mark_stack_reg && credit >= 0) {
# else
while ((((ptr_t)GC_mark_stack_top_reg - (ptr_t)GC_mark_stack_reg) | credit)
>= 0) {
# endif
current_p = GC_mark_stack_top_reg -> mse_start;
descr = GC_mark_stack_top_reg -> mse_descr;
retry:
/* current_p and descr describe the current object. */
/* *GC_mark_stack_top_reg is vacant. */
/* The following is 0 only for small objects described by a simple */
/* length descriptor. For many applications this is the common */
/* case, so we try to detect it quickly. */
if (descr & ((~(WORDS_TO_BYTES(SPLIT_RANGE_WORDS) - 1)) | DS_TAGS)) {
word tag = descr & DS_TAGS;
switch(tag) {
case DS_LENGTH:
/* Large length. */
/* Process part of the range to avoid pushing too much on the */
/* stack. */
GC_mark_stack_top_reg -> mse_start =
limit = current_p + SPLIT_RANGE_WORDS-1;
GC_mark_stack_top_reg -> mse_descr =
descr - WORDS_TO_BYTES(SPLIT_RANGE_WORDS-1);
/* Make sure that pointers overlapping the two ranges are */
/* considered. */
limit = (word *)((char *)limit + sizeof(word) - ALIGNMENT);
break;
case DS_BITMAP:
GC_mark_stack_top_reg--;
descr &= ~DS_TAGS;
credit -= WORDS_TO_BYTES(WORDSZ/2); /* guess */
while (descr != 0) {
if ((signed_word)descr < 0) {
current = *current_p;
if ((ptr_t)current >= least_ha && (ptr_t)current < greatest_ha) {
PREFETCH(current);
HC_PUSH_CONTENTS((ptr_t)current, GC_mark_stack_top_reg,
mark_stack_limit, current_p, exit1);
}
}
descr <<= 1;
++ current_p;
}
continue;
case DS_PROC:
GC_mark_stack_top_reg--;
credit -= PROC_BYTES;
GC_mark_stack_top_reg =
(*PROC(descr))
(current_p, GC_mark_stack_top_reg,
mark_stack_limit, ENV(descr));
continue;
case DS_PER_OBJECT:
if ((signed_word)descr >= 0) {
/* Descriptor is in the object. */
descr = *(word *)((ptr_t)current_p + descr - DS_PER_OBJECT);
} else {
/* Descriptor is in type descriptor pointed to by first */
/* word in object. */
ptr_t type_descr = *(ptr_t *)current_p;
/* type_descr is either a valid pointer to the descriptor */
/* structure, or this object was on a free list. If it */
/* it was anything but the last object on the free list, */
/* we will misinterpret the next object on the free list as */
/* the type descriptor, and get a 0 GC descriptor, which */
/* is ideal. Unfortunately, we need to check for the last */
/* object case explicitly. */
if (0 == type_descr) {
/* Rarely executed. */
GC_mark_stack_top_reg--;
continue;
}
descr = *(word *)(type_descr
- (descr - (DS_PER_OBJECT - INDIR_PER_OBJ_BIAS)));
}
goto retry;
}
} else /* Small object with length descriptor */ {
GC_mark_stack_top_reg--;
limit = (word *)(((ptr_t)current_p) + (word)descr);
}
/* The simple case in which we're scanning a range. */
credit -= (ptr_t)limit - (ptr_t)current_p;
limit -= 1;
{
# define PREF_DIST 4
# ifndef SMALL_CONFIG
word deferred;
/* Try to prefetch the next pointer to be examined asap. */
/* Empirically, this also seems to help slightly without */
/* prefetches, at least on linux/X86. Presumably this loop */
/* ends up with less register pressure, and gcc thus ends up */
/* generating slightly better code. Overall gcc code quality */
/* for this loop is still not great. */
for(;;) {
PREFETCH((ptr_t)limit - PREF_DIST*CACHE_LINE_SIZE);
deferred = *limit;
limit = (word *)((char *)limit - ALIGNMENT);
if ((ptr_t)deferred >= least_ha && (ptr_t)deferred < greatest_ha) {
PREFETCH(deferred);
break;
}
if (current_p > limit) goto next_object;
/* Unroll once, so we don't do too many of the prefetches */
/* based on limit. */
deferred = *limit;
limit = (word *)((char *)limit - ALIGNMENT);
if ((ptr_t)deferred >= least_ha && (ptr_t)deferred < greatest_ha) {
PREFETCH(deferred);
break;
}
if (current_p > limit) goto next_object;
}
# endif
while (current_p <= limit) {
/* Empirically, unrolling this loop doesn't help a lot. */
/* Since HC_PUSH_CONTENTS expands to a lot of code, */
/* we don't. */
current = *current_p;
PREFETCH((ptr_t)current_p + PREF_DIST*CACHE_LINE_SIZE);
if ((ptr_t)current >= least_ha && (ptr_t)current < greatest_ha) {
/* Prefetch the contents of the object we just pushed. It's */
/* likely we will need them soon. */
PREFETCH(current);
HC_PUSH_CONTENTS((ptr_t)current, GC_mark_stack_top_reg,
mark_stack_limit, current_p, exit2);
}
current_p = (word *)((char *)current_p + ALIGNMENT);
}
# ifndef SMALL_CONFIG
/* We still need to mark the entry we previously prefetched. */
/* We alrady know that it passes the preliminary pointer */
/* validity test. */
HC_PUSH_CONTENTS((ptr_t)deferred, GC_mark_stack_top_reg,
mark_stack_limit, current_p, exit4);
next_object:;
# endif
}
}
GC_mark_stack_top = GC_mark_stack_top_reg;
}
/* Allocate or reallocate space for mark stack of size s words */
/* May silently fail. */
static void alloc_mark_stack(n)
word n;
{
mse * new_stack = (mse *)GC_scratch_alloc(n * sizeof(struct ms_entry));
GC_mark_stack_too_small = FALSE;
if (GC_mark_stack_size != 0) {
if (new_stack != 0) {
word displ = (word)GC_mark_stack & (GC_page_size - 1);
signed_word size = GC_mark_stack_size * sizeof(struct ms_entry);
/* Recycle old space */
if (0 != displ) displ = GC_page_size - displ;
size = (size - displ) & ~(GC_page_size - 1);
if (size > 0) {
GC_add_to_heap((struct hblk *)
((word)GC_mark_stack + displ), (word)size);
}
GC_mark_stack = new_stack;
GC_mark_stack_size = n;
# ifdef PRINTSTATS
GC_printf1("Grew mark stack to %lu frames\n",
(unsigned long) GC_mark_stack_size);
# endif
} else {
# ifdef PRINTSTATS
GC_printf1("Failed to grow mark stack to %lu frames\n",
(unsigned long) n);
# endif
}
} else {
if (new_stack == 0) {
GC_err_printf0("No space for mark stack\n");
EXIT();
}
GC_mark_stack = new_stack;
GC_mark_stack_size = n;
}
GC_mark_stack_top = GC_mark_stack-1;
}
void GC_mark_init()
{
alloc_mark_stack(INITIAL_MARK_STACK_SIZE);
}
/*
* Push all locations between b and t onto the mark stack.
* b is the first location to be checked. t is one past the last
* location to be checked.
* Should only be used if there is no possibility of mark stack
* overflow.
*/
void GC_push_all(bottom, top)
ptr_t bottom;
ptr_t top;
{
register word length;
bottom = (ptr_t)(((word) bottom + ALIGNMENT-1) & ~(ALIGNMENT-1));
top = (ptr_t)(((word) top) & ~(ALIGNMENT-1));
if (top == 0 || bottom == top) return;
GC_mark_stack_top++;
if (GC_mark_stack_top >= GC_mark_stack + GC_mark_stack_size) {
ABORT("unexpected mark stack overflow");
}
length = top - bottom;
# if DS_TAGS > ALIGNMENT - 1
length += DS_TAGS;
length &= ~DS_TAGS;
# endif
GC_mark_stack_top -> mse_start = (word *)bottom;
GC_mark_stack_top -> mse_descr = length;
}
/*
* Analogous to the above, but push only those pages that may have been
* dirtied. A block h is assumed dirty if dirty_fn(h) != 0.
* We use push_fn to actually push the block.
* Will not overflow mark stack if push_fn pushes a small fixed number
* of entries. (This is invoked only if push_fn pushes a single entry,
* or if it marks each object before pushing it, thus ensuring progress
* in the event of a stack overflow.)
*/
void GC_push_dirty(bottom, top, dirty_fn, push_fn)
ptr_t bottom;
ptr_t top;
int (*dirty_fn)(/* struct hblk * h */);
void (*push_fn)(/* ptr_t bottom, ptr_t top */);
{
register struct hblk * h;
bottom = (ptr_t)(((long) bottom + ALIGNMENT-1) & ~(ALIGNMENT-1));
top = (ptr_t)(((long) top) & ~(ALIGNMENT-1));
if (top == 0 || bottom == top) return;
h = HBLKPTR(bottom + HBLKSIZE);
if (top <= (ptr_t) h) {
if ((*dirty_fn)(h-1)) {
(*push_fn)(bottom, top);
}
return;
}
if ((*dirty_fn)(h-1)) {
(*push_fn)(bottom, (ptr_t)h);
}
while ((ptr_t)(h+1) <= top) {
if ((*dirty_fn)(h)) {
if ((word)(GC_mark_stack_top - GC_mark_stack)
> 3 * GC_mark_stack_size / 4) {
/* Danger of mark stack overflow */
(*push_fn)((ptr_t)h, top);
return;
} else {
(*push_fn)((ptr_t)h, (ptr_t)(h+1));
}
}
h++;
}
if ((ptr_t)h != top) {
if ((*dirty_fn)(h)) {
(*push_fn)((ptr_t)h, top);
}
}
if (GC_mark_stack_top >= GC_mark_stack + GC_mark_stack_size) {
ABORT("unexpected mark stack overflow");
}
}
# ifndef SMALL_CONFIG
void GC_push_conditional(bottom, top, all)
ptr_t bottom;
ptr_t top;
int all;
{
if (all) {
if (GC_dirty_maintained) {
# ifdef PROC_VDB
/* Pages that were never dirtied cannot contain pointers */
GC_push_dirty(bottom, top, GC_page_was_ever_dirty, GC_push_all);
# else
GC_push_all(bottom, top);
# endif
} else {
GC_push_all(bottom, top);
}
} else {
GC_push_dirty(bottom, top, GC_page_was_dirty, GC_push_all);
}
}
#endif
# ifdef MSWIN32
void __cdecl GC_push_one(p)
# else
void GC_push_one(p)
# endif
word p;
{
# ifdef NURSERY
if (0 != GC_push_proc) {
GC_push_proc(p);
return;
}
# endif
GC_PUSH_ONE_STACK(p, MARKED_FROM_REGISTER);
}
# ifdef __STDC__
# define BASE(p) (word)GC_base((void *)(p))
# else
# define BASE(p) (word)GC_base((char *)(p))
# endif
/* As above, but argument passed preliminary test. */
# if defined(PRINT_BLACK_LIST) || defined(KEEP_BACK_PTRS)
void GC_push_one_checked(p, interior_ptrs, source)
ptr_t source;
# else
void GC_push_one_checked(p, interior_ptrs)
# define source 0
# endif
register word p;
register GC_bool interior_ptrs;
{
register word r;
register hdr * hhdr;
register int displ;
GET_HDR(p, hhdr);
if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
if (hhdr != 0 && interior_ptrs) {
r = BASE(p);
hhdr = HDR(r);
displ = BYTES_TO_WORDS(HBLKDISPL(r));
} else {
hhdr = 0;
}
} else {
register map_entry_type map_entry;
displ = HBLKDISPL(p);
map_entry = MAP_ENTRY((hhdr -> hb_map), displ);
if (map_entry == OBJ_INVALID) {
# ifndef ALL_INTERIOR_POINTERS
if (interior_ptrs) {
r = BASE(p);
displ = BYTES_TO_WORDS(HBLKDISPL(r));
if (r == 0) hhdr = 0;
} else {
hhdr = 0;
}
# else
/* map already reflects interior pointers */
hhdr = 0;
# endif
} else {
displ = BYTES_TO_WORDS(displ);
displ -= map_entry;
r = (word)((word *)(HBLKPTR(p)) + displ);
}
}
/* If hhdr != 0 then r == GC_base(p), only we did it faster. */
/* displ is the word index within the block. */
if (hhdr == 0) {
if (interior_ptrs) {
# ifdef PRINT_BLACK_LIST
GC_add_to_black_list_stack(p, source);
# else
GC_add_to_black_list_stack(p);
# endif
} else {
GC_ADD_TO_BLACK_LIST_NORMAL(p, source);
# undef source /* In case we had to define it. */
}
} else {
if (!mark_bit_from_hdr(hhdr, displ)) {
set_mark_bit_from_hdr(hhdr, displ);
GC_STORE_BACK_PTR(source, (ptr_t)r);
PUSH_OBJ((word *)r, hhdr, GC_mark_stack_top,
&(GC_mark_stack[GC_mark_stack_size]));
}
}
}
# ifdef TRACE_BUF
# define TRACE_ENTRIES 1000
struct trace_entry {
char * kind;
word gc_no;
word words_allocd;
word arg1;
word arg2;
} GC_trace_buf[TRACE_ENTRIES];
int GC_trace_buf_ptr = 0;
void GC_add_trace_entry(char *kind, word arg1, word arg2)
{
GC_trace_buf[GC_trace_buf_ptr].kind = kind;
GC_trace_buf[GC_trace_buf_ptr].gc_no = GC_gc_no;
GC_trace_buf[GC_trace_buf_ptr].words_allocd = GC_words_allocd;
GC_trace_buf[GC_trace_buf_ptr].arg1 = arg1 ^ 0x80000000;
GC_trace_buf[GC_trace_buf_ptr].arg2 = arg2 ^ 0x80000000;
GC_trace_buf_ptr++;
if (GC_trace_buf_ptr >= TRACE_ENTRIES) GC_trace_buf_ptr = 0;
}
void GC_print_trace(word gc_no, GC_bool lock)
{
int i;
struct trace_entry *p;
if (lock) LOCK();
for (i = GC_trace_buf_ptr-1; i != GC_trace_buf_ptr; i--) {
if (i < 0) i = TRACE_ENTRIES-1;
p = GC_trace_buf + i;
if (p -> gc_no < gc_no || p -> kind == 0) return;
printf("Trace:%s (gc:%d,words:%d) 0x%X, 0x%X\n",
p -> kind, p -> gc_no, p -> words_allocd,
(p -> arg1) ^ 0x80000000, (p -> arg2) ^ 0x80000000);
}
printf("Trace incomplete\n");
if (lock) UNLOCK();
}
# endif /* TRACE_BUF */
/*
* A version of GC_push_all that treats all interior pointers as valid
* and scans the entire region immediately, in case the contents
* change.
*/
void GC_push_all_eager(bottom, top)
ptr_t bottom;
ptr_t top;
{
word * b = (word *)(((long) bottom + ALIGNMENT-1) & ~(ALIGNMENT-1));
word * t = (word *)(((long) top) & ~(ALIGNMENT-1));
register word *p;
register word q;
register word *lim;
register ptr_t greatest_ha = GC_greatest_plausible_heap_addr;
register ptr_t least_ha = GC_least_plausible_heap_addr;
# define GC_greatest_plausible_heap_addr greatest_ha
# define GC_least_plausible_heap_addr least_ha
if (top == 0) return;
/* check all pointers in range and put in push if they appear */
/* to be valid. */
lim = t - 1 /* longword */;
for (p = b; p <= lim; p = (word *)(((char *)p) + ALIGNMENT)) {
q = *p;
GC_PUSH_ONE_STACK(q, p);
}
# undef GC_greatest_plausible_heap_addr
# undef GC_least_plausible_heap_addr
}
#ifndef THREADS
/*
* A version of GC_push_all that treats all interior pointers as valid
* and scans part of the area immediately, to make sure that saved
* register values are not lost.
* Cold_gc_frame delimits the stack section that must be scanned
* eagerly. A zero value indicates that no eager scanning is needed.
*/
void GC_push_all_stack_partially_eager(bottom, top, cold_gc_frame)
ptr_t bottom;
ptr_t top;
ptr_t cold_gc_frame;
{
# ifdef ALL_INTERIOR_POINTERS
# define EAGER_BYTES 1024
/* Push the hot end of the stack eagerly, so that register values */
/* saved inside GC frames are marked before they disappear. */
/* The rest of the marking can be deferred until later. */
if (0 == cold_gc_frame) {
GC_push_all_stack(bottom, top);
return;
}
# ifdef STACK_GROWS_DOWN
GC_push_all_eager(bottom, cold_gc_frame);
GC_push_all(cold_gc_frame - sizeof(ptr_t), top);
# else /* STACK_GROWS_UP */
GC_push_all_eager(cold_gc_frame, top);
GC_push_all(bottom, cold_gc_frame + sizeof(ptr_t));
# endif /* STACK_GROWS_UP */
# else
GC_push_all_eager(bottom, top);
# endif
# ifdef TRACE_BUF
GC_add_trace_entry("GC_push_all_stack", bottom, top);
# endif
}
#endif /* !THREADS */
void GC_push_all_stack(bottom, top)
ptr_t bottom;
ptr_t top;
{
# ifdef ALL_INTERIOR_POINTERS
GC_push_all(bottom, top);
# else
GC_push_all_eager(bottom, top);
# endif
}
#ifndef SMALL_CONFIG
/* Push all objects reachable from marked objects in the given block */
/* of size 1 objects. */
void GC_push_marked1(h, hhdr)
struct hblk *h;
register hdr * hhdr;
{
word * mark_word_addr = &(hhdr->hb_marks[divWORDSZ(HDR_WORDS)]);
register word *p;
word *plim;
register int i;
register word q;
register word mark_word;
register ptr_t greatest_ha = GC_greatest_plausible_heap_addr;
register ptr_t least_ha = GC_least_plausible_heap_addr;
# define GC_greatest_plausible_heap_addr greatest_ha
# define GC_least_plausible_heap_addr least_ha
p = (word *)(h->hb_body);
plim = (word *)(((word)h) + HBLKSIZE);
/* go through all words in block */
while( p < plim ) {
mark_word = *mark_word_addr++;
i = 0;
while(mark_word != 0) {
if (mark_word & 1) {
q = p[i];
GC_PUSH_ONE_HEAP(q, p + i);
}
i++;
mark_word >>= 1;
}
p += WORDSZ;
}
# undef GC_greatest_plausible_heap_addr
# undef GC_least_plausible_heap_addr
}
#ifndef UNALIGNED
/* Push all objects reachable from marked objects in the given block */
/* of size 2 objects. */
void GC_push_marked2(h, hhdr)
struct hblk *h;
register hdr * hhdr;
{
word * mark_word_addr = &(hhdr->hb_marks[divWORDSZ(HDR_WORDS)]);
register word *p;
word *plim;
register int i;
register word q;
register word mark_word;
register ptr_t greatest_ha = GC_greatest_plausible_heap_addr;
register ptr_t least_ha = GC_least_plausible_heap_addr;
# define GC_greatest_plausible_heap_addr greatest_ha
# define GC_least_plausible_heap_addr least_ha
p = (word *)(h->hb_body);
plim = (word *)(((word)h) + HBLKSIZE);
/* go through all words in block */
while( p < plim ) {
mark_word = *mark_word_addr++;
i = 0;
while(mark_word != 0) {
if (mark_word & 1) {
q = p[i];
GC_PUSH_ONE_HEAP(q, p + i);
q = p[i+1];
GC_PUSH_ONE_HEAP(q, p + i);
}
i += 2;
mark_word >>= 2;
}
p += WORDSZ;
}
# undef GC_greatest_plausible_heap_addr
# undef GC_least_plausible_heap_addr
}
/* Push all objects reachable from marked objects in the given block */
/* of size 4 objects. */
/* There is a risk of mark stack overflow here. But we handle that. */
/* And only unmarked objects get pushed, so it's not very likely. */
void GC_push_marked4(h, hhdr)
struct hblk *h;
register hdr * hhdr;
{
word * mark_word_addr = &(hhdr->hb_marks[divWORDSZ(HDR_WORDS)]);
register word *p;
word *plim;
register int i;
register word q;
register word mark_word;
register ptr_t greatest_ha = GC_greatest_plausible_heap_addr;
register ptr_t least_ha = GC_least_plausible_heap_addr;
# define GC_greatest_plausible_heap_addr greatest_ha
# define GC_least_plausible_heap_addr least_ha
p = (word *)(h->hb_body);
plim = (word *)(((word)h) + HBLKSIZE);
/* go through all words in block */
while( p < plim ) {
mark_word = *mark_word_addr++;
i = 0;
while(mark_word != 0) {
if (mark_word & 1) {
q = p[i];
GC_PUSH_ONE_HEAP(q, p + i);
q = p[i+1];
GC_PUSH_ONE_HEAP(q, p + i + 1);
q = p[i+2];
GC_PUSH_ONE_HEAP(q, p + i + 2);
q = p[i+3];
GC_PUSH_ONE_HEAP(q, p + i + 3);
}
i += 4;
mark_word >>= 4;
}
p += WORDSZ;
}
# undef GC_greatest_plausible_heap_addr
# undef GC_least_plausible_heap_addr
}
#endif /* UNALIGNED */
#endif /* SMALL_CONFIG */
/* Push all objects reachable from marked objects in the given block */
void GC_push_marked(h, hhdr)
struct hblk *h;
register hdr * hhdr;
{
register int sz = hhdr -> hb_sz;
register int descr = hhdr -> hb_descr;
register word * p;
register int word_no;
register word * lim;
register mse * GC_mark_stack_top_reg;
register mse * mark_stack_limit = &(GC_mark_stack[GC_mark_stack_size]);
/* Some quick shortcuts: */
if ((0 | DS_LENGTH) == descr) return;
if (GC_block_empty(hhdr)/* nothing marked */) return;
# ifdef GATHERSTATS
GC_n_rescuing_pages++;
# endif
GC_objects_are_marked = TRUE;
if (sz > MAXOBJSZ) {
lim = (word *)h + HDR_WORDS;
} else {
lim = (word *)(h + 1) - sz;
}
switch(sz) {
# if !defined(SMALL_CONFIG)
case 1:
GC_push_marked1(h, hhdr);
break;
# endif
# if !defined(SMALL_CONFIG) && !defined(UNALIGNED)
case 2:
GC_push_marked2(h, hhdr);
break;
case 4:
GC_push_marked4(h, hhdr);
break;
# endif
default:
GC_mark_stack_top_reg = GC_mark_stack_top;
for (p = (word *)h + HDR_WORDS, word_no = HDR_WORDS; p <= lim;
p += sz, word_no += sz) {
if (mark_bit_from_hdr(hhdr, word_no)) {
/* Mark from fields inside the object */
PUSH_OBJ((word *)p, hhdr, GC_mark_stack_top_reg, mark_stack_limit);
# ifdef GATHERSTATS
/* Subtract this object from total, since it was */
/* added in twice. */
GC_composite_in_use -= sz;
# endif
}
}
GC_mark_stack_top = GC_mark_stack_top_reg;
}
}
#ifndef SMALL_CONFIG
/* Test whether any page in the given block is dirty */
GC_bool GC_block_was_dirty(h, hhdr)
struct hblk *h;
register hdr * hhdr;
{
register int sz = hhdr -> hb_sz;
if (sz < MAXOBJSZ) {
return(GC_page_was_dirty(h));
} else {
register ptr_t p = (ptr_t)h;
sz += HDR_WORDS;
sz = WORDS_TO_BYTES(sz);
while (p < (ptr_t)h + sz) {
if (GC_page_was_dirty((struct hblk *)p)) return(TRUE);
p += HBLKSIZE;
}
return(FALSE);
}
}
#endif /* SMALL_CONFIG */
/* Similar to GC_push_next_marked, but return address of next block */
struct hblk * GC_push_next_marked(h)
struct hblk *h;
{
register hdr * hhdr;
h = GC_next_used_block(h);
if (h == 0) return(0);
hhdr = HDR(h);
GC_push_marked(h, hhdr);
return(h + OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz));
}
#ifndef SMALL_CONFIG
/* Identical to above, but mark only from dirty pages */
struct hblk * GC_push_next_marked_dirty(h)
struct hblk *h;
{
register hdr * hhdr;
if (!GC_dirty_maintained) { ABORT("dirty bits not set up"); }
for (;;) {
h = GC_next_used_block(h);
if (h == 0) return(0);
hhdr = HDR(h);
# ifdef STUBBORN_ALLOC
if (hhdr -> hb_obj_kind == STUBBORN) {
if (GC_page_was_changed(h) && GC_block_was_dirty(h, hhdr)) {
break;
}
} else {
if (GC_block_was_dirty(h, hhdr)) break;
}
# else
if (GC_block_was_dirty(h, hhdr)) break;
# endif
h += OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz);
}
GC_push_marked(h, hhdr);
return(h + OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz));
}
#endif
/* Similar to above, but for uncollectable pages. Needed since we */
/* do not clear marks for such pages, even for full collections. */
struct hblk * GC_push_next_marked_uncollectable(h)
struct hblk *h;
{
register hdr * hhdr = HDR(h);
for (;;) {
h = GC_next_used_block(h);
if (h == 0) return(0);
hhdr = HDR(h);
if (hhdr -> hb_obj_kind == UNCOLLECTABLE) break;
h += OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz);
}
GC_push_marked(h, hhdr);
return(h + OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz));
}