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GC tweaks

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In a minor collection, old-generation pages can be ignored for
the fixup pass. Also, the "moved" bit implies the "marked" bit.

Also, move the mark bits to low and the hash bits to high,
which leads to slightly better generated code for the GC.
This commit is contained in:
Matthew Flatt 2013-04-10 21:31:59 -06:00
parent f7ca24d1b3
commit 661a1dd5e2
2 changed files with 20 additions and 12 deletions
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3
src/racket/gc2/gc2_obj.h
View File

@ -9,7 +9,6 @@
# define LOG_APAGE_SIZE 14
#endif
typedef struct objhead {
uintptr_t hash : ((8 * sizeof(intptr_t)) - (4+3+LOG_APAGE_SIZE) );
/* the type and size of the object */
uintptr_t type : 3;
/* these are the various mark bits we use */
@ -19,6 +18,8 @@ typedef struct objhead {
uintptr_t moved : 1;
uintptr_t dead : 1;
uintptr_t size : LOG_APAGE_SIZE;
/* leftover bits are used for hashing: */
uintptr_t hash : ((8 * sizeof(intptr_t)) - (4+3+LOG_APAGE_SIZE) );
} objhead;
#define OBJHEAD_SIZE (sizeof(objhead))

29
src/racket/gc2/newgc.c
View File

@ -1816,10 +1816,10 @@ inline static void reset_nursery(NewGC *gc)
resize_gen0(gc, new_gen0_size);
}
inline static mpage *pagemap_find_page_for_marking(NewGC *gc, const void *p) {
inline static mpage *pagemap_find_page_for_marking(NewGC *gc, const void *p, int fixup) {
mpage *page;
page = pagemap_find_page(gc->page_maps, p);
if (page && !gc->gc_full && page->generation && !page->marked_on) return NULL;
if (page && !gc->gc_full && page->generation && (fixup || !page->marked_on)) return NULL;
return page;
}
@ -1834,7 +1834,7 @@ inline static int marked(NewGC *gc, const void *p)
mpage *page;
if(!p) return 0;
if(!(page = pagemap_find_page_for_marking(gc, p))) return 1;
if(!(page = pagemap_find_page_for_marking(gc, p, 0))) return 1;
switch(page->size_class) {
case SIZE_CLASS_BIG_PAGE_MARKED:
return 1;
@ -3108,7 +3108,7 @@ void GC_mark2(const void *const_p, struct NewGC *gc)
return;
}
if(!(page = pagemap_find_page_for_marking(gc, p))) {
if(!(page = pagemap_find_page_for_marking(gc, p, 0))) {
#ifdef MZ_USE_PLACES
if (MASTERGC && MASTERGC->major_places_gc && (page = pagemap_find_page(MASTERGC->page_maps, p))) {
is_a_master_page = 1;
@ -3327,7 +3327,7 @@ static inline void propagate_marks_worker(NewGC *gc, Mark2_Proc *mark_table, voi
if (IS_BIG_PAGE_PTR(pp)) {
mpage *page;
p = REMOVE_BIG_PAGE_PTR_TAG(pp);
page = pagemap_find_page_for_marking(gc, p);
page = pagemap_find_page_for_marking(gc, p, 0);
#ifdef MZ_USE_PLACES
if (!page && MASTERGC && MASTERGC->major_places_gc) {
page = pagemap_find_page(MASTERGC->page_maps, p);
@ -3421,7 +3421,7 @@ static void promote_marked_gen0_big_pages(NewGC *gc) {
void *GC_resolve2(void *p, NewGC *gc)
{
mpage *page = pagemap_find_page_for_marking(gc, p);
mpage *page = pagemap_find_page_for_marking(gc, p, 1);
objhead *info;
if(!page || page->size_class)
@ -3449,17 +3449,24 @@ void GC_fixup2(void *pp, struct NewGC *gc)
mpage *page;
void *p = *(void**)pp;
if(!p || (NUM(p) & 0x1))
if (!p || (NUM(p) & 0x1))
return;
if((page = pagemap_find_page_for_marking(gc, p))) {
page = pagemap_find_page_for_marking(gc, p, 1);
if (page) {
objhead *info;
if(page->size_class) return;
if (page->size_class) return;
info = OBJPTR_TO_OBJHEAD(p);
if(info->mark && info->moved)
/* assert: info->moved => info->mark */
/* !gc->gc_full => info->moved */
if (info->moved)
*(void**)pp = *(void**)p;
else GCDEBUG((DEBUGOUTF, "Not repairing %p from %p (not moved)\n",p,pp));
else {
GCDEBUG((DEBUGOUTF, "Not repairing %p from %p (not moved)\n",p,pp));
}
} else {
#ifdef POINTER_OWNERSHIP_CHECK
check_page_owner(gc, p);