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Store next_free pointer to free blocks only

db4
Slava Pestov 2009-03-19 03:00:21 -05:00
parent d72e395b2e
commit 44d61b71f6
2 changed files with 30 additions and 25 deletions
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42
vm/code_gc.c
View File

@ -13,7 +13,7 @@ void new_heap(F_HEAP *heap, CELL size)
/* If there is no previous block, next_free becomes the head of the free list, /* If there is no previous block, next_free becomes the head of the free list,
else its linked in */ else its linked in */
INLINE void update_free_list(F_HEAP *heap, F_BLOCK *prev, F_BLOCK *next_free) INLINE void update_free_list(F_HEAP *heap, F_FREE_BLOCK *prev, F_FREE_BLOCK *next_free)
{ {
if(prev) if(prev)
prev->next_free = next_free; prev->next_free = next_free;
@ -28,18 +28,18 @@ compiling.limit. */
void build_free_list(F_HEAP *heap, CELL size) void build_free_list(F_HEAP *heap, CELL size)
{ {
F_BLOCK *prev = NULL; F_BLOCK *prev = NULL;
F_BLOCK *prev_free = NULL; F_FREE_BLOCK *prev_free = NULL;
F_BLOCK *scan = first_block(heap); F_BLOCK *scan = first_block(heap);
F_BLOCK *end = (F_BLOCK *)(heap->segment->start + size); F_FREE_BLOCK *end = (F_FREE_BLOCK *)(heap->segment->start + size);
/* Add all free blocks to the free list */ /* Add all free blocks to the free list */
while(scan && scan < end) while(scan && scan < (F_BLOCK *)end)
{ {
switch(scan->status) switch(scan->status)
{ {
case B_FREE: case B_FREE:
update_free_list(heap,prev_free,scan); update_free_list(heap,prev_free,(F_FREE_BLOCK *)scan);
prev_free = scan; prev_free = (F_FREE_BLOCK *)scan;
break; break;
case B_ALLOCATED: case B_ALLOCATED:
break; break;
@ -56,9 +56,9 @@ void build_free_list(F_HEAP *heap, CELL size)
branch is only taken after loading a new image, not after code GC */ branch is only taken after loading a new image, not after code GC */
if((CELL)(end + 1) <= heap->segment->end) if((CELL)(end + 1) <= heap->segment->end)
{ {
end->status = B_FREE; end->block.status = B_FREE;
end->block.size = heap->segment->end - (CELL)end;
end->next_free = NULL; end->next_free = NULL;
end->size = heap->segment->end - (CELL)end;
/* add final free block */ /* add final free block */
update_free_list(heap,prev_free,end); update_free_list(heap,prev_free,end);
@ -82,18 +82,18 @@ void build_free_list(F_HEAP *heap, CELL size)
/* Allocate a block of memory from the mark and sweep GC heap */ /* Allocate a block of memory from the mark and sweep GC heap */
void *heap_allot(F_HEAP *heap, CELL size) void *heap_allot(F_HEAP *heap, CELL size)
{ {
F_BLOCK *prev = NULL; F_FREE_BLOCK *prev = NULL;
F_BLOCK *scan = heap->free_list; F_FREE_BLOCK *scan = heap->free_list;
size = (size + 31) & ~31; size = (size + 31) & ~31;
while(scan) while(scan)
{ {
CELL this_size = scan->size - sizeof(F_BLOCK); if(scan->block.status != B_FREE)
if(scan->status != B_FREE)
critical_error("Invalid block in free list",(CELL)scan); critical_error("Invalid block in free list",(CELL)scan);
CELL this_size = scan->block.size - sizeof(F_BLOCK);
if(this_size < size) if(this_size < size)
{ {
prev = scan; prev = scan;
@ -102,9 +102,9 @@ void *heap_allot(F_HEAP *heap, CELL size)
} }
/* we found a candidate block */ /* we found a candidate block */
F_BLOCK *next_free; F_FREE_BLOCK *next_free;
if(this_size - size <= sizeof(F_BLOCK)) if(this_size - size <= sizeof(F_BLOCK) * 2)
{ {
/* too small to be split */ /* too small to be split */
next_free = scan->next_free; next_free = scan->next_free;
@ -113,11 +113,11 @@ void *heap_allot(F_HEAP *heap, CELL size)
{ {
/* split the block in two */ /* split the block in two */
CELL new_size = size + sizeof(F_BLOCK); CELL new_size = size + sizeof(F_BLOCK);
F_BLOCK *split = (F_BLOCK *)((CELL)scan + new_size); F_FREE_BLOCK *split = (F_FREE_BLOCK *)((CELL)scan + new_size);
split->status = B_FREE; split->block.status = B_FREE;
split->size = scan->size - new_size; split->block.size = scan->block.size - new_size;
split->next_free = scan->next_free; split->next_free = scan->next_free;
scan->size = new_size; scan->block.size = new_size;
next_free = split; next_free = split;
} }
@ -125,9 +125,9 @@ void *heap_allot(F_HEAP *heap, CELL size)
update_free_list(heap,prev,next_free); update_free_list(heap,prev,next_free);
/* this is our new block */ /* this is our new block */
scan->status = B_ALLOCATED; scan->block.status = B_ALLOCATED;
return scan + 1; return &scan->block + 1;
} }
return NULL; return NULL;

13
vm/code_gc.h
View File

@ -12,16 +12,21 @@ typedef struct _F_BLOCK
/* In bytes, includes this header */ /* In bytes, includes this header */
CELL size; CELL size;
/* Filled in on image load */
struct _F_BLOCK *next_free;
/* Used during compaction */ /* Used during compaction */
struct _F_BLOCK *forwarding; struct _F_BLOCK *forwarding;
} F_BLOCK; } F_BLOCK;
typedef struct _F_FREE_BLOCK
{
F_BLOCK block;
/* Filled in on image load */
struct _F_FREE_BLOCK *next_free;
} F_FREE_BLOCK;
typedef struct { typedef struct {
F_SEGMENT *segment; F_SEGMENT *segment;
F_BLOCK *free_list; F_FREE_BLOCK *free_list;
} F_HEAP; } F_HEAP;
void new_heap(F_HEAP *heap, CELL size); void new_heap(F_HEAP *heap, CELL size);