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Look up the previous block again after a GC in jmem_heap_realloc_block (#3021)

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Garbage collection can create new free blocks in the heap structure as
it releases memory, so the previous block needs to be looked up again
if a GC happens during a realloc.

JerryScript-DCO-1.0-Signed-off-by: Dániel Bátyai dbatyai@inf.u-szeged.hu
This commit is contained in:
Dániel Bátyai
2019-08-28 14:58:35 +02:00
committed by GitHub
parent 26d48c3e28
commit 5fa0a690eb
1 changed files with 10 additions and 4 deletions
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jerry-core/jmem/jmem-heap.c
+10 -4
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@@ -516,8 +516,6 @@ jmem_heap_realloc_block (void *ptr, /**< memory region to reallocate */
return block_p;
}
jmem_heap_free_t *prev_p = jmem_heap_find_prev (block_p);
if (aligned_new_size < aligned_old_size)
{
JMEM_VALGRIND_NOACCESS_SPACE (block_p, old_size);
@@ -525,7 +523,7 @@ jmem_heap_realloc_block (void *ptr, /**< memory region to reallocate */
JMEM_HEAP_STAT_FREE (old_size);
JMEM_HEAP_STAT_ALLOC (new_size);
jmem_heap_insert_block ((jmem_heap_free_t *)((uint8_t *) block_p + aligned_new_size),
prev_p,
jmem_heap_find_prev (block_p),
aligned_old_size - aligned_new_size);
JERRY_CONTEXT (jmem_heap_allocated_size) -= (aligned_old_size - aligned_new_size);
@@ -547,6 +545,7 @@ jmem_heap_realloc_block (void *ptr, /**< memory region to reallocate */
ecma_free_unused_memory (JMEM_PRESSURE_LOW);
}
jmem_heap_free_t *prev_p = jmem_heap_find_prev (block_p);
JMEM_VALGRIND_DEFINED_SPACE (prev_p, sizeof (jmem_heap_free_t));
jmem_heap_free_t * const next_p = JMEM_HEAP_GET_ADDR_FROM_OFFSET (prev_p->next_offset);
JMEM_VALGRIND_DEFINED_SPACE (next_p, sizeof (jmem_heap_free_t));
@@ -619,8 +618,15 @@ jmem_heap_realloc_block (void *ptr, /**< memory region to reallocate */
/* jmem_heap_alloc_block_internal will adjust the allocated_size, but insert_block will not,
so we reduce it here first, so that the limit calculation remains consistent. */
JERRY_CONTEXT (jmem_heap_allocated_size) -= aligned_old_size;
ret_block_p = jmem_heap_alloc_block_internal (new_size);
/* jmem_heap_alloc_block_internal may trigger garbage collection, which can create new free blocks
* in the heap structure, so we need to look up the previous block again. */
if (JERRY_UNLIKELY (JERRY_CONTEXT (ecma_gc_new_objects) == 0))
{
prev_p = jmem_heap_find_prev (block_p);
}
memcpy (ret_block_p, block_p, old_size);
jmem_heap_insert_block (block_p, prev_p, aligned_old_size);
}