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fix padding check for aligned allocation; improve perf for small aligned allocations

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daan 2020-01-31 13:20:02 -08:00
parent 7ff3ec2bf7
commit 4531367de2
5 changed files with 53 additions and 47 deletions
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8
src/alloc-aligned.c
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@ -18,20 +18,22 @@ static void* mi_heap_malloc_zero_aligned_at(mi_heap_t* const heap, const size_t
// note: we don't require `size > offset`, we just guarantee that
// the address at offset is aligned regardless of the allocated size.
mi_assert(alignment > 0 && alignment % sizeof(void*) == 0);
if (alignment <= MI_MAX_ALIGN_SIZE && offset==0) return _mi_heap_malloc_zero(heap, size, zero);
if (mi_unlikely(size > PTRDIFF_MAX)) return NULL; // we don't allocate more than PTRDIFF_MAX (see <https://sourceware.org/ml/libc-announce/2019/msg00001.html>)
if (mi_unlikely(alignment==0 || !_mi_is_power_of_two(alignment))) return NULL; // require power-of-two (see <https://en.cppreference.com/w/c/memory/aligned_alloc>)
const uintptr_t align_mask = alignment-1; // for any x, `(x & align_mask) == (x % alignment)`
// try if there is a small block available with just the right alignment
if (mi_likely(size <= MI_SMALL_SIZE_MAX)) {
mi_page_t* page = _mi_heap_get_free_small_page(heap,size);
if (mi_likely(size <= (MI_SMALL_SIZE_MAX - MI_PADDING_SIZE))) {
mi_page_t* page = _mi_heap_get_free_small_page(heap,size + MI_PADDING_SIZE);
const bool is_aligned = (((uintptr_t)page->free+offset) & align_mask)==0;
if (mi_likely(page->free != NULL && is_aligned))
{
#if MI_STAT>1
mi_heap_stat_increase( heap, malloc, size);
#endif
void* p = _mi_page_malloc(heap,page,size); // TODO: inline _mi_page_malloc
void* p = _mi_page_malloc(heap,page,size + MI_PADDING_SIZE); // TODO: inline _mi_page_malloc
mi_assert_internal(p != NULL);
mi_assert_internal(((uintptr_t)p + offset) % alignment == 0);
if (zero) _mi_block_zero_init(page,p,size);