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Avoid unnecessary allocation from realloc #12

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Merged
merged 3 commits into from
Feb 3, 2019
Merged

Avoid unnecessary allocation from realloc #12

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85cf5dd
Avoid unnecessary allocation from realloc
Theodus Feb 2, 2019
2b8b4c8
Do not realloc if size is in the same sizeclass
Theodus Feb 2, 2019
ae3f9f6
Get alloc size without wrapper
Theodus Feb 3, 2019
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2 changes: 1 addition & 1 deletion src/mem/slab.h
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Original file line number Diff line number Diff line change
Expand Up @@ -71,7 +71,7 @@ namespace snmalloc

meta.debug_slab_invariant(is_short(), this);

if (zero_mem == YesZero)
if constexpr (zero_mem == YesZero)
{
if (rsize < PAGE_ALIGNED_SIZE)
memory_provider.zero(p, rsize);
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10 changes: 7 additions & 3 deletions src/override/malloc.cc
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Expand Up @@ -80,12 +80,16 @@ extern "C"
"Calling realloc on pointer that is not to the start of an allocation");
}
#endif
size_t sz = Alloc::alloc_size(ptr);
// Keep the current allocation if the given size is in the same sizeclass.
if (sz == sizeclass_to_size(size_to_sizeclass(size)))
return ptr;

void* p = SNMALLOC_NAME_MANGLE(malloc)(size);
if (p)
if (p != nullptr)
{
assert(p == Alloc::external_pointer<Start>(p));
size_t sz =
(std::min)(size, SNMALLOC_NAME_MANGLE(malloc_usable_size)(ptr));
sz = (std::min)(size, sz);
memcpy(p, ptr, sz);
SNMALLOC_NAME_MANGLE(free)(ptr);
}
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