Adopt malloc_type for allocating Swift objects from runtime #63226
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| void *swift::swift_slowAllocTyped(size_t size, size_t alignMask, | ||
| MallocTypeId typeId) { |
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At first, I had the calls to the old and new malloc APIs in one function and let the untyped one forward to the typed one:
void *swift_slowAlloc(size_t size, size_t alignMask) {
return swift_slowAllocTyped(size, alignMask, /*typeId=*/0);
}
But the #if became very unwieldy, so I decided to turn it around (Typed variant doing it's thing and having the untyped one as a fallback) and accept a bit of code duplication.
| static size_t computeAlignment(size_t alignMask) { | ||
| return (alignMask == ~(size_t(0))) ? _swift_MinAllocationAlignment | ||
| : alignMask + 1; | ||
| } | ||
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Extract this helper to reduce code duplication. Also: relevant comment is now right next to the code.
stdlib/public/runtime/HeapObject.cpp
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| @@ -115,12 +118,77 @@ static HeapObject *_swift_tryRetain_(HeapObject *object) | |||
| return _ ## name ## _ args; \ | |||
| } while(0) | |||
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| #if defined(_MALLOC_TYPE_ENABLED) | |||
| static malloc_type_id_t computeTypeId(const HeapMetadata *heapMetadata) { | |||
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I want to cache the malloc_type_descriptor_t (32 bit) value computed here. Any suggestions on how to best do this? We will require one value per heap-allocated type.
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The cost of caching it would probably exceed the cost of doing the computation here (which is going to compile to a couple of few arithmetic instructions.)
I might factor it out into another function, but I don't think it's worth trying to cache unless profiling shows this computation is a bottleneck.
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