Specialize heap small and large chunk implementations #4366
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Prior to this commit, the heap
chunk_t
was generic for both small and large chunks taking up more space than required for either one.This commit specializes the small and large chunk structures by using pointer tagging on the
chunk->m
field to keep track of the chunk type and large chunk slot/shallow/finaliser and the small chunk sizeclass. This should in theory improve performance as now thelarge_chunk_t
is 32 bytes andsmall_chunk_t
is 36 bytes on 64 bit platforms (whilechunk_t
was previously 44 bytes.There are no logic changes other than whatever was required to support the specialization.