llvm-project

243ddf60 - [libc] add shrink in-place support for reallocations (#200272)

[libc] add shrink in-place support for reallocations (#200272) This PR adds shrinking in-place for the freelist heap. This allows the heap to reuse the place if the reallocation shrinks the size larger than a minimal block unit. Synthesized random action tests show that that increase heap utilization rate from 87% to 97% percent, basically aligns with the expectation of dlmalloc. Assisted-by: AI tools, manually checked.