[all-commits] [llvm/llvm-project] 290e9d: [libc][__support] Fix linear fast path for first e...

[Schrodinger ZHU Yifan via All-commits]

  Branch: refs/heads/users/schrodingerzhu/libc-use-tlsf-freestore
  Home:   https://github.com/llvm/llvm-project
  Commit: 290e9d59155f0e52efce8094dc57babddb34af37
      https://github.com/llvm/llvm-project/commit/290e9d59155f0e52efce8094dc57babddb34af37
  Author: Yifan Zhu <yfzhu at google.com>
  Date:   2026-07-31 (Fri, 31 Jul 2026)

  Changed paths:
    M libc/src/__support/freestore.h
    M libc/test/src/__support/freelist_heap_test.cpp

  Log Message:
  -----------
  [libc][__support] Fix linear fast path for first exponential bin in TLSFFreeStoreImpl

Linear bins occupy indices 0 to EXP_BASE - 1. Index EXP_BASE (32) is the first exponential bin.
Previously, index_to_min_size and the linear fast path in find_and_remove_fit used <= EXP_BASE,
which treated index EXP_BASE as a linear bin. This caused find_and_remove_fit to return the
first block in bin EXP_BASE without checking if its size was sufficient for the request.

This change replaces <= with < when comparing against EXP_BASE in index_to_min_size and
find_and_remove_fit, and adds a unit test (NegativeTestForFullHeap).

TAG=agy
CONV=cff84e8c-ee22-4f39-af3c-344d1e6f417b



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