[all-commits] [llvm/llvm-project] a8332d: [libcxxabi] Make fallback malloc heap size configu...

[Yuxuan Chen via All-commits]

  Branch: refs/heads/users/yuxuanchen1997/libcxxabi-fallback-heap-size
  Home:   https://github.com/llvm/llvm-project
  Commit: a8332da06c9de6ab0df4a32d148d4093b23fd199
      https://github.com/llvm/llvm-project/commit/a8332da06c9de6ab0df4a32d148d4093b23fd199
  Author: Yuxuan Chen <ych at meta.com>
  Date:   2026-02-11 (Wed, 11 Feb 2026)

  Changed paths:
    M libcxxabi/CMakeLists.txt
    M libcxxabi/src/fallback_malloc.cpp

  Log Message:
  -----------
  [libcxxabi] Make fallback malloc heap size configurable via CMake

The emergency fallback heap used during exception handling when
malloc() fails (e.g. under OOM) was hardcoded to 512 bytes, which
is only enough for a few in-flight exceptions. In contrast, libstdc++
reserves ~73 KiB for this purpose.

Add a LIBCXXABI_FALLBACK_MALLOC_HEAP_SIZE CMake option (default 512)
so that builds targeting services that need to survive OOM conditions
can increase the pool size. Validate the value at both CMake configure
time and C++ compile time, since the heap's unsigned short offsets
limit it to ~256 KiB.



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