[all-commits] [llvm/llvm-project] c8fd0c: [MC] Make .pseudo_probe sections deterministic aft...

Fangrui Song via All-commits all-commits at lists.llvm.org
Wed Sep 20 13:48:03 PDT 2023

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: c8fd0cf713446ac1f3e9b677ec8500365a98c219
  Author: Fangrui Song <i at maskray.me>
  Date:   2023-09-20 (Wed, 20 Sep 2023)

  Changed paths:
    M llvm/include/llvm/MC/MCPseudoProbe.h

  Log Message:
  [MC] Make .pseudo_probe sections deterministic after D91878

MCPseudoProbeSections::emit iterates over MCProbeDivisions and creates sections.
When the map key is MCSymbol *, the iteration order is not stable. The
underlying BumpPtrAllocator largely decreases the flakiness. That said,
the allocations from BumpPtrAllocator may have different orders.
Under tcmalloc, llvm/test/Transforms/SampleProfile/pseudo-probe-emit.ll fails
about 7 times per 1000 runs.

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