[all-commits] [llvm/llvm-project] 7a7dc7: [SampleProfile] Preserve first stale profile CG match

[Yuxuan Chen via All-commits]

  Branch: refs/heads/users/yuxuanchen1997/fix-stale-profile-anchor-overwrite
  Home:   https://github.com/llvm/llvm-project
  Commit: 7a7dc7ddebe6b6fa1a06c25378262f084bc700bd
      https://github.com/llvm/llvm-project/commit/7a7dc7ddebe6b6fa1a06c25378262f084bc700bd
  Author: Yuxuan Chen <ych at meta.com>
  Date:   2026-07-10 (Fri, 10 Jul 2026)

  Changed paths:
    M llvm/lib/Transforms/IPO/SampleProfileMatcher.cpp
    A llvm/test/Transforms/SampleProfile/Inputs/pseudo-probe-stale-profile-lcs-anchor-overwrite.prof
    A llvm/test/Transforms/SampleProfile/pseudo-probe-stale-profile-lcs-anchor-overwrite.ll

  Log Message:
  -----------
  [SampleProfile] Preserve first stale profile CG match

During stale profile LCS matching, the matcher may compare the same IR function against multiple profile candidates. This can happen for overloads that share a demangled basename. The comparison result is useful for the current LCS, but rewriting FuncToProfileNameMap on every successful comparison can replace the profile selected for an IR function with a later candidate.

If another IR function is also matched to that later candidate, both functions can end up using the same stale CFG location map and runStaleProfileMatching asserts that the map is already populated.

Preserve the first selected profile mapping with try_emplace while still caching each pairwise comparison result. Add a regression with a minimal sample profile that used to trigger the assertion.



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