[all-commits] [llvm/llvm-project] a3b12f: [MemDep] Remove cached non-local defs referencing ...

[Oscar Priego via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: a3b12f0cd5337230199fc9c6319cc2c4614f75b8
      https://github.com/llvm/llvm-project/commit/a3b12f0cd5337230199fc9c6319cc2c4614f75b8
  Author: Oscar Priego <oscar.priegov at gmail.com>
  Date:   2026-09-08 (Tue, 08 Sep 2026)

  Changed paths:
    M llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
    M llvm/test/Transforms/GVN/pr46054-md-nonlocaldefcache-cleanup.ll

  Log Message:
  -----------
  [MemDep] Remove cached non-local defs referencing deleted instructions (#219929)

MemoryDependenceResults::removeInstruction() removed entries from
NonLocalDefsCache when the removed non-pointer instruction was itself a
cache key, but did not remove entries where that instruction was the cached
dependency result.

This could leave a stale instruction reachable through NonLocalDefsCache
after GVN erased it. A later non-local load query could then consume the
dangling dependency and crash in GVN::analyzeLoadAvailability().

Use ReverseNonLocalDefsCache to remove forward cache entries whose
dependency result references the removed instruction, keeping both maps
consistent.

Related removal paths now use the existing reverse-map helper, with
consistency assertions to catch future map divergence.

Fixes #219885.

A downstream Mono integration has also hit #219885 in practice when
tagging non-pointer array-header loads with !invariant.group. They
currently gate those tags off as a temporary workaround pending the
upstream fix in this PR:

Phantomical/mono at 7e44c68



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