[all-commits] [llvm/llvm-project] 34a34f: [HashRecognize] Prevent values other than `Compute...

[Sean Clarke via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 34a34f1dac1d40e2ba49f39e9ebce8eafdf44ecc
      https://github.com/llvm/llvm-project/commit/34a34f1dac1d40e2ba49f39e9ebce8eafdf44ecc
  Author: Sean Clarke <sclarke at tenstorrent.com>
  Date:   2026-07-31 (Fri, 31 Jul 2026)

  Changed paths:
    M llvm/lib/Analysis/HashRecognize.cpp
    M llvm/test/Analysis/HashRecognize/cyclic-redundancy-check.ll

  Log Message:
  -----------
  [HashRecognize] Prevent values other than `ComputedValue` from exiting loop (#213080)

A check exists to prevent recurrences from having stray uses, but this
is only applied when a simple recurrence exists, and does not apply to
other values such as the induction variable. Since the loop is in LCSSA
form, check the incoming value from the loop on each of the exit block
PHIs and bail if any of them are not `ComputedValue`.

This replaces the existing check requiring `ComputedValue` to be used in
the exit block. Note that this no longer covers the case where the exit
block has no PHIs, and therefore does not use `ComputedValue`. In this
case, the loop is dead and will be cleaned up by DCE anyway.



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