[all-commits] [llvm/llvm-project] d4c070: [VectorCombine] Freeze index unless it is known to...

[Florian Hahn via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: d4c070d801413186c5a59cede9d721e9ca099708
      https://github.com/llvm/llvm-project/commit/d4c070d801413186c5a59cede9d721e9ca099708
  Author: Florian Hahn <flo at fhahn.com>
  Date:   2021-06-01 (Tue, 01 Jun 2021)

  Changed paths:
    M llvm/lib/Transforms/Vectorize/VectorCombine.cpp
    M llvm/test/Transforms/VectorCombine/AArch64/load-extractelement-scalarization.ll

  Log Message:
  -----------
  [VectorCombine] Freeze index unless it is known to be non-poison.

If the index itself is already poison, the poison propagates through
instructions clamping the index to a valid range. This still causes
introducing a load of poison, as flagged by Alive2 and pointed out
at 575e2aff5574.

This patch updates the code to freeze the index, unless it is proven to
not be poison.

Reviewed By: nlopes

Differential Revision: https://reviews.llvm.org/D103378