[all-commits] [llvm/llvm-project] 274a9b: [DSE] Support redundant stores eliminated by memset.

[Florian Hahn via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 274a9b0f0b4e9f6a8520e92d9eff629815436e28
      https://github.com/llvm/llvm-project/commit/274a9b0f0b4e9f6a8520e92d9eff629815436e28
  Author: Florian Hahn <flo at fhahn.com>
  Date:   2021-10-29 (Fri, 29 Oct 2021)

  Changed paths:
    M llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
    M llvm/test/Transforms/DeadStoreElimination/stores-of-existing-values.ll

  Log Message:
  -----------
  [DSE] Support redundant stores eliminated by memset.

This patch adds support to remove stores that write the same value
as earlier memesets.

It uses isOverwrite to check that a memset completely overwrites a later
store. The candidate store must store the same bytewise value as the
byte stored by the memset.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D112321