[all-commits] [llvm/llvm-project] 42229b: [LICM] Only create load in pre-header when promoti...

[Florian Hahn via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 42229b96bf94ec896d5c62fa643d83ba96e86eea
      https://github.com/llvm/llvm-project/commit/42229b96bf94ec896d5c62fa643d83ba96e86eea
  Author: Florian Hahn <flo at fhahn.com>
  Date:   2022-04-11 (Mon, 11 Apr 2022)

  Changed paths:
    M llvm/lib/Transforms/Scalar/LICM.cpp
    M llvm/test/Transforms/LICM/scalar-promote.ll

  Log Message:
  -----------
  [LICM] Only create load in pre-header when promoting load.

When only a store is sunk, there is no need to create a load in the
pre-header, as the result of the load will never get used.

The dead load can can introduce UB, if the function is marked as
writeonly.

Fixes #51248.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D123473