[all-commits] [llvm/llvm-project] 79ea83: [SelectionDAG] memcpy expansion of const volatile ...

[simonwallis2 via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 79ea83e104e368ef0f520f1bfa74c15d91baef93
      https://github.com/llvm/llvm-project/commit/79ea83e104e368ef0f520f1bfa74c15d91baef93
  Author: Simon Wallis <simon.wallis2 at arm.com>
  Date:   2020-09-07 (Mon, 07 Sep 2020)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
    A llvm/test/CodeGen/ARM/memcpy-const-vol-struct.ll

  Log Message:
  -----------
  [SelectionDAG] memcpy expansion of const volatile struct ignores const zero

In getMemcpyLoadsAndStores(), a memcpy where the source is a zero constant is expanded to a MemOp::Set instead of a MemOp::Copy, even when the memcpy is volatile.
This is incorrect.

The fix is to add a check for volatile, and expand to MemOp::Copy in the volatile case.

Reviewed By: chill

Differential Revision: https://reviews.llvm.org/D87134