[all-commits] [llvm/llvm-project] 3504ac: [ARM] Don't mark vctp as having sideeffects

[David Green via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 3504acc33e8b9ddd7de71d75cdc329a14dbf58d9
      https://github.com/llvm/llvm-project/commit/3504acc33e8b9ddd7de71d75cdc329a14dbf58d9
  Author: David Green <david.green at arm.com>
  Date:   2020-07-19 (Sun, 19 Jul 2020)

  Changed paths:
    M llvm/lib/Target/ARM/ARMInstrMVE.td
    M llvm/test/CodeGen/Thumb2/mve-float16regloops.ll
    M llvm/test/CodeGen/Thumb2/mve-vctp.ll

  Log Message:
  -----------
  [ARM] Don't mark vctp as having sideeffects

As far as I can tell, it should not be necessary for VCTP to be
unpredictable in tail predicated loops. Either it has a a valid loop
counter as a operand which will naturally keep it in the right loop, or
it doesn't and it won't be converted to a tail predicated loop. Not
marking it as having side effects allows it to be scheduled more cleanly
for cases where it is not expected to become a tail predicate loop.

Differential Revision: https://reviews.llvm.org/D83907