[all-commits] [llvm/llvm-project] 9d3e56: DAG: Try scalarizing when expanding saturating add...

[Matt Arsenault via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 9d3e56e2eea1849e4b8bd9a46ceb41b9ee2aa017
      https://github.com/llvm/llvm-project/commit/9d3e56e2eea1849e4b8bd9a46ceb41b9ee2aa017
  Author: Matt Arsenault <Matthew.Arsenault at amd.com>
  Date:   2020-07-16 (Thu, 16 Jul 2020)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
    M llvm/test/CodeGen/Thumb2/mve-saturating-arith.ll

  Log Message:
  -----------
  DAG: Try scalarizing when expanding saturating add/sub

In an upcoming AMDGPU patch, the scalar cases will be legal and vector
ops should be scalarized, rather than producing a long sequence of
vector ops which will also need to be scalarized.

Use a lazy heuristic that seems to work and improves the thumb2 MVE
test.