[all-commits] [llvm/llvm-project] ccf49b: [GlobalISel] support widen unmerge if WideTy > SrcTy

[Dominik Montada via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: ccf49b9ef012bab44b1f1322223e8b2e5ca89bad
      https://github.com/llvm/llvm-project/commit/ccf49b9ef012bab44b1f1322223e8b2e5ca89bad
  Author: Dominik Montada <dominik.montada at hightec-rt.com>
  Date:   2020-03-23 (Mon, 23 Mar 2020)

  Changed paths:
    M llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
    M llvm/test/CodeGen/AMDGPU/GlobalISel/legalize-unmerge-values.mir
    M llvm/unittests/CodeGen/GlobalISel/LegalizerHelperTest.cpp

  Log Message:
  -----------
  [GlobalISel] support widen unmerge if WideTy > SrcTy

Summary:
Widening G_UNMERGE_VALUES to a type which is larger than the
original source type is the same as widening it to the same
type as the source type: in both cases, G_UNMERGE_VALUES has
to be replaced with bit arithmetic which. Although the arithmetic
itself is independent of whether the source type is smaller
or equal to the widen type, widening the source type to the
widen type should result in less artifacts being emitted,
since this is the type that the user explicitly requested.

Reviewers: arsenm, dsanders, aemerson, aditya_nandakumar

Reviewed By: arsenm, dsanders

Subscribers: jvesely, wdng, nhaehnle, rovka, hiraditya, volkan, kerbowa, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D76494