[all-commits] [llvm/llvm-project] 08c9c1: [InstCombine][SVE] Fix visitInsertElementInst for ...

[huihzhang via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 08c9c13749aebd03bec55442301442670fa0b72c
      https://github.com/llvm/llvm-project/commit/08c9c13749aebd03bec55442301442670fa0b72c
  Author: Huihui Zhang <huihuiz at quicinc.com>
  Date:   2020-05-07 (Thu, 07 May 2020)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
    M llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
    A llvm/test/Transforms/InstCombine/vscale_insertelement.ll

  Log Message:
  -----------
  [InstCombine][SVE] Fix visitInsertElementInst for scalable type.

Summary:
This patch fixes the following issues in visitInsertElementInst:

      1. Bail out for scalable type when analysis requires fixed size number of vector elements.
      2. Use cast<FixedVectorType> to get vector number of elements. This ensure assertion
          on scalable vector type.
      3. For scalable type, avoid folding a chain of insertelement into splat:
            insertelt(insertelt(insertelt(insertelt X, %k, 0), %k, 1), %k, 2) ...
              ->
            shufflevector(insertelt(X, %k, 0), undef, zero)
          The length of scalable vector is unknown at compile-time, therefore we don't know if
          given insertelement sequence is valid for splat.

Reviewers: sdesmalen, efriedma, spatel, nikic

Reviewed By: sdesmalen, efriedma

Subscribers: tschuett, hiraditya, rkruppe, psnobl, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D78895