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[DAGCombine] A shuffle of a splat is always the splat itself
authorZvi Rackover <zvi.rackover@intel.com>
Thu, 30 Mar 2017 01:42:57 +0000 (01:42 +0000)
committerZvi Rackover <zvi.rackover@intel.com>
Thu, 30 Mar 2017 01:42:57 +0000 (01:42 +0000)
commit2f7335804b26719b793f0a9089317913f787819d
tree74a69dedc9b39834f6fcdd9db4052a6fdcf9c09e
parent2d9dd043ff6c00dd54abe4a970046f497f5f704c
[DAGCombine]  A shuffle of a splat is always the splat itself

Summary:
Add a simplification:
shuffle (splat-shuffle), undef, M --> splat-shuffle

Fixes pr32449

Patch by Sanjay Patel

Reviewers: eli.friedman, RKSimon, spatel

Reviewed By: spatel

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D31426

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@299047 91177308-0d34-0410-b5e6-96231b3b80d8
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
test/CodeGen/X86/shuffle-of-splat-multiuses.ll