[llvm] fc31b58 - [InstCombine] simplify code for shuffle mask canonicalization; NFC

[Sanjay Patel via llvm-commits]

Author: Sanjay Patel
Date: 2019-11-25T11:11:12-05:00
New Revision: fc31b58eff9da4447f9f332f07de3cd07ab4b56c

URL: https://github.com/llvm/llvm-project/commit/fc31b58eff9da4447f9f332f07de3cd07ab4b56c
DIFF: https://github.com/llvm/llvm-project/commit/fc31b58eff9da4447f9f332f07de3cd07ab4b56c.diff

LOG: [InstCombine] simplify code for shuffle mask canonicalization; NFC

We never use the local 'Mask' before returning, so that was dead code.

Added: 
    

Modified: 
    llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp

Removed: 
    


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diff  --git a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
index 2f9d342daca0..fd31f524e5ce 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
@@ -1900,13 +1900,11 @@ Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
         continue;
       }
 
-      if (Mask[i] < (int)LHSWidth && isa<UndefValue>(LHS)) {
-        Mask[i] = -1;     // Turn into undef.
+      // Change select of undef to undef mask element or force to LHS.
+      if (Mask[i] < (int)LHSWidth && isa<UndefValue>(LHS))
         Elts.push_back(UndefValue::get(Int32Ty));
-      } else {
-        Mask[i] = Mask[i] % LHSWidth;  // Force to LHS.
-        Elts.push_back(ConstantInt::get(Int32Ty, Mask[i]));
-      }
+      else
+        Elts.push_back(ConstantInt::get(Int32Ty, Mask[i] % LHSWidth));
     }
     SVI.setOperand(0, SVI.getOperand(1));
     SVI.setOperand(1, UndefValue::get(RHS->getType()));