[llvm] 6a9e987 - [VectorCombine] foldPermuteOfBinops - ensure potential identity mask isn't length changing.

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2025-01-14T12:17:21Z
New Revision: 6a9e9878a200a6e494beed8944d6d08347945727

URL: https://github.com/llvm/llvm-project/commit/6a9e9878a200a6e494beed8944d6d08347945727
DIFF: https://github.com/llvm/llvm-project/commit/6a9e9878a200a6e494beed8944d6d08347945727.diff

LOG: [VectorCombine] foldPermuteOfBinops - ensure potential identity mask isn't length changing.

Added: 
    

Modified: 
    llvm/lib/Transforms/Vectorize/VectorCombine.cpp

Removed: 
    


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diff  --git a/llvm/lib/Transforms/Vectorize/VectorCombine.cpp b/llvm/lib/Transforms/Vectorize/VectorCombine.cpp
index d17be8e1ac79ee..88d7cf2013a6b0 100644
--- a/llvm/lib/Transforms/Vectorize/VectorCombine.cpp
+++ b/llvm/lib/Transforms/Vectorize/VectorCombine.cpp
@@ -1639,8 +1639,12 @@ bool VectorCombine::foldPermuteOfBinops(Instruction &I) {
   }
 
   unsigned NumOpElts = Op0Ty->getNumElements();
-  bool IsIdentity0 = ShuffleVectorInst::isIdentityMask(NewMask0, NumOpElts);
-  bool IsIdentity1 = ShuffleVectorInst::isIdentityMask(NewMask1, NumOpElts);
+  bool IsIdentity0 =
+      all_of(NewMask0, [NumOpElts](int M) { return M < (int)NumOpElts; }) &&
+      ShuffleVectorInst::isIdentityMask(NewMask0, NumOpElts);
+  bool IsIdentity1 =
+      all_of(NewMask1, [NumOpElts](int M) { return M < (int)NumOpElts; }) &&
+      ShuffleVectorInst::isIdentityMask(NewMask1, NumOpElts);
 
   // Try to merge shuffles across the binop if the new shuffles are not costly.
   InstructionCost OldCost =