[llvm] bf873aa - [VectorCombine] foldShuffleToIdentity - add debug message for match

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2024-12-22T17:21:44Z
New Revision: bf873aa3ecef93c8dc8eb792da9e73ceff120492

URL: https://github.com/llvm/llvm-project/commit/bf873aa3ecef93c8dc8eb792da9e73ceff120492
DIFF: https://github.com/llvm/llvm-project/commit/bf873aa3ecef93c8dc8eb792da9e73ceff120492.diff

LOG: [VectorCombine] foldShuffleToIdentity - add debug message for match

Helps with debugging to show to that the fold found the match.

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 b7956e037ad4b1..61f9b83b5c697c 100644
--- a/llvm/lib/Transforms/Vectorize/VectorCombine.cpp
+++ b/llvm/lib/Transforms/Vectorize/VectorCombine.cpp
@@ -2376,6 +2376,8 @@ bool VectorCombine::foldShuffleToIdentity(Instruction &I) {
   if (NumVisited <= 1)
     return false;
 
+  LLVM_DEBUG(dbgs() << "Found a superfluous identity shuffle: " << I << "\n");
+
   // If we got this far, we know the shuffles are superfluous and can be
   // removed. Scan through again and generate the new tree of instructions.
   Builder.SetInsertPoint(&I);