From 8f4d2e02bea6933d7f4c35f577bf5780bad93beb Mon Sep 17 00:00:00 2001
From: Simon Pilgrim <llvm-dev@redking.me.uk>
Date: Sat, 1 Mar 2025 09:57:08 +0000
Subject: [PATCH] [VectorCombine] scalarizeLoadExtract - add debug message for
 match + cost-comparison

Helps with debugging to show to that the fold found the match, and shows the old + new costs to indicate whether the fold was/wasn't profitable.
---
 llvm/lib/Transforms/Vectorize/VectorCombine.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/llvm/lib/Transforms/Vectorize/VectorCombine.cpp b/llvm/lib/Transforms/Vectorize/VectorCombine.cpp
index 2e20961b4c912..bb4e1c0f67e79 100644
--- a/llvm/lib/Transforms/Vectorize/VectorCombine.cpp
+++ b/llvm/lib/Transforms/Vectorize/VectorCombine.cpp
@@ -1612,6 +1612,10 @@ bool VectorCombine::scalarizeLoadExtract(Instruction &I) {
     ScalarizedCost += TTI.getAddressComputationCost(VecTy->getElementType());
   }
 
+  LLVM_DEBUG(dbgs() << "Found all extractions of a vector load: " << I
+                    << "\n  LoadExtractCost: " << OriginalCost
+                    << " vs ScalarizedCost: " << ScalarizedCost << "\n");
+
   if (ScalarizedCost >= OriginalCost)
     return false;