[llvm] cfd53ff - [InstCombine] Use MapVector for SourceAggregates. (#132564)

[via llvm-commits]

Author: Florian Hahn
Date: 2025-03-23T11:16:50Z
New Revision: cfd53ffb44f5d3c438c909b2bc9ae5604f452f39

URL: https://github.com/llvm/llvm-project/commit/cfd53ffb44f5d3c438c909b2bc9ae5604f452f39
DIFF: https://github.com/llvm/llvm-project/commit/cfd53ffb44f5d3c438c909b2bc9ae5604f452f39.diff

LOG: [InstCombine] Use MapVector for SourceAggregates. (#132564)

foldAggregateConstructionIntoAggregateReuse iterates over the entries of
SourceAggregates and the order of inserted instructions depends on the
order of the iterator. Using a regular DenseMap can lead to
non-deterministic value naming/numbering.

I don't think it can actually impact the generated binary, but it makes
diffing IR more difficult.

PR: https://github.com/llvm/llvm-project/pull/132564

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 6860a7cd07b78..f897cc7855d2d 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
@@ -1111,7 +1111,7 @@ Instruction *InstCombinerImpl::foldAggregateConstructionIntoAggregateReuse(
   // For each predecessor, what is the source aggregate,
   // from which all the elements were originally extracted from?
   // Note that we want for the map to have stable iteration order!
-  SmallDenseMap<BasicBlock *, Value *, 4> SourceAggregates;
+  SmallMapVector<BasicBlock *, Value *, 4> SourceAggregates;
   bool FoundSrcAgg = false;
   for (BasicBlock *Pred : Preds) {
     std::pair<decltype(SourceAggregates)::iterator, bool> IV =