[llvm] [InstCombine] recognize missed i128 split optimization (PR #129363)

[Simon Pilgrim via llvm-commits]

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@@ -3119,6 +3119,15 @@ static Value *matchOrConcat(Instruction &Or, InstCombiner::BuilderTy &Builder) {
       match(UpperSrc, m_BitReverse(m_Value(UpperBRev))))
     return ConcatIntrinsicCalls(Intrinsic::bitreverse, UpperBRev, LowerBRev);
 
+  Value *X;
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RKSimon wrote:

@bassiounix You just need to add a comment describing the pattern.

https://github.com/llvm/llvm-project/pull/129363