[llvm] InstSimplify: lookthru casts, binops in folding shuffles (PR #92668)

[Matt Arsenault via llvm-commits]

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@@ -5468,16 +5517,26 @@ static Value *simplifyShuffleVectorInst(Value *Op0, Value *Op1,
   // shuffle. This handles simple identity shuffles as well as chains of
   // shuffles that may widen/narrow and/or move elements across lanes and back.
   Value *RootVec = nullptr;
-  for (unsigned i = 0; i != MaskNumElts; ++i) {
+  ReplacementTy ReplaceInRootVec;
+  for (unsigned Idx = 0; Idx != MaskNumElts; ++Idx) {
     // Note that recursion is limited for each vector element, so if any element
     // exceeds the limit, this will fail to simplify.
-    RootVec =
-        foldIdentityShuffles(i, Op0, Op1, Indices[i], RootVec, MaxRecurse);
+    std::pair<Value *, ReplacementTy> Res =
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arsenm wrote:

C++17 structured binding 

https://github.com/llvm/llvm-project/pull/92668