[llvm] [LSV] Insert casts to vectorize mismatched types (PR #134436)

[Matt Arsenault via llvm-commits]

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@@ -1310,6 +1315,135 @@ std::optional<APInt> Vectorizer::getConstantOffsetSelects(
   return std::nullopt;
 }
 
+void Vectorizer::insertCastsToMergeClasses(EquivalenceClassMap &EQClasses) {
+  if (EQClasses.size() < 2)
+    return;
+
+  auto CopyMetaDataFromTo = [&](Instruction *Src, Instruction *Dst) {
+    SmallVector<std::pair<unsigned, MDNode *>, 4> MD;
+    Src->getAllMetadata(MD);
+    for (const auto [ID, Node] : MD) {
+      Dst->setMetadata(ID, Node);
+    }
+  };
+
+  // For each class, determine if all instructions are of type int, FP or ptr.
+  // This information will help us determine the type instructions should be
+  // casted into.
+  MapVector<EqClassKey, Bitset<3>> ClassAllTy;
+  for (const auto &C : EQClasses) {
+    auto CommonTypeKind = [](Instruction *I) {
+      if (I->getType()->isIntOrIntVectorTy())
+        return 0;
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arsenm wrote:

I'm not sure why integers with different bitwidths would get the same class 

https://github.com/llvm/llvm-project/pull/134436