[llvm] [MergeFunc] Fix crash caused by bitcasting ArrayType (PR #133259)

[Florian Hahn via llvm-commits]

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@@ -76,6 +76,41 @@ void IRBuilderBase::SetInstDebugLocation(Instruction *I) const {
     }
 }
 
+Value *IRBuilderBase::CreateAggregateCast(Value *V, Type *DestTy) {
+  Type *SrcTy = V->getType();
+  if (SrcTy == DestTy)
+    return V;
+  if (auto *SrcST = dyn_cast<StructType>(SrcTy)) {
+    assert(DestTy->isStructTy() && "Expected StructType");
+    auto *DestST = cast<StructType>(DestTy);
+    assert(SrcST->getNumElements() == DestST->getNumElements());
+    Value *Result = PoisonValue::get(DestTy);
+    for (unsigned int I = 0, E = SrcST->getNumElements(); I < E; ++I) {
+      Value *Element = CreateAggregateCast(CreateExtractValue(V, ArrayRef(I)),
+                                           DestST->getElementType(I));
+
+      Result = CreateInsertValue(Result, Element, ArrayRef(I));
+    }
+    return Result;
+  }
+  if (auto *SrcAT = dyn_cast<ArrayType>(SrcTy)) {
+    assert(DestTy->isArrayTy() && "Expected ArrayType");
+    auto *DestAT = cast<ArrayType>(DestTy);
+    assert(SrcAT->getNumElements() == DestAT->getNumElements());
+    Value *Result = PoisonValue::get(DestTy);
+    for (unsigned int I = 0, E = SrcAT->getNumElements(); I < E; ++I) {
+      Value *Element = CreateAggregateCast(CreateExtractValue(V, ArrayRef(I)),
+                                           DestAT->getElementType());
+
+      Result = CreateInsertValue(Result, Element, ArrayRef(I));
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fhahn wrote:

Is this effectively the same as for the structure case, except for the `cast`/`assert` for the types? If so, would be good if we could unify the code.

https://github.com/llvm/llvm-project/pull/133259