[llvm] [DirectX] Bug fix for Data Scalarization crash (PR #118426)

[Justin Bogner via llvm-commits]

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@@ -106,6 +90,21 @@ bool DataScalarizerVisitor::visitLoadInst(LoadInst &LI) {
   unsigned NumOperands = LI.getNumOperands();
   for (unsigned I = 0; I < NumOperands; ++I) {
     Value *CurrOpperand = LI.getOperand(I);
+    ConstantExpr *CE = dyn_cast<ConstantExpr>(CurrOpperand);
+    if (CE && CE->getOpcode() == Instruction::GetElementPtr) {
+      GetElementPtrInst *OldGEP =
+          cast<GetElementPtrInst>(CE->getAsInstruction());
+      OldGEP->insertBefore(&LI);
+      Value *NewGEP = createNewGetElementPtr(*OldGEP);
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bogner wrote:

I think I prefer the version where this calls `visitGetElementPtrInstruction` rather than calling `createNewGetElementPtr`, for consistency with the other, similar pass. If you'd like to keep this one as is though, we should at least add an `assert(NewGEP)` here to make it clear that the failure path in `createNewGetElementPtr` isn't expected in these cases.

https://github.com/llvm/llvm-project/pull/118426