[llvm] [DirectX] Fix the writing of ConstantExpr GEPs to DXIL bitcode (PR #154446)

[Farzon Lotfi via llvm-commits]

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@@ -343,9 +343,7 @@ bool DataScalarizerVisitor::visitGetElementPtrInst(GetElementPtrInst &GEPI) {
 
   GOp->replaceAllUsesWith(NewGEP);
 
-  if (auto *CE = dyn_cast<ConstantExpr>(GOp))
-    CE->destroyConstant();
-  else if (auto *OldGEPI = dyn_cast<GetElementPtrInst>(GOp))
+  if (auto *OldGEPI = dyn_cast<GetElementPtrInst>(GOp))
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farzonl wrote:

A little confused what is going on here. In the diff it looks like we always did `OldGEPI->eraseFromParent();` was this previously defined somewhere above? Is the diff off? Why do we have to `dyn_cast` `GOp`? Shouldn't that already be a GEP?

https://github.com/llvm/llvm-project/pull/154446