[llvm] [MemCpyOpt] Always create gep instructions in `processMemCpyMemCpyDependence` (PR #98686)

[Nikita Popov via llvm-commits]

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@@ -1188,8 +1188,9 @@ bool MemCpyOptPass::processMemCpyMemCpyDependence(MemCpyInst *M,
     if (MDestOffset == MForwardOffset)
       CopySource = M->getDest();
     else {
-      NewCopySource = cast<Instruction>(Builder.CreateInBoundsPtrAdd(
-          CopySource, Builder.getInt64(MForwardOffset)));
+      NewCopySource = GetElementPtrInst::CreateInBounds(
+          Builder.getInt8Ty(), CopySource, Builder.getInt64(MForwardOffset), "",
+          Builder.GetInsertPoint());
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nikic wrote:

This is going to miss the debug location. I'd prefer to keep IRBuilder and use a dyn_cast. If it's a constant, then there is no need to clean up.

https://github.com/llvm/llvm-project/pull/98686