[llvm] [InstCombine] Fold pointer adding in integer to arithmetic add (PR #91596)

[Yingwei Zheng via llvm-commits]

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@@ -2073,6 +2073,16 @@ Instruction *InstCombinerImpl::visitPtrToInt(PtrToIntInst &CI) {
     return InsertElementInst::Create(Vec, NewCast, Index);
   }
 
+  // (ptrtoint (gep (inttoptr Base), Offset)) -> Base + Offset
+  Value *Base, *Offset;
+  if (match(SrcOp, m_OneUse(m_PtrAdd(m_OneUse(m_IntToPtr(m_Value(Base))),
+                                     m_Value(Offset)))) &&
+      Base->getType() == Ty && Offset->getType() == Ty) {
+    auto *NewOp = BinaryOperator::CreateAdd(Base, Offset);
+    NewOp->setHasNoUnsignedWrap(true);
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dtcxzyw wrote:

You can treat `inbounds` as `nsw + nuw`. See also https://discourse.llvm.org/t/rfc-add-nusw-and-nuw-flags-for-getelementptr/78672.

https://github.com/llvm/llvm-project/pull/91596