Addressed comments

Author: npanchen

llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp

@@ -2632,13 +2632,16 @@ Instruction *InstCombinerImpl::visitSub(BinaryOperator &I) {
       return replaceInstUsesWith(I, Res);
 
   if (match(Op0, m_ZExt(m_PtrToInt(m_Value(LHSOp)))) &&
-      match(Op1, m_PtrToInt(m_Value(RHSOp))) && isa<GlobalValue>(RHSOp)) {
-    Value *Offset;
-    if (match(LHSOp, m_GEP(m_Specific(RHSOp), m_Value(Offset)))) {
-      auto *GEP = cast<GEPOperator>(LHSOp);
-      if (GEP->isInBounds()) {
-        Value *Res = Builder.CreateZExt(EmitGEPOffset(GEP), I.getType());
-        return replaceInstUsesWith(I, Res);
+      match(Op1, m_ZExtOrSelf(m_PtrToInt(m_Value(RHSOp))))) {
+    if (auto *GEP = dyn_cast<GEPOperator>(LHSOp)) {
+      if (GEP->getPointerOperand() == RHSOp) {
+        if (GEP->hasNoUnsignedWrap() || GEP->hasNoUnsignedSignedWrap()) {
+          Value *Offset = EmitGEPOffset(GEP);
+          Value *Res = GEP->hasNoUnsignedWrap()
+                           ? Builder.CreateZExt(Offset, I.getType())
+                           : Builder.CreateSExt(Offset, I.getType());
+          return replaceInstUsesWith(I, Res);
+        }
       }
     }
   }

llvm/test/Transforms/InstCombine/sub-gep.ll

@@ -316,19 +316,57 @@ define i16 @test25_as1(ptr addrspace(1) %P, i64 %A) {
 }
 
 @Arr_as2 = external addrspace(2) global [42 x i16]
-define i64 @zext_ptrtoint_sub_ptrtoint_as2(ptr addrspace(1) %p, i32 %offset) {
+define i64 @zext_ptrtoint_sub_ptrtoint_as2(i32 %offset) {
 ; CHECK-LABEL: @zext_ptrtoint_sub_ptrtoint_as2(
 ; CHECK-NEXT:  %A.idx = shl nsw i32 %offset, 1
+; CHECK-NEXT:  %D = sext i32 %A.idx to i64
+; CHECK-NEXT:  ret i64 %D
+  %A = getelementptr nusw bfloat, ptr addrspace(2) @Arr_as2, i32 %offset
+  %B = ptrtoint ptr addrspace(2) %A to i32
+  %C = zext i32 %B to i64
+  %D = sub i64 %C, ptrtoint (ptr addrspace(2) @Arr_as2 to i64)
+  ret i64 %D
+}
+
+define i64 @zext_ptrtoint_sub_ptrtoint_as2_nuw(i32 %offset) {
+; CHECK-LABEL: @zext_ptrtoint_sub_ptrtoint_as2_nuw(
+; CHECK-NEXT:  %A.idx = shl nuw i32 %offset, 1
 ; CHECK-NEXT:  %D = zext i32 %A.idx to i64
 ; CHECK-NEXT:  ret i64 %D
-  %A = getelementptr inbounds bfloat, ptr addrspace(2) @Arr_as2, i32 %offset
+  %A = getelementptr nuw bfloat, ptr addrspace(2) @Arr_as2, i32 %offset
   %B = ptrtoint ptr addrspace(2) %A to i32
   %C = zext i32 %B to i64
   %D = sub i64 %C, ptrtoint (ptr addrspace(2) @Arr_as2 to i64)
   ret i64 %D
 }
 
-define i64 @ptrtoint_sub_zext_ptrtoint_as2(ptr addrspace(2) %p, i32 %offset) {
+define i64 @zext_ptrtoint_sub_zext_ptrtoint_as2(i32 %offset) {
+; CHECK-LABEL: @zext_ptrtoint_sub_zext_ptrtoint_as2(
+; CHECK-NEXT:  %A.idx = shl nsw i32 %offset, 1
+; CHECK-NEXT:  %E = sext i32 %A.idx to i64
+; CHECK-NEXT:  ret i64 %E
+  %A = getelementptr nusw bfloat, ptr addrspace(2) @Arr_as2, i32 %offset
+  %B = ptrtoint ptr addrspace(2) %A to i32
+  %C = zext i32 %B to i64
+  %D = zext i32 ptrtoint (ptr addrspace(2) @Arr_as2 to i32) to i64
+  %E = sub i64 %C, %D
+  ret i64 %E
+}
+
+define i64 @zext_ptrtoint_sub_zext_ptrtoint_as2_nuw(i32 %offset) {
+; CHECK-LABEL: @zext_ptrtoint_sub_zext_ptrtoint_as2_nuw(
+; CHECK-NEXT:  %A.idx = shl nuw i32 %offset, 1
+; CHECK-NEXT:  %E = zext i32 %A.idx to i64
+; CHECK-NEXT:  ret i64 %E
+  %A = getelementptr nuw bfloat, ptr addrspace(2) @Arr_as2, i32 %offset
+  %B = ptrtoint ptr addrspace(2) %A to i32
+  %C = zext i32 %B to i64
+  %D = zext i32 ptrtoint (ptr addrspace(2) @Arr_as2 to i32) to i64
+  %E = sub i64 %C, %D
+  ret i64 %E
+}
+
+define i64 @ptrtoint_sub_zext_ptrtoint_as2(i32 %offset) {
 ; CHECK-LABEL: @ptrtoint_sub_zext_ptrtoint_as2(
 ; CHECK-NEXT:  %A = getelementptr inbounds bfloat, ptr addrspace(2) @Arr_as2, i32 %offset
 ; CHECK-NEXT:  %B = ptrtoint ptr addrspace(2) %A to i32