address comments

Author: AlexMaclean

llvm/test/Transforms/SROA/select-gep.ll

@@ -219,6 +219,29 @@ define i64 @test_select_like_zext_idx_mem2reg(i1 %c) {
   ret i64 %res
 }
 
+; Test gep with a zext index that is not equivalent to a select. No unfolding
+; or promotion should take place.
+define i64 @test_zext_unlike_select_idx_mem2reg(i8 %c) {
+; CHECK-LABEL: @test_zext_unlike_select_idx_mem2reg(
+; CHECK-NEXT:    [[ALLOCA:%.*]] = alloca [2 x i64], align 8
+; CHECK-NEXT:    store i64 1, ptr [[ALLOCA]], align 4
+; CHECK-NEXT:    [[GEP1:%.*]] = getelementptr inbounds i64, ptr [[ALLOCA]], i64 1
+; CHECK-NEXT:    store i64 2, ptr [[GEP1]], align 4
+; CHECK-NEXT:    [[IDX:%.*]] = zext i8 [[C:%.*]] to i64
+; CHECK-NEXT:    [[GEP2:%.*]] = getelementptr inbounds i64, ptr [[ALLOCA]], i64 [[IDX]]
+; CHECK-NEXT:    [[RES:%.*]] = load i64, ptr [[GEP2]], align 4
+; CHECK-NEXT:    ret i64 [[RES]]
+;
+  %alloca = alloca [2 x i64], align 8
+  store i64 1, ptr %alloca
+  %gep1 = getelementptr inbounds i64, ptr %alloca, i64 1
+  store i64 2, ptr %gep1
+  %idx = zext i8 %c to i64
+  %gep2 = getelementptr inbounds i64, ptr %alloca, i64 %idx
+  %res = load i64, ptr %gep2
+  ret i64 %res
+}
+
 ; Test gep of index select unfolding on an alloca that escaped, and as such
 ; is not splittable or promotable.
 ; FIXME: Ideally, no transform would take place in this case.