[SeparateConstOffsetFromGEP] Add additional inbounds preservation tests (NFC)

Adding these for NVPTX because for AMDGPU the problematic -1 case
does not get reordered in the first place.

Author: nikic

llvm/test/Transforms/SeparateConstOffsetFromGEP/NVPTX/lower-gep-reorder.ll

@@ -63,3 +63,44 @@ end:
   call void asm sideeffect "; use $0", "v"(ptr  %idx3)
   ret void
 }
+
+define void @inboundsPossiblyNegative1(ptr %in.ptr, i64 %in.idx1) {
+; CHECK-LABEL: define void @inboundsPossiblyNegative1(
+; CHECK-SAME: ptr [[IN_PTR:%.*]], i64 [[IN_IDX1:%.*]]) {
+; CHECK-NEXT:    [[TMP0:%.*]] = getelementptr <2 x i8>, ptr [[IN_PTR]], i64 [[IN_IDX1]]
+; CHECK-NEXT:    [[TMP1:%.*]] = getelementptr <2 x i8>, ptr [[TMP0]], i64 1
+; CHECK-NEXT:    ret void
+;
+  %const1 = getelementptr inbounds <2 x i8>, ptr %in.ptr, i64 1
+  %idx1 = getelementptr inbounds <2 x i8>, ptr %const1, i64 %in.idx1
+  ret void
+}
+
+define void @inboundsPossiblyNegative2(ptr %in.ptr, i64 %in.idx1) {
+; CHECK-LABEL: define void @inboundsPossiblyNegative2(
+; CHECK-SAME: ptr [[IN_PTR:%.*]], i64 [[IN_IDX1:%.*]]) {
+; CHECK-NEXT:    [[IN_IDX1_NNEG:%.*]] = and i64 [[IN_IDX1]], 9223372036854775807
+; CHECK-NEXT:    [[TMP0:%.*]] = getelementptr inbounds <2 x i8>, ptr [[IN_PTR]], i64 [[IN_IDX1_NNEG]]
+; CHECK-NEXT:    [[TMP1:%.*]] = getelementptr inbounds <2 x i8>, ptr [[TMP0]], i64 -1
+; CHECK-NEXT:    ret void
+;
+  %in.idx1.nneg = and i64 %in.idx1, 9223372036854775807
+  %const1 = getelementptr inbounds <2 x i8>, ptr %in.ptr, i64 -1
+  %idx1 = getelementptr inbounds <2 x i8>, ptr %const1, i64 %in.idx1.nneg
+  ret void
+}
+
+define void @inboundsNonNegative(ptr %in.ptr, i64 %in.idx1) {
+; CHECK-LABEL: define void @inboundsNonNegative(
+; CHECK-SAME: ptr [[IN_PTR:%.*]], i64 [[IN_IDX1:%.*]]) {
+; CHECK-NEXT:    [[IDXPROM:%.*]] = and i64 [[IN_IDX1]], 9223372036854775807
+; CHECK-NEXT:    [[TMP0:%.*]] = getelementptr inbounds <2 x i8>, ptr [[IN_PTR]], i64 [[IDXPROM]]
+; CHECK-NEXT:    [[TMP1:%.*]] = getelementptr inbounds <2 x i8>, ptr [[TMP0]], i64 1
+; CHECK-NEXT:    ret void
+;
+  %in.idx1.nneg = and i64 %in.idx1, 9223372036854775807
+  %const1 = getelementptr inbounds <2 x i8>, ptr %in.ptr, i64 1
+  %idx1 = getelementptr inbounds <2 x i8>, ptr %const1, i64 %in.idx1.nneg
+  ret void
+}
+