Index: llvm/test/Transforms/InstCombine/addsub-constant-folding.ll
===================================================================
--- llvm/test/Transforms/InstCombine/addsub-constant-folding.ll
+++ llvm/test/Transforms/InstCombine/addsub-constant-folding.ll
@@ -132,6 +132,113 @@
   ret i32 %t1
 }
 
+define i8 @add_nsw_const_const_sub_nsw(i8 %arg) {
+; CHECK-LABEL: @add_nsw_const_const_sub_nsw(
+; CHECK-NEXT:    [[T1:%.*]] = sub i8 -128, [[ARG:%.*]]
+; CHECK-NEXT:    ret i8 [[T1]]
+;
+  %t0 = add nsw i8 %arg, 1
+  %t1 = sub nsw i8 -127, %t0
+  ret i8 %t1
+}
+
+define i8 @add_nsw_const_const_sub(i8 %arg) {
+; CHECK-LABEL: @add_nsw_const_const_sub(
+; CHECK-NEXT:    [[T1:%.*]] = sub i8 -128, [[ARG:%.*]]
+; CHECK-NEXT:    ret i8 [[T1]]
+;
+  %t0 = add nsw i8 %arg, 1
+  %t1 = sub i8 -127, %t0
+  ret i8 %t1
+}
+
+define i8 @add_const_const_sub_nsw(i8 %arg) {
+; CHECK-LABEL: @add_const_const_sub_nsw(
+; CHECK-NEXT:    [[T1:%.*]] = sub i8 -128, [[ARG:%.*]]
+; CHECK-NEXT:    ret i8 [[T1]]
+;
+  %t0 = add i8 %arg, 1
+  %t1 = sub nsw i8 -127, %t0
+  ret i8 %t1
+}
+
+; 127-X with nsw will be more poisonous than -127-(X+2) with nsw. (see X = -1)
+define i8 @add_nsw_const_const_sub_nsw_ov(i8 %arg) {
+; CHECK-LABEL: @add_nsw_const_const_sub_nsw_ov(
+; CHECK-NEXT:    [[T1:%.*]] = sub i8 127, [[ARG:%.*]]
+; CHECK-NEXT:    ret i8 [[T1]]
+;
+  %t0 = add nsw i8 %arg, 2
+  %t1 = sub nsw i8 -127, %t0
+  ret i8 %t1
+}
+
+define i8 @add_nuw_const_const_sub_nuw(i8 %arg) {
+; CHECK-LABEL: @add_nuw_const_const_sub_nuw(
+; CHECK-NEXT:    [[T1:%.*]] = sub i8 -128, [[ARG:%.*]]
+; CHECK-NEXT:    ret i8 [[T1]]
+;
+  %t0 = add nuw i8 %arg, 1
+  %t1 = sub nuw i8 -127, %t0
+  ret i8 %t1
+}
+
+define i8 @add_const_const_sub_nuw(i8 %arg) {
+; CHECK-LABEL: @add_const_const_sub_nuw(
+; CHECK-NEXT:    [[T1:%.*]] = sub i8 -128, [[ARG:%.*]]
+; CHECK-NEXT:    ret i8 [[T1]]
+;
+  %t0 = add i8 %arg, 1
+  %t1 = sub nuw i8 -127, %t0
+  ret i8 %t1
+}
+
+
+define <2 x i8> @non_splat_vec_add_nsw_const_const_sub_nsw_not_ov1(<2 x i8> %arg) {
+; CHECK-LABEL: @non_splat_vec_add_nsw_const_const_sub_nsw_not_ov1(
+; CHECK-NEXT:    [[T1:%.*]] = sub <2 x i8> <i8 -2, i8 -126>, [[ARG:%.*]]
+; CHECK-NEXT:    ret <2 x i8> [[T1]]
+;
+  %t0 = add nsw <2 x i8> %arg, <i8 1, i8 0>
+  %t1 = sub nsw <2 x i8> <i8 -1, i8 -126>, %t0
+  ret <2 x i8> %t1
+}
+
+
+; TODO: We can add nsw on sub, curret Value Tracking use [max element,min element] constant range, to check overflow for vector?
+define <2 x i8> @non_splat_vec_add_nsw_const_const_sub_nsw_not_ov2(<2 x i8> %arg) {
+; CHECK-LABEL: @non_splat_vec_add_nsw_const_const_sub_nsw_not_ov2(
+; CHECK-NEXT:    [[T1:%.*]] = sub <2 x i8> <i8 -126, i8 -128>, [[ARG:%.*]]
+; CHECK-NEXT:    ret <2 x i8> [[T1]]
+;
+  %t0 = add nsw <2 x i8> %arg, <i8 1, i8 2>
+  %t1 = sub nsw <2 x i8> <i8 -125, i8 -126>, %t0
+  ret <2 x i8> %t1
+}
+
+; TODO: We can add nsw on sub, curret Value Tracking can't decide this is not overflowed?
+define <2 x i8> @non_splat_vec_add_nsw_const_const_sub_nsw_not_ov3(<2 x i8> %arg) {
+; CHECK-LABEL: @non_splat_vec_add_nsw_const_const_sub_nsw_not_ov3(
+; CHECK-NEXT:    [[T1:%.*]] = sub <2 x i8> <i8 -120, i8 -127>, [[ARG:%.*]]
+; CHECK-NEXT:    ret <2 x i8> [[T1]]
+;
+  %t0 = add nsw <2 x i8> %arg, <i8 0, i8 1>
+  %t1 = sub nsw <2 x i8> <i8 -120, i8 -126>, %t0
+  ret <2 x i8> %t1
+}
+
+; 127-X with nsw will be more poisonous than -127-(X+2) with nsw. (see X = -1)
+define <2 x i8> @non_splat_vec_add_nsw_const_const_sub_nsw_ov(<2 x i8> %arg) {
+; CHECK-LABEL: @non_splat_vec_add_nsw_const_const_sub_nsw_ov(
+; CHECK-NEXT:    [[T1:%.*]] = sub <2 x i8> <i8 -127, i8 127>, [[ARG:%.*]]
+; CHECK-NEXT:    ret <2 x i8> [[T1]]
+;
+  %t0 = add nsw <2 x i8> %arg, <i8 1, i8 2>
+  %t1 = sub nsw <2 x i8> <i8 -126, i8 -127>, %t0
+  ret <2 x i8> %t1
+}
+
+
 define i32 @add_const_const_sub_extrause(i32 %arg) {
 ; CHECK-LABEL: @add_const_const_sub_extrause(
 ; CHECK-NEXT:    [[T0:%.*]] = add i32 [[ARG:%.*]], 8