1; RUN: opt < %s -instcombine -S | FileCheck %s
2
3target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
4
5; CHECK-LABEL: @oppositesign
6; CHECK: add nsw i16 %a, %b
7define i16 @oppositesign(i16 %x, i16 %y) {
8; %a is negative, %b is positive
9  %a = or i16 %x, 32768
10  %b = and i16 %y, 32767
11  %c = add i16 %a, %b
12  ret i16 %c
13}
14
15define i16 @zero_sign_bit(i16 %a) {
16; CHECK-LABEL: @zero_sign_bit(
17; CHECK-NEXT: and
18; CHECK-NEXT: add nuw
19; CHECK-NEXT: ret
20  %1 = and i16 %a, 32767
21  %2 = add i16 %1, 512
22  ret i16 %2
23}
24
25define i16 @zero_sign_bit2(i16 %a, i16 %b) {
26; CHECK-LABEL: @zero_sign_bit2(
27; CHECK-NEXT: and
28; CHECK-NEXT: and
29; CHECK-NEXT: add nuw
30; CHECK-NEXT: ret
31  %1 = and i16 %a, 32767
32  %2 = and i16 %b, 32767
33  %3 = add i16 %1, %2
34  ret i16 %3
35}
36
37declare i16 @bounded(i16 %input);
38declare i32 @__gxx_personality_v0(...);
39!0 = !{i16 0, i16 32768} ; [0, 32767]
40!1 = !{i16 0, i16 32769} ; [0, 32768]
41
42define i16 @add_bounded_values(i16 %a, i16 %b) personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
43; CHECK-LABEL: @add_bounded_values(
44entry:
45  %c = call i16 @bounded(i16 %a), !range !0
46  %d = invoke i16 @bounded(i16 %b) to label %cont unwind label %lpad, !range !0
47cont:
48; %c and %d are in [0, 32767]. Therefore, %c + %d doesn't unsigned overflow.
49  %e = add i16 %c, %d
50; CHECK: add nuw i16 %c, %d
51  ret i16 %e
52lpad:
53  %0 = landingpad { i8*, i32 }
54          filter [0 x i8*] zeroinitializer
55  ret i16 42
56}
57
58define i16 @add_bounded_values_2(i16 %a, i16 %b) personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
59; CHECK-LABEL: @add_bounded_values_2(
60entry:
61  %c = call i16 @bounded(i16 %a), !range !1
62  %d = invoke i16 @bounded(i16 %b) to label %cont unwind label %lpad, !range !1
63cont:
64; Similar to add_bounded_values, but %c and %d are in [0, 32768]. Therefore,
65; %c + %d may unsigned overflow and we cannot add NUW.
66  %e = add i16 %c, %d
67; CHECK: add i16 %c, %d
68  ret i16 %e
69lpad:
70  %0 = landingpad { i8*, i32 }
71          filter [0 x i8*] zeroinitializer
72  ret i16 42
73}
74
75; CHECK-LABEL: @ripple_nsw1
76; CHECK: add nsw i16 %a, %b
77define i16 @ripple_nsw1(i16 %x, i16 %y) {
78; %a has at most one bit set
79  %a = and i16 %y, 1
80
81; %b has a 0 bit other than the sign bit
82  %b = and i16 %x, 49151
83
84  %c = add i16 %a, %b
85  ret i16 %c
86}
87
88; Like the previous test, but flip %a and %b
89; CHECK-LABEL: @ripple_nsw2
90; CHECK: add nsw i16 %b, %a
91define i16 @ripple_nsw2(i16 %x, i16 %y) {
92  %a = and i16 %y, 1
93  %b = and i16 %x, 49151
94  %c = add i16 %b, %a
95  ret i16 %c
96}
97
98; CHECK-LABEL: @ripple_no_nsw1
99; CHECK: add i32 %a, %x
100define i32 @ripple_no_nsw1(i32 %x, i32 %y) {
101; We know nothing about %x
102  %a = and i32 %y, 1
103  %b = add i32 %a, %x
104  ret i32 %b
105}
106
107; CHECK-LABEL: @ripple_no_nsw2
108; CHECK: add nuw i16 %a, %b
109define i16 @ripple_no_nsw2(i16 %x, i16 %y) {
110; %a has at most one bit set
111  %a = and i16 %y, 1
112
113; %b has a 0 bit, but it is the sign bit
114  %b = and i16 %x, 32767
115
116  %c = add i16 %a, %b
117  ret i16 %c
118}
119