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