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
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
|
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -instsimplify -S | FileCheck %s
; %r = shl nuw i8 C, %x
; As per langref: If the nuw keyword is present, then the shift produces
; a poison value if it shifts out any non-zero bits.
; Thus, if the sign bit is set on C, then %x can only be 0, which means that
; %r can only be C.
define i8 @shl_nuw (i8 %x) {
; CHECK-LABEL: @shl_nuw(
; CHECK-NEXT: ret i8 -1
;
%ret = shl nuw i8 -1, %x
; nuw here means that %x can only be 0
ret i8 %ret
}
define i8 @shl_nuw_nsw (i8 %x) {
; CHECK-LABEL: @shl_nuw_nsw(
; CHECK-NEXT: ret i8 -1
;
%ret = shl nuw nsw i8 -1, %x
; nuw here means that %x can only be 0
ret i8 %ret
}
define i8 @shl_128 (i8 %x) {
; CHECK-LABEL: @shl_128(
; CHECK-NEXT: ret i8 -128
;
%ret = shl nuw i8 128, %x
; 128 == 1<<7 == just the sign bit is set
ret i8 %ret
}
; ============================================================================ ;
; Positive tests with value range known
; ============================================================================ ;
declare void @llvm.assume(i1 %cond);
define i8 @knownbits_negative(i8 %x, i8 %y) {
; CHECK-LABEL: @knownbits_negative(
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i8 [[X:%.*]], 0
; CHECK-NEXT: tail call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: [[RET:%.*]] = shl nuw i8 [[X]], [[Y:%.*]]
; CHECK-NEXT: ret i8 [[RET]]
;
%cmp = icmp slt i8 %x, 0
tail call void @llvm.assume(i1 %cmp)
%ret = shl nuw i8 %x, %y
ret i8 %ret
}
define i8 @knownbits_negativeorzero(i8 %x, i8 %y) {
; CHECK-LABEL: @knownbits_negativeorzero(
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i8 [[X:%.*]], 1
; CHECK-NEXT: tail call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: [[RET:%.*]] = shl nuw i8 [[X]], [[Y:%.*]]
; CHECK-NEXT: ret i8 [[RET]]
;
%cmp = icmp slt i8 %x, 1
tail call void @llvm.assume(i1 %cmp)
%ret = shl nuw i8 %x, %y
ret i8 %ret
}
; ============================================================================ ;
; Vectors
; ============================================================================ ;
define <2 x i8> @shl_vec(<2 x i8> %x) {
; CHECK-LABEL: @shl_vec(
; CHECK-NEXT: ret <2 x i8> <i8 -1, i8 -1>
;
%ret = shl nuw <2 x i8> <i8 -1, i8 -1>, %x
ret <2 x i8> %ret
}
define <3 x i8> @shl_vec_undef(<3 x i8> %x) {
; CHECK-LABEL: @shl_vec_undef(
; CHECK-NEXT: ret <3 x i8> <i8 -1, i8 undef, i8 -1>
;
%ret = shl nuw <3 x i8> <i8 -1, i8 undef, i8 -1>, %x
ret <3 x i8> %ret
}
define <2 x i8> @shl_vec_nonsplat(<2 x i8> %x) {
; CHECK-LABEL: @shl_vec_nonsplat(
; CHECK-NEXT: ret <2 x i8> <i8 -1, i8 -2>
;
%ret = shl nuw <2 x i8> <i8 -1, i8 -2>, %x
ret <2 x i8> %ret
}
; ============================================================================ ;
; Negative tests. Should not be folded.
; ============================================================================ ;
define i8 @shl_127 (i8 %x) {
; CHECK-LABEL: @shl_127(
; CHECK-NEXT: [[RET:%.*]] = shl nuw i8 127, [[X:%.*]]
; CHECK-NEXT: ret i8 [[RET]]
;
%ret = shl nuw i8 127, %x
; 127 == (1<<7)-1 == all bits except the sign bit are set.
ret i8 %ret
}
define i8 @bad_shl (i8 %x) {
; CHECK-LABEL: @bad_shl(
; CHECK-NEXT: [[RET:%.*]] = shl i8 -1, [[X:%.*]]
; CHECK-NEXT: ret i8 [[RET]]
;
%ret = shl i8 -1, %x ; need nuw
ret i8 %ret
}
define i8 @bad_nsw (i8 %x) {
; CHECK-LABEL: @bad_nsw(
; CHECK-NEXT: [[RET:%.*]] = shl nsw i8 -1, [[X:%.*]]
; CHECK-NEXT: ret i8 [[RET]]
;
%ret = shl nsw i8 -1, %x ; need nuw
ret i8 %ret
}
; First `shl` operand is not `-1` constant
define i8 @bad_shl0(i8 %shlop1, i8 %x) {
; CHECK-LABEL: @bad_shl0(
; CHECK-NEXT: [[RET:%.*]] = shl nuw i8 [[SHLOP1:%.*]], [[X:%.*]]
; CHECK-NEXT: ret i8 [[RET]]
;
%ret = shl nuw i8 %shlop1, %x
ret i8 %ret
}
; Bad shl nuw constant
define i8 @bad_shl1(i8 %x) {
; CHECK-LABEL: @bad_shl1(
; CHECK-NEXT: [[RET:%.*]] = shl nuw i8 1, [[X:%.*]]
; CHECK-NEXT: ret i8 [[RET]]
;
%ret = shl nuw i8 1, %x ; not -1
ret i8 %ret
}
define <2 x i8> @bad_shl_vec_nonsplat(<2 x i8> %x) {
; CHECK-LABEL: @bad_shl_vec_nonsplat(
; CHECK-NEXT: [[RET:%.*]] = shl nuw <2 x i8> <i8 -1, i8 1>, [[X:%.*]]
; CHECK-NEXT: ret <2 x i8> [[RET]]
;
%ret = shl nuw <2 x i8> <i8 -1, i8 1>, %x
ret <2 x i8> %ret
}
; Bad known bits
define i8 @bad_knownbits(i8 %x, i8 %y) {
; CHECK-LABEL: @bad_knownbits(
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i8 [[X:%.*]], 2
; CHECK-NEXT: tail call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: [[RET:%.*]] = shl nuw i8 [[X]], [[Y:%.*]]
; CHECK-NEXT: ret i8 [[RET]]
;
%cmp = icmp slt i8 %x, 2
tail call void @llvm.assume(i1 %cmp)
%ret = shl nuw i8 %x, %y
ret i8 %ret
}
define i8 @bad_knownbits_minusoneormore(i8 %x, i8 %y) {
; CHECK-LABEL: @bad_knownbits_minusoneormore(
; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i8 [[X:%.*]], -2
; CHECK-NEXT: tail call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: [[RET:%.*]] = shl nuw i8 [[X]], [[Y:%.*]]
; CHECK-NEXT: ret i8 [[RET]]
;
%cmp = icmp sgt i8 %x, -2
tail call void @llvm.assume(i1 %cmp)
%ret = shl nuw i8 %x, %y
ret i8 %ret
}
define i8 @bad_knownbits_zeroorpositive(i8 %x, i8 %y) {
; CHECK-LABEL: @bad_knownbits_zeroorpositive(
; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i8 [[X:%.*]], -1
; CHECK-NEXT: tail call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: [[RET:%.*]] = shl nuw i8 [[X]], [[Y:%.*]]
; CHECK-NEXT: ret i8 [[RET]]
;
%cmp = icmp sgt i8 %x, -1
tail call void @llvm.assume(i1 %cmp)
%ret = shl nuw i8 %x, %y
ret i8 %ret
}
define i8 @bad_knownbits_positive(i8 %x, i8 %y) {
; CHECK-LABEL: @bad_knownbits_positive(
; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i8 [[X:%.*]], 0
; CHECK-NEXT: tail call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: [[RET:%.*]] = shl nuw i8 [[X]], [[Y:%.*]]
; CHECK-NEXT: ret i8 [[RET]]
;
%cmp = icmp sgt i8 %x, 0
tail call void @llvm.assume(i1 %cmp)
%ret = shl nuw i8 %x, %y
ret i8 %ret
}
|
