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
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
|
; RUN: opt -S -loop-vectorize -force-vector-width=4 -force-vector-interleave=1 < %s 2>&1 | FileCheck %s
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
; Check that the vectorizer identifies the %p.09 phi,
; as an induction variable, despite the potential overflow
; due to the truncation from 32bit to 8bit.
; SCEV will detect the pattern "sext(trunc(%p.09)) + %step"
; and generate the required runtime checks under which
; we can assume no overflow. We check here that we generate
; exactly two runtime checks:
; 1) an overflow check:
; {0,+,(trunc i32 %step to i8)}<%for.body> Added Flags: <nssw>
; 2) an equality check verifying that the step of the induction
; is equal to sext(trunc(step)):
; Equal predicate: %step == (sext i8 (trunc i32 %step to i8) to i32)
;
; See also pr30654.
;
; int a[N];
; void doit1(int n, int step) {
; int i;
; char p = 0;
; for (i = 0; i < n; i++) {
; a[i] = p;
; p = p + step;
; }
; }
;
; CHECK-LABEL: @doit1
; CHECK: vector.scevcheck
; CHECK: %mul = call { i8, i1 } @llvm.umul.with.overflow.i8(i8 {{.*}}, i8 {{.*}})
; CHECK-NOT: %mul = call { i8, i1 } @llvm.umul.with.overflow.i8(i8 {{.*}}, i8 {{.*}})
; CHECK: %[[TEST:[0-9]+]] = or i1 {{.*}}, %mul.overflow
; CHECK: %[[NTEST:[0-9]+]] = or i1 false, %[[TEST]]
; CHECK: %ident.check = icmp ne i32 {{.*}}, %{{.*}}
; CHECK: %{{.*}} = or i1 %[[NTEST]], %ident.check
; CHECK-NOT: %mul = call { i8, i1 } @llvm.umul.with.overflow.i8(i8 {{.*}}, i8 {{.*}})
; CHECK: vector.body:
; CHECK: <4 x i32>
@a = common local_unnamed_addr global [250 x i32] zeroinitializer, align 16
; Function Attrs: norecurse nounwind uwtable
define void @doit1(i32 %n, i32 %step) local_unnamed_addr {
entry:
%cmp7 = icmp sgt i32 %n, 0
br i1 %cmp7, label %for.body.preheader, label %for.end
for.body.preheader:
%wide.trip.count = zext i32 %n to i64
br label %for.body
for.body:
%indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %for.body.preheader ]
%p.09 = phi i32 [ %add, %for.body ], [ 0, %for.body.preheader ]
%sext = shl i32 %p.09, 24
%conv = ashr exact i32 %sext, 24
%arrayidx = getelementptr inbounds [250 x i32], [250 x i32]* @a, i64 0, i64 %indvars.iv
store i32 %conv, i32* %arrayidx, align 4
%add = add nsw i32 %conv, %step
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%exitcond = icmp eq i64 %indvars.iv.next, %wide.trip.count
br i1 %exitcond, label %for.end.loopexit, label %for.body
for.end.loopexit:
br label %for.end
for.end:
ret void
}
; Same as above, but for checking the SCEV "zext(trunc(%p.09)) + %step".
; Here we expect the following two predicates to be added for runtime checking:
; 1) {0,+,(trunc i32 %step to i8)}<%for.body> Added Flags: <nusw>
; 2) Equal predicate: %step == (sext i8 (trunc i32 %step to i8) to i32)
;
; int a[N];
; void doit2(int n, int step) {
; int i;
; unsigned char p = 0;
; for (i = 0; i < n; i++) {
; a[i] = p;
; p = p + step;
; }
; }
;
; CHECK-LABEL: @doit2
; CHECK: vector.scevcheck
; CHECK: %mul = call { i8, i1 } @llvm.umul.with.overflow.i8(i8 {{.*}}, i8 {{.*}})
; CHECK-NOT: %mul = call { i8, i1 } @llvm.umul.with.overflow.i8(i8 {{.*}}, i8 {{.*}})
; CHECK: %[[TEST:[0-9]+]] = or i1 {{.*}}, %mul.overflow
; CHECK: %[[NTEST:[0-9]+]] = or i1 false, %[[TEST]]
; CHECK: %[[EXT:[0-9]+]] = sext i8 {{.*}} to i32
; CHECK: %ident.check = icmp ne i32 {{.*}}, %[[EXT]]
; CHECK: %{{.*}} = or i1 %[[NTEST]], %ident.check
; CHECK-NOT: %mul = call { i8, i1 } @llvm.umul.with.overflow.i8(i8 {{.*}}, i8 {{.*}})
; CHECK: vector.body:
; CHECK: <4 x i32>
; Function Attrs: norecurse nounwind uwtable
define void @doit2(i32 %n, i32 %step) local_unnamed_addr {
entry:
%cmp7 = icmp sgt i32 %n, 0
br i1 %cmp7, label %for.body.preheader, label %for.end
for.body.preheader:
%wide.trip.count = zext i32 %n to i64
br label %for.body
for.body:
%indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %for.body.preheader ]
%p.09 = phi i32 [ %add, %for.body ], [ 0, %for.body.preheader ]
%conv = and i32 %p.09, 255
%arrayidx = getelementptr inbounds [250 x i32], [250 x i32]* @a, i64 0, i64 %indvars.iv
store i32 %conv, i32* %arrayidx, align 4
%add = add nsw i32 %conv, %step
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%exitcond = icmp eq i64 %indvars.iv.next, %wide.trip.count
br i1 %exitcond, label %for.end.loopexit, label %for.body
for.end.loopexit:
br label %for.end
for.end:
ret void
}
; Here we check that the same phi scev analysis would fail
; to create the runtime checks because the step is not invariant.
; As a result vectorization will fail.
;
; int a[N];
; void doit3(int n, int step) {
; int i;
; char p = 0;
; for (i = 0; i < n; i++) {
; a[i] = p;
; p = p + step;
; step += 2;
; }
; }
;
; CHECK-LABEL: @doit3
; CHECK-NOT: vector.scevcheck
; CHECK-NOT: vector.body:
; CHECK-LABEL: for.body:
; Function Attrs: norecurse nounwind uwtable
define void @doit3(i32 %n, i32 %step) local_unnamed_addr {
entry:
%cmp9 = icmp sgt i32 %n, 0
br i1 %cmp9, label %for.body.preheader, label %for.end
for.body.preheader:
%wide.trip.count = zext i32 %n to i64
br label %for.body
for.body:
%indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %for.body.preheader ]
%p.012 = phi i32 [ %add, %for.body ], [ 0, %for.body.preheader ]
%step.addr.010 = phi i32 [ %add3, %for.body ], [ %step, %for.body.preheader ]
%sext = shl i32 %p.012, 24
%conv = ashr exact i32 %sext, 24
%arrayidx = getelementptr inbounds [250 x i32], [250 x i32]* @a, i64 0, i64 %indvars.iv
store i32 %conv, i32* %arrayidx, align 4
%add = add nsw i32 %conv, %step.addr.010
%add3 = add nsw i32 %step.addr.010, 2
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%exitcond = icmp eq i64 %indvars.iv.next, %wide.trip.count
br i1 %exitcond, label %for.end.loopexit, label %for.body
for.end.loopexit:
br label %for.end
for.end:
ret void
}
; Lastly, we also check the case where we can tell at compile time that
; the step of the induction is equal to sext(trunc(step)), in which case
; we don't have to check this equality at runtime (we only need the
; runtime overflow check). Therefore only the following overflow predicate
; will be added for runtime checking:
; {0,+,%cstep}<%for.body> Added Flags: <nssw>
;
; a[N];
; void doit4(int n, char cstep) {
; int i;
; char p = 0;
; int istep = cstep;
; for (i = 0; i < n; i++) {
; a[i] = p;
; p = p + istep;
; }
; }
; CHECK-LABEL: @doit4
; CHECK: vector.scevcheck
; CHECK: %mul = call { i8, i1 } @llvm.umul.with.overflow.i8(i8 {{.*}}, i8 {{.*}})
; CHECK-NOT: %mul = call { i8, i1 } @llvm.umul.with.overflow.i8(i8 {{.*}}, i8 {{.*}})
; CHECK: %{{.*}} = or i1 {{.*}}, %mul.overflow
; CHECK-NOT: %ident.check = icmp ne i32 {{.*}}, %{{.*}}
; CHECK-NOT: %{{.*}} = or i1 %{{.*}}, %ident.check
; CHECK-NOT: %mul = call { i8, i1 } @llvm.umul.with.overflow.i8(i8 {{.*}}, i8 {{.*}})
; CHECK: vector.body:
; CHECK: <4 x i32>
; Function Attrs: norecurse nounwind uwtable
define void @doit4(i32 %n, i8 signext %cstep) local_unnamed_addr {
entry:
%conv = sext i8 %cstep to i32
%cmp10 = icmp sgt i32 %n, 0
br i1 %cmp10, label %for.body.preheader, label %for.end
for.body.preheader:
%wide.trip.count = zext i32 %n to i64
br label %for.body
for.body:
%indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %for.body.preheader ]
%p.011 = phi i32 [ %add, %for.body ], [ 0, %for.body.preheader ]
%sext = shl i32 %p.011, 24
%conv2 = ashr exact i32 %sext, 24
%arrayidx = getelementptr inbounds [250 x i32], [250 x i32]* @a, i64 0, i64 %indvars.iv
store i32 %conv2, i32* %arrayidx, align 4
%add = add nsw i32 %conv2, %conv
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%exitcond = icmp eq i64 %indvars.iv.next, %wide.trip.count
br i1 %exitcond, label %for.end.loopexit, label %for.body
for.end.loopexit:
br label %for.end
for.end:
ret void
}
|
