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
| ; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s
; Trip counts with trivial exit conditions.
; CHECK: Determining loop execution counts for: @a
; CHECK: Loop %loop: Unpredictable backedge-taken count.
; CHECK: Loop %loop: Unpredictable max backedge-taken count.
; CHECK: Determining loop execution counts for: @b
; CHECK: Loop %loop: backedge-taken count is false
; CHECK: Loop %loop: max backedge-taken count is false
; CHECK: Determining loop execution counts for: @c
; CHECK: Loop %loop: backedge-taken count is false
; CHECK: Loop %loop: max backedge-taken count is false
; CHECK: Determining loop execution counts for: @d
; CHECK: Loop %loop: Unpredictable backedge-taken count.
; CHECK: Loop %loop: Unpredictable max backedge-taken count.
define void @a(i64 %n) nounwind {
entry:
%t0 = icmp sgt i64 %n, 0
br i1 %t0, label %loop, label %return
loop:
%i = phi i64 [ %i.next, %loop ], [ 0, %entry ]
%i.next = add nsw i64 %i, 1
%exitcond = icmp eq i64 %i.next, %n
br i1 false, label %return, label %loop
return:
ret void
}
define void @b(i64 %n) nounwind {
entry:
%t0 = icmp sgt i64 %n, 0
br i1 %t0, label %loop, label %return
loop:
%i = phi i64 [ %i.next, %loop ], [ 0, %entry ]
%i.next = add nsw i64 %i, 1
%exitcond = icmp eq i64 %i.next, %n
br i1 true, label %return, label %loop
return:
ret void
}
define void @c(i64 %n) nounwind {
entry:
%t0 = icmp sgt i64 %n, 0
br i1 %t0, label %loop, label %return
loop:
%i = phi i64 [ %i.next, %loop ], [ 0, %entry ]
%i.next = add nsw i64 %i, 1
%exitcond = icmp eq i64 %i.next, %n
br i1 false, label %loop, label %return
return:
ret void
}
define void @d(i64 %n) nounwind {
entry:
%t0 = icmp sgt i64 %n, 0
br i1 %t0, label %loop, label %return
loop:
%i = phi i64 [ %i.next, %loop ], [ 0, %entry ]
%i.next = add nsw i64 %i, 1
%exitcond = icmp eq i64 %i.next, %n
br i1 true, label %loop, label %return
return:
ret void
}
; Trip counts for non-polynomial iterations. It's theoretically possible
; to compute a maximum count for these, but short of that, ScalarEvolution
; should return unknown.
; PR7416
; CHECK: Determining loop execution counts for: @nonpolynomial
; CHECK-NEXT: Loop %loophead: Unpredictable backedge-taken count
; CHECK-NEXT: Loop %loophead: Unpredictable max backedge-taken count
declare i1 @g() nounwind
define void @nonpolynomial() {
entry:
br label %loophead
loophead:
%x = phi i32 [0, %entry], [%x.1, %bb1], [%x.2, %bb2]
%y = icmp slt i32 %x, 100
br i1 %y, label %loopbody, label %retbb
loopbody:
%z = call i1 @g()
br i1 %z, label %bb1, label %bb2
bb1:
%x.1 = add i32 %x, 2
br label %loophead
bb2:
%x.2 = add i32 %x, 3
br label %loophead
retbb:
ret void
}
; PHI nodes with all constant operands.
; CHECK: Determining loop execution counts for: @constant_phi_operands
; CHECK: Loop %loop: backedge-taken count is 1
; CHECK: Loop %loop: max backedge-taken count is 1
define void @constant_phi_operands() nounwind {
entry:
br label %loop
loop:
%i = phi i64 [ 1, %loop ], [ 0, %entry ]
%exitcond = icmp eq i64 %i, 1
br i1 %exitcond, label %return, label %loop
return:
ret void
}
; PR16130: Loop exit depends on an 'or' expression.
; One side of the expression test against a value that will be skipped.
; We can't assume undefined behavior just because we have an NSW flag.
;
; CHECK: Determining loop execution counts for: @exit_orcond_nsw
; CHECK: Loop %for.body.i: Unpredictable backedge-taken count.
; CHECK: Loop %for.body.i: max backedge-taken count is 1
define void @exit_orcond_nsw(i32 *%a) nounwind {
entry:
br label %for.body.i
for.body.i: ; preds = %for.body.i, %entry
%b.01.i = phi i32 [ 0, %entry ], [ %add.i, %for.body.i ]
%tobool.i = icmp ne i32 %b.01.i, 0
%add.i = add nsw i32 %b.01.i, 8
%cmp.i = icmp eq i32 %add.i, 13
%or.cond = or i1 %tobool.i, %cmp.i
br i1 %or.cond, label %exit, label %for.body.i
exit: ; preds = %for.body.i
%b.01.i.lcssa = phi i32 [ %b.01.i, %for.body.i ]
store i32 %b.01.i.lcssa, i32* %a, align 4
ret void
}
|