1; RUN: opt -passes='loop(unswitch),verify<loops>' -S < %s | FileCheck %s
2
3declare void @unknown()
4declare void @unknown2()
5
6@y = global i64 0, align 8
7
8; The following is approximately:
9; void f(bool *x) {
10;   for (int i = 0; i < 1; ++i) {
11;     if (*x) {
12;       if (y)
13;         unknown();
14;       else
15;         break;
16;     }
17;   }
18; }
19; With MemorySanitizer, the loop can not be unswitched on "y", because "y" could
20; be uninitialized when x == false.
21; Test that the branch on "y" is inside the loop (after the first unconditional
22; branch).
23
24define void @may_not_execute_trivial(i1* %x) sanitize_memory {
25; CHECK-LABEL: @may_not_execute_trivial(
26entry:
27  %y = load i64, i64* @y, align 8
28  %y.cmp = icmp eq i64 %y, 0
29  br label %for.body
30; CHECK: %[[Y:.*]] = load i64, i64* @y
31; CHECK: %[[YCMP:.*]] = icmp eq i64 %[[Y]], 0
32; CHECK-NOT: br i1
33; CHECK: br label %for.body
34
35for.body:
36  %i = phi i32 [ 0, %entry ], [ %inc, %for.inc ]
37  %x.load = load i1, i1* %x
38  br i1 %x.load, label %for.inc, label %if.then
39; CHECK: %[[XLOAD:.*]] = load i1, i1* %x
40; CHECK: br i1 %[[XLOAD]]
41
42if.then:
43  br i1 %y.cmp, label %for.end, label %if.then4
44; CHECK: br i1 %[[YCMP]]
45
46if.then4:
47  call void @unknown()
48  br label %for.inc
49
50for.inc:
51  %inc = add nsw i32 %i, 1
52  %cmp = icmp slt i32 %inc, 1
53  br i1 %cmp, label %for.body, label %for.end
54
55for.end:
56  ret void
57}
58
59
60; The same as above, but "y" is a function parameter instead of a global.
61; This shows that it is not enough to suppress hoisting of load instructions,
62; the actual problem is in the speculative branching.
63
64define void @may_not_execute2_trivial(i1* %x, i1 %y) sanitize_memory {
65; CHECK-LABEL: @may_not_execute2_trivial(
66entry:
67  br label %for.body
68; CHECK-NOT: br i1
69; CHECK: br label %for.body
70
71for.body:
72  %i = phi i32 [ 0, %entry ], [ %inc, %for.inc ]
73  %x.load = load i1, i1* %x
74  br i1 %x.load, label %for.inc, label %if.then
75; CHECK: %[[XLOAD:.*]] = load i1, i1* %x
76; CHECK: br i1 %[[XLOAD]]
77
78if.then:
79  br i1 %y, label %for.end, label %if.then4
80; CHECK: br i1 %y
81
82if.then4:
83  call void @unknown()
84  br label %for.inc
85
86for.inc:
87  %inc = add nsw i32 %i, 1
88  %cmp = icmp slt i32 %inc, 1
89  br i1 %cmp, label %for.body, label %for.end
90
91for.end:
92  ret void
93}
94
95
96; The following is approximately:
97; void f() {
98;   for (int i = 0; i < 1; ++i) {
99;     if (y)
100;       unknown();
101;     else
102;       break;
103;   }
104; }
105; "if (y)" is guaranteed to execute; the loop can be unswitched.
106
107define void @must_execute_trivial() sanitize_memory {
108; CHECK-LABEL: @must_execute_trivial(
109entry:
110  %y = load i64, i64* @y, align 8
111  %y.cmp = icmp eq i64 %y, 0
112  br label %for.body
113; CHECK:   %[[Y:.*]] = load i64, i64* @y
114; CHECK:   %[[YCMP:.*]] = icmp eq i64 %[[Y]], 0
115; CHECK:   br i1 %[[YCMP]], label %[[EXIT_SPLIT:.*]], label %[[PH:.*]]
116;
117; CHECK: [[PH]]:
118; CHECK:   br label %for.body
119
120for.body:
121  %i = phi i32 [ 0, %entry ], [ %inc, %for.inc ]
122  br i1 %y.cmp, label %for.end, label %if.then4
123; CHECK: br label %if.then4
124
125if.then4:
126  call void @unknown()
127  br label %for.inc
128
129for.inc:
130  %inc = add nsw i32 %i, 1
131  %cmp = icmp slt i32 %inc, 1
132  br i1 %cmp, label %for.body, label %for.end
133
134for.end:
135  ret void
136; CHECK: for.end:
137; CHECK:   br label %[[EXIT_SPLIT]]
138;
139; CHECK: [[EXIT_SPLIT]]:
140; CHECK:   ret void
141}
142