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
|
; RUN: opt -S -jump-threading < %s | FileCheck %s
declare void @foo()
declare void @bar()
declare void @baz()
declare void @quux()
; Jump threading of branch with select as condition.
; Mostly theoretical since instruction combining simplifies all selects of
; booleans where at least one operand is true/false/undef.
; CHECK: @test_br
; CHECK-NEXT: entry:
; CHECK-NEXT: br i1 %cond, label %L1,
define void @test_br(i1 %cond, i1 %value) nounwind {
entry:
br i1 %cond, label %L0, label %L3
L0:
%expr = select i1 %cond, i1 true, i1 %value
br i1 %expr, label %L1, label %L2
L1:
call void @foo()
ret void
L2:
call void @bar()
ret void
L3:
call void @baz()
br label %L0
}
; Jump threading of switch with select as condition.
; CHECK: @test_switch
; CHECK-NEXT: entry:
; CHECK-NEXT: br i1 %cond, label %L1,
define void @test_switch(i1 %cond, i8 %value) nounwind {
entry:
br i1 %cond, label %L0, label %L4
L0:
%expr = select i1 %cond, i8 1, i8 %value
switch i8 %expr, label %L3 [i8 1, label %L1 i8 2, label %L2]
L1:
call void @foo()
ret void
L2:
call void @bar()
ret void
L3:
call void @baz()
ret void
L4:
call void @quux()
br label %L0
}
; Make sure the blocks in the indirectbr test aren't trivially removable as
; successors by taking their addresses.
@anchor = constant [3 x i8*] [
i8* blockaddress(@test_indirectbr, %L1),
i8* blockaddress(@test_indirectbr, %L2),
i8* blockaddress(@test_indirectbr, %L3)
]
; Jump threading of indirectbr with select as address.
; CHECK: @test_indirectbr
; CHECK-NEXT: entry:
; CHECK-NEXT: br i1 %cond, label %L1, label %L3
define void @test_indirectbr(i1 %cond, i8* %address) nounwind {
entry:
br i1 %cond, label %L0, label %L3
L0:
%indirect.goto.dest = select i1 %cond, i8* blockaddress(@test_indirectbr, %L1), i8* %address
indirectbr i8* %indirect.goto.dest, [label %L1, label %L2, label %L3]
L1:
call void @foo()
ret void
L2:
call void @bar()
ret void
L3:
call void @baz()
ret void
}
; A more complicated case: the condition is a select based on a comparison.
; CHECK: @test_switch_cmp
; CHECK-NEXT: entry:
; CHECK-NEXT: br i1 %cond, label %L0, label %[[THREADED:[A-Za-z.0-9]+]]
; CHECK: [[THREADED]]:
; CHECK-NEXT: call void @quux
; CHECK-NEXT: br label %L1
define void @test_switch_cmp(i1 %cond, i32 %val, i8 %value) nounwind {
entry:
br i1 %cond, label %L0, label %L4
L0:
%val.phi = phi i32 [%val, %entry], [-1, %L4]
%cmp = icmp slt i32 %val.phi, 0
%expr = select i1 %cmp, i8 1, i8 %value
switch i8 %expr, label %L3 [i8 1, label %L1 i8 2, label %L2]
L1:
call void @foo()
ret void
L2:
call void @bar()
ret void
L3:
call void @baz()
ret void
L4:
call void @quux()
br label %L0
}
|
