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
|
; RUN: opt < %s -basicaa -sink -S | FileCheck %s
@A = external global i32
@B = external global i32
; Sink should sink the load past the store (which doesn't overlap) into
; the block that uses it.
; CHECK-LABEL: @foo(
; CHECK: true:
; CHECK-NEXT: %l = load i32* @A
; CHECK-NEXT: ret i32 %l
define i32 @foo(i1 %z) {
%l = load i32* @A
store i32 0, i32* @B
br i1 %z, label %true, label %false
true:
ret i32 %l
false:
ret i32 0
}
; But don't sink load volatiles...
; CHECK-LABEL: @foo2(
; CHECK: load volatile
; CHECK-NEXT: store i32
define i32 @foo2(i1 %z) {
%l = load volatile i32* @A
store i32 0, i32* @B
br i1 %z, label %true, label %false
true:
ret i32 %l
false:
ret i32 0
}
; Sink to the nearest post-dominator
; CHECK-LABEL: @diamond(
; CHECK: X:
; CHECK-NEXT: phi
; CHECK-NEXT: mul nsw
; CHECK-NEXT: sub
define i32 @diamond(i32 %a, i32 %b, i32 %c) {
%1 = mul nsw i32 %c, %b
%2 = icmp sgt i32 %a, 0
br i1 %2, label %B0, label %B1
B0: ; preds = %0
br label %X
B1: ; preds = %0
br label %X
X: ; preds = %5, %3
%.01 = phi i32 [ %c, %B0 ], [ %a, %B1 ]
%R = sub i32 %1, %.01
ret i32 %R
}
; We shouldn't sink constant sized allocas from the entry block, since CodeGen
; interprets allocas outside the entry block as dynamically sized stack objects.
; CHECK-LABEL: @alloca_nosink
; CHECK: entry:
; CHECK-NEXT: alloca
define i32 @alloca_nosink(i32 %a, i32 %b) {
entry:
%0 = alloca i32
%1 = icmp ne i32 %a, 0
br i1 %1, label %if, label %endif
if:
%2 = getelementptr i32* %0, i32 1
store i32 0, i32* %0
store i32 1, i32* %2
%3 = getelementptr i32* %0, i32 %b
%4 = load i32* %3
ret i32 %4
endif:
ret i32 0
}
; Make sure we sink dynamic sized allocas
; CHECK-LABEL: @alloca_sink_dynamic
; CHECK: entry:
; CHECK-NOT: alloca
; CHECK: if:
; CHECK-NEXT: alloca
define i32 @alloca_sink_dynamic(i32 %a, i32 %b, i32 %size) {
entry:
%0 = alloca i32, i32 %size
%1 = icmp ne i32 %a, 0
br i1 %1, label %if, label %endif
if:
%2 = getelementptr i32* %0, i32 1
store i32 0, i32* %0
store i32 1, i32* %2
%3 = getelementptr i32* %0, i32 %b
%4 = load i32* %3
ret i32 %4
endif:
ret i32 0
}
; We also want to sink allocas that are not in the entry block. These
; will already be considered as dynamically sized stack objects, so sinking
; them does no further damage.
; CHECK-LABEL: @alloca_sink_nonentry
; CHECK: if0:
; CHECK-NOT: alloca
; CHECK: if:
; CHECK-NEXT: alloca
define i32 @alloca_sink_nonentry(i32 %a, i32 %b, i32 %c) {
entry:
%cmp = icmp ne i32 %c, 0
br i1 %cmp, label %endif, label %if0
if0:
%0 = alloca i32
%1 = icmp ne i32 %a, 0
br i1 %1, label %if, label %endif
if:
%2 = getelementptr i32* %0, i32 1
store i32 0, i32* %0
store i32 1, i32* %2
%3 = getelementptr i32* %0, i32 %b
%4 = load i32* %3
ret i32 %4
endif:
ret i32 0
}
|
