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
| ; RUN: opt < %s -tailcallelim -verify-dom-info -S | FileCheck %s
; PR4323
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
; Several cases where tail call elimination should move the load above the call,
; then eliminate the tail recursion.
@global = external global i32 ; <i32*> [#uses=1]
@extern_weak_global = extern_weak global i32 ; <i32*> [#uses=1]
; This load can be moved above the call because the function won't write to it
; and the call has no side effects.
define fastcc i32 @raise_load_1(i32* %a_arg, i32 %a_len_arg, i32 %start_arg) nounwind readonly {
; CHECK-LABEL: @raise_load_1(
; CHECK-NOT: call
; CHECK: load i32, i32*
; CHECK-NOT: call
; CHECK: }
entry:
%tmp2 = icmp sge i32 %start_arg, %a_len_arg ; <i1> [#uses=1]
br i1 %tmp2, label %if, label %else
if: ; preds = %entry
ret i32 0
else: ; preds = %entry
%tmp7 = add i32 %start_arg, 1 ; <i32> [#uses=1]
%tmp8 = call fastcc i32 @raise_load_1(i32* %a_arg, i32 %a_len_arg, i32 %tmp7) ; <i32> [#uses=1]
%tmp9 = load i32, i32* %a_arg ; <i32> [#uses=1]
%tmp10 = add i32 %tmp9, %tmp8 ; <i32> [#uses=1]
ret i32 %tmp10
}
; This load can be moved above the call because the function won't write to it
; and the load provably can't trap.
define fastcc i32 @raise_load_2(i32* %a_arg, i32 %a_len_arg, i32 %start_arg) readonly {
; CHECK-LABEL: @raise_load_2(
; CHECK-NOT: call
; CHECK: load i32, i32*
; CHECK-NOT: call
; CHECK: }
entry:
%tmp2 = icmp sge i32 %start_arg, %a_len_arg ; <i1> [#uses=1]
br i1 %tmp2, label %if, label %else
if: ; preds = %entry
ret i32 0
else: ; preds = %entry
%nullcheck = icmp eq i32* %a_arg, null ; <i1> [#uses=1]
br i1 %nullcheck, label %unwind, label %recurse
unwind: ; preds = %else
unreachable
recurse: ; preds = %else
%tmp7 = add i32 %start_arg, 1 ; <i32> [#uses=1]
%tmp8 = call fastcc i32 @raise_load_2(i32* %a_arg, i32 %a_len_arg, i32 %tmp7) ; <i32> [#uses=1]
%tmp9 = load i32, i32* @global ; <i32> [#uses=1]
%tmp10 = add i32 %tmp9, %tmp8 ; <i32> [#uses=1]
ret i32 %tmp10
}
; This load can be safely moved above the call (even though it's from an
; extern_weak global) because the call has no side effects.
define fastcc i32 @raise_load_3(i32* %a_arg, i32 %a_len_arg, i32 %start_arg) nounwind readonly {
; CHECK-LABEL: @raise_load_3(
; CHECK-NOT: call
; CHECK: load i32, i32*
; CHECK-NOT: call
; CHECK: }
entry:
%tmp2 = icmp sge i32 %start_arg, %a_len_arg ; <i1> [#uses=1]
br i1 %tmp2, label %if, label %else
if: ; preds = %entry
ret i32 0
else: ; preds = %entry
%tmp7 = add i32 %start_arg, 1 ; <i32> [#uses=1]
%tmp8 = call fastcc i32 @raise_load_3(i32* %a_arg, i32 %a_len_arg, i32 %tmp7) ; <i32> [#uses=1]
%tmp9 = load i32, i32* @extern_weak_global ; <i32> [#uses=1]
%tmp10 = add i32 %tmp9, %tmp8 ; <i32> [#uses=1]
ret i32 %tmp10
}
; The second load can be safely moved above the call even though it's from an
; unknown pointer (which normally means it might trap) because the first load
; proves it doesn't trap.
define fastcc i32 @raise_load_4(i32* %a_arg, i32 %a_len_arg, i32 %start_arg) readonly {
; CHECK-LABEL: @raise_load_4(
; CHECK-NOT: call
; CHECK: load i32, i32*
; CHECK-NEXT: load i32, i32*
; CHECK-NOT: call
; CHECK: }
entry:
%tmp2 = icmp sge i32 %start_arg, %a_len_arg ; <i1> [#uses=1]
br i1 %tmp2, label %if, label %else
if: ; preds = %entry
ret i32 0
else: ; preds = %entry
%nullcheck = icmp eq i32* %a_arg, null ; <i1> [#uses=1]
br i1 %nullcheck, label %unwind, label %recurse
unwind: ; preds = %else
unreachable
recurse: ; preds = %else
%tmp7 = add i32 %start_arg, 1 ; <i32> [#uses=1]
%first = load i32, i32* %a_arg ; <i32> [#uses=1]
%tmp8 = call fastcc i32 @raise_load_4(i32* %a_arg, i32 %first, i32 %tmp7) ; <i32> [#uses=1]
%second = load i32, i32* %a_arg ; <i32> [#uses=1]
%tmp10 = add i32 %second, %tmp8 ; <i32> [#uses=1]
ret i32 %tmp10
}
; This load can be moved above the call because the function won't write to it
; and the a_arg is dereferenceable.
define fastcc i32 @raise_load_5(i32* dereferenceable(4) %a_arg, i32 %a_len_arg, i32 %start_arg) readonly {
; CHECK-LABEL: @raise_load_5(
; CHECK-NOT: call
; CHECK: load i32, i32*
; CHECK-NOT: call
; CHECK: }
entry:
%tmp2 = icmp sge i32 %start_arg, %a_len_arg ; <i1> [#uses=1]
br i1 %tmp2, label %if, label %else
if: ; preds = %entry
ret i32 0
else: ; preds = %entry
%tmp7 = add i32 %start_arg, 1 ; <i32> [#uses=1]
%tmp8 = call fastcc i32 @raise_load_5(i32* %a_arg, i32 %a_len_arg, i32 %tmp7) ; <i32> [#uses=1]
%tmp9 = load i32, i32* %a_arg ; <i32> [#uses=1]
%tmp10 = add i32 %tmp9, %tmp8 ; <i32> [#uses=1]
ret i32 %tmp10
}
; This load can be moved above the call because the function call does not write to the memory the load
; is accessing and the load is safe to speculate.
define fastcc i32 @raise_load_6(i32* %a_arg, i32 %a_len_arg, i32 %start_arg) nounwind {
; CHECK-LABEL: @raise_load_6(
; CHECK-NOT: call
; CHECK: load i32, i32*
; CHECK-NOT: call
; CHECK: }
entry:
%s = alloca i32
store i32 4, i32* %s
%tmp2 = icmp sge i32 %start_arg, %a_len_arg ; <i1> [#uses=1]
br i1 %tmp2, label %if, label %else
if: ; preds = %entry
store i32 1, i32* %a_arg
ret i32 0
else: ; preds = %entry
%tmp7 = add i32 %start_arg, 1 ; <i32> [#uses=1]
%tmp8 = call fastcc i32 @raise_load_6(i32* %a_arg, i32 %a_len_arg, i32 %tmp7) ; <i32> [#uses=1]
%tmp9 = load i32, i32* %s ; <i32> [#uses=1]
%tmp10 = add i32 %tmp9, %tmp8 ; <i32> [#uses=1]
ret i32 %tmp10
}
|