summaryrefslogtreecommitdiffstats
path: root/clang/test/CodeGenCXX/stack-reuse.cpp
blob: 8325604391ae211506ebdeabeb96525fe4be1498 (plain)
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
// RUN: %clang_cc1 -triple armv7-unknown-linux-gnueabihf %s -o - -emit-llvm -O1 | FileCheck %s

// Stack should be reused when possible, no need to allocate two separate slots
// if they have disjoint lifetime.

// Sizes of objects are related to previously existed threshold of 32.  In case
// of S_large stack size is rounded to 40 bytes.

// 32B
struct S_small {
  int a[8];
};

// 36B
struct S_large {
  int a[9];
};

// Helper class for lifetime scope absence testing
struct Combiner {
  S_large a, b;

  Combiner(S_large);
  Combiner f();
};

extern S_small foo_small();
extern S_large foo_large();
extern void bar_small(S_small*);
extern void bar_large(S_large*);

// Prevent mangling of function names.
extern "C" {

void small_rvoed_unnamed_temporary_object() {
// CHECK-LABEL: define void @small_rvoed_unnamed_temporary_object
// CHECK: call void @llvm.lifetime.start
// CHECK: call void @_Z9foo_smallv
// CHECK: call void @llvm.lifetime.end
// CHECK: call void @llvm.lifetime.start
// CHECK: call void @_Z9foo_smallv
// CHECK: call void @llvm.lifetime.end

  foo_small();
  foo_small();
}

void large_rvoed_unnamed_temporary_object() {
// CHECK-LABEL: define void @large_rvoed_unnamed_temporary_object
// CHECK: call void @llvm.lifetime.start
// CHECK: call void @_Z9foo_largev
// CHECK: call void @llvm.lifetime.end
// CHECK: call void @llvm.lifetime.start
// CHECK: call void @_Z9foo_largev
// CHECK: call void @llvm.lifetime.end

  foo_large();
  foo_large();
}

void small_rvoed_named_temporary_object() {
// CHECK-LABEL: define void @small_rvoed_named_temporary_object
// CHECK: call void @llvm.lifetime.start
// CHECK: call void @_Z9foo_smallv
// CHECK: call void @llvm.lifetime.end
// CHECK: call void @llvm.lifetime.start
// CHECK: call void @_Z9foo_smallv
// CHECK: call void @llvm.lifetime.end

  {
    S_small s = foo_small();
  }
  {
    S_small s = foo_small();
  }
}

void large_rvoed_named_temporary_object() {
// CHECK-LABEL: define void @large_rvoed_named_temporary_object
// CHECK: call void @llvm.lifetime.start
// CHECK: call void @_Z9foo_largev
// CHECK: call void @llvm.lifetime.end
// CHECK: call void @llvm.lifetime.start
// CHECK: call void @_Z9foo_largev
// CHECK: call void @llvm.lifetime.end

  {
    S_large s = foo_large();
  }
  {
    S_large s = foo_large();
  }
}

void small_auto_object() {
// CHECK-LABEL: define void @small_auto_object
// CHECK: call void @llvm.lifetime.start
// CHECK: call void @_Z9bar_smallP7S_small
// CHECK: call void @llvm.lifetime.end
// CHECK: call void @llvm.lifetime.start
// CHECK: call void @_Z9bar_smallP7S_small
// CHECK: call void @llvm.lifetime.end

  {
    S_small s;
    bar_small(&s);
  }
  {
    S_small s;
    bar_small(&s);
  }
}

void large_auto_object() {
// CHECK-LABEL: define void @large_auto_object
// CHECK: call void @llvm.lifetime.start
// CHECK: call void @_Z9bar_largeP7S_large
// CHECK: call void @llvm.lifetime.end
// CHECK: call void @llvm.lifetime.start
// CHECK: call void @_Z9bar_largeP7S_large
// CHECK: call void @llvm.lifetime.end

  {
    S_large s;
    bar_large(&s);
  }
  {
    S_large s;
    bar_large(&s);
  }
}

int large_combiner_test(S_large s) {
// CHECK-LABEL: define i32 @large_combiner_test
// CHECK: [[T2:%.*]] = alloca %struct.Combiner
// CHECK: [[T1:%.*]] = alloca %struct.Combiner
// CHECK: [[T3:%.*]] = call %struct.Combiner* @_ZN8CombinerC1E7S_large(%struct.Combiner* nonnull [[T1]], [9 x i32] %s.coerce)
// CHECK: call void @_ZN8Combiner1fEv(%struct.Combiner* nonnull sret [[T2]], %struct.Combiner* nonnull [[T1]])
// CHECK: [[T4:%.*]] = getelementptr inbounds %struct.Combiner, %struct.Combiner* [[T2]], i32 0, i32 0, i32 0, i32 0
// CHECK: [[T5:%.*]] = load i32, i32* [[T4]]
// CHECK: ret i32 [[T5]]

  return Combiner(s).f().a.a[0];
}

}
OpenPOWER on IntegriCloud