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
|
//@ compile-flags: -C no-prepopulate-passes
#![crate_type = "lib"]
use std::mem::MaybeUninit;
// CHECK-LABEL: @zero_sized_elem
#[no_mangle]
pub fn zero_sized_elem() {
// CHECK-NOT: br label %repeat_loop_header{{.*}}
// CHECK-NOT: call void @llvm.memset.p0
let x = [(); 4];
opaque(&x);
}
// CHECK-LABEL: @zero_len_array
#[no_mangle]
pub fn zero_len_array() {
// CHECK-NOT: br label %repeat_loop_header{{.*}}
// CHECK-NOT: call void @llvm.memset.p0
let x = [4; 0];
opaque(&x);
}
// CHECK-LABEL: @byte_array
#[no_mangle]
pub fn byte_array() {
// CHECK: call void @llvm.memset.{{.+}}(ptr {{.*}}, i8 7, i{{[0-9]+}} 4
// CHECK-NOT: br label %repeat_loop_header{{.*}}
let x = [7u8; 4];
opaque(&x);
}
#[allow(dead_code)]
#[derive(Copy, Clone)]
enum Init {
Loop,
Memset,
}
// CHECK-LABEL: @byte_enum_array
#[no_mangle]
pub fn byte_enum_array() {
// CHECK: call void @llvm.memset.{{.+}}(ptr {{.*}}, i8 {{.*}}, i{{[0-9]+}} 4
// CHECK-NOT: br label %repeat_loop_header{{.*}}
let x = [Init::Memset; 4];
opaque(&x);
}
// CHECK-LABEL: @zeroed_integer_array
#[no_mangle]
pub fn zeroed_integer_array() {
// CHECK: call void @llvm.memset.{{.+}}(ptr {{.*}}, i8 0, i{{[0-9]+}} 16
// CHECK-NOT: br label %repeat_loop_header{{.*}}
let x = [0u32; 4];
opaque(&x);
}
// CHECK-LABEL: @nonzero_integer_array
#[no_mangle]
pub fn nonzero_integer_array() {
// CHECK: br label %repeat_loop_header{{.*}}
// CHECK-NOT: call void @llvm.memset.p0
let x = [0x1a_2b_3c_4d_u32; 4];
opaque(&x);
}
const N: usize = 100;
// CHECK-LABEL: @u16_init_one_bytes
#[no_mangle]
pub fn u16_init_one_bytes() -> [u16; N] {
// CHECK-NOT: select
// CHECK-NOT: br
// CHECK-NOT: switch
// CHECK-NOT: icmp
// CHECK: call void @llvm.memset.p0
[const { u16::from_be_bytes([1, 1]) }; N]
}
// CHECK-LABEL: @option_none_init
#[no_mangle]
pub fn option_none_init() -> [Option<u8>; N] {
// CHECK-NOT: select
// CHECK-NOT: br
// CHECK-NOT: switch
// CHECK-NOT: icmp
// CHECK: call void @llvm.memset.p0
[const { None }; N]
}
// If there is partial provenance or some bytes are initialized and some are not,
// we can't really do better than initialize bytes or groups of bytes together.
// CHECK-LABEL: @option_maybe_uninit_init
#[no_mangle]
pub fn option_maybe_uninit_init() -> [MaybeUninit<u16>; N] {
// CHECK-NOT: select
// CHECK: br label %repeat_loop_header{{.*}}
// CHECK-NOT: switch
// CHECK: icmp
// CHECK-NOT: call void @llvm.memset.p0
[const {
let mut val: MaybeUninit<u16> = MaybeUninit::uninit();
let ptr = val.as_mut_ptr() as *mut u8;
unsafe {
ptr.write(0);
}
val
}; N]
}
#[repr(packed)]
struct Packed {
start: u8,
ptr: &'static (),
rest: u16,
rest2: u8,
}
// If there is partial provenance or some bytes are initialized and some are not,
// we can't really do better than initialize bytes or groups of bytes together.
// CHECK-LABEL: @option_maybe_uninit_provenance
#[no_mangle]
pub fn option_maybe_uninit_provenance() -> [MaybeUninit<Packed>; N] {
// CHECK-NOT: select
// CHECK: br label %repeat_loop_header{{.*}}
// CHECK-NOT: switch
// CHECK: icmp
// CHECK-NOT: call void @llvm.memset.p0
[const {
let mut val: MaybeUninit<Packed> = MaybeUninit::uninit();
unsafe {
let ptr = &raw mut (*val.as_mut_ptr()).ptr;
static HAS_ADDR: () = ();
ptr.write_unaligned(&HAS_ADDR);
}
val
}; N]
}
// Use an opaque function to prevent rustc from removing useless drops.
#[inline(never)]
pub fn opaque(_: impl Sized) {}
|
