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
|
pub trait FlushSubnormals: Sized {
fn flush(self) -> Self {
self
}
}
impl<T> FlushSubnormals for *const T {}
impl<T> FlushSubnormals for *mut T {}
macro_rules! impl_float {
{ $($ty:ty),* } => {
$(
impl FlushSubnormals for $ty {
fn flush(self) -> Self {
let is_f32 = core::mem::size_of::<Self>() == 4;
let ppc_flush = is_f32 && cfg!(all(
any(target_arch = "powerpc", all(target_arch = "powerpc64", target_endian = "big")),
target_feature = "altivec",
not(target_feature = "vsx"),
));
let arm_flush = is_f32 && cfg!(all(target_arch = "arm", target_feature = "neon"));
let flush = ppc_flush || arm_flush;
if flush && self.is_subnormal() {
<$ty>::copysign(0., self)
} else {
self
}
}
}
)*
}
}
macro_rules! impl_else {
{ $($ty:ty),* } => {
$(
impl FlushSubnormals for $ty {}
)*
}
}
impl_float! { f32, f64 }
impl_else! { i8, i16, i32, i64, isize, u8, u16, u32, u64, usize }
/// AltiVec should flush subnormal inputs to zero, but QEMU seems to only flush outputs.
/// https://gitlab.com/qemu-project/qemu/-/issues/1779
#[cfg(all(
any(target_arch = "powerpc", target_arch = "powerpc64"),
target_feature = "altivec"
))]
fn in_buggy_qemu() -> bool {
use std::sync::OnceLock;
static BUGGY: OnceLock<bool> = OnceLock::new();
fn add(x: f32, y: f32) -> f32 {
#[cfg(target_arch = "powerpc")]
use core::arch::powerpc::*;
#[cfg(target_arch = "powerpc64")]
use core::arch::powerpc64::*;
let array: [f32; 4] =
unsafe { core::mem::transmute(vec_add(vec_splats(x), vec_splats(y))) };
array[0]
}
*BUGGY.get_or_init(|| add(-1.0857398e-38, 0.).is_sign_negative())
}
#[cfg(all(
any(target_arch = "powerpc", target_arch = "powerpc64"),
target_feature = "altivec"
))]
pub fn flush_in<T: FlushSubnormals>(x: T) -> T {
if in_buggy_qemu() {
x
} else {
x.flush()
}
}
#[cfg(not(all(
any(target_arch = "powerpc", target_arch = "powerpc64"),
target_feature = "altivec"
)))]
pub fn flush_in<T: FlushSubnormals>(x: T) -> T {
x.flush()
}
pub fn flush<T: FlushSubnormals>(x: T) -> T {
x.flush()
}
|
