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Rollup merge of #107973 - saethlin:fix-simd-test-ub, r=workingjubilee
Fix unintentional UB in SIMD tests r? `@workingjubilee`
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Original file line number | Diff line number | Diff line change |
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// run-pass | ||
#![allow(unused_must_use)] | ||
// ignore-emscripten FIXME(#45351) hits an LLVM assert | ||
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#![feature(repr_simd, platform_intrinsics, concat_idents, test)] | ||
#![allow(non_camel_case_types)] | ||
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extern crate test; | ||
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#[repr(simd)] | ||
#[derive(PartialEq, Debug)] | ||
struct i32x4(i32, i32, i32, i32); | ||
#[repr(simd)] | ||
#[derive(PartialEq, Debug)] | ||
struct i8x4(i8, i8, i8, i8); | ||
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#[repr(simd)] | ||
#[derive(PartialEq, Debug)] | ||
struct u32x4(u32, u32, u32, u32); | ||
#[repr(simd)] | ||
#[derive(PartialEq, Debug)] | ||
struct u8x4(u8, u8, u8, u8); | ||
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#[repr(simd)] | ||
#[derive(PartialEq, Debug)] | ||
struct f32x4(f32, f32, f32, f32); | ||
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#[repr(simd)] | ||
#[derive(PartialEq, Debug)] | ||
struct f64x4(f64, f64, f64, f64); | ||
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#![feature(repr_simd, platform_intrinsics)] | ||
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extern "platform-intrinsic" { | ||
fn simd_cast<T, U>(x: T) -> U; | ||
} | ||
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const A: i32 = -1234567; | ||
const B: i32 = 12345678; | ||
const C: i32 = -123456789; | ||
const D: i32 = 1234567890; | ||
use std::cmp::{max, min}; | ||
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trait Foo { | ||
fn is_float() -> bool { false } | ||
fn in_range(x: i32) -> bool; | ||
} | ||
impl Foo for i32 { | ||
fn in_range(_: i32) -> bool { true } | ||
} | ||
impl Foo for i8 { | ||
fn in_range(x: i32) -> bool { -128 <= x && x < 128 } | ||
} | ||
impl Foo for u32 { | ||
fn in_range(x: i32) -> bool { 0 <= x } | ||
} | ||
impl Foo for u8 { | ||
fn in_range(x: i32) -> bool { 0 <= x && x < 128 } | ||
} | ||
impl Foo for f32 { | ||
fn is_float() -> bool { true } | ||
fn in_range(_: i32) -> bool { true } | ||
} | ||
impl Foo for f64 { | ||
fn is_float() -> bool { true } | ||
fn in_range(_: i32) -> bool { true } | ||
} | ||
#[derive(Copy, Clone)] | ||
#[repr(simd)] | ||
struct V<T>([T; 2]); | ||
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fn main() { | ||
macro_rules! test { | ||
($from: ident, $to: ident) => {{ | ||
// force the casts to actually happen, or else LLVM/rustc | ||
// may fold them and get slightly different results. | ||
let (a, b, c, d) = test::black_box((A as $from, B as $from, C as $from, D as $from)); | ||
// the SIMD vectors are all FOOx4, so we can concat_idents | ||
// so we don't have to pass in the extra args to the macro | ||
let mut from = simd_cast(concat_idents!($from, x4)(a, b, c, d)); | ||
let mut to = concat_idents!($to, x4)(a as $to, | ||
b as $to, | ||
c as $to, | ||
d as $to); | ||
// assist type inference, it needs to know what `from` is | ||
// for the `if` statements. | ||
to == from; | ||
unsafe { | ||
let u = V::<u32>([i16::MIN as u32, i16::MAX as u32]); | ||
let i: V<i16> = simd_cast(u); | ||
assert_eq!(i.0[0], u.0[0] as i16); | ||
assert_eq!(i.0[1], u.0[1] as i16); | ||
} | ||
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// there are platform differences for some out of range | ||
// casts, so we just normalize such things: it's OK for | ||
// "invalid" calculations to result in nonsense answers. | ||
// (e.g., negative float to unsigned integer goes through a | ||
// library routine on the default i686 platforms, and the | ||
// implementation of that routine differs on e.g., Linux | ||
// vs. macOS, resulting in different answers.) | ||
if $from::is_float() { | ||
if !$to::in_range(A) { from.0 = 0 as $to; to.0 = 0 as $to; } | ||
if !$to::in_range(B) { from.1 = 0 as $to; to.1 = 0 as $to; } | ||
if !$to::in_range(C) { from.2 = 0 as $to; to.2 = 0 as $to; } | ||
if !$to::in_range(D) { from.3 = 0 as $to; to.3 = 0 as $to; } | ||
} | ||
unsafe { | ||
let f = V::<f32>([i16::MIN as f32, i16::MAX as f32]); | ||
let i: V<i16> = simd_cast(f); | ||
assert_eq!(i.0[0], f.0[0] as i16); | ||
assert_eq!(i.0[1], f.0[1] as i16); | ||
} | ||
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assert!(to == from, | ||
"{} -> {} ({:?} != {:?})", stringify!($from), stringify!($to), | ||
from, to); | ||
}} | ||
unsafe { | ||
let f = V::<f32>([u8::MIN as f32, u8::MAX as f32]); | ||
let u: V<u8> = simd_cast(f); | ||
assert_eq!(u.0[0], f.0[0] as u8); | ||
assert_eq!(u.0[1], f.0[1] as u8); | ||
} | ||
macro_rules! tests { | ||
(: $($to: ident),*) => { () }; | ||
// repeating the list twice is easier than writing a cartesian | ||
// product macro | ||
($from: ident $(, $from_: ident)*: $($to: ident),*) => { | ||
fn $from() { unsafe { $( test!($from, $to); )* } } | ||
tests!($($from_),*: $($to),*) | ||
}; | ||
($($types: ident),*) => {{ | ||
tests!($($types),* : $($types),*); | ||
$($types();)* | ||
}} | ||
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unsafe { | ||
// We would like to do isize::MIN..=isize::MAX, but those values are not representable in | ||
// an f64, so we clamp to the range of an i32 to prevent running into UB. | ||
let f = V::<f64>([ | ||
max(isize::MIN, i32::MIN as isize) as f64, | ||
min(isize::MAX, i32::MAX as isize) as f64, | ||
]); | ||
let i: V<isize> = simd_cast(f); | ||
assert_eq!(i.0[0], f.0[0] as isize); | ||
assert_eq!(i.0[1], f.0[1] as isize); | ||
} | ||
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// test various combinations, including truncation, | ||
// signed/unsigned extension, and floating point casts. | ||
tests!(i32, i8, u32, u8, f32); | ||
tests!(i32, u32, f32, f64) | ||
unsafe { | ||
let f = V::<f64>([ | ||
max(usize::MIN, u32::MIN as usize) as f64, | ||
min(usize::MAX, u32::MAX as usize) as f64, | ||
]); | ||
let u: V<usize> = simd_cast(f); | ||
assert_eq!(u.0[0], f.0[0] as usize); | ||
assert_eq!(u.0[1], f.0[1] as usize); | ||
} | ||
} |
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