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Fix UB in _mm_movemask_ps, _mm_movemask_pd, _mm256_movemask_ps and _mm256_movemask_pd

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The `simd_bitmask` intrinsic requires each element to be all-1 or all-0, while the x86 functions only check for the highest bit.
This commit is contained in:
Eduardo Sánchez Muñoz 2023-10-11 22:03:52 +02:00 • committed by Amanieu d'Antras
parent b2c5bc9696
commit 45f28923ce
3 changed files with 16 additions and 4 deletions
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10
library/stdarch/crates/core_arch/src/x86/avx.rs
View file

@ -2066,7 +2066,10 @@ pub unsafe fn _mm_testnzc_ps(a: __m128, b: __m128) -> i32 {
#[cfg_attr(test, assert_instr(vmovmskpd))]
#[stable(feature = "simd_x86", since = "1.27.0")]
pub unsafe fn _mm256_movemask_pd(a: __m256d) -> i32 {
simd_bitmask::<u64x4, u8>(transmute(a)).into()
// Propagate the highest bit to the rest, because simd_bitmask
// requires all-1 or all-0.
let mask: i64x4 = simd_lt(transmute(a), i64x4::splat(0));
simd_bitmask::<i64x4, u8>(mask).into()
}
/// Sets each bit of the returned mask based on the most significant bit of the
@ -2079,7 +2082,10 @@ pub unsafe fn _mm256_movemask_pd(a: __m256d) -> i32 {
#[cfg_attr(test, assert_instr(vmovmskps))]
#[stable(feature = "simd_x86", since = "1.27.0")]
pub unsafe fn _mm256_movemask_ps(a: __m256) -> i32 {
simd_bitmask::<u32x8, u8>(transmute(a)).into()
// Propagate the highest bit to the rest, because simd_bitmask
// requires all-1 or all-0.
let mask: i32x8 = simd_lt(transmute(a), i32x8::splat(0));
simd_bitmask::<i32x8, u8>(mask).into()
}
/// Returns vector of type __m256d with all elements set to zero.

5
library/stdarch/crates/core_arch/src/x86/sse.rs
View file

@ -1081,7 +1081,10 @@ pub unsafe fn _mm_movelh_ps(a: __m128, b: __m128) -> __m128 {
#[cfg_attr(test, assert_instr(movmskps))]
#[stable(feature = "simd_x86", since = "1.27.0")]
pub unsafe fn _mm_movemask_ps(a: __m128) -> i32 {
simd_bitmask::<u32x4, u8>(transmute(a)).into()
// Propagate the highest bit to the rest, because simd_bitmask
// requires all-1 or all-0.
let mask: i32x4 = simd_lt(transmute(a), i32x4::splat(0));
simd_bitmask::<i32x4, u8>(mask).into()
}
/// Construct a `__m128` with the lowest element read from `p` and the other

5
library/stdarch/crates/core_arch/src/x86/sse2.rs
View file

@ -2450,7 +2450,10 @@ pub unsafe fn _mm_setzero_pd() -> __m128d {
#[cfg_attr(test, assert_instr(movmskpd))]
#[stable(feature = "simd_x86", since = "1.27.0")]
pub unsafe fn _mm_movemask_pd(a: __m128d) -> i32 {
simd_bitmask::<u64x2, u8>(transmute(a)).into()
// Propagate the highest bit to the rest, because simd_bitmask
// requires all-1 or all-0.
let mask: i64x2 = simd_lt(transmute(a), i64x2::splat(0));
simd_bitmask::<i64x2, u8>(mask).into()
}
/// Loads 128-bits (composed of 2 packed double-precision (64-bit)