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x86: use intrinsics::simd for hadds/hsubs #2012

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Merged
sayantn merged 1 commit into from
Feb 1, 2026
Merged

x86: use intrinsics::simd for hadds/hsubs #2012

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36 changes: 30 additions & 6 deletions crates/core_arch/src/x86/avx2.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -991,7 +991,21 @@ pub const fn _mm256_hadd_epi32(a: __m256i, b: __m256i) -> __m256i {
#[cfg_attr(test, assert_instr(vphaddsw))]
#[stable(feature = "simd_x86", since = "1.27.0")]
pub fn _mm256_hadds_epi16(a: __m256i, b: __m256i) -> __m256i {
unsafe { transmute(phaddsw(a.as_i16x16(), b.as_i16x16())) }
let a = a.as_i16x16();
let b = b.as_i16x16();
unsafe {
let even: i16x16 = simd_shuffle!(
a,
b,
[0, 2, 4, 6, 16, 18, 20, 22, 8, 10, 12, 14, 24, 26, 28, 30]
);
let odd: i16x16 = simd_shuffle!(
a,
b,
[1, 3, 5, 7, 17, 19, 21, 23, 9, 11, 13, 15, 25, 27, 29, 31]
);
simd_saturating_add(even, odd).as_m256i()
}
}

/// Horizontally subtract adjacent pairs of 16-bit integers in `a` and `b`.
Expand Down Expand Up @@ -1047,7 +1061,21 @@ pub const fn _mm256_hsub_epi32(a: __m256i, b: __m256i) -> __m256i {
#[cfg_attr(test, assert_instr(vphsubsw))]
#[stable(feature = "simd_x86", since = "1.27.0")]
pub fn _mm256_hsubs_epi16(a: __m256i, b: __m256i) -> __m256i {
unsafe { transmute(phsubsw(a.as_i16x16(), b.as_i16x16())) }
let a = a.as_i16x16();
let b = b.as_i16x16();
unsafe {
let even: i16x16 = simd_shuffle!(
a,
b,
[0, 2, 4, 6, 16, 18, 20, 22, 8, 10, 12, 14, 24, 26, 28, 30]
);
let odd: i16x16 = simd_shuffle!(
a,
b,
[1, 3, 5, 7, 17, 19, 21, 23, 9, 11, 13, 15, 25, 27, 29, 31]
);
simd_saturating_sub(even, odd).as_m256i()
}
}

/// Returns values from `slice` at offsets determined by `offsets * scale`,
Expand Down Expand Up @@ -3791,10 +3819,6 @@ pub const fn _mm256_extract_epi16<const INDEX: i32>(a: __m256i) -> i32 {

#[allow(improper_ctypes)]
unsafe extern "C" {
#[link_name = "llvm.x86.avx2.phadd.sw"]
fn phaddsw(a: i16x16, b: i16x16) -> i16x16;
#[link_name = "llvm.x86.avx2.phsub.sw"]
fn phsubsw(a: i16x16, b: i16x16) -> i16x16;
#[link_name = "llvm.x86.avx2.pmadd.wd"]
fn pmaddwd(a: i16x16, b: i16x16) -> i32x8;
#[link_name = "llvm.x86.avx2.pmadd.ub.sw"]
Expand Down
22 changes: 14 additions & 8 deletions crates/core_arch/src/x86/ssse3.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -188,7 +188,13 @@ pub const fn _mm_hadd_epi16(a: __m128i, b: __m128i) -> __m128i {
#[cfg_attr(test, assert_instr(phaddsw))]
#[stable(feature = "simd_x86", since = "1.27.0")]
pub fn _mm_hadds_epi16(a: __m128i, b: __m128i) -> __m128i {
unsafe { transmute(phaddsw128(a.as_i16x8(), b.as_i16x8())) }
let a = a.as_i16x8();
let b = b.as_i16x8();
unsafe {
let even: i16x8 = simd_shuffle!(a, b, [0, 2, 4, 6, 8, 10, 12, 14]);
let odd: i16x8 = simd_shuffle!(a, b, [1, 3, 5, 7, 9, 11, 13, 15]);
simd_saturating_add(even, odd).as_m128i()
}
}

/// Horizontally adds the adjacent pairs of values contained in 2 packed
Expand Down Expand Up @@ -240,7 +246,13 @@ pub const fn _mm_hsub_epi16(a: __m128i, b: __m128i) -> __m128i {
#[cfg_attr(test, assert_instr(phsubsw))]
#[stable(feature = "simd_x86", since = "1.27.0")]
pub fn _mm_hsubs_epi16(a: __m128i, b: __m128i) -> __m128i {
unsafe { transmute(phsubsw128(a.as_i16x8(), b.as_i16x8())) }
let a = a.as_i16x8();
let b = b.as_i16x8();
unsafe {
let even: i16x8 = simd_shuffle!(a, b, [0, 2, 4, 6, 8, 10, 12, 14]);
let odd: i16x8 = simd_shuffle!(a, b, [1, 3, 5, 7, 9, 11, 13, 15]);
simd_saturating_sub(even, odd).as_m128i()
}
}

/// Horizontally subtract the adjacent pairs of values contained in 2
Expand Down Expand Up @@ -337,12 +349,6 @@ unsafe extern "C" {
#[link_name = "llvm.x86.ssse3.pshuf.b.128"]
fn pshufb128(a: u8x16, b: u8x16) -> u8x16;

#[link_name = "llvm.x86.ssse3.phadd.sw.128"]
fn phaddsw128(a: i16x8, b: i16x8) -> i16x8;

#[link_name = "llvm.x86.ssse3.phsub.sw.128"]
fn phsubsw128(a: i16x8, b: i16x8) -> i16x8;

#[link_name = "llvm.x86.ssse3.pmadd.ub.sw.128"]
fn pmaddubsw128(a: u8x16, b: i8x16) -> i16x8;

Expand Down