From 4f4187a80a27952ac9e77547b68570705dc710d7 Mon Sep 17 00:00:00 2001
From: Mathis Randl <mathis.randl@epfl.ch>
Date: Wed, 20 Nov 2024 13:20:43 +0100
Subject: [PATCH] simd cleanup + specified the behavior wrt non-simd impl
---
src/numerics/f32vector.rs | 64 +++++++++++++++++++++++++++++++--------
1 file changed, 52 insertions(+), 12 deletions(-)
diff --git a/src/numerics/f32vector.rs b/src/numerics/f32vector.rs
index bae4b75..a1fd06b 100644
--- a/src/numerics/f32vector.rs
+++ b/src/numerics/f32vector.rs
@@ -22,19 +22,23 @@ impl<'a> F32Vector<'a> {
/// Panics in debug mode if the two vectors have different lengths.
/// In release mode, the longest vector will be silently truncated.
#[inline]
- pub fn l2_dist_squared(&self, other: &F32Vector<'a>) -> f32 {
- let mut sum = f32x8::splat(0.0);
- for (chka, chkb) in self
- .array
- .chunks_exact(f32x8::LEN)
- .zip(other.array.chunks_exact(f32x8::LEN))
- {
- let simd_a = f32x8::from_slice(chka);
- let simd_b = f32x8::from_slice(chkb);
- let diff = simd_a - simd_b;
- sum += diff * diff;
+ pub fn l2_dist_squared(&self, othr: &F32Vector<'a>) -> f32 {
+ debug_assert!(self.len() == othr.len());
+ debug_assert!(self.len() % f32x8::LEN == 0);
+
+ let mut intermediate_sum_x8: f32x8 = f32x8::splat(0.0);
+
+ let self_chunks = self.array.chunks_exact(f32x8::LEN);
+ let othr_chunks = othr.array.chunks_exact(f32x8::LEN);
+
+ for (slice_self, slice_othr) in self_chunks.zip(othr_chunks) {
+ let f32x8_slf = f32x8::from_slice(slice_self);
+ let f32x8_oth = f32x8::from_slice(slice_othr);
+ let diff = f32x8_slf - f32x8_oth;
+ intermediate_sum_x8 += diff * diff;
}
- sum.reduce_sum()
+
+ intermediate_sum_x8.reduce_sum() // 8-to-1 sum
}
/// # Usage
@@ -71,6 +75,17 @@ mod tests {
suspect.is_finite() && suspect >= 0.0
}
+ fn l2_spec<'a>(v1: F32Vector<'a>, v2: F32Vector<'a>) -> f32 {
+ v1.array
+ .iter()
+ .zip(v2.array.iter())
+ .map(|(&x, &y)| {
+ let diff = x - y;
+ diff * diff
+ })
+ .sum()
+ }
+
#[test]
fn self_sim_is_zero() {
fn qc_self_sim_is_zero(totest: Vec<f32>) -> TestResult {
@@ -118,4 +133,29 @@ mod tests {
qc_squared_invariant as fn(Vec<f32>, Vec<f32>, Vec<f32>, Vec<f32>) -> TestResult,
);
}
+
+ #[test]
+ fn simd_matches_spec() {
+ fn qc_simd_matches_spec(u: Vec<f32>, v: Vec<f32>) -> TestResult {
+ let min_length = u.len().min(v.len()) / 8 * 8;
+ let (u_f32v, v_f32v) = (
+ F32Vector::from(&u[0..min_length]),
+ F32Vector::from(&v[0..min_length]),
+ );
+ let simd = u_f32v.l2_dist_squared(&v_f32v);
+ let spec = l2_spec(u_f32v, v_f32v);
+
+ if simd.is_infinite() {
+ TestResult::from_bool(spec.is_infinite())
+ } else if simd.is_nan() {
+ TestResult::from_bool(spec.is_nan())
+ } else {
+ TestResult::from_bool(close(simd, spec))
+ }
+ }
+
+ QuickCheck::new()
+ .tests(10_000)
+ .quickcheck(qc_simd_matches_spec as fn(Vec<f32>, Vec<f32>) -> TestResult);
+ }
}
--
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