Skip to content

math: close remaining scalar holdout waves #123

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
arduano merged 1 commit into from
Mar 23, 2026
Merged

math: close remaining scalar holdout waves #123

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
9 changes: 6 additions & 3 deletions src/math/f64/core.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,6 @@ const F64_LOG_NORM_MANTISSA: i64 = 0x3FE0_0000_0000_0000u64 as i64;
const F64_EXPONENT_BIAS_ADJUST: i64 = 1022;
const F64_EXP_LN2_HI: f64 = 6.931_471_803_691_238e-1;
const F64_EXP_LN2_LO: f64 = 1.908_214_929_270_587_7e-10;

// DECISION(2026-03-23): KEEP_SIMD_PORTABLE
// Function(s): f64 log2_u35 / exp2_u35 / ln_u35 / exp_u35
// Why kept:
Expand All @@ -21,8 +20,12 @@ const F64_EXP_LN2_LO: f64 = 1.908_214_929_270_587_7e-10;
// DECISION(2026-03-23): KEEP_SCALAR_REFERENCE
// Function(s): f64 sin_u35 / cos_u35 / tan_u35
// Why scalar:
// - the previous portable trig fast path still lagged native scalar on this host
// - the implementation was reverted to scalar-reference while preserving family ownership
// - the final retry of the old portable trig kernel failed the u35 contract around pi boundaries,
// tan-pole neighborhoods, and moderate finite lanes before it could justify a speed keep
// - the refreshed scalar-reference recheck still leaves runtime-selected throughput behind native
// scalar on this host (`sin`: about 17.03 ms vs 15.97 ms, `cos`: about 16.58 ms vs 15.75 ms,
// `tan`: about 20.85 ms vs 20.19 ms)
// - native scalar still remains the honest default while family ownership stays localized here
// Revisit when:
// - a stronger range-reduction strategy or cheaper trig kernel appears

Expand Down
5 changes: 4 additions & 1 deletion src/math/families/binary_misc/mod.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,10 @@ use crate::{Simd, SimdFloat32, SimdFloat64};
// DECISION(2026-03-23): KEEP_SCALAR_REFERENCE
// Function(s): f32 fmod
// Why scalar:
// - local benches still favor native scalar and there is no convincing portable SIMD default yet
// - the final combined-wave recheck still leaves runtime-selected fmod behind native scalar on this
// host (about 8.10 ms vs 7.62 ms)
// - there is still no convincing portable SIMD default that beats scalar without adding quotient-range
// complexity
// - the public trait entry point stays stable while the honest implementation remains scalar-reference
// Revisit when:
// - quotient-range handling becomes cheap enough for a worthwhile portable kernel
Expand Down
6 changes: 4 additions & 2 deletions src/math/families/core.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -4,8 +4,10 @@ use crate::{Simd, SimdFloat32, SimdFloat64};
// DECISION(2026-03-23): KEEP_SCALAR_REFERENCE
// Function(s): f32 ln_u35 / exp_u35
// Why scalar:
// - local benches keep the current runtime-selected path below native scalar
// - retaining the family entry points still preserves structure for later retries
// - the final combined-wave recheck still keeps runtime-selected ln_u35 and exp_u35 below native scalar
// on this host (`ln`: about 2.72 ms vs 2.46 ms, `exp`: about 2.34 ms vs 2.11 ms)
// - these contracts are stricter than the relaxed portable f32 log2_u35 / exp2_u35 pieces they would
// naturally compose from, so there is no cheap honest rescue today
// Revisit when:
// - a better shared f32 log/exp kernel exists

Expand Down
Loading