From 37480bc9e6fef8b2a455b07742a1ee4f364f972c Mon Sep 17 00:00:00 2001 From: Ralf Jung Date: Mon, 21 Jul 2025 11:20:38 +0200 Subject: [PATCH] coretests/num: use ldexp instead of hard-coding a power of 2 --- library/coretests/tests/num/dec2flt/float.rs | 11 +++--- .../coretests/tests/num/flt2dec/estimator.rs | 4 ++- library/coretests/tests/num/flt2dec/mod.rs | 34 +++++-------------- library/coretests/tests/num/mod.rs | 21 ++++++++++++ 4 files changed, 38 insertions(+), 32 deletions(-) diff --git a/library/coretests/tests/num/dec2flt/float.rs b/library/coretests/tests/num/dec2flt/float.rs index 193d5887749ab..8bf4094ced72f 100644 --- a/library/coretests/tests/num/dec2flt/float.rs +++ b/library/coretests/tests/num/dec2flt/float.rs @@ -1,13 +1,14 @@ use core::num::dec2flt::float::RawFloat; +use crate::num::{ldexp_f32, ldexp_f64}; + // FIXME(f16_f128): enable on all targets once possible. #[test] #[cfg(target_has_reliable_f16)] fn test_f16_integer_decode() { assert_eq!(3.14159265359f16.integer_decode(), (1608, -9, 1)); assert_eq!((-8573.5918555f16).integer_decode(), (1072, 3, -1)); - #[cfg(not(miri))] // miri doesn't have powf16 - assert_eq!(2f16.powf(14.0).integer_decode(), (1 << 10, 4, 1)); + assert_eq!(crate::num::ldexp_f16(1.0, 14).integer_decode(), (1 << 10, 4, 1)); assert_eq!(0f16.integer_decode(), (0, -25, 1)); assert_eq!((-0f16).integer_decode(), (0, -25, -1)); assert_eq!(f16::INFINITY.integer_decode(), (1 << 10, 6, 1)); @@ -23,8 +24,7 @@ fn test_f16_integer_decode() { fn test_f32_integer_decode() { assert_eq!(3.14159265359f32.integer_decode(), (13176795, -22, 1)); assert_eq!((-8573.5918555f32).integer_decode(), (8779358, -10, -1)); - // Set 2^100 directly instead of using powf, because it doesn't guarantee precision - assert_eq!(1.2676506e30_f32.integer_decode(), (8388608, 77, 1)); + assert_eq!(ldexp_f32(1.0, 100).integer_decode(), (8388608, 77, 1)); assert_eq!(0f32.integer_decode(), (0, -150, 1)); assert_eq!((-0f32).integer_decode(), (0, -150, -1)); assert_eq!(f32::INFINITY.integer_decode(), (8388608, 105, 1)); @@ -40,8 +40,7 @@ fn test_f32_integer_decode() { fn test_f64_integer_decode() { assert_eq!(3.14159265359f64.integer_decode(), (7074237752028906, -51, 1)); assert_eq!((-8573.5918555f64).integer_decode(), (4713381968463931, -39, -1)); - // Set 2^100 directly instead of using powf, because it doesn't guarantee precision - assert_eq!(1.2676506002282294e30_f64.integer_decode(), (4503599627370496, 48, 1)); + assert_eq!(ldexp_f64(1.0, 100).integer_decode(), (4503599627370496, 48, 1)); assert_eq!(0f64.integer_decode(), (0, -1075, 1)); assert_eq!((-0f64).integer_decode(), (0, -1075, -1)); assert_eq!(f64::INFINITY.integer_decode(), (4503599627370496, 972, 1)); diff --git a/library/coretests/tests/num/flt2dec/estimator.rs b/library/coretests/tests/num/flt2dec/estimator.rs index da203b5f3620e..f53282611f686 100644 --- a/library/coretests/tests/num/flt2dec/estimator.rs +++ b/library/coretests/tests/num/flt2dec/estimator.rs @@ -1,5 +1,7 @@ use core::num::flt2dec::estimator::*; +use crate::num::ldexp_f64; + #[test] fn test_estimate_scaling_factor() { macro_rules! assert_almost_eq { @@ -56,7 +58,7 @@ fn test_estimate_scaling_factor() { let step = if cfg!(miri) { 37 } else { 1 }; for i in (-1074..972).step_by(step) { - let expected = super::ldexp_f64(1.0, i).log10().ceil(); + let expected = ldexp_f64(1.0, i).log10().ceil(); assert_almost_eq!(estimate_scaling_factor(1, i as i16), expected as i16); } } diff --git a/library/coretests/tests/num/flt2dec/mod.rs b/library/coretests/tests/num/flt2dec/mod.rs index ce36db33d05f3..4e73bd1f12ee9 100644 --- a/library/coretests/tests/num/flt2dec/mod.rs +++ b/library/coretests/tests/num/flt2dec/mod.rs @@ -6,6 +6,8 @@ use core::num::fmt::{Formatted, Part}; use std::mem::MaybeUninit; use std::{fmt, str}; +use crate::num::{ldexp_f32, ldexp_f64}; + mod estimator; mod strategy { mod dragon; @@ -75,24 +77,6 @@ macro_rules! try_fixed { }) } -#[cfg(target_has_reliable_f16)] -fn ldexp_f16(a: f16, b: i32) -> f16 { - ldexp_f64(a as f64, b) as f16 -} - -fn ldexp_f32(a: f32, b: i32) -> f32 { - ldexp_f64(a as f64, b) as f32 -} - -fn ldexp_f64(a: f64, b: i32) -> f64 { - unsafe extern "C" { - fn ldexp(x: f64, n: i32) -> f64; - } - // SAFETY: assuming a correct `ldexp` has been supplied, the given arguments cannot possibly - // cause undefined behavior - unsafe { ldexp(a, b) } -} - fn check_exact(mut f: F, v: T, vstr: &str, expected: &[u8], expectedk: i16) where T: DecodableFloat, @@ -268,7 +252,7 @@ where // 10^2 * 0.31984375 // 10^2 * 0.32 // 10^2 * 0.3203125 - check_shortest!(f(ldexp_f16(1.0, 5)) => b"32", 2); + check_shortest!(f(crate::num::ldexp_f16(1.0, 5)) => b"32", 2); // 10^5 * 0.65472 // 10^5 * 0.65504 @@ -283,7 +267,7 @@ where // 10^-9 * 0 // 10^-9 * 0.59604644775390625 // 10^-8 * 0.11920928955078125 - let minf16 = ldexp_f16(1.0, -24); + let minf16 = crate::num::ldexp_f16(1.0, -24); check_shortest!(f(minf16) => b"6", -7); } @@ -292,7 +276,7 @@ pub fn f16_exact_sanity_test(mut f: F) where F: for<'a> FnMut(&Decoded, &'a mut [MaybeUninit], i16) -> (&'a [u8], i16), { - let minf16 = ldexp_f16(1.0, -24); + let minf16 = crate::num::ldexp_f16(1.0, -24); check_exact!(f(0.1f16) => b"999755859375 ", -1); check_exact!(f(0.5f16) => b"5 ", 0); @@ -642,7 +626,7 @@ where assert_eq!(to_string(f, f16::MAX, Minus, 1), "65500.0"); assert_eq!(to_string(f, f16::MAX, Minus, 8), "65500.00000000"); - let minf16 = ldexp_f16(1.0, -24); + let minf16 = crate::num::ldexp_f16(1.0, -24); assert_eq!(to_string(f, minf16, Minus, 0), "0.00000006"); assert_eq!(to_string(f, minf16, Minus, 8), "0.00000006"); assert_eq!(to_string(f, minf16, Minus, 9), "0.000000060"); @@ -766,7 +750,7 @@ where assert_eq!(to_string(f, f16::MAX, Minus, (-4, 4), false), "6.55e4"); assert_eq!(to_string(f, f16::MAX, Minus, (-5, 5), false), "65500"); - let minf16 = ldexp_f16(1.0, -24); + let minf16 = crate::num::ldexp_f16(1.0, -24); assert_eq!(to_string(f, minf16, Minus, (-2, 2), false), "6e-8"); assert_eq!(to_string(f, minf16, Minus, (-7, 7), false), "6e-8"); assert_eq!(to_string(f, minf16, Minus, (-8, 8), false), "0.00000006"); @@ -922,7 +906,7 @@ where assert_eq!(to_string(f, f16::MAX, Minus, 6, false), "6.55040e4"); assert_eq!(to_string(f, f16::MAX, Minus, 16, false), "6.550400000000000e4"); - let minf16 = ldexp_f16(1.0, -24); + let minf16 = crate::num::ldexp_f16(1.0, -24); assert_eq!(to_string(f, minf16, Minus, 1, false), "6e-8"); assert_eq!(to_string(f, minf16, Minus, 2, false), "6.0e-8"); assert_eq!(to_string(f, minf16, Minus, 4, false), "5.960e-8"); @@ -1229,7 +1213,7 @@ where #[cfg(target_has_reliable_f16)] { - let minf16 = ldexp_f16(1.0, -24); + let minf16 = crate::num::ldexp_f16(1.0, -24); assert_eq!(to_string(f, minf16, Minus, 0), "0"); assert_eq!(to_string(f, minf16, Minus, 1), "0.0"); assert_eq!(to_string(f, minf16, Minus, 2), "0.00"); diff --git a/library/coretests/tests/num/mod.rs b/library/coretests/tests/num/mod.rs index f340926292c88..54e54f734f647 100644 --- a/library/coretests/tests/num/mod.rs +++ b/library/coretests/tests/num/mod.rs @@ -54,6 +54,27 @@ macro_rules! assume_usize_width { } } +/// Return `a * 2^b`. +#[cfg(target_has_reliable_f16)] +fn ldexp_f16(a: f16, b: i32) -> f16 { + ldexp_f64(a as f64, b) as f16 +} + +/// Return `a * 2^b`. +fn ldexp_f32(a: f32, b: i32) -> f32 { + ldexp_f64(a as f64, b) as f32 +} + +/// Return `a * 2^b`. +fn ldexp_f64(a: f64, b: i32) -> f64 { + unsafe extern "C" { + fn ldexp(x: f64, n: i32) -> f64; + } + // SAFETY: assuming a correct `ldexp` has been supplied, the given arguments cannot possibly + // cause undefined behavior + unsafe { ldexp(a, b) } +} + /// Helper function for testing numeric operations pub fn test_num(ten: T, two: T) where