From e94e9873999afed5948594569f049f20ebddd495 Mon Sep 17 00:00:00 2001 From: Trevor Gross Date: Mon, 10 Feb 2025 12:01:16 +0000 Subject: [PATCH] Eliminate the use of `force_eval!` in `ceil`, `floor`, and `trunc` --- .../libm/src/math/generic/ceil.rs | 91 ++++++++++++++++--- .../libm/src/math/generic/floor.rs | 77 ++++++++++++---- .../libm/src/math/generic/trunc.rs | 89 +++++++++++++++++- 3 files changed, 220 insertions(+), 37 deletions(-) diff --git a/library/compiler-builtins/libm/src/math/generic/ceil.rs b/library/compiler-builtins/libm/src/math/generic/ceil.rs index 971a4d3d8c5f..bf7e1d8e2100 100644 --- a/library/compiler-builtins/libm/src/math/generic/ceil.rs +++ b/library/compiler-builtins/libm/src/math/generic/ceil.rs @@ -7,9 +7,14 @@ //! performance seems to be better (based on icount) and it does not seem to experience rounding //! errors on i386. +use super::super::support::{FpResult, Status}; use super::super::{Float, Int, IntTy, MinInt}; pub fn ceil(x: F) -> F { + ceil_status(x).val +} + +pub fn ceil_status(x: F) -> FpResult { let zero = IntTy::::ZERO; let mut ix = x.to_bits(); @@ -17,20 +22,20 @@ pub fn ceil(x: F) -> F { // If the represented value has no fractional part, no truncation is needed. if e >= F::SIG_BITS as i32 { - return x; + return FpResult::ok(x); } - if e >= 0 { + let status; + let res = if e >= 0 { // |x| >= 1.0 - let m = F::SIG_MASK >> e.unsigned(); if (ix & m) == zero { // Portion to be masked is already zero; no adjustment needed. - return x; + return FpResult::ok(x); } // Otherwise, raise an inexact exception. - force_eval!(x + F::MAX); + status = Status::INEXACT; if x.is_sign_positive() { ix += m; @@ -40,7 +45,11 @@ pub fn ceil(x: F) -> F { F::from_bits(ix) } else { // |x| < 1.0, raise an inexact exception since truncation will happen (unless x == 0). - force_eval!(x + F::MAX); + if ix & F::SIG_MASK == F::Int::ZERO { + status = Status::OK; + } else { + status = Status::INEXACT; + } if x.is_sign_negative() { // -1.0 < x <= -0.0; rounding up goes toward -0.0. @@ -52,18 +61,30 @@ pub fn ceil(x: F) -> F { // +0.0 remains unchanged x } - } + }; + + FpResult::new(res, status) } #[cfg(test)] mod tests { use super::*; + use crate::support::Hexf; /// Test against https://en.cppreference.com/w/cpp/numeric/math/ceil - fn spec_test() { - // Not Asserted: that the current rounding mode has no effect. - for f in [F::ZERO, F::NEG_ZERO, F::INFINITY, F::NEG_INFINITY].iter().copied() { - assert_biteq!(ceil(f), f); + fn spec_test(cases: &[(F, F, Status)]) { + let roundtrip = [F::ZERO, F::ONE, F::NEG_ONE, F::NEG_ZERO, F::INFINITY, F::NEG_INFINITY]; + + for x in roundtrip { + let FpResult { val, status } = ceil_status(x); + assert_biteq!(val, x, "{}", Hexf(x)); + assert_eq!(status, Status::OK, "{}", Hexf(x)); + } + + for &(x, res, res_stat) in cases { + let FpResult { val, status } = ceil_status(x); + assert_biteq!(val, res, "{}", Hexf(x)); + assert_eq!(status, res_stat, "{}", Hexf(x)); } } @@ -72,7 +93,17 @@ mod tests { #[test] #[cfg(f16_enabled)] fn spec_tests_f16() { - spec_test::(); + let cases = [ + (0.1, 1.0, Status::INEXACT), + (-0.1, -0.0, Status::INEXACT), + (0.9, 1.0, Status::INEXACT), + (-0.9, -0.0, Status::INEXACT), + (1.1, 2.0, Status::INEXACT), + (-1.1, -1.0, Status::INEXACT), + (1.9, 2.0, Status::INEXACT), + (-1.9, -1.0, Status::INEXACT), + ]; + spec_test::(&cases); } #[test] @@ -83,7 +114,17 @@ mod tests { #[test] fn spec_tests_f32() { - spec_test::(); + let cases = [ + (0.1, 1.0, Status::INEXACT), + (-0.1, -0.0, Status::INEXACT), + (0.9, 1.0, Status::INEXACT), + (-0.9, -0.0, Status::INEXACT), + (1.1, 2.0, Status::INEXACT), + (-1.1, -1.0, Status::INEXACT), + (1.9, 2.0, Status::INEXACT), + (-1.9, -1.0, Status::INEXACT), + ]; + spec_test::(&cases); } #[test] @@ -94,12 +135,32 @@ mod tests { #[test] fn spec_tests_f64() { - spec_test::(); + let cases = [ + (0.1, 1.0, Status::INEXACT), + (-0.1, -0.0, Status::INEXACT), + (0.9, 1.0, Status::INEXACT), + (-0.9, -0.0, Status::INEXACT), + (1.1, 2.0, Status::INEXACT), + (-1.1, -1.0, Status::INEXACT), + (1.9, 2.0, Status::INEXACT), + (-1.9, -1.0, Status::INEXACT), + ]; + spec_test::(&cases); } #[test] #[cfg(f128_enabled)] fn spec_tests_f128() { - spec_test::(); + let cases = [ + (0.1, 1.0, Status::INEXACT), + (-0.1, -0.0, Status::INEXACT), + (0.9, 1.0, Status::INEXACT), + (-0.9, -0.0, Status::INEXACT), + (1.1, 2.0, Status::INEXACT), + (-1.1, -1.0, Status::INEXACT), + (1.9, 2.0, Status::INEXACT), + (-1.9, -1.0, Status::INEXACT), + ]; + spec_test::(&cases); } } diff --git a/library/compiler-builtins/libm/src/math/generic/floor.rs b/library/compiler-builtins/libm/src/math/generic/floor.rs index 6754c08f870b..7799551644f3 100644 --- a/library/compiler-builtins/libm/src/math/generic/floor.rs +++ b/library/compiler-builtins/libm/src/math/generic/floor.rs @@ -7,9 +7,14 @@ //! performance seems to be better (based on icount) and it does not seem to experience rounding //! errors on i386. +use super::super::support::{FpResult, Status}; use super::super::{Float, Int, IntTy, MinInt}; pub fn floor(x: F) -> F { + floor_status(x).val +} + +pub fn floor_status(x: F) -> FpResult { let zero = IntTy::::ZERO; let mut ix = x.to_bits(); @@ -17,20 +22,20 @@ pub fn floor(x: F) -> F { // If the represented value has no fractional part, no truncation is needed. if e >= F::SIG_BITS as i32 { - return x; + return FpResult::ok(x); } - if e >= 0 { + let status; + let res = if e >= 0 { // |x| >= 1.0 - let m = F::SIG_MASK >> e.unsigned(); if ix & m == zero { // Portion to be masked is already zero; no adjustment needed. - return x; + return FpResult::ok(x); } // Otherwise, raise an inexact exception. - force_eval!(x + F::MAX); + status = Status::INEXACT; if x.is_sign_negative() { ix += m; @@ -39,8 +44,12 @@ pub fn floor(x: F) -> F { ix &= !m; F::from_bits(ix) } else { - // |x| < 1.0, raise an inexact exception since truncation will happen (unless x == 0). - force_eval!(x + F::MAX); + // |x| < 1.0, raise an inexact exception since truncation will happen. + if ix & F::SIG_MASK == F::Int::ZERO { + status = Status::OK; + } else { + status = Status::INEXACT; + } if x.is_sign_positive() { // 0.0 <= x < 1.0; rounding down goes toward +0.0. @@ -52,27 +61,40 @@ pub fn floor(x: F) -> F { // -0.0 remains unchanged x } - } + }; + + FpResult::new(res, status) } #[cfg(test)] mod tests { use super::*; + use crate::support::Hexf; /// Test against https://en.cppreference.com/w/cpp/numeric/math/floor - fn spec_test() { - // Not Asserted: that the current rounding mode has no effect. - for f in [F::ZERO, F::NEG_ZERO, F::INFINITY, F::NEG_INFINITY].iter().copied() { - assert_biteq!(floor(f), f); + fn spec_test(cases: &[(F, F, Status)]) { + let roundtrip = [F::ZERO, F::ONE, F::NEG_ONE, F::NEG_ZERO, F::INFINITY, F::NEG_INFINITY]; + + for x in roundtrip { + let FpResult { val, status } = floor_status(x); + assert_biteq!(val, x, "{}", Hexf(x)); + assert_eq!(status, Status::OK, "{}", Hexf(x)); + } + + for &(x, res, res_stat) in cases { + let FpResult { val, status } = floor_status(x); + assert_biteq!(val, res, "{}", Hexf(x)); + assert_eq!(status, res_stat, "{}", Hexf(x)); } } - /* Skipping f16 / f128 "sanity_check"s due to rejected literal lexing at MSRV */ + /* Skipping f16 / f128 "sanity_check"s and spec cases due to rejected literal lexing at MSRV */ #[test] #[cfg(f16_enabled)] fn spec_tests_f16() { - spec_test::(); + let cases = []; + spec_test::(&cases); } #[test] @@ -84,7 +106,17 @@ mod tests { #[test] fn spec_tests_f32() { - spec_test::(); + let cases = [ + (0.1, 0.0, Status::INEXACT), + (-0.1, -1.0, Status::INEXACT), + (0.9, 0.0, Status::INEXACT), + (-0.9, -1.0, Status::INEXACT), + (1.1, 1.0, Status::INEXACT), + (-1.1, -2.0, Status::INEXACT), + (1.9, 1.0, Status::INEXACT), + (-1.9, -2.0, Status::INEXACT), + ]; + spec_test::(&cases); } #[test] @@ -95,12 +127,23 @@ mod tests { #[test] fn spec_tests_f64() { - spec_test::(); + let cases = [ + (0.1, 0.0, Status::INEXACT), + (-0.1, -1.0, Status::INEXACT), + (0.9, 0.0, Status::INEXACT), + (-0.9, -1.0, Status::INEXACT), + (1.1, 1.0, Status::INEXACT), + (-1.1, -2.0, Status::INEXACT), + (1.9, 1.0, Status::INEXACT), + (-1.9, -2.0, Status::INEXACT), + ]; + spec_test::(&cases); } #[test] #[cfg(f128_enabled)] fn spec_tests_f128() { - spec_test::(); + let cases = []; + spec_test::(&cases); } } diff --git a/library/compiler-builtins/libm/src/math/generic/trunc.rs b/library/compiler-builtins/libm/src/math/generic/trunc.rs index ca5f1bdd6276..0fb3fa5ad3b8 100644 --- a/library/compiler-builtins/libm/src/math/generic/trunc.rs +++ b/library/compiler-builtins/libm/src/math/generic/trunc.rs @@ -1,15 +1,20 @@ /* SPDX-License-Identifier: MIT * origin: musl src/math/trunc.c */ +use super::super::support::{FpResult, Status}; use super::super::{Float, Int, IntTy, MinInt}; pub fn trunc(x: F) -> F { + trunc_status(x).val +} + +pub fn trunc_status(x: F) -> FpResult { let mut xi: F::Int = x.to_bits(); let e: i32 = x.exp_unbiased(); // C1: The represented value has no fractional part, so no truncation is needed if e >= F::SIG_BITS as i32 { - return x; + return FpResult::ok(x); } let mask = if e < 0 { @@ -23,22 +28,68 @@ pub fn trunc(x: F) -> F { // C4: If the to-be-masked-out portion is already zero, we have an exact result if (xi & !mask) == IntTy::::ZERO { - return x; + return FpResult::ok(x); } // C5: Otherwise the result is inexact and we will truncate. Raise `FE_INEXACT`, mask the // result, and return. - force_eval!(x + F::MAX); + + let status = if xi & F::SIG_MASK == F::Int::ZERO { Status::OK } else { Status::INEXACT }; xi &= mask; - F::from_bits(xi) + FpResult::new(F::from_bits(xi), status) } #[cfg(test)] mod tests { use super::*; + use crate::support::Hexf; + + fn spec_test(cases: &[(F, F, Status)]) { + let roundtrip = [F::ZERO, F::ONE, F::NEG_ONE, F::NEG_ZERO, F::INFINITY, F::NEG_INFINITY]; + + for x in roundtrip { + let FpResult { val, status } = trunc_status(x); + assert_biteq!(val, x, "{}", Hexf(x)); + assert_eq!(status, Status::OK, "{}", Hexf(x)); + } + + for &(x, res, res_stat) in cases { + let FpResult { val, status } = trunc_status(x); + assert_biteq!(val, res, "{}", Hexf(x)); + assert_eq!(status, res_stat, "{}", Hexf(x)); + } + } + + /* Skipping f16 / f128 "sanity_check"s and spec cases due to rejected literal lexing at MSRV */ #[test] - fn sanity_check() { + #[cfg(f16_enabled)] + fn spec_tests_f16() { + let cases = []; + spec_test::(&cases); + } + + #[test] + fn sanity_check_f32() { + assert_eq!(trunc(0.5f32), 0.0); + assert_eq!(trunc(1.1f32), 1.0); + assert_eq!(trunc(2.9f32), 2.0); + } + + #[test] + fn spec_tests_f32() { + let cases = [ + (0.1, 0.0, Status::INEXACT), + (-0.1, -0.0, Status::INEXACT), + (0.9, 0.0, Status::INEXACT), + (-0.9, -0.0, Status::INEXACT), + (1.1, 1.0, Status::INEXACT), + (-1.1, -1.0, Status::INEXACT), + (1.9, 1.0, Status::INEXACT), + (-1.9, -1.0, Status::INEXACT), + ]; + spec_test::(&cases); + assert_biteq!(trunc(1.1f32), 1.0); assert_biteq!(trunc(1.1f64), 1.0); @@ -54,4 +105,32 @@ mod tests { assert_biteq!(trunc(hf32!("-0x1p-1")), -0.0); assert_biteq!(trunc(hf64!("-0x1p-1")), -0.0); } + + #[test] + fn sanity_check_f64() { + assert_eq!(trunc(1.1f64), 1.0); + assert_eq!(trunc(2.9f64), 2.0); + } + + #[test] + fn spec_tests_f64() { + let cases = [ + (0.1, 0.0, Status::INEXACT), + (-0.1, -0.0, Status::INEXACT), + (0.9, 0.0, Status::INEXACT), + (-0.9, -0.0, Status::INEXACT), + (1.1, 1.0, Status::INEXACT), + (-1.1, -1.0, Status::INEXACT), + (1.9, 1.0, Status::INEXACT), + (-1.9, -1.0, Status::INEXACT), + ]; + spec_test::(&cases); + } + + #[test] + #[cfg(f128_enabled)] + fn spec_tests_f128() { + let cases = []; + spec_test::(&cases); + } }