diff --git a/library/compiler-builtins/libm/etc/function-definitions.json b/library/compiler-builtins/libm/etc/function-definitions.json index eef176fb57c8..86b0882927cc 100644 --- a/library/compiler-builtins/libm/etc/function-definitions.json +++ b/library/compiler-builtins/libm/etc/function-definitions.json @@ -654,6 +654,7 @@ "src/libm_helper.rs", "src/math/arch/aarch64.rs", "src/math/arch/wasm32.rs", + "src/math/generic/rint.rs", "src/math/rint.rs" ], "type": "f64" @@ -662,6 +663,7 @@ "sources": [ "src/math/arch/aarch64.rs", "src/math/arch/wasm32.rs", + "src/math/generic/rint.rs", "src/math/rintf.rs" ], "type": "f32" diff --git a/library/compiler-builtins/libm/src/math/generic/mod.rs b/library/compiler-builtins/libm/src/math/generic/mod.rs index b08a77d5d649..d3df650e1a5b 100644 --- a/library/compiler-builtins/libm/src/math/generic/mod.rs +++ b/library/compiler-builtins/libm/src/math/generic/mod.rs @@ -3,6 +3,7 @@ mod copysign; mod fabs; mod fdim; mod floor; +mod rint; mod sqrt; mod trunc; @@ -11,5 +12,6 @@ pub use copysign::copysign; pub use fabs::fabs; pub use fdim::fdim; pub use floor::floor; +pub use rint::rint; pub use sqrt::sqrt; pub use trunc::trunc; diff --git a/library/compiler-builtins/libm/src/math/generic/rint.rs b/library/compiler-builtins/libm/src/math/generic/rint.rs new file mode 100644 index 000000000000..80ba1faac311 --- /dev/null +++ b/library/compiler-builtins/libm/src/math/generic/rint.rs @@ -0,0 +1,72 @@ +/* SPDX-License-Identifier: MIT */ +/* origin: musl src/math/rint.c */ + +use super::super::Float; + +pub fn rint(x: F) -> F { + let toint = F::ONE / F::EPSILON; + let e = x.exp(); + let positive = x.is_sign_positive(); + + // On i386 `force_eval!` must be used to force rounding via storage to memory. Otherwise, + // the excess precission from x87 would cause an incorrect final result. + let use_force = cfg!(x86_no_sse) && F::BITS == 32 || F::BITS == 64; + + if e >= F::EXP_BIAS + F::SIG_BITS { + // No fractional part; exact result can be returned. + x + } else { + // Apply a net-zero adjustment that nudges `y` in the direction of the rounding mode. + let y = if positive { + let tmp = if use_force { force_eval!(x) } else { x } + toint; + (if use_force { force_eval!(tmp) } else { tmp } - toint) + } else { + let tmp = if use_force { force_eval!(x) } else { x } - toint; + (if use_force { force_eval!(tmp) } else { tmp } + toint) + }; + + if y == F::ZERO { + // A zero result takes the sign of the input. + if positive { F::ZERO } else { F::NEG_ZERO } + } else { + y + } + } +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn zeroes_f32() { + assert_biteq!(rint(0.0_f32), 0.0_f32); + assert_biteq!(rint(-0.0_f32), -0.0_f32); + } + + #[test] + fn sanity_check_f32() { + assert_biteq!(rint(-1.0_f32), -1.0); + assert_biteq!(rint(2.8_f32), 3.0); + assert_biteq!(rint(-0.5_f32), -0.0); + assert_biteq!(rint(0.5_f32), 0.0); + assert_biteq!(rint(-1.5_f32), -2.0); + assert_biteq!(rint(1.5_f32), 2.0); + } + + #[test] + fn zeroes_f64() { + assert_biteq!(rint(0.0_f64), 0.0_f64); + assert_biteq!(rint(-0.0_f64), -0.0_f64); + } + + #[test] + fn sanity_check_f64() { + assert_biteq!(rint(-1.0_f64), -1.0); + assert_biteq!(rint(2.8_f64), 3.0); + assert_biteq!(rint(-0.5_f64), -0.0); + assert_biteq!(rint(0.5_f64), 0.0); + assert_biteq!(rint(-1.5_f64), -2.0); + assert_biteq!(rint(1.5_f64), 2.0); + } +} diff --git a/library/compiler-builtins/libm/src/math/rint.rs b/library/compiler-builtins/libm/src/math/rint.rs index c9ea6402ec73..592583aa5e54 100644 --- a/library/compiler-builtins/libm/src/math/rint.rs +++ b/library/compiler-builtins/libm/src/math/rint.rs @@ -9,51 +9,5 @@ pub fn rint(x: f64) -> f64 { args: x, } - let one_over_e = 1.0 / f64::EPSILON; - let as_u64: u64 = x.to_bits(); - let exponent: u64 = (as_u64 >> 52) & 0x7ff; - let is_positive = (as_u64 >> 63) == 0; - if exponent >= 0x3ff + 52 { - x - } else { - let ans = if is_positive { - #[cfg(all(target_arch = "x86", not(target_feature = "sse2")))] - let x = force_eval!(x); - let xplusoneovere = x + one_over_e; - #[cfg(all(target_arch = "x86", not(target_feature = "sse2")))] - let xplusoneovere = force_eval!(xplusoneovere); - xplusoneovere - one_over_e - } else { - #[cfg(all(target_arch = "x86", not(target_feature = "sse2")))] - let x = force_eval!(x); - let xminusoneovere = x - one_over_e; - #[cfg(all(target_arch = "x86", not(target_feature = "sse2")))] - let xminusoneovere = force_eval!(xminusoneovere); - xminusoneovere + one_over_e - }; - - if ans == 0.0 { if is_positive { 0.0 } else { -0.0 } } else { ans } - } -} - -// PowerPC tests are failing on LLVM 13: https://github.com/rust-lang/rust/issues/88520 -#[cfg(not(target_arch = "powerpc64"))] -#[cfg(test)] -mod tests { - use super::rint; - - #[test] - fn negative_zero() { - assert_eq!(rint(-0.0_f64).to_bits(), (-0.0_f64).to_bits()); - } - - #[test] - fn sanity_check() { - assert_eq!(rint(-1.0), -1.0); - assert_eq!(rint(2.8), 3.0); - assert_eq!(rint(-0.5), -0.0); - assert_eq!(rint(0.5), 0.0); - assert_eq!(rint(-1.5), -2.0); - assert_eq!(rint(1.5), 2.0); - } + super::generic::rint(x) } diff --git a/library/compiler-builtins/libm/src/math/rintf.rs b/library/compiler-builtins/libm/src/math/rintf.rs index 33b5b3ddebf6..56666df11542 100644 --- a/library/compiler-builtins/libm/src/math/rintf.rs +++ b/library/compiler-builtins/libm/src/math/rintf.rs @@ -9,51 +9,5 @@ pub fn rintf(x: f32) -> f32 { args: x, } - let one_over_e = 1.0 / f32::EPSILON; - let as_u32: u32 = x.to_bits(); - let exponent: u32 = (as_u32 >> 23) & 0xff; - let is_positive = (as_u32 >> 31) == 0; - if exponent >= 0x7f + 23 { - x - } else { - let ans = if is_positive { - #[cfg(all(target_arch = "x86", not(target_feature = "sse2")))] - let x = force_eval!(x); - let xplusoneovere = x + one_over_e; - #[cfg(all(target_arch = "x86", not(target_feature = "sse2")))] - let xplusoneovere = force_eval!(xplusoneovere); - xplusoneovere - one_over_e - } else { - #[cfg(all(target_arch = "x86", not(target_feature = "sse2")))] - let x = force_eval!(x); - let xminusoneovere = x - one_over_e; - #[cfg(all(target_arch = "x86", not(target_feature = "sse2")))] - let xminusoneovere = force_eval!(xminusoneovere); - xminusoneovere + one_over_e - }; - - if ans == 0.0 { if is_positive { 0.0 } else { -0.0 } } else { ans } - } -} - -// PowerPC tests are failing on LLVM 13: https://github.com/rust-lang/rust/issues/88520 -#[cfg(not(target_arch = "powerpc64"))] -#[cfg(test)] -mod tests { - use super::rintf; - - #[test] - fn negative_zero() { - assert_eq!(rintf(-0.0_f32).to_bits(), (-0.0_f32).to_bits()); - } - - #[test] - fn sanity_check() { - assert_eq!(rintf(-1.0), -1.0); - assert_eq!(rintf(2.8), 3.0); - assert_eq!(rintf(-0.5), -0.0); - assert_eq!(rintf(0.5), 0.0); - assert_eq!(rintf(-1.5), -2.0); - assert_eq!(rintf(1.5), 2.0); - } + super::generic::rint(x) }