diff options
Diffstat (limited to 'library/compiler-builtins/libm-test/src/precision.rs')
| -rw-r--r-- | library/compiler-builtins/libm-test/src/precision.rs | 573 |
1 files changed, 573 insertions, 0 deletions
diff --git a/library/compiler-builtins/libm-test/src/precision.rs b/library/compiler-builtins/libm-test/src/precision.rs new file mode 100644 index 00000000000..f5fb5f6707b --- /dev/null +++ b/library/compiler-builtins/libm-test/src/precision.rs @@ -0,0 +1,573 @@ +//! Configuration for skipping or changing the result for individual test cases (inputs) rather +//! than ignoring entire tests. + +use core::f32; + +use CheckBasis::{Mpfr, Musl}; +use libm::support::CastFrom; +use {BaseName as Bn, Identifier as Id}; + +use crate::{BaseName, CheckBasis, CheckCtx, Float, Identifier, Int, TestResult}; + +/// Type implementing [`IgnoreCase`]. +pub struct SpecialCase; + +/// ULP allowed to differ from the results returned by a test basis. +#[allow(clippy::single_match)] +pub fn default_ulp(ctx: &CheckCtx) -> u32 { + // ULP compared to the infinite (MPFR) result. + let mut ulp = match ctx.base_name { + // Operations that require exact results. This list should correlate with what we + // have documented at <https://doc.rust-lang.org/std/primitive.f32.html>. + Bn::Ceil + | Bn::Copysign + | Bn::Fabs + | Bn::Fdim + | Bn::Floor + | Bn::Fma + | Bn::Fmax + | Bn::Fmaximum + | Bn::FmaximumNum + | Bn::Fmin + | Bn::Fminimum + | Bn::FminimumNum + | Bn::Fmod + | Bn::Frexp + | Bn::Ilogb + | Bn::Ldexp + | Bn::Modf + | Bn::Nextafter + | Bn::Remainder + | Bn::Remquo + | Bn::Rint + | Bn::Round + | Bn::Roundeven + | Bn::Scalbn + | Bn::Sqrt + | Bn::Trunc => 0, + + // Operations that aren't required to be exact, but our implementations are. + Bn::Cbrt => 0, + + // Bessel functions have large inaccuracies. + Bn::J0 | Bn::J1 | Bn::Y0 | Bn::Y1 | Bn::Jn | Bn::Yn => 8_000_000, + + // For all other operations, specify our implementation's worst case precision. + Bn::Acos => 1, + Bn::Acosh => 4, + Bn::Asin => 1, + Bn::Asinh => 2, + Bn::Atan => 1, + Bn::Atan2 => 2, + Bn::Atanh => 2, + Bn::Cos => 1, + Bn::Cosh => 1, + Bn::Erf => 1, + Bn::Erfc => 4, + Bn::Exp => 1, + Bn::Exp10 => 6, + Bn::Exp2 => 1, + Bn::Expm1 => 1, + Bn::Hypot => 1, + Bn::Lgamma | Bn::LgammaR => 16, + Bn::Log => 1, + Bn::Log10 => 1, + Bn::Log1p => 1, + Bn::Log2 => 1, + Bn::Pow => 1, + Bn::Sin => 1, + Bn::Sincos => 1, + Bn::Sinh => 2, + Bn::Tan => 1, + Bn::Tanh => 2, + // tgammaf has higher accuracy than tgamma. + Bn::Tgamma if ctx.fn_ident != Id::Tgamma => 1, + Bn::Tgamma => 20, + }; + + // There are some cases where musl's approximation is less accurate than ours. For these + // cases, increase the ULP. + if ctx.basis == Musl { + match ctx.base_name { + Bn::Cosh => ulp = 2, + Bn::Exp10 if usize::BITS < 64 => ulp = 4, + Bn::Lgamma | Bn::LgammaR => ulp = 400, + Bn::Tanh => ulp = 4, + _ => (), + } + + match ctx.fn_ident { + Id::Cbrt => ulp = 2, + // FIXME(#401): musl has an incorrect result here. + Id::Fdim => ulp = 2, + Id::Sincosf => ulp = 500, + Id::Tgamma => ulp = 20, + _ => (), + } + } + + if cfg!(target_arch = "x86") { + match ctx.fn_ident { + // Input `fma(0.999999999999999, 1.0000000000000013, 0.0) = 1.0000000000000002` is + // incorrect on i586 and i686. + Id::Fma => ulp = 1, + _ => (), + } + } + + // In some cases, our implementation is less accurate than musl on i586. + if cfg!(x86_no_sse) { + match ctx.fn_ident { + // FIXME(#401): these need to be correctly rounded but are not. + Id::Fmaf => ulp = 1, + Id::Fdim => ulp = 1, + Id::Round => ulp = 1, + + Id::Asinh => ulp = 3, + Id::Asinhf => ulp = 3, + Id::Cbrt => ulp = 1, + Id::Exp10 | Id::Exp10f => ulp = 1_000_000, + Id::Exp2 | Id::Exp2f => ulp = 10_000_000, + Id::Log1p | Id::Log1pf => ulp = 2, + Id::Tan => ulp = 2, + _ => (), + } + } + + ulp +} + +/// Result of checking for possible overrides. +#[derive(Debug, Default)] +pub enum CheckAction { + /// The check should pass. Default case. + #[default] + AssertSuccess, + + /// Override the ULP for this check. + AssertWithUlp(u32), + + /// Failure is expected, ensure this is the case (xfail). Takes a contxt string to help trace + /// back exactly why we expect this to fail. + AssertFailure(&'static str), + + /// The override somehow validated the result, here it is. + Custom(TestResult), + + /// Disregard the output. + Skip, +} + +/// Don't run further validation on this test case. +const SKIP: CheckAction = CheckAction::Skip; + +/// Return this to skip checks on a test that currently fails but shouldn't. Takes a description +/// of context. +const XFAIL: fn(&'static str) -> CheckAction = CheckAction::AssertFailure; + +/// Indicates that we expect a test to fail but we aren't asserting that it does (e.g. some results +/// within a range do actually pass). +/// +/// Same as `SKIP`, just indicates we have something to eventually fix. +const XFAIL_NOCHECK: CheckAction = CheckAction::Skip; + +/// By default, all tests should pass. +const DEFAULT: CheckAction = CheckAction::AssertSuccess; + +/// Allow overriding the outputs of specific test cases. +/// +/// There are some cases where we want to xfail specific cases or handle certain inputs +/// differently than the rest of calls to `validate`. This provides a hook to do that. +/// +/// If `None` is returned, checks will proceed as usual. If `Some(result)` is returned, checks +/// are skipped and the provided result is returned instead. +/// +/// This gets implemented once per input type, then the functions provide further filtering +/// based on function name and values. +/// +/// `ulp` can also be set to adjust the ULP for that specific test, even if `None` is still +/// returned. +pub trait MaybeOverride<Input> { + fn check_float<F: Float>( + _input: Input, + _actual: F, + _expected: F, + _ctx: &CheckCtx, + ) -> CheckAction { + DEFAULT + } + + fn check_int<I: Int>(_input: Input, _actual: I, _expected: I, _ctx: &CheckCtx) -> CheckAction { + DEFAULT + } +} + +#[cfg(f16_enabled)] +impl MaybeOverride<(f16,)> for SpecialCase {} + +impl MaybeOverride<(f32,)> for SpecialCase { + fn check_float<F: Float>(input: (f32,), actual: F, expected: F, ctx: &CheckCtx) -> CheckAction { + if ctx.base_name == BaseName::Expm1 + && !input.0.is_infinite() + && input.0 > 80.0 + && actual.is_infinite() + && !expected.is_infinite() + { + // we return infinity but the number is representable + if ctx.basis == CheckBasis::Musl { + return XFAIL_NOCHECK; + } + return XFAIL("expm1 representable numbers"); + } + + if cfg!(x86_no_sse) + && ctx.base_name == BaseName::Exp2 + && !expected.is_infinite() + && actual.is_infinite() + { + // We return infinity when there is a representable value. Test input: 127.97238 + return XFAIL("586 exp2 representable numbers"); + } + + if ctx.base_name == BaseName::Sinh && input.0.abs() > 80.0 && actual.is_nan() { + // we return some NaN that should be real values or infinite + if ctx.basis == CheckBasis::Musl { + return XFAIL_NOCHECK; + } + return XFAIL("sinh unexpected NaN"); + } + + if (ctx.base_name == BaseName::Lgamma || ctx.base_name == BaseName::LgammaR) + && input.0 > 4e36 + && expected.is_infinite() + && !actual.is_infinite() + { + // This result should saturate but we return a finite value. + return XFAIL_NOCHECK; + } + + if ctx.base_name == BaseName::J0 && input.0 < -1e34 { + // Errors get huge close to -inf + return XFAIL_NOCHECK; + } + + unop_common(input, actual, expected, ctx) + } + + fn check_int<I: Int>(input: (f32,), actual: I, expected: I, ctx: &CheckCtx) -> CheckAction { + // On MPFR for lgammaf_r, we set -1 as the integer result for negative infinity but MPFR + // sets +1 + if ctx.basis == CheckBasis::Mpfr + && ctx.base_name == BaseName::LgammaR + && input.0 == f32::NEG_INFINITY + && actual.abs() == expected.abs() + { + return XFAIL("lgammar integer result"); + } + + DEFAULT + } +} + +impl MaybeOverride<(f64,)> for SpecialCase { + fn check_float<F: Float>(input: (f64,), actual: F, expected: F, ctx: &CheckCtx) -> CheckAction { + if cfg!(x86_no_sse) + && ctx.base_name == BaseName::Ceil + && ctx.basis == CheckBasis::Musl + && input.0 < 0.0 + && input.0 > -1.0 + && expected == F::ZERO + && actual == F::ZERO + { + // musl returns -0.0, we return +0.0 + return XFAIL("i586 ceil signed zero"); + } + + if cfg!(x86_no_sse) + && (ctx.base_name == BaseName::Rint || ctx.base_name == BaseName::Roundeven) + && (expected - actual).abs() <= F::ONE + && (expected - actual).abs() > F::ZERO + { + // Our rounding mode is incorrect. + return XFAIL("i586 rint rounding mode"); + } + + if cfg!(x86_no_sse) + && (ctx.fn_ident == Identifier::Ceil || ctx.fn_ident == Identifier::Floor) + && expected.eq_repr(F::NEG_ZERO) + && actual.eq_repr(F::ZERO) + { + // FIXME: the x87 implementations do not keep the distinction between -0.0 and 0.0. + // See https://github.com/rust-lang/libm/pull/404#issuecomment-2572399955 + return XFAIL("i586 ceil/floor signed zero"); + } + + if cfg!(x86_no_sse) + && (ctx.fn_ident == Identifier::Exp10 || ctx.fn_ident == Identifier::Exp2) + { + // FIXME: i586 has very imprecise results with ULP > u32::MAX for these + // operations so we can't reasonably provide a limit. + return XFAIL_NOCHECK; + } + + if ctx.base_name == BaseName::J0 && input.0 < -1e300 { + // Errors get huge close to -inf + return XFAIL_NOCHECK; + } + + // maybe_check_nan_bits(actual, expected, ctx) + unop_common(input, actual, expected, ctx) + } + + fn check_int<I: Int>(input: (f64,), actual: I, expected: I, ctx: &CheckCtx) -> CheckAction { + // On MPFR for lgamma_r, we set -1 as the integer result for negative infinity but MPFR + // sets +1 + if ctx.basis == CheckBasis::Mpfr + && ctx.base_name == BaseName::LgammaR + && input.0 == f64::NEG_INFINITY + && actual.abs() == expected.abs() + { + return XFAIL("lgammar integer result"); + } + + DEFAULT + } +} + +#[cfg(f128_enabled)] +impl MaybeOverride<(f128,)> for SpecialCase {} + +// F1 and F2 are always the same type, this is just to please generics +fn unop_common<F1: Float, F2: Float>( + input: (F1,), + actual: F2, + expected: F2, + ctx: &CheckCtx, +) -> CheckAction { + if ctx.base_name == BaseName::Acosh + && input.0 < F1::NEG_ONE + && !(expected.is_nan() && actual.is_nan()) + { + // acoshf is undefined for x <= 1.0, but we return a random result at lower values. + + if ctx.basis == CheckBasis::Musl { + return XFAIL_NOCHECK; + } + + return XFAIL("acoshf undefined"); + } + + if (ctx.base_name == BaseName::Lgamma || ctx.base_name == BaseName::LgammaR) + && input.0 < F1::ZERO + && !input.0.is_infinite() + { + // loggamma should not be defined for x < 0, yet we both return results + return XFAIL_NOCHECK; + } + + // fabs and copysign must leave NaNs untouched. + if ctx.base_name == BaseName::Fabs && input.0.is_nan() { + // LLVM currently uses x87 instructions which quieten signalling NaNs to handle the i686 + // `extern "C"` `f32`/`f64` return ABI. + // LLVM issue <https://github.com/llvm/llvm-project/issues/66803> + // Rust issue <https://github.com/rust-lang/rust/issues/115567> + if cfg!(target_arch = "x86") && ctx.basis == CheckBasis::Musl && actual.is_nan() { + return XFAIL_NOCHECK; + } + + // MPFR only has one NaN bitpattern; allow the default `.is_nan()` checks to validate. + if ctx.basis == CheckBasis::Mpfr { + return DEFAULT; + } + + // abs and copysign require signaling NaNs to be propagated, so verify bit equality. + if actual.to_bits() == expected.to_bits() { + return CheckAction::Custom(Ok(())); + } else { + return CheckAction::Custom(Err(anyhow::anyhow!("NaNs have different bitpatterns"))); + } + } + + DEFAULT +} + +#[cfg(f16_enabled)] +impl MaybeOverride<(f16, f16)> for SpecialCase { + fn check_float<F: Float>( + input: (f16, f16), + actual: F, + expected: F, + ctx: &CheckCtx, + ) -> CheckAction { + binop_common(input, actual, expected, ctx) + } +} + +impl MaybeOverride<(f32, f32)> for SpecialCase { + fn check_float<F: Float>( + input: (f32, f32), + actual: F, + expected: F, + ctx: &CheckCtx, + ) -> CheckAction { + binop_common(input, actual, expected, ctx) + } +} + +impl MaybeOverride<(f64, f64)> for SpecialCase { + fn check_float<F: Float>( + input: (f64, f64), + actual: F, + expected: F, + ctx: &CheckCtx, + ) -> CheckAction { + binop_common(input, actual, expected, ctx) + } +} + +#[cfg(f128_enabled)] +impl MaybeOverride<(f128, f128)> for SpecialCase { + fn check_float<F: Float>( + input: (f128, f128), + actual: F, + expected: F, + ctx: &CheckCtx, + ) -> CheckAction { + binop_common(input, actual, expected, ctx) + } +} + +// F1 and F2 are always the same type, this is just to please generics +fn binop_common<F1: Float, F2: Float>( + input: (F1, F1), + actual: F2, + expected: F2, + ctx: &CheckCtx, +) -> CheckAction { + // MPFR only has one NaN bitpattern; allow the default `.is_nan()` checks to validate. Skip if + // the first input (magnitude source) is NaN and the output is also a NaN, or if the second + // input (sign source) is NaN. + if ctx.basis == CheckBasis::Mpfr + && ((input.0.is_nan() && actual.is_nan() && expected.is_nan()) || input.1.is_nan()) + { + return SKIP; + } + + /* FIXME(#439): our fmin and fmax do not compare signed zeros */ + + if ctx.base_name == BaseName::Fmin + && input.0.biteq(F1::NEG_ZERO) + && input.1.biteq(F1::ZERO) + && expected.biteq(F2::NEG_ZERO) + && actual.biteq(F2::ZERO) + { + return XFAIL("fmin signed zeroes"); + } + + if ctx.base_name == BaseName::Fmax + && input.0.biteq(F1::NEG_ZERO) + && input.1.biteq(F1::ZERO) + && expected.biteq(F2::ZERO) + && actual.biteq(F2::NEG_ZERO) + { + return XFAIL("fmax signed zeroes"); + } + + // Musl propagates NaNs if one is provided as the input, but we return the other input. + if (ctx.base_name == BaseName::Fmax || ctx.base_name == BaseName::Fmin) + && ctx.basis == Musl + && (input.0.is_nan() ^ input.1.is_nan()) + && expected.is_nan() + { + return XFAIL("fmax/fmin musl NaN"); + } + + DEFAULT +} + +impl MaybeOverride<(i32, f32)> for SpecialCase { + fn check_float<F: Float>( + input: (i32, f32), + actual: F, + expected: F, + ctx: &CheckCtx, + ) -> CheckAction { + // `ynf(213, 109.15641) = -inf` with our library, should be finite. + if ctx.basis == Mpfr + && ctx.base_name == BaseName::Yn + && input.0 > 200 + && !expected.is_infinite() + && actual.is_infinite() + { + return XFAIL("ynf infinity mismatch"); + } + + int_float_common(input, actual, expected, ctx) + } +} + +impl MaybeOverride<(i32, f64)> for SpecialCase { + fn check_float<F: Float>( + input: (i32, f64), + actual: F, + expected: F, + ctx: &CheckCtx, + ) -> CheckAction { + int_float_common(input, actual, expected, ctx) + } +} + +fn int_float_common<F1: Float, F2: Float>( + input: (i32, F1), + actual: F2, + expected: F2, + ctx: &CheckCtx, +) -> CheckAction { + if ctx.basis == Mpfr + && (ctx.base_name == BaseName::Jn || ctx.base_name == BaseName::Yn) + && input.1 == F1::NEG_INFINITY + && actual == F2::ZERO + && expected == F2::ZERO + { + return XFAIL("we disagree with MPFR on the sign of zero"); + } + + // Values near infinity sometimes get cut off for us. `ynf(681, 509.90924) = -inf` but should + // be -3.2161271e38. + if ctx.basis == Musl + && ctx.fn_ident == Identifier::Ynf + && !expected.is_infinite() + && actual.is_infinite() + && (expected.abs().to_bits().abs_diff(actual.abs().to_bits()) + < F2::Int::cast_from(10_000_000u32)) + { + return XFAIL_NOCHECK; + } + + // Our bessel functions blow up with large N values + if ctx.basis == Musl && (ctx.base_name == BaseName::Jn || ctx.base_name == BaseName::Yn) { + if cfg!(x86_no_sse) { + // Precision is especially bad on i586, not worth checking. + return XFAIL_NOCHECK; + } + + if input.0 > 4000 { + return XFAIL_NOCHECK; + } else if input.0 > 100 { + return CheckAction::AssertWithUlp(1_000_000); + } + } + DEFAULT +} + +#[cfg(f16_enabled)] +impl MaybeOverride<(f16, i32)> for SpecialCase {} +impl MaybeOverride<(f32, i32)> for SpecialCase {} +impl MaybeOverride<(f64, i32)> for SpecialCase {} +#[cfg(f128_enabled)] +impl MaybeOverride<(f128, i32)> for SpecialCase {} + +impl MaybeOverride<(f32, f32, f32)> for SpecialCase {} +impl MaybeOverride<(f64, f64, f64)> for SpecialCase {} +#[cfg(f128_enabled)] +impl MaybeOverride<(f128, f128, f128)> for SpecialCase {} |