diff --git a/libm-test/src/precision.rs b/libm-test/src/precision.rs index 32825b15d..3fb8c1b37 100644 --- a/libm-test/src/precision.rs +++ b/libm-test/src/precision.rs @@ -271,18 +271,6 @@ impl MaybeOverride<(f32,)> for SpecialCase { impl MaybeOverride<(f64,)> for SpecialCase { fn check_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 @@ -292,16 +280,6 @@ impl MaybeOverride<(f64,)> for SpecialCase { 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) { diff --git a/libm/src/math/arch/i586.rs b/libm/src/math/arch/i586.rs index f92b9a2af..9bc2b3225 100644 --- a/libm/src/math/arch/i586.rs +++ b/libm/src/math/arch/i586.rs @@ -1,37 +1,63 @@ //! Architecture-specific support for x86-32 without SSE2 -use super::super::fabs; - /// Use an alternative implementation on x86, because the /// main implementation fails with the x87 FPU used by /// debian i386, probably due to excess precision issues. -/// Basic implementation taken from https://github.com/rust-lang/libm/issues/219. -pub fn ceil(x: f64) -> f64 { - if fabs(x).to_bits() < 4503599627370496.0_f64.to_bits() { - let truncated = x as i64 as f64; - if truncated < x { - return truncated + 1.0; - } else { - return truncated; - } - } else { - return x; - } +/// Based on https://github.com/NetBSD/src/blob/trunk/lib/libm/arch/i387/s_ceil.S +#[unsafe(naked)] +pub extern "C" fn ceil(_: f64) -> f64 { + core::arch::naked_asm!( + "pushl %ebp", + "movl %esp,%ebp", + "subl $8,%esp", + // Store fpu control word. + "fstcw -4(%ebp)", + "movw -4(%ebp),%dx", + // Round towards +oo. + "orw $0x0800,%dx", + "andw $0xfbff,%dx", + "movw %dx,-8(%ebp)", + // Load modified control word + "fldcw -8(%ebp)", + // Round. + "fldl 8(%ebp)", + "frndint", + // Restore original control word. + "fldcw -4(%ebp)", + // + "leave", + "ret", + options(att_syntax) + ) } /// Use an alternative implementation on x86, because the /// main implementation fails with the x87 FPU used by /// debian i386, probably due to excess precision issues. -/// Basic implementation taken from https://github.com/rust-lang/libm/issues/219. -pub fn floor(x: f64) -> f64 { - if fabs(x).to_bits() < 4503599627370496.0_f64.to_bits() { - let truncated = x as i64 as f64; - if truncated > x { - return truncated - 1.0; - } else { - return truncated; - } - } else { - return x; - } +/// Based on https://github.com/NetBSD/src/blob/trunk/lib/libm/arch/i387/s_floor.S +#[unsafe(naked)] +pub extern "C" fn floor(_: f64) -> f64 { + core::arch::naked_asm!( + "pushl %ebp", + "movl %esp,%ebp", + "subl $8,%esp", + // Store fpu control word. + "fstcw -4(%ebp)", + "movw -4(%ebp),%dx", + // Round towards -oo. + "orw $0x0400,%dx", + "andw $0xf7ff,%dx", + "movw %dx,-8(%ebp)", + // Load modified control word + "fldcw -8(%ebp)", + // Round. + "fldl 8(%ebp)", + "frndint", + // Restore original control word. + "fldcw -4(%ebp)", + // + "leave", + "ret", + options(att_syntax) + ) }