Use remquo from Rug

Rug 1.27.0 exposes `remquo`; make use of it for our tests. Removing our
workaround also allows removing the direct dependency on `gmp-mpfr-sys`

Author: tgross35

crates/libm-test/Cargo.toml

@@ -28,7 +28,8 @@ short-benchmarks = []
 
 [dependencies]
 anyhow = "1.0.95"
-gmp-mpfr-sys = { version = "1.6.4", optional = true, default-features = false, features = ["mpfr"] }
+# This is not directly used but is required so we can enable `gmp-mpfr-sys/force-cross`.
+gmp-mpfr-sys = { version = "1.6.4", optional = true, default-features = false }
 iai-callgrind = { version = "0.14.0", optional = true }
 indicatif = { version = "0.17.9", default-features = false }
 libm = { path = "../..", features = ["unstable-public-internals"] }

crates/libm-test/src/mpfloat.rs

@@ -4,13 +4,10 @@
 //! a struct named `Operation` that implements [`MpOp`].
 
 use std::cmp::Ordering;
-use std::ffi::{c_int, c_long};
 
-use gmp_mpfr_sys::mpfr::rnd_t;
 use rug::Assign;
 pub use rug::Float as MpFloat;
 use rug::az::{self, Az};
-use rug::float::Round;
 use rug::float::Round::Nearest;
 use rug::ops::{PowAssignRound, RemAssignRound};
 
@@ -410,28 +407,20 @@ macro_rules! impl_op_for_ty {
             }
 
             impl MpOp for crate::op::[<remquo $suffix>]::Routine {
-                type MpTy = (MpFloat, MpFloat, MpFloat);
+                type MpTy = (MpFloat, MpFloat);
 
                 fn new_mp() -> Self::MpTy {
                     (
                         new_mpfloat::<Self::FTy>(),
                         new_mpfloat::<Self::FTy>(),
-                        new_mpfloat::<Self::FTy>()
                     )
                 }
 
                 fn run(this: &mut Self::MpTy, input: Self::RustArgs) -> Self::RustRet {
                     this.0.assign(input.0);
                     this.1.assign(input.1);
-                    let (ord, ql) = mpfr_remquo(&mut this.2, &this.0, &this.1, Nearest);
-
-                    // `remquo` integer results are sign-magnitude representation. Transfer the
-                    // sign bit from the long result to the int result.
-                    let clear = !(1 << (c_int::BITS - 1));
-                    let sign = ((ql >> (c_long::BITS - 1)) as i32) << (c_int::BITS - 1);
-                    let q = (ql as i32) & clear | sign;
-
-                    (prep_retval::<Self::FTy>(&mut this.2, ord), q)
+                    let (ord, q) = this.0.remainder_quo31_round(&this.1, Nearest);
+                    (prep_retval::<Self::FTy>(&mut this.0, ord), q)
                 }
             }
 
@@ -541,24 +530,3 @@ impl MpOp for crate::op::nextafterf::Routine {
         unimplemented!("nextafter does not yet have a MPFR operation");
     }
 }
-
-/// `rug` does not provide `remquo` so this exposes `mpfr_remquo`. See rug#76.
-fn mpfr_remquo(r: &mut MpFloat, x: &MpFloat, y: &MpFloat, round: Round) -> (Ordering, c_long) {
-    let r = r.as_raw_mut();
-    let x = x.as_raw();
-    let y = y.as_raw();
-    let mut q: c_long = 0;
-
-    let round = match round {
-        Round::Nearest => rnd_t::RNDN,
-        Round::Zero => rnd_t::RNDZ,
-        Round::Up => rnd_t::RNDU,
-        Round::Down => rnd_t::RNDD,
-        Round::AwayZero => rnd_t::RNDA,
-        _ => unreachable!(),
-    };
-
-    // SAFETY: mutable and const pointers are valid and do not alias, by Rust's rules.
-    let ord = unsafe { gmp_mpfr_sys::mpfr::remquo(r, &mut q, x, y, round) };
-    (ord.cmp(&0), q)
-}

crates/libm-test/src/precision.rs

@@ -408,15 +408,6 @@ impl MaybeOverride<(f32, f32)> for SpecialCase {
     ) -> CheckAction {
         binop_common(input, actual, expected, ctx)
     }
-
-    fn check_int<I: Int>(
-        _input: (f32, f32),
-        actual: I,
-        expected: I,
-        ctx: &CheckCtx,
-    ) -> CheckAction {
-        remquo_common(actual, expected, ctx)
-    }
 }
 
 impl MaybeOverride<(f64, f64)> for SpecialCase {
@@ -428,15 +419,6 @@ impl MaybeOverride<(f64, f64)> for SpecialCase {
     ) -> CheckAction {
         binop_common(input, actual, expected, ctx)
     }
-
-    fn check_int<I: Int>(
-        _input: (f64, f64),
-        actual: I,
-        expected: I,
-        ctx: &CheckCtx,
-    ) -> CheckAction {
-        remquo_common(actual, expected, ctx)
-    }
 }
 
 #[cfg(f128_enabled)]
@@ -499,19 +481,6 @@ fn binop_common<F1: Float, F2: Float>(
     DEFAULT
 }
 
-fn remquo_common<I: Int>(actual: I, expected: I, ctx: &CheckCtx) -> CheckAction {
-    // FIXME: Our MPFR implementation disagrees with musl and may need to be updated.
-    if ctx.basis == CheckBasis::Mpfr
-        && ctx.base_name == BaseName::Remquo
-        && expected == I::MIN
-        && actual == I::ZERO
-    {
-        return XFAIL("remquo integer mismatch");
-    }
-
-    DEFAULT
-}
-
 impl MaybeOverride<(i32, f32)> for SpecialCase {
     fn check_float<F: Float>(
         input: (i32, f32),