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-rw-r--r--src/tools/miri/src/intrinsics/mod.rs7
-rw-r--r--src/tools/miri/src/math.rs173
-rw-r--r--src/tools/miri/src/shims/foreign_items.rs210
-rw-r--r--src/tools/miri/tests/pass/float.rs154
4 files changed, 375 insertions, 169 deletions
diff --git a/src/tools/miri/src/intrinsics/mod.rs b/src/tools/miri/src/intrinsics/mod.rs
index 8bcec4e7cbe..4628c30e2df 100644
--- a/src/tools/miri/src/intrinsics/mod.rs
+++ b/src/tools/miri/src/intrinsics/mod.rs
@@ -13,7 +13,6 @@ use rustc_span::{Symbol, sym};
 use self::atomic::EvalContextExt as _;
 use self::helpers::{ToHost, ToSoft};
 use self::simd::EvalContextExt as _;
-use crate::math::apply_random_float_error_ulp;
 use crate::*;
 
 /// Check that the number of args is what we expect.
@@ -362,13 +361,13 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 let f = this.read_scalar(f)?.to_f32()?;
                 let i = this.read_scalar(i)?.to_i32()?;
 
-                let res = math::fixed_powi_float_value(this, f, i).unwrap_or_else(|| {
+                let res = math::fixed_powi_value(this, f, i).unwrap_or_else(|| {
                     // Using host floats (but it's fine, this operation does not have guaranteed precision).
                     let res = f.to_host().powi(i).to_soft();
 
                     // Apply a relative error of 4ULP to introduce some non-determinism
                     // simulating imprecise implementations and optimizations.
-                    apply_random_float_error_ulp(this, res, 4)
+                    math::apply_random_float_error_ulp(this, res, 4)
                 });
                 let res = this.adjust_nan(res, &[f]);
                 this.write_scalar(res, dest)?;
@@ -378,7 +377,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 let f = this.read_scalar(f)?.to_f64()?;
                 let i = this.read_scalar(i)?.to_i32()?;
 
-                let res = math::fixed_powi_float_value(this, f, i).unwrap_or_else(|| {
+                let res = math::fixed_powi_value(this, f, i).unwrap_or_else(|| {
                     // Using host floats (but it's fine, this operation does not have guaranteed precision).
                     let res = f.to_host().powi(i).to_soft();
 
diff --git a/src/tools/miri/src/math.rs b/src/tools/miri/src/math.rs
index dc1541b43df..7d2f1c08368 100644
--- a/src/tools/miri/src/math.rs
+++ b/src/tools/miri/src/math.rs
@@ -1,8 +1,9 @@
 use std::ops::Neg;
+use std::{f32, f64};
 
 use rand::Rng as _;
 use rustc_apfloat::Float as _;
-use rustc_apfloat::ieee::{IeeeFloat, Semantics};
+use rustc_apfloat::ieee::{DoubleS, IeeeFloat, Semantics, SingleS};
 use rustc_middle::ty::{self, FloatTy, ScalarInt};
 
 use crate::*;
@@ -107,29 +108,69 @@ pub(crate) fn apply_random_float_error_to_imm<'tcx>(
     interp_ok(ImmTy::from_scalar_int(res, val.layout))
 }
 
-/// Given an floating-point operation and a floating-point value, clamps the result to the output
-/// range of the given operation.
+/// Given a floating-point operation and a floating-point value, clamps the result to the output
+/// range of the given operation according to the C standard, if any.
 pub(crate) fn clamp_float_value<S: Semantics>(
     intrinsic_name: &str,
     val: IeeeFloat<S>,
-) -> IeeeFloat<S> {
+) -> IeeeFloat<S>
+where
+    IeeeFloat<S>: IeeeExt,
+{
+    let zero = IeeeFloat::<S>::ZERO;
+    let one = IeeeFloat::<S>::one();
+    let two = IeeeFloat::<S>::two();
+    let pi = IeeeFloat::<S>::pi();
+    let pi_over_2 = (pi / two).value;
+
     match intrinsic_name {
-        // sin and cos: [-1, 1]
-        "sinf32" | "cosf32" | "sinf64" | "cosf64" =>
-            val.clamp(IeeeFloat::<S>::one().neg(), IeeeFloat::<S>::one()),
-        // exp: [0, +INF]
-        "expf32" | "exp2f32" | "expf64" | "exp2f64" =>
-            IeeeFloat::<S>::maximum(val, IeeeFloat::<S>::ZERO),
+        // sin, cos, tanh: [-1, 1]
+        #[rustfmt::skip]
+        | "sinf32"
+        | "sinf64"
+        | "cosf32"
+        | "cosf64"
+        | "tanhf"
+        | "tanh"
+         => val.clamp(one.neg(), one),
+
+        // exp: [0, +INF)
+        "expf32" | "exp2f32" | "expf64" | "exp2f64" => val.maximum(zero),
+
+        // cosh: [1, +INF)
+        "coshf" | "cosh" => val.maximum(one),
+
+        // acos: [0, π]
+        "acosf" | "acos" => val.clamp(zero, pi),
+
+        // asin: [-π, +π]
+        "asinf" | "asin" => val.clamp(pi.neg(), pi),
+
+        // atan: (-π/2, +π/2)
+        "atanf" | "atan" => val.clamp(pi_over_2.neg(), pi_over_2),
+
+        // erfc: (-1, 1)
+        "erff" | "erf" => val.clamp(one.neg(), one),
+
+        // erfc: (0, 2)
+        "erfcf" | "erfc" => val.clamp(zero, two),
+
+        // atan2(y, x): arctan(y/x) in [−π, +π]
+        "atan2f" | "atan2" => val.clamp(pi.neg(), pi),
+
         _ => val,
     }
 }
 
 /// For the intrinsics:
-/// - sinf32, sinf64
-/// - cosf32, cosf64
+/// - sinf32, sinf64, sinhf, sinh
+/// - cosf32, cosf64, coshf, cosh
+/// - tanhf, tanh, atanf, atan, atan2f, atan2
 /// - expf32, expf64, exp2f32, exp2f64
 /// - logf32, logf64, log2f32, log2f64, log10f32, log10f64
 /// - powf32, powf64
+/// - erff, erf, erfcf, erfc
+/// - hypotf, hypot
 ///
 /// # Return
 ///
@@ -157,16 +198,68 @@ pub(crate) fn fixed_float_value<S: Semantics>(
     ecx: &mut MiriInterpCx<'_>,
     intrinsic_name: &str,
     args: &[IeeeFloat<S>],
-) -> Option<IeeeFloat<S>> {
+) -> Option<IeeeFloat<S>>
+where
+    IeeeFloat<S>: IeeeExt,
+{
     let this = ecx.eval_context_mut();
     let one = IeeeFloat::<S>::one();
+    let two = IeeeFloat::<S>::two();
+    let three = IeeeFloat::<S>::three();
+    let pi = IeeeFloat::<S>::pi();
+    let pi_over_2 = (pi / two).value;
+    let pi_over_4 = (pi_over_2 / two).value;
+
     Some(match (intrinsic_name, args) {
-        // cos(+- 0) = 1
-        ("cosf32" | "cosf64", [input]) if input.is_zero() => one,
+        // cos(±0) and cosh(±0)= 1
+        ("cosf32" | "cosf64" | "coshf" | "cosh", [input]) if input.is_zero() => one,
 
         // e^0 = 1
         ("expf32" | "expf64" | "exp2f32" | "exp2f64", [input]) if input.is_zero() => one,
 
+        // tanh(±INF) = ±1
+        ("tanhf" | "tanh", [input]) if input.is_infinite() => one.copy_sign(*input),
+
+        // atan(±INF) = ±π/2
+        ("atanf" | "atan", [input]) if input.is_infinite() => pi_over_2.copy_sign(*input),
+
+        // erf(±INF) = ±1
+        ("erff" | "erf", [input]) if input.is_infinite() => one.copy_sign(*input),
+
+        // erfc(-INF) = 2
+        ("erfcf" | "erfc", [input]) if input.is_neg_infinity() => (one + one).value,
+
+        // hypot(x, ±0) = abs(x), if x is not a NaN.
+        ("_hypotf" | "hypotf" | "_hypot" | "hypot", [x, y]) if !x.is_nan() && y.is_zero() =>
+            x.abs(),
+
+        // atan2(±0,−0) = ±π.
+        // atan2(±0, y) = ±π for y < 0.
+        // Must check for non NaN because `y.is_negative()` also applies to NaN.
+        ("atan2f" | "atan2", [x, y]) if (x.is_zero() && (y.is_negative() && !y.is_nan())) =>
+            pi.copy_sign(*x),
+
+        // atan2(±x,−∞) = ±π for finite x > 0.
+        ("atan2f" | "atan2", [x, y])
+            if (!x.is_zero() && !x.is_infinite()) && y.is_neg_infinity() =>
+            pi.copy_sign(*x),
+
+        // atan2(x, ±0) = −π/2 for x < 0.
+        // atan2(x, ±0) =  π/2 for x > 0.
+        ("atan2f" | "atan2", [x, y]) if !x.is_zero() && y.is_zero() => pi_over_2.copy_sign(*x),
+
+        //atan2(±∞, −∞) = ±3π/4
+        ("atan2f" | "atan2", [x, y]) if x.is_infinite() && y.is_neg_infinity() =>
+            (pi_over_4 * three).value.copy_sign(*x),
+
+        //atan2(±∞, +∞) = ±π/4
+        ("atan2f" | "atan2", [x, y]) if x.is_infinite() && y.is_pos_infinity() =>
+            pi_over_4.copy_sign(*x),
+
+        // atan2(±∞, y) returns ±π/2 for finite y.
+        ("atan2f" | "atan2", [x, y]) if x.is_infinite() && (!y.is_infinite() && !y.is_nan()) =>
+            pi_over_2.copy_sign(*x),
+
         // (-1)^(±INF) = 1
         ("powf32" | "powf64", [base, exp]) if *base == -one && exp.is_infinite() => one,
 
@@ -196,25 +289,27 @@ pub(crate) fn fixed_float_value<S: Semantics>(
 
 /// Returns `Some(output)` if `powi` (called `pown` in C) results in a fixed value specified in the
 /// C standard (specifically, C23 annex F.10.4.6) when doing `base^exp`. Otherwise, returns `None`.
-pub(crate) fn fixed_powi_float_value<S: Semantics>(
+pub(crate) fn fixed_powi_value<S: Semantics>(
     ecx: &mut MiriInterpCx<'_>,
     base: IeeeFloat<S>,
     exp: i32,
-) -> Option<IeeeFloat<S>> {
-    let this = ecx.eval_context_mut();
-    Some(match exp {
+) -> Option<IeeeFloat<S>>
+where
+    IeeeFloat<S>: IeeeExt,
+{
+    match exp {
         0 => {
             let one = IeeeFloat::<S>::one();
-            let rng = this.machine.rng.get_mut();
-            let return_nan = this.machine.float_nondet && rng.random() && base.is_signaling();
+            let rng = ecx.machine.rng.get_mut();
+            let return_nan = ecx.machine.float_nondet && rng.random() && base.is_signaling();
             // For SNaN treatment, we are consistent with `powf`above.
             // (We wouldn't have two, unlike powf all implementations seem to agree for powi,
             // but for now we are maximally conservative.)
-            if return_nan { this.generate_nan(&[base]) } else { one }
+            Some(if return_nan { ecx.generate_nan(&[base]) } else { one })
         }
 
         _ => return None,
-    })
+    }
 }
 
 pub(crate) fn sqrt<S: rustc_apfloat::ieee::Semantics>(x: IeeeFloat<S>) -> IeeeFloat<S> {
@@ -299,19 +394,47 @@ pub(crate) fn sqrt<S: rustc_apfloat::ieee::Semantics>(x: IeeeFloat<S>) -> IeeeFl
     }
 }
 
-/// Extend functionality of rustc_apfloat softfloats
+/// Extend functionality of `rustc_apfloat` softfloats for IEEE float types.
 pub trait IeeeExt: rustc_apfloat::Float {
+    // Some values we use:
+
     #[inline]
     fn one() -> Self {
         Self::from_u128(1).value
     }
 
     #[inline]
+    fn two() -> Self {
+        Self::from_u128(2).value
+    }
+
+    #[inline]
+    fn three() -> Self {
+        Self::from_u128(3).value
+    }
+
+    fn pi() -> Self;
+
+    #[inline]
     fn clamp(self, min: Self, max: Self) -> Self {
         self.maximum(min).minimum(max)
     }
 }
-impl<S: rustc_apfloat::ieee::Semantics> IeeeExt for IeeeFloat<S> {}
+
+macro_rules! impl_ieee_pi {
+    ($float_ty:ident, $semantic:ty) => {
+        impl IeeeExt for IeeeFloat<$semantic> {
+            #[inline]
+            fn pi() -> Self {
+                // We take the value from the standard library as the most reasonable source for an exact π here.
+                Self::from_bits($float_ty::consts::PI.to_bits().into())
+            }
+        }
+    };
+}
+
+impl_ieee_pi!(f32, SingleS);
+impl_ieee_pi!(f64, DoubleS);
 
 #[cfg(test)]
 mod tests {
diff --git a/src/tools/miri/src/shims/foreign_items.rs b/src/tools/miri/src/shims/foreign_items.rs
index a700644b95d..187423472ab 100644
--- a/src/tools/miri/src/shims/foreign_items.rs
+++ b/src/tools/miri/src/shims/foreign_items.rs
@@ -18,6 +18,7 @@ use rustc_target::callconv::FnAbi;
 use self::helpers::{ToHost, ToSoft};
 use super::alloc::EvalContextExt as _;
 use super::backtrace::EvalContextExt as _;
+use crate::helpers::EvalContextExt as _;
 use crate::*;
 
 /// Type of dynamic symbols (for `dlsym` et al)
@@ -826,33 +827,36 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
             => {
                 let [f] = this.check_shim_sig_lenient(abi, CanonAbi::C , link_name, args)?;
                 let f = this.read_scalar(f)?.to_f32()?;
-                // Using host floats (but it's fine, these operations do not have guaranteed precision).
-                let f_host = f.to_host();
-                let res = match link_name.as_str() {
-                    "cbrtf" => f_host.cbrt(),
-                    "coshf" => f_host.cosh(),
-                    "sinhf" => f_host.sinh(),
-                    "tanf" => f_host.tan(),
-                    "tanhf" => f_host.tanh(),
-                    "acosf" => f_host.acos(),
-                    "asinf" => f_host.asin(),
-                    "atanf" => f_host.atan(),
-                    "log1pf" => f_host.ln_1p(),
-                    "expm1f" => f_host.exp_m1(),
-                    "tgammaf" => f_host.gamma(),
-                    "erff" => f_host.erf(),
-                    "erfcf" => f_host.erfc(),
-                    _ => bug!(),
-                };
-                let res = res.to_soft();
-                // Apply a relative error of 16ULP to introduce some non-determinism
-                // simulating imprecise implementations and optimizations.
-                // FIXME: temporarily disabled as it breaks std tests.
-                // let res = math::apply_random_float_error_ulp(
-                //     this,
-                //     res,
-                //     4, // log2(16)
-                // );
+
+                let res = math::fixed_float_value(this, link_name.as_str(), &[f]).unwrap_or_else(|| {
+                    // Using host floats (but it's fine, these operations do not have
+                    // guaranteed precision).
+                    let f_host = f.to_host();
+                    let res = match link_name.as_str() {
+                        "cbrtf" => f_host.cbrt(),
+                        "coshf" => f_host.cosh(),
+                        "sinhf" => f_host.sinh(),
+                        "tanf" => f_host.tan(),
+                        "tanhf" => f_host.tanh(),
+                        "acosf" => f_host.acos(),
+                        "asinf" => f_host.asin(),
+                        "atanf" => f_host.atan(),
+                        "log1pf" => f_host.ln_1p(),
+                        "expm1f" => f_host.exp_m1(),
+                        "tgammaf" => f_host.gamma(),
+                        "erff" => f_host.erf(),
+                        "erfcf" => f_host.erfc(),
+                        _ => bug!(),
+                    };
+                    let res = res.to_soft();
+                    // Apply a relative error of 4ULP to introduce some non-determinism
+                    // simulating imprecise implementations and optimizations.
+                    let res = math::apply_random_float_error_ulp(this, res, 4);
+
+                    // Clamp the result to the guaranteed range of this function according to the C standard,
+                    // if any.
+                    math::clamp_float_value(link_name.as_str(), res)
+                });
                 let res = this.adjust_nan(res, &[f]);
                 this.write_scalar(res, dest)?;
             }
@@ -865,24 +869,27 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 let [f1, f2] = this.check_shim_sig_lenient(abi, CanonAbi::C , link_name, args)?;
                 let f1 = this.read_scalar(f1)?.to_f32()?;
                 let f2 = this.read_scalar(f2)?.to_f32()?;
-                // underscore case for windows, here and below
-                // (see https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/floating-point-primitives?view=vs-2019)
-                // Using host floats (but it's fine, these operations do not have guaranteed precision).
-                let res = match link_name.as_str() {
-                    "_hypotf" | "hypotf" => f1.to_host().hypot(f2.to_host()).to_soft(),
-                    "atan2f" => f1.to_host().atan2(f2.to_host()).to_soft(),
-                    #[allow(deprecated)]
-                    "fdimf" => f1.to_host().abs_sub(f2.to_host()).to_soft(),
-                    _ => bug!(),
-                };
-                // Apply a relative error of 16ULP to introduce some non-determinism
-                // simulating imprecise implementations and optimizations.
-                // FIXME: temporarily disabled as it breaks std tests.
-                // let res = math::apply_random_float_error_ulp(
-                //     this,
-                //     res,
-                //     4, // log2(16)
-                // );
+
+                let res = math::fixed_float_value(this, link_name.as_str(), &[f1, f2])
+                    .unwrap_or_else(|| {
+                        let res = match link_name.as_str() {
+                            // underscore case for windows, here and below
+                            // (see https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/floating-point-primitives?view=vs-2019)
+                            // Using host floats (but it's fine, these operations do not have guaranteed precision).
+                            "_hypotf" | "hypotf" => f1.to_host().hypot(f2.to_host()).to_soft(),
+                            "atan2f" => f1.to_host().atan2(f2.to_host()).to_soft(),
+                            #[allow(deprecated)]
+                            "fdimf" => f1.to_host().abs_sub(f2.to_host()).to_soft(),
+                            _ => bug!(),
+                        };
+                        // Apply a relative error of 4ULP to introduce some non-determinism
+                        // simulating imprecise implementations and optimizations.
+                        let res = math::apply_random_float_error_ulp(this, res, 4);
+
+                        // Clamp the result to the guaranteed range of this function according to the C standard,
+                        // if any.
+                        math::clamp_float_value(link_name.as_str(), res)
+                    });
                 let res = this.adjust_nan(res, &[f1, f2]);
                 this.write_scalar(res, dest)?;
             }
@@ -903,33 +910,36 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
             => {
                 let [f] = this.check_shim_sig_lenient(abi, CanonAbi::C , link_name, args)?;
                 let f = this.read_scalar(f)?.to_f64()?;
-                // Using host floats (but it's fine, these operations do not have guaranteed precision).
-                let f_host = f.to_host();
-                let res = match link_name.as_str() {
-                    "cbrt" => f_host.cbrt(),
-                    "cosh" => f_host.cosh(),
-                    "sinh" => f_host.sinh(),
-                    "tan" => f_host.tan(),
-                    "tanh" => f_host.tanh(),
-                    "acos" => f_host.acos(),
-                    "asin" => f_host.asin(),
-                    "atan" => f_host.atan(),
-                    "log1p" => f_host.ln_1p(),
-                    "expm1" => f_host.exp_m1(),
-                    "tgamma" => f_host.gamma(),
-                    "erf" => f_host.erf(),
-                    "erfc" => f_host.erfc(),
-                    _ => bug!(),
-                };
-                let res = res.to_soft();
-                // Apply a relative error of 16ULP to introduce some non-determinism
-                // simulating imprecise implementations and optimizations.
-                // FIXME: temporarily disabled as it breaks std tests.
-                // let res = math::apply_random_float_error_ulp(
-                //     this,
-                //     res.to_soft(),
-                //     4, // log2(16)
-                // );
+
+                let res = math::fixed_float_value(this, link_name.as_str(), &[f]).unwrap_or_else(|| {
+                    // Using host floats (but it's fine, these operations do not have
+                    // guaranteed precision).
+                    let f_host = f.to_host();
+                    let res = match link_name.as_str() {
+                        "cbrt" => f_host.cbrt(),
+                        "cosh" => f_host.cosh(),
+                        "sinh" => f_host.sinh(),
+                        "tan" => f_host.tan(),
+                        "tanh" => f_host.tanh(),
+                        "acos" => f_host.acos(),
+                        "asin" => f_host.asin(),
+                        "atan" => f_host.atan(),
+                        "log1p" => f_host.ln_1p(),
+                        "expm1" => f_host.exp_m1(),
+                        "tgamma" => f_host.gamma(),
+                        "erf" => f_host.erf(),
+                        "erfc" => f_host.erfc(),
+                        _ => bug!(),
+                    };
+                    let res = res.to_soft();
+                    // Apply a relative error of 4ULP to introduce some non-determinism
+                    // simulating imprecise implementations and optimizations.
+                    let res = math::apply_random_float_error_ulp(this, res, 4);
+
+                    // Clamp the result to the guaranteed range of this function according to the C standard,
+                    // if any.
+                    math::clamp_float_value(link_name.as_str(), res)
+                });
                 let res = this.adjust_nan(res, &[f]);
                 this.write_scalar(res, dest)?;
             }
@@ -942,24 +952,26 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 let [f1, f2] = this.check_shim_sig_lenient(abi, CanonAbi::C , link_name, args)?;
                 let f1 = this.read_scalar(f1)?.to_f64()?;
                 let f2 = this.read_scalar(f2)?.to_f64()?;
-                // underscore case for windows, here and below
-                // (see https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/floating-point-primitives?view=vs-2019)
-                // Using host floats (but it's fine, these operations do not have guaranteed precision).
-                let res = match link_name.as_str() {
-                    "_hypot" | "hypot" => f1.to_host().hypot(f2.to_host()).to_soft(),
-                    "atan2" => f1.to_host().atan2(f2.to_host()).to_soft(),
-                    #[allow(deprecated)]
-                    "fdim" => f1.to_host().abs_sub(f2.to_host()).to_soft(),
-                    _ => bug!(),
-                };
-                // Apply a relative error of 16ULP to introduce some non-determinism
-                // simulating imprecise implementations and optimizations.
-                // FIXME: temporarily disabled as it breaks std tests.
-                // let res = math::apply_random_float_error_ulp(
-                //     this,
-                //     res,
-                //     4, // log2(16)
-                // );
+
+                let res = math::fixed_float_value(this, link_name.as_str(), &[f1, f2]).unwrap_or_else(|| {
+                    let res = match link_name.as_str() {
+                        // underscore case for windows, here and below
+                        // (see https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/floating-point-primitives?view=vs-2019)
+                        // Using host floats (but it's fine, these operations do not have guaranteed precision).
+                        "_hypot" | "hypot" => f1.to_host().hypot(f2.to_host()).to_soft(),
+                        "atan2" => f1.to_host().atan2(f2.to_host()).to_soft(),
+                        #[allow(deprecated)]
+                        "fdim" => f1.to_host().abs_sub(f2.to_host()).to_soft(),
+                        _ => bug!(),
+                    };
+                    // Apply a relative error of 4ULP to introduce some non-determinism
+                    // simulating imprecise implementations and optimizations.
+                    let res = math::apply_random_float_error_ulp(this, res, 4);
+
+                    // Clamp the result to the guaranteed range of this function according to the C standard,
+                    // if any.
+                    math::clamp_float_value(link_name.as_str(), res)
+                });
                 let res = this.adjust_nan(res, &[f1, f2]);
                 this.write_scalar(res, dest)?;
             }
@@ -985,11 +997,14 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 // Using host floats (but it's fine, these operations do not have guaranteed precision).
                 let (res, sign) = x.to_host().ln_gamma();
                 this.write_int(sign, &signp)?;
+
                 let res = res.to_soft();
-                // Apply a relative error of 16ULP to introduce some non-determinism
+                // Apply a relative error of 4ULP to introduce some non-determinism
                 // simulating imprecise implementations and optimizations.
-                // FIXME: temporarily disabled as it breaks std tests.
-                // let res = math::apply_random_float_error_ulp(this, res, 4 /* log2(16) */);
+                let res = math::apply_random_float_error_ulp(this, res, 4);
+                // Clamp the result to the guaranteed range of this function according to the C standard,
+                // if any.
+                let res = math::clamp_float_value(link_name.as_str(), res);
                 let res = this.adjust_nan(res, &[x]);
                 this.write_scalar(res, dest)?;
             }
@@ -1001,11 +1016,14 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 // Using host floats (but it's fine, these operations do not have guaranteed precision).
                 let (res, sign) = x.to_host().ln_gamma();
                 this.write_int(sign, &signp)?;
+
                 let res = res.to_soft();
-                // Apply a relative error of 16ULP to introduce some non-determinism
+                // Apply a relative error of 4ULP to introduce some non-determinism
                 // simulating imprecise implementations and optimizations.
-                // FIXME: temporarily disabled as it breaks std tests.
-                // let res = math::apply_random_float_error_ulp(this, res, 4 /* log2(16) */);
+                let res = math::apply_random_float_error_ulp(this, res, 4);
+                // Clamp the result to the guaranteed range of this function according to the C standard,
+                // if any.
+                let res = math::clamp_float_value(link_name.as_str(), res);
                 let res = this.adjust_nan(res, &[x]);
                 this.write_scalar(res, dest)?;
             }
diff --git a/src/tools/miri/tests/pass/float.rs b/src/tools/miri/tests/pass/float.rs
index 1b1163c7797..d6e1b2a83d9 100644
--- a/src/tools/miri/tests/pass/float.rs
+++ b/src/tools/miri/tests/pass/float.rs
@@ -1093,6 +1093,8 @@ pub fn libm() {
 
     assert_approx_eq!(1f32.exp_m1(), f32::consts::E - 1.0);
     assert_approx_eq!(1f64.exp_m1(), f64::consts::E - 1.0);
+    assert_approx_eq!(f32::NEG_INFINITY.exp_m1(), -1.0);
+    assert_approx_eq!(f64::NEG_INFINITY.exp_m1(), -1.0);
 
     assert_approx_eq!(10f32.exp2(), 1024f32);
     assert_approx_eq!(50f64.exp2(), 1125899906842624f64);
@@ -1128,6 +1130,7 @@ pub fn libm() {
     assert_eq!(ldexp(0.65f64, 3i32), 5.2f64);
     assert_eq!(ldexp(1.42, 0xFFFF), f64::INFINITY);
     assert_eq!(ldexp(1.42, -0xFFFF), 0f64);
+    assert_eq!(ldexp(42.0, 0), 42.0);
 
     // Trigonometric functions.
 
@@ -1136,8 +1139,14 @@ pub fn libm() {
     assert_approx_eq!((f64::consts::PI / 2f64).sin(), 1f64);
     assert_approx_eq!(f32::consts::FRAC_PI_6.sin(), 0.5);
     assert_approx_eq!(f64::consts::FRAC_PI_6.sin(), 0.5);
-    assert_approx_eq!(f32::consts::FRAC_PI_4.sin().asin(), f32::consts::FRAC_PI_4);
-    assert_approx_eq!(f64::consts::FRAC_PI_4.sin().asin(), f64::consts::FRAC_PI_4);
+    // Increase error tolerance from 12ULP to 16ULP because of the extra operation.
+    assert_approx_eq!(f32::consts::FRAC_PI_4.sin().asin(), f32::consts::FRAC_PI_4, 16);
+    assert_approx_eq!(f64::consts::FRAC_PI_4.sin().asin(), f64::consts::FRAC_PI_4, 16);
+    assert_biteq(0.0f32.asin(), 0.0f32, "asin(+0) = +0");
+    assert_biteq((-0.0f32).asin(), -0.0, "asin(-0) = -0");
+    assert_biteq(0.0f64.asin(), 0.0, "asin(+0) = +0");
+    assert_biteq((-0.0f64).asin(), -0.0, "asin(-0) = -0");
+
 
     assert_approx_eq!(1.0f32.sinh(), 1.1752012f32);
     assert_approx_eq!(1.0f64.sinh(), 1.1752011936438014f64);
@@ -1164,11 +1173,18 @@ pub fn libm() {
     assert_approx_eq!((f64::consts::PI * 2f64).cos(), 1f64);
     assert_approx_eq!(f32::consts::FRAC_PI_3.cos(), 0.5);
     assert_approx_eq!(f64::consts::FRAC_PI_3.cos(), 0.5);
-    assert_approx_eq!(f32::consts::FRAC_PI_4.cos().acos(), f32::consts::FRAC_PI_4);
-    assert_approx_eq!(f64::consts::FRAC_PI_4.cos().acos(), f64::consts::FRAC_PI_4);
+    // Increase error tolerance from 12ULP to 16ULP because of the extra operation.
+    assert_approx_eq!(f32::consts::FRAC_PI_4.cos().acos(), f32::consts::FRAC_PI_4, 16);
+    assert_approx_eq!(f64::consts::FRAC_PI_4.cos().acos(), f64::consts::FRAC_PI_4, 16);
+    assert_biteq(1.0f32.acos(), 0.0, "acos(1) = 0");
+    assert_biteq(1.0f64.acos(), 0.0, "acos(1) = 0");
 
     assert_approx_eq!(1.0f32.cosh(), 1.54308f32);
     assert_approx_eq!(1.0f64.cosh(), 1.5430806348152437f64);
+    assert_eq!(0.0f32.cosh(), 1.0);
+    assert_eq!(0.0f64.cosh(), 1.0);
+    assert_eq!((-0.0f32).cosh(), 1.0);
+    assert_eq!((-0.0f64).cosh(), 1.0);
     assert_approx_eq!(2.0f32.acosh(), 1.31695789692481670862504634730796844f32);
     assert_approx_eq!(3.0f64.acosh(), 1.76274717403908605046521864995958461f64);
 
@@ -1178,6 +1194,47 @@ pub fn libm() {
     assert_approx_eq!(1.0_f64, 1.0_f64.tan().atan());
     assert_approx_eq!(1.0f32.atan2(2.0f32), 0.46364761f32);
     assert_approx_eq!(1.0f32.atan2(2.0f32), 0.46364761f32);
+    // C standard defines a bunch of fixed outputs for atan2
+    macro_rules! fixed_atan2_cases{
+        ($float_type:ident) => {{
+            use std::$float_type::consts::{PI, FRAC_PI_2, FRAC_PI_4};
+            use $float_type::{INFINITY, NEG_INFINITY};
+
+            // atan2(±0,−0) = ±π.
+            assert_eq!($float_type::atan2(0.0, -0.0), PI, "atan2(0,−0) = π");
+            assert_eq!($float_type::atan2(-0.0, -0.0), -PI, "atan2(-0,−0) = -π");
+
+            // atan2(±0, y) = ±π for y < 0.
+            assert_eq!($float_type::atan2(0.0, -1.0), PI, "atan2(0, y) = π for y < 0.");
+            assert_eq!($float_type::atan2(-0.0, -1.0), -PI, "atan2(-0, y) = -π for y < 0.");
+
+            // atan2(x, ±0) = −π/2 for x < 0.
+            assert_eq!($float_type::atan2(-1.0, 0.0), -FRAC_PI_2, "atan2(x, 0) = −π/2 for x < 0");
+            assert_eq!($float_type::atan2(-1.0, -0.0), -FRAC_PI_2, "atan2(x, -0) = −π/2 for x < 0");
+
+            // atan2(x, ±0) =  π/2 for x > 0.
+            assert_eq!($float_type::atan2(1.0, 0.0), FRAC_PI_2, "atan2(x, 0) =  π/2 for x > 0.");
+            assert_eq!($float_type::atan2(1.0, -0.0), FRAC_PI_2, "atan2(x, -0) =  π/2 for x > 0.");
+
+            // atan2(±x,−∞) = ±π for finite x > 0.
+            assert_eq!($float_type::atan2(1.0, NEG_INFINITY), PI, "atan2(x, −∞) = π for finite x > 0");
+            assert_eq!($float_type::atan2(-1.0, NEG_INFINITY), -PI, "atan2(-x, −∞) = -π for finite x > 0");
+
+            // atan2(±∞, y) returns ±π/2 for finite y.
+            assert_eq!($float_type::atan2(INFINITY, 1.0), FRAC_PI_2, "atan2(+∞, y) returns π/2 for finite y");
+            assert_eq!($float_type::atan2(NEG_INFINITY, 1.0), -FRAC_PI_2, "atan2(-∞, y) returns -π/2 for finite y");
+
+            // atan2(±∞, −∞) = ±3π/4
+            assert_eq!($float_type::atan2(INFINITY, NEG_INFINITY), 3.0 * FRAC_PI_4, "atan2(+∞, −∞) = 3π/4");
+            assert_eq!($float_type::atan2(NEG_INFINITY, NEG_INFINITY), -3.0 * FRAC_PI_4, "atan2(-∞, −∞) = -3π/4");
+
+            // atan2(±∞, +∞) = ±π/4
+            assert_eq!($float_type::atan2(INFINITY, INFINITY), FRAC_PI_4, "atan2(+∞, +∞) = π/4");
+            assert_eq!($float_type::atan2(NEG_INFINITY, INFINITY), -FRAC_PI_4, "atan2(-∞, +∞) = -π/4");
+        }}
+    }
+    fixed_atan2_cases!(f32);
+    fixed_atan2_cases!(f64);
 
     assert_approx_eq!(
         1.0f32.tanh(),
@@ -1187,6 +1244,11 @@ pub fn libm() {
         1.0f64.tanh(),
         (1.0 - f64::consts::E.powi(-2)) / (1.0 + f64::consts::E.powi(-2))
     );
+    assert_eq!(f32::INFINITY.tanh(), 1.0);
+    assert_eq!(f32::NEG_INFINITY.tanh(), -1.0);
+    assert_eq!(f64::INFINITY.tanh(), 1.0);
+    assert_eq!(f64::NEG_INFINITY.tanh(), -1.0);
+
     assert_approx_eq!(0.5f32.atanh(), 0.54930614433405484569762261846126285f32);
     assert_approx_eq!(0.5f64.atanh(), 0.54930614433405484569762261846126285f64);
 
@@ -1207,8 +1269,14 @@ pub fn libm() {
 
     assert_approx_eq!(1.0f32.erf(), 0.84270079294971486934122063508260926f32);
     assert_approx_eq!(1.0f64.erf(), 0.84270079294971486934122063508260926f64);
+    assert_eq!(f32::INFINITY.erf(), 1.0);
+    assert_eq!(f64::INFINITY.erf(), 1.0);
     assert_approx_eq!(1.0f32.erfc(), 0.15729920705028513065877936491739074f32);
     assert_approx_eq!(1.0f64.erfc(), 0.15729920705028513065877936491739074f64);
+    assert_eq!(f32::NEG_INFINITY.erfc(), 2.0);
+    assert_eq!(f64::NEG_INFINITY.erfc(), 2.0);
+    assert_eq!(f32::INFINITY.erfc(), 0.0);
+    assert_eq!(f64::INFINITY.erfc(), 0.0);
 }
 
 fn test_fast() {
@@ -1418,7 +1486,6 @@ fn test_non_determinism() {
     }
     pub fn test_operations_f32(a: f32, b: f32) {
         test_operations_f!(a, b);
-        // FIXME: some are temporarily disabled as it breaks std tests.
         ensure_nondet(|| a.powf(b));
         ensure_nondet(|| a.powi(2));
         ensure_nondet(|| a.log(b));
@@ -1427,35 +1494,34 @@ fn test_non_determinism() {
         ensure_nondet(|| f32::consts::E.ln());
         ensure_nondet(|| 10f32.log10());
         ensure_nondet(|| 8f32.log2());
-        // ensure_nondet(|| 1f32.ln_1p());
-        // ensure_nondet(|| 27.0f32.cbrt());
-        // ensure_nondet(|| 3.0f32.hypot(4.0f32));
+        ensure_nondet(|| 1f32.ln_1p());
+        ensure_nondet(|| 27.0f32.cbrt());
+        ensure_nondet(|| 3.0f32.hypot(4.0f32));
         ensure_nondet(|| 1f32.sin());
         ensure_nondet(|| 1f32.cos());
         // On i686-pc-windows-msvc , these functions are implemented by calling the `f64` version,
         // which means the little rounding errors Miri introduces are discarded by the cast down to
         // `f32`. Just skip the test for them.
-        // if !cfg!(all(target_os = "windows", target_env = "msvc", target_arch = "x86")) {
-        //     ensure_nondet(|| 1.0f32.tan());
-        //     ensure_nondet(|| 1.0f32.asin());
-        //     ensure_nondet(|| 5.0f32.acos());
-        //     ensure_nondet(|| 1.0f32.atan());
-        //     ensure_nondet(|| 1.0f32.atan2(2.0f32));
-        //     ensure_nondet(|| 1.0f32.sinh());
-        //     ensure_nondet(|| 1.0f32.cosh());
-        //     ensure_nondet(|| 1.0f32.tanh());
-        // }
-        // ensure_nondet(|| 1.0f32.asinh());
-        // ensure_nondet(|| 2.0f32.acosh());
-        // ensure_nondet(|| 0.5f32.atanh());
-        // ensure_nondet(|| 5.0f32.gamma());
-        // ensure_nondet(|| 5.0f32.ln_gamma());
-        // ensure_nondet(|| 5.0f32.erf());
-        // ensure_nondet(|| 5.0f32.erfc());
+        if !cfg!(all(target_os = "windows", target_env = "msvc", target_arch = "x86")) {
+            ensure_nondet(|| 1.0f32.tan());
+            ensure_nondet(|| 1.0f32.asin());
+            ensure_nondet(|| 5.0f32.acos());
+            ensure_nondet(|| 1.0f32.atan());
+            ensure_nondet(|| 1.0f32.atan2(2.0f32));
+            ensure_nondet(|| 1.0f32.sinh());
+            ensure_nondet(|| 1.0f32.cosh());
+            ensure_nondet(|| 1.0f32.tanh());
+        }
+        ensure_nondet(|| 1.0f32.asinh());
+        ensure_nondet(|| 2.0f32.acosh());
+        ensure_nondet(|| 0.5f32.atanh());
+        ensure_nondet(|| 5.0f32.gamma());
+        ensure_nondet(|| 5.0f32.ln_gamma());
+        ensure_nondet(|| 5.0f32.erf());
+        ensure_nondet(|| 5.0f32.erfc());
     }
     pub fn test_operations_f64(a: f64, b: f64) {
         test_operations_f!(a, b);
-        // FIXME: some are temporarily disabled as it breaks std tests.
         ensure_nondet(|| a.powf(b));
         ensure_nondet(|| a.powi(2));
         ensure_nondet(|| a.log(b));
@@ -1464,26 +1530,26 @@ fn test_non_determinism() {
         ensure_nondet(|| 3f64.ln());
         ensure_nondet(|| f64::consts::E.log10());
         ensure_nondet(|| f64::consts::E.log2());
-        // ensure_nondet(|| 1f64.ln_1p());
-        // ensure_nondet(|| 27.0f64.cbrt());
-        // ensure_nondet(|| 3.0f64.hypot(4.0f64));
+        ensure_nondet(|| 1f64.ln_1p());
+        ensure_nondet(|| 27.0f64.cbrt());
+        ensure_nondet(|| 3.0f64.hypot(4.0f64));
         ensure_nondet(|| 1f64.sin());
         ensure_nondet(|| 1f64.cos());
-        // ensure_nondet(|| 1.0f64.tan());
-        // ensure_nondet(|| 1.0f64.asin());
-        // ensure_nondet(|| 5.0f64.acos());
-        // ensure_nondet(|| 1.0f64.atan());
-        // ensure_nondet(|| 1.0f64.atan2(2.0f64));
-        // ensure_nondet(|| 1.0f64.sinh());
-        // ensure_nondet(|| 1.0f64.cosh());
-        // ensure_nondet(|| 1.0f64.tanh());
-        // ensure_nondet(|| 1.0f64.asinh());
-        // ensure_nondet(|| 3.0f64.acosh());
-        // ensure_nondet(|| 0.5f64.atanh());
-        // ensure_nondet(|| 5.0f64.gamma());
-        // ensure_nondet(|| 5.0f64.ln_gamma());
-        // ensure_nondet(|| 5.0f64.erf());
-        // ensure_nondet(|| 5.0f64.erfc());
+        ensure_nondet(|| 1.0f64.tan());
+        ensure_nondet(|| 1.0f64.asin());
+        ensure_nondet(|| 5.0f64.acos());
+        ensure_nondet(|| 1.0f64.atan());
+        ensure_nondet(|| 1.0f64.atan2(2.0f64));
+        ensure_nondet(|| 1.0f64.sinh());
+        ensure_nondet(|| 1.0f64.cosh());
+        ensure_nondet(|| 1.0f64.tanh());
+        ensure_nondet(|| 1.0f64.asinh());
+        ensure_nondet(|| 3.0f64.acosh());
+        ensure_nondet(|| 0.5f64.atanh());
+        ensure_nondet(|| 5.0f64.gamma());
+        ensure_nondet(|| 5.0f64.ln_gamma());
+        ensure_nondet(|| 5.0f64.erf());
+        ensure_nondet(|| 5.0f64.erfc());
     }
     pub fn test_operations_f128(a: f128, b: f128) {
         test_operations_f!(a, b);