Make some float methods unstable const fn

Some float methods are now `const fn` under the `const_float_methods` feature gate.

In order to support `min`, `max`, `abs` and `copysign`, the implementation of some intrinsics had to be moved from Miri to rustc_const_eval.

Author: eduardosm

compiler/rustc_const_eval/src/interpret/intrinsics.rs

@@ -4,6 +4,7 @@
 
 use std::assert_matches::assert_matches;
 
+use rustc_apfloat::ieee::{Double, Half, Quad, Single};
 use rustc_hir::def_id::DefId;
 use rustc_middle::mir::{self, BinOp, ConstValue, NonDivergingIntrinsic};
 use rustc_middle::ty::layout::{LayoutOf as _, TyAndLayout, ValidityRequirement};
@@ -438,6 +439,26 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 self.write_scalar(Scalar::from_target_usize(align.bytes(), self), dest)?;
             }
 
+            sym::minnumf16 => self.float_min_intrinsic::<Half>(args, dest)?,
+            sym::minnumf32 => self.float_min_intrinsic::<Single>(args, dest)?,
+            sym::minnumf64 => self.float_min_intrinsic::<Double>(args, dest)?,
+            sym::minnumf128 => self.float_min_intrinsic::<Quad>(args, dest)?,
+
+            sym::maxnumf16 => self.float_max_intrinsic::<Half>(args, dest)?,
+            sym::maxnumf32 => self.float_max_intrinsic::<Single>(args, dest)?,
+            sym::maxnumf64 => self.float_max_intrinsic::<Double>(args, dest)?,
+            sym::maxnumf128 => self.float_max_intrinsic::<Quad>(args, dest)?,
+
+            sym::copysignf16 => self.float_copysign_intrinsic::<Half>(args, dest)?,
+            sym::copysignf32 => self.float_copysign_intrinsic::<Single>(args, dest)?,
+            sym::copysignf64 => self.float_copysign_intrinsic::<Double>(args, dest)?,
+            sym::copysignf128 => self.float_copysign_intrinsic::<Quad>(args, dest)?,
+
+            sym::fabsf16 => self.float_abs_intrinsic::<Half>(args, dest)?,
+            sym::fabsf32 => self.float_abs_intrinsic::<Single>(args, dest)?,
+            sym::fabsf64 => self.float_abs_intrinsic::<Double>(args, dest)?,
+            sym::fabsf128 => self.float_abs_intrinsic::<Quad>(args, dest)?,
+
             // Unsupported intrinsic: skip the return_to_block below.
             _ => return interp_ok(false),
         }
@@ -697,4 +718,63 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         let rhs_bytes = get_bytes(self, rhs)?;
         interp_ok(Scalar::from_bool(lhs_bytes == rhs_bytes))
     }
+
+    fn float_min_intrinsic<F>(
+        &mut self,
+        args: &[OpTy<'tcx, M::Provenance>],
+        dest: &MPlaceTy<'tcx, M::Provenance>,
+    ) -> InterpResult<'tcx, ()>
+    where
+        F: rustc_apfloat::Float + rustc_apfloat::FloatConvert<F> + Into<Scalar<M::Provenance>>,
+    {
+        let a: F = self.read_scalar(&args[0])?.to_float()?;
+        let b: F = self.read_scalar(&args[1])?.to_float()?;
+        let res = self.adjust_nan(a.min(b), &[a, b]);
+        self.write_scalar(res, dest)?;
+        interp_ok(())
+    }
+
+    fn float_max_intrinsic<F>(
+        &mut self,
+        args: &[OpTy<'tcx, M::Provenance>],
+        dest: &MPlaceTy<'tcx, M::Provenance>,
+    ) -> InterpResult<'tcx, ()>
+    where
+        F: rustc_apfloat::Float + rustc_apfloat::FloatConvert<F> + Into<Scalar<M::Provenance>>,
+    {
+        let a: F = self.read_scalar(&args[0])?.to_float()?;
+        let b: F = self.read_scalar(&args[1])?.to_float()?;
+        let res = self.adjust_nan(a.max(b), &[a, b]);
+        self.write_scalar(res, dest)?;
+        interp_ok(())
+    }
+
+    fn float_copysign_intrinsic<F>(
+        &mut self,
+        args: &[OpTy<'tcx, M::Provenance>],
+        dest: &MPlaceTy<'tcx, M::Provenance>,
+    ) -> InterpResult<'tcx, ()>
+    where
+        F: rustc_apfloat::Float + rustc_apfloat::FloatConvert<F> + Into<Scalar<M::Provenance>>,
+    {
+        let a: F = self.read_scalar(&args[0])?.to_float()?;
+        let b: F = self.read_scalar(&args[1])?.to_float()?;
+        // bitwise, no NaN adjustments
+        self.write_scalar(a.copy_sign(b), dest)?;
+        interp_ok(())
+    }
+
+    fn float_abs_intrinsic<F>(
+        &mut self,
+        args: &[OpTy<'tcx, M::Provenance>],
+        dest: &MPlaceTy<'tcx, M::Provenance>,
+    ) -> InterpResult<'tcx, ()>
+    where
+        F: rustc_apfloat::Float + rustc_apfloat::FloatConvert<F> + Into<Scalar<M::Provenance>>,
+    {
+        let x: F = self.read_scalar(&args[0])?.to_float()?;
+        // bitwise, no NaN adjustments
+        self.write_scalar(x.abs(), dest)?;
+        interp_ok(())
+    }
 }

library/core/src/intrinsics.rs

@@ -120,6 +120,7 @@
 #![feature(const_char_encode_utf16)]
 #![feature(const_eval_select)]
 #![feature(const_exact_div)]
+#![feature(const_float_methods)]
 #![feature(const_fmt_arguments_new)]
 #![feature(const_hash)]
 #![feature(const_heap)]

library/core/src/lib.rs

@@ -471,7 +471,7 @@ impl f128 {
     #[inline]
     #[must_use]
     #[unstable(feature = "f128", issue = "116909")]
-    pub fn is_sign_positive(self) -> bool {
+    pub const fn is_sign_positive(self) -> bool {
         !self.is_sign_negative()
     }
 
@@ -497,7 +497,7 @@ impl f128 {
     #[inline]
     #[must_use]
     #[unstable(feature = "f128", issue = "116909")]
-    pub fn is_sign_negative(self) -> bool {
+    pub const fn is_sign_negative(self) -> bool {
         // IEEE754 says: isSignMinus(x) is true if and only if x has negative sign. isSignMinus
         // applies to zeros and NaNs as well.
         // SAFETY: This is just transmuting to get the sign bit, it's fine.
@@ -538,7 +538,7 @@ impl f128 {
     #[inline]
     #[unstable(feature = "f128", issue = "116909")]
     // #[unstable(feature = "float_next_up_down", issue = "91399")]
-    pub fn next_up(self) -> Self {
+    pub const fn next_up(self) -> Self {
         // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
         // denormals to zero. This is in general unsound and unsupported, but here
         // we do our best to still produce the correct result on such targets.
@@ -592,7 +592,7 @@ impl f128 {
     #[inline]
     #[unstable(feature = "f128", issue = "116909")]
     // #[unstable(feature = "float_next_up_down", issue = "91399")]
-    pub fn next_down(self) -> Self {
+    pub const fn next_down(self) -> Self {
         // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
         // denormals to zero. This is in general unsound and unsupported, but here
         // we do our best to still produce the correct result on such targets.
@@ -627,8 +627,9 @@ impl f128 {
     /// ```
     #[inline]
     #[unstable(feature = "f128", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "this returns the result of the operation, without modifying the original"]
-    pub fn recip(self) -> Self {
+    pub const fn recip(self) -> Self {
         1.0 / self
     }
 
@@ -647,8 +648,9 @@ impl f128 {
     /// ```
     #[inline]
     #[unstable(feature = "f128", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "this returns the result of the operation, without modifying the original"]
-    pub fn to_degrees(self) -> Self {
+    pub const fn to_degrees(self) -> Self {
         // Use a literal for better precision.
         const PIS_IN_180: f128 = 57.2957795130823208767981548141051703324054724665643215491602_f128;
         self * PIS_IN_180
@@ -670,8 +672,9 @@ impl f128 {
     /// ```
     #[inline]
     #[unstable(feature = "f128", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "this returns the result of the operation, without modifying the original"]
-    pub fn to_radians(self) -> f128 {
+    pub const fn to_radians(self) -> f128 {
         // Use a literal for better precision.
         const RADS_PER_DEG: f128 =
             0.0174532925199432957692369076848861271344287188854172545609719_f128;
@@ -698,8 +701,9 @@ impl f128 {
     /// ```
     #[inline]
     #[unstable(feature = "f128", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "this returns the result of the comparison, without modifying either input"]
-    pub fn max(self, other: f128) -> f128 {
+    pub const fn max(self, other: f128) -> f128 {
         intrinsics::maxnumf128(self, other)
     }
 
@@ -723,8 +727,9 @@ impl f128 {
     /// ```
     #[inline]
     #[unstable(feature = "f128", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "this returns the result of the comparison, without modifying either input"]
-    pub fn min(self, other: f128) -> f128 {
+    pub const fn min(self, other: f128) -> f128 {
         intrinsics::minnumf128(self, other)
     }
 
@@ -757,7 +762,7 @@ impl f128 {
     #[unstable(feature = "f128", issue = "116909")]
     // #[unstable(feature = "float_minimum_maximum", issue = "91079")]
     #[must_use = "this returns the result of the comparison, without modifying either input"]
-    pub fn maximum(self, other: f128) -> f128 {
+    pub const fn maximum(self, other: f128) -> f128 {
         if self > other {
             self
         } else if other > self {
@@ -798,7 +803,7 @@ impl f128 {
     #[unstable(feature = "f128", issue = "116909")]
     // #[unstable(feature = "float_minimum_maximum", issue = "91079")]
     #[must_use = "this returns the result of the comparison, without modifying either input"]
-    pub fn minimum(self, other: f128) -> f128 {
+    pub const fn minimum(self, other: f128) -> f128 {
         if self < other {
             self
         } else if other < self {
@@ -1269,9 +1274,20 @@ impl f128 {
     /// ```
     #[inline]
     #[unstable(feature = "f128", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "method returns a new number and does not mutate the original value"]
-    pub fn clamp(mut self, min: f128, max: f128) -> f128 {
-        assert!(min <= max, "min > max, or either was NaN. min = {min:?}, max = {max:?}");
+    pub const fn clamp(mut self, min: f128, max: f128) -> f128 {
+        #[inline] // inline to avoid LLVM crash
+        const fn assert_at_const(min: f128, max: f128) {
+            // Note that we cannot format in constant expressions.
+            assert!(min <= max, "min > max, or either was NaN");
+        }
+        #[inline] // inline to avoid codegen regression
+        fn assert_at_rt(min: f128, max: f128) {
+            assert!(min <= max, "min > max, or either was NaN. min = {min:?}, max = {max:?}");
+        }
+        // FIXME(const-hack): We would prefer to have streamlined panics when formatters become const-friendly.
+        intrinsics::const_eval_select((min, max), assert_at_const, assert_at_rt);
         if self < min {
             self = min;
         }

library/core/src/num/f128.rs

@@ -459,7 +459,7 @@ impl f16 {
     #[inline]
     #[must_use]
     #[unstable(feature = "f16", issue = "116909")]
-    pub fn is_sign_positive(self) -> bool {
+    pub const fn is_sign_positive(self) -> bool {
         !self.is_sign_negative()
     }
 
@@ -488,7 +488,7 @@ impl f16 {
     #[inline]
     #[must_use]
     #[unstable(feature = "f16", issue = "116909")]
-    pub fn is_sign_negative(self) -> bool {
+    pub const fn is_sign_negative(self) -> bool {
         // IEEE754 says: isSignMinus(x) is true if and only if x has negative sign. isSignMinus
         // applies to zeros and NaNs as well.
         // SAFETY: This is just transmuting to get the sign bit, it's fine.
@@ -529,7 +529,7 @@ impl f16 {
     #[inline]
     #[unstable(feature = "f16", issue = "116909")]
     // #[unstable(feature = "float_next_up_down", issue = "91399")]
-    pub fn next_up(self) -> Self {
+    pub const fn next_up(self) -> Self {
         // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
         // denormals to zero. This is in general unsound and unsupported, but here
         // we do our best to still produce the correct result on such targets.
@@ -583,7 +583,7 @@ impl f16 {
     #[inline]
     #[unstable(feature = "f16", issue = "116909")]
     // #[unstable(feature = "float_next_up_down", issue = "91399")]
-    pub fn next_down(self) -> Self {
+    pub const fn next_down(self) -> Self {
         // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
         // denormals to zero. This is in general unsound and unsupported, but here
         // we do our best to still produce the correct result on such targets.
@@ -618,8 +618,9 @@ impl f16 {
     /// ```
     #[inline]
     #[unstable(feature = "f16", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "this returns the result of the operation, without modifying the original"]
-    pub fn recip(self) -> Self {
+    pub const fn recip(self) -> Self {
         1.0 / self
     }
 
@@ -638,8 +639,9 @@ impl f16 {
     /// ```
     #[inline]
     #[unstable(feature = "f16", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "this returns the result of the operation, without modifying the original"]
-    pub fn to_degrees(self) -> Self {
+    pub const fn to_degrees(self) -> Self {
         // Use a literal for better precision.
         const PIS_IN_180: f16 = 57.2957795130823208767981548141051703_f16;
         self * PIS_IN_180
@@ -661,8 +663,9 @@ impl f16 {
     /// ```
     #[inline]
     #[unstable(feature = "f16", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "this returns the result of the operation, without modifying the original"]
-    pub fn to_radians(self) -> f16 {
+    pub const fn to_radians(self) -> f16 {
         // Use a literal for better precision.
         const RADS_PER_DEG: f16 = 0.017453292519943295769236907684886_f16;
         self * RADS_PER_DEG
@@ -687,8 +690,9 @@ impl f16 {
     /// ```
     #[inline]
     #[unstable(feature = "f16", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "this returns the result of the comparison, without modifying either input"]
-    pub fn max(self, other: f16) -> f16 {
+    pub const fn max(self, other: f16) -> f16 {
         intrinsics::maxnumf16(self, other)
     }
 
@@ -711,8 +715,9 @@ impl f16 {
     /// ```
     #[inline]
     #[unstable(feature = "f16", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "this returns the result of the comparison, without modifying either input"]
-    pub fn min(self, other: f16) -> f16 {
+    pub const fn min(self, other: f16) -> f16 {
         intrinsics::minnumf16(self, other)
     }
 
@@ -744,7 +749,7 @@ impl f16 {
     #[unstable(feature = "f16", issue = "116909")]
     // #[unstable(feature = "float_minimum_maximum", issue = "91079")]
     #[must_use = "this returns the result of the comparison, without modifying either input"]
-    pub fn maximum(self, other: f16) -> f16 {
+    pub const fn maximum(self, other: f16) -> f16 {
         if self > other {
             self
         } else if other > self {
@@ -784,7 +789,7 @@ impl f16 {
     #[unstable(feature = "f16", issue = "116909")]
     // #[unstable(feature = "float_minimum_maximum", issue = "91079")]
     #[must_use = "this returns the result of the comparison, without modifying either input"]
-    pub fn minimum(self, other: f16) -> f16 {
+    pub const fn minimum(self, other: f16) -> f16 {
         if self < other {
             self
         } else if other < self {
@@ -1244,9 +1249,20 @@ impl f16 {
     /// ```
     #[inline]
     #[unstable(feature = "f16", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "method returns a new number and does not mutate the original value"]
-    pub fn clamp(mut self, min: f16, max: f16) -> f16 {
-        assert!(min <= max, "min > max, or either was NaN. min = {min:?}, max = {max:?}");
+    pub const fn clamp(mut self, min: f16, max: f16) -> f16 {
+        #[inline] // inline to avoid LLVM crash
+        const fn assert_at_const(min: f16, max: f16) {
+            // Note that we cannot format in constant expressions.
+            assert!(min <= max, "min > max, or either was NaN");
+        }
+        #[inline] // inline to avoid codegen regression
+        fn assert_at_rt(min: f16, max: f16) {
+            assert!(min <= max, "min > max, or either was NaN. min = {min:?}, max = {max:?}");
+        }
+        // FIXME(const-hack): We would prefer to have streamlined panics when formatters become const-friendly.
+        intrinsics::const_eval_select((min, max), assert_at_const, assert_at_rt);
         if self < min {
             self = min;
         }

library/core/src/num/f16.rs

@@ -828,8 +828,9 @@ impl f32 {
     /// ```
     #[must_use = "this returns the result of the operation, without modifying the original"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn recip(self) -> f32 {
+    pub const fn recip(self) -> f32 {
         1.0 / self
     }
 
@@ -845,8 +846,9 @@ impl f32 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn to_degrees(self) -> f32 {
+    pub const fn to_degrees(self) -> f32 {
         // Use a constant for better precision.
         const PIS_IN_180: f32 = 57.2957795130823208767981548141051703_f32;
         self * PIS_IN_180
@@ -864,8 +866,9 @@ impl f32 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn to_radians(self) -> f32 {
+    pub const fn to_radians(self) -> f32 {
         const RADS_PER_DEG: f32 = consts::PI / 180.0;
         self * RADS_PER_DEG
     }
@@ -885,8 +888,9 @@ impl f32 {
     /// ```
     #[must_use = "this returns the result of the comparison, without modifying either input"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn max(self, other: f32) -> f32 {
+    pub const fn max(self, other: f32) -> f32 {
         intrinsics::maxnumf32(self, other)
     }
 
@@ -905,8 +909,9 @@ impl f32 {
     /// ```
     #[must_use = "this returns the result of the comparison, without modifying either input"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn min(self, other: f32) -> f32 {
+    pub const fn min(self, other: f32) -> f32 {
         intrinsics::minnumf32(self, other)
     }
 
@@ -933,7 +938,7 @@ impl f32 {
     #[must_use = "this returns the result of the comparison, without modifying either input"]
     #[unstable(feature = "float_minimum_maximum", issue = "91079")]
     #[inline]
-    pub fn maximum(self, other: f32) -> f32 {
+    pub const fn maximum(self, other: f32) -> f32 {
         if self > other {
             self
         } else if other > self {
@@ -968,7 +973,7 @@ impl f32 {
     #[must_use = "this returns the result of the comparison, without modifying either input"]
     #[unstable(feature = "float_minimum_maximum", issue = "91079")]
     #[inline]
-    pub fn minimum(self, other: f32) -> f32 {
+    pub const fn minimum(self, other: f32) -> f32 {
         if self < other {
             self
         } else if other < self {
@@ -1401,9 +1406,19 @@ impl f32 {
     /// ```
     #[must_use = "method returns a new number and does not mutate the original value"]
     #[stable(feature = "clamp", since = "1.50.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn clamp(mut self, min: f32, max: f32) -> f32 {
-        assert!(min <= max, "min > max, or either was NaN. min = {min:?}, max = {max:?}");
+    pub const fn clamp(mut self, min: f32, max: f32) -> f32 {
+        const fn assert_at_const(min: f32, max: f32) {
+            // Note that we cannot format in constant expressions.
+            assert!(min <= max, "min > max, or either was NaN");
+        }
+        #[inline] // inline to avoid codegen regression
+        fn assert_at_rt(min: f32, max: f32) {
+            assert!(min <= max, "min > max, or either was NaN. min = {min:?}, max = {max:?}");
+        }
+        // FIXME(const-hack): We would prefer to have streamlined panics when formatters become const-friendly.
+        intrinsics::const_eval_select((min, max), assert_at_const, assert_at_rt);
         if self < min {
             self = min;
         }

library/core/src/num/f32.rs

@@ -845,8 +845,9 @@ impl f64 {
     /// ```
     #[must_use = "this returns the result of the operation, without modifying the original"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn recip(self) -> f64 {
+    pub const fn recip(self) -> f64 {
         1.0 / self
     }
 
@@ -862,8 +863,9 @@ impl f64 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn to_degrees(self) -> f64 {
+    pub const fn to_degrees(self) -> f64 {
         // The division here is correctly rounded with respect to the true
         // value of 180/π. (This differs from f32, where a constant must be
         // used to ensure a correctly rounded result.)
@@ -882,8 +884,9 @@ impl f64 {
     #[must_use = "this returns the result of the operation, \
                   without modifying the original"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn to_radians(self) -> f64 {
+    pub const fn to_radians(self) -> f64 {
         const RADS_PER_DEG: f64 = consts::PI / 180.0;
         self * RADS_PER_DEG
     }
@@ -903,8 +906,9 @@ impl f64 {
     /// ```
     #[must_use = "this returns the result of the comparison, without modifying either input"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn max(self, other: f64) -> f64 {
+    pub const fn max(self, other: f64) -> f64 {
         intrinsics::maxnumf64(self, other)
     }
 
@@ -923,8 +927,9 @@ impl f64 {
     /// ```
     #[must_use = "this returns the result of the comparison, without modifying either input"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn min(self, other: f64) -> f64 {
+    pub const fn min(self, other: f64) -> f64 {
         intrinsics::minnumf64(self, other)
     }
 
@@ -951,7 +956,7 @@ impl f64 {
     #[must_use = "this returns the result of the comparison, without modifying either input"]
     #[unstable(feature = "float_minimum_maximum", issue = "91079")]
     #[inline]
-    pub fn maximum(self, other: f64) -> f64 {
+    pub const fn maximum(self, other: f64) -> f64 {
         if self > other {
             self
         } else if other > self {
@@ -986,7 +991,7 @@ impl f64 {
     #[must_use = "this returns the result of the comparison, without modifying either input"]
     #[unstable(feature = "float_minimum_maximum", issue = "91079")]
     #[inline]
-    pub fn minimum(self, other: f64) -> f64 {
+    pub const fn minimum(self, other: f64) -> f64 {
         if self < other {
             self
         } else if other < self {
@@ -1401,9 +1406,19 @@ impl f64 {
     /// ```
     #[must_use = "method returns a new number and does not mutate the original value"]
     #[stable(feature = "clamp", since = "1.50.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn clamp(mut self, min: f64, max: f64) -> f64 {
-        assert!(min <= max, "min > max, or either was NaN. min = {min:?}, max = {max:?}");
+    pub const fn clamp(mut self, min: f64, max: f64) -> f64 {
+        const fn assert_at_const(min: f64, max: f64) {
+            // Note that we cannot format in constant expressions.
+            assert!(min <= max, "min > max, or either was NaN");
+        }
+        #[inline] // inline to avoid codegen regression
+        fn assert_at_rt(min: f64, max: f64) {
+            assert!(min <= max, "min > max, or either was NaN. min = {min:?}, max = {max:?}");
+        }
+        // FIXME(const-hack): We would prefer to have streamlined panics when formatters become const-friendly.
+        intrinsics::const_eval_select((min, max), assert_at_const, assert_at_rt);
         if self < min {
             self = min;
         }

library/core/src/num/f64.rs

@@ -210,8 +210,9 @@ impl f128 {
     #[inline]
     #[rustc_allow_incoherent_impl]
     #[unstable(feature = "f128", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "method returns a new number and does not mutate the original value"]
-    pub fn abs(self) -> Self {
+    pub const fn abs(self) -> Self {
         // FIXME(f16_f128): replace with `intrinsics::fabsf128` when available
         // We don't do this now because LLVM has lowering bugs for f128 math.
         Self::from_bits(self.to_bits() & !(1 << 127))
@@ -240,8 +241,9 @@ impl f128 {
     #[inline]
     #[rustc_allow_incoherent_impl]
     #[unstable(feature = "f128", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "method returns a new number and does not mutate the original value"]
-    pub fn signum(self) -> f128 {
+    pub const fn signum(self) -> f128 {
         if self.is_nan() { Self::NAN } else { 1.0_f128.copysign(self) }
     }
 
@@ -278,8 +280,9 @@ impl f128 {
     #[inline]
     #[rustc_allow_incoherent_impl]
     #[unstable(feature = "f128", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "method returns a new number and does not mutate the original value"]
-    pub fn copysign(self, sign: f128) -> f128 {
+    pub const fn copysign(self, sign: f128) -> f128 {
         unsafe { intrinsics::copysignf128(self, sign) }
     }
 

library/std/src/f128.rs

@@ -210,8 +210,9 @@ impl f16 {
     #[inline]
     #[rustc_allow_incoherent_impl]
     #[unstable(feature = "f16", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "method returns a new number and does not mutate the original value"]
-    pub fn abs(self) -> Self {
+    pub const fn abs(self) -> Self {
         // FIXME(f16_f128): replace with `intrinsics::fabsf16` when available
         Self::from_bits(self.to_bits() & !(1 << 15))
     }
@@ -239,8 +240,9 @@ impl f16 {
     #[inline]
     #[rustc_allow_incoherent_impl]
     #[unstable(feature = "f16", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "method returns a new number and does not mutate the original value"]
-    pub fn signum(self) -> f16 {
+    pub const fn signum(self) -> f16 {
         if self.is_nan() { Self::NAN } else { 1.0_f16.copysign(self) }
     }
 
@@ -277,8 +279,9 @@ impl f16 {
     #[inline]
     #[rustc_allow_incoherent_impl]
     #[unstable(feature = "f16", issue = "116909")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[must_use = "method returns a new number and does not mutate the original value"]
-    pub fn copysign(self, sign: f16) -> f16 {
+    pub const fn copysign(self, sign: f16) -> f16 {
         unsafe { intrinsics::copysignf16(self, sign) }
     }
 

library/std/src/f16.rs

@@ -194,8 +194,9 @@ impl f32 {
     #[rustc_allow_incoherent_impl]
     #[must_use = "method returns a new number and does not mutate the original value"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn abs(self) -> f32 {
+    pub const fn abs(self) -> f32 {
         unsafe { intrinsics::fabsf32(self) }
     }
 
@@ -218,8 +219,9 @@ impl f32 {
     #[rustc_allow_incoherent_impl]
     #[must_use = "method returns a new number and does not mutate the original value"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn signum(self) -> f32 {
+    pub const fn signum(self) -> f32 {
         if self.is_nan() { Self::NAN } else { 1.0_f32.copysign(self) }
     }
 
@@ -253,7 +255,8 @@ impl f32 {
     #[must_use = "method returns a new number and does not mutate the original value"]
     #[inline]
     #[stable(feature = "copysign", since = "1.35.0")]
-    pub fn copysign(self, sign: f32) -> f32 {
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
+    pub const fn copysign(self, sign: f32) -> f32 {
         unsafe { intrinsics::copysignf32(self, sign) }
     }
 

library/std/src/f32.rs

@@ -194,8 +194,9 @@ impl f64 {
     #[rustc_allow_incoherent_impl]
     #[must_use = "method returns a new number and does not mutate the original value"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn abs(self) -> f64 {
+    pub const fn abs(self) -> f64 {
         unsafe { intrinsics::fabsf64(self) }
     }
 
@@ -218,8 +219,9 @@ impl f64 {
     #[rustc_allow_incoherent_impl]
     #[must_use = "method returns a new number and does not mutate the original value"]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn signum(self) -> f64 {
+    pub const fn signum(self) -> f64 {
         if self.is_nan() { Self::NAN } else { 1.0_f64.copysign(self) }
     }
 
@@ -252,8 +254,9 @@ impl f64 {
     #[rustc_allow_incoherent_impl]
     #[must_use = "method returns a new number and does not mutate the original value"]
     #[stable(feature = "copysign", since = "1.35.0")]
+    #[rustc_const_unstable(feature = "const_float_methods", issue = "130843")]
     #[inline]
-    pub fn copysign(self, sign: f64) -> f64 {
+    pub const fn copysign(self, sign: f64) -> f64 {
         unsafe { intrinsics::copysignf64(self, sign) }
     }
 

library/std/src/f64.rs

@@ -288,6 +288,7 @@
 #![feature(cfg_target_thread_local)]
 #![feature(cfi_encoding)]
 #![feature(concat_idents)]
+#![feature(const_float_methods)]
 #![feature(decl_macro)]
 #![feature(deprecated_suggestion)]
 #![feature(doc_cfg)]

library/std/src/lib.rs

@@ -145,20 +145,6 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 this.write_scalar(Scalar::from_bool(branch), dest)?;
             }
 
-            // Floating-point operations
-            "fabsf32" => {
-                let [f] = check_arg_count(args)?;
-                let f = this.read_scalar(f)?.to_f32()?;
-                // This is a "bitwise" operation, so there's no NaN non-determinism.
-                this.write_scalar(Scalar::from_f32(f.abs()), dest)?;
-            }
-            "fabsf64" => {
-                let [f] = check_arg_count(args)?;
-                let f = this.read_scalar(f)?.to_f64()?;
-                // This is a "bitwise" operation, so there's no NaN non-determinism.
-                this.write_scalar(Scalar::from_f64(f.abs()), dest)?;
-            }
-
             "floorf32" | "ceilf32" | "truncf32" | "roundf32" | "rintf32" => {
                 let [f] = check_arg_count(args)?;
                 let f = this.read_scalar(f)?.to_f32()?;
@@ -249,31 +235,6 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 this.write_scalar(res, dest)?;
             }
 
-            "minnumf32" | "maxnumf32" | "copysignf32" => {
-                let [a, b] = check_arg_count(args)?;
-                let a = this.read_scalar(a)?.to_f32()?;
-                let b = this.read_scalar(b)?.to_f32()?;
-                let res = match intrinsic_name {
-                    "minnumf32" => this.adjust_nan(a.min(b), &[a, b]),
-                    "maxnumf32" => this.adjust_nan(a.max(b), &[a, b]),
-                    "copysignf32" => a.copy_sign(b), // bitwise, no NaN adjustments
-                    _ => bug!(),
-                };
-                this.write_scalar(Scalar::from_f32(res), dest)?;
-            }
-            "minnumf64" | "maxnumf64" | "copysignf64" => {
-                let [a, b] = check_arg_count(args)?;
-                let a = this.read_scalar(a)?.to_f64()?;
-                let b = this.read_scalar(b)?.to_f64()?;
-                let res = match intrinsic_name {
-                    "minnumf64" => this.adjust_nan(a.min(b), &[a, b]),
-                    "maxnumf64" => this.adjust_nan(a.max(b), &[a, b]),
-                    "copysignf64" => a.copy_sign(b), // bitwise, no NaN adjustments
-                    _ => bug!(),
-                };
-                this.write_scalar(Scalar::from_f64(res), dest)?;
-            }
-
             "fmaf32" => {
                 let [a, b, c] = check_arg_count(args)?;
                 let a = this.read_scalar(a)?.to_f32()?;

src/tools/miri/src/intrinsics/mod.rs

@@ -0,0 +1,47 @@
+//@ run-pass
+//! Tests the float intrinsics: min, max, abs, copysign
+
+#![feature(const_float_methods)]
+#![feature(f16, f128)]
+
+const F16_MIN: f16 = 1.0_f16.min(0.5_f16);
+const F16_MAX: f16 = 1.0_f16.max(0.5_f16);
+const F16_ABS: f16 = (-1.0_f16).abs();
+const F16_COPYSIGN: f16 = 1.0_f16.copysign(-2.0_f16);
+
+const F32_MIN: f32 = 1.0_f32.min(0.5_f32);
+const F32_MAX: f32 = 1.0_f32.max(0.5_f32);
+const F32_ABS: f32 = (-1.0_f32).abs();
+const F32_COPYSIGN: f32 = 1.0_f32.copysign(-2.0_f32);
+
+const F64_MIN: f64 = 1.0_f64.min(0.5_f64);
+const F64_MAX: f64 = 1.0_f64.max(0.5_f64);
+const F64_ABS: f64 = (-1.0_f64).abs();
+const F64_COPYSIGN: f64 = 1.0_f64.copysign(-2.0_f64);
+
+const F128_MIN: f128 = 1.0_f128.min(0.5_f128);
+const F128_MAX: f128 = 1.0_f128.max(0.5_f128);
+const F128_ABS: f128 = (-1.0_f128).abs();
+const F128_COPYSIGN: f128 = 1.0_f128.copysign(-2.0_f128);
+
+fn main() {
+    assert_eq!(F16_MIN, 0.5);
+    assert_eq!(F16_MAX, 1.0);
+    assert_eq!(F16_ABS, 1.0);
+    assert_eq!(F16_COPYSIGN, -1.0);
+
+    assert_eq!(F32_MIN, 0.5);
+    assert_eq!(F32_MAX, 1.0);
+    assert_eq!(F32_ABS, 1.0);
+    assert_eq!(F32_COPYSIGN, -1.0);
+
+    assert_eq!(F64_MIN, 0.5);
+    assert_eq!(F64_MAX, 1.0);
+    assert_eq!(F64_ABS, 1.0);
+    assert_eq!(F64_COPYSIGN, -1.0);
+
+    assert_eq!(F128_MIN, 0.5);
+    assert_eq!(F128_MAX, 1.0);
+    assert_eq!(F128_ABS, 1.0);
+    assert_eq!(F128_COPYSIGN, -1.0);
+}