Rollup merge of #126429 - tgross35:f16-f128-const-eval, r=RalfJung

Add `f16` and `f128` const eval for binary and unary operationations

Add const evaluation and Miri support for f16 and f128, including unary and binary operations. Casts are not yet included.

Fixes #124583

r? ``@RalfJung``

compiler/rustc_const_eval/src/interpret/operator.rs

@@ -362,14 +362,18 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 let left = left.to_scalar();
                 let right = right.to_scalar();
                 Ok(match fty {
-                    FloatTy::F16 => unimplemented!("f16_f128"),
+                    FloatTy::F16 => {
+                        self.binary_float_op(bin_op, layout, left.to_f16()?, right.to_f16()?)
+                    }
                     FloatTy::F32 => {
                         self.binary_float_op(bin_op, layout, left.to_f32()?, right.to_f32()?)
                     }
                     FloatTy::F64 => {
                         self.binary_float_op(bin_op, layout, left.to_f64()?, right.to_f64()?)
                     }
-                    FloatTy::F128 => unimplemented!("f16_f128"),
+                    FloatTy::F128 => {
+                        self.binary_float_op(bin_op, layout, left.to_f128()?, right.to_f128()?)
+                    }
                 })
             }
             _ if left.layout.ty.is_integral() => {
@@ -429,11 +433,16 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
             }
             ty::Float(fty) => {
                 let val = val.to_scalar();
+                if un_op != Neg {
+                    span_bug!(self.cur_span(), "Invalid float op {:?}", un_op);
+                }
+
                 // No NaN adjustment here, `-` is a bitwise operation!
-                let res = match (un_op, fty) {
-                    (Neg, FloatTy::F32) => Scalar::from_f32(-val.to_f32()?),
-                    (Neg, FloatTy::F64) => Scalar::from_f64(-val.to_f64()?),
-                    _ => span_bug!(self.cur_span(), "Invalid float op {:?}", un_op),
+                let res = match fty {
+                    FloatTy::F16 => Scalar::from_f16(-val.to_f16()?),
+                    FloatTy::F32 => Scalar::from_f32(-val.to_f32()?),
+                    FloatTy::F64 => Scalar::from_f64(-val.to_f64()?),
+                    FloatTy::F128 => Scalar::from_f128(-val.to_f128()?),
                 };
                 Ok(ImmTy::from_scalar(res, layout))
             }

compiler/rustc_middle/src/mir/interpret/value.rs

@@ -69,6 +69,13 @@ impl<Prov: Provenance> fmt::LowerHex for Scalar<Prov> {
     }
 }
 
+impl<Prov> From<Half> for Scalar<Prov> {
+    #[inline(always)]
+    fn from(f: Half) -> Self {
+        Scalar::from_f16(f)
+    }
+}
+
 impl<Prov> From<Single> for Scalar<Prov> {
     #[inline(always)]
     fn from(f: Single) -> Self {
@@ -83,6 +90,13 @@ impl<Prov> From<Double> for Scalar<Prov> {
     }
 }
 
+impl<Prov> From<Quad> for Scalar<Prov> {
+    #[inline(always)]
+    fn from(f: Quad) -> Self {
+        Scalar::from_f128(f)
+    }
+}
+
 impl<Prov> From<ScalarInt> for Scalar<Prov> {
     #[inline(always)]
     fn from(ptr: ScalarInt) -> Self {

src/tools/miri/src/helpers.rs

@@ -7,7 +7,7 @@ use std::time::Duration;
 
 use rand::RngCore;
 
-use rustc_apfloat::ieee::{Double, Single};
+use rustc_apfloat::ieee::{Double, Half, Quad, Single};
 use rustc_apfloat::Float;
 use rustc_hir::{
     def::{DefKind, Namespace},
@@ -1201,12 +1201,14 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         };
 
         let (val, status) = match fty {
-            FloatTy::F16 => unimplemented!("f16_f128"),
+            FloatTy::F16 =>
+                float_to_int_inner::<Half>(this, src.to_scalar().to_f16()?, cast_to, round),
             FloatTy::F32 =>
                 float_to_int_inner::<Single>(this, src.to_scalar().to_f32()?, cast_to, round),
             FloatTy::F64 =>
                 float_to_int_inner::<Double>(this, src.to_scalar().to_f64()?, cast_to, round),
-            FloatTy::F128 => unimplemented!("f16_f128"),
+            FloatTy::F128 =>
+                float_to_int_inner::<Quad>(this, src.to_scalar().to_f128()?, cast_to, round),
         };
 
         if status.intersects(

src/tools/miri/tests/pass/float.rs

@@ -1,6 +1,8 @@
 #![feature(stmt_expr_attributes)]
 #![feature(float_gamma)]
 #![feature(core_intrinsics)]
+#![feature(f128)]
+#![feature(f16)]
 #![allow(arithmetic_overflow)]
 
 use std::fmt::Debug;
@@ -41,103 +43,23 @@ trait FloatToInt<Int>: Copy {
     unsafe fn cast_unchecked(self) -> Int;
 }
 
-impl FloatToInt<i8> for f32 {
-    fn cast(self) -> i8 {
-        self as _
-    }
-    unsafe fn cast_unchecked(self) -> i8 {
-        self.to_int_unchecked()
-    }
-}
-impl FloatToInt<i32> for f32 {
-    fn cast(self) -> i32 {
-        self as _
-    }
-    unsafe fn cast_unchecked(self) -> i32 {
-        self.to_int_unchecked()
-    }
-}
-impl FloatToInt<u32> for f32 {
-    fn cast(self) -> u32 {
-        self as _
-    }
-    unsafe fn cast_unchecked(self) -> u32 {
-        self.to_int_unchecked()
-    }
-}
-impl FloatToInt<i64> for f32 {
-    fn cast(self) -> i64 {
-        self as _
-    }
-    unsafe fn cast_unchecked(self) -> i64 {
-        self.to_int_unchecked()
-    }
-}
-impl FloatToInt<u64> for f32 {
-    fn cast(self) -> u64 {
-        self as _
-    }
-    unsafe fn cast_unchecked(self) -> u64 {
-        self.to_int_unchecked()
-    }
+macro_rules! float_to_int {
+    ($fty:ty => $($ity:ty),+ $(,)?) => {
+        $(
+            impl FloatToInt<$ity> for $fty {
+                fn cast(self) -> $ity {
+                    self as _
+                }
+                unsafe fn cast_unchecked(self) -> $ity {
+                    self.to_int_unchecked()
+                }
+            }
+        )*
+    };
 }
 
-impl FloatToInt<i8> for f64 {
-    fn cast(self) -> i8 {
-        self as _
-    }
-    unsafe fn cast_unchecked(self) -> i8 {
-        self.to_int_unchecked()
-    }
-}
-impl FloatToInt<i32> for f64 {
-    fn cast(self) -> i32 {
-        self as _
-    }
-    unsafe fn cast_unchecked(self) -> i32 {
-        self.to_int_unchecked()
-    }
-}
-impl FloatToInt<u32> for f64 {
-    fn cast(self) -> u32 {
-        self as _
-    }
-    unsafe fn cast_unchecked(self) -> u32 {
-        self.to_int_unchecked()
-    }
-}
-impl FloatToInt<i64> for f64 {
-    fn cast(self) -> i64 {
-        self as _
-    }
-    unsafe fn cast_unchecked(self) -> i64 {
-        self.to_int_unchecked()
-    }
-}
-impl FloatToInt<u64> for f64 {
-    fn cast(self) -> u64 {
-        self as _
-    }
-    unsafe fn cast_unchecked(self) -> u64 {
-        self.to_int_unchecked()
-    }
-}
-impl FloatToInt<i128> for f64 {
-    fn cast(self) -> i128 {
-        self as _
-    }
-    unsafe fn cast_unchecked(self) -> i128 {
-        self.to_int_unchecked()
-    }
-}
-impl FloatToInt<u128> for f64 {
-    fn cast(self) -> u128 {
-        self as _
-    }
-    unsafe fn cast_unchecked(self) -> u128 {
-        self.to_int_unchecked()
-    }
-}
+float_to_int!(f32 => i8, u8, i16, u16, i32, u32, i64, u64, i128, u128);
+float_to_int!(f64 => i8, u8, i16, u16, i32, u32, i64, u64, i128, u128);
 
 /// Test this cast both via `as` and via `approx_unchecked` (i.e., it must not saturate).
 #[track_caller]
@@ -153,18 +75,29 @@ where
 
 fn basic() {
     // basic arithmetic
+    assert_eq(6.0_f16 * 6.0_f16, 36.0_f16);
     assert_eq(6.0_f32 * 6.0_f32, 36.0_f32);
     assert_eq(6.0_f64 * 6.0_f64, 36.0_f64);
+    assert_eq(6.0_f128 * 6.0_f128, 36.0_f128);
+    assert_eq(-{ 5.0_f16 }, -5.0_f16);
     assert_eq(-{ 5.0_f32 }, -5.0_f32);
     assert_eq(-{ 5.0_f64 }, -5.0_f64);
+    assert_eq(-{ 5.0_f128 }, -5.0_f128);
+
     // infinities, NaN
+    // FIXME(f16_f128): add when constants and `is_infinite` are available
     assert!((5.0_f32 / 0.0).is_infinite());
     assert_ne!({ 5.0_f32 / 0.0 }, { -5.0_f32 / 0.0 });
     assert!((5.0_f64 / 0.0).is_infinite());
     assert_ne!({ 5.0_f64 / 0.0 }, { 5.0_f64 / -0.0 });
     assert_ne!(f32::NAN, f32::NAN);
     assert_ne!(f64::NAN, f64::NAN);
+
     // negative zero
+    let posz = 0.0f16;
+    let negz = -0.0f16;
+    assert_eq(posz, negz);
+    assert_ne!(posz.to_bits(), negz.to_bits());
     let posz = 0.0f32;
     let negz = -0.0f32;
     assert_eq(posz, negz);
@@ -173,15 +106,30 @@ fn basic() {
     let negz = -0.0f64;
     assert_eq(posz, negz);
     assert_ne!(posz.to_bits(), negz.to_bits());
+    let posz = 0.0f128;
+    let negz = -0.0f128;
+    assert_eq(posz, negz);
+    assert_ne!(posz.to_bits(), negz.to_bits());
+
     // byte-level transmute
-    let x: u64 = unsafe { std::mem::transmute(42.0_f64) };
-    let y: f64 = unsafe { std::mem::transmute(x) };
-    assert_eq(y, 42.0_f64);
+    let x: u16 = unsafe { std::mem::transmute(42.0_f16) };
+    let y: f16 = unsafe { std::mem::transmute(x) };
+    assert_eq(y, 42.0_f16);
     let x: u32 = unsafe { std::mem::transmute(42.0_f32) };
     let y: f32 = unsafe { std::mem::transmute(x) };
     assert_eq(y, 42.0_f32);
+    let x: u64 = unsafe { std::mem::transmute(42.0_f64) };
+    let y: f64 = unsafe { std::mem::transmute(x) };
+    assert_eq(y, 42.0_f64);
+    let x: u128 = unsafe { std::mem::transmute(42.0_f128) };
+    let y: f128 = unsafe { std::mem::transmute(x) };
+    assert_eq(y, 42.0_f128);
 
     // `%` sign behavior, some of this used to be buggy
+    assert!((black_box(1.0f16) % 1.0).is_sign_positive());
+    assert!((black_box(1.0f16) % -1.0).is_sign_positive());
+    assert!((black_box(-1.0f16) % 1.0).is_sign_negative());
+    assert!((black_box(-1.0f16) % -1.0).is_sign_negative());
     assert!((black_box(1.0f32) % 1.0).is_sign_positive());
     assert!((black_box(1.0f32) % -1.0).is_sign_positive());
     assert!((black_box(-1.0f32) % 1.0).is_sign_negative());
@@ -190,7 +138,12 @@ fn basic() {
     assert!((black_box(1.0f64) % -1.0).is_sign_positive());
     assert!((black_box(-1.0f64) % 1.0).is_sign_negative());
     assert!((black_box(-1.0f64) % -1.0).is_sign_negative());
+    assert!((black_box(1.0f128) % 1.0).is_sign_positive());
+    assert!((black_box(1.0f128) % -1.0).is_sign_positive());
+    assert!((black_box(-1.0f128) % 1.0).is_sign_negative());
+    assert!((black_box(-1.0f128) % -1.0).is_sign_negative());
 
+    // FIXME(f16_f128): add when `abs` is available
     assert_eq!((-1.0f32).abs(), 1.0f32);
     assert_eq!(34.2f64.abs(), 34.2f64);
 }

tests/ui/numbers-arithmetic/f16-f128-lit.rs

@@ -1,3 +1,5 @@
+// Make sure negation happens correctly. Also included:
+// issue: rust-lang/rust#124583
 //@ run-pass
 
 #![feature(f16)]
@@ -8,9 +10,11 @@ fn main() {
     assert_eq!((-0.0_f16).to_bits(), 0x8000);
     assert_eq!(10.0_f16.to_bits(), 0x4900);
     assert_eq!((-10.0_f16).to_bits(), 0xC900);
+    assert_eq!((-(-0.0f16)).to_bits(), 0x0000);
 
     assert_eq!(0.0_f128.to_bits(), 0x0000_0000_0000_0000_0000_0000_0000_0000);
     assert_eq!((-0.0_f128).to_bits(), 0x8000_0000_0000_0000_0000_0000_0000_0000);
     assert_eq!(10.0_f128.to_bits(), 0x4002_4000_0000_0000_0000_0000_0000_0000);
     assert_eq!((-10.0_f128).to_bits(), 0xC002_4000_0000_0000_0000_0000_0000_0000);
+    assert_eq!((-(-0.0f128)).to_bits(), 0x0000_0000_0000_0000_0000_0000_0000_0000);
 }