Rollup merge of rust-lang#122470 - tgross35:f16-f128-step4-libs-min, r=Amanieu

`f16` and `f128` step 4: basic library support

This is the next step after rust-lang#121926, another portion of rust-lang#114607

Tracking issue: rust-lang#116909

This PR adds the most basic operations to `f16` and `f128` that get lowered as LLVM intrinsics. This is a very small step but it seemed reasonable enough to add unopinionated basic operations before the larger modules that are built on top of them.

r? ```@Amanieu``` since you were pretty involved in the RFC
cc ```@compiler-errors```
```@rustbot``` label +T-libs-api +S-blocked +F-f16_and_f128

Author: fmease

library/core/src/clone.rs

@@ -227,13 +227,10 @@ mod impls {
     impl_clone! {
         usize u8 u16 u32 u64 u128
         isize i8 i16 i32 i64 i128
-        f32 f64
+        f16 f32 f64 f128
         bool char
     }
 
-    #[cfg(not(bootstrap))]
-    impl_clone! { f16 f128 }
-
     #[unstable(feature = "never_type", issue = "35121")]
     impl Clone for ! {
         #[inline]

library/core/src/cmp.rs

@@ -1497,12 +1497,9 @@ mod impls {
     }
 
     partial_eq_impl! {
-        bool char usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f32 f64
+        bool char usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f16 f32 f64 f128
     }
 
-    #[cfg(not(bootstrap))]
-    partial_eq_impl! { f16 f128 }
-
     macro_rules! eq_impl {
         ($($t:ty)*) => ($(
             #[stable(feature = "rust1", since = "1.0.0")]
@@ -1553,10 +1550,7 @@ mod impls {
         }
     }
 
-    partial_ord_impl! { f32 f64 }
-
-    #[cfg(not(bootstrap))]
-    partial_ord_impl! { f16 f128 }
+    partial_ord_impl! { f16 f32 f64 f128 }
 
     macro_rules! ord_impl {
         ($($t:ty)*) => ($(

library/core/src/convert/num.rs

@@ -34,8 +34,10 @@ macro_rules! impl_float_to_int {
     }
 }
 
+impl_float_to_int!(f16 => u8, u16, u32, u64, u128, usize, i8, i16, i32, i64, i128, isize);
 impl_float_to_int!(f32 => u8, u16, u32, u64, u128, usize, i8, i16, i32, i64, i128, isize);
 impl_float_to_int!(f64 => u8, u16, u32, u64, u128, usize, i8, i16, i32, i64, i128, isize);
+impl_float_to_int!(f128 => u8, u16, u32, u64, u128, usize, i8, i16, i32, i64, i128, isize);
 
 // Conversion traits for primitive integer and float types
 // Conversions T -> T are covered by a blanket impl and therefore excluded
@@ -163,7 +165,12 @@ impl_from!(u16 => f64, #[stable(feature = "lossless_float_conv", since = "1.6.0"
 impl_from!(u32 => f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
 
 // float -> float
+impl_from!(f16 => f32, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
+impl_from!(f16 => f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
+impl_from!(f16 => f128, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
 impl_from!(f32 => f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
+impl_from!(f32 => f128, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
+impl_from!(f64 => f128, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
 
 macro_rules! impl_float_from_bool {
     ($float:ty) => {

library/core/src/fmt/nofloat.rs

@@ -11,5 +11,7 @@ macro_rules! floating {
     };
 }
 
+floating! { f16 }
 floating! { f32 }
 floating! { f64 }
+floating! { f128 }

library/core/src/lib.rs

@@ -200,8 +200,6 @@
 //
 // Language features:
 // tidy-alphabetical-start
-#![cfg_attr(not(bootstrap), feature(f128))]
-#![cfg_attr(not(bootstrap), feature(f16))]
 #![feature(abi_unadjusted)]
 #![feature(adt_const_params)]
 #![feature(allow_internal_unsafe)]
@@ -226,6 +224,8 @@
 #![feature(doc_notable_trait)]
 #![feature(effects)]
 #![feature(extern_types)]
+#![feature(f128)]
+#![feature(f16)]
 #![feature(freeze_impls)]
 #![feature(fundamental)]
 #![feature(generic_arg_infer)]
@@ -347,6 +347,10 @@ pub mod u8;
 #[path = "num/shells/usize.rs"]
 pub mod usize;
 
+#[path = "num/f128.rs"]
+pub mod f128;
+#[path = "num/f16.rs"]
+pub mod f16;
 #[path = "num/f32.rs"]
 pub mod f32;
 #[path = "num/f64.rs"]

library/core/src/marker.rs

@@ -422,17 +422,11 @@ marker_impls! {
     Copy for
         usize, u8, u16, u32, u64, u128,
         isize, i8, i16, i32, i64, i128,
-        f32, f64,
+        f16, f32, f64, f128,
         bool, char,
         {T: ?Sized} *const T,
         {T: ?Sized} *mut T,
-}
 
-#[cfg(not(bootstrap))]
-marker_impls! {
-    #[stable(feature = "rust1", since = "1.0.0")]
-    Copy for
-        f16, f128,
 }
 
 #[unstable(feature = "never_type", issue = "35121")]

library/core/src/num/f128.rs

@@ -0,0 +1,16 @@
+//! Constants for the `f128` quadruple-precision floating point type.
+//!
+//! *[See also the `f128` primitive type][f128].*
+//!
+//! Mathematically significant numbers are provided in the `consts` sub-module.
+//!
+//! For the constants defined directly in this module
+//! (as distinct from those defined in the `consts` sub-module),
+//! new code should instead use the associated constants
+//! defined directly on the `f128` type.
+
+#![unstable(feature = "f128", issue = "116909")]
+
+/// Basic mathematical constants.
+#[unstable(feature = "f128", issue = "116909")]
+pub mod consts {}

library/core/src/num/f16.rs

@@ -0,0 +1,16 @@
+//! Constants for the `f16` half-precision floating point type.
+//!
+//! *[See also the `f16` primitive type][f16].*
+//!
+//! Mathematically significant numbers are provided in the `consts` sub-module.
+//!
+//! For the constants defined directly in this module
+//! (as distinct from those defined in the `consts` sub-module),
+//! new code should instead use the associated constants
+//! defined directly on the `f16` type.
+
+#![unstable(feature = "f16", issue = "116909")]
+
+/// Basic mathematical constants.
+#[unstable(feature = "f16", issue = "116909")]
+pub mod consts {}

library/core/src/ops/arith.rs

@@ -109,7 +109,7 @@ macro_rules! add_impl {
     )*)
 }
 
-add_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f32 f64 }
+add_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f16 f32 f64 f128 }
 
 /// The subtraction operator `-`.
 ///
@@ -218,7 +218,7 @@ macro_rules! sub_impl {
     )*)
 }
 
-sub_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f32 f64 }
+sub_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f16 f32 f64 f128 }
 
 /// The multiplication operator `*`.
 ///
@@ -348,7 +348,7 @@ macro_rules! mul_impl {
     )*)
 }
 
-mul_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f32 f64 }
+mul_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f16 f32 f64 f128 }
 
 /// The division operator `/`.
 ///
@@ -506,7 +506,7 @@ macro_rules! div_impl_float {
     )*)
 }
 
-div_impl_float! { f32 f64 }
+div_impl_float! { f16 f32 f64 f128 }
 
 /// The remainder operator `%`.
 ///
@@ -623,7 +623,7 @@ macro_rules! rem_impl_float {
     )*)
 }
 
-rem_impl_float! { f32 f64 }
+rem_impl_float! { f16 f32 f64 f128 }
 
 /// The unary negation operator `-`.
 ///
@@ -698,7 +698,7 @@ macro_rules! neg_impl {
     )*)
 }
 
-neg_impl! { isize i8 i16 i32 i64 i128 f32 f64 }
+neg_impl! { isize i8 i16 i32 i64 i128 f16 f32 f64 f128 }
 
 /// The addition assignment operator `+=`.
 ///
@@ -765,7 +765,7 @@ macro_rules! add_assign_impl {
     )+)
 }
 
-add_assign_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f32 f64 }
+add_assign_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f16 f32 f64 f128 }
 
 /// The subtraction assignment operator `-=`.
 ///
@@ -832,7 +832,7 @@ macro_rules! sub_assign_impl {
     )+)
 }
 
-sub_assign_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f32 f64 }
+sub_assign_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f16 f32 f64 f128 }
 
 /// The multiplication assignment operator `*=`.
 ///
@@ -890,7 +890,7 @@ macro_rules! mul_assign_impl {
     )+)
 }
 
-mul_assign_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f32 f64 }
+mul_assign_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f16 f32 f64 f128 }
 
 /// The division assignment operator `/=`.
 ///
@@ -947,7 +947,7 @@ macro_rules! div_assign_impl {
     )+)
 }
 
-div_assign_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f32 f64 }
+div_assign_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f16 f32 f64 f128 }
 
 /// The remainder assignment operator `%=`.
 ///
@@ -1008,4 +1008,4 @@ macro_rules! rem_assign_impl {
     )+)
 }
 
-rem_assign_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f32 f64 }
+rem_assign_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f16 f32 f64 f128 }

library/core/src/primitive_docs.rs

@@ -1074,7 +1074,22 @@ mod prim_tuple {}
 #[doc(hidden)]
 impl<T> (T,) {}
 
+#[rustc_doc_primitive = "f16"]
+#[doc(alias = "half")]
+/// A 16-bit floating point type (specifically, the "binary16" type defined in IEEE 754-2008).
+///
+/// This type is very similar to [`prim@f32`] but has decreased precision because it uses half as many
+/// bits. Please see [the documentation for [`prim@f32`] or [Wikipedia on
+/// half-precision values][wikipedia] for more information.
+///
+/// *[See also the `std::f16::consts` module](crate::f16::consts).*
+///
+/// [wikipedia]: https://en.wikipedia.org/wiki/Half-precision_floating-point_format
+#[unstable(feature = "f16", issue = "116909")]
+mod prim_f16 {}
+
 #[rustc_doc_primitive = "f32"]
+#[doc(alias = "single")]
 /// A 32-bit floating point type (specifically, the "binary32" type defined in IEEE 754-2008).
 ///
 /// This type can represent a wide range of decimal numbers, like `3.5`, `27`,
@@ -1143,6 +1158,7 @@ impl<T> (T,) {}
 mod prim_f32 {}
 
 #[rustc_doc_primitive = "f64"]
+#[doc(alias = "double")]
 /// A 64-bit floating point type (specifically, the "binary64" type defined in IEEE 754-2008).
 ///
 /// This type is very similar to [`f32`], but has increased
@@ -1157,6 +1173,20 @@ mod prim_f32 {}
 #[stable(feature = "rust1", since = "1.0.0")]
 mod prim_f64 {}
 
+#[rustc_doc_primitive = "f128"]
+#[doc(alias = "quad")]
+/// A 128-bit floating point type (specifically, the "binary128" type defined in IEEE 754-2008).
+///
+/// This type is very similar to [`prim@f32`] and [`prim@f64`], but has increased precision by using twice
+/// as many bits as `f64`. Please see [the documentation for [`prim@f32`] or [Wikipedia on
+/// quad-precision values][wikipedia] for more information.
+///
+/// *[See also the `std::f128::consts` module](crate::f128::consts).*
+///
+/// [wikipedia]: https://en.wikipedia.org/wiki/Quadruple-precision_floating-point_format
+#[unstable(feature = "f128", issue = "116909")]
+mod prim_f128 {}
+
 #[rustc_doc_primitive = "i8"]
 //
 /// The 8-bit signed integer type.

library/std/src/f128.rs

@@ -0,0 +1,11 @@
+//! Constants for the `f128` double-precision floating point type.
+//!
+//! *[See also the `f128` primitive type](primitive@f128).*
+//!
+//! Mathematically significant numbers are provided in the `consts` sub-module.
+
+#[cfg(test)]
+mod tests;
+
+#[unstable(feature = "f128", issue = "116909")]
+pub use core::f128::consts;

library/std/src/f128/tests.rs

@@ -0,0 +1,40 @@
+#![allow(dead_code)] // FIXME(f16_f128): remove once constants are used
+
+/// Smallest number
+const TINY_BITS: u128 = 0x1;
+/// Next smallest number
+const TINY_UP_BITS: u128 = 0x2;
+/// Exponent = 0b11...10, Sifnificand 0b1111..10. Min val > 0
+const MAX_DOWN_BITS: u128 = 0x7ffeffffffffffffffffffffffffffff;
+/// Zeroed exponent, full significant
+const LARGEST_SUBNORMAL_BITS: u128 = 0x0000ffffffffffffffffffffffffffff;
+/// Exponent = 0b1, zeroed significand
+const SMALLEST_NORMAL_BITS: u128 = 0x00010000000000000000000000000000;
+/// First pattern over the mantissa
+const NAN_MASK1: u128 = 0x0000aaaaaaaaaaaaaaaaaaaaaaaaaaaa;
+/// Second pattern over the mantissa
+const NAN_MASK2: u128 = 0x00005555555555555555555555555555;
+
+/// Compare by value
+#[allow(unused_macros)]
+macro_rules! assert_f128_eq {
+    ($a:expr, $b:expr) => {
+        let (l, r): (&f128, &f128) = (&$a, &$b);
+        assert_eq!(*l, *r, "\na: {:#0130x}\nb: {:#0130x}", l.to_bits(), r.to_bits())
+    };
+}
+
+/// Compare by representation
+#[allow(unused_macros)]
+macro_rules! assert_f128_biteq {
+    ($a:expr, $b:expr) => {
+        let (l, r): (&f128, &f128) = (&$a, &$b);
+        let lb = l.to_bits();
+        let rb = r.to_bits();
+        assert_eq!(
+            lb, rb,
+            "float {:?} is not bitequal to {:?}.\na: {:#0130x}\nb: {:#0130x}",
+            *l, *r, lb, rb
+        );
+    };
+}

library/std/src/f16.rs

@@ -0,0 +1,11 @@
+//! Constants for the `f16` double-precision floating point type.
+//!
+//! *[See also the `f16` primitive type](primitive@f16).*
+//!
+//! Mathematically significant numbers are provided in the `consts` sub-module.
+
+#[cfg(test)]
+mod tests;
+
+#[unstable(feature = "f16", issue = "116909")]
+pub use core::f16::consts;