Revert "Eliminate the use of public_test_dep!"

[1] has not gone forward, so this needs to be reverted again in order to
unblock a compiler-builtins upgrade that is necessary for the LLVM 20
upgrade.

This reverts commit a2494f14e99ae90c964f12bf0c059d63ccc07c2a.

[1]: rust-lang#135501

Author: tgross35

compiler-builtins/src/float/mod.rs

@@ -1,3 +1,7 @@
+use core::ops;
+
+use crate::int::{DInt, Int, MinInt};
+
 pub mod add;
 pub mod cmp;
 pub mod conv;
@@ -6,11 +10,192 @@ pub mod extend;
 pub mod mul;
 pub mod pow;
 pub mod sub;
-pub(crate) mod traits;
 pub mod trunc;
 
-#[cfg(not(feature = "public-test-deps"))]
-pub(crate) use traits::{Float, HalfRep};
+/// Wrapper to extract the integer type half of the float's size
+pub(crate) type HalfRep<F> = <<F as Float>::Int as DInt>::H;
+
+public_test_dep! {
+/// Trait for some basic operations on floats
+#[allow(dead_code)]
+pub(crate) trait Float:
+    Copy
+    + core::fmt::Debug
+    + PartialEq
+    + PartialOrd
+    + ops::AddAssign
+    + ops::MulAssign
+    + ops::Add<Output = Self>
+    + ops::Sub<Output = Self>
+    + ops::Div<Output = Self>
+    + ops::Rem<Output = Self>
+{
+    /// A uint of the same width as the float
+    type Int: Int<OtherSign = Self::SignedInt, UnsignedInt = Self::Int>;
+
+    /// A int of the same width as the float
+    type SignedInt: Int + MinInt<OtherSign = Self::Int, UnsignedInt = Self::Int>;
+
+    /// An int capable of containing the exponent bits plus a sign bit. This is signed.
+    type ExpInt: Int;
+
+    const ZERO: Self;
+    const ONE: Self;
+
+    /// The bitwidth of the float type.
+    const BITS: u32;
+
+    /// The bitwidth of the significand.
+    const SIG_BITS: u32;
+
+    /// The bitwidth of the exponent.
+    const EXP_BITS: u32 = Self::BITS - Self::SIG_BITS - 1;
+
+    /// The saturated (maximum bitpattern) value of the exponent, i.e. the infinite
+    /// representation.
+    ///
+    /// This is in the rightmost position, use `EXP_MASK` for the shifted value.
+    const EXP_SAT: u32 = (1 << Self::EXP_BITS) - 1;
+
+    /// The exponent bias value.
+    const EXP_BIAS: u32 = Self::EXP_SAT >> 1;
+
+    /// A mask for the sign bit.
+    const SIGN_MASK: Self::Int;
+
+    /// A mask for the significand.
+    const SIG_MASK: Self::Int;
+
+    /// The implicit bit of the float format.
+    const IMPLICIT_BIT: Self::Int;
+
+    /// A mask for the exponent.
+    const EXP_MASK: Self::Int;
+
+    /// Returns `self` transmuted to `Self::Int`
+    fn to_bits(self) -> Self::Int;
+
+    /// Returns `self` transmuted to `Self::SignedInt`
+    fn to_bits_signed(self) -> Self::SignedInt;
+
+    /// Checks if two floats have the same bit representation. *Except* for NaNs! NaN can be
+    /// represented in multiple different ways. This method returns `true` if two NaNs are
+    /// compared.
+    fn eq_repr(self, rhs: Self) -> bool;
+
+    /// Returns true if the sign is negative
+    fn is_sign_negative(self) -> bool;
+
+    /// Returns the exponent, not adjusting for bias.
+    fn exp(self) -> Self::ExpInt;
+
+    /// Returns the significand with no implicit bit (or the "fractional" part)
+    fn frac(self) -> Self::Int;
+
+    /// Returns the significand with implicit bit
+    fn imp_frac(self) -> Self::Int;
+
+    /// Returns a `Self::Int` transmuted back to `Self`
+    fn from_bits(a: Self::Int) -> Self;
+
+    /// Constructs a `Self` from its parts. Inputs are treated as bits and shifted into position.
+    fn from_parts(negative: bool, exponent: Self::Int, significand: Self::Int) -> Self;
+
+    fn abs(self) -> Self {
+        let abs_mask = !Self::SIGN_MASK ;
+        Self::from_bits(self.to_bits() & abs_mask)
+    }
+
+    /// Returns (normalized exponent, normalized significand)
+    fn normalize(significand: Self::Int) -> (i32, Self::Int);
+
+    /// Returns if `self` is subnormal
+    fn is_subnormal(self) -> bool;
+}
+}
+
+macro_rules! float_impl {
+    ($ty:ident, $ity:ident, $sity:ident, $expty:ident, $bits:expr, $significand_bits:expr) => {
+        impl Float for $ty {
+            type Int = $ity;
+            type SignedInt = $sity;
+            type ExpInt = $expty;
+
+            const ZERO: Self = 0.0;
+            const ONE: Self = 1.0;
+
+            const BITS: u32 = $bits;
+            const SIG_BITS: u32 = $significand_bits;
+
+            const SIGN_MASK: Self::Int = 1 << (Self::BITS - 1);
+            const SIG_MASK: Self::Int = (1 << Self::SIG_BITS) - 1;
+            const IMPLICIT_BIT: Self::Int = 1 << Self::SIG_BITS;
+            const EXP_MASK: Self::Int = !(Self::SIGN_MASK | Self::SIG_MASK);
+
+            fn to_bits(self) -> Self::Int {
+                self.to_bits()
+            }
+            fn to_bits_signed(self) -> Self::SignedInt {
+                self.to_bits() as Self::SignedInt
+            }
+            fn eq_repr(self, rhs: Self) -> bool {
+                #[cfg(feature = "mangled-names")]
+                fn is_nan(x: $ty) -> bool {
+                    // When using mangled-names, the "real" compiler-builtins might not have the
+                    // necessary builtin (__unordtf2) to test whether `f128` is NaN.
+                    // FIXME(f16_f128): Remove once the nightly toolchain has the __unordtf2 builtin
+                    // x is NaN if all the bits of the exponent are set and the significand is non-0
+                    x.to_bits() & $ty::EXP_MASK == $ty::EXP_MASK && x.to_bits() & $ty::SIG_MASK != 0
+                }
+                #[cfg(not(feature = "mangled-names"))]
+                fn is_nan(x: $ty) -> bool {
+                    x.is_nan()
+                }
+                if is_nan(self) && is_nan(rhs) {
+                    true
+                } else {
+                    self.to_bits() == rhs.to_bits()
+                }
+            }
+            fn is_sign_negative(self) -> bool {
+                self.is_sign_negative()
+            }
+            fn exp(self) -> Self::ExpInt {
+                ((self.to_bits() & Self::EXP_MASK) >> Self::SIG_BITS) as Self::ExpInt
+            }
+            fn frac(self) -> Self::Int {
+                self.to_bits() & Self::SIG_MASK
+            }
+            fn imp_frac(self) -> Self::Int {
+                self.frac() | Self::IMPLICIT_BIT
+            }
+            fn from_bits(a: Self::Int) -> Self {
+                Self::from_bits(a)
+            }
+            fn from_parts(negative: bool, exponent: Self::Int, significand: Self::Int) -> Self {
+                Self::from_bits(
+                    ((negative as Self::Int) << (Self::BITS - 1))
+                        | ((exponent << Self::SIG_BITS) & Self::EXP_MASK)
+                        | (significand & Self::SIG_MASK),
+                )
+            }
+            fn normalize(significand: Self::Int) -> (i32, Self::Int) {
+                let shift = significand.leading_zeros().wrapping_sub(Self::EXP_BITS);
+                (
+                    1i32.wrapping_sub(shift as i32),
+                    significand << shift as Self::Int,
+                )
+            }
+            fn is_subnormal(self) -> bool {
+                (self.to_bits() & Self::EXP_MASK) == Self::Int::ZERO
+            }
+        }
+    };
+}
 
-#[cfg(feature = "public-test-deps")]
-pub use traits::{Float, HalfRep};
+#[cfg(f16_enabled)]
+float_impl!(f16, u16, i16, i8, 16, 10);
+float_impl!(f32, u32, i32, i16, 32, 23);
+float_impl!(f64, u64, i64, i16, 64, 52);
+#[cfg(f128_enabled)]
+float_impl!(f128, u128, i128, i16, 128, 112);