Implement copysign for libcalls

Author: workingjubilee

src/float/bitops.rs

@@ -0,0 +1,54 @@
+// FIXME: This module existing reflects a failure of the codegen backend to always legalize bitops.
+// LLVM should be taught how to always emit llvm.fcopysign for f{16,32,64,128} without needing this!
+
+// FIXME: delete when we move fabs to core and it reaches stable
+fn fabs_f32(f: f32) -> f32 {
+    f32::from_bits(f.to_bits() & const { !(i32::MIN as u32) })
+}
+
+// FIXME: delete when we move fabs to core and it reaches stable
+fn fabs_f64(f: f64) -> f64 {
+    f64::from_bits(f.to_bits() & const { !(i64::MIN as u64) })
+}
+
+// FIXME: delete when we move fabs to core and it reaches stable
+fn fabs_128(f: f128) -> f128 {
+    f128::from_bits(f.to_bits() & const { !(i128::MIN as u128) })
+}
+
+fn copysign_f32(magnitude: f32, sign: f32) -> f32 {
+    let sign = fabs_f32(sign).to_bits() ^ sign.to_bits();
+    f32::from_bits(fabs_f32(magnitude).to_bits() | sign)
+}
+
+fn copysign_f64(magnitude: f64, sign: f64) -> f64 {
+    let sign = fabs_f64(sign).to_bits() ^ sign.to_bits();
+    f64::from_bits(fabs_f64(magnitude).to_bits() | sign)
+}
+
+fn copysign_f128(magnitude: f128, sign: f128) -> f128 {
+    let sign = fabs_128(sign).to_bits() ^ sign.to_bits();
+    f128::from_bits(fabs_128(magnitude).to_bits() | sign)
+}
+
+intrinsics! {
+    #[cfg_attr(target_env = "msvc", link_name = "_fcopysign")]
+    pub extern "C" fn fcopysign(magnitude: f32, sign: f32) -> f32 {
+        copysign_f32(magnitude, sign)
+    }
+
+    #[cfg_attr(target_env = "msvc", link_name = "_copysign")]
+    pub extern "C" fn copysign(magnitude: f64, sign: f64) -> f64 {
+        copysign_f64(magnitude, sign)
+    }
+
+    #[cfg(not(any(target_arch = "x86", target_arch = "x86_64", target_arch = "powerpc", target_arch = "powerpc64")))]
+    pub extern "C" fn copysignl(magnitude: f128, sign: f128) -> f128 {
+        copysign_f128(magnitude, sign)
+    }
+
+    #[cfg(any(target_arch = "x86_64", target_arch = "x86_64", target_arch = "powerpc", target_arch = "powerpc64"))]
+    pub extern "C" fn copysignf128(magnitude: f128, sign: f128) -> f128 {
+        copysign_f128(magnitude, sign)
+    }
+}

src/float/mod.rs

@@ -3,6 +3,7 @@ use core::ops;
 use crate::int::{DInt, Int, MinInt};
 
 pub mod add;
+pub mod bitops;
 pub mod cmp;
 pub mod conv;
 pub mod div;