Add intrinsics for floating-point min and max

3 files changed, 67 insertions, 36 deletions

diff --git a/src/libcore/intrinsics.rs b/src/libcore/intrinsics.rs
index 84867264e70..b609af16ffe 100644
--- a/src/libcore/intrinsics.rs
+++ b/src/libcore/intrinsics.rs
@@ -1051,6 +1051,19 @@ extern "rust-intrinsic" {
     /// Returns the absolute value of an `f64`.
     pub fn fabsf64(x: f64) -> f64;
 
+    /// Returns the minimum of two `f32` values.
+    #[cfg(not(bootstrap))]
+    pub fn minnumf32(x: f32, y: f32) -> f32;
+    /// Returns the minimum of two `f64` values.
+    #[cfg(not(bootstrap))]
+    pub fn minnumf64(x: f64, y: f64) -> f64;
+    /// Returns the maximum of two `f32` values.
+    #[cfg(not(bootstrap))]
+    pub fn maxnumf32(x: f32, y: f32) -> f32;
+    /// Returns the maximum of two `f64` values.
+    #[cfg(not(bootstrap))]
+    pub fn maxnumf64(x: f64, y: f64) -> f64;
+
     /// Copies the sign from `y` to `x` for `f32` values.
     pub fn copysignf32(x: f32, y: f32) -> f32;
     /// Copies the sign from `y` to `x` for `f64` values.
@@ -1561,3 +1574,47 @@ pub unsafe fn copy<T>(src: *const T, dst: *mut T, count: usize) {
 pub unsafe fn write_bytes<T>(dst: *mut T, val: u8, count: usize) {
     real_intrinsics::write_bytes(dst, val, count)
 }
+
+// Simple bootstrap implementations of minnum/maxnum for stage0 compilation.
+
+/// Returns the minimum of two `f32` values.
+#[cfg(bootstrap)]
+pub fn minnumf32(x: f32, y: f32) -> f32 {
+    // IEEE754 says: minNum(x, y) is the canonicalized number x if x < y, y if y < x, the
+    // canonicalized number if one operand is a number and the other a quiet NaN. Otherwise it
+    // is either x or y, canonicalized (this means results might differ among implementations).
+    // When either x or y is a signaling NaN, then the result is according to 6.2.
+    //
+    // Since we do not support sNaN in Rust yet, we do not need to handle them.
+    // FIXME(nagisa): due to https://bugs.llvm.org/show_bug.cgi?id=33303 we canonicalize by
+    // multiplying by 1.0. Should switch to the `canonicalize` when it works.
+    (if x < y || y != y { x } else { y }) * 1.0
+}
+
+/// Returns the minimum of two `f64` values.
+#[cfg(bootstrap)]
+pub fn minnumf64(x: f64, y: f64) -> f64 {
+    // Identical to the `f32` case.
+    (if x < y || y != y { x } else { y }) * 1.0
+}
+
+/// Returns the maximum of two `f32` values.
+#[cfg(bootstrap)]
+pub fn maxnumf32(x: f32, y: f32) -> f32 {
+    // IEEE754 says: maxNum(x, y) is the canonicalized number y if x < y, x if y < x, the
+    // canonicalized number if one operand is a number and the other a quiet NaN. Otherwise it
+    // is either x or y, canonicalized (this means results might differ among implementations).
+    // When either x or y is a signaling NaN, then the result is according to 6.2.
+    //
+    // Since we do not support sNaN in Rust yet, we do not need to handle them.
+    // FIXME(nagisa): due to https://bugs.llvm.org/show_bug.cgi?id=33303 we canonicalize by
+    // multiplying by 1.0. Should switch to the `canonicalize` when it works.
+    (if x < y || x != x { y } else { x }) * 1.0
+}
+
+/// Returns the maximum of two `f64` values.
+#[cfg(bootstrap)]
+pub fn maxnumf64(x: f64, y: f64) -> f64 {
+    // Identical to the `f32` case.
+    (if x < y || x != x { y } else { x }) * 1.0
+}
diff --git a/src/libcore/num/f32.rs b/src/libcore/num/f32.rs
index 3f8d142c845..0bcd371b528 100644
--- a/src/libcore/num/f32.rs
+++ b/src/libcore/num/f32.rs
@@ -7,6 +7,9 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
+#[cfg(not(test))]
+use crate::intrinsics;
+
 use crate::mem;
 use crate::num::FpCategory;
 
@@ -372,15 +375,7 @@ impl f32 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn max(self, other: f32) -> f32 {
-        // IEEE754 says: maxNum(x, y) is the canonicalized number y if x < y, x if y < x, the
-        // canonicalized number if one operand is a number and the other a quiet NaN. Otherwise it
-        // is either x or y, canonicalized (this means results might differ among implementations).
-        // When either x or y is a signalingNaN, then the result is according to 6.2.
-        //
-        // Since we do not support sNaN in Rust yet, we do not need to handle them.
-        // FIXME(nagisa): due to https://bugs.llvm.org/show_bug.cgi?id=33303 we canonicalize by
-        // multiplying by 1.0. Should switch to the `canonicalize` when it works.
-        (if self.is_nan() || self < other { other } else { self }) * 1.0
+        intrinsics::maxnumf32(self, other)
     }
 
     /// Returns the minimum of the two numbers.
@@ -396,15 +391,7 @@ impl f32 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn min(self, other: f32) -> f32 {
-        // IEEE754 says: minNum(x, y) is the canonicalized number x if x < y, y if y < x, the
-        // canonicalized number if one operand is a number and the other a quiet NaN. Otherwise it
-        // is either x or y, canonicalized (this means results might differ among implementations).
-        // When either x or y is a signalingNaN, then the result is according to 6.2.
-        //
-        // Since we do not support sNaN in Rust yet, we do not need to handle them.
-        // FIXME(nagisa): due to https://bugs.llvm.org/show_bug.cgi?id=33303 we canonicalize by
-        // multiplying by 1.0. Should switch to the `canonicalize` when it works.
-        (if other.is_nan() || self < other { self } else { other }) * 1.0
+        intrinsics::minnumf32(self, other)
     }
 
     /// Raw transmutation to `u32`.
diff --git a/src/libcore/num/f64.rs b/src/libcore/num/f64.rs
index 7f19101fe6e..4d4a2c9c5a9 100644
--- a/src/libcore/num/f64.rs
+++ b/src/libcore/num/f64.rs
@@ -7,6 +7,9 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
+#[cfg(not(test))]
+use crate::intrinsics;
+
 use crate::mem;
 use crate::num::FpCategory;
 
@@ -385,15 +388,7 @@ impl f64 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn max(self, other: f64) -> f64 {
-        // IEEE754 says: maxNum(x, y) is the canonicalized number y if x < y, x if y < x, the
-        // canonicalized number if one operand is a number and the other a quiet NaN. Otherwise it
-        // is either x or y, canonicalized (this means results might differ among implementations).
-        // When either x or y is a signalingNaN, then the result is according to 6.2.
-        //
-        // Since we do not support sNaN in Rust yet, we do not need to handle them.
-        // FIXME(nagisa): due to https://bugs.llvm.org/show_bug.cgi?id=33303 we canonicalize by
-        // multiplying by 1.0. Should switch to the `canonicalize` when it works.
-        (if self.is_nan() || self < other { other } else { self }) * 1.0
+        intrinsics::maxnumf64(self, other)
     }
 
     /// Returns the minimum of the two numbers.
@@ -409,15 +404,7 @@ impl f64 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn min(self, other: f64) -> f64 {
-        // IEEE754 says: minNum(x, y) is the canonicalized number x if x < y, y if y < x, the
-        // canonicalized number if one operand is a number and the other a quiet NaN. Otherwise it
-        // is either x or y, canonicalized (this means results might differ among implementations).
-        // When either x or y is a signalingNaN, then the result is according to 6.2.
-        //
-        // Since we do not support sNaN in Rust yet, we do not need to handle them.
-        // FIXME(nagisa): due to https://bugs.llvm.org/show_bug.cgi?id=33303 we canonicalize by
-        // multiplying by 1.0. Should switch to the `canonicalize` when it works.
-        (if other.is_nan() || self < other { self } else { other }) * 1.0
+        intrinsics::minnumf64(self, other)
     }
 
     /// Raw transmutation to `u64`.