1 files changed, 137 insertions, 0 deletions
diff --git a/library/compiler-builtins/libm/src/math/sincos.rs b/library/compiler-builtins/libm/src/math/sincos.rs
new file mode 100644
index 00000000000..ebf482f2df3
--- /dev/null
+++ b/library/compiler-builtins/libm/src/math/sincos.rs
@@ -0,0 +1,137 @@
+/* origin: FreeBSD /usr/src/lib/msun/src/s_sin.c */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+use super::{get_high_word, k_cos, k_sin, rem_pio2};
+
+/// Both the sine and cosine of `x` (f64).
+///
+/// `x` is specified in radians and the return value is (sin(x), cos(x)).
+#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
+pub fn sincos(x: f64) -> (f64, f64) {
+    let s: f64;
+    let c: f64;
+    let mut ix: u32;
+
+    ix = get_high_word(x);
+    ix &= 0x7fffffff;
+
+    /* |x| ~< pi/4 */
+    if ix <= 0x3fe921fb {
+        /* if |x| < 2**-27 * sqrt(2) */
+        if ix < 0x3e46a09e {
+            /* raise inexact if x!=0 and underflow if subnormal */
+            let x1p120 = f64::from_bits(0x4770000000000000); // 0x1p120 == 2^120
+            if ix < 0x00100000 {
+                force_eval!(x / x1p120);
+            } else {
+                force_eval!(x + x1p120);
+            }
+            return (x, 1.0);
+        }
+        return (k_sin(x, 0.0, 0), k_cos(x, 0.0));
+    }
+
+    /* sincos(Inf or NaN) is NaN */
+    if ix >= 0x7ff00000 {
+        let rv = x - x;
+        return (rv, rv);
+    }
+
+    /* argument reduction needed */
+    let (n, y0, y1) = rem_pio2(x);
+    s = k_sin(y0, y1, 1);
+    c = k_cos(y0, y1);
+    match n & 3 {
+        0 => (s, c),
+        1 => (c, -s),
+        2 => (-s, -c),
+        3 => (-c, s),
+        #[cfg(debug_assertions)]
+        _ => unreachable!(),
+        #[cfg(not(debug_assertions))]
+        _ => (0.0, 1.0),
+    }
+}
+
+// These tests are based on those from sincosf.rs
+#[cfg(test)]
+mod tests {
+    use super::sincos;
+
+    const TOLERANCE: f64 = 1e-6;
+
+    #[test]
+    fn with_pi() {
+        let (s, c) = sincos(core::f64::consts::PI);
+        assert!(
+            (s - 0.0).abs() < TOLERANCE,
+            "|{} - {}| = {} >= {}",
+            s,
+            0.0,
+            (s - 0.0).abs(),
+            TOLERANCE
+        );
+        assert!(
+            (c + 1.0).abs() < TOLERANCE,
+            "|{} + {}| = {} >= {}",
+            c,
+            1.0,
+            (s + 1.0).abs(),
+            TOLERANCE
+        );
+    }
+
+    #[test]
+    fn rotational_symmetry() {
+        use core::f64::consts::PI;
+        const N: usize = 24;
+        for n in 0..N {
+            let theta = 2. * PI * (n as f64) / (N as f64);
+            let (s, c) = sincos(theta);
+            let (s_plus, c_plus) = sincos(theta + 2. * PI);
+            let (s_minus, c_minus) = sincos(theta - 2. * PI);
+
+            assert!(
+                (s - s_plus).abs() < TOLERANCE,
+                "|{} - {}| = {} >= {}",
+                s,
+                s_plus,
+                (s - s_plus).abs(),
+                TOLERANCE
+            );
+            assert!(
+                (s - s_minus).abs() < TOLERANCE,
+                "|{} - {}| = {} >= {}",
+                s,
+                s_minus,
+                (s - s_minus).abs(),
+                TOLERANCE
+            );
+            assert!(
+                (c - c_plus).abs() < TOLERANCE,
+                "|{} - {}| = {} >= {}",
+                c,
+                c_plus,
+                (c - c_plus).abs(),
+                TOLERANCE
+            );
+            assert!(
+                (c - c_minus).abs() < TOLERANCE,
+                "|{} - {}| = {} >= {}",
+                c,
+                c_minus,
+                (c - c_minus).abs(),
+                TOLERANCE
+            );
+        }
+    }
+}