1 files changed, 46 insertions, 0 deletions
diff --git a/vendor/compiler_builtins/libm/src/math/k_tanf.rs b/vendor/compiler_builtins/libm/src/math/k_tanf.rs
new file mode 100644
index 000000000..af8db539d
--- /dev/null
+++ b/vendor/compiler_builtins/libm/src/math/k_tanf.rs
@@ -0,0 +1,46 @@
+/* origin: FreeBSD /usr/src/lib/msun/src/k_tan.c */
+/*
+ * ====================================================
+ * Copyright 2004 Sun Microsystems, Inc.  All Rights Reserved.
+ *
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+/* |tan(x)/x - t(x)| < 2**-25.5 (~[-2e-08, 2e-08]). */
+const T: [f64; 6] = [
+    0.333331395030791399758,   /* 0x15554d3418c99f.0p-54 */
+    0.133392002712976742718,   /* 0x1112fd38999f72.0p-55 */
+    0.0533812378445670393523,  /* 0x1b54c91d865afe.0p-57 */
+    0.0245283181166547278873,  /* 0x191df3908c33ce.0p-58 */
+    0.00297435743359967304927, /* 0x185dadfcecf44e.0p-61 */
+    0.00946564784943673166728, /* 0x1362b9bf971bcd.0p-59 */
+];
+
+#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
+pub(crate) fn k_tanf(x: f64, odd: bool) -> f32 {
+    let z = x * x;
+    /*
+     * Split up the polynomial into small independent terms to give
+     * opportunities for parallel evaluation.  The chosen splitting is
+     * micro-optimized for Athlons (XP, X64).  It costs 2 multiplications
+     * relative to Horner's method on sequential machines.
+     *
+     * We add the small terms from lowest degree up for efficiency on
+     * non-sequential machines (the lowest degree terms tend to be ready
+     * earlier).  Apart from this, we don't care about order of
+     * operations, and don't need to to care since we have precision to
+     * spare.  However, the chosen splitting is good for accuracy too,
+     * and would give results as accurate as Horner's method if the
+     * small terms were added from highest degree down.
+     */
+    let mut r = T[4] + z * T[5];
+    let t = T[2] + z * T[3];
+    let w = z * z;
+    let s = z * x;
+    let u = T[0] + z * T[1];
+    r = (x + s * u) + (s * w) * (t + w * r);
+    (if odd { -1. / r } else { r }) as f32
+}