[PATCH] libm -- optimize __ldexp_cexp[f]

[Steve Kargl]

The following patch is an opimization for he kernels
used by cexp(x) and cexpf(x).

. Use sincos[f] instead of a call to cos[f] and a 
  call to sin[f].
. While here, alphabetize declaration.

--- /usr/src/lib/msun/src/k_exp.c       2019-02-23 07:45:03.879997000 -0800
+++ src/k_exp.c 2019-12-26 08:15:30.109189000 -0800
@@ -88,7 +88,7 @@
 double complex
 __ldexp_cexp(double complex z, int expt)
 {
-       double x, y, exp_x, scale1, scale2;
+       double c, exp_x, s, scale1, scale2, x, y;
        int ex_expt, half_expt;
 
        x = creal(z);
@@ -105,6 +105,7 @@
        half_expt = expt - half_expt;
        INSERT_WORDS(scale2, (0x3ff + half_expt) << 20, 0);
 
-       return (CMPLX(cos(y) * exp_x * scale1 * scale2,
-           sin(y) * exp_x * scale1 * scale2));
+       sincos(y, &s, &c);
+       return (CMPLX(c * exp_x * scale1 * scale2,
+           s * exp_x * scale1 * scale2));
 }
--- /usr/src/lib/msun/src/k_expf.c      2019-02-23 07:45:03.881215000 -0800
+++ src/k_expf.c        2019-12-26 08:15:30.109818000 -0800
@@ -71,7 +71,7 @@
 float complex
 __ldexp_cexpf(float complex z, int expt)
 {
-       float x, y, exp_x, scale1, scale2;
+       float c, exp_x, s, scale1, scale2, x, y;
        int ex_expt, half_expt;
 
        x = crealf(z);
@@ -84,6 +84,7 @@
        half_expt = expt - half_expt;
        SET_FLOAT_WORD(scale2, (0x7f + half_expt) << 23);
 
-       return (CMPLXF(cosf(y) * exp_x * scale1 * scale2,
-           sinf(y) * exp_x * scale1 * scale2));
+       sincosf(y, &s, &c);
+       return (CMPLXF(c * exp_x * scale1 * scale2,
+           s * exp_x * scale1 * scale2));
 }

-- 
Steve
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