Remove some redundant computations in s_sin.c

There are multiple points in the code where the absolute value of a
number is computed multiple times or is computed even though the value
can only be positive.  This change removes those redundant
computations.  Tested on x86_64 to verify that there were no
regressions in the testsuite.

diff --git a/ChangeLog b/ChangeLog
index 9ebb675..a8dab6d 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2013-12-20  Siddhesh Poyarekar  <siddhesh@redhat.com>
+
+       * sysdeps/ieee754/dbl-64/s_sin.c (__sin): Use DA directly.
+       (__cos): Likewise.
+       (sloww1): Don't adjust sign of DX.
+       (csloww1): Likewise.
+       (sloww2): Use X directly and don't adjust sign of DX.
+       (csloww2): Likewise.
+
 2013-12-19  Joseph Myers  <joseph@codesourcery.com>
 
        * math/auto-libm-test-in: Add tests of cabs and carg.

diff --git a/sysdeps/ieee754/dbl-64/s_sin.c b/sysdeps/ieee754/dbl-64/s_sin.c
index 9066667..4e2ac3d 100644 (file)
--- a/sysdeps/ieee754/dbl-64/s_sin.c
+++ b/sysdeps/ieee754/dbl-64/s_sin.c
@@ -290,19 +290,18 @@ __sin (double x)
                {
                  m = 1;
                  t = a;
-                 db = da;
                }
              else
                {
                  m = 0;
                  t = -a;
-                 db = -da;
+                 da = -da;
                }
              u.x = big + t;
              y = t - (u.x - big);
              xx = y * y;
-             s = y + (db + y * xx * (sn3 + xx * sn5));
-             c = y * db + xx * (cs2 + xx * (cs4 + xx * cs6));
+             s = y + (da + y * xx * (sn3 + xx * sn5));
+             c = y * da + xx * (cs2 + xx * (cs4 + xx * cs6));
              SINCOS_TABLE_LOOKUP (u, sn, ssn, cs, ccs);
              cor = (ssn + s * ccs - sn * c) + cs * s;
              res = sn + cor;
@@ -498,19 +497,18 @@ __cos (double x)
            {
              m = 1;
              t = a;
-             db = da;
            }
          else
            {
              m = 0;
              t = -a;
-             db = -da;
+             da = -da;
            }
          u.x = big + t;
          y = t - (u.x - big);
          xx = y * y;
-         s = y + (db + y * xx * (sn3 + xx * sn5));
-         c = y * db + xx * (cs2 + xx * (cs4 + xx * cs6));
+         s = y + (da + y * xx * (sn3 + xx * sn5));
+         c = y * da + xx * (cs2 + xx * (cs4 + xx * cs6));
          SINCOS_TABLE_LOOKUP (u, sn, ssn, cs, ccs);
          cor = (ssn + s * ccs - sn * c) + cs * s;
          res = sn + cor;
@@ -557,19 +555,18 @@ __cos (double x)
                {
                  m = 1;
                  t = a;
-                 db = da;
                }
              else
                {
                  m = 0;
                  t = -a;
-                 db = -da;
+                 da = -da;
                }
              u.x = big + t;
              y = t - (u.x - big);
              xx = y * y;
-             s = y + (db + y * xx * (sn3 + xx * sn5));
-             c = y * db + xx * (cs2 + xx * (cs4 + xx * cs6));
+             s = y + (da + y * xx * (sn3 + xx * sn5));
+             c = y * da + xx * (cs2 + xx * (cs4 + xx * cs6));
              SINCOS_TABLE_LOOKUP (u, sn, ssn, cs, ccs);
              cor = (ssn + s * ccs - sn * c) + cs * s;
              res = sn + cor;
@@ -899,7 +896,6 @@ sloww1 (double x, double dx, double orig)
   y = ABS (x);
   u.x = big + y;
   y = y - (u.x - big);
-  dx = (x > 0) ? dx : -dx;
   xx = y * y;
   s = y * xx * (sn3 + xx * sn5);
   c = xx * (cs2 + xx * (cs4 + xx * cs6));
@@ -951,10 +947,8 @@ sloww2 (double x, double dx, double orig, int n)
   mynumber u;
   double sn, ssn, cs, ccs, s, c, w[2], y, y1, y2, e1, e2, xx, cor, res;
 
-  y = ABS (x);
-  u.x = big + y;
-  y = y - (u.x - big);
-  dx = (x > 0) ? dx : -dx;
+  u.x = big + x;
+  y = x - (u.x - big);
   xx = y * y;
   s = y * xx * (sn3 + xx * sn5);
   c = y * dx + xx * (cs2 + xx * (cs4 + xx * cs6));
@@ -979,7 +973,7 @@ sloww2 (double x, double dx, double orig, int n)
     return (n & 2) ? -res : res;
   else
     {
-      __docos (ABS (x), dx, w);
+      __docos (x, dx, w);
 
       if (w[1] > 0)
        cor = 1.000000005 * w[1] + 1.1e-30 * ABS (orig);
@@ -1254,7 +1248,6 @@ csloww1 (double x, double dx, double orig)
   y = ABS (x);
   u.x = big + y;
   y = y - (u.x - big);
-  dx = (x > 0) ? dx : -dx;
   xx = y * y;
   s = y * xx * (sn3 + xx * sn5);
   c = xx * (cs2 + xx * (cs4 + xx * cs6));
@@ -1305,10 +1298,8 @@ csloww2 (double x, double dx, double orig, int n)
   mynumber u;
   double sn, ssn, cs, ccs, s, c, w[2], y, y1, y2, e1, e2, xx, cor, res;
 
-  y = ABS (x);
-  u.x = big + y;
-  y = y - (u.x - big);
-  dx = (x > 0) ? dx : -dx;
+  u.x = big + x;
+  y = x - (u.x - big);
   xx = y * y;
   s = y * xx * (sn3 + xx * sn5);
   c = y * dx + xx * (cs2 + xx * (cs4 + xx * cs6));
@@ -1333,7 +1324,7 @@ csloww2 (double x, double dx, double orig, int n)
     return (n) ? -res : res;
   else
     {
-      __docos (ABS (x), dx, w);
+      __docos (x, dx, w);
       if (w[1] > 0)
        cor = 1.000000005 * w[1] + 1.1e-30 * ABS (orig);
       else