Eliminate redundant sign extensions in pow()

When looking at the code generated for pow() on ppc64 I noticed quite a few sign extensions. Making the array indices unsigned reduces the number of sign extensions from 24 to 7. Tested for powerpc64le and x86_64.
git-mirror · Jan 4, 2016 · 0a1f1e7 · 0a1f1e7
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diff --git a/ChangeLog b/ChangeLog
@@ -1,3 +1,9 @@
+2016-01-04  Anton Blanchard  <anton@samba.org>
+
+	* sysdeps/ieee754/dbl-64/e_pow.c (log1): Use unsigned int
+	for array indices.
+	* sysdeps/ieee754/dbl-64/e_pow.c (my_log2): Likewise.
+
 2016-01-04  Joseph Myers  <joseph@codesourcery.com>
 
 	* NEWS: Update copyright dates.

diff --git a/sysdeps/ieee754/dbl-64/e_pow.c b/sysdeps/ieee754/dbl-64/e_pow.c
@@ -245,7 +245,8 @@ static double
 SECTION
 log1 (double x, double *delta, double *error)
 {
-  int i, j, m;
+  unsigned int i, j;
+  int m;
   double uu, vv, eps, nx, e, e1, e2, t, t1, t2, res, add = 0;
   mynumber u, v;
 #ifdef BIG_ENDI
@@ -344,7 +345,8 @@ static double
 SECTION
 my_log2 (double x, double *delta, double *error)
 {
-  int i, j, m;
+  unsigned int i, j;
+  int m;
   double uu, vv, eps, nx, e, e1, e2, t, t1, t2, res, add = 0;
   double ou1, ou2, lu1, lu2, ov, lv1, lv2, a, a1, a2;
   double y, yy, z, zz, j1, j2, j7, j8;