[PATCH] Use intermediate variable to compute exponent in __mul and__sqr

[Siddhesh Poyarekar <siddhesh at redhat dot com>]

Hi,

Here's a tiny bit of optimization for __mul and __sqr that keeps the
values in a register during computation and then writes the result out
to EZ only once.  This gives about a 1% boost in performance.
Verified that it does not cause regressions on x86_64.  I've not
changed the ppc bits since I intend to post a separate patch to sync
up this part of code once this is in (and provided that the result is
positive for ppc as well).

OK to commit?

Siddhesh

	* sysdeps/ieee754/dbl-64/mpa.c (__mul): Use intermediate
	variable to calculate EZ.
	(__sqr): Likewise.

diff --git a/sysdeps/ieee754/dbl-64/mpa.c b/sysdeps/ieee754/dbl-64/mpa.c
index a5aace7..bbe9648 100644
--- a/sysdeps/ieee754/dbl-64/mpa.c
+++ b/sysdeps/ieee754/dbl-64/mpa.c
@@ -737,15 +737,16 @@ __mul (const mp_no *x, const mp_no *y, mp_no *z, int p)
     }
   Z[k] = zk;
 
-  EZ = EX + EY;
+  int e = EX + EY;
   /* Is there a carry beyond the most significant digit?  */
   if (__glibc_unlikely (Z[1] == ZERO))
     {
       for (i = 1; i <= p; i++)
 	Z[i] = Z[i + 1];
-      EZ--;
+      e--;
     }
 
+  EZ = e;
   Z[0] = X[0] * Y[0];
 }
 
@@ -830,14 +831,16 @@ __sqr (const mp_no *x, mp_no *y, int p)
   /* Squares are always positive.  */
   Y[0] = 1.0;
 
-  EY = 2 * EX;
+  int e = EX * 2;
   /* Is there a carry beyond the most significant digit?  */
   if (__glibc_unlikely (Y[1] == ZERO))
     {
       for (i = 1; i <= p; i++)
 	Y[i] = Y[i + 1];
-      EY--;
+      e--;
     }
+
+  EY = e;
 }
 
 /* Invert *X and store in *Y.  Relative error bound: