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Optimize the fixup for +-0 by using better classification for this case

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and by using a table lookup to avoid a branch when this case occurs.
On i386, this saves 1-4 cycles out of about 64 for non-large args.
This commit is contained in:
Bruce Evans 2008-02-22 10:04:53 +00:00
parent da9b9cd9dc
commit a7aa8cc980
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=176458
1 changed files with 4 additions and 2 deletions
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6
lib/msun/src/s_rintl.c
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@ -44,6 +44,7 @@ shift[2] = {
#error "Unsupported long double format"
#endif
};
static const float zero[2] = { 0.0, -0.0 };
long double
rintl(long double x)
@ -74,7 +75,8 @@ rintl(long double x)
* If the result is +-0, then it must have the same sign as x, but
* the above calculation doesn't always give this. Fix up the sign.
*/
if (x == 0.0L)
return (sign ? -0.0L : 0.0L);
if (u.bits.exp < BIAS && x == 0.0L)
return (zero[sign]);
return (x);
}