OpenE2K/glibc
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Optimize f_mod

Browse Source 
Branch prediction for the 32-bit implementation and a new optimized
64-bit implementation.
This commit is contained in:
Ulrich Drepper 2011-10-23 20:55:26 -04:00
parent 10d005f77f
commit 0275fff8a1
3 changed files with 113 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
ChangeLog
View File

@ -1,5 +1,9 @@
2011-10-23 Ulrich Drepper <drepper@gmail.com>
* sysdeps/ieee754/dbl-64/e_fmod.c (__ieee754_fmod): Add some branch
prediction.
* sysdeps/ieee754/dbl-64/wordsize-64/e_fmod.c: New file.
* string/strnlen.c: Don't define STRNLEN, reverse logic.
Remove unused variable magic_bits.
* sysdeps/i386/i686/multiarch/rtld-strnlen.c: New file.

11
sysdeps/ieee754/dbl-64/e_fmod.c
View File

@ -1,4 +1,3 @@
/* @(#)e_fmod.c 5.1 93/09/24 */
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
@ -44,7 +43,7 @@ __ieee754_fmod (double x, double y)
}
/* determine ix = ilogb(x) */
if(hx<0x00100000) { /* subnormal x */
if(__builtin_expect(hx<0x00100000, 0)) { /* subnormal x */
if(hx==0) {
for (ix = -1043, i=lx; i>0; i<<=1) ix -=1;
} else {
@ -53,7 +52,7 @@ __ieee754_fmod (double x, double y)
} else ix = (hx>>20)-1023;
/* determine iy = ilogb(y) */
if(hy<0x00100000) { /* subnormal y */
if(__builtin_expect(hy<0x00100000, 0)) { /* subnormal y */
if(hy==0) {
for (iy = -1043, i=ly; i>0; i<<=1) iy -=1;
} else {
@ -62,7 +61,7 @@ __ieee754_fmod (double x, double y)
} else iy = (hy>>20)-1023;
/* set up {hx,lx}, {hy,ly} and align y to x */
if(ix >= -1022)
if(__builtin_expect(ix >= -1022, 1))
hx = 0x00100000|(0x000fffff&hx);
else { /* subnormal x, shift x to normal */
n = -1022-ix;
@ -74,7 +73,7 @@ __ieee754_fmod (double x, double y)
lx = 0;
}
}
if(iy >= -1022)
if(__builtin_expect(iy >= -1022, 1))
hy = 0x00100000|(0x000fffff&hy);
else { /* subnormal y, shift y to normal */
n = -1022-iy;
@ -108,7 +107,7 @@ __ieee754_fmod (double x, double y)
hx = hx+hx+(lx>>31); lx = lx+lx;
iy -= 1;
}
if(iy>= -1022) { /* normalize output */
if(__builtin_expect(iy>= -1022, 1)) { /* normalize output */
hx = ((hx-0x00100000)|((iy+1023)<<20));
INSERT_WORDS(x,hx|sx,lx);
} else { /* subnormal output */

104
sysdeps/ieee754/dbl-64/wordsize-64/e_fmod.c Normal file
View File

@ -0,0 +1,104 @@
/* Rewritten for 64-bit machines by Ulrich Drepper <drepper@gmail.com>. */
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
/*
* __ieee754_fmod(x,y)
* Return x mod y in exact arithmetic
* Method: shift and subtract
*/
#include "math.h"
#include "math_private.h"
static const double one = 1.0, Zero[] = {0.0, -0.0,};
double
__ieee754_fmod (double x, double y)
{
int32_t n,i,ix,iy;
int64_t hx,hy,hz,sx;
EXTRACT_WORDS64(hx,x);
EXTRACT_WORDS64(hy,y);
sx = hx&UINT64_C(0x8000000000000000); /* sign of x */
hx ^=sx; /* |x| */
hy &= UINT64_C(0x7fffffffffffffff); /* |y| */
/* purge off exception values */
if(__builtin_expect(hy==0
|| hx >= UINT64_C(0x7ff0000000000000)
|| hy > UINT64_C(0x7ff0000000000000), 0))
/* y=0,or x not finite or y is NaN */
return (x*y)/(x*y);
if(__builtin_expect(hx<=hy, 0)) {
if(hx<hy) return x; /* |x|<|y| return x */
return Zero[(uint64_t)sx>>63]; /* |x|=|y| return x*0*/
}
/* determine ix = ilogb(x) */
if(__builtin_expect(hx<UINT64_C(0x0010000000000000), 0)) {
/* subnormal x */
for (ix = -1022,i=(hx<<11); i>0; i<<=1) ix -=1;
} else ix = (hx>>52)-1023;
/* determine iy = ilogb(y) */
if(__builtin_expect(hy<UINT64_C(0x0010000000000000), 0)) { /* subnormal y */
for (iy = -1022,i=(hy<<11); i>0; i<<=1) iy -=1;
} else iy = (hy>>52)-1023;
/* set up hx, hy and align y to x */
if(__builtin_expect(ix >= -1022, 1))
hx = UINT64_C(0x0010000000000000)|(UINT64_C(0x000fffffffffffff)&hx);
else { /* subnormal x, shift x to normal */
n = -1022-ix;
hx<<=n;
}
if(__builtin_expect(iy >= -1022, 1))
hy = UINT64_C(0x0010000000000000)|(UINT64_C(0x000fffffffffffff)&hy);
else { /* subnormal y, shift y to normal */
n = -1022-iy;
hy<<=n;
}
/* fix point fmod */
n = ix - iy;
while(n--) {
hz=hx-hy;
if(hz<0){hx = hx+hx;}
else {
if(hz==0) /* return sign(x)*0 */
return Zero[(uint64_t)sx>>63];
hx = hz+hz;
}
}
hz=hx-hy;
if(hz>=0) {hx=hz;}
/* convert back to floating value and restore the sign */
if(hx==0) /* return sign(x)*0 */
return Zero[(uint64_t)sx>>63];
while(hx<UINT64_C(0x0010000000000000)) { /* normalize x */
hx = hx+hx;
iy -= 1;
}
if(__builtin_expect(iy>= -1022, 1)) { /* normalize output */
hx = ((hx-UINT64_C(0x0010000000000000))|((uint64_t)(iy+1023)<<52));
INSERT_WORDS64(x,hx|sx);
} else { /* subnormal output */
n = -1022 - iy;
hx>>=n;
INSERT_WORDS64(x,hx|sx);
x *= one; /* create necessary signal */
}
return x; /* exact output */
}
strong_alias (__ieee754_fmod, __fmod_finite)