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Optimize scalbln
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Ulrich Drepper committed Jan 11, 2012
1 parent 5452bff commit 41d0e86
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9 changes: 8 additions & 1 deletion ChangeLog
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@@ -1,3 +1,10 @@
2012-01-11 Ulrich Drepper <drepper@gmail.com>

* sysdeps/ieee754/dbl-64/s_scalbln.c: Add branch prediction.
* sysdeps/ieee754/flt-32/s_scalblnf.c: Likewise.
* sysdeps/ieee754/ldbl-96/s_scalblnl.c: Likewise.
* sysdeps/ieee754/dbl-64/wordsize-64/s_scalbln.c: New file.

2012-01-10 Ulrich Drepper <drepper@gmail.com>

* sysdeps/ieee754/dbl-64/wordsize-64/s_modf.c: New file.
Expand All @@ -9,9 +16,9 @@
* math/bits/mathcalls.h: Add const attribute to fmin and fmax.

* sysdeps/ieee754/dbl-64/s_scalbn.c: Add branch prediction.
* sysdeps/ieee754/dbl-64/wordsize-64/s_scalbn.c: Likewise.
* sysdeps/ieee754/flt-32/s_scalbnf.c: Likewise.
* sysdeps/ieee754/ldbl-96/s_scalbnl.c: Likewise.
* sysdeps/ieee754/dbl-64/wordsize-64/s_scalbn.c: New file.

* math/bits/math-finite.h: Add ldexp support.

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40 changes: 14 additions & 26 deletions sysdeps/ieee754/dbl-64/s_scalbln.c
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@@ -1,4 +1,3 @@
/* @(#)s_scalbn.c 5.1 93/09/24 */
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
Expand All @@ -10,10 +9,6 @@
* ====================================================
*/

#if defined(LIBM_SCCS) && !defined(lint)
static char rcsid[] = "$NetBSD: s_scalbn.c,v 1.8 1995/05/10 20:48:08 jtc Exp $";
#endif

/*
* scalbn (double x, int n)
* scalbn(x,n) returns x* 2**n computed by exponent
Expand All @@ -24,44 +19,37 @@ static char rcsid[] = "$NetBSD: s_scalbn.c,v 1.8 1995/05/10 20:48:08 jtc Exp $";
#include "math.h"
#include "math_private.h"

#ifdef __STDC__
static const double
#else
static double
#endif
two54 = 1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
twom54 = 5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */
huge = 1.0e+300,
tiny = 1.0e-300;

#ifdef __STDC__
double __scalbln (double x, long int n)
#else
double __scalbln (x,n)
double x; long int n;
#endif
double
__scalbln (double x, long int n)
{
int32_t k,hx,lx;
EXTRACT_WORDS(hx,lx,x);
k = (hx&0x7ff00000)>>20; /* extract exponent */
if (k==0) { /* 0 or subnormal x */
if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */
k = (hx&0x7ff00000)>>20; /* extract exponent */
if (__builtin_expect(k==0, 0)) { /* 0 or subnormal x */
if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */
x *= two54;
GET_HIGH_WORD(hx,x);
k = ((hx&0x7ff00000)>>20) - 54;
}
if (k==0x7ff) return x+x; /* NaN or Inf */
k = k+n;
if (n> 50000 || k > 0x7fe)
if (__builtin_expect(k==0x7ff, 0)) return x+x; /* NaN or Inf */
k = k+n;
if (__builtin_expect(n> 50000 || k > 0x7fe, 0))
return huge*__copysign(huge,x); /* overflow */
if (n< -50000) return tiny*__copysign(tiny,x); /*underflow*/
if (k > 0) /* normal result */
if (__builtin_expect(n< -50000, 0))
return tiny*__copysign(tiny,x); /*underflow*/
if (__builtin_expect(k > 0, 1)) /* normal result */
{SET_HIGH_WORD(x,(hx&0x800fffff)|(k<<20)); return x;}
if (k <= -54)
if (k <= -54)
return tiny*__copysign(tiny,x); /*underflow*/
k += 54; /* subnormal result */
k += 54; /* subnormal result */
SET_HIGH_WORD(x,(hx&0x800fffff)|(k<<20));
return x*twom54;
return x*twom54;
}
weak_alias (__scalbln, scalbln)
#ifdef NO_LONG_DOUBLE
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60 changes: 60 additions & 0 deletions sysdeps/ieee754/dbl-64/wordsize-64/s_scalbln.c
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@@ -0,0 +1,60 @@
/*
* ====================================================
* 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.
* ====================================================
*/

/*
* scalbn (double x, int n)
* scalbn(x,n) returns x* 2**n computed by exponent
* manipulation rather than by actually performing an
* exponentiation or a multiplication.
*/

#include "math.h"
#include "math_private.h"

static const double
two54 = 1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
twom54 = 5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */
huge = 1.0e+300,
tiny = 1.0e-300;

double
__scalbln (double x, long int n)
{
int64_t ix;
int64_t k;
EXTRACT_WORDS64(ix,x);
k = (ix >> 52) & 0x7ff; /* extract exponent */
if (__builtin_expect(k==0, 0)) { /* 0 or subnormal x */
if ((ix & UINT64_C(0xfffffffffffff))==0) return x; /* +-0 */
x *= two54;
EXTRACT_WORDS64(ix,x);
k = ((ix >> 52) & 0x7ff) - 54;
}
if (__builtin_expect(k==0x7ff, 0)) return x+x; /* NaN or Inf */
k = k+n;
if (__builtin_expect(n> 50000 || k > 0x7fe, 0))
return huge*__copysign(huge,x); /* overflow */
if (__builtin_expect(n< -50000, 0))
return tiny*__copysign(tiny,x); /*underflow*/
if (__builtin_expect(k > 0, 1)) /* normal result */
{INSERT_WORDS64(x,(ix&UINT64_C(0x800fffffffffffff))|(k<<52));
return x;}
if (k <= -54)
return tiny*__copysign(tiny,x); /*underflow*/
k += 54; /* subnormal result */
INSERT_WORDS64(x,(ix&INT64_C(0x800fffffffffffff))|(k<<52));
return x*twom54;
}
weak_alias (__scalbln, scalbln)
#ifdef NO_LONG_DOUBLE
strong_alias (__scalbln, __scalblnl)
weak_alias (__scalbln, scalblnl)
#endif
38 changes: 13 additions & 25 deletions sysdeps/ieee754/flt-32/s_scalblnf.c
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Expand Up @@ -13,51 +13,39 @@
* ====================================================
*/

#if defined(LIBM_SCCS) && !defined(lint)
static char rcsid[] = "$NetBSD: s_scalbnf.c,v 1.4 1995/05/10 20:48:10 jtc Exp $";
#endif

#include "math.h"
#include "math_private.h"

#ifdef __STDC__
static const float
#else
static float
#endif
two25 = 3.355443200e+07, /* 0x4c000000 */
twom25 = 2.9802322388e-08, /* 0x33000000 */
huge = 1.0e+30,
tiny = 1.0e-30;

#ifdef __STDC__
float __scalblnf (float x, long int n)
#else
float __scalblnf (x,n)
float x; long int n;
#endif
float
__scalblnf (float x, long int n)
{
int32_t k,ix;
GET_FLOAT_WORD(ix,x);
k = (ix&0x7f800000)>>23; /* extract exponent */
if (k==0) { /* 0 or subnormal x */
if ((ix&0x7fffffff)==0) return x; /* +-0 */
k = (ix&0x7f800000)>>23; /* extract exponent */
if (__builtin_expect(k==0, 0)) { /* 0 or subnormal x */
if ((ix&0x7fffffff)==0) return x; /* +-0 */
x *= two25;
GET_FLOAT_WORD(ix,x);
k = ((ix&0x7f800000)>>23) - 25;
}
if (k==0xff) return x+x; /* NaN or Inf */
k = k+n;
if (n> 50000 || k > 0xfe)
if (__builtin_expect(k==0xff, 0)) return x+x; /* NaN or Inf */
k = k+n;
if (__builtin_expect(n> 50000 || k > 0xfe, 0))
return huge*copysignf(huge,x); /* overflow */
if (n< -50000)
if (__builtin_expect(n< -50000, 0))
return tiny*copysignf(tiny,x); /*underflow*/
if (k > 0) /* normal result */
if (__builtin_expect(k > 0, 1)) /* normal result */
{SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); return x;}
if (k <= -25)
if (k <= -25)
return tiny*copysignf(tiny,x); /*underflow*/
k += 25; /* subnormal result */
k += 25; /* subnormal result */
SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23));
return x*twom25;
return x*twom25;
}
weak_alias (__scalblnf, scalblnf)
38 changes: 13 additions & 25 deletions sysdeps/ieee754/ldbl-96/s_scalblnl.c
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Expand Up @@ -14,10 +14,6 @@
* ====================================================
*/

#if defined(LIBM_SCCS) && !defined(lint)
static char rcsid[] = "$NetBSD: $";
#endif

/*
* scalbnl (long double x, int n)
* scalbnl(x,n) returns x* 2**n computed by exponent
Expand All @@ -28,44 +24,36 @@ static char rcsid[] = "$NetBSD: $";
#include "math.h"
#include "math_private.h"

#ifdef __STDC__
static const long double
#else
static long double
#endif
two63 = 4.50359962737049600000e+15,
twom63 = 1.08420217248550443400e-19,
huge = 1.0e+4900L,
tiny = 1.0e-4900L;

#ifdef __STDC__
long double __scalblnl (long double x, long int n)
#else
long double __scalblnl (x,n)
long double x; long int n;
#endif
long double
__scalblnl (long double x, long int n)
{
int32_t k,es,hx,lx;
GET_LDOUBLE_WORDS(es,hx,lx,x);
k = es&0x7fff; /* extract exponent */
if (k==0) { /* 0 or subnormal x */
if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */
k = es&0x7fff; /* extract exponent */
if (__builtin_expect(k==0, 0)) { /* 0 or subnormal x */
if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */
x *= two63;
GET_LDOUBLE_EXP(es,x);
k = (hx&0x7fff) - 63;
}
if (k==0x7fff) return x+x; /* NaN or Inf */
k = k+n;
if (n> 50000 || k > 0x7ffe)
if (__builtin_expect(k==0x7fff, 0)) return x+x; /* NaN or Inf */
k = k+n;
if (__builtin_expect(n> 50000 || k > 0x7ffe, 0))
return huge*__copysignl(huge,x); /* overflow */
if (n< -50000)
if (__builtin_expect(n< -50000, 0))
return tiny*__copysignl(tiny,x);
if (k > 0) /* normal result */
if (__builtin_expect(k > 0, 1)) /* normal result */
{SET_LDOUBLE_EXP(x,(es&0x8000)|k); return x;}
if (k <= -63)
if (k <= -63)
return tiny*__copysignl(tiny,x); /*underflow*/
k += 63; /* subnormal result */
k += 63; /* subnormal result */
SET_LDOUBLE_EXP(x,(es&0x8000)|k);
return x*twom63;
return x*twom63;
}
weak_alias (__scalblnl, scalblnl)

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