Optimize s_modf

ChangeLog

@@ -1,5 +1,11 @@
 2012-01-10  Ulrich Drepper  <drepper@gmail.com>
 
+	* sysdeps/ieee754/dbl-64/wordsize-64/s_modf.c: New file.
+
+	* sysdeps/ieee754/dbl-64/s_modf.c: Add branch prediction.
+	* sysdeps/ieee754/flt-32/s_modff.c: Likewise.
+	* sysdeps/ieee754/ldbl-96/s_modfl.c: Likewise.
+
 	* math/bits/mathcalls.h: Add const attribute to fmin and fmax.
 
 	* sysdeps/ieee754/dbl-64/s_scalbn.c: Add branch prediction.

NEWS

@@ -1,4 +1,4 @@
-GNU C Library NEWS -- history of user-visible changes.  2012-1-8
+GNU C Library NEWS -- history of user-visible changes.  2012-1-10
 Copyright (C) 1992-2009, 2010, 2011, 2012 Free Software Foundation, Inc.
 See the end for copying conditions.
 
@@ -39,6 +39,9 @@ Version 2.16
 
 * Checking versions of poll, ppoll added.
   Implemented by Ulrich Drepper.
+
+* More generic and 64-bit performance optimizations to math functions.
+  Implemented by Ulrich Drepper.
 
 Version 2.15
 

sysdeps/ieee754/dbl-64/s_modf.c

@@ -1,4 +1,3 @@
-/* @(#)s_modf.c 5.1 93/09/24 */
 /*
  * ====================================================
  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
@@ -10,10 +9,6 @@
  * ====================================================
  */
 
-#if defined(LIBM_SCCS) && !defined(lint)
-static char rcsid[] = "$NetBSD: s_modf.c,v 1.8 1995/05/10 20:47:55 jtc Exp $";
-#endif
-
 /*
  * modf(double x, double *iptr)
  * return fraction part of x, and return x's integral part in *iptr.
@@ -27,26 +22,18 @@ static char rcsid[] = "$NetBSD: s_modf.c,v 1.8 1995/05/10 20:47:55 jtc Exp $";
 #include "math.h"
 #include "math_private.h"
 
-#ifdef __STDC__
 static const double one = 1.0;
-#else
-static double one = 1.0;
-#endif
 
-#ifdef __STDC__
-	double __modf(double x, double *iptr)
-#else
-	double __modf(x, iptr)
-	double x,*iptr;
-#endif
+double
+__modf(double x, double *iptr)
 {
 	int32_t i0,i1,j0;
 	u_int32_t i;
 	EXTRACT_WORDS(i0,i1,x);
 	j0 = ((i0>>20)&0x7ff)-0x3ff;	/* exponent of x */
 	if(j0<20) {			/* integer part in high x */
 	    if(j0<0) {			/* |x|<1 */
-	        INSERT_WORDS(*iptr,i0&0x80000000,0);	/* *iptr = +-0 */
+		INSERT_WORDS(*iptr,i0&0x80000000,0);	/* *iptr = +-0 */
 		return x;
 	    } else {
 		i = (0x000fffff)>>j0;
@@ -59,7 +46,7 @@ static double one = 1.0;
 		    return x - *iptr;
 		}
 	    }
-	} else if (j0>51) {		/* no fraction part */
+	} else if (__builtin_expect(j0>51, 0)) { /* no fraction part */
 	    *iptr = x*one;
 	    /* We must handle NaNs separately.  */
 	    if (j0 == 0x400 && ((i0 & 0xfffff) | i1))
@@ -73,7 +60,7 @@ static double one = 1.0;
 		INSERT_WORDS(x,i0&0x80000000,0);	/* return +-0 */
 		return x;
 	    } else {
-	        INSERT_WORDS(*iptr,i0,i1&(~i));
+		INSERT_WORDS(*iptr,i0,i1&(~i));
 		return x - *iptr;
 	    }
 	}

sysdeps/ieee754/dbl-64/wordsize-64/s_modf.c

@@ -0,0 +1,65 @@
+/* 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.
+ * ====================================================
+ */
+
+/*
+ * modf(double x, double *iptr)
+ * return fraction part of x, and return x's integral part in *iptr.
+ * Method:
+ *	Bit twiddling.
+ *
+ * Exception:
+ *	No exception.
+ */
+
+#include "math.h"
+#include "math_private.h"
+
+static const double one = 1.0;
+
+double
+__modf(double x, double *iptr)
+{
+	int64_t i0;
+	int32_t j0;
+	EXTRACT_WORDS64(i0,x);
+	j0 = ((i0>>52)&0x7ff)-0x3ff;	/* exponent of x */
+	if(j0<52) {			/* integer part in x */
+	    if(j0<0) {			/* |x|<1 */
+		/* *iptr = +-0 */
+		INSERT_WORDS64(*iptr,i0&UINT64_C(0x8000000000000000));
+		return x;
+	    } else {
+		uint64_t i = UINT64_C(0x000fffffffffffff)>>j0;
+		if((i0&i)==0) {		/* x is integral */
+		    *iptr = x;
+		    /* return +-0 */
+		    INSERT_WORDS64(x,i0&UINT64_C(0x8000000000000000));
+		    return x;
+		} else {
+		    INSERT_WORDS64(*iptr,i0&(~i));
+		    return x - *iptr;
+		}
+	    }
+	} else { /* no fraction part */
+	    *iptr = x*one;
+	    /* We must handle NaNs separately.  */
+	    if (j0 == 0x400 && (i0 & UINT64_C(0xfffffffffffff)))
+	      return x*one;
+	    INSERT_WORDS64(x,i0&UINT64_C(0x8000000000000000));	/* return +-0 */
+	    return x;
+	}
+}
+weak_alias (__modf, modf)
+#ifdef NO_LONG_DOUBLE
+strong_alias (__modf, __modfl)
+weak_alias (__modf, modfl)
+#endif

sysdeps/ieee754/flt-32/s_modff.c

@@ -13,33 +13,21 @@
  * ====================================================
  */
 
-#if defined(LIBM_SCCS) && !defined(lint)
-static char rcsid[] = "$NetBSD: s_modff.c,v 1.4 1995/05/10 20:47:56 jtc Exp $";
-#endif
-
 #include "math.h"
 #include "math_private.h"
 
-#ifdef __STDC__
 static const float one = 1.0;
-#else
-static float one = 1.0;
-#endif
 
-#ifdef __STDC__
-	float __modff(float x, float *iptr)
-#else
-	float __modff(x, iptr)
-	float x,*iptr;
-#endif
+float
+__modff(float x, float *iptr)
 {
 	int32_t i0,j0;
 	u_int32_t i;
 	GET_FLOAT_WORD(i0,x);
 	j0 = ((i0>>23)&0xff)-0x7f;	/* exponent of x */
-	if(j0<23) {			/* integer part in x */
+	if(__builtin_expect(j0<23, 1)) {		/* integer part in x */
 	    if(j0<0) {			/* |x|<1 */
-	        SET_FLOAT_WORD(*iptr,i0&0x80000000);	/* *iptr = +-0 */
+		SET_FLOAT_WORD(*iptr,i0&0x80000000);	/* *iptr = +-0 */
 		return x;
 	    } else {
 		i = (0x007fffff)>>j0;

sysdeps/ieee754/ldbl-96/s_modfl.c

@@ -14,10 +14,6 @@
  * ====================================================
  */
 
-#if defined(LIBM_SCCS) && !defined(lint)
-static char rcsid[] = "$NetBSD: $";
-#endif
-
 /*
  * modfl(long double x, long double *iptr)
  * return fraction part of x, and return x's integral part in *iptr.
@@ -31,26 +27,18 @@ static char rcsid[] = "$NetBSD: $";
 #include "math.h"
 #include "math_private.h"
 
-#ifdef __STDC__
 static const long double one = 1.0;
-#else
-static long double one = 1.0;
-#endif
 
-#ifdef __STDC__
-	long double __modfl(long double x, long double *iptr)
-#else
-	long double __modfl(x, iptr)
-	long double x,*iptr;
-#endif
+long double
+__modfl(long double x, long double *iptr)
 {
 	int32_t i0,i1,j0;
 	u_int32_t i,se;
 	GET_LDOUBLE_WORDS(se,i0,i1,x);
 	j0 = (se&0x7fff)-0x3fff;	/* exponent of x */
 	if(j0<32) {			/* integer part in high x */
 	    if(j0<0) {			/* |x|<1 */
-	        SET_LDOUBLE_WORDS(*iptr,se&0x8000,0,0);	/* *iptr = +-0 */
+		SET_LDOUBLE_WORDS(*iptr,se&0x8000,0,0);	/* *iptr = +-0 */
 		return x;
 	    } else {
 		i = (0x7fffffff)>>j0;
@@ -63,7 +51,7 @@ static long double one = 1.0;
 		    return x - *iptr;
 		}
 	    }
-	} else if (j0>63) {		/* no fraction part */
+	} else if (__builtin_expect(j0>63, 0)) { /* no fraction part */
 	    *iptr = x*one;
 	    /* We must handle NaNs separately.  */
 	    if (j0 == 0x4000 && ((i0 & 0x7fffffff) | i1))