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Use STRICT_ASSIGN() for log1pf() and log1p() instead of a volatile cast

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hack for log1pf() only.  The cast hack broke with gcc-4, resulting in
~1 million errors of more than 1 ulp, with a maximum error of ~1.5 ulps.
Now the maximum error for log1pf() on i386 is 0.5034 ulps again (this
depends on extra precision), and log1p() has a chance of working with
extra precision.

See s_log1pf.c 1.8 for the original hack.  (It claims only 62343 large
errors).

Convert to _FBSDID().  Another thing broken with gcc-4 is the static
const hack used for rcsids.
This commit is contained in:
Bruce Evans 2008-01-19 18:13:21 +00:00
parent 6e8f9331d7
commit 0814af48f7
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=175494
2 changed files with 10 additions and 8 deletions
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9
lib/msun/src/s_log1p.c
View File

@ -10,9 +10,8 @@
* ====================================================
*/
#ifndef lint
static char rcsid[] = "$FreeBSD$";
#endif
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
/* double log1p(double x)
*
@ -79,6 +78,8 @@ static char rcsid[] = "$FreeBSD$";
* See HP-15C Advanced Functions Handbook, p.193.
*/
#include <float.h>
#include "math.h"
#include "math_private.h"
@ -124,7 +125,7 @@ log1p(double x)
if (hx >= 0x7ff00000) return x+x;
if(k!=0) {
if(hx<0x43400000) {
u = 1.0+x;
STRICT_ASSIGN(double,u,1.0+x);
GET_HIGH_WORD(hu,u);
k = (hu>>20)-1023;
c = (k>0)? 1.0-(u-x):x-(u-1.0);/* correction term */

9
lib/msun/src/s_log1pf.c
View File

@ -13,9 +13,10 @@
* ====================================================
*/
#ifndef lint
static char rcsid[] = "$FreeBSD$";
#endif
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <float.h>
#include "math.h"
#include "math_private.h"
@ -62,7 +63,7 @@ log1pf(float x)
if (hx >= 0x7f800000) return x+x;
if(k!=0) {
if(hx<0x5a000000) {
*(volatile float *)&u = (float)1.0+x;
STRICT_ASSIGN(float,u,(float)1.0+x);
GET_FLOAT_WORD(hu,u);
k = (hu>>23)-127;
/* correction term */