qiurui
/
glibc
mirror of git://sourceware.org/git/glibc.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

[BZ #22243] fix log2(0) and log(10) in downward rounding 

On 64bit targets if the SVID compat wrapper is suppressed (e.g. static linking)
then log2(0) and log10(0) returned inf instead of -inf.

	[BZ #22243]
	* sysdeps/ieee754/dbl-64/wordsize-64/e_log10.c (__ieee754_log10): Use fabs.
	* sysdeps/ieee754/dbl-64/wordsize-64/e_log2.c (__ieee754_log2): Likewise.
This commit is contained in:
Szabolcs Nagy 2017-10-03 17:13:18 +01:00
parent 955774751b
commit 8f8f8ef7ab
3 changed files with 8 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
ChangeLog
View File

@ -1,3 +1,9 @@
2017-10-04 Szabolcs Nagy <szabolcs.nagy@arm.com>
[BZ #22243]
* sysdeps/ieee754/dbl-64/wordsize-64/e_log10.c (__ieee754_log10): Use fabs.
* sysdeps/ieee754/dbl-64/wordsize-64/e_log2.c (__ieee754_log2): Likewise.
2017-10-03 H.J. Lu <hongjiu.lu@intel.com>
* sysdeps/i386/start.S: Replace "leal main@GOT(%ebx), %eax" with

2
sysdeps/ieee754/dbl-64/wordsize-64/e_log10.c
View File

@ -65,7 +65,7 @@ __ieee754_log10 (double x)
if (hx < INT64_C(0x0010000000000000))
{ /* x < 2**-1022 */
if (__glibc_unlikely ((hx & UINT64_C(0x7fffffffffffffff)) == 0))
return -two54 / (x - x); /* log(+-0)=-inf */
return -two54 / fabs (x); /* log(+-0)=-inf */
if (__glibc_unlikely (hx < 0))
return (x - x) / (x - x); /* log(-#) = NaN */
k -= 54;

2
sysdeps/ieee754/dbl-64/wordsize-64/e_log2.c
View File

@ -81,7 +81,7 @@ __ieee754_log2 (double x)
if (hx < INT64_C(0x0010000000000000))
{ /* x < 2**-1022 */
if (__glibc_unlikely ((hx & UINT64_C(0x7fffffffffffffff)) == 0))
return -two54 / (x - x); /* log(+-0)=-inf */
return -two54 / fabs (x); /* log(+-0)=-inf */
if (__glibc_unlikely (hx < 0))
return (x - x) / (x - x); /* log(-#) = NaN */
k -= 54;