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

Fix csqrt spurious underflows (bug 18823). 

The csqrt functions scale up small arguments to avoid underflows when
calling hypot functions.  However, even when hypot does not underflow,
a subsequent calculation of 0.5 * hypot can underflow.  This patch
duly increases the threshold and scale factor to avoid such underflows
as well.

Tested for x86_64, x86 and mips64.

	[BZ #18823]
	* math/s_csqrt.c (__csqrt): Increase threshold and scale factor
	for scaling up small arguments.
	* math/s_csqrtf.c (__csqrtf): Likewise.
	* math/s_csqrtl.c (__csqrtl): Likewise.
	* math/auto-libm-test-in: Add more tests of csqrt.
	* math/auto-libm-test-out: Regenerated.
This commit is contained in:
Joseph Myers 2015-08-17 23:02:54 +00:00
parent 1e15a853ed
commit 3fb4cfaf1f
7 changed files with 1861 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
ChangeLog
View File

@ -1,3 +1,13 @@
2015-08-17 Joseph Myers <joseph@codesourcery.com>
[BZ #18823]
* math/s_csqrt.c (__csqrt): Increase threshold and scale factor
for scaling up small arguments.
* math/s_csqrtf.c (__csqrtf): Likewise.
* math/s_csqrtl.c (__csqrtl): Likewise.
* math/auto-libm-test-in: Add more tests of csqrt.
* math/auto-libm-test-out: Regenerated.
2015-08-17 Andreas Schwab <schwab@suse.de>
* sysdeps/unix/sysv/linux/powerpc/Versions (libm): Add empty

2
NEWS
View File

@ -11,7 +11,7 @@ Version 2.23
16517, 16519, 16520, 16734, 17905, 18084, 18086, 18265, 18480, 18525,
18618, 18647, 18661, 18681, 18674, 18778, 18781, 18787, 18789, 18790,
18795, 18820, 18824.
18795, 18820, 18823, 18824.
* The obsolete header <regexp.h> has been removed. Programs that require
this header must be updated to use <regex.h> instead.

9
math/auto-libm-test-in
View File

@ -1162,6 +1162,15 @@ csqrt -0x0.ffp1024 0x1.1p-509
csqrt 0x0.ffp16384 0x1.1p-8189
csqrt -0x0.ffp16384 0x1.1p-8189
csqrt 0x1p-149 0x1.000002p-126
csqrt 0x1p-149 0x1.000004p-126
csqrt 0x1p-1074 0x1.0000000000001p-1022
csqrt 0x1p-1074 0x1.0000000000002p-1022
csqrt 0x1p-16445 0x1.0000000000000002p-16382
csqrt 0x1p-16445 0x1.0000000000000004p-16382
csqrt 0x1p-16494 0x1.0000000000000000000000000001p-16382
csqrt 0x1p-16494 0x1.0000000000000000000000000002p-16382
ctan 0 0
ctan 0 -0
ctan -0 0

1832
math/auto-libm-test-out
View File

File diff suppressed because it is too large Load Diff

6
math/s_csqrt.c
View File

@ -104,10 +104,10 @@ __csqrt (__complex__ double x)
__real__ x = 0.0;
__imag__ x = __scalbn (__imag__ x, -2 * scale);
}
else if (fabs (__real__ x) < DBL_MIN
&& fabs (__imag__ x) < DBL_MIN)
else if (fabs (__real__ x) < 2.0 * DBL_MIN
&& fabs (__imag__ x) < 2.0 * DBL_MIN)
{
scale = -(DBL_MANT_DIG / 2);
scale = -((DBL_MANT_DIG + 1) / 2);
__real__ x = __scalbn (__real__ x, -2 * scale);
__imag__ x = __scalbn (__imag__ x, -2 * scale);
}

6
math/s_csqrtf.c
View File

@ -104,10 +104,10 @@ __csqrtf (__complex__ float x)
__real__ x = 0.0f;
__imag__ x = __scalbnf (__imag__ x, -2 * scale);
}
else if (fabsf (__real__ x) < FLT_MIN
&& fabsf (__imag__ x) < FLT_MIN)
else if (fabsf (__real__ x) < 2.0f * FLT_MIN
&& fabsf (__imag__ x) < 2.0f * FLT_MIN)
{
scale = -(FLT_MANT_DIG / 2);
scale = -((FLT_MANT_DIG + 1) / 2);
__real__ x = __scalbnf (__real__ x, -2 * scale);
__imag__ x = __scalbnf (__imag__ x, -2 * scale);
}

6
math/s_csqrtl.c
View File

@ -104,10 +104,10 @@ __csqrtl (__complex__ long double x)
__real__ x = 0.0L;
__imag__ x = __scalbnl (__imag__ x, -2 * scale);
}
else if (fabsl (__real__ x) < LDBL_MIN
&& fabsl (__imag__ x) < LDBL_MIN)
else if (fabsl (__real__ x) < 2.0L * LDBL_MIN
&& fabsl (__imag__ x) < 2.0L * LDBL_MIN)
{
scale = -(LDBL_MANT_DIG / 2);
scale = -((LDBL_MANT_DIG + 1) / 2);
__real__ x = __scalbnl (__real__ x, -2 * scale);
__imag__ x = __scalbnl (__imag__ x, -2 * scale);
}