glibc/sysdeps/ieee754
Joseph Myers f6987f5aa4 Fix hypot missing underflows (bug 18803).
Similar to various other bugs in this area, hypot functions can fail
to raise the underflow exception when the result is tiny and inexact
but one or more low bits of the intermediate result that is scaled
down (or, in the i386 case, converted from a wider evaluation format)
are zero.  This patch forces the exception in a similar way to
previous fixes.

Note that this issue cannot arise for implementations of hypotf using
double (or wider) for intermediate evaluation (if hypotf should
underflow, that means the double square root is being computed of some
number of the form N*2^-298, for 0 < N < 2^46, which is exactly
represented as a double, and whatever the rounding mode such a square
root cannot have a mantissa with all zeroes after the initial 23
bits).  Thus no changes are made to hypotf implementations in this
patch, only to hypot and hypotl.

Tested for x86_64, x86, mips64 and powerpc.

	[BZ #18803]
	* sysdeps/i386/fpu/e_hypot.S: Use DEFINE_DBL_MIN.
	(MO): New macro.
	(__ieee754_hypot) [PIC]: Load PIC register.
	(__ieee754_hypot): Use DBL_NARROW_EVAL_UFLOW_NONNEG instead of
	DBL_NARROW_EVAL.
	* sysdeps/ieee754/dbl-64/e_hypot.c (__ieee754_hypot): Use
	math_check_force_underflow_nonneg in case where result might be
	tiny.
	* sysdeps/ieee754/ldbl-128/e_hypotl.c (__ieee754_hypotl):
	Likewise.
	* sysdeps/ieee754/ldbl-128ibm/e_hypotl.c (__ieee754_hypotl):
	Likewise.
	* sysdeps/ieee754/ldbl-96/e_hypotl.c (__ieee754_hypotl): Likewise.
	* sysdeps/powerpc/fpu/e_hypot.c (__ieee754_hypot): Likewise.
	* math/auto-libm-test-in: Add more tests of hypot.
	* math/auto-libm-test-out: Regenerated.
2015-09-24 23:43:57 +00:00
..
bits Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
dbl-64 Fix hypot missing underflows (bug 18803). 2015-09-24 23:43:57 +00:00
flt-32 Don't use volatile in exp2f. 2015-09-23 22:52:13 +00:00
ldbl-64-128 Make scalbn set errno (bug 6803). 2015-09-16 21:11:00 +00:00
ldbl-96 Fix hypot missing underflows (bug 18803). 2015-09-24 23:43:57 +00:00
ldbl-128 Fix hypot missing underflows (bug 18803). 2015-09-24 23:43:57 +00:00
ldbl-128ibm Fix hypot missing underflows (bug 18803). 2015-09-24 23:43:57 +00:00
ldbl-opt Use math_narrow_eval more consistently. 2015-09-23 18:14:57 +00:00
ieee754.h Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
k_standard.c Add comment to CSTR macro in k_standard.c. 2015-02-27 01:12:19 +00:00
k_standardf.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
k_standardl.c Fix spurious "inexact" exceptions from __kernel_standard_l (bug 18245, bug 18583). 2015-06-23 17:26:46 +00:00
Makefile Avoid -Wno-write-strings for k_standard.c. 2015-02-26 22:50:54 +00:00
s_lib_version.c Remove trailing whitespace. 2013-06-05 20:44:03 +00:00
s_matherr.c Use <> for math.h and math_private.h everywhere. 2012-03-09 16:09:10 -08:00
s_signgam.c Use <> for math.h and math_private.h everywhere. 2012-03-09 16:09:10 -08:00