Bug 18247 is an off-by-one error in strtof's determination of a
decimal exponent such that any value with that decimal exponent is at
most half the least subnormal and so the appropriate underflowing
value for the rounding mode can be determined with no
multiple-precision computations. (Whether the value is in fact safe
despite the off-by-one depends on the floating-point format in
question. It's wrong for float and for m68k ldbl-96 but not for other
supported formats.) This patch corrects the computation of the
exponent in question to be safe in general, adding a comment
explaining the new computation.
Tested for x86_64.
[BZ #18247]
* stdlib/strtod_l.c (____STRTOF_INTERNAL): Decrease minimum
decimal exponent by 1.
* stdlib/tst-strtod-round-data: Add more tests.
* stdlib/tst-strtod-round.c (tests): Regenerated.
Due to tile missing a bunch of FP exception and rounding
support, the tests generate warnings. These changes fix the
warnings by just not compiling some unused functions, and
adding some attribute ((unused)) tags.
Building this test on ARM fails because the prototypes for the long
double variants of the math functions are unavailable.
Add an additional include guard to math.h that enables long double math
function declarations if _LIBC_TEST is defined and define _LIBC_TEST in
stdlib/tst-strtod-round.c.
ChangeLog:
2014-09-30 Will Newton <will.newton@linaro.org>
* math/math.h: Define long double math functions if
_LIBC_TEST is defined.
* stdlib/tst-strtod-round.c: Define _LIBC_TEST.
