If you remove the "override CFLAGS += -Wno-uninitialized" in
math/Makefile, you get errors from lgamma implementations of the form:
../sysdeps/ieee754/dbl-64/e_lgamma_r.c: In function '__ieee754_lgamma_r':
../sysdeps/ieee754/dbl-64/e_lgamma_r.c:297:13: error: 'nadj' may be used uninitialized in this function [-Werror=maybe-uninitialized]
if(hx<0) r = nadj - r;
This is one of the standard kinds of false positive uninitialized
warnings: nadj is set under a certain condition, and then later used
under the same condition. This patch uses DIAG_* macros to suppress
the warning on the use of nadj. The ldbl-128 / ldbl-128ibm
implementation has a substantially different structure that avoids
this issue.
Tested for x86_64. (In fact this patch eliminates the need for that
-Wno-uninitialized on x86_64, but I want to test on more architectures
before removing it.)
* sysdeps/ieee754/dbl-64/e_lgamma_r.c: Include <libc-internal.h>.
(__ieee754_lgamma_r): Ignore uninitialized warnings around use of
NADJ.
* sysdeps/ieee754/flt-32/e_lgammaf_r.c: Include <libc-internal.h>.
(__ieee754_lgammaf_r): Ignore uninitialized warnings around use of
NADJ.
* sysdeps/ieee754/ldbl-96/e_lgammal_r.c: Include <libc-internal.h>.
(__ieee754_lgammal_r): Ignore uninitialized warnings around use of
NADJ.
The flt-32 implementation of lgammaf produces spurious underflow
exceptions for some large arguments, because of calculations involving
x^-2 multiplied by small constants. This patch fixes this by
adjusting the threshold for a simpler computation to 2**26 (the error
in the simpler computation is on the order of 0.5 * log (x), for a
result on the order of x * log (x)).
Tested for x86_64 and x86.
[BZ #18220]
* sysdeps/ieee754/flt-32/e_lgammaf_r.c (__ieee754_lgammaf_r): Use
2**26 not 2**58 as threshold for returning x * (log (x) - 1).
* math/auto-libm-test-in: Add another test of lgamma.
* math/auto-libm-test-out: Regenerated.
* sysdeps/ieee754/dbl-64/e_lgamma_r.c: Fix *signgamp for -0.0.
* sysdeps/ieee754/flt-32/e_lgammaf_r.c: Likewise.
* sysdeps/ieee754/ldbl-96/e_lgammal_r.c: Likewise.
* math/libm-test.inc: Add test for this case.
Half the patch by Christian Iseli <christian.iseli@licr.org>.
1999-10-19 Ulrich Drepper <drepper@cygnus.com>
* sysdeps/i386/fpu/s_nextafterl.c: Add __nextafterl and nextafterl
aliases.
* sysdeps/ieee754/flt-32/e_lgammaf_r.c: Don't handle -Inf special.
* sysdeps/ieee754/flt-32/e_gammaf_r.c (__ieee754_gammaf_r): Check
for -Inf and return NaN.
* math/gen-libm-test.pl: Fix program name in help message.
* math/libm-test.inc (check_complex): It's Imaginary, not Complex.
* math/libm-test.inc (gamma_test): Result of gamma(-inf) is +inf.
* sysdeps/i386/Implies: Correct order of libm directories.
