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Fix -Os log1p, log1pf build (bug 21314).

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As reported in bug 21314, building log1p and log1pf fails with -Os
because of a spurious -Wmaybe-uninitialized warning (reported there
for GCC 5 for MIPS, I see it also with GCC 7 for x86_64).  This patch,
based on the patches in the bug, fixes this using the DIAG_* macros.

Tested for x86_64 with -Os that this eliminates those warnings and so
allows the build to progress further.

2018-02-01  Carlos O'Donell  <carlos@redhat.com>
	    Ramin Seyed-Moussavi  <lordrasmus@gmail.com>
	    Joseph Myers  <joseph@codesourcery.com>

	[BZ #21314]
	* sysdeps/ieee754/dbl-64/s_log1p.c: Include <libc-diag.h>.
	(__log1p): Disable -Wmaybe-uninitialized for -Os around
	computation using c.
	* sysdeps/ieee754/flt-32/s_log1pf.c: Include <libc-diag.h>.
	(__log1pf): Disable -Wmaybe-uninitialized for -Os around
	computation using c.
This commit is contained in:
Carlos O'Donell 2018-02-01 20:40:48 +00:00 committed by Joseph Myers
parent 086ee48eae
commit f1d7368196
3 changed files with 38 additions and 3 deletions
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12
ChangeLog
View File

@ -1,3 +1,15 @@
2018-02-01 Carlos O'Donell <carlos@redhat.com>
Ramin Seyed-Moussavi <lordrasmus@gmail.com>
Joseph Myers <joseph@codesourcery.com>
[BZ #21314]
* sysdeps/ieee754/dbl-64/s_log1p.c: Include <libc-diag.h>.
(__log1p): Disable -Wmaybe-uninitialized for -Os around
computation using c.
* sysdeps/ieee754/flt-32/s_log1pf.c: Include <libc-diag.h>.
(__log1pf): Disable -Wmaybe-uninitialized for -Os around
computation using c.
2018-02-01 Dmitry V. Levin <ldv@altlinux.org>
* version.h (RELEASE): Set to "development".

12
sysdeps/ieee754/dbl-64/s_log1p.c
View File

@ -81,6 +81,7 @@
#include <float.h>
#include <math.h>
#include <math_private.h>
#include <libc-diag.h>
static const double
ln2_hi = 6.93147180369123816490e-01, /* 3fe62e42 fee00000 */
@ -191,5 +192,14 @@ __log1p (double x)
if (k == 0)
return f - (hfsq - s * (hfsq + R));
else
return k * ln2_hi - ((hfsq - (s * (hfsq + R) + (k * ln2_lo + c))) - f);
{
/* With GCC 7 when compiling with -Os the compiler warns that c
might be used uninitialized. This can't be true because k
must be 0 for c to be uninitialized and we handled that
computation earlier without using c. */
DIAG_PUSH_NEEDS_COMMENT;
DIAG_IGNORE_Os_NEEDS_COMMENT (7, "-Wmaybe-uninitialized");
return k * ln2_hi - ((hfsq - (s * (hfsq + R) + (k * ln2_lo + c))) - f);
DIAG_POP_NEEDS_COMMENT;
}
}

17
sysdeps/ieee754/flt-32/s_log1pf.c
View File

@ -16,6 +16,7 @@
#include <float.h>
#include <math.h>
#include <math_private.h>
#include <libc-diag.h>
static const float
ln2_hi = 6.9313812256e-01, /* 0x3f317180 */
@ -97,6 +98,18 @@ __log1pf(float x)
s = f/((float)2.0+f);
z = s*s;
R = z*(Lp1+z*(Lp2+z*(Lp3+z*(Lp4+z*(Lp5+z*(Lp6+z*Lp7))))));
if(k==0) return f-(hfsq-s*(hfsq+R)); else
return k*ln2_hi-((hfsq-(s*(hfsq+R)+(k*ln2_lo+c)))-f);
if (k == 0)
return f - (hfsq - s * (hfsq + R));
else
{
/* With GCC 7 when compiling with -Os the compiler warns
that c might be used uninitialized. This can't be true
because k must be 0 for c to be uninitialized and we
handled that computation earlier without using c. */
DIAG_PUSH_NEEDS_COMMENT;
DIAG_IGNORE_Os_NEEDS_COMMENT (7, "-Wmaybe-uninitialized");
return k * ln2_hi - ((hfsq - (s * (hfsq + R)
+ (k * ln2_lo + c))) - f);
DIAG_POP_NEEDS_COMMENT;
}
}