The truncl assembly implementation (sysdeps/powerpc/powerpc64/fpu/s_truncl.S)
returns wrong results for some inputs where first double is a exact integer
and the precision is determined by second long double.
Checking on implementation comments and history, I am very confident the
assembly implementation was based on a version before commit
5c68d40169 that fixes BZ#2423 (Errors in
long double (ldbl-128ibm) rounding functions in glibc-2.4).
By just removing the implementation and make the build select
sysdeps/ieee754/ldbl-128ibm/s_truncl.c instead it fixes tgammal
issues regarding wrong result sign.
This patch fixes bug 16390, incorrect signs of zero results from
ldbl-128ibm atan2l, soft-float only. The problem is a longstanding
GCC bug with fabsl not being correct for signed zero for soft float,
and the fix is using -fno-builtin-fabsl as a workaround, as already
done for various other source files. Tested powerpc-nofpu.
* sysdeps/powerpc/nofpu/Makefile [$(subdir) = math]
(CFLAGS-e_atan2l.c): Use -fno-builtin-fabsl.
sysdeps/powerpc/powerpc32/libgcc-compat.S makes certain symbols that
glibc once accidentally reexported from libgcc into compat symbols.
Where the exports were purely accidental, this is the right thing to
do. However, for powerpc-nofpu the soft-fp symbols are deliberately
exported from libc, given public versions in
sysdeps/powerpc/nofpu/Versions and used by libm in preference to the
libgcc versions that do not support the software exceptions and
rounding modes. The libc versions should also be usable by user
programs, though normally libgcc gets linked in first (meaning,
effectively, that the <fenv.h> functions are broken as regards their
expected effects on user arithmetic).
A longstanding todo item is to remove the functions in question from
libgcc (when built with recent enough glibc) - that is, remove them
from static libgcc and make them compat symbols in shared libgcc - so
that this works properly (this is one of the items mentioned at
<http://gcc.gnu.org/wiki/Software_floating_point> - parts of that page
are obviously out of date, but this item still applies). Doing this
requires first that the functions are actually available from libc for
new links, not just as compat symbols.
This patch stops the symbols in question being compat symbols for
powerpc-nofpu. The nofpu Versions entries for them are removed (the
symbols never were exported at GLIBC_2.3.2, only GLIBC_2.0, because
the compat symbols took precedence).
Tested powerpc-nofpu. The symbols are no longer compat symbols and
libm.so now properly gets undefined references to them (resolved to
libc.so) instead of the libgcc copies getting linked into libm as
before.
* sysdeps/powerpc/powerpc32/libgcc-compat.S
[_SOFT_FLOAT || __NO_FPRS__] (__fixdfdi_v_glibc20): Do not define
as a macro and a compat symbol.
[_SOFT_FLOAT || __NO_FPRS__] (__fixsfdi_v_glibc20): Likewise.
[_SOFT_FLOAT || __NO_FPRS__] (__fixunsdfdi_v_glibc20): Likewise.
[_SOFT_FLOAT || __NO_FPRS__] (__fixunssfdi_v_glibc20): Likewise.
[_SOFT_FLOAT || __NO_FPRS__] (__floatdidf_v_glibc20): Likewise.
[_SOFT_FLOAT || __NO_FPRS__] (__floaddisf_v_glibc20): Likewise.
[HAVE_DOT_HIDDEN && (_SOFT_FLOAT || __NO_FPRS__)] (__fixdfdi): Do
not use .hidden.
[HAVE_DOT_HIDDEN && (_SOFT_FLOAT || __NO_FPRS__)] (__fixsfdi):
Likewise.
[HAVE_DOT_HIDDEN && (_SOFT_FLOAT || __NO_FPRS__)] (__fixunsdfdi):
Likewise.
[HAVE_DOT_HIDDEN && (_SOFT_FLOAT || __NO_FPRS__)] (__fixunssfdi):
Likewise.
[HAVE_DOT_HIDDEN && (_SOFT_FLOAT || __NO_FPRS__)] (__floaddidf):
Likewise.
[HAVE_DOT_HIDDEN && (_SOFT_FLOAT || __NO_FPRS__)] (__floaddisf):
Likewise.
* sysdeps/powerpc/nofpu/Versions (libc): Remove __fixdfdi,
__fixsfdi, __fixunsdfdi, __fixunssfdi, __floatdidf and __floatdisf
from GLIBC_2.3.2.
For PPC64, all the wrappers at sysdeps are superfluous: they are
basically the same implementation from math/w_sqrt.c with the
'#ifdef _IEEE_LIBM'. And the power4 version just force the 'fsqrt'
instruction utilization with an inline assembly, which is already
handled by math_private.h __ieee754_sqrt implementation.
Adhemerval Zanella
Joseph Myers
Allan McRae
Andreas Schwab