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Re: signbit glitch (coreutils 6.10, Solaris 8 sparc, GCC 4.2.2)
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From: |
Bruno Haible |
|
Subject: |
Re: signbit glitch (coreutils 6.10, Solaris 8 sparc, GCC 4.2.2) |
|
Date: |
Sat, 26 Jan 2008 02:31:30 +0100 |
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User-agent: |
KMail/1.5.4 |
Paul Eggert wrote:
> I ran into the following minor glitch when compiling coreutils 6.10 on
> Solaris 8 sparc with GCC 4.2.2:
>
> vasnprintf.c: In function 'vasnprintf':
> vasnprintf.c:2196: warning: implicit declaration of function 'signbit'
Thanks for reporting this.
> Here is a patch to the gnulib signbit module to work around this
> problem:
>
> 2008-01-24 Paul Eggert <address@hidden>
>
> * m4/signbit.m4 (gl_SIGNBIT): Check that signbit is a macro.
> This suppresses a warning when compiling coreutils 6.10 with
> GCC 4.2.2 on Solaris 8. In that combination, math.h does not
> define signbit, but GCC implements it internally (there is no
> library function) and issues a warning.
If GCC implements it as a built-in, with your patch, we'll reject the
built-in and provide substitutes in the form of functions. But it's
more efficient to use the GCC built-ins then. The warning goes away
if one uses __builtin_signbit instead of signbit.
I'm applying this:
2008-01-25 Paul Eggert <address@hidden>
Bruno Haible <address@hidden>
* m4/signbit.m4 (gl_SIGNBIT): Require a macro definition. Test whether
the GCC builtins for signbits are present and set
REPLACE_SIGNBIT_USING_GCC if so.
* lib/math.in.h (signbit): Define using GCC builtins if
REPLACE_SIGNBIT_USING_GCC is set.
* m4/math_h.m4 (gl_MATH_H_DEFAULTS): Initialize
REPLACE_SIGNBIT_USING_GCC.
* modules/math (Makefile.am): Substitute REPLACE_SIGNBIT_USING_GCC.
*** lib/math.in.h.orig 2008-01-26 02:25:45.000000000 +0100
--- lib/math.in.h 2008-01-26 00:41:20.000000000 +0100
***************
*** 353,358 ****
--- 353,366 ----
#if @GNULIB_SIGNBIT@
+ # if @REPLACE_SIGNBIT_USING_GCC@
+ # undef signbit
+ /* GCC 4.0 and newer provides three built-ins for signbit. */
+ # define signbit(x) \
+ (sizeof (x) == sizeof (long double) ? __builtin_signbitl (x) : \
+ sizeof (x) == sizeof (double) ? __builtin_signbit (x) : \
+ __builtin_signbitf (x))
+ # endif
# if @REPLACE_SIGNBIT@
# undef signbit
extern int gl_signbitf (float arg);
*** m4/math_h.m4.orig 2008-01-26 02:25:45.000000000 +0100
--- m4/math_h.m4 2008-01-26 00:40:25.000000000 +0100
***************
*** 1,5 ****
! # math_h.m4 serial 8
! dnl Copyright (C) 2007 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
--- 1,5 ----
! # math_h.m4 serial 9
! dnl Copyright (C) 2007-2008 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
***************
*** 36,65 ****
GNULIB_TRUNCF=0; AC_SUBST([GNULIB_TRUNCF])
GNULIB_TRUNCL=0; AC_SUBST([GNULIB_TRUNCL])
dnl Assume proper GNU behavior unless another module says otherwise.
! HAVE_DECL_ACOSL=1; AC_SUBST([HAVE_DECL_ACOSL])
! HAVE_DECL_ASINL=1; AC_SUBST([HAVE_DECL_ASINL])
! HAVE_DECL_ATANL=1; AC_SUBST([HAVE_DECL_ATANL])
! HAVE_DECL_COSL=1; AC_SUBST([HAVE_DECL_COSL])
! HAVE_DECL_EXPL=1; AC_SUBST([HAVE_DECL_EXPL])
! HAVE_DECL_FREXPL=1; AC_SUBST([HAVE_DECL_FREXPL])
! HAVE_DECL_LDEXPL=1; AC_SUBST([HAVE_DECL_LDEXPL])
! HAVE_DECL_LOGL=1; AC_SUBST([HAVE_DECL_LOGL])
! HAVE_DECL_SINL=1; AC_SUBST([HAVE_DECL_SINL])
! HAVE_DECL_SQRTL=1; AC_SUBST([HAVE_DECL_SQRTL])
! HAVE_DECL_TANL=1; AC_SUBST([HAVE_DECL_TANL])
! HAVE_DECL_TRUNC=1; AC_SUBST([HAVE_DECL_TRUNC])
! HAVE_DECL_TRUNCF=1; AC_SUBST([HAVE_DECL_TRUNCF])
! HAVE_DECL_TRUNCL=1; AC_SUBST([HAVE_DECL_TRUNCL])
! REPLACE_CEILF=0; AC_SUBST([REPLACE_CEILF])
! REPLACE_CEILL=0; AC_SUBST([REPLACE_CEILL])
! REPLACE_FLOORF=0; AC_SUBST([REPLACE_FLOORF])
! REPLACE_FLOORL=0; AC_SUBST([REPLACE_FLOORL])
! REPLACE_FREXP=0; AC_SUBST([REPLACE_FREXP])
! REPLACE_FREXPL=0; AC_SUBST([REPLACE_FREXPL])
! REPLACE_ISFINITE=0; AC_SUBST([REPLACE_ISFINITE])
! REPLACE_LDEXPL=0; AC_SUBST([REPLACE_LDEXPL])
! REPLACE_ROUND=0; AC_SUBST([REPLACE_ROUND])
! REPLACE_ROUNDF=0; AC_SUBST([REPLACE_ROUNDF])
! REPLACE_ROUNDL=0; AC_SUBST([REPLACE_ROUNDL])
! REPLACE_SIGNBIT=0; AC_SUBST([REPLACE_SIGNBIT])
])
--- 36,66 ----
GNULIB_TRUNCF=0; AC_SUBST([GNULIB_TRUNCF])
GNULIB_TRUNCL=0; AC_SUBST([GNULIB_TRUNCL])
dnl Assume proper GNU behavior unless another module says otherwise.
! HAVE_DECL_ACOSL=1; AC_SUBST([HAVE_DECL_ACOSL])
! HAVE_DECL_ASINL=1; AC_SUBST([HAVE_DECL_ASINL])
! HAVE_DECL_ATANL=1; AC_SUBST([HAVE_DECL_ATANL])
! HAVE_DECL_COSL=1; AC_SUBST([HAVE_DECL_COSL])
! HAVE_DECL_EXPL=1; AC_SUBST([HAVE_DECL_EXPL])
! HAVE_DECL_FREXPL=1; AC_SUBST([HAVE_DECL_FREXPL])
! HAVE_DECL_LDEXPL=1; AC_SUBST([HAVE_DECL_LDEXPL])
! HAVE_DECL_LOGL=1; AC_SUBST([HAVE_DECL_LOGL])
! HAVE_DECL_SINL=1; AC_SUBST([HAVE_DECL_SINL])
! HAVE_DECL_SQRTL=1; AC_SUBST([HAVE_DECL_SQRTL])
! HAVE_DECL_TANL=1; AC_SUBST([HAVE_DECL_TANL])
! HAVE_DECL_TRUNC=1; AC_SUBST([HAVE_DECL_TRUNC])
! HAVE_DECL_TRUNCF=1; AC_SUBST([HAVE_DECL_TRUNCF])
! HAVE_DECL_TRUNCL=1; AC_SUBST([HAVE_DECL_TRUNCL])
! REPLACE_CEILF=0; AC_SUBST([REPLACE_CEILF])
! REPLACE_CEILL=0; AC_SUBST([REPLACE_CEILL])
! REPLACE_FLOORF=0; AC_SUBST([REPLACE_FLOORF])
! REPLACE_FLOORL=0; AC_SUBST([REPLACE_FLOORL])
! REPLACE_FREXP=0; AC_SUBST([REPLACE_FREXP])
! REPLACE_FREXPL=0; AC_SUBST([REPLACE_FREXPL])
! REPLACE_ISFINITE=0; AC_SUBST([REPLACE_ISFINITE])
! REPLACE_LDEXPL=0; AC_SUBST([REPLACE_LDEXPL])
! REPLACE_ROUND=0; AC_SUBST([REPLACE_ROUND])
! REPLACE_ROUNDF=0; AC_SUBST([REPLACE_ROUNDF])
! REPLACE_ROUNDL=0; AC_SUBST([REPLACE_ROUNDL])
! REPLACE_SIGNBIT=0; AC_SUBST([REPLACE_SIGNBIT])
! REPLACE_SIGNBIT_USING_GCC=0; AC_SUBST([REPLACE_SIGNBIT_USING_GCC])
])
*** m4/signbit.m4.orig 2008-01-26 02:25:46.000000000 +0100
--- m4/signbit.m4 2008-01-26 02:25:33.000000000 +0100
***************
*** 1,5 ****
! # signbit.m4 serial 2
! dnl Copyright (C) 2007 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
--- 1,5 ----
! # signbit.m4 serial 3
! dnl Copyright (C) 2007-2008 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
***************
*** 11,17 ****
--- 11,129 ----
[
AC_TRY_RUN([
#include <math.h>
+ /* If signbit is defined as a function, don't use it, since calling it for
+ 'float' or 'long double' arguments would involve conversions.
+ If signbit is not declared at all but exists as a library function, don't
+ use it, since the prototype may not match.
+ If signbit is not declared at all but exists as a compiler built-in, don't
+ use it, since it's preferable to use __builtin_signbit* (no warnings,
+ no conversions). */
+ #ifndef signbit
+ # error "signbit should be a macro"
+ #endif
#include <string.h>
+ ]gl_SIGNBIT_TEST_PROGRAM
+ , [gl_cv_func_signbit=yes], [gl_cv_func_signbit=no],
+ [gl_cv_func_signbit="guessing no"])
+ ])
+ dnl GCC 4.0 and newer provides three built-ins for signbit.
+ dnl They can be used without warnings, also in C++, regardless of <math.h>.
+ dnl But they may expand to calls to functions, which may or may not be in
+ dnl libc.
+ AC_CACHE_CHECK([for signbit compiler built-ins], [gl_cv_func_signbit_gcc],
+ [
+ AC_TRY_RUN([
+ #if __GNUC__ >= 4
+ # define signbit(x) \
+ (sizeof (x) == sizeof (long double) ? __builtin_signbitl (x) : \
+ sizeof (x) == sizeof (double) ? __builtin_signbit (x) : \
+ __builtin_signbitf (x))
+ #else
+ # error "signbit should be three compiler built-ins"
+ #endif
+ #include <string.h>
+ ]gl_SIGNBIT_TEST_PROGRAM
+ , [gl_cv_func_signbit_gcc=yes], [gl_cv_func_signbit_gcc=no],
+ [gl_cv_func_signbit_gcc="guessing no"])
+ ])
+ dnl Use the compiler built-ins whenever possible, because they are more
+ dnl efficient than the system library functions (if they exist).
+ if test "$gl_cv_func_signbit_gcc" = yes; then
+ REPLACE_SIGNBIT_USING_GCC=1
+ else
+ if test "$gl_cv_func_signbit" != yes; then
+ REPLACE_SIGNBIT=1
+ AC_LIBOBJ([signbitf])
+ AC_LIBOBJ([signbitd])
+ AC_LIBOBJ([signbitl])
+ gl_FLOAT_SIGN_LOCATION
+ gl_DOUBLE_SIGN_LOCATION
+ gl_LONG_DOUBLE_SIGN_LOCATION
+ if test "$gl_cv_cc_float_signbit" = unknown; then
+ dnl Test whether copysignf() is declared.
+ AC_CHECK_DECLS([copysignf], , , [#include <math.h>])
+ if test "$ac_cv_have_decl_copysignf" = yes; then
+ dnl Test whether copysignf() can be used without libm.
+ AC_CACHE_CHECK([whether copysignf can be used without linking with
libm],
+ [gl_cv_func_copysignf_no_libm],
+ [
+ AC_TRY_LINK([#include <math.h>
+ float x, y;],
+ [return copysignf (x, y) < 0;],
+ [gl_cv_func_copysignf_no_libm=yes],
+ [gl_cv_func_copysignf_no_libm=no])
+ ])
+ if test $gl_cv_func_copysignf_no_libm = yes; then
+ AC_DEFINE([HAVE_COPYSIGNF_IN_LIBC], 1,
+ [Define if the copysignf function is declared in <math.h> and
available in libc.])
+ fi
+ fi
+ fi
+ if test "$gl_cv_cc_double_signbit" = unknown; then
+ dnl Test whether copysign() is declared.
+ AC_CHECK_DECLS([copysign], , , [#include <math.h>])
+ if test "$ac_cv_have_decl_copysign" = yes; then
+ dnl Test whether copysign() can be used without libm.
+ AC_CACHE_CHECK([whether copysign can be used without linking with
libm],
+ [gl_cv_func_copysign_no_libm],
+ [
+ AC_TRY_LINK([#include <math.h>
+ double x, y;],
+ [return copysign (x, y) < 0;],
+ [gl_cv_func_copysign_no_libm=yes],
+ [gl_cv_func_copysign_no_libm=no])
+ ])
+ if test $gl_cv_func_copysign_no_libm = yes; then
+ AC_DEFINE([HAVE_COPYSIGN_IN_LIBC], 1,
+ [Define if the copysign function is declared in <math.h> and
available in libc.])
+ fi
+ fi
+ fi
+ if test "$gl_cv_cc_long_double_signbit" = unknown; then
+ dnl Test whether copysignl() is declared.
+ AC_CHECK_DECLS([copysignl], , , [#include <math.h>])
+ if test "$ac_cv_have_decl_copysignl" = yes; then
+ dnl Test whether copysignl() can be used without libm.
+ AC_CACHE_CHECK([whether copysignl can be used without linking with
libm],
+ [gl_cv_func_copysignl_no_libm],
+ [
+ AC_TRY_LINK([#include <math.h>
+ long double x, y;],
+ [return copysignl (x, y) < 0;],
+ [gl_cv_func_copysignl_no_libm=yes],
+ [gl_cv_func_copysignl_no_libm=no])
+ ])
+ if test $gl_cv_func_copysignl_no_libm = yes; then
+ AC_DEFINE([HAVE_COPYSIGNL_IN_LIBC], 1,
+ [Define if the copysignl function is declared in <math.h> and
available in libc.])
+ fi
+ fi
+ fi
+ fi
+ fi
+ ])
+
+ AC_DEFUN([gl_SIGNBIT_TEST_PROGRAM], [
float p0f = 0.0f;
float m0f = -0.0f;
double p0d = 0.0;
***************
*** 54,131 ****
return 1;
}
return 0;
! }], [gl_cv_func_signbit=yes], [gl_cv_func_signbit=no],
! [gl_cv_func_signbit="guessing no"])
! ])
! if test "$gl_cv_func_signbit" != yes; then
! REPLACE_SIGNBIT=1
! AC_LIBOBJ([signbitf])
! AC_LIBOBJ([signbitd])
! AC_LIBOBJ([signbitl])
! gl_FLOAT_SIGN_LOCATION
! gl_DOUBLE_SIGN_LOCATION
! gl_LONG_DOUBLE_SIGN_LOCATION
! if test "$gl_cv_cc_float_signbit" = unknown; then
! dnl Test whether copysignf() is declared.
! AC_CHECK_DECLS([copysignf], , , [#include <math.h>])
! if test "$ac_cv_have_decl_copysignf" = yes; then
! dnl Test whether copysignf() can be used without libm.
! AC_CACHE_CHECK([whether copysignf can be used without linking with
libm],
! [gl_cv_func_copysignf_no_libm],
! [
! AC_TRY_LINK([#include <math.h>
! float x, y;],
! [return copysignf (x, y) < 0;],
! [gl_cv_func_copysignf_no_libm=yes],
! [gl_cv_func_copysignf_no_libm=no])
! ])
! if test $gl_cv_func_copysignf_no_libm = yes; then
! AC_DEFINE([HAVE_COPYSIGNF_IN_LIBC], 1,
! [Define if the copysignf function is declared in <math.h> and
available in libc.])
! fi
! fi
! fi
! if test "$gl_cv_cc_double_signbit" = unknown; then
! dnl Test whether copysign() is declared.
! AC_CHECK_DECLS([copysign], , , [#include <math.h>])
! if test "$ac_cv_have_decl_copysign" = yes; then
! dnl Test whether copysign() can be used without libm.
! AC_CACHE_CHECK([whether copysign can be used without linking with
libm],
! [gl_cv_func_copysign_no_libm],
! [
! AC_TRY_LINK([#include <math.h>
! double x, y;],
! [return copysign (x, y) < 0;],
! [gl_cv_func_copysign_no_libm=yes],
! [gl_cv_func_copysign_no_libm=no])
! ])
! if test $gl_cv_func_copysign_no_libm = yes; then
! AC_DEFINE([HAVE_COPYSIGN_IN_LIBC], 1,
! [Define if the copysign function is declared in <math.h> and
available in libc.])
! fi
! fi
! fi
! if test "$gl_cv_cc_long_double_signbit" = unknown; then
! dnl Test whether copysignl() is declared.
! AC_CHECK_DECLS([copysignl], , , [#include <math.h>])
! if test "$ac_cv_have_decl_copysignl" = yes; then
! dnl Test whether copysignl() can be used without libm.
! AC_CACHE_CHECK([whether copysignl can be used without linking with
libm],
! [gl_cv_func_copysignl_no_libm],
! [
! AC_TRY_LINK([#include <math.h>
! long double x, y;],
! [return copysignl (x, y) < 0;],
! [gl_cv_func_copysignl_no_libm=yes],
! [gl_cv_func_copysignl_no_libm=no])
! ])
! if test $gl_cv_func_copysignl_no_libm = yes; then
! AC_DEFINE([HAVE_COPYSIGNL_IN_LIBC], 1,
! [Define if the copysignl function is declared in <math.h> and
available in libc.])
! fi
! fi
! fi
! fi
])
AC_DEFUN([gl_FLOAT_SIGN_LOCATION],
--- 166,172 ----
return 1;
}
return 0;
! }
])
AC_DEFUN([gl_FLOAT_SIGN_LOCATION],
*** modules/math.orig 2008-01-26 02:25:46.000000000 +0100
--- modules/math 2008-01-26 00:39:25.000000000 +0100
***************
*** 64,69 ****
--- 64,70 ----
-e 's|@''REPLACE_ROUNDF''@|$(REPLACE_ROUNDF)|g' \
-e 's|@''REPLACE_ROUNDL''@|$(REPLACE_ROUNDL)|g' \
-e 's|@''REPLACE_SIGNBIT''@|$(REPLACE_SIGNBIT)|g' \
+ -e
's|@''REPLACE_SIGNBIT_USING_GCC''@|$(REPLACE_SIGNBIT_USING_GCC)|g' \
-e '/definition of GL_LINK_WARNING/r $(LINK_WARNING_H)' \
< $(srcdir)/math.in.h; \
} > address@hidden