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Date: Tue, 7 Oct 2008 20:10:19 +0200
From: Bernhard Reutner-Fischer <rep dot dot dot nop at gmail dot com>
To: Ian Lance Taylor <iant at google dot com>
Cc: gcc-patches at gcc dot gnu dot org
Subject: Re: [PATCH] link libgcc_s.so against a lib containing copysignl on 	powerpc-*-linux-uclibc
Message-ID: <20081007181019.GB5178@mx.loc>
References: <20081007141721.GG9250@mx.loc> <m33aj82wcc.fsf@google.com>
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On Tue, Oct 07, 2008 at 09:39:31AM -0700, Ian Lance Taylor wrote:
>Bernhard Reutner-Fischer <rep.dot.nop@gmail.com> writes:
>
>> gcc/ChangeLog:
>>
>> 2008-10-07  Bernhard Reutner-Fischer  <>
>>
>> 	* config/t-slibgcc-elf-ver (SHLIB_LC): Also link against
>> 	@libgcc_libm@.
>>
>> libgcc/ChangeLog:
>>
>> 2008-10-07  Bernhard Reutner-Fischer  <>
>>
>> 	* configure.ac (libgcc_cv_copysignl_lib, LIBGCC_LIBM): New
>> 	variables to denote if we are on powerpc-uclibc where libm
>> 	functions live in libm.
>> 	* Makefile.in (LIBGCC_LIBM): Set.
>> 	(libgcc_s$(SHLIB_EXT)): Substitute @libgcc_libm@ with
>> 	$(LIBGCC_LIBM).
>> 	* (configure): Regenerate.
>
>
>> +# On powerpc libgcc_s references copysignl which is a libm function but
>> +# glibc apparently also provides it via libc as opposed to uClibc where
>> +# it lives in libm.
>> +dnl save_LIBS="$LIBS"
>> +dnl LIBS=
>> +dnl AC_SEARCH_LIBS(copysignl, m)
>> +dnl LIBGCC_LIBS="$LIBS"
>> +dnl LIBS="$save_LIBS"
>> +dnl AC_SUBST(LIBGCC_LIBS)
>
>Why don't you run these commands listed as dnl?

I don't have a working compiler here yet and GCC_NO_EXECUTABLES. I can
only assemble, not link (we're about to build the libgcc for the
compiler here).
>
>> +AC_CACHE_CHECK([for library containing copysignl],
>> +  libgcc_cv_copysignl_lib, [
>> +    echo '#include <features.h>' > conftest.c
>> +    case $target_alias in
>> +    *powerpc*)
>> +	echo 'int the_libc = __UCLIBC__;' >> conftest.c
>> +	;;
>> +    *)
>> +	echo 'int the_libc; /* dummy */' >> conftest.c
>> +	;;
>> +    esac
>> +    libgcc_cv_copysignl_lib="-lc"
>> +    if AC_TRY_COMMAND(${CC-cc} -S conftest.c -o conftest.s 1>&AS_MESSAGE_LOG_FD)
>> +    then
>> +	libgcc_cv_copysignl_lib="-lm"
>> +    fi
>
>AC_TRY_COMMAND is not part of the documented set of autoconf
>commands.  And this test seems reversed: shouldn't you add -lm if
>AC_TRY_COMMAND fails?

AC_TRY_COMMAND is used in the same file to check visibility support.
An alternative would be to run nm(1), but for that i need to know the
location of libc and libm so AC_TRY_COMMAND was easier.

The test is supposed to
- pass only on powerpc-*-*-uclibc*
- fail otherwise
so yes, that isn't quite right and should drop the case statement and
check something like __UCLIBC__ + __powerpc__ instead (or use #if
!defined\n#else\n#error glibm\n#endif but that would be more echo
invocations).


>I don't see any reason to write shell code that tests $target_alias

true.

>(and shouldn't it be $host_alias anyhow)?  Just write C code that does
>"#ifdef PPC"?

It can't be the host_alias, we can as well build either a
build=host=i386,target=ppc (cross-compiler) or a
build=i386,host=target=ppc ("native" compiler, cross-compiled).
>
>The basic idea seems fine, though.

Thanks. I'm attaching an updated patch, ChangeLog remains the same.
Ok for trunk?

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Content-Disposition: attachment; filename="820-powerpc-softfloat-libm_for_copysignl.patch"

diff -rdup gcc-4.4.0.old/gcc/config/t-slibgcc-elf-ver gcc-4.4.0/gcc/config/t-slibgcc-elf-ver
--- gcc-4.4.0.old/gcc/config/t-slibgcc-elf-ver	2005-10-31 18:03:08.000000000 +0100
+++ gcc-4.4.0/gcc/config/t-slibgcc-elf-ver	2008-10-07 19:28:13.000000000 +0200
@@ -9,7 +9,7 @@ SHLIB_MAP = @shlib_map_file@
 SHLIB_OBJS = @shlib_objs@
 SHLIB_DIR = @multilib_dir@
 SHLIB_SLIBDIR_QUAL = @shlib_slibdir_qual@
-SHLIB_LC = -lc
+SHLIB_LC = @libgcc_libm@ -lc
 
 SHLIB_LINK = $(GCC_FOR_TARGET) $(LIBGCC2_CFLAGS) -shared -nodefaultlibs \
 	-Wl,--soname=$(SHLIB_SONAME) \
diff -rdup gcc-4.4.0.old/libgcc/configure gcc-4.4.0/libgcc/configure
--- gcc-4.4.0.old/libgcc/configure	2008-07-17 10:40:53.000000000 +0200
+++ gcc-4.4.0/libgcc/configure	2008-10-07 19:40:48.000000000 +0200
@@ -272,7 +272,7 @@ PACKAGE_STRING='GNU C Runtime Library 1.
 PACKAGE_BUGREPORT=''
 
 ac_unique_file="static-object.mk"
-ac_subst_vars='SHELL PATH_SEPARATOR PACKAGE_NAME PACKAGE_TARNAME PACKAGE_VERSION PACKAGE_STRING PACKAGE_BUGREPORT exec_prefix prefix program_transform_name bindir sbindir libexecdir datadir sysconfdir sharedstatedir localstatedir libdir includedir oldincludedir infodir mandir build_alias host_alias target_alias DEFS ECHO_C ECHO_N ECHO_T LIBS libgcc_topdir enable_shared slibdir INSTALL_PROGRAM INSTALL_SCRIPT INSTALL_DATA AWK build build_cpu build_vendor build_os host host_cpu host_vendor host_os host_noncanonical build_libsubdir build_subdir host_subdir target_subdir AR ac_ct_AR LIPO ac_ct_LIPO NM ac_ct_NM RANLIB ac_ct_RANLIB STRIP ac_ct_STRIP LN_S CC CFLAGS LDFLAGS CPPFLAGS ac_ct_CC EXEEXT OBJEXT CPP decimal_float enable_decimal_float fixed_point vis_hide set_have_cc_tls tmake_file extra_parts asm_hidden_op LIBOBJS LTLIBOBJS'
+ac_subst_vars='SHELL PATH_SEPARATOR PACKAGE_NAME PACKAGE_TARNAME PACKAGE_VERSION PACKAGE_STRING PACKAGE_BUGREPORT exec_prefix prefix program_transform_name bindir sbindir libexecdir datadir sysconfdir sharedstatedir localstatedir libdir includedir oldincludedir infodir mandir build_alias host_alias target_alias DEFS ECHO_C ECHO_N ECHO_T LIBS libgcc_topdir enable_shared slibdir INSTALL_PROGRAM INSTALL_SCRIPT INSTALL_DATA AWK build build_cpu build_vendor build_os host host_cpu host_vendor host_os host_noncanonical build_libsubdir build_subdir host_subdir target_subdir AR ac_ct_AR LIPO ac_ct_LIPO NM ac_ct_NM RANLIB ac_ct_RANLIB STRIP ac_ct_STRIP LN_S CC CFLAGS LDFLAGS CPPFLAGS ac_ct_CC EXEEXT OBJEXT CPP decimal_float enable_decimal_float fixed_point vis_hide set_have_cc_tls LIBGCC_LIBM tmake_file extra_parts asm_hidden_op LIBOBJS LTLIBOBJS'
 ac_subst_files=''
 ac_pwd=`pwd`
 
@@ -3522,6 +3522,39 @@ if test "$enable_tls $gcc_cv_have_cc_tls
 fi
 
 
+# On powerpc libgcc_s references copysignl which is a libm function but
+# glibc apparently also provides it via libc as opposed to uClibc where
+# it lives in libm.
+echo "$as_me:$LINENO: checking for library containing copysignl" >&5
+echo $ECHO_N "checking for library containing copysignl... $ECHO_C" >&6
+if test "${libgcc_cv_copysignl_lib+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+
+    echo '#include <features.h>' > conftest.c
+    echo 'int the_libc = __UCLIBC__ + __powerpc__;' >> conftest.c
+    libgcc_cv_copysignl_lib="-lc"
+    if { ac_try='${CC-cc} -S conftest.c -o conftest.s 1>&5'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }
+    then
+	libgcc_cv_copysignl_lib="-lm"
+    fi
+    rm -f conftest.*
+
+fi
+echo "$as_me:$LINENO: result: $libgcc_cv_copysignl_lib" >&5
+echo "${ECHO_T}$libgcc_cv_copysignl_lib" >&6
+
+case /${libgcc_cv_copysignl_lib}/ in
+  /-lm/) LIBGCC_LIBM="$LIBGCC_LIBM -lm" ;;
+  *) LIBGCC_LIBM= ;;
+esac
+
+
 # Conditionalize the makefile for this target machine.
 tmake_file_=
 for f in ${tmake_file}
@@ -4242,6 +4275,7 @@ s,@enable_decimal_float@,$enable_decimal
 s,@fixed_point@,$fixed_point,;t t
 s,@vis_hide@,$vis_hide,;t t
 s,@set_have_cc_tls@,$set_have_cc_tls,;t t
+s,@LIBGCC_LIBM@,$LIBGCC_LIBM,;t t
 s,@tmake_file@,$tmake_file,;t t
 s,@extra_parts@,$extra_parts,;t t
 s,@asm_hidden_op@,$asm_hidden_op,;t t
diff -rdup gcc-4.4.0.old/libgcc/configure.ac gcc-4.4.0/libgcc/configure.ac
--- gcc-4.4.0.old/libgcc/configure.ac	2008-07-17 10:40:53.000000000 +0200
+++ gcc-4.4.0/libgcc/configure.ac	2008-10-07 19:34:48.000000000 +0200
@@ -203,6 +203,27 @@ if test "$enable_tls $gcc_cv_have_cc_tls
 fi
 AC_SUBST(set_have_cc_tls)
 
+# On powerpc libgcc_s references copysignl which is a libm function but
+# glibc apparently also provides it via libc as opposed to uClibc where
+# it lives in libm.
+AC_CACHE_CHECK([for library containing copysignl],
+  libgcc_cv_copysignl_lib, [
+    echo '#include <features.h>' > conftest.c
+    echo 'int the_libc = __UCLIBC__ + __powerpc__;' >> conftest.c
+    libgcc_cv_copysignl_lib="-lc"
+    if AC_TRY_COMMAND(${CC-cc} -S conftest.c -o conftest.s 1>&AS_MESSAGE_LOG_FD)
+    then
+	libgcc_cv_copysignl_lib="-lm"
+    fi
+    rm -f conftest.*
+  ])
+
+case /${libgcc_cv_copysignl_lib}/ in
+  /-lm/) LIBGCC_LIBM="$LIBGCC_LIBM -lm" ;;
+  *) LIBGCC_LIBM= ;;
+esac
+AC_SUBST(LIBGCC_LIBM)
+
 # Conditionalize the makefile for this target machine.
 tmake_file_=
 for f in ${tmake_file}
diff -rdup gcc-4.4.0.old/libgcc/Makefile.in gcc-4.4.0/libgcc/Makefile.in
--- gcc-4.4.0.old/libgcc/Makefile.in	2008-07-17 10:40:53.000000000 +0200
+++ gcc-4.4.0/libgcc/Makefile.in	2008-10-07 19:28:13.000000000 +0200
@@ -40,6 +40,7 @@ enable_shared = @enable_shared@
 decimal_float = @decimal_float@
 enable_decimal_float = @enable_decimal_float@
 fixed_point = @fixed_point@
+LIBGCC_LIBM = @LIBGCC_LIBM@
 
 host_noncanonical = @host_noncanonical@
 
@@ -786,9 +787,10 @@ libgcc_s$(SHLIB_EXT): $(libgcc-s-objects
 		@multilib_dir@,$(MULTIDIR),$(subst \
 		@shlib_objs@,$(objects),$(subst \
 		@shlib_base_name@,libgcc_s,$(subst \
+		@libgcc_libm@,$(LIBGCC_LIBM),$(subst \
 		@shlib_map_file@,$(mapfile),$(subst \
 		@shlib_slibdir_qual@,$(MULTIOSSUBDIR),$(subst \
-		@shlib_slibdir@,$(shlib_slibdir),$(SHLIB_LINK))))))))
+		@shlib_slibdir@,$(shlib_slibdir),$(SHLIB_LINK)))))))))
 
 libunwind$(SHLIB_EXT): $(libunwind-s-objects) $(extra-parts)
 	# @multilib_flags@ is still needed because this may use

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