Re: [Patch, target] Sort out some issues in config{,/*}/darwin*.h

[Jack Howarth <howarth at bromo dot med dot uc dot edu>]

On Wed, Apr 14, 2010 at 05:41:58PM +0100, IainS wrote:
> Hi all,
>
> Whilst this is mostly darwin-specific, it clearly needs build-system  
> approval for the generation and installation of "dsymutil-wrapper.sh" in 
> $(libexecdir)
>
> References:
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43751
> http://gcc.gnu.org/ml/gcc/2010-04/msg00207.html
> http://gcc.gnu.org/ml/fortran/2010-04/msg00131.html
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42333
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43254
>
> Much though I dislike addressing multiple problems in one patch...
> ... this particular area is like a balloon - if you push it in one place 
> it just pops out somewhere else.
>
> So this is what I've done:
>
> 	o Trivial white-space tidies in asm directives (.comm, .lcomm, .glob  
> missing leading tabs)
>
> 	o Split the LINK_COMMAND_SPEC into two bits:
>  		LINK_COMMAND_SPEC_A    Common across the platform.
> 		DSYMUTIL_SPEC which needs to vary depending on the default debug  
> format.
> 	
> 	o macro-ized DSYMUTIL so that we can change it without editing the  
> specs.
> 	o Provided a wrapper for the system-supplied dsymutil that allows us to 
> edit out bogus warnings.
> 		this is installed in $(libexecdir) . The initial version filters the  
> message that gives us problems
> 	        like PR43254.
>
> 	o Altered the behavior of DSYMUTIL_SPEC so that it:
> 		(a) Always runs when we are generating an exe - IMO this is more  
> intuitive to the end user - and
> 		     it side-steps the problem with the existing spec.
> 		(b) it defaults to generation of flat debug (.dwarf) files - you can  
> generate the .dSYM by passing
> 		    -mdsym on the c/l (although .dwarf works just fine with the XCode 
> gdb AFAICT).
>
> 		   This latter step hopefully will get round the myriad "X.dSYM is  
> directory" configury error msgs.
> 		
> 		- this now works for all FEs including fortran.
>
> 	o Filter out -lm and re-apply it where needed.  [I've provided a bolt- 
> hole for anyone who wants to
> 	   force -lm (-force_lm) at least until we confirm that this is not an 
> issue.]
>
> 	o Remove -lgcc from darwin.h and re-apply it in the rs6000/ 
> darwin{7,8}.h where it is required
>            as the source of save/restore_world (added a FIXME that this 
> probably should not be so).
>
> 	o as a temporary hack - I've placed libgcc.a ahead of libm and  
> libsystem on darwin 10. This works
> 	   around PR42333.

Iain,
   Have you considered removing the extra -lgcc outright instead?
>From the comments of the Apple clang programmers...

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42333#c44

they are heading in that direction soon.
            Jack

>
> 	o fixed darwin10 not to provide no_compact_unwind when building for  
> <10.6.
>
>
> Have fun.. and I'd welcome comments on improvements.
>
> Iain
>
> gcc/ChangeLog:
>
> 	* dsymutil-wrapper.sh.in: New.
> 	* Makefile.in: Build and install (to libexecdir) dsymutil-wrapper.sh.
> 	* config/i386/darwin.h: Correct tabs before asm directives.
> 	* config/rs6000/darwin.h: Ditto.
> 	* config/rs6000/darwin7.h: Add -lgcc to LIB_SPEC and add FIXME note.
> 	* config/rs6000/darwin8.h: Ditto.
> 	* config/darwin.h: Correct tabs before asm directives.
> 	Split LINK_COMMAND_SPEC into
> 	(LINK_COMMAND_SPEC_A): New. (DSYMUTIL_SPEC): New.
> 	Remove source code dependency on dsymutils running.  Reference
> 	dsymutil-wrapper.sh.  Strip -lm from Darwin versions that supply
> 	this in libSystem or libgcc_s.  Remove -lgcc catch-all from the
> 	LIB_SPEC.
> 	(DEBUG_INLINED_SECTION): New macro.
> 	* config/darwin9.h: LINK_COMMAND_SPEC: Use LINK_COMMAND_SPEC_A.
> 	(DSYMUTIL_SPEC): New.
> 	Correct tabs before asm directives.
> 	* config/darwin10.h: Reference libgcc.a before libm and libSystem
> 	to work around PR42333.  Add FIXME note.  Make "no_compact_unwind"
> 	depend on targetting >= 10.6.
>
>
>

> Index: gcc/dsymutil-wrapper.sh.in
> ===================================================================
> --- gcc/dsymutil-wrapper.sh.in	(revision 0)
> +++ gcc/dsymutil-wrapper.sh.in	(revision 0)
> @@ -0,0 +1,36 @@
> +#!/bin/sh
> +#
> +#   Wrapper script for dsymutil on Darwin (Mac OS X) systems.
> +#   Copyright (C) 2010 Free Software Foundation, Inc.
> +#   Contributed by Iain Sandoe <iains@gcc.gnu.org>.
> +#
> +# This file is part of GCC.
> +#
> +# GCC is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 3, or (at your option)
> +# any later version.
> +#
> +# GCC is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with GCC; see the file COPYING3.  If not see
> +# <http://www.gnu.org/licenses/>.  */
> +#
> +#
> +# Disable bogus warnings from dsymutil that upset our testsuite.
> +#
> +# Passing '-Wdsymutil' as argument 1 to the script will bypass the
> +# filter.
> +
> +case "$1" in
> +  -Wdsymutil)
> +    shift; dsymutil $* ; exit $status ;;
> +	
> +  *)
> +   dsymutil $* | sed /warning:\ DWARFDebugInfoEntry::AppendDependants\(\)\ --\ check\ on\ this\ item\ TAG_subrange_type:\ attr\ =\ \ AT_upper_bound\ \ form\ =\ FORM_ref4/d ;;
> +esac
> +exit 0
> Index: gcc/Makefile.in
> ===================================================================
> --- gcc/Makefile.in	(revision 158296)
> +++ gcc/Makefile.in	(working copy)
> @@ -1455,7 +1455,7 @@ MOSTLYCLEANFILES = insn-flags.h insn-config.h insn
>   genrtl.c genrtl.h gt-*.h gtype-*.h gtype-desc.c gtyp-input.list \
>   xgcc$(exeext) cpp$(exeext) cc1$(exeext) cc1*-dummy$(exeext) $(EXTRA_PASSES) \
>   $(EXTRA_PARTS) $(EXTRA_PROGRAMS) gcc-cross$(exeext) \
> - $(SPECS) collect2$(exeext) lto-wrapper$(exeext) \
> + $(SPECS) collect2$(exeext) lto-wrapper$(exeext) dsymutil-wrapper.sh \
>   gcov-iov$(build_exeext) gcov$(exeext) gcov-dump$(exeext) \
>   *.[0-9][0-9].* *.[si] *-checksum.c libbackend.a libgcc.mk
>  
> @@ -1729,7 +1729,7 @@ all.internal: start.encap rest.encap doc
>  all.cross: native gcc-cross$(exeext) cpp$(exeext) specs \
>  	libgcc-support lang.all.cross doc @GENINSRC@ srcextra
>  # This is what must be made before installing GCC and converting libraries.
> -start.encap: native xgcc$(exeext) cpp$(exeext) specs \
> +start.encap: native xgcc$(exeext) cpp$(exeext) specs dsymutil-wrapper.sh \
>  	libgcc-support lang.start.encap @GENINSRC@ srcextra
>  # These can't be made until after GCC can run.
>  rest.encap: lang.rest.encap
> @@ -2037,6 +2037,9 @@ lto-wrapper$(exeext): lto-wrapper.o intl.o $(LIBDE
>  
>  lto-wrapper.o: lto-wrapper.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) intl.h
>  
> +dsymutil-wrapper.sh: $(srcdir)/dsymutil-wrapper.sh.in
> +	cp -pf $(srcdir)/dsymutil-wrapper.sh.in $@
> +
>  # A file used by all variants of C.
>  
>  c-common.o : c-common.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(TREE_H) \
> @@ -4253,8 +4256,8 @@ maintainer-clean:
>  # Install the driver last so that the window when things are
>  # broken is small.
>  install: install-common $(INSTALL_HEADERS) \
> -    install-cpp install-man install-info install-@POSUB@ \
> -    install-driver install-lto-wrapper
> +    install-cpp install-man install-info install-@POSUB@ install-dsymutil-wrapper \
> +    install-driver install-lto-wrapper 
>  
>  ifeq ($(enable_plugin),yes)
>  install: install-plugin
> @@ -4564,6 +4567,9 @@ install-collect2: collect2 installdirs
>  install-lto-wrapper: lto-wrapper$(exeext)
>  	$(INSTALL_PROGRAM) lto-wrapper$(exeext) $(DESTDIR)$(libexecsubdir)/lto-wrapper$(exeext)
>  
> +install-dsymutil-wrapper: dsymutil-wrapper.sh
> +	$(INSTALL_SCRIPT) dsymutil-wrapper.sh $(DESTDIR)$(libsubdir)/dsymutil-wrapper.sh
> +
>  # Cancel installation by deleting the installed files.
>  uninstall: lang.uninstall
>  	-rm -rf $(DESTDIR)$(libsubdir)
> Index: gcc/config/i386/darwin.h
> ===================================================================
> --- gcc/config/i386/darwin.h	(revision 158296)
> +++ gcc/config/i386/darwin.h	(working copy)
> @@ -198,9 +198,9 @@ along with GCC; see the file COPYING3.  If not see
>   do { if ((LOG) != 0)			\
>          {				\
>            if (in_section == text_section) \
> -            fprintf (FILE, "\t%s %d,0x90\n", ALIGN_ASM_OP, (LOG)); \
> +            fprintf (FILE, "%s %d,0x90\n", ALIGN_ASM_OP, (LOG)); \
>            else				\
> -            fprintf (FILE, "\t%s %d\n", ALIGN_ASM_OP, (LOG)); \
> +            fprintf (FILE, "%s %d\n", ALIGN_ASM_OP, (LOG)); \
>          }				\
>      } while (0)
>  
> @@ -208,7 +208,7 @@ along with GCC; see the file COPYING3.  If not see
>     to define a global common symbol.  */
>  
>  #define ASM_OUTPUT_COMMON(FILE, NAME, SIZE, ROUNDED)  \
> -( fputs (".comm ", (FILE)),			\
> +( fputs ("\t.comm ", (FILE)),			\
>    assemble_name ((FILE), (NAME)),		\
>    fprintf ((FILE), ","HOST_WIDE_INT_PRINT_UNSIGNED"\n", (ROUNDED)))
>  
> @@ -216,7 +216,7 @@ along with GCC; see the file COPYING3.  If not see
>     to define a local common symbol.  */
>  
>  #define ASM_OUTPUT_LOCAL(FILE, NAME, SIZE, ROUNDED)  \
> -( fputs (".lcomm ", (FILE)),			\
> +( fputs ("\t.lcomm ", (FILE)),			\
>    assemble_name ((FILE), (NAME)),		\
>    fprintf ((FILE), ","HOST_WIDE_INT_PRINT_UNSIGNED"\n", (ROUNDED)))
>  
> Index: gcc/config/rs6000/darwin7.h
> ===================================================================
> --- gcc/config/rs6000/darwin7.h	(revision 158296)
> +++ gcc/config/rs6000/darwin7.h	(working copy)
> @@ -24,7 +24,19 @@ along with GCC; see the file COPYING3.  If not see
>     looked for in libmx first.  Include libmx by default because otherwise
>     libstdc++ isn't usable.  */
>  
> +/* Include lm if we've been asked for it and we're on a system for which it
> +   makes sense.  Note that the spec does not preclude a static version of 
> +   libm.
> +*/
> +
> +/* FIXME:
> +   We need the -lgcc here because we still pickup save/restore_world
> +   from there.
> +*/
> +
>  #undef	LIB_SPEC
> -#define LIB_SPEC "%{!static:\
> -  %:version-compare(!< 10.3 mmacosx-version-min= -lmx)\
> -  -lSystem}"
> +#define LIB_SPEC \
> +  "%{Zlm:%:version-compare(< 10.4 mmacosx-version-min= -lm) } %<Zlm \
> +   %{!static: -lgcc \
> +      %:version-compare(!< 10.3 mmacosx-version-min= -lmx)\
> +     -lSystem}"
> Index: gcc/config/rs6000/darwin8.h
> ===================================================================
> --- gcc/config/rs6000/darwin8.h	(revision 158296)
> +++ gcc/config/rs6000/darwin8.h	(working copy)
> @@ -26,7 +26,14 @@ along with GCC; see the file COPYING3.  If not see
>     libSystemStubs when compiling on (not necessarily for) 8.0 and
>     above and not 64-bit long double.  */
>  
> +/* FIXME:
> +   We need the -lgcc here because we still pickup save/restore_world
> +   from there.
> +*/
> +
>  #undef	LIB_SPEC
> -#define LIB_SPEC "%{!static:\
> -  %{!mlong-double-64:%{pg:-lSystemStubs_profile;:-lSystemStubs}} \
> -  %{!m64:%:version-compare(>< 10.3 10.4 mmacosx-version-min= -lmx)} -lSystem}"
> +#define LIB_SPEC \
> +  "%{Zlm:%:version-compare(< 10.4 mmacosx-version-min= -lm) } %<Zlm \
> +   %{!static: -lgcc \
> +     %{!mlong-double-64:%{pg:-lSystemStubs_profile;:-lSystemStubs}} \
> +     %{!m64:%:version-compare(>< 10.3 10.4 mmacosx-version-min= -lmx)} -lSystem}"
> Index: gcc/config/rs6000/darwin.h
> ===================================================================
> --- gcc/config/rs6000/darwin.h	(revision 158296)
> +++ gcc/config/rs6000/darwin.h	(working copy)
> @@ -247,7 +247,7 @@
>  #define ASM_OUTPUT_COMMON(FILE, NAME, SIZE, ROUNDED)			\
>    do {									\
>      unsigned HOST_WIDE_INT _new_size = SIZE;				\
> -    fputs (".comm ", (FILE));						\
> +    fputs ("\t.comm ", (FILE));						\
>      RS6000_OUTPUT_BASENAME ((FILE), (NAME));				\
>      if (_new_size == 0) _new_size = 1;					\
>      fprintf ((FILE), ","HOST_WIDE_INT_PRINT_UNSIGNED"\n", _new_size);	\
> Index: gcc/config/darwin.h
> ===================================================================
> --- gcc/config/darwin.h	(revision 158296)
> +++ gcc/config/darwin.h	(working copy)
> @@ -144,7 +144,19 @@ extern GTY(()) int darwin_ms_struct;
>     command-line option translations specific to the particular target
>     architecture.  */
>  
> +/* We want to control the positioning and/or inclusion of -lm on
> +   Darwin/OSX systems which, post 10.3.9, obtain the math functions
> +   from either libgcc_s or libSystem.
> +   
> +   Since '-lm' is treated as an output file we cannot act on it directly
> +   and have to turn it into a flag we can manipulate.  Once used, the
> +   flag must be deleted with (%<Zlm).  For the sake of allowing a user
> +   to override this behavior -force_lm undoes this. */
> +   
>  #define TARGET_OPTION_TRANSLATE_TABLE \
> +  { "-lm", "-Zlm" },  \
> +  { "-force_lm", "-lm" },  \
> +  { "-Wdsymutil", "-Zwds" },  \
>    { "-all_load", "-Zall_load" },  \
>    { "-allowable_client", "-Zallowable_client" },  \
>    { "-arch_errors_fatal", "-Zarch_errors_fatal" },  \
> @@ -262,12 +274,14 @@ extern GTY(()) int darwin_ms_struct;
>     precomp, libtool, and fat build additions.  Also we
>     don't specify a second %G after %L because libSystem is
>     self-contained and doesn't need to link against libgcc.a.  */
> +
>  /* In general, random Darwin linker flags should go into LINK_SPEC
>     instead of LINK_COMMAND_SPEC.  The command spec is better for
>     specifying the handling of options understood by generic Unix
>     linkers, and for positional arguments like libraries.  */
> -#define LINK_COMMAND_SPEC "\
> -%{!fdump=*:%{!fsyntax-only:%{!c:%{!M:%{!MM:%{!E:%{!S:\
> +
> +#define LINK_COMMAND_SPEC_A \
> +    "%{!fdump=*:%{!fsyntax-only:%{!c:%{!M:%{!MM:%{!E:%{!S:\
>      %(linker) %l %X %{d} %{s} %{t} %{Z} %{u*} \
>      %{A} %{e*} %{m} %{r} %{x} \
>      %{o*}%{!o:-o a.out} \
> @@ -276,11 +290,25 @@ extern GTY(()) int darwin_ms_struct;
>      %{fopenmp|ftree-parallelize-loops=*: \
>        %{static|static-libgcc|static-libstdc++|static-libgfortran: libgomp.a%s; : -lgomp } } \
>      %{!nostdlib:%{!nodefaultlibs: %(link_ssp) %G %L }} \
> -    %{!A:%{!nostdlib:%{!nostartfiles:%E}}} %{T*} %{F*} }}}}}}}\n\
> -%{!fdump=*:%{!fsyntax-only:%{!c:%{!M:%{!MM:%{!E:%{!S:\
> -    %{.c|.cc|.C|.cpp|.cp|.c++|.cxx|.CPP|.m|.mm: \
> -    %{gdwarf-2:%{!gstabs*:%{!g0: dsymutil %{o*:%*}%{!o:a.out}}}}}}}}}}}}"
> +    %{!A:%{!nostdlib:%{!nostartfiles:%E}}} %{T*} %{F*} }}}}}}}\n"
>  
> +/* Horrible hackery to work around a dsymutil bug.  If you pass -Wdsymutil
> +   as the first item to the wrapper, you will get all dsymutil warnings. */
> +#define DSYMUTIL "dsymutil-wrapper.sh"
> +
> +/* We will default to generation of flat debug files.  This is more
> +   compatible with the majority of c/l and configury projects.
> +   An new c/l switch is invented here (-mdysm) that causes dsymutil
> +   to generate a .dSYM directory structure.   This latter is the 
> +   behavior of the XCode toolset on an OSX/Darwin system. */
> +   
> +#define DSYMUTIL_SPEC \
> +"%{!fdump=*:%{!fsyntax-only:%{!c:%{!M:%{!MM:%{!E:%{!S:\
> +    %{gdwarf*:%{!gstabs*:%{!g0: " DSYMUTIL " %{Zwds:-Wdsymutil} \
> +      %{!mdsym: -f } %{o*:%*}%{!o:a.out}}}}}}}}}}}"
> +
> +#define LINK_COMMAND_SPEC LINK_COMMAND_SPEC_A DSYMUTIL_SPEC
> +
>  #ifdef TARGET_SYSTEM_ROOT
>  #define LINK_SYSROOT_SPEC \
>    "%{isysroot*:-syslibroot %*;:-syslibroot " TARGET_SYSTEM_ROOT "}"
> @@ -374,11 +402,17 @@ extern GTY(()) int darwin_ms_struct;
>     %{whatsloaded} %{dylinker_install_name*} \
>     %{dylinker} %{Mach} "
>  
> -
>  /* Machine dependent libraries.  */
>  
> -#define LIB_SPEC "%{!static:-lSystem}"
> +/* Include lm if we've been asked for it and we're on a system for which it
> +   makes sense.  Note that the spec does not preclude a static version of 
> +   libm.
> +*/
>  
> +#define LIB_SPEC \
> +  "%{Zlm:%:version-compare(< 10.4 mmacosx-version-min= -lm) } %<Zlm \
> +   %{!static:-lSystem}"
> +
>  /* Support -mmacosx-version-min by supplying different (stub) libgcc_s.dylib
>     libraries to link against, and by not linking against libgcc_s on
>     earlier-than-10.3.9.
> @@ -397,15 +431,15 @@ extern GTY(()) int darwin_ms_struct;
>     "%{static-libgcc|static: -lgcc_eh -lgcc;				   \
>        shared-libgcc|fexceptions|fgnu-runtime:				   \
>         %:version-compare(!> 10.5 mmacosx-version-min= -lgcc_s.10.4)	   \
> -       %:version-compare(>= 10.5 mmacosx-version-min= -lgcc_s.10.5)	   \
> +       %:version-compare(>< 10.5 10.6 mmacosx-version-min= -lgcc_s.10.5)   \
>         %:version-compare(!> 10.5 mmacosx-version-min= -lgcc_ext.10.4)	   \
>         %:version-compare(>= 10.5 mmacosx-version-min= -lgcc_ext.10.5)	   \
> -       -lgcc;								   \
> +       ;								   \
>        :%:version-compare(>< 10.3.9 10.5 mmacosx-version-min= -lgcc_s.10.4) \
> -       %:version-compare(>= 10.5 mmacosx-version-min= -lgcc_s.10.5)	   \
> +       %:version-compare(>< 10.5 10.6 mmacosx-version-min= -lgcc_s.10.5)   \
>         %:version-compare(!> 10.5 mmacosx-version-min= -lgcc_ext.10.4)	   \
>         %:version-compare(>= 10.5 mmacosx-version-min= -lgcc_ext.10.5)	   \
> -       -lgcc}"
> +       }"
>  
>  /* We specify crt0.o as -lcrt0.o so that ld will search the library path.
>  
> @@ -467,6 +501,7 @@ extern GTY(()) int darwin_ms_struct;
>  #define DEBUG_LOC_SECTION	"__DWARF,__debug_loc,regular,debug"
>  #define DEBUG_PUBNAMES_SECTION	"__DWARF,__debug_pubnames,regular,debug"
>  #define DEBUG_PUBTYPES_SECTION	"__DWARF,__debug_pubtypes,regular,debug"
> +#define DEBUG_INLINED_SECTION   "__DWARF,__debug_inlined,regular,debug"
>  #define DEBUG_STR_SECTION	"__DWARF,__debug_str,regular,debug"
>  #define DEBUG_RANGES_SECTION	"__DWARF,__debug_ranges,regular,debug"
>  
> @@ -701,12 +736,12 @@ int darwin_label_is_anonymous_local_objc_name (con
>  #define DATA_SECTION_ASM_OP "\t.data"
>  
>  #undef	ALIGN_ASM_OP
> -#define ALIGN_ASM_OP		".align"
> +#define ALIGN_ASM_OP "\t.align"
>  
>  #undef	ASM_OUTPUT_ALIGN
>  #define ASM_OUTPUT_ALIGN(FILE,LOG)	\
>    if ((LOG) != 0)			\
> -    fprintf (FILE, "\t%s %d\n", ALIGN_ASM_OP, (LOG))
> +    fprintf (FILE, "%s %d\n", ALIGN_ASM_OP, (LOG))
>  
>  /* Ensure correct alignment of bss data.  */
>  
> @@ -714,7 +749,7 @@ int darwin_label_is_anonymous_local_objc_name (con
>  #define ASM_OUTPUT_ALIGNED_DECL_LOCAL(FILE, DECL, NAME, SIZE, ALIGN)	\
>    do {									\
>      unsigned HOST_WIDE_INT _new_size = SIZE;				\
> -    fputs (".lcomm ", (FILE));						\
> +    fputs ("\t.lcomm ", (FILE));						\
>      assemble_name ((FILE), (NAME));					\
>      if (_new_size == 0) _new_size = 1;					\
>      fprintf ((FILE), ","HOST_WIDE_INT_PRINT_UNSIGNED",%u\n", _new_size,	\
> @@ -782,7 +817,7 @@ extern GTY(()) section * darwin_sections[NUM_DARWI
>         } while (0)
>  
>  /* Globalizing directive for a label.  */
> -#define GLOBAL_ASM_OP ".globl "
> +#define GLOBAL_ASM_OP "\t.globl "
>  #define TARGET_ASM_GLOBALIZE_LABEL darwin_globalize_label
>  
>  /* Emit an assembler directive to set visibility for a symbol.  Used
> Index: gcc/config/darwin10.h
> ===================================================================
> --- gcc/config/darwin10.h	(revision 158296)
> +++ gcc/config/darwin10.h	(working copy)
> @@ -18,11 +18,25 @@ You should have received a copy of the GNU General
>  along with GCC; see the file COPYING3.  If not see
>  <http://www.gnu.org/licenses/>.  */
>  
> +/* FIXME:
> +   Hack to work around PR42333: we include the static version of libgcc
> +   before lSystem so that we override a buggy implementation of divdc3 */
> +
> +/* Include lm if we've been asked for it and we're on a system for which
> +   it makes sense.  Note that this spec does not preclude a static version
> +   of libm.
> +*/
> +
>  /* Fix PR41260 by passing -no_compact_unwind on darwin10 and later until
>  unwinder in libSystem is fixed to digest new epilog unwinding notes. */
> -
> + 
>  #undef LIB_SPEC
> -#define LIB_SPEC "%{!static:-no_compact_unwind -lSystem}"
> +#define LIB_SPEC \
> +  "%:version-compare(>= 10.6 mmacosx-version-min= -lgcc) \
> +   %{Zlm:%:version-compare(< 10.4 mmacosx-version-min= -lm) } %<Zlm \
> +   %{!static: \
> +     %:version-compare(>= 10.6 mmacosx-version-min= -no_compact_unwind) \
> +     -lSystem}"
>  
>  /* Unwind labels are no longer required in darwin10.  */
>  
> Index: gcc/config/darwin9.h
> ===================================================================
> --- gcc/config/darwin9.h	(revision 158296)
> +++ gcc/config/darwin9.h	(working copy)
> @@ -24,22 +24,19 @@ along with GCC; see the file COPYING3.  If not see
>  #define DARWIN_PREFER_DWARF
>  
>  /* Since DWARF2 is default, conditions for running dsymutil are different.  */
> -#undef LINK_COMMAND_SPEC
> -#define LINK_COMMAND_SPEC "\
> -%{!fdump=*:%{!fsyntax-only:%{!c:%{!M:%{!MM:%{!E:%{!S:\
> -    %(linker) %l %X %{d} %{s} %{t} %{Z} \
> -    %{A} %{e*} %{m} %{r} %{x} \
> -    %{o*}%{!o:-o a.out} \
> -    %{!A:%{!nostdlib:%{!nostartfiles:%S}}} \
> -    %{L*} %(link_libgcc) %o %{fprofile-arcs|fprofile-generate*|coverage:-lgcov} \
> -    %{fopenmp|ftree-parallelize-loops=*: \
> -      %{static|static-libgcc|static-libstdc++|static-libgfortran: libgomp.a%s; : -lgomp } } \
> -    %{!nostdlib:%{!nodefaultlibs:  %(link_ssp) %G %L }} \
> -    %{!A:%{!nostdlib:%{!nostartfiles:%E}}} %{T*} %{F*} }}}}}}}\n\
> -%{!fdump=*:%{!fsyntax-only:%{!c:%{!M:%{!MM:%{!E:%{!S:\
> -    %{.c|.cc|.C|.cpp|.cp|.c++|.cxx|.CPP|.m|.mm: \
> -    %{g*:%{!gstabs*:%{!g0: dsymutil %{o*:%*}%{!o:a.out}}}}}}}}}}}}"
>  
> +/* We will default to generation of flat debug files.  This is more
> +   compatible with the majority of c/l and configury projects.
> +   An new c/l switch is invented here (-mdysm) that causes dsymutil
> +   to generate a .dSYM directory structure.   This latter is the 
> +   behavior of the XCode toolset on an OSX/Darwin system. */
> +
> +#undef DSYMUTIL_SPEC
> +#define DSYMUTIL_SPEC \
> +"%{!fdump=*:%{!fsyntax-only:%{!c:%{!M:%{!MM:%{!E:%{!S:\
> +    %{g*:%{!gstabs*:%{!g0: " DSYMUTIL " %{Zwds:-Wdsymutil} \
> +      %{!mdsym:-f } %{o*:%*}%{!o:a.out}}}}}}}}}}}"
> +
>  /* libSystem contains unwind information for signal frames.  */
>  #define DARWIN_LIBSYSTEM_HAS_UNWIND
>  
> @@ -50,7 +47,7 @@ along with GCC; see the file COPYING3.  If not see
>  #define ASM_OUTPUT_ALIGNED_COMMON(FILE, NAME, SIZE, ALIGN)		\
>    do {									\
>      unsigned HOST_WIDE_INT _new_size = (SIZE);				\
> -    fprintf ((FILE), ".comm ");						\
> +    fprintf ((FILE), "\t.comm ");						\
>      assemble_name ((FILE), (NAME));					\
>      if (_new_size == 0) _new_size = 1;					\
>      fprintf ((FILE), ","HOST_WIDE_INT_PRINT_UNSIGNED",%u\n",		\

>