Re: [RFA] PR13946 [1/3] toplevel configure/makefile objc/boehm-gc

[David Ayers <d dot ayers at inode dot at>]

Paolo Bonzini schrieb:
> 
> An alternative possibility is this:
> - get rid of boehm-gc within the libgcj variable.
> - readd boehm-gc to every noconfigdirs="$noconfigdirs ${libgcj}" line of
> configure.in; later we can refine this to include only those systems
> where boehm-gc is not working.
> - put the AC_ARG_ENABLE after the last such line of configure.in, and
> raise an error there if noconfigdirs includes boehm-gc
> - add another "if", after the AC_ARG_ENABLE, that prevents boehm-gc from
> building if enable_objc_gc is not specified and target_configdirs does
> not include libgcj.
> 
> Actually, the last step is not necessary as, in the worst case, it will
> cause an unnecessary build of boehm-gc.  If people do not like this (as
> I think), I guess your patch is good enough with the libgcj_saved change
> (but I cannot approve it).

After clearing up some of my confusion about
--disable-libgcj/--enable-libgcj, I think I've got most of this
alternative now.

Instead of searching for libgcj in target_configdirs (I don't think
libgcj is ever in there, yet even if I searched for target-libjava it
wasn't clear at which point this should be done), I checked for whether
java was enabled with/without enabled_libgcj and added target-boehm-gc
to noconfigdirs accordingly.  Would this be acceptable?

I'll start bootstrapping the attached patch with following configurations:

--enable-languages=c,objc
--enable-languages=c,objc --enable-objc-gc

--enable-languages=c,objc,java
--enable-languages=c,objc,java --enable-objc-gc --disable-libgcj

--enable-objc-gc --disable-libgcj

Any thoughts, further suggestions?
OK, for the trunk if bootstraps and tests pass?

Cheers,
David

2006-05-20  David Ayers  <d.ayers@inode.at>

	PR libobjc/13946
	* Makefile.def: Add dependancies for libobjc which boehm-gc.
	* Makefile.in: Regenerate.
	* configure.in: Add --enable-objc-gc at toplevel and have it
	enable boehm-gc for Objective-C.
	Remove target-boehm-gc from libgcj.
	Add target-boehm-gc to target_libraries.
	Add target-boehm-gc to noconfigdirs where ${libgcj}
	is specified.
	* configure: Regenerate.
	
Index: Makefile.def
===================================================================
--- Makefile.def	(Revision 113722)
+++ Makefile.def	(Arbeitskopie)
@@ -445,7 +445,9 @@
 dependencies = { module=all-target-libjava; on=all-target-boehm-gc; };
 dependencies = { module=all-target-libjava; on=all-target-qthreads; };
 dependencies = { module=all-target-libjava; on=all-target-libffi; };
+dependencies = { module=configure-target-libobjc; on=configure-target-boehm-gc; };
 dependencies = { module=all-target-libobjc; on=all-target-libiberty; };
+dependencies = { module=all-target-libobjc; on=all-target-boehm-gc; };
 dependencies = { module=all-target-libstdc++-v3; on=all-target-libiberty; };
 
 // Target modules in the 'src' repository.
Index: configure.in
===================================================================
--- configure.in	(Revision 113722)
+++ configure.in	(Arbeitskopie)
@@ -134,7 +134,6 @@
 
 # libgcj represents the runtime libraries only used by gcj.
 libgcj="target-libffi \
-	target-boehm-gc \
 	target-zlib \
 	target-qthreads \
 	target-libjava"
@@ -150,6 +149,7 @@
 		target-libssp \
 		target-libgcc-math \
 		target-libgfortran \
+		target-boehm-gc \
 		${libgcj} \
 		target-libobjc \
 		target-libada \
@@ -379,7 +379,7 @@
 
 case "${target}" in
   *-*-chorusos)
-    noconfigdirs="$noconfigdirs target-newlib target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs target-newlib target-libgloss target-boehm-gc ${libgcj}"
     ;;
   powerpc-*-darwin*)
     noconfigdirs="$noconfigdirs bfd binutils ld gas opcodes gdb gprof"
@@ -388,10 +388,10 @@
   *-*-darwin*)
     noconfigdirs="$noconfigdirs ld gas gdb gprof"
     noconfigdirs="$noconfigdirs sim target-rda"
-    noconfigdirs="$noconfigdirs ${libgcj}"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj}"
     ;;
   *-*-freebsd[[12]] | *-*-freebsd[[12]].* | *-*-freebsd*aout*)
-    noconfigdirs="$noconfigdirs target-newlib target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs target-newlib target-libgloss target-boehm-gc ${libgcj}"
     ;;
   *-*-freebsd*)
     noconfigdirs="$noconfigdirs target-newlib target-libgloss"
@@ -405,13 +405,13 @@
       i*86-*-*) ;;
       alpha*-*-*) ;;
       *)
-	noconfigdirs="$noconfigdirs ${libgcj}"
+	noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj}"
 	;;
     esac
     ;;
   *-*-kaos*)
     # Remove unsupported stuff on all kaOS configurations.
-    skipdirs="target-libiberty ${libgcj} target-libstdc++-v3 target-librx"
+    skipdirs="target-libiberty target-boehm-gc ${libgcj} target-libstdc++-v3 target-librx"
     skipdirs="$skipdirs target-libobjc target-examples target-groff target-gperf"
     skipdirs="$skipdirs zlib fastjar target-libjava target-boehm-gc target-zlib"
     noconfigdirs="$noconfigdirs target-libgloss"
@@ -425,25 +425,25 @@
       i*86-*-netbsdelf*) ;;
       arm*-*-netbsdelf*) ;;
       *)
-	noconfigdirs="$noconfigdirs ${libgcj}"
+	noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj}"
 	;;
     esac
     ;;
   *-*-netware*)
-    noconfigdirs="$noconfigdirs target-newlib target-libiberty target-libgloss ${libgcj} target-libmudflap"
+    noconfigdirs="$noconfigdirs target-newlib target-libiberty target-libgloss target-boehm-gc ${libgcj} target-libmudflap"
     ;;
   *-*-rtems*)
-    noconfigdirs="$noconfigdirs target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs target-libgloss target-boehm-gc ${libgcj}"
     ;;
     # The tpf target doesn't support gdb yet.
   *-*-tpf*)
-    noconfigdirs="$noconfigdirs target-newlib target-libgloss target-libiberty ${libgcj} target-libmudflap gdb tcl tk libgui itcl"
+    noconfigdirs="$noconfigdirs target-newlib target-libgloss target-libiberty target-boehm-gc ${libgcj} target-libmudflap gdb tcl tk libgui itcl"
     ;;
   *-*-uclinux*)
-    noconfigdirs="$noconfigdirs target-newlib target-libgloss target-rda ${libgcj}"
+    noconfigdirs="$noconfigdirs target-newlib target-libgloss target-rda target-boehm-gc ${libgcj}"
     ;;
   *-*-vxworks*)
-    noconfigdirs="$noconfigdirs target-newlib target-libgloss target-libiberty target-libstdc++-v3 ${libgcj}"
+    noconfigdirs="$noconfigdirs target-newlib target-libgloss target-libiberty target-libstdc++-v3 target-boehm-gc ${libgcj}"
     ;;
   alpha*-dec-osf*)
     # ld works, but does not support shared libraries.
@@ -452,7 +452,7 @@
     noconfigdirs="$noconfigdirs gas ld fileutils target-newlib target-libgloss"
     ;;
   alpha*-*-*vms*)
-    noconfigdirs="$noconfigdirs gdb ld target-newlib target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs gdb ld target-newlib target-libgloss target-boehm-gc ${libgcj}"
     ;;
   alpha*-*-linux*)
     # newlib is not 64 bit ready
@@ -460,16 +460,16 @@
     ;;
   alpha*-*-*)
     # newlib is not 64 bit ready
-    noconfigdirs="$noconfigdirs target-newlib target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs target-newlib target-libgloss target-boehm-gc ${libgcj}"
     ;;
   am33_2.0-*-linux*)
-    noconfigdirs="$noconfigdirs ${libgcj} target-newlib target-libgloss"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj} target-newlib target-libgloss"
     ;;
   sh-*-linux*)
-    noconfigdirs="$noconfigdirs ${libgcj} target-newlib target-libgloss"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj} target-newlib target-libgloss"
     ;;    
   sh*-*-pe|mips*-*-pe|*arm-wince-pe)
-    noconfigdirs="$noconfigdirs ${libgcj}"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj}"
     noconfigdirs="$noconfigdirs target-examples"
     noconfigdirs="$noconfigdirs target-libiberty texinfo send-pr"
     noconfigdirs="$noconfigdirs tcl tk itcl libgui sim"
@@ -484,12 +484,12 @@
     esac
     ;;
   arc-*-*)
-    noconfigdirs="$noconfigdirs target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs target-libgloss target-boehm-gc ${libgcj}"
     ;;
   arm-semi-aof )
     ;;
   arm-*-coff | strongarm-*-coff | xscale-*-coff)
-    noconfigdirs="$noconfigdirs ${libgcj}"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj}"
     ;;
   arm-*-elf* | strongarm-*-elf* | xscale-*-elf* | arm*-*-eabi* )
     noconfigdirs="$noconfigdirs target-libffi target-qthreads"
@@ -499,25 +499,25 @@
     noconfigdirs="$noconfigdirs target-libjava target-libobjc"
     ;;
   arm*-*-symbianelf*)
-    noconfigdirs="$noconfigdirs ${libgcj} target-libiberty"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj} target-libiberty"
     ;;
   arm-*-pe*)
-    noconfigdirs="$noconfigdirs target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs target-libgloss target-boehm-gc ${libgcj}"
     ;;
   thumb-*-coff)
-    noconfigdirs="$noconfigdirs target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs target-libgloss target-boehm-gc ${libgcj}"
     ;;
   thumb-*-elf)
-    noconfigdirs="$noconfigdirs target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs target-libgloss target-boehm-gc ${libgcj}"
     ;;
   thumb-*-pe)
-    noconfigdirs="$noconfigdirs target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs target-libgloss target-boehm-gc ${libgcj}"
     ;;
   arm-*-riscix*)
-    noconfigdirs="$noconfigdirs ld target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs ld target-libgloss target-boehm-gc ${libgcj}"
     ;;
   avr-*-*)
-    noconfigdirs="$noconfigdirs target-libiberty target-libstdc++-v3 ${libgcj}"
+    noconfigdirs="$noconfigdirs target-libiberty target-libstdc++-v3 target-boehm-gc ${libgcj}"
     ;;
   bfin-*-*)
     noconfigdirs="$noconfigdirs target-libgloss gdb"
@@ -526,10 +526,10 @@
     fi
     ;;
   c4x-*-* | tic4x-*-*)
-    noconfigdirs="$noconfigdirs target-libstdc++-v3 target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs target-libstdc++-v3 target-libgloss target-boehm-gc ${libgcj}"
     ;;
   c54x*-*-* | tic54x-*-*)
-    noconfigdirs="$noconfigdirs target-libstdc++-v3 target-libgloss ${libgcj} gcc gdb newlib"
+    noconfigdirs="$noconfigdirs target-libstdc++-v3 target-libgloss target-boehm-gc ${libgcj} gcc gdb newlib"
     ;;
   cris-*-* | crisv32-*-*)
     unsupported_languages="$unsupported_languages java"
@@ -544,29 +544,29 @@
 	noconfigdirs="$noconfigdirs target-newlib target-libgloss";;
       *)
 	unsupported_languages="$unsupported_languages fortran"
-	noconfigdirs="$noconfigdirs ${libgcj} target-newlib target-libgloss";;
+	noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj} target-newlib target-libgloss";;
     esac
     ;;
   crx-*-*)
-    noconfigdirs="$noconfigdirs target-libstdc++-v3 target-mudflap ${libgcj}"
+    noconfigdirs="$noconfigdirs target-libstdc++-v3 target-mudflap target-boehm-gc ${libgcj}"
     ;;
   d10v-*-*)
-    noconfigdirs="$noconfigdirs target-libstdc++-v3 target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs target-libstdc++-v3 target-libgloss target-boehm-gc ${libgcj}"
     ;;
   d30v-*-*)
-    noconfigdirs="$noconfigdirs ${libgcj} gdb"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj} gdb"
     ;;
   fr30-*-elf*)
-    noconfigdirs="$noconfigdirs ${libgcj} gdb"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj} gdb"
     ;;
   frv-*-*)
-    noconfigdirs="$noconfigdirs ${libgcj}"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj}"
     ;;
   h8300*-*-*)
-    noconfigdirs="$noconfigdirs target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs target-libgloss target-boehm-gc ${libgcj}"
     ;;
   h8500-*-*)
-    noconfigdirs="$noconfigdirs target-libstdc++-v3 target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs target-libstdc++-v3 target-libgloss target-boehm-gc ${libgcj}"
     ;;
   hppa1.1-*-osf* | hppa1.1-*-bsd* )
     ;;
@@ -582,15 +582,15 @@
   hppa*-*-lites* | \
   hppa*-*-openbsd* | \
   hppa*64*-*-*)
-    noconfigdirs="$noconfigdirs ${libgcj}"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj}"
     ;;
   hppa*-*-*)
     # According to Alexandre Oliva <aoliva@redhat.com>, libjava won't
     # build on HP-UX 10.20.
-    noconfigdirs="$noconfigdirs ld shellutils ${libgcj}"
+    noconfigdirs="$noconfigdirs ld shellutils target-boehm-gc ${libgcj}"
     ;;
   i960-*-*)
-    noconfigdirs="$noconfigdirs ${libgcj} gdb"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj} gdb"
     ;;
   ia64*-*-elf*)
     # No gdb support yet.
@@ -598,19 +598,19 @@
     ;;
   ia64*-**-hpux*)
     # No gdb or ld support yet.
-    noconfigdirs="$noconfigdirs ${libgcj} readline mmalloc libgui itcl gdb ld"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj} readline mmalloc libgui itcl gdb ld"
     ;;
   i370-*-opened*)
     ;;
   i[[3456789]]86-*-coff | i[[3456789]]86-*-elf)
-    noconfigdirs="$noconfigdirs ${libgcj}"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj}"
     ;;
   i[[3456789]]86-*-linux*)
     # The GCC port for glibc1 has no MD_FALLBACK_FRAME_STATE_FOR, so let's
     # not build java stuff by default.
     case "${target}" in
       *-*-*libc1*)
-	noconfigdirs="$noconfigdirs ${libgcj}";;
+	noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj}";;
     esac
 
     # This section makes it possible to build newlib natively on linux.
@@ -626,7 +626,7 @@
     ;;
   i[[3456789]]86-*-mingw32*)
     target_configdirs="$target_configdirs target-mingw"
-    noconfigdirs="$noconfigdirs expect target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs expect target-libgloss target-boehm-gc ${libgcj}"
 
     # Can't build gdb for mingw32 if not native.
     case "${host}" in
@@ -637,7 +637,7 @@
     ;;    
   *-*-cygwin*)
     target_configdirs="$target_configdirs target-libtermcap target-winsup"
-    noconfigdirs="$noconfigdirs target-gperf target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs target-gperf target-libgloss target-boehm-gc ${libgcj}"
     # always build newlib if winsup directory is present.
     if test -d "$srcdir/winsup"; then
       skipdirs=`echo " ${skipdirs} " | sed -e 's/ target-newlib / /'`
@@ -656,39 +656,39 @@
   i[[3456789]]86-*-uwin* | i[[3456789]]86-*-interix* )
     ;;
   i[[3456789]]86-*-pe)
-    noconfigdirs="$noconfigdirs target-libstdc++-v3 target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs target-libstdc++-v3 target-libgloss target-boehm-gc ${libgcj}"
     ;;
   i[[3456789]]86-*-sco3.2v5*)
     # The linker does not yet know about weak symbols in COFF,
     # and is not configured to handle mixed ELF and COFF.
-    noconfigdirs="$noconfigdirs ld target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs ld target-libgloss target-boehm-gc ${libgcj}"
     ;;
   i[[3456789]]86-*-sco*)
-    noconfigdirs="$noconfigdirs gprof target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs gprof target-libgloss target-boehm-gc ${libgcj}"
     ;;
   i[[3456789]]86-*-solaris2*)
     noconfigdirs="$noconfigdirs target-libgloss"
     ;;
   i[[3456789]]86-*-sysv4*)
-    noconfigdirs="$noconfigdirs target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs target-libgloss target-boehm-gc ${libgcj}"
     ;;
   i[[3456789]]86-*-beos*)
-    noconfigdirs="$noconfigdirs gdb target-newlib target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs gdb target-newlib target-libgloss target-boehm-gc ${libgcj}"
     ;;
   i[[3456789]]86-*-rdos*)
     noconfigdirs="$noconfigdirs gdb target-newlib target-libgloss"
     ;;
   m32r-*-*)
-    noconfigdirs="$noconfigdirs ${libgcj}"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj}"
     ;;
   m68hc11-*-*|m6811-*-*|m68hc12-*-*|m6812-*-*)
-    noconfigdirs="$noconfigdirs target-libiberty target-libstdc++-v3 ${libgcj}"
+    noconfigdirs="$noconfigdirs target-libiberty target-libstdc++-v3 target-boehm-gc ${libgcj}"
     ;;
   m68k-*-elf*)
-    noconfigdirs="$noconfigdirs ${libgcj}"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj}"
     ;;
   m68k-*-coff*)
-    noconfigdirs="$noconfigdirs ${libgcj}"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj}"
     ;;
   mcore-*-pe*)
   # The EPOC C++ environment does not support exceptions or rtti,
@@ -700,78 +700,78 @@
     unsupported_languages="$unsupported_languages fortran java"
     ;;
   mn10200-*-*)
-    noconfigdirs="$noconfigdirs ${libgcj}"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj}"
     ;;
   mn10300-*-*)
-    noconfigdirs="$noconfigdirs ${libgcj}"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj}"
     ;;
   mt-*-*)
     noconfigdirs="$noconfigdirs sim"
     ;;
   powerpc-*-aix*)
     # copied from rs6000-*-* entry
-    noconfigdirs="$noconfigdirs gprof target-libgloss target-libssp ${libgcj}"
+    noconfigdirs="$noconfigdirs gprof target-libgloss target-libssp target-boehm-gc ${libgcj}"
     ;;
   powerpc*-*-winnt* | powerpc*-*-pe* | ppc*-*-pe)
     target_configdirs="$target_configdirs target-winsup"
-    noconfigdirs="$noconfigdirs gdb tcl tk make expect target-libgloss itcl gnuserv ${libgcj}"
+    noconfigdirs="$noconfigdirs gdb tcl tk make expect target-libgloss itcl gnuserv target-boehm-gc ${libgcj}"
     # always build newlib.
     skipdirs=`echo " ${skipdirs} " | sed -e 's/ target-newlib / /'`
     ;;
     # This is temporary until we can link against shared libraries
   powerpcle-*-solaris*)
-    noconfigdirs="$noconfigdirs gdb sim make tcl tk expect itcl gnuserv ${libgcj}"
+    noconfigdirs="$noconfigdirs gdb sim make tcl tk expect itcl gnuserv target-boehm-gc ${libgcj}"
     ;;
   powerpc-*-beos*)
-    noconfigdirs="$noconfigdirs gdb target-newlib target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs gdb target-newlib target-libgloss target-boehm-gc ${libgcj}"
     ;;
   powerpc-*-eabi)
-    noconfigdirs="$noconfigdirs ${libgcj}"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj}"
     ;;
   powerpc-*-eabi* | powerpcle-*-eabi* | powerpc-*-rtems* )
     ;;
   rs6000-*-lynxos*)
-    noconfigdirs="$noconfigdirs target-newlib gprof ${libgcj}"
+    noconfigdirs="$noconfigdirs target-newlib gprof target-boehm-gc ${libgcj}"
     ;;
   rs6000-*-aix*)
-    noconfigdirs="$noconfigdirs gprof target-libgloss target-libssp ${libgcj}"
+    noconfigdirs="$noconfigdirs gprof target-libgloss target-libssp target-boehm-gc ${libgcj}"
     ;;
   rs6000-*-*)
-    noconfigdirs="$noconfigdirs gprof ${libgcj}"
+    noconfigdirs="$noconfigdirs gprof target-boehm-gc ${libgcj}"
     ;;
   m68k-apollo-*)
-    noconfigdirs="$noconfigdirs ld binutils gprof target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs ld binutils gprof target-libgloss target-boehm-gc ${libgcj}"
     ;;
   mips*-*-irix5*)
-    noconfigdirs="$noconfigdirs gprof target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs gprof target-libgloss target-boehm-gc ${libgcj}"
     ;;
   mips*-*-irix6*)
     # Linking libjava exceeds command-line length limits on at least
     # IRIX 6.2, but not on IRIX 6.5.
     # Also, boehm-gc won't build on IRIX 6.5, according to Jeffrey Oldham
     # <oldham@codesourcery.com>
-    noconfigdirs="$noconfigdirs gprof target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs gprof target-libgloss target-boehm-gc ${libgcj}"
     ;;
   mips*-dec-bsd*)
-    noconfigdirs="$noconfigdirs gprof target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs gprof target-libgloss target-boehm-gc ${libgcj}"
     ;;
   mips*-*-bsd*)
-    noconfigdirs="$noconfigdirs gprof target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs gprof target-libgloss target-boehm-gc ${libgcj}"
     ;;
   mipstx39-*-*)
-    noconfigdirs="$noconfigdirs gprof ${libgcj}"   # same as generic mips
+    noconfigdirs="$noconfigdirs gprof target-boehm-gc ${libgcj}"   # same as generic mips
     ;;
   mips64*-*-linux*)
-    noconfigdirs="$noconfigdirs target-newlib ${libgcj}"
+    noconfigdirs="$noconfigdirs target-newlib target-boehm-gc ${libgcj}"
     ;;
   mips*-*-linux*)
     noconfigdirs="$noconfigdirs target-newlib target-libgloss"
     ;;
   mips*-*-*)
-    noconfigdirs="$noconfigdirs gprof ${libgcj}"
+    noconfigdirs="$noconfigdirs gprof target-boehm-gc ${libgcj}"
     ;;
   romp-*-*)
-    noconfigdirs="$noconfigdirs bfd binutils ld gas opcodes target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs bfd binutils ld gas opcodes target-libgloss target-boehm-gc ${libgcj}"
     ;;
   sh-*-* | sh64-*-*)
     case "${host}" in
@@ -780,19 +780,19 @@
       i[[3456789]]86-*-msdosdjgpp*) ;; # don't add gprof back in
       *) skipdirs=`echo " ${skipdirs} " | sed -e 's/ gprof / /'` ;;
     esac
-    noconfigdirs="$noconfigdirs target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs target-libgloss target-boehm-gc ${libgcj}"
     ;;
   sparc-*-elf*)
-    noconfigdirs="$noconfigdirs ${libgcj}"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj}"
     ;;
   sparc64-*-elf*)
-    noconfigdirs="$noconfigdirs ${libgcj}"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj}"
     ;;
   sparclite-*-*)
-    noconfigdirs="$noconfigdirs ${libgcj}"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj}"
     ;;
   sparc-*-sunos4*)
-    noconfigdirs="$noconfigdirs ${libgcj}"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj}"
     if test x${is_cross_compiler} != xno ; then
            noconfigdirs="$noconfigdirs gdb target-newlib target-libgloss"
     else
@@ -800,42 +800,42 @@
     fi
     ;;
   sparc-*-solaris2.[[0-6]] | sparc-*-solaris2.[[0-6]].*)
-    noconfigdirs="$noconfigdirs ${libgcj}"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj}"
     ;;
   sparc-*-solaris* | sparc64-*-solaris* | sparcv9-*-solaris*)
     ;;
   v810-*-*)
-    noconfigdirs="$noconfigdirs bfd binutils gas gcc gdb ld target-libstdc++-v3 opcodes target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs bfd binutils gas gcc gdb ld target-libstdc++-v3 opcodes target-libgloss target-boehm-gc ${libgcj}"
     ;;
   v850-*-*)
-    noconfigdirs="$noconfigdirs target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs target-libgloss target-boehm-gc ${libgcj}"
     ;;
   v850e-*-*)
-    noconfigdirs="$noconfigdirs target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs target-libgloss target-boehm-gc ${libgcj}"
     ;;
   v850ea-*-*)
-    noconfigdirs="$noconfigdirs target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs target-libgloss target-boehm-gc ${libgcj}"
     ;;
   vax-*-vms)
-    noconfigdirs="$noconfigdirs bfd binutils gdb ld target-newlib opcodes target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs bfd binutils gdb ld target-newlib opcodes target-libgloss target-boehm-gc ${libgcj}"
     ;;
   vax-*-*)
-    noconfigdirs="$noconfigdirs target-newlib target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs target-newlib target-libgloss target-boehm-gc ${libgcj}"
     ;;
   xtensa-*-*)
-    noconfigdirs="$noconfigdirs ${libgcj}"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj}"
     ;;
   ip2k-*-*)
-    noconfigdirs="$noconfigdirs target-libiberty target-libstdc++-v3 ${libgcj}"
+    noconfigdirs="$noconfigdirs target-libiberty target-libstdc++-v3 target-boehm-gc ${libgcj}"
     ;;
   *-*-linux* | *-*-gnu* | *-*-k*bsd*-gnu)
     noconfigdirs="$noconfigdirs target-newlib target-libgloss"
     ;;
   *-*-lynxos*)
-    noconfigdirs="$noconfigdirs target-newlib target-libgloss ${libgcj}"
+    noconfigdirs="$noconfigdirs target-newlib target-libgloss target-boehm-gc ${libgcj}"
     ;; 
   *-*-*)
-    noconfigdirs="$noconfigdirs ${libgcj}"
+    noconfigdirs="$noconfigdirs target-boehm-gc ${libgcj}"
     ;;
 esac
 
@@ -1323,6 +1323,34 @@
   fi
 done
 
+# Check for Boehm's garbage collector
+AC_ARG_ENABLE(objc-gc,
+[  --enable-objc-gc       enable the use of Boehm's garbage collector with
+                          the GNU Objective-C runtime.],
+[case ,${enable_languages},:${enable_objc_gc}:${noconfigdirs} in
+  *,objc,*:*:yes:*target-boehm-gc*)
+    AC_MSG_ERROR([Boehm's garbage collector was requested yet not supported in this configuration])
+    ;;
+esac])
+
+# Make sure we only build Boehm's garbage collector if required.
+case ,${enable_languages},:${enable_libgcj}:${enable_objc_gc} in
+  *,objc,*:*:yes)
+    # Keep target-boehm-gc if requested for Objective-C.
+    ;;
+  *,java,*:no:*)
+    # Remove target-boehm-gc if libgcj has been disabled explicitly.
+    noconfigdirs="$noconfigdirs target-boehm-gc"
+    ;;
+  *,java,*:*:*)
+    # Keep target-boehm-gc by default for Java.
+    ;;
+  *)
+    # Otherwise remove target-boehm-gc.
+    noconfigdirs="$noconfigdirs target-boehm-gc"
+    ;;
+esac
+
 # Remove the entries in $skipdirs and $noconfigdirs from $configdirs,
 # $build_configdirs and $target_configdirs.
 # If we have the source for $noconfigdirs entries, add them to $notsupp.