Add slim-lto support to gcc's build machinery

[Markus Trippelsdorf <markus at trippelsdorf dot de>]

Hi,

now that slim-lto objects are enabled by default, it would be nice to
use them when building gcc with bootstrap-lto. The following patch
implements the handling of these objects in gcc's build machinery.
(Once -fuse-linker-plugin is made the default, -ffat-lto-objects in
config/bootstrap-lto.mk could be dropped.)

LTO-Bootstrapped on x86_64-linux (with default -fuse-linker-plugin).
The patch was already approved by Paolo Bonzini.

Please apply, because I don't have access.
Thanks.

2013-11-20  Markus Trippelsdorf  <markus@trippelsdorf.de>

	* libtool.m4 : Handle slim-lto objects.
	* ltmain.sh: Handle lto options.

diff --git a/libtool.m4 b/libtool.m4
index 797468f02a5a..c55b6eba7a94 100644
--- a/libtool.m4
+++ b/libtool.m4
@@ -3440,6 +3440,7 @@ for ac_symprfx in "" "_"; do
   else
     lt_cv_sys_global_symbol_pipe="sed -n -e 's/^.*[[	 ]]\($symcode$symcode*\)[[	 ]][[	 ]]*$ac_symprfx$sympat$opt_cr$/$symxfrm/p'"
   fi
+  lt_cv_sys_global_symbol_pipe="$lt_cv_sys_global_symbol_pipe | sed '/ __gnu_lto/d'"
 
   # Check to see that the pipe works correctly.
   pipe_works=no
@@ -4459,7 +4460,7 @@ _LT_EOF
       if $LD --help 2>&1 | $EGREP ': supported targets:.* elf' > /dev/null \
 	 && test "$tmp_diet" = no
       then
-	tmp_addflag=
+	tmp_addflag=' $pic_flag'
 	tmp_sharedflag='-shared'
 	case $cc_basename,$host_cpu in
         pgcc*)				# Portland Group C compiler
@@ -5525,8 +5526,8 @@ if test "$_lt_caught_CXX_error" != yes; then
       # Check if GNU C++ uses GNU ld as the underlying linker, since the
       # archiving commands below assume that GNU ld is being used.
       if test "$with_gnu_ld" = yes; then
-        _LT_TAGVAR(archive_cmds, $1)='$CC -shared -nostdlib $predep_objects $libobjs $deplibs $postdep_objects $compiler_flags ${wl}-soname $wl$soname -o $lib'
-        _LT_TAGVAR(archive_expsym_cmds, $1)='$CC -shared -nostdlib $predep_objects $libobjs $deplibs $postdep_objects $compiler_flags ${wl}-soname $wl$soname ${wl}-retain-symbols-file $wl$export_symbols -o $lib'
+        _LT_TAGVAR(archive_cmds, $1)='$CC $pic_flag -shared -nostdlib $predep_objects $libobjs $deplibs $postdep_objects $compiler_flags ${wl}-soname $wl$soname -o $lib'
+        _LT_TAGVAR(archive_expsym_cmds, $1)='$CC $pic_flag -shared -nostdlib $predep_objects $libobjs $deplibs $postdep_objects $compiler_flags ${wl}-soname $wl$soname ${wl}-retain-symbols-file $wl$export_symbols -o $lib'
 
         _LT_TAGVAR(hardcode_libdir_flag_spec, $1)='${wl}-rpath ${wl}$libdir'
         _LT_TAGVAR(export_dynamic_flag_spec, $1)='${wl}--export-dynamic'
@@ -6503,6 +6504,13 @@ public class foo {
 };
 _LT_EOF
 ])
+
+_lt_libdeps_save_CFLAGS=$CFLAGS
+case "$CC $CFLAGS " in #(
+*\ -flto*\ *) CFLAGS="$CFLAGS -fno-lto" ;;
+*\ -fwhopr*\ *) CFLAGS="$CFLAGS -fno-whopr" ;;
+esac
+
 dnl Parse the compiler output and extract the necessary
 dnl objects, libraries and library flags.
 if AC_TRY_EVAL(ac_compile); then
@@ -6551,6 +6559,7 @@ if AC_TRY_EVAL(ac_compile); then
        fi
        ;;
 
+    *.lto.$objext) ;; # Ignore GCC LTO objects
     *.$objext)
        # This assumes that the test object file only shows up
        # once in the compiler output.
@@ -6586,6 +6595,7 @@ else
 fi
 
 $RM -f confest.$objext
+CFLAGS=$_lt_libdeps_save_CFLAGS
 
 # PORTME: override above test on systems where it is broken
 m4_if([$1], [CXX],
diff --git a/ltmain.sh b/ltmain.sh
index a03433f17894..2e0910194f24 100644
--- a/ltmain.sh
+++ b/ltmain.sh
@@ -4980,7 +4980,8 @@ func_mode_link ()
       # @file GCC response files
       # -tp=* Portland pgcc target processor selection
       -64|-mips[0-9]|-r[0-9][0-9]*|-xarch=*|-xtarget=*|+DA*|+DD*|-q*|-m*| \
-      -t[45]*|-txscale*|-p|-pg|--coverage|-fprofile-*|-F*|@*|-tp=*)
+      -t[45]*|-txscale*|-p|-pg|--coverage|-fprofile-*|-F*|@*|-tp=*| \
+      -O*|-flto*|-fwhopr|-fuse-linker-plugin)
         func_quote_for_eval "$arg"
 	arg="$func_quote_for_eval_result"
         func_append compile_command " $arg"
-- 
Markus