Patchwork 6/n: trans-mem: runtime

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Submitter Torvald Riegel
Date Nov. 6, 2011, 7:44 p.m.
Message ID <1320608670.18023.326.camel@triegel.csb>
Download mbox | patch
Permalink /patch/123960/
State New
Headers show

Comments

Torvald Riegel - Nov. 6, 2011, 7:44 p.m.
On Thu, 2011-11-03 at 20:15 +0000, Joseph S. Myers wrote:
> On Thu, 3 Nov 2011, Aldy Hernandez wrote:
> 
> > Index: libitm/acinclude.m4
> > ===================================================================
> > --- libitm/acinclude.m4	(.../trunk)	(revision 0)
> > +++ libitm/acinclude.m4	(.../branches/transactional-memory)	(revision
> > 180773)
> > @@ -0,0 +1,343 @@
> > +dnl ----------------------------------------------------------------------
> > +dnl This whole bit snagged from libgfortran.
> 
> If you need a configure test in more than one library, do not copy it like 
> this; put a common macro in config/ and use it from both libraries.
> 
> > +dnl ----------------------------------------------------------------------
> > +dnl This whole bit snagged from libstdc++-v3.
> 
> Likewise.  There may well be some bits that for whatever reason need to be 
> similar but different, or that are specific to libitm, but if something 
> can be shared then it should be shared.

Is the attached patch what you'd like to see? It doesn't yet use the
generic macros in libgfortran, libgomp, or libstdc++v3, but this could
be added after the TM merge (and somebody who knows more about the build
system than me should have a look first, probably..).
Sync-built-in checks haven't been generalized yet because libitm will
likely switch to the new cxx-mem-model built-ins. LIBITM_ENABLE_SYMVERS
is different from the libstdc++v3 version. Is GCC_CHECK_LINKER_FEATURES
at the right place in exportcontrols.m4, or different name/file?
Bootstrapped on x86_64 and tm.exp/libitm tested. 

OK for branch?
commit b81687945ccb46c860acf66cbb8d391e0062882c
Author: Torvald Riegel <triegel@redhat.com>
Date:   Sun Nov 6 20:32:28 2011 +0100

    Generalize AC macros.
    
    	libitm/
    	* acinclude.m4: Move export control checks to
    	../config/exportcontrols.m4. Use GCC_ENABLE; remove LIBITM_ENABLE.
    	* configure.ac: Likewise.
    	* aclocal.m4: Include ../config/exportcontrols.m4.
    	* configure: Regenerate.
    
    	config/
    	* exportcontrols.m4: New file; based on libgfortran's and
    	libstdc++v3's acinclude.m4.

index 0000000..1d9a998
Joseph S. Myers - Nov. 6, 2011, 11:04 p.m.
On Sun, 6 Nov 2011, Torvald Riegel wrote:

> Is the attached patch what you'd like to see? It doesn't yet use the

It's plausible, but really a build system maintainer should look at it.
Torvald Riegel - Nov. 6, 2011, 11:49 p.m.
On Sun, 2011-11-06 at 23:04 +0000, Joseph S. Myers wrote:
> On Sun, 6 Nov 2011, Torvald Riegel wrote:
> 
> > Is the attached patch what you'd like to see? It doesn't yet use the
> 
> It's plausible, but really a build system maintainer should look at it.
> 

So, can we keep this as-is then and fix this after the TM merge
(together with the similar bits in libgfortran, libgomp, and libstc
++v3), or is this a stopper?
If the latter, could the build system maintainers please look at this
soon?

Torvald
Joseph S. Myers - Nov. 7, 2011, 4:32 p.m.
On Mon, 7 Nov 2011, Torvald Riegel wrote:

> On Sun, 2011-11-06 at 23:04 +0000, Joseph S. Myers wrote:
> > On Sun, 6 Nov 2011, Torvald Riegel wrote:
> > 
> > > Is the attached patch what you'd like to see? It doesn't yet use the
> > 
> > It's plausible, but really a build system maintainer should look at it.
> > 
> 
> So, can we keep this as-is then and fix this after the TM merge
> (together with the similar bits in libgfortran, libgomp, and libstc
> ++v3), or is this a stopper?

It would seem reasonable to me to deal with this after the merge - and 
after Rainer's issues from 
<http://gcc.gnu.org/ml/gcc-patches/2011-11/msg00915.html> about unused 
configure checks, Makefile variables etc. are dealt with.

Patch

--- /dev/null
+++ b/config/ChangeLog.tm-merge
@@ -0,0 +1,6 @@ 
+2011-11-07  Torvald Riegel  <triegel@redhat.com>
+
+	Merged from transactional-memory.
+
+	* exportcontrols.m4: New file; based on libgfortran's and
+	libstdc++v3's acinclude.m4.
diff --git a/config/exportcontrols.m4 b/config/exportcontrols.m4
new file mode 100644
index 0000000..78cf3ec
--- /dev/null
+++ b/config/exportcontrols.m4
@@ -0,0 +1,182 @@ 
+dnl ----------------------------------------------------------------------
+dnl This whole bit snagged from libgfortran.
+
+dnl Check whether the target supports hidden visibility.
+AC_DEFUN([GCC_CHECK_ATTRIBUTE_VISIBILITY], [
+  AC_CACHE_CHECK([whether the target supports hidden visibility],
+		 gcc_cv_have_attribute_visibility, [
+  save_CFLAGS="$CFLAGS"
+  CFLAGS="$CFLAGS -Werror"
+  AC_TRY_COMPILE([void __attribute__((visibility("hidden"))) foo(void) { }],
+		 [], gcc_cv_have_attribute_visibility=yes,
+		 gcc_cv_have_attribute_visibility=no)
+  CFLAGS="$save_CFLAGS"])
+  if test $gcc_cv_have_attribute_visibility = yes; then
+    AC_DEFINE(HAVE_ATTRIBUTE_VISIBILITY, 1,
+      [Define to 1 if the target supports __attribute__((visibility(...))).])
+  fi])
+
+dnl Check whether the target supports dllexport
+AC_DEFUN([GCC_CHECK_ATTRIBUTE_DLLEXPORT], [
+  AC_CACHE_CHECK([whether the target supports dllexport],
+		 gcc_cv_have_attribute_dllexport, [
+  save_CFLAGS="$CFLAGS"
+  CFLAGS="$CFLAGS -Werror"
+  AC_TRY_COMPILE([void __attribute__((dllexport)) foo(void) { }],
+		 [], gcc_cv_have_attribute_dllexport=yes,
+		 gcc_cv_have_attribute_dllexport=no)
+  CFLAGS="$save_CFLAGS"])
+  if test $gcc_cv_have_attribute_dllexport = yes; then
+    AC_DEFINE(HAVE_ATTRIBUTE_DLLEXPORT, 1,
+      [Define to 1 if the target supports __attribute__((dllexport)).])
+  fi])
+
+dnl Check whether the target supports symbol aliases.
+AC_DEFUN([GCC_CHECK_ATTRIBUTE_ALIAS], [
+  AC_CACHE_CHECK([whether the target supports symbol aliases],
+		 gcc_cv_have_attribute_alias, [
+  AC_TRY_LINK([
+void foo(void) { }
+extern void bar(void) __attribute__((alias("foo")));],
+    [bar();], gcc_cv_have_attribute_alias=yes, gcc_cv_have_attribute_alias=no)])
+  if test $gcc_cv_have_attribute_alias = yes; then
+    AC_DEFINE(HAVE_ATTRIBUTE_ALIAS, 1,
+      [Define to 1 if the target supports __attribute__((alias(...))).])
+  fi])
+
+
+dnl ----------------------------------------------------------------------
+dnl This whole bit snagged from libstdc++v3.
+
+dnl
+dnl If GNU ld is in use, check to see if tricky linker opts can be used.  If
+dnl the native linker is in use, all variables will be defined to something
+dnl safe (like an empty string).
+dnl
+dnl Defines:
+dnl  SECTION_LDFLAGS='-Wl,--gc-sections' if possible
+dnl  OPT_LDFLAGS='-Wl,-O1' and '-z,relro' if possible
+dnl  LD (as a side effect of testing)
+dnl Sets:
+dnl  with_gnu_ld
+dnl  gcc_ld_is_gold (set to "no" or "yes")
+dnl  gcc_gnu_ld_version (possibly)
+dnl
+dnl The last will be a single integer, e.g., version 1.23.45.0.67.89 will
+dnl set gcc_gnu_ld_version to 12345.  Zeros cause problems.
+dnl
+AC_DEFUN([GCC_CHECK_LINKER_FEATURES], [
+  # If we're not using GNU ld, then there's no point in even trying these
+  # tests.  Check for that first.  We should have already tested for gld
+  # by now (in libtool), but require it now just to be safe...
+  test -z "$SECTION_LDFLAGS" && SECTION_LDFLAGS=''
+  test -z "$OPT_LDFLAGS" && OPT_LDFLAGS=''
+  AC_REQUIRE([AC_PROG_LD])
+  AC_REQUIRE([AC_PROG_AWK])
+
+  # The name set by libtool depends on the version of libtool.  Shame on us
+  # for depending on an impl detail, but c'est la vie.  Older versions used
+  # ac_cv_prog_gnu_ld, but now it's lt_cv_prog_gnu_ld, and is copied back on
+  # top of with_gnu_ld (which is also set by --with-gnu-ld, so that actually
+  # makes sense).  We'll test with_gnu_ld everywhere else, so if that isn't
+  # set (hence we're using an older libtool), then set it.
+  if test x${with_gnu_ld+set} != xset; then
+    if test x${ac_cv_prog_gnu_ld+set} != xset; then
+      # We got through "ac_require(ac_prog_ld)" and still not set?  Huh?
+      with_gnu_ld=no
+    else
+      with_gnu_ld=$ac_cv_prog_gnu_ld
+    fi
+  fi
+
+  # Start by getting the version number.  I think the libtool test already
+  # does some of this, but throws away the result.
+  gcc_ld_is_gold=no
+  if test x"$with_gnu_ld" = x"yes"; then
+    AC_MSG_CHECKING([for ld version])
+    changequote(,)
+    if $LD --version 2>/dev/null | grep 'GNU gold' >/dev/null 2>&1; then
+      gcc_ld_is_gold=yes
+    fi
+    ldver=`$LD --version 2>/dev/null |
+	   sed -e 's/GNU gold /GNU ld /;s/GNU ld version /GNU ld /;s/GNU ld ([^)]*) /GNU ld /;s/GNU ld \([0-9.][0-9.]*\).*/\1/; q'`
+    changequote([,])
+    gcc_gnu_ld_version=`echo $ldver | \
+	   $AWK -F. '{ if (NF<3) [$]3=0; print ([$]1*100+[$]2)*100+[$]3 }'`
+    AC_MSG_RESULT($gcc_gnu_ld_version)
+  fi
+
+  # Set --gc-sections.
+  gcc_have_gc_sections=no
+  if test "$gcc_ld_is_gold" = "yes"; then
+    if $LD --help 2>/dev/null | grep gc-sections >/dev/null 2>&1; then
+      gcc_have_gc_sections=yes
+    fi
+  else
+    gcc_gcsections_min_ld=21602
+    if test x"$with_gnu_ld" = x"yes" &&
+	test $gcc_gnu_ld_version -gt $gcc_gcsections_min_ld ; then
+      gcc_have_gc_sections=yes
+    fi
+  fi
+  if test "$gcc_have_gc_sections" = "yes"; then
+    # Sufficiently young GNU ld it is!  Joy and bunny rabbits!
+    # NB: This flag only works reliably after 2.16.1. Configure tests
+    # for this are difficult, so hard wire a value that should work.
+
+    ac_test_CFLAGS="${CFLAGS+set}"
+    ac_save_CFLAGS="$CFLAGS"
+    CFLAGS='-Wl,--gc-sections'
+
+    # Check for -Wl,--gc-sections
+    AC_MSG_CHECKING([for ld that supports -Wl,--gc-sections])
+    AC_TRY_LINK([ int one(void) { return 1; }
+     int two(void) { return 2; }
+	], [ two(); ] , [ac_gcsections=yes], [ac_gcsections=no])
+    if test "$ac_gcsections" = "yes"; then
+      rm -f conftest.c
+      touch conftest.c
+      if $CC -c conftest.c; then
+	if $LD --gc-sections -o conftest conftest.o 2>&1 | \
+	   grep "Warning: gc-sections option ignored" > /dev/null; then
+	  ac_gcsections=no
+	fi
+      fi
+      rm -f conftest.c conftest.o conftest
+    fi
+    if test "$ac_gcsections" = "yes"; then
+      SECTION_LDFLAGS="-Wl,--gc-sections $SECTION_LDFLAGS"
+    fi
+    AC_MSG_RESULT($ac_gcsections)
+
+    if test "$ac_test_CFLAGS" = set; then
+      CFLAGS="$ac_save_CFLAGS"
+    else
+      # this is the suspicious part
+      CFLAGS=''
+    fi
+  fi
+
+  # Set -z,relro.
+  # Note this is only for shared objects.
+  ac_ld_relro=no
+  if test x"$with_gnu_ld" = x"yes"; then
+    AC_MSG_CHECKING([for ld that supports -Wl,-z,relro])
+    cxx_z_relo=`$LD -v --help 2>/dev/null | grep "z relro"`
+    if test -n "$cxx_z_relo"; then
+      OPT_LDFLAGS="-Wl,-z,relro"
+      ac_ld_relro=yes
+    fi
+    AC_MSG_RESULT($ac_ld_relro)
+  fi
+
+  # Set linker optimization flags.
+  if test x"$with_gnu_ld" = x"yes"; then
+    OPT_LDFLAGS="-Wl,-O1 $OPT_LDFLAGS"
+  fi
+
+  AC_SUBST(SECTION_LDFLAGS)
+  AC_SUBST(OPT_LDFLAGS)
+])
+
+
diff --git a/libitm/acinclude.m4 b/libitm/acinclude.m4
index 8fcde4b..d1642dc 100644
--- a/libitm/acinclude.m4
+++ b/libitm/acinclude.m4
@@ -1,5 +1,6 @@ 
 dnl ----------------------------------------------------------------------
-dnl This whole bit snagged from libgfortran.
+dnl sync built-ins checks are similar to the ones used in libgfortran/libgomp.
+dnl ??? Generalize at some point?
 
 dnl Check whether the target supports __sync_*_compare_and_swap.
 AC_DEFUN([LIBITM_CHECK_SYNC_BUILTINS], [
@@ -26,49 +27,6 @@  AC_DEFUN([LIBITM_CHECK_64BIT_SYNC_BUILTINS], [
 	        [Define to 1 if the target supports 64-bit __sync_*_compare_and_swap])
   fi])
 
-dnl Check whether the target supports hidden visibility.
-AC_DEFUN([LIBITM_CHECK_ATTRIBUTE_VISIBILITY], [
-  AC_CACHE_CHECK([whether the target supports hidden visibility],
-		 libitm_cv_have_attribute_visibility, [
-  save_CFLAGS="$CFLAGS"
-  CFLAGS="$CFLAGS -Werror"
-  AC_TRY_COMPILE([void __attribute__((visibility("hidden"))) foo(void) { }],
-		 [], libitm_cv_have_attribute_visibility=yes,
-		 libitm_cv_have_attribute_visibility=no)
-  CFLAGS="$save_CFLAGS"])
-  if test $libitm_cv_have_attribute_visibility = yes; then
-    AC_DEFINE(HAVE_ATTRIBUTE_VISIBILITY, 1,
-      [Define to 1 if the target supports __attribute__((visibility(...))).])
-  fi])
-
-dnl Check whether the target supports dllexport
-AC_DEFUN([LIBITM_CHECK_ATTRIBUTE_DLLEXPORT], [
-  AC_CACHE_CHECK([whether the target supports dllexport],
-		 libitm_cv_have_attribute_dllexport, [
-  save_CFLAGS="$CFLAGS"
-  CFLAGS="$CFLAGS -Werror"
-  AC_TRY_COMPILE([void __attribute__((dllexport)) foo(void) { }],
-		 [], libitm_cv_have_attribute_dllexport=yes,
-		 libitm_cv_have_attribute_dllexport=no)
-  CFLAGS="$save_CFLAGS"])
-  if test $libitm_cv_have_attribute_dllexport = yes; then
-    AC_DEFINE(HAVE_ATTRIBUTE_DLLEXPORT, 1,
-      [Define to 1 if the target supports __attribute__((dllexport)).])
-  fi])
-
-dnl Check whether the target supports symbol aliases.
-AC_DEFUN([LIBITM_CHECK_ATTRIBUTE_ALIAS], [
-  AC_CACHE_CHECK([whether the target supports symbol aliases],
-		 libitm_cv_have_attribute_alias, [
-  AC_TRY_LINK([
-void foo(void) { }
-extern void bar(void) __attribute__((alias("foo")));],
-    [bar();], libitm_cv_have_attribute_alias=yes, libitm_cv_have_attribute_alias=no)])
-  if test $libitm_cv_have_attribute_alias = yes; then
-    AC_DEFINE(HAVE_ATTRIBUTE_ALIAS, 1,
-      [Define to 1 if the target supports __attribute__((alias(...))).])
-  fi])
-
 dnl Check how size_t is mangled.
 AC_DEFUN([LIBITM_CHECK_SIZE_T_MANGLING], [
   AC_CACHE_CHECK([how size_t is mangled],
@@ -106,140 +64,8 @@  AC_DEFUN([AC_PROG_LD])
 ])
 
 dnl ----------------------------------------------------------------------
-dnl This whole bit snagged from libstdc++-v3.
-
-dnl
-dnl LIBITM_ENABLE
-dnl    (FEATURE, DEFAULT, HELP-ARG, HELP-STRING)
-dnl    (FEATURE, DEFAULT, HELP-ARG, HELP-STRING, permit a|b|c)
-dnl    (FEATURE, DEFAULT, HELP-ARG, HELP-STRING, SHELL-CODE-HANDLER)
-dnl
-dnl See docs/html/17_intro/configury.html#enable for documentation.
-dnl
-m4_define([LIBITM_ENABLE],[dnl
-m4_define([_g_switch],[--enable-$1])dnl
-m4_define([_g_help],[AC_HELP_STRING(_g_switch$3,[$4 @<:@default=$2@:>@])])dnl
- AC_ARG_ENABLE($1,_g_help,
-  m4_bmatch([$5],
-   [^permit ],
-     [[
-      case "$enableval" in
-       m4_bpatsubst([$5],[permit ])) ;;
-       *) AC_MSG_ERROR(Unknown argument to enable/disable $1) ;;
-          dnl Idea for future:  generate a URL pointing to
-          dnl "onlinedocs/configopts.html#whatever"
-      esac
-     ]],
-   [^$],
-     [[
-      case "$enableval" in
-       yes|no) ;;
-       *) AC_MSG_ERROR(Argument to enable/disable $1 must be yes or no) ;;
-      esac
-     ]],
-   [[$5]]),
-  [enable_]m4_bpatsubst([$1],-,_)[=][$2])
-m4_undefine([_g_switch])dnl
-m4_undefine([_g_help])dnl
-])
-
-
-dnl
-dnl If GNU ld is in use, check to see if tricky linker opts can be used.  If
-dnl the native linker is in use, all variables will be defined to something
-dnl safe (like an empty string).
-dnl
-dnl Defines:
-dnl  SECTION_LDFLAGS='-Wl,--gc-sections' if possible
-dnl  OPT_LDFLAGS='-Wl,-O1' if possible
-dnl  LD (as a side effect of testing)
-dnl Sets:
-dnl  with_gnu_ld
-dnl  libitm_gnu_ld_version (possibly)
-dnl
-dnl The last will be a single integer, e.g., version 1.23.45.0.67.89 will
-dnl set libitm_gnu_ld_version to 12345.  Zeros cause problems.
-dnl
-AC_DEFUN([LIBITM_CHECK_LINKER_FEATURES], [
-  # If we're not using GNU ld, then there's no point in even trying these
-  # tests.  Check for that first.  We should have already tested for gld
-  # by now (in libtool), but require it now just to be safe...
-  test -z "$SECTION_LDFLAGS" && SECTION_LDFLAGS=''
-  test -z "$OPT_LDFLAGS" && OPT_LDFLAGS=''
-  AC_REQUIRE([AC_PROG_LD])
-  AC_REQUIRE([AC_PROG_AWK])
-
-  # The name set by libtool depends on the version of libtool.  Shame on us
-  # for depending on an impl detail, but c'est la vie.  Older versions used
-  # ac_cv_prog_gnu_ld, but now it's lt_cv_prog_gnu_ld, and is copied back on
-  # top of with_gnu_ld (which is also set by --with-gnu-ld, so that actually
-  # makes sense).  We'll test with_gnu_ld everywhere else, so if that isn't
-  # set (hence we're using an older libtool), then set it.
-  if test x${with_gnu_ld+set} != xset; then
-    if test x${ac_cv_prog_gnu_ld+set} != xset; then
-      # We got through "ac_require(ac_prog_ld)" and still not set?  Huh?
-      with_gnu_ld=no
-    else
-      with_gnu_ld=$ac_cv_prog_gnu_ld
-    fi
-  fi
-
-  # Start by getting the version number.  I think the libtool test already
-  # does some of this, but throws away the result.
-  changequote(,)
-  ldver=`$LD --version 2>/dev/null | head -1 | \
-         sed -e 's/GNU ld \(version \)\{0,1\}\(([^)]*) \)\{0,1\}\([0-9.][0-9.]*\).*/\3/'`
-  changequote([,])
-  libitm_gnu_ld_version=`echo $ldver | \
-         $AWK -F. '{ if (NF<3) [$]3=0; print ([$]1*100+[$]2)*100+[$]3 }'`
-
-  # Set --gc-sections.
-  if test "$with_gnu_ld" = "notbroken"; then
-    # GNU ld it is!  Joy and bunny rabbits!
-
-    # All these tests are for C++; save the language and the compiler flags.
-    # Need to do this so that g++ won't try to link in libstdc++
-    ac_test_CFLAGS="${CFLAGS+set}"
-    ac_save_CFLAGS="$CFLAGS"
-    CFLAGS='-x c++  -Wl,--gc-sections'
-
-    # Check for -Wl,--gc-sections
-    # XXX This test is broken at the moment, as symbols required for linking
-    # are now in libsupc++ (not built yet).  In addition, this test has
-    # cored on solaris in the past.  In addition, --gc-sections doesn't
-    # really work at the moment (keeps on discarding used sections, first
-    # .eh_frame and now some of the glibc sections for iconv).
-    # Bzzzzt.  Thanks for playing, maybe next time.
-    AC_MSG_CHECKING([for ld that supports -Wl,--gc-sections])
-    AC_TRY_RUN([
-     int main(void)
-     {
-       try { throw 1; }
-       catch (...) { };
-       return 0;
-     }
-    ], [ac_sectionLDflags=yes],[ac_sectionLDflags=no], [ac_sectionLDflags=yes])
-    if test "$ac_test_CFLAGS" = set; then
-      CFLAGS="$ac_save_CFLAGS"
-    else
-      # this is the suspicious part
-      CFLAGS=''
-    fi
-    if test "$ac_sectionLDflags" = "yes"; then
-      SECTION_LDFLAGS="-Wl,--gc-sections $SECTION_LDFLAGS"
-    fi
-    AC_MSG_RESULT($ac_sectionLDflags)
-  fi
-
-  # Set linker optimization flags.
-  if test x"$with_gnu_ld" = x"yes"; then
-    OPT_LDFLAGS="-Wl,-O1 $OPT_LDFLAGS"
-  fi
-
-  AC_SUBST(SECTION_LDFLAGS)
-  AC_SUBST(OPT_LDFLAGS)
-])
-
+dnl This whole bit is based on libstdc++-v3 but has been changed.
+dnl ??? Generalize at some point?
 
 dnl
 dnl Add version tags to symbols in shared library (or not), additionally
@@ -256,13 +82,13 @@  dnl       'no' disables versioning.
 dnl
 AC_DEFUN([LIBITM_ENABLE_SYMVERS], [
 
-LIBITM_ENABLE(symvers,yes,[=STYLE],
+GCC_ENABLE(symvers,yes,[=STYLE],
   [enables symbol versioning of the shared library],
   [permit yes|no|gnu])
 
 # If we never went through the LIBITM_CHECK_LINKER_FEATURES macro, then we
 # don't know enough about $LD to do tricks...
-AC_REQUIRE([LIBITM_CHECK_LINKER_FEATURES])
+AC_REQUIRE([GCC_CHECK_LINKER_FEATURES])
 # FIXME  The following test is too strict, in theory.
 if test $enable_shared = no ||
         test "x$LD" = x ||
@@ -308,7 +134,7 @@  if test $enable_symvers = yes; then
   if test $with_gnu_ld = yes &&
      test $libitm_shared_libgcc = yes;
   then
-    if test $libitm_gnu_ld_version -ge $libitm_min_gnu_ld_version ; then
+    if test $gcc_gnu_ld_version -ge $libitm_min_gnu_ld_version ; then
       enable_symvers=gnu
     else
       # The right tools, the right setup, but too old.  Fallbacks?
@@ -316,7 +142,7 @@  if test $enable_symvers = yes; then
       AC_MSG_WARN(=== full symbol versioning support in this release of GCC.)
       AC_MSG_WARN(=== You would need to upgrade your binutils to version)
       AC_MSG_WARN(=== $libitm_min_gnu_ld_version or later and rebuild GCC.)
-      if test $libitm_gnu_ld_version -ge 21200 ; then
+      if test $gcc_gnu_ld_version -ge 21200 ; then
         # Globbing fix is present, proper block support is not.
         dnl AC_MSG_WARN([=== Dude, you are soooo close.  Maybe we can fake it.])
         dnl enable_symvers=???
diff --git a/libitm/aclocal.m4 b/libitm/aclocal.m4
index 6dcccdf..438b165 100644
--- a/libitm/aclocal.m4
+++ b/libitm/aclocal.m4
@@ -1000,6 +1000,7 @@  m4_include([../config/multi.m4])
 m4_include([../config/override.m4])
 m4_include([../config/stdint.m4])
 m4_include([../config/tls.m4])
+m4_include([../config/exportcontrols.m4])
 m4_include([../ltoptions.m4])
 m4_include([../ltsugar.m4])
 m4_include([../ltversion.m4])
diff --git a/libitm/configure b/libitm/configure
index 08d2993..efb42b7 100755
--- a/libitm/configure
+++ b/libitm/configure
@@ -16448,7 +16448,7 @@  $as_echo "#define HAVE_TLS 1" >>confdefs.h
 
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether the target supports hidden visibility" >&5
 $as_echo_n "checking whether the target supports hidden visibility... " >&6; }
-if test "${libitm_cv_have_attribute_visibility+set}" = set; then :
+if test "${gcc_cv_have_attribute_visibility+set}" = set; then :
   $as_echo_n "(cached) " >&6
 else
 
@@ -16466,16 +16466,16 @@  main ()
 }
 _ACEOF
 if ac_fn_c_try_compile "$LINENO"; then :
-  libitm_cv_have_attribute_visibility=yes
+  gcc_cv_have_attribute_visibility=yes
 else
-  libitm_cv_have_attribute_visibility=no
+  gcc_cv_have_attribute_visibility=no
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
   CFLAGS="$save_CFLAGS"
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libitm_cv_have_attribute_visibility" >&5
-$as_echo "$libitm_cv_have_attribute_visibility" >&6; }
-  if test $libitm_cv_have_attribute_visibility = yes; then
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_have_attribute_visibility" >&5
+$as_echo "$gcc_cv_have_attribute_visibility" >&6; }
+  if test $gcc_cv_have_attribute_visibility = yes; then
 
 $as_echo "#define HAVE_ATTRIBUTE_VISIBILITY 1" >>confdefs.h
 
@@ -16483,7 +16483,7 @@  $as_echo "#define HAVE_ATTRIBUTE_VISIBILITY 1" >>confdefs.h
 
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether the target supports dllexport" >&5
 $as_echo_n "checking whether the target supports dllexport... " >&6; }
-if test "${libitm_cv_have_attribute_dllexport+set}" = set; then :
+if test "${gcc_cv_have_attribute_dllexport+set}" = set; then :
   $as_echo_n "(cached) " >&6
 else
 
@@ -16501,16 +16501,16 @@  main ()
 }
 _ACEOF
 if ac_fn_c_try_compile "$LINENO"; then :
-  libitm_cv_have_attribute_dllexport=yes
+  gcc_cv_have_attribute_dllexport=yes
 else
-  libitm_cv_have_attribute_dllexport=no
+  gcc_cv_have_attribute_dllexport=no
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
   CFLAGS="$save_CFLAGS"
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libitm_cv_have_attribute_dllexport" >&5
-$as_echo "$libitm_cv_have_attribute_dllexport" >&6; }
-  if test $libitm_cv_have_attribute_dllexport = yes; then
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_have_attribute_dllexport" >&5
+$as_echo "$gcc_cv_have_attribute_dllexport" >&6; }
+  if test $gcc_cv_have_attribute_dllexport = yes; then
 
 $as_echo "#define HAVE_ATTRIBUTE_DLLEXPORT 1" >>confdefs.h
 
@@ -16518,7 +16518,7 @@  $as_echo "#define HAVE_ATTRIBUTE_DLLEXPORT 1" >>confdefs.h
 
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether the target supports symbol aliases" >&5
 $as_echo_n "checking whether the target supports symbol aliases... " >&6; }
-if test "${libitm_cv_have_attribute_alias+set}" = set; then :
+if test "${gcc_cv_have_attribute_alias+set}" = set; then :
   $as_echo_n "(cached) " >&6
 else
 
@@ -16536,16 +16536,16 @@  bar();
 }
 _ACEOF
 if ac_fn_c_try_link "$LINENO"; then :
-  libitm_cv_have_attribute_alias=yes
+  gcc_cv_have_attribute_alias=yes
 else
-  libitm_cv_have_attribute_alias=no
+  gcc_cv_have_attribute_alias=no
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libitm_cv_have_attribute_alias" >&5
-$as_echo "$libitm_cv_have_attribute_alias" >&6; }
-  if test $libitm_cv_have_attribute_alias = yes; then
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_have_attribute_alias" >&5
+$as_echo "$gcc_cv_have_attribute_alias" >&6; }
+  if test $gcc_cv_have_attribute_alias = yes; then
 
 $as_echo "#define HAVE_ATTRIBUTE_ALIAS 1" >>confdefs.h
 
@@ -16686,54 +16686,84 @@  with_gnu_ld=$lt_cv_prog_gnu_ld
 
   # Start by getting the version number.  I think the libtool test already
   # does some of this, but throws away the result.
+  gcc_ld_is_gold=no
+  if test x"$with_gnu_ld" = x"yes"; then
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for ld version" >&5
+$as_echo_n "checking for ld version... " >&6; }
 
-  ldver=`$LD --version 2>/dev/null | head -1 | \
-         sed -e 's/GNU ld \(version \)\{0,1\}\(([^)]*) \)\{0,1\}\([0-9.][0-9.]*\).*/\3/'`
+    if $LD --version 2>/dev/null | grep 'GNU gold' >/dev/null 2>&1; then
+      gcc_ld_is_gold=yes
+    fi
+    ldver=`$LD --version 2>/dev/null |
+	   sed -e 's/GNU gold /GNU ld /;s/GNU ld version /GNU ld /;s/GNU ld ([^)]*) /GNU ld /;s/GNU ld \([0-9.][0-9.]*\).*/\1/; q'`
 
-  libitm_gnu_ld_version=`echo $ldver | \
-         $AWK -F. '{ if (NF<3) $3=0; print ($1*100+$2)*100+$3 }'`
+    gcc_gnu_ld_version=`echo $ldver | \
+	   $AWK -F. '{ if (NF<3) $3=0; print ($1*100+$2)*100+$3 }'`
+    { $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_gnu_ld_version" >&5
+$as_echo "$gcc_gnu_ld_version" >&6; }
+  fi
 
   # Set --gc-sections.
-  if test "$with_gnu_ld" = "notbroken"; then
-    # GNU ld it is!  Joy and bunny rabbits!
+  gcc_have_gc_sections=no
+  if test "$gcc_ld_is_gold" = "yes"; then
+    if $LD --help 2>/dev/null | grep gc-sections >/dev/null 2>&1; then
+      gcc_have_gc_sections=yes
+    fi
+  else
+    gcc_gcsections_min_ld=21602
+    if test x"$with_gnu_ld" = x"yes" &&
+	test $gcc_gnu_ld_version -gt $gcc_gcsections_min_ld ; then
+      gcc_have_gc_sections=yes
+    fi
+  fi
+  if test "$gcc_have_gc_sections" = "yes"; then
+    # Sufficiently young GNU ld it is!  Joy and bunny rabbits!
+    # NB: This flag only works reliably after 2.16.1. Configure tests
+    # for this are difficult, so hard wire a value that should work.
 
-    # All these tests are for C++; save the language and the compiler flags.
-    # Need to do this so that g++ won't try to link in libstdc++
     ac_test_CFLAGS="${CFLAGS+set}"
     ac_save_CFLAGS="$CFLAGS"
-    CFLAGS='-x c++  -Wl,--gc-sections'
+    CFLAGS='-Wl,--gc-sections'
 
     # Check for -Wl,--gc-sections
-    # XXX This test is broken at the moment, as symbols required for linking
-    # are now in libsupc++ (not built yet).  In addition, this test has
-    # cored on solaris in the past.  In addition, --gc-sections doesn't
-    # really work at the moment (keeps on discarding used sections, first
-    # .eh_frame and now some of the glibc sections for iconv).
-    # Bzzzzt.  Thanks for playing, maybe next time.
     { $as_echo "$as_me:${as_lineno-$LINENO}: checking for ld that supports -Wl,--gc-sections" >&5
 $as_echo_n "checking for ld that supports -Wl,--gc-sections... " >&6; }
-    if test "$cross_compiling" = yes; then :
-  ac_sectionLDflags=yes
-else
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+    cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
+ int one(void) { return 1; }
+     int two(void) { return 2; }
 
-     int main(void)
-     {
-       try { throw 1; }
-       catch (...) { };
-       return 0;
-     }
-
+int
+main ()
+{
+ two();
+  ;
+  return 0;
+}
 _ACEOF
-if ac_fn_c_try_run "$LINENO"; then :
-  ac_sectionLDflags=yes
+if ac_fn_c_try_link "$LINENO"; then :
+  ac_gcsections=yes
 else
-  ac_sectionLDflags=no
-fi
-rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext \
-  conftest.$ac_objext conftest.beam conftest.$ac_ext
+  ac_gcsections=no
 fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+    if test "$ac_gcsections" = "yes"; then
+      rm -f conftest.c
+      touch conftest.c
+      if $CC -c conftest.c; then
+	if $LD --gc-sections -o conftest conftest.o 2>&1 | \
+	   grep "Warning: gc-sections option ignored" > /dev/null; then
+	  ac_gcsections=no
+	fi
+      fi
+      rm -f conftest.c conftest.o conftest
+    fi
+    if test "$ac_gcsections" = "yes"; then
+      SECTION_LDFLAGS="-Wl,--gc-sections $SECTION_LDFLAGS"
+    fi
+    { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_gcsections" >&5
+$as_echo "$ac_gcsections" >&6; }
 
     if test "$ac_test_CFLAGS" = set; then
       CFLAGS="$ac_save_CFLAGS"
@@ -16741,11 +16771,21 @@  fi
       # this is the suspicious part
       CFLAGS=''
     fi
-    if test "$ac_sectionLDflags" = "yes"; then
-      SECTION_LDFLAGS="-Wl,--gc-sections $SECTION_LDFLAGS"
+  fi
+
+  # Set -z,relro.
+  # Note this is only for shared objects.
+  ac_ld_relro=no
+  if test x"$with_gnu_ld" = x"yes"; then
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for ld that supports -Wl,-z,relro" >&5
+$as_echo_n "checking for ld that supports -Wl,-z,relro... " >&6; }
+    cxx_z_relo=`$LD -v --help 2>/dev/null | grep "z relro"`
+    if test -n "$cxx_z_relo"; then
+      OPT_LDFLAGS="-Wl,-z,relro"
+      ac_ld_relro=yes
     fi
-    { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_sectionLDflags" >&5
-$as_echo "$ac_sectionLDflags" >&6; }
+    { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_ld_relro" >&5
+$as_echo "$ac_ld_relro" >&6; }
   fi
 
   # Set linker optimization flags.
@@ -16852,7 +16892,7 @@  if test $enable_symvers = yes; then
   if test $with_gnu_ld = yes &&
      test $libitm_shared_libgcc = yes;
   then
-    if test $libitm_gnu_ld_version -ge $libitm_min_gnu_ld_version ; then
+    if test $gcc_gnu_ld_version -ge $libitm_min_gnu_ld_version ; then
       enable_symvers=gnu
     else
       # The right tools, the right setup, but too old.  Fallbacks?
@@ -16864,7 +16904,7 @@  $as_echo "$as_me: WARNING: === full symbol versioning support in this release of
 $as_echo "$as_me: WARNING: === You would need to upgrade your binutils to version" >&2;}
       { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: === $libitm_min_gnu_ld_version or later and rebuild GCC." >&5
 $as_echo "$as_me: WARNING: === $libitm_min_gnu_ld_version or later and rebuild GCC." >&2;}
-      if test $libitm_gnu_ld_version -ge 21200 ; then
+      if test $gcc_gnu_ld_version -ge 21200 ; then
         # Globbing fix is present, proper block support is not.
                         { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: === Symbol versioning will be disabled." >&5
 $as_echo "$as_me: WARNING: === Symbol versioning will be disabled." >&2;}
diff --git a/libitm/configure.ac b/libitm/configure.ac
index 7f35b15..affc17b 100644
--- a/libitm/configure.ac
+++ b/libitm/configure.ac
@@ -24,7 +24,7 @@  AC_CONFIG_HEADER(config.h)
 # -------
 
 AC_MSG_CHECKING([for --enable-version-specific-runtime-libs])
-LIBITM_ENABLE(version-specific-runtime-libs, no, ,
+GCC_ENABLE(version-specific-runtime-libs, no, ,
    [Specify that runtime libraries should be installed in a compiler-specific directory],
    permit yes|no)
 AC_MSG_RESULT($enable_version_specific_runtime_libs)
@@ -35,7 +35,7 @@  AC_MSG_RESULT($enable_version_specific_runtime_libs)
 # sources.  Therefore we have --enable-generated-files-in-srcdir to do 
 # just that.
 AC_MSG_CHECKING([for --enable-generated-files-in-srcdir])
-LIBITM_ENABLE(generated-files-in-srcdir, no, ,
+GCC_ENABLE(generated-files-in-srcdir, no, ,
    [put copies of generated files in source dir intended for creating source 
     tarballs for users without texinfo bison or flex.],
    permit yes|no)
@@ -209,9 +209,9 @@  GCC_LINUX_FUTEX(:)
 GCC_CHECK_TLS
 
 # See what sort of export controls are availible.
-LIBITM_CHECK_ATTRIBUTE_VISIBILITY
-LIBITM_CHECK_ATTRIBUTE_DLLEXPORT
-LIBITM_CHECK_ATTRIBUTE_ALIAS
+GCC_CHECK_ATTRIBUTE_VISIBILITY
+GCC_CHECK_ATTRIBUTE_DLLEXPORT
+GCC_CHECK_ATTRIBUTE_ALIAS
 LIBITM_ENABLE_SYMVERS
 
 if test $enable_symvers = gnu; then