From 3ba82d605ce2a86abb9b2dd0ca3b4b660117417d Mon Sep 17 00:00:00 2001
From: bkoz <bkoz@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Fri, 14 Jul 2006 22:41:43 +0000
Subject: 2006-07-14  Benjamin Kosnik  <bkoz@redhat.com>

        * acinclude.m4 (GLIBCXX_ENABLE_ATOMIC_BUILTINS): New.
        * configure.ac: Use it.
        * configure: Regenerated.
        * config.h.in: Regenerated.
        * configure.host: Simplify.
        * include/bits/atomicity.h: Adjust macros.
        * config/cpu/generic/atomicity.h: Move...
        * config/cpu/generic/atomicity_mutex: New.
        * config/cpu/generic/atomicity_mutex/atomicity.h: ...here.
        * config/cpu/generic/atomic_builtins: Rename...
        * config/cpu/generic/atomicity_builtins: ...to this.
        * config/cpu/generic/atomicity_builtins/atomicity.h: Moved.
	* config/cpu/mips/atomicity.h: Comment MIPS II requirement.

	* scripts/testsuite_flags.in: Make --cxxflags reflect CXXFLAGS.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@115456 138bc75d-0d04-0410-961f-82ee72b054a4
---
 libstdc++-v3/acinclude.m4 | 63 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)

(limited to 'libstdc++-v3/acinclude.m4')

diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index 349566466ac..c160a1a3366 100644
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -1966,6 +1966,69 @@ AC_DEFUN([GLIBCXX_ENABLE_PCH], [
 ])
 
 
+dnl
+dnl Check for atomic builtins.
+dnl See:
+dnl http://gcc.gnu.org/onlinedocs/gcc/Atomic-Builtins.html#Atomic-Builtins
+dnl
+dnl This checks to see if the host supports the compiler-generated
+dnl builtins for atomic operations. Note, this is intended to be an
+dnl all-or-nothing switch, so all the atomic operations that are used
+dnl should be checked.
+dnl
+dnl Note:
+dnl libgomp and libgfortran do this with a link test, instead of an asm test.
+dnl see: CHECK_SYNC_FETCH_AND_ADD
+dnl
+dnl Defines:
+dnl  _GLIBCXX_ATOMIC_BUILTINS if the compiler on this target supports atomics.
+dnl
+AC_DEFUN([GLIBCXX_ENABLE_ATOMIC_BUILTINS], [
+  AC_MSG_CHECKING([for atomic builtins])
+  AC_LANG_SAVE
+  AC_LANG_CPLUSPLUS
+
+  # Fake what AC_TRY_COMPILE does.  XXX Look at redoing this new-style.
+    cat > conftest.$ac_ext << EOF
+[#]line __oline__ "configure"
+int main()
+{
+  // NB: _Atomic_word not necessarily int. 
+  typedef int atomic_type;
+  atomic_type c1;
+  atomic_type c2;
+  const atomic_type c3(0);
+  if (__sync_fetch_and_add(&c1, c2) == c3)
+    {
+      // Do something.
+    }
+   return 0;
+}
+EOF
+    old_CXXFLAGS="$CXXFLAGS"
+    CXXFLAGS="$CXXFLAGS -S"
+    if AC_TRY_EVAL(ac_compile); then
+      if grep __sync_fetch_and_add conftest.s >/dev/null 2>&1 ; then
+        enable_atomic_builtins=no
+      else
+      AC_DEFINE(_GLIBCXX_ATOMIC_BUILTINS, 1,
+        [Define if builtin atomic operations are supported on this host.])
+        enable_atomic_builtins=yes
+	atomicity_dir=cpu/generic/atomicity_builtins
+      fi
+    fi
+    CXXFLAGS="$old_CXXFLAGS"
+    rm -f conftest*
+
+   # Now, if still generic, set to mutex.
+  if test $atomicity_dir = "cpu/generic" ; then
+	atomicity_dir=cpu/generic/atomicity_mutex
+  fi
+ AC_LANG_RESTORE
+ AC_MSG_RESULT($enable_atomic_builtins)
+])
+
+
 dnl
 dnl Check for exception handling support.  If an explicit enable/disable
 dnl sjlj exceptions is given, we don't have to detect.  Otherwise the
-- 
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