From 3aa5c524e6202e91290c7be9b4d2b5897232bec4 Mon Sep 17 00:00:00 2001
From: ericwa <ericwa@72102866-910b-0410-8b05-ffd578937521>
Date: Sat, 28 May 2011 18:05:14 +0000
Subject: [PATCH] tweak and re-enable atomic ops detection

git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@33179 72102866-910b-0410-8b05-ffd578937521
---
 Source/NSObject.m |  8 ----
 configure.ac      | 94 +++++++++++++++++++++++++----------------------
 2 files changed, 51 insertions(+), 51 deletions(-)

diff --git a/Source/NSObject.m b/Source/NSObject.m
index 265175567..85d350419 100644
--- a/Source/NSObject.m
+++ b/Source/NSObject.m
@@ -194,14 +194,6 @@ static void GSLogZombie(id o, SEL sel)
 #undef	GSATOMICREAD
 #endif
 
-/*
- * FIXME: Refrain from using atomic builtins until we know how to reliably check
- * whether they do work with GCC.
- */
-#ifdef USE_ATOMIC_BUILTINS
-#undef USE_ATOMIC_BUILTINS
-#endif
-
 
 #if	defined(__MINGW__)
 #ifndef _WIN64
diff --git a/configure.ac b/configure.ac
index 25f48ab1f..a2c4a9fff 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1013,7 +1013,7 @@ AC_USE_SYSTEM_EXTENSIONS
 
 AC_LANG_PUSH(C)
 AC_MSG_CHECKING([whether the compiler supports atomic operations]);
-  AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[typedef int atomic;]],
+  AC_LINK_IFELSE([AC_LANG_PROGRAM([[typedef int atomic;]],
     [[atomic x; atomic y; __sync_bool_compare_and_swap(&x, y, y + 1);]])],
   have_atomic=yes,
   have_atomic=no);
@@ -1023,51 +1023,59 @@ AC_MSG_CHECKING([whether the compiler supports atomic operations]);
       [Define if the compiler provides builtins for atomic operations])
   else
     AC_MSG_RESULT([no]);
-  fi
-if test "$CC" = "gcc"; then
-  saved_CFLAGS="$CFLAGS";
-  ATOMIC_CFLAGS="";
+    if test "$CC" = "gcc"; then
+       saved_CFLAGS="$CFLAGS";
+       ATOMIC_CFLAGS="";
   
-  # FIXME: Forcing -march=i568 for any i568 or later CPU is a stop gap measure
-  # to make the compiler emit native assembly for atomic operations on i586 or
-  # latter processors (GCC by defaults emits code compatible with the original
-  # i386 and requires library functions to emulate atomic operations). When
-  # gnustep-make takes care of this kind of target setting, the check can safely
-  # be removed.  
-  case "$target_cpu" in
-    i586*|i686*|i786*)
-      ATOMIC_CFLAGS="-march=i586";
-      CFLAGS="$saved_CFLAGS $ATOMIC_CFLAGS";
-      OBJCFLAGS="$OBJCFLAGS $ATOMIC_CFLAGS";
-  esac
-  AC_MSG_CHECKING([checking whether atomic operations require an external library]);
-    AC_LINK_IFELSE([AC_LANG_PROGRAM([[typedef int atomic;]],
-      [[atomic x; atomic y; __sync_bool_compare_and_swap(&x, y, y + 1);]])],
-    need_linkage=no,
-  need_linkage=yes);
+      # FIXME: Forcing -march=i568 for any i568 or later CPU is a stop gap measure
+      # to make the compiler emit native assembly for atomic operations on i586 or
+      # latter processors (GCC by defaults emits code compatible with the original
+      # i386 and requires library functions to emulate atomic operations). When
+      # gnustep-make takes care of this kind of target setting, the check can safely
+      # be removed.  
+      case "$target_cpu" in
+        i586*|i686*|i786*)
+          ATOMIC_CFLAGS="-march=i586"
+          CFLAGS="$saved_CFLAGS $ATOMIC_CFLAGS"
+          OBJCFLAGS="$OBJCFLAGS $ATOMIC_CFLAGS"
+          ;;
+        x86_64)
+          ATOMIC_CFLAGS="-march=x86-64"
+          CFLAGS="$saved_CFLAGS $ATOMIC_CFLAGS"
+          OBJCFLAGS="$OBJCFLAGS $ATOMIC_CFLAGS"
+          ;;
+      esac
+      AC_MSG_CHECKING([whether gcc supports atomic operations by setting -march]);
+        AC_LINK_IFELSE([AC_LANG_PROGRAM([[typedef int atomic;]],
+          [[atomic x; atomic y; __sync_bool_compare_and_swap(&x, y, y + 1);]])],
+        need_march=yes,
+      need_march=no);
 
-  if test "$need_linkage" = "no"; then
-    AC_MSG_RESULT([no]);
-  else
-    AC_MSG_RESULT([yes]);
-    saved_LDFLAGS="$LDFLAGS";
-    LDFLAGS="$saved_LDFLAGS -lgcc";
-    AC_MSG_CHECKING([checking for atomic operations from libgcc]);
-      AC_LINK_IFELSE([AC_LANG_PROGRAM([[typedef int atomic;]],
-        [[atomic x; atomic y; __sync_bool_compare_and_swap(&x, y, y + 1);]])],
-      atomic_in_libgcc=yes,
-    atomic_in_libgcc=no);
-    if test "$atomic_in_libgcc" = "yes"; then
-      AC_MSG_RESULT([yes]);
-      LIBS="$LIBS -lgcc";
-      AC_DEFINE(USE_ATOMIC_BUILTINS,1,
-        [Define if the compiler provides builtins for atomic operations])
-    else
-      LDFLAGS="$saved_LDFLAGS";
-      AC_MSG_RESULT([no]);
+      if test "$need_march" = "yes"; then
+        AC_MSG_RESULT([yes]);
+        AC_DEFINE(USE_ATOMIC_BUILTINS,1,
+          [Define if the compiler provides builtins for atomic operations])
+      else
+        AC_MSG_RESULT([no]);
+        saved_LDFLAGS="$LDFLAGS";
+        LDFLAGS="$saved_LDFLAGS -lgcc";
+        AC_MSG_CHECKING([whether gcc supports atomic operations by linikng to libgcc]);
+          AC_LINK_IFELSE([AC_LANG_PROGRAM([[typedef int atomic;]],
+            [[atomic x; atomic y; __sync_bool_compare_and_swap(&x, y, y + 1);]])],
+          atomic_in_libgcc=yes,
+        atomic_in_libgcc=no);
+        if test "$atomic_in_libgcc" = "yes"; then
+          AC_MSG_RESULT([yes]);
+          LIBS="$LIBS -lgcc";
+          AC_DEFINE(USE_ATOMIC_BUILTINS,1,
+            [Define if the compiler provides builtins for atomic operations])
+        else
+          LDFLAGS="$saved_LDFLAGS";
+          AC_MSG_RESULT([no]);
+        fi
+      fi     
     fi
-  fi     
-fi
+  fi
 AC_LANG_POP(C)