mark_rts.c (GC_approx_sp): Use __builtin_frame_address when compiling with GCC…

mark_rts.c (GC_approx_sp): Use __builtin_frame_address when compiling with GCC rather than taking the...

	* mark_rts.c (GC_approx_sp): Use __builtin_frame_address when
	compiling with GCC rather than taking the address of a local
	variable.

From-SVN: r154771

boehm-gc/ChangeLog

 2009-11-30  Ben Elliston  <bje@au.ibm.com>
 
+	* mark_rts.c (GC_approx_sp): Use __builtin_frame_address when
+	compiling with GCC rather than taking the address of a local
+	variable.
+
+2009-11-30  Ben Elliston  <bje@au.ibm.com>
+
 	* os_dep.c: Use the POSIX signal API in preference to the BSD API.
 	Generate a compilation error if neither the POSIX nor BSD APIs can
 	be detected.

boehm-gc/mark_rts.c

@@ -376,7 +376,13 @@ ptr_t GC_approx_sp()
 #   ifdef _MSC_VER
 #     pragma warning(disable:4172)
 #   endif
-    return((ptr_t)(&dummy));
+#ifdef __GNUC__
+    /* Eliminate a warning from GCC about taking the address of a
+       local variable.  */
+    return __builtin_frame_address (0);
+#else
+    return ((ptr_t)(&dummy));
+#endif /* __GNUC__ */
 #   ifdef _MSC_VER
 #     pragma warning(default:4172)
 #   endif