re PR libstdc++/5730 (complex<double>::norm() -- huge slowdown from egcs-2.91.66)

2003-03-21  Jerry Quinn  <jlquinn@optonline.net>

	PR libstdc++/5730
	* include/bits/c++config (_GLIBCPP_FAST_MATH): Define.
        * include/std/std_complex.h (norm):  Use faster,
        less accurate computation for builtin float types under --fast-math.

From-SVN: r64701

libstdc++-v3/ChangeLog

+2003-03-21  Jerry Quinn  <jlquinn@optonline.net>
+
+	PR libstdc++/5730
+	* include/bits/c++config (_GLIBCPP_FAST_MATH): Define.
+        * include/std/std_complex.h (norm):  Use faster,
+        less accurate computation for builtin float types under --fast-math.
+
 2003-03-21  Magnus Fromreide  <gnats@magfr.user.lysator.liu.se>
 
 	* testsuite/testsuite_hooks.h: Fix warning nits.

libstdc++-v3/include/bits/c++config

@@ -87,6 +87,13 @@
 #error __USE_MALLOC should never be defined.  Read the release notes.
 #endif
 
+// Create a boolean flag to be used to determine if --fast-math is set.
+#ifdef __FAST_MATH__
+#define _GLIBCPP_FAST_MATH 1
+#else
+#define _GLIBCPP_FAST_MATH 0
+#endif
+
 // The remainder of the prewritten config is mostly automatic; all the
 // user hooks are listed above.
 

libstdc++-v3/include/std/std_complex.h

@@ -456,7 +456,7 @@ namespace std
     inline _Tp
     norm(const complex<_Tp>& __z)
     {
-      return _Norm_helper<__is_floating<_Tp>::_M_type>::_S_do_it(__z);
+      return _Norm_helper<__is_floating<_Tp>::_M_type && !_GLIBCPP_FAST_MATH>::_S_do_it(__z);
     }
 
   template<typename _Tp>