Index: gcc/doc/invoke.texi
===================================================================
RCS file: /cvsroot/gcc/gcc/gcc/doc/invoke.texi,v
retrieving revision 1.661
diff -p -u -r1.661 invoke.texi
--- gcc/doc/invoke.texi	30 Jul 2005 02:12:12 -0000	1.661
+++ gcc/doc/invoke.texi	10 Sep 2005 21:55:21 -0000
@@ -9155,6 +9155,12 @@ instruction set.
 @xref{X86 Built-in Functions}, for details of the functions enabled
 and disabled by these switches.
 
+These options also enable gcc to use these extended instructions in
+generated code.  Applications which perform runtime CPU detection and
+also use the built-in functions must compile separate files for each
+support architecture with the appropriate flags, taking care to
+isolate the CPU detection code in a file compiled without these options.
+
 To have SSE/SSE2 instructions generated automatically from floating-point
 code, see @option{-mfpmath=sse}.