* doc/md.texi (Standard Pattern Names): Document blockage pattern.

From-SVN: r121268

gcc/ChangeLog

+2007-01-28  David Edelsohn  <edelsohn@gnu.org>
+
+	* doc/md.texi (Standard Pattern Names): Document blockage pattern.
+
 2007-01-28  Zdenek Dvorak <dvorakz@suse.cz>
 
 	* tree-ssa-loop-unswitch.c: Include tree-inline.h.

gcc/doc/md.texi

@@ -4704,6 +4704,13 @@ respectively, a low or moderate degree of temporal locality.
 Targets that do not support write prefetches or locality hints can ignore
 the values of operands 1 and 2.
 
+@cindex @code{blockage} instruction pattern
+@item @samp{blockage}
+
+This pattern defines a pseudo insn that prevents the instruction
+scheduler from moving instructions across the boundary defined by the
+blockage insn.  Normally an UNSPEC_VOLATILE pattern.
+
 @cindex @code{memory_barrier} instruction pattern
 @item @samp{memory_barrier}