md.texi (movMM): Clarify semantics of storing into a non-paradoxical SUBREG.

        * doc/md.texi (movMM): Clarify semantics of storing into a
        non-paradoxical SUBREG.

From-SVN: r46494

gcc/ChangeLog

+Thu Oct 25 12:21:58 2001  Jeffrey A Law  (law@cygnus.com)
+
+	* doc/md.texi (movMM): Clarify semantics of storing into a 
+	non-paradoxical SUBREG.
+
 2001-10-25  Zack Weinberg  <zack@codesourcery.com>
 
 	* langhooks.c (lang_hook_default_clear_binding_stack): New.

gcc/doc/md.texi

@@ -2024,7 +2024,9 @@ This instruction pattern moves data with that machine mode from operand
 If operand 0 is a @code{subreg} with mode @var{m} of a register whose
 own mode is wider than @var{m}, the effect of this instruction is
 to store the specified value in the part of the register that corresponds
-to mode @var{m}.  The effect on the rest of the register is undefined.
+to mode @var{m}.  Bits outside of @var{m}, but which are within the
+same target word as the @code{subreg} are undefined.  Bits which are
+outside the target word are left unchanged.
 
 This class of patterns is special in several ways.  First of all, each
 of these names up to and including full word size @emph{must} be defined,