fix opt/6165

[Richard Henderson]

On Fri, Apr 05, 2002 at 12:07:08PM +0100, Richard Earnshaw wrote:
> IMO, this should be mentioned in rtl.texi, then other ports can know to 
> make use of it.

Done.


r~


        * doc/rtl.texi (Regs and Memory): Document (mem:BLK (scratch)).

Index: rtl.texi
===================================================================
RCS file: /cvs/gcc/gcc/gcc/doc/rtl.texi,v
retrieving revision 1.32
diff -c -p -d -r1.32 rtl.texi
*** rtl.texi	2002/03/23 01:10:56	1.32
--- rtl.texi	2002/04/06 01:13:01
*************** a unit of memory is accessed.  @var{alia
*** 1558,1563 ****
--- 1558,1567 ----
  reference.  In general two items are in different alias sets if they cannot
  reference the same memory address.
  
+ The construct @code{(mem:BLK (scratch))} is considered to alias all
+ other memories.  Thus it may be used as a memory barrier in epilogue
+ stack deallocation patterns.
+ 
  @findex addressof
  @item (addressof:@var{m} @var{reg})
  This RTX represents a request for the address of register @var{reg}.  Its mode