From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeffrey A Law <law@cygnus.com>
To: Richard Henderson <rth@cygnus.com>
Cc: John Wehle <john@feith.com>, egcs@cygnus.com, egcs-patches@cygnus.com
Subject: Re: Possible CSE quirk involving SUBREG on the i386 
Date: Wed, 01 Jul 1998 22:54:00 -0000
Message-id: <23985.899358631@hurl.cygnus.com>
References: <19980701033305.A23054@dot.cygnus.com>
X-SW-Source: 1998-07/msg00068.html

  In message < 19980701033305.A23054@dot.cygnus.com >you write:
  > Ho hum.  The explanation is simple here -- MODES_TIEABLE_P.
  > 
  > I believe that we can do slightly better for this; while only
  > the first four int regs can hold QImode values, all of them 
  > can hold HImode values.
  > 
  > This happens to cure this exact problem, but the same problem
  > will occur with unsigned char, and I don't see that we can do
  > anything about it.
  > 
  > 
  > r~
  > 
  > 
  > 	* i386.h (HARD_REGNO_MODE_OK): Kill spurrious test.
  > 	(MODES_TIEABLE_P): Tie SImode and HImode.
Patch seems reasonble.  I think you should install it.

I think we're still trying to decide if we can relax MODES_TIEABLE_P's
need to be symmetric. :-)  That might help the char problem in some
cases.

jeff