From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeffrey A Law <law@cygnus.com>
To: "Michael P. Hayes" <michaelh@ongaonga.chch.cri.nz>
Cc: gcc2@cygnus.com, egcs@cygnus.com
Subject: Re: Jump optimisation patches 
Date: Mon, 02 Feb 1998 10:32:00 -0000
Message-id: <29444.886441074@hurl.cygnus.com>
References: <199802020948.WAA09821@ongaonga.chch.cri.nz>
X-SW-Source: 1998-02/msg00077.html

  In message < 199802020948.WAA09821@ongaonga.chch.cri.nz >you write:
  > Jeffrey A Law writes:
  >  > 
  >  >   In message <199711050316.QAA19266@ongaonga.chch.cri.nz>you write:
  >  >   > 
  >  >   > 1997-11-05  Michael P. Hayes  <michaelh@ongaonga.chch.cri.nz>
  >  >   > 
  >  >   > 	(jump.c): Allow conditional loading of floating point constants
  >  >   > 	and constants from memory.  Reinstalled modified_in_p tests.
  >  > I've installed these patches into egcs.
  > 
  > Whoa.  I completely rewrote these patches for GCC 2.8.0 to test for
  > the proper place that the extra move insn should be inserted.  I've
  > been using the patch for the conditional loading of floating point
  > constants without any problems but Kenner didn't include it since
  > he had some reservations about its utility.
jump.c in egcs is very close to jump.c in gcc-2.8; we haven't made
any significant changes to it yet.  As a result it was quite easy
to make your patch work for egcs :-)

  > The conditional loading of memory operands could also be more general.
  > 
  >  > Don't you also need one in the conditional for this optimization:
  >  > 
  >  >          /* If branches are expensive, convert
  >  >                 if (foo) bar++;    to    bar += (foo != 0);
  >  >              and similarly for "bar--;"
  > 
  > Ah, need one what?  
A call to modified_in_p.

jeff