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: Weiwen Liu <weiwen.liu@yale.edu>, law@cygnus.com, egcs@cygnus.com
Subject: Re: Patch for jump optimization 
Date: Tue, 03 Feb 1998 21:35:00 -0000
Message-id: <27348.886569613@hurl.cygnus.com>
References: <199802030846.VAA11549@ongaonga.chch.cri.nz>
X-SW-Source: 1998-02/msg00145.html

  In message < 199802030846.VAA11549@ongaonga.chch.cri.nz >you write:
  > Weiwen Liu writes:
  >  > On alpha-dec-osf4.0, the current egcs in the cvs tree fails to build
  >  > libgcc2.a, because the jump optimization (modified_in_p) fails to
  >  > process the following insn.
  >  > 
  >  > (jump_insn 52 51 54 (set (pc)
  >  >         (if_then_else (eq (reg:DI 102)
  >  >                 (const_int 0))
  >  >             (label_ref 56)
  >  >             (pc))) 178 {umindi3+2} (nil)
  >  >     (nil))
  > 
  > The problem is that Jeff got a little carried away installing an old
  > patch of mine that disabled some jump optimisations if the inserted
  > insn clobbered something required by the following insn.
  > I fixed the problem for GCC 2.8.0 by looking for safer places that
  > the insn could be inserted, and then only rejecting the optimisation
  > if it couldn't find a suitable place.
  > 
I must have missed that -- I didn't remember seeing any related changes go
into gcc-2.8.  I must have missed them.

Just so we're both clear, the stuff to handle constants in memory should be
OK right?

  > The calls to modified_in_p aren't required.
I'll install your updated patch :-)

Thanks for clarifying things!

jeff