From: Eric Backus <ericb AT lsid DOT hp DOT com>
Subject: Re: How safe is -O2?
To: greve AT rs1 DOT thch DOT uni-bonn DOT de
Date: Mon, 18 May 92 10:48:44 PDT
Cc: djgpp AT sun DOT soe DOT clarkson DOT edu
Mailer: Elm [revision: 66.25]
Status: O

> - When trying to recompile libgcc, cc1plus stumbled over fix.cc in
>   $(gcc)/libsrc/gcc/gpp when started with -O2. It just interrupted
>   it's work half way, return code 1. No error msg, nothing. fix.cc
>   can be compiled with -O, though. What happened? (There was enough
>   paging space, HD space for the tmp-files etc. Nothing of the trivial
>   kind...)
>
>    greve AT rs1 DOT thch DOT uni-bonn DOT de
>    unt145 AT dbnrhrz1

I use "-O2" all the time.  I also use "-finline-functions" and
"-fomit-frame-pointer".  I've even tried "-funroll-loops".  Works fine
for me on programs of low to medium complexity.  I haven't tried on
anything major.  I haven't compared to see if "-O2" really improves
anything.  (Does the 386 even have a frame pointer?)
--
				Eric Backus
				ericb%hplsla AT hplabs DOT hp DOT com
				(206) 335-2495