Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!uw-beaver!rice!sun-spots-request
From: unido!ecrcvax!ecrcvax!micha@uunet.uu.net (Micha Meier)
Newsgroups: comp.sys.sun
Subject: cc -O2 on SUNOS 4.0
Keywords: Software
Message-ID: <710@ecrcvax.UUCP>
Date: 26 Apr 89 01:44:26 GMT
Sender: usenet@rice.edu
Organization: ECRC, Munich 81, West Germany
Lines: 14
Approved: Sun-Spots@rice.edu
Original-Date: 5 Apr 89 14:19:41 GMT
X-Sun-Spots-Digest: Volume 7, Issue 249, message 18 of 20

We have a problem with the C optimizer in 4.0: if we use anything higher
than cc -O1, the resulting code uses no hardware registers and so it runs
about half the speed of the non-optimized program (!). I first thought
that the optimizer does not work at all but then we found out that for
some programs it works just fine. Does anybody know what criteria
/usr/lib/iropt uses to allocate program variables to hardware registers?
I don't know whether this is a bug or a feature but in any case we need a
solution.

The problem is crucial since the concerned function is the core of our
system and when it runs slowly, so does the whole system.  Please answer
by email.

--Micha					{pyramid,unido}!ecrcvax!micha