Path: utzoo!telly!ddsw1!lll-winken!killer!mit-eddie!fenchurch.mit.edu!jbs
From: jbs@fenchurch.MIT.EDU (Jeff Siegal)
Newsgroups: gnu.gcc.bug
Subject: Re: GCC 1.30 complaints
Message-ID: <10343@eddie.MIT.EDU>
Date: 26 Oct 88 22:00:41 GMT
References: <8810220131.AA00312@ucsci.ucsc.edu> <1531@vaxnix.tandy.COM> <9773@bigtex.cactus.org> <1608@vaxnix.tandy.COM>
Sender: uucp@eddie.MIT.EDU
Reply-To: jbs@fenchurch.MIT.EDU (Jeff Siegal)
Distribution: gnu
Organization: MIT EE/CS Computer Facilities, Cambridge, MA
Lines: 23

In article <1608@vaxnix.tandy.COM> ron@vaxnix.UUCP (Ron Light) writes:
>In article <9773@bigtex.cactus.org> james@bigtex.cactus.org (James Van Artsdalen) writes:
>If I have a delay loop, for whatever reason, I would be very
>angry if the compiler decided, for itself, "Oh, this is stupid, we don't
>need this."

The compiler doesn't know it is a "delay loop."  It only knows that it
is an empty loop.  It might have resulted from code like:

	for (i=0; i<100; ++i) {
	    assert(a[i] != 0);
	}

when compiled with NDEBUG=1

>A compiler's job is [...]to take the source code I've
>given it and try to produce the most reasonable approximation of assembly
>or binary code.

Perhaps, but the job of an *optimizing*compiler* is to produce the
fastest/smallest code sequence it can, out of the set of possible code
sequences which perform the same function.

Jeff Siegal