Path: utzoo!mnetor!uunet!lll-winken!lll-tis!ames!oliveb!sun!gorodish!guy
From: guy@gorodish.Sun.COM (Guy Harris)
Newsgroups: comp.lang.c
Subject: Re: Bad optimization in PCC?
Message-ID: <50678@sun.uucp>
Date: 25 Apr 88 03:18:00 GMT
References: <793@amnesix.liu.se>
Sender: news@sun.uucp
Lines: 10

> While hacking a piece of code the other day, I came across what
> looks like a case of bad optimization in PCC-derivated compilers.

The peephole optimizer isn't part of PCC, so this doesn't have anything to do
with PCC per se.

> It seems to me that a *good* peep-hole optimizer should be able to
> recognize that if the jump at line (+) is taken then the jump at line
> (*) will not be taken.

Nope.  What happens if "*np" is asynchronously changed between the two tests?