Path: utzoo!attcan!uunet!samsung!think.com!linus!agate!shelby!neon!Gang-of-Four!dkeisen
From: dkeisen@Gang-of-Four.Stanford.EDU (Dave Eisen)
Newsgroups: comp.lang.c
Subject: Re: '386 XENIX "cc -Ox" optimization bug
Keywords: -Ox
Message-ID: <1990Dec14.153442.19210@Neon.Stanford.EDU>
Date: 14 Dec 90 15:34:42 GMT
References: <40991@ut-emx.uucp> <1990Dec13.175120.12187@robot.in-berlin.de>
Sender: news@Neon.Stanford.EDU (USENET News System)
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Lines: 22

In article <1990Dec13.175120.12187@robot.in-berlin.de> karl@robot.in-berlin.de (Karl-P. Huestegge) writes:
>Always 'works ok' with MSC 386 5.1 on my system.
>
>BTW: -Ox is default. And is the same as -Oactl. All three cc-commands
>     produce the same code.

Nope. The default for -O is -Ot (optimize for time), not a, c, or l. 
-Ox (which is the same as -Oactl) relaxes alias checking so it can
change the semantics of your code if there is any aliasing going on.
Use it with great caution. 

I would have preferred to see their "maximum" optimization mean
maximum optimization that doesn't break correct code. 




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Dave Eisen                      	    dkeisen@Gang-of-Four.Stanford.EDU
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