Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!rutgers!gatech!bloom-beacon!think!barmar
From: barmar@think.COM (Barry Margolin)
Newsgroups: comp.lang.misc
Subject: Re: Query re optimising hcrs
Message-ID: <24655@think.UUCP>
Date: 30 Jul 88 10:14:29 GMT
References: <561@etive.ed.ac.uk> <24414@think.UUCP> <3678@hcr.UUCP>
Sender: usenet@think.UUCP
Reply-To: barmar@kulla.think.com.UUCP (Barry Margolin)
Organization: Thinking Machines Corporation, Cambridge, MA
Lines: 25

In article <3678@hcr.UUCP> jim@hcr.UUCP (Jim Sullivan) writes:
]In article <24414@think.UUCP> barmar@kulla.think.com.UUCP (Barry Margolin) writes:
]>Under this assumption, the transformation of
]>     if <complex-expr> & <simple-expr>
]>     then <result>
]>into
]>     if <simple-expr>
]>     then if <complex-expr>
]>	  then <result>
]>is reasonable.
]Actually, it isn't....  For example,
]	if( a && b ) 

That is why MY example used "&", not "&&".  We should all know that
when the language semantics specify a particular order of evaluation
it is not reasonable for an optimizing compiler to change it.  The
discussion presupposed certain optimizations that are valid, and the
question was whether they are reasonable.


Barry Margolin
Thinking Machines Corp.

barmar@think.com
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