From mboxrd@z Thu Jan  1 00:00:00 1970
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From: dewar@cs.nyu.edu (Robert Dewar)
Subject: Re: Can compilers do this?
Date: 1996/02/23
Message-ID: <dewar.825137225@schonberg>#1/1
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references: <4gjd6g$mfq@newsbf02.news.aol.com>
organization: Courant Institute of Mathematical Sciences
newsgroups: comp.lang.ada
Date: 1996-02-23T00:00:00+00:00
List-Id: <comp.lang.ada>

To follow up BwB's question

"Also, suppose Y and X are floating point variables, and M and B are
CONSTANT floating point variables (not named numbers) initialized to
1.0  and  0.0  respectively. If one writes

     Y := M * X  +  B ;

can (and will) any compiler reduce this to

     Y := X ;"

They do not even have to be CONSTANT floating point variables, the
compiler may well be able to figure out the current values of
variables without them being CONSTANT.

If indeed they are constant, I cannot imagine any compiler that would

NOT do the optimization you suggest. Any compiler that did not is
broken if you ask me!