Path: utzoo!attcan!seachg!jalsop
From: jalsop@seachg.uucp (John Alsop)
Newsgroups: comp.sys.ncr
Subject: Re: Informix 4gl and C optimizer
Message-ID: <1990Dec20.140514.6995@seachg.uucp>
Date: 20 Dec 90 14:05:14 GMT
References: <1990Dec14.035146.18882@seachg.uucp> <1990Dec19.000453.5631@almira.uucp>
Reply-To: jalsop@seachg.UUCP (John Alsop)
Organization: Sea Change Corporation, Mississauga, Ontario, Canada
Lines: 28

In article <1990Dec19.000453.5631@almira.uucp> haug@almira.UUCP (Brian Haug) writes:
:In article <1990Dec14.035146.18882@seachg.uucp> jalsop@seachg.UUCP (John Alsop) writes:
:>I'm curious as to why the code generated by Informix' 4GL should cause such
:>pathological behaviour of the optimizer.  Ideas anyone?
:
:The reason for this pathological behaviour, taking a wild guess, is that the
:code has several constants, and the procedure is fairly long.  At optimization
:level 2, one of the optimization run in time proportional to the product of
:these two values (length of assembler code and number of constants).  You may
:also see this type of behaviour with lex output.

This sounds like it must be the problem.  The C code which was generated
by Informix in this case consisted of a large number of constant definitions 
and some long procedures which contained a large number of function calls 
and little else.

Unfortunately this kind of code can't really be optimized anyway, so all
the work is for nothing!


-- 
John Alsop

Sea Change Corporation
6695 Millcreek Drive, Unit 8
Mississauga, Ontario, Canada L5N 5R8
Tel: 416-542-9484 Fax: 416-542-9479
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