const, volatile, etc [was Re: #defines with parameters]

Piercarlo Grandi pcg at aber-cs.UUCP
Tue Dec 20 18:19:51 AEST 1988


In article <753 at auspex.UUCP> guy at auspex.UUCP (Guy Harris) writes:

#   Oh wow, another *ex cathedra* pronouncement from Pontifex Grandi I.

The only one that takes tremendously seriously his own postings is you, Guy.
It is you that is getting in the popist mould, scorching the heretic with
excommunications.  I may be advocating unfashionable ideas, but with
reasonable arguments, and ones that people can understand, and can debate and
so gain more understanding of the issues, if they want.

I am merely trying to persuade you that there are good points to be made on
my side as well, not that I am infallible like a committee :->. All I get in
return is cheap jabs at my person.

#   Please note that there are those who would - with good reason - claim
#   that there exist agressive optimizers that *are* cost-effective (cf.
#   MIPS).

Oh yes. But the existence of people that claim, with fair and reasonable
arguments, that aggressive optimization works so well on their hardware (and
can be ported to other architectures as well), does not imply that it is a
generally desirable idea. C and UNIX were designed by and for the people that
could not afford the MIPSes of their day, weren't they? Cost effectiveness
depends a lot on what you happen to have in your wallett... Is by any chance
your example meant to show that dpANS C is custom designed for well heeled
customers of the MIPSes of this world :-( ?  :-> :->.

#   Please note also that aggressive optimizers do more than just choose
#   whether to put variables into registers.

Indeed, indeed. Please note that I have never said otherwise (I am even on
record as having admitted that they do also introduce many interesting
bugs).  While I think that register variable selection is one of the
optimizations that are best left to the programmer, if he is competent
enough, I have given some examples of optimizations that I think best not to
leave to the programmer.  Please note that the sad argument about complex
optimizer (un)reliability stands high in many people's everyday experience.
-- 
Piercarlo "Peter" Grandi			INET: pcg at cs.aber.ac.uk
Sw.Eng. Group, Dept. of Computer Science	UUCP: ...!mcvax!ukc!aber-cs!pcg
UCW, Penglais, Aberystwyth, WALES SY23 3BZ (UK)



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