Re: Crosspost: Help wanted from comp.compilers

[Marin David Condic <nobody@noplace.com>]

John: You're blocking. Tell us how you *really* feel. :-)

Here is a pretty valid point: Compilation time just isn't that big a 
deal these days. Recompiling the world on even a fairly large project 
just doesn't take that long. Not when compared to the overall 
development time. And the engineers almost always have something useful 
to do while waiting for the results of a recompile anyway, so what is 
the worry? Are we going to wear out the processor by making it execute a 
few million unnecessary instructions per second? Do we have to pay it by 
the module? Does it get bored, tired and lazy and want to quit unless 
you give it a pay raise? In my experience, not very often. So buy lots 
of really fast processors and let them have at it. They are enthusiastic 
and will work really hard even if you don't give them an "Atta boy!" 
very often.

In my experience, what seems to take a long time on a major recompile is 
when errors have got into the code and the compile is continually 
aborted mid-run so that some geek can go fix something he should have 
got right the first time, but didn't for any variety of reasons. 
(Mismatches between development and production versions of things are a 
typical culprit.) If it were not for having to stop and fix those 
errors, the compile time itself isn't really a slowdown of operations. 
At worst, you submit a batch job to run overnight and its done in the 
morning. Usually, it is nowhere near that bad - you run the compile and 
go clean up documentation while you wait for the results. Human 
multitasking tends to minimize any real issues about waiting for 
compilation. And even then, with processors and disks running as fast as 
they do, I just don't see that much wait time involved.

In some ways, I prefer to shoot everything in the head and *force* a 
recompilation of everything under the sun. That way, I am absolutely 
sure that what got compiled was the latest and greatest of everything 
and there isn't a snowball's chance in hell that I got some old, out of 
date, object file into the build due to some quirk or defect in the 
software that does the recompile. Its cheap insurance. To that end, 
Ada's insistence on consistency checking - even if poor implementations 
are sometimes overly conservative - is a good thing.

MDC



John R. Strohm wrote:

> Requiring recompilation is, IN THE PRESENCE OF GOOD SOFTWARE ENGINEERING, a
> safety check that isn't going to cost THAT much, compared to the potential
> cost of NOT recompiling.
> 


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Marin David Condic
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