Re: [Chicken-hackers] [PATCH] Fix performance bottleneck in compiling large files, add profiling option

[Felix]

From: Peter Bex <address@hidden>
Subject: Re: [Chicken-hackers] [PATCH] Fix performance bottleneck in compiling 
large files, add profiling option
Date: Mon, 23 Jan 2012 09:09:56 +0100

> On Mon, Jan 23, 2012 at 05:47:55AM +0100, Felix wrote:
>> > I think this option is generally useful since if the compiler reports
>> > a procedure nesting depth of more than about 10, this rapidly becomes
>> > useless to a user (it also reports procedure nesting when the
>> > scrutinizer finds a possible type error).
>> > 
>> 
>> Thanks for the patch and the investigation of this problem. I must
>> say that I would find such an option rather obscure.
> 
> I considered that, but I think in some cases it would be useful to
> be able to increase the limit, or remove it altogether.
> Don't forget, it's not just the C comments but also the scrutinizer
> messages that are affected by this option.
> 
> We could move the option to the "obscure options" section of the help :)
> 

No, please no such option.

>> Couldn't we simply
>> do a cutoff, probably preserving starting and ending elements of the
>> nesting list?, in other words:
>> 
>>   "FOO in BAR in ... in YES in NO in PERHAPS" ?
>> 
>> With (say) 10 elements at the front and the back this should be more
>> than sufficient.
> 
> This could be done but I'm afraid that traversing all the way up the
> tree also causes exponential cost.  A cutoff point ensures that there's
> an upper bound for each item, and that upper bound can be seen as a
> constant factor of the compilation as a whole.

Then cut it off, 20 should be enough.


cheers,
felix