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linking performance [message #977605]

Fri, 09 November 2012 07:19

Vlad Dumitrescu
Messages: 313
Registered: July 2009
Location: Gothenburg

Senior Member

Hi!

This question is related to my previous ones, regarding to performance when running the Xtext builder on files. I found that part of the problem is caused by the linking step that needs to do a lot of work. However, I can't see how to change the grammar so as to need a lighter linker. I hope someone can give me some pointers.

The language has symbols that can either just represent themselves or be references to named elements in the code. Originally I modeled all these symbols as potential links and used the linker to decide whether it's a real one or not. But that slows it down considerably.

I tried to specify the exact kind of reference that is expected, since in several places it is possible to know that statically and that resulted in a halving of the time the Xtext builder needed!

But of course the joy didn't last long, because in the general case of an expression, a symbolic value may be any of these references or a simple name and the parser can't discern which, because they all look alike. Of course, it has the info higher up in the stack, but this isn't a context-sensitive parser.

Is there any trick that I can use, or is my initial solution the only one that works? Or maybe I just misunderstood a lot of things about how to use Xtext?

Code example to understand the problem. A function call's target can be a general expression.

In the case where the reference can be resolved statically, we want two cross-references, one to the "mod" and one to the "fun".

mod.fun(1,mod,fun)

Here, ?MOD is a macro that is known at compile time. Here we want two cross-references from it, one to the macro definition and in case the value is a symbol, to that module.

?MOD.fun(1,?MOD,fun)

In this third case, Fun is a variable and we don't know its value. No cross-references.

mod.Fun(1,mod,Fun)

In the parameter lists, "mod" and "fun" are just names unrelated to the ones before. The macro and variable should reference their respective definitions.

best regards,
Vlad

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[Message index]

		linking performance By: Vlad Dumitrescu on Fri, 09 November 2012 07:19
		Re: linking performance By: Sebastian Zarnekow on Fri, 09 November 2012 08:54
		Re: linking performance By: Vlad Dumitrescu on Fri, 09 November 2012 09:30
		Re: linking performance By: Henrik Lindberg on Fri, 09 November 2012 09:44
		Re: linking performance By: Vlad Dumitrescu on Sat, 10 November 2012 17:15
		Re: linking performance By: Henrik Lindberg on Sun, 11 November 2012 22:51
		Re: linking performance By: Vlad Dumitrescu on Tue, 13 November 2012 05:47
		Re: linking performance By: Henrik Lindberg on Tue, 13 November 2012 10:27
		Re: linking performance By: Ed Merks on Tue, 13 November 2012 12:12
		Re: linking performance By: Vlad Dumitrescu on Tue, 13 November 2012 18:07
		Re: linking performance By: Ed Merks on Wed, 14 November 2012 00:48
		Re: linking performance By: Vlad Dumitrescu on Wed, 14 November 2012 04:05
		Re: linking performance By: Knut Wannheden on Tue, 27 November 2012 04:50
		Re: linking performance By: Sebastian Zarnekow on Tue, 27 November 2012 06:05

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