Re: C versus C++ parser performance

[Hans Aberg]

On 2 Feb 2007, at 09:53, Geoffrey D Alexander wrote:

> I have a C parser (using the C skeleton) that contains C++ code  
> that I'm
> compiling with g++.  The parser works fine. But a previous thread  
> titled
> "bison and C++" from December 2006 said that compiling C parsers  
> with a
> C++ compiler is no longer support.  So, I converted my compiler to use
> the C++ skeleton.  Functionally, this worked fine.  The new C++ parser
> produces the same output as the old C-based parser.
>
> However, I did notice a slowdown of 5 to 20 percent in the C++ parser.
> Also, the C++ parser shows an increase of 10 to 15 percent in the  
> number
> of memory allocation as reported by valgrind.
>
> Is this a known problem?  Are there plan to improve C++ parser
> performance?

People do not bother about such things, as typically, the parser does  
not take up much time in a compiler/interpreter: most time is spent  
in the lexer and the actions. In addition, memory is ample nowadays.  
So, for example, LR(1) becomes feasible but, which may blow up memory  
several times relative the LALR(1) that Bison uses.

  Hans Aberg