RE: Precompiled headers (or other speed ups)

[David Korn <dkorn at pixelpower dot com>]

>-----Original Message-----
>From: dewar@gnat.com [mailto:dewar@gnat.com]

><<was posted in last August, but there is a good example of how the parser
>can dominate just about everything.  That message kicked off a very good
>discussion on precompiled headers and parsing performance in C++.
>>.
>
>This is quite surprising, depending on what parsing means, if parsing
>means just building a syntax tree from the grammar, it is amazing that
>this should take any time at all compared to other phases.

  Well, only really surprising if you assume the parsing code is well
written :-) After all, the mid/backend is mostly doing memory-memory
transforms on the trees, and that's going to run as fast as your cache
and cpu can handle.  Parsers, OTOH, have to I/O.  Badly written parsers 
might even use c stdio functions to fgetc the entire file one char at a 
time....

    cheers, 
       DaveK
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