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Re: Problem with PFE approach [Was: Faster compilation speed]
- From: Devang Patel <dpatel at apple dot com>
- To: "Timothy J. Wood" <tjw at omnigroup dot com>
- Cc: Mike Stump <mrs at apple dot com>, gcc at gcc dot gnu dot org
- Date: Fri, 16 Aug 2002 13:54:40 -0700
- Subject: Re: Problem with PFE approach [Was: Faster compilation speed]
On Friday, August 16, 2002, at 01:31 PM, Timothy J. Wood wrote:
Are there problems with what I describe below or are people just
avoiding commenting on this since it is too hard to implement? :)
I wanted to stop reading after "a) Toss some or all of your PFE code in
the bin (yikes!)"
In any case, you want best of both worlds -- cpp-precomp (Apple's yet
another precomp implementation) and PFE.
Both of uses very different models
1) cpp-precomp saves and restores tokens. Where as, PFE (and PCH,
AFAIK)
is based on saving and restoring internal trees.
2) One replace #include statement in-place with preprocessed tokens
where as
other continues compilation from previously saved trees.
In your previous two queries, what you want from PFE is to discard few
things
based on macros from precompiled headers. But when PFE restores trees,
it has gone too far as far as macros are concerned.
- Devang