Date: Fri, 20 Jun 2003 16:18:45 -0400
Message-Id: <200306202018.h5KKIjZD027328@envy.delorie.com>
From: DJ Delorie <dj AT delorie DOT com>
To: djgpp AT delorie DOT com
In-reply-to: <3ef366a3_5@corp.newsgroups.com> (some.net@delorie.com)
Subject: Re: DJGPP internals
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>     Does anyone know (I know DJ does)

Yes, I know ;-)

> how many passes the djgpp compiler does? If I'm correct modern
> compiler are 3 pass compilers. c0-c2 or is that c3?

The notion of "passes" is fuzzy in gcc.  There are 4-5 programs
involved (newer ones have cpp and cc1 combined):

* gcc (driver)
* cpp
* cc1
* as
* ld

Within cc1, there are a few major activities going on:

* Conversion of source language to a parse tree
* Optimization of the parse tree.
* Conversion of the parse tree to RTL.
* Optimization of the RTL.
* Conversion of RTL to assembly.

If you want to know how many times any of these programs loops over
the program (in whatever form it's in), the answer is LOTS.  Even the
assembler is a multi-pass assembler.

> How does the crt.o or C runtime fit into the compiling of the source?

It's only used at the very end, when the linker is invoked.