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From: HBO043%DJUKFA11.BITNET@cunyvm.cuny.edu (Christoph van Wuellen)
Newsgroups: comp.os.minix
Subject: 68000 and 386 C compiler: doc page
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Date: 1 Mar 91 18:37:59 GMT
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68000 and i386 C Compiler     ---  Version III patchlevel 1   (III.1)
=========================          ..................................

This compiler consists of various modules that build up a
front end -- these modules are common to all versions of
this compiler -- consisting of parser, analyzer and optimizer,
of modules that are specific for the target processor,
namely *68k.c (for the 68000) and *386.c (for the i386),
and of assembly language output modules that are further
dependent on the (syntax of the) target assembler.

The specific modules are:

gen386.c, reg386.c, peep386.c
=============================

Code generator modules for the i386 processor, namely
code generator (gen386.c), register allocator (reg386.c),
and peephole optimizer (peep386.c)

out386_gas.c     <<--this file was called out386_sun.c in Version III.0)
============

At this moment, this is the only output module for the i386 compiler.
It generates assembler files compatible with the GNU GAS assembler.
If compiled with -DSUN_ASM_SYNTAX, the output is compatible with the
Sun386i-Assembler. There are very little differences between the Sun
and the GAS assembler

gen68k.c, reg68k.c, peep68k.c
=============================

Code generator (gen68k.c), register allocator (reg68k.c), and
peephole optimizer (peep68k.c) for the 68000 compiler.

out68k_ack.c
============

Output module for the ACK assembler as supplied with the MINIX
operating system.

out68k_gas.c
============

Output module for the GAS assembler.

out68k_cpm.c
============

Output module for the CP/M-68K assembler. This is the same assembler
as supplied with the developement package for the ATARI and thus,
this module is also compatible with the ALCYON and SOZOBON assembler.

The module contains some other dirty tricks such as a very special
translation of external symbols (which helped me to install some
software in spite of the fact that external names are truncated to
eight characters) etc.
It has not been maintained since very long, since I stopped working
with CP/M-68K.

Compile-time options
====================

There are several symbols you can define at compile time to control
the behaviour of the compiler.

-DICODE		enables the -Qicode option (see below)

-DVERBOSE	the compiler will generate diagnostics while compiling
                when compiled with this option. This should be a
                run-time option.

-DMC68000       The compiler will be a 68000 compiler

-DINTEL_386     The compiler will be a i386 compiler

Although you can compile, say, gen68k.c with -DINTEL_386 (this produces
an 'empty' object file), you must only compile one of the alternate
output modules. This may be fixed in the future at the expense of
additional -Dxxxxx options, e.g. -DACK might only activate code
in out68k_ack.c, not in the other 68k output modules.


INVOCATION OF THE COMPILER
==========================

Normally, you will call this compiler from a driver such as cc.
This chapter gives you the necessary information to patch the
internal tables of cc as to support this compiler.

The compiler is basically called with two arguments, the input-file
and the output-file.
The input file contains PREPROCESSED C-sources and is normally the
output of cpp, the C preprocessor.
The output file contains the assembly language file.

To compile a source, source.c, to an object file you could type the
commands (this example works under MINIX-68K)

/usr/lib/cpp source.c > TMPFILE.i
/usr/lib/c68 TMPFILE.i TMPFILE.s
rm TMPFILE.i
/usr/bin/as - -o source.o TMPFILE.s
rm TMPFILE.s

In fact, c68 together with cpp replaces cem, opt, and cg.

c68/c386 may also be given some options. The syntax is:

c68 <option>.... infile outfile

All options begin with -Q, such that cc knows quickly which option
(which is given to cc originally) is meant to be supplied to c68/c386.

Not all options are accepted on all targets. The i386 compiler does not
support 16-bit ints because this is incompatible with stack alignment.
The 68000 compiler does not have FPU support because there is no FPU
for the 68000.

List of options:
================

-Qlist          Generate a file, c68.list or c386.list, which
                lists the preprocessed input file, symbol tables,
                and error spots. Primarily used for compiler debugging.

-Qnolist        Do not generate a list file (Default).

-Qicode         Generate a file, c68.icode or c386.icode, which
                dumps the parse tree in human-readable format.
                Only accepted if the compiler is itself compiled with
                -DICODE. This is used for compiler debugging.

-Qnoicode       Do not dump the parse tree (Default).
                Only accepted if the compiler is itself compiled with
                -DICODE. This is used for compiler debugging.

-Qshort         Use 16-bit ints. Default for the 68000 compiler.

-Qnoshort       Use 32-bit ints. Default for the i386 compiler.

-Qwarn          Print all warning mesages.

-Qnowarn        Suppress (most of the) warning messages (default).

-Qreg           Allocate variables to registers automatically.
                Variables declared with the register attribute
                are allocated first, even if the compiler
                considers them less important.

-Qnoreg         Allocate only variables with have a register
                attribute to register variables. This might be
                important if you have problems with automatically
                allocated register variables in conjunction with
                longjmp().

                One of the next patches will support a volatile
                attributes which prevents variables from being
                mapped to registers. This is an ANSI extension, but
                easy to implement. If you have problems with longjmp(),
                try if -Qnoreg helps.

-Qopt           Perform optimizations. Of course, this is the default.

-Qnoopt         Do not perform ANY optimization. Useful only for
                compiler debugging. -Qnoopt includes -Qnoreg.

-Qfpu		Generate inline FPU code. This is the default for
                the i386 compiler.

-Qnofpu		Generate library calls for doing floating point
                operations. This is the default for the 68000 compiler.

===========================================

Christoph van Wuellen
Lehrstuhl fuer Theoretische Chemie
Ruhr Universitaet
4630 Bochum

Germany