[Coco] [Color Computer] GCC update

[James Diffendaffer]

Sorry I haven't posted anything sooner.  I've been busy with work and
it appears that is only going to get worse since I'm going to be
starting on a new contract this week.  I just found out late Sunday.

Although I haven't really been coding I have worked out a few issues
related to OS-9 code generation.  The solution is actually going to be
that the assembler and linker are going to deal with it instead of the
compiler.

This has several advantages and a few disadvantages.

Advantages:
The GCC port will be easier this way.
It has the *potential* to generate the most efficient relocatable code.
Other compilers could benefit from this assembler and linker.

Disadvantages:
Object formats will change.
The assembler and linker will be more comples.
It will take some time to build the new assembler and linker.

I've already worked out how to build one of the nastiest parts of the
linker.  The branch/load/store optimizer.  
And I've worked out a method for prioritizing variable storage in Page
0 and the DP.

The bad news is prioritizing allocation of Page 0 and DP space will
require some trial and error in the formula used to calculate what
variables are most important.

Thes optimizations should generate the fastest code.  However it is
possible to write code that works under one linker but will break
under this linker.  Expecting non-stack variables/data defined
together to lie together in memory in a specific order is bad anyway
since this is undefined behavior in standard C.  If you want them to
stay together you will need to define them in a structure, array or
something else intended to be together.






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