Martin,
I did a port of GCC to the Analog Devices SHARC chip. I ended up
supporting 3 kinds of pointers for this chip (two for address
spaces and one for byte pointers - the chip itself is only word
addressable (although words can be from 16 to 48 bits in size
depending on what memory is being accessed.)
I also worked on the Bliss-36 compiler at DEC, so I'm well acquainted
with the PDP10 architecture.
I don't have access to any 10/20 HW, but I'd be happy to act as a
reviewer/advisor to your changes.
Al Lehotsky
On Apr 18, 2008, at 20:21, Martin Chaney wrote:
Hi,
I'm am the proprietor of a gcc compiler for the PDP10 architecture.
(This is a compiler previously worked on by Lars Brinkhoff who left
XKL some while before I joined XKL. It's possible some of you may
have been familiar with him or the compiler from that time.)
The compiler is currently in a state where it is synched with the
both the 4.3 and 4.4 branches, and it passes the testsuite tests
(with the exception of some I've flagged as expected failures for
the pdp10).
My employer is happy to release my work on the gcc compiler back to
the gcc community and I've sent in a request for the necessary forms.
The PDP10 architecture is unusual in various ways that distinguish
it from the mainstream architectures supported by the gcc compiler
and this has made the development of this compiler a significant
task. Undoubtedly I've made customizations in inappropriate ways.
I'm seeking contacts with people who might be able to advise me on
how to cleanup my implementation to reduce the amount of #ifdef
__PDP10_H__ I've sprinkled liberally throughout the source. Also,
if its possible to get simple changes made to prevent breaking my
PDP10 version and that are otherwise innocuous that would be
wonderful. For example, the PDP10 word size is 36 bits; Fairly
recently people have taken to writing code that assumes word size
is a power of 2 even when it's straightforward to write in a manner
that doesn't make that assumption.
Considering the large number of files customized to get the PDP10
compiler working, I'm not sure whether it's possible to get it to
build directly from the gcc trunk, but it would be nice to work
toward that goal.
Some other things which distinguish the PDP10 architecture from
assumptions in the gcc code base include: its variety of formats of
pointers only one of which can be viewed as an integer and that one
is capable of referencing only word aligned data, a functional
difference between signed and unsigned integers, and peculiarities
to the use of PDP10 byte arrays which are very difficult to describe.
Any help or advise would be appreciated.
Martin Chaney
XKL, LLC
