gcc cross compiler for PDP-11

From: Paul Koning <pkoning_at_equallogic.com>
Date: Wed Feb 4 16:47:33 2004

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>> concerning gcc/binuils & pdp-11
>>
>> - gcc's (3.3.2) backend generates "unix" style asm
>> - gas wants "gas" style asm and doesn't like the "unix" style asm
>> - the pdp-11 gcc maintainer knows this and has some fixes which he's
>> going to release soon
>
> GCC version 3.x generates code that, um, sucks. For most C-based
> programming, there is absolutely no reason to "upgrade" beyond the
> older (V2.95.3) release, which works fine with the pdp11 backend.

There are plenty of day one bugs in the pdp11 backend. Some have been
fixed recently, others remain. It may be that the 2.95 version did a
better job of float handling than the early 3.x series, but I don't
think it actually gets it right. And there were problems with -(SP)
and (SP)+ modes for bytes... The calculation of instruction lengths
(to select between branches and "long branches") is also wrong.

I volunteered to take up the pdp11 backend maintainer slot, and I'm
trying to get some of these fixes in.

It would sure help if I could get explicit input. "It sucks" is not
data I can use to improve what's there. If people know of problems,
please submit bug reports. (Bug reports submitted by the standard gcc
bug submittal process would be best.)

By the way, the gcc backend generates either "dec" or "unix" output;
the "dec" output isn't technically valid dec syntax but it IS valid
gas syntax.

    paul
Received on Wed Feb 04 2004 - 16:47:33 GMT