[M3devel] help booting CM3 on FreeBSD 4.11?

[Tony Hosking]

On 25 Apr 2009, at 09:21, Jay wrote:

>
>> By the way, I take it booting the compiler "old-fashionedly" with
>> PM3 is out of the question?
>
>
> What is the PM3 way?
>  The SRC way is out of the question at least (unless you want to / 
> start/ with it and go through a few releases...).
>
> I gather that the PM3 was good and could be resusitated.
> But it is is some work..maybe too much.
>
> I gather that PM3 factored out word size and endianness from the IL?
> And padding/alignment? And jmpbuf size?

Nope. Same as cm3.

>
>  And whatever else is target-dependent?
>  There isn't much.
> Not impossible, but seems a bit onerous.
>
> padding/alignment actually don't have to be factored out, kind of.
> They can be made "worst case", as long as the interactions with C  
> are correct.
>
> word size and endianness are in the IL but I think only barely.
>
> jmpbuf size is easy to factor out at a small perf cost.
> or again, make it worst case.
>
>
> These "worst cases" are likely to be pretty bad, such that they are  
> ok for building the first compiler, but then you'd want to  
> immediately rebuild it "ideally".
> jmpbuf size varies from around 16 bytes to over 200 bytes for example.
> You could also use
> extern int jmpbufsize;
> jmpbuf = alloca(jmpbufsize)
>
>
> thereby not blowing stack, but still being slow.
> Again, fine for bootstrap purposes but it should end there.
>
>
> "aligned procedures" can be factored out easily via acting worst case.
>
>
> Is this what PM3 did though?
> Shipped one textual IL for all platforms, built m3cc (which doesn't / 
> really/
> require having cm3), then built everything from the portable IL,  
> then rebuilt it all again more ideally?
>
> I think if a portable distribution format is to be had, maybe go all  
> the way to using a C backend? However that doesn't solve all/many/ 
> any of the above problems, given how low level the IL is.
>
>
> - Jay