[Info-vax] If I wanted to get there, I certainly wouldn't start from here (was: Re: VMS on a PC)

[Richard Maher]

Hi John,

> As I've said before, Macro-32 is the real bottleneck.  Besides redoing
about
> 1/3 of the compiler (the same 1/3 redone from Alpha to I64), you have to
> come up with some mapping of the registers used by the current code base
> (code currently assumes registers R0-R31 are available in some fashion).
> Try mapping that onto the 16 registers in the X86-64 architecture and get
> that to work with linkages to C/BLISS; exception handling; unwinding; etc.

Again just idle curiosity, but would a lot of these problems go away if one
were porting VAX/VMS to X86 rather that Alpha or I64? I guess there's just
so much software and new versions that just never made it to VAX, but would
CISC to CISC have been a more straight forward exercise? Surely after
anything-to-EPIC, everything else has to be easy?

FWIW, I vote a big yes for JF's dead-horse! But where would they find the
resources for such a project?

Cheers Richard Maher

PS. Presumably after BLISS on VMS for I64, a "supported" BLISS for Windows
I64 would not be out of the question? Does Microsoft not bother with a
Windows version for Itanium any more? Does Rdb no longer induldge their
fantasies with that Rdb for NT Workbench thing? Did anyone (apart from Rdb
Engineering) ever really want Rdb on Windows anyway? And who really cares?

"John Reagan" <johnrreagan at earthlink.net> wrote in message
news:OrmdnbhjUqgxCunUnZ2dnUVZ_vjinZ2d at earthlink.com...
>
> "Alan Winston - SSRL Central Computing" <winston at SSRL.SLAC.STANFORD.EDU>
> wrote in message news:00A85C81.E779B5E0 at SSRL.SLAC.STANFORD.EDU...
>
> >
> > Wasn't there an 8086 port of Bliss for Windows NT?  (I think it's even
on
> > the freeware someplace.)
> >
>
> Yes.  However, it was truely X86-only.  Knew nothing about the 64-bit
> extensions to the architecture (additional registers, additional
> instructions).  Didn't generate ELF object files.  Conformed to the
Windows
> calling conventios.  And was only a subset of BLISS.  Features not used by
> GEM or Visual Fortran (or Rdb) were not implemented.  Beyond that, the
> X86-variant of GEM also didn't include features used by languages other
than
> BLISS or C.  For instance, all the packed decimal stuff used by COBOL or
> varying-length strings of Pascal was just stubbed-off.
>
> As I've said before, Macro-32 is the real bottleneck.  Besides redoing
about
> 1/3 of the compiler (the same 1/3 redone from Alpha to I64), you have to
> come up with some mapping of the registers used by the current code base
> (code currently assumes registers R0-R31 are available in some fashion).
> Try mapping that onto the 16 registers in the X86-64 architecture and get
> that to work with linkages to C/BLISS; exception handling; unwinding; etc.
>
> John
>
>