[Simh] simh and jump tables

[Norman Lastovica]

When all of the modules are specified at
once and if a single oject file is being
produced, you can use /ASSUME=WHOLE which
lets the compiler treat all of the source
as being the entire program with DECC.

        [NO]WHOLE_PROGRAM

           Asserts to the compiler that except for "well-behaved library
           routines," the whole program consists only of the single
           object module being produced by this compilation.  The
           optimizations enabled by /ASSUME=WHOLE_PROGRAM include all
           those enabled by /ASSUME=NOPOINTER_TO_GLOBALS, and possibly
           additional optimizations as well.

           The default is /ASSUME=NOWHOLE_PROGRAM.

> -----Original Message-----
> From: simh-bounces at trailing-edge.com
> [mailto:simh-bounces at trailing-edge.com]On Behalf Of Tackett Galen
> Sent: Monday, April 10, 2006 10:38 AM
> To: simh at trailing-edge.com
> Subject: Re: [Simh] simh and jump tables
> 
> 
> Villy,
> 
> Don't think it futile. Think of it as education. :-) I'm sure some of the
> rest of us did learn a bit from what you wrote.
> 
> Regarding C compilers and optimizations, the only one I know really well is
> HP C for OpenVMS (VAX, Alpha and IA64) but similar things may apply to other
> compilers--
> 
> Recent versions of HP C for OpenVMS do a lot of optimization by default, but
> certain kinds of optimizations, especially some architecture-specific ones,
> don't happen by default. I don't have enough experience with these
> optimizations, or with simh for that matter, to be able to judge their
> effectiveness for this application. It would be entertaining to try if I
> only had the time and a VMS system at home (wish wish :)
> 
> One such feature, called "plus list optimization", enables optimization
> across multiple source files. It basically involves using "+" instead of ","
> to separate the names of your [multiple] source files. I can imagine
> scenarios where this might be especially effective, but I haven't a clue
> whether simh might be such.
> 
> Thanks for commenting on your experience, Villy. Always keep exploring.
> 
> --
> Galen
> 
> 
> Villy wrote: 
> > Well
> >
> >the end result of 10 - 12 hours of intensive coding is the discovery that
> >the switch statements in C (well GCC) at least are coded as computed jumps
> -
> >a fact that I might have realized if I didn't have this long standing
> > hate relationship with C.
> >...
> >
> >The big question now  is - which compiler was used to generate the 
> > distribution.
> 
> > Interesting exercise - if somewhat futile.
> 
> 
> 
> 
> 
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