[Boost-build] architecture/instruction-set

From: Vladimir Prus (ghost_at_[hidden])
Date: 2007-12-01 12:45:04

I was doing some documentation, and it seems to me that
architecture/instruction-set are confusingly named, and implemented.

For start, most compilers distinguish between generating code for
a given processor (which won't run on different processors, in general),
and tuning code for a given processor. gcc.jam uses <instruction-set>
to set -march, which is the hard processor selection. msvc.jam uses
<instruction-set> for /flavor -- which is "soft" tuning selection.
Should we have another <tune> option?

Also, now 'architecture' is general family (x86, ia64, sparc), and 
'instruction-set' is specific processor there. It does not seem to be
that 'architecture' is right name here -- after all, how the processor
is implemented internally is surely changed radically, several time,
during lifetime of x86.

Would a better naming be:

        - cpu-family (for general family, keeping backward 
        compatibility of some sort)
        - cpu (for exact cpu to target)

Or maybe we should just use 'cpu' with subfeatures for exact cpu?
Like

        cpu=x86-nocona

?

- Volodya

-- 
Vladimir Prus
http://vladimir_prus.blogspot.com
Boost.Build V2: http://boost.org/boost-build2