Re: include/dis-asm.h patch for cgen disassemblers

[Andrew Cagney <ac131313 at cygnus dot com>]

[doh, I got binutils@wrong]

[Frank sent this privately, quoted with permission]

> Hi -
> 
> On Fri, Feb 01, 2002 at 01:32:52AM -0500, Andrew Cagney wrote:
> 
>> [...]
>> Yes, and both bfd_arch_ia64 and bfd_arch_i386 are defined as separate 
>> bfd_architectures.
> 
> 
> That's something else, explained by other factors, such as the
> ~12-year delay between their development, and a reluctance to
> build any given program with both pieces.
> 

It is also explained by someone making the rational decision that these two ISA's really are different and hence deserve separate bfd_architecture designations.

Consider the PS2.  It contains a number of compute engines (for want of a better term), each with their own ISA.  Do they each get their own bfd_architecture or does something else happen?

Remembering the history of BFD, I'd think they would get different bfd_architecture designations.  GDB has certainly been working on this assumption.

> 
> 
>> Sorry, can you try that again.
> 
> 
> Think about it.  If the processor has modes, each of which has a
> different set of instructions available to it, then for many
> purposes, those sets need to be formally identified as distinct
> groups.  That's what an instruction set is, in the deeper sense.
> 
> 
> 

To me this appears to be subverting what I understand to be the original intent of BFD's architecture / machine model. The subverting might be a good thing, however, it needs to be carefully considered and in a context that doesn't preassume definitions that CGEN or SID have adopted.

I think for this change to go through BFD needs to first clearly define (and document - hint!) what bfd_architecture, machine and this new thing are and where they apply.

My guess is ``environment'' (stolen from the PPC ISA manual).  For instance:

    bfd_powerpc - the ISA or ISA family
    ppc620 - the specific implementation - supports two modes (or as you like to call them ISA)
    environment - 32/64, operating/user, altivec, ...

Andrew