This is the mail archive of the cgen@sources.redhat.com mailing list for the CGEN project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

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


Hi -

cagney wrote:
> [...]
> > isa ~= instruction set ~= group of machine instructions decodable;
> >                           can be a function of cpu state
> 
> Er, ISA == Instruction Set Architecture which to me is bfd_architecture. 
>   I think, here you're looking for something else.
> 
> For instance, Arm has thumb and MIPS has MIPS16.  They are modes but 
> sill part of a single ISA.

Yes, but not in an interesting sense.  It's much like the IA32 engine
inside IA64: they surely aren't the same ISA, despite being executable
by the same hardware, and operating partly on the same registers.
Sure, arm & thumb are closer together, and they may be documented in
the same publication, but that's not substantial to this question.

The conceptual issue is whether or not the choice of instructions
available is a function of processor state.  For the purposes of
tools like disassemblers and simulators, and really even assemblers
and compilers, each such group forms a separate instruction set.


- FChE

Attachment: msg00033/pgp00000.pgp
Description: PGP signature


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]