Re: RFA: Recording MIPS ABI selection in binaries

[Michael Eager <eager at eagercon dot com>]

One of the action items I have on my plate for the Dwarf2 
committee is to write/revise a proposal for handling multiple
architectures within a single compilation/executable.  My
current thinking is that this would be handled by an extension
to the line number information.  This would permit fine 
grained specification of the ISA.  (One motivation for this
is for a processor which can switch between ISA's in the
middle of an assembly file.)

I may not have followed this thread as well as I might have.
Is the question w/r/t MIPS about identifying MIPS 3 vs MIPS 4
ISAs, or distinguishing between 32-bit and 16-bit ISAs.  The
latter is (unfortunately) encoded in the low order bit of the
target address of a jump, and cannot easily be determined by 
looking at the object file.  

This probably doesn't have any relevance to other debugging
formats.  


Richard Henderson wrote:
> 
> On Wed, Aug 09, 2000 at 10:10:50AM -0700, Chris G. Demetriou wrote:
> > * should it even be compilation unit granularity?  It seems that a
> > mechanism for finer granularity would be appropriate...
> 
> Well, as proposed it would be in the CIE record, which is nominally
> one compilation unit.  You could have more than one per unit if you
> wished.
> 
> > it's possible to use different ISA assembly at finer granularity than
> > that, if you're coding in assembly.
> 
> If you're coding in assembly, you may be hard-pressed to get this
> information into the object file.  It's not easy to write dwarf2
> by hand; the assembler can do some (line numbers and such) but there's
> no existing mechanism by which to get stuff into the producer string.
> 
> > * is it actually easy for objdump to make use of debugging
> > information?
> 
> Not exactly.
> 
> r~


-- 
Michael Eager	 Eager Consulting     eager@eagercon.com
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