Re: [Qemu-devel] [PATCH v2 04/18] tcg/aarch64: Implement field extraction opcodes

[Richard Henderson]

On 10/18/2016 08:33 AM, Claudio Fontana wrote:
> > > +    case INDEX_op_extract_i64:
> > > +    case INDEX_op_extract_i32:
> > > +        tcg_out_ubfm(s, ext, a0, a1, a2, a2 + args[3] - 1);
> > > +        break;
> > > +
> > > +    case INDEX_op_sextract_i64:
> > > +    case INDEX_op_sextract_i32:
> > > +        tcg_out_sbfm(s, ext, a0, a1, a2, a2 + args[3] - 1);
> > > +        break;
> > > +
> ah, probably missing something obvious.. not args[3]?

No, the r and s fields encode lsb and msb of the field.

I had the same wrong memory of the encoding; which is fair considering the 
aarch32 instruction *does* use lsb and size-1.

The failure was quite obvious even in the disassembly once I actually got a 
machine checked out to test it.


r~