member descriptor ics

trying to fill in rewriting holes... for this one I had to some support for doubles and some `mov` variants in the assembler and rewriter. Kind of hacky/lazy...
yeah you're right; I actually thought I hadn't committed this change,
although I *do* think it's optional for `mov` and cousins, is that right?

On Mon, Sep 22, 2014 at 8:13 PM, Kevin Modzelewski <notifications@github.com
> wrote:

> In src/asm_writing/assembler.cpp:
>
> > @@ -116,7 +116,9 @@ void Assembler::emitInt(int64_t n, int bytes) {
> >  }
> >
> >  void Assembler::emitRex(uint8_t rex) {
> > -    emitByte(rex | 0x40);
> > +    if (rex != 0) {
> > +        emitByte(rex | 0x40);
> > +    }
>
> Hmm I'm not sure this is right -- I think an 0x40 REX prefix still can
> have meaning. For example I think you need to specify it to use certain
> 1-byte register parts:
> http://wiki.osdev.org/X86-64_Instruction_Encoding#REX_prefix
>
> ie I think this handling (don't emit rex if unnecessary) has to be handled
> by the instruction-specific function.
>
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> <https://github.com/dropbox/pyston/pull/151/files#r17890517>.
>