[LLVMdev] More address registers

[Evan Cheng]

On Feb 18, 2008, at 1:24 PM, Andreas Fredriksson wrote:

> 2008/2/15, Andreas Fredriksson <deplinenoise at gmail.com>:
> I tried mocking this up using the following. (Base is what's  
> returned as the Ax in the move expression above when the DAG is  
> constructed due to SelectAddr().)
>
>     SDOperand chain = CurDAG->getCopyToReg(Base, M68K::A3, Base);
>     Base = CurDAG->getCopyFromReg(chain, M68K::A3, MVT::i32);
>
> Replying to myself here.
>
> This worked a bit better :)
>
>     const unsigned addressReg = RegMap- 
> >createVirtualRegister(&M68K::AR32RegClass);
>     SDOperand chain = CurDAG->getCopyToReg(Base, addressReg, Base);
>     Base = CurDAG->getCopyFromReg(chain, addressReg, MVT::i32);

This probably will produce correct code since the copy source and  
destination registers are of different register classes it's not in  
danger of being coalesced away. But as you have seen, it'll produce  
poor code. I think it's a reasonable step in the right direction though.

Evan

>
>
>
> // Andreas
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