[LLVMdev] Simpler subreg ops in machine code IR

Jakob Stoklund Olesen stoklund at 2pi.dk
Tue Jun 15 18:45:20 PDT 2010

On Jun 15, 2010, at 6:21 PM, Rafael Espindola wrote:

>> 1. copyRegToReg() won't be able to use register classes to pick a copy opcode. For instance, an XMM register will no longer be copied by MOVSS or MOVSD. Given just the physical register, MOVAPS will be used. Is that a problem?
> I haven't had time to really look into it, but have been playing
> around with the idea that instead of two register classes copyRegToReg
> and some of the load and store callbacks should take a MVT. This
> should be enough, no? Anyway, I like anything that makes the backend
> interface simpler :-)

Well, MVTs are even harder to get at.

MVTs disappear when the SelectionDAG IR is translated to MachineInstr IR.
Register classes disappear with register allocation.

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