[llvm-commits] [llvm] r108735 - in /llvm/trunk: include/llvm/Target/TargetLowering.h lib/CodeGen/SelectionDAG/TargetLowering.cpp

[Jakob Stoklund Olesen]

On Jul 19, 2010, at 3:41 PM, Eric Christopher wrote:

> 
> On Jul 19, 2010, at 3:38 PM, Jakob Stoklund Olesen wrote:
> 
>> QPR has 16 registers, DPR has 32.
>> 
>> If each DPR counts as a QPR, the scheduler is going to behave as if there were only 16 DPR registers available. That is almost as bad as scheduling purely for register pressure.
>> 
> 
> True, but you could maybe count each QPR as two dprs and if you run into an occasion where that matters it'd suck, but I bet it'd be infrequent.

Right. That's what I meant by scaling. I think it is necessary.

Evan is probably right that QPRs and DPRs won't be live at the same time.

But we should at least get the number of registers right.

Overriding findRepresentativeClass for ARM does get the register counts right, though.