[llvm-commits] CVS: llvm/lib/CodeGen/LiveIntervalAnalysis.cpp RegAllocLinearScan.cpp VirtRegMap.cpp VirtRegMap.h

[Chris Lattner]

On Mar 30, 2007, at 3:03 PM, Evan Cheng wrote:

>>>              unsigned reg = rep(mop.getReg());
>>>              mii->getOperand(i).setReg(reg);
>>>
>>> +            // If the definition instruction is re- 
>>> materializable, its spill
>>> +            // weight is zero.
>>>              LiveInterval &RegInt = getInterval(reg);
>>> -            RegInt.weight +=
>>> -              (mop.isUse() + mop.isDef()) * pow(10.0F, (int) 
>>> loopDepth);
>>> +            if (!RegInt.remat) {
>>> +              RegInt.weight +=
>>> +                (mop.isUse() + mop.isDef()) * pow(10.0F, (int) 
>>> loopDepth);
>>> +            }
>>
>> Should it really be zero?  It should definitely be lower that a  
>> normal value, but zero seems low.  The loop depth should still be  
>> taken into consideration.
>
> Funny you should mention this. I am re-evaluating this right now.  
> My thinking is loads (load from constantpool or stack slots) would  
> have the normal weight. The rest will have half the weight.

Why not just make everything half weight?  What would be lost?

-Chris