[llvm-commits] [llvm] r98007 - /llvm/trunk/lib/CodeGen/MachineCSE.cpp

[Evan Cheng]

On Mar 8, 2010, at 5:23 PM, Evan Cheng wrote:

> 
> On Mar 8, 2010, at 4:57 PM, Jakob Stoklund Olesen wrote:
> 
>> 
>> On Mar 8, 2010, at 3:28 PM, Evan Cheng wrote:
>> 
>>> Author: evancheng
>>> Date: Mon Mar  8 17:28:08 2010
>>> New Revision: 98007
>>> 
>>> URL: http://llvm.org/viewvc/llvm-project?rev=98007&view=rev
>>> Log:
>>> Restrict machine cse to really trivial coalescing. Leave the heavy lifting to a real coalescer.
>>> 
>>> Modified:
>>>  llvm/trunk/lib/CodeGen/MachineCSE.cpp
>>> 
>>> Modified: llvm/trunk/lib/CodeGen/MachineCSE.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineCSE.cpp?rev=98007&r1=98006&r2=98007&view=diff
>>> ==============================================================================
>>> --- llvm/trunk/lib/CodeGen/MachineCSE.cpp (original)
>>> +++ llvm/trunk/lib/CodeGen/MachineCSE.cpp Mon Mar  8 17:28:08 2010
>>> @@ -91,7 +91,10 @@
>>>   unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
>>>   if (TII->isMoveInstr(*DefMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
>>>       TargetRegisterInfo::isVirtualRegister(SrcReg) &&
>>> +        MRI->getRegClass(SrcReg) == MRI->getRegClass(Reg) &&
>>>       !SrcSubIdx && !DstSubIdx) {
>>> +      DEBUG(dbgs() << "Coalescing: " << *DefMI);
>>> +      DEBUG(dbgs() << "*** to: " << *MI);
>>>     MO.setReg(SrcReg);
>>>     DefMI->eraseFromParent();
>>>     ++NumCoalesces;
>> 
>> You could add "|| MRI->getRegClass(Reg)->hasSubClass(MRI->getRegClass(SrcReg))" without getting too complicated. That could help a bit with the few x86_64 subclasses as well.
>> 
> 
> I don't think it's necessary here. It's doing local coalescing here to avoid missing some obvious cse opportunities. If sub-reg class is involved, then it's already too complicated.

Actually I do need to make it more complicated. But then BlackFin hates me (I wonder if it's related to its author).

Evan

> 
> Evan
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