[llvm-commits] [llvm] r47554 - /llvm/trunk/lib/Target/X86/X86ISelLowering.cpp

[Evan Cheng]

On Feb 25, 2008, at 11:49 AM, Dale Johannesen wrote:

>
> On Feb 25, 2008, at 11:44 AM, Evan Cheng wrote:
>
>>
>> On Feb 25, 2008, at 11:20 AM, Dale Johannesen wrote:
>>
>>>                                const X86Subtarget *Subtarget) {
>>>
>>> +    // Must be a store of a load.  We currently handle two cases:
>>> the load
>>> +    // is a direct child, and it's under an intervening
>>> TokenFactor.  It is
>>> +    // possible to dig deeper under nested TokenFactors.
>>> +    if (ChainVal == St->getValue().Val)
>>> +      Ld = cast<LoadSDNode>(St->getChain());
>>
>> I'm not sure how safe this is. It can be storing a value produced by
>> any chain producing node. Can it be a CopyFromReg?
>>
>> Evan
>
> It is checked above that St->getValue() is a load.  Is that not  
> enough?

Ok. Can you put ST->getValue() in an appropriately named variable to  
help me understand the code? Thanks.

Evan

>
>
>>> +    else if (St->getValue().hasOneUse() &&
>>> +             ChainVal->getOpcode() == ISD::TokenFactor) {
>>> +      for (unsigned i=0, e = ChainVal->getNumOperands(); i != e; +
>>> +i) {
>>> +        if (ChainVal->getOperand(i).Val == St->getValue().Val) {
>>> +          if (TokenFactorIndex != -1)
>>> +            return SDOperand();
>>> +          TokenFactorIndex = i;
>>> +          Ld = cast<LoadSDNode>(St->getValue());
>>> +        } else
>>> +          Ops.push_back(ChainVal->getOperand(i));
>>> +      }
>>> +    }
>>> +    if (Ld) {
>>> +      // If we are a 64-bit capable x86, lower to a single movq
>>> load/store pair.
>>> +      if (Subtarget->is64Bit()) {
>>> +        SDOperand NewLd = DAG.getLoad(MVT::i64, Ld->getChain(),
>>> +                                      Ld->getBasePtr(), Ld-
>>>> getSrcValue(),
>>> +                                      Ld->getSrcValueOffset(), Ld-
>>>> isVolatile(),
>>> +                                      Ld->getAlignment());
>>> +        SDOperand NewChain = NewLd.getValue(1);
>>> +        if (TokenFactorIndex != -1) {
>>> +          Ops.push_back(NewLd);
>>> +          NewChain = DAG.getNode(ISD::TokenFactor, MVT::Other,
>>> &Ops[0],
>>> +                                 Ops.size());
>>> +        }
>>> +        return DAG.getStore(NewChain, NewLd, St->getBasePtr(),
>>> +                            St->getSrcValue(), St-
>>>> getSrcValueOffset(),
>>> +                            St->isVolatile(), St->getAlignment());
>>> +      }
>>> +
>>> +      // Otherwise, lower to two 32-bit copies.
>>> +      SDOperand LoAddr = Ld->getBasePtr();
>>> +      SDOperand HiAddr = DAG.getNode(ISD::ADD, MVT::i32, LoAddr,
>>> +                                     DAG.getConstant(MVT::i32, 4));
>>> +
>>> +      SDOperand LoLd = DAG.getLoad(MVT::i32, Ld->getChain(),  
>>> LoAddr,
>>> +                                   Ld->getSrcValue(), Ld-
>>>> getSrcValueOffset(),
>>> +                                   Ld->isVolatile(), Ld-
>>>> getAlignment());
>>> +      SDOperand HiLd = DAG.getLoad(MVT::i32, Ld->getChain(),  
>>> HiAddr,
>>> +                                   Ld->getSrcValue(), Ld-
>>>> getSrcValueOffset()+4,
>>> +                                   Ld->isVolatile(),
>>> +                                   MinAlign(Ld->getAlignment(),  
>>> 4));
>>> +
>>> +      SDOperand NewChain = LoLd.getValue(1);
>>> +      if (TokenFactorIndex != -1) {
>>> +        Ops.push_back(LoLd);
>>> +        Ops.push_back(HiLd);
>>> +        NewChain = DAG.getNode(ISD::TokenFactor, MVT::Other,
>>> &Ops[0],
>>> +                               Ops.size());
>>> +      }
>>> +
>>> +      LoAddr = St->getBasePtr();
>>> +      HiAddr = DAG.getNode(ISD::ADD, MVT::i32, LoAddr,
>>> +                           DAG.getConstant(MVT::i32, 4));
>>> +
>>> +      SDOperand LoSt = DAG.getStore(NewChain, LoLd, LoAddr,
>>>                         St->getSrcValue(), St->getSrcValueOffset(),
>>>                         St->isVolatile(), St->getAlignment());
>>> +      SDOperand HiSt = DAG.getStore(NewChain, HiLd, HiAddr,
>>> +                                    St->getSrcValue(), St-
>>>> getSrcValueOffset()+4,
>>> +                                    St->isVolatile(),
>>> +                                    MinAlign(St->getAlignment(),
>>> 4));
>>> +      return DAG.getNode(ISD::TokenFactor, MVT::Other, LoSt, HiSt);
>>>   }
>>> -
>>> -    // Otherwise, lower to two 32-bit copies.
>>> -    SDOperand LoAddr = Ld->getBasePtr();
>>> -    SDOperand HiAddr = DAG.getNode(ISD::ADD, MVT::i32, LoAddr,
>>> -                                   DAG.getConstant(MVT::i32, 4));
>>> -
>>> -    SDOperand LoLd = DAG.getLoad(MVT::i32, Ld->getChain(), LoAddr,
>>> -                                 Ld->getSrcValue(), Ld-
>>>> getSrcValueOffset(),
>>> -                                 Ld->isVolatile(), Ld-
>>>> getAlignment());
>>> -    SDOperand HiLd = DAG.getLoad(MVT::i32, Ld->getChain(), HiAddr,
>>> -                                 Ld->getSrcValue(), Ld-
>>>> getSrcValueOffset()+4,
>>> -                                 Ld->isVolatile(),
>>> -                                 MinAlign(Ld->getAlignment(), 4));
>>> -
>>> -    LoAddr = St->getBasePtr();
>>> -    HiAddr = DAG.getNode(ISD::ADD, MVT::i32, LoAddr,
>>> -                         DAG.getConstant(MVT::i32, 4));
>>> -
>>> -    SDOperand LoSt = DAG.getStore(LoLd.getValue(1), LoLd, LoAddr,
>>> -                        St->getSrcValue(), St->getSrcValueOffset(),
>>> -                        St->isVolatile(), St->getAlignment());
>>> -    SDOperand HiSt = DAG.getStore(HiLd.getValue(1), HiLd, HiAddr,
>>> -                                  St->getSrcValue(), St-
>>>> getSrcValueOffset()+4,
>>> -                                  St->isVolatile(),
>>> -                                  MinAlign(St->getAlignment(), 4));
>>> -    return DAG.getNode(ISD::TokenFactor, MVT::Other, LoSt, HiSt);
>>> }
>>> return SDOperand();
>>> }
>>>
>>>
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