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

[Dale Johannesen]

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?

>> +    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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