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Fix a bug in RegsForValue::getCopyToRegs() that causes cyclical scheduling units. If it's creating multiple CopyToReg nodes that are "flagged" together, it should not create a TokenFactor for it's chain outputs:

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c1, f1 = CopyToReg                                                                                                                                                                                             
c2, f2 = CopyToReg                                                                                                                                                                                             
c3     = TokenFactor c1, c2                                                                                                                                                                                    
 ...                                                                                                                                                                                                                      
       = user c3, ..., f2

Now that the two CopyToReg's and the user are "flagged" together. They effectively forms a single scheduling unit. The TokenFactor is now both an operand and a successor of the Flagged nodes.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@50376 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2008-04-28 22:07:13 +00:00
parent 1fcfc3b6b2
commit 33bf38ad88
1 changed files with 12 additions and 2 deletions
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14
lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
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@ -3455,8 +3455,18 @@ void RegsForValue::getCopyToRegs(SDOperand Val, SelectionDAG &DAG,
Chains[i] = Part.getValue(0);
}
if (NumRegs == 1)
Chain = Chains[0];
if (NumRegs == 1 || Flag)
// If NumRegs > 1 && Flag is used then the use of the last CopyToReg is
// flagged to it. That is the CopyToReg nodes and the user are considered
// a single scheduling unit. If we create a TokenFactor and return it as
// chain, then the TokenFactor is both a predecessor (operand) of the
// user as well as a successor (the TF operands are flagged to the user).
// c1, f1 = CopyToReg
// c2, f2 = CopyToReg
// c3 = TokenFactor c1, c2
// ...
// = op c3, ..., f2
Chain = Chains[NumRegs-1];
else
Chain = DAG.getNode(ISD::TokenFactor, MVT::Other, &Chains[0], NumRegs);
}