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Simplify a check for implicit defs and remove a FIXME. 

llvm-svn: 122537
This commit is contained in:
Cameron Zwarich 2010-12-24 03:09:36 +00:00
parent 338f9aaab2
commit ab434079d3
1 changed files with 6 additions and 8 deletions
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14
llvm/lib/CodeGen/StrongPHIElimination.cpp
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@ -189,20 +189,18 @@ void StrongPHIElimination::InsertCopiesForPHI(MachineInstr* PHI,
SmallPtrSet<MachineBasicBlock*, 8> MBBsInsertedInto;
for (unsigned i = 1; i < PHI->getNumOperands(); i += 2) {
MachineOperand& SrcMO = PHI->getOperand(i);
// If a source is defined by an implicit def, there is no need to insert a
// copy in the predecessor.
if (SrcMO.isUndef())
continue;
unsigned SrcReg = SrcMO.getReg();
unsigned SrcSubReg = SrcMO.getSubReg();
assert(TargetRegisterInfo::isVirtualRegister(SrcReg) &&
"Machine PHI Operands must all be virtual registers!");
// If source is defined by an implicit def, there is no need to insert a
// copy.
// FIXME: For some reason, if LiveIntervals is run prior to PHI elimination
// implcit defs have no defining instruction. Is this expected?
MachineInstr* DefMI = MRI->getVRegDef(SrcReg);
if (!DefMI)
continue;
MachineBasicBlock* PredBB = PHI->getOperand(i + 1).getMBB();
// A copy may have already been inserted in the predecessor in the case of a