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Reuse operand location when updating PHI instructions.

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Calling RemoveOperand is very expensive on huge PHI instructions. This makes
early tail duplication run twice as fast on the Firefox JavaScript
interpreter.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95832 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2010-02-11 00:34:33 +00:00
parent 598b24c6d1
commit 09eeac9f5f
1 changed files with 26 additions and 7 deletions
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33
lib/CodeGen/TailDuplication.cpp
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@ -403,26 +403,45 @@ TailDuplicatePass::UpdateSuccessorsPHIs(MachineBasicBlock *FromBB, bool isDead,
II->RemoveOperand(i);
}
}
II->RemoveOperand(Idx+1);
II->RemoveOperand(Idx);
}
} else
Idx = 0;
// If Idx is set, the operands at Idx and Idx+1 must be removed.
// We reuse the location to avoid expensive RemoveOperand calls.
DenseMap<unsigned,AvailableValsTy>::iterator LI=SSAUpdateVals.find(Reg);
if (LI != SSAUpdateVals.end()) {
// This register is defined in the tail block.
for (unsigned j = 0, ee = LI->second.size(); j != ee; ++j) {
MachineBasicBlock *SrcBB = LI->second[j].first;
unsigned SrcReg = LI->second[j].second;
II->addOperand(MachineOperand::CreateReg(SrcReg, false));
II->addOperand(MachineOperand::CreateMBB(SrcBB));
if (Idx != 0) {
II->getOperand(Idx).setReg(SrcReg);
II->getOperand(Idx+1).setMBB(SrcBB);
Idx = 0;
} else {
II->addOperand(MachineOperand::CreateReg(SrcReg, false));
II->addOperand(MachineOperand::CreateMBB(SrcBB));
}
}
} else {
// Live in tail block, must also be live in predecessors.
for (unsigned j = 0, ee = TDBBs.size(); j != ee; ++j) {
MachineBasicBlock *SrcBB = TDBBs[j];
II->addOperand(MachineOperand::CreateReg(Reg, false));
II->addOperand(MachineOperand::CreateMBB(SrcBB));
if (Idx != 0) {
II->getOperand(Idx).setReg(Reg);
II->getOperand(Idx+1).setMBB(SrcBB);
Idx = 0;
} else {
II->addOperand(MachineOperand::CreateReg(Reg, false));
II->addOperand(MachineOperand::CreateMBB(SrcBB));
}
}
}
if (Idx != 0) {
II->RemoveOperand(Idx+1);
II->RemoveOperand(Idx);
}
}
}
}