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Teach LiveVariables to handle <undef> operands. 

It's simple: Don't treat <undef> operands as uses, and don't assume a
virtual register has a defining instruction unless a real use has been
seen.

llvm-svn: 159061
This commit is contained in:
Jakob Stoklund Olesen 2012-06-23 02:23:00 +00:00
parent 3a691a367c
commit 502e4c6ac4
1 changed files with 5 additions and 3 deletions
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8
llvm/lib/CodeGen/LiveVariables.cpp
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@ -573,7 +573,8 @@ bool LiveVariables::runOnMachineFunction(MachineFunction &mf) {
unsigned MOReg = MO.getReg();
if (MO.isUse()) {
MO.setIsKill(false);
UseRegs.push_back(MOReg);
if (MO.readsReg())
UseRegs.push_back(MOReg);
} else /*MO.isDef()*/ {
MO.setIsDead(false);
DefRegs.push_back(MOReg);
@ -729,8 +730,9 @@ void LiveVariables::analyzePHINodes(const MachineFunction& Fn) {
for (MachineBasicBlock::const_iterator BBI = I->begin(), BBE = I->end();
BBI != BBE && BBI->isPHI(); ++BBI)
for (unsigned i = 1, e = BBI->getNumOperands(); i != e; i += 2)
PHIVarInfo[BBI->getOperand(i + 1).getMBB()->getNumber()]
.push_back(BBI->getOperand(i).getReg());
if (BBI->getOperand(i).readsReg())
PHIVarInfo[BBI->getOperand(i + 1).getMBB()->getNumber()]
.push_back(BBI->getOperand(i).getReg());
}
bool LiveVariables::VarInfo::isLiveIn(const MachineBasicBlock &MBB,