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Fix bug: Jello/2003-06-04-bzip2-bug.ll

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llvm-svn: 6624
This commit is contained in:
Chris Lattner 2003-06-05 17:15:04 +00:00
parent dc8209bab4
commit 060e5e326b
1 changed files with 21 additions and 23 deletions
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44
lib/CodeGen/PHIElimination.cpp
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@ -193,14 +193,16 @@ bool PNE::EliminatePHINodes(MachineFunction &MF, MachineBasicBlock &MBB) {
//
LiveVariables::VarInfo &InRegVI = LV->getVarInfo(SrcReg);
// Loop over all of the successors of the basic block, checking to
// see if the value is either live in the block, or if it is killed
// in the block.
// Loop over all of the successors of the basic block, checking to see
// if the value is either live in the block, or if it is killed in the
// block. Also check to see if this register is in use by another PHI
// node which has not yet been eliminated. If so, it will be killed
// at an appropriate point later.
//
bool ValueIsLive = false;
BasicBlock *BB = opBlock.getBasicBlock();
for (succ_iterator SI = succ_begin(BB), E = succ_end(BB);
SI != E; ++SI) {
SI != E && !ValueIsLive; ++SI) {
const std::pair<MachineBasicBlock*, unsigned> &
SuccInfo = LV->getBasicBlockInfo(*SI);
@ -219,32 +221,28 @@ bool PNE::EliminatePHINodes(MachineFunction &MF, MachineBasicBlock &MBB) {
ValueIsLive = true;
break;
}
// Is it used by any PHI instructions in this block?
if (ValueIsLive) break;
// Loop over all of the PHIs in this successor, checking to see if
// the register is being used...
for (MachineBasicBlock::iterator BBI = MBB->begin(), E=MBB->end();
BBI != E && (*BBI)->getOpcode() == TargetInstrInfo::PHI;
++BBI)
for (unsigned i = 1, e = (*BBI)->getNumOperands(); i < e; i += 2)
if ((*BBI)->getOperand(i).getReg() == SrcReg) {
ValueIsLive = true;
break;
}
}
// Okay, if we now know that the value is not live out of the block,
// we can add a kill marker to the copy we inserted saying that it
// kills the incoming value!
//
if (!ValueIsLive) {
// One more complication to worry about. There may actually be
// multiple PHI nodes using this value on this branch. If we aren't
// careful, the first PHI node will end up killing the value, not
// letting it get the to the copy for the final PHI node in the
// block. Therefore we have to check to see if there is already a
// kill in this block, and if so, extend the lifetime to our new
// copy.
//
for (unsigned i = 0, e = InRegVI.Kills.size(); i != e; ++i)
if (InRegVI.Kills[i].first == &opBlock) {
std::pair<LiveVariables::killed_iterator,
LiveVariables::killed_iterator> Range
= LV->killed_range(InRegVI.Kills[i].second);
LV->removeVirtualRegistersKilled(Range.first, Range.second);
break;
}
if (!ValueIsLive)
LV->addVirtualRegisterKilled(SrcReg, &opBlock, *(I-1));
}
}
}
}