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Teach MachineLICM and MachineSink how to clear kill flags conservatively

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when they move instructions.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103737 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2010-05-13 20:34:42 +00:00
parent 1e5a6c46b8
commit e6cd757e68
4 changed files with 31 additions and 1 deletions
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4
include/llvm/CodeGen/MachineInstr.h
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@ -302,6 +302,10 @@ public:
/// reference if DefOpIdx is not null.
bool isRegTiedToDefOperand(unsigned UseOpIdx, unsigned *DefOpIdx = 0) const;
/// clearKillInfo - Clears kill flags on all operands.
///
void clearKillInfo();
/// copyKillDeadInfo - Copies kill / dead operand properties from MI.
///
void copyKillDeadInfo(const MachineInstr *MI);

10
lib/CodeGen/MachineInstr.cpp
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@ -938,6 +938,16 @@ isRegTiedToDefOperand(unsigned UseOpIdx, unsigned *DefOpIdx) const {
return true;
}
/// clearKillInfo - Clears kill flags on all operands.
///
void MachineInstr::clearKillInfo() {
for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
MachineOperand &MO = getOperand(i);
if (MO.isReg() && MO.isUse())
MO.setIsKill(false);
}
}
/// copyKillDeadInfo - Copies kill / dead operand properties from MI.
///
void MachineInstr::copyKillDeadInfo(const MachineInstr *MI) {

13
lib/CodeGen/MachineLICM.cpp
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@ -738,8 +738,10 @@ bool MachineLICM::EliminateCSE(MachineInstr *MI,
"Instructions with different phys regs are not identical!");
if (MO.isReg() && MO.isDef() &&
!TargetRegisterInfo::isPhysicalRegister(MO.getReg()))
!TargetRegisterInfo::isPhysicalRegister(MO.getReg())) {
RegInfo->replaceRegWith(MO.getReg(), Dup->getOperand(i).getReg());
RegInfo->clearKillFlags(Dup->getOperand(i).getReg());
}
}
MI->eraseFromParent();
++NumCSEed;
@ -784,6 +786,15 @@ void MachineLICM::Hoist(MachineInstr *MI) {
// Otherwise, splice the instruction to the preheader.
CurPreheader->splice(CurPreheader->getFirstTerminator(),MI->getParent(),MI);
// Clear the kill flags of any register this instruction defines,
// since they may need to be live throughout the entire loop
// rather than just live for part of it.
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI->getOperand(i);
if (MO.isReg() && MO.isDef() && !MO.isDead())
RegInfo->clearKillFlags(MO.getReg());
}
// Add to the CSE map.
if (CI != CSEMap.end())
CI->second.push_back(MI);

5
lib/CodeGen/MachineSink.cpp
View File

@ -314,5 +314,10 @@ bool MachineSinking::SinkInstruction(MachineInstr *MI, bool &SawStore) {
// Move the instruction.
SuccToSinkTo->splice(InsertPos, ParentBlock, MI,
++MachineBasicBlock::iterator(MI));
// Conservatively, clear any kill flags, since it's possible that
// they are no longer correct.
MI->clearKillInfo();
return true;
}