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Kill of TransferDeadFlag - Dead copies and subreg-to-reg instructions should

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just be turned into kills on the spot.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175688 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Lang Hames 2013-02-20 23:36:57 +00:00
parent 063d49f767
commit 100c93c850
1 changed files with 13 additions and 25 deletions
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38
lib/CodeGen/ExpandPostRAPseudos.cpp
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@ -49,8 +49,6 @@ private:
bool LowerSubregToReg(MachineInstr *MI);
bool LowerCopy(MachineInstr *MI);
void TransferDeadFlag(MachineInstr *MI, unsigned DstReg,
const TargetRegisterInfo *TRI);
void TransferImplicitDefs(MachineInstr *MI);
};
} // end anonymous namespace
@ -61,21 +59,6 @@ char &llvm::ExpandPostRAPseudosID = ExpandPostRA::ID;
INITIALIZE_PASS(ExpandPostRA, "postrapseudos",
"Post-RA pseudo instruction expansion pass", false, false)
/// TransferDeadFlag - MI is a pseudo-instruction with DstReg dead,
/// and the lowered replacement instructions immediately precede it.
/// Mark the replacement instructions with the dead flag.
void
ExpandPostRA::TransferDeadFlag(MachineInstr *MI, unsigned DstReg,
const TargetRegisterInfo *TRI) {
for (MachineBasicBlock::iterator MII =
prior(MachineBasicBlock::iterator(MI)); ; --MII) {
if (MII->addRegisterDead(DstReg, TRI))
break;
assert(MII != MI->getParent()->begin() &&
"copyPhysReg output doesn't reference destination register!");
}
}
/// TransferImplicitDefs - MI is a pseudo-instruction, and the lowered
/// replacement instructions immediately precede it. Copy any implicit-def
/// operands from MI to the replacement instruction.
@ -128,17 +111,17 @@ bool ExpandPostRA::LowerSubregToReg(MachineInstr *MI) {
}
DEBUG(dbgs() << "subreg: eliminated!");
} else {
if (MI->getOperand(0).isDead()) {
MI->setDesc(TII->get(TargetOpcode::KILL));
DEBUG(dbgs() << "subreg: replaced by: " << *MI);
return true;
}
TII->copyPhysReg(*MBB, MI, MI->getDebugLoc(), DstSubReg, InsReg,
MI->getOperand(2).isKill());
// Implicitly define DstReg for subsequent uses.
MachineBasicBlock::iterator CopyMI = MI;
--CopyMI;
CopyMI->addRegisterDefined(DstReg);
// Transfer the kill/dead flags, if needed.
if (MI->getOperand(0).isDead())
TransferDeadFlag(MI, DstSubReg, TRI);
DEBUG(dbgs() << "subreg: " << *CopyMI);
}
@ -151,11 +134,18 @@ bool ExpandPostRA::LowerCopy(MachineInstr *MI) {
MachineOperand &DstMO = MI->getOperand(0);
MachineOperand &SrcMO = MI->getOperand(1);
if (DstMO.isDead()) {
DEBUG(dbgs() << "dead copy: " << *MI);
MI->setDesc(TII->get(TargetOpcode::KILL));
DEBUG(dbgs() << "replaced by: " << *MI);
return true;
}
if (SrcMO.getReg() == DstMO.getReg()) {
DEBUG(dbgs() << "identity copy: " << *MI);
// No need to insert an identity copy instruction, but replace with a KILL
// if liveness is changed.
if (DstMO.isDead() || SrcMO.isUndef() || MI->getNumOperands() > 2) {
if (SrcMO.isUndef() || MI->getNumOperands() > 2) {
// We must make sure the super-register gets killed. Replace the
// instruction with KILL.
MI->setDesc(TII->get(TargetOpcode::KILL));
@ -171,8 +161,6 @@ bool ExpandPostRA::LowerCopy(MachineInstr *MI) {
TII->copyPhysReg(*MI->getParent(), MI, MI->getDebugLoc(),
DstMO.getReg(), SrcMO.getReg(), SrcMO.isKill());
if (DstMO.isDead())
TransferDeadFlag(MI, DstMO.getReg(), TRI);
if (MI->getNumOperands() > 2)
TransferImplicitDefs(MI);
DEBUG({