/// of the de-ssa process. This replaces sources of REG_SEQUENCE as
/// sub-register references of the register defined by REG_SEQUENCE.
bool EliminateRegSequences();
+
public:
static char ID; // Pass identification, replacement for typeid
TwoAddressInstructionPass() : MachineFunctionPass(&ID) {}
if (!LastKill)
return false;
- bool isModRef = LastKill->modifiesRegister(Kill);
+ bool isModRef = LastKill->definesRegister(Kill);
NewKills.push_back(std::make_pair(std::make_pair(Kill, isModRef),
LastKill));
}
}
}
+static bool HasOtherRegSequenceUses(unsigned Reg, MachineInstr *RegSeq,
+ MachineRegisterInfo *MRI) {
+ for (MachineRegisterInfo::use_iterator UI = MRI->use_begin(Reg),
+ UE = MRI->use_end(); UI != UE; ++UI) {
+ MachineInstr *UseMI = &*UI;
+ if (UseMI != RegSeq && UseMI->isRegSequence())
+ return true;
+ }
+ return false;
+}
+
/// EliminateRegSequences - Eliminate REG_SEQUENCE instructions as part
/// of the de-ssa process. This replaces sources of REG_SEQUENCE as
/// sub-register references of the register defined by REG_SEQUENCE. e.g.
llvm_unreachable(0);
}
+ bool IsImpDef = true;
SmallVector<unsigned, 4> RealSrcs;
SmallSet<unsigned, 4> Seen;
for (unsigned i = 1, e = MI->getNumOperands(); i < e; i += 2) {
DefMI->eraseFromParent();
continue;
}
+ IsImpDef = false;
// Remember EXTRACT_SUBREG sources. These might be candidate for
// coalescing.
if (DefMI->isExtractSubreg())
RealSrcs.push_back(DefMI->getOperand(1).getReg());
- if (!Seen.insert(SrcReg) || MI->getParent() != DefMI->getParent()) {
+ if (!Seen.insert(SrcReg) ||
+ MI->getParent() != DefMI->getParent() ||
+ !MI->getOperand(i).isKill() ||
+ HasOtherRegSequenceUses(SrcReg, MI, MRI)) {
// REG_SEQUENCE cannot have duplicated operands, add a copy.
- // Also add an copy if the source if live-in the block. We don't want
+ // Also add an copy if the source is live-in the block. We don't want
// to end up with a partial-redef of a livein, e.g.
// BB0:
// reg1051:10<def> =
// BB2:
// reg1051:9<def> =
// LiveIntervalAnalysis won't like it.
+ //
+ // If the REG_SEQUENCE doesn't kill its source, keeping live variables
+ // correctly up to date becomes very difficult. Insert a copy.
+ //
const TargetRegisterClass *RC = MRI->getRegClass(SrcReg);
unsigned NewReg = MRI->createVirtualRegister(RC);
MachineBasicBlock::iterator InsertLoc = MI;
UpdateRegSequenceSrcs(SrcReg, DstReg, SubIdx, MRI);
}
- DEBUG(dbgs() << "Eliminated: " << *MI);
- MI->eraseFromParent();
+ if (IsImpDef) {
+ DEBUG(dbgs() << "Turned: " << *MI << " into an IMPLICIT_DEF");
+ MI->setDesc(TII->get(TargetOpcode::IMPLICIT_DEF));
+ for (int j = MI->getNumOperands() - 1, ee = 0; j > ee; --j)
+ MI->RemoveOperand(j);
+ } else {
+ DEBUG(dbgs() << "Eliminated: " << *MI);
+ MI->eraseFromParent();
+ }
// Try coalescing some EXTRACT_SUBREG instructions.
CoalesceExtSubRegs(RealSrcs, DstReg);