-/// disallowClobberPhysRegOnly - Unset the CanClobber bit of the specified
-/// stackslot register. The register is still available but is no longer
-/// allowed to be modifed.
-void AvailableSpills::disallowClobberPhysRegOnly(unsigned PhysReg) {
- std::multimap<unsigned, int>::iterator I =
- PhysRegsAvailable.lower_bound(PhysReg);
- while (I != PhysRegsAvailable.end() && I->first == PhysReg) {
- int SlotOrReMat = I->second;
- I++;
- assert((SpillSlotsOrReMatsAvailable[SlotOrReMat] >> 1) == PhysReg &&
- "Bidirectional map mismatch!");
- SpillSlotsOrReMatsAvailable[SlotOrReMat] &= ~1;
- DOUT << "PhysReg " << TRI->getName(PhysReg)
- << " copied, it is available for use but can no longer be modified\n";
- }
-}
-
-/// disallowClobberPhysReg - Unset the CanClobber bit of the specified
-/// stackslot register and its aliases. The register and its aliases may
-/// still available but is no longer allowed to be modifed.
-void AvailableSpills::disallowClobberPhysReg(unsigned PhysReg) {
- for (const unsigned *AS = TRI->getAliasSet(PhysReg); *AS; ++AS)
- disallowClobberPhysRegOnly(*AS);
- disallowClobberPhysRegOnly(PhysReg);
-}
-
-/// ClobberPhysRegOnly - This is called when the specified physreg changes
-/// value. We use this to invalidate any info about stuff we thing lives in it.
-void AvailableSpills::ClobberPhysRegOnly(unsigned PhysReg) {
- std::multimap<unsigned, int>::iterator I =
- PhysRegsAvailable.lower_bound(PhysReg);
- while (I != PhysRegsAvailable.end() && I->first == PhysReg) {
- int SlotOrReMat = I->second;
- PhysRegsAvailable.erase(I++);
- assert((SpillSlotsOrReMatsAvailable[SlotOrReMat] >> 1) == PhysReg &&
- "Bidirectional map mismatch!");
- SpillSlotsOrReMatsAvailable.erase(SlotOrReMat);
- DOUT << "PhysReg " << TRI->getName(PhysReg)
- << " clobbered, invalidating ";
- if (SlotOrReMat > VirtRegMap::MAX_STACK_SLOT)
- DOUT << "RM#" << SlotOrReMat-VirtRegMap::MAX_STACK_SLOT-1 << "\n";
- else
- DOUT << "SS#" << SlotOrReMat << "\n";
- }
-}
-
-/// ClobberPhysReg - This is called when the specified physreg changes
-/// value. We use this to invalidate any info about stuff we thing lives in
-/// it and any of its aliases.
-void AvailableSpills::ClobberPhysReg(unsigned PhysReg) {
- for (const unsigned *AS = TRI->getAliasSet(PhysReg); *AS; ++AS)
- ClobberPhysRegOnly(*AS);
- ClobberPhysRegOnly(PhysReg);
-}
-
-/// ModifyStackSlotOrReMat - This method is called when the value in a stack
-/// slot changes. This removes information about which register the previous
-/// value for this slot lives in (as the previous value is dead now).
-void AvailableSpills::ModifyStackSlotOrReMat(int SlotOrReMat) {
- std::map<int, unsigned>::iterator It =
- SpillSlotsOrReMatsAvailable.find(SlotOrReMat);
- if (It == SpillSlotsOrReMatsAvailable.end()) return;
- unsigned Reg = It->second >> 1;
- SpillSlotsOrReMatsAvailable.erase(It);
-
- // This register may hold the value of multiple stack slots, only remove this
- // stack slot from the set of values the register contains.
- std::multimap<unsigned, int>::iterator I = PhysRegsAvailable.lower_bound(Reg);
- for (; ; ++I) {
- assert(I != PhysRegsAvailable.end() && I->first == Reg &&
- "Map inverse broken!");
- if (I->second == SlotOrReMat) break;
- }
- PhysRegsAvailable.erase(I);
-}
-
-static void findSinglePredSuccessor(MachineBasicBlock *MBB,
- SmallVectorImpl<MachineBasicBlock *> &Succs) {
- for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(),
- SE = MBB->succ_end(); SI != SE; ++SI) {
- MachineBasicBlock *SuccMBB = *SI;
- if (SuccMBB->pred_size() == 1)
- Succs.push_back(SuccMBB);
- }
-}
-
-namespace {
- class AvailableSpills;
-
- /// LocalSpiller - This spiller does a simple pass over the machine basic
- /// block to attempt to keep spills in registers as much as possible for
- /// blocks that have low register pressure (the vreg may be spilled due to
- /// register pressure in other blocks).
- class VISIBILITY_HIDDEN LocalSpiller : public Spiller {
- MachineRegisterInfo *RegInfo;
- const TargetRegisterInfo *TRI;
- const TargetInstrInfo *TII;
- DenseMap<MachineInstr*, unsigned> DistanceMap;
- public:
- bool runOnMachineFunction(MachineFunction &MF, VirtRegMap &VRM) {
- RegInfo = &MF.getRegInfo();
- TRI = MF.getTarget().getRegisterInfo();
- TII = MF.getTarget().getInstrInfo();
- DOUT << "\n**** Local spiller rewriting function '"
- << MF.getFunction()->getName() << "':\n";
- DOUT << "**** Machine Instrs (NOTE! Does not include spills and reloads!)"
- " ****\n";
- DEBUG(MF.dump());
-
- // Spills - Keep track of which spilled values are available in physregs
- // so that we can choose to reuse the physregs instead of emitting
- // reloads. This is usually refreshed per basic block.
- AvailableSpills Spills(TRI, TII);
-
- // SingleEntrySuccs - Successor blocks which have a single predecessor.
- SmallVector<MachineBasicBlock*, 4> SinglePredSuccs;
- SmallPtrSet<MachineBasicBlock*,16> EarlyVisited;
-
- // Traverse the basic blocks depth first.
- MachineBasicBlock *Entry = MF.begin();
- SmallPtrSet<MachineBasicBlock*,16> Visited;
- for (df_ext_iterator<MachineBasicBlock*,
- SmallPtrSet<MachineBasicBlock*,16> >
- DFI = df_ext_begin(Entry, Visited), E = df_ext_end(Entry, Visited);
- DFI != E; ++DFI) {
- MachineBasicBlock *MBB = *DFI;
- if (!EarlyVisited.count(MBB))
- RewriteMBB(*MBB, VRM, Spills);
-
- // If this MBB is the only predecessor of a successor. Keep the
- // availability information and visit it next.
- do {
- // Keep visiting single predecessor successor as long as possible.
- SinglePredSuccs.clear();
- findSinglePredSuccessor(MBB, SinglePredSuccs);
- if (SinglePredSuccs.empty())
- MBB = 0;
- else {
- // FIXME: More than one successors, each of which has MBB has
- // the only predecessor.
- MBB = SinglePredSuccs[0];
- if (!Visited.count(MBB) && EarlyVisited.insert(MBB))
- RewriteMBB(*MBB, VRM, Spills);
- }
- } while (MBB);
-
- // Clear the availability info.
- Spills.clear();
- }
-
- DOUT << "**** Post Machine Instrs ****\n";
- DEBUG(MF.dump());
-
- // Mark unused spill slots.
- MachineFrameInfo *MFI = MF.getFrameInfo();
- int SS = VRM.getLowSpillSlot();
- if (SS != VirtRegMap::NO_STACK_SLOT)
- for (int e = VRM.getHighSpillSlot(); SS <= e; ++SS)
- if (!VRM.isSpillSlotUsed(SS)) {
- MFI->RemoveStackObject(SS);
- ++NumDSS;
- }
-
- return true;
- }
- private:
- void TransferDeadness(MachineBasicBlock *MBB, unsigned CurDist,
- unsigned Reg, BitVector &RegKills,
- std::vector<MachineOperand*> &KillOps);
- bool PrepForUnfoldOpti(MachineBasicBlock &MBB,
- MachineBasicBlock::iterator &MII,
- std::vector<MachineInstr*> &MaybeDeadStores,
- AvailableSpills &Spills, BitVector &RegKills,
- std::vector<MachineOperand*> &KillOps,
- VirtRegMap &VRM);
- bool CommuteToFoldReload(MachineBasicBlock &MBB,
- MachineBasicBlock::iterator &MII,
- unsigned VirtReg, unsigned SrcReg, int SS,
- BitVector &RegKills,
- std::vector<MachineOperand*> &KillOps,
- const TargetRegisterInfo *TRI,
- VirtRegMap &VRM);
- void SpillRegToStackSlot(MachineBasicBlock &MBB,
- MachineBasicBlock::iterator &MII,
- int Idx, unsigned PhysReg, int StackSlot,
- const TargetRegisterClass *RC,
- bool isAvailable, MachineInstr *&LastStore,
- AvailableSpills &Spills,
- SmallSet<MachineInstr*, 4> &ReMatDefs,
- BitVector &RegKills,
- std::vector<MachineOperand*> &KillOps,
- VirtRegMap &VRM);
- void RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM,
- AvailableSpills &Spills);
- };
-}
-
-/// InvalidateKills - MI is going to be deleted. If any of its operands are
-/// marked kill, then invalidate the information.
-static void InvalidateKills(MachineInstr &MI, BitVector &RegKills,
- std::vector<MachineOperand*> &KillOps,
- SmallVector<unsigned, 2> *KillRegs = NULL) {
- for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
- MachineOperand &MO = MI.getOperand(i);
- if (!MO.isReg() || !MO.isUse() || !MO.isKill())
- continue;
- unsigned Reg = MO.getReg();
- if (TargetRegisterInfo::isVirtualRegister(Reg))
- continue;
- if (KillRegs)
- KillRegs->push_back(Reg);
- assert(Reg < KillOps.size());
- if (KillOps[Reg] == &MO) {
- RegKills.reset(Reg);
- KillOps[Reg] = NULL;
- }
- }
-}
-
-/// InvalidateKill - A MI that defines the specified register is being deleted,
-/// invalidate the register kill information.
-static void InvalidateKill(unsigned Reg, BitVector &RegKills,
- std::vector<MachineOperand*> &KillOps) {
- if (RegKills[Reg]) {
- KillOps[Reg]->setIsKill(false);
- KillOps[Reg] = NULL;
- RegKills.reset(Reg);