mirror of
https://github.com/RPCS3/llvm-mirror.git
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1812351f99
llvm-svn: 48263
1635 lines
65 KiB
C++
1635 lines
65 KiB
C++
//===-- llvm/CodeGen/VirtRegMap.cpp - Virtual Register Map ----------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the VirtRegMap class.
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//
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// It also contains implementations of the the Spiller interface, which, given a
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// virtual register map and a machine function, eliminates all virtual
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// references by replacing them with physical register references - adding spill
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// code as necessary.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "spiller"
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#include "VirtRegMap.h"
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#include "llvm/Function.h"
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#include "llvm/CodeGen/MachineFrameInfo.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Target/TargetInstrInfo.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/ADT/BitVector.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/SmallSet.h"
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#include <algorithm>
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using namespace llvm;
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STATISTIC(NumSpills, "Number of register spills");
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STATISTIC(NumPSpills,"Number of physical register spills");
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STATISTIC(NumReMats, "Number of re-materialization");
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STATISTIC(NumDRM , "Number of re-materializable defs elided");
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STATISTIC(NumStores, "Number of stores added");
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STATISTIC(NumLoads , "Number of loads added");
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STATISTIC(NumReused, "Number of values reused");
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STATISTIC(NumDSE , "Number of dead stores elided");
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STATISTIC(NumDCE , "Number of copies elided");
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STATISTIC(NumDSS , "Number of dead spill slots removed");
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namespace {
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enum SpillerName { simple, local };
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static cl::opt<SpillerName>
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SpillerOpt("spiller",
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cl::desc("Spiller to use: (default: local)"),
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cl::Prefix,
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cl::values(clEnumVal(simple, " simple spiller"),
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clEnumVal(local, " local spiller"),
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clEnumValEnd),
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cl::init(local));
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}
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//===----------------------------------------------------------------------===//
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// VirtRegMap implementation
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//===----------------------------------------------------------------------===//
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VirtRegMap::VirtRegMap(MachineFunction &mf)
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: TII(*mf.getTarget().getInstrInfo()), MF(mf),
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Virt2PhysMap(NO_PHYS_REG), Virt2StackSlotMap(NO_STACK_SLOT),
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Virt2ReMatIdMap(NO_STACK_SLOT), Virt2SplitMap(0),
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Virt2SplitKillMap(0), ReMatMap(NULL), ReMatId(MAX_STACK_SLOT+1),
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LowSpillSlot(NO_STACK_SLOT), HighSpillSlot(NO_STACK_SLOT) {
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SpillSlotToUsesMap.resize(8);
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grow();
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}
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void VirtRegMap::grow() {
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unsigned LastVirtReg = MF.getRegInfo().getLastVirtReg();
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Virt2PhysMap.grow(LastVirtReg);
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Virt2StackSlotMap.grow(LastVirtReg);
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Virt2ReMatIdMap.grow(LastVirtReg);
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Virt2SplitMap.grow(LastVirtReg);
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Virt2SplitKillMap.grow(LastVirtReg);
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ReMatMap.grow(LastVirtReg);
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}
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int VirtRegMap::assignVirt2StackSlot(unsigned virtReg) {
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assert(TargetRegisterInfo::isVirtualRegister(virtReg));
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assert(Virt2StackSlotMap[virtReg] == NO_STACK_SLOT &&
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"attempt to assign stack slot to already spilled register");
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const TargetRegisterClass* RC = MF.getRegInfo().getRegClass(virtReg);
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int SS = MF.getFrameInfo()->CreateStackObject(RC->getSize(),
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RC->getAlignment());
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if (LowSpillSlot == NO_STACK_SLOT)
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LowSpillSlot = SS;
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if (HighSpillSlot == NO_STACK_SLOT || SS > HighSpillSlot)
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HighSpillSlot = SS;
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unsigned Idx = SS-LowSpillSlot;
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while (Idx >= SpillSlotToUsesMap.size())
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SpillSlotToUsesMap.resize(SpillSlotToUsesMap.size()*2);
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Virt2StackSlotMap[virtReg] = SS;
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++NumSpills;
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return SS;
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}
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void VirtRegMap::assignVirt2StackSlot(unsigned virtReg, int SS) {
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assert(TargetRegisterInfo::isVirtualRegister(virtReg));
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assert(Virt2StackSlotMap[virtReg] == NO_STACK_SLOT &&
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"attempt to assign stack slot to already spilled register");
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assert((SS >= 0 ||
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(SS >= MF.getFrameInfo()->getObjectIndexBegin())) &&
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"illegal fixed frame index");
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Virt2StackSlotMap[virtReg] = SS;
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}
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int VirtRegMap::assignVirtReMatId(unsigned virtReg) {
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assert(TargetRegisterInfo::isVirtualRegister(virtReg));
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assert(Virt2ReMatIdMap[virtReg] == NO_STACK_SLOT &&
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"attempt to assign re-mat id to already spilled register");
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Virt2ReMatIdMap[virtReg] = ReMatId;
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return ReMatId++;
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}
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void VirtRegMap::assignVirtReMatId(unsigned virtReg, int id) {
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assert(TargetRegisterInfo::isVirtualRegister(virtReg));
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assert(Virt2ReMatIdMap[virtReg] == NO_STACK_SLOT &&
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"attempt to assign re-mat id to already spilled register");
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Virt2ReMatIdMap[virtReg] = id;
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}
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int VirtRegMap::getEmergencySpillSlot(const TargetRegisterClass *RC) {
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std::map<const TargetRegisterClass*, int>::iterator I =
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EmergencySpillSlots.find(RC);
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if (I != EmergencySpillSlots.end())
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return I->second;
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int SS = MF.getFrameInfo()->CreateStackObject(RC->getSize(),
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RC->getAlignment());
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if (LowSpillSlot == NO_STACK_SLOT)
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LowSpillSlot = SS;
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if (HighSpillSlot == NO_STACK_SLOT || SS > HighSpillSlot)
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HighSpillSlot = SS;
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I->second = SS;
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return SS;
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}
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void VirtRegMap::addSpillSlotUse(int FI, MachineInstr *MI) {
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if (!MF.getFrameInfo()->isFixedObjectIndex(FI)) {
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assert(FI >= 0 && "Spill slot index should not be negative!");
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SpillSlotToUsesMap[FI-LowSpillSlot].insert(MI);
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}
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}
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void VirtRegMap::virtFolded(unsigned VirtReg, MachineInstr *OldMI,
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MachineInstr *NewMI, ModRef MRInfo) {
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// Move previous memory references folded to new instruction.
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MI2VirtMapTy::iterator IP = MI2VirtMap.lower_bound(NewMI);
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for (MI2VirtMapTy::iterator I = MI2VirtMap.lower_bound(OldMI),
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E = MI2VirtMap.end(); I != E && I->first == OldMI; ) {
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MI2VirtMap.insert(IP, std::make_pair(NewMI, I->second));
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MI2VirtMap.erase(I++);
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}
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// add new memory reference
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MI2VirtMap.insert(IP, std::make_pair(NewMI, std::make_pair(VirtReg, MRInfo)));
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}
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void VirtRegMap::virtFolded(unsigned VirtReg, MachineInstr *MI, ModRef MRInfo) {
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MI2VirtMapTy::iterator IP = MI2VirtMap.lower_bound(MI);
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MI2VirtMap.insert(IP, std::make_pair(MI, std::make_pair(VirtReg, MRInfo)));
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}
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void VirtRegMap::RemoveMachineInstrFromMaps(MachineInstr *MI) {
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for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
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MachineOperand &MO = MI->getOperand(i);
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if (!MO.isFrameIndex())
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continue;
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int FI = MO.getIndex();
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if (MF.getFrameInfo()->isFixedObjectIndex(FI))
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continue;
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SpillSlotToUsesMap[FI-LowSpillSlot].erase(MI);
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}
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MI2VirtMap.erase(MI);
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SpillPt2VirtMap.erase(MI);
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RestorePt2VirtMap.erase(MI);
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EmergencySpillMap.erase(MI);
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}
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void VirtRegMap::print(std::ostream &OS) const {
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const TargetRegisterInfo* TRI = MF.getTarget().getRegisterInfo();
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OS << "********** REGISTER MAP **********\n";
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for (unsigned i = TargetRegisterInfo::FirstVirtualRegister,
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e = MF.getRegInfo().getLastVirtReg(); i <= e; ++i) {
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if (Virt2PhysMap[i] != (unsigned)VirtRegMap::NO_PHYS_REG)
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OS << "[reg" << i << " -> " << TRI->getName(Virt2PhysMap[i])
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<< "]\n";
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}
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for (unsigned i = TargetRegisterInfo::FirstVirtualRegister,
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e = MF.getRegInfo().getLastVirtReg(); i <= e; ++i)
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if (Virt2StackSlotMap[i] != VirtRegMap::NO_STACK_SLOT)
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OS << "[reg" << i << " -> fi#" << Virt2StackSlotMap[i] << "]\n";
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OS << '\n';
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}
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void VirtRegMap::dump() const {
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print(DOUT);
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}
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//===----------------------------------------------------------------------===//
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// Simple Spiller Implementation
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//===----------------------------------------------------------------------===//
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Spiller::~Spiller() {}
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namespace {
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struct VISIBILITY_HIDDEN SimpleSpiller : public Spiller {
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bool runOnMachineFunction(MachineFunction& mf, VirtRegMap &VRM);
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};
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}
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bool SimpleSpiller::runOnMachineFunction(MachineFunction &MF, VirtRegMap &VRM) {
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DOUT << "********** REWRITE MACHINE CODE **********\n";
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DOUT << "********** Function: " << MF.getFunction()->getName() << '\n';
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const TargetMachine &TM = MF.getTarget();
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const TargetInstrInfo &TII = *TM.getInstrInfo();
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// LoadedRegs - Keep track of which vregs are loaded, so that we only load
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// each vreg once (in the case where a spilled vreg is used by multiple
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// operands). This is always smaller than the number of operands to the
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// current machine instr, so it should be small.
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std::vector<unsigned> LoadedRegs;
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for (MachineFunction::iterator MBBI = MF.begin(), E = MF.end();
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MBBI != E; ++MBBI) {
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DOUT << MBBI->getBasicBlock()->getName() << ":\n";
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MachineBasicBlock &MBB = *MBBI;
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for (MachineBasicBlock::iterator MII = MBB.begin(),
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E = MBB.end(); MII != E; ++MII) {
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MachineInstr &MI = *MII;
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for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
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MachineOperand &MO = MI.getOperand(i);
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if (MO.isRegister() && MO.getReg()) {
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if (TargetRegisterInfo::isVirtualRegister(MO.getReg())) {
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unsigned VirtReg = MO.getReg();
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unsigned PhysReg = VRM.getPhys(VirtReg);
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if (!VRM.isAssignedReg(VirtReg)) {
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int StackSlot = VRM.getStackSlot(VirtReg);
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const TargetRegisterClass* RC =
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MF.getRegInfo().getRegClass(VirtReg);
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if (MO.isUse() &&
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std::find(LoadedRegs.begin(), LoadedRegs.end(), VirtReg)
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== LoadedRegs.end()) {
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TII.loadRegFromStackSlot(MBB, &MI, PhysReg, StackSlot, RC);
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MachineInstr *LoadMI = prior(MII);
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VRM.addSpillSlotUse(StackSlot, LoadMI);
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LoadedRegs.push_back(VirtReg);
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++NumLoads;
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DOUT << '\t' << *LoadMI;
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}
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if (MO.isDef()) {
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TII.storeRegToStackSlot(MBB, next(MII), PhysReg, true,
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StackSlot, RC);
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MachineInstr *StoreMI = next(MII);
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VRM.addSpillSlotUse(StackSlot, StoreMI);
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++NumStores;
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}
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}
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MF.getRegInfo().setPhysRegUsed(PhysReg);
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MI.getOperand(i).setReg(PhysReg);
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} else {
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MF.getRegInfo().setPhysRegUsed(MO.getReg());
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}
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}
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}
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DOUT << '\t' << MI;
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LoadedRegs.clear();
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}
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}
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return true;
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}
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//===----------------------------------------------------------------------===//
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// Local Spiller Implementation
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//===----------------------------------------------------------------------===//
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namespace {
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class AvailableSpills;
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/// LocalSpiller - This spiller does a simple pass over the machine basic
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/// block to attempt to keep spills in registers as much as possible for
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/// blocks that have low register pressure (the vreg may be spilled due to
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/// register pressure in other blocks).
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class VISIBILITY_HIDDEN LocalSpiller : public Spiller {
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MachineRegisterInfo *RegInfo;
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const TargetRegisterInfo *TRI;
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const TargetInstrInfo *TII;
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public:
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bool runOnMachineFunction(MachineFunction &MF, VirtRegMap &VRM) {
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RegInfo = &MF.getRegInfo();
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TRI = MF.getTarget().getRegisterInfo();
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TII = MF.getTarget().getInstrInfo();
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DOUT << "\n**** Local spiller rewriting function '"
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<< MF.getFunction()->getName() << "':\n";
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DOUT << "**** Machine Instrs (NOTE! Does not include spills and reloads!)"
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" ****\n";
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DEBUG(MF.dump());
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for (MachineFunction::iterator MBB = MF.begin(), E = MF.end();
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MBB != E; ++MBB)
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RewriteMBB(*MBB, VRM);
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// Mark unused spill slots.
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MachineFrameInfo *MFI = MF.getFrameInfo();
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int SS = VRM.getLowSpillSlot();
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if (SS != VirtRegMap::NO_STACK_SLOT)
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for (int e = VRM.getHighSpillSlot(); SS <= e; ++SS)
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if (!VRM.isSpillSlotUsed(SS)) {
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MFI->RemoveStackObject(SS);
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++NumDSS;
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}
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DOUT << "**** Post Machine Instrs ****\n";
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DEBUG(MF.dump());
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return true;
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}
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private:
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bool PrepForUnfoldOpti(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator &MII,
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std::vector<MachineInstr*> &MaybeDeadStores,
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AvailableSpills &Spills, BitVector &RegKills,
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std::vector<MachineOperand*> &KillOps,
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VirtRegMap &VRM);
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void SpillRegToStackSlot(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator &MII,
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int Idx, unsigned PhysReg, int StackSlot,
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const TargetRegisterClass *RC,
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bool isAvailable, MachineInstr *&LastStore,
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AvailableSpills &Spills,
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SmallSet<MachineInstr*, 4> &ReMatDefs,
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BitVector &RegKills,
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std::vector<MachineOperand*> &KillOps,
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VirtRegMap &VRM);
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void RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM);
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};
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}
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/// AvailableSpills - As the local spiller is scanning and rewriting an MBB from
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/// top down, keep track of which spills slots or remat are available in each
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/// register.
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///
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/// Note that not all physregs are created equal here. In particular, some
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/// physregs are reloads that we are allowed to clobber or ignore at any time.
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/// Other physregs are values that the register allocated program is using that
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/// we cannot CHANGE, but we can read if we like. We keep track of this on a
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/// per-stack-slot / remat id basis as the low bit in the value of the
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/// SpillSlotsAvailable entries. The predicate 'canClobberPhysReg()' checks
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/// this bit and addAvailable sets it if.
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namespace {
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class VISIBILITY_HIDDEN AvailableSpills {
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const TargetRegisterInfo *TRI;
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const TargetInstrInfo *TII;
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// SpillSlotsOrReMatsAvailable - This map keeps track of all of the spilled
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// or remat'ed virtual register values that are still available, due to being
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// loaded or stored to, but not invalidated yet.
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std::map<int, unsigned> SpillSlotsOrReMatsAvailable;
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// PhysRegsAvailable - This is the inverse of SpillSlotsOrReMatsAvailable,
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// indicating which stack slot values are currently held by a physreg. This
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// is used to invalidate entries in SpillSlotsOrReMatsAvailable when a
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// physreg is modified.
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std::multimap<unsigned, int> PhysRegsAvailable;
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void disallowClobberPhysRegOnly(unsigned PhysReg);
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void ClobberPhysRegOnly(unsigned PhysReg);
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public:
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AvailableSpills(const TargetRegisterInfo *tri, const TargetInstrInfo *tii)
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: TRI(tri), TII(tii) {
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}
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const TargetRegisterInfo *getRegInfo() const { return TRI; }
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/// getSpillSlotOrReMatPhysReg - If the specified stack slot or remat is
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/// available in a physical register, return that PhysReg, otherwise
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/// return 0.
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unsigned getSpillSlotOrReMatPhysReg(int Slot) const {
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std::map<int, unsigned>::const_iterator I =
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SpillSlotsOrReMatsAvailable.find(Slot);
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if (I != SpillSlotsOrReMatsAvailable.end()) {
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return I->second >> 1; // Remove the CanClobber bit.
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}
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return 0;
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}
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/// addAvailable - Mark that the specified stack slot / remat is available in
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/// the specified physreg. If CanClobber is true, the physreg can be modified
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/// at any time without changing the semantics of the program.
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void addAvailable(int SlotOrReMat, MachineInstr *MI, unsigned Reg,
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bool CanClobber = true) {
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// If this stack slot is thought to be available in some other physreg,
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// remove its record.
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ModifyStackSlotOrReMat(SlotOrReMat);
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PhysRegsAvailable.insert(std::make_pair(Reg, SlotOrReMat));
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SpillSlotsOrReMatsAvailable[SlotOrReMat]= (Reg << 1) | (unsigned)CanClobber;
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if (SlotOrReMat > VirtRegMap::MAX_STACK_SLOT)
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DOUT << "Remembering RM#" << SlotOrReMat-VirtRegMap::MAX_STACK_SLOT-1;
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else
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DOUT << "Remembering SS#" << SlotOrReMat;
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DOUT << " in physreg " << TRI->getName(Reg) << "\n";
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}
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/// canClobberPhysReg - Return true if the spiller is allowed to change the
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/// value of the specified stackslot register if it desires. The specified
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/// stack slot must be available in a physreg for this query to make sense.
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bool canClobberPhysReg(int SlotOrReMat) const {
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assert(SpillSlotsOrReMatsAvailable.count(SlotOrReMat) &&
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"Value not available!");
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return SpillSlotsOrReMatsAvailable.find(SlotOrReMat)->second & 1;
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}
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/// disallowClobberPhysReg - Unset the CanClobber bit of the specified
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/// stackslot register. The register is still available but is no longer
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/// allowed to be modifed.
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void disallowClobberPhysReg(unsigned PhysReg);
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/// ClobberPhysReg - This is called when the specified physreg changes
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/// value. We use this to invalidate any info about stuff that lives in
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/// it and any of its aliases.
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void ClobberPhysReg(unsigned PhysReg);
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/// ModifyStackSlotOrReMat - This method is called when the value in a stack
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/// slot changes. This removes information about which register the previous
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/// value for this slot lives in (as the previous value is dead now).
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void ModifyStackSlotOrReMat(int SlotOrReMat);
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};
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}
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/// disallowClobberPhysRegOnly - Unset the CanClobber bit of the specified
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/// stackslot register. The register is still available but is no longer
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/// 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);
|
|
}
|
|
|
|
|
|
|
|
/// 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.isRegister() || !MO.isUse() || !MO.isKill())
|
|
continue;
|
|
unsigned Reg = MO.getReg();
|
|
if (KillRegs)
|
|
KillRegs->push_back(Reg);
|
|
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);
|
|
}
|
|
}
|
|
|
|
/// InvalidateRegDef - If the def operand of the specified def MI is now dead
|
|
/// (since it's spill instruction is removed), mark it isDead. Also checks if
|
|
/// the def MI has other definition operands that are not dead. Returns it by
|
|
/// reference.
|
|
static bool InvalidateRegDef(MachineBasicBlock::iterator I,
|
|
MachineInstr &NewDef, unsigned Reg,
|
|
bool &HasLiveDef) {
|
|
// Due to remat, it's possible this reg isn't being reused. That is,
|
|
// the def of this reg (by prev MI) is now dead.
|
|
MachineInstr *DefMI = I;
|
|
MachineOperand *DefOp = NULL;
|
|
for (unsigned i = 0, e = DefMI->getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = DefMI->getOperand(i);
|
|
if (MO.isRegister() && MO.isDef()) {
|
|
if (MO.getReg() == Reg)
|
|
DefOp = &MO;
|
|
else if (!MO.isDead())
|
|
HasLiveDef = true;
|
|
}
|
|
}
|
|
if (!DefOp)
|
|
return false;
|
|
|
|
bool FoundUse = false, Done = false;
|
|
MachineBasicBlock::iterator E = NewDef;
|
|
++I; ++E;
|
|
for (; !Done && I != E; ++I) {
|
|
MachineInstr *NMI = I;
|
|
for (unsigned j = 0, ee = NMI->getNumOperands(); j != ee; ++j) {
|
|
MachineOperand &MO = NMI->getOperand(j);
|
|
if (!MO.isRegister() || MO.getReg() != Reg)
|
|
continue;
|
|
if (MO.isUse())
|
|
FoundUse = true;
|
|
Done = true; // Stop after scanning all the operands of this MI.
|
|
}
|
|
}
|
|
if (!FoundUse) {
|
|
// Def is dead!
|
|
DefOp->setIsDead();
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/// UpdateKills - Track and update kill info. If a MI reads a register that is
|
|
/// marked kill, then it must be due to register reuse. Transfer the kill info
|
|
/// over.
|
|
static void UpdateKills(MachineInstr &MI, BitVector &RegKills,
|
|
std::vector<MachineOperand*> &KillOps) {
|
|
const TargetInstrDesc &TID = MI.getDesc();
|
|
for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = MI.getOperand(i);
|
|
if (!MO.isRegister() || !MO.isUse())
|
|
continue;
|
|
unsigned Reg = MO.getReg();
|
|
if (Reg == 0)
|
|
continue;
|
|
|
|
if (RegKills[Reg]) {
|
|
// That can't be right. Register is killed but not re-defined and it's
|
|
// being reused. Let's fix that.
|
|
KillOps[Reg]->setIsKill(false);
|
|
KillOps[Reg] = NULL;
|
|
RegKills.reset(Reg);
|
|
if (i < TID.getNumOperands() &&
|
|
TID.getOperandConstraint(i, TOI::TIED_TO) == -1)
|
|
// Unless it's a two-address operand, this is the new kill.
|
|
MO.setIsKill();
|
|
}
|
|
if (MO.isKill()) {
|
|
RegKills.set(Reg);
|
|
KillOps[Reg] = &MO;
|
|
}
|
|
}
|
|
|
|
for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
|
|
const MachineOperand &MO = MI.getOperand(i);
|
|
if (!MO.isRegister() || !MO.isDef())
|
|
continue;
|
|
unsigned Reg = MO.getReg();
|
|
RegKills.reset(Reg);
|
|
KillOps[Reg] = NULL;
|
|
}
|
|
}
|
|
|
|
/// ReMaterialize - Re-materialize definition for Reg targetting DestReg.
|
|
///
|
|
static void ReMaterialize(MachineBasicBlock &MBB,
|
|
MachineBasicBlock::iterator &MII,
|
|
unsigned DestReg, unsigned Reg,
|
|
const TargetRegisterInfo *TRI,
|
|
VirtRegMap &VRM) {
|
|
TRI->reMaterialize(MBB, MII, DestReg, VRM.getReMaterializedMI(Reg));
|
|
MachineInstr *NewMI = prior(MII);
|
|
for (unsigned i = 0, e = NewMI->getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = NewMI->getOperand(i);
|
|
if (!MO.isRegister() || MO.getReg() == 0)
|
|
continue;
|
|
unsigned VirtReg = MO.getReg();
|
|
if (TargetRegisterInfo::isPhysicalRegister(VirtReg))
|
|
continue;
|
|
assert(MO.isUse());
|
|
unsigned SubIdx = MO.getSubReg();
|
|
unsigned Phys = VRM.getPhys(VirtReg);
|
|
assert(Phys);
|
|
unsigned RReg = SubIdx ? TRI->getSubReg(Phys, SubIdx) : Phys;
|
|
MO.setReg(RReg);
|
|
}
|
|
++NumReMats;
|
|
}
|
|
|
|
|
|
// ReusedOp - For each reused operand, we keep track of a bit of information, in
|
|
// case we need to rollback upon processing a new operand. See comments below.
|
|
namespace {
|
|
struct ReusedOp {
|
|
// The MachineInstr operand that reused an available value.
|
|
unsigned Operand;
|
|
|
|
// StackSlotOrReMat - The spill slot or remat id of the value being reused.
|
|
unsigned StackSlotOrReMat;
|
|
|
|
// PhysRegReused - The physical register the value was available in.
|
|
unsigned PhysRegReused;
|
|
|
|
// AssignedPhysReg - The physreg that was assigned for use by the reload.
|
|
unsigned AssignedPhysReg;
|
|
|
|
// VirtReg - The virtual register itself.
|
|
unsigned VirtReg;
|
|
|
|
ReusedOp(unsigned o, unsigned ss, unsigned prr, unsigned apr,
|
|
unsigned vreg)
|
|
: Operand(o), StackSlotOrReMat(ss), PhysRegReused(prr),
|
|
AssignedPhysReg(apr), VirtReg(vreg) {}
|
|
};
|
|
|
|
/// ReuseInfo - This maintains a collection of ReuseOp's for each operand that
|
|
/// is reused instead of reloaded.
|
|
class VISIBILITY_HIDDEN ReuseInfo {
|
|
MachineInstr &MI;
|
|
std::vector<ReusedOp> Reuses;
|
|
BitVector PhysRegsClobbered;
|
|
public:
|
|
ReuseInfo(MachineInstr &mi, const TargetRegisterInfo *tri) : MI(mi) {
|
|
PhysRegsClobbered.resize(tri->getNumRegs());
|
|
}
|
|
|
|
bool hasReuses() const {
|
|
return !Reuses.empty();
|
|
}
|
|
|
|
/// addReuse - If we choose to reuse a virtual register that is already
|
|
/// available instead of reloading it, remember that we did so.
|
|
void addReuse(unsigned OpNo, unsigned StackSlotOrReMat,
|
|
unsigned PhysRegReused, unsigned AssignedPhysReg,
|
|
unsigned VirtReg) {
|
|
// If the reload is to the assigned register anyway, no undo will be
|
|
// required.
|
|
if (PhysRegReused == AssignedPhysReg) return;
|
|
|
|
// Otherwise, remember this.
|
|
Reuses.push_back(ReusedOp(OpNo, StackSlotOrReMat, PhysRegReused,
|
|
AssignedPhysReg, VirtReg));
|
|
}
|
|
|
|
void markClobbered(unsigned PhysReg) {
|
|
PhysRegsClobbered.set(PhysReg);
|
|
}
|
|
|
|
bool isClobbered(unsigned PhysReg) const {
|
|
return PhysRegsClobbered.test(PhysReg);
|
|
}
|
|
|
|
/// GetRegForReload - We are about to emit a reload into PhysReg. If there
|
|
/// is some other operand that is using the specified register, either pick
|
|
/// a new register to use, or evict the previous reload and use this reg.
|
|
unsigned GetRegForReload(unsigned PhysReg, MachineInstr *MI,
|
|
AvailableSpills &Spills,
|
|
std::vector<MachineInstr*> &MaybeDeadStores,
|
|
SmallSet<unsigned, 8> &Rejected,
|
|
BitVector &RegKills,
|
|
std::vector<MachineOperand*> &KillOps,
|
|
VirtRegMap &VRM) {
|
|
const TargetInstrInfo* TII = MI->getParent()->getParent()->getTarget()
|
|
.getInstrInfo();
|
|
|
|
if (Reuses.empty()) return PhysReg; // This is most often empty.
|
|
|
|
for (unsigned ro = 0, e = Reuses.size(); ro != e; ++ro) {
|
|
ReusedOp &Op = Reuses[ro];
|
|
// If we find some other reuse that was supposed to use this register
|
|
// exactly for its reload, we can change this reload to use ITS reload
|
|
// register. That is, unless its reload register has already been
|
|
// considered and subsequently rejected because it has also been reused
|
|
// by another operand.
|
|
if (Op.PhysRegReused == PhysReg &&
|
|
Rejected.count(Op.AssignedPhysReg) == 0) {
|
|
// Yup, use the reload register that we didn't use before.
|
|
unsigned NewReg = Op.AssignedPhysReg;
|
|
Rejected.insert(PhysReg);
|
|
return GetRegForReload(NewReg, MI, Spills, MaybeDeadStores, Rejected,
|
|
RegKills, KillOps, VRM);
|
|
} else {
|
|
// Otherwise, we might also have a problem if a previously reused
|
|
// value aliases the new register. If so, codegen the previous reload
|
|
// and use this one.
|
|
unsigned PRRU = Op.PhysRegReused;
|
|
const TargetRegisterInfo *TRI = Spills.getRegInfo();
|
|
if (TRI->areAliases(PRRU, PhysReg)) {
|
|
// Okay, we found out that an alias of a reused register
|
|
// was used. This isn't good because it means we have
|
|
// to undo a previous reuse.
|
|
MachineBasicBlock *MBB = MI->getParent();
|
|
const TargetRegisterClass *AliasRC =
|
|
MBB->getParent()->getRegInfo().getRegClass(Op.VirtReg);
|
|
|
|
// Copy Op out of the vector and remove it, we're going to insert an
|
|
// explicit load for it.
|
|
ReusedOp NewOp = Op;
|
|
Reuses.erase(Reuses.begin()+ro);
|
|
|
|
// Ok, we're going to try to reload the assigned physreg into the
|
|
// slot that we were supposed to in the first place. However, that
|
|
// register could hold a reuse. Check to see if it conflicts or
|
|
// would prefer us to use a different register.
|
|
unsigned NewPhysReg = GetRegForReload(NewOp.AssignedPhysReg,
|
|
MI, Spills, MaybeDeadStores,
|
|
Rejected, RegKills, KillOps, VRM);
|
|
|
|
MachineBasicBlock::iterator MII = MI;
|
|
if (NewOp.StackSlotOrReMat > VirtRegMap::MAX_STACK_SLOT) {
|
|
ReMaterialize(*MBB, MII, NewPhysReg, NewOp.VirtReg, TRI, VRM);
|
|
} else {
|
|
TII->loadRegFromStackSlot(*MBB, MII, NewPhysReg,
|
|
NewOp.StackSlotOrReMat, AliasRC);
|
|
MachineInstr *LoadMI = prior(MII);
|
|
VRM.addSpillSlotUse(NewOp.StackSlotOrReMat, LoadMI);
|
|
// Any stores to this stack slot are not dead anymore.
|
|
MaybeDeadStores[NewOp.StackSlotOrReMat] = NULL;
|
|
++NumLoads;
|
|
}
|
|
Spills.ClobberPhysReg(NewPhysReg);
|
|
Spills.ClobberPhysReg(NewOp.PhysRegReused);
|
|
|
|
MI->getOperand(NewOp.Operand).setReg(NewPhysReg);
|
|
|
|
Spills.addAvailable(NewOp.StackSlotOrReMat, MI, NewPhysReg);
|
|
--MII;
|
|
UpdateKills(*MII, RegKills, KillOps);
|
|
DOUT << '\t' << *MII;
|
|
|
|
DOUT << "Reuse undone!\n";
|
|
--NumReused;
|
|
|
|
// Finally, PhysReg is now available, go ahead and use it.
|
|
return PhysReg;
|
|
}
|
|
}
|
|
}
|
|
return PhysReg;
|
|
}
|
|
|
|
/// GetRegForReload - Helper for the above GetRegForReload(). Add a
|
|
/// 'Rejected' set to remember which registers have been considered and
|
|
/// rejected for the reload. This avoids infinite looping in case like
|
|
/// this:
|
|
/// t1 := op t2, t3
|
|
/// t2 <- assigned r0 for use by the reload but ended up reuse r1
|
|
/// t3 <- assigned r1 for use by the reload but ended up reuse r0
|
|
/// t1 <- desires r1
|
|
/// sees r1 is taken by t2, tries t2's reload register r0
|
|
/// sees r0 is taken by t3, tries t3's reload register r1
|
|
/// sees r1 is taken by t2, tries t2's reload register r0 ...
|
|
unsigned GetRegForReload(unsigned PhysReg, MachineInstr *MI,
|
|
AvailableSpills &Spills,
|
|
std::vector<MachineInstr*> &MaybeDeadStores,
|
|
BitVector &RegKills,
|
|
std::vector<MachineOperand*> &KillOps,
|
|
VirtRegMap &VRM) {
|
|
SmallSet<unsigned, 8> Rejected;
|
|
return GetRegForReload(PhysReg, MI, Spills, MaybeDeadStores, Rejected,
|
|
RegKills, KillOps, VRM);
|
|
}
|
|
};
|
|
}
|
|
|
|
/// PrepForUnfoldOpti - Turn a store folding instruction into a load folding
|
|
/// instruction. e.g.
|
|
/// xorl %edi, %eax
|
|
/// movl %eax, -32(%ebp)
|
|
/// movl -36(%ebp), %eax
|
|
/// orl %eax, -32(%ebp)
|
|
/// ==>
|
|
/// xorl %edi, %eax
|
|
/// orl -36(%ebp), %eax
|
|
/// mov %eax, -32(%ebp)
|
|
/// This enables unfolding optimization for a subsequent instruction which will
|
|
/// also eliminate the newly introduced store instruction.
|
|
bool LocalSpiller::PrepForUnfoldOpti(MachineBasicBlock &MBB,
|
|
MachineBasicBlock::iterator &MII,
|
|
std::vector<MachineInstr*> &MaybeDeadStores,
|
|
AvailableSpills &Spills,
|
|
BitVector &RegKills,
|
|
std::vector<MachineOperand*> &KillOps,
|
|
VirtRegMap &VRM) {
|
|
MachineFunction &MF = *MBB.getParent();
|
|
MachineInstr &MI = *MII;
|
|
unsigned UnfoldedOpc = 0;
|
|
unsigned UnfoldPR = 0;
|
|
unsigned UnfoldVR = 0;
|
|
int FoldedSS = VirtRegMap::NO_STACK_SLOT;
|
|
VirtRegMap::MI2VirtMapTy::const_iterator I, End;
|
|
for (tie(I, End) = VRM.getFoldedVirts(&MI); I != End; ++I) {
|
|
// Only transform a MI that folds a single register.
|
|
if (UnfoldedOpc)
|
|
return false;
|
|
UnfoldVR = I->second.first;
|
|
VirtRegMap::ModRef MR = I->second.second;
|
|
if (VRM.isAssignedReg(UnfoldVR))
|
|
continue;
|
|
// If this reference is not a use, any previous store is now dead.
|
|
// Otherwise, the store to this stack slot is not dead anymore.
|
|
FoldedSS = VRM.getStackSlot(UnfoldVR);
|
|
MachineInstr* DeadStore = MaybeDeadStores[FoldedSS];
|
|
if (DeadStore && (MR & VirtRegMap::isModRef)) {
|
|
unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(FoldedSS);
|
|
if (!PhysReg || !DeadStore->readsRegister(PhysReg))
|
|
continue;
|
|
UnfoldPR = PhysReg;
|
|
UnfoldedOpc = TII->getOpcodeAfterMemoryUnfold(MI.getOpcode(),
|
|
false, true);
|
|
}
|
|
}
|
|
|
|
if (!UnfoldedOpc)
|
|
return false;
|
|
|
|
for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = MI.getOperand(i);
|
|
if (!MO.isRegister() || MO.getReg() == 0 || !MO.isUse())
|
|
continue;
|
|
unsigned VirtReg = MO.getReg();
|
|
if (TargetRegisterInfo::isPhysicalRegister(VirtReg) || MO.getSubReg())
|
|
continue;
|
|
if (VRM.isAssignedReg(VirtReg)) {
|
|
unsigned PhysReg = VRM.getPhys(VirtReg);
|
|
if (PhysReg && TRI->regsOverlap(PhysReg, UnfoldPR))
|
|
return false;
|
|
} else if (VRM.isReMaterialized(VirtReg))
|
|
continue;
|
|
int SS = VRM.getStackSlot(VirtReg);
|
|
unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SS);
|
|
if (PhysReg) {
|
|
if (TRI->regsOverlap(PhysReg, UnfoldPR))
|
|
return false;
|
|
continue;
|
|
}
|
|
PhysReg = VRM.getPhys(VirtReg);
|
|
if (!TRI->regsOverlap(PhysReg, UnfoldPR))
|
|
continue;
|
|
|
|
// Ok, we'll need to reload the value into a register which makes
|
|
// it impossible to perform the store unfolding optimization later.
|
|
// Let's see if it is possible to fold the load if the store is
|
|
// unfolded. This allows us to perform the store unfolding
|
|
// optimization.
|
|
SmallVector<MachineInstr*, 4> NewMIs;
|
|
if (TII->unfoldMemoryOperand(MF, &MI, UnfoldVR, false, false, NewMIs)) {
|
|
assert(NewMIs.size() == 1);
|
|
MachineInstr *NewMI = NewMIs.back();
|
|
NewMIs.clear();
|
|
int Idx = NewMI->findRegisterUseOperandIdx(VirtReg, false);
|
|
assert(Idx != -1);
|
|
SmallVector<unsigned, 2> Ops;
|
|
Ops.push_back(Idx);
|
|
MachineInstr *FoldedMI = TII->foldMemoryOperand(MF, NewMI, Ops, SS);
|
|
if (FoldedMI) {
|
|
VRM.addSpillSlotUse(SS, FoldedMI);
|
|
if (!VRM.hasPhys(UnfoldVR))
|
|
VRM.assignVirt2Phys(UnfoldVR, UnfoldPR);
|
|
VRM.virtFolded(VirtReg, FoldedMI, VirtRegMap::isRef);
|
|
MII = MBB.insert(MII, FoldedMI);
|
|
VRM.RemoveMachineInstrFromMaps(&MI);
|
|
MBB.erase(&MI);
|
|
return true;
|
|
}
|
|
delete NewMI;
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/// findSuperReg - Find the SubReg's super-register of given register class
|
|
/// where its SubIdx sub-register is SubReg.
|
|
static unsigned findSuperReg(const TargetRegisterClass *RC, unsigned SubReg,
|
|
unsigned SubIdx, const TargetRegisterInfo *TRI) {
|
|
for (TargetRegisterClass::iterator I = RC->begin(), E = RC->end();
|
|
I != E; ++I) {
|
|
unsigned Reg = *I;
|
|
if (TRI->getSubReg(Reg, SubIdx) == SubReg)
|
|
return Reg;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/// SpillRegToStackSlot - Spill a register to a specified stack slot. Check if
|
|
/// the last store to the same slot is now dead. If so, remove the last store.
|
|
void LocalSpiller::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) {
|
|
TII->storeRegToStackSlot(MBB, next(MII), PhysReg, true, StackSlot, RC);
|
|
MachineInstr *StoreMI = next(MII);
|
|
VRM.addSpillSlotUse(StackSlot, StoreMI);
|
|
DOUT << "Store:\t" << *StoreMI;
|
|
|
|
// If there is a dead store to this stack slot, nuke it now.
|
|
if (LastStore) {
|
|
DOUT << "Removed dead store:\t" << *LastStore;
|
|
++NumDSE;
|
|
SmallVector<unsigned, 2> KillRegs;
|
|
InvalidateKills(*LastStore, RegKills, KillOps, &KillRegs);
|
|
MachineBasicBlock::iterator PrevMII = LastStore;
|
|
bool CheckDef = PrevMII != MBB.begin();
|
|
if (CheckDef)
|
|
--PrevMII;
|
|
VRM.RemoveMachineInstrFromMaps(LastStore);
|
|
MBB.erase(LastStore);
|
|
if (CheckDef) {
|
|
// Look at defs of killed registers on the store. Mark the defs
|
|
// as dead since the store has been deleted and they aren't
|
|
// being reused.
|
|
for (unsigned j = 0, ee = KillRegs.size(); j != ee; ++j) {
|
|
bool HasOtherDef = false;
|
|
if (InvalidateRegDef(PrevMII, *MII, KillRegs[j], HasOtherDef)) {
|
|
MachineInstr *DeadDef = PrevMII;
|
|
if (ReMatDefs.count(DeadDef) && !HasOtherDef) {
|
|
// FIXME: This assumes a remat def does not have side
|
|
// effects.
|
|
VRM.RemoveMachineInstrFromMaps(DeadDef);
|
|
MBB.erase(DeadDef);
|
|
++NumDRM;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
LastStore = next(MII);
|
|
|
|
// If the stack slot value was previously available in some other
|
|
// register, change it now. Otherwise, make the register available,
|
|
// in PhysReg.
|
|
Spills.ModifyStackSlotOrReMat(StackSlot);
|
|
Spills.ClobberPhysReg(PhysReg);
|
|
Spills.addAvailable(StackSlot, LastStore, PhysReg, isAvailable);
|
|
++NumStores;
|
|
}
|
|
|
|
/// rewriteMBB - Keep track of which spills are available even after the
|
|
/// register allocator is done with them. If possible, avid reloading vregs.
|
|
void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
|
|
DOUT << MBB.getBasicBlock()->getName() << ":\n";
|
|
|
|
MachineFunction &MF = *MBB.getParent();
|
|
|
|
// Spills - Keep track of which spilled values are available in physregs so
|
|
// that we can choose to reuse the physregs instead of emitting reloads.
|
|
AvailableSpills Spills(TRI, TII);
|
|
|
|
// MaybeDeadStores - When we need to write a value back into a stack slot,
|
|
// keep track of the inserted store. If the stack slot value is never read
|
|
// (because the value was used from some available register, for example), and
|
|
// subsequently stored to, the original store is dead. This map keeps track
|
|
// of inserted stores that are not used. If we see a subsequent store to the
|
|
// same stack slot, the original store is deleted.
|
|
std::vector<MachineInstr*> MaybeDeadStores;
|
|
MaybeDeadStores.resize(MF.getFrameInfo()->getObjectIndexEnd(), NULL);
|
|
|
|
// ReMatDefs - These are rematerializable def MIs which are not deleted.
|
|
SmallSet<MachineInstr*, 4> ReMatDefs;
|
|
|
|
// Keep track of kill information.
|
|
BitVector RegKills(TRI->getNumRegs());
|
|
std::vector<MachineOperand*> KillOps;
|
|
KillOps.resize(TRI->getNumRegs(), NULL);
|
|
|
|
for (MachineBasicBlock::iterator MII = MBB.begin(), E = MBB.end();
|
|
MII != E; ) {
|
|
MachineBasicBlock::iterator NextMII = MII; ++NextMII;
|
|
|
|
VirtRegMap::MI2VirtMapTy::const_iterator I, End;
|
|
bool Erased = false;
|
|
bool BackTracked = false;
|
|
if (PrepForUnfoldOpti(MBB, MII,
|
|
MaybeDeadStores, Spills, RegKills, KillOps, VRM))
|
|
NextMII = next(MII);
|
|
|
|
MachineInstr &MI = *MII;
|
|
const TargetInstrDesc &TID = MI.getDesc();
|
|
|
|
if (VRM.hasEmergencySpills(&MI)) {
|
|
// Spill physical register(s) in the rare case the allocator has run out
|
|
// of registers to allocate.
|
|
SmallSet<int, 4> UsedSS;
|
|
std::vector<unsigned> &EmSpills = VRM.getEmergencySpills(&MI);
|
|
for (unsigned i = 0, e = EmSpills.size(); i != e; ++i) {
|
|
unsigned PhysReg = EmSpills[i];
|
|
const TargetRegisterClass *RC =
|
|
TRI->getPhysicalRegisterRegClass(PhysReg);
|
|
assert(RC && "Unable to determine register class!");
|
|
int SS = VRM.getEmergencySpillSlot(RC);
|
|
if (UsedSS.count(SS))
|
|
assert(0 && "Need to spill more than one physical registers!");
|
|
UsedSS.insert(SS);
|
|
TII->storeRegToStackSlot(MBB, MII, PhysReg, true, SS, RC);
|
|
MachineInstr *StoreMI = prior(MII);
|
|
VRM.addSpillSlotUse(SS, StoreMI);
|
|
TII->loadRegFromStackSlot(MBB, next(MII), PhysReg, SS, RC);
|
|
MachineInstr *LoadMI = next(MII);
|
|
VRM.addSpillSlotUse(SS, LoadMI);
|
|
++NumPSpills;
|
|
}
|
|
NextMII = next(MII);
|
|
}
|
|
|
|
// Insert restores here if asked to.
|
|
if (VRM.isRestorePt(&MI)) {
|
|
std::vector<unsigned> &RestoreRegs = VRM.getRestorePtRestores(&MI);
|
|
for (unsigned i = 0, e = RestoreRegs.size(); i != e; ++i) {
|
|
unsigned VirtReg = RestoreRegs[e-i-1]; // Reverse order.
|
|
if (!VRM.getPreSplitReg(VirtReg))
|
|
continue; // Split interval spilled again.
|
|
unsigned Phys = VRM.getPhys(VirtReg);
|
|
RegInfo->setPhysRegUsed(Phys);
|
|
if (VRM.isReMaterialized(VirtReg)) {
|
|
ReMaterialize(MBB, MII, Phys, VirtReg, TRI, VRM);
|
|
} else {
|
|
const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
|
|
int SS = VRM.getStackSlot(VirtReg);
|
|
TII->loadRegFromStackSlot(MBB, &MI, Phys, SS, RC);
|
|
MachineInstr *LoadMI = prior(MII);
|
|
VRM.addSpillSlotUse(SS, LoadMI);
|
|
++NumLoads;
|
|
}
|
|
// This invalidates Phys.
|
|
Spills.ClobberPhysReg(Phys);
|
|
UpdateKills(*prior(MII), RegKills, KillOps);
|
|
DOUT << '\t' << *prior(MII);
|
|
}
|
|
}
|
|
|
|
// Insert spills here if asked to.
|
|
if (VRM.isSpillPt(&MI)) {
|
|
std::vector<std::pair<unsigned,bool> > &SpillRegs =
|
|
VRM.getSpillPtSpills(&MI);
|
|
for (unsigned i = 0, e = SpillRegs.size(); i != e; ++i) {
|
|
unsigned VirtReg = SpillRegs[i].first;
|
|
bool isKill = SpillRegs[i].second;
|
|
if (!VRM.getPreSplitReg(VirtReg))
|
|
continue; // Split interval spilled again.
|
|
const TargetRegisterClass *RC = RegInfo->getRegClass(VirtReg);
|
|
unsigned Phys = VRM.getPhys(VirtReg);
|
|
int StackSlot = VRM.getStackSlot(VirtReg);
|
|
TII->storeRegToStackSlot(MBB, next(MII), Phys, isKill, StackSlot, RC);
|
|
MachineInstr *StoreMI = next(MII);
|
|
VRM.addSpillSlotUse(StackSlot, StoreMI);
|
|
DOUT << "Store:\t" << *StoreMI;
|
|
VRM.virtFolded(VirtReg, StoreMI, VirtRegMap::isMod);
|
|
}
|
|
NextMII = next(MII);
|
|
}
|
|
|
|
/// ReusedOperands - Keep track of operand reuse in case we need to undo
|
|
/// reuse.
|
|
ReuseInfo ReusedOperands(MI, TRI);
|
|
SmallVector<unsigned, 4> VirtUseOps;
|
|
for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = MI.getOperand(i);
|
|
if (!MO.isRegister() || MO.getReg() == 0)
|
|
continue; // Ignore non-register operands.
|
|
|
|
unsigned VirtReg = MO.getReg();
|
|
if (TargetRegisterInfo::isPhysicalRegister(VirtReg)) {
|
|
// Ignore physregs for spilling, but remember that it is used by this
|
|
// function.
|
|
RegInfo->setPhysRegUsed(VirtReg);
|
|
continue;
|
|
}
|
|
|
|
// We want to process implicit virtual register uses first.
|
|
if (MO.isImplicit())
|
|
VirtUseOps.insert(VirtUseOps.begin(), i);
|
|
else
|
|
VirtUseOps.push_back(i);
|
|
}
|
|
|
|
// Process all of the spilled uses and all non spilled reg references.
|
|
for (unsigned j = 0, e = VirtUseOps.size(); j != e; ++j) {
|
|
unsigned i = VirtUseOps[j];
|
|
MachineOperand &MO = MI.getOperand(i);
|
|
unsigned VirtReg = MO.getReg();
|
|
assert(TargetRegisterInfo::isVirtualRegister(VirtReg) &&
|
|
"Not a virtual register?");
|
|
|
|
unsigned SubIdx = MO.getSubReg();
|
|
if (VRM.isAssignedReg(VirtReg)) {
|
|
// This virtual register was assigned a physreg!
|
|
unsigned Phys = VRM.getPhys(VirtReg);
|
|
RegInfo->setPhysRegUsed(Phys);
|
|
if (MO.isDef())
|
|
ReusedOperands.markClobbered(Phys);
|
|
unsigned RReg = SubIdx ? TRI->getSubReg(Phys, SubIdx) : Phys;
|
|
MI.getOperand(i).setReg(RReg);
|
|
continue;
|
|
}
|
|
|
|
// This virtual register is now known to be a spilled value.
|
|
if (!MO.isUse())
|
|
continue; // Handle defs in the loop below (handle use&def here though)
|
|
|
|
bool DoReMat = VRM.isReMaterialized(VirtReg);
|
|
int SSorRMId = DoReMat
|
|
? VRM.getReMatId(VirtReg) : VRM.getStackSlot(VirtReg);
|
|
int ReuseSlot = SSorRMId;
|
|
|
|
// Check to see if this stack slot is available.
|
|
unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SSorRMId);
|
|
|
|
// If this is a sub-register use, make sure the reuse register is in the
|
|
// right register class. For example, for x86 not all of the 32-bit
|
|
// registers have accessible sub-registers.
|
|
// Similarly so for EXTRACT_SUBREG. Consider this:
|
|
// EDI = op
|
|
// MOV32_mr fi#1, EDI
|
|
// ...
|
|
// = EXTRACT_SUBREG fi#1
|
|
// fi#1 is available in EDI, but it cannot be reused because it's not in
|
|
// the right register file.
|
|
if (PhysReg &&
|
|
(SubIdx || MI.getOpcode() == TargetInstrInfo::EXTRACT_SUBREG)) {
|
|
const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
|
|
if (!RC->contains(PhysReg))
|
|
PhysReg = 0;
|
|
}
|
|
|
|
if (PhysReg) {
|
|
// This spilled operand might be part of a two-address operand. If this
|
|
// is the case, then changing it will necessarily require changing the
|
|
// def part of the instruction as well. However, in some cases, we
|
|
// aren't allowed to modify the reused register. If none of these cases
|
|
// apply, reuse it.
|
|
bool CanReuse = true;
|
|
int ti = TID.getOperandConstraint(i, TOI::TIED_TO);
|
|
if (ti != -1 &&
|
|
MI.getOperand(ti).isRegister() &&
|
|
MI.getOperand(ti).getReg() == VirtReg) {
|
|
// Okay, we have a two address operand. We can reuse this physreg as
|
|
// long as we are allowed to clobber the value and there isn't an
|
|
// earlier def that has already clobbered the physreg.
|
|
CanReuse = Spills.canClobberPhysReg(ReuseSlot) &&
|
|
!ReusedOperands.isClobbered(PhysReg);
|
|
}
|
|
|
|
if (CanReuse) {
|
|
// If this stack slot value is already available, reuse it!
|
|
if (ReuseSlot > VirtRegMap::MAX_STACK_SLOT)
|
|
DOUT << "Reusing RM#" << ReuseSlot-VirtRegMap::MAX_STACK_SLOT-1;
|
|
else
|
|
DOUT << "Reusing SS#" << ReuseSlot;
|
|
DOUT << " from physreg "
|
|
<< TRI->getName(PhysReg) << " for vreg"
|
|
<< VirtReg <<" instead of reloading into physreg "
|
|
<< TRI->getName(VRM.getPhys(VirtReg)) << "\n";
|
|
unsigned RReg = SubIdx ? TRI->getSubReg(PhysReg, SubIdx) : PhysReg;
|
|
MI.getOperand(i).setReg(RReg);
|
|
|
|
// The only technical detail we have is that we don't know that
|
|
// PhysReg won't be clobbered by a reloaded stack slot that occurs
|
|
// later in the instruction. In particular, consider 'op V1, V2'.
|
|
// If V1 is available in physreg R0, we would choose to reuse it
|
|
// here, instead of reloading it into the register the allocator
|
|
// indicated (say R1). However, V2 might have to be reloaded
|
|
// later, and it might indicate that it needs to live in R0. When
|
|
// this occurs, we need to have information available that
|
|
// indicates it is safe to use R1 for the reload instead of R0.
|
|
//
|
|
// To further complicate matters, we might conflict with an alias,
|
|
// or R0 and R1 might not be compatible with each other. In this
|
|
// case, we actually insert a reload for V1 in R1, ensuring that
|
|
// we can get at R0 or its alias.
|
|
ReusedOperands.addReuse(i, ReuseSlot, PhysReg,
|
|
VRM.getPhys(VirtReg), VirtReg);
|
|
if (ti != -1)
|
|
// Only mark it clobbered if this is a use&def operand.
|
|
ReusedOperands.markClobbered(PhysReg);
|
|
++NumReused;
|
|
|
|
if (MI.getOperand(i).isKill() &&
|
|
ReuseSlot <= VirtRegMap::MAX_STACK_SLOT) {
|
|
// This was the last use and the spilled value is still available
|
|
// for reuse. That means the spill was unnecessary!
|
|
MachineInstr* DeadStore = MaybeDeadStores[ReuseSlot];
|
|
if (DeadStore) {
|
|
DOUT << "Removed dead store:\t" << *DeadStore;
|
|
InvalidateKills(*DeadStore, RegKills, KillOps);
|
|
VRM.RemoveMachineInstrFromMaps(DeadStore);
|
|
MBB.erase(DeadStore);
|
|
MaybeDeadStores[ReuseSlot] = NULL;
|
|
++NumDSE;
|
|
}
|
|
}
|
|
continue;
|
|
} // CanReuse
|
|
|
|
// Otherwise we have a situation where we have a two-address instruction
|
|
// whose mod/ref operand needs to be reloaded. This reload is already
|
|
// available in some register "PhysReg", but if we used PhysReg as the
|
|
// operand to our 2-addr instruction, the instruction would modify
|
|
// PhysReg. This isn't cool if something later uses PhysReg and expects
|
|
// to get its initial value.
|
|
//
|
|
// To avoid this problem, and to avoid doing a load right after a store,
|
|
// we emit a copy from PhysReg into the designated register for this
|
|
// operand.
|
|
unsigned DesignatedReg = VRM.getPhys(VirtReg);
|
|
assert(DesignatedReg && "Must map virtreg to physreg!");
|
|
|
|
// Note that, if we reused a register for a previous operand, the
|
|
// register we want to reload into might not actually be
|
|
// available. If this occurs, use the register indicated by the
|
|
// reuser.
|
|
if (ReusedOperands.hasReuses())
|
|
DesignatedReg = ReusedOperands.GetRegForReload(DesignatedReg, &MI,
|
|
Spills, MaybeDeadStores, RegKills, KillOps, VRM);
|
|
|
|
// If the mapped designated register is actually the physreg we have
|
|
// incoming, we don't need to inserted a dead copy.
|
|
if (DesignatedReg == PhysReg) {
|
|
// If this stack slot value is already available, reuse it!
|
|
if (ReuseSlot > VirtRegMap::MAX_STACK_SLOT)
|
|
DOUT << "Reusing RM#" << ReuseSlot-VirtRegMap::MAX_STACK_SLOT-1;
|
|
else
|
|
DOUT << "Reusing SS#" << ReuseSlot;
|
|
DOUT << " from physreg " << TRI->getName(PhysReg)
|
|
<< " for vreg" << VirtReg
|
|
<< " instead of reloading into same physreg.\n";
|
|
unsigned RReg = SubIdx ? TRI->getSubReg(PhysReg, SubIdx) : PhysReg;
|
|
MI.getOperand(i).setReg(RReg);
|
|
ReusedOperands.markClobbered(RReg);
|
|
++NumReused;
|
|
continue;
|
|
}
|
|
|
|
const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
|
|
RegInfo->setPhysRegUsed(DesignatedReg);
|
|
ReusedOperands.markClobbered(DesignatedReg);
|
|
TII->copyRegToReg(MBB, &MI, DesignatedReg, PhysReg, RC, RC);
|
|
|
|
MachineInstr *CopyMI = prior(MII);
|
|
UpdateKills(*CopyMI, RegKills, KillOps);
|
|
|
|
// This invalidates DesignatedReg.
|
|
Spills.ClobberPhysReg(DesignatedReg);
|
|
|
|
Spills.addAvailable(ReuseSlot, &MI, DesignatedReg);
|
|
unsigned RReg =
|
|
SubIdx ? TRI->getSubReg(DesignatedReg, SubIdx) : DesignatedReg;
|
|
MI.getOperand(i).setReg(RReg);
|
|
DOUT << '\t' << *prior(MII);
|
|
++NumReused;
|
|
continue;
|
|
} // if (PhysReg)
|
|
|
|
// Otherwise, reload it and remember that we have it.
|
|
PhysReg = VRM.getPhys(VirtReg);
|
|
assert(PhysReg && "Must map virtreg to physreg!");
|
|
|
|
// Note that, if we reused a register for a previous operand, the
|
|
// register we want to reload into might not actually be
|
|
// available. If this occurs, use the register indicated by the
|
|
// reuser.
|
|
if (ReusedOperands.hasReuses())
|
|
PhysReg = ReusedOperands.GetRegForReload(PhysReg, &MI,
|
|
Spills, MaybeDeadStores, RegKills, KillOps, VRM);
|
|
|
|
RegInfo->setPhysRegUsed(PhysReg);
|
|
ReusedOperands.markClobbered(PhysReg);
|
|
if (DoReMat) {
|
|
ReMaterialize(MBB, MII, PhysReg, VirtReg, TRI, VRM);
|
|
} else {
|
|
const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
|
|
TII->loadRegFromStackSlot(MBB, &MI, PhysReg, SSorRMId, RC);
|
|
MachineInstr *LoadMI = prior(MII);
|
|
VRM.addSpillSlotUse(SSorRMId, LoadMI);
|
|
++NumLoads;
|
|
}
|
|
// This invalidates PhysReg.
|
|
Spills.ClobberPhysReg(PhysReg);
|
|
|
|
// Any stores to this stack slot are not dead anymore.
|
|
if (!DoReMat)
|
|
MaybeDeadStores[SSorRMId] = NULL;
|
|
Spills.addAvailable(SSorRMId, &MI, PhysReg);
|
|
// Assumes this is the last use. IsKill will be unset if reg is reused
|
|
// unless it's a two-address operand.
|
|
if (TID.getOperandConstraint(i, TOI::TIED_TO) == -1)
|
|
MI.getOperand(i).setIsKill();
|
|
unsigned RReg = SubIdx ? TRI->getSubReg(PhysReg, SubIdx) : PhysReg;
|
|
MI.getOperand(i).setReg(RReg);
|
|
UpdateKills(*prior(MII), RegKills, KillOps);
|
|
DOUT << '\t' << *prior(MII);
|
|
}
|
|
|
|
DOUT << '\t' << MI;
|
|
|
|
|
|
// If we have folded references to memory operands, make sure we clear all
|
|
// physical registers that may contain the value of the spilled virtual
|
|
// register
|
|
SmallSet<int, 2> FoldedSS;
|
|
for (tie(I, End) = VRM.getFoldedVirts(&MI); I != End; ++I) {
|
|
unsigned VirtReg = I->second.first;
|
|
VirtRegMap::ModRef MR = I->second.second;
|
|
DOUT << "Folded vreg: " << VirtReg << " MR: " << MR;
|
|
|
|
int SS = VRM.getStackSlot(VirtReg);
|
|
if (SS == VirtRegMap::NO_STACK_SLOT)
|
|
continue;
|
|
FoldedSS.insert(SS);
|
|
DOUT << " - StackSlot: " << SS << "\n";
|
|
|
|
// If this folded instruction is just a use, check to see if it's a
|
|
// straight load from the virt reg slot.
|
|
if ((MR & VirtRegMap::isRef) && !(MR & VirtRegMap::isMod)) {
|
|
int FrameIdx;
|
|
unsigned DestReg = TII->isLoadFromStackSlot(&MI, FrameIdx);
|
|
if (DestReg && FrameIdx == SS) {
|
|
// If this spill slot is available, turn it into a copy (or nothing)
|
|
// instead of leaving it as a load!
|
|
if (unsigned InReg = Spills.getSpillSlotOrReMatPhysReg(SS)) {
|
|
DOUT << "Promoted Load To Copy: " << MI;
|
|
if (DestReg != InReg) {
|
|
const TargetRegisterClass *RC = RegInfo->getRegClass(VirtReg);
|
|
TII->copyRegToReg(MBB, &MI, DestReg, InReg, RC, RC);
|
|
// Revisit the copy so we make sure to notice the effects of the
|
|
// operation on the destreg (either needing to RA it if it's
|
|
// virtual or needing to clobber any values if it's physical).
|
|
NextMII = &MI;
|
|
--NextMII; // backtrack to the copy.
|
|
BackTracked = true;
|
|
} else {
|
|
DOUT << "Removing now-noop copy: " << MI;
|
|
// Unset last kill since it's being reused.
|
|
InvalidateKill(InReg, RegKills, KillOps);
|
|
}
|
|
|
|
VRM.RemoveMachineInstrFromMaps(&MI);
|
|
MBB.erase(&MI);
|
|
Erased = true;
|
|
goto ProcessNextInst;
|
|
}
|
|
} else {
|
|
unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SS);
|
|
SmallVector<MachineInstr*, 4> NewMIs;
|
|
if (PhysReg &&
|
|
TII->unfoldMemoryOperand(MF, &MI, PhysReg, false, false, NewMIs)) {
|
|
MBB.insert(MII, NewMIs[0]);
|
|
VRM.RemoveMachineInstrFromMaps(&MI);
|
|
MBB.erase(&MI);
|
|
Erased = true;
|
|
--NextMII; // backtrack to the unfolded instruction.
|
|
BackTracked = true;
|
|
goto ProcessNextInst;
|
|
}
|
|
}
|
|
}
|
|
|
|
// If this reference is not a use, any previous store is now dead.
|
|
// Otherwise, the store to this stack slot is not dead anymore.
|
|
MachineInstr* DeadStore = MaybeDeadStores[SS];
|
|
if (DeadStore) {
|
|
bool isDead = !(MR & VirtRegMap::isRef);
|
|
MachineInstr *NewStore = NULL;
|
|
if (MR & VirtRegMap::isModRef) {
|
|
unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SS);
|
|
SmallVector<MachineInstr*, 4> NewMIs;
|
|
// We can reuse this physreg as long as we are allowed to clobber
|
|
// the value and there isn't an earlier def that has already clobbered
|
|
// the physreg.
|
|
if (PhysReg &&
|
|
!TII->isStoreToStackSlot(&MI, SS) && // Not profitable!
|
|
DeadStore->killsRegister(PhysReg) &&
|
|
TII->unfoldMemoryOperand(MF, &MI, PhysReg, false, true, NewMIs)) {
|
|
MBB.insert(MII, NewMIs[0]);
|
|
NewStore = NewMIs[1];
|
|
MBB.insert(MII, NewStore);
|
|
VRM.addSpillSlotUse(SS, NewStore);
|
|
VRM.RemoveMachineInstrFromMaps(&MI);
|
|
MBB.erase(&MI);
|
|
Erased = true;
|
|
--NextMII;
|
|
--NextMII; // backtrack to the unfolded instruction.
|
|
BackTracked = true;
|
|
isDead = true;
|
|
}
|
|
}
|
|
|
|
if (isDead) { // Previous store is dead.
|
|
// If we get here, the store is dead, nuke it now.
|
|
DOUT << "Removed dead store:\t" << *DeadStore;
|
|
InvalidateKills(*DeadStore, RegKills, KillOps);
|
|
VRM.RemoveMachineInstrFromMaps(DeadStore);
|
|
MBB.erase(DeadStore);
|
|
if (!NewStore)
|
|
++NumDSE;
|
|
}
|
|
|
|
MaybeDeadStores[SS] = NULL;
|
|
if (NewStore) {
|
|
// Treat this store as a spill merged into a copy. That makes the
|
|
// stack slot value available.
|
|
VRM.virtFolded(VirtReg, NewStore, VirtRegMap::isMod);
|
|
goto ProcessNextInst;
|
|
}
|
|
}
|
|
|
|
// If the spill slot value is available, and this is a new definition of
|
|
// the value, the value is not available anymore.
|
|
if (MR & VirtRegMap::isMod) {
|
|
// Notice that the value in this stack slot has been modified.
|
|
Spills.ModifyStackSlotOrReMat(SS);
|
|
|
|
// If this is *just* a mod of the value, check to see if this is just a
|
|
// store to the spill slot (i.e. the spill got merged into the copy). If
|
|
// so, realize that the vreg is available now, and add the store to the
|
|
// MaybeDeadStore info.
|
|
int StackSlot;
|
|
if (!(MR & VirtRegMap::isRef)) {
|
|
if (unsigned SrcReg = TII->isStoreToStackSlot(&MI, StackSlot)) {
|
|
assert(TargetRegisterInfo::isPhysicalRegister(SrcReg) &&
|
|
"Src hasn't been allocated yet?");
|
|
// Okay, this is certainly a store of SrcReg to [StackSlot]. Mark
|
|
// this as a potentially dead store in case there is a subsequent
|
|
// store into the stack slot without a read from it.
|
|
MaybeDeadStores[StackSlot] = &MI;
|
|
|
|
// If the stack slot value was previously available in some other
|
|
// register, change it now. Otherwise, make the register available,
|
|
// in PhysReg.
|
|
Spills.addAvailable(StackSlot, &MI, SrcReg, false/*don't clobber*/);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Process all of the spilled defs.
|
|
for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = MI.getOperand(i);
|
|
if (!(MO.isRegister() && MO.getReg() && MO.isDef()))
|
|
continue;
|
|
|
|
unsigned VirtReg = MO.getReg();
|
|
if (!TargetRegisterInfo::isVirtualRegister(VirtReg)) {
|
|
// Check to see if this is a noop copy. If so, eliminate the
|
|
// instruction before considering the dest reg to be changed.
|
|
unsigned Src, Dst;
|
|
if (TII->isMoveInstr(MI, Src, Dst) && Src == Dst) {
|
|
++NumDCE;
|
|
DOUT << "Removing now-noop copy: " << MI;
|
|
VRM.RemoveMachineInstrFromMaps(&MI);
|
|
MBB.erase(&MI);
|
|
Erased = true;
|
|
Spills.disallowClobberPhysReg(VirtReg);
|
|
goto ProcessNextInst;
|
|
}
|
|
|
|
// If it's not a no-op copy, it clobbers the value in the destreg.
|
|
Spills.ClobberPhysReg(VirtReg);
|
|
ReusedOperands.markClobbered(VirtReg);
|
|
|
|
// Check to see if this instruction is a load from a stack slot into
|
|
// a register. If so, this provides the stack slot value in the reg.
|
|
int FrameIdx;
|
|
if (unsigned DestReg = TII->isLoadFromStackSlot(&MI, FrameIdx)) {
|
|
assert(DestReg == VirtReg && "Unknown load situation!");
|
|
|
|
// If it is a folded reference, then it's not safe to clobber.
|
|
bool Folded = FoldedSS.count(FrameIdx);
|
|
// Otherwise, if it wasn't available, remember that it is now!
|
|
Spills.addAvailable(FrameIdx, &MI, DestReg, !Folded);
|
|
goto ProcessNextInst;
|
|
}
|
|
|
|
continue;
|
|
}
|
|
|
|
unsigned SubIdx = MO.getSubReg();
|
|
bool DoReMat = VRM.isReMaterialized(VirtReg);
|
|
if (DoReMat)
|
|
ReMatDefs.insert(&MI);
|
|
|
|
// The only vregs left are stack slot definitions.
|
|
int StackSlot = VRM.getStackSlot(VirtReg);
|
|
const TargetRegisterClass *RC = RegInfo->getRegClass(VirtReg);
|
|
|
|
// If this def is part of a two-address operand, make sure to execute
|
|
// the store from the correct physical register.
|
|
unsigned PhysReg;
|
|
int TiedOp = MI.getDesc().findTiedToSrcOperand(i);
|
|
if (TiedOp != -1) {
|
|
PhysReg = MI.getOperand(TiedOp).getReg();
|
|
if (SubIdx) {
|
|
unsigned SuperReg = findSuperReg(RC, PhysReg, SubIdx, TRI);
|
|
assert(SuperReg && TRI->getSubReg(SuperReg, SubIdx) == PhysReg &&
|
|
"Can't find corresponding super-register!");
|
|
PhysReg = SuperReg;
|
|
}
|
|
} else {
|
|
PhysReg = VRM.getPhys(VirtReg);
|
|
if (ReusedOperands.isClobbered(PhysReg)) {
|
|
// Another def has taken the assigned physreg. It must have been a
|
|
// use&def which got it due to reuse. Undo the reuse!
|
|
PhysReg = ReusedOperands.GetRegForReload(PhysReg, &MI,
|
|
Spills, MaybeDeadStores, RegKills, KillOps, VRM);
|
|
}
|
|
}
|
|
|
|
RegInfo->setPhysRegUsed(PhysReg);
|
|
unsigned RReg = SubIdx ? TRI->getSubReg(PhysReg, SubIdx) : PhysReg;
|
|
ReusedOperands.markClobbered(RReg);
|
|
MI.getOperand(i).setReg(RReg);
|
|
|
|
if (!MO.isDead()) {
|
|
MachineInstr *&LastStore = MaybeDeadStores[StackSlot];
|
|
SpillRegToStackSlot(MBB, MII, -1, PhysReg, StackSlot, RC, true,
|
|
LastStore, Spills, ReMatDefs, RegKills, KillOps, VRM);
|
|
NextMII = next(MII);
|
|
|
|
// Check to see if this is a noop copy. If so, eliminate the
|
|
// instruction before considering the dest reg to be changed.
|
|
{
|
|
unsigned Src, Dst;
|
|
if (TII->isMoveInstr(MI, Src, Dst) && Src == Dst) {
|
|
++NumDCE;
|
|
DOUT << "Removing now-noop copy: " << MI;
|
|
VRM.RemoveMachineInstrFromMaps(&MI);
|
|
MBB.erase(&MI);
|
|
Erased = true;
|
|
UpdateKills(*LastStore, RegKills, KillOps);
|
|
goto ProcessNextInst;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
ProcessNextInst:
|
|
if (!Erased && !BackTracked) {
|
|
for (MachineBasicBlock::iterator II = MI; II != NextMII; ++II)
|
|
UpdateKills(*II, RegKills, KillOps);
|
|
}
|
|
MII = NextMII;
|
|
}
|
|
}
|
|
|
|
llvm::Spiller* llvm::createSpiller() {
|
|
switch (SpillerOpt) {
|
|
default: assert(0 && "Unreachable!");
|
|
case local:
|
|
return new LocalSpiller();
|
|
case simple:
|
|
return new SimpleSpiller();
|
|
}
|
|
}
|