1 //===-- llvm/CodeGen/VirtRegMap.cpp - Virtual Register Map ----------------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the VirtRegMap class.
12 // It also contains implementations of the the Spiller interface, which, given a
13 // virtual register map and a machine function, eliminates all virtual
14 // references by replacing them with physical register references - adding spill
17 //===----------------------------------------------------------------------===//
19 #define DEBUG_TYPE "spiller"
20 #include "VirtRegMap.h"
21 #include "llvm/Function.h"
22 #include "llvm/CodeGen/MachineFrameInfo.h"
23 #include "llvm/CodeGen/MachineFunction.h"
24 #include "llvm/CodeGen/SSARegMap.h"
25 #include "llvm/Target/TargetMachine.h"
26 #include "llvm/Target/TargetInstrInfo.h"
27 #include "llvm/Support/CommandLine.h"
28 #include "llvm/Support/Debug.h"
29 #include "llvm/ADT/Statistic.h"
30 #include "llvm/ADT/STLExtras.h"
34 Statistic<> NumSpills("spiller", "Number of register spills");
35 Statistic<> NumStores("spiller", "Number of stores added");
36 Statistic<> NumLoads ("spiller", "Number of loads added");
38 enum SpillerName { simple, local };
42 cl::desc("Spiller to use: (default: local)"),
44 cl::values(clEnumVal(simple, " simple spiller"),
45 clEnumVal(local, " local spiller"),
50 //===----------------------------------------------------------------------===//
51 // VirtRegMap implementation
52 //===----------------------------------------------------------------------===//
54 void VirtRegMap::grow() {
55 v2pMap_.grow(mf_->getSSARegMap()->getLastVirtReg());
56 v2ssMap_.grow(mf_->getSSARegMap()->getLastVirtReg());
59 int VirtRegMap::assignVirt2StackSlot(unsigned virtReg) {
60 assert(MRegisterInfo::isVirtualRegister(virtReg));
61 assert(v2ssMap_[virtReg] == NO_STACK_SLOT &&
62 "attempt to assign stack slot to already spilled register");
63 const TargetRegisterClass* RC = mf_->getSSARegMap()->getRegClass(virtReg);
64 int frameIndex = mf_->getFrameInfo()->CreateStackObject(RC->getSize(),
66 v2ssMap_[virtReg] = frameIndex;
71 void VirtRegMap::assignVirt2StackSlot(unsigned virtReg, int frameIndex) {
72 assert(MRegisterInfo::isVirtualRegister(virtReg));
73 assert(v2ssMap_[virtReg] == NO_STACK_SLOT &&
74 "attempt to assign stack slot to already spilled register");
75 v2ssMap_[virtReg] = frameIndex;
78 void VirtRegMap::virtFolded(unsigned virtReg,
80 MachineInstr* newMI) {
81 // move previous memory references folded to new instruction
82 MI2VirtMap::iterator i, e;
83 std::vector<MI2VirtMap::mapped_type> regs;
84 for (tie(i, e) = mi2vMap_.equal_range(oldMI); i != e; ) {
85 regs.push_back(i->second);
88 for (unsigned i = 0, e = regs.size(); i != e; ++i)
89 mi2vMap_.insert(std::make_pair(newMI, i));
91 // add new memory reference
92 mi2vMap_.insert(std::make_pair(newMI, virtReg));
95 void VirtRegMap::print(std::ostream& os) const {
96 const MRegisterInfo* mri = mf_->getTarget().getRegisterInfo();
98 std::cerr << "********** REGISTER MAP **********\n";
99 for (unsigned i = MRegisterInfo::FirstVirtualRegister,
100 e = mf_->getSSARegMap()->getLastVirtReg(); i <= e; ++i) {
101 if (v2pMap_[i] != (unsigned)VirtRegMap::NO_PHYS_REG)
102 std::cerr << "[reg" << i << " -> "
103 << mri->getName(v2pMap_[i]) << "]\n";
106 for (unsigned i = MRegisterInfo::FirstVirtualRegister,
107 e = mf_->getSSARegMap()->getLastVirtReg(); i <= e; ++i) {
108 if (v2ssMap_[i] != VirtRegMap::NO_STACK_SLOT)
109 std::cerr << "[reg" << i << " -> fi#"
110 << v2ssMap_[i] << "]\n";
115 void VirtRegMap::dump() const { print(std::cerr); }
118 //===----------------------------------------------------------------------===//
119 // Simple Spiller Implementation
120 //===----------------------------------------------------------------------===//
122 Spiller::~Spiller() {}
125 struct SimpleSpiller : public Spiller {
126 bool runOnMachineFunction(MachineFunction& mf, const VirtRegMap &VRM);
130 bool SimpleSpiller::runOnMachineFunction(MachineFunction& MF,
131 const VirtRegMap& VRM) {
132 DEBUG(std::cerr << "********** REWRITE MACHINE CODE **********\n");
133 DEBUG(std::cerr << "********** Function: "
134 << MF.getFunction()->getName() << '\n');
135 const TargetMachine& TM = MF.getTarget();
136 const MRegisterInfo& mri = *TM.getRegisterInfo();
138 DenseMap<bool, VirtReg2IndexFunctor> Loaded;
140 for (MachineFunction::iterator mbbi = MF.begin(), E = MF.end();
142 DEBUG(std::cerr << mbbi->getBasicBlock()->getName() << ":\n");
143 for (MachineBasicBlock::iterator mii = mbbi->begin(),
144 mie = mbbi->end(); mii != mie; ++mii) {
145 Loaded.grow(MF.getSSARegMap()->getLastVirtReg());
146 for (unsigned i = 0,e = mii->getNumOperands(); i != e; ++i){
147 MachineOperand& mop = mii->getOperand(i);
148 if (mop.isRegister() && mop.getReg() &&
149 MRegisterInfo::isVirtualRegister(mop.getReg())) {
150 unsigned virtReg = mop.getReg();
151 unsigned physReg = VRM.getPhys(virtReg);
152 if (mop.isUse() && VRM.hasStackSlot(mop.getReg()) &&
154 mri.loadRegFromStackSlot(*mbbi, mii, physReg,
155 VRM.getStackSlot(virtReg));
156 Loaded[virtReg] = true;
157 DEBUG(std::cerr << '\t';
158 prior(mii)->print(std::cerr, &TM));
162 if (mop.isDef() && VRM.hasStackSlot(mop.getReg())) {
163 mri.storeRegToStackSlot(*mbbi, next(mii), physReg,
164 VRM.getStackSlot(virtReg));
167 mii->SetMachineOperandReg(i, physReg);
170 DEBUG(std::cerr << '\t'; mii->print(std::cerr, &TM));
177 //===----------------------------------------------------------------------===//
178 // Local Spiller Implementation
179 //===----------------------------------------------------------------------===//
182 class LocalSpiller : public Spiller {
183 typedef std::vector<unsigned> Phys2VirtMap;
184 typedef std::vector<bool> PhysFlag;
185 typedef DenseMap<MachineInstr*, VirtReg2IndexFunctor> Virt2MI;
188 const TargetMachine *TM;
189 const TargetInstrInfo *TII;
190 const MRegisterInfo *MRI;
191 const VirtRegMap *VRM;
192 Phys2VirtMap p2vMap_;
197 bool runOnMachineFunction(MachineFunction &MF, const VirtRegMap &VRM);
200 void vacateJustPhysReg(MachineBasicBlock& mbb,
201 MachineBasicBlock::iterator mii,
204 void vacatePhysReg(MachineBasicBlock& mbb,
205 MachineBasicBlock::iterator mii,
207 vacateJustPhysReg(mbb, mii, physReg);
208 for (const unsigned* as = MRI->getAliasSet(physReg); *as; ++as)
209 vacateJustPhysReg(mbb, mii, *as);
212 void handleUse(MachineBasicBlock& mbb,
213 MachineBasicBlock::iterator mii,
216 // check if we are replacing a previous mapping
217 if (p2vMap_[physReg] != virtReg) {
218 vacatePhysReg(mbb, mii, physReg);
219 p2vMap_[physReg] = virtReg;
221 if (VRM->hasStackSlot(virtReg)) {
222 MRI->loadRegFromStackSlot(mbb, mii, physReg,
223 VRM->getStackSlot(virtReg));
225 DEBUG(std::cerr << "added: ";
226 prior(mii)->print(std::cerr, TM));
227 lastDef_[virtReg] = mii;
232 void handleDef(MachineBasicBlock& mbb,
233 MachineBasicBlock::iterator mii,
236 // check if we are replacing a previous mapping
237 if (p2vMap_[physReg] != virtReg)
238 vacatePhysReg(mbb, mii, physReg);
240 p2vMap_[physReg] = virtReg;
241 dirty_[physReg] = true;
242 lastDef_[virtReg] = mii;
245 void eliminateVirtRegsInMbb(MachineBasicBlock& mbb);
249 bool LocalSpiller::runOnMachineFunction(MachineFunction &mf,
250 const VirtRegMap &vrm) {
252 TM = &MF->getTarget();
253 TII = TM->getInstrInfo();
254 MRI = TM->getRegisterInfo();
256 p2vMap_.assign(MRI->getNumRegs(), 0);
257 dirty_.assign(MRI->getNumRegs(), false);
259 DEBUG(std::cerr << "********** REWRITE MACHINE CODE **********\n");
260 DEBUG(std::cerr << "********** Function: "
261 << MF->getFunction()->getName() << '\n');
263 for (MachineFunction::iterator mbbi = MF->begin(),
264 mbbe = MF->end(); mbbi != mbbe; ++mbbi) {
265 lastDef_.grow(MF->getSSARegMap()->getLastVirtReg());
266 DEBUG(std::cerr << mbbi->getBasicBlock()->getName() << ":\n");
267 eliminateVirtRegsInMbb(*mbbi);
268 // clear map, dirty flag and last ref
269 p2vMap_.assign(p2vMap_.size(), 0);
270 dirty_.assign(dirty_.size(), false);
276 void LocalSpiller::vacateJustPhysReg(MachineBasicBlock& mbb,
277 MachineBasicBlock::iterator mii,
279 unsigned virtReg = p2vMap_[physReg];
280 if (dirty_[physReg] && VRM->hasStackSlot(virtReg)) {
281 assert(lastDef_[virtReg] && "virtual register is mapped "
282 "to a register and but was not defined!");
283 MachineBasicBlock::iterator lastDef = lastDef_[virtReg];
284 MachineBasicBlock::iterator nextLastRef = next(lastDef);
285 MRI->storeRegToStackSlot(*lastDef->getParent(),
288 VRM->getStackSlot(virtReg));
290 DEBUG(std::cerr << "added: ";
291 prior(nextLastRef)->print(std::cerr, TM);
292 std::cerr << "after: ";
293 lastDef->print(std::cerr, TM));
294 lastDef_[virtReg] = 0;
296 p2vMap_[physReg] = 0;
297 dirty_[physReg] = false;
300 void LocalSpiller::eliminateVirtRegsInMbb(MachineBasicBlock &MBB) {
301 for (MachineBasicBlock::iterator MI = MBB.begin(), E = MBB.end();
304 // if we have references to memory operands make sure
305 // we clear all physical registers that may contain
306 // the value of the spilled virtual register
307 VirtRegMap::MI2VirtMap::const_iterator i, e;
308 for (tie(i, e) = VRM->getFoldedVirts(MI); i != e; ++i) {
309 if (VRM->hasPhys(i->second))
310 vacateJustPhysReg(MBB, MI, VRM->getPhys(i->second));
313 // rewrite all used operands
314 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
315 MachineOperand& op = MI->getOperand(i);
316 if (op.isRegister() && op.getReg() && op.isUse() &&
317 MRegisterInfo::isVirtualRegister(op.getReg())) {
318 unsigned virtReg = op.getReg();
319 unsigned physReg = VRM->getPhys(virtReg);
320 handleUse(MBB, MI, virtReg, physReg);
321 MI->SetMachineOperandReg(i, physReg);
322 // mark as dirty if this is def&use
324 dirty_[physReg] = true;
325 lastDef_[virtReg] = MI;
330 // spill implicit physical register defs
331 const TargetInstrDescriptor& tid = TII->get(MI->getOpcode());
332 for (const unsigned* id = tid.ImplicitDefs; *id; ++id)
333 vacatePhysReg(MBB, MI, *id);
335 // spill explicit physical register defs
336 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
337 MachineOperand& op = MI->getOperand(i);
338 if (op.isRegister() && op.getReg() && !op.isUse() &&
339 MRegisterInfo::isPhysicalRegister(op.getReg()))
340 vacatePhysReg(MBB, MI, op.getReg());
343 // rewrite def operands (def&use was handled with the
344 // uses so don't check for those here)
345 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
346 MachineOperand& op = MI->getOperand(i);
347 if (op.isRegister() && op.getReg() && !op.isUse())
348 if (MRegisterInfo::isPhysicalRegister(op.getReg()))
349 vacatePhysReg(MBB, MI, op.getReg());
351 unsigned physReg = VRM->getPhys(op.getReg());
352 handleDef(MBB, MI, op.getReg(), physReg);
353 MI->SetMachineOperandReg(i, physReg);
357 DEBUG(std::cerr << '\t'; MI->print(std::cerr, TM));
360 for (unsigned i = 1, e = p2vMap_.size(); i != e; ++i)
361 vacateJustPhysReg(MBB, MBB.getFirstTerminator(), i);
365 llvm::Spiller* llvm::createSpiller() {
366 switch (SpillerOpt) {
367 default: assert(0 && "Unreachable!");
369 return new LocalSpiller();
371 return new SimpleSpiller();