1 //===-- lib/Codegen/MachineRegisterInfo.cpp -------------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // Implementation of the MachineRegisterInfo class.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/CodeGen/MachineRegisterInfo.h"
15 #include "llvm/CodeGen/MachineInstrBuilder.h"
16 #include "llvm/Target/TargetInstrInfo.h"
17 #include "llvm/Target/TargetMachine.h"
20 MachineRegisterInfo::MachineRegisterInfo(const TargetRegisterInfo &TRI)
22 VRegInfo.reserve(256);
23 RegAllocHints.reserve(256);
24 UsedPhysRegs.resize(TRI.getNumRegs());
26 // Create the physreg use/def lists.
27 PhysRegUseDefLists = new MachineOperand*[TRI.getNumRegs()];
28 memset(PhysRegUseDefLists, 0, sizeof(MachineOperand*)*TRI.getNumRegs());
31 MachineRegisterInfo::~MachineRegisterInfo() {
33 for (unsigned i = 0, e = getNumVirtRegs(); i != e; ++i)
34 assert(VRegInfo[TargetRegisterInfo::index2VirtReg(i)].second == 0 &&
35 "Vreg use list non-empty still?");
36 for (unsigned i = 0, e = UsedPhysRegs.size(); i != e; ++i)
37 assert(!PhysRegUseDefLists[i] &&
38 "PhysRegUseDefLists has entries after all instructions are deleted");
40 delete [] PhysRegUseDefLists;
43 /// setRegClass - Set the register class of the specified virtual register.
46 MachineRegisterInfo::setRegClass(unsigned Reg, const TargetRegisterClass *RC) {
47 VRegInfo[Reg].first = RC;
50 const TargetRegisterClass *
51 MachineRegisterInfo::constrainRegClass(unsigned Reg,
52 const TargetRegisterClass *RC,
53 unsigned MinNumRegs) {
54 const TargetRegisterClass *OldRC = getRegClass(Reg);
57 const TargetRegisterClass *NewRC = getCommonSubClass(OldRC, RC);
58 if (!NewRC || NewRC == OldRC)
60 if (NewRC->getNumRegs() < MinNumRegs)
62 setRegClass(Reg, NewRC);
67 MachineRegisterInfo::recomputeRegClass(unsigned Reg, const TargetMachine &TM) {
68 const TargetInstrInfo *TII = TM.getInstrInfo();
69 const TargetRegisterInfo *TRI = TM.getRegisterInfo();
70 const TargetRegisterClass *OldRC = getRegClass(Reg);
71 const TargetRegisterClass *NewRC = TRI->getLargestLegalSuperClass(OldRC);
73 // Stop early if there is no room to grow.
77 // Accumulate constraints from all uses.
78 for (reg_nodbg_iterator I = reg_nodbg_begin(Reg), E = reg_nodbg_end(); I != E;
80 // TRI doesn't have accurate enough information to model this yet.
81 if (I.getOperand().getSubReg())
83 // Inline asm instuctions don't remember their constraints.
86 const TargetRegisterClass *OpRC =
87 TII->getRegClass(I->getDesc(), I.getOperandNo(), TRI);
89 NewRC = getCommonSubClass(NewRC, OpRC);
90 if (!NewRC || NewRC == OldRC)
93 setRegClass(Reg, NewRC);
97 /// createVirtualRegister - Create and return a new virtual register in the
98 /// function with the specified register class.
101 MachineRegisterInfo::createVirtualRegister(const TargetRegisterClass *RegClass){
102 assert(RegClass && "Cannot create register without RegClass!");
103 assert(RegClass->isAllocatable() &&
104 "Virtual register RegClass must be allocatable.");
106 // New virtual register number.
107 unsigned Reg = TargetRegisterInfo::index2VirtReg(getNumVirtRegs());
109 // Add a reg, but keep track of whether the vector reallocated or not.
110 const unsigned FirstVirtReg = TargetRegisterInfo::index2VirtReg(0);
111 void *ArrayBase = getNumVirtRegs() == 0 ? 0 : &VRegInfo[FirstVirtReg];
113 VRegInfo[Reg].first = RegClass;
114 RegAllocHints.grow(Reg);
116 if (ArrayBase && &VRegInfo[FirstVirtReg] != ArrayBase)
117 // The vector reallocated, handle this now.
118 HandleVRegListReallocation();
122 /// HandleVRegListReallocation - We just added a virtual register to the
123 /// VRegInfo info list and it reallocated. Update the use/def lists info
125 void MachineRegisterInfo::HandleVRegListReallocation() {
126 // The back pointers for the vreg lists point into the previous vector.
127 // Update them to point to their correct slots.
128 for (unsigned i = 0, e = getNumVirtRegs(); i != e; ++i) {
129 unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
130 MachineOperand *List = VRegInfo[Reg].second;
132 // Update the back-pointer to be accurate once more.
133 List->Contents.Reg.Prev = &VRegInfo[Reg].second;
137 /// replaceRegWith - Replace all instances of FromReg with ToReg in the
138 /// machine function. This is like llvm-level X->replaceAllUsesWith(Y),
139 /// except that it also changes any definitions of the register as well.
140 void MachineRegisterInfo::replaceRegWith(unsigned FromReg, unsigned ToReg) {
141 assert(FromReg != ToReg && "Cannot replace a reg with itself");
143 // TODO: This could be more efficient by bulk changing the operands.
144 for (reg_iterator I = reg_begin(FromReg), E = reg_end(); I != E; ) {
145 MachineOperand &O = I.getOperand();
152 /// getVRegDef - Return the machine instr that defines the specified virtual
153 /// register or null if none is found. This assumes that the code is in SSA
154 /// form, so there should only be one definition.
155 MachineInstr *MachineRegisterInfo::getVRegDef(unsigned Reg) const {
156 // Since we are in SSA form, we can use the first definition.
158 return &*def_begin(Reg);
162 bool MachineRegisterInfo::hasOneUse(unsigned RegNo) const {
163 use_iterator UI = use_begin(RegNo);
166 return ++UI == use_end();
169 bool MachineRegisterInfo::hasOneNonDBGUse(unsigned RegNo) const {
170 use_nodbg_iterator UI = use_nodbg_begin(RegNo);
171 if (UI == use_nodbg_end())
173 return ++UI == use_nodbg_end();
176 /// clearKillFlags - Iterate over all the uses of the given register and
177 /// clear the kill flag from the MachineOperand. This function is used by
178 /// optimization passes which extend register lifetimes and need only
179 /// preserve conservative kill flag information.
180 void MachineRegisterInfo::clearKillFlags(unsigned Reg) const {
181 for (use_iterator UI = use_begin(Reg), UE = use_end(); UI != UE; ++UI)
182 UI.getOperand().setIsKill(false);
185 bool MachineRegisterInfo::isLiveIn(unsigned Reg) const {
186 for (livein_iterator I = livein_begin(), E = livein_end(); I != E; ++I)
187 if (I->first == Reg || I->second == Reg)
192 bool MachineRegisterInfo::isLiveOut(unsigned Reg) const {
193 for (liveout_iterator I = liveout_begin(), E = liveout_end(); I != E; ++I)
199 /// getLiveInPhysReg - If VReg is a live-in virtual register, return the
200 /// corresponding live-in physical register.
201 unsigned MachineRegisterInfo::getLiveInPhysReg(unsigned VReg) const {
202 for (livein_iterator I = livein_begin(), E = livein_end(); I != E; ++I)
203 if (I->second == VReg)
208 /// getLiveInVirtReg - If PReg is a live-in physical register, return the
209 /// corresponding live-in physical register.
210 unsigned MachineRegisterInfo::getLiveInVirtReg(unsigned PReg) const {
211 for (livein_iterator I = livein_begin(), E = livein_end(); I != E; ++I)
212 if (I->first == PReg)
217 /// EmitLiveInCopies - Emit copies to initialize livein virtual registers
218 /// into the given entry block.
220 MachineRegisterInfo::EmitLiveInCopies(MachineBasicBlock *EntryMBB,
221 const TargetRegisterInfo &TRI,
222 const TargetInstrInfo &TII) {
223 // Emit the copies into the top of the block.
224 for (unsigned i = 0, e = LiveIns.size(); i != e; ++i)
225 if (LiveIns[i].second) {
226 if (use_empty(LiveIns[i].second)) {
227 // The livein has no uses. Drop it.
229 // It would be preferable to have isel avoid creating live-in
230 // records for unused arguments in the first place, but it's
231 // complicated by the debug info code for arguments.
232 LiveIns.erase(LiveIns.begin() + i);
236 BuildMI(*EntryMBB, EntryMBB->begin(), DebugLoc(),
237 TII.get(TargetOpcode::COPY), LiveIns[i].second)
238 .addReg(LiveIns[i].first);
240 // Add the register to the entry block live-in set.
241 EntryMBB->addLiveIn(LiveIns[i].first);
244 // Add the register to the entry block live-in set.
245 EntryMBB->addLiveIn(LiveIns[i].first);
249 void MachineRegisterInfo::closePhysRegsUsed(const TargetRegisterInfo &TRI) {
250 for (int i = UsedPhysRegs.find_first(); i >= 0;
251 i = UsedPhysRegs.find_next(i))
252 for (const unsigned *SS = TRI.getSubRegisters(i);
253 unsigned SubReg = *SS; ++SS)
254 if (SubReg > unsigned(i))
255 UsedPhysRegs.set(SubReg);
259 void MachineRegisterInfo::dumpUses(unsigned Reg) const {
260 for (use_iterator I = use_begin(Reg), E = use_end(); I != E; ++I)
261 I.getOperand().getParent()->dump();