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1 //===-- lib/CodeGen/MachineInstrBundle.cpp --------------------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "llvm/CodeGen/MachineInstrBundle.h"
11 #include "llvm/ADT/SmallSet.h"
12 #include "llvm/ADT/SmallVector.h"
13 #include "llvm/CodeGen/MachineFunctionPass.h"
14 #include "llvm/CodeGen/MachineInstrBuilder.h"
15 #include "llvm/CodeGen/Passes.h"
16 #include "llvm/Target/TargetInstrInfo.h"
17 #include "llvm/Target/TargetMachine.h"
18 #include "llvm/Target/TargetRegisterInfo.h"
19 #include "llvm/Target/TargetSubtargetInfo.h"
20 #include <utility>
21 using namespace llvm;
22 
23 namespace {
24   class UnpackMachineBundles : public MachineFunctionPass {
25   public:
26     static char ID; // Pass identification
UnpackMachineBundles(std::function<bool (const Function &)> Ftor=nullptr)27     UnpackMachineBundles(std::function<bool(const Function &)> Ftor = nullptr)
28         : MachineFunctionPass(ID), PredicateFtor(std::move(Ftor)) {
29       initializeUnpackMachineBundlesPass(*PassRegistry::getPassRegistry());
30     }
31 
32     bool runOnMachineFunction(MachineFunction &MF) override;
33 
34   private:
35     std::function<bool(const Function &)> PredicateFtor;
36   };
37 } // end anonymous namespace
38 
39 char UnpackMachineBundles::ID = 0;
40 char &llvm::UnpackMachineBundlesID = UnpackMachineBundles::ID;
41 INITIALIZE_PASS(UnpackMachineBundles, "unpack-mi-bundles",
42                 "Unpack machine instruction bundles", false, false)
43 
runOnMachineFunction(MachineFunction & MF)44 bool UnpackMachineBundles::runOnMachineFunction(MachineFunction &MF) {
45   if (PredicateFtor && !PredicateFtor(*MF.getFunction()))
46     return false;
47 
48   bool Changed = false;
49   for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
50     MachineBasicBlock *MBB = &*I;
51 
52     for (MachineBasicBlock::instr_iterator MII = MBB->instr_begin(),
53            MIE = MBB->instr_end(); MII != MIE; ) {
54       MachineInstr *MI = &*MII;
55 
56       // Remove BUNDLE instruction and the InsideBundle flags from bundled
57       // instructions.
58       if (MI->isBundle()) {
59         while (++MII != MIE && MII->isBundledWithPred()) {
60           MII->unbundleFromPred();
61           for (unsigned i = 0, e = MII->getNumOperands(); i != e; ++i) {
62             MachineOperand &MO = MII->getOperand(i);
63             if (MO.isReg() && MO.isInternalRead())
64               MO.setIsInternalRead(false);
65           }
66         }
67         MI->eraseFromParent();
68 
69         Changed = true;
70         continue;
71       }
72 
73       ++MII;
74     }
75   }
76 
77   return Changed;
78 }
79 
80 FunctionPass *
createUnpackMachineBundles(std::function<bool (const Function &)> Ftor)81 llvm::createUnpackMachineBundles(std::function<bool(const Function &)> Ftor) {
82   return new UnpackMachineBundles(std::move(Ftor));
83 }
84 
85 namespace {
86   class FinalizeMachineBundles : public MachineFunctionPass {
87   public:
88     static char ID; // Pass identification
FinalizeMachineBundles()89     FinalizeMachineBundles() : MachineFunctionPass(ID) {
90       initializeFinalizeMachineBundlesPass(*PassRegistry::getPassRegistry());
91     }
92 
93     bool runOnMachineFunction(MachineFunction &MF) override;
94   };
95 } // end anonymous namespace
96 
97 char FinalizeMachineBundles::ID = 0;
98 char &llvm::FinalizeMachineBundlesID = FinalizeMachineBundles::ID;
99 INITIALIZE_PASS(FinalizeMachineBundles, "finalize-mi-bundles",
100                 "Finalize machine instruction bundles", false, false)
101 
runOnMachineFunction(MachineFunction & MF)102 bool FinalizeMachineBundles::runOnMachineFunction(MachineFunction &MF) {
103   return llvm::finalizeBundles(MF);
104 }
105 
106 
107 /// finalizeBundle - Finalize a machine instruction bundle which includes
108 /// a sequence of instructions starting from FirstMI to LastMI (exclusive).
109 /// This routine adds a BUNDLE instruction to represent the bundle, it adds
110 /// IsInternalRead markers to MachineOperands which are defined inside the
111 /// bundle, and it copies externally visible defs and uses to the BUNDLE
112 /// instruction.
finalizeBundle(MachineBasicBlock & MBB,MachineBasicBlock::instr_iterator FirstMI,MachineBasicBlock::instr_iterator LastMI)113 void llvm::finalizeBundle(MachineBasicBlock &MBB,
114                           MachineBasicBlock::instr_iterator FirstMI,
115                           MachineBasicBlock::instr_iterator LastMI) {
116   assert(FirstMI != LastMI && "Empty bundle?");
117   MIBundleBuilder Bundle(MBB, FirstMI, LastMI);
118 
119   MachineFunction &MF = *MBB.getParent();
120   const TargetInstrInfo *TII = MF.getSubtarget().getInstrInfo();
121   const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
122 
123   MachineInstrBuilder MIB =
124       BuildMI(MF, FirstMI->getDebugLoc(), TII->get(TargetOpcode::BUNDLE));
125   Bundle.prepend(MIB);
126 
127   SmallVector<unsigned, 32> LocalDefs;
128   SmallSet<unsigned, 32> LocalDefSet;
129   SmallSet<unsigned, 8> DeadDefSet;
130   SmallSet<unsigned, 16> KilledDefSet;
131   SmallVector<unsigned, 8> ExternUses;
132   SmallSet<unsigned, 8> ExternUseSet;
133   SmallSet<unsigned, 8> KilledUseSet;
134   SmallSet<unsigned, 8> UndefUseSet;
135   SmallVector<MachineOperand*, 4> Defs;
136   for (; FirstMI != LastMI; ++FirstMI) {
137     for (unsigned i = 0, e = FirstMI->getNumOperands(); i != e; ++i) {
138       MachineOperand &MO = FirstMI->getOperand(i);
139       if (!MO.isReg())
140         continue;
141       if (MO.isDef()) {
142         Defs.push_back(&MO);
143         continue;
144       }
145 
146       unsigned Reg = MO.getReg();
147       if (!Reg)
148         continue;
149       assert(TargetRegisterInfo::isPhysicalRegister(Reg));
150       if (LocalDefSet.count(Reg)) {
151         MO.setIsInternalRead();
152         if (MO.isKill())
153           // Internal def is now killed.
154           KilledDefSet.insert(Reg);
155       } else {
156         if (ExternUseSet.insert(Reg).second) {
157           ExternUses.push_back(Reg);
158           if (MO.isUndef())
159             UndefUseSet.insert(Reg);
160         }
161         if (MO.isKill())
162           // External def is now killed.
163           KilledUseSet.insert(Reg);
164       }
165     }
166 
167     for (unsigned i = 0, e = Defs.size(); i != e; ++i) {
168       MachineOperand &MO = *Defs[i];
169       unsigned Reg = MO.getReg();
170       if (!Reg)
171         continue;
172 
173       if (LocalDefSet.insert(Reg).second) {
174         LocalDefs.push_back(Reg);
175         if (MO.isDead()) {
176           DeadDefSet.insert(Reg);
177         }
178       } else {
179         // Re-defined inside the bundle, it's no longer killed.
180         KilledDefSet.erase(Reg);
181         if (!MO.isDead())
182           // Previously defined but dead.
183           DeadDefSet.erase(Reg);
184       }
185 
186       if (!MO.isDead()) {
187         for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs) {
188           unsigned SubReg = *SubRegs;
189           if (LocalDefSet.insert(SubReg).second)
190             LocalDefs.push_back(SubReg);
191         }
192       }
193     }
194 
195     Defs.clear();
196   }
197 
198   SmallSet<unsigned, 32> Added;
199   for (unsigned i = 0, e = LocalDefs.size(); i != e; ++i) {
200     unsigned Reg = LocalDefs[i];
201     if (Added.insert(Reg).second) {
202       // If it's not live beyond end of the bundle, mark it dead.
203       bool isDead = DeadDefSet.count(Reg) || KilledDefSet.count(Reg);
204       MIB.addReg(Reg, getDefRegState(true) | getDeadRegState(isDead) |
205                  getImplRegState(true));
206     }
207   }
208 
209   for (unsigned i = 0, e = ExternUses.size(); i != e; ++i) {
210     unsigned Reg = ExternUses[i];
211     bool isKill = KilledUseSet.count(Reg);
212     bool isUndef = UndefUseSet.count(Reg);
213     MIB.addReg(Reg, getKillRegState(isKill) | getUndefRegState(isUndef) |
214                getImplRegState(true));
215   }
216 }
217 
218 /// finalizeBundle - Same functionality as the previous finalizeBundle except
219 /// the last instruction in the bundle is not provided as an input. This is
220 /// used in cases where bundles are pre-determined by marking instructions
221 /// with 'InsideBundle' marker. It returns the MBB instruction iterator that
222 /// points to the end of the bundle.
223 MachineBasicBlock::instr_iterator
finalizeBundle(MachineBasicBlock & MBB,MachineBasicBlock::instr_iterator FirstMI)224 llvm::finalizeBundle(MachineBasicBlock &MBB,
225                      MachineBasicBlock::instr_iterator FirstMI) {
226   MachineBasicBlock::instr_iterator E = MBB.instr_end();
227   MachineBasicBlock::instr_iterator LastMI = std::next(FirstMI);
228   while (LastMI != E && LastMI->isInsideBundle())
229     ++LastMI;
230   finalizeBundle(MBB, FirstMI, LastMI);
231   return LastMI;
232 }
233 
234 /// finalizeBundles - Finalize instruction bundles in the specified
235 /// MachineFunction. Return true if any bundles are finalized.
finalizeBundles(MachineFunction & MF)236 bool llvm::finalizeBundles(MachineFunction &MF) {
237   bool Changed = false;
238   for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
239     MachineBasicBlock &MBB = *I;
240     MachineBasicBlock::instr_iterator MII = MBB.instr_begin();
241     MachineBasicBlock::instr_iterator MIE = MBB.instr_end();
242     if (MII == MIE)
243       continue;
244     assert(!MII->isInsideBundle() &&
245            "First instr cannot be inside bundle before finalization!");
246 
247     for (++MII; MII != MIE; ) {
248       if (!MII->isInsideBundle())
249         ++MII;
250       else {
251         MII = finalizeBundle(MBB, std::prev(MII));
252         Changed = true;
253       }
254     }
255   }
256 
257   return Changed;
258 }
259 
260 //===----------------------------------------------------------------------===//
261 // MachineOperand iterator
262 //===----------------------------------------------------------------------===//
263 
264 MachineOperandIteratorBase::VirtRegInfo
analyzeVirtReg(unsigned Reg,SmallVectorImpl<std::pair<MachineInstr *,unsigned>> * Ops)265 MachineOperandIteratorBase::analyzeVirtReg(unsigned Reg,
266                     SmallVectorImpl<std::pair<MachineInstr*, unsigned> > *Ops) {
267   VirtRegInfo RI = { false, false, false };
268   for(; isValid(); ++*this) {
269     MachineOperand &MO = deref();
270     if (!MO.isReg() || MO.getReg() != Reg)
271       continue;
272 
273     // Remember each (MI, OpNo) that refers to Reg.
274     if (Ops)
275       Ops->push_back(std::make_pair(MO.getParent(), getOperandNo()));
276 
277     // Both defs and uses can read virtual registers.
278     if (MO.readsReg()) {
279       RI.Reads = true;
280       if (MO.isDef())
281         RI.Tied = true;
282     }
283 
284     // Only defs can write.
285     if (MO.isDef())
286       RI.Writes = true;
287     else if (!RI.Tied && MO.getParent()->isRegTiedToDefOperand(getOperandNo()))
288       RI.Tied = true;
289   }
290   return RI;
291 }
292 
293 MachineOperandIteratorBase::PhysRegInfo
analyzePhysReg(unsigned Reg,const TargetRegisterInfo * TRI)294 MachineOperandIteratorBase::analyzePhysReg(unsigned Reg,
295                                            const TargetRegisterInfo *TRI) {
296   bool AllDefsDead = true;
297   PhysRegInfo PRI = {false, false, false, false, false, false, false, false};
298 
299   assert(TargetRegisterInfo::isPhysicalRegister(Reg) &&
300          "analyzePhysReg not given a physical register!");
301   for (; isValid(); ++*this) {
302     MachineOperand &MO = deref();
303 
304     if (MO.isRegMask() && MO.clobbersPhysReg(Reg)) {
305       PRI.Clobbered = true;
306       continue;
307     }
308 
309     if (!MO.isReg())
310       continue;
311 
312     unsigned MOReg = MO.getReg();
313     if (!MOReg || !TargetRegisterInfo::isPhysicalRegister(MOReg))
314       continue;
315 
316     if (!TRI->regsOverlap(MOReg, Reg))
317       continue;
318 
319     bool Covered = TRI->isSuperRegisterEq(Reg, MOReg);
320     if (MO.readsReg()) {
321       PRI.Read = true;
322       if (Covered) {
323         PRI.FullyRead = true;
324         if (MO.isKill())
325           PRI.Killed = true;
326       }
327     } else if (MO.isDef()) {
328       PRI.Defined = true;
329       if (Covered)
330         PRI.FullyDefined = true;
331       if (!MO.isDead())
332         AllDefsDead = false;
333     }
334   }
335 
336   if (AllDefsDead) {
337     if (PRI.FullyDefined || PRI.Clobbered)
338       PRI.DeadDef = true;
339     else if (PRI.Defined)
340       PRI.PartialDeadDef = true;
341   }
342 
343   return PRI;
344 }
345