1 //===- MachineFunction.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 // Collect native machine code information for a function.  This allows
11 // target-specific information about the generated code to be stored with each
12 // function.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #include "llvm/CodeGen/MachineFunction.h"
17 #include "llvm/ADT/BitVector.h"
18 #include "llvm/ADT/DenseMap.h"
19 #include "llvm/ADT/DenseSet.h"
20 #include "llvm/ADT/STLExtras.h"
21 #include "llvm/ADT/SmallString.h"
22 #include "llvm/ADT/SmallVector.h"
23 #include "llvm/ADT/StringRef.h"
24 #include "llvm/ADT/Twine.h"
25 #include "llvm/Analysis/ConstantFolding.h"
26 #include "llvm/Analysis/EHPersonalities.h"
27 #include "llvm/CodeGen/MachineBasicBlock.h"
28 #include "llvm/CodeGen/MachineConstantPool.h"
29 #include "llvm/CodeGen/MachineFrameInfo.h"
30 #include "llvm/CodeGen/MachineInstr.h"
31 #include "llvm/CodeGen/MachineJumpTableInfo.h"
32 #include "llvm/CodeGen/MachineMemOperand.h"
33 #include "llvm/CodeGen/MachineModuleInfo.h"
34 #include "llvm/CodeGen/MachineRegisterInfo.h"
35 #include "llvm/CodeGen/PseudoSourceValue.h"
36 #include "llvm/CodeGen/TargetFrameLowering.h"
37 #include "llvm/CodeGen/TargetLowering.h"
38 #include "llvm/CodeGen/TargetRegisterInfo.h"
39 #include "llvm/CodeGen/TargetSubtargetInfo.h"
40 #include "llvm/CodeGen/WasmEHFuncInfo.h"
41 #include "llvm/CodeGen/WinEHFuncInfo.h"
42 #include "llvm/Config/llvm-config.h"
43 #include "llvm/IR/Attributes.h"
44 #include "llvm/IR/BasicBlock.h"
45 #include "llvm/IR/Constant.h"
46 #include "llvm/IR/DataLayout.h"
47 #include "llvm/IR/DerivedTypes.h"
48 #include "llvm/IR/Function.h"
49 #include "llvm/IR/GlobalValue.h"
50 #include "llvm/IR/Instruction.h"
51 #include "llvm/IR/Instructions.h"
52 #include "llvm/IR/Metadata.h"
53 #include "llvm/IR/Module.h"
54 #include "llvm/IR/ModuleSlotTracker.h"
55 #include "llvm/IR/Value.h"
56 #include "llvm/MC/MCContext.h"
57 #include "llvm/MC/MCSymbol.h"
58 #include "llvm/MC/SectionKind.h"
59 #include "llvm/Support/Casting.h"
60 #include "llvm/Support/CommandLine.h"
61 #include "llvm/Support/Compiler.h"
62 #include "llvm/Support/DOTGraphTraits.h"
63 #include "llvm/Support/Debug.h"
64 #include "llvm/Support/ErrorHandling.h"
65 #include "llvm/Support/GraphWriter.h"
66 #include "llvm/Support/raw_ostream.h"
67 #include "llvm/Target/TargetMachine.h"
68 #include <algorithm>
69 #include <cassert>
70 #include <cstddef>
71 #include <cstdint>
72 #include <iterator>
73 #include <string>
74 #include <utility>
75 #include <vector>
76 
77 using namespace llvm;
78 
79 #define DEBUG_TYPE "codegen"
80 
81 static cl::opt<unsigned>
82 AlignAllFunctions("align-all-functions",
83                   cl::desc("Force the alignment of all functions."),
84                   cl::init(0), cl::Hidden);
85 
86 static const char *getPropertyName(MachineFunctionProperties::Property Prop) {
87   using P = MachineFunctionProperties::Property;
88 
89   switch(Prop) {
90   case P::FailedISel: return "FailedISel";
91   case P::IsSSA: return "IsSSA";
92   case P::Legalized: return "Legalized";
93   case P::NoPHIs: return "NoPHIs";
94   case P::NoVRegs: return "NoVRegs";
95   case P::RegBankSelected: return "RegBankSelected";
96   case P::Selected: return "Selected";
97   case P::TracksLiveness: return "TracksLiveness";
98   }
99   llvm_unreachable("Invalid machine function property");
100 }
101 
102 void MachineFunctionProperties::print(raw_ostream &OS) const {
103   const char *Separator = "";
104   for (BitVector::size_type I = 0; I < Properties.size(); ++I) {
105     if (!Properties[I])
106       continue;
107     OS << Separator << getPropertyName(static_cast<Property>(I));
108     Separator = ", ";
109   }
110 }
111 
112 //===----------------------------------------------------------------------===//
113 // MachineFunction implementation
114 //===----------------------------------------------------------------------===//
115 
116 // Out-of-line virtual method.
117 MachineFunctionInfo::~MachineFunctionInfo() = default;
118 
119 void ilist_alloc_traits<MachineBasicBlock>::deleteNode(MachineBasicBlock *MBB) {
120   MBB->getParent()->DeleteMachineBasicBlock(MBB);
121 }
122 
123 static inline unsigned getFnStackAlignment(const TargetSubtargetInfo *STI,
124                                            const Function &F) {
125   if (F.hasFnAttribute(Attribute::StackAlignment))
126     return F.getFnStackAlignment();
127   return STI->getFrameLowering()->getStackAlignment();
128 }
129 
130 MachineFunction::MachineFunction(const Function &F, const TargetMachine &Target,
131                                  const TargetSubtargetInfo &STI,
132                                  unsigned FunctionNum, MachineModuleInfo &mmi)
133     : F(F), Target(Target), STI(&STI), Ctx(mmi.getContext()), MMI(mmi) {
134   FunctionNumber = FunctionNum;
135   init();
136 }
137 
138 void MachineFunction::init() {
139   // Assume the function starts in SSA form with correct liveness.
140   Properties.set(MachineFunctionProperties::Property::IsSSA);
141   Properties.set(MachineFunctionProperties::Property::TracksLiveness);
142   if (STI->getRegisterInfo())
143     RegInfo = new (Allocator) MachineRegisterInfo(this);
144   else
145     RegInfo = nullptr;
146 
147   MFInfo = nullptr;
148   // We can realign the stack if the target supports it and the user hasn't
149   // explicitly asked us not to.
150   bool CanRealignSP = STI->getFrameLowering()->isStackRealignable() &&
151                       !F.hasFnAttribute("no-realign-stack");
152   FrameInfo = new (Allocator) MachineFrameInfo(
153       getFnStackAlignment(STI, F), /*StackRealignable=*/CanRealignSP,
154       /*ForceRealign=*/CanRealignSP &&
155           F.hasFnAttribute(Attribute::StackAlignment));
156 
157   if (F.hasFnAttribute(Attribute::StackAlignment))
158     FrameInfo->ensureMaxAlignment(F.getFnStackAlignment());
159 
160   ConstantPool = new (Allocator) MachineConstantPool(getDataLayout());
161   Alignment = STI->getTargetLowering()->getMinFunctionAlignment();
162 
163   // FIXME: Shouldn't use pref alignment if explicit alignment is set on F.
164   // FIXME: Use Function::optForSize().
165   if (!F.hasFnAttribute(Attribute::OptimizeForSize))
166     Alignment = std::max(Alignment,
167                          STI->getTargetLowering()->getPrefFunctionAlignment());
168 
169   if (AlignAllFunctions)
170     Alignment = AlignAllFunctions;
171 
172   JumpTableInfo = nullptr;
173 
174   if (isFuncletEHPersonality(classifyEHPersonality(
175           F.hasPersonalityFn() ? F.getPersonalityFn() : nullptr))) {
176     WinEHInfo = new (Allocator) WinEHFuncInfo();
177   }
178 
179   if (isScopedEHPersonality(classifyEHPersonality(
180           F.hasPersonalityFn() ? F.getPersonalityFn() : nullptr))) {
181     WasmEHInfo = new (Allocator) WasmEHFuncInfo();
182   }
183 
184   assert(Target.isCompatibleDataLayout(getDataLayout()) &&
185          "Can't create a MachineFunction using a Module with a "
186          "Target-incompatible DataLayout attached\n");
187 
188   PSVManager =
189     llvm::make_unique<PseudoSourceValueManager>(*(getSubtarget().
190                                                   getInstrInfo()));
191 }
192 
193 MachineFunction::~MachineFunction() {
194   clear();
195 }
196 
197 void MachineFunction::clear() {
198   Properties.reset();
199   // Don't call destructors on MachineInstr and MachineOperand. All of their
200   // memory comes from the BumpPtrAllocator which is about to be purged.
201   //
202   // Do call MachineBasicBlock destructors, it contains std::vectors.
203   for (iterator I = begin(), E = end(); I != E; I = BasicBlocks.erase(I))
204     I->Insts.clearAndLeakNodesUnsafely();
205   MBBNumbering.clear();
206 
207   InstructionRecycler.clear(Allocator);
208   OperandRecycler.clear(Allocator);
209   BasicBlockRecycler.clear(Allocator);
210   CodeViewAnnotations.clear();
211   VariableDbgInfos.clear();
212   if (RegInfo) {
213     RegInfo->~MachineRegisterInfo();
214     Allocator.Deallocate(RegInfo);
215   }
216   if (MFInfo) {
217     MFInfo->~MachineFunctionInfo();
218     Allocator.Deallocate(MFInfo);
219   }
220 
221   FrameInfo->~MachineFrameInfo();
222   Allocator.Deallocate(FrameInfo);
223 
224   ConstantPool->~MachineConstantPool();
225   Allocator.Deallocate(ConstantPool);
226 
227   if (JumpTableInfo) {
228     JumpTableInfo->~MachineJumpTableInfo();
229     Allocator.Deallocate(JumpTableInfo);
230   }
231 
232   if (WinEHInfo) {
233     WinEHInfo->~WinEHFuncInfo();
234     Allocator.Deallocate(WinEHInfo);
235   }
236 }
237 
238 const DataLayout &MachineFunction::getDataLayout() const {
239   return F.getParent()->getDataLayout();
240 }
241 
242 /// Get the JumpTableInfo for this function.
243 /// If it does not already exist, allocate one.
244 MachineJumpTableInfo *MachineFunction::
245 getOrCreateJumpTableInfo(unsigned EntryKind) {
246   if (JumpTableInfo) return JumpTableInfo;
247 
248   JumpTableInfo = new (Allocator)
249     MachineJumpTableInfo((MachineJumpTableInfo::JTEntryKind)EntryKind);
250   return JumpTableInfo;
251 }
252 
253 /// Should we be emitting segmented stack stuff for the function
254 bool MachineFunction::shouldSplitStack() const {
255   return getFunction().hasFnAttribute("split-stack");
256 }
257 
258 /// This discards all of the MachineBasicBlock numbers and recomputes them.
259 /// This guarantees that the MBB numbers are sequential, dense, and match the
260 /// ordering of the blocks within the function.  If a specific MachineBasicBlock
261 /// is specified, only that block and those after it are renumbered.
262 void MachineFunction::RenumberBlocks(MachineBasicBlock *MBB) {
263   if (empty()) { MBBNumbering.clear(); return; }
264   MachineFunction::iterator MBBI, E = end();
265   if (MBB == nullptr)
266     MBBI = begin();
267   else
268     MBBI = MBB->getIterator();
269 
270   // Figure out the block number this should have.
271   unsigned BlockNo = 0;
272   if (MBBI != begin())
273     BlockNo = std::prev(MBBI)->getNumber() + 1;
274 
275   for (; MBBI != E; ++MBBI, ++BlockNo) {
276     if (MBBI->getNumber() != (int)BlockNo) {
277       // Remove use of the old number.
278       if (MBBI->getNumber() != -1) {
279         assert(MBBNumbering[MBBI->getNumber()] == &*MBBI &&
280                "MBB number mismatch!");
281         MBBNumbering[MBBI->getNumber()] = nullptr;
282       }
283 
284       // If BlockNo is already taken, set that block's number to -1.
285       if (MBBNumbering[BlockNo])
286         MBBNumbering[BlockNo]->setNumber(-1);
287 
288       MBBNumbering[BlockNo] = &*MBBI;
289       MBBI->setNumber(BlockNo);
290     }
291   }
292 
293   // Okay, all the blocks are renumbered.  If we have compactified the block
294   // numbering, shrink MBBNumbering now.
295   assert(BlockNo <= MBBNumbering.size() && "Mismatch!");
296   MBBNumbering.resize(BlockNo);
297 }
298 
299 /// Allocate a new MachineInstr. Use this instead of `new MachineInstr'.
300 MachineInstr *MachineFunction::CreateMachineInstr(const MCInstrDesc &MCID,
301                                                   const DebugLoc &DL,
302                                                   bool NoImp) {
303   return new (InstructionRecycler.Allocate<MachineInstr>(Allocator))
304     MachineInstr(*this, MCID, DL, NoImp);
305 }
306 
307 /// Create a new MachineInstr which is a copy of the 'Orig' instruction,
308 /// identical in all ways except the instruction has no parent, prev, or next.
309 MachineInstr *
310 MachineFunction::CloneMachineInstr(const MachineInstr *Orig) {
311   return new (InstructionRecycler.Allocate<MachineInstr>(Allocator))
312              MachineInstr(*this, *Orig);
313 }
314 
315 MachineInstr &MachineFunction::CloneMachineInstrBundle(MachineBasicBlock &MBB,
316     MachineBasicBlock::iterator InsertBefore, const MachineInstr &Orig) {
317   MachineInstr *FirstClone = nullptr;
318   MachineBasicBlock::const_instr_iterator I = Orig.getIterator();
319   while (true) {
320     MachineInstr *Cloned = CloneMachineInstr(&*I);
321     MBB.insert(InsertBefore, Cloned);
322     if (FirstClone == nullptr) {
323       FirstClone = Cloned;
324     } else {
325       Cloned->bundleWithPred();
326     }
327 
328     if (!I->isBundledWithSucc())
329       break;
330     ++I;
331   }
332   return *FirstClone;
333 }
334 
335 /// Delete the given MachineInstr.
336 ///
337 /// This function also serves as the MachineInstr destructor - the real
338 /// ~MachineInstr() destructor must be empty.
339 void
340 MachineFunction::DeleteMachineInstr(MachineInstr *MI) {
341   // Strip it for parts. The operand array and the MI object itself are
342   // independently recyclable.
343   if (MI->Operands)
344     deallocateOperandArray(MI->CapOperands, MI->Operands);
345   // Don't call ~MachineInstr() which must be trivial anyway because
346   // ~MachineFunction drops whole lists of MachineInstrs wihout calling their
347   // destructors.
348   InstructionRecycler.Deallocate(Allocator, MI);
349 }
350 
351 /// Allocate a new MachineBasicBlock. Use this instead of
352 /// `new MachineBasicBlock'.
353 MachineBasicBlock *
354 MachineFunction::CreateMachineBasicBlock(const BasicBlock *bb) {
355   return new (BasicBlockRecycler.Allocate<MachineBasicBlock>(Allocator))
356              MachineBasicBlock(*this, bb);
357 }
358 
359 /// Delete the given MachineBasicBlock.
360 void
361 MachineFunction::DeleteMachineBasicBlock(MachineBasicBlock *MBB) {
362   assert(MBB->getParent() == this && "MBB parent mismatch!");
363   MBB->~MachineBasicBlock();
364   BasicBlockRecycler.Deallocate(Allocator, MBB);
365 }
366 
367 MachineMemOperand *MachineFunction::getMachineMemOperand(
368     MachinePointerInfo PtrInfo, MachineMemOperand::Flags f, uint64_t s,
369     unsigned base_alignment, const AAMDNodes &AAInfo, const MDNode *Ranges,
370     SyncScope::ID SSID, AtomicOrdering Ordering,
371     AtomicOrdering FailureOrdering) {
372   return new (Allocator)
373       MachineMemOperand(PtrInfo, f, s, base_alignment, AAInfo, Ranges,
374                         SSID, Ordering, FailureOrdering);
375 }
376 
377 MachineMemOperand *
378 MachineFunction::getMachineMemOperand(const MachineMemOperand *MMO,
379                                       int64_t Offset, uint64_t Size) {
380   if (MMO->getValue())
381     return new (Allocator)
382                MachineMemOperand(MachinePointerInfo(MMO->getValue(),
383                                                     MMO->getOffset()+Offset),
384                                  MMO->getFlags(), Size, MMO->getBaseAlignment(),
385                                  AAMDNodes(), nullptr, MMO->getSyncScopeID(),
386                                  MMO->getOrdering(), MMO->getFailureOrdering());
387   return new (Allocator)
388              MachineMemOperand(MachinePointerInfo(MMO->getPseudoValue(),
389                                                   MMO->getOffset()+Offset),
390                                MMO->getFlags(), Size, MMO->getBaseAlignment(),
391                                AAMDNodes(), nullptr, MMO->getSyncScopeID(),
392                                MMO->getOrdering(), MMO->getFailureOrdering());
393 }
394 
395 MachineMemOperand *
396 MachineFunction::getMachineMemOperand(const MachineMemOperand *MMO,
397                                       const AAMDNodes &AAInfo) {
398   MachinePointerInfo MPI = MMO->getValue() ?
399              MachinePointerInfo(MMO->getValue(), MMO->getOffset()) :
400              MachinePointerInfo(MMO->getPseudoValue(), MMO->getOffset());
401 
402   return new (Allocator)
403              MachineMemOperand(MPI, MMO->getFlags(), MMO->getSize(),
404                                MMO->getBaseAlignment(), AAInfo,
405                                MMO->getRanges(), MMO->getSyncScopeID(),
406                                MMO->getOrdering(), MMO->getFailureOrdering());
407 }
408 
409 MachineInstr::ExtraInfo *
410 MachineFunction::createMIExtraInfo(ArrayRef<MachineMemOperand *> MMOs,
411                                    MCSymbol *PreInstrSymbol,
412                                    MCSymbol *PostInstrSymbol) {
413   return MachineInstr::ExtraInfo::create(Allocator, MMOs, PreInstrSymbol,
414                                          PostInstrSymbol);
415 }
416 
417 const char *MachineFunction::createExternalSymbolName(StringRef Name) {
418   char *Dest = Allocator.Allocate<char>(Name.size() + 1);
419   std::copy(Name.begin(), Name.end(), Dest);
420   Dest[Name.size()] = 0;
421   return Dest;
422 }
423 
424 uint32_t *MachineFunction::allocateRegMask() {
425   unsigned NumRegs = getSubtarget().getRegisterInfo()->getNumRegs();
426   unsigned Size = MachineOperand::getRegMaskSize(NumRegs);
427   uint32_t *Mask = Allocator.Allocate<uint32_t>(Size);
428   memset(Mask, 0, Size * sizeof(Mask[0]));
429   return Mask;
430 }
431 
432 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
433 LLVM_DUMP_METHOD void MachineFunction::dump() const {
434   print(dbgs());
435 }
436 #endif
437 
438 StringRef MachineFunction::getName() const {
439   return getFunction().getName();
440 }
441 
442 void MachineFunction::print(raw_ostream &OS, const SlotIndexes *Indexes) const {
443   OS << "# Machine code for function " << getName() << ": ";
444   getProperties().print(OS);
445   OS << '\n';
446 
447   // Print Frame Information
448   FrameInfo->print(*this, OS);
449 
450   // Print JumpTable Information
451   if (JumpTableInfo)
452     JumpTableInfo->print(OS);
453 
454   // Print Constant Pool
455   ConstantPool->print(OS);
456 
457   const TargetRegisterInfo *TRI = getSubtarget().getRegisterInfo();
458 
459   if (RegInfo && !RegInfo->livein_empty()) {
460     OS << "Function Live Ins: ";
461     for (MachineRegisterInfo::livein_iterator
462          I = RegInfo->livein_begin(), E = RegInfo->livein_end(); I != E; ++I) {
463       OS << printReg(I->first, TRI);
464       if (I->second)
465         OS << " in " << printReg(I->second, TRI);
466       if (std::next(I) != E)
467         OS << ", ";
468     }
469     OS << '\n';
470   }
471 
472   ModuleSlotTracker MST(getFunction().getParent());
473   MST.incorporateFunction(getFunction());
474   for (const auto &BB : *this) {
475     OS << '\n';
476     // If we print the whole function, print it at its most verbose level.
477     BB.print(OS, MST, Indexes, /*IsStandalone=*/true);
478   }
479 
480   OS << "\n# End machine code for function " << getName() << ".\n\n";
481 }
482 
483 namespace llvm {
484 
485   template<>
486   struct DOTGraphTraits<const MachineFunction*> : public DefaultDOTGraphTraits {
487     DOTGraphTraits(bool isSimple = false) : DefaultDOTGraphTraits(isSimple) {}
488 
489     static std::string getGraphName(const MachineFunction *F) {
490       return ("CFG for '" + F->getName() + "' function").str();
491     }
492 
493     std::string getNodeLabel(const MachineBasicBlock *Node,
494                              const MachineFunction *Graph) {
495       std::string OutStr;
496       {
497         raw_string_ostream OSS(OutStr);
498 
499         if (isSimple()) {
500           OSS << printMBBReference(*Node);
501           if (const BasicBlock *BB = Node->getBasicBlock())
502             OSS << ": " << BB->getName();
503         } else
504           Node->print(OSS);
505       }
506 
507       if (OutStr[0] == '\n') OutStr.erase(OutStr.begin());
508 
509       // Process string output to make it nicer...
510       for (unsigned i = 0; i != OutStr.length(); ++i)
511         if (OutStr[i] == '\n') {                            // Left justify
512           OutStr[i] = '\\';
513           OutStr.insert(OutStr.begin()+i+1, 'l');
514         }
515       return OutStr;
516     }
517   };
518 
519 } // end namespace llvm
520 
521 void MachineFunction::viewCFG() const
522 {
523 #ifndef NDEBUG
524   ViewGraph(this, "mf" + getName());
525 #else
526   errs() << "MachineFunction::viewCFG is only available in debug builds on "
527          << "systems with Graphviz or gv!\n";
528 #endif // NDEBUG
529 }
530 
531 void MachineFunction::viewCFGOnly() const
532 {
533 #ifndef NDEBUG
534   ViewGraph(this, "mf" + getName(), true);
535 #else
536   errs() << "MachineFunction::viewCFGOnly is only available in debug builds on "
537          << "systems with Graphviz or gv!\n";
538 #endif // NDEBUG
539 }
540 
541 /// Add the specified physical register as a live-in value and
542 /// create a corresponding virtual register for it.
543 unsigned MachineFunction::addLiveIn(unsigned PReg,
544                                     const TargetRegisterClass *RC) {
545   MachineRegisterInfo &MRI = getRegInfo();
546   unsigned VReg = MRI.getLiveInVirtReg(PReg);
547   if (VReg) {
548     const TargetRegisterClass *VRegRC = MRI.getRegClass(VReg);
549     (void)VRegRC;
550     // A physical register can be added several times.
551     // Between two calls, the register class of the related virtual register
552     // may have been constrained to match some operation constraints.
553     // In that case, check that the current register class includes the
554     // physical register and is a sub class of the specified RC.
555     assert((VRegRC == RC || (VRegRC->contains(PReg) &&
556                              RC->hasSubClassEq(VRegRC))) &&
557             "Register class mismatch!");
558     return VReg;
559   }
560   VReg = MRI.createVirtualRegister(RC);
561   MRI.addLiveIn(PReg, VReg);
562   return VReg;
563 }
564 
565 /// Return the MCSymbol for the specified non-empty jump table.
566 /// If isLinkerPrivate is specified, an 'l' label is returned, otherwise a
567 /// normal 'L' label is returned.
568 MCSymbol *MachineFunction::getJTISymbol(unsigned JTI, MCContext &Ctx,
569                                         bool isLinkerPrivate) const {
570   const DataLayout &DL = getDataLayout();
571   assert(JumpTableInfo && "No jump tables");
572   assert(JTI < JumpTableInfo->getJumpTables().size() && "Invalid JTI!");
573 
574   StringRef Prefix = isLinkerPrivate ? DL.getLinkerPrivateGlobalPrefix()
575                                      : DL.getPrivateGlobalPrefix();
576   SmallString<60> Name;
577   raw_svector_ostream(Name)
578     << Prefix << "JTI" << getFunctionNumber() << '_' << JTI;
579   return Ctx.getOrCreateSymbol(Name);
580 }
581 
582 /// Return a function-local symbol to represent the PIC base.
583 MCSymbol *MachineFunction::getPICBaseSymbol() const {
584   const DataLayout &DL = getDataLayout();
585   return Ctx.getOrCreateSymbol(Twine(DL.getPrivateGlobalPrefix()) +
586                                Twine(getFunctionNumber()) + "$pb");
587 }
588 
589 /// \name Exception Handling
590 /// \{
591 
592 LandingPadInfo &
593 MachineFunction::getOrCreateLandingPadInfo(MachineBasicBlock *LandingPad) {
594   unsigned N = LandingPads.size();
595   for (unsigned i = 0; i < N; ++i) {
596     LandingPadInfo &LP = LandingPads[i];
597     if (LP.LandingPadBlock == LandingPad)
598       return LP;
599   }
600 
601   LandingPads.push_back(LandingPadInfo(LandingPad));
602   return LandingPads[N];
603 }
604 
605 void MachineFunction::addInvoke(MachineBasicBlock *LandingPad,
606                                 MCSymbol *BeginLabel, MCSymbol *EndLabel) {
607   LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
608   LP.BeginLabels.push_back(BeginLabel);
609   LP.EndLabels.push_back(EndLabel);
610 }
611 
612 MCSymbol *MachineFunction::addLandingPad(MachineBasicBlock *LandingPad) {
613   MCSymbol *LandingPadLabel = Ctx.createTempSymbol();
614   LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
615   LP.LandingPadLabel = LandingPadLabel;
616   return LandingPadLabel;
617 }
618 
619 void MachineFunction::addCatchTypeInfo(MachineBasicBlock *LandingPad,
620                                        ArrayRef<const GlobalValue *> TyInfo) {
621   LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
622   for (unsigned N = TyInfo.size(); N; --N)
623     LP.TypeIds.push_back(getTypeIDFor(TyInfo[N - 1]));
624 }
625 
626 void MachineFunction::addFilterTypeInfo(MachineBasicBlock *LandingPad,
627                                         ArrayRef<const GlobalValue *> TyInfo) {
628   LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
629   std::vector<unsigned> IdsInFilter(TyInfo.size());
630   for (unsigned I = 0, E = TyInfo.size(); I != E; ++I)
631     IdsInFilter[I] = getTypeIDFor(TyInfo[I]);
632   LP.TypeIds.push_back(getFilterIDFor(IdsInFilter));
633 }
634 
635 void MachineFunction::tidyLandingPads(DenseMap<MCSymbol*, uintptr_t> *LPMap) {
636   for (unsigned i = 0; i != LandingPads.size(); ) {
637     LandingPadInfo &LandingPad = LandingPads[i];
638     if (LandingPad.LandingPadLabel &&
639         !LandingPad.LandingPadLabel->isDefined() &&
640         (!LPMap || (*LPMap)[LandingPad.LandingPadLabel] == 0))
641       LandingPad.LandingPadLabel = nullptr;
642 
643     // Special case: we *should* emit LPs with null LP MBB. This indicates
644     // "nounwind" case.
645     if (!LandingPad.LandingPadLabel && LandingPad.LandingPadBlock) {
646       LandingPads.erase(LandingPads.begin() + i);
647       continue;
648     }
649 
650     for (unsigned j = 0, e = LandingPads[i].BeginLabels.size(); j != e; ++j) {
651       MCSymbol *BeginLabel = LandingPad.BeginLabels[j];
652       MCSymbol *EndLabel = LandingPad.EndLabels[j];
653       if ((BeginLabel->isDefined() ||
654            (LPMap && (*LPMap)[BeginLabel] != 0)) &&
655           (EndLabel->isDefined() ||
656            (LPMap && (*LPMap)[EndLabel] != 0))) continue;
657 
658       LandingPad.BeginLabels.erase(LandingPad.BeginLabels.begin() + j);
659       LandingPad.EndLabels.erase(LandingPad.EndLabels.begin() + j);
660       --j;
661       --e;
662     }
663 
664     // Remove landing pads with no try-ranges.
665     if (LandingPads[i].BeginLabels.empty()) {
666       LandingPads.erase(LandingPads.begin() + i);
667       continue;
668     }
669 
670     // If there is no landing pad, ensure that the list of typeids is empty.
671     // If the only typeid is a cleanup, this is the same as having no typeids.
672     if (!LandingPad.LandingPadBlock ||
673         (LandingPad.TypeIds.size() == 1 && !LandingPad.TypeIds[0]))
674       LandingPad.TypeIds.clear();
675     ++i;
676   }
677 }
678 
679 void MachineFunction::addCleanup(MachineBasicBlock *LandingPad) {
680   LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
681   LP.TypeIds.push_back(0);
682 }
683 
684 void MachineFunction::addSEHCatchHandler(MachineBasicBlock *LandingPad,
685                                          const Function *Filter,
686                                          const BlockAddress *RecoverBA) {
687   LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
688   SEHHandler Handler;
689   Handler.FilterOrFinally = Filter;
690   Handler.RecoverBA = RecoverBA;
691   LP.SEHHandlers.push_back(Handler);
692 }
693 
694 void MachineFunction::addSEHCleanupHandler(MachineBasicBlock *LandingPad,
695                                            const Function *Cleanup) {
696   LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
697   SEHHandler Handler;
698   Handler.FilterOrFinally = Cleanup;
699   Handler.RecoverBA = nullptr;
700   LP.SEHHandlers.push_back(Handler);
701 }
702 
703 void MachineFunction::setCallSiteLandingPad(MCSymbol *Sym,
704                                             ArrayRef<unsigned> Sites) {
705   LPadToCallSiteMap[Sym].append(Sites.begin(), Sites.end());
706 }
707 
708 unsigned MachineFunction::getTypeIDFor(const GlobalValue *TI) {
709   for (unsigned i = 0, N = TypeInfos.size(); i != N; ++i)
710     if (TypeInfos[i] == TI) return i + 1;
711 
712   TypeInfos.push_back(TI);
713   return TypeInfos.size();
714 }
715 
716 int MachineFunction::getFilterIDFor(std::vector<unsigned> &TyIds) {
717   // If the new filter coincides with the tail of an existing filter, then
718   // re-use the existing filter.  Folding filters more than this requires
719   // re-ordering filters and/or their elements - probably not worth it.
720   for (std::vector<unsigned>::iterator I = FilterEnds.begin(),
721        E = FilterEnds.end(); I != E; ++I) {
722     unsigned i = *I, j = TyIds.size();
723 
724     while (i && j)
725       if (FilterIds[--i] != TyIds[--j])
726         goto try_next;
727 
728     if (!j)
729       // The new filter coincides with range [i, end) of the existing filter.
730       return -(1 + i);
731 
732 try_next:;
733   }
734 
735   // Add the new filter.
736   int FilterID = -(1 + FilterIds.size());
737   FilterIds.reserve(FilterIds.size() + TyIds.size() + 1);
738   FilterIds.insert(FilterIds.end(), TyIds.begin(), TyIds.end());
739   FilterEnds.push_back(FilterIds.size());
740   FilterIds.push_back(0); // terminator
741   return FilterID;
742 }
743 
744 void llvm::addLandingPadInfo(const LandingPadInst &I, MachineBasicBlock &MBB) {
745   MachineFunction &MF = *MBB.getParent();
746   if (const auto *PF = dyn_cast<Function>(
747           I.getParent()->getParent()->getPersonalityFn()->stripPointerCasts()))
748     MF.getMMI().addPersonality(PF);
749 
750   if (I.isCleanup())
751     MF.addCleanup(&MBB);
752 
753   // FIXME: New EH - Add the clauses in reverse order. This isn't 100% correct,
754   //        but we need to do it this way because of how the DWARF EH emitter
755   //        processes the clauses.
756   for (unsigned i = I.getNumClauses(); i != 0; --i) {
757     Value *Val = I.getClause(i - 1);
758     if (I.isCatch(i - 1)) {
759       MF.addCatchTypeInfo(&MBB,
760                           dyn_cast<GlobalValue>(Val->stripPointerCasts()));
761     } else {
762       // Add filters in a list.
763       Constant *CVal = cast<Constant>(Val);
764       SmallVector<const GlobalValue *, 4> FilterList;
765       for (User::op_iterator II = CVal->op_begin(), IE = CVal->op_end();
766            II != IE; ++II)
767         FilterList.push_back(cast<GlobalValue>((*II)->stripPointerCasts()));
768 
769       MF.addFilterTypeInfo(&MBB, FilterList);
770     }
771   }
772 }
773 
774 /// \}
775 
776 //===----------------------------------------------------------------------===//
777 //  MachineJumpTableInfo implementation
778 //===----------------------------------------------------------------------===//
779 
780 /// Return the size of each entry in the jump table.
781 unsigned MachineJumpTableInfo::getEntrySize(const DataLayout &TD) const {
782   // The size of a jump table entry is 4 bytes unless the entry is just the
783   // address of a block, in which case it is the pointer size.
784   switch (getEntryKind()) {
785   case MachineJumpTableInfo::EK_BlockAddress:
786     return TD.getPointerSize();
787   case MachineJumpTableInfo::EK_GPRel64BlockAddress:
788     return 8;
789   case MachineJumpTableInfo::EK_GPRel32BlockAddress:
790   case MachineJumpTableInfo::EK_LabelDifference32:
791   case MachineJumpTableInfo::EK_Custom32:
792     return 4;
793   case MachineJumpTableInfo::EK_Inline:
794     return 0;
795   }
796   llvm_unreachable("Unknown jump table encoding!");
797 }
798 
799 /// Return the alignment of each entry in the jump table.
800 unsigned MachineJumpTableInfo::getEntryAlignment(const DataLayout &TD) const {
801   // The alignment of a jump table entry is the alignment of int32 unless the
802   // entry is just the address of a block, in which case it is the pointer
803   // alignment.
804   switch (getEntryKind()) {
805   case MachineJumpTableInfo::EK_BlockAddress:
806     return TD.getPointerABIAlignment(0);
807   case MachineJumpTableInfo::EK_GPRel64BlockAddress:
808     return TD.getABIIntegerTypeAlignment(64);
809   case MachineJumpTableInfo::EK_GPRel32BlockAddress:
810   case MachineJumpTableInfo::EK_LabelDifference32:
811   case MachineJumpTableInfo::EK_Custom32:
812     return TD.getABIIntegerTypeAlignment(32);
813   case MachineJumpTableInfo::EK_Inline:
814     return 1;
815   }
816   llvm_unreachable("Unknown jump table encoding!");
817 }
818 
819 /// Create a new jump table entry in the jump table info.
820 unsigned MachineJumpTableInfo::createJumpTableIndex(
821                                const std::vector<MachineBasicBlock*> &DestBBs) {
822   assert(!DestBBs.empty() && "Cannot create an empty jump table!");
823   JumpTables.push_back(MachineJumpTableEntry(DestBBs));
824   return JumpTables.size()-1;
825 }
826 
827 /// If Old is the target of any jump tables, update the jump tables to branch
828 /// to New instead.
829 bool MachineJumpTableInfo::ReplaceMBBInJumpTables(MachineBasicBlock *Old,
830                                                   MachineBasicBlock *New) {
831   assert(Old != New && "Not making a change?");
832   bool MadeChange = false;
833   for (size_t i = 0, e = JumpTables.size(); i != e; ++i)
834     ReplaceMBBInJumpTable(i, Old, New);
835   return MadeChange;
836 }
837 
838 /// If Old is a target of the jump tables, update the jump table to branch to
839 /// New instead.
840 bool MachineJumpTableInfo::ReplaceMBBInJumpTable(unsigned Idx,
841                                                  MachineBasicBlock *Old,
842                                                  MachineBasicBlock *New) {
843   assert(Old != New && "Not making a change?");
844   bool MadeChange = false;
845   MachineJumpTableEntry &JTE = JumpTables[Idx];
846   for (size_t j = 0, e = JTE.MBBs.size(); j != e; ++j)
847     if (JTE.MBBs[j] == Old) {
848       JTE.MBBs[j] = New;
849       MadeChange = true;
850     }
851   return MadeChange;
852 }
853 
854 void MachineJumpTableInfo::print(raw_ostream &OS) const {
855   if (JumpTables.empty()) return;
856 
857   OS << "Jump Tables:\n";
858 
859   for (unsigned i = 0, e = JumpTables.size(); i != e; ++i) {
860     OS << printJumpTableEntryReference(i) << ": ";
861     for (unsigned j = 0, f = JumpTables[i].MBBs.size(); j != f; ++j)
862       OS << ' ' << printMBBReference(*JumpTables[i].MBBs[j]);
863   }
864 
865   OS << '\n';
866 }
867 
868 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
869 LLVM_DUMP_METHOD void MachineJumpTableInfo::dump() const { print(dbgs()); }
870 #endif
871 
872 Printable llvm::printJumpTableEntryReference(unsigned Idx) {
873   return Printable([Idx](raw_ostream &OS) { OS << "%jump-table." << Idx; });
874 }
875 
876 //===----------------------------------------------------------------------===//
877 //  MachineConstantPool implementation
878 //===----------------------------------------------------------------------===//
879 
880 void MachineConstantPoolValue::anchor() {}
881 
882 Type *MachineConstantPoolEntry::getType() const {
883   if (isMachineConstantPoolEntry())
884     return Val.MachineCPVal->getType();
885   return Val.ConstVal->getType();
886 }
887 
888 bool MachineConstantPoolEntry::needsRelocation() const {
889   if (isMachineConstantPoolEntry())
890     return true;
891   return Val.ConstVal->needsRelocation();
892 }
893 
894 SectionKind
895 MachineConstantPoolEntry::getSectionKind(const DataLayout *DL) const {
896   if (needsRelocation())
897     return SectionKind::getReadOnlyWithRel();
898   switch (DL->getTypeAllocSize(getType())) {
899   case 4:
900     return SectionKind::getMergeableConst4();
901   case 8:
902     return SectionKind::getMergeableConst8();
903   case 16:
904     return SectionKind::getMergeableConst16();
905   case 32:
906     return SectionKind::getMergeableConst32();
907   default:
908     return SectionKind::getReadOnly();
909   }
910 }
911 
912 MachineConstantPool::~MachineConstantPool() {
913   // A constant may be a member of both Constants and MachineCPVsSharingEntries,
914   // so keep track of which we've deleted to avoid double deletions.
915   DenseSet<MachineConstantPoolValue*> Deleted;
916   for (unsigned i = 0, e = Constants.size(); i != e; ++i)
917     if (Constants[i].isMachineConstantPoolEntry()) {
918       Deleted.insert(Constants[i].Val.MachineCPVal);
919       delete Constants[i].Val.MachineCPVal;
920     }
921   for (DenseSet<MachineConstantPoolValue*>::iterator I =
922        MachineCPVsSharingEntries.begin(), E = MachineCPVsSharingEntries.end();
923        I != E; ++I) {
924     if (Deleted.count(*I) == 0)
925       delete *I;
926   }
927 }
928 
929 /// Test whether the given two constants can be allocated the same constant pool
930 /// entry.
931 static bool CanShareConstantPoolEntry(const Constant *A, const Constant *B,
932                                       const DataLayout &DL) {
933   // Handle the trivial case quickly.
934   if (A == B) return true;
935 
936   // If they have the same type but weren't the same constant, quickly
937   // reject them.
938   if (A->getType() == B->getType()) return false;
939 
940   // We can't handle structs or arrays.
941   if (isa<StructType>(A->getType()) || isa<ArrayType>(A->getType()) ||
942       isa<StructType>(B->getType()) || isa<ArrayType>(B->getType()))
943     return false;
944 
945   // For now, only support constants with the same size.
946   uint64_t StoreSize = DL.getTypeStoreSize(A->getType());
947   if (StoreSize != DL.getTypeStoreSize(B->getType()) || StoreSize > 128)
948     return false;
949 
950   Type *IntTy = IntegerType::get(A->getContext(), StoreSize*8);
951 
952   // Try constant folding a bitcast of both instructions to an integer.  If we
953   // get two identical ConstantInt's, then we are good to share them.  We use
954   // the constant folding APIs to do this so that we get the benefit of
955   // DataLayout.
956   if (isa<PointerType>(A->getType()))
957     A = ConstantFoldCastOperand(Instruction::PtrToInt,
958                                 const_cast<Constant *>(A), IntTy, DL);
959   else if (A->getType() != IntTy)
960     A = ConstantFoldCastOperand(Instruction::BitCast, const_cast<Constant *>(A),
961                                 IntTy, DL);
962   if (isa<PointerType>(B->getType()))
963     B = ConstantFoldCastOperand(Instruction::PtrToInt,
964                                 const_cast<Constant *>(B), IntTy, DL);
965   else if (B->getType() != IntTy)
966     B = ConstantFoldCastOperand(Instruction::BitCast, const_cast<Constant *>(B),
967                                 IntTy, DL);
968 
969   return A == B;
970 }
971 
972 /// Create a new entry in the constant pool or return an existing one.
973 /// User must specify the log2 of the minimum required alignment for the object.
974 unsigned MachineConstantPool::getConstantPoolIndex(const Constant *C,
975                                                    unsigned Alignment) {
976   assert(Alignment && "Alignment must be specified!");
977   if (Alignment > PoolAlignment) PoolAlignment = Alignment;
978 
979   // Check to see if we already have this constant.
980   //
981   // FIXME, this could be made much more efficient for large constant pools.
982   for (unsigned i = 0, e = Constants.size(); i != e; ++i)
983     if (!Constants[i].isMachineConstantPoolEntry() &&
984         CanShareConstantPoolEntry(Constants[i].Val.ConstVal, C, DL)) {
985       if ((unsigned)Constants[i].getAlignment() < Alignment)
986         Constants[i].Alignment = Alignment;
987       return i;
988     }
989 
990   Constants.push_back(MachineConstantPoolEntry(C, Alignment));
991   return Constants.size()-1;
992 }
993 
994 unsigned MachineConstantPool::getConstantPoolIndex(MachineConstantPoolValue *V,
995                                                    unsigned Alignment) {
996   assert(Alignment && "Alignment must be specified!");
997   if (Alignment > PoolAlignment) PoolAlignment = Alignment;
998 
999   // Check to see if we already have this constant.
1000   //
1001   // FIXME, this could be made much more efficient for large constant pools.
1002   int Idx = V->getExistingMachineCPValue(this, Alignment);
1003   if (Idx != -1) {
1004     MachineCPVsSharingEntries.insert(V);
1005     return (unsigned)Idx;
1006   }
1007 
1008   Constants.push_back(MachineConstantPoolEntry(V, Alignment));
1009   return Constants.size()-1;
1010 }
1011 
1012 void MachineConstantPool::print(raw_ostream &OS) const {
1013   if (Constants.empty()) return;
1014 
1015   OS << "Constant Pool:\n";
1016   for (unsigned i = 0, e = Constants.size(); i != e; ++i) {
1017     OS << "  cp#" << i << ": ";
1018     if (Constants[i].isMachineConstantPoolEntry())
1019       Constants[i].Val.MachineCPVal->print(OS);
1020     else
1021       Constants[i].Val.ConstVal->printAsOperand(OS, /*PrintType=*/false);
1022     OS << ", align=" << Constants[i].getAlignment();
1023     OS << "\n";
1024   }
1025 }
1026 
1027 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1028 LLVM_DUMP_METHOD void MachineConstantPool::dump() const { print(dbgs()); }
1029 #endif
1030