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      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/STLExtras.h"
     18 #include "llvm/ADT/SmallString.h"
     19 #include "llvm/Analysis/ConstantFolding.h"
     20 #include "llvm/Analysis/EHPersonalities.h"
     21 #include "llvm/CodeGen/MachineConstantPool.h"
     22 #include "llvm/CodeGen/MachineFrameInfo.h"
     23 #include "llvm/CodeGen/MachineFunctionInitializer.h"
     24 #include "llvm/CodeGen/MachineFunctionPass.h"
     25 #include "llvm/CodeGen/MachineInstr.h"
     26 #include "llvm/CodeGen/MachineJumpTableInfo.h"
     27 #include "llvm/CodeGen/MachineModuleInfo.h"
     28 #include "llvm/CodeGen/MachineRegisterInfo.h"
     29 #include "llvm/CodeGen/Passes.h"
     30 #include "llvm/CodeGen/PseudoSourceValue.h"
     31 #include "llvm/CodeGen/WinEHFuncInfo.h"
     32 #include "llvm/IR/DataLayout.h"
     33 #include "llvm/IR/DebugInfo.h"
     34 #include "llvm/IR/Function.h"
     35 #include "llvm/IR/Module.h"
     36 #include "llvm/IR/ModuleSlotTracker.h"
     37 #include "llvm/MC/MCAsmInfo.h"
     38 #include "llvm/MC/MCContext.h"
     39 #include "llvm/Support/Debug.h"
     40 #include "llvm/Support/GraphWriter.h"
     41 #include "llvm/Support/raw_ostream.h"
     42 #include "llvm/Target/TargetFrameLowering.h"
     43 #include "llvm/Target/TargetLowering.h"
     44 #include "llvm/Target/TargetMachine.h"
     45 #include "llvm/Target/TargetSubtargetInfo.h"
     46 using namespace llvm;
     47 
     48 #define DEBUG_TYPE "codegen"
     49 
     50 void MachineFunctionInitializer::anchor() {}
     51 
     52 //===----------------------------------------------------------------------===//
     53 // MachineFunction implementation
     54 //===----------------------------------------------------------------------===//
     55 
     56 // Out-of-line virtual method.
     57 MachineFunctionInfo::~MachineFunctionInfo() {}
     58 
     59 void ilist_traits<MachineBasicBlock>::deleteNode(MachineBasicBlock *MBB) {
     60   MBB->getParent()->DeleteMachineBasicBlock(MBB);
     61 }
     62 
     63 MachineFunction::MachineFunction(const Function *F, const TargetMachine &TM,
     64                                  unsigned FunctionNum, MachineModuleInfo &mmi)
     65     : Fn(F), Target(TM), STI(TM.getSubtargetImpl(*F)), Ctx(mmi.getContext()),
     66       MMI(mmi) {
     67   if (STI->getRegisterInfo())
     68     RegInfo = new (Allocator) MachineRegisterInfo(this);
     69   else
     70     RegInfo = nullptr;
     71 
     72   MFInfo = nullptr;
     73   FrameInfo = new (Allocator)
     74       MachineFrameInfo(STI->getFrameLowering()->getStackAlignment(),
     75                        STI->getFrameLowering()->isStackRealignable(),
     76                        !F->hasFnAttribute("no-realign-stack"));
     77 
     78   if (Fn->hasFnAttribute(Attribute::StackAlignment))
     79     FrameInfo->ensureMaxAlignment(Fn->getFnStackAlignment());
     80 
     81   ConstantPool = new (Allocator) MachineConstantPool(getDataLayout());
     82   Alignment = STI->getTargetLowering()->getMinFunctionAlignment();
     83 
     84   // FIXME: Shouldn't use pref alignment if explicit alignment is set on Fn.
     85   // FIXME: Use Function::optForSize().
     86   if (!Fn->hasFnAttribute(Attribute::OptimizeForSize))
     87     Alignment = std::max(Alignment,
     88                          STI->getTargetLowering()->getPrefFunctionAlignment());
     89 
     90   FunctionNumber = FunctionNum;
     91   JumpTableInfo = nullptr;
     92 
     93   if (isFuncletEHPersonality(classifyEHPersonality(
     94           F->hasPersonalityFn() ? F->getPersonalityFn() : nullptr))) {
     95     WinEHInfo = new (Allocator) WinEHFuncInfo();
     96   }
     97 
     98   assert(TM.isCompatibleDataLayout(getDataLayout()) &&
     99          "Can't create a MachineFunction using a Module with a "
    100          "Target-incompatible DataLayout attached\n");
    101 
    102   PSVManager = llvm::make_unique<PseudoSourceValueManager>();
    103 }
    104 
    105 MachineFunction::~MachineFunction() {
    106   // Don't call destructors on MachineInstr and MachineOperand. All of their
    107   // memory comes from the BumpPtrAllocator which is about to be purged.
    108   //
    109   // Do call MachineBasicBlock destructors, it contains std::vectors.
    110   for (iterator I = begin(), E = end(); I != E; I = BasicBlocks.erase(I))
    111     I->Insts.clearAndLeakNodesUnsafely();
    112 
    113   InstructionRecycler.clear(Allocator);
    114   OperandRecycler.clear(Allocator);
    115   BasicBlockRecycler.clear(Allocator);
    116   if (RegInfo) {
    117     RegInfo->~MachineRegisterInfo();
    118     Allocator.Deallocate(RegInfo);
    119   }
    120   if (MFInfo) {
    121     MFInfo->~MachineFunctionInfo();
    122     Allocator.Deallocate(MFInfo);
    123   }
    124 
    125   FrameInfo->~MachineFrameInfo();
    126   Allocator.Deallocate(FrameInfo);
    127 
    128   ConstantPool->~MachineConstantPool();
    129   Allocator.Deallocate(ConstantPool);
    130 
    131   if (JumpTableInfo) {
    132     JumpTableInfo->~MachineJumpTableInfo();
    133     Allocator.Deallocate(JumpTableInfo);
    134   }
    135 
    136   if (WinEHInfo) {
    137     WinEHInfo->~WinEHFuncInfo();
    138     Allocator.Deallocate(WinEHInfo);
    139   }
    140 }
    141 
    142 const DataLayout &MachineFunction::getDataLayout() const {
    143   return Fn->getParent()->getDataLayout();
    144 }
    145 
    146 /// Get the JumpTableInfo for this function.
    147 /// If it does not already exist, allocate one.
    148 MachineJumpTableInfo *MachineFunction::
    149 getOrCreateJumpTableInfo(unsigned EntryKind) {
    150   if (JumpTableInfo) return JumpTableInfo;
    151 
    152   JumpTableInfo = new (Allocator)
    153     MachineJumpTableInfo((MachineJumpTableInfo::JTEntryKind)EntryKind);
    154   return JumpTableInfo;
    155 }
    156 
    157 /// Should we be emitting segmented stack stuff for the function
    158 bool MachineFunction::shouldSplitStack() {
    159   return getFunction()->hasFnAttribute("split-stack");
    160 }
    161 
    162 /// This discards all of the MachineBasicBlock numbers and recomputes them.
    163 /// This guarantees that the MBB numbers are sequential, dense, and match the
    164 /// ordering of the blocks within the function.  If a specific MachineBasicBlock
    165 /// is specified, only that block and those after it are renumbered.
    166 void MachineFunction::RenumberBlocks(MachineBasicBlock *MBB) {
    167   if (empty()) { MBBNumbering.clear(); return; }
    168   MachineFunction::iterator MBBI, E = end();
    169   if (MBB == nullptr)
    170     MBBI = begin();
    171   else
    172     MBBI = MBB->getIterator();
    173 
    174   // Figure out the block number this should have.
    175   unsigned BlockNo = 0;
    176   if (MBBI != begin())
    177     BlockNo = std::prev(MBBI)->getNumber() + 1;
    178 
    179   for (; MBBI != E; ++MBBI, ++BlockNo) {
    180     if (MBBI->getNumber() != (int)BlockNo) {
    181       // Remove use of the old number.
    182       if (MBBI->getNumber() != -1) {
    183         assert(MBBNumbering[MBBI->getNumber()] == &*MBBI &&
    184                "MBB number mismatch!");
    185         MBBNumbering[MBBI->getNumber()] = nullptr;
    186       }
    187 
    188       // If BlockNo is already taken, set that block's number to -1.
    189       if (MBBNumbering[BlockNo])
    190         MBBNumbering[BlockNo]->setNumber(-1);
    191 
    192       MBBNumbering[BlockNo] = &*MBBI;
    193       MBBI->setNumber(BlockNo);
    194     }
    195   }
    196 
    197   // Okay, all the blocks are renumbered.  If we have compactified the block
    198   // numbering, shrink MBBNumbering now.
    199   assert(BlockNo <= MBBNumbering.size() && "Mismatch!");
    200   MBBNumbering.resize(BlockNo);
    201 }
    202 
    203 /// Allocate a new MachineInstr. Use this instead of `new MachineInstr'.
    204 MachineInstr *
    205 MachineFunction::CreateMachineInstr(const MCInstrDesc &MCID,
    206                                     DebugLoc DL, bool NoImp) {
    207   return new (InstructionRecycler.Allocate<MachineInstr>(Allocator))
    208     MachineInstr(*this, MCID, DL, NoImp);
    209 }
    210 
    211 /// Create a new MachineInstr which is a copy of the 'Orig' instruction,
    212 /// identical in all ways except the instruction has no parent, prev, or next.
    213 MachineInstr *
    214 MachineFunction::CloneMachineInstr(const MachineInstr *Orig) {
    215   return new (InstructionRecycler.Allocate<MachineInstr>(Allocator))
    216              MachineInstr(*this, *Orig);
    217 }
    218 
    219 /// Delete the given MachineInstr.
    220 ///
    221 /// This function also serves as the MachineInstr destructor - the real
    222 /// ~MachineInstr() destructor must be empty.
    223 void
    224 MachineFunction::DeleteMachineInstr(MachineInstr *MI) {
    225   // Strip it for parts. The operand array and the MI object itself are
    226   // independently recyclable.
    227   if (MI->Operands)
    228     deallocateOperandArray(MI->CapOperands, MI->Operands);
    229   // Don't call ~MachineInstr() which must be trivial anyway because
    230   // ~MachineFunction drops whole lists of MachineInstrs wihout calling their
    231   // destructors.
    232   InstructionRecycler.Deallocate(Allocator, MI);
    233 }
    234 
    235 /// Allocate a new MachineBasicBlock. Use this instead of
    236 /// `new MachineBasicBlock'.
    237 MachineBasicBlock *
    238 MachineFunction::CreateMachineBasicBlock(const BasicBlock *bb) {
    239   return new (BasicBlockRecycler.Allocate<MachineBasicBlock>(Allocator))
    240              MachineBasicBlock(*this, bb);
    241 }
    242 
    243 /// Delete the given MachineBasicBlock.
    244 void
    245 MachineFunction::DeleteMachineBasicBlock(MachineBasicBlock *MBB) {
    246   assert(MBB->getParent() == this && "MBB parent mismatch!");
    247   MBB->~MachineBasicBlock();
    248   BasicBlockRecycler.Deallocate(Allocator, MBB);
    249 }
    250 
    251 MachineMemOperand *
    252 MachineFunction::getMachineMemOperand(MachinePointerInfo PtrInfo, unsigned f,
    253                                       uint64_t s, unsigned base_alignment,
    254                                       const AAMDNodes &AAInfo,
    255                                       const MDNode *Ranges) {
    256   return new (Allocator) MachineMemOperand(PtrInfo, f, s, base_alignment,
    257                                            AAInfo, Ranges);
    258 }
    259 
    260 MachineMemOperand *
    261 MachineFunction::getMachineMemOperand(const MachineMemOperand *MMO,
    262                                       int64_t Offset, uint64_t Size) {
    263   if (MMO->getValue())
    264     return new (Allocator)
    265                MachineMemOperand(MachinePointerInfo(MMO->getValue(),
    266                                                     MMO->getOffset()+Offset),
    267                                  MMO->getFlags(), Size,
    268                                  MMO->getBaseAlignment());
    269   return new (Allocator)
    270              MachineMemOperand(MachinePointerInfo(MMO->getPseudoValue(),
    271                                                   MMO->getOffset()+Offset),
    272                                MMO->getFlags(), Size,
    273                                MMO->getBaseAlignment());
    274 }
    275 
    276 MachineInstr::mmo_iterator
    277 MachineFunction::allocateMemRefsArray(unsigned long Num) {
    278   return Allocator.Allocate<MachineMemOperand *>(Num);
    279 }
    280 
    281 std::pair<MachineInstr::mmo_iterator, MachineInstr::mmo_iterator>
    282 MachineFunction::extractLoadMemRefs(MachineInstr::mmo_iterator Begin,
    283                                     MachineInstr::mmo_iterator End) {
    284   // Count the number of load mem refs.
    285   unsigned Num = 0;
    286   for (MachineInstr::mmo_iterator I = Begin; I != End; ++I)
    287     if ((*I)->isLoad())
    288       ++Num;
    289 
    290   // Allocate a new array and populate it with the load information.
    291   MachineInstr::mmo_iterator Result = allocateMemRefsArray(Num);
    292   unsigned Index = 0;
    293   for (MachineInstr::mmo_iterator I = Begin; I != End; ++I) {
    294     if ((*I)->isLoad()) {
    295       if (!(*I)->isStore())
    296         // Reuse the MMO.
    297         Result[Index] = *I;
    298       else {
    299         // Clone the MMO and unset the store flag.
    300         MachineMemOperand *JustLoad =
    301           getMachineMemOperand((*I)->getPointerInfo(),
    302                                (*I)->getFlags() & ~MachineMemOperand::MOStore,
    303                                (*I)->getSize(), (*I)->getBaseAlignment(),
    304                                (*I)->getAAInfo());
    305         Result[Index] = JustLoad;
    306       }
    307       ++Index;
    308     }
    309   }
    310   return std::make_pair(Result, Result + Num);
    311 }
    312 
    313 std::pair<MachineInstr::mmo_iterator, MachineInstr::mmo_iterator>
    314 MachineFunction::extractStoreMemRefs(MachineInstr::mmo_iterator Begin,
    315                                      MachineInstr::mmo_iterator End) {
    316   // Count the number of load mem refs.
    317   unsigned Num = 0;
    318   for (MachineInstr::mmo_iterator I = Begin; I != End; ++I)
    319     if ((*I)->isStore())
    320       ++Num;
    321 
    322   // Allocate a new array and populate it with the store information.
    323   MachineInstr::mmo_iterator Result = allocateMemRefsArray(Num);
    324   unsigned Index = 0;
    325   for (MachineInstr::mmo_iterator I = Begin; I != End; ++I) {
    326     if ((*I)->isStore()) {
    327       if (!(*I)->isLoad())
    328         // Reuse the MMO.
    329         Result[Index] = *I;
    330       else {
    331         // Clone the MMO and unset the load flag.
    332         MachineMemOperand *JustStore =
    333           getMachineMemOperand((*I)->getPointerInfo(),
    334                                (*I)->getFlags() & ~MachineMemOperand::MOLoad,
    335                                (*I)->getSize(), (*I)->getBaseAlignment(),
    336                                (*I)->getAAInfo());
    337         Result[Index] = JustStore;
    338       }
    339       ++Index;
    340     }
    341   }
    342   return std::make_pair(Result, Result + Num);
    343 }
    344 
    345 const char *MachineFunction::createExternalSymbolName(StringRef Name) {
    346   char *Dest = Allocator.Allocate<char>(Name.size() + 1);
    347   std::copy(Name.begin(), Name.end(), Dest);
    348   Dest[Name.size()] = 0;
    349   return Dest;
    350 }
    351 
    352 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
    353 void MachineFunction::dump() const {
    354   print(dbgs());
    355 }
    356 #endif
    357 
    358 StringRef MachineFunction::getName() const {
    359   assert(getFunction() && "No function!");
    360   return getFunction()->getName();
    361 }
    362 
    363 void MachineFunction::print(raw_ostream &OS, SlotIndexes *Indexes) const {
    364   OS << "# Machine code for function " << getName() << ": ";
    365   if (RegInfo) {
    366     OS << (RegInfo->isSSA() ? "SSA" : "Post SSA");
    367     if (!RegInfo->tracksLiveness())
    368       OS << ", not tracking liveness";
    369   }
    370   OS << '\n';
    371 
    372   // Print Frame Information
    373   FrameInfo->print(*this, OS);
    374 
    375   // Print JumpTable Information
    376   if (JumpTableInfo)
    377     JumpTableInfo->print(OS);
    378 
    379   // Print Constant Pool
    380   ConstantPool->print(OS);
    381 
    382   const TargetRegisterInfo *TRI = getSubtarget().getRegisterInfo();
    383 
    384   if (RegInfo && !RegInfo->livein_empty()) {
    385     OS << "Function Live Ins: ";
    386     for (MachineRegisterInfo::livein_iterator
    387          I = RegInfo->livein_begin(), E = RegInfo->livein_end(); I != E; ++I) {
    388       OS << PrintReg(I->first, TRI);
    389       if (I->second)
    390         OS << " in " << PrintReg(I->second, TRI);
    391       if (std::next(I) != E)
    392         OS << ", ";
    393     }
    394     OS << '\n';
    395   }
    396 
    397   ModuleSlotTracker MST(getFunction()->getParent());
    398   MST.incorporateFunction(*getFunction());
    399   for (const auto &BB : *this) {
    400     OS << '\n';
    401     BB.print(OS, MST, Indexes);
    402   }
    403 
    404   OS << "\n# End machine code for function " << getName() << ".\n\n";
    405 }
    406 
    407 namespace llvm {
    408   template<>
    409   struct DOTGraphTraits<const MachineFunction*> : public DefaultDOTGraphTraits {
    410 
    411   DOTGraphTraits (bool isSimple=false) : DefaultDOTGraphTraits(isSimple) {}
    412 
    413     static std::string getGraphName(const MachineFunction *F) {
    414       return ("CFG for '" + F->getName() + "' function").str();
    415     }
    416 
    417     std::string getNodeLabel(const MachineBasicBlock *Node,
    418                              const MachineFunction *Graph) {
    419       std::string OutStr;
    420       {
    421         raw_string_ostream OSS(OutStr);
    422 
    423         if (isSimple()) {
    424           OSS << "BB#" << Node->getNumber();
    425           if (const BasicBlock *BB = Node->getBasicBlock())
    426             OSS << ": " << BB->getName();
    427         } else
    428           Node->print(OSS);
    429       }
    430 
    431       if (OutStr[0] == '\n') OutStr.erase(OutStr.begin());
    432 
    433       // Process string output to make it nicer...
    434       for (unsigned i = 0; i != OutStr.length(); ++i)
    435         if (OutStr[i] == '\n') {                            // Left justify
    436           OutStr[i] = '\\';
    437           OutStr.insert(OutStr.begin()+i+1, 'l');
    438         }
    439       return OutStr;
    440     }
    441   };
    442 }
    443 
    444 void MachineFunction::viewCFG() const
    445 {
    446 #ifndef NDEBUG
    447   ViewGraph(this, "mf" + getName());
    448 #else
    449   errs() << "MachineFunction::viewCFG is only available in debug builds on "
    450          << "systems with Graphviz or gv!\n";
    451 #endif // NDEBUG
    452 }
    453 
    454 void MachineFunction::viewCFGOnly() const
    455 {
    456 #ifndef NDEBUG
    457   ViewGraph(this, "mf" + getName(), true);
    458 #else
    459   errs() << "MachineFunction::viewCFGOnly is only available in debug builds on "
    460          << "systems with Graphviz or gv!\n";
    461 #endif // NDEBUG
    462 }
    463 
    464 /// Add the specified physical register as a live-in value and
    465 /// create a corresponding virtual register for it.
    466 unsigned MachineFunction::addLiveIn(unsigned PReg,
    467                                     const TargetRegisterClass *RC) {
    468   MachineRegisterInfo &MRI = getRegInfo();
    469   unsigned VReg = MRI.getLiveInVirtReg(PReg);
    470   if (VReg) {
    471     const TargetRegisterClass *VRegRC = MRI.getRegClass(VReg);
    472     (void)VRegRC;
    473     // A physical register can be added several times.
    474     // Between two calls, the register class of the related virtual register
    475     // may have been constrained to match some operation constraints.
    476     // In that case, check that the current register class includes the
    477     // physical register and is a sub class of the specified RC.
    478     assert((VRegRC == RC || (VRegRC->contains(PReg) &&
    479                              RC->hasSubClassEq(VRegRC))) &&
    480             "Register class mismatch!");
    481     return VReg;
    482   }
    483   VReg = MRI.createVirtualRegister(RC);
    484   MRI.addLiveIn(PReg, VReg);
    485   return VReg;
    486 }
    487 
    488 /// Return the MCSymbol for the specified non-empty jump table.
    489 /// If isLinkerPrivate is specified, an 'l' label is returned, otherwise a
    490 /// normal 'L' label is returned.
    491 MCSymbol *MachineFunction::getJTISymbol(unsigned JTI, MCContext &Ctx,
    492                                         bool isLinkerPrivate) const {
    493   const DataLayout &DL = getDataLayout();
    494   assert(JumpTableInfo && "No jump tables");
    495   assert(JTI < JumpTableInfo->getJumpTables().size() && "Invalid JTI!");
    496 
    497   const char *Prefix = isLinkerPrivate ? DL.getLinkerPrivateGlobalPrefix()
    498                                        : DL.getPrivateGlobalPrefix();
    499   SmallString<60> Name;
    500   raw_svector_ostream(Name)
    501     << Prefix << "JTI" << getFunctionNumber() << '_' << JTI;
    502   return Ctx.getOrCreateSymbol(Name);
    503 }
    504 
    505 /// Return a function-local symbol to represent the PIC base.
    506 MCSymbol *MachineFunction::getPICBaseSymbol() const {
    507   const DataLayout &DL = getDataLayout();
    508   return Ctx.getOrCreateSymbol(Twine(DL.getPrivateGlobalPrefix()) +
    509                                Twine(getFunctionNumber()) + "$pb");
    510 }
    511 
    512 //===----------------------------------------------------------------------===//
    513 //  MachineFrameInfo implementation
    514 //===----------------------------------------------------------------------===//
    515 
    516 /// Make sure the function is at least Align bytes aligned.
    517 void MachineFrameInfo::ensureMaxAlignment(unsigned Align) {
    518   if (!StackRealignable || !RealignOption)
    519     assert(Align <= StackAlignment &&
    520            "For targets without stack realignment, Align is out of limit!");
    521   if (MaxAlignment < Align) MaxAlignment = Align;
    522 }
    523 
    524 /// Clamp the alignment if requested and emit a warning.
    525 static inline unsigned clampStackAlignment(bool ShouldClamp, unsigned Align,
    526                                            unsigned StackAlign) {
    527   if (!ShouldClamp || Align <= StackAlign)
    528     return Align;
    529   DEBUG(dbgs() << "Warning: requested alignment " << Align
    530                << " exceeds the stack alignment " << StackAlign
    531                << " when stack realignment is off" << '\n');
    532   return StackAlign;
    533 }
    534 
    535 /// Create a new statically sized stack object, returning a nonnegative
    536 /// identifier to represent it.
    537 int MachineFrameInfo::CreateStackObject(uint64_t Size, unsigned Alignment,
    538                       bool isSS, const AllocaInst *Alloca) {
    539   assert(Size != 0 && "Cannot allocate zero size stack objects!");
    540   Alignment = clampStackAlignment(!StackRealignable || !RealignOption,
    541                                   Alignment, StackAlignment);
    542   Objects.push_back(StackObject(Size, Alignment, 0, false, isSS, Alloca,
    543                                 !isSS));
    544   int Index = (int)Objects.size() - NumFixedObjects - 1;
    545   assert(Index >= 0 && "Bad frame index!");
    546   ensureMaxAlignment(Alignment);
    547   return Index;
    548 }
    549 
    550 /// Create a new statically sized stack object that represents a spill slot,
    551 /// returning a nonnegative identifier to represent it.
    552 int MachineFrameInfo::CreateSpillStackObject(uint64_t Size,
    553                                              unsigned Alignment) {
    554   Alignment = clampStackAlignment(!StackRealignable || !RealignOption,
    555                                   Alignment, StackAlignment);
    556   CreateStackObject(Size, Alignment, true);
    557   int Index = (int)Objects.size() - NumFixedObjects - 1;
    558   ensureMaxAlignment(Alignment);
    559   return Index;
    560 }
    561 
    562 /// Notify the MachineFrameInfo object that a variable sized object has been
    563 /// created. This must be created whenever a variable sized object is created,
    564 /// whether or not the index returned is actually used.
    565 int MachineFrameInfo::CreateVariableSizedObject(unsigned Alignment,
    566                                                 const AllocaInst *Alloca) {
    567   HasVarSizedObjects = true;
    568   Alignment = clampStackAlignment(!StackRealignable || !RealignOption,
    569                                   Alignment, StackAlignment);
    570   Objects.push_back(StackObject(0, Alignment, 0, false, false, Alloca, true));
    571   ensureMaxAlignment(Alignment);
    572   return (int)Objects.size()-NumFixedObjects-1;
    573 }
    574 
    575 /// Create a new object at a fixed location on the stack.
    576 /// All fixed objects should be created before other objects are created for
    577 /// efficiency. By default, fixed objects are immutable. This returns an
    578 /// index with a negative value.
    579 int MachineFrameInfo::CreateFixedObject(uint64_t Size, int64_t SPOffset,
    580                                         bool Immutable, bool isAliased) {
    581   assert(Size != 0 && "Cannot allocate zero size fixed stack objects!");
    582   // The alignment of the frame index can be determined from its offset from
    583   // the incoming frame position.  If the frame object is at offset 32 and
    584   // the stack is guaranteed to be 16-byte aligned, then we know that the
    585   // object is 16-byte aligned.
    586   unsigned Align = MinAlign(SPOffset, StackAlignment);
    587   Align = clampStackAlignment(!StackRealignable || !RealignOption, Align,
    588                               StackAlignment);
    589   Objects.insert(Objects.begin(), StackObject(Size, Align, SPOffset, Immutable,
    590                                               /*isSS*/   false,
    591                                               /*Alloca*/ nullptr, isAliased));
    592   return -++NumFixedObjects;
    593 }
    594 
    595 /// Create a spill slot at a fixed location on the stack.
    596 /// Returns an index with a negative value.
    597 int MachineFrameInfo::CreateFixedSpillStackObject(uint64_t Size,
    598                                                   int64_t SPOffset) {
    599   unsigned Align = MinAlign(SPOffset, StackAlignment);
    600   Align = clampStackAlignment(!StackRealignable || !RealignOption, Align,
    601                               StackAlignment);
    602   Objects.insert(Objects.begin(), StackObject(Size, Align, SPOffset,
    603                                               /*Immutable*/ true,
    604                                               /*isSS*/ true,
    605                                               /*Alloca*/ nullptr,
    606                                               /*isAliased*/ false));
    607   return -++NumFixedObjects;
    608 }
    609 
    610 BitVector MachineFrameInfo::getPristineRegs(const MachineFunction &MF) const {
    611   const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
    612   BitVector BV(TRI->getNumRegs());
    613 
    614   // Before CSI is calculated, no registers are considered pristine. They can be
    615   // freely used and PEI will make sure they are saved.
    616   if (!isCalleeSavedInfoValid())
    617     return BV;
    618 
    619   for (const MCPhysReg *CSR = TRI->getCalleeSavedRegs(&MF); CSR && *CSR; ++CSR)
    620     BV.set(*CSR);
    621 
    622   // Saved CSRs are not pristine.
    623   for (auto &I : getCalleeSavedInfo())
    624     for (MCSubRegIterator S(I.getReg(), TRI, true); S.isValid(); ++S)
    625       BV.reset(*S);
    626 
    627   return BV;
    628 }
    629 
    630 unsigned MachineFrameInfo::estimateStackSize(const MachineFunction &MF) const {
    631   const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
    632   const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo();
    633   unsigned MaxAlign = getMaxAlignment();
    634   int Offset = 0;
    635 
    636   // This code is very, very similar to PEI::calculateFrameObjectOffsets().
    637   // It really should be refactored to share code. Until then, changes
    638   // should keep in mind that there's tight coupling between the two.
    639 
    640   for (int i = getObjectIndexBegin(); i != 0; ++i) {
    641     int FixedOff = -getObjectOffset(i);
    642     if (FixedOff > Offset) Offset = FixedOff;
    643   }
    644   for (unsigned i = 0, e = getObjectIndexEnd(); i != e; ++i) {
    645     if (isDeadObjectIndex(i))
    646       continue;
    647     Offset += getObjectSize(i);
    648     unsigned Align = getObjectAlignment(i);
    649     // Adjust to alignment boundary
    650     Offset = (Offset+Align-1)/Align*Align;
    651 
    652     MaxAlign = std::max(Align, MaxAlign);
    653   }
    654 
    655   if (adjustsStack() && TFI->hasReservedCallFrame(MF))
    656     Offset += getMaxCallFrameSize();
    657 
    658   // Round up the size to a multiple of the alignment.  If the function has
    659   // any calls or alloca's, align to the target's StackAlignment value to
    660   // ensure that the callee's frame or the alloca data is suitably aligned;
    661   // otherwise, for leaf functions, align to the TransientStackAlignment
    662   // value.
    663   unsigned StackAlign;
    664   if (adjustsStack() || hasVarSizedObjects() ||
    665       (RegInfo->needsStackRealignment(MF) && getObjectIndexEnd() != 0))
    666     StackAlign = TFI->getStackAlignment();
    667   else
    668     StackAlign = TFI->getTransientStackAlignment();
    669 
    670   // If the frame pointer is eliminated, all frame offsets will be relative to
    671   // SP not FP. Align to MaxAlign so this works.
    672   StackAlign = std::max(StackAlign, MaxAlign);
    673   unsigned AlignMask = StackAlign - 1;
    674   Offset = (Offset + AlignMask) & ~uint64_t(AlignMask);
    675 
    676   return (unsigned)Offset;
    677 }
    678 
    679 void MachineFrameInfo::print(const MachineFunction &MF, raw_ostream &OS) const{
    680   if (Objects.empty()) return;
    681 
    682   const TargetFrameLowering *FI = MF.getSubtarget().getFrameLowering();
    683   int ValOffset = (FI ? FI->getOffsetOfLocalArea() : 0);
    684 
    685   OS << "Frame Objects:\n";
    686 
    687   for (unsigned i = 0, e = Objects.size(); i != e; ++i) {
    688     const StackObject &SO = Objects[i];
    689     OS << "  fi#" << (int)(i-NumFixedObjects) << ": ";
    690     if (SO.Size == ~0ULL) {
    691       OS << "dead\n";
    692       continue;
    693     }
    694     if (SO.Size == 0)
    695       OS << "variable sized";
    696     else
    697       OS << "size=" << SO.Size;
    698     OS << ", align=" << SO.Alignment;
    699 
    700     if (i < NumFixedObjects)
    701       OS << ", fixed";
    702     if (i < NumFixedObjects || SO.SPOffset != -1) {
    703       int64_t Off = SO.SPOffset - ValOffset;
    704       OS << ", at location [SP";
    705       if (Off > 0)
    706         OS << "+" << Off;
    707       else if (Off < 0)
    708         OS << Off;
    709       OS << "]";
    710     }
    711     OS << "\n";
    712   }
    713 }
    714 
    715 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
    716 void MachineFrameInfo::dump(const MachineFunction &MF) const {
    717   print(MF, dbgs());
    718 }
    719 #endif
    720 
    721 //===----------------------------------------------------------------------===//
    722 //  MachineJumpTableInfo implementation
    723 //===----------------------------------------------------------------------===//
    724 
    725 /// Return the size of each entry in the jump table.
    726 unsigned MachineJumpTableInfo::getEntrySize(const DataLayout &TD) const {
    727   // The size of a jump table entry is 4 bytes unless the entry is just the
    728   // address of a block, in which case it is the pointer size.
    729   switch (getEntryKind()) {
    730   case MachineJumpTableInfo::EK_BlockAddress:
    731     return TD.getPointerSize();
    732   case MachineJumpTableInfo::EK_GPRel64BlockAddress:
    733     return 8;
    734   case MachineJumpTableInfo::EK_GPRel32BlockAddress:
    735   case MachineJumpTableInfo::EK_LabelDifference32:
    736   case MachineJumpTableInfo::EK_Custom32:
    737     return 4;
    738   case MachineJumpTableInfo::EK_Inline:
    739     return 0;
    740   }
    741   llvm_unreachable("Unknown jump table encoding!");
    742 }
    743 
    744 /// Return the alignment of each entry in the jump table.
    745 unsigned MachineJumpTableInfo::getEntryAlignment(const DataLayout &TD) const {
    746   // The alignment of a jump table entry is the alignment of int32 unless the
    747   // entry is just the address of a block, in which case it is the pointer
    748   // alignment.
    749   switch (getEntryKind()) {
    750   case MachineJumpTableInfo::EK_BlockAddress:
    751     return TD.getPointerABIAlignment();
    752   case MachineJumpTableInfo::EK_GPRel64BlockAddress:
    753     return TD.getABIIntegerTypeAlignment(64);
    754   case MachineJumpTableInfo::EK_GPRel32BlockAddress:
    755   case MachineJumpTableInfo::EK_LabelDifference32:
    756   case MachineJumpTableInfo::EK_Custom32:
    757     return TD.getABIIntegerTypeAlignment(32);
    758   case MachineJumpTableInfo::EK_Inline:
    759     return 1;
    760   }
    761   llvm_unreachable("Unknown jump table encoding!");
    762 }
    763 
    764 /// Create a new jump table entry in the jump table info.
    765 unsigned MachineJumpTableInfo::createJumpTableIndex(
    766                                const std::vector<MachineBasicBlock*> &DestBBs) {
    767   assert(!DestBBs.empty() && "Cannot create an empty jump table!");
    768   JumpTables.push_back(MachineJumpTableEntry(DestBBs));
    769   return JumpTables.size()-1;
    770 }
    771 
    772 /// If Old is the target of any jump tables, update the jump tables to branch
    773 /// to New instead.
    774 bool MachineJumpTableInfo::ReplaceMBBInJumpTables(MachineBasicBlock *Old,
    775                                                   MachineBasicBlock *New) {
    776   assert(Old != New && "Not making a change?");
    777   bool MadeChange = false;
    778   for (size_t i = 0, e = JumpTables.size(); i != e; ++i)
    779     ReplaceMBBInJumpTable(i, Old, New);
    780   return MadeChange;
    781 }
    782 
    783 /// If Old is a target of the jump tables, update the jump table to branch to
    784 /// New instead.
    785 bool MachineJumpTableInfo::ReplaceMBBInJumpTable(unsigned Idx,
    786                                                  MachineBasicBlock *Old,
    787                                                  MachineBasicBlock *New) {
    788   assert(Old != New && "Not making a change?");
    789   bool MadeChange = false;
    790   MachineJumpTableEntry &JTE = JumpTables[Idx];
    791   for (size_t j = 0, e = JTE.MBBs.size(); j != e; ++j)
    792     if (JTE.MBBs[j] == Old) {
    793       JTE.MBBs[j] = New;
    794       MadeChange = true;
    795     }
    796   return MadeChange;
    797 }
    798 
    799 void MachineJumpTableInfo::print(raw_ostream &OS) const {
    800   if (JumpTables.empty()) return;
    801 
    802   OS << "Jump Tables:\n";
    803 
    804   for (unsigned i = 0, e = JumpTables.size(); i != e; ++i) {
    805     OS << "  jt#" << i << ": ";
    806     for (unsigned j = 0, f = JumpTables[i].MBBs.size(); j != f; ++j)
    807       OS << " BB#" << JumpTables[i].MBBs[j]->getNumber();
    808   }
    809 
    810   OS << '\n';
    811 }
    812 
    813 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
    814 void MachineJumpTableInfo::dump() const { print(dbgs()); }
    815 #endif
    816 
    817 
    818 //===----------------------------------------------------------------------===//
    819 //  MachineConstantPool implementation
    820 //===----------------------------------------------------------------------===//
    821 
    822 void MachineConstantPoolValue::anchor() { }
    823 
    824 Type *MachineConstantPoolEntry::getType() const {
    825   if (isMachineConstantPoolEntry())
    826     return Val.MachineCPVal->getType();
    827   return Val.ConstVal->getType();
    828 }
    829 
    830 bool MachineConstantPoolEntry::needsRelocation() const {
    831   if (isMachineConstantPoolEntry())
    832     return true;
    833   return Val.ConstVal->needsRelocation();
    834 }
    835 
    836 SectionKind
    837 MachineConstantPoolEntry::getSectionKind(const DataLayout *DL) const {
    838   if (needsRelocation())
    839     return SectionKind::getReadOnlyWithRel();
    840   switch (DL->getTypeAllocSize(getType())) {
    841   case 4:
    842     return SectionKind::getMergeableConst4();
    843   case 8:
    844     return SectionKind::getMergeableConst8();
    845   case 16:
    846     return SectionKind::getMergeableConst16();
    847   default:
    848     return SectionKind::getReadOnly();
    849   }
    850 }
    851 
    852 MachineConstantPool::~MachineConstantPool() {
    853   for (unsigned i = 0, e = Constants.size(); i != e; ++i)
    854     if (Constants[i].isMachineConstantPoolEntry())
    855       delete Constants[i].Val.MachineCPVal;
    856   for (DenseSet<MachineConstantPoolValue*>::iterator I =
    857        MachineCPVsSharingEntries.begin(), E = MachineCPVsSharingEntries.end();
    858        I != E; ++I)
    859     delete *I;
    860 }
    861 
    862 /// Test whether the given two constants can be allocated the same constant pool
    863 /// entry.
    864 static bool CanShareConstantPoolEntry(const Constant *A, const Constant *B,
    865                                       const DataLayout &DL) {
    866   // Handle the trivial case quickly.
    867   if (A == B) return true;
    868 
    869   // If they have the same type but weren't the same constant, quickly
    870   // reject them.
    871   if (A->getType() == B->getType()) return false;
    872 
    873   // We can't handle structs or arrays.
    874   if (isa<StructType>(A->getType()) || isa<ArrayType>(A->getType()) ||
    875       isa<StructType>(B->getType()) || isa<ArrayType>(B->getType()))
    876     return false;
    877 
    878   // For now, only support constants with the same size.
    879   uint64_t StoreSize = DL.getTypeStoreSize(A->getType());
    880   if (StoreSize != DL.getTypeStoreSize(B->getType()) || StoreSize > 128)
    881     return false;
    882 
    883   Type *IntTy = IntegerType::get(A->getContext(), StoreSize*8);
    884 
    885   // Try constant folding a bitcast of both instructions to an integer.  If we
    886   // get two identical ConstantInt's, then we are good to share them.  We use
    887   // the constant folding APIs to do this so that we get the benefit of
    888   // DataLayout.
    889   if (isa<PointerType>(A->getType()))
    890     A = ConstantFoldInstOperands(Instruction::PtrToInt, IntTy,
    891                                  const_cast<Constant *>(A), DL);
    892   else if (A->getType() != IntTy)
    893     A = ConstantFoldInstOperands(Instruction::BitCast, IntTy,
    894                                  const_cast<Constant *>(A), DL);
    895   if (isa<PointerType>(B->getType()))
    896     B = ConstantFoldInstOperands(Instruction::PtrToInt, IntTy,
    897                                  const_cast<Constant *>(B), DL);
    898   else if (B->getType() != IntTy)
    899     B = ConstantFoldInstOperands(Instruction::BitCast, IntTy,
    900                                  const_cast<Constant *>(B), DL);
    901 
    902   return A == B;
    903 }
    904 
    905 /// Create a new entry in the constant pool or return an existing one.
    906 /// User must specify the log2 of the minimum required alignment for the object.
    907 unsigned MachineConstantPool::getConstantPoolIndex(const Constant *C,
    908                                                    unsigned Alignment) {
    909   assert(Alignment && "Alignment must be specified!");
    910   if (Alignment > PoolAlignment) PoolAlignment = Alignment;
    911 
    912   // Check to see if we already have this constant.
    913   //
    914   // FIXME, this could be made much more efficient for large constant pools.
    915   for (unsigned i = 0, e = Constants.size(); i != e; ++i)
    916     if (!Constants[i].isMachineConstantPoolEntry() &&
    917         CanShareConstantPoolEntry(Constants[i].Val.ConstVal, C, DL)) {
    918       if ((unsigned)Constants[i].getAlignment() < Alignment)
    919         Constants[i].Alignment = Alignment;
    920       return i;
    921     }
    922 
    923   Constants.push_back(MachineConstantPoolEntry(C, Alignment));
    924   return Constants.size()-1;
    925 }
    926 
    927 unsigned MachineConstantPool::getConstantPoolIndex(MachineConstantPoolValue *V,
    928                                                    unsigned Alignment) {
    929   assert(Alignment && "Alignment must be specified!");
    930   if (Alignment > PoolAlignment) PoolAlignment = Alignment;
    931 
    932   // Check to see if we already have this constant.
    933   //
    934   // FIXME, this could be made much more efficient for large constant pools.
    935   int Idx = V->getExistingMachineCPValue(this, Alignment);
    936   if (Idx != -1) {
    937     MachineCPVsSharingEntries.insert(V);
    938     return (unsigned)Idx;
    939   }
    940 
    941   Constants.push_back(MachineConstantPoolEntry(V, Alignment));
    942   return Constants.size()-1;
    943 }
    944 
    945 void MachineConstantPool::print(raw_ostream &OS) const {
    946   if (Constants.empty()) return;
    947 
    948   OS << "Constant Pool:\n";
    949   for (unsigned i = 0, e = Constants.size(); i != e; ++i) {
    950     OS << "  cp#" << i << ": ";
    951     if (Constants[i].isMachineConstantPoolEntry())
    952       Constants[i].Val.MachineCPVal->print(OS);
    953     else
    954       Constants[i].Val.ConstVal->printAsOperand(OS, /*PrintType=*/false);
    955     OS << ", align=" << Constants[i].getAlignment();
    956     OS << "\n";
    957   }
    958 }
    959 
    960 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
    961 void MachineConstantPool::dump() const { print(dbgs()); }
    962 #endif
    963