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