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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/Function.h"
     18 #include "llvm/CodeGen/MachineConstantPool.h"
     19 #include "llvm/CodeGen/MachineFunctionPass.h"
     20 #include "llvm/CodeGen/MachineFrameInfo.h"
     21 #include "llvm/CodeGen/MachineInstr.h"
     22 #include "llvm/CodeGen/MachineJumpTableInfo.h"
     23 #include "llvm/CodeGen/MachineModuleInfo.h"
     24 #include "llvm/CodeGen/MachineRegisterInfo.h"
     25 #include "llvm/CodeGen/Passes.h"
     26 #include "llvm/MC/MCAsmInfo.h"
     27 #include "llvm/MC/MCContext.h"
     28 #include "llvm/Analysis/ConstantFolding.h"
     29 #include "llvm/Analysis/DebugInfo.h"
     30 #include "llvm/Support/Debug.h"
     31 #include "llvm/Target/TargetData.h"
     32 #include "llvm/Target/TargetLowering.h"
     33 #include "llvm/Target/TargetMachine.h"
     34 #include "llvm/Target/TargetFrameLowering.h"
     35 #include "llvm/ADT/SmallString.h"
     36 #include "llvm/ADT/STLExtras.h"
     37 #include "llvm/Support/GraphWriter.h"
     38 #include "llvm/Support/raw_ostream.h"
     39 using namespace llvm;
     40 
     41 //===----------------------------------------------------------------------===//
     42 // MachineFunction implementation
     43 //===----------------------------------------------------------------------===//
     44 
     45 // Out of line virtual method.
     46 MachineFunctionInfo::~MachineFunctionInfo() {}
     47 
     48 void ilist_traits<MachineBasicBlock>::deleteNode(MachineBasicBlock *MBB) {
     49   MBB->getParent()->DeleteMachineBasicBlock(MBB);
     50 }
     51 
     52 MachineFunction::MachineFunction(const Function *F, const TargetMachine &TM,
     53                                  unsigned FunctionNum, MachineModuleInfo &mmi,
     54                                  GCModuleInfo* gmi)
     55   : Fn(F), Target(TM), Ctx(mmi.getContext()), MMI(mmi), GMI(gmi) {
     56   if (TM.getRegisterInfo())
     57     RegInfo = new (Allocator) MachineRegisterInfo(*TM.getRegisterInfo());
     58   else
     59     RegInfo = 0;
     60   MFInfo = 0;
     61   FrameInfo = new (Allocator) MachineFrameInfo(*TM.getFrameLowering());
     62   if (Fn->hasFnAttr(Attribute::StackAlignment))
     63     FrameInfo->setMaxAlignment(Attribute::getStackAlignmentFromAttrs(
     64         Fn->getAttributes().getFnAttributes()));
     65   ConstantPool = new (Allocator) MachineConstantPool(TM.getTargetData());
     66   Alignment = TM.getTargetLowering()->getMinFunctionAlignment();
     67   // FIXME: Shouldn't use pref alignment if explicit alignment is set on Fn.
     68   if (!Fn->hasFnAttr(Attribute::OptimizeForSize))
     69     Alignment = std::max(Alignment,
     70                          TM.getTargetLowering()->getPrefFunctionAlignment());
     71   FunctionNumber = FunctionNum;
     72   JumpTableInfo = 0;
     73 }
     74 
     75 MachineFunction::~MachineFunction() {
     76   BasicBlocks.clear();
     77   InstructionRecycler.clear(Allocator);
     78   BasicBlockRecycler.clear(Allocator);
     79   if (RegInfo) {
     80     RegInfo->~MachineRegisterInfo();
     81     Allocator.Deallocate(RegInfo);
     82   }
     83   if (MFInfo) {
     84     MFInfo->~MachineFunctionInfo();
     85     Allocator.Deallocate(MFInfo);
     86   }
     87   FrameInfo->~MachineFrameInfo();         Allocator.Deallocate(FrameInfo);
     88   ConstantPool->~MachineConstantPool();   Allocator.Deallocate(ConstantPool);
     89 
     90   if (JumpTableInfo) {
     91     JumpTableInfo->~MachineJumpTableInfo();
     92     Allocator.Deallocate(JumpTableInfo);
     93   }
     94 }
     95 
     96 /// getOrCreateJumpTableInfo - Get the JumpTableInfo for this function, if it
     97 /// does already exist, allocate one.
     98 MachineJumpTableInfo *MachineFunction::
     99 getOrCreateJumpTableInfo(unsigned EntryKind) {
    100   if (JumpTableInfo) return JumpTableInfo;
    101 
    102   JumpTableInfo = new (Allocator)
    103     MachineJumpTableInfo((MachineJumpTableInfo::JTEntryKind)EntryKind);
    104   return JumpTableInfo;
    105 }
    106 
    107 /// RenumberBlocks - This discards all of the MachineBasicBlock numbers and
    108 /// recomputes them.  This guarantees that the MBB numbers are sequential,
    109 /// dense, and match the ordering of the blocks within the function.  If a
    110 /// specific MachineBasicBlock is specified, only that block and those after
    111 /// it are renumbered.
    112 void MachineFunction::RenumberBlocks(MachineBasicBlock *MBB) {
    113   if (empty()) { MBBNumbering.clear(); return; }
    114   MachineFunction::iterator MBBI, E = end();
    115   if (MBB == 0)
    116     MBBI = begin();
    117   else
    118     MBBI = MBB;
    119 
    120   // Figure out the block number this should have.
    121   unsigned BlockNo = 0;
    122   if (MBBI != begin())
    123     BlockNo = prior(MBBI)->getNumber()+1;
    124 
    125   for (; MBBI != E; ++MBBI, ++BlockNo) {
    126     if (MBBI->getNumber() != (int)BlockNo) {
    127       // Remove use of the old number.
    128       if (MBBI->getNumber() != -1) {
    129         assert(MBBNumbering[MBBI->getNumber()] == &*MBBI &&
    130                "MBB number mismatch!");
    131         MBBNumbering[MBBI->getNumber()] = 0;
    132       }
    133 
    134       // If BlockNo is already taken, set that block's number to -1.
    135       if (MBBNumbering[BlockNo])
    136         MBBNumbering[BlockNo]->setNumber(-1);
    137 
    138       MBBNumbering[BlockNo] = MBBI;
    139       MBBI->setNumber(BlockNo);
    140     }
    141   }
    142 
    143   // Okay, all the blocks are renumbered.  If we have compactified the block
    144   // numbering, shrink MBBNumbering now.
    145   assert(BlockNo <= MBBNumbering.size() && "Mismatch!");
    146   MBBNumbering.resize(BlockNo);
    147 }
    148 
    149 /// CreateMachineInstr - Allocate a new MachineInstr. Use this instead
    150 /// of `new MachineInstr'.
    151 ///
    152 MachineInstr *
    153 MachineFunction::CreateMachineInstr(const MCInstrDesc &MCID,
    154                                     DebugLoc DL, bool NoImp) {
    155   return new (InstructionRecycler.Allocate<MachineInstr>(Allocator))
    156     MachineInstr(MCID, DL, NoImp);
    157 }
    158 
    159 /// CloneMachineInstr - Create a new MachineInstr which is a copy of the
    160 /// 'Orig' instruction, identical in all ways except the instruction
    161 /// has no parent, prev, or next.
    162 ///
    163 MachineInstr *
    164 MachineFunction::CloneMachineInstr(const MachineInstr *Orig) {
    165   return new (InstructionRecycler.Allocate<MachineInstr>(Allocator))
    166              MachineInstr(*this, *Orig);
    167 }
    168 
    169 /// DeleteMachineInstr - Delete the given MachineInstr.
    170 ///
    171 void
    172 MachineFunction::DeleteMachineInstr(MachineInstr *MI) {
    173   MI->~MachineInstr();
    174   InstructionRecycler.Deallocate(Allocator, MI);
    175 }
    176 
    177 /// CreateMachineBasicBlock - Allocate a new MachineBasicBlock. Use this
    178 /// instead of `new MachineBasicBlock'.
    179 ///
    180 MachineBasicBlock *
    181 MachineFunction::CreateMachineBasicBlock(const BasicBlock *bb) {
    182   return new (BasicBlockRecycler.Allocate<MachineBasicBlock>(Allocator))
    183              MachineBasicBlock(*this, bb);
    184 }
    185 
    186 /// DeleteMachineBasicBlock - Delete the given MachineBasicBlock.
    187 ///
    188 void
    189 MachineFunction::DeleteMachineBasicBlock(MachineBasicBlock *MBB) {
    190   assert(MBB->getParent() == this && "MBB parent mismatch!");
    191   MBB->~MachineBasicBlock();
    192   BasicBlockRecycler.Deallocate(Allocator, MBB);
    193 }
    194 
    195 MachineMemOperand *
    196 MachineFunction::getMachineMemOperand(MachinePointerInfo PtrInfo, unsigned f,
    197                                       uint64_t s, unsigned base_alignment,
    198                                       const MDNode *TBAAInfo,
    199                                       const MDNode *Ranges) {
    200   return new (Allocator) MachineMemOperand(PtrInfo, f, s, base_alignment,
    201                                            TBAAInfo, Ranges);
    202 }
    203 
    204 MachineMemOperand *
    205 MachineFunction::getMachineMemOperand(const MachineMemOperand *MMO,
    206                                       int64_t Offset, uint64_t Size) {
    207   return new (Allocator)
    208              MachineMemOperand(MachinePointerInfo(MMO->getValue(),
    209                                                   MMO->getOffset()+Offset),
    210                                MMO->getFlags(), Size,
    211                                MMO->getBaseAlignment(), 0);
    212 }
    213 
    214 MachineInstr::mmo_iterator
    215 MachineFunction::allocateMemRefsArray(unsigned long Num) {
    216   return Allocator.Allocate<MachineMemOperand *>(Num);
    217 }
    218 
    219 std::pair<MachineInstr::mmo_iterator, MachineInstr::mmo_iterator>
    220 MachineFunction::extractLoadMemRefs(MachineInstr::mmo_iterator Begin,
    221                                     MachineInstr::mmo_iterator End) {
    222   // Count the number of load mem refs.
    223   unsigned Num = 0;
    224   for (MachineInstr::mmo_iterator I = Begin; I != End; ++I)
    225     if ((*I)->isLoad())
    226       ++Num;
    227 
    228   // Allocate a new array and populate it with the load information.
    229   MachineInstr::mmo_iterator Result = allocateMemRefsArray(Num);
    230   unsigned Index = 0;
    231   for (MachineInstr::mmo_iterator I = Begin; I != End; ++I) {
    232     if ((*I)->isLoad()) {
    233       if (!(*I)->isStore())
    234         // Reuse the MMO.
    235         Result[Index] = *I;
    236       else {
    237         // Clone the MMO and unset the store flag.
    238         MachineMemOperand *JustLoad =
    239           getMachineMemOperand((*I)->getPointerInfo(),
    240                                (*I)->getFlags() & ~MachineMemOperand::MOStore,
    241                                (*I)->getSize(), (*I)->getBaseAlignment(),
    242                                (*I)->getTBAAInfo());
    243         Result[Index] = JustLoad;
    244       }
    245       ++Index;
    246     }
    247   }
    248   return std::make_pair(Result, Result + Num);
    249 }
    250 
    251 std::pair<MachineInstr::mmo_iterator, MachineInstr::mmo_iterator>
    252 MachineFunction::extractStoreMemRefs(MachineInstr::mmo_iterator Begin,
    253                                      MachineInstr::mmo_iterator End) {
    254   // Count the number of load mem refs.
    255   unsigned Num = 0;
    256   for (MachineInstr::mmo_iterator I = Begin; I != End; ++I)
    257     if ((*I)->isStore())
    258       ++Num;
    259 
    260   // Allocate a new array and populate it with the store information.
    261   MachineInstr::mmo_iterator Result = allocateMemRefsArray(Num);
    262   unsigned Index = 0;
    263   for (MachineInstr::mmo_iterator I = Begin; I != End; ++I) {
    264     if ((*I)->isStore()) {
    265       if (!(*I)->isLoad())
    266         // Reuse the MMO.
    267         Result[Index] = *I;
    268       else {
    269         // Clone the MMO and unset the load flag.
    270         MachineMemOperand *JustStore =
    271           getMachineMemOperand((*I)->getPointerInfo(),
    272                                (*I)->getFlags() & ~MachineMemOperand::MOLoad,
    273                                (*I)->getSize(), (*I)->getBaseAlignment(),
    274                                (*I)->getTBAAInfo());
    275         Result[Index] = JustStore;
    276       }
    277       ++Index;
    278     }
    279   }
    280   return std::make_pair(Result, Result + Num);
    281 }
    282 
    283 void MachineFunction::dump() const {
    284   print(dbgs());
    285 }
    286 
    287 void MachineFunction::print(raw_ostream &OS, SlotIndexes *Indexes) const {
    288   OS << "# Machine code for function " << Fn->getName() << ": ";
    289   if (RegInfo) {
    290     OS << (RegInfo->isSSA() ? "SSA" : "Post SSA");
    291     if (!RegInfo->tracksLiveness())
    292       OS << ", not tracking liveness";
    293   }
    294   OS << '\n';
    295 
    296   // Print Frame Information
    297   FrameInfo->print(*this, OS);
    298 
    299   // Print JumpTable Information
    300   if (JumpTableInfo)
    301     JumpTableInfo->print(OS);
    302 
    303   // Print Constant Pool
    304   ConstantPool->print(OS);
    305 
    306   const TargetRegisterInfo *TRI = getTarget().getRegisterInfo();
    307 
    308   if (RegInfo && !RegInfo->livein_empty()) {
    309     OS << "Function Live Ins: ";
    310     for (MachineRegisterInfo::livein_iterator
    311          I = RegInfo->livein_begin(), E = RegInfo->livein_end(); I != E; ++I) {
    312       OS << PrintReg(I->first, TRI);
    313       if (I->second)
    314         OS << " in " << PrintReg(I->second, TRI);
    315       if (llvm::next(I) != E)
    316         OS << ", ";
    317     }
    318     OS << '\n';
    319   }
    320   if (RegInfo && !RegInfo->liveout_empty()) {
    321     OS << "Function Live Outs:";
    322     for (MachineRegisterInfo::liveout_iterator
    323          I = RegInfo->liveout_begin(), E = RegInfo->liveout_end(); I != E; ++I)
    324       OS << ' ' << PrintReg(*I, TRI);
    325     OS << '\n';
    326   }
    327 
    328   for (const_iterator BB = begin(), E = end(); BB != E; ++BB) {
    329     OS << '\n';
    330     BB->print(OS, Indexes);
    331   }
    332 
    333   OS << "\n# End machine code for function " << Fn->getName() << ".\n\n";
    334 }
    335 
    336 namespace llvm {
    337   template<>
    338   struct DOTGraphTraits<const MachineFunction*> : public DefaultDOTGraphTraits {
    339 
    340   DOTGraphTraits (bool isSimple=false) : DefaultDOTGraphTraits(isSimple) {}
    341 
    342     static std::string getGraphName(const MachineFunction *F) {
    343       return "CFG for '" + F->getFunction()->getName().str() + "' function";
    344     }
    345 
    346     std::string getNodeLabel(const MachineBasicBlock *Node,
    347                              const MachineFunction *Graph) {
    348       std::string OutStr;
    349       {
    350         raw_string_ostream OSS(OutStr);
    351 
    352         if (isSimple()) {
    353           OSS << "BB#" << Node->getNumber();
    354           if (const BasicBlock *BB = Node->getBasicBlock())
    355             OSS << ": " << BB->getName();
    356         } else
    357           Node->print(OSS);
    358       }
    359 
    360       if (OutStr[0] == '\n') OutStr.erase(OutStr.begin());
    361 
    362       // Process string output to make it nicer...
    363       for (unsigned i = 0; i != OutStr.length(); ++i)
    364         if (OutStr[i] == '\n') {                            // Left justify
    365           OutStr[i] = '\\';
    366           OutStr.insert(OutStr.begin()+i+1, 'l');
    367         }
    368       return OutStr;
    369     }
    370   };
    371 }
    372 
    373 void MachineFunction::viewCFG() const
    374 {
    375 #ifndef NDEBUG
    376   ViewGraph(this, "mf" + getFunction()->getName());
    377 #else
    378   errs() << "MachineFunction::viewCFG is only available in debug builds on "
    379          << "systems with Graphviz or gv!\n";
    380 #endif // NDEBUG
    381 }
    382 
    383 void MachineFunction::viewCFGOnly() const
    384 {
    385 #ifndef NDEBUG
    386   ViewGraph(this, "mf" + getFunction()->getName(), true);
    387 #else
    388   errs() << "MachineFunction::viewCFGOnly is only available in debug builds on "
    389          << "systems with Graphviz or gv!\n";
    390 #endif // NDEBUG
    391 }
    392 
    393 /// addLiveIn - Add the specified physical register as a live-in value and
    394 /// create a corresponding virtual register for it.
    395 unsigned MachineFunction::addLiveIn(unsigned PReg,
    396                                     const TargetRegisterClass *RC) {
    397   MachineRegisterInfo &MRI = getRegInfo();
    398   unsigned VReg = MRI.getLiveInVirtReg(PReg);
    399   if (VReg) {
    400     assert(MRI.getRegClass(VReg) == RC && "Register class mismatch!");
    401     return VReg;
    402   }
    403   VReg = MRI.createVirtualRegister(RC);
    404   MRI.addLiveIn(PReg, VReg);
    405   return VReg;
    406 }
    407 
    408 /// getJTISymbol - Return the MCSymbol for the specified non-empty jump table.
    409 /// If isLinkerPrivate is specified, an 'l' label is returned, otherwise a
    410 /// normal 'L' label is returned.
    411 MCSymbol *MachineFunction::getJTISymbol(unsigned JTI, MCContext &Ctx,
    412                                         bool isLinkerPrivate) const {
    413   assert(JumpTableInfo && "No jump tables");
    414 
    415   assert(JTI < JumpTableInfo->getJumpTables().size() && "Invalid JTI!");
    416   const MCAsmInfo &MAI = *getTarget().getMCAsmInfo();
    417 
    418   const char *Prefix = isLinkerPrivate ? MAI.getLinkerPrivateGlobalPrefix() :
    419                                          MAI.getPrivateGlobalPrefix();
    420   SmallString<60> Name;
    421   raw_svector_ostream(Name)
    422     << Prefix << "JTI" << getFunctionNumber() << '_' << JTI;
    423   return Ctx.GetOrCreateSymbol(Name.str());
    424 }
    425 
    426 /// getPICBaseSymbol - Return a function-local symbol to represent the PIC
    427 /// base.
    428 MCSymbol *MachineFunction::getPICBaseSymbol() const {
    429   const MCAsmInfo &MAI = *Target.getMCAsmInfo();
    430   return Ctx.GetOrCreateSymbol(Twine(MAI.getPrivateGlobalPrefix())+
    431                                Twine(getFunctionNumber())+"$pb");
    432 }
    433 
    434 //===----------------------------------------------------------------------===//
    435 //  MachineFrameInfo implementation
    436 //===----------------------------------------------------------------------===//
    437 
    438 /// CreateFixedObject - Create a new object at a fixed location on the stack.
    439 /// All fixed objects should be created before other objects are created for
    440 /// efficiency. By default, fixed objects are immutable. This returns an
    441 /// index with a negative value.
    442 ///
    443 int MachineFrameInfo::CreateFixedObject(uint64_t Size, int64_t SPOffset,
    444                                         bool Immutable) {
    445   assert(Size != 0 && "Cannot allocate zero size fixed stack objects!");
    446   // The alignment of the frame index can be determined from its offset from
    447   // the incoming frame position.  If the frame object is at offset 32 and
    448   // the stack is guaranteed to be 16-byte aligned, then we know that the
    449   // object is 16-byte aligned.
    450   unsigned StackAlign = TFI.getStackAlignment();
    451   unsigned Align = MinAlign(SPOffset, StackAlign);
    452   Objects.insert(Objects.begin(), StackObject(Size, Align, SPOffset, Immutable,
    453                                               /*isSS*/false, false));
    454   return -++NumFixedObjects;
    455 }
    456 
    457 
    458 BitVector
    459 MachineFrameInfo::getPristineRegs(const MachineBasicBlock *MBB) const {
    460   assert(MBB && "MBB must be valid");
    461   const MachineFunction *MF = MBB->getParent();
    462   assert(MF && "MBB must be part of a MachineFunction");
    463   const TargetMachine &TM = MF->getTarget();
    464   const TargetRegisterInfo *TRI = TM.getRegisterInfo();
    465   BitVector BV(TRI->getNumRegs());
    466 
    467   // Before CSI is calculated, no registers are considered pristine. They can be
    468   // freely used and PEI will make sure they are saved.
    469   if (!isCalleeSavedInfoValid())
    470     return BV;
    471 
    472   for (const uint16_t *CSR = TRI->getCalleeSavedRegs(MF); CSR && *CSR; ++CSR)
    473     BV.set(*CSR);
    474 
    475   // The entry MBB always has all CSRs pristine.
    476   if (MBB == &MF->front())
    477     return BV;
    478 
    479   // On other MBBs the saved CSRs are not pristine.
    480   const std::vector<CalleeSavedInfo> &CSI = getCalleeSavedInfo();
    481   for (std::vector<CalleeSavedInfo>::const_iterator I = CSI.begin(),
    482          E = CSI.end(); I != E; ++I)
    483     BV.reset(I->getReg());
    484 
    485   return BV;
    486 }
    487 
    488 
    489 void MachineFrameInfo::print(const MachineFunction &MF, raw_ostream &OS) const{
    490   if (Objects.empty()) return;
    491 
    492   const TargetFrameLowering *FI = MF.getTarget().getFrameLowering();
    493   int ValOffset = (FI ? FI->getOffsetOfLocalArea() : 0);
    494 
    495   OS << "Frame Objects:\n";
    496 
    497   for (unsigned i = 0, e = Objects.size(); i != e; ++i) {
    498     const StackObject &SO = Objects[i];
    499     OS << "  fi#" << (int)(i-NumFixedObjects) << ": ";
    500     if (SO.Size == ~0ULL) {
    501       OS << "dead\n";
    502       continue;
    503     }
    504     if (SO.Size == 0)
    505       OS << "variable sized";
    506     else
    507       OS << "size=" << SO.Size;
    508     OS << ", align=" << SO.Alignment;
    509 
    510     if (i < NumFixedObjects)
    511       OS << ", fixed";
    512     if (i < NumFixedObjects || SO.SPOffset != -1) {
    513       int64_t Off = SO.SPOffset - ValOffset;
    514       OS << ", at location [SP";
    515       if (Off > 0)
    516         OS << "+" << Off;
    517       else if (Off < 0)
    518         OS << Off;
    519       OS << "]";
    520     }
    521     OS << "\n";
    522   }
    523 }
    524 
    525 void MachineFrameInfo::dump(const MachineFunction &MF) const {
    526   print(MF, dbgs());
    527 }
    528 
    529 //===----------------------------------------------------------------------===//
    530 //  MachineJumpTableInfo implementation
    531 //===----------------------------------------------------------------------===//
    532 
    533 /// getEntrySize - Return the size of each entry in the jump table.
    534 unsigned MachineJumpTableInfo::getEntrySize(const TargetData &TD) const {
    535   // The size of a jump table entry is 4 bytes unless the entry is just the
    536   // address of a block, in which case it is the pointer size.
    537   switch (getEntryKind()) {
    538   case MachineJumpTableInfo::EK_BlockAddress:
    539     return TD.getPointerSize();
    540   case MachineJumpTableInfo::EK_GPRel64BlockAddress:
    541     return 8;
    542   case MachineJumpTableInfo::EK_GPRel32BlockAddress:
    543   case MachineJumpTableInfo::EK_LabelDifference32:
    544   case MachineJumpTableInfo::EK_Custom32:
    545     return 4;
    546   case MachineJumpTableInfo::EK_Inline:
    547     return 0;
    548   }
    549   llvm_unreachable("Unknown jump table encoding!");
    550 }
    551 
    552 /// getEntryAlignment - Return the alignment of each entry in the jump table.
    553 unsigned MachineJumpTableInfo::getEntryAlignment(const TargetData &TD) const {
    554   // The alignment of a jump table entry is the alignment of int32 unless the
    555   // entry is just the address of a block, in which case it is the pointer
    556   // alignment.
    557   switch (getEntryKind()) {
    558   case MachineJumpTableInfo::EK_BlockAddress:
    559     return TD.getPointerABIAlignment();
    560   case MachineJumpTableInfo::EK_GPRel64BlockAddress:
    561     return TD.getABIIntegerTypeAlignment(64);
    562   case MachineJumpTableInfo::EK_GPRel32BlockAddress:
    563   case MachineJumpTableInfo::EK_LabelDifference32:
    564   case MachineJumpTableInfo::EK_Custom32:
    565     return TD.getABIIntegerTypeAlignment(32);
    566   case MachineJumpTableInfo::EK_Inline:
    567     return 1;
    568   }
    569   llvm_unreachable("Unknown jump table encoding!");
    570 }
    571 
    572 /// createJumpTableIndex - Create a new jump table entry in the jump table info.
    573 ///
    574 unsigned MachineJumpTableInfo::createJumpTableIndex(
    575                                const std::vector<MachineBasicBlock*> &DestBBs) {
    576   assert(!DestBBs.empty() && "Cannot create an empty jump table!");
    577   JumpTables.push_back(MachineJumpTableEntry(DestBBs));
    578   return JumpTables.size()-1;
    579 }
    580 
    581 /// ReplaceMBBInJumpTables - If Old is the target of any jump tables, update
    582 /// the jump tables to branch to New instead.
    583 bool MachineJumpTableInfo::ReplaceMBBInJumpTables(MachineBasicBlock *Old,
    584                                                   MachineBasicBlock *New) {
    585   assert(Old != New && "Not making a change?");
    586   bool MadeChange = false;
    587   for (size_t i = 0, e = JumpTables.size(); i != e; ++i)
    588     ReplaceMBBInJumpTable(i, Old, New);
    589   return MadeChange;
    590 }
    591 
    592 /// ReplaceMBBInJumpTable - If Old is a target of the jump tables, update
    593 /// the jump table to branch to New instead.
    594 bool MachineJumpTableInfo::ReplaceMBBInJumpTable(unsigned Idx,
    595                                                  MachineBasicBlock *Old,
    596                                                  MachineBasicBlock *New) {
    597   assert(Old != New && "Not making a change?");
    598   bool MadeChange = false;
    599   MachineJumpTableEntry &JTE = JumpTables[Idx];
    600   for (size_t j = 0, e = JTE.MBBs.size(); j != e; ++j)
    601     if (JTE.MBBs[j] == Old) {
    602       JTE.MBBs[j] = New;
    603       MadeChange = true;
    604     }
    605   return MadeChange;
    606 }
    607 
    608 void MachineJumpTableInfo::print(raw_ostream &OS) const {
    609   if (JumpTables.empty()) return;
    610 
    611   OS << "Jump Tables:\n";
    612 
    613   for (unsigned i = 0, e = JumpTables.size(); i != e; ++i) {
    614     OS << "  jt#" << i << ": ";
    615     for (unsigned j = 0, f = JumpTables[i].MBBs.size(); j != f; ++j)
    616       OS << " BB#" << JumpTables[i].MBBs[j]->getNumber();
    617   }
    618 
    619   OS << '\n';
    620 }
    621 
    622 void MachineJumpTableInfo::dump() const { print(dbgs()); }
    623 
    624 
    625 //===----------------------------------------------------------------------===//
    626 //  MachineConstantPool implementation
    627 //===----------------------------------------------------------------------===//
    628 
    629 void MachineConstantPoolValue::anchor() { }
    630 
    631 Type *MachineConstantPoolEntry::getType() const {
    632   if (isMachineConstantPoolEntry())
    633     return Val.MachineCPVal->getType();
    634   return Val.ConstVal->getType();
    635 }
    636 
    637 
    638 unsigned MachineConstantPoolEntry::getRelocationInfo() const {
    639   if (isMachineConstantPoolEntry())
    640     return Val.MachineCPVal->getRelocationInfo();
    641   return Val.ConstVal->getRelocationInfo();
    642 }
    643 
    644 MachineConstantPool::~MachineConstantPool() {
    645   for (unsigned i = 0, e = Constants.size(); i != e; ++i)
    646     if (Constants[i].isMachineConstantPoolEntry())
    647       delete Constants[i].Val.MachineCPVal;
    648   for (DenseSet<MachineConstantPoolValue*>::iterator I =
    649        MachineCPVsSharingEntries.begin(), E = MachineCPVsSharingEntries.end();
    650        I != E; ++I)
    651     delete *I;
    652 }
    653 
    654 /// CanShareConstantPoolEntry - Test whether the given two constants
    655 /// can be allocated the same constant pool entry.
    656 static bool CanShareConstantPoolEntry(const Constant *A, const Constant *B,
    657                                       const TargetData *TD) {
    658   // Handle the trivial case quickly.
    659   if (A == B) return true;
    660 
    661   // If they have the same type but weren't the same constant, quickly
    662   // reject them.
    663   if (A->getType() == B->getType()) return false;
    664 
    665   // We can't handle structs or arrays.
    666   if (isa<StructType>(A->getType()) || isa<ArrayType>(A->getType()) ||
    667       isa<StructType>(B->getType()) || isa<ArrayType>(B->getType()))
    668     return false;
    669 
    670   // For now, only support constants with the same size.
    671   uint64_t StoreSize = TD->getTypeStoreSize(A->getType());
    672   if (StoreSize != TD->getTypeStoreSize(B->getType()) ||
    673       StoreSize > 128)
    674     return false;
    675 
    676   Type *IntTy = IntegerType::get(A->getContext(), StoreSize*8);
    677 
    678   // Try constant folding a bitcast of both instructions to an integer.  If we
    679   // get two identical ConstantInt's, then we are good to share them.  We use
    680   // the constant folding APIs to do this so that we get the benefit of
    681   // TargetData.
    682   if (isa<PointerType>(A->getType()))
    683     A = ConstantFoldInstOperands(Instruction::PtrToInt, IntTy,
    684                                  const_cast<Constant*>(A), TD);
    685   else if (A->getType() != IntTy)
    686     A = ConstantFoldInstOperands(Instruction::BitCast, IntTy,
    687                                  const_cast<Constant*>(A), TD);
    688   if (isa<PointerType>(B->getType()))
    689     B = ConstantFoldInstOperands(Instruction::PtrToInt, IntTy,
    690                                  const_cast<Constant*>(B), TD);
    691   else if (B->getType() != IntTy)
    692     B = ConstantFoldInstOperands(Instruction::BitCast, IntTy,
    693                                  const_cast<Constant*>(B), TD);
    694 
    695   return A == B;
    696 }
    697 
    698 /// getConstantPoolIndex - Create a new entry in the constant pool or return
    699 /// an existing one.  User must specify the log2 of the minimum required
    700 /// alignment for the object.
    701 ///
    702 unsigned MachineConstantPool::getConstantPoolIndex(const Constant *C,
    703                                                    unsigned Alignment) {
    704   assert(Alignment && "Alignment must be specified!");
    705   if (Alignment > PoolAlignment) PoolAlignment = Alignment;
    706 
    707   // Check to see if we already have this constant.
    708   //
    709   // FIXME, this could be made much more efficient for large constant pools.
    710   for (unsigned i = 0, e = Constants.size(); i != e; ++i)
    711     if (!Constants[i].isMachineConstantPoolEntry() &&
    712         CanShareConstantPoolEntry(Constants[i].Val.ConstVal, C, TD)) {
    713       if ((unsigned)Constants[i].getAlignment() < Alignment)
    714         Constants[i].Alignment = Alignment;
    715       return i;
    716     }
    717 
    718   Constants.push_back(MachineConstantPoolEntry(C, Alignment));
    719   return Constants.size()-1;
    720 }
    721 
    722 unsigned MachineConstantPool::getConstantPoolIndex(MachineConstantPoolValue *V,
    723                                                    unsigned Alignment) {
    724   assert(Alignment && "Alignment must be specified!");
    725   if (Alignment > PoolAlignment) PoolAlignment = Alignment;
    726 
    727   // Check to see if we already have this constant.
    728   //
    729   // FIXME, this could be made much more efficient for large constant pools.
    730   int Idx = V->getExistingMachineCPValue(this, Alignment);
    731   if (Idx != -1) {
    732     MachineCPVsSharingEntries.insert(V);
    733     return (unsigned)Idx;
    734   }
    735 
    736   Constants.push_back(MachineConstantPoolEntry(V, Alignment));
    737   return Constants.size()-1;
    738 }
    739 
    740 void MachineConstantPool::print(raw_ostream &OS) const {
    741   if (Constants.empty()) return;
    742 
    743   OS << "Constant Pool:\n";
    744   for (unsigned i = 0, e = Constants.size(); i != e; ++i) {
    745     OS << "  cp#" << i << ": ";
    746     if (Constants[i].isMachineConstantPoolEntry())
    747       Constants[i].Val.MachineCPVal->print(OS);
    748     else
    749       OS << *(Value*)Constants[i].Val.ConstVal;
    750     OS << ", align=" << Constants[i].getAlignment();
    751     OS << "\n";
    752   }
    753 }
    754 
    755 void MachineConstantPool::dump() const { print(dbgs()); }
    756