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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/DebugInfo.h"
     18 #include "llvm/Function.h"
     19 #include "llvm/CodeGen/MachineConstantPool.h"
     20 #include "llvm/CodeGen/MachineFunctionPass.h"
     21 #include "llvm/CodeGen/MachineFrameInfo.h"
     22 #include "llvm/CodeGen/MachineInstr.h"
     23 #include "llvm/CodeGen/MachineJumpTableInfo.h"
     24 #include "llvm/CodeGen/MachineModuleInfo.h"
     25 #include "llvm/CodeGen/MachineRegisterInfo.h"
     26 #include "llvm/CodeGen/Passes.h"
     27 #include "llvm/MC/MCAsmInfo.h"
     28 #include "llvm/MC/MCContext.h"
     29 #include "llvm/Analysis/ConstantFolding.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->ensureMaxAlignment(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 
     88   FrameInfo->~MachineFrameInfo();
     89   Allocator.Deallocate(FrameInfo);
     90 
     91   ConstantPool->~MachineConstantPool();
     92   Allocator.Deallocate(ConstantPool);
     93 
     94   if (JumpTableInfo) {
     95     JumpTableInfo->~MachineJumpTableInfo();
     96     Allocator.Deallocate(JumpTableInfo);
     97   }
     98 }
     99 
    100 /// getOrCreateJumpTableInfo - Get the JumpTableInfo for this function, if it
    101 /// does already exist, allocate one.
    102 MachineJumpTableInfo *MachineFunction::
    103 getOrCreateJumpTableInfo(unsigned EntryKind) {
    104   if (JumpTableInfo) return JumpTableInfo;
    105 
    106   JumpTableInfo = new (Allocator)
    107     MachineJumpTableInfo((MachineJumpTableInfo::JTEntryKind)EntryKind);
    108   return JumpTableInfo;
    109 }
    110 
    111 /// RenumberBlocks - This discards all of the MachineBasicBlock numbers and
    112 /// recomputes them.  This guarantees that the MBB numbers are sequential,
    113 /// dense, and match the ordering of the blocks within the function.  If a
    114 /// specific MachineBasicBlock is specified, only that block and those after
    115 /// it are renumbered.
    116 void MachineFunction::RenumberBlocks(MachineBasicBlock *MBB) {
    117   if (empty()) { MBBNumbering.clear(); return; }
    118   MachineFunction::iterator MBBI, E = end();
    119   if (MBB == 0)
    120     MBBI = begin();
    121   else
    122     MBBI = MBB;
    123 
    124   // Figure out the block number this should have.
    125   unsigned BlockNo = 0;
    126   if (MBBI != begin())
    127     BlockNo = prior(MBBI)->getNumber()+1;
    128 
    129   for (; MBBI != E; ++MBBI, ++BlockNo) {
    130     if (MBBI->getNumber() != (int)BlockNo) {
    131       // Remove use of the old number.
    132       if (MBBI->getNumber() != -1) {
    133         assert(MBBNumbering[MBBI->getNumber()] == &*MBBI &&
    134                "MBB number mismatch!");
    135         MBBNumbering[MBBI->getNumber()] = 0;
    136       }
    137 
    138       // If BlockNo is already taken, set that block's number to -1.
    139       if (MBBNumbering[BlockNo])
    140         MBBNumbering[BlockNo]->setNumber(-1);
    141 
    142       MBBNumbering[BlockNo] = MBBI;
    143       MBBI->setNumber(BlockNo);
    144     }
    145   }
    146 
    147   // Okay, all the blocks are renumbered.  If we have compactified the block
    148   // numbering, shrink MBBNumbering now.
    149   assert(BlockNo <= MBBNumbering.size() && "Mismatch!");
    150   MBBNumbering.resize(BlockNo);
    151 }
    152 
    153 /// CreateMachineInstr - Allocate a new MachineInstr. Use this instead
    154 /// of `new MachineInstr'.
    155 ///
    156 MachineInstr *
    157 MachineFunction::CreateMachineInstr(const MCInstrDesc &MCID,
    158                                     DebugLoc DL, bool NoImp) {
    159   return new (InstructionRecycler.Allocate<MachineInstr>(Allocator))
    160     MachineInstr(MCID, DL, NoImp);
    161 }
    162 
    163 /// CloneMachineInstr - Create a new MachineInstr which is a copy of the
    164 /// 'Orig' instruction, identical in all ways except the instruction
    165 /// has no parent, prev, or next.
    166 ///
    167 MachineInstr *
    168 MachineFunction::CloneMachineInstr(const MachineInstr *Orig) {
    169   return new (InstructionRecycler.Allocate<MachineInstr>(Allocator))
    170              MachineInstr(*this, *Orig);
    171 }
    172 
    173 /// DeleteMachineInstr - Delete the given MachineInstr.
    174 ///
    175 void
    176 MachineFunction::DeleteMachineInstr(MachineInstr *MI) {
    177   MI->~MachineInstr();
    178   InstructionRecycler.Deallocate(Allocator, MI);
    179 }
    180 
    181 /// CreateMachineBasicBlock - Allocate a new MachineBasicBlock. Use this
    182 /// instead of `new MachineBasicBlock'.
    183 ///
    184 MachineBasicBlock *
    185 MachineFunction::CreateMachineBasicBlock(const BasicBlock *bb) {
    186   return new (BasicBlockRecycler.Allocate<MachineBasicBlock>(Allocator))
    187              MachineBasicBlock(*this, bb);
    188 }
    189 
    190 /// DeleteMachineBasicBlock - Delete the given MachineBasicBlock.
    191 ///
    192 void
    193 MachineFunction::DeleteMachineBasicBlock(MachineBasicBlock *MBB) {
    194   assert(MBB->getParent() == this && "MBB parent mismatch!");
    195   MBB->~MachineBasicBlock();
    196   BasicBlockRecycler.Deallocate(Allocator, MBB);
    197 }
    198 
    199 MachineMemOperand *
    200 MachineFunction::getMachineMemOperand(MachinePointerInfo PtrInfo, unsigned f,
    201                                       uint64_t s, unsigned base_alignment,
    202                                       const MDNode *TBAAInfo,
    203                                       const MDNode *Ranges) {
    204   return new (Allocator) MachineMemOperand(PtrInfo, f, s, base_alignment,
    205                                            TBAAInfo, Ranges);
    206 }
    207 
    208 MachineMemOperand *
    209 MachineFunction::getMachineMemOperand(const MachineMemOperand *MMO,
    210                                       int64_t Offset, uint64_t Size) {
    211   return new (Allocator)
    212              MachineMemOperand(MachinePointerInfo(MMO->getValue(),
    213                                                   MMO->getOffset()+Offset),
    214                                MMO->getFlags(), Size,
    215                                MMO->getBaseAlignment(), 0);
    216 }
    217 
    218 MachineInstr::mmo_iterator
    219 MachineFunction::allocateMemRefsArray(unsigned long Num) {
    220   return Allocator.Allocate<MachineMemOperand *>(Num);
    221 }
    222 
    223 std::pair<MachineInstr::mmo_iterator, MachineInstr::mmo_iterator>
    224 MachineFunction::extractLoadMemRefs(MachineInstr::mmo_iterator Begin,
    225                                     MachineInstr::mmo_iterator End) {
    226   // Count the number of load mem refs.
    227   unsigned Num = 0;
    228   for (MachineInstr::mmo_iterator I = Begin; I != End; ++I)
    229     if ((*I)->isLoad())
    230       ++Num;
    231 
    232   // Allocate a new array and populate it with the load information.
    233   MachineInstr::mmo_iterator Result = allocateMemRefsArray(Num);
    234   unsigned Index = 0;
    235   for (MachineInstr::mmo_iterator I = Begin; I != End; ++I) {
    236     if ((*I)->isLoad()) {
    237       if (!(*I)->isStore())
    238         // Reuse the MMO.
    239         Result[Index] = *I;
    240       else {
    241         // Clone the MMO and unset the store flag.
    242         MachineMemOperand *JustLoad =
    243           getMachineMemOperand((*I)->getPointerInfo(),
    244                                (*I)->getFlags() & ~MachineMemOperand::MOStore,
    245                                (*I)->getSize(), (*I)->getBaseAlignment(),
    246                                (*I)->getTBAAInfo());
    247         Result[Index] = JustLoad;
    248       }
    249       ++Index;
    250     }
    251   }
    252   return std::make_pair(Result, Result + Num);
    253 }
    254 
    255 std::pair<MachineInstr::mmo_iterator, MachineInstr::mmo_iterator>
    256 MachineFunction::extractStoreMemRefs(MachineInstr::mmo_iterator Begin,
    257                                      MachineInstr::mmo_iterator End) {
    258   // Count the number of load mem refs.
    259   unsigned Num = 0;
    260   for (MachineInstr::mmo_iterator I = Begin; I != End; ++I)
    261     if ((*I)->isStore())
    262       ++Num;
    263 
    264   // Allocate a new array and populate it with the store information.
    265   MachineInstr::mmo_iterator Result = allocateMemRefsArray(Num);
    266   unsigned Index = 0;
    267   for (MachineInstr::mmo_iterator I = Begin; I != End; ++I) {
    268     if ((*I)->isStore()) {
    269       if (!(*I)->isLoad())
    270         // Reuse the MMO.
    271         Result[Index] = *I;
    272       else {
    273         // Clone the MMO and unset the load flag.
    274         MachineMemOperand *JustStore =
    275           getMachineMemOperand((*I)->getPointerInfo(),
    276                                (*I)->getFlags() & ~MachineMemOperand::MOLoad,
    277                                (*I)->getSize(), (*I)->getBaseAlignment(),
    278                                (*I)->getTBAAInfo());
    279         Result[Index] = JustStore;
    280       }
    281       ++Index;
    282     }
    283   }
    284   return std::make_pair(Result, Result + Num);
    285 }
    286 
    287 #ifndef NDEBUG
    288 void MachineFunction::dump() const {
    289   print(dbgs());
    290 }
    291 #endif
    292 
    293 StringRef MachineFunction::getName() const {
    294   assert(getFunction() && "No function!");
    295   return getFunction()->getName();
    296 }
    297 
    298 void MachineFunction::print(raw_ostream &OS, SlotIndexes *Indexes) const {
    299   OS << "# Machine code for function " << getName() << ": ";
    300   if (RegInfo) {
    301     OS << (RegInfo->isSSA() ? "SSA" : "Post SSA");
    302     if (!RegInfo->tracksLiveness())
    303       OS << ", not tracking liveness";
    304   }
    305   OS << '\n';
    306 
    307   // Print Frame Information
    308   FrameInfo->print(*this, OS);
    309 
    310   // Print JumpTable Information
    311   if (JumpTableInfo)
    312     JumpTableInfo->print(OS);
    313 
    314   // Print Constant Pool
    315   ConstantPool->print(OS);
    316 
    317   const TargetRegisterInfo *TRI = getTarget().getRegisterInfo();
    318 
    319   if (RegInfo && !RegInfo->livein_empty()) {
    320     OS << "Function Live Ins: ";
    321     for (MachineRegisterInfo::livein_iterator
    322          I = RegInfo->livein_begin(), E = RegInfo->livein_end(); I != E; ++I) {
    323       OS << PrintReg(I->first, TRI);
    324       if (I->second)
    325         OS << " in " << PrintReg(I->second, TRI);
    326       if (llvm::next(I) != E)
    327         OS << ", ";
    328     }
    329     OS << '\n';
    330   }
    331   if (RegInfo && !RegInfo->liveout_empty()) {
    332     OS << "Function Live Outs:";
    333     for (MachineRegisterInfo::liveout_iterator
    334          I = RegInfo->liveout_begin(), E = RegInfo->liveout_end(); I != E; ++I)
    335       OS << ' ' << PrintReg(*I, TRI);
    336     OS << '\n';
    337   }
    338 
    339   for (const_iterator BB = begin(), E = end(); BB != E; ++BB) {
    340     OS << '\n';
    341     BB->print(OS, Indexes);
    342   }
    343 
    344   OS << "\n# End machine code for function " << getName() << ".\n\n";
    345 }
    346 
    347 namespace llvm {
    348   template<>
    349   struct DOTGraphTraits<const MachineFunction*> : public DefaultDOTGraphTraits {
    350 
    351   DOTGraphTraits (bool isSimple=false) : DefaultDOTGraphTraits(isSimple) {}
    352 
    353     static std::string getGraphName(const MachineFunction *F) {
    354       return "CFG for '" + F->getName().str() + "' function";
    355     }
    356 
    357     std::string getNodeLabel(const MachineBasicBlock *Node,
    358                              const MachineFunction *Graph) {
    359       std::string OutStr;
    360       {
    361         raw_string_ostream OSS(OutStr);
    362 
    363         if (isSimple()) {
    364           OSS << "BB#" << Node->getNumber();
    365           if (const BasicBlock *BB = Node->getBasicBlock())
    366             OSS << ": " << BB->getName();
    367         } else
    368           Node->print(OSS);
    369       }
    370 
    371       if (OutStr[0] == '\n') OutStr.erase(OutStr.begin());
    372 
    373       // Process string output to make it nicer...
    374       for (unsigned i = 0; i != OutStr.length(); ++i)
    375         if (OutStr[i] == '\n') {                            // Left justify
    376           OutStr[i] = '\\';
    377           OutStr.insert(OutStr.begin()+i+1, 'l');
    378         }
    379       return OutStr;
    380     }
    381   };
    382 }
    383 
    384 void MachineFunction::viewCFG() const
    385 {
    386 #ifndef NDEBUG
    387   ViewGraph(this, "mf" + getName());
    388 #else
    389   errs() << "MachineFunction::viewCFG is only available in debug builds on "
    390          << "systems with Graphviz or gv!\n";
    391 #endif // NDEBUG
    392 }
    393 
    394 void MachineFunction::viewCFGOnly() const
    395 {
    396 #ifndef NDEBUG
    397   ViewGraph(this, "mf" + getName(), true);
    398 #else
    399   errs() << "MachineFunction::viewCFGOnly is only available in debug builds on "
    400          << "systems with Graphviz or gv!\n";
    401 #endif // NDEBUG
    402 }
    403 
    404 /// addLiveIn - Add the specified physical register as a live-in value and
    405 /// create a corresponding virtual register for it.
    406 unsigned MachineFunction::addLiveIn(unsigned PReg,
    407                                     const TargetRegisterClass *RC) {
    408   MachineRegisterInfo &MRI = getRegInfo();
    409   unsigned VReg = MRI.getLiveInVirtReg(PReg);
    410   if (VReg) {
    411     assert(MRI.getRegClass(VReg) == RC && "Register class mismatch!");
    412     return VReg;
    413   }
    414   VReg = MRI.createVirtualRegister(RC);
    415   MRI.addLiveIn(PReg, VReg);
    416   return VReg;
    417 }
    418 
    419 /// getJTISymbol - Return the MCSymbol for the specified non-empty jump table.
    420 /// If isLinkerPrivate is specified, an 'l' label is returned, otherwise a
    421 /// normal 'L' label is returned.
    422 MCSymbol *MachineFunction::getJTISymbol(unsigned JTI, MCContext &Ctx,
    423                                         bool isLinkerPrivate) const {
    424   assert(JumpTableInfo && "No jump tables");
    425   assert(JTI < JumpTableInfo->getJumpTables().size() && "Invalid JTI!");
    426   const MCAsmInfo &MAI = *getTarget().getMCAsmInfo();
    427 
    428   const char *Prefix = isLinkerPrivate ? MAI.getLinkerPrivateGlobalPrefix() :
    429                                          MAI.getPrivateGlobalPrefix();
    430   SmallString<60> Name;
    431   raw_svector_ostream(Name)
    432     << Prefix << "JTI" << getFunctionNumber() << '_' << JTI;
    433   return Ctx.GetOrCreateSymbol(Name.str());
    434 }
    435 
    436 /// getPICBaseSymbol - Return a function-local symbol to represent the PIC
    437 /// base.
    438 MCSymbol *MachineFunction::getPICBaseSymbol() const {
    439   const MCAsmInfo &MAI = *Target.getMCAsmInfo();
    440   return Ctx.GetOrCreateSymbol(Twine(MAI.getPrivateGlobalPrefix())+
    441                                Twine(getFunctionNumber())+"$pb");
    442 }
    443 
    444 //===----------------------------------------------------------------------===//
    445 //  MachineFrameInfo implementation
    446 //===----------------------------------------------------------------------===//
    447 
    448 /// CreateFixedObject - Create a new object at a fixed location on the stack.
    449 /// All fixed objects should be created before other objects are created for
    450 /// efficiency. By default, fixed objects are immutable. This returns an
    451 /// index with a negative value.
    452 ///
    453 int MachineFrameInfo::CreateFixedObject(uint64_t Size, int64_t SPOffset,
    454                                         bool Immutable) {
    455   assert(Size != 0 && "Cannot allocate zero size fixed stack objects!");
    456   // The alignment of the frame index can be determined from its offset from
    457   // the incoming frame position.  If the frame object is at offset 32 and
    458   // the stack is guaranteed to be 16-byte aligned, then we know that the
    459   // object is 16-byte aligned.
    460   unsigned StackAlign = TFI.getStackAlignment();
    461   unsigned Align = MinAlign(SPOffset, StackAlign);
    462   Objects.insert(Objects.begin(), StackObject(Size, Align, SPOffset, Immutable,
    463                                               /*isSS*/   false,
    464                                               /*NeedSP*/ false,
    465                                               /*Alloca*/ 0));
    466   return -++NumFixedObjects;
    467 }
    468 
    469 
    470 BitVector
    471 MachineFrameInfo::getPristineRegs(const MachineBasicBlock *MBB) const {
    472   assert(MBB && "MBB must be valid");
    473   const MachineFunction *MF = MBB->getParent();
    474   assert(MF && "MBB must be part of a MachineFunction");
    475   const TargetMachine &TM = MF->getTarget();
    476   const TargetRegisterInfo *TRI = TM.getRegisterInfo();
    477   BitVector BV(TRI->getNumRegs());
    478 
    479   // Before CSI is calculated, no registers are considered pristine. They can be
    480   // freely used and PEI will make sure they are saved.
    481   if (!isCalleeSavedInfoValid())
    482     return BV;
    483 
    484   for (const uint16_t *CSR = TRI->getCalleeSavedRegs(MF); CSR && *CSR; ++CSR)
    485     BV.set(*CSR);
    486 
    487   // The entry MBB always has all CSRs pristine.
    488   if (MBB == &MF->front())
    489     return BV;
    490 
    491   // On other MBBs the saved CSRs are not pristine.
    492   const std::vector<CalleeSavedInfo> &CSI = getCalleeSavedInfo();
    493   for (std::vector<CalleeSavedInfo>::const_iterator I = CSI.begin(),
    494          E = CSI.end(); I != E; ++I)
    495     BV.reset(I->getReg());
    496 
    497   return BV;
    498 }
    499 
    500 
    501 void MachineFrameInfo::print(const MachineFunction &MF, raw_ostream &OS) const{
    502   if (Objects.empty()) return;
    503 
    504   const TargetFrameLowering *FI = MF.getTarget().getFrameLowering();
    505   int ValOffset = (FI ? FI->getOffsetOfLocalArea() : 0);
    506 
    507   OS << "Frame Objects:\n";
    508 
    509   for (unsigned i = 0, e = Objects.size(); i != e; ++i) {
    510     const StackObject &SO = Objects[i];
    511     OS << "  fi#" << (int)(i-NumFixedObjects) << ": ";
    512     if (SO.Size == ~0ULL) {
    513       OS << "dead\n";
    514       continue;
    515     }
    516     if (SO.Size == 0)
    517       OS << "variable sized";
    518     else
    519       OS << "size=" << SO.Size;
    520     OS << ", align=" << SO.Alignment;
    521 
    522     if (i < NumFixedObjects)
    523       OS << ", fixed";
    524     if (i < NumFixedObjects || SO.SPOffset != -1) {
    525       int64_t Off = SO.SPOffset - ValOffset;
    526       OS << ", at location [SP";
    527       if (Off > 0)
    528         OS << "+" << Off;
    529       else if (Off < 0)
    530         OS << Off;
    531       OS << "]";
    532     }
    533     OS << "\n";
    534   }
    535 }
    536 
    537 #ifndef NDEBUG
    538 void MachineFrameInfo::dump(const MachineFunction &MF) const {
    539   print(MF, dbgs());
    540 }
    541 #endif
    542 
    543 //===----------------------------------------------------------------------===//
    544 //  MachineJumpTableInfo implementation
    545 //===----------------------------------------------------------------------===//
    546 
    547 /// getEntrySize - Return the size of each entry in the jump table.
    548 unsigned MachineJumpTableInfo::getEntrySize(const TargetData &TD) const {
    549   // The size of a jump table entry is 4 bytes unless the entry is just the
    550   // address of a block, in which case it is the pointer size.
    551   switch (getEntryKind()) {
    552   case MachineJumpTableInfo::EK_BlockAddress:
    553     return TD.getPointerSize();
    554   case MachineJumpTableInfo::EK_GPRel64BlockAddress:
    555     return 8;
    556   case MachineJumpTableInfo::EK_GPRel32BlockAddress:
    557   case MachineJumpTableInfo::EK_LabelDifference32:
    558   case MachineJumpTableInfo::EK_Custom32:
    559     return 4;
    560   case MachineJumpTableInfo::EK_Inline:
    561     return 0;
    562   }
    563   llvm_unreachable("Unknown jump table encoding!");
    564 }
    565 
    566 /// getEntryAlignment - Return the alignment of each entry in the jump table.
    567 unsigned MachineJumpTableInfo::getEntryAlignment(const TargetData &TD) const {
    568   // The alignment of a jump table entry is the alignment of int32 unless the
    569   // entry is just the address of a block, in which case it is the pointer
    570   // alignment.
    571   switch (getEntryKind()) {
    572   case MachineJumpTableInfo::EK_BlockAddress:
    573     return TD.getPointerABIAlignment();
    574   case MachineJumpTableInfo::EK_GPRel64BlockAddress:
    575     return TD.getABIIntegerTypeAlignment(64);
    576   case MachineJumpTableInfo::EK_GPRel32BlockAddress:
    577   case MachineJumpTableInfo::EK_LabelDifference32:
    578   case MachineJumpTableInfo::EK_Custom32:
    579     return TD.getABIIntegerTypeAlignment(32);
    580   case MachineJumpTableInfo::EK_Inline:
    581     return 1;
    582   }
    583   llvm_unreachable("Unknown jump table encoding!");
    584 }
    585 
    586 /// createJumpTableIndex - Create a new jump table entry in the jump table info.
    587 ///
    588 unsigned MachineJumpTableInfo::createJumpTableIndex(
    589                                const std::vector<MachineBasicBlock*> &DestBBs) {
    590   assert(!DestBBs.empty() && "Cannot create an empty jump table!");
    591   JumpTables.push_back(MachineJumpTableEntry(DestBBs));
    592   return JumpTables.size()-1;
    593 }
    594 
    595 /// ReplaceMBBInJumpTables - If Old is the target of any jump tables, update
    596 /// the jump tables to branch to New instead.
    597 bool MachineJumpTableInfo::ReplaceMBBInJumpTables(MachineBasicBlock *Old,
    598                                                   MachineBasicBlock *New) {
    599   assert(Old != New && "Not making a change?");
    600   bool MadeChange = false;
    601   for (size_t i = 0, e = JumpTables.size(); i != e; ++i)
    602     ReplaceMBBInJumpTable(i, Old, New);
    603   return MadeChange;
    604 }
    605 
    606 /// ReplaceMBBInJumpTable - If Old is a target of the jump tables, update
    607 /// the jump table to branch to New instead.
    608 bool MachineJumpTableInfo::ReplaceMBBInJumpTable(unsigned Idx,
    609                                                  MachineBasicBlock *Old,
    610                                                  MachineBasicBlock *New) {
    611   assert(Old != New && "Not making a change?");
    612   bool MadeChange = false;
    613   MachineJumpTableEntry &JTE = JumpTables[Idx];
    614   for (size_t j = 0, e = JTE.MBBs.size(); j != e; ++j)
    615     if (JTE.MBBs[j] == Old) {
    616       JTE.MBBs[j] = New;
    617       MadeChange = true;
    618     }
    619   return MadeChange;
    620 }
    621 
    622 void MachineJumpTableInfo::print(raw_ostream &OS) const {
    623   if (JumpTables.empty()) return;
    624 
    625   OS << "Jump Tables:\n";
    626 
    627   for (unsigned i = 0, e = JumpTables.size(); i != e; ++i) {
    628     OS << "  jt#" << i << ": ";
    629     for (unsigned j = 0, f = JumpTables[i].MBBs.size(); j != f; ++j)
    630       OS << " BB#" << JumpTables[i].MBBs[j]->getNumber();
    631   }
    632 
    633   OS << '\n';
    634 }
    635 
    636 #ifndef NDEBUG
    637 void MachineJumpTableInfo::dump() const { print(dbgs()); }
    638 #endif
    639 
    640 
    641 //===----------------------------------------------------------------------===//
    642 //  MachineConstantPool implementation
    643 //===----------------------------------------------------------------------===//
    644 
    645 void MachineConstantPoolValue::anchor() { }
    646 
    647 Type *MachineConstantPoolEntry::getType() const {
    648   if (isMachineConstantPoolEntry())
    649     return Val.MachineCPVal->getType();
    650   return Val.ConstVal->getType();
    651 }
    652 
    653 
    654 unsigned MachineConstantPoolEntry::getRelocationInfo() const {
    655   if (isMachineConstantPoolEntry())
    656     return Val.MachineCPVal->getRelocationInfo();
    657   return Val.ConstVal->getRelocationInfo();
    658 }
    659 
    660 MachineConstantPool::~MachineConstantPool() {
    661   for (unsigned i = 0, e = Constants.size(); i != e; ++i)
    662     if (Constants[i].isMachineConstantPoolEntry())
    663       delete Constants[i].Val.MachineCPVal;
    664   for (DenseSet<MachineConstantPoolValue*>::iterator I =
    665        MachineCPVsSharingEntries.begin(), E = MachineCPVsSharingEntries.end();
    666        I != E; ++I)
    667     delete *I;
    668 }
    669 
    670 /// CanShareConstantPoolEntry - Test whether the given two constants
    671 /// can be allocated the same constant pool entry.
    672 static bool CanShareConstantPoolEntry(const Constant *A, const Constant *B,
    673                                       const TargetData *TD) {
    674   // Handle the trivial case quickly.
    675   if (A == B) return true;
    676 
    677   // If they have the same type but weren't the same constant, quickly
    678   // reject them.
    679   if (A->getType() == B->getType()) return false;
    680 
    681   // We can't handle structs or arrays.
    682   if (isa<StructType>(A->getType()) || isa<ArrayType>(A->getType()) ||
    683       isa<StructType>(B->getType()) || isa<ArrayType>(B->getType()))
    684     return false;
    685 
    686   // For now, only support constants with the same size.
    687   uint64_t StoreSize = TD->getTypeStoreSize(A->getType());
    688   if (StoreSize != TD->getTypeStoreSize(B->getType()) ||
    689       StoreSize > 128)
    690     return false;
    691 
    692   Type *IntTy = IntegerType::get(A->getContext(), StoreSize*8);
    693 
    694   // Try constant folding a bitcast of both instructions to an integer.  If we
    695   // get two identical ConstantInt's, then we are good to share them.  We use
    696   // the constant folding APIs to do this so that we get the benefit of
    697   // TargetData.
    698   if (isa<PointerType>(A->getType()))
    699     A = ConstantFoldInstOperands(Instruction::PtrToInt, IntTy,
    700                                  const_cast<Constant*>(A), TD);
    701   else if (A->getType() != IntTy)
    702     A = ConstantFoldInstOperands(Instruction::BitCast, IntTy,
    703                                  const_cast<Constant*>(A), TD);
    704   if (isa<PointerType>(B->getType()))
    705     B = ConstantFoldInstOperands(Instruction::PtrToInt, IntTy,
    706                                  const_cast<Constant*>(B), TD);
    707   else if (B->getType() != IntTy)
    708     B = ConstantFoldInstOperands(Instruction::BitCast, IntTy,
    709                                  const_cast<Constant*>(B), TD);
    710 
    711   return A == B;
    712 }
    713 
    714 /// getConstantPoolIndex - Create a new entry in the constant pool or return
    715 /// an existing one.  User must specify the log2 of the minimum required
    716 /// alignment for the object.
    717 ///
    718 unsigned MachineConstantPool::getConstantPoolIndex(const Constant *C,
    719                                                    unsigned Alignment) {
    720   assert(Alignment && "Alignment must be specified!");
    721   if (Alignment > PoolAlignment) PoolAlignment = Alignment;
    722 
    723   // Check to see if we already have this constant.
    724   //
    725   // FIXME, this could be made much more efficient for large constant pools.
    726   for (unsigned i = 0, e = Constants.size(); i != e; ++i)
    727     if (!Constants[i].isMachineConstantPoolEntry() &&
    728         CanShareConstantPoolEntry(Constants[i].Val.ConstVal, C, TD)) {
    729       if ((unsigned)Constants[i].getAlignment() < Alignment)
    730         Constants[i].Alignment = Alignment;
    731       return i;
    732     }
    733 
    734   Constants.push_back(MachineConstantPoolEntry(C, Alignment));
    735   return Constants.size()-1;
    736 }
    737 
    738 unsigned MachineConstantPool::getConstantPoolIndex(MachineConstantPoolValue *V,
    739                                                    unsigned Alignment) {
    740   assert(Alignment && "Alignment must be specified!");
    741   if (Alignment > PoolAlignment) PoolAlignment = Alignment;
    742 
    743   // Check to see if we already have this constant.
    744   //
    745   // FIXME, this could be made much more efficient for large constant pools.
    746   int Idx = V->getExistingMachineCPValue(this, Alignment);
    747   if (Idx != -1) {
    748     MachineCPVsSharingEntries.insert(V);
    749     return (unsigned)Idx;
    750   }
    751 
    752   Constants.push_back(MachineConstantPoolEntry(V, Alignment));
    753   return Constants.size()-1;
    754 }
    755 
    756 void MachineConstantPool::print(raw_ostream &OS) const {
    757   if (Constants.empty()) return;
    758 
    759   OS << "Constant Pool:\n";
    760   for (unsigned i = 0, e = Constants.size(); i != e; ++i) {
    761     OS << "  cp#" << i << ": ";
    762     if (Constants[i].isMachineConstantPoolEntry())
    763       Constants[i].Val.MachineCPVal->print(OS);
    764     else
    765       OS << *(const Value*)Constants[i].Val.ConstVal;
    766     OS << ", align=" << Constants[i].getAlignment();
    767     OS << "\n";
    768   }
    769 }
    770 
    771 #ifndef NDEBUG
    772 void MachineConstantPool::dump() const { print(dbgs()); }
    773 #endif
    774