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      1 //===-- PPCMCInstLower.cpp - Convert PPC MachineInstr to an MCInst --------===//
      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 // This file contains code to lower PPC MachineInstrs to their corresponding
     11 // MCInst records.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #include "PPC.h"
     16 #include "MCTargetDesc/PPCMCExpr.h"
     17 #include "PPCSubtarget.h"
     18 #include "llvm/ADT/SmallString.h"
     19 #include "llvm/ADT/Twine.h"
     20 #include "llvm/CodeGen/AsmPrinter.h"
     21 #include "llvm/CodeGen/MachineFunction.h"
     22 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
     23 #include "llvm/IR/DataLayout.h"
     24 #include "llvm/IR/GlobalValue.h"
     25 #include "llvm/IR/Mangler.h"
     26 #include "llvm/MC/MCAsmInfo.h"
     27 #include "llvm/MC/MCExpr.h"
     28 #include "llvm/MC/MCInst.h"
     29 #include "llvm/Target/TargetLowering.h"
     30 #include "llvm/Target/TargetLoweringObjectFile.h"
     31 using namespace llvm;
     32 
     33 static MachineModuleInfoMachO &getMachOMMI(AsmPrinter &AP) {
     34   return AP.MMI->getObjFileInfo<MachineModuleInfoMachO>();
     35 }
     36 
     37 
     38 static MCSymbol *GetSymbolFromOperand(const MachineOperand &MO, AsmPrinter &AP){
     39   const TargetMachine &TM = AP.TM;
     40   Mangler *Mang = AP.Mang;
     41   const DataLayout &DL = AP.getDataLayout();
     42   MCContext &Ctx = AP.OutContext;
     43   bool isDarwin = TM.getTargetTriple().isOSDarwin();
     44 
     45   SmallString<128> Name;
     46   StringRef Suffix;
     47   if (MO.getTargetFlags() == PPCII::MO_PLT_OR_STUB) {
     48     if (isDarwin)
     49       Suffix = "$stub";
     50   } else if (MO.getTargetFlags() & PPCII::MO_NLP_FLAG)
     51     Suffix = "$non_lazy_ptr";
     52 
     53   if (!Suffix.empty())
     54     Name += DL.getPrivateGlobalPrefix();
     55 
     56   unsigned PrefixLen = Name.size();
     57 
     58   if (!MO.isGlobal()) {
     59     assert(MO.isSymbol() && "Isn't a symbol reference");
     60     Mangler::getNameWithPrefix(Name, MO.getSymbolName(), DL);
     61   } else {
     62     const GlobalValue *GV = MO.getGlobal();
     63     TM.getNameWithPrefix(Name, GV, *Mang);
     64   }
     65 
     66   unsigned OrigLen = Name.size() - PrefixLen;
     67 
     68   Name += Suffix;
     69   MCSymbol *Sym = Ctx.getOrCreateSymbol(Name);
     70   StringRef OrigName = StringRef(Name).substr(PrefixLen, OrigLen);
     71 
     72   // If the target flags on the operand changes the name of the symbol, do that
     73   // before we return the symbol.
     74   if (MO.getTargetFlags() == PPCII::MO_PLT_OR_STUB && isDarwin) {
     75     MachineModuleInfoImpl::StubValueTy &StubSym =
     76       getMachOMMI(AP).getFnStubEntry(Sym);
     77     if (StubSym.getPointer())
     78       return Sym;
     79 
     80     if (MO.isGlobal()) {
     81       StubSym =
     82       MachineModuleInfoImpl::
     83       StubValueTy(AP.getSymbol(MO.getGlobal()),
     84                   !MO.getGlobal()->hasInternalLinkage());
     85     } else {
     86       StubSym =
     87       MachineModuleInfoImpl::
     88       StubValueTy(Ctx.getOrCreateSymbol(OrigName), false);
     89     }
     90     return Sym;
     91   }
     92 
     93   // If the symbol reference is actually to a non_lazy_ptr, not to the symbol,
     94   // then add the suffix.
     95   if (MO.getTargetFlags() & PPCII::MO_NLP_FLAG) {
     96     MachineModuleInfoMachO &MachO = getMachOMMI(AP);
     97 
     98     MachineModuleInfoImpl::StubValueTy &StubSym =
     99       (MO.getTargetFlags() & PPCII::MO_NLP_HIDDEN_FLAG) ?
    100          MachO.getHiddenGVStubEntry(Sym) : MachO.getGVStubEntry(Sym);
    101 
    102     if (!StubSym.getPointer()) {
    103       assert(MO.isGlobal() && "Extern symbol not handled yet");
    104       StubSym = MachineModuleInfoImpl::
    105                    StubValueTy(AP.getSymbol(MO.getGlobal()),
    106                                !MO.getGlobal()->hasInternalLinkage());
    107     }
    108     return Sym;
    109   }
    110 
    111   return Sym;
    112 }
    113 
    114 static MCOperand GetSymbolRef(const MachineOperand &MO, const MCSymbol *Symbol,
    115                               AsmPrinter &Printer, bool isDarwin) {
    116   MCContext &Ctx = Printer.OutContext;
    117   MCSymbolRefExpr::VariantKind RefKind = MCSymbolRefExpr::VK_None;
    118 
    119   unsigned access = MO.getTargetFlags() & PPCII::MO_ACCESS_MASK;
    120 
    121   switch (access) {
    122     case PPCII::MO_TPREL_LO:
    123       RefKind = MCSymbolRefExpr::VK_PPC_TPREL_LO;
    124       break;
    125     case PPCII::MO_TPREL_HA:
    126       RefKind = MCSymbolRefExpr::VK_PPC_TPREL_HA;
    127       break;
    128     case PPCII::MO_DTPREL_LO:
    129       RefKind = MCSymbolRefExpr::VK_PPC_DTPREL_LO;
    130       break;
    131     case PPCII::MO_TLSLD_LO:
    132       RefKind = MCSymbolRefExpr::VK_PPC_GOT_TLSLD_LO;
    133       break;
    134     case PPCII::MO_TOC_LO:
    135       RefKind = MCSymbolRefExpr::VK_PPC_TOC_LO;
    136       break;
    137     case PPCII::MO_TLS:
    138       RefKind = MCSymbolRefExpr::VK_PPC_TLS;
    139       break;
    140   }
    141 
    142   if (MO.getTargetFlags() == PPCII::MO_PLT_OR_STUB && !isDarwin)
    143     RefKind = MCSymbolRefExpr::VK_PLT;
    144 
    145   const MCExpr *Expr = MCSymbolRefExpr::create(Symbol, RefKind, Ctx);
    146 
    147   if (!MO.isJTI() && MO.getOffset())
    148     Expr = MCBinaryExpr::createAdd(Expr,
    149                                    MCConstantExpr::create(MO.getOffset(), Ctx),
    150                                    Ctx);
    151 
    152   // Subtract off the PIC base if required.
    153   if (MO.getTargetFlags() & PPCII::MO_PIC_FLAG) {
    154     const MachineFunction *MF = MO.getParent()->getParent()->getParent();
    155 
    156     const MCExpr *PB = MCSymbolRefExpr::create(MF->getPICBaseSymbol(), Ctx);
    157     Expr = MCBinaryExpr::createSub(Expr, PB, Ctx);
    158   }
    159 
    160   // Add ha16() / lo16() markers if required.
    161   switch (access) {
    162     case PPCII::MO_LO:
    163       Expr = PPCMCExpr::createLo(Expr, isDarwin, Ctx);
    164       break;
    165     case PPCII::MO_HA:
    166       Expr = PPCMCExpr::createHa(Expr, isDarwin, Ctx);
    167       break;
    168   }
    169 
    170   return MCOperand::createExpr(Expr);
    171 }
    172 
    173 void llvm::LowerPPCMachineInstrToMCInst(const MachineInstr *MI, MCInst &OutMI,
    174                                         AsmPrinter &AP, bool isDarwin) {
    175   OutMI.setOpcode(MI->getOpcode());
    176 
    177   for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
    178     const MachineOperand &MO = MI->getOperand(i);
    179 
    180     MCOperand MCOp;
    181     switch (MO.getType()) {
    182     default:
    183       MI->dump();
    184       llvm_unreachable("unknown operand type");
    185     case MachineOperand::MO_Register:
    186       assert(!MO.getSubReg() && "Subregs should be eliminated!");
    187       assert(MO.getReg() > PPC::NoRegister &&
    188              MO.getReg() < PPC::NUM_TARGET_REGS &&
    189              "Invalid register for this target!");
    190       MCOp = MCOperand::createReg(MO.getReg());
    191       break;
    192     case MachineOperand::MO_Immediate:
    193       MCOp = MCOperand::createImm(MO.getImm());
    194       break;
    195     case MachineOperand::MO_MachineBasicBlock:
    196       MCOp = MCOperand::createExpr(MCSymbolRefExpr::create(
    197                                       MO.getMBB()->getSymbol(), AP.OutContext));
    198       break;
    199     case MachineOperand::MO_GlobalAddress:
    200     case MachineOperand::MO_ExternalSymbol:
    201       MCOp = GetSymbolRef(MO, GetSymbolFromOperand(MO, AP), AP, isDarwin);
    202       break;
    203     case MachineOperand::MO_JumpTableIndex:
    204       MCOp = GetSymbolRef(MO, AP.GetJTISymbol(MO.getIndex()), AP, isDarwin);
    205       break;
    206     case MachineOperand::MO_ConstantPoolIndex:
    207       MCOp = GetSymbolRef(MO, AP.GetCPISymbol(MO.getIndex()), AP, isDarwin);
    208       break;
    209     case MachineOperand::MO_BlockAddress:
    210       MCOp = GetSymbolRef(MO,AP.GetBlockAddressSymbol(MO.getBlockAddress()),AP,
    211                           isDarwin);
    212       break;
    213     case MachineOperand::MO_RegisterMask:
    214       continue;
    215     }
    216 
    217     OutMI.addOperand(MCOp);
    218   }
    219 }
    220