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