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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/GlobalValue.h"
     23 #include "llvm/MC/MCAsmInfo.h"
     24 #include "llvm/MC/MCExpr.h"
     25 #include "llvm/MC/MCInst.h"
     26 #include "llvm/Target/Mangler.h"
     27 using namespace llvm;
     28 
     29 static MachineModuleInfoMachO &getMachOMMI(AsmPrinter &AP) {
     30   return AP.MMI->getObjFileInfo<MachineModuleInfoMachO>();
     31 }
     32 
     33 
     34 static MCSymbol *GetSymbolFromOperand(const MachineOperand &MO, AsmPrinter &AP){
     35   MCContext &Ctx = AP.OutContext;
     36 
     37   SmallString<128> Name;
     38   if (!MO.isGlobal()) {
     39     assert(MO.isSymbol() && "Isn't a symbol reference");
     40     Name += AP.MAI->getGlobalPrefix();
     41     Name += MO.getSymbolName();
     42   } else {
     43     const GlobalValue *GV = MO.getGlobal();
     44     bool isImplicitlyPrivate = false;
     45     if (MO.getTargetFlags() == PPCII::MO_DARWIN_STUB ||
     46         (MO.getTargetFlags() & PPCII::MO_NLP_FLAG))
     47       isImplicitlyPrivate = true;
     48 
     49     AP.Mang->getNameWithPrefix(Name, GV, isImplicitlyPrivate);
     50   }
     51 
     52   // If the target flags on the operand changes the name of the symbol, do that
     53   // before we return the symbol.
     54   if (MO.getTargetFlags() == PPCII::MO_DARWIN_STUB) {
     55     Name += "$stub";
     56     const char *PGP = AP.MAI->getPrivateGlobalPrefix();
     57     const char *Prefix = "";
     58     if (!Name.startswith(PGP)) {
     59       // http://llvm.org/bugs/show_bug.cgi?id=15763
     60       // all stubs and lazy_ptrs should be local symbols, which need leading 'L'
     61       Prefix = PGP;
     62     }
     63     MCSymbol *Sym = Ctx.GetOrCreateSymbol(Twine(Prefix) + Twine(Name));
     64     MachineModuleInfoImpl::StubValueTy &StubSym =
     65       getMachOMMI(AP).getFnStubEntry(Sym);
     66     if (StubSym.getPointer())
     67       return Sym;
     68 
     69     if (MO.isGlobal()) {
     70       StubSym =
     71       MachineModuleInfoImpl::
     72       StubValueTy(AP.Mang->getSymbol(MO.getGlobal()),
     73                   !MO.getGlobal()->hasInternalLinkage());
     74     } else {
     75       Name.erase(Name.end()-5, Name.end());
     76       StubSym =
     77       MachineModuleInfoImpl::
     78       StubValueTy(Ctx.GetOrCreateSymbol(Name.str()), false);
     79     }
     80     return Sym;
     81   }
     82 
     83   // If the symbol reference is actually to a non_lazy_ptr, not to the symbol,
     84   // then add the suffix.
     85   if (MO.getTargetFlags() & PPCII::MO_NLP_FLAG) {
     86     Name += "$non_lazy_ptr";
     87     MCSymbol *Sym = Ctx.GetOrCreateSymbol(Name.str());
     88 
     89     MachineModuleInfoMachO &MachO = getMachOMMI(AP);
     90 
     91     MachineModuleInfoImpl::StubValueTy &StubSym =
     92       (MO.getTargetFlags() & PPCII::MO_NLP_HIDDEN_FLAG) ?
     93          MachO.getHiddenGVStubEntry(Sym) : MachO.getGVStubEntry(Sym);
     94 
     95     if (StubSym.getPointer() == 0) {
     96       assert(MO.isGlobal() && "Extern symbol not handled yet");
     97       StubSym = MachineModuleInfoImpl::
     98                    StubValueTy(AP.Mang->getSymbol(MO.getGlobal()),
     99                                !MO.getGlobal()->hasInternalLinkage());
    100     }
    101     return Sym;
    102   }
    103 
    104   return Ctx.GetOrCreateSymbol(Name.str());
    105 }
    106 
    107 static MCOperand GetSymbolRef(const MachineOperand &MO, const MCSymbol *Symbol,
    108                               AsmPrinter &Printer, bool isDarwin) {
    109   MCContext &Ctx = Printer.OutContext;
    110   MCSymbolRefExpr::VariantKind RefKind = MCSymbolRefExpr::VK_None;
    111 
    112   unsigned access = MO.getTargetFlags() & PPCII::MO_ACCESS_MASK;
    113 
    114   switch (access) {
    115     case PPCII::MO_TPREL_LO:
    116       RefKind = MCSymbolRefExpr::VK_PPC_TPREL_LO;
    117       break;
    118     case PPCII::MO_TPREL_HA:
    119       RefKind = MCSymbolRefExpr::VK_PPC_TPREL_HA;
    120       break;
    121     case PPCII::MO_DTPREL_LO:
    122       RefKind = MCSymbolRefExpr::VK_PPC_DTPREL_LO;
    123       break;
    124     case PPCII::MO_TLSLD_LO:
    125       RefKind = MCSymbolRefExpr::VK_PPC_GOT_TLSLD_LO;
    126       break;
    127     case PPCII::MO_TOC_LO:
    128       RefKind = MCSymbolRefExpr::VK_PPC_TOC_LO;
    129       break;
    130     case PPCII::MO_TLS:
    131       RefKind = MCSymbolRefExpr::VK_PPC_TLS;
    132       break;
    133   }
    134 
    135   const MCExpr *Expr = MCSymbolRefExpr::Create(Symbol, RefKind, Ctx);
    136 
    137   if (!MO.isJTI() && MO.getOffset())
    138     Expr = MCBinaryExpr::CreateAdd(Expr,
    139                                    MCConstantExpr::Create(MO.getOffset(), Ctx),
    140                                    Ctx);
    141 
    142   // Subtract off the PIC base if required.
    143   if (MO.getTargetFlags() & PPCII::MO_PIC_FLAG) {
    144     const MachineFunction *MF = MO.getParent()->getParent()->getParent();
    145 
    146     const MCExpr *PB = MCSymbolRefExpr::Create(MF->getPICBaseSymbol(), Ctx);
    147     Expr = MCBinaryExpr::CreateSub(Expr, PB, Ctx);
    148   }
    149 
    150   // Add ha16() / lo16() markers if required.
    151   switch (access) {
    152     case PPCII::MO_LO:
    153       Expr = PPCMCExpr::CreateLo(Expr, isDarwin, Ctx);
    154       break;
    155     case PPCII::MO_HA:
    156       Expr = PPCMCExpr::CreateHa(Expr, isDarwin, Ctx);
    157       break;
    158   }
    159 
    160   return MCOperand::CreateExpr(Expr);
    161 }
    162 
    163 void llvm::LowerPPCMachineInstrToMCInst(const MachineInstr *MI, MCInst &OutMI,
    164                                         AsmPrinter &AP, bool isDarwin) {
    165   OutMI.setOpcode(MI->getOpcode());
    166 
    167   for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
    168     const MachineOperand &MO = MI->getOperand(i);
    169 
    170     MCOperand MCOp;
    171     switch (MO.getType()) {
    172     default:
    173       MI->dump();
    174       llvm_unreachable("unknown operand type");
    175     case MachineOperand::MO_Register:
    176       assert(!MO.getSubReg() && "Subregs should be eliminated!");
    177       MCOp = MCOperand::CreateReg(MO.getReg());
    178       break;
    179     case MachineOperand::MO_Immediate:
    180       MCOp = MCOperand::CreateImm(MO.getImm());
    181       break;
    182     case MachineOperand::MO_MachineBasicBlock:
    183       MCOp = MCOperand::CreateExpr(MCSymbolRefExpr::Create(
    184                                       MO.getMBB()->getSymbol(), AP.OutContext));
    185       break;
    186     case MachineOperand::MO_GlobalAddress:
    187     case MachineOperand::MO_ExternalSymbol:
    188       MCOp = GetSymbolRef(MO, GetSymbolFromOperand(MO, AP), AP, isDarwin);
    189       break;
    190     case MachineOperand::MO_JumpTableIndex:
    191       MCOp = GetSymbolRef(MO, AP.GetJTISymbol(MO.getIndex()), AP, isDarwin);
    192       break;
    193     case MachineOperand::MO_ConstantPoolIndex:
    194       MCOp = GetSymbolRef(MO, AP.GetCPISymbol(MO.getIndex()), AP, isDarwin);
    195       break;
    196     case MachineOperand::MO_BlockAddress:
    197       MCOp = GetSymbolRef(MO,AP.GetBlockAddressSymbol(MO.getBlockAddress()),AP,
    198                           isDarwin);
    199       break;
    200     case MachineOperand::MO_RegisterMask:
    201       continue;
    202     }
    203 
    204     OutMI.addOperand(MCOp);
    205   }
    206 }
    207