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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 "llvm/ADT/SmallString.h"
     17 #include "llvm/CodeGen/AsmPrinter.h"
     18 #include "llvm/CodeGen/MachineFunction.h"
     19 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
     20 #include "llvm/IR/GlobalValue.h"
     21 #include "llvm/MC/MCAsmInfo.h"
     22 #include "llvm/MC/MCExpr.h"
     23 #include "llvm/MC/MCInst.h"
     24 #include "llvm/Target/Mangler.h"
     25 using namespace llvm;
     26 
     27 static MachineModuleInfoMachO &getMachOMMI(AsmPrinter &AP) {
     28   return AP.MMI->getObjFileInfo<MachineModuleInfoMachO>();
     29 }
     30 
     31 
     32 static MCSymbol *GetSymbolFromOperand(const MachineOperand &MO, AsmPrinter &AP){
     33   MCContext &Ctx = AP.OutContext;
     34 
     35   SmallString<128> Name;
     36   if (!MO.isGlobal()) {
     37     assert(MO.isSymbol() && "Isn't a symbol reference");
     38     Name += AP.MAI->getGlobalPrefix();
     39     Name += MO.getSymbolName();
     40   } else {
     41     const GlobalValue *GV = MO.getGlobal();
     42     bool isImplicitlyPrivate = false;
     43     if (MO.getTargetFlags() == PPCII::MO_DARWIN_STUB ||
     44         (MO.getTargetFlags() & PPCII::MO_NLP_FLAG))
     45       isImplicitlyPrivate = true;
     46 
     47     AP.Mang->getNameWithPrefix(Name, GV, isImplicitlyPrivate);
     48   }
     49 
     50   // If the target flags on the operand changes the name of the symbol, do that
     51   // before we return the symbol.
     52   if (MO.getTargetFlags() == PPCII::MO_DARWIN_STUB) {
     53     Name += "$stub";
     54     MCSymbol *Sym = Ctx.GetOrCreateSymbol(Name.str());
     55     MachineModuleInfoImpl::StubValueTy &StubSym =
     56       getMachOMMI(AP).getFnStubEntry(Sym);
     57     if (StubSym.getPointer())
     58       return Sym;
     59 
     60     if (MO.isGlobal()) {
     61       StubSym =
     62       MachineModuleInfoImpl::
     63       StubValueTy(AP.Mang->getSymbol(MO.getGlobal()),
     64                   !MO.getGlobal()->hasInternalLinkage());
     65     } else {
     66       Name.erase(Name.end()-5, Name.end());
     67       StubSym =
     68       MachineModuleInfoImpl::
     69       StubValueTy(Ctx.GetOrCreateSymbol(Name.str()), false);
     70     }
     71     return Sym;
     72   }
     73 
     74   // If the symbol reference is actually to a non_lazy_ptr, not to the symbol,
     75   // then add the suffix.
     76   if (MO.getTargetFlags() & PPCII::MO_NLP_FLAG) {
     77     Name += "$non_lazy_ptr";
     78     MCSymbol *Sym = Ctx.GetOrCreateSymbol(Name.str());
     79 
     80     MachineModuleInfoMachO &MachO = getMachOMMI(AP);
     81 
     82     MachineModuleInfoImpl::StubValueTy &StubSym =
     83       (MO.getTargetFlags() & PPCII::MO_NLP_HIDDEN_FLAG) ?
     84          MachO.getHiddenGVStubEntry(Sym) : MachO.getGVStubEntry(Sym);
     85 
     86     if (StubSym.getPointer() == 0) {
     87       assert(MO.isGlobal() && "Extern symbol not handled yet");
     88       StubSym = MachineModuleInfoImpl::
     89                    StubValueTy(AP.Mang->getSymbol(MO.getGlobal()),
     90                                !MO.getGlobal()->hasInternalLinkage());
     91     }
     92     return Sym;
     93   }
     94 
     95   return Ctx.GetOrCreateSymbol(Name.str());
     96 }
     97 
     98 static MCOperand GetSymbolRef(const MachineOperand &MO, const MCSymbol *Symbol,
     99                               AsmPrinter &Printer, bool isDarwin) {
    100   MCContext &Ctx = Printer.OutContext;
    101   MCSymbolRefExpr::VariantKind RefKind = MCSymbolRefExpr::VK_None;
    102 
    103   unsigned access = MO.getTargetFlags() & PPCII::MO_ACCESS_MASK;
    104 
    105   switch (access) {
    106     case PPCII::MO_HA16: RefKind = isDarwin ?
    107                            MCSymbolRefExpr::VK_PPC_DARWIN_HA16 :
    108                            MCSymbolRefExpr::VK_PPC_GAS_HA16;
    109                          break;
    110     case PPCII::MO_LO16: RefKind = isDarwin ?
    111                            MCSymbolRefExpr::VK_PPC_DARWIN_LO16 :
    112                            MCSymbolRefExpr::VK_PPC_GAS_LO16;
    113                          break;
    114     case PPCII::MO_TPREL16_HA: RefKind = MCSymbolRefExpr::VK_PPC_TPREL16_HA;
    115                                break;
    116     case PPCII::MO_TPREL16_LO: RefKind = MCSymbolRefExpr::VK_PPC_TPREL16_LO;
    117                                break;
    118     case PPCII::MO_DTPREL16_LO: RefKind = MCSymbolRefExpr::VK_PPC_DTPREL16_LO;
    119                                 break;
    120     case PPCII::MO_TLSLD16_LO: RefKind = MCSymbolRefExpr::VK_PPC_GOT_TLSLD16_LO;
    121                                break;
    122     case PPCII::MO_TOC16_LO: RefKind = MCSymbolRefExpr::VK_PPC_TOC16_LO;
    123                              break;
    124    }
    125 
    126   // FIXME: This isn't right, but we don't have a good way to express this in
    127   // the MC Level, see below.
    128   if (MO.getTargetFlags() & PPCII::MO_PIC_FLAG)
    129     RefKind = MCSymbolRefExpr::VK_None;
    130 
    131   const MCExpr *Expr = MCSymbolRefExpr::Create(Symbol, RefKind, Ctx);
    132 
    133   if (!MO.isJTI() && MO.getOffset())
    134     Expr = MCBinaryExpr::CreateAdd(Expr,
    135                                    MCConstantExpr::Create(MO.getOffset(), Ctx),
    136                                    Ctx);
    137 
    138   // Subtract off the PIC base if required.
    139   if (MO.getTargetFlags() & PPCII::MO_PIC_FLAG) {
    140     const MachineFunction *MF = MO.getParent()->getParent()->getParent();
    141 
    142     const MCExpr *PB = MCSymbolRefExpr::Create(MF->getPICBaseSymbol(), Ctx);
    143     Expr = MCBinaryExpr::CreateSub(Expr, PB, Ctx);
    144     // FIXME: We have no way to make the result be VK_PPC_LO16/VK_PPC_HA16,
    145     // since it is not a symbol!
    146   }
    147 
    148   return MCOperand::CreateExpr(Expr);
    149 }
    150 
    151 void llvm::LowerPPCMachineInstrToMCInst(const MachineInstr *MI, MCInst &OutMI,
    152                                         AsmPrinter &AP, bool isDarwin) {
    153   OutMI.setOpcode(MI->getOpcode());
    154 
    155   for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
    156     const MachineOperand &MO = MI->getOperand(i);
    157 
    158     MCOperand MCOp;
    159     switch (MO.getType()) {
    160     default:
    161       MI->dump();
    162       llvm_unreachable("unknown operand type");
    163     case MachineOperand::MO_Register:
    164       assert(!MO.getSubReg() && "Subregs should be eliminated!");
    165       MCOp = MCOperand::CreateReg(MO.getReg());
    166       break;
    167     case MachineOperand::MO_Immediate:
    168       MCOp = MCOperand::CreateImm(MO.getImm());
    169       break;
    170     case MachineOperand::MO_MachineBasicBlock:
    171       MCOp = MCOperand::CreateExpr(MCSymbolRefExpr::Create(
    172                                       MO.getMBB()->getSymbol(), AP.OutContext));
    173       break;
    174     case MachineOperand::MO_GlobalAddress:
    175     case MachineOperand::MO_ExternalSymbol:
    176       MCOp = GetSymbolRef(MO, GetSymbolFromOperand(MO, AP), AP, isDarwin);
    177       break;
    178     case MachineOperand::MO_JumpTableIndex:
    179       MCOp = GetSymbolRef(MO, AP.GetJTISymbol(MO.getIndex()), AP, isDarwin);
    180       break;
    181     case MachineOperand::MO_ConstantPoolIndex:
    182       MCOp = GetSymbolRef(MO, AP.GetCPISymbol(MO.getIndex()), AP, isDarwin);
    183       break;
    184     case MachineOperand::MO_BlockAddress:
    185       MCOp = GetSymbolRef(MO,AP.GetBlockAddressSymbol(MO.getBlockAddress()),AP,
    186                           isDarwin);
    187       break;
    188     case MachineOperand::MO_RegisterMask:
    189       continue;
    190     }
    191 
    192     OutMI.addOperand(MCOp);
    193   }
    194 }
    195