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      1 //===-- ARMMCInstLower.cpp - Convert ARM 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 ARM MachineInstrs to their corresponding
     11 // MCInst records.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #include "ARM.h"
     16 #include "ARMAsmPrinter.h"
     17 #include "MCTargetDesc/ARMMCExpr.h"
     18 #include "llvm/Constants.h"
     19 #include "llvm/CodeGen/MachineBasicBlock.h"
     20 #include "llvm/MC/MCExpr.h"
     21 #include "llvm/MC/MCInst.h"
     22 #include "llvm/Target/Mangler.h"
     23 using namespace llvm;
     24 
     25 
     26 MCOperand ARMAsmPrinter::GetSymbolRef(const MachineOperand &MO,
     27                                       const MCSymbol *Symbol) {
     28   const MCExpr *Expr;
     29   switch (MO.getTargetFlags()) {
     30   default: {
     31     Expr = MCSymbolRefExpr::Create(Symbol, MCSymbolRefExpr::VK_None,
     32                                    OutContext);
     33     switch (MO.getTargetFlags()) {
     34     default:
     35       assert(0 && "Unknown target flag on symbol operand");
     36     case 0:
     37       break;
     38     case ARMII::MO_LO16:
     39       Expr = MCSymbolRefExpr::Create(Symbol, MCSymbolRefExpr::VK_None,
     40                                      OutContext);
     41       Expr = ARMMCExpr::CreateLower16(Expr, OutContext);
     42       break;
     43     case ARMII::MO_HI16:
     44       Expr = MCSymbolRefExpr::Create(Symbol, MCSymbolRefExpr::VK_None,
     45                                      OutContext);
     46       Expr = ARMMCExpr::CreateUpper16(Expr, OutContext);
     47       break;
     48     }
     49     break;
     50   }
     51 
     52   case ARMII::MO_PLT:
     53     Expr = MCSymbolRefExpr::Create(Symbol, MCSymbolRefExpr::VK_ARM_PLT,
     54                                    OutContext);
     55     break;
     56   }
     57 
     58   if (!MO.isJTI() && MO.getOffset())
     59     Expr = MCBinaryExpr::CreateAdd(Expr,
     60                                    MCConstantExpr::Create(MO.getOffset(),
     61                                                           OutContext),
     62                                    OutContext);
     63   return MCOperand::CreateExpr(Expr);
     64 
     65 }
     66 
     67 bool ARMAsmPrinter::lowerOperand(const MachineOperand &MO,
     68                                  MCOperand &MCOp) {
     69   switch (MO.getType()) {
     70   default:
     71     assert(0 && "unknown operand type");
     72     return false;
     73   case MachineOperand::MO_Register:
     74     // Ignore all non-CPSR implicit register operands.
     75     if (MO.isImplicit() && MO.getReg() != ARM::CPSR)
     76       return false;
     77     assert(!MO.getSubReg() && "Subregs should be eliminated!");
     78     MCOp = MCOperand::CreateReg(MO.getReg());
     79     break;
     80   case MachineOperand::MO_Immediate:
     81     MCOp = MCOperand::CreateImm(MO.getImm());
     82     break;
     83   case MachineOperand::MO_MachineBasicBlock:
     84     MCOp = MCOperand::CreateExpr(MCSymbolRefExpr::Create(
     85         MO.getMBB()->getSymbol(), OutContext));
     86     break;
     87   case MachineOperand::MO_GlobalAddress:
     88     MCOp = GetSymbolRef(MO, Mang->getSymbol(MO.getGlobal()));
     89     break;
     90   case MachineOperand::MO_ExternalSymbol:
     91    MCOp = GetSymbolRef(MO,
     92                         GetExternalSymbolSymbol(MO.getSymbolName()));
     93     break;
     94   case MachineOperand::MO_JumpTableIndex:
     95     MCOp = GetSymbolRef(MO, GetJTISymbol(MO.getIndex()));
     96     break;
     97   case MachineOperand::MO_ConstantPoolIndex:
     98     MCOp = GetSymbolRef(MO, GetCPISymbol(MO.getIndex()));
     99     break;
    100   case MachineOperand::MO_BlockAddress:
    101     MCOp = GetSymbolRef(MO, GetBlockAddressSymbol(MO.getBlockAddress()));
    102     break;
    103   case MachineOperand::MO_FPImmediate: {
    104     APFloat Val = MO.getFPImm()->getValueAPF();
    105     bool ignored;
    106     Val.convert(APFloat::IEEEdouble, APFloat::rmTowardZero, &ignored);
    107     MCOp = MCOperand::CreateFPImm(Val.convertToDouble());
    108     break;
    109   }
    110   }
    111   return true;
    112 }
    113 
    114 void llvm::LowerARMMachineInstrToMCInst(const MachineInstr *MI, MCInst &OutMI,
    115                                         ARMAsmPrinter &AP) {
    116   OutMI.setOpcode(MI->getOpcode());
    117 
    118   for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
    119     const MachineOperand &MO = MI->getOperand(i);
    120 
    121     MCOperand MCOp;
    122     if (AP.lowerOperand(MO, MCOp))
    123       OutMI.addOperand(MCOp);
    124   }
    125 }
    126