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      1 //===-- ARMAsmBackend.h - ARM Assembler Backend -----------------*- C++ -*-===//
      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 #ifndef LLVM_LIB_TARGET_ARM_ARMASMBACKEND_H
     11 #define LLVM_LIB_TARGET_ARM_ARMASMBACKEND_H
     12 
     13 #include "MCTargetDesc/ARMFixupKinds.h"
     14 #include "llvm/MC/MCAsmBackend.h"
     15 #include "llvm/MC/MCSubtargetInfo.h"
     16 
     17 using namespace llvm;
     18 
     19 namespace {
     20 
     21 class ARMAsmBackend : public MCAsmBackend {
     22   const MCSubtargetInfo *STI;
     23   bool isThumbMode;    // Currently emitting Thumb code.
     24   bool IsLittleEndian; // Big or little endian.
     25 public:
     26   ARMAsmBackend(const Target &T, const Triple &TT, bool IsLittle)
     27       : MCAsmBackend(), STI(ARM_MC::createARMMCSubtargetInfo(TT, "", "")),
     28         isThumbMode(TT.getArchName().startswith("thumb")),
     29         IsLittleEndian(IsLittle) {}
     30 
     31   ~ARMAsmBackend() override { delete STI; }
     32 
     33   unsigned getNumFixupKinds() const override {
     34     return ARM::NumTargetFixupKinds;
     35   }
     36 
     37   bool hasNOP() const { return STI->getFeatureBits()[ARM::HasV6T2Ops]; }
     38 
     39   const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override;
     40 
     41   /// processFixupValue - Target hook to process the literal value of a fixup
     42   /// if necessary.
     43   void processFixupValue(const MCAssembler &Asm, const MCAsmLayout &Layout,
     44                          const MCFixup &Fixup, const MCFragment *DF,
     45                          const MCValue &Target, uint64_t &Value,
     46                          bool &IsResolved) override;
     47 
     48   unsigned adjustFixupValue(const MCFixup &Fixup, uint64_t Value, bool IsPCRel,
     49                             MCContext *Ctx, bool IsLittleEndian,
     50                             bool IsResolved) const;
     51 
     52   void applyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize,
     53                   uint64_t Value, bool IsPCRel) const override;
     54 
     55   unsigned getRelaxedOpcode(unsigned Op) const;
     56 
     57   bool mayNeedRelaxation(const MCInst &Inst) const override;
     58 
     59   const char *reasonForFixupRelaxation(const MCFixup &Fixup,
     60                                        uint64_t Value) const;
     61 
     62   bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value,
     63                             const MCRelaxableFragment *DF,
     64                             const MCAsmLayout &Layout) const override;
     65 
     66   void relaxInstruction(const MCInst &Inst, MCInst &Res) const override;
     67 
     68   bool writeNopData(uint64_t Count, MCObjectWriter *OW) const override;
     69 
     70   void handleAssemblerFlag(MCAssemblerFlag Flag) override;
     71 
     72   unsigned getPointerSize() const { return 4; }
     73   bool isThumb() const { return isThumbMode; }
     74   void setIsThumb(bool it) { isThumbMode = it; }
     75   bool isLittle() const { return IsLittleEndian; }
     76 };
     77 } // end anonymous namespace
     78 
     79 #endif
     80