examples/non-const-visitor.h

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#ifndef VIXL_EXAMPLES_NON_CONST_VISITOR_H_
#define VIXL_EXAMPLES_NON_CONST_VISITOR_H_

using namespace vixl;

class SwitchAddSubRegisterSources : public DecoderVisitor {
 public:
  SwitchAddSubRegisterSources()
      : DecoderVisitor(DecoderVisitor::kNonConstVisitor) {}

  // Our visitor switches the register sources for some add and sub instructions
  // (not all add and sub instructions). Visitors are listed by the macro
  // `VISITOR_LIST` in a64/decoder-a64.h.
  virtual void VisitAddSubShifted(const Instruction* instr) {
    int rn = instr->Rn();
    int rm = instr->Rm();
    // Only non-const visitors are allowed to discard constness of the visited
    // instruction.
    Instruction* mutable_instr = MutableInstruction(instr);
    Instr instr_bits = mutable_instr->InstructionBits();

    // Switch the bitfields for the `rn` and `rm` registers.
    instr_bits &= ~(Rn_mask | Rm_mask);
    instr_bits |= (rn << Rm_offset) | (rm << Rn_offset);

    // Rewrite the instruction.
    mutable_instr->SetInstructionBits(instr_bits);
  }

  // Define the remaining visitors to do nothing.
#define UNUSED_VISITOR_LIST(V)      \
  V(PCRelAddressing)                \
  V(AddSubImmediate)                \
  V(LogicalImmediate)               \
  V(MoveWideImmediate)              \
  V(Bitfield)                       \
  V(Extract)                        \
  V(UnconditionalBranch)            \
  V(UnconditionalBranchToRegister)  \
  V(CompareBranch)                  \
  V(TestBranch)                     \
  V(ConditionalBranch)              \
  V(System)                         \
  V(Exception)                      \
  V(LoadStorePairPostIndex)         \
  V(LoadStorePairOffset)            \
  V(LoadStorePairPreIndex)          \
  V(LoadStorePairNonTemporal)       \
  V(LoadLiteral)                    \
  V(LoadStoreUnscaledOffset)        \
  V(LoadStorePostIndex)             \
  V(LoadStorePreIndex)              \
  V(LoadStoreRegisterOffset)        \
  V(LoadStoreUnsignedOffset)        \
  V(LoadStoreExclusive)             \
  V(LogicalShifted)                 \
  V(AddSubExtended)                 \
  V(AddSubWithCarry)                \
  V(ConditionalCompareRegister)     \
  V(ConditionalCompareImmediate)    \
  V(ConditionalSelect)              \
  V(DataProcessing1Source)          \
  V(DataProcessing2Source)          \
  V(DataProcessing3Source)          \
  V(FPCompare)                      \
  V(FPConditionalCompare)           \
  V(FPConditionalSelect)            \
  V(FPImmediate)                    \
  V(FPDataProcessing1Source)        \
  V(FPDataProcessing2Source)        \
  V(FPDataProcessing3Source)        \
  V(FPIntegerConvert)               \
  V(FPFixedPointConvert)            \
  V(Unallocated)                    \
  V(Unimplemented)
#define DEFINE_UNUSED_VISITOR(Name)                                  \
  virtual void Visit##Name(const Instruction* i) {                   \
    USE(i); /* Prevents compiler warnings about unused variables. */ \
  }
  UNUSED_VISITOR_LIST(DEFINE_UNUSED_VISITOR)
#undef DEFINE_UNUSED_VISITOR
#undef UNUSED_VISITOR_LIST
};


void GenerateNonConstVisitorTestCode(MacroAssembler* masm);

int64_t RunNonConstVisitorTestGeneratedCode(const Instruction* start_instr);

void ModifyNonConstVisitorTestGeneratedCode(Instruction* start,
                                            Instruction* end);


#endif