gem5/arch/mips/isa/formats/noop.isa

////////////////////////////////////////////////////////////////////
//
// Noop instruction
//

output header {{
        /**
         * Base class for integer operations.
         */
        class Noop : public MipsStaticInst
        {
                protected:

                /// Constructor
                Noop(const char *mnem, MachInst _machInst, OpClass __opClass) : MipsStaticInst(mnem, _machInst, __opClass)
                {
                }

                std::string generateDisassembly(Addr pc, const SymbolTable *symtab) const;
        };
}};

output decoder {{
        std::string Noop::generateDisassembly(Addr pc, const SymbolTable *symtab) const
        {
                return "Disassembly of integer instruction\n";
        }
}};

def template NoopExecute {{
        Fault %(class_name)s::execute(%(CPU_exec_context)s *xc, Trace::InstRecord *traceData) const
        {
                //Nothing to see here, move along
                return No_Fault;
        }
}};

// Primary format for integer operate instructions:
def format Noop(code, *opt_flags) {{
        orig_code = code
        cblk = CodeBlock(code)
        iop = InstObjParams(name, Name, 'MipsStaticInst', cblk, opt_flags)
        header_output = BasicDeclare.subst(iop)
        decoder_output = BasicConstructor.subst(iop)
        decode_block = BasicDecodeWithMnemonic.subst(iop)
        exec_output = NoopExecute.subst(iop)
}};

////////////////////////////////////////////////////////////////////
//
// Nop
//

output header {{
    /**
     * Static instruction class for no-ops.  This is a leaf class.
     */
    class Nop : public AlphaStaticInst
    {
        /// Disassembly of original instruction.
        const std::string originalDisassembly;

      public:
        /// Constructor
        Nop(const std::string _originalDisassembly, MachInst _machInst)
            : AlphaStaticInst("nop", _machInst, No_OpClass),
              originalDisassembly(_originalDisassembly)
        {
            flags[IsNop] = true;
        }

        ~Nop() { }

        std::string
        generateDisassembly(Addr pc, const SymbolTable *symtab) const;

        %(BasicExecDeclare)s
    };
}};

output decoder {{
    std::string Nop::generateDisassembly(Addr pc,
                                         const SymbolTable *symtab) const
    {
#ifdef SS_COMPATIBLE_DISASSEMBLY
        return originalDisassembly;
#else
        return csprintf("%-10s (%s)", "nop", originalDisassembly);
#endif
    }

    /// Helper function for decoding nops.  Substitute Nop object
    /// for original inst passed in as arg (and delete latter).
    inline
    AlphaStaticInst *
    makeNop(AlphaStaticInst *inst)
    {
        AlphaStaticInst *nop = new Nop(inst->disassemble(0), inst->machInst);
        delete inst;
        return nop;
    }
}};

output exec {{
    Fault
    Nop::execute(%(CPU_exec_context)s *, Trace::InstRecord *) const
    {
        return No_Fault;
    }
}};

// integer & FP operate instructions use Rc as dest, so check for
// Rc == 31 to detect nops
def template OperateNopCheckDecode {{
 {
     AlphaStaticInst *i = new %(class_name)s(machInst);
     if (RC == 31) {
         i = makeNop(i);
     }
     return i;
 }
}};


// Like BasicOperate format, but generates NOP if RC/FC == 31
def format BasicOperateWithNopCheck(code, *opt_args) {{
    iop = InstObjParams(name, Name, 'AlphaStaticInst', CodeBlock(code),
                        opt_args)
    header_output = BasicDeclare.subst(iop)
    decoder_output = BasicConstructor.subst(iop)
    decode_block = OperateNopCheckDecode.subst(iop)
    exec_output = BasicExecute.subst(iop)
}};