Merge changes.

[gem5.git] / arch / alpha / isa_desc

// -*- mode:c++ -*-

////////////////////////////////////////////////////////////////////
//
// Alpha ISA description file.
//
////////////////////////////////////////////////////////////////////


////////////////////////////////////////////////////////////////////
//
// Output include file directives.
//

output header {{
#include <sstream>
#include <iostream>
#include <iomanip>

#include "cpu/static_inst.hh"
#include "mem/mem_req.hh"  // some constructors use MemReq flags
}};

output decoder {{
#include "base/cprintf.hh"
#include "base/loader/symtab.hh"
#include "cpu/exec_context.hh"  // for Jump::branchTarget()

#include <math.h>
#if defined(linux)
#include <fenv.h>
#endif
}};

output exec {{
#include <math.h>
#if defined(linux)
#include <fenv.h>
#endif

#ifdef FULL_SYSTEM
#include "arch/alpha/pseudo_inst.hh"
#endif
#include "cpu/base_cpu.hh"
#include "cpu/exetrace.hh"
#include "sim/sim_exit.hh"
}};

////////////////////////////////////////////////////////////////////
//
// Namespace statement.  Everything below this line will be in the
// AlphaISAInst namespace.
//


namespace AlphaISA;

////////////////////////////////////////////////////////////////////
//
// Bitfield definitions.
//

// Universal (format-independent) fields
def bitfield OPCODE     <31:26>;
def bitfield RA         <25:21>;
def bitfield RB         <20:16>;

// Memory format
def signed bitfield MEMDISP <15: 0>; // displacement
def        bitfield MEMFUNC <15: 0>; // function code (same field, unsigned)

// Memory-format jumps
def bitfield JMPFUNC    <15:14>; // function code (disp<15:14>)
def bitfield JMPHINT    <13: 0>; // tgt Icache idx hint (disp<13:0>)

// Branch format
def signed bitfield BRDISP <20: 0>; // displacement

// Integer operate format(s>;
def bitfield INTIMM     <20:13>; // integer immediate (literal)
def bitfield IMM        <12:12>; // immediate flag
def bitfield INTFUNC    <11: 5>; // function code
def bitfield RC         < 4: 0>; // dest reg

// Floating-point operate format
def bitfield FA           <25:21>;
def bitfield FB           <20:16>;
def bitfield FP_FULLFUNC  <15: 5>; // complete function code
    def bitfield FP_TRAPMODE  <15:13>; // trapping mode
    def bitfield FP_ROUNDMODE <12:11>; // rounding mode
    def bitfield FP_TYPEFUNC  <10: 5>; // type+func: handiest for decoding
        def bitfield FP_SRCTYPE   <10: 9>; // source reg type
        def bitfield FP_SHORTFUNC < 8: 5>; // short function code
        def bitfield FP_SHORTFUNC_TOP2 <8:7>; // top 2 bits of short func code
def bitfield FC           < 4: 0>; // dest reg

// PALcode format
def bitfield PALFUNC    <25: 0>; // function code

// EV5 PAL instructions:
// HW_LD/HW_ST
def bitfield HW_LDST_PHYS  <15>; // address is physical
def bitfield HW_LDST_ALT   <14>; // use ALT_MODE IPR
def bitfield HW_LDST_WRTCK <13>; // HW_LD only: fault if no write acc
def bitfield HW_LDST_QUAD  <12>; // size: 0=32b, 1=64b
def bitfield HW_LDST_VPTE  <11>; // HW_LD only: is PTE fetch
def bitfield HW_LDST_LOCK  <10>; // HW_LD only: is load locked
def bitfield HW_LDST_COND  <10>; // HW_ST only: is store conditional
def signed bitfield HW_LDST_DISP  <9:0>; // signed displacement

// HW_REI
def bitfield HW_REI_TYP <15:14>; // type: stalling vs. non-stallingk
def bitfield HW_REI_MBZ <13: 0>; // must be zero

// HW_MTPR/MW_MFPR
def bitfield HW_IPR_IDX <15:0>;  // IPR index

// M5 instructions
def bitfield M5FUNC <7:0>;

def operand_types {{
    'sb' : ('signed int', 8),
    'ub' : ('unsigned int', 8),
    'sw' : ('signed int', 16),
    'uw' : ('unsigned int', 16),
    'sl' : ('signed int', 32),
    'ul' : ('unsigned int', 32),
    'sq' : ('signed int', 64),
    'uq' : ('unsigned int', 64),
    'sf' : ('float', 32),
    'df' : ('float', 64)
}};

def operands {{
    # Int regs default to unsigned, but code should not count on this.
    # For clarity, descriptions that depend on unsigned behavior should
    # explicitly specify '.uq'.
    'Ra': IntRegOperandTraits('uq', 'RA', 'IsInteger', 1),
    'Rb': IntRegOperandTraits('uq', 'RB', 'IsInteger', 2),
    'Rc': IntRegOperandTraits('uq', 'RC', 'IsInteger', 3),
    'Fa': FloatRegOperandTraits('df', 'FA', 'IsFloating', 1),
    'Fb': FloatRegOperandTraits('df', 'FB', 'IsFloating', 2),
    'Fc': FloatRegOperandTraits('df', 'FC', 'IsFloating', 3),
    'Mem': MemOperandTraits('uq', None,
                            ('IsMemRef', 'IsLoad', 'IsStore'), 4),
    'NPC': NPCOperandTraits('uq', None, ( None, None, 'IsControl' ), 4),
    'Runiq': ControlRegOperandTraits('uq', 'Uniq', None, 1),
    'FPCR':  ControlRegOperandTraits('uq', 'Fpcr', None, 1),
    # The next two are hacks for non-full-system call-pal emulation
    'R0':  IntRegOperandTraits('uq', '0', None, 1),
    'R16': IntRegOperandTraits('uq', '16', None, 1)
}};

////////////////////////////////////////////////////////////////////
//
// Basic instruction classes/templates/formats etc.
//

output header {{
// uncomment the following to get SimpleScalar-compatible disassembly
// (useful for diffing output traces).
// #define SS_COMPATIBLE_DISASSEMBLY

    /**
     * Base class for all Alpha static instructions.
     */
    class AlphaStaticInst : public StaticInst<AlphaISA>
    {
      protected:

        /// Make AlphaISA register dependence tags directly visible in
        /// this class and derived classes.  Maybe these should really
        /// live here and not in the AlphaISA namespace.
        enum DependenceTags {
            FP_Base_DepTag = AlphaISA::FP_Base_DepTag,
            Fpcr_DepTag = AlphaISA::Fpcr_DepTag,
            Uniq_DepTag = AlphaISA::Uniq_DepTag,
            IPR_Base_DepTag = AlphaISA::IPR_Base_DepTag
        };

        /// Constructor.
        AlphaStaticInst(const char *mnem, MachInst _machInst,
                        OpClass __opClass)
            : StaticInst<AlphaISA>(mnem, _machInst, __opClass)
        {
        }

        /// Print a register name for disassembly given the unique
        /// dependence tag number (FP or int).
        void printReg(std::ostream &os, int reg);

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

output decoder {{
    void
    AlphaStaticInst::printReg(std::ostream &os, int reg)
    {
        if (reg < FP_Base_DepTag) {
            ccprintf(os, "r%d", reg);
        }
        else {
            ccprintf(os, "f%d", reg - FP_Base_DepTag);
        }
    }

    std::string
    AlphaStaticInst::generateDisassembly(Addr pc, const SymbolTable *symtab)
    {
        std::stringstream ss;

        ccprintf(ss, "%-10s ", mnemonic);

        // just print the first two source regs... if there's
        // a third one, it's a read-modify-write dest (Rc),
        // e.g. for CMOVxx
        if (_numSrcRegs > 0) {
            printReg(ss, _srcRegIdx[0]);
        }
        if (_numSrcRegs > 1) {
            ss << ",";
            printReg(ss, _srcRegIdx[1]);
        }

        // just print the first dest... if there's a second one,
        // it's generally implicit
        if (_numDestRegs > 0) {
            if (_numSrcRegs > 0)
                ss << ",";
            printReg(ss, _destRegIdx[0]);
        }

        return ss.str();
    }
}};

// Declarations for execute() methods.
def template BasicExecDeclare {{
    Fault execute(%(CPU_exec_context)s *, Trace::InstRecord *);
}};

// Basic instruction class declaration template.
def template BasicDeclare {{
    /**
     * Static instruction class for "%(mnemonic)s".
     */
    class %(class_name)s : public %(base_class)s
    {
      public:
        /// Constructor.
        %(class_name)s(MachInst machInst);

        %(BasicExecDeclare)s
    };
}};

// Basic instruction class constructor template.
def template BasicConstructor {{
    inline %(class_name)s::%(class_name)s(MachInst machInst)
         : %(base_class)s("%(mnemonic)s", machInst, %(op_class)s)
    {
        %(constructor)s;
    }
}};

// Basic instruction class execute method template.
def template BasicExecute {{
    Fault %(class_name)s::execute(%(CPU_exec_context)s *xc,
                                  Trace::InstRecord *traceData)
    {
        Fault fault = No_Fault;

        %(fp_enable_check)s;
        %(op_decl)s;
        %(op_rd)s;
        %(code)s;

        if (fault == No_Fault) {
            %(op_wb)s;
        }

        return fault;
    }
}};

// Basic decode template.
def template BasicDecode {{
    return new %(class_name)s(machInst);
}};

// Basic decode template, passing mnemonic in as string arg to constructor.
def template BasicDecodeWithMnemonic {{
    return new %(class_name)s("%(mnemonic)s", machInst);
}};

// The most basic instruction format... used only for a few misc. insts
def format BasicOperate(code, *flags) {{
    iop = InstObjParams(name, Name, 'AlphaStaticInst', CodeBlock(code), flags)
    header_output = BasicDeclare.subst(iop)
    decoder_output = BasicConstructor.subst(iop)
    decode_block = BasicDecode.subst(iop)
    exec_output = BasicExecute.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);

        %(BasicExecDeclare)s
    };
}};

output decoder {{
    std::string Nop::generateDisassembly(Addr pc, const SymbolTable *symtab)
    {
#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 *)
    {
        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)
}};


////////////////////////////////////////////////////////////////////
//
// Integer operate instructions
//

output header {{
    /**
     * Base class for integer immediate instructions.
     */
    class IntegerImm : public AlphaStaticInst
    {
      protected:
        /// Immediate operand value (unsigned 8-bit int).
        uint8_t imm;

        /// Constructor
        IntegerImm(const char *mnem, MachInst _machInst, OpClass __opClass)
            : AlphaStaticInst(mnem, _machInst, __opClass), imm(INTIMM)
        {
        }

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

output decoder {{
    std::string
    IntegerImm::generateDisassembly(Addr pc, const SymbolTable *symtab)
    {
        std::stringstream ss;

        ccprintf(ss, "%-10s ", mnemonic);

        // just print the first source reg... if there's
        // a second one, it's a read-modify-write dest (Rc),
        // e.g. for CMOVxx
        if (_numSrcRegs > 0) {
            printReg(ss, _srcRegIdx[0]);
            ss << ",";
        }

        ss << (int)imm;
 
        if (_numDestRegs > 0) {
            ss << ",";
            printReg(ss, _destRegIdx[0]);
        }

        return ss.str();
    }
}};


def template RegOrImmDecode {{
 {
     AlphaStaticInst *i =
         (IMM) ? (AlphaStaticInst *)new %(class_name)sImm(machInst)
               : (AlphaStaticInst *)new %(class_name)s(machInst);
     if (RC == 31) {
         i = makeNop(i);
     }
     return i;
 }
}};

// Primary format for integer operate instructions:
// - Generates both reg-reg and reg-imm versions if Rb_or_imm is used.
// - Generates NOP if RC == 31.
def format IntegerOperate(code, *opt_flags) {{
    # If the code block contains 'Rb_or_imm', we define two instructions,
    # one using 'Rb' and one using 'imm', and have the decoder select
    # the right one.
    uses_imm = (code.find('Rb_or_imm') != -1)
    if uses_imm:
        orig_code = code
        # base code is reg version:
        # rewrite by substituting 'Rb' for 'Rb_or_imm'
        code = re.sub(r'Rb_or_imm', 'Rb', orig_code)
        # generate immediate version by substituting 'imm'
        # note that imm takes no extenstion, so we extend
        # the regexp to replace any extension as well
        imm_code = re.sub(r'Rb_or_imm(\.\w+)?', 'imm', orig_code)

    # generate declaration for register version
    cblk = CodeBlock(code)
    iop = InstObjParams(name, Name, 'AlphaStaticInst', cblk, opt_flags)
    header_output = BasicDeclare.subst(iop)
    decoder_output = BasicConstructor.subst(iop)
    exec_output = BasicExecute.subst(iop)

    if uses_imm:
        # append declaration for imm version
        imm_cblk = CodeBlock(imm_code)
        imm_iop = InstObjParams(name, Name + 'Imm', 'IntegerImm', imm_cblk,
                                opt_flags)
        header_output += BasicDeclare.subst(imm_iop)
        decoder_output += BasicConstructor.subst(imm_iop)
        exec_output += BasicExecute.subst(imm_iop)
        # decode checks IMM bit to pick correct version
        decode_block = RegOrImmDecode.subst(iop)
    else:
        # no imm version: just check for nop
        decode_block = OperateNopCheckDecode.subst(iop)
}};


////////////////////////////////////////////////////////////////////
//
// Floating-point instructions
//
//      Note that many FP-type instructions which do not support all the
//      various rounding & trapping modes use the simpler format
//      BasicOperateWithNopCheck.
//

output exec {{
    /// Check "FP enabled" machine status bit.  Called when executing any FP
    /// instruction in full-system mode.
    /// @retval Full-system mode: No_Fault if FP is enabled, Fen_Fault
    /// if not.  Non-full-system mode: always returns No_Fault.
#ifdef FULL_SYSTEM
    inline Fault checkFpEnableFault(%(CPU_exec_context)s *xc)
    {
        Fault fault = No_Fault; // dummy... this ipr access should not fault
        if (!EV5::ICSR_FPE(xc->readIpr(AlphaISA::IPR_ICSR, fault))) {
            fault = Fen_Fault;
        }
        return fault;
    }
#else
    inline Fault checkFpEnableFault(%(CPU_exec_context)s *xc)
    {
        return No_Fault;
    }
#endif
}};

output header {{
    /**
     * Base class for general floating-point instructions.  Includes
     * support for various Alpha rounding and trapping modes.  Only FP
     * instructions that require this support are derived from this
     * class; the rest derive directly from AlphaStaticInst.
     */
    class AlphaFP : public  AlphaStaticInst
    {
      public:
        /// Alpha FP rounding modes.
        enum RoundingMode {
            Chopped = 0,        ///< round toward zero
            Minus_Infinity = 1, ///< round toward minus infinity
            Normal = 2,         ///< round to nearest (default)
            Dynamic = 3,        ///< use FPCR setting (in instruction)
            Plus_Infinity = 3   ///< round to plus inifinity (in FPCR)
        };

        /// Alpha FP trapping modes.
        /// For instructions that produce integer results, the
        /// "Underflow Enable" modes really mean "Overflow Enable", and
        /// the assembly modifier is V rather than U.
        enum TrappingMode {
            /// default: nothing enabled
            Imprecise = 0,                 ///< no modifier
            /// underflow/overflow traps enabled, inexact disabled
            Underflow_Imprecise = 1,       ///< /U or /V
            Underflow_Precise = 5,         ///< /SU or /SV
            /// underflow/overflow and inexact traps enabled
            Underflow_Inexact_Precise = 7  ///< /SUI or /SVI
        };

      protected:
#if defined(linux)
        static const int alphaToC99RoundingMode[];
#endif

        /// Map enum RoundingMode values to disassembly suffixes.
        static const char *roundingModeSuffix[];
        /// Map enum TrappingMode values to FP disassembly suffixes.
        static const char *fpTrappingModeSuffix[];
        /// Map enum TrappingMode values to integer disassembly suffixes.
        static const char *intTrappingModeSuffix[];

        /// This instruction's rounding mode.
        RoundingMode roundingMode;
        /// This instruction's trapping mode.
        TrappingMode trappingMode;

        /// Constructor
        AlphaFP(const char *mnem, MachInst _machInst, OpClass __opClass)
            : AlphaStaticInst(mnem, _machInst, __opClass),
              roundingMode((enum RoundingMode)FP_ROUNDMODE),
              trappingMode((enum TrappingMode)FP_TRAPMODE)
        {
            if (trappingMode != Imprecise) {
                warn("precise FP traps unimplemented\n");
            }
        }

#if defined(linux)
        int getC99RoundingMode(uint64_t fpcr_val);
#endif

        // This differs from the AlphaStaticInst version only in
        // printing suffixes for non-default rounding & trapping modes.
        std::string generateDisassembly(Addr pc, const SymbolTable *symtab);
    };

}};


def template FloatingPointDecode {{
 {
     bool fast = (FP_TRAPMODE == AlphaFP::Imprecise
                  && FP_ROUNDMODE == AlphaFP::Normal);
     AlphaStaticInst *i =
         fast ? (AlphaStaticInst *)new %(class_name)sFast(machInst) :
                (AlphaStaticInst *)new %(class_name)sGeneral(machInst);

     if (FC == 31) {
         i = makeNop(i);
     }

     return i;
 }
}};

output decoder {{
#if defined(linux)
    int
    AlphaFP::getC99RoundingMode(uint64_t fpcr_val)
    {
        if (roundingMode == Dynamic) {
            return alphaToC99RoundingMode[bits(fpcr_val, 59, 58)];
        }
        else {
            return alphaToC99RoundingMode[roundingMode];
        }
    }
#endif

    std::string
    AlphaFP::generateDisassembly(Addr pc, const SymbolTable *symtab)
    {
        std::string mnem_str(mnemonic);

#ifndef SS_COMPATIBLE_DISASSEMBLY
        std::string suffix("");
        suffix += ((_destRegIdx[0] >= FP_Base_DepTag)
                   ? fpTrappingModeSuffix[trappingMode]
                   : intTrappingModeSuffix[trappingMode]);
        suffix += roundingModeSuffix[roundingMode];

        if (suffix != "") {
            mnem_str = csprintf("%s/%s", mnemonic, suffix);
        }
#endif

        std::stringstream ss;
        ccprintf(ss, "%-10s ", mnem_str.c_str());

        // just print the first two source regs... if there's
        // a third one, it's a read-modify-write dest (Rc),
        // e.g. for CMOVxx
        if (_numSrcRegs > 0) {
            printReg(ss, _srcRegIdx[0]);
        }
        if (_numSrcRegs > 1) {
            ss << ",";
            printReg(ss, _srcRegIdx[1]);
        }

        // just print the first dest... if there's a second one,
        // it's generally implicit
        if (_numDestRegs > 0) {
            if (_numSrcRegs > 0)
                ss << ",";
            printReg(ss, _destRegIdx[0]);
        }

        return ss.str();
    }

#if defined(linux)
    const int AlphaFP::alphaToC99RoundingMode[] = {
        FE_TOWARDZERO,  // Chopped
        FE_DOWNWARD,    // Minus_Infinity
        FE_TONEAREST,   // Normal
        FE_UPWARD       // Dynamic in inst, Plus_Infinity in FPCR
    };
#endif

    const char *AlphaFP::roundingModeSuffix[] = { "c", "m", "", "d" };
    // mark invalid trapping modes, but don't fail on them, because
    // you could decode anything on a misspeculated path
    const char *AlphaFP::fpTrappingModeSuffix[] =
        { "", "u", "INVTM2", "INVTM3", "INVTM4", "su", "INVTM6", "sui" };
    const char *AlphaFP::intTrappingModeSuffix[] =
        { "", "v", "INVTM2", "INVTM3", "INVTM4", "sv", "INVTM6", "svi" };
}};

// General format for floating-point operate instructions:
// - Checks trapping and rounding mode flags.  Trapping modes
//   currently unimplemented (will fail).
// - Generates NOP if FC == 31.
def format FloatingPointOperate(code, *opt_args) {{
    iop = InstObjParams(name, Name, 'AlphaFP', CodeBlock(code), opt_args)
    decode_block = FloatingPointDecode.subst(iop)

    fast_iop = InstObjParams(name, Name + 'Fast', 'AlphaFP',
                             CodeBlock(code), opt_args)
    header_output = BasicDeclare.subst(fast_iop)
    decoder_output = BasicConstructor.subst(fast_iop)
    exec_output = BasicExecute.subst(fast_iop)

    gen_code_prefix = r'''
#if defined(linux)
    fesetround(getC99RoundingMode(xc->readFpcr()));
#endif
'''
    gen_code_suffix = r'''
#if defined(linux)
    fesetround(FE_TONEAREST);
#endif
'''

    gen_iop = InstObjParams(name, Name + 'General', 'AlphaFP',
    CodeBlock(gen_code_prefix + code + gen_code_suffix), opt_args)
    header_output += BasicDeclare.subst(gen_iop)
    decoder_output += BasicConstructor.subst(gen_iop)
    exec_output += BasicExecute.subst(gen_iop)
}};


////////////////////////////////////////////////////////////////////
//
// Memory-format instructions: LoadAddress, Load, Store
//

output header {{
    /**
     * Base class for general Alpha memory-format instructions.
     */
    class Memory : public AlphaStaticInst
    {
      protected:

        /// Memory request flags.  See mem_req_base.hh.
        unsigned memAccessFlags;
        /// Pointer to EAComp object.
        const StaticInstPtr<AlphaISA> eaCompPtr;
        /// Pointer to MemAcc object.
        const StaticInstPtr<AlphaISA> memAccPtr;

        /// Constructor
        Memory(const char *mnem, MachInst _machInst, OpClass __opClass,
               StaticInstPtr<AlphaISA> _eaCompPtr = nullStaticInstPtr,
               StaticInstPtr<AlphaISA> _memAccPtr = nullStaticInstPtr)
            : AlphaStaticInst(mnem, _machInst, __opClass),
              memAccessFlags(0), eaCompPtr(_eaCompPtr), memAccPtr(_memAccPtr)
        {
        }

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

      public:

        const StaticInstPtr<AlphaISA> &eaCompInst() const { return eaCompPtr; }
        const StaticInstPtr<AlphaISA> &memAccInst() const { return memAccPtr; }
    };

    /**
     * Base class for memory-format instructions using a 32-bit
     * displacement (i.e. most of them).
     */
    class MemoryDisp32 : public Memory
    {
      protected:
        /// Displacement for EA calculation (signed).
        int32_t disp;

        /// Constructor.
        MemoryDisp32(const char *mnem, MachInst _machInst, OpClass __opClass,
                     StaticInstPtr<AlphaISA> _eaCompPtr = nullStaticInstPtr,
                     StaticInstPtr<AlphaISA> _memAccPtr = nullStaticInstPtr)
            : Memory(mnem, _machInst, __opClass, _eaCompPtr, _memAccPtr),
              disp(MEMDISP)
        {
        }
    };


    /**
     * Base class for a few miscellaneous memory-format insts
     * that don't interpret the disp field: wh64, fetch, fetch_m, ecb.
     * None of these instructions has a destination register either.
     */
    class MemoryNoDisp : public Memory
    {
      protected:
        /// Constructor
        MemoryNoDisp(const char *mnem, MachInst _machInst, OpClass __opClass,
                     StaticInstPtr<AlphaISA> _eaCompPtr,
                     StaticInstPtr<AlphaISA> _memAccPtr)
            : Memory(mnem, _machInst, __opClass, _eaCompPtr, _memAccPtr)
        {
        }

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


    /**
     * Base class for "fake" effective-address computation
     * instructions returnded by eaCompInst().
     */
    class EACompBase : public AlphaStaticInst
    {
      public:
        /// Constructor
        EACompBase(MachInst machInst)
            : AlphaStaticInst("(eacomp)", machInst, IntAluOp)
        {
        }

        %(BasicExecDeclare)s
    };

    /**
     * Base class for "fake" memory-access instructions returnded by
     * memAccInst().
     */
    class MemAccBase : public AlphaStaticInst
    {
      public:
        /// Constructor
        MemAccBase(MachInst machInst, OpClass __opClass)
            : AlphaStaticInst("(memacc)", machInst, __opClass)
        {
        }

        %(BasicExecDeclare)s
    };

}};


output decoder {{
    std::string
    Memory::generateDisassembly(Addr pc, const SymbolTable *symtab)
    {
        return csprintf("%-10s %c%d,%d(r%d)", mnemonic,
                        flags[IsFloating] ? 'f' : 'r', RA, MEMDISP, RB);
    }

    std::string
    MemoryNoDisp::generateDisassembly(Addr pc, const SymbolTable *symtab)
    {
        return csprintf("%-10s (r%d)", mnemonic, RB);
    }
}};

output exec {{
    Fault
    EACompBase::execute(%(CPU_exec_context)s *, Trace::InstRecord *)
    {
        panic("attempt to execute eacomp");
    }

    Fault
    MemAccBase::execute(%(CPU_exec_context)s *, Trace::InstRecord *)
    {
        panic("attempt to execute memacc");
    }
}};


def format LoadAddress(code) {{
    iop = InstObjParams(name, Name, 'MemoryDisp32', CodeBlock(code))
    header_output = BasicDeclare.subst(iop)
    decoder_output = BasicConstructor.subst(iop)
    decode_block = BasicDecode.subst(iop)
    exec_output = BasicExecute.subst(iop)
}};


def template LoadStoreDeclare {{
    /**
     * Static instruction class for "%(mnemonic)s".
     */
    class %(class_name)s : public %(base_class)s
    {
      protected:

        /**
         * "Fake" effective address computation class for "%(mnemonic)s".
         */
        class EAComp : public EACompBase
        {
          public:
            /// Constructor
            EAComp(MachInst machInst);
        };

        /**
         * "Fake" memory access instruction class for "%(mnemonic)s".
         */
        class MemAcc : public MemAccBase
        {
          public:
            /// Constructor
            MemAcc(MachInst machInst);
        };

      public:

        /// Constructor.
        %(class_name)s(MachInst machInst);

        %(BasicExecDeclare)s
    };
}};

def template LoadStoreConstructor {{
    inline %(class_name)s::EAComp::EAComp(MachInst machInst)
        : EACompBase(machInst)
    {
        %(ea_constructor)s;
    }

    inline %(class_name)s::MemAcc::MemAcc(MachInst machInst)
        : MemAccBase(machInst, %(op_class)s)
    {
        %(memacc_constructor)s;
    }

    inline %(class_name)s::%(class_name)s(MachInst machInst)
         : %(base_class)s("%(mnemonic)s", machInst, %(op_class)s,
                          new EAComp(machInst), new MemAcc(machInst))
    {
        %(constructor)s;
    }
}};

def template LoadStoreExecute {{
    Fault %(class_name)s::execute(%(CPU_exec_context)s *xc,
                                  Trace::InstRecord *traceData)
    {
        Addr EA;
        Fault fault = No_Fault;

        %(fp_enable_check)s;
        %(op_decl)s;
        %(op_nonmem_rd)s;
        %(ea_code)s;

        if (fault == No_Fault) {
            %(op_mem_rd)s;
            %(memacc_code)s;
        }

        if (fault == No_Fault) {
            %(op_mem_wb)s;
        }

        if (fault == No_Fault) {
            %(postacc_code)s;
        }

        if (fault == No_Fault) {
            %(op_nonmem_wb)s;
        }

        return fault;
    }
}};


def template PrefetchExecute {{
    Fault %(class_name)s::execute(%(CPU_exec_context)s *xc,
                                  Trace::InstRecord *traceData)
    {
        Addr EA;
        Fault fault = No_Fault;

        %(fp_enable_check)s;
        %(op_decl)s;
        %(op_nonmem_rd)s;
        %(ea_code)s;

        if (fault == No_Fault) {
            xc->prefetch(EA, memAccessFlags);
        }

        return No_Fault;
    }
}};

// load instructions use Ra as dest, so check for
// Ra == 31 to detect nops
def template LoadNopCheckDecode {{
 {
     AlphaStaticInst *i = new %(class_name)s(machInst);
     if (RA == 31) {
         i = makeNop(i);
     }
     return i;
 }
}};


// for some load instructions, Ra == 31 indicates a prefetch (not a nop)
def template LoadPrefetchCheckDecode {{
 {
     if (RA != 31) {
         return new %(class_name)s(machInst);
     }
     else {
         return new %(class_name)sPrefetch(machInst);
     }
 }
}};


let {{
def LoadStoreBase(name, Name, ea_code, memacc_code, postacc_code = '',
                  base_class = 'MemoryDisp32', flags = [],
                  decode_template = BasicDecode,
                  exec_template = LoadStoreExecute):
    # Segregate flags into instruction flags (handled by InstObjParams)
    # and memory access flags (handled here).

    # Would be nice to autogenerate this list, but oh well.
    valid_mem_flags = ['LOCKED', 'NO_FAULT', 'EVICT_NEXT', 'PF_EXCLUSIVE']
    inst_flags = []
    mem_flags = []
    for f in flags:
        if f in valid_mem_flags:
            mem_flags.append(f)
        else:
            inst_flags.append(f)

    ea_cblk = CodeBlock(ea_code)
    memacc_cblk = CodeBlock(memacc_code)
    postacc_cblk = CodeBlock(postacc_code)

    cblk = CodeBlock(ea_code + memacc_code + postacc_code)
    iop = InstObjParams(name, Name, base_class, cblk, inst_flags)

    iop.ea_constructor = ea_cblk.constructor
    iop.ea_code = ea_cblk.code
    iop.memacc_constructor = memacc_cblk.constructor
    iop.memacc_code = memacc_cblk.code
    iop.postacc_code = postacc_cblk.code

    mem_flags = string.join(mem_flags, '|')
    if mem_flags != '':
        iop.constructor += '\n\tmemAccessFlags = ' + mem_flags + ';'

    # (header_output, decoder_output, decode_block, exec_output)
    return (LoadStoreDeclare.subst(iop), LoadStoreConstructor.subst(iop),
            decode_template.subst(iop), exec_template.subst(iop))
}};


def format LoadOrNop(ea_code, memacc_code, *flags) {{
    (header_output, decoder_output, decode_block, exec_output) = \
        LoadStoreBase(name, Name, ea_code, memacc_code, flags = flags,
                      decode_template = LoadNopCheckDecode)
}};


// Note that the flags passed in apply only to the prefetch version
def format LoadOrPrefetch(ea_code, memacc_code, *pf_flags) {{
    # declare the load instruction object and generate the decode block
    (header_output, decoder_output, decode_block, exec_output) = \
        LoadStoreBase(name, Name, ea_code, memacc_code,
                      decode_template = LoadPrefetchCheckDecode)

    # Declare the prefetch instruction object.

    # convert flags from tuple to list to make them mutable
    pf_flags = list(pf_flags) + ['IsMemRef', 'IsLoad', 'IsDataPrefetch', 'MemReadOp', 'NO_FAULT']

    (pf_header_output, pf_decoder_output, _, pf_exec_output) = \
        LoadStoreBase(name, Name + 'Prefetch', ea_code, '',
                      flags = pf_flags, exec_template = PrefetchExecute)

    header_output += pf_header_output
    decoder_output += pf_decoder_output
    exec_output += pf_exec_output
}};


def format Store(ea_code, memacc_code, *flags) {{
    (header_output, decoder_output, decode_block, exec_output) = \
        LoadStoreBase(name, Name, ea_code, memacc_code, flags = flags)
}};


def format StoreCond(ea_code, memacc_code, postacc_code, *flags) {{
    (header_output, decoder_output, decode_block, exec_output) = \
        LoadStoreBase(name, Name, ea_code, memacc_code, postacc_code,
                      flags = flags)
}};


// Use 'MemoryNoDisp' as base: for wh64, fetch, ecb
def format MiscPrefetch(ea_code, memacc_code, *flags) {{
    (header_output, decoder_output, decode_block, exec_output) = \
        LoadStoreBase(name, Name, ea_code, memacc_code, flags = flags,
                      base_class = 'MemoryNoDisp')
}};


////////////////////////////////////////////////////////////////////
//
// Control transfer instructions
//

output header {{

    /**
     * Base class for instructions whose disassembly is not purely a
     * function of the machine instruction (i.e., it depends on the
     * PC).  This class overrides the disassemble() method to check
     * the PC and symbol table values before re-using a cached
     * disassembly string.  This is necessary for branches and jumps,
     * where the disassembly string includes the target address (which
     * may depend on the PC and/or symbol table).
     */
    class PCDependentDisassembly : public AlphaStaticInst
    {
      protected:
        /// Cached program counter from last disassembly
        Addr               cachedPC;
        /// Cached symbol table pointer from last disassembly
        const SymbolTable *cachedSymtab;

        /// Constructor
        PCDependentDisassembly(const char *mnem, MachInst _machInst,
                               OpClass __opClass)
            : AlphaStaticInst(mnem, _machInst, __opClass),
              cachedPC(0), cachedSymtab(0)
        {
        }

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

    /**
     * Base class for branches (PC-relative control transfers),
     * conditional or unconditional.
     */
    class Branch : public PCDependentDisassembly
    {
      protected:
        /// Displacement to target address (signed).
        int32_t disp;

        /// Constructor.
        Branch(const char *mnem, MachInst _machInst, OpClass __opClass)
            : PCDependentDisassembly(mnem, _machInst, __opClass),
              disp(BRDISP << 2)
        {
        }

        Addr branchTarget(Addr branchPC) const;

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

    /**
     * Base class for jumps (register-indirect control transfers).  In
     * the Alpha ISA, these are always unconditional.
     */
    class Jump : public PCDependentDisassembly
    {
      protected:

        /// Displacement to target address (signed).
        int32_t disp;

      public:
        /// Constructor
        Jump(const char *mnem, MachInst _machInst, OpClass __opClass)
            : PCDependentDisassembly(mnem, _machInst, __opClass),
              disp(BRDISP)
        {
        }

        Addr branchTarget(ExecContext *xc) const;

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

output decoder {{
    Addr
    Branch::branchTarget(Addr branchPC) const
    {
        return branchPC + 4 + disp;
    }

    Addr
    Jump::branchTarget(ExecContext *xc) const
    {
        Addr NPC = xc->readPC() + 4;
        uint64_t Rb = xc->readIntReg(_srcRegIdx[0]);
        return (Rb & ~3) | (NPC & 1);
    }

    const std::string &
    PCDependentDisassembly::disassemble(Addr pc, const SymbolTable *symtab)
    {
        if (!cachedDisassembly ||
            pc != cachedPC || symtab != cachedSymtab)
        {
            if (cachedDisassembly)
                delete cachedDisassembly;

            cachedDisassembly =
                new std::string(generateDisassembly(pc, symtab));
            cachedPC = pc;
            cachedSymtab = symtab;
        }

        return *cachedDisassembly;
    }

    std::string
    Branch::generateDisassembly(Addr pc, const SymbolTable *symtab)
    {
        std::stringstream ss;

        ccprintf(ss, "%-10s ", mnemonic);

        // There's only one register arg (RA), but it could be
        // either a source (the condition for conditional
        // branches) or a destination (the link reg for
        // unconditional branches)
        if (_numSrcRegs > 0) {
            printReg(ss, _srcRegIdx[0]);
            ss << ",";
        }
        else if (_numDestRegs > 0) {
            printReg(ss, _destRegIdx[0]);
            ss << ",";
        }

#ifdef SS_COMPATIBLE_DISASSEMBLY
        if (_numSrcRegs == 0 && _numDestRegs == 0) {
            printReg(ss, 31);
            ss << ",";
        }
#endif

        Addr target = pc + 4 + disp;

        std::string str;
        if (symtab && symtab->findSymbol(target, str))
            ss << str;
        else 
            ccprintf(ss, "0x%x", target);

        return ss.str();
    }

    std::string
    Jump::generateDisassembly(Addr pc, const SymbolTable *symtab)
    {
        std::stringstream ss;

        ccprintf(ss, "%-10s ", mnemonic);

#ifdef SS_COMPATIBLE_DISASSEMBLY
        if (_numDestRegs == 0) {
            printReg(ss, 31);
            ss << ",";
        }
#endif

        if (_numDestRegs > 0) {
            printReg(ss, _destRegIdx[0]);
            ss << ",";
        }

        ccprintf(ss, "(r%d)", RB);

        return ss.str();
    }
}};

def template JumpOrBranchDecode {{
    return (RA == 31)
        ? (StaticInst<AlphaISA> *)new %(class_name)s(machInst)
        : (StaticInst<AlphaISA> *)new %(class_name)sAndLink(machInst);
}};

def format CondBranch(code) {{
    code = 'bool cond;\n' + code + '\nif (cond) NPC = NPC + disp;\n';
    iop = InstObjParams(name, Name, 'Branch', CodeBlock(code),
                        ('IsDirectControl', 'IsCondControl'))
    header_output = BasicDeclare.subst(iop)
    decoder_output = BasicConstructor.subst(iop)
    decode_block = BasicDecode.subst(iop)
    exec_output = BasicExecute.subst(iop)
}};

let {{
def UncondCtrlBase(name, Name, base_class, npc_expr, flags):
    # Declare basic control transfer w/o link (i.e. link reg is R31)
    nolink_code = 'NPC = %s;\n' % npc_expr
    nolink_iop = InstObjParams(name, Name, base_class,
                               CodeBlock(nolink_code), flags)
    header_output = BasicDeclare.subst(nolink_iop)
    decoder_output = BasicConstructor.subst(nolink_iop)
    exec_output = BasicExecute.subst(nolink_iop)

    # Generate declaration of '*AndLink' version, append to decls
    link_code = 'Ra = NPC & ~3;\n' + nolink_code
    link_iop = InstObjParams(name, Name + 'AndLink', base_class,
                             CodeBlock(link_code), flags)
    header_output += BasicDeclare.subst(link_iop)
    decoder_output += BasicConstructor.subst(link_iop)
    exec_output += BasicExecute.subst(link_iop)

    # need to use link_iop for the decode template since it is expecting
    # the shorter version of class_name (w/o "AndLink")

    return (header_output, decoder_output,
            JumpOrBranchDecode.subst(nolink_iop), exec_output)
}};

def format UncondBranch(*flags) {{
    flags += ('IsUncondControl', 'IsDirectControl')
    (header_output, decoder_output, decode_block, exec_output) = \
        UncondCtrlBase(name, Name, 'Branch', 'NPC + disp', flags)
}};

def format Jump(*flags) {{
    flags += ('IsUncondControl', 'IsIndirectControl')
    (header_output, decoder_output, decode_block, exec_output) = \
        UncondCtrlBase(name, Name, 'Jump', '(Rb & ~3) | (NPC & 1)', flags)
}};


////////////////////////////////////////////////////////////////////
//
// PAL calls
//

output header {{
    /**
     * Base class for emulated call_pal calls (used only in
     * non-full-system mode).
     */
    class EmulatedCallPal : public AlphaStaticInst
    {
      protected:

        /// Constructor.
        EmulatedCallPal(const char *mnem, MachInst _machInst,
                        OpClass __opClass)
            : AlphaStaticInst(mnem, _machInst, __opClass)
        {
        }

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

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

def format EmulatedCallPal(code, *flags) {{
    iop = InstObjParams(name, Name, 'EmulatedCallPal', CodeBlock(code), flags)
    header_output = BasicDeclare.subst(iop)
    decoder_output = BasicConstructor.subst(iop)
    decode_block = BasicDecode.subst(iop)
    exec_output = BasicExecute.subst(iop)
}};

output header {{
    /**
     * Base class for full-system-mode call_pal instructions.
     * Probably could turn this into a leaf class and get rid of the
     * parser template.
     */
    class CallPalBase : public AlphaStaticInst
    {
      protected:
        int palFunc;    ///< Function code part of instruction
        int palOffset;  ///< Target PC, offset from IPR_PAL_BASE
        bool palValid;  ///< is the function code valid?
        bool palPriv;   ///< is this call privileged?

        /// Constructor.
        CallPalBase(const char *mnem, MachInst _machInst,
                    OpClass __opClass);

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

output decoder {{
    inline
    CallPalBase::CallPalBase(const char *mnem, MachInst _machInst,
                             OpClass __opClass)
        : AlphaStaticInst(mnem, _machInst, __opClass),
        palFunc(PALFUNC)
    {
        // From the 21164 HRM (paraphrased):
        // Bit 7 of the function code (mask 0x80) indicates
        // whether the call is privileged (bit 7 == 0) or
        // unprivileged (bit 7 == 1).  The privileged call table
        // starts at 0x2000, the unprivielged call table starts at
        // 0x3000.  Bits 5-0 (mask 0x3f) are used to calculate the
        // offset.
        const int palPrivMask = 0x80;
        const int palOffsetMask = 0x3f;

        // Pal call is invalid unless all other bits are 0
        palValid = ((machInst & ~(palPrivMask | palOffsetMask)) == 0);
        palPriv = ((machInst & palPrivMask) == 0);
        int shortPalFunc = (machInst & palOffsetMask);
        // Add 1 to base to set pal-mode bit
        palOffset = (palPriv ? 0x2001 : 0x3001) + (shortPalFunc << 6);
    }

    std::string
    CallPalBase::generateDisassembly(Addr pc, const SymbolTable *symtab)
    {
        return csprintf("%-10s %#x", "call_pal", palFunc);
    }
}};

def format CallPal(code, *flags) {{
    iop = InstObjParams(name, Name, 'CallPalBase', CodeBlock(code), flags)
    header_output = BasicDeclare.subst(iop)
    decoder_output = BasicConstructor.subst(iop)
    decode_block = BasicDecode.subst(iop)
    exec_output = BasicExecute.subst(iop)
}};

////////////////////////////////////////////////////////////////////
//
// hw_ld, hw_st
//

output header {{
    /**
     * Base class for hw_ld and hw_st.
     */
    class HwLoadStore : public Memory
    {
      protected:

        /// Displacement for EA calculation (signed).
        int16_t disp;

        /// Constructor
        HwLoadStore(const char *mnem, MachInst _machInst, OpClass __opClass,
                    StaticInstPtr<AlphaISA> _eaCompPtr,
                    StaticInstPtr<AlphaISA> _memAccPtr);

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


output decoder {{
    inline
    HwLoadStore::HwLoadStore(const char *mnem, MachInst _machInst,
                             OpClass __opClass,
                             StaticInstPtr<AlphaISA> _eaCompPtr,
                             StaticInstPtr<AlphaISA> _memAccPtr)
        : Memory(mnem, _machInst, __opClass, _eaCompPtr, _memAccPtr),
        disp(HW_LDST_DISP)
    {
        memAccessFlags = 0;
        if (HW_LDST_PHYS) memAccessFlags |= PHYSICAL;
        if (HW_LDST_ALT)  memAccessFlags |= ALTMODE;
        if (HW_LDST_VPTE) memAccessFlags |= VPTE;
        if (HW_LDST_LOCK) memAccessFlags |= LOCKED;
    }

    std::string
    HwLoadStore::generateDisassembly(Addr pc, const SymbolTable *symtab)
    {
#ifdef SS_COMPATIBLE_DISASSEMBLY
        return csprintf("%-10s r%d,%d(r%d)", mnemonic, RA, disp, RB);
#else
        // HW_LDST_LOCK and HW_LDST_COND are the same bit.
        const char *lock_str =
            (HW_LDST_LOCK) ? (flags[IsLoad] ? ",LOCK" : ",COND") : "";

        return csprintf("%-10s r%d,%d(r%d)%s%s%s%s%s",
                        mnemonic, RA, disp, RB,
                        HW_LDST_PHYS ? ",PHYS" : "",
                        HW_LDST_ALT ? ",ALT" : "",
                        HW_LDST_QUAD ? ",QUAD" : "",
                        HW_LDST_VPTE ? ",VPTE" : "",
                        lock_str);
#endif
    }
}};

def format HwLoadStore(ea_code, memacc_code, class_ext, *flags) {{
    (header_output, decoder_output, decode_block, exec_output) = \
        LoadStoreBase(name, Name + class_ext, ea_code, memacc_code,
                      flags = flags, base_class = 'HwLoadStore')
}};


def format HwStoreCond(ea_code, memacc_code, postacc_code, class_ext, *flags) {{
    (header_output, decoder_output, decode_block, exec_output) = \
        LoadStoreBase(name, Name + class_ext, ea_code, memacc_code,
                      postacc_code, flags = flags, base_class = 'HwLoadStore')
}};


output header {{
    /**
     * Base class for hw_mfpr and hw_mtpr.
     */
    class HwMoveIPR : public AlphaStaticInst
    {
      protected:
        /// Index of internal processor register.
        int ipr_index;

        /// Constructor
        HwMoveIPR(const char *mnem, MachInst _machInst, OpClass __opClass)
            : AlphaStaticInst(mnem, _machInst, __opClass),
              ipr_index(HW_IPR_IDX)
        {
        }

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

output decoder {{
    std::string
    HwMoveIPR::generateDisassembly(Addr pc, const SymbolTable *symtab)
    {
        if (_numSrcRegs > 0) {
            // must be mtpr
            return csprintf("%-10s r%d,IPR(%#x)",
                            mnemonic, RA, ipr_index);
        }
        else {
            // must be mfpr
            return csprintf("%-10s IPR(%#x),r%d",
                            mnemonic, ipr_index, RA);
        }
    }
}};

def format HwMoveIPR(code) {{
    iop = InstObjParams(name, Name, 'HwMoveIPR', CodeBlock(code))
    header_output = BasicDeclare.subst(iop)
    decoder_output = BasicConstructor.subst(iop)
    decode_block = BasicDecode.subst(iop)
    exec_output = BasicExecute.subst(iop)
}};


////////////////////////////////////////////////////////////////////
//
// Unimplemented instructions
//

output header {{
    /**
     * Static instruction class for unimplemented instructions that
     * cause simulator termination.  Note that these are recognized
     * (legal) instructions that the simulator does not support; the
     * 'Unknown' class is used for unrecognized/illegal instructions.
     * This is a leaf class.
     */
    class FailUnimplemented : public AlphaStaticInst
    {
      public:
        /// Constructor
        FailUnimplemented(const char *_mnemonic, MachInst _machInst)
            : AlphaStaticInst(_mnemonic, _machInst, No_OpClass)
        {
            // don't call execute() (which panics) if we're on a
            // speculative path
            flags[IsNonSpeculative] = true;
        }

        %(BasicExecDeclare)s

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

    /**
     * Base class for unimplemented instructions that cause a warning
     * to be printed (but do not terminate simulation).  This
     * implementation is a little screwy in that it will print a
     * warning for each instance of a particular unimplemented machine
     * instruction, not just for each unimplemented opcode.  Should
     * probably make the 'warned' flag a static member of the derived
     * class.
     */
    class WarnUnimplemented : public AlphaStaticInst
    {
      private:
        /// Have we warned on this instruction yet?
        bool warned;

      public:
        /// Constructor
        WarnUnimplemented(const char *_mnemonic, MachInst _machInst)
            : AlphaStaticInst(_mnemonic, _machInst, No_OpClass), warned(false)
        {
            // don't call execute() (which panics) if we're on a
            // speculative path
            flags[IsNonSpeculative] = true;
        }

        %(BasicExecDeclare)s

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

output decoder {{
    std::string
    FailUnimplemented::generateDisassembly(Addr pc, const SymbolTable *symtab)
    {
        return csprintf("%-10s (unimplemented)", mnemonic);
    }

    std::string
    WarnUnimplemented::generateDisassembly(Addr pc, const SymbolTable *symtab)
    {
#ifdef SS_COMPATIBLE_DISASSEMBLY
        return csprintf("%-10s", mnemonic);
#else
        return csprintf("%-10s (unimplemented)", mnemonic);
#endif
    }
}};

output exec {{
    Fault
    FailUnimplemented::execute(%(CPU_exec_context)s *xc,
                               Trace::InstRecord *traceData)
    {
        panic("attempt to execute unimplemented instruction '%s' "
              "(inst 0x%08x, opcode 0x%x)", mnemonic, machInst, OPCODE);
        return Unimplemented_Opcode_Fault;
    }

    Fault
    WarnUnimplemented::execute(%(CPU_exec_context)s *xc,
                               Trace::InstRecord *traceData)
    {
        if (!warned) {
            warn("instruction '%s' unimplemented\n", mnemonic);
            warned = true;
        }

        return No_Fault;
    }
}};


def format FailUnimpl() {{
    iop = InstObjParams(name, 'FailUnimplemented')
    decode_block = BasicDecodeWithMnemonic.subst(iop)
}};

def format WarnUnimpl() {{
    iop = InstObjParams(name, 'WarnUnimplemented')
    decode_block = BasicDecodeWithMnemonic.subst(iop)
}};

output header {{
    /**
     * Static instruction class for unknown (illegal) instructions.
     * These cause simulator termination if they are executed in a
     * non-speculative mode.  This is a leaf class.
     */
    class Unknown : public AlphaStaticInst
    {
      public:
        /// Constructor
        Unknown(MachInst _machInst)
            : AlphaStaticInst("unknown", _machInst, No_OpClass)
        {
            // don't call execute() (which panics) if we're on a
            // speculative path
            flags[IsNonSpeculative] = true;
        }

        %(BasicExecDeclare)s

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

////////////////////////////////////////////////////////////////////
//
// Unknown instructions
//

output decoder {{
    std::string
    Unknown::generateDisassembly(Addr pc, const SymbolTable *symtab)
    {
        return csprintf("%-10s (inst 0x%x, opcode 0x%x)",
                        "unknown", machInst, OPCODE);
    }
}};

output exec {{
    Fault
    Unknown::execute(%(CPU_exec_context)s *xc, Trace::InstRecord *traceData)
    {
        panic("attempt to execute unknown instruction "
              "(inst 0x%08x, opcode 0x%x)", machInst, OPCODE);
        return Unimplemented_Opcode_Fault;
    }
}};

def format Unknown() {{
    decode_block = 'return new Unknown(machInst);\n'
}};

////////////////////////////////////////////////////////////////////
//
// Utility functions for execute methods
//

output exec {{

    /// Return opa + opb, summing carry into third arg.
    inline uint64_t
    addc(uint64_t opa, uint64_t opb, int &carry)
    {
        uint64_t res = opa + opb;
        if (res < opa || res < opb)
            ++carry;
        return res;
    }

    /// Multiply two 64-bit values (opa * opb), returning the 128-bit
    /// product in res_hi and res_lo.
    inline void
    mul128(uint64_t opa, uint64_t opb, uint64_t &res_hi, uint64_t &res_lo)
    {
        // do a 64x64 --> 128 multiply using four 32x32 --> 64 multiplies
        uint64_t opa_hi = opa<63:32>;
        uint64_t opa_lo = opa<31:0>;
        uint64_t opb_hi = opb<63:32>;
        uint64_t opb_lo = opb<31:0>;

        res_lo = opa_lo * opb_lo;

        // The middle partial products logically belong in bit
        // positions 95 to 32.  Thus the lower 32 bits of each product
        // sum into the upper 32 bits of the low result, while the
        // upper 32 sum into the low 32 bits of the upper result.
        uint64_t partial1 = opa_hi * opb_lo;
        uint64_t partial2 = opa_lo * opb_hi;

        uint64_t partial1_lo = partial1<31:0> << 32;
        uint64_t partial1_hi = partial1<63:32>;
        uint64_t partial2_lo = partial2<31:0> << 32;
        uint64_t partial2_hi = partial2<63:32>;

        // Add partial1_lo and partial2_lo to res_lo, keeping track
        // of any carries out
        int carry_out = 0;
        res_lo = addc(partial1_lo, res_lo, carry_out);
        res_lo = addc(partial2_lo, res_lo, carry_out);

        // Now calculate the high 64 bits...
        res_hi = (opa_hi * opb_hi) + partial1_hi + partial2_hi + carry_out;
    }

    /// Map 8-bit S-floating exponent to 11-bit T-floating exponent.
    /// See Table 2-2 of Alpha AHB.
    inline int
    map_s(int old_exp)
    {
        int hibit = old_exp<7:>;
        int lobits = old_exp<6:0>;

        if (hibit == 1) {
            return (lobits == 0x7f) ? 0x7ff : (0x400 | lobits);
        }
        else {
            return (lobits == 0) ? 0 : (0x380 | lobits);
        }
    }

    /// Convert a 32-bit S-floating value to the equivalent 64-bit
    /// representation to be stored in an FP reg.
    inline uint64_t
    s_to_t(uint32_t s_val)
    {
        uint64_t tmp = s_val;
        return (tmp<31:> << 63 // sign bit
                | (uint64_t)map_s(tmp<30:23>) << 52 // exponent
                | tmp<22:0> << 29); // fraction
    }

    /// Convert a 64-bit T-floating value to the equivalent 32-bit
    /// S-floating representation to be stored in memory.
    inline int32_t
    t_to_s(uint64_t t_val)
    {
        return (t_val<63:62> << 30   // sign bit & hi exp bit
                | t_val<58:29>);     // rest of exp & fraction
    }
}};

////////////////////////////////////////////////////////////////////
//
// The actual decoder specification
//

decode OPCODE default Unknown::unknown() {

    format LoadAddress {
        0x08: lda({{ Ra = Rb + disp; }});
        0x09: ldah({{ Ra = Rb + (disp << 16); }});
    }

    format LoadOrNop {
        0x0a: ldbu({{ EA = Rb + disp; }}, {{ Ra.uq = Mem.ub; }});
        0x0c: ldwu({{ EA = Rb + disp; }}, {{ Ra.uq = Mem.uw; }});
        0x0b: ldq_u({{ EA = (Rb + disp) & ~7; }}, {{ Ra = Mem.uq; }});
        0x23: ldt({{ EA = Rb + disp; }}, {{ Fa = Mem.df; }});
        0x2a: ldl_l({{ EA = Rb + disp; }}, {{ Ra.sl = Mem.sl; }}, LOCKED);
        0x2b: ldq_l({{ EA = Rb + disp; }}, {{ Ra.uq = Mem.uq; }}, LOCKED);
        0x20: copy_load({{EA = Ra;}}, 
                        {{fault = xc->copySrcTranslate(EA);}},
                        IsMemRef, IsLoad, IsCopy);
    }

    format LoadOrPrefetch {
        0x28: ldl({{ EA = Rb + disp; }}, {{ Ra.sl = Mem.sl; }});
        0x29: ldq({{ EA = Rb + disp; }}, {{ Ra.uq = Mem.uq; }}, EVICT_NEXT);
        // IsFloating flag on lds gets the prefetch to disassemble
        // using f31 instead of r31... funcitonally it's unnecessary
        0x22: lds({{ EA = Rb + disp; }}, {{ Fa.uq = s_to_t(Mem.ul); }},
                  PF_EXCLUSIVE, IsFloating);  
    }

    format Store {
        0x0e: stb({{ EA = Rb + disp; }}, {{ Mem.ub = Ra<7:0>; }});
        0x0d: stw({{ EA = Rb + disp; }}, {{ Mem.uw = Ra<15:0>; }});
        0x2c: stl({{ EA = Rb + disp; }}, {{ Mem.ul = Ra<31:0>; }});
        0x2d: stq({{ EA = Rb + disp; }}, {{ Mem.uq = Ra.uq; }});
        0x0f: stq_u({{ EA = (Rb + disp) & ~7; }}, {{ Mem.uq = Ra.uq; }});
        0x26: sts({{ EA = Rb + disp; }}, {{ Mem.ul = t_to_s(Fa.uq); }});
        0x27: stt({{ EA = Rb + disp; }}, {{ Mem.df = Fa; }});
        0x24: copy_store({{EA = Rb;}},
                         {{fault = xc->copy(EA);}},
                         IsMemRef, IsStore, IsCopy);
    }

    format StoreCond {
        0x2e: stl_c({{ EA = Rb + disp; }}, {{ Mem.ul = Ra<31:0>; }},
                    {{
                        uint64_t tmp = Mem_write_result;
                        // see stq_c
                        Ra = (tmp == 0 || tmp == 1) ? tmp : Ra;
                    }}, LOCKED);
        0x2f: stq_c({{ EA = Rb + disp; }}, {{ Mem.uq = Ra; }},
                    {{
                        uint64_t tmp = Mem_write_result;
                        // If the write operation returns 0 or 1, then
                        // this was a conventional store conditional,
                        // and the value indicates the success/failure
                        // of the operation.  If another value is
                        // returned, then this was a Turbolaser
                        // mailbox access, and we don't update the
                        // result register at all.
                        Ra = (tmp == 0 || tmp == 1) ? tmp : Ra;
                    }}, LOCKED);
    }

    format IntegerOperate {

        0x10: decode INTFUNC {  // integer arithmetic operations

            0x00: addl({{ Rc.sl = Ra.sl + Rb_or_imm.sl; }});
            0x40: addlv({{
                uint32_t tmp  = Ra.sl + Rb_or_imm.sl;
                // signed overflow occurs when operands have same sign
                // and sign of result does not match.
                if (Ra.sl<31:> == Rb_or_imm.sl<31:> && tmp<31:> != Ra.sl<31:>)
                    fault = Integer_Overflow_Fault;
                Rc.sl = tmp;
            }});
            0x02: s4addl({{ Rc.sl = (Ra.sl << 2) + Rb_or_imm.sl; }});
            0x12: s8addl({{ Rc.sl = (Ra.sl << 3) + Rb_or_imm.sl; }});

            0x20: addq({{ Rc = Ra + Rb_or_imm; }});
            0x60: addqv({{
                uint64_t tmp = Ra + Rb_or_imm;
                // signed overflow occurs when operands have same sign
                // and sign of result does not match.
                if (Ra<63:> == Rb_or_imm<63:> && tmp<63:> != Ra<63:>)
                    fault = Integer_Overflow_Fault;
                Rc = tmp;
            }});
            0x22: s4addq({{ Rc = (Ra << 2) + Rb_or_imm; }});
            0x32: s8addq({{ Rc = (Ra << 3) + Rb_or_imm; }});

            0x09: subl({{ Rc.sl = Ra.sl - Rb_or_imm.sl; }});
            0x49: sublv({{
                uint32_t tmp  = Ra.sl - Rb_or_imm.sl;
                // signed overflow detection is same as for add,
                // except we need to look at the *complemented*
                // sign bit of the subtrahend (Rb), i.e., if the initial
                // signs are the *same* then no overflow can occur
                if (Ra.sl<31:> != Rb_or_imm.sl<31:> && tmp<31:> != Ra.sl<31:>)
                    fault = Integer_Overflow_Fault;
                Rc.sl = tmp;
            }});
            0x0b: s4subl({{ Rc.sl = (Ra.sl << 2) - Rb_or_imm.sl; }});
            0x1b: s8subl({{ Rc.sl = (Ra.sl << 3) - Rb_or_imm.sl; }});

            0x29: subq({{ Rc = Ra - Rb_or_imm; }});
            0x69: subqv({{
                uint64_t tmp  = Ra - Rb_or_imm;
                // signed overflow detection is same as for add,
                // except we need to look at the *complemented*
                // sign bit of the subtrahend (Rb), i.e., if the initial
                // signs are the *same* then no overflow can occur
                if (Ra<63:> != Rb_or_imm<63:> && tmp<63:> != Ra<63:>)
                    fault = Integer_Overflow_Fault;
                Rc = tmp;
            }});
            0x2b: s4subq({{ Rc = (Ra << 2) - Rb_or_imm; }});
            0x3b: s8subq({{ Rc = (Ra << 3) - Rb_or_imm; }});

            0x2d: cmpeq({{ Rc = (Ra == Rb_or_imm); }});
            0x6d: cmple({{ Rc = (Ra.sq <= Rb_or_imm.sq); }});
            0x4d: cmplt({{ Rc = (Ra.sq <  Rb_or_imm.sq); }});
            0x3d: cmpule({{ Rc = (Ra.uq <= Rb_or_imm.uq); }});
            0x1d: cmpult({{ Rc = (Ra.uq <  Rb_or_imm.uq); }});

            0x0f: cmpbge({{
                int hi = 7;
                int lo = 0;
                uint64_t tmp = 0;
                for (int i = 0; i < 8; ++i) {
                    tmp |= (Ra.uq<hi:lo> >= Rb_or_imm.uq<hi:lo>) << i;
                    hi += 8;
                    lo += 8;
                }
                Rc = tmp;
            }});
        }

        0x11: decode INTFUNC {  // integer logical operations

            0x00: and({{ Rc = Ra & Rb_or_imm; }});
            0x08: bic({{ Rc = Ra & ~Rb_or_imm; }});
            0x20: bis({{ Rc = Ra | Rb_or_imm; }});
            0x28: ornot({{ Rc = Ra | ~Rb_or_imm; }});
            0x40: xor({{ Rc = Ra ^ Rb_or_imm; }});
            0x48: eqv({{ Rc = Ra ^ ~Rb_or_imm; }});

            // conditional moves
            0x14: cmovlbs({{ Rc = ((Ra & 1) == 1) ? Rb_or_imm : Rc; }});
            0x16: cmovlbc({{ Rc = ((Ra & 1) == 0) ? Rb_or_imm : Rc; }});
            0x24: cmoveq({{ Rc = (Ra == 0) ? Rb_or_imm : Rc; }});
            0x26: cmovne({{ Rc = (Ra != 0) ? Rb_or_imm : Rc; }});
            0x44: cmovlt({{ Rc = (Ra.sq <  0) ? Rb_or_imm : Rc; }});
            0x46: cmovge({{ Rc = (Ra.sq >= 0) ? Rb_or_imm : Rc; }});
            0x64: cmovle({{ Rc = (Ra.sq <= 0) ? Rb_or_imm : Rc; }});
            0x66: cmovgt({{ Rc = (Ra.sq >  0) ? Rb_or_imm : Rc; }});

            // For AMASK, RA must be R31.
            0x61: decode RA {
                31: amask({{ Rc = Rb_or_imm & ~ULL(0x17); }});
            }

            // For IMPLVER, RA must be R31 and the B operand
            // must be the immediate value 1.
            0x6c: decode RA {
                31: decode IMM {
                    1: decode INTIMM {
                        // return EV5 for FULL_SYSTEM and EV6 otherwise
                        1: implver({{
#ifdef FULL_SYSTEM
                             Rc = 1;
#else
                             Rc = 2;
#endif
                        }});
                    }
                }
            }

#ifdef FULL_SYSTEM
            // The mysterious 11.25...
            0x25: WarnUnimpl::eleven25();
#endif
        }

        0x12: decode INTFUNC {
            0x39: sll({{ Rc = Ra << Rb_or_imm<5:0>; }});
            0x34: srl({{ Rc = Ra.uq >> Rb_or_imm<5:0>; }});
            0x3c: sra({{ Rc = Ra.sq >> Rb_or_imm<5:0>; }});

            0x02: mskbl({{ Rc = Ra & ~(mask( 8) << (Rb_or_imm<2:0> * 8)); }});
            0x12: mskwl({{ Rc = Ra & ~(mask(16) << (Rb_or_imm<2:0> * 8)); }});
            0x22: mskll({{ Rc = Ra & ~(mask(32) << (Rb_or_imm<2:0> * 8)); }});
            0x32: mskql({{ Rc = Ra & ~(mask(64) << (Rb_or_imm<2:0> * 8)); }});

            0x52: mskwh({{
                int bv = Rb_or_imm<2:0>;
                Rc =  bv ? (Ra & ~(mask(16) >> (64 - 8 * bv))) : Ra;
            }});
            0x62: msklh({{
                int bv = Rb_or_imm<2:0>;
                Rc =  bv ? (Ra & ~(mask(32) >> (64 - 8 * bv))) : Ra;
            }});
            0x72: mskqh({{
                int bv = Rb_or_imm<2:0>;
                Rc =  bv ? (Ra & ~(mask(64) >> (64 - 8 * bv))) : Ra;
            }});

            0x06: extbl({{ Rc = (Ra.uq >> (Rb_or_imm<2:0> * 8))< 7:0>; }});
            0x16: extwl({{ Rc = (Ra.uq >> (Rb_or_imm<2:0> * 8))<15:0>; }});
            0x26: extll({{ Rc = (Ra.uq >> (Rb_or_imm<2:0> * 8))<31:0>; }});
            0x36: extql({{ Rc = (Ra.uq >> (Rb_or_imm<2:0> * 8)); }});

            0x5a: extwh({{
                Rc = (Ra << (64 - (Rb_or_imm<2:0> * 8))<5:0>)<15:0>; }});
            0x6a: extlh({{
                Rc = (Ra << (64 - (Rb_or_imm<2:0> * 8))<5:0>)<31:0>; }});
            0x7a: extqh({{
                Rc = (Ra << (64 - (Rb_or_imm<2:0> * 8))<5:0>); }});

            0x0b: insbl({{ Rc = Ra< 7:0> << (Rb_or_imm<2:0> * 8); }});
            0x1b: inswl({{ Rc = Ra<15:0> << (Rb_or_imm<2:0> * 8); }});
            0x2b: insll({{ Rc = Ra<31:0> << (Rb_or_imm<2:0> * 8); }});
            0x3b: insql({{ Rc = Ra       << (Rb_or_imm<2:0> * 8); }});

            0x57: inswh({{
                int bv = Rb_or_imm<2:0>;
                Rc = bv ? (Ra.uq<15:0> >> (64 - 8 * bv)) : 0;
            }});
            0x67: inslh({{
                int bv = Rb_or_imm<2:0>;
                Rc = bv ? (Ra.uq<31:0> >> (64 - 8 * bv)) : 0;
            }});
            0x77: insqh({{
                int bv = Rb_or_imm<2:0>;
                Rc = bv ? (Ra.uq       >> (64 - 8 * bv)) : 0;
            }});

            0x30: zap({{
                uint64_t zapmask = 0;
                for (int i = 0; i < 8; ++i) {
                    if (Rb_or_imm<i:>)
                        zapmask |= (mask(8) << (i * 8));
                }
                Rc = Ra & ~zapmask;
            }});
            0x31: zapnot({{
                uint64_t zapmask = 0;
                for (int i = 0; i < 8; ++i) {
                    if (!Rb_or_imm<i:>)
                        zapmask |= (mask(8) << (i * 8));
                }
                Rc = Ra & ~zapmask;
            }});
        }

        0x13: decode INTFUNC {  // integer multiplies
            0x00: mull({{ Rc.sl = Ra.sl * Rb_or_imm.sl; }}, IntMultOp);
            0x20: mulq({{ Rc    = Ra    * Rb_or_imm;    }}, IntMultOp);
            0x30: umulh({{
                uint64_t hi, lo;
                mul128(Ra, Rb_or_imm, hi, lo);
                Rc = hi;
            }}, IntMultOp);
            0x40: mullv({{
                // 32-bit multiply with trap on overflow
                int64_t Rax = Ra.sl;    // sign extended version of Ra.sl
                int64_t Rbx = Rb_or_imm.sl;
                int64_t tmp = Rax * Rbx;
                // To avoid overflow, all the upper 32 bits must match
                // the sign bit of the lower 32.  We code this as
                // checking the upper 33 bits for all 0s or all 1s.
                uint64_t sign_bits = tmp<63:31>;
                if (sign_bits != 0 && sign_bits != mask(33))
                    fault = Integer_Overflow_Fault;
                Rc.sl = tmp<31:0>;
            }}, IntMultOp);
            0x60: mulqv({{
                // 64-bit multiply with trap on overflow
                uint64_t hi, lo;
                mul128(Ra, Rb_or_imm, hi, lo);
                // all the upper 64 bits must match the sign bit of
                // the lower 64
                if (!((hi == 0 && lo<63:> == 0) ||
                      (hi == mask(64) && lo<63:> == 1)))
                    fault = Integer_Overflow_Fault;
                Rc = lo;
            }}, IntMultOp);
        }

        0x1c: decode INTFUNC {
            0x00: decode RA { 31: sextb({{ Rc.sb = Rb_or_imm< 7:0>; }}); }
            0x01: decode RA { 31: sextw({{ Rc.sw = Rb_or_imm<15:0>; }}); }
        0x32: ctlz({{
            uint64_t count = 0;
            uint64_t temp = Rb;
            if (temp<63:32>) temp >>= 32; else count += 32;
            if (temp<31:16>) temp >>= 16; else count += 16;
            if (temp<15:8>) temp >>= 8; else count += 8;
            if (temp<7:4>) temp >>= 4; else count += 4;
            if (temp<3:2>) temp >>= 2; else count += 2;
            if (temp<1:1>) temp >>= 1; else count += 1;
            if ((temp<0:0>) != 0x1) count += 1; 
            Rc = count; 
            }}, IntAluOp);
         
        0x33: cttz({{
            uint64_t count = 0;
            uint64_t temp = Rb;
            if (!(temp<31:0>)) { temp >>= 32; count += 32; }
            if (!(temp<15:0>)) { temp >>= 16; count += 16; }
            if (!(temp<7:0>)) { temp >>= 8; count += 8; }
            if (!(temp<3:0>)) { temp >>= 4; count += 4; }
            if (!(temp<1:0>)) { temp >>= 2; count += 2; }
            if (!(temp<0:0> & ULL(0x1))) count += 1; 
            Rc = count; 
        }}, IntAluOp);

            format FailUnimpl {
                0x30: ctpop();
                0x31: perr();
                0x34: unpkbw();
                0x35: unpkbl();
                0x36: pkwb();
                0x37: pklb();
                0x38: minsb8();
                0x39: minsw4();
                0x3a: minub8();
                0x3b: minuw4();
                0x3c: maxub8();
                0x3d: maxuw4();
                0x3e: maxsb8();
                0x3f: maxsw4();
            }

            format BasicOperateWithNopCheck {
                0x70: decode RB {
                    31: ftoit({{ Rc = Fa.uq; }}, FloatCvtOp);
                }
                0x78: decode RB {
                    31: ftois({{ Rc.sl = t_to_s(Fa.uq); }},
                              FloatCvtOp);
                }
            }
        }
    }

    // Conditional branches.
    format CondBranch {
        0x39: beq({{ cond = (Ra == 0); }});
        0x3d: bne({{ cond = (Ra != 0); }});
        0x3e: bge({{ cond = (Ra.sq >= 0); }});
        0x3f: bgt({{ cond = (Ra.sq >  0); }});
        0x3b: ble({{ cond = (Ra.sq <= 0); }});
        0x3a: blt({{ cond = (Ra.sq < 0); }});
        0x38: blbc({{ cond = ((Ra & 1) == 0); }});
        0x3c: blbs({{ cond = ((Ra & 1) == 1); }});

        0x31: fbeq({{ cond = (Fa == 0); }});
        0x35: fbne({{ cond = (Fa != 0); }});
        0x36: fbge({{ cond = (Fa >= 0); }});
        0x37: fbgt({{ cond = (Fa >  0); }});
        0x33: fble({{ cond = (Fa <= 0); }});
        0x32: fblt({{ cond = (Fa < 0); }});
    }

    // unconditional branches
    format UncondBranch {
        0x30: br();
        0x34: bsr(IsCall);
    }

    // indirect branches
    0x1a: decode JMPFUNC {
        format Jump {
            0: jmp();
            1: jsr(IsCall);
            2: ret(IsReturn);
            3: jsr_coroutine(IsCall, IsReturn);
        }
    }

    // IEEE floating point
    0x14: decode FP_SHORTFUNC {
        // Integer to FP register moves must have RB == 31
        0x4: decode RB {
            31: decode FP_FULLFUNC {
                format BasicOperateWithNopCheck {
                    0x004: itofs({{ Fc.uq = s_to_t(Ra.ul); }}, FloatCvtOp);
                    0x024: itoft({{ Fc.uq = Ra.uq; }}, FloatCvtOp);
                    0x014: FailUnimpl::itoff(); // VAX-format conversion
                }
            }
        }

        // Square root instructions must have FA == 31
        0xb: decode FA {
            31: decode FP_TYPEFUNC {
                format FloatingPointOperate {
#ifdef SS_COMPATIBLE_FP
                    0x0b: sqrts({{
                        if (Fb < 0.0)
                            fault = Arithmetic_Fault;
                        Fc = sqrt(Fb);
                    }}, FloatSqrtOp);
#else
                    0x0b: sqrts({{
                        if (Fb.sf < 0.0)
                            fault = Arithmetic_Fault;
                        Fc.sf = sqrt(Fb.sf);
                    }}, FloatSqrtOp);
#endif
                    0x2b: sqrtt({{
                        if (Fb < 0.0)
                            fault = Arithmetic_Fault;
                        Fc = sqrt(Fb);
                    }}, FloatSqrtOp);
                }
            }
        }

        // VAX-format sqrtf and sqrtg are not implemented
        0xa: FailUnimpl::sqrtfg();
    }

    // IEEE floating point
    0x16: decode FP_SHORTFUNC_TOP2 {
        // The top two bits of the short function code break this space
        // into four groups: binary ops, compares, reserved, and conversions.
        // See Table 4-12 of AHB.       
        // Most of these instructions may have various trapping and
        // rounding mode flags set; these are decoded in the
        // FloatingPointDecode template used by the
        // FloatingPointOperate format.

        // add/sub/mul/div: just decode on the short function code
        // and source type.
        0: decode FP_TYPEFUNC {
            format FloatingPointOperate {
#ifdef SS_COMPATIBLE_FP
                0x00: adds({{ Fc = Fa + Fb; }});
                0x01: subs({{ Fc = Fa - Fb; }});
                0x02: muls({{ Fc = Fa * Fb; }}, FloatMultOp);
                0x03: divs({{ Fc = Fa / Fb; }}, FloatDivOp);
#else
                0x00: adds({{ Fc.sf = Fa.sf + Fb.sf; }});
                0x01: subs({{ Fc.sf = Fa.sf - Fb.sf; }});
                0x02: muls({{ Fc.sf = Fa.sf * Fb.sf; }}, FloatMultOp);
                0x03: divs({{ Fc.sf = Fa.sf / Fb.sf; }}, FloatDivOp);
#endif

                0x20: addt({{ Fc = Fa + Fb; }});
                0x21: subt({{ Fc = Fa - Fb; }});
                0x22: mult({{ Fc = Fa * Fb; }}, FloatMultOp);
                0x23: divt({{ Fc = Fa / Fb; }}, FloatDivOp);
            }
        }

        // Floating-point compare instructions must have the default
        // rounding mode, and may use the default trapping mode or
        // /SU.  Both trapping modes are treated the same by M5; the
        // only difference on the real hardware (as far a I can tell)
        // is that without /SU you'd get an imprecise trap if you
        // tried to compare a NaN with something else (instead of an
        // "unordered" result).
        1: decode FP_FULLFUNC {
            format BasicOperateWithNopCheck {
                0x0a5, 0x5a5: cmpteq({{ Fc = (Fa == Fb) ? 2.0 : 0.0; }},
                                     FloatCmpOp);
                0x0a7, 0x5a7: cmptle({{ Fc = (Fa <= Fb) ? 2.0 : 0.0; }},
                                     FloatCmpOp);
                0x0a6, 0x5a6: cmptlt({{ Fc = (Fa <  Fb) ? 2.0 : 0.0; }},
                                     FloatCmpOp);
                0x0a4, 0x5a4: cmptun({{ // unordered
                    Fc = (!(Fa < Fb) && !(Fa == Fb) && !(Fa > Fb)) ? 2.0 : 0.0;
                }}, FloatCmpOp);
            }
        }

        // The FP-to-integer and integer-to-FP conversion insts
        // require that FA be 31.
        3: decode FA {
            31: decode FP_TYPEFUNC {
                format FloatingPointOperate {
                    0x2f: cvttq({{ Fc.sq = (int64_t)rint(Fb); }});

                    // The cvtts opcode is overloaded to be cvtst if the trap
                    // mode is 2 or 6 (which are not valid otherwise)
                    0x2c: decode FP_FULLFUNC {
                        format BasicOperateWithNopCheck {
                            // trap on denorm version "cvtst/s" is
                            // simulated same as cvtst
                            0x2ac, 0x6ac: cvtst({{ Fc = Fb.sf; }});
                        }
                      default: cvtts({{ Fc.sf = Fb; }});
                    }

                    // The trapping mode for integer-to-FP conversions
                    // must be /SUI or nothing; /U and /SU are not
                    // allowed.  The full set of rounding modes are
                    // supported though.
                    0x3c: decode FP_TRAPMODE {
                        0,7: cvtqs({{ Fc.sf = Fb.sq; }});
                    }
                    0x3e: decode FP_TRAPMODE {
                        0,7: cvtqt({{ Fc    = Fb.sq; }});
                    }
                }
            }
        }
    }

    // misc FP operate
    0x17: decode FP_FULLFUNC {
        format BasicOperateWithNopCheck {
            0x010: cvtlq({{
                Fc.sl = (Fb.uq<63:62> << 30) | Fb.uq<58:29>;
            }});
            0x030: cvtql({{
                Fc.uq = (Fb.uq<31:30> << 62) | (Fb.uq<29:0> << 29);
            }});

            // We treat the precise & imprecise trapping versions of
            // cvtql identically.
            0x130, 0x530: cvtqlv({{
                // To avoid overflow, all the upper 32 bits must match
                // the sign bit of the lower 32.  We code this as
                // checking the upper 33 bits for all 0s or all 1s.
                uint64_t sign_bits = Fb.uq<63:31>;
                if (sign_bits != 0 && sign_bits != mask(33))
                    fault = Integer_Overflow_Fault;
                Fc.uq = (Fb.uq<31:30> << 62) | (Fb.uq<29:0> << 29);
            }});

            0x020: cpys({{  // copy sign
                Fc.uq = (Fa.uq<63:> << 63) | Fb.uq<62:0>;
            }});
            0x021: cpysn({{ // copy sign negated
                Fc.uq = (~Fa.uq<63:> << 63) | Fb.uq<62:0>;
            }});
            0x022: cpyse({{ // copy sign and exponent
                Fc.uq = (Fa.uq<63:52> << 52) | Fb.uq<51:0>;
            }});

            0x02a: fcmoveq({{ Fc = (Fa == 0) ? Fb : Fc; }});
            0x02b: fcmovne({{ Fc = (Fa != 0) ? Fb : Fc; }});
            0x02c: fcmovlt({{ Fc = (Fa <  0) ? Fb : Fc; }});
            0x02d: fcmovge({{ Fc = (Fa >= 0) ? Fb : Fc; }});
            0x02e: fcmovle({{ Fc = (Fa <= 0) ? Fb : Fc; }});
            0x02f: fcmovgt({{ Fc = (Fa >  0) ? Fb : Fc; }});

            0x024: mt_fpcr({{ FPCR = Fa.uq; }});
            0x025: mf_fpcr({{ Fa.uq = FPCR; }});
        }
    }

    // miscellaneous mem-format ops
    0x18: decode MEMFUNC {
        format WarnUnimpl {
            0x8000: fetch();
            0xa000: fetch_m();
            0xe800: ecb();
        }

        format MiscPrefetch {
            0xf800: wh64({{ EA = Rb & ~ULL(63); }},
                         {{ xc->writeHint(EA, 64, memAccessFlags); }},
                         IsMemRef, IsDataPrefetch, IsStore, MemWriteOp,
                         NO_FAULT);
        }

        format BasicOperate {
            0xc000: rpcc({{
#ifdef FULL_SYSTEM
        /* Rb is a fake dependency so here is a fun way to get
         * the parser to understand that.
         */
                Ra = xc->readIpr(AlphaISA::IPR_CC, fault) + (Rb & 0);
        
#else
                Ra = curTick;
#endif
            }});

            // All of the barrier instructions below do nothing in
            // their execute() methods (hence the empty code blocks).
            // All of their functionality is hard-coded in the
            // pipeline based on the flags IsSerializing,
            // IsMemBarrier, and IsWriteBarrier.  In the current
            // detailed CPU model, the execute() function only gets
            // called at fetch, so there's no way to generate pipeline
            // behavior at any other stage.  Once we go to an
            // exec-in-exec CPU model we should be able to get rid of
            // these flags and implement this behavior via the
            // execute() methods.

            // trapb is just a barrier on integer traps, where excb is
            // a barrier on integer and FP traps.  "EXCB is thus a
            // superset of TRAPB." (Alpha ARM, Sec 4.11.4) We treat
            // them the same though.
            0x0000: trapb({{ }}, IsSerializing, No_OpClass);
            0x0400: excb({{ }}, IsSerializing, No_OpClass);
            0x4000: mb({{ }}, IsMemBarrier, MemReadOp);
            0x4400: wmb({{ }}, IsWriteBarrier, MemWriteOp);
        }

#ifdef FULL_SYSTEM
        format BasicOperate {
            0xe000: rc({{
                Ra = xc->readIntrFlag();
                xc->setIntrFlag(0);
            }}, IsNonSpeculative);
            0xf000: rs({{
                Ra = xc->readIntrFlag();
                xc->setIntrFlag(1);
            }}, IsNonSpeculative);
        }
#else
        format FailUnimpl {
            0xe000: rc();
            0xf000: rs();
        }
#endif
    }

#ifdef FULL_SYSTEM
    0x00: CallPal::call_pal({{
        if (!palValid ||
            (palPriv
             && xc->readIpr(AlphaISA::IPR_ICM, fault) != AlphaISA::mode_kernel)) {
            // invalid pal function code, or attempt to do privileged
            // PAL call in non-kernel mode
            fault = Unimplemented_Opcode_Fault;
        }
        else {
            // check to see if simulator wants to do something special
            // on this PAL call (including maybe suppress it)
            bool dopal = xc->simPalCheck(palFunc);

            if (dopal) {
                AlphaISA::swap_palshadow(&xc->xcBase()->regs, true);
                xc->setIpr(AlphaISA::IPR_EXC_ADDR, NPC);
                NPC = xc->readIpr(AlphaISA::IPR_PAL_BASE, fault) + palOffset;
            }
        }
    }}, IsNonSpeculative);
#else
    0x00: decode PALFUNC {
        format EmulatedCallPal {
            0x00: halt ({{
                SimExit(curTick, "halt instruction encountered");
            }}, IsNonSpeculative);
            0x83: callsys({{ 
                xc->syscall();
            }}, IsNonSpeculative);
            // Read uniq reg into ABI return value register (r0)
            0x9e: rduniq({{ R0 = Runiq; }}, IsNonSpeculative);
            // Write uniq reg with value from ABI arg register (r16)
            0x9f: wruniq({{ Runiq = R16; }}, IsNonSpeculative);
        }
    }
#endif

#ifdef FULL_SYSTEM
    format HwLoadStore {
        0x1b: decode HW_LDST_QUAD {
            0: hw_ld({{ EA = (Rb + disp) & ~3; }}, {{ Ra = Mem.ul; }}, L);
            1: hw_ld({{ EA = (Rb + disp) & ~7; }}, {{ Ra = Mem.uq; }}, Q);
        }

        0x1f: decode HW_LDST_COND {
            0: decode HW_LDST_QUAD {
                0: hw_st({{ EA = (Rb + disp) & ~3; }},
                         {{ Mem.ul = Ra<31:0>; }}, L);
                1: hw_st({{ EA = (Rb + disp) & ~7; }},
                         {{ Mem.uq = Ra.uq; }}, Q);
            }

            1: FailUnimpl::hw_st_cond();
        }
    }

    format BasicOperate {
        0x1e: hw_rei({{ xc->hwrei(); }});

        // M5 special opcodes use the reserved 0x01 opcode space
        0x01: decode M5FUNC {
            0x00: arm({{
                AlphaPseudo::arm(xc->xcBase());
            }}, IsNonSpeculative);
            0x01: quiesce({{
                AlphaPseudo::quiesce(xc->xcBase());
            }}, IsNonSpeculative);
            0x10: ivlb({{
                AlphaPseudo::ivlb(xc->xcBase());
            }}, No_OpClass, IsNonSpeculative);
            0x11: ivle({{
                AlphaPseudo::ivle(xc->xcBase());
            }}, No_OpClass, IsNonSpeculative);
            0x20: m5exit_old({{
                AlphaPseudo::m5exit_old(xc->xcBase());
            }}, No_OpClass, IsNonSpeculative);
            0x21: m5exit({{
                AlphaPseudo::m5exit(xc->xcBase());
            }}, No_OpClass, IsNonSpeculative);
            0x30: initparam({{ Ra = xc->xcBase()->cpu->system->init_param; }});
            0x40: resetstats({{
                AlphaPseudo::resetstats(xc->xcBase());
            }}, IsNonSpeculative);
            0x41: dumpstats({{
                AlphaPseudo::dumpstats(xc->xcBase());
            }}, IsNonSpeculative);
            0x42: dumpresetstats({{
                AlphaPseudo::dumpresetstats(xc->xcBase());
            }}, IsNonSpeculative);
            0x43: m5checkpoint({{
                AlphaPseudo::m5checkpoint(xc->xcBase());
            }}, IsNonSpeculative);
            0x50: m5readfile({{
                AlphaPseudo::readfile(xc->xcBase());
            }}, IsNonSpeculative);
            0x51: m5break({{
        AlphaPseudo::debugbreak(xc->xcBase());
        }}, IsNonSpeculative);
            0x52: m5switchcpu({{
        AlphaPseudo::switchcpu(xc->xcBase());
        }}, IsNonSpeculative);

        }
    }

    format HwMoveIPR {
        0x19: hw_mfpr({{
            // this instruction is only valid in PAL mode
            if (!xc->inPalMode()) {
                fault = Unimplemented_Opcode_Fault;
            }
            else {
                Ra = xc->readIpr(ipr_index, fault);
            }
        }});
        0x1d: hw_mtpr({{
            // this instruction is only valid in PAL mode
            if (!xc->inPalMode()) {
                fault = Unimplemented_Opcode_Fault;
            }
            else {
                xc->setIpr(ipr_index, Ra);
                if (traceData) { traceData->setData(Ra); }
            }
        }});
    }
#endif
}