src/arch/mips/isa/formats/noop.isa

   1 // -*- mode:c++ -*-
   2
   3 ////////////////////////////////////////////////////////////////////
   4 //
   5 // Nop
   6 //
   7
   8 output header {{
   9     /**
  10      * Static instruction class for no-ops.  This is a leaf class.
  11      */
  12     class Nop : public MipsStaticInst
  13     {
  14         /// Disassembly of original instruction.
  15         const std::string originalDisassembly;
  16
  17       public:
  18         /// Constructor
  19         Nop(const std::string _originalDisassembly, MachInst _machInst)
  20             : MipsStaticInst("nop", _machInst, No_OpClass),
  21               originalDisassembly(_originalDisassembly)
  22         {
  23             flags[IsNop] = true;
  24         }
  25
  26         ~Nop() { }
  27
  28         std::string
  29         generateDisassembly(Addr pc, const SymbolTable *symtab) const;
  30
  31         %(BasicExecDeclare)s
  32     };
  33 }};
  34
  35 output decoder {{
  36     std::string Nop::generateDisassembly(Addr pc,
  37                                          const SymbolTable *symtab) const
  38     {
  39         return csprintf("%-10s %s", "nop", originalDisassembly);
  40     }
  41
  42     /// Helper function for decoding nops.  Substitute Nop object
  43     /// for original inst passed in as arg (and delete latter).
  44     inline
  45     MipsStaticInst *
  46     makeNop(MipsStaticInst *inst)
  47     {
  48         MipsStaticInst *nop = new Nop(inst->disassemble(0), inst->machInst);
  49         delete inst;
  50         return nop;
  51     }
  52 }};
  53
  54 output exec {{
  55     Fault
  56     Nop::execute(%(CPU_exec_context)s *, Trace::InstRecord *) const
  57     {
  58         return NoFault;
  59     }
  60 }};
  61
  62 // integer & FP operate instructions use RT as dest, so check for
  63 // RT == 0 to detect nops
  64 def template OperateNopCheckDecode {{
  65  {
  66      MipsStaticInst *i = new %(class_name)s(machInst);
  67
  68      //if (RD == 0) {
  69      //  i = makeNop(i);
  70      //}
  71
  72      return i;
  73  }
  74 }};
  75
  76
  77 // Like BasicOperate format, but generates NOP if RC/FC == 31
  78 def format BasicOperateWithNopCheck(code, *opt_args) {{
  79     iop = InstObjParams(name, Name, 'MipsStaticInst', CodeBlock(code),
  80                         opt_args)
  81     header_output = BasicDeclare.subst(iop)
  82     decoder_output = BasicConstructor.subst(iop)
  83     decode_block = OperateNopCheckDecode.subst(iop)
  84     exec_output = BasicExecute.subst(iop)
  85 }};
  86
  87 def format Nop() {{
  88         decode_block = 'return new Nop(\"\",machInst);\n'
  89 }};
  90