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 #ifdef SS_COMPATIBLE_DISASSEMBLY
  40         return originalDisassembly;
  41 #else
  42         return csprintf("%-10s (%s)", "nop", originalDisassembly);
  43 #endif
  44     }
  45
  46     /// Helper function for decoding nops.  Substitute Nop object
  47     /// for original inst passed in as arg (and delete latter).
  48     inline
  49     MipsStaticInst *
  50     makeNop(MipsStaticInst *inst)
  51     {
  52         MipsStaticInst *nop = new Nop(inst->disassemble(0), inst->machInst);
  53         delete inst;
  54         return nop;
  55     }
  56 }};
  57
  58 output exec {{
  59     Fault
  60     Nop::execute(%(CPU_exec_context)s *, Trace::InstRecord *) const
  61     {
  62         return NoFault;
  63     }
  64 }};
  65
  66 // integer & FP operate instructions use RT as dest, so check for
  67 // RT == 0 to detect nops
  68 def template OperateNopCheckDecode {{
  69  {
  70      MipsStaticInst *i = new %(class_name)s(machInst);
  71
  72      //if (RD == 0) {
  73      //  i = makeNop(i);
  74      //}
  75
  76      return i;
  77  }
  78 }};
  79
  80
  81 // Like BasicOperate format, but generates NOP if RC/FC == 31
  82 def format BasicOperateWithNopCheck(code, *opt_args) {{
  83     iop = InstObjParams(name, Name, 'MipsStaticInst', CodeBlock(code),
  84                         opt_args)
  85     header_output = BasicDeclare.subst(iop)
  86     decoder_output = BasicConstructor.subst(iop)
  87     decode_block = OperateNopCheckDecode.subst(iop)
  88     exec_output = BasicExecute.subst(iop)
  89 }};
  90
  91 def format Nop() {{
  92         decode_block = 'return new Nop(\"sll r0,r0,0\",machInst);\n'
  93 }};
  94