noop.isa revision 2750
1// -*- mode:c++ -*- 2 3//////////////////////////////////////////////////////////////////// 4// 5// Nop 6// 7 8output 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 35output 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 std::string nop_str = "(" + inst->disassemble(0) + ")"; 49 MipsStaticInst *nop = new Nop(nop_str, inst->machInst); 50 delete inst; 51 return nop; 52 } 53}}; 54 55output exec {{ 56 Fault 57 Nop::execute(%(CPU_exec_context)s *, Trace::InstRecord *) const 58 { 59 return NoFault; 60 } 61}}; 62 63// Int & FP operate instructions use RD as dest, so check for 64// RD == 0 to detect nops 65def template RegNopCheckDecode {{ 66 { 67 MipsStaticInst *i = new %(class_name)s(machInst); 68 //if (RD == 0) { 69 //i = makeNop(i); 70 //} 71 return i; 72 } 73}}; 74 75def template OperateNopCheckDecode {{ 76 { 77 MipsStaticInst *i = new %(class_name)s(machInst); 78 //if (RD == 0) { 79 // i = makeNop(i); 80 //} 81 return i; 82 } 83}}; 84 85// IntImm & Memory instructions use Rt as dest, so check for 86// Rt == 0 to detect nops 87def template ImmNopCheckDecode {{ 88 { 89 MipsStaticInst *i = new %(class_name)s(machInst); 90 //if (RT == 0) { 91 // i = makeNop(i); 92 // } 93 return i; 94 } 95}}; 96 97 98// Like BasicOperate format, but generates NOP if RC/FC == 31 99def format BasicOperateWithNopCheck(code, *opt_args) {{ 100 iop = InstObjParams(name, Name, 'MipsStaticInst', CodeBlock(code), 101 opt_args) 102 header_output = BasicDeclare.subst(iop) 103 decoder_output = BasicConstructor.subst(iop) 104 decode_block = OperateNopCheckDecode.subst(iop) 105 exec_output = BasicExecute.subst(iop) 106}}; 107 108def format Nop() {{ 109 decode_block = 'return new Nop(\"\",machInst);\n' 110}}; 111 112