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