1// -*- mode:c++ -*-
2
3// Copyright (c) 2007 MIPS Technologies, Inc.
4// All rights reserved.
5//
6// Redistribution and use in source and binary forms, with or without
7// modification, are permitted provided that the following conditions are
8// met: redistributions of source code must retain the above copyright
9// notice, this list of conditions and the following disclaimer;
10// redistributions in binary form must reproduce the above copyright
11// notice, this list of conditions and the following disclaimer in the
12// documentation and/or other materials provided with the distribution;
13// neither the name of the copyright holders nor the names of its
14// contributors may be used to endorse or promote products derived from
15// this software without specific prior written permission.
16//
17// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
20// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
21// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
22// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
27// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28//
29// Authors: Korey Sewell
30
31////////////////////////////////////////////////////////////////////
32//
33// Nop
34//
35
36output header {{
37 /**
38 * Static instruction class for no-ops. This is a leaf class.
39 */
40 class Nop : public MipsStaticInst
41 {
42 /// Disassembly of original instruction.
43 const std::string originalDisassembly;
44
45 public:
46 /// Constructor
47 Nop(const std::string _originalDisassembly, MachInst _machInst)
48 : MipsStaticInst("nop", _machInst, No_OpClass),
49 originalDisassembly(_originalDisassembly)
50 {
51 flags[IsNop] = true;
52 }
53
54 ~Nop() { }
55
56 std::string generateDisassembly(
57 Addr pc, const SymbolTable *symtab) const override;
58
59 Fault execute(ExecContext *, Trace::InstRecord *) const override;
60 };
61}};
62
63output decoder {{
64 std::string Nop::generateDisassembly(Addr pc,
65 const SymbolTable *symtab) const
66 {
67 return csprintf("%-10s %s", "nop", originalDisassembly);
68 }
69
70 /// Helper function for decoding nops. Substitute Nop object
71 /// for original inst passed in as arg (and delete latter).
72 inline
73 MipsStaticInst *
74 makeNop(MipsStaticInst *inst)
75 {
76 std::string nop_str = "(" + inst->disassemble(0) + ")";
77 MipsStaticInst *nop = new Nop(nop_str, inst->machInst);
78 delete inst;
79 return nop;
80 }
81}};
82
83output exec {{
84 Fault
85 Nop::execute(ExecContext *, Trace::InstRecord *) const
86 {
87 return NoFault;
88 }
89}};
90
91// Int & FP operate instructions use RD as dest, so check for
92// RD == 0 to detect nops
93def template RegNopCheckDecode {{
94 {
95 MipsStaticInst *i = new %(class_name)s(machInst);
96 //if (RD == 0) {
97 //i = makeNop(i);
98 //}
99 return i;
100 }
101}};
102
103def template OperateNopCheckDecode {{
104 {
105 MipsStaticInst *i = new %(class_name)s(machInst);
106 //if (RD == 0) {
107 // i = makeNop(i);
108 //}
109 return i;
110 }
111}};
112
113// IntImm & Memory instructions use Rt as dest, so check for
114// Rt == 0 to detect nops
115def template ImmNopCheckDecode {{
116 {
117 MipsStaticInst *i = new %(class_name)s(machInst);
118 //if (RT == 0) {
119 // i = makeNop(i);
120 // }
121 return i;
122 }
123}};
124
125
126// Like BasicOperate format, but generates NOP if RC/FC == 31
127def format BasicOperateWithNopCheck(code, *opt_args) {{
128 iop = InstObjParams(name, Name, 'MipsStaticInst', code,
129 opt_args)
130 header_output = BasicDeclare.subst(iop)
131 decoder_output = BasicConstructor.subst(iop)
132 decode_block = OperateNopCheckDecode.subst(iop)
133 exec_output = BasicExecute.subst(iop)
134}};
135
136def format Nop() {{
137 decode_block = 'return new Nop(\"\",machInst);\n'
138}};
139