noop.isa revision 10196:be0e1724eb39 
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
57        generateDisassembly(Addr pc, const SymbolTable *symtab) const;
58
59        %(BasicExecDeclare)s
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(CPU_EXEC_CONTEXT *, 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
140