branch.isa revision 3985 
1// Copyright (c) 2006-2007 The Regents of The University of Michigan
2// All rights reserved.
3//
4// Redistribution and use in source and binary forms, with or without
5// modification, are permitted provided that the following conditions are
6// met: redistributions of source code must retain the above copyright
7// notice, this list of conditions and the following disclaimer;
8// redistributions in binary form must reproduce the above copyright
9// notice, this list of conditions and the following disclaimer in the
10// documentation and/or other materials provided with the distribution;
11// neither the name of the copyright holders nor the names of its
12// contributors may be used to endorse or promote products derived from
13// this software without specific prior written permission.
14//
15// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
18// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
19// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
20// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
21// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
25// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26//
27// Authors: Gabe Black
28//          Steve Reinhardt
29
30////////////////////////////////////////////////////////////////////
31//
32// Branch instructions
33//
34
35output header {{
36        /**
37         * Base class for branch operations.
38         */
39        class Branch : public SparcStaticInst
40        {
41          protected:
42            // Constructor
43            Branch(const char *mnem, MachInst _machInst, OpClass __opClass) :
44                SparcStaticInst(mnem, _machInst, __opClass)
45            {
46            }
47
48            std::string generateDisassembly(Addr pc,
49                    const SymbolTable *symtab) const;
50        };
51
52        /**
53         * Base class for branch operations with an immediate displacement.
54         */
55        class BranchDisp : public Branch
56        {
57          protected:
58            // Constructor
59            BranchDisp(const char *mnem, MachInst _machInst,
60                    OpClass __opClass) :
61                Branch(mnem, _machInst, __opClass)
62            {
63            }
64
65            std::string generateDisassembly(Addr pc,
66                    const SymbolTable *symtab) const;
67
68            int32_t disp;
69        };
70
71        /**
72         * Base class for branches with n bit displacements.
73         */
74        template<int bits>
75        class BranchNBits : public BranchDisp
76        {
77          protected:
78            // Constructor
79            BranchNBits(const char *mnem, MachInst _machInst,
80                    OpClass __opClass) :
81                BranchDisp(mnem, _machInst, __opClass)
82            {
83                disp = sext<bits + 2>((_machInst & mask(bits)) << 2);
84            }
85        };
86
87        /**
88         * Base class for 16bit split displacements.
89         */
90        class BranchSplit : public BranchDisp
91        {
92          protected:
93            // Constructor
94            BranchSplit(const char *mnem, MachInst _machInst,
95                    OpClass __opClass) :
96                BranchDisp(mnem, _machInst, __opClass)
97            {
98                disp = sext<18>((D16HI << 16) | (D16LO << 2));
99            }
100        };
101
102        /**
103         * Base class for branches that use an immediate and a register to
104         * compute their displacements.
105         */
106        class BranchImm13 : public Branch
107        {
108          protected:
109            // Constructor
110            BranchImm13(const char *mnem, MachInst _machInst, OpClass __opClass) :
111                Branch(mnem, _machInst, __opClass), imm(sext<13>(SIMM13))
112            {
113            }
114
115            std::string generateDisassembly(Addr pc,
116                    const SymbolTable *symtab) const;
117
118            int32_t imm;
119        };
120}};
121
122output decoder {{
123
124        template class BranchNBits<19>;
125
126        template class BranchNBits<22>;
127
128        template class BranchNBits<30>;
129
130        std::string Branch::generateDisassembly(Addr pc,
131                const SymbolTable *symtab) const
132        {
133            std::stringstream response;
134
135            printMnemonic(response, mnemonic);
136            printRegArray(response, _srcRegIdx, _numSrcRegs);
137            if(_numDestRegs && _numSrcRegs)
138                    response << ", ";
139            printDestReg(response, 0);
140
141            return response.str();
142        }
143
144        std::string BranchImm13::generateDisassembly(Addr pc,
145                const SymbolTable *symtab) const
146        {
147            std::stringstream response;
148
149            printMnemonic(response, mnemonic);
150            printRegArray(response, _srcRegIdx, _numSrcRegs);
151            if(_numSrcRegs > 0)
152                response << ", ";
153            ccprintf(response, "0x%x", imm);
154            if (_numDestRegs > 0)
155                response << ", ";
156            printDestReg(response, 0);
157
158            return response.str();
159        }
160
161        std::string BranchDisp::generateDisassembly(Addr pc,
162                const SymbolTable *symtab) const
163        {
164            std::stringstream response;
165            std::string symbol;
166            Addr symbolAddr;
167
168            Addr target = disp + pc;
169
170            printMnemonic(response, mnemonic);
171            ccprintf(response, "0x%x", target);
172
173            if(symtab && symtab->findNearestSymbol(target, symbol, symbolAddr))
174            {
175                ccprintf(response, " <%s", symbol);
176                if(symbolAddr != target)
177                    ccprintf(response, "+%d>", target - symbolAddr);
178                else
179                    ccprintf(response, ">");
180            }
181
182            return response.str();
183        }
184}};
185
186def template BranchExecute {{
187        Fault %(class_name)s::execute(%(CPU_exec_context)s *xc,
188                Trace::InstRecord *traceData) const
189        {
190            //Attempt to execute the instruction
191            Fault fault = NoFault;
192
193            %(op_decl)s;
194            %(op_rd)s;
195
196            NNPC = xc->readNextNPC();
197            %(code)s;
198
199            if(fault == NoFault)
200            {
201                //Write the resulting state to the execution context
202                %(op_wb)s;
203            }
204
205            return fault;
206        }
207}};
208
209let {{
210    handle_annul = '''
211    {
212        if(A)
213        {
214            NPC = xc->readNextNPC();
215            NNPC = NPC + 4;
216        }
217        else
218        {
219            NPC = xc->readNextPC();
220            NNPC = xc->readNextNPC();
221        }
222    }'''
223}};
224
225// Primary format for branch instructions:
226def format Branch(code, *opt_flags) {{
227        (usesImm, code, immCode,
228         rString, iString) = splitOutImm(code)
229        iop = InstObjParams(name, Name, 'Branch', code, opt_flags)
230        header_output = BasicDeclare.subst(iop)
231        decoder_output = BasicConstructor.subst(iop)
232        exec_output = BranchExecute.subst(iop)
233        if usesImm:
234            imm_iop = InstObjParams(name, Name + 'Imm', 'BranchImm' + iString,
235                    immCode, opt_flags)
236            header_output += BasicDeclare.subst(imm_iop)
237            decoder_output += BasicConstructor.subst(imm_iop)
238            exec_output += BranchExecute.subst(imm_iop)
239            decode_block = ROrImmDecode.subst(iop)
240        else:
241            decode_block = BasicDecode.subst(iop)
242}};
243
244// Primary format for branch instructions:
245def format BranchN(bits, code, *opt_flags) {{
246        code = re.sub(r'handle_annul', handle_annul, code)
247        new_opt_flags = []
248        for flag in opt_flags:
249            if flag == ',a':
250                name += ',a'
251                Name += 'Annul'
252            else:
253                new_opt_flags += flag
254        iop = InstObjParams(name, Name, "BranchNBits<%d>" % bits, code, new_opt_flags)
255        header_output = BasicDeclare.subst(iop)
256        decoder_output = BasicConstructor.subst(iop)
257        exec_output = BranchExecute.subst(iop)
258        decode_block = BasicDecode.subst(iop)
259}};
260
261// Primary format for branch instructions:
262def format BranchSplit(code, *opt_flags) {{
263        code = re.sub(r'handle_annul', handle_annul, code)
264        iop = InstObjParams(name, Name, 'BranchSplit', code, opt_flags)
265        header_output = BasicDeclare.subst(iop)
266        decoder_output = BasicConstructor.subst(iop)
267        exec_output = BranchExecute.subst(iop)
268        decode_block = BasicDecode.subst(iop)
269}};
270
271