summaryrefslogtreecommitdiff
path: root/cpu/static_inst.hh
blob: 3eeefb6756684038aa5f803ae1297e98076b5112 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
/*
 * Copyright (c) 2003 The Regents of The University of Michigan
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef __STATIC_INST_HH__
#define __STATIC_INST_HH__

#include <bitset>
#include <string>

#include "sim/host.hh"
#include "base/hashmap.hh"
#include "base/refcnt.hh"

#include "cpu/full_cpu/op_class.hh"
#include "targetarch/isa_traits.hh"

// forward declarations
class ExecContext;
class DynInst;
class FastCPU;
class SimpleCPU;
class SymbolTable;

namespace Trace {
    class InstRecord;
}

/**
 * Base, ISA-independent static instruction class.
 *
 * The main component of this class is the vector of flags and the
 * associated methods for reading them.  Any object that can rely
 * solely on these flags can process instructions without being
 * recompiled for multiple ISAs.
 */
class StaticInstBase : public RefCounted
{
  protected:

    /// Set of boolean static instruction properties.
    ///
    /// Notes:
    /// - The IsInteger and IsFloating flags are based on the class of
    /// registers accessed by the instruction.  Although most
    /// instructions will have exactly one of these two flags set, it
    /// is possible for an instruction to have neither (e.g., direct
    /// unconditional branches, memory barriers) or both (e.g., an
    /// FP/int conversion).
    /// - If IsMemRef is set, then exactly one of IsLoad or IsStore
    /// will be set.  Prefetches are marked as IsLoad, even if they
    /// prefetch exclusive copies.
    /// - If IsControl is set, then exactly one of IsDirectControl or
    /// IsIndirect Control will be set, and exactly one of
    /// IsCondControl or IsUncondControl will be set.
    /// - IsSerializing, IsMemBarrier, and IsWriteBarrier are
    /// implemented as flags since in the current model there's no
    /// other way for instructions to inject behavior into the
    /// pipeline outside of fetch.  Once we go to an exec-in-exec CPU
    /// model we should be able to get rid of these flags and
    /// implement this behavior via the execute() methods.
    ///
    enum Flags {
        IsNop,		///< Is a no-op (no effect at all).

        IsInteger,	///< References integer regs.
        IsFloating,	///< References FP regs.

        IsMemRef,	///< References memory (load, store, or prefetch).
        IsLoad,		///< Reads from memory (load or prefetch).
        IsStore,	///< Writes to memory.
        IsInstPrefetch,	///< Instruction-cache prefetch.
        IsDataPrefetch,	///< Data-cache prefetch.
        IsCopy,         ///< Fast Cache block copy

        IsControl,		///< Control transfer instruction.
        IsDirectControl,	///< PC relative control transfer.
        IsIndirectControl,	///< Register indirect control transfer.
        IsCondControl,		///< Conditional control transfer.
        IsUncondControl,	///< Unconditional control transfer.
        IsCall,			///< Subroutine call.
        IsReturn,		///< Subroutine return.

        IsThreadSync,	///< Thread synchronization operation.

        IsSerializing,	///< Serializes pipeline: won't execute until all
                        /// older instructions have committed.
        IsMemBarrier,	///< Is a memory barrier
        IsWriteBarrier,	///< Is a write barrier

        IsNonSpeculative, ///< Should not be executed speculatively

        NumFlags
    };

    /// Flag values for this instruction.
    std::bitset<NumFlags> flags;

    /// See opClass().
    OpClass _opClass;

    /// See numSrcRegs().
    int8_t _numSrcRegs;

    /// See numDestRegs().
    int8_t _numDestRegs;

    /// The following are used to track physical register usage
    /// for machines with separate int & FP reg files.
    //@{
    int8_t _numFPDestRegs;
    int8_t _numIntDestRegs;
    //@}

    /// Constructor.
    /// It's important to initialize everything here to a sane
    /// default, since the decoder generally only overrides
    /// the fields that are meaningful for the particular
    /// instruction.
    StaticInstBase(OpClass __opClass)
        : _opClass(__opClass), _numSrcRegs(0), _numDestRegs(0),
          _numFPDestRegs(0), _numIntDestRegs(0)
    {
    }

  public:

    /// @name Register information.
    /// The sum of numFPDestRegs() and numIntDestRegs() equals
    /// numDestRegs().  The former two functions are used to track
    /// physical register usage for machines with separate int & FP
    /// reg files.
    //@{
    /// Number of source registers.
    int8_t numSrcRegs()  const { return _numSrcRegs; }
    /// Number of destination registers.
    int8_t numDestRegs() const { return _numDestRegs; }
    /// Number of floating-point destination regs.
    int8_t numFPDestRegs()  const { return _numFPDestRegs; }
    /// Number of integer destination regs.
    int8_t numIntDestRegs() const { return _numIntDestRegs; }
    //@}

    /// @name Flag accessors.
    /// These functions are used to access the values of the various
    /// instruction property flags.  See StaticInstBase::Flags for descriptions
    /// of the individual flags.
    //@{

    bool isNop() 	  const { return flags[IsNop]; }

    bool isMemRef()    	  const { return flags[IsMemRef]; }
    bool isLoad()	  const { return flags[IsLoad]; }
    bool isStore()	  const { return flags[IsStore]; }
    bool isInstPrefetch() const { return flags[IsInstPrefetch]; }
    bool isDataPrefetch() const { return flags[IsDataPrefetch]; }
    bool isCopy()         const { return flags[IsCopy];}

    bool isInteger()	  const { return flags[IsInteger]; }
    bool isFloating()	  const { return flags[IsFloating]; }

    bool isControl()	  const { return flags[IsControl]; }
    bool isCall()	  const { return flags[IsCall]; }
    bool isReturn()	  const { return flags[IsReturn]; }
    bool isDirectCtrl()	  const { return flags[IsDirectControl]; }
    bool isIndirectCtrl() const { return flags[IsIndirectControl]; }
    bool isCondCtrl()	  const { return flags[IsCondControl]; }
    bool isUncondCtrl()	  const { return flags[IsUncondControl]; }

    bool isThreadSync()   const { return flags[IsThreadSync]; }
    bool isSerializing()  const { return flags[IsSerializing]; }
    bool isMemBarrier()   const { return flags[IsMemBarrier]; }
    bool isWriteBarrier() const { return flags[IsWriteBarrier]; }
    bool isNonSpeculative() const { return flags[IsNonSpeculative]; }
    //@}

    /// Operation class.  Used to select appropriate function unit in issue.
    OpClass opClass()     const { return _opClass; }
};


// forward declaration
template <class ISA>
class StaticInstPtr;

/**
 * Generic yet ISA-dependent static instruction class.
 *
 * This class builds on StaticInstBase, defining fields and interfaces
 * that are generic across all ISAs but that differ in details
 * according to the specific ISA being used.
 */
template <class ISA>
class StaticInst : public StaticInstBase
{
  public:

    /// Binary machine instruction type.
    typedef typename ISA::MachInst MachInst;
    /// Memory address type.
    typedef typename ISA::Addr	   Addr;
    /// Logical register index type.
    typedef typename ISA::RegIndex RegIndex;

    enum {
        MaxInstSrcRegs = ISA::MaxInstSrcRegs,	//< Max source regs
        MaxInstDestRegs = ISA::MaxInstDestRegs,	//< Max dest regs
    };


    /// Return logical index (architectural reg num) of i'th destination reg.
    /// Only the entries from 0 through numDestRegs()-1 are valid.
    RegIndex destRegIdx(int i) const { return _destRegIdx[i]; }

    /// Return logical index (architectural reg num) of i'th source reg.
    /// Only the entries from 0 through numSrcRegs()-1 are valid.
    RegIndex srcRegIdx(int i)  const { return _srcRegIdx[i]; }

    /// Pointer to a statically allocated "null" instruction object.
    /// Used to give eaCompInst() and memAccInst() something to return
    /// when called on non-memory instructions.
    static StaticInstPtr<ISA> nullStaticInstPtr;

    /**
     * Memory references only: returns "fake" instruction representing
     * the effective address part of the memory operation.  Used to
     * obtain the dependence info (numSrcRegs and srcRegIdx[]) for
     * just the EA computation.
     */
    virtual const
    StaticInstPtr<ISA> &eaCompInst() const { return nullStaticInstPtr; }

    /**
     * Memory references only: returns "fake" instruction representing
     * the memory access part of the memory operation.  Used to
     * obtain the dependence info (numSrcRegs and srcRegIdx[]) for
     * just the memory access (not the EA computation).
     */
    virtual const
    StaticInstPtr<ISA> &memAccInst() const { return nullStaticInstPtr; }

    /// The binary machine instruction.
    const MachInst machInst;

  protected:

    /// See destRegIdx().
    RegIndex _destRegIdx[MaxInstDestRegs];
    /// See srcRegIdx().
    RegIndex _srcRegIdx[MaxInstSrcRegs];

    /**
     * Base mnemonic (e.g., "add").  Used by generateDisassembly()
     * methods.  Also useful to readily identify instructions from
     * within the debugger when #cachedDisassembly has not been
     * initialized.
     */
    const char *mnemonic;

    /**
     * String representation of disassembly (lazily evaluated via
     * disassemble()).
     */
    std::string *cachedDisassembly;

    /**
     * Internal function to generate disassembly string.
     */
    virtual std::string generateDisassembly(Addr pc,
                                            const SymbolTable *symtab) = 0;

    /// Constructor.
    StaticInst(const char *_mnemonic, MachInst _machInst, OpClass __opClass)
        : StaticInstBase(__opClass),
          machInst(_machInst), mnemonic(_mnemonic), cachedDisassembly(0)
    {
    }

  public:

    virtual ~StaticInst()
    {
        if (cachedDisassembly)
            delete cachedDisassembly;
    }

    /**
     * Execute this instruction under SimpleCPU model.
     */
    virtual Fault execute(SimpleCPU *xc, Trace::InstRecord *traceData) = 0;

    /**
     * Execute this instruction under FastCPU model.
     */
    virtual Fault execute(FastCPU *xc, Trace::InstRecord *traceData) = 0;

    /**
     * Execute this instruction under detailed FullCPU model.
     */
    virtual Fault execute(DynInst *xc, Trace::InstRecord *traceData) = 0;

    /**
     * Return the target address for a PC-relative branch.
     * Invalid if not a PC-relative branch (i.e. isDirectCtrl()
     * should be true).
     */
    virtual Addr branchTarget(Addr branchPC) const
    {
        panic("StaticInst::branchTarget() called on instruction "
              "that is not a PC-relative branch.");
    }

    /**
     * Return the target address for an indirect branch (jump).  The
     * register value is read from the supplied execution context, so
     * the result is valid only if the execution context is about to
     * execute the branch in question.  Invalid if not an indirect
     * branch (i.e. isIndirectCtrl() should be true).
     */
    virtual Addr branchTarget(ExecContext *xc) const
    {
        panic("StaticInst::branchTarget() called on instruction "
              "that is not an indirect branch.");
    }

    /**
     * Return true if the instruction is a control transfer, and if so,
     * return the target address as well.
     */
    bool hasBranchTarget(Addr pc, ExecContext *xc, Addr &tgt);

    /**
     * Return string representation of disassembled instruction.
     * The default version of this function will call the internal
     * virtual generateDisassembly() function to get the string,
     * then cache it in #cachedDisassembly.  If the disassembly
     * should not be cached, this function should be overridden directly.
     */
    virtual const std::string &disassemble(Addr pc,
                                           const SymbolTable *symtab = 0)
    {
        if (!cachedDisassembly)
            cachedDisassembly =
                new std::string(generateDisassembly(pc, symtab));

        return *cachedDisassembly;
    }

    /// Decoded instruction cache type.
    /// For now we're using a generic hash_map; this seems to work
    /// pretty well.
    typedef m5::hash_map<MachInst, StaticInstPtr<ISA> > DecodeCache;

    /// A cache of decoded instruction objects.
    static DecodeCache decodeCache;

    /**
     * Dump some basic stats on the decode cache hash map.
     * Only gets called if DECODE_CACHE_HASH_STATS is defined.
     */
    static void dumpDecodeCacheStats();

    /// Decode a machine instruction.
    /// @param mach_inst The binary instruction to decode.
    /// @retval A pointer to the corresponding StaticInst object.
    static
    StaticInstPtr<ISA> decode(MachInst mach_inst)
    {
#ifdef DECODE_CACHE_HASH_STATS
        // Simple stats on decode hash_map.  Turns out the default
        // hash function is as good as anything I could come up with.
        const int dump_every_n = 10000000;
        static int decodes_til_dump = dump_every_n;

        if (--decodes_til_dump == 0) {
            dumpDecodeCacheStats();
            decodes_til_dump = dump_every_n;
        }
#endif

        typename DecodeCache::iterator iter = decodeCache.find(mach_inst);
        if (iter != decodeCache.end()) {
            return iter->second;
        }

        StaticInstPtr<ISA> si = ISA::decodeInst(mach_inst);
        decodeCache[mach_inst] = si;
        return si;
    }
};

typedef RefCountingPtr<StaticInstBase> StaticInstBasePtr;

/// Reference-counted pointer to a StaticInst object.
/// This type should be used instead of "StaticInst<ISA> *" so that
/// StaticInst objects can be properly reference-counted.
template <class ISA>
class StaticInstPtr : public RefCountingPtr<StaticInst<ISA> >
{
  public:
    /// Constructor.
    StaticInstPtr()
        : RefCountingPtr<StaticInst<ISA> >()
    {
    }

    /// Conversion from "StaticInst<ISA> *".
    StaticInstPtr(StaticInst<ISA> *p)
        : RefCountingPtr<StaticInst<ISA> >(p)
    {
    }

    /// Copy constructor.
    StaticInstPtr(const StaticInstPtr &r)
        : RefCountingPtr<StaticInst<ISA> >(r)
    {
    }

    /// Construct directly from machine instruction.
    /// Calls StaticInst<ISA>::decode().
    StaticInstPtr(typename ISA::MachInst mach_inst)
        : RefCountingPtr<StaticInst<ISA> >(StaticInst<ISA>::decode(mach_inst))
    {
    }

    /// Convert to pointer to StaticInstBase class.
    operator const StaticInstBasePtr()
    {
        return get();
    }
};

#endif // __STATIC_INST_HH__