src/cpu/static_inst.hh

   1 /*
   2  * Copyright (c) 2003-2005 The Regents of The University of Michigan
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are
   7  * met: redistributions of source code must retain the above copyright
   8  * notice, this list of conditions and the following disclaimer;
   9  * redistributions in binary form must reproduce the above copyright
  10  * notice, this list of conditions and the following disclaimer in the
  11  * documentation and/or other materials provided with the distribution;
  12  * neither the name of the copyright holders nor the names of its
  13  * contributors may be used to endorse or promote products derived from
  14  * this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  17  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  18  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  19  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  20  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  21  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  22  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  26  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  *
  28  * Authors: Steve Reinhardt
  29  */
  30
  31 #ifndef __CPU_STATIC_INST_HH__
  32 #define __CPU_STATIC_INST_HH__
  33
  34 #include <bitset>
  35 #include <string>
  36
  37 #include "base/bitfield.hh"
  38 #include "base/hashmap.hh"
  39 #include "base/misc.hh"
  40 #include "base/refcnt.hh"
  41 #include "cpu/op_class.hh"
  42 #include "cpu/o3/dyn_inst.hh"
  43 #include "sim/host.hh"
  44 #include "arch/isa_traits.hh"
  45
  46 // forward declarations
  47 struct AlphaSimpleImpl;
  48 struct OzoneImpl;
  49 struct SimpleImpl;
  50 class ThreadContext;
  51 class DynInst;
  52 class Packet;
  53
  54 template <class Impl>
  55 class OzoneDynInst;
  56
  57 class CheckerCPU;
  58 class FastCPU;
  59 class AtomicSimpleCPU;
  60 class TimingSimpleCPU;
  61 class InorderCPU;
  62 class SymbolTable;
  63
  64 namespace Trace {
  65     class InstRecord;
  66 }
  67
  68 /**
  69  * Base, ISA-independent static instruction class.
  70  *
  71  * The main component of this class is the vector of flags and the
  72  * associated methods for reading them.  Any object that can rely
  73  * solely on these flags can process instructions without being
  74  * recompiled for multiple ISAs.
  75  */
  76 class StaticInstBase : public RefCounted
  77 {
  78   protected:
  79
  80     /// Set of boolean static instruction properties.
  81     ///
  82     /// Notes:
  83     /// - The IsInteger and IsFloating flags are based on the class of
  84     /// registers accessed by the instruction.  Although most
  85     /// instructions will have exactly one of these two flags set, it
  86     /// is possible for an instruction to have neither (e.g., direct
  87     /// unconditional branches, memory barriers) or both (e.g., an
  88     /// FP/int conversion).
  89     /// - If IsMemRef is set, then exactly one of IsLoad or IsStore
  90     /// will be set.
  91     /// - If IsControl is set, then exactly one of IsDirectControl or
  92     /// IsIndirect Control will be set, and exactly one of
  93     /// IsCondControl or IsUncondControl will be set.
  94     /// - IsSerializing, IsMemBarrier, and IsWriteBarrier are
  95     /// implemented as flags since in the current model there's no
  96     /// other way for instructions to inject behavior into the
  97     /// pipeline outside of fetch.  Once we go to an exec-in-exec CPU
  98     /// model we should be able to get rid of these flags and
  99     /// implement this behavior via the execute() methods.
 100     ///
 101     enum Flags {
 102         IsNop,          ///< Is a no-op (no effect at all).
 103
 104         IsInteger,      ///< References integer regs.
 105         IsFloating,     ///< References FP regs.
 106
 107         IsMemRef,       ///< References memory (load, store, or prefetch).
 108         IsLoad,         ///< Reads from memory (load or prefetch).
 109         IsStore,        ///< Writes to memory.
 110         IsStoreConditional,    ///< Store conditional instruction.
 111         IsInstPrefetch, ///< Instruction-cache prefetch.
 112         IsDataPrefetch, ///< Data-cache prefetch.
 113         IsCopy,         ///< Fast Cache block copy
 114
 115         IsControl,              ///< Control transfer instruction.
 116         IsDirectControl,        ///< PC relative control transfer.
 117         IsIndirectControl,      ///< Register indirect control transfer.
 118         IsCondControl,          ///< Conditional control transfer.
 119         IsUncondControl,        ///< Unconditional control transfer.
 120         IsCall,                 ///< Subroutine call.
 121         IsReturn,               ///< Subroutine return.
 122
 123         IsCondDelaySlot,///< Conditional Delay-Slot Instruction
 124
 125         IsThreadSync,   ///< Thread synchronization operation.
 126
 127         IsSerializing,  ///< Serializes pipeline: won't execute until all
 128                         /// older instructions have committed.
 129         IsSerializeBefore,
 130         IsSerializeAfter,
 131         IsMemBarrier,   ///< Is a memory barrier
 132         IsWriteBarrier, ///< Is a write barrier
 133
 134         IsNonSpeculative, ///< Should not be executed speculatively
 135         IsQuiesce,      ///< Is a quiesce instruction
 136
 137         IsIprAccess,    ///< Accesses IPRs
 138         IsUnverifiable, ///< Can't be verified by a checker
 139
 140         NumFlags
 141     };
 142
 143     /// Flag values for this instruction.
 144     std::bitset<NumFlags> flags;
 145
 146     /// See opClass().
 147     OpClass _opClass;
 148
 149     /// See numSrcRegs().
 150     int8_t _numSrcRegs;
 151
 152     /// See numDestRegs().
 153     int8_t _numDestRegs;
 154
 155     /// The following are used to track physical register usage
 156     /// for machines with separate int & FP reg files.
 157     //@{
 158     int8_t _numFPDestRegs;
 159     int8_t _numIntDestRegs;
 160     //@}
 161
 162     /// Constructor.
 163     /// It's important to initialize everything here to a sane
 164     /// default, since the decoder generally only overrides
 165     /// the fields that are meaningful for the particular
 166     /// instruction.
 167     StaticInstBase(OpClass __opClass)
 168         : _opClass(__opClass), _numSrcRegs(0), _numDestRegs(0),
 169           _numFPDestRegs(0), _numIntDestRegs(0)
 170     {
 171     }
 172
 173   public:
 174
 175     /// @name Register information.
 176     /// The sum of numFPDestRegs() and numIntDestRegs() equals
 177     /// numDestRegs().  The former two functions are used to track
 178     /// physical register usage for machines with separate int & FP
 179     /// reg files.
 180     //@{
 181     /// Number of source registers.
 182     int8_t numSrcRegs()  const { return _numSrcRegs; }
 183     /// Number of destination registers.
 184     int8_t numDestRegs() const { return _numDestRegs; }
 185     /// Number of floating-point destination regs.
 186     int8_t numFPDestRegs()  const { return _numFPDestRegs; }
 187     /// Number of integer destination regs.
 188     int8_t numIntDestRegs() const { return _numIntDestRegs; }
 189     //@}
 190
 191     /// @name Flag accessors.
 192     /// These functions are used to access the values of the various
 193     /// instruction property flags.  See StaticInstBase::Flags for descriptions
 194     /// of the individual flags.
 195     //@{
 196
 197     bool isNop()          const { return flags[IsNop]; }
 198
 199     bool isMemRef()       const { return flags[IsMemRef]; }
 200     bool isLoad()         const { return flags[IsLoad]; }
 201     bool isStore()        const { return flags[IsStore]; }
 202     bool isStoreConditional()     const { return flags[IsStoreConditional]; }
 203     bool isInstPrefetch() const { return flags[IsInstPrefetch]; }
 204     bool isDataPrefetch() const { return flags[IsDataPrefetch]; }
 205     bool isCopy()         const { return flags[IsCopy];}
 206
 207     bool isInteger()      const { return flags[IsInteger]; }
 208     bool isFloating()     const { return flags[IsFloating]; }
 209
 210     bool isControl()      const { return flags[IsControl]; }
 211     bool isCall()         const { return flags[IsCall]; }
 212     bool isReturn()       const { return flags[IsReturn]; }
 213     bool isDirectCtrl()   const { return flags[IsDirectControl]; }
 214     bool isIndirectCtrl() const { return flags[IsIndirectControl]; }
 215     bool isCondCtrl()     const { return flags[IsCondControl]; }
 216     bool isUncondCtrl()   const { return flags[IsUncondControl]; }
 217
 218     bool isThreadSync()   const { return flags[IsThreadSync]; }
 219     bool isSerializing()  const { return flags[IsSerializing] ||
 220                                       flags[IsSerializeBefore] ||
 221                                       flags[IsSerializeAfter]; }
 222     bool isSerializeBefore() const { return flags[IsSerializeBefore]; }
 223     bool isSerializeAfter() const { return flags[IsSerializeAfter]; }
 224     bool isMemBarrier()   const { return flags[IsMemBarrier]; }
 225     bool isWriteBarrier() const { return flags[IsWriteBarrier]; }
 226     bool isNonSpeculative() const { return flags[IsNonSpeculative]; }
 227     bool isQuiesce() const { return flags[IsQuiesce]; }
 228     bool isIprAccess() const { return flags[IsIprAccess]; }
 229     bool isUnverifiable() const { return flags[IsUnverifiable]; }
 230     //@}
 231
 232     /// Operation class.  Used to select appropriate function unit in issue.
 233     OpClass opClass()     const { return _opClass; }
 234 };
 235
 236
 237 // forward declaration
 238 class StaticInstPtr;
 239
 240 /**
 241  * Generic yet ISA-dependent static instruction class.
 242  *
 243  * This class builds on StaticInstBase, defining fields and interfaces
 244  * that are generic across all ISAs but that differ in details
 245  * according to the specific ISA being used.
 246  */
 247 class StaticInst : public StaticInstBase
 248 {
 249   public:
 250
 251     /// Binary machine instruction type.
 252     typedef TheISA::MachInst MachInst;
 253     /// Binary extended machine instruction type.
 254     typedef TheISA::ExtMachInst ExtMachInst;
 255     /// Logical register index type.
 256     typedef TheISA::RegIndex RegIndex;
 257
 258     enum {
 259         MaxInstSrcRegs = TheISA::MaxInstSrcRegs,        //< Max source regs
 260         MaxInstDestRegs = TheISA::MaxInstDestRegs,      //< Max dest regs
 261     };
 262
 263
 264     /// Return logical index (architectural reg num) of i'th destination reg.
 265     /// Only the entries from 0 through numDestRegs()-1 are valid.
 266     RegIndex destRegIdx(int i) const { return _destRegIdx[i]; }
 267
 268     /// Return logical index (architectural reg num) of i'th source reg.
 269     /// Only the entries from 0 through numSrcRegs()-1 are valid.
 270     RegIndex srcRegIdx(int i)  const { return _srcRegIdx[i]; }
 271
 272     /// Pointer to a statically allocated "null" instruction object.
 273     /// Used to give eaCompInst() and memAccInst() something to return
 274     /// when called on non-memory instructions.
 275     static StaticInstPtr nullStaticInstPtr;
 276
 277     /**
 278      * Memory references only: returns "fake" instruction representing
 279      * the effective address part of the memory operation.  Used to
 280      * obtain the dependence info (numSrcRegs and srcRegIdx[]) for
 281      * just the EA computation.
 282      */
 283     virtual const
 284     StaticInstPtr &eaCompInst() const { return nullStaticInstPtr; }
 285
 286     /**
 287      * Memory references only: returns "fake" instruction representing
 288      * the memory access part of the memory operation.  Used to
 289      * obtain the dependence info (numSrcRegs and srcRegIdx[]) for
 290      * just the memory access (not the EA computation).
 291      */
 292     virtual const
 293     StaticInstPtr &memAccInst() const { return nullStaticInstPtr; }
 294
 295     /// The binary machine instruction.
 296     const ExtMachInst machInst;
 297
 298   protected:
 299
 300     /// See destRegIdx().
 301     RegIndex _destRegIdx[MaxInstDestRegs];
 302     /// See srcRegIdx().
 303     RegIndex _srcRegIdx[MaxInstSrcRegs];
 304
 305     /**
 306      * Base mnemonic (e.g., "add").  Used by generateDisassembly()
 307      * methods.  Also useful to readily identify instructions from
 308      * within the debugger when #cachedDisassembly has not been
 309      * initialized.
 310      */
 311     const char *mnemonic;
 312
 313     /**
 314      * String representation of disassembly (lazily evaluated via
 315      * disassemble()).
 316      */
 317     mutable std::string *cachedDisassembly;
 318
 319     /**
 320      * Internal function to generate disassembly string.
 321      */
 322     virtual std::string
 323     generateDisassembly(Addr pc, const SymbolTable *symtab) const = 0;
 324
 325     /// Constructor.
 326     StaticInst(const char *_mnemonic, ExtMachInst _machInst, OpClass __opClass)
 327         : StaticInstBase(__opClass),
 328           machInst(_machInst), mnemonic(_mnemonic), cachedDisassembly(0)
 329     {
 330     }
 331
 332   public:
 333
 334     virtual ~StaticInst()
 335     {
 336         if (cachedDisassembly)
 337             delete cachedDisassembly;
 338     }
 339
 340 /**
 341  * The execute() signatures are auto-generated by scons based on the
 342  * set of CPU models we are compiling in today.
 343  */
 344 #include "cpu/static_inst_exec_sigs.hh"
 345
 346     /**
 347      * Return the target address for a PC-relative branch.
 348      * Invalid if not a PC-relative branch (i.e. isDirectCtrl()
 349      * should be true).
 350      */
 351     virtual Addr branchTarget(Addr branchPC) const
 352     {
 353         panic("StaticInst::branchTarget() called on instruction "
 354               "that is not a PC-relative branch.");
 355     }
 356
 357     /**
 358      * Return the target address for an indirect branch (jump).  The
 359      * register value is read from the supplied thread context, so
 360      * the result is valid only if the thread context is about to
 361      * execute the branch in question.  Invalid if not an indirect
 362      * branch (i.e. isIndirectCtrl() should be true).
 363      */
 364     virtual Addr branchTarget(ThreadContext *tc) const
 365     {
 366         panic("StaticInst::branchTarget() called on instruction "
 367               "that is not an indirect branch.");
 368     }
 369
 370     /**
 371      * Return true if the instruction is a control transfer, and if so,
 372      * return the target address as well.
 373      */
 374     bool hasBranchTarget(Addr pc, ThreadContext *tc, Addr &tgt) const;
 375
 376     /**
 377      * Return string representation of disassembled instruction.
 378      * The default version of this function will call the internal
 379      * virtual generateDisassembly() function to get the string,
 380      * then cache it in #cachedDisassembly.  If the disassembly
 381      * should not be cached, this function should be overridden directly.
 382      */
 383     virtual const std::string &disassemble(Addr pc,
 384                                            const SymbolTable *symtab = 0) const
 385     {
 386         if (!cachedDisassembly)
 387             cachedDisassembly =
 388                 new std::string(generateDisassembly(pc, symtab));
 389
 390         return *cachedDisassembly;
 391     }
 392
 393     /// Decoded instruction cache type.
 394     /// For now we're using a generic hash_map; this seems to work
 395     /// pretty well.
 396     typedef m5::hash_map<ExtMachInst, StaticInstPtr> DecodeCache;
 397
 398     /// A cache of decoded instruction objects.
 399     static DecodeCache decodeCache;
 400
 401     /**
 402      * Dump some basic stats on the decode cache hash map.
 403      * Only gets called if DECODE_CACHE_HASH_STATS is defined.
 404      */
 405     static void dumpDecodeCacheStats();
 406
 407     /// Decode a machine instruction.
 408     /// @param mach_inst The binary instruction to decode.
 409     /// @retval A pointer to the corresponding StaticInst object.
 410     //This is defined as inline below.
 411     static StaticInstPtr decode(ExtMachInst mach_inst);
 412
 413     /// Return opcode of machine instruction
 414     uint32_t getOpcode() { return bits(machInst, 31, 26);}
 415
 416     /// Return name of machine instruction
 417     std::string getName() { return mnemonic; }
 418 };
 419
 420 typedef RefCountingPtr<StaticInstBase> StaticInstBasePtr;
 421
 422 /// Reference-counted pointer to a StaticInst object.
 423 /// This type should be used instead of "StaticInst *" so that
 424 /// StaticInst objects can be properly reference-counted.
 425 class StaticInstPtr : public RefCountingPtr<StaticInst>
 426 {
 427   public:
 428     /// Constructor.
 429     StaticInstPtr()
 430         : RefCountingPtr<StaticInst>()
 431     {
 432     }
 433
 434     /// Conversion from "StaticInst *".
 435     StaticInstPtr(StaticInst *p)
 436         : RefCountingPtr<StaticInst>(p)
 437     {
 438     }
 439
 440     /// Copy constructor.
 441     StaticInstPtr(const StaticInstPtr &r)
 442         : RefCountingPtr<StaticInst>(r)
 443     {
 444     }
 445
 446     /// Construct directly from machine instruction.
 447     /// Calls StaticInst::decode().
 448     StaticInstPtr(TheISA::ExtMachInst mach_inst)
 449         : RefCountingPtr<StaticInst>(StaticInst::decode(mach_inst))
 450     {
 451     }
 452
 453     /// Convert to pointer to StaticInstBase class.
 454     operator const StaticInstBasePtr()
 455     {
 456         return this->get();
 457     }
 458 };
 459
 460 inline StaticInstPtr
 461 StaticInst::decode(StaticInst::ExtMachInst mach_inst)
 462 {
 463 #ifdef DECODE_CACHE_HASH_STATS
 464     // Simple stats on decode hash_map.  Turns out the default
 465     // hash function is as good as anything I could come up with.
 466     const int dump_every_n = 10000000;
 467     static int decodes_til_dump = dump_every_n;
 468
 469     if (--decodes_til_dump == 0) {
 470         dumpDecodeCacheStats();
 471         decodes_til_dump = dump_every_n;
 472     }
 473 #endif
 474
 475     DecodeCache::iterator iter = decodeCache.find(mach_inst);
 476     if (iter != decodeCache.end()) {
 477         return iter->second;
 478     }
 479
 480     StaticInstPtr si = TheISA::decodeInst(mach_inst);
 481     decodeCache[mach_inst] = si;
 482     return si;
 483 }
 484
 485 #endif // __CPU_STATIC_INST_HH__