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29 #ifndef __STATIC_INST_HH__
30 #define __STATIC_INST_HH__
35 #include "sim/host.hh"
36 #include "base/hashmap.hh"
37 #include "base/refcnt.hh"
39 #include "cpu/full_cpu/op_class.hh"
40 #include "targetarch/isa_traits.hh"
42 // forward declarations
44 class SpecExecContext;
55 * Base, ISA-independent static instruction class.
57 * The main component of this class is the vector of flags and the
58 * associated methods for reading them. Any object that can rely
59 * solely on these flags can process instructions without being
60 * recompiled for multiple ISAs.
62 class StaticInstBase : public RefCounted
66 /// Set of boolean static instruction properties.
69 /// - The IsInteger and IsFloating flags are based on the class of
70 /// registers accessed by the instruction. Although most
71 /// instructions will have exactly one of these two flags set, it
72 /// is possible for an instruction to have neither (e.g., direct
73 /// unconditional branches, memory barriers) or both (e.g., an
74 /// FP/int conversion).
75 /// - If IsMemRef is set, then exactly one of IsLoad or IsStore
76 /// will be set. Prefetches are marked as IsLoad, even if they
77 /// prefetch exclusive copies.
78 /// - If IsControl is set, then exactly one of IsDirectControl or
79 /// IsIndirect Control will be set, and exactly one of
80 /// IsCondControl or IsUncondControl will be set.
81 /// - IsSerializing, IsMemBarrier, and IsWriteBarrier are
82 /// implemented as flags since in the current model there's no
83 /// other way for instructions to inject behavior into the
84 /// pipeline outside of fetch. Once we go to an exec-in-exec CPU
85 /// model we should be able to get rid of these flags and
86 /// implement this behavior via the execute() methods.
89 IsNop, ///< Is a no-op (no effect at all).
91 IsInteger, ///< References integer regs.
92 IsFloating, ///< References FP regs.
94 IsMemRef, ///< References memory (load, store, or prefetch).
95 IsLoad, ///< Reads from memory (load or prefetch).
96 IsStore, ///< Writes to memory.
97 IsInstPrefetch, ///< Instruction-cache prefetch.
98 IsDataPrefetch, ///< Data-cache prefetch.
100 IsControl, ///< Control transfer instruction.
101 IsDirectControl, ///< PC relative control transfer.
102 IsIndirectControl, ///< Register indirect control transfer.
103 IsCondControl, ///< Conditional control transfer.
104 IsUncondControl, ///< Unconditional control transfer.
105 IsCall, ///< Subroutine call.
106 IsReturn, ///< Subroutine return.
108 IsThreadSync, ///< Thread synchronization operation.
110 IsSerializing, ///< Serializes pipeline: won't until all
111 /// older instructions have committed.
112 IsMemBarrier, ///< Is a memory barrier
113 IsWriteBarrier, ///< Is a write barrier
118 /// Flag values for this instruction.
119 std::bitset<NumFlags> flags;
124 /// See numSrcRegs().
127 /// See numDestRegs().
130 /// The following are used to track physical register usage
131 /// for machines with separate int & FP reg files.
133 int8_t _numFPDestRegs;
134 int8_t _numIntDestRegs;
138 /// It's important to initialize everything here to a sane
139 /// default, since the decoder generally only overrides
140 /// the fields that are meaningful for the particular
142 StaticInstBase(OpClass __opClass)
143 : _opClass(__opClass), _numSrcRegs(0), _numDestRegs(0),
144 _numFPDestRegs(0), _numIntDestRegs(0)
150 /// @name Register information.
151 /// The sum of numFPDestRegs() and numIntDestRegs() equals
152 /// numDestRegs(). The former two functions are used to track
153 /// physical register usage for machines with separate int & FP
156 /// Number of source registers.
157 int8_t numSrcRegs() const { return _numSrcRegs; }
158 /// Number of destination registers.
159 int8_t numDestRegs() const { return _numDestRegs; }
160 /// Number of floating-point destination regs.
161 int8_t numFPDestRegs() const { return _numFPDestRegs; }
162 /// Number of integer destination regs.
163 int8_t numIntDestRegs() const { return _numIntDestRegs; }
166 /// @name Flag accessors.
167 /// These functions are used to access the values of the various
168 /// instruction property flags. See StaticInstBase::Flags for descriptions
169 /// of the individual flags.
172 bool isNop() const { return flags[IsNop]; }
174 bool isMemRef() const { return flags[IsMemRef]; }
175 bool isLoad() const { return flags[IsLoad]; }
176 bool isStore() const { return flags[IsStore]; }
177 bool isInstPrefetch() const { return flags[IsInstPrefetch]; }
178 bool isDataPrefetch() const { return flags[IsDataPrefetch]; }
180 bool isInteger() const { return flags[IsInteger]; }
181 bool isFloating() const { return flags[IsFloating]; }
183 bool isControl() const { return flags[IsControl]; }
184 bool isCall() const { return flags[IsCall]; }
185 bool isReturn() const { return flags[IsReturn]; }
186 bool isDirectCtrl() const { return flags[IsDirectControl]; }
187 bool isIndirectCtrl() const { return flags[IsIndirectControl]; }
188 bool isCondCtrl() const { return flags[IsCondControl]; }
189 bool isUncondCtrl() const { return flags[IsUncondControl]; }
191 bool isThreadSync() const { return flags[IsThreadSync]; }
192 bool isSerializing() const { return flags[IsSerializing]; }
193 bool isMemBarrier() const { return flags[IsMemBarrier]; }
194 bool isWriteBarrier() const { return flags[IsWriteBarrier]; }
197 /// Operation class. Used to select appropriate function unit in issue.
198 OpClass opClass() const { return _opClass; }
202 // forward declaration
207 * Generic yet ISA-dependent static instruction class.
209 * This class builds on StaticInstBase, defining fields and interfaces
210 * that are generic across all ISAs but that differ in details
211 * according to the specific ISA being used.
214 class StaticInst : public StaticInstBase
218 /// Binary machine instruction type.
219 typedef typename ISA::MachInst MachInst;
220 /// Memory address type.
221 typedef typename ISA::Addr Addr;
222 /// Logical register index type.
223 typedef typename ISA::RegIndex RegIndex;
226 MaxInstSrcRegs = ISA::MaxInstSrcRegs, //< Max source regs
227 MaxInstDestRegs = ISA::MaxInstDestRegs, //< Max dest regs
231 /// Return logical index (architectural reg num) of i'th destination reg.
232 /// Only the entries from 0 through numDestRegs()-1 are valid.
233 RegIndex destRegIdx(int i) const { return _destRegIdx[i]; }
235 /// Return logical index (architectural reg num) of i'th source reg.
236 /// Only the entries from 0 through numSrcRegs()-1 are valid.
237 RegIndex srcRegIdx(int i) const { return _srcRegIdx[i]; }
239 /// Pointer to a statically allocated "null" instruction object.
240 /// Used to give eaCompInst() and memAccInst() something to return
241 /// when called on non-memory instructions.
242 static StaticInstPtr<ISA> nullStaticInstPtr;
245 * Memory references only: returns "fake" instruction representing
246 * the effective address part of the memory operation. Used to
247 * obtain the dependence info (numSrcRegs and srcRegIdx[]) for
248 * just the EA computation.
250 virtual StaticInstPtr<ISA> eaCompInst() { return nullStaticInstPtr; }
253 * Memory references only: returns "fake" instruction representing
254 * the memory access part of the memory operation. Used to
255 * obtain the dependence info (numSrcRegs and srcRegIdx[]) for
256 * just the memory access (not the EA computation).
258 virtual StaticInstPtr<ISA> memAccInst() { return nullStaticInstPtr; }
260 /// The binary machine instruction.
261 const MachInst machInst;
265 /// See destRegIdx().
266 RegIndex _destRegIdx[MaxInstDestRegs];
268 RegIndex _srcRegIdx[MaxInstSrcRegs];
271 * Base mnemonic (e.g., "add"). Used by generateDisassembly()
272 * methods. Also useful to readily identify instructions from
273 * within the debugger when #cachedDisassembly has not been
276 const char *mnemonic;
279 * String representation of disassembly (lazily evaluated via
282 std::string *cachedDisassembly;
285 * Internal function to generate disassembly string.
287 virtual std::string generateDisassembly(Addr pc,
288 const SymbolTable *symtab) = 0;
291 StaticInst(const char *_mnemonic, MachInst _machInst, OpClass __opClass)
292 : StaticInstBase(__opClass),
293 machInst(_machInst), mnemonic(_mnemonic), cachedDisassembly(0)
299 virtual ~StaticInst()
301 if (cachedDisassembly)
302 delete cachedDisassembly;
306 * Execute this instruction under SimpleCPU model.
308 virtual Fault execute(SimpleCPU *cpu, ExecContext *xc,
309 Trace::InstRecord *traceData) = 0;
312 * Execute this instruction under detailed FullCPU model.
314 virtual Fault execute(FullCPU *cpu, SpecExecContext *xc, DynInst *dynInst,
315 Trace::InstRecord *traceData) = 0;
318 * Return the target address for a PC-relative branch.
319 * Invalid if not a PC-relative branch (i.e. isDirectCtrl()
322 virtual Addr branchTarget(Addr branchPC) const
324 panic("StaticInst::branchTarget() called on instruction "
325 "that is not a PC-relative branch.");
329 * Return the target address for an indirect branch (jump). The
330 * register value is read from the supplied execution context, so
331 * the result is valid only if the execution context is about to
332 * execute the branch in question. Invalid if not an indirect
333 * branch (i.e. isIndirectCtrl() should be true).
335 virtual Addr branchTarget(ExecContext *xc) const
337 panic("StaticInst::branchTarget() called on instruction "
338 "that is not an indirect branch.");
342 * Return true if the instruction is a control transfer, and if so,
343 * return the target address as well.
345 bool hasBranchTarget(Addr pc, ExecContext *xc, Addr &tgt);
348 * Return string representation of disassembled instruction.
349 * The default version of this function will call the internal
350 * virtual generateDisassembly() function to get the string,
351 * then cache it in #cachedDisassembly. If the disassembly
352 * should not be cached, this function should be overridden directly.
354 virtual const std::string &disassemble(Addr pc,
355 const SymbolTable *symtab = 0)
357 if (!cachedDisassembly)
359 new std::string(generateDisassembly(pc, symtab));
361 return *cachedDisassembly;
364 /// Decoded instruction cache type.
365 /// For now we're using a generic hash_map; this seems to work
367 typedef m5::hash_map<MachInst, StaticInstPtr<ISA> > DecodeCache;
369 /// A cache of decoded instruction objects.
370 static DecodeCache decodeCache;
373 * Dump some basic stats on the decode cache hash map.
374 * Only gets called if DECODE_CACHE_HASH_STATS is defined.
376 static void dumpDecodeCacheStats();
378 /// Decode a machine instruction.
379 /// @param mach_inst The binary instruction to decode.
380 /// @retval A pointer to the corresponding StaticInst object.
382 StaticInstPtr<ISA> decode(MachInst mach_inst)
384 #ifdef DECODE_CACHE_HASH_STATS
385 // Simple stats on decode hash_map. Turns out the default
386 // hash function is as good as anything I could come up with.
387 const int dump_every_n = 10000000;
388 static int decodes_til_dump = dump_every_n;
390 if (--decodes_til_dump == 0) {
391 dumpDecodeCacheStats();
392 decodes_til_dump = dump_every_n;
396 typename DecodeCache::iterator iter = decodeCache.find(mach_inst);
397 if (iter != decodeCache.end()) {
401 StaticInstPtr<ISA> si = ISA::decodeInst(mach_inst);
402 decodeCache[mach_inst] = si;
407 typedef RefCountingPtr<StaticInstBase> StaticInstBasePtr;
409 /// Reference-counted pointer to a StaticInst object.
410 /// This type should be used instead of "StaticInst<ISA> *" so that
411 /// StaticInst objects can be properly reference-counted.
413 class StaticInstPtr : public RefCountingPtr<StaticInst<ISA> >
418 : RefCountingPtr<StaticInst<ISA> >()
422 /// Conversion from "StaticInst<ISA> *".
423 StaticInstPtr(StaticInst<ISA> *p)
424 : RefCountingPtr<StaticInst<ISA> >(p)
428 /// Copy constructor.
429 StaticInstPtr(const StaticInstPtr &r)
430 : RefCountingPtr<StaticInst<ISA> >(r)
434 /// Construct directly from machine instruction.
435 /// Calls StaticInst<ISA>::decode().
436 StaticInstPtr(typename ISA::MachInst mach_inst)
437 : RefCountingPtr<StaticInst<ISA> >(StaticInst<ISA>::decode(mach_inst))
441 /// Convert to pointer to StaticInstBase class.
442 operator const StaticInstBasePtr()
448 #endif // __STATIC_INST_HH__