gecko/js/src/jscompartment.h

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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 * 1.1 (the "License"); you may not use this file except in compliance with
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 *
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 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
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 * The Original Code is SpiderMonkey code.
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#ifndef jscompartment_h___
#define jscompartment_h___

#include "jscntxt.h"
#include "jsgc.h"
#include "jsmath.h"
#include "jsobj.h"
#include "jsfun.h"
#include "jsgcstats.h"
#include "jsclist.h"
#include "jsxml.h"

#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable:4251) /* Silence warning about JS_FRIEND_API and data members. */
#endif

namespace js {

/* Holds the number of recording attemps for an address. */
typedef HashMap<jsbytecode*,
                size_t,
                DefaultHasher<jsbytecode*>,
                SystemAllocPolicy> RecordAttemptMap;

/* Holds the profile data for loops. */
typedef HashMap<jsbytecode*,
                LoopProfile*,
                DefaultHasher<jsbytecode*>,
                SystemAllocPolicy> LoopProfileMap;

class Oracle;

typedef HashSet<JSScript *,
                DefaultHasher<JSScript *>,
                SystemAllocPolicy> TracedScriptSet;

/*
 * Trace monitor. Every JSCompartment has an associated trace monitor
 * that keeps track of loop frequencies for all JavaScript code loaded
 * into that runtime.
 */
struct TraceMonitor {
    /*
     * The context currently executing JIT-compiled code in this compartment, or
     * NULL if none. Among other things, this can in certain cases prevent
     * last-ditch GC and suppress calls to JS_ReportOutOfMemory.
     *
     * !tracecx && !recorder: not on trace
     * !tracecx && recorder: recording
     * tracecx && !recorder: executing a trace
     * tracecx && recorder: executing inner loop, recording outer loop
     */
    JSContext               *tracecx;

    /* Counts the number of iterations run by the currently executing trace. */
    unsigned                iterationCounter;

    /*
     * Cached storage to use when executing on trace. While we may enter nested
     * traces, we always reuse the outer trace's storage, so never need more
     * than of these.
     */
    TraceNativeStorage      *storage;

    /*
     * There are 4 allocators here.  This might seem like overkill, but they
     * have different lifecycles, and by keeping them separate we keep the
     * amount of retained memory down significantly.  They are flushed (ie.
     * all the allocated memory is freed) periodically.
     *
     * - dataAlloc has the lifecycle of the monitor.  It's flushed only when
     *   the monitor is flushed.  It's used for fragments.
     *
     * - traceAlloc has the same flush lifecycle as the dataAlloc, but it is
     *   also *marked* when a recording starts and rewinds to the mark point
     *   if recording aborts.  So you can put things in it that are only
     *   reachable on a successful record/compile cycle like GuardRecords and
     *   SideExits.
     *
     * - tempAlloc is flushed after each recording, successful or not.  It's
     *   used to store LIR code and for all other elements in the LIR
     *   pipeline.
     *
     * - codeAlloc has the same lifetime as dataAlloc, but its API is
     *   different (CodeAlloc vs. VMAllocator).  It's used for native code.
     *   It's also a good idea to keep code and data separate to avoid I-cache
     *   vs. D-cache issues.
     */
    VMAllocator*            dataAlloc;
    VMAllocator*            traceAlloc;
    VMAllocator*            tempAlloc;
    nanojit::CodeAlloc*     codeAlloc;
    nanojit::Assembler*     assembler;
    FrameInfoCache*         frameCache;

    /* This gets incremented every time the monitor is flushed. */
    uintN                   flushEpoch;

    Oracle*                 oracle;
    TraceRecorder*          recorder;

    /* If we are profiling a loop, this tracks the current profile. Otherwise NULL. */
    LoopProfile*            profile;

    GlobalState             globalStates[MONITOR_N_GLOBAL_STATES];
    TreeFragment*           vmfragments[FRAGMENT_TABLE_SIZE];
    RecordAttemptMap*       recordAttempts;

    /* A hashtable mapping PC values to loop profiles for those loops. */
    LoopProfileMap*         loopProfiles;

    /*
     * Maximum size of the code cache before we start flushing. 1/16 of this
     * size is used as threshold for the regular expression code cache.
     */
    uint32                  maxCodeCacheBytes;

    /*
     * If nonzero, do not flush the JIT cache after a deep bail. That would
     * free JITted code pages that we will later return to. Instead, set the
     * needFlush flag so that it can be flushed later.
     */
    JSBool                  needFlush;

    /*
     * Fragment map for the regular expression compiler.
     */
    REHashMap*              reFragments;

    // Cached temporary typemap to avoid realloc'ing every time we create one.
    // This must be used in only one place at a given time. It must be cleared
    // before use.
    TypeMap*                cachedTempTypeMap;

    /* Scripts with recorded fragments. */
    TracedScriptSet         tracedScripts;

#ifdef DEBUG
    /* Fields needed for fragment/guard profiling. */
    nanojit::Seq<nanojit::Fragment*>* branches;
    uint32                  lastFragID;
    /*
     * profAlloc has a lifetime which spans exactly from js_InitJIT to
     * js_FinishJIT.
     */
    VMAllocator*            profAlloc;
    FragStatsMap*           profTab;
#endif

    bool ontrace() const {
        return !!tracecx;
    }

    /* Flush the JIT cache. */
    void flush();

    /* Sweep any cache entry pointing to dead GC things. */
    void sweep();

    bool outOfMemory() const;
};

namespace mjit {
class JaegerCompartment;
}
}

/* Number of potentially reusable scriptsToGC to search for the eval cache. */
#ifndef JS_EVAL_CACHE_SHIFT
# define JS_EVAL_CACHE_SHIFT        6
#endif
#define JS_EVAL_CACHE_SIZE          JS_BIT(JS_EVAL_CACHE_SHIFT)

#ifdef DEBUG
# define EVAL_CACHE_METER_LIST(_)   _(probe), _(hit), _(step), _(noscope)
# define identity(x)                x

struct JSEvalCacheMeter {
    uint64 EVAL_CACHE_METER_LIST(identity);
};

# undef identity
#endif

struct JS_FRIEND_API(JSCompartment) {
    JSRuntime                    *rt;
    JSPrincipals                 *principals;
    js::gc::Chunk                *chunk;

    js::gc::ArenaList            arenas[js::gc::FINALIZE_LIMIT];
    js::gc::FreeLists            freeLists;

#ifdef JS_GCMETER
    js::gc::JSGCArenaStats       compartmentStats[js::gc::FINALIZE_LIMIT];
#endif

#ifdef JS_TRACER
    /* Trace-tree JIT recorder/interpreter state. */
    js::TraceMonitor traceMonitor;
#endif

    /* Lock-free hashed lists of scripts created by eval to garbage-collect. */
    JSScript                     *scriptsToGC[JS_EVAL_CACHE_SIZE];

#ifdef DEBUG
    JSEvalCacheMeter    evalCacheMeter;
#endif

    void                         *data;
    bool                         marked;
    bool                         active;  // GC flag, whether there are active frames
    js::WrapperMap               crossCompartmentWrappers;

#ifdef JS_METHODJIT
    js::mjit::JaegerCompartment  *jaegerCompartment;
#endif

    bool                         debugMode;  // true iff debug mode on
    JSCList                      scripts;    // scripts in this compartment

    /*
     * Weak references to lazily-created, well-known XML singletons.
     *
     * NB: Singleton objects must be carefully disconnected from the rest of
     * the object graph usually associated with a JSContext's global object,
     * including the set of standard class objects.  See jsxml.c for details.
     */
    JSObject                     *anynameObject;
    JSObject                     *functionNamespaceObject;

    JSCompartment(JSRuntime *cx);
    ~JSCompartment();

    bool init();

    bool wrap(JSContext *cx, js::Value *vp);
    bool wrap(JSContext *cx, JSString **strp);
    bool wrap(JSContext *cx, JSObject **objp);
    bool wrapId(JSContext *cx, jsid *idp);
    bool wrap(JSContext *cx, js::PropertyOp *op);
    bool wrap(JSContext *cx, js::PropertyDescriptor *desc);
    bool wrap(JSContext *cx, js::AutoIdVector &props);
    bool wrapException(JSContext *cx);

    void sweep(JSContext *cx, uint32 releaseInterval);
    void purge(JSContext *cx);
    void finishArenaLists();
    bool arenaListsAreEmpty();

  private:
    js::MathCache                *mathCache;

    js::MathCache *allocMathCache(JSContext *cx);

  public:
    js::MathCache *getMathCache(JSContext *cx) {
        return mathCache ? mathCache : allocMathCache(cx);
    }
};

#define JS_TRACE_MONITOR(cx)    (cx->compartment->traceMonitor)
#define JS_SCRIPTS_TO_GC(cx)    (cx->compartment->scriptsToGC)

namespace js {
static inline MathCache *
GetMathCache(JSContext *cx)
{
    return cx->compartment->getMathCache(cx);
}
}

#ifdef DEBUG
# define EVAL_CACHE_METER(x)    (cx->compartment->evalCacheMeter.x++)
#else
# define EVAL_CACHE_METER(x)    ((void) 0)
#endif

#ifdef _MSC_VER
#pragma warning(pop)
#endif

namespace js {

class PreserveCompartment {
  protected:
    JSContext *cx;
  private:
    JSCompartment *oldCompartment;
    JS_DECL_USE_GUARD_OBJECT_NOTIFIER
  public:
     PreserveCompartment(JSContext *cx JS_GUARD_OBJECT_NOTIFIER_PARAM) : cx(cx) {
        JS_GUARD_OBJECT_NOTIFIER_INIT;
        oldCompartment = cx->compartment;
    }

    ~PreserveCompartment() {
        cx->compartment = oldCompartment;
    }
};

class SwitchToCompartment : public PreserveCompartment {
  public:
    SwitchToCompartment(JSContext *cx, JSCompartment *newCompartment) : PreserveCompartment(cx) {
        cx->compartment = newCompartment;
    }

    SwitchToCompartment(JSContext *cx, JSObject *target) : PreserveCompartment(cx) {
        cx->compartment = target->getCompartment();
    }
};

}

#endif /* jscompartment_h___ */