gecko/js/src/jspropertycache.h

/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla Communicator client code, released
 * March 31, 1998.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
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 * under the terms of either the GPL or the LGPL, and not to allow others to
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 * decision by deleting the provisions above and replace them with the notice
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 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#ifndef jspropertycache_h___
#define jspropertycache_h___

#include "jsapi.h"
#include "jsprvtd.h"
#include "jstypes.h"

JS_BEGIN_EXTERN_C

/*
 * Property cache with structurally typed capabilities for invalidation, for
 * polymorphic callsite method/get/set speedups.  For details, see
 * <https://developer.mozilla.org/en/SpiderMonkey/Internals/Property_cache>.
 */

enum {
    PROPERTY_CACHE_LOG2 = 12,
    PROPERTY_CACHE_SIZE = JS_BIT(PROPERTY_CACHE_LOG2),
    PROPERTY_CACHE_MASK = JS_BITMASK(PROPERTY_CACHE_LOG2)
};

/*
 * Add kshape rather than xor it to avoid collisions between nearby bytecode
 * that are evolving an object by setting successive properties, incrementing
 * the object's scope->shape on each set.
 */
inline jsuword
PROPERTY_CACHE_HASH(jsbytecode *pc, jsuword kshape)
{
    return ((((jsuword(pc) >> PROPERTY_CACHE_LOG2) ^ jsuword(pc)) + kshape) & PROPERTY_CACHE_MASK);
}

/* Property cache value capabilities. */
enum {
    PCVCAP_PROTOBITS = 4,
    PCVCAP_PROTOSIZE = JS_BIT(PCVCAP_PROTOBITS),
    PCVCAP_PROTOMASK = JS_BITMASK(PCVCAP_PROTOBITS),

    PCVCAP_SCOPEBITS = 4,
    PCVCAP_SCOPESIZE = JS_BIT(PCVCAP_SCOPEBITS),
    PCVCAP_SCOPEMASK = JS_BITMASK(PCVCAP_SCOPEBITS),

    PCVCAP_TAGBITS = PCVCAP_PROTOBITS + PCVCAP_SCOPEBITS,
    PCVCAP_TAGMASK = JS_BITMASK(PCVCAP_TAGBITS)
};

const uint32 SHAPE_OVERFLOW_BIT = JS_BIT(32 - PCVCAP_TAGBITS);

inline jsuword
PCVCAP_TAG(jsuword t)
{
    return t & PCVCAP_TAGMASK;
}

inline jsuword
PCVCAP_MAKE(uint32 t, unsigned int s, unsigned int p)
{
    JS_ASSERT(t < SHAPE_OVERFLOW_BIT);
    JS_ASSERT(s <= PCVCAP_SCOPEMASK);
    JS_ASSERT(p <= PCVCAP_PROTOMASK);
    return (t << PCVCAP_TAGBITS) | (s << PCVCAP_PROTOBITS) | p;
}

inline uint32
PCVCAP_SHAPE(jsuword t)
{
    return t >> PCVCAP_TAGBITS;
}

struct JSPropCacheEntry
{
    jsbytecode          *kpc;           /* pc of cache-testing bytecode */
    jsuword             kshape;         /* shape of direct (key) object */
    jsuword             vcap;           /* value capability, see above */
    jsuword             vword;          /* value word, see PCVAL_* below */

    bool adding() const {
        return PCVCAP_TAG(vcap) == 0 && kshape != PCVCAP_SHAPE(vcap);
    }

    bool directHit() const {
        return PCVCAP_TAG(vcap) == 0 && kshape == PCVCAP_SHAPE(vcap);
    }

    static inline bool matchShape(JSContext *cx, JSObject *obj, uint32 shape);
};

/*
 * Special value for functions returning JSPropCacheEntry * to distinguish
 * between failure and no no-cache-fill cases.
 */
#define JS_NO_PROP_CACHE_FILL ((JSPropCacheEntry *) NULL + 1)

#if defined DEBUG_brendan || defined DEBUG_brendaneich
#define JS_PROPERTY_CACHE_METERING 1
#endif

typedef struct JSPropertyCache {
    JSPropCacheEntry    table[PROPERTY_CACHE_SIZE];
    JSBool              empty;
#ifdef JS_PROPERTY_CACHE_METERING
    JSPropCacheEntry    *pctestentry;   /* entry of the last PC-based test */
    uint32              fills;          /* number of cache entry fills */
    uint32              nofills;        /* couldn't fill (e.g. default get) */
    uint32              rofills;        /* set on read-only prop can't fill */
    uint32              disfills;       /* fill attempts on disabled cache */
    uint32              oddfills;       /* fill attempt after setter deleted */
    uint32              modfills;       /* fill that rehashed to a new entry */
    uint32              brandfills;     /* scope brandings to type structural
                                           method fills */
    uint32              noprotos;       /* resolve-returned non-proto pobj */
    uint32              longchains;     /* overlong scope and/or proto chain */
    uint32              recycles;       /* cache entries recycled by fills */
    uint32              tests;          /* cache probes */
    uint32              pchits;         /* fast-path polymorphic op hits */
    uint32              protopchits;    /* pchits hitting immediate prototype */
    uint32              initests;       /* cache probes from JSOP_INITPROP */
    uint32              inipchits;      /* init'ing next property pchit case */
    uint32              inipcmisses;    /* init'ing next property pc misses */
    uint32              settests;       /* cache probes from JOF_SET opcodes */
    uint32              addpchits;      /* adding next property pchit case */
    uint32              setpchits;      /* setting existing property pchit */
    uint32              setpcmisses;    /* setting/adding property pc misses */
    uint32              setmisses;      /* JSOP_SET{NAME,PROP} total misses */
    uint32              kpcmisses;      /* slow-path key id == atom misses */
    uint32              kshapemisses;   /* slow-path key object misses */
    uint32              vcapmisses;     /* value capability misses */
    uint32              misses;         /* cache misses */
    uint32              flushes;        /* cache flushes */
    uint32              pcpurges;       /* shadowing purges on proto chain */
# define PCMETER(x)     x
#else
# define PCMETER(x)     ((void)0)
#endif
} JSPropertyCache;

/*
 * Property cache value tagging/untagging macros.
 */
enum {
    PCVAL_OBJECT = 0,
    PCVAL_SLOT = 1,
    PCVAL_SPROP = 2,

    PCVAL_TAGBITS = 2,
    PCVAL_TAGMASK = JS_BITMASK(PCVAL_TAGBITS),

    PCVAL_NULL = 0
};

inline jsuword PCVAL_TAG(jsuword v) { return v & PCVAL_TAGMASK; }
inline jsuword PCVAL_CLRTAG(jsuword v) { return v & ~jsuword(PCVAL_TAGMASK); }
inline jsuword PCVAL_SETTAG(jsuword v, jsuword t) { return v | t; }

inline bool PCVAL_IS_NULL(jsuword v) { return v == PCVAL_NULL; }

inline bool PCVAL_IS_OBJECT(jsuword v) { return PCVAL_TAG(v) == PCVAL_OBJECT; }
inline JSObject *PCVAL_TO_OBJECT(jsuword v) { JS_ASSERT(PCVAL_IS_OBJECT(v)); return (JSObject *) v; }
inline jsuword OBJECT_TO_PCVAL(JSObject *obj) { return jsuword(obj); }

inline jsval PCVAL_OBJECT_TO_JSVAL(jsuword v) { return OBJECT_TO_JSVAL(PCVAL_TO_OBJECT(v)); }
inline jsuword JSVAL_OBJECT_TO_PCVAL(jsval v) { return OBJECT_TO_PCVAL(JSVAL_TO_OBJECT(v)); }

inline bool PCVAL_IS_SLOT(jsuword v) { return v & PCVAL_SLOT; }
inline jsuint PCVAL_TO_SLOT(jsuword v) { JS_ASSERT(PCVAL_IS_SLOT(v)); return jsuint(v) >> 1; }
inline jsuword SLOT_TO_PCVAL(jsuint i) { return (jsuword(i) << 1) | PCVAL_SLOT; }

inline bool PCVAL_IS_SPROP(jsuword v) { return PCVAL_TAG(v) == PCVAL_SPROP; }
inline JSScopeProperty *PCVAL_TO_SPROP(jsuword v) { JS_ASSERT(PCVAL_IS_SPROP(v)); return (JSScopeProperty *) PCVAL_CLRTAG(v); }
inline jsuword SPROP_TO_PCVAL(JSScopeProperty *sprop) { return PCVAL_SETTAG(jsuword(sprop), PCVAL_SPROP); }

/*
 * Fill property cache entry for key cx->fp->pc, optimized value word computed
 * from obj and sprop, and entry capability forged from 24-bit OBJ_SHAPE(obj),
 * 4-bit scopeIndex, and 4-bit protoIndex.
 *
 * Return the filled cache entry or JS_NO_PROP_CACHE_FILL if caching was not
 * possible.
 */
extern JS_REQUIRES_STACK JSPropCacheEntry *
js_FillPropertyCache(JSContext *cx, JSObject *obj,
                     uintN scopeIndex, uintN protoIndex, JSObject *pobj,
                     JSScopeProperty *sprop, JSBool adding = false);

extern JS_REQUIRES_STACK JSAtom *
js_FullTestPropertyCache(JSContext *cx, jsbytecode *pc,
                         JSObject **objp, JSObject **pobjp,
                         JSPropCacheEntry *entry);

/* The property cache does not need a destructor. */
#define js_FinishPropertyCache(cache) ((void) 0)

extern void
js_PurgePropertyCache(JSContext *cx, JSPropertyCache *cache);

extern void
js_PurgePropertyCacheForScript(JSContext *cx, JSScript *script);

JS_END_EXTERN_C

#endif /* jspropertycache_h___ */