1/*
2 * Copyright (C) 2011 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. 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 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
23 * THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#ifndef WriteBarrierSupport_h
27#define WriteBarrierSupport_h
28
29#include "SamplingCounter.h"
30#include <wtf/Assertions.h>
31
32namespace JSC {
33
34// This allows the JIT to distinguish between uses of the barrier for different
35// kinds of writes. This is used by the JIT for profiling, and may be appropriate
36// for allowing the GC implementation to specialize the JIT's write barrier code
37// for different kinds of target objects.
38enum WriteBarrierUseKind {
39 // This allows specialization for access to the property storage (either
40 // array element or property), but not for any other kind of property
41 // accesses (such as writes that are a consequence of setter execution).
42 WriteBarrierForPropertyAccess,
43
44 // This allows specialization for variable accesses (such as global or
45 // scoped variables).
46 WriteBarrierForVariableAccess,
47
48 // This captures all other forms of write barriers. It should always be
49 // correct to use a generic access write barrier, even when storing to
50 // properties. Hence, if optimization is not necessary, it is preferable
51 // to just use a generic access.
52 WriteBarrierForGenericAccess
53};
54
55class WriteBarrierCounters {
56private:
57 WriteBarrierCounters() { }
58
59public:
60#if ENABLE(WRITE_BARRIER_PROFILING)
61 static GlobalSamplingCounter usesWithBarrierFromCpp;
62 static GlobalSamplingCounter usesWithoutBarrierFromCpp;
63 static GlobalSamplingCounter usesWithBarrierFromJit;
64 static GlobalSamplingCounter usesForPropertiesFromJit;
65 static GlobalSamplingCounter usesForVariablesFromJit;
66 static GlobalSamplingCounter usesWithoutBarrierFromJit;
67
68 static void initialize();
69
70 static GlobalSamplingCounter& jitCounterFor(WriteBarrierUseKind useKind)
71 {
72 switch (useKind) {
73 case WriteBarrierForPropertyAccess:
74 return usesForPropertiesFromJit;
75 case WriteBarrierForVariableAccess:
76 return usesForVariablesFromJit;
77 default:
78 ASSERT(useKind == WriteBarrierForGenericAccess);
79 return usesWithBarrierFromJit;
80 }
81 }
82#else
83 // These are necessary to work around not having conditional exports.
84 JS_EXPORTDATA static char usesWithBarrierFromCpp;
85 JS_EXPORTDATA static char usesWithoutBarrierFromCpp;
86#endif // ENABLE(WRITE_BARRIER_PROFILING)
87
88 static void countWriteBarrier()
89 {
90#if ENABLE(WRITE_BARRIER_PROFILING)
91 WriteBarrierCounters::usesWithBarrierFromCpp.count();
92#endif
93 }
94};
95
96} // namespace JSC
97
98#endif // WriteBarrierSupport_h
99
100