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#pragma once
27
28#include "SamplingCounter.h"
29#include <wtf/Assertions.h>
30
31namespace JSC {
32
33// This allows the JIT to distinguish between uses of the barrier for different
34// kinds of writes. This is used by the JIT for profiling, and may be appropriate
35// for allowing the GC implementation to specialize the JIT's write barrier code
36// for different kinds of target objects.
37enum WriteBarrierUseKind {
38 // This allows specialization for access to the property storage (either
39 // array element or property), but not for any other kind of property
40 // accesses (such as writes that are a consequence of setter execution).
41 WriteBarrierForPropertyAccess,
42
43 // This allows specialization for variable accesses (such as global or
44 // scoped variables).
45 WriteBarrierForVariableAccess,
46
47 // This captures all other forms of write barriers. It should always be
48 // correct to use a generic access write barrier, even when storing to
49 // properties. Hence, if optimization is not necessary, it is preferable
50 // to just use a generic access.
51 WriteBarrierForGenericAccess
52};
53
54class WriteBarrierCounters {
55private:
56 WriteBarrierCounters() { }
57
58public:
59#if ENABLE(WRITE_BARRIER_PROFILING)
60 static GlobalSamplingCounter usesWithBarrierFromCpp;
61 static GlobalSamplingCounter usesWithoutBarrierFromCpp;
62 static GlobalSamplingCounter usesWithBarrierFromJit;
63 static GlobalSamplingCounter usesForPropertiesFromJit;
64 static GlobalSamplingCounter usesForVariablesFromJit;
65 static GlobalSamplingCounter usesWithoutBarrierFromJit;
66
67 static void initialize();
68
69 static GlobalSamplingCounter& jitCounterFor(WriteBarrierUseKind useKind)
70 {
71 switch (useKind) {
72 case WriteBarrierForPropertyAccess:
73 return usesForPropertiesFromJit;
74 case WriteBarrierForVariableAccess:
75 return usesForVariablesFromJit;
76 default:
77 ASSERT(useKind == WriteBarrierForGenericAccess);
78 return usesWithBarrierFromJit;
79 }
80 }
81#else
82 // These are necessary to work around not having conditional exports.
83 JS_EXPORT_PRIVATE static char usesWithBarrierFromCpp;
84 JS_EXPORT_PRIVATE static char usesWithoutBarrierFromCpp;
85#endif // ENABLE(WRITE_BARRIER_PROFILING)
86
87 static void countWriteBarrier()
88 {
89#if ENABLE(WRITE_BARRIER_PROFILING)
90 WriteBarrierCounters::usesWithBarrierFromCpp.count();
91#endif
92 }
93};
94
95} // namespace JSC
96