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26 #ifndef WriteBarrierSupport_h
27 #define WriteBarrierSupport_h
29 #include "SamplingCounter.h"
30 #include <wtf/Assertions.h>
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.
38 enum 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
,
44 // This allows specialization for variable accesses (such as global or
46 WriteBarrierForVariableAccess
,
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
55 class WriteBarrierCounters
{
57 WriteBarrierCounters() { }
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
;
68 static void initialize();
70 static GlobalSamplingCounter
& jitCounterFor(WriteBarrierUseKind useKind
)
73 case WriteBarrierForPropertyAccess
:
74 return usesForPropertiesFromJit
;
75 case WriteBarrierForVariableAccess
:
76 return usesForVariablesFromJit
;
78 ASSERT(useKind
== WriteBarrierForGenericAccess
);
79 return usesWithBarrierFromJit
;
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)
88 static void countWriteBarrier()
90 #if ENABLE(WRITE_BARRIER_PROFILING)
91 WriteBarrierCounters::usesWithBarrierFromCpp
.count();
98 #endif // WriteBarrierSupport_h