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/*
* Copyright (C) 2011-2019 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Apple Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include "ConcurrentJSLock.h"
#include "SpeculatedType.h"
#include "Structure.h"
#include <wtf/PrintStream.h>
#include <wtf/StringPrintStream.h>
namespace JSC {
template<unsigned numberOfBucketsArgument>
struct ValueProfileBase {
static constexpr unsigned numberOfBuckets = numberOfBucketsArgument;
static constexpr unsigned numberOfSpecFailBuckets = 1;
static constexpr unsigned bucketIndexMask = numberOfBuckets - 1;
static constexpr unsigned totalNumberOfBuckets = numberOfBuckets + numberOfSpecFailBuckets;
ValueProfileBase()
{
for (unsigned i = 0; i < totalNumberOfBuckets; ++i)
m_buckets[i] = JSValue::encode(JSValue());
}
EncodedJSValue* specFailBucket(unsigned i)
{
ASSERT(numberOfBuckets + i < totalNumberOfBuckets);
return m_buckets + numberOfBuckets + i;
}
const ClassInfo* classInfo(unsigned bucket) const
{
JSValue value = JSValue::decode(m_buckets[bucket]);
if (!!value) {
if (!value.isCell())
return 0;
return value.asCell()->structure()->classInfo();
}
return 0;
}
unsigned numberOfSamples() const
{
unsigned result = 0;
for (unsigned i = 0; i < totalNumberOfBuckets; ++i) {
if (!!JSValue::decode(m_buckets[i]))
result++;
}
return result;
}
unsigned totalNumberOfSamples() const
{
return numberOfSamples() + isSampledBefore();
}
bool isSampledBefore() const { return m_prediction != SpecNone; }
bool isLive() const
{
for (unsigned i = 0; i < totalNumberOfBuckets; ++i) {
if (!!JSValue::decode(m_buckets[i]))
return true;
}
return false;
}
CString briefDescription(const ConcurrentJSLocker& locker)
{
computeUpdatedPrediction(locker);
StringPrintStream out;
out.print("predicting ", SpeculationDump(m_prediction));
return out.toCString();
}
void dump(PrintStream& out)
{
out.print("sampled before = ", isSampledBefore(), " live samples = ", numberOfSamples(), " prediction = ", SpeculationDump(m_prediction));
bool first = true;
for (unsigned i = 0; i < totalNumberOfBuckets; ++i) {
JSValue value = JSValue::decode(m_buckets[i]);
if (!!value) {
if (first) {
out.printf(": ");
first = false;
} else
out.printf(", ");
out.print(value);
}
}
}
// Updates the prediction and returns the new one. Never call this from any thread
// that isn't executing the code.
SpeculatedType computeUpdatedPrediction(const ConcurrentJSLocker&)
{
for (unsigned i = 0; i < totalNumberOfBuckets; ++i) {
JSValue value = JSValue::decode(m_buckets[i]);
if (!value)
continue;
mergeSpeculation(m_prediction, speculationFromValue(value));
m_buckets[i] = JSValue::encode(JSValue());
}
return m_prediction;
}
EncodedJSValue m_buckets[totalNumberOfBuckets];
SpeculatedType m_prediction { SpecNone };
};
struct MinimalValueProfile : public ValueProfileBase<0> {
MinimalValueProfile(): ValueProfileBase<0>() { }
};
template<unsigned logNumberOfBucketsArgument>
struct ValueProfileWithLogNumberOfBuckets : public ValueProfileBase<1 << logNumberOfBucketsArgument> {
static constexpr unsigned logNumberOfBuckets = logNumberOfBucketsArgument;
ValueProfileWithLogNumberOfBuckets()
: ValueProfileBase<1 << logNumberOfBucketsArgument>()
{
}
};
struct ValueProfile : public ValueProfileWithLogNumberOfBuckets<0> {
ValueProfile() : ValueProfileWithLogNumberOfBuckets<0>() { }
};
// This is a mini value profile to catch pathologies. It is a counter that gets
// incremented when we take the slow path on any instruction.
struct RareCaseProfile {
RareCaseProfile(BytecodeIndex bytecodeIndex)
: m_bytecodeIndex(bytecodeIndex)
, m_counter(0)
{
}
BytecodeIndex m_bytecodeIndex;
uint32_t m_counter;
};
inline BytecodeIndex getRareCaseProfileBytecodeIndex(RareCaseProfile* rareCaseProfile)
{
return rareCaseProfile->m_bytecodeIndex;
}
struct ValueProfileAndOperand : public ValueProfile {
int m_operand;
};
struct ValueProfileAndOperandBuffer {
WTF_MAKE_STRUCT_FAST_ALLOCATED;
ValueProfileAndOperandBuffer(unsigned size)
: m_size(size)
{
// FIXME: ValueProfile has more stuff than we need. We could optimize these value profiles
// to be more space efficient.
// https://bugs.webkit.org/show_bug.cgi?id=175413
m_buffer = MallocPtr<ValueProfileAndOperand, VMMalloc>::malloc(m_size * sizeof(ValueProfileAndOperand));
for (unsigned i = 0; i < m_size; ++i)
new (&m_buffer.get()[i]) ValueProfileAndOperand();
}
~ValueProfileAndOperandBuffer()
{
for (unsigned i = 0; i < m_size; ++i)
m_buffer.get()[i].~ValueProfileAndOperand();
}
template <typename Function>
void forEach(Function function)
{
for (unsigned i = 0; i < m_size; ++i)
function(m_buffer.get()[i]);
}
unsigned m_size;
MallocPtr<ValueProfileAndOperand, VMMalloc> m_buffer;
};
} // namespace JSC