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*
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* modification, are permitted provided that the following conditions
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*
* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
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*/
#pragma once
#include "ConcurrentJSLock.h"
#include "SpeculatedType.h"
#include "Structure.h"
#include "VirtualRegister.h"
#include <wtf/PrintStream.h>
#include <wtf/StringPrintStream.h>
namespace JSC {
class UnlinkedValueProfile;
template<unsigned numberOfBucketsArgument>
struct ValueProfileBase {
friend class UnlinkedValueProfile;
static constexpr unsigned numberOfBuckets = numberOfBucketsArgument;
static constexpr unsigned numberOfSpecFailBuckets = 1;
static constexpr unsigned totalNumberOfBuckets = numberOfBuckets + numberOfSpecFailBuckets;
ValueProfileBase()
{
clearBuckets();
}
EncodedJSValue* specFailBucket(unsigned i)
{
ASSERT(numberOfBuckets + i < totalNumberOfBuckets);
return m_buckets + numberOfBuckets + i;
}
void clearBuckets()
{
for (unsigned i = 0; i < totalNumberOfBuckets; ++i)
m_buckets[i] = JSValue::encode(JSValue());
}
const ClassInfo* classInfo(unsigned bucket) const
{
JSValue value = JSValue::decode(m_buckets[bucket]);
if (!!value) {
if (!value.isCell())
return nullptr;
return value.asCell()->classInfo();
}
return nullptr;
}
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);
}
}
}
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>() { }
static ptrdiff_t offsetOfFirstBucket() { return OBJECT_OFFSETOF(ValueProfile, m_buckets[0]); }
};
struct ValueProfileAndVirtualRegister : public ValueProfile {
VirtualRegister m_operand;
};
static_assert(sizeof(ValueProfileAndVirtualRegister) >= sizeof(unsigned));
class alignas(ValueProfileAndVirtualRegister) ValueProfileAndVirtualRegisterBuffer final {
WTF_MAKE_NONCOPYABLE(ValueProfileAndVirtualRegisterBuffer);
public:
static ValueProfileAndVirtualRegisterBuffer* create(unsigned size)
{
void* buffer = VMMalloc::malloc(sizeof(ValueProfileAndVirtualRegisterBuffer) + size * sizeof(ValueProfileAndVirtualRegister));
return new (buffer) ValueProfileAndVirtualRegisterBuffer(size);
}
static void destroy(ValueProfileAndVirtualRegisterBuffer* buffer)
{
buffer->~ValueProfileAndVirtualRegisterBuffer();
VMMalloc::free(buffer);
}
template <typename Function>
void forEach(Function function)
{
for (unsigned i = 0; i < m_size; ++i)
function(data()[i]);
}
unsigned size() const { return m_size; }
ValueProfileAndVirtualRegister* data() const
{
return bitwise_cast<ValueProfileAndVirtualRegister*>(this + 1);
}
private:
ValueProfileAndVirtualRegisterBuffer(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
for (unsigned i = 0; i < m_size; ++i)
new (&data()[i]) ValueProfileAndVirtualRegister();
}
~ValueProfileAndVirtualRegisterBuffer()
{
for (unsigned i = 0; i < m_size; ++i)
data()[i].~ValueProfileAndVirtualRegister();
}
unsigned m_size;
};
class UnlinkedValueProfile {
public:
UnlinkedValueProfile() = default;
void update(ValueProfile& profile)
{
SpeculatedType newType = profile.m_prediction | m_prediction;
profile.m_prediction = newType;
m_prediction = newType;
}
private:
SpeculatedType m_prediction { SpecNone };
};
} // namespace JSC