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/*
* Copyright (C) 2025 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.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``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 INC. OR
* 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
#if ENABLE(WEBASSEMBLY)
#include <JavaScriptCore/WasmCallingConvention.h>
#include <wtf/Expected.h>
#include <wtf/TrailingArray.h>
#include <wtf/text/WTFString.h>
namespace JSC::Wasm {
class CallProfile {
public:
CallProfile() = default;
~CallProfile();
uint32_t count() const { return m_count; }
void incrementCount()
{
++m_count;
}
void observeCrossInstanceCall()
{
makeMegamorphic();
}
void observeCallIndirect(EncodedJSValue boxedCallee)
{
if (m_boxedCallee == boxedCallee)
return;
if (!m_boxedCallee) {
m_boxedCallee = boxedCallee;
return;
}
if (isMegamorphic(m_boxedCallee))
return;
auto* poly = polymorphic(m_boxedCallee);
if (!poly)
poly = makePolymorphic();
for (auto& profile : *poly) {
if (profile.boxedCallee() == boxedCallee) {
profile.incrementCount();
return;
}
if (!profile.boxedCallee()) {
profile.m_boxedCallee = boxedCallee;
profile.incrementCount();
return;
}
}
makeMegamorphic();
}
EncodedJSValue boxedCallee() const { return m_boxedCallee; }
static constexpr ptrdiff_t offsetOfCount() { return OBJECT_OFFSETOF(CallProfile, m_count); }
static constexpr ptrdiff_t offsetOfBoxedCallee() { return OBJECT_OFFSETOF(CallProfile, m_boxedCallee); }
enum State : EncodedJSValue {
Monomorphic = 0b0000,
Polymorphic = 0b0100,
Megamorphic = 0b1000,
};
static constexpr EncodedJSValue calleeMask = Polymorphic | Megamorphic;
#if USE(JSVALUE64)
static_assert(!(JSValue::NativeCalleeTag & calleeMask));
#endif
static constexpr size_t maxPolymorphicCallees = 4;
class alignas(16) PolymorphicCallee final : public TrailingArray<PolymorphicCallee, CallProfile> {
WTF_DEPRECATED_MAKE_FAST_ALLOCATED(PolymorphicCallee);
WTF_MAKE_NONMOVABLE(PolymorphicCallee);
using TrailingArrayType = TrailingArray<PolymorphicCallee, CallProfile>;
friend TrailingArrayType;
public:
static std::unique_ptr<PolymorphicCallee> create(unsigned size, CallProfile* profile)
{
return std::unique_ptr<PolymorphicCallee>(new (fastMalloc(allocationSize(size))) PolymorphicCallee(size, profile));
}
static constexpr ptrdiff_t offsetOfProfile() { return OBJECT_OFFSETOF(PolymorphicCallee, m_profile); }
private:
PolymorphicCallee(unsigned size, CallProfile* profile)
: TrailingArrayType(size)
, m_profile(profile)
{
}
CallProfile* m_profile { nullptr };
};
static bool isMegamorphic(EncodedJSValue boxedCallee)
{
return boxedCallee & Megamorphic;
}
static Callee* monomorphic(EncodedJSValue boxedCallee)
{
if (boxedCallee & calleeMask)
return nullptr;
uintptr_t bits = static_cast<uintptr_t>(boxedCallee & ~calleeMask);
if (!bits)
return nullptr;
return std::bit_cast<Callee*>(CalleeBits(bits).asNativeCallee());
}
static PolymorphicCallee* polymorphic(EncodedJSValue boxedCallee)
{
if (boxedCallee & Megamorphic)
return nullptr;
if (boxedCallee & Polymorphic)
return std::bit_cast<PolymorphicCallee*>(static_cast<uintptr_t>(boxedCallee & ~calleeMask));
return nullptr;
}
private:
void makeMegamorphic()
{
m_boxedCallee = (m_boxedCallee | Megamorphic);
}
PolymorphicCallee* makePolymorphic();
uint32_t m_count { 0 };
#if USE(JSVALUE64)
EncodedJSValue m_boxedCallee { Monomorphic };
#else
EncodedJSValue m_boxedCallee { Megamorphic };
#endif
};
} // namespace JSC::Wasm
#endif // ENABLE(WEBASSEMBLY)
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