Source/JavaScriptCore/dfg/DFGOSRExit.h

/*
 * Copyright (C) 2011-2021 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.
 *
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 * 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
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 */

#pragma once

#if ENABLE(DFG_JIT)

#include "DFGOSRExitBase.h"
#include "DFGVariableEventStream.h"
#include "GPRInfo.h"
#include "MacroAssembler.h"
#include "MethodOfGettingAValueProfile.h"
#include "Operands.h"
#include "ValueRecovery.h"
#include <wtf/RefPtr.h>

namespace JSC {

class ArrayProfile;
class CCallHelpers;

namespace Probe {
class Context;
} // namespace Probe

namespace Profiler {
class OSRExit;
} // namespace Profiler

namespace DFG {

class SpeculativeJIT;
struct BasicBlock;
struct Node;

// This enum describes the types of additional recovery that
// may need be performed should a speculation check fail.
enum SpeculationRecoveryType : uint8_t {
    SpeculativeAdd,
    SpeculativeAddSelf,
    SpeculativeAddImmediate,
    BooleanSpeculationCheck
};

// === SpeculationRecovery ===
//
// This class provides additional information that may be associated with a
// speculation check - for example 
class SpeculationRecovery {
public:
    SpeculationRecovery(SpeculationRecoveryType type, GPRReg dest, GPRReg src)
        : m_src(src)
        , m_dest(dest)
        , m_type(type)
    {
        ASSERT(m_type == SpeculativeAdd || m_type == SpeculativeAddSelf || m_type == BooleanSpeculationCheck);
    }

    SpeculationRecovery(SpeculationRecoveryType type, GPRReg dest, int32_t immediate)
        : m_immediate(immediate)
        , m_dest(dest)
        , m_type(type)
    {
        ASSERT(m_type == SpeculativeAddImmediate);
    }

    SpeculationRecoveryType type() { return m_type; }
    GPRReg dest() { return m_dest; }
    GPRReg src() { return m_src; }
    int32_t immediate() { return m_immediate; }

private:
    // different recovery types may required different additional information here.
    union {
        GPRReg m_src;
        int32_t m_immediate;
    };
    GPRReg m_dest;

    // Indicates the type of additional recovery to be performed.
    SpeculationRecoveryType m_type;
};

enum class ExtraInitializationLevel;

struct OSRExitState : RefCounted<OSRExitState> {
    OSRExitState(OSRExitBase& exit, CodeBlock* codeBlock, CodeBlock* baselineCodeBlock, Operands<ValueRecovery>& operands, Vector<UndefinedOperandSpan>&& undefinedOperandSpans, SpeculationRecovery* recovery, ptrdiff_t stackPointerOffset, int32_t activeThreshold, double memoryUsageAdjustedThreshold, void* jumpTarget, ArrayProfile* arrayProfile, bool isJumpToLLInt)
        : exit(exit)
        , codeBlock(codeBlock)
        , baselineCodeBlock(baselineCodeBlock)
        , operands(operands)
        , undefinedOperandSpans(undefinedOperandSpans)
        , recovery(recovery)
        , stackPointerOffset(stackPointerOffset)
        , activeThreshold(activeThreshold)
        , memoryUsageAdjustedThreshold(memoryUsageAdjustedThreshold)
        , jumpTarget(jumpTarget)
        , arrayProfile(arrayProfile)
        , isJumpToLLInt(isJumpToLLInt)
    { }

    OSRExitBase& exit;
    CodeBlock* codeBlock;
    CodeBlock* baselineCodeBlock;
    Operands<ValueRecovery> operands;
    Vector<UndefinedOperandSpan> undefinedOperandSpans;
    SpeculationRecovery* recovery;
    ptrdiff_t stackPointerOffset;
    uint32_t activeThreshold;
    double memoryUsageAdjustedThreshold;
    void* jumpTarget;
    ArrayProfile* arrayProfile;
    bool isJumpToLLInt;

    ExtraInitializationLevel extraInitializationLevel;
    Profiler::OSRExit* profilerExit { nullptr };
};

JSC_DECLARE_JIT_OPERATION(operationCompileOSRExit, void, (CallFrame*, void*));
JSC_DECLARE_JIT_OPERATION(operationDebugPrintSpeculationFailure, void, (CallFrame*, void*, void*));
JSC_DECLARE_JIT_OPERATION(operationMaterializeOSRExitSideState, void, (VM*, const OSRExitBase*, EncodedJSValue*));

// === OSRExit ===
//
// This structure describes how to exit the speculative path by
// going into baseline code.
struct OSRExit : public OSRExitBase {
    OSRExit(ExitKind, JSValueSource, MethodOfGettingAValueProfile, SpeculativeJIT*, unsigned streamIndex, unsigned recoveryIndex = UINT_MAX);

    CodeLocationLabel<JSInternalPtrTag> m_patchableJumpLocation;
    MacroAssemblerCodeRef<OSRExitPtrTag> m_code;

    RefPtr<OSRExitState> exitState;
    
    JSValueSource m_jsValueSource;
    MethodOfGettingAValueProfile m_valueProfile;
    
    unsigned m_recoveryIndex;

    CodeLocationJump<JSInternalPtrTag> codeLocationForRepatch() const;

    unsigned m_streamIndex;
    void considerAddingAsFrequentExitSite(CodeBlock* profiledCodeBlock)
    {
        OSRExitBase::considerAddingAsFrequentExitSite(profiledCodeBlock, ExitFromDFG);
    }

    static void compileExit(CCallHelpers&, VM&, const OSRExit&, const Operands<ValueRecovery>&, SpeculationRecovery*);

private:
    static void emitRestoreArguments(CCallHelpers&, VM&, const Operands<ValueRecovery>&);
    friend void JIT_OPERATION_ATTRIBUTES operationDebugPrintSpeculationFailure(CallFrame*, void*, void*);
};

struct SpeculationFailureDebugInfo {
    WTF_MAKE_STRUCT_FAST_ALLOCATED;
    CodeBlock* codeBlock;
    ExitKind kind;
    BytecodeIndex bytecodeIndex;
};

} } // namespace JSC::DFG

#endif // ENABLE(DFG_JIT)