V4: Split PlatformAssemblerCommon (and base classes) in its own file

This makes it easier to re-use them later on, without inheriting all
extra stuff that the baseline JIT needs.

Change-Id: I9368b16017b8b9d99f8c005a5b47ec9f9ed09fb0
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 697 insertions, 0 deletions

diff --git a/src/qml/jit/qv4assemblercommon_p.h b/src/qml/jit/qv4assemblercommon_p.h
new file mode 100644
index 0000000000..a48d6fae44
--- /dev/null
+++ b/src/qml/jit/qv4assemblercommon_p.h
@@ -0,0 +1,697 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQml module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QV4PLATFORMASSEMBLER_P_H
+#define QV4PLATFORMASSEMBLER_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <private/qv4engine_p.h>
+#include <private/qv4global_p.h>
+#include <private/qv4function_p.h>
+#include <QHash>
+#include <wtf/Vector.h>
+#include <assembler/MacroAssembler.h>
+
+#ifdef V4_ENABLE_JIT
+
+QT_BEGIN_NAMESPACE
+
+namespace QV4 {
+namespace JIT {
+
+#if defined(Q_PROCESSOR_X86_64) || defined(ENABLE_ALL_ASSEMBLERS_FOR_REFACTORING_PURPOSES)
+#if defined(Q_OS_LINUX) || defined(Q_OS_QNX) || defined(Q_OS_FREEBSD) || defined(Q_OS_DARWIN)
+
+class PlatformAssembler_X86_64_SysV : public JSC::MacroAssembler<JSC::MacroAssemblerX86_64>
+{
+public:
+    static constexpr int NativeStackAlignment = 16;
+
+    static const RegisterID NoRegister = RegisterID(-1);
+
+    static const RegisterID ReturnValueRegister   = RegisterID::eax;
+    static const RegisterID ReturnValueRegisterValue = ReturnValueRegister;
+    static const RegisterID AccumulatorRegister   = RegisterID::eax;
+    static const RegisterID AccumulatorRegisterValue = AccumulatorRegister;
+    static const RegisterID ScratchRegister       = RegisterID::r10;
+    static const RegisterID ScratchRegister2      = RegisterID::r9; // Note: overlaps with Arg5Reg, so do not use while setting up a call!
+    static const RegisterID JSStackFrameRegister  = RegisterID::r12;
+    static const RegisterID CppStackFrameRegister = RegisterID::r13;
+    static const RegisterID EngineRegister        = RegisterID::r14;
+    static const RegisterID StackPointerRegister  = RegisterID::esp;
+    static const RegisterID FramePointerRegister  = RegisterID::ebp;
+    static const FPRegisterID FPScratchRegister   = FPRegisterID::xmm1;
+    static const FPRegisterID FPScratchRegister2  = FPRegisterID::xmm2;
+
+    static const RegisterID Arg0Reg = RegisterID::edi;
+    static const RegisterID Arg1Reg = RegisterID::esi;
+    static const RegisterID Arg2Reg = RegisterID::edx;
+    static const RegisterID Arg3Reg = RegisterID::ecx;
+    static const RegisterID Arg4Reg = RegisterID::r8;
+    static const RegisterID Arg5Reg = RegisterID::r9;
+    static const RegisterID Arg6Reg = NoRegister;
+    static const RegisterID Arg7Reg = NoRegister;
+    static const int ArgInRegCount = 6;
+
+    void popValue()
+    {
+        addPtr(TrustedImmPtr(sizeof(ReturnedValue)), StackPointerRegister);
+    }
+
+    void generatePlatformFunctionEntry()
+    {
+        push(FramePointerRegister);
+        move(StackPointerRegister, FramePointerRegister);
+        move(TrustedImmPtr(nullptr), AccumulatorRegister); push(AccumulatorRegister); // exceptionHandler
+        push(JSStackFrameRegister);
+        push(CppStackFrameRegister);
+        push(EngineRegister);
+        move(Arg0Reg, CppStackFrameRegister);
+        move(Arg1Reg, EngineRegister);
+    }
+
+    void generatePlatformFunctionExit()
+    {
+        pop(EngineRegister);
+        pop(CppStackFrameRegister);
+        pop(JSStackFrameRegister);
+        pop(); // exceptionHandler
+        pop(FramePointerRegister);
+        ret();
+    }
+
+    void callAbsolute(const void *funcPtr)
+    {
+        move(TrustedImmPtr(funcPtr), ScratchRegister);
+        call(ScratchRegister);
+    }
+
+    void pushAligned(RegisterID reg)
+    {
+        subPtr(TrustedImm32(PointerSize), StackPointerRegister);
+        push(reg);
+    }
+
+    void popAligned(RegisterID reg)
+    {
+        pop(reg);
+        addPtr(TrustedImm32(PointerSize), StackPointerRegister);
+    }
+};
+
+typedef PlatformAssembler_X86_64_SysV PlatformAssemblerBase;
+
+#endif
+#if defined(Q_OS_WIN)
+
+class PlatformAssembler_Win64 : public JSC::MacroAssembler<JSC::MacroAssemblerX86_64>
+{
+public:
+    static const RegisterID NoRegister = RegisterID(-1);
+
+    static const RegisterID ReturnValueRegister   = RegisterID::eax;
+    static const RegisterID ReturnValueRegisterValue = ReturnValueRegister;
+    static const RegisterID AccumulatorRegister   = RegisterID::eax;
+    static const RegisterID AccumulatorRegisterValue = AccumulatorRegister;
+    static const RegisterID ScratchRegister       = RegisterID::r10;
+    static const RegisterID ScratchRegister2      = RegisterID::r9; // Note: overlaps with Arg3Reg, so do not use while setting up a call!
+    static const RegisterID JSStackFrameRegister  = RegisterID::r12;
+    static const RegisterID CppStackFrameRegister = RegisterID::r13;
+    static const RegisterID EngineRegister        = RegisterID::r14;
+    static const RegisterID StackPointerRegister  = RegisterID::esp;
+    static const RegisterID FramePointerRegister  = RegisterID::ebp;
+    static const FPRegisterID FPScratchRegister   = FPRegisterID::xmm1;
+
+    static const RegisterID Arg0Reg = RegisterID::ecx;
+    static const RegisterID Arg1Reg = RegisterID::edx;
+    static const RegisterID Arg2Reg = RegisterID::r8;
+    static const RegisterID Arg3Reg = RegisterID::r9;
+    static const RegisterID Arg4Reg = NoRegister;
+    static const RegisterID Arg5Reg = NoRegister;
+    static const RegisterID Arg6Reg = NoRegister;
+    static const RegisterID Arg7Reg = NoRegister;
+    static const int ArgInRegCount = 4;
+
+    void popValue()
+    {
+        addPtr(TrustedImmPtr(sizeof(ReturnedValue)), StackPointerRegister);
+    }
+
+    void generatePlatformFunctionEntry()
+    {
+        push(FramePointerRegister);
+        move(StackPointerRegister, FramePointerRegister);
+        move(TrustedImmPtr(nullptr), AccumulatorRegister); push(AccumulatorRegister); // exceptionHandler
+        push(JSStackFrameRegister);
+        push(CppStackFrameRegister);
+        push(EngineRegister);
+        move(Arg0Reg, CppStackFrameRegister);
+        move(Arg1Reg, EngineRegister);
+    }
+
+    void generatePlatformFunctionExit()
+    {
+        pop(EngineRegister);
+        pop(CppStackFrameRegister);
+        pop(JSStackFrameRegister);
+        pop(); // exceptionHandler
+        pop(FramePointerRegister);
+        ret();
+    }
+
+    void callAbsolute(const void *funcPtr)
+    {
+        move(TrustedImmPtr(funcPtr), ScratchRegister);
+        subPtr(TrustedImm32(4 * PointerSize), StackPointerRegister);
+        call(ScratchRegister);
+        addPtr(TrustedImm32(4 * PointerSize), StackPointerRegister);
+    }
+
+    void pushAligned(RegisterID reg)
+    {
+        subPtr(TrustedImm32(PointerSize), StackPointerRegister);
+        push(reg);
+    }
+
+    void popAligned(RegisterID reg)
+    {
+        pop(reg);
+        addPtr(TrustedImm32(PointerSize), StackPointerRegister);
+    }
+};
+
+typedef PlatformAssembler_Win64 PlatformAssemblerBase;
+
+#endif
+#endif
+
+#if (defined(Q_PROCESSOR_X86) && !defined(Q_PROCESSOR_X86_64)) || defined(ENABLE_ALL_ASSEMBLERS_FOR_REFACTORING_PURPOSES)
+
+class PlatformAssembler_X86_All : public JSC::MacroAssembler<JSC::MacroAssemblerX86>
+{
+public:
+    static const RegisterID NoRegister = RegisterID(-1);
+
+    static const RegisterID ReturnValueRegisterValue = RegisterID::eax;
+    static const RegisterID ReturnValueRegisterTag   = RegisterID::edx;
+    static const RegisterID ScratchRegister          = RegisterID::ecx;
+    static const RegisterID AccumulatorRegisterValue = ReturnValueRegisterValue;
+    static const RegisterID AccumulatorRegisterTag   = ReturnValueRegisterTag;
+    static const RegisterID JSStackFrameRegister  = RegisterID::ebx;
+    static const RegisterID CppStackFrameRegister = RegisterID::esi;
+    static const RegisterID EngineRegister        = RegisterID::edi;
+    static const RegisterID StackPointerRegister  = RegisterID::esp;
+    static const RegisterID FramePointerRegister  = RegisterID::ebp;
+    static const FPRegisterID FPScratchRegister   = FPRegisterID::xmm1;
+
+    static const RegisterID Arg0Reg = NoRegister;
+    static const RegisterID Arg1Reg = NoRegister;
+    static const RegisterID Arg2Reg = NoRegister;
+    static const RegisterID Arg3Reg = NoRegister;
+    static const RegisterID Arg4Reg = NoRegister;
+    static const RegisterID Arg5Reg = NoRegister;
+    static const RegisterID Arg6Reg = NoRegister;
+    static const RegisterID Arg7Reg = NoRegister;
+    static const int ArgInRegCount = 0;
+
+    void popValue()
+    {
+        addPtr(TrustedImmPtr(sizeof(ReturnedValue)), StackPointerRegister);
+    }
+
+    void generatePlatformFunctionEntry()
+    {
+        push(RegisterID::ebp);
+        move(RegisterID::esp, RegisterID::ebp);
+        move(TrustedImmPtr(nullptr), AccumulatorRegisterValue); push(AccumulatorRegisterValue); // exceptionHandler
+        push(JSStackFrameRegister);
+        push(CppStackFrameRegister);
+        push(EngineRegister);
+        // Ensure the stack is 16-byte aligned in order for compiler generated aligned SSE2
+        // instructions to be able to target the stack.
+        subPtr(TrustedImm32(8), StackPointerRegister);
+        loadPtr(Address(FramePointerRegister, 2 * PointerSize), CppStackFrameRegister);
+        loadPtr(Address(FramePointerRegister, 3 * PointerSize), EngineRegister);
+    }
+
+    void generatePlatformFunctionExit()
+    {
+        addPtr(TrustedImm32(8), StackPointerRegister);
+        pop(EngineRegister);
+        pop(CppStackFrameRegister);
+        pop(JSStackFrameRegister);
+        pop(); // exceptionHandler
+        pop(RegisterID::ebp);
+        ret();
+    }
+
+    void callAbsolute(const void *funcPtr)
+    {
+        move(TrustedImmPtr(funcPtr), ScratchRegister);
+        call(ScratchRegister);
+    }
+
+    void pushAligned(RegisterID reg)
+    {
+        subPtr(TrustedImm32(PointerSize), StackPointerRegister);
+        push(reg);
+    }
+
+    void popAligned(RegisterID reg)
+    {
+        pop(reg);
+        addPtr(TrustedImm32(PointerSize), StackPointerRegister);
+    }
+};
+
+typedef PlatformAssembler_X86_All PlatformAssemblerBase;
+
+#endif
+
+#if defined(Q_PROCESSOR_ARM_64) || defined(ENABLE_ALL_ASSEMBLERS_FOR_REFACTORING_PURPOSES)
+
+class PlatformAssembler_ARM64 : public JSC::MacroAssembler<JSC::MacroAssemblerARM64>
+{
+public:
+    static const RegisterID NoRegister = RegisterID(-1);
+
+    static const RegisterID ReturnValueRegister   = JSC::ARM64Registers::x0;
+    static const RegisterID ReturnValueRegisterValue = ReturnValueRegister;
+    static const RegisterID AccumulatorRegister   = JSC::ARM64Registers::x9;
+    static const RegisterID AccumulatorRegisterValue = AccumulatorRegister;
+    static const RegisterID ScratchRegister       = JSC::ARM64Registers::x10;
+    static const RegisterID ScratchRegister2      = JSC::ARM64Registers::x7; // Note: overlaps with Arg7Reg, so do not use while setting up a call!
+    static const RegisterID JSStackFrameRegister  = JSC::ARM64Registers::x19;
+    static const RegisterID CppStackFrameRegister = JSC::ARM64Registers::x20;
+    static const RegisterID EngineRegister        = JSC::ARM64Registers::x21;
+    static const RegisterID StackPointerRegister  = JSC::ARM64Registers::sp;
+    static const RegisterID FramePointerRegister  = JSC::ARM64Registers::fp;
+    static const FPRegisterID FPScratchRegister   = JSC::ARM64Registers::q1;
+
+    static const RegisterID Arg0Reg = JSC::ARM64Registers::x0;
+    static const RegisterID Arg1Reg = JSC::ARM64Registers::x1;
+    static const RegisterID Arg2Reg = JSC::ARM64Registers::x2;
+    static const RegisterID Arg3Reg = JSC::ARM64Registers::x3;
+    static const RegisterID Arg4Reg = JSC::ARM64Registers::x4;
+    static const RegisterID Arg5Reg = JSC::ARM64Registers::x5;
+    static const RegisterID Arg6Reg = JSC::ARM64Registers::x6;
+    static const RegisterID Arg7Reg = JSC::ARM64Registers::x7;
+    static const int ArgInRegCount = 8;
+
+    void push(RegisterID src)
+    {
+        pushToSave(src);
+    }
+
+    void pop(RegisterID dest)
+    {
+        popToRestore(dest);
+    }
+
+    void pop()
+    {
+        add64(TrustedImm32(16), stackPointerRegister);
+    }
+
+    void popValue()
+    {
+        pop();
+    }
+
+    void generatePlatformFunctionEntry()
+    {
+        pushPair(JSC::ARM64Registers::fp, JSC::ARM64Registers::lr);
+        move(RegisterID::sp, RegisterID::fp);
+        move(TrustedImmPtr(nullptr), AccumulatorRegister); // exceptionHandler
+        pushPair(JSStackFrameRegister, AccumulatorRegister);
+        pushPair(EngineRegister, CppStackFrameRegister);
+        move(Arg0Reg, CppStackFrameRegister);
+        move(Arg1Reg, EngineRegister);
+    }
+
+    void generatePlatformFunctionExit()
+    {
+        move(AccumulatorRegister, ReturnValueRegister);
+        popPair(EngineRegister, CppStackFrameRegister);
+        popPair(JSStackFrameRegister, AccumulatorRegister);
+        popPair(JSC::ARM64Registers::fp, JSC::ARM64Registers::lr);
+        ret();
+    }
+
+    void callAbsolute(const void *funcPtr)
+    {
+        move(TrustedImmPtr(funcPtr), ScratchRegister);
+        call(ScratchRegister);
+    }
+
+    void pushAligned(RegisterID reg)
+    {
+        pushToSave(reg);
+    }
+
+    void popAligned(RegisterID reg)
+    {
+        popToRestore(reg);
+    }
+};
+
+typedef PlatformAssembler_ARM64 PlatformAssemblerBase;
+
+#endif
+
+#if defined(Q_PROCESSOR_ARM_32) || defined(ENABLE_ALL_ASSEMBLERS_FOR_REFACTORING_PURPOSES)
+
+class PlatformAssembler_ARM32 : public JSC::MacroAssembler<JSC::MacroAssemblerARMv7>
+{
+public:
+    static const RegisterID NoRegister = RegisterID(-1);
+
+    static const RegisterID ReturnValueRegisterValue = JSC::ARMRegisters::r0;
+    static const RegisterID ReturnValueRegisterTag   = JSC::ARMRegisters::r1;
+    static const RegisterID ScratchRegister          = JSC::ARMRegisters::r2;
+    static const RegisterID AccumulatorRegisterValue = JSC::ARMRegisters::r4;
+    static const RegisterID AccumulatorRegisterTag   = JSC::ARMRegisters::r5;
+    // r6 is used by MacroAssemblerARMv7
+    static const RegisterID JSStackFrameRegister     = JSC::ARMRegisters::r8;
+    static const RegisterID CppStackFrameRegister    = JSC::ARMRegisters::r10;
+#if CPU(ARM_THUMB2) || defined(V4_BOOTSTRAP)
+    static const RegisterID FramePointerRegister     = JSC::ARMRegisters::r7;
+    static const RegisterID EngineRegister           = JSC::ARMRegisters::r11;
+#else // Thumbs down
+    static const RegisterID FramePointerRegister     = JSC::ARMRegisters::r11;
+    static const RegisterID EngineRegister           = JSC::ARMRegisters::r7;
+#endif
+    static const RegisterID StackPointerRegister     = JSC::ARMRegisters::r13;
+    static const FPRegisterID FPScratchRegister      = JSC::ARMRegisters::d1;
+
+    static const RegisterID Arg0Reg = JSC::ARMRegisters::r0;
+    static const RegisterID Arg1Reg = JSC::ARMRegisters::r1;
+    static const RegisterID Arg2Reg = JSC::ARMRegisters::r2;
+    static const RegisterID Arg3Reg = JSC::ARMRegisters::r3;
+    static const RegisterID Arg4Reg = NoRegister;
+    static const RegisterID Arg5Reg = NoRegister;
+    static const RegisterID Arg6Reg = NoRegister;
+    static const RegisterID Arg7Reg = NoRegister;
+    static const int ArgInRegCount = 4;
+
+    void popValue()
+    {
+        addPtr(TrustedImm32(sizeof(ReturnedValue)), StackPointerRegister);
+    }
+
+    void generatePlatformFunctionEntry()
+    {
+        push(JSC::ARMRegisters::lr);
+        push(FramePointerRegister);
+        move(StackPointerRegister, FramePointerRegister);
+        push(TrustedImm32(0)); // exceptionHandler
+        push(AccumulatorRegisterValue);
+        push(AccumulatorRegisterTag);
+        push(addressTempRegister);
+        push(JSStackFrameRegister);
+        push(CppStackFrameRegister);
+        push(EngineRegister);
+        subPtr(TrustedImm32(4), StackPointerRegister); // stack alignment
+        move(Arg0Reg, CppStackFrameRegister);
+        move(Arg1Reg, EngineRegister);
+    }
+
+    void generatePlatformFunctionExit()
+    {
+        move(AccumulatorRegisterValue, ReturnValueRegisterValue);
+        move(AccumulatorRegisterTag, ReturnValueRegisterTag);
+        addPtr(TrustedImm32(4), StackPointerRegister); // stack alignment
+        pop(EngineRegister);
+        pop(CppStackFrameRegister);
+        pop(JSStackFrameRegister);
+        pop(addressTempRegister);
+        pop(AccumulatorRegisterTag);
+        pop(AccumulatorRegisterValue);
+        pop(); // exceptionHandler
+        pop(FramePointerRegister);
+        pop(JSC::ARMRegisters::lr);
+        ret();
+    }
+
+    void callAbsolute(const void *funcPtr)
+    {
+        move(TrustedImmPtr(funcPtr), dataTempRegister);
+        call(dataTempRegister);
+    }
+
+    void pushAligned(RegisterID reg)
+    {
+        subPtr(TrustedImm32(PointerSize), StackPointerRegister);
+        push(reg);
+    }
+
+    void popAligned(RegisterID reg)
+    {
+        pop(reg);
+        addPtr(TrustedImm32(PointerSize), StackPointerRegister);
+    }
+};
+
+typedef PlatformAssembler_ARM32 PlatformAssemblerBase;
+#endif
+
+class PlatformAssemblerCommon : public JIT::PlatformAssemblerBase
+{
+public:
+    PlatformAssemblerCommon(const Value *constantTable)
+        : constantTable(constantTable)
+    {}
+
+    virtual ~PlatformAssemblerCommon();
+
+    Address exceptionHandlerAddress() const
+    {
+        return Address(FramePointerRegister, -1 * PointerSize);
+    }
+
+    Address contextAddress() const
+    {
+        return Address(JSStackFrameRegister, offsetof(CallData, context));
+    }
+
+    RegisterID registerForArg(int arg) const
+    {
+        Q_ASSERT(arg >= 0);
+        Q_ASSERT(arg < ArgInRegCount);
+        switch (arg) {
+        case 0: return Arg0Reg;
+        case 1: return Arg1Reg;
+        case 2: return Arg2Reg;
+        case 3: return Arg3Reg;
+        case 4: return Arg4Reg;
+        case 5: return Arg5Reg;
+        case 6: return Arg6Reg;
+        case 7: return Arg7Reg;
+        default:
+            Q_UNIMPLEMENTED();
+            Q_UNREACHABLE();
+        }
+    }
+
+    Address loadFunctionPtr(RegisterID target)
+    {
+        Address addr(CppStackFrameRegister, offsetof(CppStackFrame, v4Function));
+        loadPtr(addr, target);
+        return Address(target);
+    }
+
+    Address loadCompilationUnitPtr(RegisterID target)
+    {
+        Address addr = loadFunctionPtr(target);
+        addr.offset = offsetof(QV4::Function, compilationUnit);
+        loadPtr(addr, target);
+        return Address(target);
+    }
+
+    Address loadConstAddress(int constIndex, RegisterID baseReg = ScratchRegister)
+    {
+        Address addr = loadCompilationUnitPtr(baseReg);
+        addr.offset = offsetof(QV4::CompiledData::CompilationUnitBase, constants);
+        loadPtr(addr, baseReg);
+        addr.offset = constIndex * int(sizeof(QV4::Value));
+        return addr;
+    }
+
+    Address loadStringAddress(int stringId)
+    {
+        Address addr = loadCompilationUnitPtr(ScratchRegister);
+        addr.offset = offsetof(QV4::CompiledData::CompilationUnitBase, runtimeStrings);
+        loadPtr(addr, ScratchRegister);
+        return Address(ScratchRegister, stringId * PointerSize);
+    }
+
+    void passAsArg(RegisterID src, int arg)
+    {
+        move(src, registerForArg(arg));
+    }
+
+    void generateCatchTrampoline(std::function<void()> loadUndefined)
+    {
+        for (Jump j : catchyJumps)
+            j.link(this);
+
+        loadPtr(exceptionHandlerAddress(), ScratchRegister);
+        Jump exitFunction = branchPtr(Equal, ScratchRegister, TrustedImmPtr(0));
+        jump(ScratchRegister);
+        exitFunction.link(this);
+        loadUndefined();
+
+        if (functionExit.isSet())
+            jump(functionExit);
+        else
+            generateFunctionExit();
+    }
+
+    void checkException()
+    {
+        addCatchyJump(
+                    branch32(NotEqual,
+                             Address(EngineRegister, offsetof(EngineBase, hasException)),
+                             TrustedImm32(0)));
+    }
+
+    void addCatchyJump(Jump j)
+    {
+        Q_ASSERT(j.isSet());
+        catchyJumps.push_back(j);
+    }
+
+    void generateFunctionEntry()
+    {
+        generatePlatformFunctionEntry();
+        loadPtr(Address(CppStackFrameRegister, offsetof(CppStackFrame, jsFrame)), JSStackFrameRegister);
+        allocateStackSpace();
+    }
+
+    virtual void allocateStackSpace() {}
+
+    void generateFunctionExit()
+    {
+        if (functionExit.isSet()) {
+            jump(functionExit);
+            return;
+        }
+
+        functionExit = label();
+        freeStackSpace();
+        generatePlatformFunctionExit();
+    }
+
+    virtual void freeStackSpace() {}
+
+    void addLabelForOffset(int offset)
+    {
+        labelForOffset.insert(offset, label());
+    }
+
+    void addJumpToOffset(const Jump &jump, int offset)
+    {
+        jumpsToLink.push_back({ jump, offset });
+    }
+
+    void addEHTarget(const DataLabelPtr &label, int offset)
+    {
+        ehTargets.push_back({ label, offset });
+    }
+
+    void link(Function *function);
+
+    Value constant(int idx) const
+    { return constantTable[idx]; }
+
+    // stuff for runtime calls
+    void prepareCallWithArgCount(int argc);
+    void storeInstructionPointer(int instructionOffset);
+    void passAccumulatorAsArg(int arg);
+    void pushAccumulatorAsArg(int arg);
+    void passFunctionAsArg(int arg);
+    void passEngineAsArg(int arg);
+    void passJSSlotAsArg(int reg, int arg);
+    void passAddressAsArg(Address addr, int arg);
+    void passCppFrameAsArg(int arg);
+    void passInt32AsArg(int value, int arg);
+    void callRuntime(const char *functionName, const void *funcPtr);
+    void callRuntimeUnchecked(const char *functionName, const void *funcPtr);
+
+
+private:
+    void passAccumulatorAsArg_internal(int arg, bool doPush);
+    static Address argStackAddress(int arg);
+
+private:
+    const Value* constantTable;
+    struct JumpTarget { JSC::MacroAssemblerBase::Jump jump; int offset; };
+    std::vector<JumpTarget> jumpsToLink;
+    struct ExceptionHanlderTarget { JSC::MacroAssemblerBase::DataLabelPtr label; int offset; };
+    std::vector<ExceptionHanlderTarget> ehTargets;
+    QHash<int, JSC::MacroAssemblerBase::Label> labelForOffset;
+    QHash<const void *, const char *> functions;
+    std::vector<Jump> catchyJumps;
+    Label functionExit;
+
+#ifndef QT_NO_DEBUG
+    enum { NoCall = -1 };
+    int remainingArgcForCall = NoCall;
+#endif
+    int argcOnStackForCall = 0;
+};
+
+} // JIT namespace
+} // QV4 namespace
+
+QT_END_NAMESPACE
+
+#endif // V4_ENABLE_JIT
+
+#endif // QV4PLATFORMASSEMBLER_P_H