CoreCLR源码探索(二) new是什么_hook jit compilemethod

OPDEF(CEE_NEWOBJ, "newobj", VarPop, PushRef, InlineMethod, IObjModel, 1, 0xFF, 0x73, CALL)
OPDEF(CEE_NEWARR, "newarr", PopI, PushRef, InlineType, IObjModel, 1, 0xFF, 0x8D, NEXT)

CorJitResult CILJit::compileMethod(
    ICorJitInfo* compHnd, CORINFO_METHOD_INFO* methodInfo, unsigned flags, BYTE** entryAddress, ULONG* nativeSizeOfCode)
{
    // 省略部分代码......
    assert(methodInfo->ILCode);
    result = jitNativeCode(methodHandle, methodInfo->scope, compHnd, methodInfo, &methodCodePtr, nativeSizeOfCode,
                           &jitFlags, nullptr);
    // 省略部分代码......
    return CorJitResult(result);
}

int jitNativeCode(CORINFO_METHOD_HANDLE methodHnd,
                  CORINFO_MODULE_HANDLE classPtr,
                  COMP_HANDLE           compHnd,
                  CORINFO_METHOD_INFO*  methodInfo,
                  void**                methodCodePtr,
                  ULONG*                methodCodeSize,
                  JitFlags*             compileFlags,
                  void*                 inlineInfoPtr)
{
    // 省略部分代码......
    pParam->pComp->compInit(pParam->pAlloc, pParam->inlineInfo);
    pParam->pComp->jitFallbackCompile = pParam->jitFallbackCompile;
    // Now generate the code
    pParam->result =
        pParam->pComp->compCompile(pParam->methodHnd, pParam->classPtr, pParam->compHnd, pParam->methodInfo,
                                   pParam->methodCodePtr, pParam->methodCodeSize, pParam->compileFlags);
    // 省略部分代码......
    return result;
}

int Compiler::compCompile(CORINFO_METHOD_HANDLE methodHnd,
                          CORINFO_MODULE_HANDLE classPtr,
                          COMP_HANDLE           compHnd,
                          CORINFO_METHOD_INFO*  methodInfo,
                          void**                methodCodePtr,
                          ULONG*                methodCodeSize,
                          JitFlags*             compileFlags)
{
    // 省略部分代码......
    pParam->result = pParam->pThis->compCompileHelper(pParam->classPtr, pParam->compHnd, pParam->methodInfo,
                                                      pParam->methodCodePtr, pParam->methodCodeSize,
                                                      pParam->compileFlags, pParam->instVerInfo);
    // 省略部分代码......
    return param.result;
}

int Compiler::compCompileHelper(CORINFO_MODULE_HANDLE            classPtr,
                                COMP_HANDLE                      compHnd,
                                CORINFO_METHOD_INFO*             methodInfo,
                                void**                           methodCodePtr,
                                ULONG*                           methodCodeSize,
                                JitFlags*                        compileFlags,
                                CorInfoInstantiationVerification instVerInfo)
{
    // 省略部分代码......
    // 初始化本地变量表
    lvaInitTypeRef();
    
    // 省略部分代码......
    // 查找所有BasicBlock
    fgFindBasicBlocks();
 
    // 省略部分代码......
    // 调用3个参数的compCompile函数，注意不是7个函数的compCompile函数
    compCompile(methodCodePtr, methodCodeSize, compileFlags);
 
    // 省略部分代码......
    return CORJIT_OK;
}

//*********************************************************************************************
// #Phases
//
// This is the most interesting 'toplevel' function in the JIT.  It goes through the operations of
// importing, morphing, optimizations and code generation.  This is called from the EE through the
// code:CILJit::compileMethod function.
//
// For an overview of the structure of the JIT, see:
//   https://github.com/dotnet/coreclr/blob/master/Documentation/botr/ryujit-overview.md
//
void Compiler::compCompile(void** methodCodePtr, ULONG* methodCodeSize, JitFlags* compileFlags)
{
    // 省略部分代码......
    // 转换BasicBlock(基本代码块)到GenTree(语句树)
    fgImport();
 
    // 省略部分代码......
    // 这里会进行各个处理步骤(Phases)，如Inline和优化等
    
    // 省略部分代码......
    // 转换GT_ALLOCOBJ节点到GT_CALL节点(分配内存=调用帮助函数)
    ObjectAllocator objectAllocator(this);
    objectAllocator.Run();
 
    // 省略部分代码......
    // 创建本地变量表和计算各个变量的引用计数
    lvaMarkLocalVars();
 
    // 省略部分代码......
    // 具体化语句树
    Lowering lower(this, m_pLinearScan); // PHASE_LOWERING
    lower.Run();
 
    // 省略部分代码......
    // 生成机器码
    codeGen->genGenerateCode(methodCodePtr, methodCodeSize);
}

void Compiler::fgImport()
{
    // 省略部分代码......
    impImport(fgFirstBB);
    // 省略部分代码......
}

void Compiler::impImport(BasicBlock* method)
{
    // 省略部分代码......
    /* Import blocks in the worker-list until there are no more */
    while (impPendingList)
    {
        PendingDsc* dsc = impPendingList;
        impPendingList  = impPendingList->pdNext;
        // 省略部分代码......
        /* Now import the block */
        impImportBlock(dsc->pdBB);
    }
}

//***************************************************************
// Import the instructions for the given basic block.  Perform
// verification, throwing an exception on failure.  Push any successor blocks that are enabled for the first
// time, or whose verification pre-state is changed.
void Compiler::impImportBlock(BasicBlock* block)
{
    // 省略部分代码......
    pParam->pThis->impImportBlockCode(pParam->block);
 
}

/*****************************************************************************
 *  Import the instr for the given basic block
 */
void Compiler::impImportBlockCode(BasicBlock* block)
{
    // 省略部分代码......
    // 处理CEE_NEWOBJ指令
    case CEE_NEWOBJ:
        // 在这里微软给出了有三种情况
        // 一种是对象是array，一种是对象有活动的长度（例如string），一种是普通的class
        // 在这里我们只分析第三种情况
        // There are three different cases for new
        // Object size is variable (depends on arguments)
        //      1) Object is an array (arrays treated specially by the EE)
        //      2) Object is some other variable sized object (e.g. String)
        //      3) Class Size can be determined beforehand (normal case)
        // In the first case, we need to call a NEWOBJ helper (multinewarray)
        // in the second case we call the constructor with a '0' this pointer
        // In the third case we alloc the memory, then call the constuctor
        
        // 省略部分代码......
        // 创建一个GT_ALLOCOBJ类型的GenTree(语句树)节点，用于分配内存
        op1 = gtNewAllocObjNode(info.compCompHnd->getNewHelper(&resolvedToken, info.compMethodHnd),
                                resolvedToken.hClass, TYP_REF, op1);
        
        // 省略部分代码......
        // 因为GT_ALLOCOBJ仅负责分配内存，我们还需要调用构造函数
        // 这里复用了CEE_CALL指令的处理
        goto CALL;
 
        // 省略部分代码......
        CALL: // memberRef should be set.
        
            // 省略部分代码......
            // 创建一个GT_CALL类型的GenTree(语句树)节点，用于调用构造函数
            callTyp = impImportCall(opcode, &resolvedToken, constraintCall ? &constrainedResolvedToken : nullptr,
                                    newObjThisPtr, prefixFlags, &callInfo, opcodeOffs);

CorInfoHelpFunc CEEInfo::getNewHelper(CORINFO_RESOLVED_TOKEN * pResolvedToken, CORINFO_METHOD_HANDLE callerHandle)
{
    // 省略部分代码......
    MethodTable* pMT = VMClsHnd.AsMethodTable();
    
    // 省略部分代码......
    result = getNewHelperStatic(pMT);
    
    // 省略部分代码......
    return result;
}

CorInfoHelpFunc CEEInfo::getNewHelperStatic(MethodTable * pMT)
{
    // 省略部分代码......
    // 这里有很多判断，例如是否是Com对象或拥有析构函数，默认会返回CORINFO_HELP_NEWFAST
    // Slow helper is the default
    CorInfoHelpFunc helper = CORINFO_HELP_NEWFAST;
    
    // 省略部分代码......
    return helper;
}

void ObjectAllocator::DoPhase()
{
    // 省略部分代码......
    MorphAllocObjNodes();
}

void ObjectAllocator::MorphAllocObjNodes()
{
    // 省略部分代码......
    for (GenTreeStmt* stmt = block->firstStmt(); stmt; stmt = stmt->gtNextStmt)
    {
        // 省略部分代码......
        bool canonicalAllocObjFound = false;
 
        // 省略部分代码......
        if (op2->OperGet() == GT_ALLOCOBJ)
            canonicalAllocObjFound = true;
        
        // 省略部分代码......
        if (canonicalAllocObjFound)
        {
            // 省略部分代码......
            op2 = MorphAllocObjNodeIntoHelperCall(asAllocObj);
        }
    }
}

// MorphAllocObjNodeIntoHelperCall: Morph a GT_ALLOCOBJ node into an
//                                  allocation helper call.
GenTreePtr ObjectAllocator::MorphAllocObjNodeIntoHelperCall(GenTreeAllocObj* allocObj)
{
    // 省略部分代码......
    GenTreePtr helperCall = comp->fgMorphIntoHelperCall(allocObj, allocObj->gtNewHelper, comp->gtNewArgList(op1));
    return helperCall;
}

GenTreePtr Compiler::fgMorphIntoHelperCall(GenTreePtr tree, int helper, GenTreeArgList* args)
{
    tree->ChangeOper(GT_CALL);
    tree->gtFlags |= GTF_CALL;
    
    // 省略部分代码......
    // 如果GT_ALLOCOBJ中帮助函数的标识是CORINFO_HELP_NEWFAST，这里就是eeFindHelper(CORINFO_HELP_NEWFAST)
    // eeFindHelper会把帮助函数的表示转换为帮助函数的句柄
    tree->gtCall.gtCallType            = CT_HELPER;
    tree->gtCall.gtCallMethHnd         = eeFindHelper(helper);
    
    // 省略部分代码......
    tree = fgMorphArgs(tree->AsCall());
    return tree;
}

// Produce code for a GT_CALL node
void CodeGen::genCallInstruction(GenTreePtr node)
{
    // 省略部分代码......
    if (callType == CT_HELPER)
    {
        // 把句柄转换为帮助函数的句柄，默认是CORINFO_HELP_NEWFAST
        helperNum = compiler->eeGetHelperNum(methHnd);
        // 获取指向帮助函数的指针
        // 这里等于调用compiler->compGetHelperFtn(CORINFO_HELP_NEWFAST, ...)
        addr = compiler->compGetHelperFtn(helperNum, (void**)&pAddr);
    }
    else
    {
        // 调用普通函数
        // Direct call to a non-virtual user function.
        addr = call->gtDirectCallAddress;
    }
}

void* Compiler::compGetHelperFtn(CorInfoHelpFunc ftnNum,        /* IN  */
                                 void**          ppIndirection) /* OUT */
{
    // 省略部分代码......
    addr = info.compCompHnd->getHelperFtn(ftnNum, ppIndirection);
    return addr;
}

void* CEEJitInfo::getHelperFtn(CorInfoHelpFunc    ftnNum,         /* IN  */
                               void **            ppIndirection)  /* OUT */
{
    // 省略部分代码......
    pfnHelper = hlpDynamicFuncTable[dynamicFtnNum].pfnHelper;
 
    // 省略部分代码......
    result = (LPVOID)GetEEFuncEntryPoint(pfnHelper);
    return result;
}

JITHELPER(CORINFO_HELP_NEWFAST,                     JIT_New,    CORINFO_HELP_SIG_REG_ONLY)

HCIMPL1(Object*, JIT_New, CORINFO_CLASS_HANDLE typeHnd_)
{
    // 省略部分代码......
    MethodTable *pMT = typeHnd.AsMethodTable();
    
    // 省略部分代码......
    // AllocateObject是分配内存的函数，这个函数供CoreCLR的内部代码或非托管代码调用
    // JIT_New是对这个函数的一个包装，仅供JIT生成的代码调用
    newobj = AllocateObject(pMT);
    
    // 省略部分代码......
    return(OBJECTREFToObject(newobj));
}
HCIMPLEND

/*****************************************************************************
 *  Import the instr for the given basic block
 */
void Compiler::impImportBlockCode(BasicBlock* block)
{
    // 省略部分代码......
    // 处理CEE_NEWARR指令
    case CEE_NEWARR:
 
        // 省略部分代码......
        args = gtNewArgList(op1, op2);
 
        // 生成GT_CALL类型的节点调用帮助函数
        /* Create a call to 'new' */
        // Note that this only works for shared generic code because the same helper is used for all
        // reference array types
        op1 = gtNewHelperCallNode(info.compCompHnd->getNewArrHelper(resolvedToken.hClass), TYP_REF, 0, args);
}

/***********************************************************************/
// <REVIEW> this only works for shared generic code because all the
// helpers are actually the same. If they were different then things might
// break because the same helper would end up getting used for different but
// representation-compatible arrays (e.g. one with a default constructor
// and one without) </REVIEW>
CorInfoHelpFunc CEEInfo::getNewArrHelper (CORINFO_CLASS_HANDLE arrayClsHnd)
{
    // 省略部分代码......
    TypeHandle arrayType(arrayClsHnd);
    result = getNewArrHelperStatic(arrayType);
    
    // 省略部分代码......
    return result;
}

CorInfoHelpFunc CEEInfo::getNewArrHelperStatic(TypeHandle clsHnd)
{
    // 省略部分代码......
    if (CorTypeInfo::IsGenericVariable(elemType))
    {
        result = CORINFO_HELP_NEWARR_1_OBJ;
    }
    else if (CorTypeInfo::IsObjRef(elemType))
    {
        // It is an array of object refs
        result = CORINFO_HELP_NEWARR_1_OBJ;
    }
    else
    {
        // These cases always must use the slow helper
        // 省略部分代码......
    }
    return result;
{

DYNAMICJITHELPER(CORINFO_HELP_NEWARR_1_OBJ, JIT_NewArr1,CORINFO_HELP_SIG_REG_ONLY)

HCIMPL2(Object*, JIT_NewArr1, CORINFO_CLASS_HANDLE arrayTypeHnd_, INT_PTR size)
{
    // 省略部分代码......
    CorElementType elemType = pArrayClassRef->GetArrayElementTypeHandle().GetSignatureCorElementType();
    
    if (CorTypeInfo::IsPrimitiveType(elemType)
    {
        // 省略部分代码......
        // 如果类型是基元类型(int, double等)则使用更快的FastAllocatePrimitiveArray函数
        newArray = FastAllocatePrimitiveArray(pArrayClassRef->GetMethodTable(), static_cast<DWORD>(size), bAllocateInLargeHeap);
    }
    else
    {
        // 省略部分代码......
        // 默认使用AllocateArrayEx函数
        INT32 size32 = (INT32)size;
        newArray = AllocateArrayEx(typeHnd, &size32, 1);
    }
    
    // 省略部分代码......
    return(OBJECTREFToObject(newArray));
}
HCIMPLEND

/*****************************************************************************
 *  lvaAssignVirtualFrameOffsetsToLocals() : Assign virtual stack offsets to
 *  locals, temps, and anything else.  These will all be negative offsets
 *  (stack grows down) relative to the virtual '0'/return address
 */
void Compiler::lvaAssignVirtualFrameOffsetsToLocals()
{
    // 省略部分代码......
    for (cur = 0; alloc_order[cur]; cur++)
    {
        // 省略部分代码......
        for (lclNum = 0, varDsc = lvaTable; lclNum < lvaCount; lclNum++, varDsc++)
        {
            // 省略部分代码......
            // Reserve the stack space for this variable
            stkOffs = lvaAllocLocalAndSetVirtualOffset(lclNum, lvaLclSize(lclNum), stkOffs);
        }
    }
}

int Compiler::lvaAllocLocalAndSetVirtualOffset(unsigned lclNum, unsigned size, int stkOffs)
{
    // 省略部分代码......
    /* Reserve space on the stack by bumping the frame size */
    lvaIncrementFrameSize(size);
    stkOffs -= size;
    lvaTable[lclNum].lvStkOffs = stkOffs;
 
    // 省略部分代码......
    return stkOffs;
}

inline void Compiler::lvaIncrementFrameSize(unsigned size)
{
    if (size > MAX_FrameSize || compLclFrameSize + size > MAX_FrameSize)
    {
        BADCODE("Frame size overflow");
    }
    compLclFrameSize += size;
}

void CodeGen::genFnProlog()
{
    // 省略部分代码......
    // ARM64和其他平台的调用时机不一样，但是参数一样
    genAllocLclFrame(compiler->compLclFrameSize, initReg, &initRegZeroed, intRegState.rsCalleeRegArgMaskLiveIn);
}

/*-----------------------------------------------------------------------------
 *
 *  Probe the stack and allocate the local stack frame: subtract from SP.
 *  On ARM64, this only does the probing; allocating the frame is done when callee-saved registers are saved.
 */
void CodeGen::genAllocLclFrame(unsigned frameSize, regNumber initReg, bool* pInitRegZeroed, regMaskTP maskArgRegsLiveIn)
{
    // 省略部分代码......
    //      sub esp, frameSize   6
    inst_RV_IV(INS_sub, REG_SPBASE, frameSize, EA_PTRSIZE);
}

// AllocateObject will throw OutOfMemoryException so don't need to check
// for NULL return value from it.
OBJECTREF AllocateObject(MethodTable *pMT
#ifdef FEATURE_COMINTEROP
                         , bool fHandleCom
#endif
    )
{
    // 省略部分代码......
    Object     *orObject = NULL;
    
    // 如果类型有重要的析构函数，预编译所有相关的函数(详细可以搜索CER)
    // 同一个类型只会处理一次
    if (pMT->HasCriticalFinalizer())
        PrepareCriticalFinalizerObject(pMT);
 
    // 省略部分代码......
    DWORD baseSize = pMT->GetBaseSize();
 
    // 调用gc的帮助函数分配内存，如果需要向8对齐则调用AllocAlign8，否则调用Alloc
    if (pMT->RequiresAlign8())
    {
        // 省略部分代码......
        orObject = (Object *) AllocAlign8(baseSize,
                                          pMT->HasFinalizer(),
                                          pMT->ContainsPointers(),
                                          pMT->IsValueType());
    }
    else
    {
        orObject = (Object *) Alloc(baseSize,
                                    pMT->HasFinalizer(),
                                    pMT->ContainsPointers());
    }
 
    // 检查同步块索引(SyncBlock)是否为0
    // verify zero'd memory (at least for sync block)
    _ASSERTE( orObject->HasEmptySyncBlockInfo() );
 
    // 设置类型信息(MethodTable)
    if ((baseSize >= LARGE_OBJECT_SIZE))
    {
        orObject->SetMethodTableForLargeObject(pMT);
        GCHeap::GetGCHeap()->PublishObject((BYTE*)orObject);
    }
    else
    {
        orObject->SetMethodTable(pMT);
    }
    
    // 省略部分代码......
    return UNCHECKED_OBJECTREF_TO_OBJECTREF(oref);
}

// There are only three ways to get into allocate an object.
//     * Call optimized helpers that were generated on the fly. This is how JIT compiled code does most
//         allocations, however they fall back code:Alloc, when for all but the most common code paths. These
//         helpers are NOT used if profiler has asked to track GC allocation (see code:TrackAllocations)
//     * Call code:Alloc - When the jit helpers fall back, or we do allocations within the runtime code
//         itself, we ultimately call here.
//     * Call code:AllocLHeap - Used very rarely to force allocation to be on the large object heap.
//     
// While this is a choke point into allocating an object, it is primitive (it does not want to know about
// MethodTable and thus does not initialize that poitner. It also does not know if the object is finalizable
// or contains pointers. Thus we quickly wrap this function in more user-friendly ones that know about
// MethodTables etc. (see code:FastAllocatePrimitiveArray code:AllocateArrayEx code:AllocateObject)
// 
// You can get an exhaustive list of code sites that allocate GC objects by finding all calls to
// code:ProfilerObjectAllocatedCallback (since the profiler has to hook them all).
inline Object* Alloc(size_t size, BOOL bFinalize, BOOL bContainsPointers )
{
    // 省略部分代码......
    // We don't want to throw an SO during the GC, so make sure we have plenty
    // of stack before calling in.
    INTERIOR_STACK_PROBE_FOR(GetThread(), static_cast<unsigned>(DEFAULT_ENTRY_PROBE_AMOUNT * 1.5));
    if (GCHeapUtilities::UseAllocationContexts())
        retVal = GCHeapUtilities::GetGCHeap()->Alloc(GetThreadAllocContext(), size, flags);
    else
        retVal = GCHeapUtilities::GetGCHeap()->Alloc(size, flags);
 
    if (!retVal)
    {
        ThrowOutOfMemory();
    }
 
    END_INTERIOR_STACK_PROBE;
    return retVal;
}

/*
 * Allocates a single dimensional array of primitive types.
 */
OBJECTREF   FastAllocatePrimitiveArray(MethodTable* pMT, DWORD cElements, BOOL bAllocateInLargeHeap)
{
    // 省略部分代码......
    // 检查元素数量不能大于一个硬性限制
    SIZE_T componentSize = pMT->GetComponentSize();
    if (cElements > MaxArrayLength(componentSize))
        ThrowOutOfMemory();
 
    // 检查总大小不能溢出
    S_SIZE_T safeTotalSize = S_SIZE_T(cElements) * S_SIZE_T(componentSize) + S_SIZE_T(pMT->GetBaseSize());
    if (safeTotalSize.IsOverflow())
        ThrowOutOfMemory();
 
    size_t totalSize = safeTotalSize.Value();
 
    // 省略部分代码......
    // 调用gc的帮助函数分配内存
    ArrayBase* orObject;
    if (bAllocateInLargeHeap)
    {
        orObject = (ArrayBase*) AllocLHeap(totalSize, FALSE, FALSE);
    }
    else 
    {
        ArrayTypeDesc *pArrayR8TypeDesc = g_pPredefinedArrayTypes[ELEMENT_TYPE_R8];
        if (DATA_ALIGNMENT < sizeof(double) && pArrayR8TypeDesc != NULL && pMT == pArrayR8TypeDesc->GetMethodTable() && totalSize < LARGE_OBJECT_SIZE - MIN_OBJECT_SIZE) 
        {
            // Creation of an array of doubles, not in the large object heap.
            // We want to align the doubles to 8 byte boundaries, but the GC gives us pointers aligned
            // to 4 bytes only (on 32 bit platforms). To align, we ask for 12 bytes more to fill with a
            // dummy object.
            // If the GC gives us a 8 byte aligned address, we use it for the array and place the dummy
            // object after the array, otherwise we put the dummy object first, shifting the base of
            // the array to an 8 byte aligned address.
            // Note: on 64 bit platforms, the GC always returns 8 byte aligned addresses, and we don't
            // execute this code because DATA_ALIGNMENT < sizeof(double) is false.
 
            _ASSERTE(DATA_ALIGNMENT == sizeof(double)/2);
            _ASSERTE((MIN_OBJECT_SIZE % sizeof(double)) == DATA_ALIGNMENT);   // used to change alignment
            _ASSERTE(pMT->GetComponentSize() == sizeof(double));
            _ASSERTE(g_pObjectClass->GetBaseSize() == MIN_OBJECT_SIZE);
            _ASSERTE(totalSize < totalSize + MIN_OBJECT_SIZE);
            orObject = (ArrayBase*) Alloc(totalSize + MIN_OBJECT_SIZE, FALSE, FALSE);
 
            Object *orDummyObject;
            if((size_t)orObject % sizeof(double))
            {
                orDummyObject = orObject;
                orObject = (ArrayBase*) ((size_t)orObject + MIN_OBJECT_SIZE);
            }
            else
            {
                orDummyObject = (Object*) ((size_t)orObject + totalSize);
            }
            _ASSERTE(((size_t)orObject % sizeof(double)) == 0);
            orDummyObject->SetMethodTable(g_pObjectClass);
        }
        else
        {
            orObject = (ArrayBase*) Alloc(totalSize, FALSE, FALSE);
            bPublish = (totalSize >= LARGE_OBJECT_SIZE);
        }
    }
 
    // 设置类型信息(MethodTable)
    // Initialize Object
    orObject->SetMethodTable( pMT );
    _ASSERTE(orObject->GetMethodTable() != NULL);
    
    // 设置数组长度
    orObject->m_NumComponents = cElements;
 
    // 省略部分代码......
    return( ObjectToOBJECTREF((Object*)orObject) );
}

// Handles arrays of arbitrary dimensions
//
// If dwNumArgs is set to greater than 1 for a SZARRAY this function will recursively 
// allocate sub-arrays and fill them in.  
//
// For arrays with lower bounds, pBounds is <lower bound 1>, <count 1>, <lower bound 2>, ...
OBJECTREF AllocateArrayEx(TypeHandle arrayType, INT32 *pArgs, DWORD dwNumArgs, BOOL bAllocateInLargeHeap 
                          DEBUG_ARG(BOOL bDontSetAppDomain))
{
    // 省略部分代码......
    ArrayBase * orArray = NULL;
 
    // 省略部分代码......
    // 调用gc的帮助函数分配内存
    if (bAllocateInLargeHeap)
    {
        orArray = (ArrayBase *) AllocLHeap(totalSize, FALSE, pArrayMT->ContainsPointers());
        // 设置类型信息(MethodTable)
        orArray->SetMethodTableForLargeObject(pArrayMT);
    }
    else
    {
#ifdef FEATURE_64BIT_ALIGNMENT
        MethodTable *pElementMT = arrayDesc->GetTypeParam().GetMethodTable();
        if (pElementMT->RequiresAlign8() && pElementMT->IsValueType())
        {
            // This platform requires that certain fields are 8-byte aligned (and the runtime doesn't provide
            // this guarantee implicitly, e.g. on 32-bit platforms). Since it's the array payload, not the
            // header that requires alignment we need to be careful. However it just so happens that all the
            // cases we care about (single and multi-dim arrays of value types) have an even number of DWORDs
            // in their headers so the alignment requirements for the header and the payload are the same.
            _ASSERTE(((pArrayMT->GetBaseSize() - SIZEOF_OBJHEADER) & 7) == 0);
            orArray = (ArrayBase *) AllocAlign8(totalSize, FALSE, pArrayMT->ContainsPointers(), FALSE);
        }
        else
#endif
        {
            orArray = (ArrayBase *) Alloc(totalSize, FALSE, pArrayMT->ContainsPointers());
        }
        // 设置类型信息(MethodTable)
        orArray->SetMethodTable(pArrayMT);
    }
    
    // 设置数组长度
    // Initialize Object
    orArray->m_NumComponents = cElements;
 
    // 省略部分代码......
    return ObjectToOBJECTREF((Object *) orArray);
}

00007FF919570B53  mov         rcx,7FF9194161A0h  // 设置第一个参数(指向MethodTable的指针)
00007FF919570B5D  call        00007FF97905E350  // 调用分配内存的函数，默认是JIT_New
00007FF919570B62  mov         qword ptr [rbp+38h],rax  // 把地址设置到临时变量(rbp+38)
00007FF919570B66  mov         r8,37BFC73068h  
00007FF919570B70  mov         r8,qword ptr [r8]  // 设置第三个参数("hello")
00007FF919570B73  mov         rcx,qword ptr [rbp+38h]  // 设置第一个参数(this)
00007FF919570B77  mov         edx,12345678h  // 设置第二个参数(0x12345678)
00007FF919570B7C  call        00007FF9195700B8  // 调用构造函数
00007FF919570B81  mov         rcx,qword ptr [rbp+38h]  
00007FF919570B85  mov         qword ptr [rbp+50h],rcx  // 把临时变量复制到myClass变量中

; IN: rcx: MethodTable*
; OUT: rax: new object
LEAF_ENTRY JIT_TrialAllocSFastMP_InlineGetThread, _TEXT
        mov     edx, [rcx + OFFSET__MethodTable__m_BaseSize] // 从MethodTable获取需要分配的内存大小，放到edx
 
        ; m_BaseSize is guaranteed to be a multiple of 8.
        PATCHABLE_INLINE_GETTHREAD r11, JIT_TrialAllocSFastMP_InlineGetThread__PatchTLSOffset
        mov     r10, [r11 + OFFSET__Thread__m_alloc_context__alloc_limit] // 获取从TLS分配内存的限制地址，放到r10
        mov     rax, [r11 + OFFSET__Thread__m_alloc_context__alloc_ptr] // 获取从TLS分配内存的当前地址，放到rax
 
        add     rdx, rax // 地址 + 需要分配的内存大小，放到rdx
 
        cmp     rdx, r10 // 判断是否可以从TLS分配内存
        ja      AllocFailed // if (rdx > r10)
 
        mov     [r11 + OFFSET__Thread__m_alloc_context__alloc_ptr], rdx // 设置新的当前地址
        mov     [rax], rcx // 给刚刚分配到的内存设置MethodTable
 
ifdef _DEBUG
        call    DEBUG_TrialAllocSetAppDomain_NoScratchArea
endif ; _DEBUG
 
        ret // 分配成功，返回
 
    AllocFailed:
        jmp     JIT_NEW // 分配失败，调用默认的JIT_New函数
LEAF_END JIT_TrialAllocSFastMP_InlineGetThread, _TEXT

00007FF919570B93  mov         rcx,7FF9195B4CFAh  // 设置第一个参数(指向MethodTable的指针)
00007FF919570B9D  mov         edx,378h  // 设置第二个参数(数组的大小)
00007FF919570BA2  call        00007FF97905E440  // 调用分配内存的函数，默认是JIT_NewArr1
00007FF919570BA7  mov         qword ptr [rbp+30h],rax  // 设置到临时变量(rbp+30)
00007FF919570BAB  mov         rcx,qword ptr [rbp+30h]  
00007FF919570BAF  mov         qword ptr [rbp+48h],rcx  // 把临时变量复制到myArray变量中