C++ Use::Def方法代码示例

void Rationalizer::RewriteAddress(LIR::Use& use)
{
    assert(use.IsInitialized());

    GenTreeUnOp* address = use.Def()->AsUnOp();
    assert(address->OperGet() == GT_ADDR);

    GenTree*   location   = address->gtGetOp1();
    genTreeOps locationOp = location->OperGet();

    if (location->IsLocal())
    {
// We are changing the child from GT_LCL_VAR TO GT_LCL_VAR_ADDR.
// Therefore gtType of the child needs to be changed to a TYP_BYREF
#ifdef DEBUG
        if (locationOp == GT_LCL_VAR)
        {
            JITDUMP("Rewriting GT_ADDR(GT_LCL_VAR) to GT_LCL_VAR_ADDR:\n");
        }
        else
        {
            assert(locationOp == GT_LCL_FLD);
            JITDUMP("Rewriting GT_ADDR(GT_LCL_FLD) to GT_LCL_FLD_ADDR:\n");
        }
#endif // DEBUG

        location->SetOper(addrForm(locationOp));
        location->gtType = TYP_BYREF;
        copyFlags(location, address, GTF_ALL_EFFECT);

        use.ReplaceWith(comp, location);
        BlockRange().Remove(address);
    }
    else if (locationOp == GT_CLS_VAR)
    {
        location->SetOper(GT_CLS_VAR_ADDR);
        location->gtType = TYP_BYREF;
        copyFlags(location, address, GTF_ALL_EFFECT);

        use.ReplaceWith(comp, location);
        BlockRange().Remove(address);

        JITDUMP("Rewriting GT_ADDR(GT_CLS_VAR) to GT_CLS_VAR_ADDR:\n");
    }
    else if (location->OperIsIndir())
    {
        use.ReplaceWith(comp, location->gtGetOp1());
        BlockRange().Remove(location);
        BlockRange().Remove(address);

        JITDUMP("Rewriting GT_ADDR(GT_IND(X)) to X:\n");
    }

    DISPTREERANGE(BlockRange(), use.Def());
    JITDUMP("\n");
}

void Rationalizer::RewriteAssignment(LIR::Use& use)
{
    assert(use.IsInitialized());

    GenTreeOp* assignment = use.Def()->AsOp();
    assert(assignment->OperGet() == GT_ASG);

    GenTree* location = assignment->gtGetOp1();
    GenTree* value    = assignment->gtGetOp2();

    genTreeOps locationOp = location->OperGet();
    switch (locationOp)
    {
        case GT_LCL_VAR:
        case GT_LCL_FLD:
        case GT_REG_VAR:
        case GT_PHI_ARG:
            RewriteAssignmentIntoStoreLclCore(assignment, location, value, locationOp);
            BlockRange().Remove(location);
            break;

        case GT_IND:
        {
            GenTreeStoreInd* store =
                new (comp, GT_STOREIND) GenTreeStoreInd(location->TypeGet(), location->gtGetOp1(), value);

            copyFlags(store, assignment, GTF_ALL_EFFECT);
            copyFlags(store, location, GTF_IND_FLAGS);

            if (assignment->IsReverseOp())
            {
                store->gtFlags |= GTF_REVERSE_OPS;
            }

            // TODO: JIT dump

            // Remove the GT_IND node and replace the assignment node with the store
            BlockRange().Remove(location);
            BlockRange().InsertBefore(assignment, store);
            use.ReplaceWith(comp, store);
            BlockRange().Remove(assignment);
        }
        break;

        case GT_CLS_VAR:
        {
            location->SetOper(GT_CLS_VAR_ADDR);
            location->gtType = TYP_BYREF;

            assignment->SetOper(GT_STOREIND);

            // TODO: JIT dump
        }
        break;

        default:
            unreached();
            break;
    }
}

// Rewrite a SIMD indirection as GT_IND(GT_LEA(obj.op1)), or as a simple
// lclVar if possible.
//
// Arguments:
//    use      - A use reference for a block node
//    keepBlk  - True if this should remain a block node if it is not a lclVar
//
// Return Value:
//    None.
//
// TODO-1stClassStructs: These should be eliminated earlier, once we can handle
// lclVars in all the places that used to have GT_OBJ.
//
void Rationalizer::RewriteSIMDOperand(LIR::Use& use, bool keepBlk)
{
#ifdef FEATURE_SIMD
    // No lowering is needed for non-SIMD nodes, so early out if featureSIMD is not enabled.
    if (!comp->featureSIMD)
    {
        return;
    }

    GenTree* tree = use.Def();
    if (!tree->OperIsIndir())
    {
        return;
    }
    var_types simdType = tree->TypeGet();

    if (!varTypeIsSIMD(simdType))
    {
        return;
    }

    // If we have GT_IND(GT_LCL_VAR_ADDR) and the GT_LCL_VAR_ADDR is TYP_BYREF/TYP_I_IMPL,
    // and the var is a SIMD type, replace the expression by GT_LCL_VAR.
    GenTree* addr = tree->AsIndir()->Addr();
    if (addr->OperIsLocalAddr() && comp->isAddrOfSIMDType(addr))
    {
        BlockRange().Remove(tree);

        addr->SetOper(loadForm(addr->OperGet()));
        addr->gtType = simdType;
        use.ReplaceWith(comp, addr);
    }
    else if ((addr->OperGet() == GT_ADDR) && (addr->gtGetOp1()->OperGet() == GT_SIMD))
    {
        // if we have GT_IND(GT_ADDR(GT_SIMD)), remove the GT_IND(GT_ADDR()), leaving just the GT_SIMD.
        BlockRange().Remove(tree);
        BlockRange().Remove(addr);

        use.ReplaceWith(comp, addr->gtGetOp1());
    }
    else if (!keepBlk)
    {
        tree->SetOper(GT_IND);
        tree->gtType = simdType;
    }
#endif // FEATURE_SIMD
}

// Rewrite GT_OBJ of SIMD Vector as GT_IND(GT_LEA(obj.op1)) of a SIMD type.
//
// Arguments:
//    ppTree      - A pointer-to-a-pointer for the GT_OBJ
//    fgWalkData  - A pointer to tree walk data providing the context
//
// Return Value:
//    None.
//
// TODO-Cleanup: Once SIMD types are plumbed through the frontend, this will no longer
// be required.
//
void Rationalizer::RewriteObj(LIR::Use& use)
{
#ifdef FEATURE_SIMD
    GenTreeObj* obj = use.Def()->AsObj();

// For UNIX struct passing, we can have Obj nodes for arguments.
// For other cases, we should never see a non-SIMD type here.
#ifdef FEATURE_UNIX_AMD64_STRUCT_PASSING
    if (!varTypeIsSIMD(obj))
    {
        return;
    }
#endif // FEATURE_UNIX_AMD64_STRUCT_PASSING

    // Should come here only if featureSIMD is enabled
    noway_assert(comp->featureSIMD);

    // We should only call this with a SIMD type.
    noway_assert(varTypeIsSIMD(obj));
    var_types simdType = obj->TypeGet();

    // If the operand of obj is a GT_ADDR(GT_LCL_VAR) and LclVar is known to be a SIMD type,
    // replace obj by GT_LCL_VAR.
    GenTree* srcAddr = obj->gtGetOp1();
    if (srcAddr->OperIsLocalAddr() && comp->isAddrOfSIMDType(srcAddr))
    {
        BlockRange().Remove(obj);

        srcAddr->SetOper(loadForm(srcAddr->OperGet()));
        srcAddr->gtType = simdType;
        use.ReplaceWith(comp, srcAddr);
    }
    else
    {
        obj->SetOper(GT_IND);
        obj->gtType = simdType;
    }
#else
    // we should never reach without feature SIMD
    assert(!"Unexpected obj during rationalization\n");
    unreached();
#endif
}

// Rewrite a SIMD indirection as GT_IND(GT_LEA(obj.op1)), or as a simple
// lclVar if possible.
//
// Arguments:
//    use      - A use reference for a block node
//    keepBlk  - True if this should remain a block node if it is not a lclVar
//
// Return Value:
//    None.
//
// TODO-1stClassStructs: These should be eliminated earlier, once we can handle
// lclVars in all the places that used to have GT_OBJ.
//
void Rationalizer::RewriteSIMDOperand(LIR::Use& use, bool keepBlk)
{
#ifdef FEATURE_SIMD
    // No lowering is needed for non-SIMD nodes, so early out if featureSIMD is not enabled.
    if (!comp->featureSIMD)
    {
        return;
    }

    GenTree* tree = use.Def();
    if (!tree->OperIsIndir())
    {
        return;
    }
    var_types simdType = tree->TypeGet();

    if (!varTypeIsSIMD(simdType))
    {
        return;
    }

    // If the operand of is a GT_ADDR(GT_LCL_VAR) and LclVar is known to be of simdType,
    // replace obj by GT_LCL_VAR.
    GenTree* addr = tree->AsIndir()->Addr();
    if (addr->OperIsLocalAddr() && comp->isAddrOfSIMDType(addr))
    {
        BlockRange().Remove(tree);

        addr->SetOper(loadForm(addr->OperGet()));
        addr->gtType = simdType;
        use.ReplaceWith(comp, addr);
    }
    else if (!keepBlk)
    {
        tree->SetOper(GT_IND);
        tree->gtType = simdType;
    }
#endif // FEATURE_SIMD
}

Compiler::fgWalkResult Rationalizer::RewriteNode(GenTree** useEdge, ArrayStack<GenTree*>& parentStack)
{
    assert(useEdge != nullptr);

    GenTree* node = *useEdge;
    assert(node != nullptr);

#ifdef DEBUG
    const bool isLateArg = (node->gtFlags & GTF_LATE_ARG) != 0;
#endif

    // First, remove any preceeding list nodes, which are not otherwise visited by the tree walk.
    //
    // NOTE: GT_FIELD_LIST head nodes, and GT_LIST nodes used by phi nodes will in fact be visited.
    for (GenTree* prev = node->gtPrev; prev != nullptr && prev->OperIsAnyList() && !(prev->OperIsFieldListHead());
         prev          = node->gtPrev)
    {
        BlockRange().Remove(prev);
    }

    // In addition, remove the current node if it is a GT_LIST node that is not an aggregate.
    if (node->OperIsAnyList())
    {
        GenTreeArgList* list = node->AsArgList();
        if (!list->OperIsFieldListHead())
        {
            BlockRange().Remove(list);
        }
        return Compiler::WALK_CONTINUE;
    }

    LIR::Use use;
    if (parentStack.Height() < 2)
    {
        use = LIR::Use::GetDummyUse(BlockRange(), *useEdge);
    }
    else
    {
        use = LIR::Use(BlockRange(), useEdge, parentStack.Index(1));
    }

    assert(node == use.Def());
    switch (node->OperGet())
    {
        case GT_ASG:
            RewriteAssignment(use);
            break;

        case GT_BOX:
            // GT_BOX at this level just passes through so get rid of it
            use.ReplaceWith(comp, node->gtGetOp1());
            BlockRange().Remove(node);
            break;

        case GT_ADDR:
            RewriteAddress(use);
            break;

        case GT_IND:
            // Clear the `GTF_IND_ASG_LHS` flag, which overlaps with `GTF_IND_REQ_ADDR_IN_REG`.
            node->gtFlags &= ~GTF_IND_ASG_LHS;

            if (varTypeIsSIMD(node))
            {
                RewriteSIMDOperand(use, false);
            }
            else
            {
                // Due to promotion of structs containing fields of type struct with a
                // single scalar type field, we could potentially see IR nodes of the
                // form GT_IND(GT_ADD(lclvarAddr, 0)) where 0 is an offset representing
                // a field-seq. These get folded here.
                //
                // TODO: This code can be removed once JIT implements recursive struct
                // promotion instead of lying about the type of struct field as the type
                // of its single scalar field.
                GenTree* addr = node->AsIndir()->Addr();
                if (addr->OperGet() == GT_ADD && addr->gtGetOp1()->OperGet() == GT_LCL_VAR_ADDR &&
                    addr->gtGetOp2()->IsIntegralConst(0))
                {
                    GenTreeLclVarCommon* lclVarNode = addr->gtGetOp1()->AsLclVarCommon();
                    unsigned             lclNum     = lclVarNode->GetLclNum();
                    LclVarDsc*           varDsc     = comp->lvaTable + lclNum;
                    if (node->TypeGet() == varDsc->TypeGet())
                    {
                        JITDUMP("Rewriting GT_IND(GT_ADD(LCL_VAR_ADDR,0)) to LCL_VAR\n");
                        lclVarNode->SetOper(GT_LCL_VAR);
                        lclVarNode->gtType = node->TypeGet();
                        use.ReplaceWith(comp, lclVarNode);
                        BlockRange().Remove(addr);
                        BlockRange().Remove(addr->gtGetOp2());
                        BlockRange().Remove(node);
                    }
                }
            }
            break;

        case GT_NOP:
            // fgMorph sometimes inserts NOP nodes between defs and uses
            // supposedly 'to prevent constant folding'. In this case, remove the
//.........这里部分代码省略.........

void Rationalizer::RewriteAssignment(LIR::Use& use)
{
    assert(use.IsInitialized());

    GenTreeOp* assignment = use.Def()->AsOp();
    assert(assignment->OperGet() == GT_ASG);

    GenTree* location = assignment->gtGetOp1();
    GenTree* value    = assignment->gtGetOp2();

    genTreeOps locationOp = location->OperGet();

    if (assignment->OperIsBlkOp())
    {
#ifdef FEATURE_SIMD
        if (varTypeIsSIMD(location) && assignment->OperIsInitBlkOp())
        {
            if (location->OperGet() == GT_LCL_VAR)
            {
                var_types simdType = location->TypeGet();
                GenTree*  initVal  = assignment->gtOp.gtOp2;
                var_types baseType = comp->getBaseTypeOfSIMDLocal(location);
                if (baseType != TYP_UNKNOWN)
                {
                    GenTreeSIMD* simdTree = new (comp, GT_SIMD)
                        GenTreeSIMD(simdType, initVal, SIMDIntrinsicInit, baseType, genTypeSize(simdType));
                    assignment->gtOp.gtOp2 = simdTree;
                    value                  = simdTree;
                    initVal->gtNext        = simdTree;
                    simdTree->gtPrev       = initVal;

                    simdTree->gtNext = location;
                    location->gtPrev = simdTree;
                }
            }
        }
#endif // FEATURE_SIMD
        if ((location->TypeGet() == TYP_STRUCT) && !assignment->IsPhiDefn() && !value->IsMultiRegCall())
        {
            if ((location->OperGet() == GT_LCL_VAR))
            {
                // We need to construct a block node for the location.
                // Modify lcl to be the address form.
                location->SetOper(addrForm(locationOp));
                LclVarDsc* varDsc     = &(comp->lvaTable[location->AsLclVarCommon()->gtLclNum]);
                location->gtType      = TYP_BYREF;
                GenTreeBlk*  storeBlk = nullptr;
                unsigned int size     = varDsc->lvExactSize;

                if (varDsc->lvStructGcCount != 0)
                {
                    CORINFO_CLASS_HANDLE structHnd = varDsc->lvVerTypeInfo.GetClassHandle();
                    GenTreeObj*          objNode   = comp->gtNewObjNode(structHnd, location)->AsObj();
                    unsigned int         slots = (unsigned)(roundUp(size, TARGET_POINTER_SIZE) / TARGET_POINTER_SIZE);

                    objNode->SetGCInfo(varDsc->lvGcLayout, varDsc->lvStructGcCount, slots);
                    objNode->ChangeOper(GT_STORE_OBJ);
                    objNode->SetData(value);
                    comp->fgMorphUnsafeBlk(objNode);
                    storeBlk = objNode;
                }
                else
                {
                    storeBlk = new (comp, GT_STORE_BLK) GenTreeBlk(GT_STORE_BLK, TYP_STRUCT, location, value, size);
                }
                storeBlk->gtFlags |= (GTF_REVERSE_OPS | GTF_ASG);
                storeBlk->gtFlags |= ((location->gtFlags | value->gtFlags) & GTF_ALL_EFFECT);

                GenTree* insertionPoint = location->gtNext;
                BlockRange().InsertBefore(insertionPoint, storeBlk);
                use.ReplaceWith(comp, storeBlk);
                BlockRange().Remove(assignment);
                JITDUMP("After transforming local struct assignment into a block op:\n");
                DISPTREERANGE(BlockRange(), use.Def());
                JITDUMP("\n");
                return;
            }
            else
            {
                assert(location->OperIsBlk());
            }
        }
    }

    switch (locationOp)
    {
        case GT_LCL_VAR:
        case GT_LCL_FLD:
        case GT_REG_VAR:
        case GT_PHI_ARG:
            RewriteAssignmentIntoStoreLclCore(assignment, location, value, locationOp);
            BlockRange().Remove(location);
            break;

        case GT_IND:
        {
            GenTreeStoreInd* store =
                new (comp, GT_STOREIND) GenTreeStoreInd(location->TypeGet(), location->gtGetOp1(), value);

            copyFlags(store, assignment, GTF_ALL_EFFECT);
//.........这里部分代码省略.........

void Rationalizer::RewriteAssignment(LIR::Use& use)
{
    assert(use.IsInitialized());

    GenTreeOp* assignment = use.Def()->AsOp();
    assert(assignment->OperGet() == GT_ASG);

    GenTree* location = assignment->gtGetOp1();
    GenTree* value    = assignment->gtGetOp2();

    genTreeOps locationOp = location->OperGet();

#ifdef FEATURE_SIMD
    if (varTypeIsSIMD(location) && assignment->OperIsInitBlkOp())
    {
        if (location->OperGet() == GT_LCL_VAR)
        {
            var_types simdType = location->TypeGet();
            GenTree*  initVal  = assignment->gtOp.gtOp2;
            var_types baseType = comp->getBaseTypeOfSIMDLocal(location);
            if (baseType != TYP_UNKNOWN)
            {
                GenTreeSIMD* simdTree = new (comp, GT_SIMD)
                    GenTreeSIMD(simdType, initVal, SIMDIntrinsicInit, baseType, genTypeSize(simdType));
                assignment->gtOp.gtOp2 = simdTree;
                value                  = simdTree;
                initVal->gtNext        = simdTree;
                simdTree->gtPrev       = initVal;

                simdTree->gtNext = location;
                location->gtPrev = simdTree;
            }
        }
        else
        {
            assert(location->OperIsBlk());
        }
    }
#endif // FEATURE_SIMD

    switch (locationOp)
    {
        case GT_LCL_VAR:
        case GT_LCL_FLD:
        case GT_REG_VAR:
        case GT_PHI_ARG:
            RewriteAssignmentIntoStoreLclCore(assignment, location, value, locationOp);
            BlockRange().Remove(location);
            break;

        case GT_IND:
        {
            GenTreeStoreInd* store =
                new (comp, GT_STOREIND) GenTreeStoreInd(location->TypeGet(), location->gtGetOp1(), value);

            copyFlags(store, assignment, GTF_ALL_EFFECT);
            copyFlags(store, location, GTF_IND_FLAGS);

            if (assignment->IsReverseOp())
            {
                store->gtFlags |= GTF_REVERSE_OPS;
            }

            // TODO: JIT dump

            // Remove the GT_IND node and replace the assignment node with the store
            BlockRange().Remove(location);
            BlockRange().InsertBefore(assignment, store);
            use.ReplaceWith(comp, store);
            BlockRange().Remove(assignment);
        }
        break;

        case GT_CLS_VAR:
        {
            location->SetOper(GT_CLS_VAR_ADDR);
            location->gtType = TYP_BYREF;

            assignment->SetOper(GT_STOREIND);

            // TODO: JIT dump
        }
        break;

        case GT_BLK:
        case GT_OBJ:
        case GT_DYN_BLK:
        {
            assert(varTypeIsStruct(location));
            GenTreeBlk* storeBlk = location->AsBlk();
            genTreeOps  storeOper;
            switch (location->gtOper)
            {
                case GT_BLK:
                    storeOper = GT_STORE_BLK;
                    break;
                case GT_OBJ:
                    storeOper = GT_STORE_OBJ;
                    break;
                case GT_DYN_BLK:
//.........这里部分代码省略.........

//.........这里部分代码省略.........
    case GT_CALL:
        nextNode = DecomposeCall(use);
        break;

    case GT_RETURN:
        assert(tree->gtOp.gtOp1->OperGet() == GT_LONG);
        break;

    case GT_STOREIND:
        nextNode = DecomposeStoreInd(use);
        break;

    case GT_STORE_LCL_FLD:
        assert(tree->gtOp.gtOp1->OperGet() == GT_LONG);
        NYI("st.lclFld of of TYP_LONG");
        break;

    case GT_IND:
        nextNode = DecomposeInd(use);
        break;

    case GT_NOT:
        nextNode = DecomposeNot(use);
        break;

    case GT_NEG:
        nextNode = DecomposeNeg(use);
        break;

    // Binary operators. Those that require different computation for upper and lower half are
    // handled by the use of GetHiOper().
    case GT_ADD:
    case GT_SUB:
    case GT_OR:
    case GT_XOR:
    case GT_AND:
        nextNode = DecomposeArith(use);
        break;

    case GT_MUL:
        nextNode = DecomposeMul(use);
        break;

    case GT_DIV:
        NYI("Arithmetic binary operators on TYP_LONG - GT_DIV");
        break;

    case GT_MOD:
        NYI("Arithmetic binary operators on TYP_LONG - GT_MOD");
        break;

    case GT_UDIV:
        NYI("Arithmetic binary operators on TYP_LONG - GT_UDIV");
        break;

    case GT_UMOD:
        NYI("Arithmetic binary operators on TYP_LONG - GT_UMOD");
        break;

    case GT_LSH:
    case GT_RSH:
    case GT_RSZ:
        nextNode = DecomposeShift(use);
        break;

    case GT_ROL:
    case GT_ROR:
        NYI("Arithmetic binary operators on TYP_LONG - ROTATE");
        break;

    case GT_MULHI:
        NYI("Arithmetic binary operators on TYP_LONG - MULHI");
        break;

    case GT_LOCKADD:
    case GT_XADD:
    case GT_XCHG:
    case GT_CMPXCHG:
        NYI("Interlocked operations on TYP_LONG");
        break;

    default:
    {
        JITDUMP("Illegal TYP_LONG node %s in Decomposition.", GenTree::NodeName(tree->OperGet()));
        noway_assert(!"Illegal TYP_LONG node in Decomposition.");
        break;
    }
    }

#ifdef DEBUG
    if (m_compiler->verbose)
    {
        // NOTE: st_lcl_var doesn't dump properly afterwards.
        printf("Decomposing TYP_LONG tree.  AFTER:\n");
        m_compiler->gtDispTreeRange(Range(), use.Def());
    }
#endif

    return nextNode;
}

Compiler::fgWalkResult Rationalizer::RewriteNode(GenTree** useEdge, ArrayStack<GenTree*>& parentStack)
{
    assert(useEdge != nullptr);

    GenTree* node = *useEdge;
    assert(node != nullptr);

#ifdef DEBUG
    const bool isLateArg = (node->gtFlags & GTF_LATE_ARG) != 0;
#endif

    // First, remove any preceeding GT_LIST nodes, which are not otherwise visited by the tree walk.
    //
    // NOTE: GT_LIST nodes that are used by block ops and phi nodes will in fact be visited.
    for (GenTree* prev = node->gtPrev; prev != nullptr && prev->OperGet() == GT_LIST; prev = node->gtPrev)
    {
        BlockRange().Remove(prev);
    }

    // In addition, remove the current node if it is a GT_LIST node.
    if ((*useEdge)->OperGet() == GT_LIST)
    {
        BlockRange().Remove(*useEdge);
        return Compiler::WALK_CONTINUE;
    }

    LIR::Use use;
    if (parentStack.Height() < 2)
    {
        use = LIR::Use::GetDummyUse(BlockRange(), *useEdge);
    }
    else
    {
        use = LIR::Use(BlockRange(), useEdge, parentStack.Index(1));
    }

    assert(node == use.Def());
    switch (node->OperGet())
    {
        case GT_ASG:
            RewriteAssignment(use);
            break;

        case GT_BOX:
            // GT_BOX at this level just passes through so get rid of it
            use.ReplaceWith(comp, node->gtGetOp1());
            BlockRange().Remove(node);
            break;

        case GT_ADDR:
            RewriteAddress(use);
            break;

        case GT_NOP:
            // fgMorph sometimes inserts NOP nodes between defs and uses
            // supposedly 'to prevent constant folding'. In this case, remove the
            // NOP.
            if (node->gtGetOp1() != nullptr)
            {
                use.ReplaceWith(comp, node->gtGetOp1());
                BlockRange().Remove(node);
            }
            break;

        case GT_COMMA:
        {
            GenTree* op1 = node->gtGetOp1();
            if ((op1->gtFlags & GTF_ALL_EFFECT) == 0)
            {
                // The LHS has no side effects. Remove it.
                bool               isClosed    = false;
                unsigned           sideEffects = 0;
                LIR::ReadOnlyRange lhsRange    = BlockRange().GetTreeRange(op1, &isClosed, &sideEffects);

                // None of the transforms performed herein violate tree order, so these
                // should always be true.
                assert(isClosed);
                assert((sideEffects & GTF_ALL_EFFECT) == 0);

                BlockRange().Delete(comp, m_block, std::move(lhsRange));
            }

            GenTree* replacement = node->gtGetOp2();
            if (!use.IsDummyUse())
            {
                use.ReplaceWith(comp, replacement);
            }
            else
            {
                // This is a top-level comma. If the RHS has no side effects we can remove
                // it as well.
                if ((replacement->gtFlags & GTF_ALL_EFFECT) == 0)
                {
                    bool               isClosed    = false;
                    unsigned           sideEffects = 0;
                    LIR::ReadOnlyRange rhsRange    = BlockRange().GetTreeRange(replacement, &isClosed, &sideEffects);

                    // None of the transforms performed herein violate tree order, so these
                    // should always be true.
                    assert(isClosed);
//.........这里部分代码省略.........

// Transform CopyBlk involving SIMD vectors into stlclvar or stind of a SIMD type.
// Transformation is done if either src or dst are known to be SIMD vectors.
//
// Arguments:
//    ppTree      - A pointer-to-a-pointer for the GT_COPYBLK
//    fgWalkData  - A pointer to tree walk data providing the context
//
// Return Value:
//    None.
//
// If either the source or the dst are known to be SIMD (a lclVar or SIMD intrinsic),
// get the simdType (TYP_DOUBLE or a SIMD type for SSE2) from the size of the SIMD node.
//
// For the source:
// - If it is a SIMD intrinsic or a lvSIMDType lclVar, change the node type to simdType.
// - Otherwise, add a GT_IND of simdType.
// For the dst:
// - If it is a lclVar of a SIMD type, chanage the node type to simdType.
// - Otherwise, change it to a GT_STORE_IND of simdType
//
// TODO-Cleanup: Once SIMD types are plumbed through the frontend, this will no longer
// be required.
//
void Rationalizer::RewriteCopyBlk(LIR::Use& use)
{
#ifdef FEATURE_SIMD
    // No need to transofrm non-SIMD nodes, if featureSIMD is not enabled.
    if (!comp->featureSIMD)
    {
        return;
    }

    // See if this is a SIMD copyBlk
    GenTreeCpBlk* cpBlk   = use.Def()->AsCpBlk();
    GenTreePtr    dstAddr = cpBlk->Dest();
    GenTree*      srcAddr = cpBlk->Source();

    const bool srcIsSIMDAddr = comp->isAddrOfSIMDType(srcAddr);
    const bool dstIsSIMDAddr = comp->isAddrOfSIMDType(dstAddr);

    // Do not transform if neither src or dst is known to be a SIMD type.
    // If src tree type is something we cannot reason but if dst is known to be of a SIMD type
    // we will treat src tree as a SIMD type and vice versa.
    if (!srcIsSIMDAddr && !dstIsSIMDAddr)
    {
        return;
    }

    // At this point it is known to be a copyblk of SIMD vectors and we can
    // start transforming the original tree. Prior to this point do not perform
    // any modifications to the original tree.
    JITDUMP("\nRewriting SIMD CopyBlk\n");
    DISPTREERANGE(BlockRange(), cpBlk);

    // There are currently only three sizes supported: 8 bytes, 12 bytes, 16 bytes or the vector register length.
    GenTreeIntConCommon* sizeNode = cpBlk->Size()->AsIntConCommon();
    var_types            simdType = comp->getSIMDTypeForSize((unsigned int)sizeNode->IconValue());

    // Remove 'size' from execution order
    BlockRange().Remove(sizeNode);

    // Is destination a lclVar which is not an arg?
    // If yes then we can turn it to a stlcl.var, otherwise turn into stind.
    GenTree*   simdDst = nullptr;
    genTreeOps oper    = GT_NONE;
    if (dstIsSIMDAddr && dstAddr->OperIsLocalAddr())
    {
        simdDst         = dstAddr;
        simdDst->gtType = simdType;
        oper            = GT_STORE_LCL_VAR;

        // For structs that are padded (e.g. Vector3f, Vector3i), the morpher will have marked them
        // as GTF_VAR_USEASG.  Unmark them.
        simdDst->gtFlags &= ~(GTF_VAR_USEASG);
    }
    else
    {
        // Address of a non-local var
        simdDst = dstAddr;
        oper    = GT_STOREIND;
    }

    GenTree* simdSrc = nullptr;
    if ((srcAddr->OperGet() == GT_ADDR) && varTypeIsSIMD(srcAddr->gtGetOp1()))
    {
        // Get rid of parent node of GT_ADDR(..) if its child happens to be of a SIMD type.
        BlockRange().Remove(srcAddr);
        simdSrc = srcAddr->gtGetOp1();
    }
    else if (srcIsSIMDAddr && srcAddr->OperIsLocalAddr())
    {
        // If the source has been rewritten into a local addr node, rewrite it back into a
        // local var node.
        simdSrc = srcAddr;
        simdSrc->SetOper(loadForm(srcAddr->OperGet()));
    }
    else
    {
        // Since destination is known to be a SIMD type, src must be a SIMD type too
        // though we cannot figure it out easily enough. Transform src into
//.........这里部分代码省略.........

// Rewrite InitBlk involving SIMD vector into stlcl.var of a SIMD type.
//
// Arguments:
//    ppTree      - A pointer-to-a-pointer for the GT_INITBLK
//    fgWalkData  - A pointer to tree walk data providing the context
//
// Return Value:
//    None.
//
// TODO-Cleanup: Once SIMD types are plumbed through the frontend, this will no longer
// be required.
//
void Rationalizer::RewriteInitBlk(LIR::Use& use)
{
#ifdef FEATURE_SIMD
    // No lowering is needed for non-SIMD nodes, so early out if featureSIMD is not enabled.
    if (!comp->featureSIMD)
    {
        return;
    }

    // See if this is a SIMD initBlk that needs to be changed to a simple st.lclVar.
    GenTreeInitBlk* initBlk = use.Def()->AsInitBlk();

    // Is the dstAddr is addr of a SIMD type lclVar?
    GenTree* dstAddr = initBlk->Dest();
    if (!comp->isAddrOfSIMDType(dstAddr) || !dstAddr->OperIsLocalAddr())
    {
        return;
    }

    unsigned lclNum = dstAddr->AsLclVarCommon()->gtLclNum;
    if (!comp->lvaTable[lclNum].lvSIMDType)
    {
        return;
    }

    var_types            baseType      = comp->lvaTable[lclNum].lvBaseType;
    CORINFO_CLASS_HANDLE typeHnd       = comp->lvaTable[lclNum].lvVerTypeInfo.GetClassHandle();
    unsigned             simdLocalSize = comp->getSIMDTypeSizeInBytes(typeHnd);

    JITDUMP("Rewriting SIMD InitBlk\n");
    DISPTREERANGE(BlockRange(), initBlk);

    assert((dstAddr->gtFlags & GTF_VAR_USEASG) == 0);

    // There are currently only three sizes supported: 8 bytes, 16 bytes or the vector register length.
    GenTreeIntConCommon* sizeNode = initBlk->Size()->AsIntConCommon();
    unsigned int         size     = (unsigned int)roundUp(sizeNode->IconValue(), TARGET_POINTER_SIZE);
    var_types            simdType = comp->getSIMDTypeForSize(size);
    assert(roundUp(simdLocalSize, TARGET_POINTER_SIZE) == size);

    GenTree*     initVal  = initBlk->InitVal();
    GenTreeSIMD* simdNode = new (comp, GT_SIMD)
        GenTreeSIMD(simdType, initVal, SIMDIntrinsicInit, baseType, (unsigned)sizeNode->IconValue());

    dstAddr->SetOper(GT_STORE_LCL_VAR);
    GenTreeLclVar* store = dstAddr->AsLclVar();
    store->gtType        = simdType;
    store->gtOp.gtOp1    = simdNode;
    store->gtFlags |= ((simdNode->gtFlags & GTF_ALL_EFFECT) | GTF_ASG);
    BlockRange().Remove(store);

    // Insert the new nodes into the block
    BlockRange().InsertAfter(initVal, simdNode, store);
    use.ReplaceWith(comp, store);

    // Remove the old size and GT_INITBLK nodes.
    BlockRange().Remove(sizeNode);
    BlockRange().Remove(initBlk);

    JITDUMP("After rewriting SIMD InitBlk:\n");
    DISPTREERANGE(BlockRange(), use.Def());
    JITDUMP("\n");
#endif // FEATURE_SIMD
}