gentree.h

//
// Copyright (c) Microsoft. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.
//

/*XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XX                                                                           XX
XX                          GenTree                                          XX
XX                                                                           XX
XX  This is the node in the semantic tree graph. It represents the operation XX
XX  corresponding to the node, and other information during code-gen.        XX
XX                                                                           XX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
*/

/*****************************************************************************/
#ifndef _GENTREE_H_
#define _GENTREE_H_
/*****************************************************************************/

#include "vartype.h"    // For "var_types"
#include "target.h"     // For "regNumber"
#include "ssaconfig.h"  // For "SsaConfig::RESERVED_SSA_NUM"
#include "reglist.h"
#include "valuenumtype.h"
#include "simplerhash.h"
#include "nodeinfo.h"
#include "simd.h"

// Debugging GenTree is much easier if we add a magic virtual function to make the debugger able to figure out what type it's got.
// This is enabled by default in DEBUG. To enable it in RET builds (temporarily!), you need to change the build to define DEBUGGABLE_GENTREE=1,
// as well as pass /OPT:NOICF to the linker (or else all the vtables get merged, making the debugging value supplied by them useless).
// See protojit.nativeproj for a commented example of setting the build flags correctly.
#ifndef DEBUGGABLE_GENTREE
#ifdef DEBUG
#define DEBUGGABLE_GENTREE  1
#else // !DEBUG
#define DEBUGGABLE_GENTREE  0
#endif // !DEBUG
#endif // !DEBUGGABLE_GENTREE

/*****************************************************************************/

DECLARE_TYPED_ENUM(genTreeOps,BYTE)
{
    #define GTNODE(en,sn,cm,ok) en,
    #include "gtlist.h"

    GT_COUNT,

    // GT_CNS_NATIVELONG is the gtOper symbol for GT_CNS_LNG or GT_CNS_INT, depending on the target.
    // For the 64-bit targets we will only use GT_CNS_INT as it used to represent all the possible sizes
    // For the 32-bit targets we use a GT_CNS_LNG to hold a 64-bit integer constant and GT_CNS_INT for all others.
    // In the future when we retarget the JIT for x86 we should consider eliminating GT_CNS_LNG
    //
#ifdef _TARGET_64BIT_
    GT_CNS_NATIVELONG = GT_CNS_INT,
#else
    GT_CNS_NATIVELONG = GT_CNS_LNG,
#endif
}
END_DECLARE_TYPED_ENUM(genTreeOps,BYTE)

/*****************************************************************************
 *
 *  The following enum defines a set of bit flags that can be used
 *  to classify expression tree nodes. Note that some operators will
 *  have more than one bit set, as follows:
 *
 *          GTK_CONST    implies    GTK_LEAF
 *          GTK_RELOP    implies    GTK_BINOP
 *          GTK_LOGOP    implies    GTK_BINOP
 */

enum genTreeKinds
{
    GTK_SPECIAL = 0x0000,       // unclassified operator (special handling reqd)

    GTK_CONST   = 0x0001,       // constant     operator
    GTK_LEAF    = 0x0002,       // leaf         operator
    GTK_UNOP    = 0x0004,       // unary        operator
    GTK_BINOP   = 0x0008,       // binary       operator
    GTK_RELOP   = 0x0010,       // comparison   operator
    GTK_LOGOP   = 0x0020,       // logical      operator
    GTK_ASGOP   = 0x0040,       // assignment   operator

    GTK_KINDMASK= 0x007F,       // operator kind mask

    GTK_COMMUTE = 0x0080,       // commutative  operator

    GTK_EXOP    = 0x0100,       // Indicates that an oper for a node type that extends GenTreeOp (or GenTreeUnOp)
                                // by adding non-node fields to unary or binary operator.

    GTK_LOCAL   = 0x0200,       // is a local access (load, store, phi)

    /* Define composite value(s) */

    GTK_SMPOP   = (GTK_UNOP|GTK_BINOP|GTK_RELOP|GTK_LOGOP)
};

/*****************************************************************************/

#define SMALL_TREE_NODES    1

/*****************************************************************************/

DECLARE_TYPED_ENUM(gtCallTypes,BYTE)
{
    CT_USER_FUNC,       // User function
    CT_HELPER,          // Jit-helper
    CT_INDIRECT,        // Indirect call

    CT_COUNT            // fake entry (must be last)
}
END_DECLARE_TYPED_ENUM(gtCallTypes,BYTE)


/*****************************************************************************/

struct                  BasicBlock;
 
struct                  InlineCandidateInfo;

/*****************************************************************************/

// GT_FIELD nodes will be lowered into more "code-gen-able" representations, like
// GT_IND's of addresses, or GT_LCL_FLD nodes.  We'd like to preserve the more abstract
// information, and will therefore annotate such lowered nodes with FieldSeq's.  A FieldSeq
// represents a (possibly) empty sequence of fields.  The fields are in the order
// in which they are dereferenced.  The first field may be an object field or a struct field;
// all subsequent fields must be struct fields.
struct FieldSeqNode
{
    CORINFO_FIELD_HANDLE m_fieldHnd;
    FieldSeqNode*        m_next;

    FieldSeqNode(CORINFO_FIELD_HANDLE fieldHnd, FieldSeqNode* next) : m_fieldHnd(fieldHnd), m_next(next) {}

    // returns true when this is the pseudo #FirstElem field sequence
    bool IsFirstElemFieldSeq();

    // returns true when this is the pseudo #ConstantIndex field sequence
    bool IsConstantIndexFieldSeq();

    // returns true when this is the the pseudo #FirstElem field sequence or the pseudo #ConstantIndex field sequence
    bool IsPseudoField();

    // Make sure this provides methods that allow it to be used as a KeyFuncs type in SimplerHash.
    static int GetHashCode(FieldSeqNode fsn)
    {
        return reinterpret_cast<int>(fsn.m_fieldHnd) ^ reinterpret_cast<int>(fsn.m_next);
    }

    static bool Equals(FieldSeqNode fsn1, FieldSeqNode fsn2)
    {
        return fsn1.m_fieldHnd == fsn2.m_fieldHnd && fsn1.m_next == fsn2.m_next;
    }
};

// This class canonicalizes field sequences.
class FieldSeqStore
{
    typedef SimplerHashTable<FieldSeqNode, /*KeyFuncs*/FieldSeqNode, FieldSeqNode*, DefaultSimplerHashBehavior> FieldSeqNodeCanonMap;

    IAllocator*           m_alloc;
    FieldSeqNodeCanonMap* m_canonMap;

    static FieldSeqNode   s_notAField;  // No value, just exists to provide an address.

    // Dummy variables to provide the addresses for the "pseudo field handle" statics below.
    static int FirstElemPseudoFieldStruct;
    static int ConstantIndexPseudoFieldStruct;

public:
    FieldSeqStore(IAllocator* alloc);

    // Returns the (canonical in the store) singleton field sequence for the given handle.
    FieldSeqNode* CreateSingleton(CORINFO_FIELD_HANDLE fieldHnd);

    // This is a special distinguished FieldSeqNode indicating that a constant does *not*
    // represent a valid field sequence.  This is "infectious", in the sense that appending it
    // (on either side) to any field sequence yields the "NotAField()" sequence.
    static FieldSeqNode* NotAField() { return &s_notAField; }

    // Returns the (canonical in the store) field sequence representing the concatenation of
    // the sequences represented by "a" and "b".  Assumes that "a" and "b" are canonical; that is,
    // they are the results of CreateSingleton, NotAField, or Append calls.  If either of the arguments
    // are the "NotAField" value, so is the result.
    FieldSeqNode* Append(FieldSeqNode* a, FieldSeqNode* b);

    // We have a few "pseudo" field handles:

    // This treats the constant offset of the first element of something as if it were a field.
    // Works for method table offsets of boxed structs, or first elem offset of arrays/strings.
    static CORINFO_FIELD_HANDLE FirstElemPseudoField;

    // If there is a constant index, we make a psuedo field to correspond to the constant added to
    // offset of the indexed field.  This keeps the field sequence structure "normalized", especially in the
    // case where the element type is a struct, so we might add a further struct field offset.
    static CORINFO_FIELD_HANDLE ConstantIndexPseudoField;

    static bool IsPseudoField(CORINFO_FIELD_HANDLE hnd)
    {
        return hnd == FirstElemPseudoField || hnd == ConstantIndexPseudoField;
    }
};



/*****************************************************************************/

typedef struct GenTree *  GenTreePtr;
struct GenTreeArgList;

// Forward declarations of the subtypes
#define GTSTRUCT_0(fn, en)                struct GenTree##fn;
#define GTSTRUCT_1(fn, en)                struct GenTree##fn;
#define GTSTRUCT_2(fn, en, en2)           struct GenTree##fn;
#define GTSTRUCT_3(fn, en, en2, en3)      struct GenTree##fn;
#define GTSTRUCT_4(fn, en, en2, en3, en4) struct GenTree##fn;
#define GTSTRUCT_N(fn, ...) struct GenTree##fn;
#include "gtstructs.h"

/*****************************************************************************/

#ifndef _WIN64
#include <pshpack4.h>
#endif

struct GenTree
{
    // We use GT_STRUCT_0 only for the category of simple ops.
#define GTSTRUCT_0(fn, en)           GenTree##fn* As##fn() \
                                     { \
                                         assert(this->OperIsSimple()); \
                                         return reinterpret_cast<GenTree##fn*>(this); \
                                     } \
                                     GenTree##fn& As##fn##Ref() { return *As##fn(); } \
                                     __declspec(property(get=As##fn##Ref)) GenTree##fn& gt##fn;
#define GTSTRUCT_1(fn, en)           GenTree##fn* As##fn() \
                                     { \
                                         assert(this->gtOper == en); \
                                         return reinterpret_cast<GenTree##fn*>(this); \
                                     } \
                                     GenTree##fn& As##fn##Ref() { return *As##fn(); } \
                                     __declspec(property(get=As##fn##Ref)) GenTree##fn& gt##fn;
#define GTSTRUCT_2(fn, en, en2)      GenTree##fn* As##fn() \
                                     { \
                                         assert(this->gtOper == en || this->gtOper == en2); \
                                         return reinterpret_cast<GenTree##fn*>(this); \
                                     } \
                                     GenTree##fn& As##fn##Ref() { return *As##fn(); } \
                                     __declspec(property(get=As##fn##Ref)) GenTree##fn& gt##fn;
#define GTSTRUCT_3(fn, en, en2, en3) GenTree##fn* As##fn() \
                                     { \
                                         assert(this->gtOper == en || this->gtOper == en2 || this->gtOper == en3); \
                                         return reinterpret_cast<GenTree##fn*>(this); \
                                     } \
                                     GenTree##fn& As##fn##Ref() { return *As##fn(); } \
                                     __declspec(property(get=As##fn##Ref)) GenTree##fn& gt##fn;

#define GTSTRUCT_4(fn, en, en2, en3, en4) GenTree##fn* As##fn() \
                                     { \
                                         assert(this->gtOper == en || this->gtOper == en2 || this->gtOper == en3 || this->gtOper == en4); \
                                         return reinterpret_cast<GenTree##fn*>(this); \
                                     } \
                                     GenTree##fn& As##fn##Ref() { return *As##fn(); } \
                                     __declspec(property(get=As##fn##Ref)) GenTree##fn& gt##fn;

#ifdef DEBUG
// VC does not optimize out this loop in retail even though the value it computes is unused
// so we need a separate version for non-debug
#define GTSTRUCT_N(fn, ...)          GenTree##fn* As##fn() \
                                     { \
                                         genTreeOps validOps[] = {__VA_ARGS__}; \
                                         bool found = false;            \
                                         for (unsigned i=0; i<ArrLen(validOps); i++) { \
                                             if (this->gtOper == validOps[i]) \
                                             {                          \
                                                 found = true;          \
                                                 break;                 \
                                             }                          \
                                         }                              \
                                         assert(found);                 \
                                         return reinterpret_cast<GenTree##fn*>(this); \
                                     }                                  \
                                     GenTree##fn& As##fn##Ref() { return *As##fn(); }                    \
                                     __declspec(property(get=As##fn##Ref)) GenTree##fn& gt##fn;
#else
#define GTSTRUCT_N(fn, ...)          GenTree##fn* As##fn()    \
                                     { \
                                         return reinterpret_cast<GenTree##fn*>(this); \
                                     }                                  \
                                     GenTree##fn& As##fn##Ref() { return *As##fn(); }                    \
                                     __declspec(property(get=As##fn##Ref)) GenTree##fn& gt##fn;
#endif

#include "gtstructs.h"

    genTreeOps          gtOper;       // enum subtype BYTE
    var_types           gtType;       // enum subtype BYTE 

    genTreeOps          OperGet() const { return gtOper; }
    var_types           TypeGet() const { return gtType; }

#ifdef DEBUG
    genTreeOps          gtOperSave;   // Only used to save gtOper when we destroy a node, to aid debugging.
#endif

#if FEATURE_ANYCSE

#define NO_CSE           (0)

#define IS_CSE_INDEX(x)  (x != 0)
#define IS_CSE_USE(x)    (x > 0)
#define IS_CSE_DEF(x)    (x < 0)
#define GET_CSE_INDEX(x) ((x > 0) ? x : -x)
#define TO_CSE_DEF(x)    (-x)

    signed char       gtCSEnum;        // 0 or the CSE index (negated if def)
                                       // valid only for CSE expressions

#endif // FEATURE_ANYCSE

#if ASSERTION_PROP
    unsigned char     gtAssertionNum;  // 0 or Assertion table index
                                       // valid only for non-GT_STMT nodes

    bool         HasAssertion() const             { return gtAssertionNum != 0; }
    void         ClearAssertion()                 { gtAssertionNum = 0;         }

    unsigned int GetAssertion() const             { return gtAssertionNum;  }
    void         SetAssertion(unsigned int value) { assert((unsigned char)value == value); gtAssertionNum = (unsigned char)value; }

#endif

#if FEATURE_STACK_FP_X87
    unsigned char       gtFPlvl;        // x87 stack depth at this node
    void                gtCopyFPlvl(GenTree * other) { gtFPlvl = other->gtFPlvl; }
    void                gtSetFPlvl(unsigned level) { noway_assert(FitsIn<unsigned char>(level)); gtFPlvl = (unsigned char)level; }
#else // FEATURE_STACK_FP_X87
    void                gtCopyFPlvl(GenTree * other) { }
    void                gtSetFPlvl(unsigned level) { }
#endif // FEATURE_STACK_FP_X87

    //
    // Cost metrics on the node. Don't allow direct access to the variable for setting.
    //

public:

#ifdef DEBUG
    // You are not allowed to read the cost values before they have been set in gtSetEvalOrder().
    // Keep track of whether the costs have been initialized, and assert if they are read before being initialized.
    // Obviously, this information does need to be initialized when a node is created.
    // This is public so the dumpers can see it.

    bool gtCostsInitialized;
#endif // DEBUG

#define MAX_COST        UCHAR_MAX
#define IND_COST_EX     3             // execution cost for an indirection

    __declspec(property(get=GetCostEx))
    unsigned char    gtCostEx;     // estimate of expression execution cost

    __declspec(property(get=GetCostSz))
    unsigned char    gtCostSz;     // estimate of expression code size cost

    unsigned char GetCostEx() const { assert(gtCostsInitialized); return _gtCostEx; }
    unsigned char GetCostSz() const { assert(gtCostsInitialized); return _gtCostSz; }

    // Set the costs. They are always both set at the same time.
    // Don't use the "put" property: force calling this function, to make it more obvious in the few places
    // that set the values.
    // Note that costs are only set in gtSetEvalOrder() and its callees.
    void            SetCosts(unsigned costEx, unsigned costSz)
    {
        assert(costEx != (unsigned)-1); // looks bogus
        assert(costSz != (unsigned)-1); // looks bogus
        INDEBUG(gtCostsInitialized = true;)

        _gtCostEx = (costEx > MAX_COST) ? MAX_COST : (unsigned char)costEx;
        _gtCostSz = (costSz > MAX_COST) ? MAX_COST : (unsigned char)costSz;
    }

    // Opimized copy function, to avoid the SetCosts() function comparisons, and make it more clear that a node copy is happening.
    void            CopyCosts(const GenTree* const tree)
    {
        INDEBUG(gtCostsInitialized = tree->gtCostsInitialized;) // If the 'tree' costs aren't initialized, we'll hit an assert below.
        _gtCostEx = tree->gtCostEx;
        _gtCostSz = tree->gtCostSz;
    }

    // Same as CopyCosts, but avoids asserts if the costs we are copying have not been initialized.
    // This is because the importer, for example, clones nodes, before these costs have been initialized.
    // Note that we directly access the 'tree' costs, not going through the accessor functions (either
    // directly or through the properties).
    void            CopyRawCosts(const GenTree* const tree)
    {
        INDEBUG(gtCostsInitialized = tree->gtCostsInitialized;)
        _gtCostEx = tree->_gtCostEx;
        _gtCostSz = tree->_gtCostSz;
    }

private:

    unsigned char    _gtCostEx;     // estimate of expression execution cost
    unsigned char    _gtCostSz;     // estimate of expression code size cost

    //
    // Register or register pair number of the node.
    //

#ifdef DEBUG
public:
    enum genRegTag
    {
        GT_REGTAG_NONE,     // Nothing has been assigned to _gtRegNum/_gtRegPair
        GT_REGTAG_REG,      // _gtRegNum  has been assigned
        GT_REGTAG_REGPAIR   // _gtRegPair has been assigned
    };
    genRegTag GetRegTag() const
    {
        assert(gtRegTag == GT_REGTAG_NONE ||
               gtRegTag == GT_REGTAG_REG  ||
               gtRegTag == GT_REGTAG_REGPAIR);
        return gtRegTag;
    }
private:
    genRegTag           gtRegTag; // What is in _gtRegNum/_gtRegPair?
#endif // DEBUG

private:

    union
    { 
        // NOTE: After LSRA, one of these values may be valid even if GTF_REG_VAL is not set in gtFlags.
        // They store the register assigned to the node. If a register is not assigned, _gtRegNum is set to REG_NA
        // or _gtRegPair is set to REG_PAIR_NONE, depending on the node type.
        regNumberSmall   _gtRegNum;     // which register      the value is in
        regPairNoSmall   _gtRegPair;    // which register pair the value is in
    };

public:

    // The register number is stored in a small format (8 bits), but the getters return and the setters take
    // a full-size (unsigned) format, to localize the casts here.

    __declspec(property(get=GetRegNum,put=SetRegNum))
    regNumber           gtRegNum;

    // for codegen purposes, is this node a subnode of its parent
    bool isContained() const;

    bool isContainedIndir() const;

    bool isIndirAddrMode();

    bool isIndir() const;

    bool isContainedIntOrIImmed() const     { return isContained() && IsCnsIntOrI(); }

    bool isContainedFltOrDblImmed() const   { return isContained() && (OperGet() == GT_CNS_DBL); }

    bool isLclField() const                 { return OperGet() == GT_LCL_FLD || OperGet() == GT_STORE_LCL_FLD; }

    bool isContainedLclField() const        { return isContained() && isLclField(); }

    // Indicates whether it is a memory op.
    // Right now it includes Indir and LclField ops.
    bool isMemoryOp() const                 { return isIndir() || isLclField(); }

    bool isContainedMemoryOp() const        { return isContained() && isMemoryOp(); }

    regNumber GetRegNum() const
    {
        assert((gtRegTag == GT_REGTAG_REG) ||
               (gtRegTag == GT_REGTAG_NONE)); // TODO-Cleanup: get rid of the NONE case, and fix everyplace that reads undefined values
        regNumber reg = (regNumber) _gtRegNum;
        assert((gtRegTag == GT_REGTAG_NONE) || // TODO-Cleanup: get rid of the NONE case, and fix everyplace that reads undefined values
               (reg >= REG_FIRST &&
                reg <= REG_COUNT));
        return reg;
    }

    void SetRegNum(regNumber reg)
    {
        assert(reg >= REG_FIRST &&
               reg <= REG_COUNT);
        // Make sure the upper bits of _gtRegPair are clear
        _gtRegPair = (regPairNoSmall) 0;
        _gtRegNum = (regNumberSmall) reg;
        INDEBUG(gtRegTag = GT_REGTAG_REG;)
        assert(_gtRegNum == reg);
    }

    __declspec(property(get=GetRegPair,put=SetRegPair))
    regPairNo           gtRegPair;

    regPairNo GetRegPair() const
    {
        assert((gtRegTag == GT_REGTAG_REGPAIR) ||
               (gtRegTag == GT_REGTAG_NONE)); // TODO-Cleanup: get rid of the NONE case, and fix everyplace that reads undefined values
        regPairNo regPair = (regPairNo) _gtRegPair;
        assert((gtRegTag == GT_REGTAG_NONE) || // TODO-Cleanup: get rid of the NONE case, and fix everyplace that reads undefined values
               (regPair >= REG_PAIR_FIRST &&
                regPair <= REG_PAIR_LAST) ||
               (regPair == REG_PAIR_NONE));     // allow initializing to an undefined value
        return regPair;
    }

    void SetRegPair(regPairNo regPair)
    {
        assert((regPair >= REG_PAIR_FIRST &&
                regPair <= REG_PAIR_LAST) ||
               (regPair == REG_PAIR_NONE));     // allow initializing to an undefined value
        _gtRegPair = (regPairNoSmall) regPair;
        INDEBUG(gtRegTag = GT_REGTAG_REGPAIR;)
        assert(_gtRegPair == regPair);
    }

    // Copy the _gtRegNum/_gtRegPair/gtRegTag fields
    void CopyReg(GenTreePtr from)
    {
        // To do the copy, use _gtRegPair, which must be bigger than _gtRegNum. Note that the values
        // might be undefined (so gtRegTag == GT_REGTAG_NONE).
        _gtRegPair = from->_gtRegPair;
        C_ASSERT(sizeof(_gtRegPair) >= sizeof(_gtRegNum));
        INDEBUG(gtRegTag = from->gtRegTag;)
    }

    void gtClearReg(Compiler* compiler);

    bool gtHasReg() const
    {
        // Has the node been assigned a register by LSRA?
        //
        // In order for this to work properly, gtClearReg (above) must be called prior to setting
        // the register value.
        if (isRegPairType(TypeGet()))
        {
            assert(_gtRegNum != REG_NA);
            INDEBUG(assert(gtRegTag == GT_REGTAG_REGPAIR));
            return gtRegPair != REG_PAIR_NONE;
        }
        else
        {
            assert(_gtRegNum != REG_PAIR_NONE);
            INDEBUG(assert(gtRegTag == GT_REGTAG_REG));
            return gtRegNum != REG_NA;
        }
    }

    regMaskTP gtGetRegMask() const
    {
        if (isRegPairType(TypeGet()))
        {
            return genRegPairMask(gtRegPair);
        }
        else
        {
            return genRegMask(gtRegNum);
        }
    }

    unsigned            gtFlags;        // see GTF_xxxx below
    
    ValueNumPair        gtVNPair;

    regMaskSmall        gtRsvdRegs;     // set of fixed trashed  registers
#ifdef LEGACY_BACKEND
    regMaskSmall        gtUsedRegs;     // set of used (trashed) registers
#endif // LEGACY_BACKEND

#ifndef LEGACY_BACKEND
    TreeNodeInfo        gtLsraInfo;
#endif // !LEGACY_BACKEND

    void                SetVNsFromNode(GenTreePtr tree)
    {
        gtVNPair = tree->gtVNPair;
    }

    ValueNum            GetVN(ValueNumKind vnk) const
    {
        if (vnk == VNK_Liberal)
        {
            return gtVNPair.GetLiberal();
        }
        else
        {
            assert(vnk == VNK_Conservative);
            return gtVNPair.GetConservative();
        }
    }
    void                SetVN(ValueNumKind vnk, ValueNum vn)
    {
        if (vnk == VNK_Liberal)
        {
            return gtVNPair.SetLiberal(vn);
        }
        else
        {
            assert(vnk == VNK_Conservative);
            return gtVNPair.SetConservative(vn);
        }
    }
    void                ClearVN()
    {
        gtVNPair = ValueNumPair();          // Initializes both elements to "NoVN".
    }

    //---------------------------------------------------------------------
    //  The first set of flags can be used with a large set of nodes, and
    //  thus they must all have distinct values. That is, one can test any
    //  expression node for one of these flags.
    //---------------------------------------------------------------------

    #define GTF_ASG             0x00000001  // sub-expression contains an assignment
    #define GTF_CALL            0x00000002  // sub-expression contains a  func. call
    #define GTF_EXCEPT          0x00000004  // sub-expression might throw an exception
    #define GTF_GLOB_REF        0x00000008  // sub-expression uses global variable(s)
    #define GTF_ORDER_SIDEEFF   0x00000010  // sub-expression has a re-ordering side effect

    // If you set these flags, make sure that code:gtExtractSideEffList knows how to find the tree,
    // otherwise the C# (run csc /o-)
    // var v = side_eff_operation
    // with no use of v will drop your tree on the floor.
    #define GTF_PERSISTENT_SIDE_EFFECTS (GTF_ASG|GTF_CALL)
    #define GTF_SIDE_EFFECT     (GTF_PERSISTENT_SIDE_EFFECTS|GTF_EXCEPT)
    #define GTF_GLOB_EFFECT     (GTF_SIDE_EFFECT|GTF_GLOB_REF)
    #define GTF_ALL_EFFECT      (GTF_GLOB_EFFECT|GTF_ORDER_SIDEEFF)

    // The extra flag GTF_DEAD is used to tell the consumer of these flags
    // that we are calling in the context of performing a CSE, thus we 
    // should allow the run-once side effects of running a class constructor.
    //
    #define GTF_PERSISTENT_SIDE_EFFECTS_IN_CSE (GTF_ASG|GTF_CALL|GTF_DEAD)

    // Can any side-effects be observed externally, say by a caller method?
    // For assignments, only assignments to global memory can be observed
    // externally, whereas simple assignments to local variables can not.
    //
    // Be careful when using this inside a "try" protected region as the
    // order of assignments to local variables would need to be preserved
    // wrt side effects if the variables are alive on entry to the
    // "catch/finally" region. In such cases, even assignments to locals 
    // will have to be restricted.
    #define GTF_GLOBALLY_VISIBLE_SIDE_EFFECTS(flags)                    \
        (((flags) & (GTF_CALL|GTF_EXCEPT))                   ||         \
         (((flags) & (GTF_ASG|GTF_GLOB_REF)) == (GTF_ASG|GTF_GLOB_REF)))
    
    #define GTF_REVERSE_OPS     0x00000020  // operand op2 should be evaluated before op1 (normally, op1 is evaluated first and op2 is evaluated second)
    #define GTF_REG_VAL         0x00000040  // operand is sitting in a register (or part of a TYP_LONG operand is sitting in a register)

    #define GTF_SPILLED         0x00000080  // the value   has been spilled
    #define GTF_SPILLED_OPER    0x00000100  //   op1 has been spilled

#ifdef LEGACY_BACKEND
    #define GTF_SPILLED_OP2     0x00000200  //   op2 has been spilled
#endif // LEGACY_BACKEND

#ifdef DEBUG
#ifndef LEGACY_BACKEND
    #define GTF_MORPHED         0x00000200  // the node has been morphed (in the global morphing phase)
#else // LEGACY_BACKEND
    // For LEGACY_BACKEND, 0x00000200 is in use, but we can use the same value as GTF_SPILLED since we
    // don't call gtSetEvalOrder(), which clears GTF_MORPHED, after GTF_SPILLED has been set.
    #define GTF_MORPHED         0x00000080  // the node has been morphed (in the global morphing phase)
#endif // LEGACY_BACKEND
#endif // DEBUG

    #define GTF_REDINDEX_CHECK  0x00000100  // Used for redundant range checks. Disjoint from GTF_SPILLED_OPER

    #define GTF_ZSF_SET         0x00000400  // the zero(ZF) and sign(SF) flags set to the operand
#if FEATURE_SET_FLAGS
    #define GTF_SET_FLAGS       0x00000800  // Requires that codegen for this node set the flags
                                            // Use gtSetFlags() to check this flags
#endif
    #define GTF_IND_NONFAULTING 0x00000800  // An indir that cannot fault.  GTF_SET_FLAGS is not used on indirs

#if FEATURE_ANYCSE
    #define GTF_DEAD            0x00001000  // this node won't be used any more
#endif // FEATURE_ANYCSE

    #define GTF_MAKE_CSE        0x00002000  // Hoisted Expression: try hard to make this into CSE  (see optPerformHoistExpr)
    #define GTF_DONT_CSE        0x00004000  // don't bother CSE'ing this expr
    #define GTF_COLON_COND      0x00008000  // this node is conditionally executed (part of ? :)

#if defined(DEBUG) && SMALL_TREE_NODES
    #define GTF_NODE_LARGE      0x00010000
    #define GTF_NODE_SMALL      0x00020000

    // Property of the node itself, not the gtOper
    #define GTF_NODE_MASK       (GTF_COLON_COND | GTF_MORPHED   | GTF_NODE_SMALL | GTF_NODE_LARGE )
#else
    #define GTF_NODE_MASK       (GTF_COLON_COND)
#endif

    #define GTF_BOOLEAN         0x00040000  // value is known to be 0/1

    #define GTF_SMALL_OK        0x00080000  // actual small int sufficient

    #define GTF_UNSIGNED        0x00100000  // with GT_CAST:   the source operand is an unsigned type
                                            // with operators: the specified node is an unsigned operator

    #define GTF_LATE_ARG        0x00200000  // the specified node is evaluated to a temp in the arg list, and this temp is added to gtCallLateArgs.

    #define GTF_SPILL           0x00400000  // needs to be spilled here
    #define GTF_SPILL_HIGH      0x00040000  // shared with GTF_BOOLEAN

    #define GTF_COMMON_MASK     0x007FFFFF  // mask of all the flags above

    #define GTF_REUSE_REG_VAL   0x00800000  // This is set by the register allocator on nodes whose value already exists in the
                                            // register assigned to this node, so the code generator does not have to generate
                                            // code to produce the value.
                                            // It is currently used only on constant nodes.
                                            // It CANNOT be set on var (GT_LCL*) nodes, or on indir (GT_IND or GT_STOREIND) nodes, since
                                            // 1) it is not needed for lclVars and is highly unlikely to be useful for indir nodes, and
                                            // 2) it conflicts with GTFD_VAR_CSE_REF for lclVars (though this is debug only, and
                                            //    GTF_IND_ARR_INDEX for indirs.

    //---------------------------------------------------------------------
    //  The following flags can be used only with a small set of nodes, and
    //  thus their values need not be distinct (other than within the set
    //  that goes with a particular node/nodes, of course). That is, one can
    //  only test for one of these flags if the 'gtOper' value is tested as
    //  well to make sure it's the right operator for the particular flag.
    //---------------------------------------------------------------------

    // NB: GTF_VAR_* and GTF_REG_* share the same namespace of flags, because
    // GT_LCL_VAR nodes may be changed to GT_REG_VAR nodes without resetting
    // the flags. These are also used by GT_LCL_FLD.
    #define GTF_VAR_DEF         0x80000000  // GT_LCL_VAR -- this is a definition
    #define GTF_VAR_USEASG      0x40000000  // GT_LCL_VAR -- this is a use/def for a x<op>=y
    #define GTF_VAR_USEDEF      0x20000000  // GT_LCL_VAR -- this is a use/def as in x=x+y (only the lhs x is tagged)
    #define GTF_VAR_CAST        0x10000000  // GT_LCL_VAR -- has been explictly cast (variable node may not be type of local)
    #define GTF_VAR_ITERATOR    0x08000000  // GT_LCL_VAR -- this is a iterator reference in the loop condition
    #define GTF_VAR_CLONED      0x01000000  // GT_LCL_VAR -- this node has been cloned or is a clone
                                            // Relevant for inlining optimizations (see fgInlinePrependStatements)

    // TODO-Cleanup: Currently, GTF_REG_BIRTH is used only by stackfp
    //         We should consider using it more generally for VAR_BIRTH, instead of
    //         GTF_VAR_DEF && !GTF_VAR_USEASG
    #define GTF_REG_BIRTH       0x04000000  // GT_REG_VAR -- enregistered variable born here
    #define GTF_VAR_DEATH       0x02000000  // GT_LCL_VAR, GT_REG_VAR -- variable dies here (last use)

    #define GTF_VAR_ARR_INDEX   0x00000020  // The variable is part of (the index portion of) an array index expression.
                                            // Shares a value with GTF_REVERSE_OPS, which is meaningless for local var.

    #define GTF_LIVENESS_MASK   (GTF_VAR_DEF|GTF_VAR_USEASG|GTF_VAR_USEDEF|GTF_REG_BIRTH|GTF_VAR_DEATH)

    #define GTF_CALL_UNMANAGED  0x80000000  // GT_CALL    -- direct call to unmanaged code
    #define GTF_CALL_INLINE_CANDIDATE 0x40000000 // GT_CALL -- this call has been marked as an inline candidate
//  
    #define GTF_CALL_VIRT_KIND_MASK  0x30000000 
    #define GTF_CALL_NONVIRT         0x00000000  // GT_CALL    -- a non virtual call
    #define GTF_CALL_VIRT_STUB       0x10000000  // GT_CALL    -- a stub-dispatch virtual call
    #define GTF_CALL_VIRT_VTABLE     0x20000000  // GT_CALL    -- a  vtable-based virtual call

    #define GTF_CALL_NULLCHECK  0x08000000  // GT_CALL    -- must check instance pointer for null
    #define GTF_CALL_POP_ARGS   0x04000000  // GT_CALL    -- caller pop arguments?
    #define GTF_CALL_HOISTABLE  0x02000000  // GT_CALL    -- call is hoistable
    #define GTF_CALL_REG_SAVE   0x01000000  // GT_CALL    -- This call preserves all integer regs
                                            // For additional flags for GT_CALL node see GTF_CALL_M_

#ifdef DEBUG
    #define GTFD_VAR_CSE_REF    0x00800000  // GT_LCL_VAR -- This is a CSE LCL_VAR node
#endif

    #define GTF_NOP_DEATH         0x40000000  // GT_NOP     -- operand dies here

    #define GTF_FLD_NULLCHECK     0x80000000  // GT_FIELD -- need to nullcheck the "this" pointer
    #define GTF_FLD_VOLATILE      0x40000000  // GT_FIELD/GT_CLS_VAR -- same as GTF_IND_VOLATILE

    #define GTF_INX_RNGCHK        0x80000000  // GT_INDEX -- the array reference should be range-checked.
    #define GTF_INX_REFARR_LAYOUT 0x20000000  // GT_INDEX -- same as GTF_IND_REFARR_LAYOUT
    #define GTF_INX_STRING_LAYOUT 0x40000000  // GT_INDEX -- this uses the special string array layout

    #define GTF_IND_VOLATILE      0x40000000  // GT_IND   -- the load or store must use volatile sematics (this is a nop on X86)
    #define GTF_IND_REFARR_LAYOUT 0x20000000  // GT_IND   -- the array holds object refs (only effects layout of Arrays)
    #define GTF_IND_TGTANYWHERE   0x10000000  // GT_IND   -- the target could be anywhere
    #define GTF_IND_TLS_REF       0x08000000  // GT_IND   -- the target is accessed via TLS
    #define GTF_IND_ASG_LHS       0x04000000  // GT_IND   -- this GT_IND node is (the effective val) of the LHS of an assignment; don't evaluate it independently.
    #define GTF_IND_UNALIGNED     0x02000000  // GT_IND   -- the load or store is unaligned (we assume worst case alignment of 1 byte) 
    #define GTF_IND_INVARIANT     0x01000000  // GT_IND   -- the target is invariant (a prejit indirection)
    #define GTF_IND_ARR_LEN       0x80000000  // GT_IND   -- the indirection represents an array length (of the REF contribution to its argument).
    #define GTF_IND_ARR_INDEX     0x00800000  // GT_IND   -- the indirection represents an (SZ) array index (this shares the same value as GTFD_VAR_CSE_REF,
                                              //             but is disjoint because a GT_LCL_VAR is never an ind (GT_IND or GT_STOREIND)

    #define GTF_IND_FLAGS         (GTF_IND_VOLATILE|GTF_IND_REFARR_LAYOUT|GTF_IND_TGTANYWHERE|GTF_IND_NONFAULTING|\
                                   GTF_IND_TLS_REF|GTF_IND_UNALIGNED|GTF_IND_INVARIANT|GTF_IND_ARR_INDEX)

    #define GTF_CLS_VAR_ASG_LHS   0x04000000  // GT_CLS_VAR   -- this GT_CLS_VAR node is (the effective val) of the LHS of an assignment; don't evaluate it independently.

    #define GTF_ADDR_ONSTACK      0x80000000  // GT_ADDR    -- this expression is guarenteed to be on the stack


    #define GTF_ADDRMODE_NO_CSE 0x80000000  // GT_ADD/GT_MUL/GT_LSH -- Do not CSE this node only, forms complex addressing mode

    #define GTF_MUL_64RSLT      0x40000000  // GT_MUL     -- produce 64-bit result

    #define GTF_MOD_INT_RESULT  0x80000000  // GT_MOD,    -- the real tree represented by this
                                            // GT_UMOD       node evaluates to an int even though
                                            //               its type is long.  The result is
                                            //               placed in the low member of the
                                            //               reg pair

    #define GTF_RELOP_NAN_UN    0x80000000  // GT_<relop> -- Is branch taken if ops are NaN?
    #define GTF_RELOP_JMP_USED  0x40000000  // GT_<relop> -- result of compare used for jump or ?:
    #define GTF_RELOP_QMARK     0x20000000  // GT_<relop> -- the node is the condition for ?:
    #define GTF_RELOP_SMALL     0x10000000  // GT_<relop> -- We should use a byte or short sized compare (op1->gtType is the small type)

    #define GTF_QMARK_CAST_INSTOF 0x80000000  // GT_QMARK   -- Is this a top (not nested) level qmark created for castclass or instanceof?

    #define GTF_BOX_VALUE 0x80000000  // GT_BOX   -- "box" is on a value type

    #define GTF_ICON_HDL_MASK   0xF0000000  // Bits used by handle types below

    #define GTF_ICON_SCOPE_HDL  0x10000000  // GT_CNS_INT -- constant is a scope handle
    #define GTF_ICON_CLASS_HDL  0x20000000  // GT_CNS_INT -- constant is a class handle
    #define GTF_ICON_METHOD_HDL 0x30000000  // GT_CNS_INT -- constant is a method handle
    #define GTF_ICON_FIELD_HDL  0x40000000  // GT_CNS_INT -- constant is a field handle
    #define GTF_ICON_STATIC_HDL 0x50000000  // GT_CNS_INT -- constant is a handle to static data
    #define GTF_ICON_STR_HDL    0x60000000  // GT_CNS_INT -- constant is a string handle
    #define GTF_ICON_PSTR_HDL   0x70000000  // GT_CNS_INT -- constant is a ptr to a string handle
    #define GTF_ICON_PTR_HDL    0x80000000  // GT_CNS_INT -- constant is a ldptr handle
    #define GTF_ICON_VARG_HDL   0x90000000  // GT_CNS_INT -- constant is a var arg cookie handle
    #define GTF_ICON_PINVKI_HDL 0xA0000000  // GT_CNS_INT -- constant is a pinvoke calli handle
    #define GTF_ICON_TOKEN_HDL  0xB0000000  // GT_CNS_INT -- constant is a token handle
    #define GTF_ICON_TLS_HDL    0xC0000000  // GT_CNS_INT -- constant is a TLS ref with offset
    #define GTF_ICON_FTN_ADDR   0xD0000000  // GT_CNS_INT -- constant is a function address
    #define GTF_ICON_CIDMID_HDL 0xE0000000  // GT_CNS_INT -- constant is a class or module ID handle
    #define GTF_ICON_BBC_PTR    0xF0000000  // GT_CNS_INT -- constant is a basic block count pointer

    #define GTF_ICON_FIELD_OFF  0x08000000  // GT_CNS_INT -- constant is a field offset

    #define GTF_BLK_HASGCPTR    0x80000000  // GT_COPYBLK -- This struct copy will copy GC Pointers
    #define GTF_BLK_VOLATILE    0x40000000  // GT_INITBLK/GT_COPYBLK -- is a volatile block operation
    #define GTF_BLK_UNALIGNED   0x02000000  // GT_INITBLK/GT_COPYBLK -- is an unaligned block operation

    #define GTF_OVERFLOW        0x10000000  // GT_ADD, GT_SUB, GT_MUL, - Need overflow check
                                            // GT_ASG_ADD, GT_ASG_SUB,
                                            // GT_CAST
                                            // Use gtOverflow(Ex)() to check this flag

    #define GTF_NO_OP_NO        0x80000000  // GT_NO_OP   --Have the codegenerator generate a special nop

    //----------------------------------------------------------------

    #define GTF_STMT_CMPADD     0x80000000  // GT_STMT    -- added by compiler
    #define GTF_STMT_HAS_CSE    0x40000000  // GT_STMT    -- CSE def or use was subsituted
    #define GTF_STMT_TOP_LEVEL  0x20000000  // GT_STMT    -- Top-level statement - true iff gtStmtList->gtPrev == nullptr
                                            //               True for all stmts when in FGOrderTree
    #define GTF_STMT_SKIP_LOWER 0x10000000  // GT_STMT    -- Skip lowering if we already lowered an embedded stmt.

    //----------------------------------------------------------------

    GenTreePtr          gtNext;
    GenTreePtr          gtPrev;

#ifdef DEBUG
    unsigned            gtTreeID;
    unsigned            gtSeqNum;       // liveness traversal order within the current statement
#endif

    static
    const unsigned short   gtOperKindTable[];

    static
    unsigned        OperKind(unsigned gtOper)
    {
        assert(gtOper < GT_COUNT);

        return  gtOperKindTable[gtOper];
    }

    unsigned        OperKind() const
    {
        assert(gtOper < GT_COUNT);

        return  gtOperKindTable[gtOper];
    }

    static bool     IsExOp(unsigned opKind)
    {
        return (opKind & GTK_EXOP) != 0;
    }
    // Returns the operKind with the GTK_EX_OP bit removed (the
    // kind of operator, unary or binary, that is extended).
    static unsigned StripExOp(unsigned opKind)
    {
        return opKind & ~GTK_EXOP;
    }

    static
    int             OperIsConst(genTreeOps gtOper)
    {
        return  (OperKind(gtOper) & GTK_CONST  ) != 0;
    }

    int             OperIsConst() const
    {
        return  (OperKind(gtOper) & GTK_CONST  ) != 0;
    }

    static
    int             OperIsLeaf(genTreeOps gtOper)
    {
        return  (OperKind(gtOper) & GTK_LEAF   ) != 0;
    }

    int             OperIsLeaf() const
    {
        return  (OperKind(gtOper) & GTK_LEAF   ) != 0;
    }

    static
    int             OperIsCompare(genTreeOps gtOper)
    {
        return  (OperKind(gtOper) & GTK_RELOP  ) != 0;
    }

    static
    bool            OperIsLocal(genTreeOps gtOper)
    {
        bool result = (OperKind(gtOper) & GTK_LOCAL) != 0;
        assert(result ==
               (gtOper == GT_LCL_VAR ||
                gtOper == GT_PHI_ARG ||
                gtOper == GT_REG_VAR ||
                gtOper == GT_LCL_FLD ||
                gtOper == GT_STORE_LCL_VAR ||
                gtOper == GT_STORE_LCL_FLD));
        return result;
    }

    static
    bool            OperIsBlkOp(genTreeOps gtOper)
    {
        return (gtOper == GT_INITBLK ||
                gtOper == GT_COPYBLK ||
                gtOper == GT_COPYOBJ);
    }

    static
    bool            OperIsCopyBlkOp(genTreeOps gtOper)
    {
        return (gtOper == GT_COPYOBJ || gtOper == GT_COPYBLK);
    }


    static
    bool            OperIsLocalAddr(genTreeOps gtOper)
    {
        return (gtOper == GT_LCL_VAR_ADDR ||
                gtOper == GT_LCL_FLD_ADDR);
    }

    static
    bool           OperIsScalarLocal(genTreeOps gtOper)
    {
        return (gtOper == GT_LCL_VAR ||
                gtOper == GT_REG_VAR ||
                gtOper == GT_STORE_LCL_VAR);
    }

    static
    bool            OperIsNonPhiLocal(genTreeOps gtOper)
    {
        return OperIsLocal(gtOper) && (gtOper != GT_PHI_ARG);
    }

    static
    bool            OperIsLocalRead(genTreeOps gtOper)
    {
        return (OperIsLocal(gtOper) && !OperIsLocalStore(gtOper));
    }

    static
    bool            OperIsLocalStore(genTreeOps gtOper)
    {
        return (gtOper == GT_STORE_LCL_VAR ||
                gtOper == GT_STORE_LCL_FLD);

    }

    static
    bool            OperIsAddrMode(genTreeOps gtOper)
    {
        return (gtOper == GT_LEA);
    }

    bool            OperIsBlkOp() const
    {
        return OperIsBlkOp(OperGet());
    }

    bool            OperIsCopyBlkOp() const
    {
        return OperIsCopyBlkOp(OperGet());
    }

    bool            OperIsAddrMode() const
    {
        return OperIsAddrMode(OperGet());
    }

    bool            OperIsLocal() const
    {
        return OperIsLocal(OperGet());
    }

    bool            OperIsLocalAddr() const
    {
        return OperIsLocalAddr(OperGet());
    }

    bool            OperIsScalarLocal() const
    {
        return OperIsScalarLocal(OperGet());
    }

    bool            OperIsNonPhiLocal() const
    {
        return OperIsNonPhiLocal(OperGet());
    }

    bool            OperIsLocalStore() const
    {
        return OperIsLocalStore(OperGet());
    }

    bool            OperIsLocalRead() const
    {
        return OperIsLocalRead(OperGet());
    }

    int             OperIsCompare()
    {
        return  (OperKind(gtOper) & GTK_RELOP  ) != 0;
    }

    static
    int             OperIsLogical(genTreeOps gtOper)
    {
        return  (OperKind(gtOper) & GTK_LOGOP  ) != 0;
    }

    int             OperIsLogical() const
    {
        return  (OperKind(gtOper) & GTK_LOGOP  ) != 0;
    }

    int             OperIsArithmetic() const
    {
        genTreeOps op = OperGet();
        return     op==GT_ADD 
                || op==GT_SUB        
                || op==GT_MUL 
                || op==GT_DIV
                || op==GT_MOD
        
                || op==GT_UDIV
                || op==GT_UMOD

                || op==GT_OR 
                || op==GT_XOR
                || op==GT_AND

                || op==GT_LSH
                || op==GT_RSH
                || op==GT_RSZ;        
        
    }

    static
    int             OperIsUnary(genTreeOps gtOper)
    {
        return  (OperKind(gtOper) & GTK_UNOP   ) != 0;
    }

    int             OperIsUnary() const
    {
        return   OperIsUnary(gtOper);
    }

    static
    int             OperIsBinary(genTreeOps gtOper)
    {
        return  (OperKind(gtOper) & GTK_BINOP  ) != 0;
    }

    int             OperIsBinary() const
    {
        return   OperIsBinary(gtOper);
    }

    static
    int             OperIsSimple(genTreeOps gtOper)
    {
        return  (OperKind(gtOper) & GTK_SMPOP  ) != 0;
    }

    static
    int             OperIsSpecial(genTreeOps gtOper)
    {        
        return  ((OperKind(gtOper) & GTK_KINDMASK) == GTK_SPECIAL);
    }

    int             OperIsSimple() const
    {
        return  OperIsSimple(gtOper);
    }

#ifdef FEATURE_SIMD
    bool             isCommutativeSIMDIntrinsic();
#else // !
    bool             isCommutativeSIMDIntrinsic()
    {
        return false;
    }
#endif // FEATURE_SIMD

    static
    int             OperIsCommutative(genTreeOps gtOper)
    {
        return  (OperKind(gtOper) & GTK_COMMUTE) != 0;
    }

    int             OperIsCommutative()
    {
        return OperIsCommutative(gtOper) || (OperIsSIMD(gtOper) && isCommutativeSIMDIntrinsic());
    }

    static
    int             OperIsAssignment(genTreeOps gtOper)
    {
        return  (OperKind(gtOper) & GTK_ASGOP) != 0;
    }

    int             OperIsAssignment() const
    {
        return  OperIsAssignment(gtOper);
    }

    static
    int             OperIsIndir(genTreeOps gtOper)
    {
        return  gtOper == GT_IND || gtOper == GT_STOREIND || gtOper == GT_NULLCHECK;
    }

    int             OperIsIndir() const
    {
        return  OperIsIndir(gtOper);
    }

    static 
    bool            OperIsImplicitIndir(genTreeOps gtOper)
    {
        switch (gtOper)
        {
        case GT_LOCKADD:
        case GT_XADD:
        case GT_CMPXCHG:
        case GT_COPYBLK:
        case GT_COPYOBJ:
        case GT_INITBLK:
        case GT_LDOBJ:
        case GT_BOX:
        case GT_ARR_INDEX:
        case GT_ARR_ELEM:
        case GT_ARR_OFFSET:
            return true;
        default:
            return false;
        }
    }

    bool            OperIsImplicitIndir() const
    {
        return  OperIsImplicitIndir(gtOper);
    }

    bool            OperIsStore() const
    {
        return OperIsStore(gtOper);
    }

    static
    bool            OperIsStore(genTreeOps gtOper)
    {
        return (gtOper == GT_STOREIND
                || gtOper == GT_STORE_LCL_VAR
                || gtOper == GT_STORE_LCL_FLD
                || gtOper == GT_STORE_CLS_VAR);
    }

    static
    int             OperIsAtomicOp(genTreeOps gtOper)
    {
        return  (gtOper == GT_XADD 
                 || gtOper == GT_XCHG  
                 || gtOper == GT_LOCKADD 
                 || gtOper == GT_CMPXCHG);
    }

    int             OperIsAtomicOp()
    {
        return  OperIsAtomicOp(gtOper);
    }

    // This is basically here for cleaner FEATURE_SIMD #ifdefs.
    static
    bool            OperIsSIMD(genTreeOps gtOper)
    {
#ifdef FEATURE_SIMD
        return gtOper == GT_SIMD;
#else // !FEATURE_SIMD
        return false;
#endif // !FEATURE_SIMD
    }

    // Requires that "op" is an op= operator.  Returns
    // the corresponding "op".
    static
    genTreeOps      OpAsgToOper(genTreeOps op);

#ifdef DEBUG
    bool            NullOp1Legal() const
    {
        assert(OperIsSimple(gtOper));
        switch (gtOper)
        {
        case GT_PHI: case GT_LEA: case GT_RETFILT: case GT_NOP:
            return true;
        case GT_RETURN:
            return gtType == TYP_VOID;
        default:
            return false;
        }
    }

    bool            NullOp2Legal() const
    {
        assert(OperIsSimple(gtOper));
        if (!OperIsBinary(gtOper))
        {
            return true;
        }
        switch (gtOper)
        {
        case GT_LIST:
        case GT_MATH:
        case GT_LEA:
        case GT_STOREIND:
        case GT_INITBLK:
        case GT_COPYBLK:
        case GT_COPYOBJ:
#ifdef FEATURE_SIMD
        case GT_SIMD:
#endif // !FEATURE_SIMD
            return true;
        default:
            return false;
        }
    }

    static
    inline bool RequiresNonNullOp2(genTreeOps oper);

#endif // DEBUG

    inline bool IsZero();

    inline bool IsBoxedValue();

    bool IsList() const
    {
        return gtOper == GT_LIST;
    }

    inline GenTreePtr MoveNext();

    inline GenTreePtr Current();

    inline GenTreePtr *pCurrent();

    inline GenTreePtr gtGetOp1();

    inline GenTreePtr gtGetOp2();

    // Given a tree node, if this is a child of that node, return the pointer to the child node so that it
    // can be modified; otherwise, return null.
    GenTreePtr*       gtGetChildPointer(GenTreePtr parent);

    // Get the parent of this node, and optionally capture the pointer to the child so that it can be modified.
    GenTreePtr        gtGetParent(GenTreePtr** parentChildPtrPtr);

    inline GenTreePtr gtEffectiveVal(bool commaOnly = false);

    // Return the child of this node if it is a GT_RELOAD or GT_COPY; otherwise simply return the node itself
    inline GenTree*   gtSkipReloadOrCopy();

    bool            OperMayThrow();

    unsigned        GetScaleIndexMul();
    unsigned        GetScaleIndexShf();
    unsigned        GetScaledIndex();

    // Returns true if "addr" is a GT_ADD node, at least one of whose arguments is an integer
    // (<= 32 bit) constant.  If it returns true, it sets "*offset" to (one of the) constant value(s), and
    // "*addr" to the other argument.
    bool            IsAddWithI32Const(GenTreePtr* addr, int* offset);

    // Insert 'node' after this node in execution order.
    void            InsertAfterSelf(GenTree* node, GenTreeStmt* stmt = nullptr);

public:

#if SMALL_TREE_NODES
    static
    unsigned char   s_gtNodeSizes[];
#endif

    static
    void            InitNodeSize();

    size_t          GetNodeSize() const;

    bool            IsNodeProperlySized() const;

    void            CopyFrom(const GenTree* src, Compiler* comp);

    static
    genTreeOps      ReverseRelop(genTreeOps relop);

    static
    genTreeOps      SwapRelop(genTreeOps relop);

    //---------------------------------------------------------------------

    static
    bool            Compare(GenTreePtr op1, GenTreePtr op2, bool swapOK = false);

    //---------------------------------------------------------------------
    #ifdef DEBUG
    //---------------------------------------------------------------------

    static
    const   char *  NodeName(genTreeOps op);

    //---------------------------------------------------------------------
    #endif
    //---------------------------------------------------------------------

    bool                        IsNothingNode       () const;
    void                        gtBashToNOP         ();

    void                        SetOper             (genTreeOps oper);  // set gtOper
    void                        SetOperResetFlags   (genTreeOps oper);  // set gtOper and reset flags

    void                        ChangeOperConst     (genTreeOps oper);  // ChangeOper(constOper)
    void                        ChangeOper          (genTreeOps oper);  // set gtOper and only keep GTF_COMMON_MASK flags
    void                        ChangeOperUnchecked (genTreeOps oper);

    bool IsLocal() const
    {
        return OperIsLocal(OperGet());
    }

    // Returns "true" iff "this" defines a local variable.  Requires "comp" to be the 
    // current compilation.  If returns "true", sets "*pLclVarTree" to the
    // tree for the local that is defined, and, if "pIsEntire" is non-null, sets "*pIsEntire" to
    // true or false, depending on whether the assignment writes to the entirety of the local
    // variable, or just a portion of it.
    bool DefinesLocal(Compiler* comp, GenTreeLclVarCommon** pLclVarTree, bool* pIsEntire = nullptr);

    // Returns true if "this" represents the address of a local, or a field of a local.  If returns true, sets
    // "*pLclVarTree" to the node indicating the local variable.  If the address is that of a field of this node,
    // sets "*pFldSeq" to the field sequence representing that field, else null.
    bool IsLocalAddrExpr(Compiler* comp, GenTreeLclVarCommon** pLclVarTree, FieldSeqNode** pFldSeq);

    // Simpler variant of the above which just returns the local node if this is an expression that 
    // yields an address into a local
    GenTreeLclVarCommon* IsLocalAddrExpr();

    // If returns "true", "this" may represent the address of a static or instance field
    // (or a field of such a field, in the case of an object field of type struct).  
    // If returns "true", then either "*pObj" is set to the object reference, 
    // or "*pStatic" is set to the baseAddr or offset to be added to the "*pFldSeq" 
    // Only one of "*pObj" or "*pStatic" will be set, the other one will be null.
    // The boolean return value only indicates that "this" *may* be a field address 
    // -- the field sequence must also be checked.  
    // If it is a field address, the field sequence will be a sequence of length >= 1, 
    // starting with an instance or static field, and optionally continuing with struct fields.
    bool IsFieldAddr(Compiler* comp, GenTreePtr* pObj, GenTreePtr* pStatic, FieldSeqNode** pFldSeq);

    // Requires "this" to be the address of an array (the child of a GT_IND labeled with GTF_IND_ARR_INDEX).
    // Sets "pArr" to the node representing the array (either an array object pointer, or perhaps a byref to the some element).
    // Sets "*pArrayType" to the class handle for the array type.
    // Sets "*inxVN" to the value number inferred for the array index.
    // Sets "*pFldSeq" to the sequence, if any, of struct fields used to index into the array element.
    void ParseArrayAddress(Compiler* comp, 
                           struct ArrayInfo* arrayInfo, 
                           GenTreePtr* pArr, 
                           ValueNum* pInxVN,
                           FieldSeqNode** pFldSeq);

    // Helper method for the above.
    void ParseArrayAddressWork(Compiler* comp, ssize_t inputMul, GenTreePtr* pArr, ValueNum* pInxVN, ssize_t* pOffset, FieldSeqNode** pFldSeq);

    // Requires "this" to be a GT_IND.  Requires the outermost caller to set "*pFldSeq" to nullptr.
    // Returns true if it is an array index expression, or access to a (sequence of) struct field(s)
    // within a struct array element.  If it returns true, sets *arrayInfo to the array information, and sets *pFldSeq to the sequence
    // of struct field accesses.
    bool ParseArrayElemForm(Compiler* comp, ArrayInfo* arrayInfo, FieldSeqNode** pFldSeq);

    // Requires "this" to be the address of a (possible) array element (or struct field within that).
    // If it is, sets "*arrayInfo" to the array access info, "*pFldSeq" to the sequence of struct fields
    // accessed within the array element, and returns true.  If not, returns "false".
    bool ParseArrayElemAddrForm(Compiler* comp, ArrayInfo* arrayInfo, FieldSeqNode** pFldSeq);

    // Requires "this" to be an int expression.  If it is a sequence of one or more integer constants added together,
    // returns true and sets "*pFldSeq" to the sequence of fields with which those constants are annotated.
    bool ParseOffsetForm(Compiler* comp, FieldSeqNode** pFldSeq);

    // Labels "*this" as an array index expression: label all constants and variables that could contribute, as part of an affine expression, to the value of the
    // of the index.
    void LabelIndex(Compiler* comp, bool isConst = true);

    // Assumes that "this" occurs in a context where it is being dereferenced as the LHS of an assignment-like
    // statement (assignment, initblk, or copyblk).  The "width" should be the number of bytes copied by the
    // operation.  Returns "true" if "this" is an address of (or within)
    // a local variable; sets "*pLclVarTree" to that local variable instance; and, if "pIsEntire" is non-null,
    // sets "*pIsEntire" to true if this assignment writes the full width of the local.
    bool DefinesLocalAddr(Compiler* comp, unsigned width, GenTreeLclVarCommon** pLclVarTree, bool* pIsEntire);

    bool                        IsRegVar            () const
    {
        return OperGet() == GT_REG_VAR?true:false;
    }
    bool                        InReg() const
    {
        return (gtFlags & GTF_REG_VAL)?true:false;       
    }
    void                        SetInReg()
    {
        gtFlags |= GTF_REG_VAL;
    }

    regNumber                   GetReg() const
    {
        return InReg() ? gtRegNum : REG_NA;
    }
    bool                        IsRegVarDeath       () const
    {
        assert(OperGet() == GT_REG_VAR);
        return (gtFlags & GTF_VAR_DEATH)?true:false;       
    }
    bool                        IsRegVarBirth       () const
    {
        assert(OperGet() == GT_REG_VAR);
        return (gtFlags & GTF_REG_BIRTH)?true:false;       
    }
    bool                        IsReverseOp() const
    {
        return (gtFlags & GTF_REVERSE_OPS)?true:false;
    }

    inline bool                 IsCnsIntOrI         () const;

    inline bool                 IsIntCnsFitsInI32   ();

    inline bool                 IsCnsFltOrDbl() const;

    inline bool                 IsCnsNonZeroFltOrDbl();    

    bool                        IsIconHandle        () const
    {
        assert(gtOper == GT_CNS_INT);
        return (gtFlags & GTF_ICON_HDL_MASK) ? true : false;
    }

    bool                        IsIconHandle        (unsigned handleType) const
    {
        assert(gtOper == GT_CNS_INT);
        assert((handleType & GTF_ICON_HDL_MASK) != 0);      // check that handleType is one of the valid GTF_ICON_* values
        assert((handleType & ~GTF_ICON_HDL_MASK) == 0);
        return (gtFlags & GTF_ICON_HDL_MASK) == handleType;
    }

    // Return just the part of the flags corresponding to the GTF_ICON_*_HDL flag. For example,
    // GTF_ICON_SCOPE_HDL. The tree node must be a const int, but it might not be a handle, in which
    // case we'll return zero.
    unsigned                    GetIconHandleFlag   () const
    {
        assert(gtOper == GT_CNS_INT);
        return (gtFlags & GTF_ICON_HDL_MASK);
    }

    // Mark this node as no longer being a handle; clear its GTF_ICON_*_HDL bits.
    void                        ClearIconHandleMask()
    {
        assert(gtOper == GT_CNS_INT);
        gtFlags &= ~GTF_ICON_HDL_MASK;
    }

    // Return true if the two GT_CNS_INT trees have the same handle flag (GTF_ICON_*_HDL).
    static bool                 SameIconHandleFlag(GenTree* t1, GenTree* t2)
    {
        return t1->GetIconHandleFlag() == t2->GetIconHandleFlag();
    }

    bool                        IsArgPlaceHolderNode() const { return OperGet() == GT_ARGPLACE; }
    bool                        IsCall              () const { return OperGet() == GT_CALL; }
    bool                        IsStatement         () const { return OperGet() == GT_STMT; }
    inline bool                 IsHelperCall        ();

    bool                        IsVarAddr           () const;
    bool                        gtOverflow          () const;
    bool                        gtOverflowEx        () const;
    bool                        gtSetFlags          () const;
    bool                        gtRequestSetFlags   ();
#ifdef DEBUG
    bool                        gtIsValid64RsltMul  ();
    static int                  gtDispFlags         (unsigned flags);
#endif

    // cast operations 
    inline var_types            CastFromType();
    inline var_types&           CastToType();

    // Returns "true" iff "*this" is an assignment (GT_ASG) tree that defines an SSA name (lcl = phi(...));
    bool IsPhiDefn();

    // Returns "true" iff "*this" is a statement containing an assignment that defines an SSA name (lcl = phi(...));
    bool IsPhiDefnStmt();

    // Can't use an assignment operator, because we need the extra "comp" argument
    // (to provide the allocator necessary for the VarSet assignment).
    // TODO-Cleanup: Not really needed now, w/o liveset on tree nodes
    void CopyTo(class Compiler* comp, const GenTree& gt);

    // Like the above, excepts assumes copying from small node to small node.
    // (Following the code it replaces, it does *not* copy the GenTree fields,
    // which CopyTo does.)
    void CopyToSmall(const GenTree& gt);

    // Because of the fact that we hid the assignment operator of "BitSet" (in DEBUG),
    // we can't synthesize an assignment operator.
    // TODO-Cleanup: Could change this w/o liveset on tree nodes
    // (This is also necessary for the VTable trick.)
    GenTree() {}

    // Returns the number of children of the current node.
    unsigned NumChildren();

    // Requires "childNum < NumChildren()".  Returns the "n"th child of "this."
    GenTreePtr GetChild(unsigned childNum);

    // The maximum possible # of children of any node.
    static const int MAX_CHILDREN = 6;

    bool IsReuseRegVal() const
    {
        // This can be extended to non-constant nodes, but not to local or indir nodes.
        if(OperIsConst() && ((gtFlags & GTF_REUSE_REG_VAL) != 0))
        {
            return true;
        }
        return false;
    }
    void SetReuseRegVal()
    {
        assert(OperIsConst());
        gtFlags |= GTF_REUSE_REG_VAL;
    }
    void ResetReuseRegVal()
    {
        assert(OperIsConst());
        gtFlags &= ~GTF_REUSE_REG_VAL;
    }

#ifdef DEBUG
  private:
    GenTree& operator=(const GenTree& gt) {
        _ASSERTE(!"Don't copy");
        return *this;
    }
#endif // DEBUG

#if DEBUGGABLE_GENTREE
    // In DEBUG builds, add a dummy virtual method, to give the debugger run-time type information.
    virtual void DummyVirt() {}

    typedef void* VtablePtr;

    VtablePtr GetVtableForOper(genTreeOps oper);
    void SetVtableForOper(genTreeOps oper);

    static VtablePtr s_vtablesForOpers[GT_COUNT];
    static VtablePtr s_vtableForOp;
#endif // DEBUGGABLE_GENTREE

  public:
    inline void* operator new(size_t sz, class Compiler*, genTreeOps oper);

    inline GenTree(genTreeOps oper, var_types type
                   DEBUG_ARG(bool largeNode = false));
};


/*****************************************************************************/
// In the current design, we never instantiate GenTreeUnOp: it exists only to be
// used as a base class.  For unary operators, we instantiate GenTreeOp, with a NULL second
// argument.  We check that this is true dynamically.  We could tighten this and get static
// checking, but that would entail accessing the first child of a unary operator via something
// like gtUnOp.gtOp1 instead of gtOp.gtOp1.
struct GenTreeUnOp: public GenTree
{
    GenTreePtr      gtOp1;

protected:
    GenTreeUnOp(genTreeOps oper, var_types type 
                DEBUG_ARG(bool largeNode = false)) : 
        GenTree(oper, type 
                DEBUG_ARG(largeNode)),
        gtOp1(nullptr)
        {}

    GenTreeUnOp(genTreeOps oper, var_types type, GenTreePtr op1 
                DEBUG_ARG(bool largeNode = false)) : 
        GenTree(oper, type 
                DEBUG_ARG(largeNode)), 
        gtOp1(op1)
        {
            assert(op1 != nullptr || NullOp1Legal());
            if (op1 != nullptr)  // Propagate effects flags from child.
                gtFlags |= op1->gtFlags & GTF_ALL_EFFECT;
        }

#if DEBUGGABLE_GENTREE
    GenTreeUnOp() : GenTree(), gtOp1(nullptr) {}
#endif
};

struct GenTreeOp: public GenTreeUnOp
{
    GenTreePtr      gtOp2;

    GenTreeOp(genTreeOps oper, var_types type, GenTreePtr op1, GenTreePtr op2 
              DEBUG_ARG(bool largeNode = false)) : 
        GenTreeUnOp(oper, type, op1 
                    DEBUG_ARG(largeNode)), 
        gtOp2(op2) 
        {
            // comparisons are always integral types
            assert(!GenTree::OperIsCompare(oper) || varTypeIsIntegral(type));
            // Binary operators, with a few exceptions, require a non-nullptr
            // second argument.
            assert(op2 != nullptr || NullOp2Legal());
            // Unary operators, on the other hand, require a null second argument.
            assert(!OperIsUnary(oper) || op2 == nullptr);
            // Propagate effects flags from child.  (UnOp handled this for first child.)
            if (op2 != nullptr)
            {
                gtFlags |= op2->gtFlags & GTF_ALL_EFFECT;
            }
        }

    // A small set of types are unary operators with optional arguments.  We use
    // this constructor to build those.
    GenTreeOp(genTreeOps oper, var_types type 
              DEBUG_ARG(bool largeNode = false)) : 
        GenTreeUnOp(oper, type 
                    DEBUG_ARG(largeNode)),
        gtOp2(nullptr)
        {
            // Unary operators with optional arguments:
            assert(oper == GT_NOP     ||
                   oper == GT_RETURN  ||
                   oper == GT_RETFILT ||
                   OperIsBlkOp(oper));
        }

#if DEBUGGABLE_GENTREE
    GenTreeOp() : GenTreeUnOp(), gtOp2(nullptr) {}
#endif
};


struct GenTreeVal: public GenTree
{
    size_t          gtVal1;

    GenTreeVal(genTreeOps oper, var_types type, ssize_t val) : 
        GenTree(oper, type),
        gtVal1(val)
        {}
#if DEBUGGABLE_GENTREE
    GenTreeVal() : GenTree() {}
#endif
};

struct GenTreeIntConCommon: public GenTree
{
    inline INT64   LngValue();
    inline void    SetLngValue(INT64 val);
    inline ssize_t IconValue();
    inline void SetIconValue(ssize_t val);
    
    GenTreeIntConCommon(genTreeOps oper, var_types type
                        DEBUG_ARG(bool largeNode = false)) : 
        GenTree(oper, type 
                DEBUG_ARG(largeNode))
        {}

#ifdef _TARGET_XARCH_
        bool FitsInAddrBase(Compiler *comp);
#endif

#if DEBUGGABLE_GENTREE
    GenTreeIntConCommon() : GenTree() {}
#endif
};

// node representing a read from a physical register
struct GenTreePhysReg: public GenTree
{
    // physregs need a field beyond gtRegNum because 
    // gtRegNum indicates the destination (and can be changed)
    // whereas reg indicates the source
    regNumber gtSrcReg;
    GenTreePhysReg(regNumber r, var_types type=TYP_I_IMPL) : 
        GenTree(GT_PHYSREG, type), gtSrcReg(r)
    {
    }
#if DEBUGGABLE_GENTREE
    GenTreePhysReg() : GenTree() {}
#endif
};

#ifndef LEGACY_BACKEND
// gtJumpTable - Switch Jump Table
//
// This node stores a DWORD constant that represents the
// absolute address of a jump table for switches.  The code 
// generator uses this table to code the destination for every case
// in an array of addresses which starting position is stored in
// this constant.
struct GenTreeJumpTable : public GenTreeIntConCommon
{
    ssize_t        gtJumpTableAddr;

    GenTreeJumpTable(var_types type
                  DEBUG_ARG(bool largeNode = false)) : 
        GenTreeIntConCommon(GT_JMPTABLE, type 
                            DEBUG_ARG(largeNode)) 
        {}
#if DEBUGGABLE_GENTREE
    GenTreeJumpTable() : GenTreeIntConCommon() {}
#endif // DEBUG
};
#endif // !LEGACY_BACKEND

/* gtIntCon -- integer constant (GT_CNS_INT) */
struct GenTreeIntCon: public GenTreeIntConCommon
{
    /* 
     * This is the GT_CNS_INT struct definition.
     * It's used to hold for both int constants and pointer handle constants.
     * For the 64-bit targets we will only use GT_CNS_INT as it used to represent all the possible sizes
     * For the 32-bit targets we use a GT_CNS_LNG to hold a 64-bit integer constant and GT_CNS_INT for all others.
     * In the future when we retarget the JIT for x86 we should consider eliminating GT_CNS_LNG
     */
    ssize_t         gtIconVal;   // Must overlap and have the same offset with the gtIconVal field in GenTreeLngCon below.
    
    /* The InitializeArray intrinsic needs to go back to the newarray statement
       to find the class handle of the array so that we can get its size.  However,
       in ngen mode, the handle in that statement does not correspond to the compile
       time handle (rather it lets you get a handle at run-time).  In that case, we also
       need to store a compile time handle, which goes in this gtCompileTimeHandle field.
    */
    ssize_t         gtCompileTimeHandle;

    // TODO-Cleanup: It's not clear what characterizes the cases where the field
    // above is used.  It may be that its uses and those of the "gtFieldSeq" field below
    // are mutually exclusive, and they could be put in a union.  Or else we should separate
    // this type into three subtypes.

    // If this constant represents the offset of one or more fields, "gtFieldSeq" represents that
    // sequence of fields.
    FieldSeqNode*   gtFieldSeq;

#if defined (LATE_DISASM)

    /*  If the constant was morphed from some other node,
        these fields enable us to get back to what the node
        originally represented. See use of gtNewIconHandleNode()
     */

    union
    {
        /* Template struct - The significant field of the other
         * structs should overlap exactly with this struct
         */

        struct
        {
            unsigned        gtIconHdl1;
            void *          gtIconHdl2;
        }
                            gtIconHdl;

        /* GT_FIELD, etc */

        struct
        {
            unsigned                gtIconCPX;
            CORINFO_CLASS_HANDLE    gtIconCls;
        }
                                    gtIconFld;
    };
#endif

    GenTreeIntCon(var_types type, ssize_t value
                  DEBUG_ARG(bool largeNode = false)) : 
        GenTreeIntConCommon(GT_CNS_INT, type 
                            DEBUG_ARG(largeNode)),
        gtIconVal(value),
        gtCompileTimeHandle(0),
        gtFieldSeq(FieldSeqStore::NotAField())
        {}

    GenTreeIntCon(var_types type, ssize_t value, FieldSeqNode* fields
                  DEBUG_ARG(bool largeNode = false)) : 
        GenTreeIntConCommon(GT_CNS_INT, type 
                            DEBUG_ARG(largeNode)),
        gtIconVal(value),
        gtCompileTimeHandle(0),
        gtFieldSeq(fields)
        {
            assert(fields != NULL);
        }

#ifdef _TARGET_64BIT_
    void TruncateOrSignExtend32()
    {        
        if (gtFlags & GTF_UNSIGNED)
        {
            gtIconVal = UINT32(gtIconVal);
        }
        else
        {
            gtIconVal = INT32(gtIconVal);
        }
    }
#endif // _TARGET_64BIT_

#if DEBUGGABLE_GENTREE
    GenTreeIntCon() : GenTreeIntConCommon() {}
#endif
};


/* gtLngCon -- long    constant (GT_CNS_LNG) */

struct GenTreeLngCon: public GenTreeIntConCommon
{
    INT64 gtLconVal;   // Must overlap and have the same offset with the gtIconVal field in GenTreeIntCon above.
    INT32 LoVal()
    {
        return (INT32)(gtLconVal & 0xffffffff);
    }

    INT32 HiVal()
    {
        return (INT32)(gtLconVal >> 32);;
    }

    GenTreeLngCon(INT64 val) : 
        GenTreeIntConCommon(GT_CNS_NATIVELONG, TYP_LONG)
        { SetLngValue(val); }
#if DEBUGGABLE_GENTREE
    GenTreeLngCon() : GenTreeIntConCommon() {}
#endif
};


inline INT64 GenTreeIntConCommon::LngValue()
{
#ifndef _TARGET_64BIT_
    assert(gtOper == GT_CNS_LNG);
    return AsLngCon()->gtLconVal;
#else
    return IconValue();
#endif
}

inline void GenTreeIntConCommon::SetLngValue(INT64 val)
{
#ifndef _TARGET_64BIT_
    assert(gtOper == GT_CNS_LNG);
    AsLngCon()->gtLconVal = val;
#else
    // Compile time asserts that these two fields overlap and have the same offsets:  gtIconVal and gtLconVal
    C_ASSERT(offsetof(GenTreeLngCon, gtLconVal) == offsetof(GenTreeIntCon, gtIconVal));
    C_ASSERT(sizeof(AsLngCon()->gtLconVal) == sizeof(AsIntCon()->gtIconVal));

    SetIconValue(ssize_t(val));
#endif
}

inline ssize_t GenTreeIntConCommon::IconValue()
{
    assert(gtOper == GT_CNS_INT);   //  We should never see a GT_CNS_LNG for a 64-bit target!
    return AsIntCon()->gtIconVal;
}

inline void GenTreeIntConCommon::SetIconValue(ssize_t val)
{
    assert(gtOper == GT_CNS_INT);   //  We should never see a GT_CNS_LNG for a 64-bit target!
    AsIntCon()->gtIconVal = val;
}

/* gtDblCon -- double  constant (GT_CNS_DBL) */

struct GenTreeDblCon: public GenTree
{
    double          gtDconVal;

    bool            isBitwiseEqual(GenTreeDblCon* other)
    {
        unsigned __int64 bits = *(unsigned __int64 *)(&gtDconVal);
        unsigned __int64 otherBits = *(unsigned __int64 *)(&(other->gtDconVal));
        return (bits == otherBits);
    }

    GenTreeDblCon(double val) : 
        GenTree(GT_CNS_DBL, TYP_DOUBLE),
        gtDconVal(val)
        {}
#if DEBUGGABLE_GENTREE
    GenTreeDblCon() : GenTree() {}
#endif
};


/* gtStrCon -- string  constant (GT_CNS_STR) */

struct GenTreeStrCon: public GenTree
{
    unsigned              gtSconCPX;
    CORINFO_MODULE_HANDLE gtScpHnd;

    // Because this node can come from an inlined method we need to
    // have the scope handle, since it will become a helper call.
    GenTreeStrCon(unsigned sconCPX, CORINFO_MODULE_HANDLE mod
                  DEBUG_ARG(bool largeNode = false)) : 
        GenTree(GT_CNS_STR, TYP_REF 
                DEBUG_ARG(largeNode)),
        gtSconCPX(sconCPX), gtScpHnd(mod)
        {}
#if DEBUGGABLE_GENTREE
    GenTreeStrCon() : GenTree() {}
#endif
};

// Common supertype of LCL_VAR, LCL_FLD, REG_VAR, PHI_ARG
// This inherits from UnOp because lclvar stores are Unops
struct GenTreeLclVarCommon: public GenTreeUnOp
{
private:
    unsigned        _gtLclNum;      // The local number. An index into the Compiler::lvaTable array.
    unsigned        _gtSsaNum;      // The SSA number.

public:
    GenTreeLclVarCommon(genTreeOps oper, var_types type, unsigned lclNum
                        DEBUG_ARG(bool largeNode = false)) : 
        GenTreeUnOp(oper, type 
                DEBUG_ARG(largeNode))
    {
        SetLclNum(lclNum);
    }

    unsigned GetLclNum() const
    {
        return _gtLclNum;
    }
    __declspec(property(get=GetLclNum))  unsigned  gtLclNum;

    void SetLclNum(unsigned lclNum)
    {
        _gtLclNum = lclNum;
        _gtSsaNum = SsaConfig::RESERVED_SSA_NUM;
    }

    unsigned GetSsaNum() const
    {
        return _gtSsaNum;
    }
    __declspec(property(get=GetSsaNum))  unsigned  gtSsaNum;

    void SetSsaNum(unsigned ssaNum)
    {
        _gtSsaNum = ssaNum;
    }

    bool HasSsaName()
    {
        return (gtSsaNum != SsaConfig::RESERVED_SSA_NUM);
    }

#if DEBUGGABLE_GENTREE
    GenTreeLclVarCommon() : GenTreeUnOp() {}
#endif
};

// gtLclVar -- load/store/addr of local variable 

struct GenTreeLclVar: public GenTreeLclVarCommon
{
    IL_OFFSET       gtLclILoffs;    // instr offset of ref (only for debug info)

    GenTreeLclVar(var_types type, unsigned lclNum, IL_OFFSET ilOffs
                  DEBUG_ARG(bool largeNode = false)) : 
        GenTreeLclVarCommon(GT_LCL_VAR, type, lclNum
                            DEBUG_ARG(largeNode)),
            gtLclILoffs(ilOffs)
            {}
    
    GenTreeLclVar(genTreeOps oper, var_types type, unsigned lclNum, IL_OFFSET ilOffs
              DEBUG_ARG(bool largeNode = false)) : 
        GenTreeLclVarCommon(oper, type, lclNum
                            DEBUG_ARG(largeNode)),
            gtLclILoffs(ilOffs)
            {
                assert(OperIsLocal(oper));
            }
    
#if DEBUGGABLE_GENTREE
    GenTreeLclVar() : GenTreeLclVarCommon() {}
#endif
};

// gtLclFld -- load/store/addr of local variable field 

struct GenTreeLclFld: public GenTreeLclVarCommon
{
    unsigned        gtLclOffs;      // offset into the variable to access

    FieldSeqNode*   gtFieldSeq;     // This LclFld node represents some sequences of accesses.

    // old/FE style constructor where load/store/addr share same opcode
    GenTreeLclFld(var_types type, unsigned lclNum, unsigned lclOffs) : 
        GenTreeLclVarCommon(GT_LCL_FLD, type, lclNum),
        gtLclOffs(lclOffs), gtFieldSeq(NULL)
        {
            assert(sizeof(*this) <= s_gtNodeSizes[GT_LCL_FLD]);
        }


    GenTreeLclFld(genTreeOps oper, var_types type, unsigned lclNum, unsigned lclOffs) : 
        GenTreeLclVarCommon(oper, type, lclNum),
        gtLclOffs(lclOffs), gtFieldSeq(NULL)
        {
            assert(sizeof(*this) <= s_gtNodeSizes[GT_LCL_FLD]);
        }
#if DEBUGGABLE_GENTREE
    GenTreeLclFld() : GenTreeLclVarCommon() {}
#endif
};

struct GenTreeRegVar: public GenTreeLclVarCommon
{
    // TODO-Cleanup: Note that the base class GenTree already has a gtRegNum field.
    // It's not clear exactly why a GT_REG_VAR has a separate field. When
    // GT_REG_VAR is created, the two are identical. It appears that they may
    // or may not remain so. In particular, there is a comment in stackfp.cpp
    // that states:
    //
    //      There used to be an assertion: assert(src->gtRegNum == src->gtRegVar.gtRegNum, ...)
    //      here, but there's actually no reason to assume that.  AFAICT, for FP vars under stack FP,
    //      src->gtRegVar.gtRegNum is the allocated stack pseudo-register, but src->gtRegNum is the
    //      FP stack position into which that is loaded to represent a particular use of the variable.
    //
    // It might be the case that only for stackfp do they ever differ.
    //
    // The following might be possible: the GT_REG_VAR node has a last use prior to a complex
    // subtree being evaluated. It could then be spilled from the register. Later,
    // it could be unspilled into a different register, which would be recorded at
    // the unspill time in the GenTree::gtRegNum, whereas GenTreeRegVar::gtRegNum
    // is left alone. It's not clear why that is useful.
    //
    // Assuming there is a particular use, like stack fp, that requires it, maybe we
    // can get rid of GT_REG_VAR and just leave it as GT_LCL_VAR, using the base class gtRegNum field.
    // If we need it for stackfp, we could add a GenTreeStackFPRegVar type, which carries both the
    // pieces of information, in a clearer and more specific way (in particular, with
    // a different member name).
    //

private:

    regNumberSmall  _gtRegNum;

public:

    GenTreeRegVar(var_types type, unsigned lclNum, regNumber regNum) : 
        GenTreeLclVarCommon(GT_REG_VAR, type, lclNum
                            )
        {
            gtRegNum = regNum;
        }

    // The register number is stored in a small format (8 bits), but the getters return and the setters take
    // a full-size (unsigned) format, to localize the casts here.

    __declspec(property(get=GetRegNum,put=SetRegNum))
    regNumber           gtRegNum;

    regNumber GetRegNum() const
    {
        return (regNumber) _gtRegNum;
    }

    void SetRegNum(regNumber reg)
    {
        _gtRegNum = (regNumberSmall) reg;
        assert(_gtRegNum == reg);
    }

#if DEBUGGABLE_GENTREE
    GenTreeRegVar() : GenTreeLclVarCommon() {}
#endif
};
                              
/* gtCast -- conversion to a different type  (GT_CAST) */

struct GenTreeCast: public GenTreeOp
{
    GenTreePtr&     CastOp() { return gtOp1; }
    var_types       gtCastType;

    GenTreeCast(var_types type, GenTreePtr op, var_types castType 
                DEBUG_ARG(bool largeNode = false)) : 
        GenTreeOp(GT_CAST, type, op, nullptr
                    DEBUG_ARG(largeNode)), 
        gtCastType(castType) 
        {}
#if DEBUGGABLE_GENTREE
    GenTreeCast() : GenTreeOp() {}
#endif
};


// GT_BOX nodes are place markers for boxed values.  The "real" tree
// for most purposes is in gtBoxOp.
struct GenTreeBox: public GenTreeUnOp
{
    // An expanded helper call to implement the "box" if we don't get
    // rid of it any other way.  Must be in same position as op1.

    GenTreePtr&      BoxOp() { return gtOp1; }
    // This is the statement that contains the assignment tree when the node is an inlined GT_BOX on a value
    // type            
    GenTreePtr       gtAsgStmtWhenInlinedBoxValue;

    GenTreeBox(var_types type, GenTreePtr boxOp, GenTreePtr asgStmtWhenInlinedBoxValue) : 
        GenTreeUnOp(GT_BOX, type, boxOp),
        gtAsgStmtWhenInlinedBoxValue(asgStmtWhenInlinedBoxValue)
        {}
#if DEBUGGABLE_GENTREE
    GenTreeBox() : GenTreeUnOp() {}
#endif
};



/* gtField  -- data member ref  (GT_FIELD) */

struct GenTreeField: public GenTree
{
    GenTreePtr      gtFldObj;
    CORINFO_FIELD_HANDLE    gtFldHnd;
    DWORD           gtFldOffset;
#ifdef FEATURE_READYTORUN_COMPILER
    CORINFO_CONST_LOOKUP gtFieldLookup;
#endif

    GenTreeField(var_types type) : 
        GenTree(GT_FIELD, type 
                ) 
        {}
#if DEBUGGABLE_GENTREE
    GenTreeField() : GenTree() {}
#endif
};

// Represents the Argument list of a call node, as a Lisp-style linked list.
// (Originally I had hoped that this could have *only* the m_arg/m_rest fields, but it turns out
// that enough of the GenTree mechanism is used that it makes sense just to make it a subtype.  But
// note that in many ways, this is *not* a "real" node of the tree, but rather a mechanism for
// giving call nodes a flexible number of children.  GenTreeArgListNodes never evaluate to registers,
// for example.)

// Note that while this extends GenTreeOp, it is *not* an EXOP.  We don't add any new fields, and one
// is free to allocate a GenTreeOp of type GT_LIST.  If you use this type, you get the convenient Current/Rest
// method names for the arguments.
struct GenTreeArgList: public GenTreeOp  
{
    GenTreePtr&      Current() { return gtOp1; }
    GenTreeArgList*& Rest()    { assert(gtOp2 == NULL || gtOp2->OperGet() == GT_LIST); return *reinterpret_cast<GenTreeArgList**>(&gtOp2); }

#if DEBUGGABLE_GENTREE
    GenTreeArgList() : GenTreeOp() {}
#endif

    GenTreeArgList(GenTreePtr arg ) : 
        GenTreeOp(GT_LIST, TYP_VOID, arg, NULL) 
        {}
      
    GenTreeArgList(GenTreePtr arg, GenTreeArgList* rest) : 
        GenTreeOp(GT_LIST, TYP_VOID, arg, rest) 
    {
        assert (arg != NULL);
        gtFlags |=  arg->gtFlags & GTF_ALL_EFFECT;
        if (rest != NULL) gtFlags |= rest->gtFlags & GTF_ALL_EFFECT;
    }
};

// There was quite a bit of confusion in the code base about which of gtOp1 and gtOp2 was the
// 'then' and 'else' clause of a colon node.  Adding these accessors, while not enforcing anything,
// at least *allows* the programmer to be obviously correct.
// However, these conventions seem backward.
// TODO-Cleanup: If we could get these accessors used everywhere, then we could switch them.
struct GenTreeColon: public GenTreeOp
{
    GenTreePtr&      ThenNode() { return gtOp2; }
    GenTreePtr&      ElseNode() { return gtOp1; }

#if DEBUGGABLE_GENTREE
    GenTreeColon() : GenTreeOp() {}
#endif

    GenTreeColon(var_types typ, GenTreePtr thenNode, GenTreePtr elseNode) : 
        GenTreeOp(GT_COLON, typ, elseNode, thenNode)
        {}
};

/* gtCall   -- method call      (GT_CALL) */
typedef class fgArgInfo *  fgArgInfoPtr;

struct GenTreeCall: public GenTree
{
    GenTreePtr        gtCallObjp;             // The instance argument ('this' pointer)
    GenTreeArgList*   gtCallArgs;             // The list of arguments in original evaluation order
    GenTreeArgList*   gtCallLateArgs;         // On x86:     The register arguments in an optimal order
                                              // On ARM/x64: - also includes any outgoing arg space arguments
                                              //             - that were evaluated into a temp LclVar
    fgArgInfoPtr      fgArgInfo;

#if !FEATURE_FIXED_OUT_ARGS
    int               regArgListCount;
    regList           regArgList;  
#endif
    
    // TODO-Throughput: Revisit this (this used to be only defined if
    // FEATURE_FIXED_OUT_ARGS was enabled, so this makes GenTreeCall 4 bytes bigger on x86). 
    CORINFO_SIG_INFO* callSig;                // Used by tail calls and to register callsites with the EE

    regMaskTP         gtCallRegUsedMask;      // mask of registers used to pass parameters

#define     GTF_CALL_M_EXPLICIT_TAILCALL       0x0001  // GT_CALL -- the call is "tail" prefixed and importer has performed tail call checks
#define     GTF_CALL_M_TAILCALL                0x0002  // GT_CALL -- the call is a tailcall
#define     GTF_CALL_M_VARARGS                 0x0004  // GT_CALL -- the call uses varargs ABI
#define     GTF_CALL_M_RETBUFFARG              0x0008  // GT_CALL -- first parameter is the return buffer argument
#define     GTF_CALL_M_DELEGATE_INV            0x0010  // GT_CALL -- call to Delegate.Invoke
#define     GTF_CALL_M_NOGCCHECK               0x0020  // GT_CALL -- not a call for computing full interruptability
#define     GTF_CALL_M_SPECIAL_INTRINSIC       0x0040  // GT_CALL -- function that could be optimized as an intrinsic 
                                                       // in special cases. Used to optimize fast way out in morphing
#define     GTF_CALL_M_UNMGD_THISCALL          0x0080  // "this" pointer (first argument) should be enregistered (only for GTF_CALL_UNMANAGED)
#define     GTF_CALL_M_VIRTSTUB_REL_INDIRECT   0x0080  // the virtstub is indirected through a relative address (only for GTF_CALL_VIRT_STUB)
#define     GTF_CALL_M_NONVIRT_SAME_THIS       0x0080  // callee "this" pointer is equal to caller this pointer (only for GTF_CALL_NONVIRT)
#define     GTF_CALL_M_FRAME_VAR_DEATH         0x0100  // GT_CALL -- the compLvFrameListRoot variable dies here (last use)

#ifndef LEGACY_BACKEND
#define     GTF_CALL_M_TAILCALL_VIA_HELPER     0x0200  // GT_CALL -- call is a tail call dispatched via tail call JIT helper.
#endif // !LEGACY_BACKEND

#if FEATURE_TAILCALL_OPT
#define     GTF_CALL_M_IMPLICIT_TAILCALL       0x0400  // GT_CALL -- call is an opportunistic tail call and importer has performed tail call checks
#endif

#define     GTF_CALL_M_PINVOKE                 0x0800  // GT_CALL -- call is a pinvoke.  This mirrors VM flag CORINFO_FLG_PINVOKE.
                                                       // A call marked as Pinvoke is not necessarily a GT_CALL_UNMANAGED. For e.g.
                                                       // an IL Stub dynamically generated for a PInvoke declaration is flagged as
                                                       // a Pinvoke but not as an unmanaged call. See impCheckForPInvokeCall() to
                                                       // know when these flags are set.

    bool IsUnmanaged()       { return (gtFlags & GTF_CALL_UNMANAGED) != 0; }
    bool NeedsNullCheck()    { return (gtFlags & GTF_CALL_NULLCHECK) != 0; }
    bool CallerPop()         { return (gtFlags & GTF_CALL_POP_ARGS) != 0;  }
    bool IsVirtual()         { return (gtFlags & GTF_CALL_VIRT_KIND_MASK) != GTF_CALL_NONVIRT; }
    bool IsVirtualStub()     { return (gtFlags & GTF_CALL_VIRT_KIND_MASK) == GTF_CALL_VIRT_STUB; }
    bool IsVirtualVtable()   { return (gtFlags & GTF_CALL_VIRT_KIND_MASK) == GTF_CALL_VIRT_VTABLE; }
    bool IsInlineCandidate() { return (gtFlags & GTF_CALL_INLINE_CANDIDATE) != 0; }

#ifndef LEGACY_BACKEND
    // Whether the method has non-standard args (i.e. passed in R10 or R11)
    // See fgMorphArgs() to know the call types for which non-standard args are inserted.
    bool HasNonStandardArgs()  { return IsUnmanaged() || (gtCallType == CT_INDIRECT && (IsVirtualStub() || gtCallCookie)); }

    // Get the count of non-standard arg count 
    int  GetNonStandardArgCount() 
    {
        if (IsUnmanaged())
        {
            // R11 = PInvoke cookie param
            return 1;
        }
        else if (gtCallType == CT_INDIRECT)
        {
            if (IsVirtualStub())
            {
                // R11 = Virtual stub param
                return 1;
            }
            else if (gtCallCookie != nullptr)
            {
                // R10 = PInvoke target param
                // R11 = PInvoke cookie param
                return 2;
            }
        }

        return 0;
    }
#endif // !LEGACY_BACKEND

    // Returns true if VM has flagged this method as CORINFO_FLG_PINVOKE.
    bool IsPInvoke()                { return (gtCallMoreFlags & GTF_CALL_M_PINVOKE) != 0; }

    // Note that the distinction of whether tail prefixed or an implicit tail call
    // is maintained on a call node till fgMorphCall() after which it will be
    // either a tail call (i.e. IsTailCall() is true) or a non-tail call.
    bool IsTailPrefixedCall()       { return (gtCallMoreFlags & GTF_CALL_M_EXPLICIT_TAILCALL) != 0; }     

    // This method returning "true" implies that tail call flowgraph morhphing has 
    // performed final checks and committed to making a tail call.
    bool IsTailCall()               { return (gtCallMoreFlags & GTF_CALL_M_TAILCALL) != 0; }

    // This method returning "true" implies that importer has performed tail call checks
    // and providing a hint that this can be converted to a tail call.
    bool CanTailCall()              { return IsTailPrefixedCall() || IsImplicitTailCall(); }

#ifndef LEGACY_BACKEND
    bool IsTailCallViaHelper()      { return IsTailCall() && (gtCallMoreFlags & GTF_CALL_M_TAILCALL_VIA_HELPER); } 
#else // LEGACY_BACKEND
    bool IsTailCallViaHelper()      { return true; }
#endif // LEGACY_BACKEND

#if FEATURE_FASTTAILCALL    
    bool IsFastTailCall()           { return IsTailCall() && !(gtCallMoreFlags & GTF_CALL_M_TAILCALL_VIA_HELPER); }
#else // !FEATURE_FASTTAILCALL
    bool IsFastTailCall()           { return false; }    
#endif // !FEATURE_FASTTAILCALL

#if FEATURE_TAILCALL_OPT
    // Returns true if this is marked for opportunistic tail calling.
    // That is, can be tail called though not explicitly prefixed with "tail" prefix.
    bool IsImplicitTailCall()       { return (gtCallMoreFlags & GTF_CALL_M_IMPLICIT_TAILCALL) != 0; }
#else // !FEATURE_TAILCALL_OPT
    bool IsImplicitTailCall()       { return false; }
#endif // !FEATURE_TAILCALL_OPT

    bool IsSameThis()      { return (gtCallMoreFlags & GTF_CALL_M_NONVIRT_SAME_THIS) != 0; } 
    bool IsDelegateInvoke(){ return (gtCallMoreFlags & GTF_CALL_M_DELEGATE_INV) != 0; } 
    bool IsVirtualStubRelativeIndir() { return (gtCallMoreFlags & GTF_CALL_M_VIRTSTUB_REL_INDIRECT) != 0; } 
    bool IsVarargs()       { return (gtCallMoreFlags & GTF_CALL_M_VARARGS) != 0; }

    unsigned short  gtCallMoreFlags;        // in addition to gtFlags
    
    unsigned char   gtCallType   :3;        // value from the gtCallTypes enumeration
    unsigned char   gtReturnType :5;        // exact return type

    CORINFO_CLASS_HANDLE    gtRetClsHnd;    // The return type handle of the call if it is a struct; used for HFAs.

    union
    {
        // only used for CALLI unmanaged calls (CT_INDIRECT)
        GenTreePtr      gtCallCookie;           
        // gtInlineCandidateInfo is only used when inlining methods 
        InlineCandidateInfo * gtInlineCandidateInfo;
        void *  gtStubCallStubAddr;             // GTF_CALL_VIRT_STUB - these are never inlined                
        CORINFO_GENERIC_HANDLE compileTimeHelperArgumentHandle; // Used to track type handle argument of dynamic helpers
    };

    // expression evaluated after args are placed which determines the control target
    GenTree * gtControlExpr; 

    union
    {
        CORINFO_METHOD_HANDLE gtCallMethHnd;  // CT_USER_FUNC
        GenTreePtr  gtCallAddr;               // CT_INDIRECT
    };

#ifdef FEATURE_READYTORUN_COMPILER
    // Call target lookup info for method call from a Ready To Run module
    CORINFO_CONST_LOOKUP gtEntryPoint;
#endif

    GenTreeCall(var_types type) : 
        GenTree(GT_CALL, type) 
        {}
#if DEBUGGABLE_GENTREE
    GenTreeCall() : GenTree() {}
#endif
};

struct GenTreeCmpXchg: public GenTree
{
    GenTreePtr      gtOpLocation;
    GenTreePtr      gtOpValue;
    GenTreePtr      gtOpComparand;

    GenTreeCmpXchg(var_types type, GenTreePtr loc, GenTreePtr val, GenTreePtr comparand) : 
        GenTree(GT_CMPXCHG, type), 
        gtOpLocation(loc), gtOpValue(val),  gtOpComparand(comparand)
        {
            // There's no reason to do a compare-exchange on a local location, so we'll assume that all of these
            // have global effects.
            gtFlags |= GTF_GLOB_EFFECT;
        }
#if DEBUGGABLE_GENTREE
    GenTreeCmpXchg() : GenTree() {}
#endif
};



struct GenTreeFptrVal: public GenTree
{
    CORINFO_METHOD_HANDLE gtFptrMethod;

#ifdef FEATURE_READYTORUN_COMPILER
    CORINFO_CONST_LOOKUP gtEntryPoint;
    CORINFO_CONST_LOOKUP gtDelegateCtor;
#endif

    GenTreeFptrVal(var_types type, CORINFO_METHOD_HANDLE meth) : 
        GenTree(GT_FTN_ADDR, type), 
        gtFptrMethod(meth) 
        {}
#if DEBUGGABLE_GENTREE
    GenTreeFptrVal() : GenTree() {}
#endif
};

/* gtQmark */
struct GenTreeQmark : public GenTreeOp
{
    // Livesets on entry to then and else subtrees
    VARSET_TP       gtThenLiveSet;
    VARSET_TP       gtElseLiveSet;
    
    // The "Compiler*" argument is not a DEBUG_ARG here because we use it to keep track of the set of
    // (possible) QMark nodes.
    GenTreeQmark(var_types type, GenTreePtr cond, GenTreePtr colonOp, class Compiler* comp);

#if DEBUGGABLE_GENTREE
    GenTreeQmark() : GenTreeOp(GT_QMARK, TYP_INT, NULL, NULL) {}
#endif
};


#if INLINE_MATH

/* gtMath   -- math intrinsic   (possibly-binary op [NULL op2 is allowed] with an additional field) */

struct GenTreeMath: public GenTreeOp
{
    CorInfoIntrinsics gtMathFN;

    GenTreeMath(var_types type, GenTreePtr op1, CorInfoIntrinsics mathFN) : 
        GenTreeOp(GT_MATH, type, op1, NULL),
        gtMathFN(mathFN)
        {}

    GenTreeMath(var_types type, GenTreePtr op1, GenTreePtr op2, CorInfoIntrinsics mathFN) : 
        GenTreeOp(GT_MATH, type, op1, op2),
        gtMathFN(mathFN)
        {}

#if DEBUGGABLE_GENTREE
    GenTreeMath() : GenTreeOp() {}
#endif
};

#endif // INLINE_MATH

#ifdef FEATURE_SIMD

/* gtSIMD   -- SIMD intrinsic   (possibly-binary op [NULL op2 is allowed] with additional fields) */
struct GenTreeSIMD: public GenTreeOp
{
    SIMDIntrinsicID         gtSIMDIntrinsicID;  // operation Id
    var_types               gtSIMDBaseType;     // SIMD vector base type
    unsigned                gtSIMDSize;         // SIMD vector size in bytes

    GenTreeSIMD(var_types type, GenTreePtr op1, SIMDIntrinsicID simdIntrinsicID, var_types baseType, unsigned size) : 
        GenTreeOp(GT_SIMD, type, op1, nullptr),
        gtSIMDIntrinsicID(simdIntrinsicID),
        gtSIMDBaseType(baseType),
        gtSIMDSize(size)
        {}

    GenTreeSIMD(var_types type, GenTreePtr op1, GenTreePtr op2, SIMDIntrinsicID simdIntrinsicID, var_types baseType, unsigned size) : 
        GenTreeOp(GT_SIMD, type, op1, op2),
        gtSIMDIntrinsicID(simdIntrinsicID),
        gtSIMDBaseType(baseType),
        gtSIMDSize(size)
        {}

#if DEBUGGABLE_GENTREE
    GenTreeSIMD() : GenTreeOp() {}
#endif
};
#endif // FEATURE_SIMD

/* gtIndex -- array access */

struct GenTreeIndex: public GenTreeOp
{
    GenTreePtr&     Arr()   { return gtOp1; }
    GenTreePtr&     Index() { return gtOp2; }

    unsigned        gtIndElemSize;  // size of elements in the array
    CORINFO_CLASS_HANDLE gtStructElemClass;   // If the element type is a struct, this is the struct type.

    GenTreeIndex(var_types type, GenTreePtr arr, GenTreePtr ind, unsigned indElemSize) :
        GenTreeOp(GT_INDEX, type, arr, ind),
        gtIndElemSize(indElemSize),
        gtStructElemClass(nullptr)  // We always initialize this after construction.
        {
#ifdef DEBUG
            static ConfigDWORD fJitSkipArrayBoundCheck;
            if (fJitSkipArrayBoundCheck.val(CLRConfig::INTERNAL_JitSkipArrayBoundCheck) == 1)
            {
                // Skip bounds check
            }
            else
#endif
            {
                // Do bounds check
                gtFlags |= GTF_INX_RNGCHK;
            }

            if (type == TYP_REF)
            {
                gtFlags |= GTF_INX_REFARR_LAYOUT;
            }

            gtFlags |= GTF_EXCEPT|GTF_GLOB_REF;
        }
#if DEBUGGABLE_GENTREE
    GenTreeIndex() : GenTreeOp() {}
#endif
};

/* gtArrLen -- array length (GT_ARR_LENGTH)
   GT_ARR_LENGTH is used for "arr.length" */

struct GenTreeArrLen: public GenTreeUnOp
{
    GenTreePtr&     ArrRef() { return gtOp1; }   // the array address node
private:
    int             gtArrLenOffset; // constant to add to "gtArrRef" to get the address of the array length.

public:
    inline int      ArrLenOffset() {
        return gtArrLenOffset;
    }

    GenTreeArrLen(var_types type, GenTreePtr arrRef, int lenOffset) : 
        GenTreeUnOp(GT_ARR_LENGTH, type, arrRef), 
        gtArrLenOffset(lenOffset)
        {}

#if DEBUGGABLE_GENTREE
    GenTreeArrLen() : GenTreeUnOp() {}
#endif
};

// This takes an array length,an index value, and the label to jump to if the index is out of range.
// It generates no result.

struct GenTreeBoundsChk: public GenTree
{
    GenTreePtr      gtArrLen;       // An expression for the length of the array being indexed.
    GenTreePtr      gtIndex;        // The index expression.

    GenTreePtr      gtIndRngFailBB; // Label to jump to for array-index-out-of-range

    /* Only out-of-ranges at same stack depth can jump to the same label (finding return address is easier)
       For delayed calling of fgSetRngChkTarget() so that the
       optimizer has a chance of eliminating some of the rng checks */
    unsigned        gtStkDepth;

    GenTreeBoundsChk(genTreeOps oper, var_types type, GenTreePtr arrLen, GenTreePtr index) : 
        GenTree(oper, type), 
        gtArrLen(arrLen), gtIndex(index), 
        gtIndRngFailBB(NULL), 
        gtStkDepth(0)
        {
            // Effects flags propagate upwards.
            gtFlags |= (arrLen->gtFlags & GTF_ALL_EFFECT);
            gtFlags |= GTF_EXCEPT;
        }
#if DEBUGGABLE_GENTREE
    GenTreeBoundsChk() : GenTree() {}
#endif

    // If the gtArrLen is really an array length, returns array reference, else "NULL".
    GenTreePtr GetArray()
    {
        if (gtArrLen->OperGet() == GT_ARR_LENGTH)
        {
            return gtArrLen->gtArrLen.ArrRef();
        }
        else
        {
            return NULL;
        }
    }
};

// gtArrElem -- general array element (GT_ARR_ELEM), for non "SZ_ARRAYS"
//              -- multidimensional arrays, or 1-d arrays with non-zero lower bounds.

struct GenTreeArrElem: public GenTree
{
    GenTreePtr      gtArrObj;

    #define         GT_ARR_MAX_RANK 3
    GenTreePtr      gtArrInds[GT_ARR_MAX_RANK]; // Indices
    unsigned char   gtArrRank;                  // Rank of the array

    unsigned char   gtArrElemSize;              // !!! Caution, this is an "unsigned char", it is used only
                                                // on the optimization path of array intrisics.
                                                // It stores the size of array elements WHEN it can fit
                                                // into an "unsigned char".
                                                // This has caused VSW 571394.
    var_types       gtArrElemType;              // The array element type

    // Requires that "inds" is a pointer to an array of "rank" GenTreePtrs for the indices.
    GenTreeArrElem(var_types type, GenTreePtr arr, unsigned char rank, unsigned char elemSize, var_types elemType, GenTreePtr* inds) : 
        GenTree(GT_ARR_ELEM, type), 
        gtArrObj(arr), gtArrRank(rank), gtArrElemSize(elemSize), gtArrElemType(elemType)
        {
            for (unsigned char i = 0; i < rank; i++) gtArrInds[i] = inds[i];
            gtFlags |= GTF_EXCEPT;
        }
#if DEBUGGABLE_GENTREE
    GenTreeArrElem() : GenTree() {}
#endif
};

//--------------------------------------------
// 
// GenTreeArrIndex (gtArrIndex): Expression to bounds-check the index for one dimension of a
//    multi-dimensional or non-zero-based array., and compute the effective index
//    (i.e. subtracting the lower bound).
//
// Notes:
//    This node is similar in some ways to GenTreeBoundsChk, which ONLY performs the check.
//    The reason that this node incorporates the check into the effective index computation is
//    to avoid duplicating the codegen, as the effective index is required to compute the
//    offset anyway.
//    TODO-CQ: Enable optimization of the lower bound and length by replacing this:
//                /--*  <arrObj>
//                +--*  <index0>
//             +--* ArrIndex[i, ]
//    with something like:
//                   /--*  <arrObj>
//                /--*  ArrLowerBound[i, ]
//                |  /--*  <arrObj>
//                +--*  ArrLen[i, ]    (either generalize GT_ARR_LENGTH or add a new node)
//                +--*  <index0>
//             +--* ArrIndex[i, ]
//    Which could, for example, be optimized to the following when known to be within bounds:
//                /--*  TempForLowerBoundDim0
//                +--*  <index0>
//             +--* - (GT_SUB)
//
struct GenTreeArrIndex: public GenTreeOp
{
    // The array object - may be any expression producing an Array reference, but is likely to be a lclVar.
    GenTreePtr&     ArrObj()    { return gtOp1; }
    // The index expression - may be any integral expression.
    GenTreePtr&     IndexExpr() { return gtOp2; }
    unsigned char   gtCurrDim;      // The current dimension
    unsigned char   gtArrRank;      // Rank of the array
    var_types       gtArrElemType;  // The array element type

    GenTreeArrIndex(var_types type, GenTreePtr arrObj, GenTreePtr indexExpr,
                  unsigned char currDim, unsigned char arrRank, var_types elemType) :
        GenTreeOp(GT_ARR_INDEX, type, arrObj, indexExpr),
                  gtCurrDim(currDim), gtArrRank(arrRank), gtArrElemType(elemType)
    {
        gtFlags |= GTF_EXCEPT;
    }
#if DEBUGGABLE_GENTREE
protected:
    friend GenTree;
    // Used only for GenTree::GetVtableForOper()
    GenTreeArrIndex() : GenTreeOp() {}
#endif
};

// Represents either an InitBlk, InitObj, CpBlk or CpObj 
// MSIL OpCode.
struct GenTreeBlkOp : public GenTreeOp
{
public:
    // The destination for the CpBlk/CpObj/InitBlk/InitObj to copy bits to
    GenTreePtr Dest()         { 
                                assert(gtOp1->gtOper == GT_LIST);
                                return gtOp1->gtOp.gtOp1;
                              }

    // True if this BlkOpNode is a volatile memory operation.
    bool IsVolatile() const { return (gtFlags & GTF_BLK_VOLATILE) != 0; }

    // Instruction selection: during codegen time, what code sequence we will be using
    // to encode this operation.
    enum
    {
        BlkOpKindInvalid,
        BlkOpKindHelper,
        BlkOpKindRepInstr,
        BlkOpKindUnroll,
    } gtBlkOpKind;

    bool gtBlkOpGcUnsafe; 

    GenTreeBlkOp(genTreeOps oper) :
        GenTreeOp(oper, TYP_VOID DEBUG_ARG(true)),
            gtBlkOpKind(BlkOpKindInvalid),
            gtBlkOpGcUnsafe(false)
    {
        assert(OperIsBlkOp(oper));
    }

#if DEBUGGABLE_GENTREE
protected:
    friend GenTree;
    GenTreeBlkOp() : GenTreeOp(){}
#endif // DEBUGGABLE_GENTREE
};

// Represents a CpObj MSIL Node.
struct GenTreeCpObj : public GenTreeBlkOp
{
public:
    // The source for the CpBlk/CpObj to copy bits from
    GenTreePtr Source()       {
        assert(gtOper == GT_COPYOBJ && gtOp1->gtOper == GT_LIST);
        return gtOp1->gtOp.gtOp2;
    }

    // In the case of CopyObj, this is the class token that represents the type that is being copied.
    GenTreePtr ClsTok() { return gtOp2; }

    // If non-null, this array represents the gc-layout of the class that is being copied
    // with CpObj.
    BYTE*       gtGcPtrs;

    // If non-zero, this is the number of slots in the class layout that 
    // contain gc-pointers.
    unsigned    gtGcPtrCount;

    // If non-zero, the number of pointer-sized slots that constitutes the class token in CpObj.
    unsigned    gtSlots;

    GenTreeCpObj(unsigned gcPtrCount, unsigned gtSlots, BYTE* gtGcPtrs) :
        GenTreeBlkOp(GT_COPYOBJ),
        gtGcPtrs(gtGcPtrs),
        gtGcPtrCount(gcPtrCount),
        gtSlots(gtSlots){ }

#if DEBUGGABLE_GENTREE
protected:
    friend GenTree;
    GenTreeCpObj() : GenTreeBlkOp(),
        gtGcPtrs(nullptr),
        gtGcPtrCount(0),
        gtSlots(0) {}
#endif // DEBUGGABLE_GENTREE
};

// Represents either an InitBlk or InitObj MSIL OpCode.
struct GenTreeInitBlk : public GenTreeBlkOp
{
public:

    // The value used to fill the destination buffer.
    GenTreePtr InitVal() { assert(gtOp1->gtOper == GT_LIST);
                           return gtOp1->gtOp.gtOp2; }

    // The size of the buffer to be copied.
    GenTreePtr Size()    { return gtOp2; }

    GenTreeInitBlk() : GenTreeBlkOp(GT_INITBLK){}

#if DEBUGGABLE_GENTREE
protected:
    friend GenTree;
#endif // DEBUGGABLE_GENTREE
};

// Represents a CpBlk or CpObj with no GC-pointers MSIL OpCode.
struct GenTreeCpBlk : public GenTreeBlkOp
{
public:

    // The value used to fill the destination buffer.
    // The source for the CpBlk/CpObj to copy bits from
    GenTreePtr Source() { assert(gtOp1->gtOper == GT_LIST);
                          return gtOp1->gtOp.gtOp2; }

    // The size of the buffer to be copied.
    GenTreePtr Size()   { return gtOp2; }

    GenTreeCpBlk() : GenTreeBlkOp(GT_COPYBLK){}

#if DEBUGGABLE_GENTREE
protected:
    friend GenTree;
#endif // DEBUGGABLE_GENTREE
};

//--------------------------------------------
// 
// GenTreeArrOffset (gtArrOffset): Expression to compute the accumulated offset for the address
//    of an element of a multi-dimensional or non-zero-based array.
//
// Notes:
//    The result of this expression is (gtOffset * dimSize) + gtIndex
//    where dimSize is the length/stride/size of the dimension, and is obtained from gtArrObj.
//    This node is generated in conjunction with the GenTreeArrIndex node, which computes the
//    effective index for a single dimension.  The sub-trees can be separately optimized, e.g.
//    within a loop body where the expression for the 0th dimension may be invariant.
//
//    Here is an example of how the tree might look for a two-dimension array reference:
//                /--*  const 0
//                |  /--* <arrObj>
//                |  +--* <index0>
//                +--* ArrIndex[i, ]
//                +--*  <arrObj>
//             /--| arrOffs[i, ]
//             |  +--*  <arrObj>
//             |  +--*  <index1>
//             +--* ArrIndex[*,j]
//             +--*  <arrObj>
//          /--| arrOffs[*,j]
//    TODO-CQ: see comment on GenTreeArrIndex for how its representation may change.  When that
//    is done, we will also want to replace the <arrObj> argument to arrOffs with the
//    ArrLen as for GenTreeArrIndex.
//
struct GenTreeArrOffs: public GenTree
{
    GenTreePtr      gtOffset;       // The accumulated offset for lower dimensions - must be TYP_I_IMPL, and
                                    // will either be a CSE temp, the constant 0, or another GenTreeArrOffs node.
    GenTreePtr      gtIndex;        // The effective index for the current dimension - must be non-negative
                                    // and can be any expression (though it is likely to be either a GenTreeArrIndex,
                                    // node, a lclVar, or a constant).
    GenTreePtr      gtArrObj;       // The array object - may be any expression producing an Array reference,
                                    // but is likely to be a lclVar.
    unsigned char   gtCurrDim;      // The current dimension
    unsigned char   gtArrRank;      // Rank of the array
    var_types       gtArrElemType;  // The array element type

    GenTreeArrOffs(var_types type, GenTreePtr offset, GenTreePtr index, GenTreePtr arrObj,
                   unsigned char currDim, unsigned char rank, var_types elemType) : 
        GenTree(GT_ARR_OFFSET, type), gtOffset(offset), gtIndex(index), gtArrObj(arrObj),
                gtCurrDim(currDim), gtArrRank(rank), gtArrElemType(elemType)
    {
        assert(index->gtFlags & GTF_EXCEPT);
        gtFlags |= GTF_EXCEPT;
    }
#if DEBUGGABLE_GENTREE
    GenTreeArrOffs() : GenTree() {}
#endif
};

/* gtAddrMode -- Target-specific canonicalized addressing expression (GT_LEA) */

struct GenTreeAddrMode: public GenTreeOp
{
    // Address is Base + Index*Scale + Offset.
    // These are the legal patterns:
    //
    //      Base                                // Base != nullptr && Index == nullptr && Scale == 0 && Offset == 0
    //      Base + Index*Scale                  // Base != nullptr && Index != nullptr && Scale != 0 && Offset == 0
    //      Base + Offset                       // Base != nullptr && Index == nullptr && Scale == 0 && Offset != 0
    //      Base + Index*Scale + Offset         // Base != nullptr && Index != nullptr && Scale != 0 && Offset != 0
    //             Index*Scale                  // Base == nullptr && Index != nullptr && Scale >  1 && Offset == 0
    //             Index*Scale + Offset         // Base == nullptr && Index != nullptr && Scale >  1 && Offset != 0
    //                           Offset         // Base == nullptr && Index == nullptr && Scale == 0 && Offset != 0
    //
    // So, for example:
    //      1. Base + Index is legal with Scale==1
    //      2. If Index is null, Scale should be zero (or unintialized / unused)
    //      3. If Scale==1, then we should have "Base" instead of "Index*Scale", and "Base + Offset" instead of "Index*Scale + Offset".

    // First operand is base address/pointer
    bool            HasBase() const     { return gtOp1 != nullptr; }
    GenTreePtr&     Base()              { return gtOp1; }

    // Second operand is scaled index value
    bool            HasIndex() const    { return gtOp2 != nullptr; }
    GenTreePtr&     Index()             { return gtOp2; }

    unsigned        gtScale;        // The scale factor
    unsigned        gtOffset;       // The offset to add

    GenTreeAddrMode(var_types type, GenTreePtr base, GenTreePtr index,
                    unsigned scale, unsigned offset) : 
        GenTreeOp(GT_LEA, type, base, index )
    {
        gtScale = scale;
        gtOffset = offset;
    }
#if DEBUGGABLE_GENTREE
protected:
    friend GenTree;
    // Used only for GenTree::GetVtableForOper()
    GenTreeAddrMode() : GenTreeOp() {}
#endif
};

// Indir is just an op, no additional data, but some additional abstractions
struct GenTreeIndir: public GenTreeOp
{
    // like an assign, op1 is the destination
    GenTreePtr&     Addr()      { return gtOp1; }

    // these methods provide an interface to the indirection node which 
    bool            HasBase();
    bool            HasIndex();
    GenTree*        Base(); 
    GenTree*        Index(); 
    unsigned        Scale();
    size_t          Offset();

    GenTreeIndir(genTreeOps oper, var_types type, GenTree *addr, GenTree *data) : 
    GenTreeOp(oper, type, addr, data)
    {
    }

#if DEBUGGABLE_GENTREE
protected:
    friend GenTree;
    // Used only for GenTree::GetVtableForOper()
    GenTreeIndir() : GenTreeOp() {}
#endif
};

// StoreInd is just a BinOp, no additional data
struct GenTreeStoreInd: public GenTreeIndir
{
    GenTreePtr&     Data()      { return gtOp2; }

    GenTreeStoreInd(var_types type, GenTree *destPtr, GenTree *data) : 
    GenTreeIndir(GT_STOREIND, type, destPtr, data)
    {
    }

#if DEBUGGABLE_GENTREE
protected:
    friend GenTree;
    // Used only for GenTree::GetVtableForOper()
    GenTreeStoreInd() : GenTreeIndir() {}
#endif
};


/* gtRetExp -- Place holder for the return expression from an inline candidate (GT_RET_EXPR) */

struct GenTreeRetExpr: public GenTree
{
    GenTreePtr      gtInlineCandidate;

#ifdef _TARGET_ARM_
    CORINFO_CLASS_HANDLE gtRetClsHnd;
#endif

    GenTreeRetExpr(var_types type) : 
        GenTree(GT_RET_EXPR, type) 
        {}
#if DEBUGGABLE_GENTREE
    GenTreeRetExpr() : GenTree() {}
#endif
};


/* gtStmt   -- 'statement expr' (GT_STMT) */

struct GenTreeStmt: public GenTree
{
    GenTreePtr      gtStmtExpr;     // root of the expression tree
    GenTreePtr      gtStmtList;     // first node (for forward walks)

    inlExpPtr       gtInlineExpList; // The inline expansion list of this statement.
                                     // This is a list of CORINFO_METHOD_HANDLEs 
                                     // that shows the history of inline expansion 
                                     // which leads to this statement. 
  
#if defined(DEBUGGING_SUPPORT) || defined(DEBUG)
    IL_OFFSETX      gtStmtILoffsx;   // instr offset (if available)
#endif

#ifdef DEBUG
    IL_OFFSET       gtStmtLastILoffs;// instr offset at end of stmt
#endif

    bool            gtStmtIsTopLevel()
    {
        return (gtFlags & GTF_STMT_TOP_LEVEL) != 0;
    }

    bool            gtStmtIsEmbedded()
    {
        return !gtStmtIsTopLevel();
    }

    // Return the next statement, if it is embedded, otherwise nullptr
    GenTreeStmt*    gtStmtNextIfEmbedded()
    {
        GenTree* nextStmt = gtNext;
        if (nextStmt != nullptr && nextStmt->gtStmt.gtStmtIsEmbedded())
        {
            return nextStmt->AsStmt();
        }
        else
        {
            return nullptr;
        }
    }

    GenTree*    gtStmtNextTopLevelStmt()
    {
        GenTree* nextStmt = gtNext;
        while (nextStmt != nullptr && nextStmt->gtStmt.gtStmtIsEmbedded())
        {
            nextStmt = nextStmt->gtNext;
        }
        return nextStmt;
    }

    __declspec(property(get=getNextStmt))
    GenTreeStmt* gtNextStmt;

    __declspec(property(get=getPrevStmt))
    GenTreeStmt* gtPrevStmt;

    GenTreeStmt* getNextStmt() 
    {
        if (gtNext == nullptr)
            return nullptr;
        else
            return gtNext->AsStmt();
    }

    GenTreeStmt* getPrevStmt() 
    {
        if (gtPrev == nullptr)
            return nullptr;
        else
            return gtPrev->AsStmt();
    }

    GenTreeStmt(GenTreePtr expr, IL_OFFSETX offset)
        : GenTree(GT_STMT, TYP_VOID)
        , gtStmtExpr(expr)
        , gtStmtList(nullptr)
        , gtInlineExpList(nullptr)
#if defined(DEBUGGING_SUPPORT) || defined(DEBUG)
        , gtStmtILoffsx(offset)
#endif
#ifdef DEBUG
        , gtStmtLastILoffs(BAD_IL_OFFSET)
#endif
    {
        // Statements can't have statements as part of their expression tree.
        assert(expr->gtOper != GT_STMT);

        gtFlags |= GTF_STMT_TOP_LEVEL;

        // Set the statement to have the same costs as the top node of the tree.
        // This is used long before costs have been assigned, so we need to copy
        // the raw costs.
        CopyRawCosts(expr);
    }

#if DEBUGGABLE_GENTREE
    GenTreeStmt() : GenTree(GT_STMT, TYP_VOID) {}
#endif
};

/* gtLdObj  -- 'push object' (GT_LDOBJ). */

struct GenTreeLdObj: public GenTreeUnOp
{
    CORINFO_CLASS_HANDLE gtClass;   // object being loaded            
    GenTreePtr *    gtFldTreeList;  // The list of trees that represents the fields of this struct

    GenTreeLdObj(var_types type, GenTreePtr op, CORINFO_CLASS_HANDLE cls) : 
        GenTreeUnOp(GT_LDOBJ, type, op),
        gtClass(cls), gtFldTreeList(NULL)
        {
            gtFlags |= GTF_GLOB_REF; // A LdObj is always a global reference.
        }
#if DEBUGGABLE_GENTREE
    GenTreeLdObj() : GenTreeUnOp() {}
#endif
};


/*  NOTE: Any tree nodes that are larger than 8 bytes (two ints or
    pointers) must be flagged as 'large' in GenTree::InitNodeSize().
 */

                
/* gtClsVar -- 'static data member' (GT_CLS_VAR) */

struct GenTreeClsVar: public GenTree
{
    CORINFO_FIELD_HANDLE    gtClsVarHnd;
    FieldSeqNode*           gtFieldSeq;

    GenTreeClsVar(var_types type, CORINFO_FIELD_HANDLE clsVarHnd, FieldSeqNode* fldSeq) : 
        GenTree(GT_CLS_VAR, type), 
        gtClsVarHnd(clsVarHnd),
        gtFieldSeq(fldSeq)
        {
            gtFlags |= GTF_GLOB_REF;
        }
#if DEBUGGABLE_GENTREE
    GenTreeClsVar() : GenTree() {}
#endif
};

/* gtArgPlace -- 'register argument placeholder' (GT_ARGPLACE) */

struct GenTreeArgPlace: public GenTree
{
    CORINFO_CLASS_HANDLE    gtArgPlaceClsHnd;    // Needed when we have a TYP_STRUCT argument

    GenTreeArgPlace(var_types type, CORINFO_CLASS_HANDLE clsHnd) : 
        GenTree(GT_ARGPLACE, type), 
        gtArgPlaceClsHnd(clsHnd) 
        {}
#if DEBUGGABLE_GENTREE
    GenTreeArgPlace() : GenTree() {}
#endif
};

/* gtLabel  -- code label target    (GT_LABEL) */

struct GenTreeLabel: public GenTree
{
    BasicBlock* gtLabBB;

    GenTreeLabel(BasicBlock* bb) : 
        GenTree(GT_LABEL, TYP_VOID), 
        gtLabBB(bb) 
        {}
#if DEBUGGABLE_GENTREE
    GenTreeLabel() : GenTree() {}
#endif
};

/* gtPhiArg -- phi node rhs argument, var = phi(phiarg, phiarg, phiarg...); GT_PHI_ARG */
struct GenTreePhiArg: public GenTreeLclVarCommon
{
    BasicBlock  *   gtPredBB;

    GenTreePhiArg(var_types type, unsigned lclNum, unsigned snum, BasicBlock* block)
        : GenTreeLclVarCommon(GT_PHI_ARG, type, lclNum)
        , gtPredBB(block)
    { 
        SetSsaNum(snum);
    }

#if DEBUGGABLE_GENTREE
    GenTreePhiArg() : GenTreeLclVarCommon() {}
#endif
};

/* gtPutArgStk -- Argument passed on stack */

struct GenTreePutArgStk: public GenTreeUnOp
{
    unsigned gtSlotNum;        // Slot number of the argument to be passed on stack

#if FEATURE_FASTTAILCALL
    bool putInIncomingArgArea;    // Whether this arg needs to be placed in incoming arg area.
                                  // By default this is false and will be placed in out-going arg area.
                                  // Fast tail calls set this to true.
                                  // In future if we need to add more such bool fields consider bit fields.

    GenTreePutArgStk(genTreeOps oper, var_types type, unsigned slotNum, bool _putInIncomingArgArea = false
                DEBUG_ARG(GenTreePtr callNode = NULL) DEBUG_ARG(bool largeNode = false)) : 
                GenTreeUnOp(oper, type DEBUG_ARG(largeNode)),
                gtSlotNum(slotNum), putInIncomingArgArea(_putInIncomingArgArea)
    {
#ifdef DEBUG
        gtCall = callNode;
#endif
    }


    GenTreePutArgStk(genTreeOps oper, var_types type, GenTreePtr op1, unsigned slotNum, bool _putInIncomingArgArea = false
                DEBUG_ARG(GenTreePtr callNode = NULL) DEBUG_ARG(bool largeNode = false)) : 
                GenTreeUnOp(oper, type, op1 DEBUG_ARG(largeNode)), 
                gtSlotNum(slotNum), putInIncomingArgArea(_putInIncomingArgArea)
    {
#ifdef DEBUG
        gtCall = callNode;
#endif
    }

#else  // !FEATURE_FASTTAIL_CALL

    GenTreePutArgStk(genTreeOps oper, var_types type, unsigned slotNum
                DEBUG_ARG(GenTreePtr callNode = NULL) DEBUG_ARG(bool largeNode = false)) : 
                GenTreeUnOp(oper, type DEBUG_ARG(largeNode)),
                gtSlotNum(slotNum)
    {
#ifdef DEBUG
        gtCall = callNode;
#endif
    }


    GenTreePutArgStk(genTreeOps oper, var_types type, GenTreePtr op1, unsigned slotNum
                DEBUG_ARG(GenTreePtr callNode = NULL) DEBUG_ARG(bool largeNode = false)) : 
                GenTreeUnOp(oper, type, op1 DEBUG_ARG(largeNode)), 
                gtSlotNum(slotNum)
    {
#ifdef DEBUG
        gtCall = callNode;
#endif
    }
#endif // FEATURE_FASTTAILCALL

#ifdef DEBUG
    GenTreePtr      gtCall;                // the call node to which this argument belongs
#endif

#if DEBUGGABLE_GENTREE
    GenTreePutArgStk() : GenTreeUnOp() {}
#endif
};

// Deferred inline functions of GenTree -- these need the subtypes above to
// be defined already.

inline bool GenTree::IsZero()
{
    if ((gtOper == GT_CNS_INT) && (gtIntConCommon.IconValue() == 0))
        return true;

    if ((gtOper == GT_CNS_LNG) && (gtIntConCommon.LngValue() == 0))
        return true;

    if ((gtOper == GT_CNS_DBL) && (gtDblCon.gtDconVal == 0.0))
        return true;
    return false;
}

inline bool GenTree::IsBoxedValue()
{
    assert(gtOper != GT_BOX || gtBox.BoxOp() != NULL);
    return (gtOper == GT_BOX) && (gtFlags & GTF_BOX_VALUE);
}

inline GenTreePtr GenTree::MoveNext()
{
    assert(IsList());
    return gtOp.gtOp2;
}

inline GenTreePtr GenTree::Current()
{
    assert(IsList());
    return gtOp.gtOp1;
}

inline GenTreePtr *GenTree::pCurrent()
{
    assert(IsList());
    return &(gtOp.gtOp1);
}

inline GenTreePtr      GenTree::gtGetOp1() 
{
    return gtOp.gtOp1;
}

#ifdef DEBUG
/* static */
inline bool GenTree::RequiresNonNullOp2(genTreeOps oper)
{
    switch (oper)
    {
    case GT_ADD:
    case GT_SUB:
    case GT_MUL:
    case GT_DIV:
    case GT_MOD:
    case GT_UDIV:
    case GT_UMOD:
    case GT_OR:
    case GT_XOR:
    case GT_AND:
    case GT_LSH:
    case GT_RSH:
    case GT_RSZ:
    case GT_INDEX:
    case GT_ASG:
    case GT_ASG_ADD:
    case GT_ASG_SUB:
    case GT_ASG_MUL:
    case GT_ASG_DIV:
    case GT_ASG_MOD:
    case GT_ASG_UDIV:
    case GT_ASG_UMOD:
    case GT_ASG_OR:
    case GT_ASG_XOR:
    case GT_ASG_AND:
    case GT_ASG_LSH:
    case GT_ASG_RSH:
    case GT_ASG_RSZ:
    case GT_EQ:
    case GT_NE:
    case GT_LT:
    case GT_LE:
    case GT_GE:
    case GT_GT:
    case GT_COMMA:
    case GT_QMARK:
    case GT_COLON:
    case GT_MKREFANY:
    case GT_INITBLK:
    case GT_COPYBLK:
        return true;
    default:
        return false;
    }
}
#endif // DEBUG

inline GenTreePtr      GenTree::gtGetOp2() 
{
    /* gtOp.gtOp2 is only valid for GTK_BINOP nodes. */

    GenTreePtr op2 = OperIsBinary() ? gtOp.gtOp2 : nullptr;

    // This documents the genTreeOps for which gtOp.gtOp2 cannot be nullptr.
    // This helps prefix in its analyis of code which calls gtGetOp2()

    assert((op2 != nullptr) || !RequiresNonNullOp2(gtOper));

    return op2;
}

inline GenTreePtr      GenTree::gtEffectiveVal(bool commaOnly)
{
    switch (gtOper)
    {
    case GT_COMMA:
        return gtOp.gtOp2->gtEffectiveVal(commaOnly);

    case GT_NOP:
        if (!commaOnly && gtOp.gtOp1 != NULL) 
            return gtOp.gtOp1->gtEffectiveVal();
        break;

    default:
        break;
    }       

    return this;
}

inline GenTree*         GenTree::gtSkipReloadOrCopy()
{
    // There can be only one reload or copy (we can't have a reload/copy of a reload/copy)
    if (gtOper == GT_RELOAD || gtOper == GT_COPY)
    {
        assert(gtGetOp1()->OperGet() != GT_RELOAD && gtGetOp1()->OperGet() != GT_COPY);
        return gtGetOp1();
    }
    return this;
}

inline bool GenTree::IsCnsIntOrI() const
{
    return (gtOper == GT_CNS_INT);
}

inline bool GenTree::IsIntCnsFitsInI32()
{
#ifdef _TARGET_64BIT_
    return IsCnsIntOrI() && ((int)gtIntConCommon.IconValue() == gtIntConCommon.IconValue());
#else // _TARGET_64BIT_
    return IsCnsIntOrI();
#endif // _TARGET_64BIT_
}

inline bool GenTree::IsCnsFltOrDbl() const
{
    return OperGet() == GT_CNS_DBL;
}

inline bool GenTree::IsCnsNonZeroFltOrDbl()
{
    if (OperGet() == GT_CNS_DBL)
    {
        double constValue = gtDblCon.gtDconVal;
        return *(__int64*)&constValue != 0;
    }

    return false;
}

inline bool GenTree::IsHelperCall() { return OperGet() == GT_CALL && gtCall.gtCallType == CT_HELPER; }

inline var_types GenTree::CastFromType() { return this->gtCast.CastOp()->TypeGet(); }
inline var_types& GenTree::CastToType()  { return this->gtCast.gtCastType; }


/*****************************************************************************/

#ifndef _WIN64
#include <poppack.h>
#endif

/*****************************************************************************/

#if     SMALL_TREE_NODES

// In debug, on some platforms (e.g., when LATE_DISASM is defined), GenTreeIntCon is bigger than GenTreeLclFld.
const
size_t              TREE_NODE_SZ_SMALL = max(sizeof(GenTreeIntCon), sizeof(GenTreeLclFld));

#endif // SMALL_TREE_NODES

const
size_t              TREE_NODE_SZ_LARGE = sizeof(GenTreeCall);

/*****************************************************************************
 * Types returned by GenTree::lvaLclVarRefs()
 */

enum varRefKinds
{
    VR_INVARIANT  = 0x00,      // an invariant value
    VR_NONE       = 0x00,
    VR_IND_REF    = 0x01,      // an object reference
    VR_IND_SCL    = 0x02,      // a non-object reference
    VR_GLB_VAR    = 0x04,      // a global (clsVar)
};
// Add a temp define to avoid merge conflict.
#define VR_IND_PTR VR_IND_REF

/*****************************************************************************/
#endif  // !GENTREE_H
/*****************************************************************************/