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[official-gcc.git] / gcc / tree.def

/* This file contains the definitions and documentation for the
   tree codes used in GCC.
   Copyright (C) 1987-2018 Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */


/* For tcc_references, tcc_expression, tcc_comparison, tcc_unary,
   tcc_binary, and tcc_statement nodes, which use struct tree_exp, the
   4th element is the number of argument slots to allocate.  This
   determines the size of the tree node object.  Other nodes use
   different structures, and the size is determined by the tree_union
   member structure; the 4th element should be zero.  Languages that
   define language-specific tcc_exceptional or tcc_constant codes must
   define the tree_size langhook to say how big they are.

   These tree codes have been sorted so that the macros in tree.h that
   check for various tree codes are optimized into range checks.  This
   gives a measurable performance improvement.  When adding a new
   code, consider its placement in relation to the other codes.

   When adding a new tree code which might appear as GIMPLE_ASSIGN RHS
   code, proper handler in chkp_compute_bounds_for_assignment may
   be required.  */

/* Any erroneous construct is parsed into a node of this type.
   This type of node is accepted without complaint in all contexts
   by later parsing activities, to avoid multiple error messages
   for one error.
   No fields in these nodes are used except the TREE_CODE.  */
DEFTREECODE (ERROR_MARK, "error_mark", tcc_exceptional, 0)

/* Used to represent a name (such as, in the DECL_NAME of a decl node).
   Internally it looks like a STRING_CST node.
   There is only one IDENTIFIER_NODE ever made for any particular name.
   Use `get_identifier' to get it (or create it, the first time).  */
DEFTREECODE (IDENTIFIER_NODE, "identifier_node", tcc_exceptional, 0)

/* Has the TREE_VALUE and TREE_PURPOSE fields.  */
/* These nodes are made into lists by chaining through the
   TREE_CHAIN field.  The elements of the list live in the
   TREE_VALUE fields, while TREE_PURPOSE fields are occasionally
   used as well to get the effect of Lisp association lists.  */
DEFTREECODE (TREE_LIST, "tree_list", tcc_exceptional, 0)

/* These nodes contain an array of tree nodes.  */
DEFTREECODE (TREE_VEC, "tree_vec", tcc_exceptional, 0)

/* A symbol binding block.  These are arranged in a tree,
   where the BLOCK_SUBBLOCKS field contains a chain of subblocks
   chained through the BLOCK_CHAIN field.
   BLOCK_SUPERCONTEXT points to the parent block.
     For a block which represents the outermost scope of a function, it
     points to the FUNCTION_DECL node.
   BLOCK_VARS points to a chain of decl nodes.
   BLOCK_CHAIN points to the next BLOCK at the same level.
   BLOCK_ABSTRACT_ORIGIN points to the original (abstract) tree node which
   this block is an instance of, or else is NULL to indicate that this
   block is not an instance of anything else.  When non-NULL, the value
   could either point to another BLOCK node or it could point to a
   FUNCTION_DECL node (e.g. in the case of a block representing the
   outermost scope of a particular inlining of a function).
   BLOCK_ABSTRACT is nonzero if the block represents an abstract
   instance of a block (i.e. one which is nested within an abstract
   instance of an inline function).
   TREE_ASM_WRITTEN is nonzero if the block was actually referenced
   in the generated assembly.  */
DEFTREECODE (BLOCK, "block", tcc_exceptional, 0)
\f
/* Each data type is represented by a tree node whose code is one of
   the following:  */
/* Each node that represents a data type has a component TYPE_SIZE
   containing a tree that is an expression for the size in bits.
   The TYPE_MODE contains the machine mode for values of this type.
   The TYPE_POINTER_TO field contains a type for a pointer to this type,
     or zero if no such has been created yet.
   The TYPE_NEXT_VARIANT field is used to chain together types
     that are variants made by type modifiers such as "const" and "volatile".
   The TYPE_MAIN_VARIANT field, in any member of such a chain,
     points to the start of the chain.
   The TYPE_NAME field contains info on the name used in the program
     for this type (for GDB symbol table output).  It is either a
     TYPE_DECL node, for types that are typedefs, or an IDENTIFIER_NODE
     in the case of structs, unions or enums that are known with a tag,
     or zero for types that have no special name.
   The TYPE_CONTEXT for any sort of type which could have a name or
    which could have named members (e.g. tagged types in C/C++) will
    point to the node which represents the scope of the given type, or
    will be NULL_TREE if the type has "file scope".  For most types, this
    will point to a BLOCK node or a FUNCTION_DECL node, but it could also
    point to a FUNCTION_TYPE node (for types whose scope is limited to the
    formal parameter list of some function type specification) or it
    could point to a RECORD_TYPE, UNION_TYPE or QUAL_UNION_TYPE node
    (for C++ "member" types).
    For non-tagged-types, TYPE_CONTEXT need not be set to anything in
    particular, since any type which is of some type category  (e.g.
    an array type or a function type) which cannot either have a name
    itself or have named members doesn't really have a "scope" per se.
  The TYPE_STUB_DECL field is used as a forward-references to names for
    ENUMERAL_TYPE, RECORD_TYPE, UNION_TYPE, and QUAL_UNION_TYPE nodes;
    see below.  */

/* The ordering of the following codes is optimized for the checking
   macros in tree.h.  Changing the order will degrade the speed of the
   compiler.  OFFSET_TYPE, ENUMERAL_TYPE, BOOLEAN_TYPE, INTEGER_TYPE,
   REAL_TYPE, POINTER_TYPE.  */

/* An offset is a pointer relative to an object.
   The TREE_TYPE field is the type of the object at the offset.
   The TYPE_OFFSET_BASETYPE points to the node for the type of object
   that the offset is relative to.  */
DEFTREECODE (OFFSET_TYPE, "offset_type", tcc_type, 0)

/* C enums.  The type node looks just like an INTEGER_TYPE node.
   The symbols for the values of the enum type are defined by
   CONST_DECL nodes, but the type does not point to them;
   however, the TYPE_VALUES is a list in which each element's TREE_PURPOSE
   is a name and the TREE_VALUE is the value (an INTEGER_CST node).  */
/* A forward reference `enum foo' when no enum named foo is defined yet
   has zero (a null pointer) in its TYPE_SIZE.  The tag name is in
   the TYPE_NAME field.  If the type is later defined, the normal
   fields are filled in.
   RECORD_TYPE, UNION_TYPE, and QUAL_UNION_TYPE forward refs are
   treated similarly.  */
DEFTREECODE (ENUMERAL_TYPE, "enumeral_type", tcc_type, 0)

/* Boolean type (true or false are the only values).  Looks like an
   INTEGRAL_TYPE.  */
DEFTREECODE (BOOLEAN_TYPE, "boolean_type", tcc_type, 0)

/* Integer types in all languages, including char in C.
   Also used for sub-ranges of other discrete types.
   Has components TYPE_MIN_VALUE, TYPE_MAX_VALUE (expressions, inclusive)
   and TYPE_PRECISION (number of bits used by this type).
   In the case of a subrange type in Pascal, the TREE_TYPE
   of this will point at the supertype (another INTEGER_TYPE,
   or an ENUMERAL_TYPE or BOOLEAN_TYPE).
   Otherwise, the TREE_TYPE is zero.  */
DEFTREECODE (INTEGER_TYPE, "integer_type", tcc_type, 0)

/* C's float and double.  Different floating types are distinguished
   by machine mode and by the TYPE_SIZE and the TYPE_PRECISION.  */
DEFTREECODE (REAL_TYPE, "real_type", tcc_type, 0)

/* The ordering of the following codes is optimized for the checking
   macros in tree.h.  Changing the order will degrade the speed of the
   compiler.  POINTER_TYPE, REFERENCE_TYPE.  Note that this range
   overlaps the previous range of ordered types.  */

/* All pointer-to-x types have code POINTER_TYPE.
   The TREE_TYPE points to the node for the type pointed to.  */
DEFTREECODE (POINTER_TYPE, "pointer_type", tcc_type, 0)

/* A reference is like a pointer except that it is coerced
   automatically to the value it points to.  Used in C++.  */
DEFTREECODE (REFERENCE_TYPE, "reference_type", tcc_type, 0)

/* The C++ decltype(nullptr) type.  */
DEFTREECODE (NULLPTR_TYPE, "nullptr_type", tcc_type, 0)

/* _Fract and _Accum types in Embedded-C.  Different fixed-point types
   are distinguished by machine mode and by the TYPE_SIZE and the
   TYPE_PRECISION.  */
DEFTREECODE (FIXED_POINT_TYPE, "fixed_point_type", tcc_type, 0)

/* The ordering of the following codes is optimized for the checking
   macros in tree.h.  Changing the order will degrade the speed of the
   compiler.  COMPLEX_TYPE, VECTOR_TYPE, ARRAY_TYPE.  */

/* Complex number types.  The TREE_TYPE field is the data type
   of the real and imaginary parts.  It must be of scalar
   arithmetic type, not including pointer type.  */
DEFTREECODE (COMPLEX_TYPE, "complex_type", tcc_type, 0)

/* Vector types.  The TREE_TYPE field is the data type of the vector
   elements.  The TYPE_PRECISION field is the number of subparts of
   the vector.  */
DEFTREECODE (VECTOR_TYPE, "vector_type", tcc_type, 0)

/* The ordering of the following codes is optimized for the checking
   macros in tree.h.  Changing the order will degrade the speed of the
   compiler.  ARRAY_TYPE, RECORD_TYPE, UNION_TYPE, QUAL_UNION_TYPE.
   Note that this range overlaps the previous range.  */

/* Types of arrays.  Special fields:
   TREE_TYPE              Type of an array element.
   TYPE_DOMAIN            Type to index by.
                            Its range of values specifies the array length.
 The field TYPE_POINTER_TO (TREE_TYPE (array_type)) is always nonzero
 and holds the type to coerce a value of that array type to in C.
 TYPE_STRING_FLAG indicates a string (in contrast to an array of chars)
 in languages (such as Chill) that make a distinction.  */
/* Array types in C or Pascal */
DEFTREECODE (ARRAY_TYPE, "array_type", tcc_type, 0)

/* Struct in C, or record in Pascal.  */
/* Special fields:
   TYPE_FIELDS  chain of FIELD_DECLs for the fields of the struct,
     VAR_DECLs, TYPE_DECLs and CONST_DECLs for record-scope variables,
     types and enumerators and FUNCTION_DECLs for methods associated
     with the type.
   A few may need to be added for Pascal.  */
/* See the comment above, before ENUMERAL_TYPE, for how
   forward references to struct tags are handled in C.  */
DEFTREECODE (RECORD_TYPE, "record_type", tcc_type, 0)

/* Union in C.  Like a struct, except that the offsets of the fields
   will all be zero.  */
/* See the comment above, before ENUMERAL_TYPE, for how
   forward references to union tags are handled in C.  */
DEFTREECODE (UNION_TYPE, "union_type", tcc_type, 0)     /* C union type */

/* Similar to UNION_TYPE, except that the expressions in DECL_QUALIFIER
   in each FIELD_DECL determine what the union contains.  The first
   field whose DECL_QUALIFIER expression is true is deemed to occupy
   the union.  */
DEFTREECODE (QUAL_UNION_TYPE, "qual_union_type", tcc_type, 0)

/* The ordering of the following codes is optimized for the checking
   macros in tree.h.  Changing the order will degrade the speed of the
   compiler.  VOID_TYPE, FUNCTION_TYPE, METHOD_TYPE.  */

/* The void type in C */
DEFTREECODE (VOID_TYPE, "void_type", tcc_type, 0)

/* Type to hold bounds for a pointer.
   Has TYPE_PRECISION component to specify number of bits used
   by this type.  */
DEFTREECODE (POINTER_BOUNDS_TYPE, "pointer_bounds_type", tcc_type, 0)

/* Type of functions.  Special fields:
   TREE_TYPE                type of value returned.
   TYPE_ARG_TYPES      list of types of arguments expected.
        this list is made of TREE_LIST nodes.
        In this list TREE_PURPOSE can be used to indicate the default
        value of parameter (used by C++ frontend).
   Types of "Procedures" in languages where they are different from functions
   have code FUNCTION_TYPE also, but then TREE_TYPE is zero or void type.  */
DEFTREECODE (FUNCTION_TYPE, "function_type", tcc_type, 0)

/* METHOD_TYPE is the type of a function which takes an extra first
   argument for "self", which is not present in the declared argument list.
   The TREE_TYPE is the return type of the method.  The TYPE_METHOD_BASETYPE
   is the type of "self".  TYPE_ARG_TYPES is the real argument list, which
   includes the hidden argument for "self".  */
DEFTREECODE (METHOD_TYPE, "method_type", tcc_type, 0)

/* This is a language-specific kind of type.
   Its meaning is defined by the language front end.
   layout_type does not know how to lay this out,
   so the front-end must do so manually.  */
DEFTREECODE (LANG_TYPE, "lang_type", tcc_type, 0)
\f
/* Expressions */

/* First, the constants.  */

DEFTREECODE (VOID_CST, "void_cst", tcc_constant, 0)

/* Contents are in an array of HOST_WIDE_INTs.

   We often access these constants both in their native precision and
   in wider precisions (with the constant being implicitly extended
   according to TYPE_SIGN).  In each case, the useful part of the array
   may be as wide as the precision requires but may be shorter when all
   of the upper bits are sign bits.  The length of the array when accessed
   in the constant's native precision is given by TREE_INT_CST_NUNITS.
   The length of the array when accessed in wider precisions is given
   by TREE_INT_CST_EXT_NUNITS.  Each element can be obtained using
   TREE_INT_CST_ELT.

   INTEGER_CST nodes can be shared, and therefore should be considered
   read only.  They should be copied before setting a flag such as
   TREE_OVERFLOW.  If an INTEGER_CST has TREE_OVERFLOW already set,
   it is known to be unique.  INTEGER_CST nodes are created for the
   integral types, for pointer types and for vector and float types in
   some circumstances.  */
DEFTREECODE (INTEGER_CST, "integer_cst", tcc_constant, 0)

/* Contents are given by POLY_INT_CST_COEFF.  */
DEFTREECODE (POLY_INT_CST, "poly_int_cst", tcc_constant, 0)

/* Contents are in TREE_REAL_CST field.  */
DEFTREECODE (REAL_CST, "real_cst", tcc_constant, 0)

/* Contents are in TREE_FIXED_CST field.  */
DEFTREECODE (FIXED_CST, "fixed_cst", tcc_constant, 0)

/* Contents are in TREE_REALPART and TREE_IMAGPART fields,
   whose contents are other constant nodes.  */
DEFTREECODE (COMPLEX_CST, "complex_cst", tcc_constant, 0)

/* See generic.texi for details.  */
DEFTREECODE (VECTOR_CST, "vector_cst", tcc_constant, 0)

/* Contents are TREE_STRING_LENGTH and the actual contents of the string.  */
DEFTREECODE (STRING_CST, "string_cst", tcc_constant, 0)

/* Declarations.  All references to names are represented as ..._DECL
   nodes.  The decls in one binding context are chained through the
   TREE_CHAIN field.  Each DECL has a DECL_NAME field which contains
   an IDENTIFIER_NODE.  (Some decls, most often labels, may have zero
   as the DECL_NAME).  DECL_CONTEXT points to the node representing
   the context in which this declaration has its scope.  For
   FIELD_DECLs, this is the RECORD_TYPE, UNION_TYPE, or
   QUAL_UNION_TYPE node that the field is a member of.  For VAR_DECL,
   PARM_DECL, FUNCTION_DECL, LABEL_DECL, and CONST_DECL nodes, this
   points to either the FUNCTION_DECL for the containing function, the
   RECORD_TYPE or UNION_TYPE for the containing type, or NULL_TREE or
   a TRANSLATION_UNIT_DECL if the given decl has "file scope".
   DECL_ABSTRACT_ORIGIN, if non-NULL, points to the original (abstract)
    ..._DECL node of which this decl is an (inlined or template expanded)
    instance.
   The TREE_TYPE field holds the data type of the object, when relevant.
    LABEL_DECLs have no data type.  For TYPE_DECL, the TREE_TYPE field
    contents are the type whose name is being declared.
   The DECL_ALIGN, DECL_SIZE,
    and DECL_MODE fields exist in decl nodes just as in type nodes.
    They are unused in LABEL_DECL, TYPE_DECL and CONST_DECL nodes.

   DECL_FIELD_BIT_OFFSET holds an integer number of bits offset for
   the location.  DECL_VOFFSET holds an expression for a variable
   offset; it is to be multiplied by DECL_VOFFSET_UNIT (an integer).
   These fields are relevant only in FIELD_DECLs and PARM_DECLs.

   DECL_INITIAL holds the value to initialize a variable to,
   or the value of a constant.  For a function, it holds the body
   (a node of type BLOCK representing the function's binding contour
   and whose body contains the function's statements.)  For a LABEL_DECL
   in C, it is a flag, nonzero if the label's definition has been seen.

   PARM_DECLs use a special field:
   DECL_ARG_TYPE is the type in which the argument is actually
    passed, which may be different from its type within the function.

   FUNCTION_DECLs use four special fields:
   DECL_ARGUMENTS holds a chain of PARM_DECL nodes for the arguments.
   DECL_RESULT holds a RESULT_DECL node for the value of a function.
    The DECL_RTL field is 0 for a function that returns no value.
    (C functions returning void have zero here.)
    The TREE_TYPE field is the type in which the result is actually
    returned.  This is usually the same as the return type of the
    FUNCTION_DECL, but it may be a wider integer type because of
    promotion.
   DECL_FUNCTION_CODE is a code number that is nonzero for
    built-in functions.  Its value is an enum built_in_function
    that says which built-in function it is.

   DECL_SOURCE_FILE holds a filename string and DECL_SOURCE_LINE
   holds a line number.  In some cases these can be the location of
   a reference, if no definition has been seen.

   DECL_ABSTRACT is nonzero if the decl represents an abstract instance
   of a decl (i.e. one which is nested within an abstract instance of a
   inline function.  */

DEFTREECODE (FUNCTION_DECL, "function_decl", tcc_declaration, 0)
DEFTREECODE (LABEL_DECL, "label_decl", tcc_declaration, 0)
/* The ordering of the following codes is optimized for the checking
   macros in tree.h.  Changing the order will degrade the speed of the
   compiler.  FIELD_DECL, VAR_DECL, CONST_DECL, PARM_DECL,
   TYPE_DECL.  */
DEFTREECODE (FIELD_DECL, "field_decl", tcc_declaration, 0)
DEFTREECODE (VAR_DECL, "var_decl", tcc_declaration, 0)
DEFTREECODE (CONST_DECL, "const_decl", tcc_declaration, 0)
DEFTREECODE (PARM_DECL, "parm_decl", tcc_declaration, 0)
DEFTREECODE (TYPE_DECL, "type_decl", tcc_declaration, 0)
DEFTREECODE (RESULT_DECL, "result_decl", tcc_declaration, 0)

/* A "declaration" of a debug temporary.  It should only appear in
   DEBUG stmts.  */
DEFTREECODE (DEBUG_EXPR_DECL, "debug_expr_decl", tcc_declaration, 0)

/* A stmt that marks the beginning of a source statement.  */
DEFTREECODE (DEBUG_BEGIN_STMT, "debug_begin_stmt", tcc_statement, 0)

/* A namespace declaration.  Namespaces appear in DECL_CONTEXT of other
   _DECLs, providing a hierarchy of names.  */
DEFTREECODE (NAMESPACE_DECL, "namespace_decl", tcc_declaration, 0)

/* A declaration import.
   The C++ FE uses this to represent a using-directive; eg:
   "using namespace foo".
   But it could be used to represent any declaration import construct.
   Whenever a declaration import appears in a lexical block, the BLOCK node
   representing that lexical block in GIMPLE will contain an IMPORTED_DECL
   node, linked via BLOCK_VARS accessor of the said BLOCK.
   For a given NODE which code is IMPORTED_DECL,
   IMPORTED_DECL_ASSOCIATED_DECL (NODE) accesses the imported declaration.  */
DEFTREECODE (IMPORTED_DECL, "imported_decl", tcc_declaration, 0)

/* A namelist declaration.
   The Fortran FE uses this to represent a namelist statement, e.g.:
   NAMELIST /namelist-group-name/ namelist-group-object-list.
   Whenever a declaration import appears in a lexical block, the BLOCK node
   representing that lexical block in GIMPLE will contain an NAMELIST_DECL
   node, linked via BLOCK_VARS accessor of the said BLOCK.
   For a given NODE which code is NAMELIST_DECL,
   NAMELIST_DECL_ASSOCIATED_DECL (NODE) accesses the imported declaration.  */
DEFTREECODE (NAMELIST_DECL, "namelist_decl", tcc_declaration, 0)

/* A translation unit.  This is not technically a declaration, since it
   can't be looked up, but it's close enough.  */
DEFTREECODE (TRANSLATION_UNIT_DECL, "translation_unit_decl",\
             tcc_declaration, 0)
\f
/* References to storage.  */

/* The ordering of the following codes is optimized for the classification
   in handled_component_p.  Keep them in a consecutive group.  */

/* Value is structure or union component.
   Operand 0 is the structure or union (an expression).
   Operand 1 is the field (a node of type FIELD_DECL).
   Operand 2, if present, is the value of DECL_FIELD_OFFSET, measured
   in units of DECL_OFFSET_ALIGN / BITS_PER_UNIT.  */
DEFTREECODE (COMPONENT_REF, "component_ref", tcc_reference, 3)

/* Reference to a group of bits within an object.  Similar to COMPONENT_REF
   except the position is given explicitly rather than via a FIELD_DECL.
   Operand 0 is the structure or union expression;
   operand 1 is a tree giving the constant number of bits being referenced;
   operand 2 is a tree giving the constant position of the first referenced bit.
   The result type width has to match the number of bits referenced.
   If the result type is integral, its signedness specifies how it is extended
   to its mode width.  */
DEFTREECODE (BIT_FIELD_REF, "bit_field_ref", tcc_reference, 3)

/* Array indexing.
   Operand 0 is the array; operand 1 is a (single) array index.
   Operand 2, if present, is a copy of TYPE_MIN_VALUE of the index.
   Operand 3, if present, is the element size, measured in units of
   the alignment of the element type.  */
DEFTREECODE (ARRAY_REF, "array_ref", tcc_reference, 4)

/* Likewise, except that the result is a range ("slice") of the array.  The
   starting index of the resulting array is taken from operand 1 and the size
   of the range is taken from the type of the expression.  */
DEFTREECODE (ARRAY_RANGE_REF, "array_range_ref", tcc_reference, 4)

/* Used only on an operand of complex type, these return
   a value of the corresponding component type.  */
DEFTREECODE (REALPART_EXPR, "realpart_expr", tcc_reference, 1)
DEFTREECODE (IMAGPART_EXPR, "imagpart_expr", tcc_reference, 1)

/* Represents viewing something of one type as being of a second type.
   This corresponds to an "Unchecked Conversion" in Ada and roughly to
   the idiom *(type2 *)&X in C.  The only operand is the value to be
   viewed as being of another type.  It is undefined if the type of the
   input and of the expression have different sizes.

   This code may also be used within the LHS of a MODIFY_EXPR, in which
   case no actual data motion may occur.  TREE_ADDRESSABLE will be set in
   this case and GCC must abort if it could not do the operation without
   generating insns.  */
DEFTREECODE (VIEW_CONVERT_EXPR, "view_convert_expr", tcc_reference, 1)

/* C unary `*' or Pascal `^'.  One operand, an expression for a pointer.  */
DEFTREECODE (INDIRECT_REF, "indirect_ref", tcc_reference, 1)

/* Used to represent lookup in a virtual method table which is dependent on
   the runtime type of an object.  Operands are:
   OBJ_TYPE_REF_EXPR: An expression that evaluates the value to use.
   OBJ_TYPE_REF_OBJECT: Is the object on whose behalf the lookup is
   being performed.  Through this the optimizers may be able to statically
   determine the dynamic type of the object.
   OBJ_TYPE_REF_TOKEN: An integer index to the virtual method table.  */
DEFTREECODE (OBJ_TYPE_REF, "obj_type_ref", tcc_expression, 3)

/* Used to represent the brace-enclosed initializers for a structure or an
   array.  It contains a sequence of component values made out of a VEC of
   constructor_elt.

   For RECORD_TYPE, UNION_TYPE, or QUAL_UNION_TYPE:
   The field INDEX of each constructor_elt is a FIELD_DECL.

   For ARRAY_TYPE:
   The field INDEX of each constructor_elt is the corresponding index.
   If the index is a RANGE_EXPR, it is a short-hand for many nodes,
   one for each index in the range.  (If the corresponding field VALUE
   has side-effects, they are evaluated once for each element.  Wrap the
   value in a SAVE_EXPR if you want to evaluate side effects only once.)

   Components that aren't present are cleared as per the C semantics,
   unless the CONSTRUCTOR_NO_CLEARING flag is set, in which case their
   value becomes undefined.  */
DEFTREECODE (CONSTRUCTOR, "constructor", tcc_exceptional, 0)

/* The expression types are mostly straightforward, with the fourth argument
   of DEFTREECODE saying how many operands there are.
   Unless otherwise specified, the operands are expressions and the
   types of all the operands and the expression must all be the same.  */

/* Contains two expressions to compute, one followed by the other.
   the first value is ignored.  The second one's value is used.  The
   type of the first expression need not agree with the other types.  */
DEFTREECODE (COMPOUND_EXPR, "compound_expr", tcc_expression, 2)

/* Assignment expression.  Operand 0 is the what to set; 1, the new value.  */
DEFTREECODE (MODIFY_EXPR, "modify_expr", tcc_expression, 2)

/* Initialization expression.  Operand 0 is the variable to initialize;
   Operand 1 is the initializer.  This differs from MODIFY_EXPR in that any
   reference to the referent of operand 0 within operand 1 is undefined.  */
DEFTREECODE (INIT_EXPR, "init_expr", tcc_expression, 2)

/* For TARGET_EXPR, operand 0 is the target of an initialization,
   operand 1 is the initializer for the target, which may be void
     if simply expanding it initializes the target.
   operand 2 is the cleanup for this node, if any.
   operand 3 is the saved initializer after this node has been
   expanded once; this is so we can re-expand the tree later.  */
DEFTREECODE (TARGET_EXPR, "target_expr", tcc_expression, 4)

/* Conditional expression ( ... ? ... : ...  in C).
   Operand 0 is the condition.
   Operand 1 is the then-value.
   Operand 2 is the else-value.
   Operand 0 may be of any type.
   Operand 1 must have the same type as the entire expression, unless
   it unconditionally throws an exception, in which case it should
   have VOID_TYPE.  The same constraints apply to operand 2.  The
   condition in operand 0 must be of integral type.

   In cfg gimple, if you do not have a selection expression, operands
   1 and 2 are NULL.  The operands are then taken from the cfg edges. */
DEFTREECODE (COND_EXPR, "cond_expr", tcc_expression, 3)

/* Represents a vector in which every element is equal to operand 0.  */
DEFTREECODE (VEC_DUPLICATE_EXPR, "vec_duplicate_expr", tcc_unary, 1)

/* Vector series created from a start (base) value and a step.

   A = VEC_SERIES_EXPR (B, C)

   means

   for (i = 0; i < N; i++)
     A[i] = B + C * i;  */
DEFTREECODE (VEC_SERIES_EXPR, "vec_series_expr", tcc_binary, 2)

/* Vector conditional expression. It is like COND_EXPR, but with
   vector operands.

   A = VEC_COND_EXPR ( X < Y, B, C)

   means

   for (i=0; i<N; i++)
     A[i] = X[i] < Y[i] ? B[i] : C[i];
*/
DEFTREECODE (VEC_COND_EXPR, "vec_cond_expr", tcc_expression, 3)

/* Vector permutation expression.  A = VEC_PERM_EXPR<v0, v1, mask> means

   N = length(mask)
   foreach i in N:
     M = mask[i] % (2*N)
     A = M < N ? v0[M] : v1[M-N]

   V0 and V1 are vectors of the same type.  MASK is an integer-typed
   vector.  The number of MASK elements must be the same with the
   number of elements in V0 and V1.  The size of the inner type
   of the MASK and of the V0 and V1 must be the same.
*/
DEFTREECODE (VEC_PERM_EXPR, "vec_perm_expr", tcc_expression, 3)

/* Declare local variables, including making RTL and allocating space.
   BIND_EXPR_VARS is a chain of VAR_DECL nodes for the variables.
   BIND_EXPR_BODY is the body, the expression to be computed using
   the variables.  The value of operand 1 becomes that of the BIND_EXPR.
   BIND_EXPR_BLOCK is the BLOCK that corresponds to these bindings
   for debugging purposes.  If this BIND_EXPR is actually expanded,
   that sets the TREE_USED flag in the BLOCK.

   The BIND_EXPR is not responsible for informing parsers
   about these variables.  If the body is coming from the input file,
   then the code that creates the BIND_EXPR is also responsible for
   informing the parser of the variables.

   If the BIND_EXPR is ever expanded, its TREE_USED flag is set.
   This tells the code for debugging symbol tables not to ignore the BIND_EXPR.
   If the BIND_EXPR should be output for debugging but will not be expanded,
   set the TREE_USED flag by hand.

   In order for the BIND_EXPR to be known at all, the code that creates it
   must also install it as a subblock in the tree of BLOCK
   nodes for the function.  */
DEFTREECODE (BIND_EXPR, "bind_expr", tcc_expression, 3)

/* Function call.  CALL_EXPRs are represented by variably-sized expression
   nodes.  There are at least three fixed operands.  Operand 0 is an
   INTEGER_CST node containing the total operand count, the number of
   arguments plus 3.  Operand 1 is the function or NULL, while operand 2 is
   is static chain argument, or NULL.  The remaining operands are the
   arguments to the call.  */
DEFTREECODE (CALL_EXPR, "call_expr", tcc_vl_exp, 3)

/* Specify a value to compute along with its corresponding cleanup.
   Operand 0 is the cleanup expression.
   The cleanup is executed by the first enclosing CLEANUP_POINT_EXPR,
   which must exist.  This differs from TRY_CATCH_EXPR in that operand 1
   is always evaluated when cleanups are run.  */
DEFTREECODE (WITH_CLEANUP_EXPR, "with_cleanup_expr", tcc_expression, 1)

/* Specify a cleanup point.
   Operand 0 is an expression that may have cleanups.  If it does, those
   cleanups are executed after the expression is expanded.

   Note that if the expression is a reference to storage, it is forced out
   of memory before the cleanups are run.  This is necessary to handle
   cases where the cleanups modify the storage referenced; in the
   expression 't.i', if 't' is a struct with an integer member 'i' and a
   cleanup which modifies 'i', the value of the expression depends on
   whether the cleanup is run before or after 't.i' is evaluated.  When
   expand_expr is run on 't.i', it returns a MEM.  This is not good enough;
   the value of 't.i' must be forced out of memory.

   As a consequence, the operand of a CLEANUP_POINT_EXPR must not have
   BLKmode, because it will not be forced out of memory.  */
DEFTREECODE (CLEANUP_POINT_EXPR, "cleanup_point_expr", tcc_expression, 1)

/* The following code is used in languages that have types where some
   field in an object of the type contains a value that is used in the
   computation of another field's offset or size and/or the size of the
   type.  The positions and/or sizes of fields can vary from object to
   object of the same type or even for one and the same object within
   its scope.

   Record types with discriminants in Ada or schema types in Pascal are
   examples of such types.  This mechanism is also used to create "fat
   pointers" for unconstrained array types in Ada; the fat pointer is a
   structure one of whose fields is a pointer to the actual array type
   and the other field is a pointer to a template, which is a structure
   containing the bounds of the array.  The bounds in the type pointed
   to by the first field in the fat pointer refer to the values in the
   template.

   When you wish to construct such a type you need "self-references"
   that allow you to reference the object having this type from the
   TYPE node, i.e. without having a variable instantiating this type.

   Such a "self-references" is done using a PLACEHOLDER_EXPR.  This is
   a node that will later be replaced with the object being referenced.
   Its type is that of the object and selects which object to use from
   a chain of references (see below).  No other slots are used in the
   PLACEHOLDER_EXPR.

   For example, if your type FOO is a RECORD_TYPE with a field BAR,
   and you need the value of <variable>.BAR to calculate TYPE_SIZE
   (FOO), just substitute <variable> above with a PLACEHOLDER_EXPR
   whose TREE_TYPE is FOO.  Then construct your COMPONENT_REF with
   the PLACEHOLDER_EXPR as the first operand (which has the correct
   type).  Later, when the size is needed in the program, the back-end
   will find this PLACEHOLDER_EXPR and generate code to calculate the
   actual size at run-time.  In the following, we describe how this
   calculation is done.

   When we wish to evaluate a size or offset, we check whether it contains a
   PLACEHOLDER_EXPR.  If it does, we call substitute_placeholder_in_expr
   passing both that tree and an expression within which the object may be
   found.  The latter expression is the object itself in the simple case of
   an Ada record with discriminant, but it can be the array in the case of an
   unconstrained array.

   In the latter case, we need the fat pointer, because the bounds of
   the array can only be accessed from it.  However, we rely here on the
   fact that the expression for the array contains the dereference of
   the fat pointer that obtained the array pointer.  */

/* Denotes a record to later be substituted before evaluating this expression.
   The type of this expression is used to find the record to replace it.  */
DEFTREECODE (PLACEHOLDER_EXPR, "placeholder_expr", tcc_exceptional, 0)

/* Simple arithmetic.  */
DEFTREECODE (PLUS_EXPR, "plus_expr", tcc_binary, 2)
DEFTREECODE (MINUS_EXPR, "minus_expr", tcc_binary, 2)
DEFTREECODE (MULT_EXPR, "mult_expr", tcc_binary, 2)

/* Pointer addition.  The first operand is always a pointer and the
   second operand is an integer of type sizetype.  */
DEFTREECODE (POINTER_PLUS_EXPR, "pointer_plus_expr", tcc_binary, 2)

/* Pointer subtraction.  The two arguments are pointers, and the result
   is a signed integer of the same precision.  Pointers are interpreted
   as unsigned, the difference is computed as if in infinite signed
   precision.  Behavior is undefined if the difference does not fit in
   the result type.  The result does not depend on the pointer type,
   it is not divided by the size of the pointed-to type.  */
DEFTREECODE (POINTER_DIFF_EXPR, "pointer_diff_expr", tcc_binary, 2)

/* Highpart multiplication.  For an integral type with precision B,
   returns bits [2B-1, B] of the full 2*B product.  */
DEFTREECODE (MULT_HIGHPART_EXPR, "mult_highpart_expr", tcc_binary, 2)

/* Division for integer result that rounds the quotient toward zero.  */
DEFTREECODE (TRUNC_DIV_EXPR, "trunc_div_expr", tcc_binary, 2)

/* Division for integer result that rounds it toward plus infinity.  */
DEFTREECODE (CEIL_DIV_EXPR, "ceil_div_expr", tcc_binary, 2)

/* Division for integer result that rounds it toward minus infinity.  */
DEFTREECODE (FLOOR_DIV_EXPR, "floor_div_expr", tcc_binary, 2)

/* Division for integer result that rounds it toward nearest integer.  */
DEFTREECODE (ROUND_DIV_EXPR, "round_div_expr", tcc_binary, 2)

/* Four kinds of remainder that go with the four kinds of division:  */

/* The sign of the remainder is that of the dividend.  */
DEFTREECODE (TRUNC_MOD_EXPR, "trunc_mod_expr", tcc_binary, 2)

/* The sign of the remainder is the opposite of that of the divisor.  */
DEFTREECODE (CEIL_MOD_EXPR, "ceil_mod_expr", tcc_binary, 2)

/* The sign of the remainder is that of the divisor.  */
DEFTREECODE (FLOOR_MOD_EXPR, "floor_mod_expr", tcc_binary, 2)

/* The sign of the remainder is not predictable.  */
DEFTREECODE (ROUND_MOD_EXPR, "round_mod_expr", tcc_binary, 2)

/* Division for real result.  */
DEFTREECODE (RDIV_EXPR, "rdiv_expr", tcc_binary, 2)

/* Division which is not supposed to need rounding.
   Used for pointer subtraction in C.  */
DEFTREECODE (EXACT_DIV_EXPR, "exact_div_expr", tcc_binary, 2)

/* Conversion of real to fixed point by truncation.  */
DEFTREECODE (FIX_TRUNC_EXPR, "fix_trunc_expr", tcc_unary, 1)

/* Conversion of an integer to a real.  */
DEFTREECODE (FLOAT_EXPR, "float_expr", tcc_unary, 1)

/* Unary negation.  */
DEFTREECODE (NEGATE_EXPR, "negate_expr", tcc_unary, 1)

/* Minimum and maximum values.  When used with floating point, if both
   operands are zeros, or if either operand is NaN, then it is unspecified
   which of the two operands is returned as the result.  */
DEFTREECODE (MIN_EXPR, "min_expr", tcc_binary, 2)
DEFTREECODE (MAX_EXPR, "max_expr", tcc_binary, 2)

/* Represents the absolute value of the operand.

   An ABS_EXPR must have either an INTEGER_TYPE or a REAL_TYPE.  The
   operand of the ABS_EXPR must have the same type.  */
DEFTREECODE (ABS_EXPR, "abs_expr", tcc_unary, 1)

/* Shift operations for shift and rotate.
   Shift means logical shift if done on an
   unsigned type, arithmetic shift if done on a signed type.
   The second operand is the number of bits to
   shift by; it need not be the same type as the first operand and result.
   Note that the result is undefined if the second operand is larger
   than or equal to the first operand's type size.

   The first operand of a shift can have either an integer or a
   (non-integer) fixed-point type.  We follow the ISO/IEC TR 18037:2004
   semantics for the latter.

   Rotates are defined for integer types only.  */
DEFTREECODE (LSHIFT_EXPR, "lshift_expr", tcc_binary, 2)
DEFTREECODE (RSHIFT_EXPR, "rshift_expr", tcc_binary, 2)
DEFTREECODE (LROTATE_EXPR, "lrotate_expr", tcc_binary, 2)
DEFTREECODE (RROTATE_EXPR, "rrotate_expr", tcc_binary, 2)

/* Bitwise operations.  Operands have same mode as result.  */
DEFTREECODE (BIT_IOR_EXPR, "bit_ior_expr", tcc_binary, 2)
DEFTREECODE (BIT_XOR_EXPR, "bit_xor_expr", tcc_binary, 2)
DEFTREECODE (BIT_AND_EXPR, "bit_and_expr", tcc_binary, 2)
DEFTREECODE (BIT_NOT_EXPR, "bit_not_expr", tcc_unary, 1)

/* ANDIF and ORIF allow the second operand not to be computed if the
   value of the expression is determined from the first operand.  AND,
   OR, and XOR always compute the second operand whether its value is
   needed or not (for side effects).  The operand may have
   BOOLEAN_TYPE or INTEGER_TYPE.  In either case, the argument will be
   either zero or one.  For example, a TRUTH_NOT_EXPR will never have
   an INTEGER_TYPE VAR_DECL as its argument; instead, a NE_EXPR will be
   used to compare the VAR_DECL to zero, thereby obtaining a node with
   value zero or one.  */
DEFTREECODE (TRUTH_ANDIF_EXPR, "truth_andif_expr", tcc_expression, 2)
DEFTREECODE (TRUTH_ORIF_EXPR, "truth_orif_expr", tcc_expression, 2)
DEFTREECODE (TRUTH_AND_EXPR, "truth_and_expr", tcc_expression, 2)
DEFTREECODE (TRUTH_OR_EXPR, "truth_or_expr", tcc_expression, 2)
DEFTREECODE (TRUTH_XOR_EXPR, "truth_xor_expr", tcc_expression, 2)
DEFTREECODE (TRUTH_NOT_EXPR, "truth_not_expr", tcc_expression, 1)

/* Relational operators.
   `EQ_EXPR' and `NE_EXPR' are allowed for any types.
   The others are allowed only for integer (or pointer or enumeral)
   or real types.
   In all cases the operands will have the same type,
   and the value is either the type used by the language for booleans
   or an integer vector type of the same size and with the same number
   of elements as the comparison operands.  True for a vector of
   comparison results has all bits set while false is equal to zero.  */
DEFTREECODE (LT_EXPR, "lt_expr", tcc_comparison, 2)
DEFTREECODE (LE_EXPR, "le_expr", tcc_comparison, 2)
DEFTREECODE (GT_EXPR, "gt_expr", tcc_comparison, 2)
DEFTREECODE (GE_EXPR, "ge_expr", tcc_comparison, 2)
DEFTREECODE (EQ_EXPR, "eq_expr", tcc_comparison, 2)
DEFTREECODE (NE_EXPR, "ne_expr", tcc_comparison, 2)

/* Additional relational operators for floating point unordered.  */
DEFTREECODE (UNORDERED_EXPR, "unordered_expr", tcc_comparison, 2)
DEFTREECODE (ORDERED_EXPR, "ordered_expr", tcc_comparison, 2)

/* These are equivalent to unordered or ...  */
DEFTREECODE (UNLT_EXPR, "unlt_expr", tcc_comparison, 2)
DEFTREECODE (UNLE_EXPR, "unle_expr", tcc_comparison, 2)
DEFTREECODE (UNGT_EXPR, "ungt_expr", tcc_comparison, 2)
DEFTREECODE (UNGE_EXPR, "unge_expr", tcc_comparison, 2)
DEFTREECODE (UNEQ_EXPR, "uneq_expr", tcc_comparison, 2)

/* This is the reverse of uneq_expr.  */
DEFTREECODE (LTGT_EXPR, "ltgt_expr", tcc_comparison, 2)

DEFTREECODE (RANGE_EXPR, "range_expr", tcc_binary, 2)

/* Represents a re-association barrier for floating point expressions
   like explicit parenthesis in fortran.  */
DEFTREECODE (PAREN_EXPR, "paren_expr", tcc_unary, 1)

/* Represents a conversion of type of a value.
   All conversions, including implicit ones, must be
   represented by CONVERT_EXPR or NOP_EXPR nodes.  */
DEFTREECODE (CONVERT_EXPR, "convert_expr", tcc_unary, 1)

/* Conversion of a pointer value to a pointer to a different
   address space.  */
DEFTREECODE (ADDR_SPACE_CONVERT_EXPR, "addr_space_convert_expr", tcc_unary, 1)

/* Conversion of a fixed-point value to an integer, a real, or a fixed-point
   value.  Or conversion of a fixed-point value from an integer, a real, or
   a fixed-point value.  */
DEFTREECODE (FIXED_CONVERT_EXPR, "fixed_convert_expr", tcc_unary, 1)

/* Represents a conversion expected to require no code to be generated.  */
DEFTREECODE (NOP_EXPR, "nop_expr", tcc_unary, 1)

/* Value is same as argument, but guaranteed not an lvalue.  */
DEFTREECODE (NON_LVALUE_EXPR, "non_lvalue_expr", tcc_unary, 1)

/* A COMPOUND_LITERAL_EXPR represents a literal that is placed in a DECL.  The
   COMPOUND_LITERAL_EXPR_DECL_EXPR is the a DECL_EXPR containing the decl
   for the anonymous object represented by the COMPOUND_LITERAL;
   the DECL_INITIAL of that decl is the CONSTRUCTOR that initializes
   the compound literal.  */
DEFTREECODE (COMPOUND_LITERAL_EXPR, "compound_literal_expr", tcc_expression, 1)

/* Represents something we computed once and will use multiple times.
   First operand is that expression.  After it is evaluated once, it
   will be replaced by the temporary variable that holds the value.  */
DEFTREECODE (SAVE_EXPR, "save_expr", tcc_expression, 1)

/* & in C.  Value is the address at which the operand's value resides.
   Operand may have any mode.  Result mode is Pmode.  */
DEFTREECODE (ADDR_EXPR, "addr_expr", tcc_expression, 1)

/* Operand0 is a function constant; result is part N of a function
   descriptor of type ptr_mode.  */
DEFTREECODE (FDESC_EXPR, "fdesc_expr", tcc_expression, 2)

/* Given a container value, a replacement value and a bit position within
   the container, produce the value that results from replacing the part of
   the container starting at the bit position with the replacement value.
   Operand 0 is a tree for the container value of integral or vector type;
   Operand 1 is a tree for the replacement value of another integral or
   the vector element type;
   Operand 2 is a tree giving the constant bit position;
   The number of bits replaced is given by the precision of the type of the
   replacement value if it is integral or by its size if it is non-integral.
   ???  The reason to make the size of the replacement implicit is to avoid
   introducing a quaternary operation.
   The replaced bits shall be fully inside the container.  If the container
   is of vector type, then these bits shall be aligned with its elements.  */
DEFTREECODE (BIT_INSERT_EXPR, "bit_insert_expr", tcc_expression, 3)

/* Given two real or integer operands of the same type,
   returns a complex value of the corresponding complex type.  */
DEFTREECODE (COMPLEX_EXPR, "complex_expr", tcc_binary, 2)

/* Complex conjugate of operand.  Used only on complex types.  */
DEFTREECODE (CONJ_EXPR, "conj_expr", tcc_unary, 1)

/* Nodes for ++ and -- in C.
   The second arg is how much to increment or decrement by.
   For a pointer, it would be the size of the object pointed to.  */
DEFTREECODE (PREDECREMENT_EXPR, "predecrement_expr", tcc_expression, 2)
DEFTREECODE (PREINCREMENT_EXPR, "preincrement_expr", tcc_expression, 2)
DEFTREECODE (POSTDECREMENT_EXPR, "postdecrement_expr", tcc_expression, 2)
DEFTREECODE (POSTINCREMENT_EXPR, "postincrement_expr", tcc_expression, 2)

/* Used to implement `va_arg'.  */
DEFTREECODE (VA_ARG_EXPR, "va_arg_expr", tcc_expression, 1)

/* Evaluate operand 0.  If and only if an exception is thrown during
   the evaluation of operand 0, evaluate operand 1.

   This differs from TRY_FINALLY_EXPR in that operand 1 is not evaluated
   on a normal or jump exit, only on an exception.  */
DEFTREECODE (TRY_CATCH_EXPR, "try_catch_expr", tcc_statement, 2)

/* Evaluate the first operand.
   The second operand is a cleanup expression which is evaluated
   on any exit (normal, exception, or jump out) from this expression.  */
DEFTREECODE (TRY_FINALLY_EXPR, "try_finally", tcc_statement, 2)
\f
/* These types of expressions have no useful value,
   and always have side effects.  */

/* Used to represent a local declaration. The operand is DECL_EXPR_DECL.  */
DEFTREECODE (DECL_EXPR, "decl_expr", tcc_statement, 1)

/* A label definition, encapsulated as a statement.
   Operand 0 is the LABEL_DECL node for the label that appears here.
   The type should be void and the value should be ignored.  */
DEFTREECODE (LABEL_EXPR, "label_expr", tcc_statement, 1)

/* GOTO.  Operand 0 is a LABEL_DECL node or an expression.
   The type should be void and the value should be ignored.  */
DEFTREECODE (GOTO_EXPR, "goto_expr", tcc_statement, 1)

/* RETURN.  Evaluates operand 0, then returns from the current function.
   Presumably that operand is an assignment that stores into the
   RESULT_DECL that hold the value to be returned.
   The operand may be null.
   The type should be void and the value should be ignored.  */
DEFTREECODE (RETURN_EXPR, "return_expr", tcc_statement, 1)

/* Exit the inner most loop conditionally.  Operand 0 is the condition.
   The type should be void and the value should be ignored.  */
DEFTREECODE (EXIT_EXPR, "exit_expr", tcc_statement, 1)

/* A loop.  Operand 0 is the body of the loop.
   It must contain an EXIT_EXPR or is an infinite loop.
   The type should be void and the value should be ignored.  */
DEFTREECODE (LOOP_EXPR, "loop_expr", tcc_statement, 1)

/* Switch expression.

   TREE_TYPE is the original type of the condition, before any
   language required type conversions.  It may be NULL, in which case
   the original type and final types are assumed to be the same.

   Operand 0 is the expression used to perform the branch,
   Operand 1 is the body of the switch, which probably contains
     CASE_LABEL_EXPRs.  It may also be NULL, in which case operand 2
     must not be NULL.  */
DEFTREECODE (SWITCH_EXPR, "switch_expr", tcc_statement, 2)

/* Used to represent a case label.

   Operand 0 is CASE_LOW.  It may be NULL_TREE, in which case the label
     is a 'default' label.
   Operand 1 is CASE_HIGH.  If it is NULL_TREE, the label is a simple
     (one-value) case label.  If it is non-NULL_TREE, the case is a range.
   Operand 2 is CASE_LABEL, which is is the corresponding LABEL_DECL.
   Operand 3 is CASE_CHAIN.  This operand is only used in tree-cfg.c to
     speed up the lookup of case labels which use a particular edge in
     the control flow graph.  */
DEFTREECODE (CASE_LABEL_EXPR, "case_label_expr", tcc_statement, 4)

/* Used to represent an inline assembly statement.  ASM_STRING returns a
   STRING_CST for the instruction (e.g., "mov x, y"). ASM_OUTPUTS,
   ASM_INPUTS, and ASM_CLOBBERS represent the outputs, inputs, and clobbers
   for the statement.  ASM_LABELS, if present, indicates various destinations
   for the asm; labels cannot be combined with outputs.  */
DEFTREECODE (ASM_EXPR, "asm_expr", tcc_statement, 5)

/* Variable references for SSA analysis.  New SSA names are created every
   time a variable is assigned a new value.  The SSA builder uses SSA_NAME
   nodes to implement SSA versioning.  */
DEFTREECODE (SSA_NAME, "ssa_name", tcc_exceptional, 0)

/* Used to represent a typed exception handler.  CATCH_TYPES is the type (or
   list of types) handled, and CATCH_BODY is the code for the handler.  */
DEFTREECODE (CATCH_EXPR, "catch_expr", tcc_statement, 2)

/* Used to represent an exception specification.  EH_FILTER_TYPES is a list
   of allowed types, and EH_FILTER_FAILURE is an expression to evaluate on
   failure.  */
DEFTREECODE (EH_FILTER_EXPR, "eh_filter_expr", tcc_statement, 2)

/* Node used for describing a property that is known at compile
   time.  */
DEFTREECODE (SCEV_KNOWN, "scev_known", tcc_expression, 0)

/* Node used for describing a property that is not known at compile
   time.  */
DEFTREECODE (SCEV_NOT_KNOWN, "scev_not_known", tcc_expression, 0)

/* Polynomial chains of recurrences.
   cr = {CHREC_LEFT (cr), +, CHREC_RIGHT (cr)}_CHREC_VARIABLE (cr).  */
DEFTREECODE (POLYNOMIAL_CHREC, "polynomial_chrec", tcc_expression, 2)

/* Used to chain children of container statements together.
   Use the interface in tree-iterator.h to access this node.  */
DEFTREECODE (STATEMENT_LIST, "statement_list", tcc_exceptional, 0)

/* Predicate assertion.  Artificial expression generated by the optimizers
   to keep track of predicate values.  This expression may only appear on
   the RHS of assignments.

   Given X = ASSERT_EXPR <Y, EXPR>, the optimizers can infer
   two things:

        1- X is a copy of Y.
        2- EXPR is a conditional expression and is known to be true.

   Valid and to be expected forms of conditional expressions are
   valid GIMPLE conditional expressions (as defined by is_gimple_condexpr)
   and conditional expressions with the first operand being a
   PLUS_EXPR with a variable possibly wrapped in a NOP_EXPR first
   operand and an integer constant second operand.

   The type of the expression is the same as Y.  */
DEFTREECODE (ASSERT_EXPR, "assert_expr", tcc_expression, 2)

/* Base class information. Holds information about a class as a
   baseclass of itself or another class.  */
DEFTREECODE (TREE_BINFO, "tree_binfo", tcc_exceptional, 0)

/* Records the size for an expression of variable size type.  This is
   for use in contexts in which we are accessing the entire object,
   such as for a function call, or block copy.
   Operand 0 is the real expression.
   Operand 1 is the size of the type in the expression.  */
DEFTREECODE (WITH_SIZE_EXPR, "with_size_expr", tcc_expression, 2)

/* Extract elements from two input vectors Operand 0 and Operand 1
   size VS, according to the offset OFF defined by Operand 2 as
   follows:
   If OFF > 0, the last VS - OFF elements of vector OP0 are concatenated to
   the first OFF elements of the vector OP1.
   If OFF == 0, then the returned vector is OP1.
   On different targets OFF may take different forms; It can be an address, in
   which case its low log2(VS)-1 bits define the offset, or it can be a mask
   generated by the builtin targetm.vectorize.mask_for_load_builtin_decl.  */
DEFTREECODE (REALIGN_LOAD_EXPR, "realign_load", tcc_expression, 3)

/* Low-level memory addressing.  Operands are BASE (address of static or
   global variable or register), OFFSET (integer constant),
   INDEX (register), STEP (integer constant), INDEX2 (register),
   The corresponding address is BASE + STEP * INDEX + INDEX2 + OFFSET.
   Only variations and values valid on the target are allowed.

   The type of STEP, INDEX and INDEX2 is sizetype.

   The type of BASE is a pointer type.  If BASE is not an address of
   a static or global variable INDEX2 will be NULL.

   The type of OFFSET is a pointer type and determines TBAA the same as
   the constant offset operand in MEM_REF.  */

DEFTREECODE (TARGET_MEM_REF, "target_mem_ref", tcc_reference, 5)

/* Memory addressing.  Operands are a pointer and a tree constant integer
   byte offset of the pointer type that when dereferenced yields the
   type of the base object the pointer points into and which is used for
   TBAA purposes.
   The type of the MEM_REF is the type the bytes at the memory location
   are interpreted as.
   MEM_REF <p, c> is equivalent to ((typeof(c))p)->x... where x... is a
   chain of component references offsetting p by c.  */
DEFTREECODE (MEM_REF, "mem_ref", tcc_reference, 2)

/* OpenACC and OpenMP.  As it is exposed in TREE_RANGE_CHECK invocations, do
   not change the ordering of these codes.  */

/* OpenACC - #pragma acc parallel [clause1 ... clauseN]
   Operand 0: OMP_BODY: Code to be executed in parallel.
   Operand 1: OMP_CLAUSES: List of clauses.  */

DEFTREECODE (OACC_PARALLEL, "oacc_parallel", tcc_statement, 2)

/* OpenACC - #pragma acc kernels [clause1 ... clauseN]
   Operand 0: OMP_BODY: Sequence of kernels.
   Operand 1: OMP_CLAUSES: List of clauses.  */

DEFTREECODE (OACC_KERNELS, "oacc_kernels", tcc_statement, 2)

/* OpenACC - #pragma acc data [clause1 ... clauseN]
   Operand 0: OACC_DATA_BODY: Data construct body.
   Operand 1: OACC_DATA_CLAUSES: List of clauses.  */

DEFTREECODE (OACC_DATA, "oacc_data", tcc_statement, 2)

/* OpenACC - #pragma acc host_data [clause1 ... clauseN]
   Operand 0: OACC_HOST_DATA_BODY: Host_data construct body.
   Operand 1: OACC_HOST_DATA_CLAUSES: List of clauses.  */

DEFTREECODE (OACC_HOST_DATA, "oacc_host_data", tcc_statement, 2)

/* OpenMP - #pragma omp parallel [clause1 ... clauseN]
   Operand 0: OMP_PARALLEL_BODY: Code to be executed by all threads.
   Operand 1: OMP_PARALLEL_CLAUSES: List of clauses.  */

DEFTREECODE (OMP_PARALLEL, "omp_parallel", tcc_statement, 2)

/* OpenMP - #pragma omp task [clause1 ... clauseN]
   Operand 0: OMP_TASK_BODY: Code to be executed by all threads.
   Operand 1: OMP_TASK_CLAUSES: List of clauses.  */

DEFTREECODE (OMP_TASK, "omp_task", tcc_statement, 2)

/* OpenMP - #pragma omp for [clause1 ... clauseN]
   Operand 0: OMP_FOR_BODY: Loop body.
   Operand 1: OMP_FOR_CLAUSES: List of clauses.
   Operand 2: OMP_FOR_INIT: Initialization code of the form
                                VAR = N1.
   Operand 3: OMP_FOR_COND: Loop conditional expression of the form
                                VAR { <, >, <=, >= } N2.
   Operand 4: OMP_FOR_INCR: Loop index increment of the form
                                VAR { +=, -= } INCR.
   Operand 5: OMP_FOR_PRE_BODY: Filled by the gimplifier with things
        from INIT, COND, and INCR that are technically part of the
        OMP_FOR structured block, but are evaluated before the loop
        body begins.
   Operand 6: OMP_FOR_ORIG_DECLS: If non-NULL, list of DECLs initialized
        in OMP_FOR_INIT.  In some cases, like C++ iterators, the original
        DECL init has been lost in gimplification and now contains a
        temporary (D.nnnn).  This list contains the original DECLs in
        the source.

   VAR must be an integer or pointer variable, which is implicitly thread
   private.  N1, N2 and INCR are required to be loop invariant integer
   expressions that are evaluated without any synchronization.
   The evaluation order, frequency of evaluation and side-effects are
   unspecified by the standards.  */
DEFTREECODE (OMP_FOR, "omp_for", tcc_statement, 7)

/* OpenMP - #pragma omp simd [clause1 ... clauseN]
   Operands like for OMP_FOR.  */
DEFTREECODE (OMP_SIMD, "omp_simd", tcc_statement, 7)

/* OpenMP - #pragma omp distribute [clause1 ... clauseN]
   Operands like for OMP_FOR.  */
DEFTREECODE (OMP_DISTRIBUTE, "omp_distribute", tcc_statement, 7)

/* OpenMP - #pragma omp taskloop [clause1 ... clauseN]
   Operands like for OMP_FOR.  */
DEFTREECODE (OMP_TASKLOOP, "omp_taskloop", tcc_statement, 7)

/* OpenMP - #pragma acc loop [clause1 ... clauseN]
   Operands like for OMP_FOR.  */
DEFTREECODE (OACC_LOOP, "oacc_loop", tcc_statement, 7)

/* OpenMP - #pragma omp teams [clause1 ... clauseN]
   Operand 0: OMP_TEAMS_BODY: Teams body.
   Operand 1: OMP_TEAMS_CLAUSES: List of clauses.  */
DEFTREECODE (OMP_TEAMS, "omp_teams", tcc_statement, 2)

/* OpenMP - #pragma omp target data [clause1 ... clauseN]
   Operand 0: OMP_TARGET_DATA_BODY: Target data construct body.
   Operand 1: OMP_TARGET_DATA_CLAUSES: List of clauses.  */
DEFTREECODE (OMP_TARGET_DATA, "omp_target_data", tcc_statement, 2)

/* OpenMP - #pragma omp target [clause1 ... clauseN]
   Operand 0: OMP_TARGET_BODY: Target construct body.
   Operand 1: OMP_TARGET_CLAUSES: List of clauses.  */
DEFTREECODE (OMP_TARGET, "omp_target", tcc_statement, 2)

/* OpenMP - #pragma omp sections [clause1 ... clauseN]
   Operand 0: OMP_SECTIONS_BODY: Sections body.
   Operand 1: OMP_SECTIONS_CLAUSES: List of clauses.  */
DEFTREECODE (OMP_SECTIONS, "omp_sections", tcc_statement, 2)

/* OpenMP - #pragma omp ordered
   Operand 0: OMP_ORDERED_BODY: Master section body.
   Operand 1: OMP_ORDERED_CLAUSES: List of clauses.  */
DEFTREECODE (OMP_ORDERED, "omp_ordered", tcc_statement, 2)

/* OpenMP - #pragma omp critical [name]
   Operand 0: OMP_CRITICAL_BODY: Critical section body.
   Operand 1: OMP_CRITICAL_CLAUSES: List of clauses.
   Operand 2: OMP_CRITICAL_NAME: Identifier for critical section.  */
DEFTREECODE (OMP_CRITICAL, "omp_critical", tcc_statement, 3)

/* OpenMP - #pragma omp single
   Operand 0: OMP_SINGLE_BODY: Single section body.
   Operand 1: OMP_SINGLE_CLAUSES: List of clauses.  */
DEFTREECODE (OMP_SINGLE, "omp_single", tcc_statement, 2)

/* OpenMP - #pragma omp section
   Operand 0: OMP_SECTION_BODY: Section body.  */
DEFTREECODE (OMP_SECTION, "omp_section", tcc_statement, 1)

/* OpenMP - #pragma omp master
   Operand 0: OMP_MASTER_BODY: Master section body.  */
DEFTREECODE (OMP_MASTER, "omp_master", tcc_statement, 1)

/* OpenMP - #pragma omp taskgroup
   Operand 0: OMP_TASKGROUP_BODY: Taskgroup body.  */
DEFTREECODE (OMP_TASKGROUP, "omp_taskgroup", tcc_statement, 1)

/* OpenACC - #pragma acc cache (variable1 ... variableN)
   Operand 0: OACC_CACHE_CLAUSES: List of variables (transformed into
        OMP_CLAUSE__CACHE_ clauses).  */
DEFTREECODE (OACC_CACHE, "oacc_cache", tcc_statement, 1)

/* OpenACC - #pragma acc declare [clause1 ... clauseN]
   Operand 0: OACC_DECLARE_CLAUSES: List of clauses.  */
DEFTREECODE (OACC_DECLARE, "oacc_declare", tcc_statement, 1)

/* OpenACC - #pragma acc enter data [clause1 ... clauseN]
   Operand 0: OACC_ENTER_DATA_CLAUSES: List of clauses.  */
DEFTREECODE (OACC_ENTER_DATA, "oacc_enter_data", tcc_statement, 1)

/* OpenACC - #pragma acc exit data [clause1 ... clauseN]
   Operand 0: OACC_EXIT_DATA_CLAUSES: List of clauses.  */
DEFTREECODE (OACC_EXIT_DATA, "oacc_exit_data", tcc_statement, 1)

/* OpenACC - #pragma acc update [clause1 ... clauseN]
   Operand 0: OACC_UPDATE_CLAUSES: List of clauses.  */
DEFTREECODE (OACC_UPDATE, "oacc_update", tcc_statement, 1)

/* OpenMP - #pragma omp target update [clause1 ... clauseN]
   Operand 0: OMP_TARGET_UPDATE_CLAUSES: List of clauses.  */
DEFTREECODE (OMP_TARGET_UPDATE, "omp_target_update", tcc_statement, 1)

/* OpenMP - #pragma omp target enter data [clause1 ... clauseN]
   Operand 0: OMP_TARGET_ENTER_DATA_CLAUSES: List of clauses.  */
DEFTREECODE (OMP_TARGET_ENTER_DATA, "omp_target_enter_data", tcc_statement, 1)

/* OpenMP - #pragma omp target exit data [clause1 ... clauseN]
   Operand 0: OMP_TARGET_EXIT_DATA_CLAUSES: List of clauses.  */
DEFTREECODE (OMP_TARGET_EXIT_DATA, "omp_target_exit_data", tcc_statement, 1)

/* OMP_ATOMIC through OMP_ATOMIC_CAPTURE_NEW must be consecutive,
   or OMP_ATOMIC_SEQ_CST needs adjusting.  */

/* OpenMP - #pragma omp atomic
   Operand 0: The address at which the atomic operation is to be performed.
        This address should be stabilized with save_expr.
   Operand 1: The expression to evaluate.  When the old value of the object
        at the address is used in the expression, it should appear as if
        build_fold_indirect_ref of the address.  */
DEFTREECODE (OMP_ATOMIC, "omp_atomic", tcc_statement, 2)

/* OpenMP - #pragma omp atomic read
   Operand 0: The address at which the atomic operation is to be performed.
        This address should be stabilized with save_expr.  */
DEFTREECODE (OMP_ATOMIC_READ, "omp_atomic_read", tcc_statement, 1)

/* OpenMP - #pragma omp atomic capture
   Operand 0: The address at which the atomic operation is to be performed.
        This address should be stabilized with save_expr.
   Operand 1: The expression to evaluate.  When the old value of the object
        at the address is used in the expression, it should appear as if
        build_fold_indirect_ref of the address.
   OMP_ATOMIC_CAPTURE_OLD returns the old memory content,
   OMP_ATOMIC_CAPTURE_NEW the new value.  */
DEFTREECODE (OMP_ATOMIC_CAPTURE_OLD, "omp_atomic_capture_old", tcc_statement, 2)
DEFTREECODE (OMP_ATOMIC_CAPTURE_NEW, "omp_atomic_capture_new", tcc_statement, 2)

/* OpenMP clauses.  */
DEFTREECODE (OMP_CLAUSE, "omp_clause", tcc_exceptional, 0)

/* TRANSACTION_EXPR tree code.
   Operand 0: BODY: contains body of the transaction.  */
DEFTREECODE (TRANSACTION_EXPR, "transaction_expr", tcc_expression, 1)

/* Widening dot-product.
   The first two arguments are of type t1.
   The third argument and the result are of type t2, such that t2 is at least
   twice the size of t1. DOT_PROD_EXPR(arg1,arg2,arg3) is equivalent to:
        tmp = WIDEN_MULT_EXPR(arg1, arg2);
        arg3 = PLUS_EXPR (tmp, arg3);
   or:
        tmp = WIDEN_MULT_EXPR(arg1, arg2);
        arg3 = WIDEN_SUM_EXPR (tmp, arg3);               */
DEFTREECODE (DOT_PROD_EXPR, "dot_prod_expr", tcc_expression, 3)

/* Widening summation.
   The first argument is of type t1.
   The second argument is of type t2, such that t2 is at least twice
   the size of t1. The type of the entire expression is also t2.
   WIDEN_SUM_EXPR is equivalent to first widening (promoting)
   the first argument from type t1 to type t2, and then summing it
   with the second argument.  */
DEFTREECODE (WIDEN_SUM_EXPR, "widen_sum_expr", tcc_binary, 2)

/* Widening sad (sum of absolute differences).
   The first two arguments are of type t1 which should be integer.
   The third argument and the result are of type t2, such that t2 is at least
   twice the size of t1.  Like DOT_PROD_EXPR, SAD_EXPR (arg1,arg2,arg3) is
   equivalent to (note we don't have WIDEN_MINUS_EXPR now, but we assume its
   behavior is similar to WIDEN_SUM_EXPR):
       tmp = WIDEN_MINUS_EXPR (arg1, arg2)
       tmp2 = ABS_EXPR (tmp)
       arg3 = PLUS_EXPR (tmp2, arg3)
  or:
       tmp = WIDEN_MINUS_EXPR (arg1, arg2)
       tmp2 = ABS_EXPR (tmp)
       arg3 = WIDEN_SUM_EXPR (tmp2, arg3)
 */
DEFTREECODE (SAD_EXPR, "sad_expr", tcc_expression, 3)

/* Widening multiplication.
   The two arguments are of type t1.
   The result is of type t2, such that t2 is at least twice
   the size of t1. WIDEN_MULT_EXPR is equivalent to first widening (promoting)
   the arguments from type t1 to type t2, and then multiplying them.  */
DEFTREECODE (WIDEN_MULT_EXPR, "widen_mult_expr", tcc_binary, 2)

/* Widening multiply-accumulate.
   The first two arguments are of type t1.
   The third argument and the result are of type t2, such as t2 is at least
   twice the size of t1.  t1 and t2 must be integral or fixed-point types.
   The expression is equivalent to a WIDEN_MULT_EXPR operation
   of the first two operands followed by an add or subtract of the third
   operand.  */
DEFTREECODE (WIDEN_MULT_PLUS_EXPR, "widen_mult_plus_expr", tcc_expression, 3)
/* This is like the above, except in the final expression the multiply result
   is subtracted from t3.  */
DEFTREECODE (WIDEN_MULT_MINUS_EXPR, "widen_mult_minus_expr", tcc_expression, 3)

/* Widening shift left.
   The first operand is of type t1.
   The second operand is the number of bits to shift by; it need not be the
   same type as the first operand and result.
   Note that the result is undefined if the second operand is larger
   than or equal to the first operand's type size.
   The type of the entire expression is t2, such that t2 is at least twice
   the size of t1.
   WIDEN_LSHIFT_EXPR is equivalent to first widening (promoting)
   the first argument from type t1 to type t2, and then shifting it
   by the second argument.  */
DEFTREECODE (WIDEN_LSHIFT_EXPR, "widen_lshift_expr", tcc_binary, 2)

/* Fused multiply-add.
   All operands and the result are of the same type.  No intermediate
   rounding is performed after multiplying operand one with operand two
   before adding operand three.  */
DEFTREECODE (FMA_EXPR, "fma_expr", tcc_expression, 3)

/* Widening vector multiplication.
   The two operands are vectors with N elements of size S. Multiplying the
   elements of the two vectors will result in N products of size 2*S.
   VEC_WIDEN_MULT_HI_EXPR computes the N/2 high products.
   VEC_WIDEN_MULT_LO_EXPR computes the N/2 low products.  */
DEFTREECODE (VEC_WIDEN_MULT_HI_EXPR, "widen_mult_hi_expr", tcc_binary, 2)
DEFTREECODE (VEC_WIDEN_MULT_LO_EXPR, "widen_mult_lo_expr", tcc_binary, 2)

/* Similarly, but return the even or odd N/2 products.  */
DEFTREECODE (VEC_WIDEN_MULT_EVEN_EXPR, "widen_mult_even_expr", tcc_binary, 2)
DEFTREECODE (VEC_WIDEN_MULT_ODD_EXPR, "widen_mult_odd_expr", tcc_binary, 2)

/* Unpack (extract and promote/widen) the high/low elements of the input
   vector into the output vector.  The input vector has twice as many
   elements as the output vector, that are half the size of the elements
   of the output vector.  This is used to support type promotion. */
DEFTREECODE (VEC_UNPACK_HI_EXPR, "vec_unpack_hi_expr", tcc_unary, 1)
DEFTREECODE (VEC_UNPACK_LO_EXPR, "vec_unpack_lo_expr", tcc_unary, 1)

/* Unpack (extract) the high/low elements of the input vector, convert
   fixed point values to floating point and widen elements into the
   output vector.  The input vector has twice as many elements as the output
   vector, that are half the size of the elements of the output vector.  */
DEFTREECODE (VEC_UNPACK_FLOAT_HI_EXPR, "vec_unpack_float_hi_expr", tcc_unary, 1)
DEFTREECODE (VEC_UNPACK_FLOAT_LO_EXPR, "vec_unpack_float_lo_expr", tcc_unary, 1)

/* Pack (demote/narrow and merge) the elements of the two input vectors
   into the output vector using truncation/saturation.
   The elements of the input vectors are twice the size of the elements of the
   output vector.  This is used to support type demotion.  */
DEFTREECODE (VEC_PACK_TRUNC_EXPR, "vec_pack_trunc_expr", tcc_binary, 2)
DEFTREECODE (VEC_PACK_SAT_EXPR, "vec_pack_sat_expr", tcc_binary, 2)

/* Convert floating point values of the two input vectors to integer
   and pack (narrow and merge) the elements into the output vector. The
   elements of the input vector are twice the size of the elements of
   the output vector.  */
DEFTREECODE (VEC_PACK_FIX_TRUNC_EXPR, "vec_pack_fix_trunc_expr", tcc_binary, 2)

/* Widening vector shift left in bits.
   Operand 0 is a vector to be shifted with N elements of size S.
   Operand 1 is an integer shift amount in bits.
   The result of the operation is N elements of size 2*S.
   VEC_WIDEN_LSHIFT_HI_EXPR computes the N/2 high results.
   VEC_WIDEN_LSHIFT_LO_EXPR computes the N/2 low results.
 */
DEFTREECODE (VEC_WIDEN_LSHIFT_HI_EXPR, "widen_lshift_hi_expr", tcc_binary, 2)
DEFTREECODE (VEC_WIDEN_LSHIFT_LO_EXPR, "widen_lshift_lo_expr", tcc_binary, 2)

/* PREDICT_EXPR.  Specify hint for branch prediction.  The
   PREDICT_EXPR_PREDICTOR specify predictor and PREDICT_EXPR_OUTCOME the
   outcome (0 for not taken and 1 for taken).  Once the profile is guessed
   all conditional branches leading to execution paths executing the
   PREDICT_EXPR will get predicted by the specified predictor.  */
DEFTREECODE (PREDICT_EXPR, "predict_expr", tcc_expression, 1)

/* OPTIMIZATION_NODE.  Node to store the optimization options.  */
DEFTREECODE (OPTIMIZATION_NODE, "optimization_node", tcc_exceptional, 0)

/* TARGET_OPTION_NODE.  Node to store the target specific options.  */
DEFTREECODE (TARGET_OPTION_NODE, "target_option_node", tcc_exceptional, 0)

/* ANNOTATE_EXPR.
   Operand 0 is the expression to be annotated.
   Operand 1 is the annotation kind.
   Operand 2 is additional data.  */
DEFTREECODE (ANNOTATE_EXPR, "annotate_expr", tcc_expression, 3)

/*
Local variables:
mode:c
End:
*/