tree.def

早期freebsd实现

/* This file contains the definitions and documentation for the
   tree codes used in the GNU C compiler.
   Copyright (C) 1987, 1988 Free Software Foundation, Inc.

This file is part of GNU CC.

GNU CC 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 2, or (at your option)
any later version.

GNU CC 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 GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */

 
/* The third argument can be:
   "x" for an exceptional code (fits no category).
   "t" for a type object code.
   "b" for a lexical block.
   "c" for codes for constants.
   "d" for codes for declarations (also serving as variable refs).
   "r" for codes for references to storage.
   "<" for codes for comparison expressions.
   "1" for codes for unary arithmetic expressions.
   "2" for codes for binary arithmetic expressions.
   "s" for codes for expressions with inherent side effects.
   "e" for codes for other kinds of expressions.  */

/* For `r', `e', `<', `1', `2', `s' and `x' nodes,
   the 4th element is the number of argument slots to allocate.
   This determines the size of the tree node object.  */

/* 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", "x", 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", "x", -1)

/* Used to hold information to identify an operator (or combination
   of two operators) considered as a `noun' rather than a `verb'.
   The first operand is encoded in the TREE_TYPE field.  */
DEFTREECODE (OP_IDENTIFIER, "op_identifier", "x", 2)

/* 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", "x", 2)

/* These nodes contain an array of tree nodes.  */
DEFTREECODE (TREE_VEC, "tree_vec", "x", 2)

/* 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_TYPE_TAGS points to a chain of types which have their own names.
   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 non-zero if the block represents an abstract
   instance of a block (i.e. one which is nested within an abstract
   instance of a inline function. */
DEFTREECODE (BLOCK, "block", "b", 0)

/* 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_NONCOPIED_PARTS field is a list specifying which parts
     of an object of this type should *not* be copied by assignment.
     The TREE_PURPOSE of each element is the offset of the part
     and the TREE_VALUE is the size in bits of the part.
   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 or 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.  */
/* TREE_CHAIN is used for ENUMERAL_TYPE, RECORD_TYPE and UNION_TYPE
   nodes used as forward-references to names; see below.  */

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

/* Integer types in all languages, including char in C.  */
/* 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).
   Otherwise, the TREE_TYPE is zero.  */
DEFTREECODE (INTEGER_TYPE, "integer_type", "t", 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", "t", 0)

/* Complex number types.  The TREE_TYPE field is the data type
   of the real and imaginary parts.  */
DEFTREECODE (COMPLEX_TYPE, "complex_type", "t", 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 TREE_VALUES is a list in which each elements' 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 and UNION_TYPE forward refs are treated similarly.  */
DEFTREECODE (ENUMERAL_TYPE, "enumeral_type", "t", 0)

/* Pascal's boolean type (true or false are the only values);
   no special fields needed.  */
DEFTREECODE (BOOLEAN_TYPE, "boolean_type", "t", 0)

/* CHAR in Pascal; not used in C.
   No special fields needed.  */
DEFTREECODE (CHAR_TYPE, "char_type", "t", 0)

/* 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", "t", 0)

/* 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", "t", 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", "t", 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", "t", 0)

/* Used for Pascal; details not determined right now.  */
DEFTREECODE (FILE_TYPE, "file_type", "t", 0)

/* 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.
   TYPE_SEP		  Expression for units from one elt to the next.
   TYPE_SEP_UNIT	  Number of bits in a unit for previous.
 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.  */
/* Array types in C or Pascal */
DEFTREECODE (ARRAY_TYPE, "array_type", "t", 0)

/* Types of sets for Pascal.  Special fields are the same as
   in an array type.  The target type is always a boolean type.  */
DEFTREECODE (SET_TYPE, "set_type", "t", 0)

/* Not known whether Pascal really needs this
   or what it should contain.  */
DEFTREECODE (STRING_TYPE, "string_type", "t", 0)

/* Struct in C, or record in Pascal.  */
/* Special fields:
   TYPE_FIELDS  chain of FIELD_DECLs for the fields of the struct.
   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", "t", 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", "t", 0)	/* C union type */

/* 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.
   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", "t", 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", "t", 0)

/* Expressions */

/* First, the constants.  */

/* Contents are in TREE_INT_CST_LOW and TREE_INT_CST_HIGH fields,
   32 bits each, giving us a 64 bit constant capability.
   Note: constants of type char in Pascal are INTEGER_CST,
   and so are pointer constants such as nil in Pascal or NULL in C.
   `(int *) 1' in C also results in an INTEGER_CST.  */
DEFTREECODE (INTEGER_CST, "integer_cst", "c", 2)

/* Contents are in TREE_REAL_CST field.  Also there is TREE_CST_RTL.  */
DEFTREECODE (REAL_CST, "real_cst", "c", 3)

/* Contents are in TREE_REALPART and TREE_IMAGPART fields,
   whose contents are other constant nodes.
   Also there is TREE_CST_RTL.  */
DEFTREECODE (COMPLEX_CST, "complex_cst", "c", 3)

/* Contents are TREE_STRING_LENGTH and TREE_STRING_POINTER fields.
   Also there is TREE_CST_RTL.  */
DEFTREECODE (STRING_CST, "string_cst", "c", 3)

/* 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 or 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 the FUNCTION_DECL for the containing function, or else
    yields NULL_TREE 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_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,
    or it is 0 for a function that returns no value.
    (C functions returning void have zero here.)
   DECL_RESULT_TYPE holds the type in which the result is actually
    returned.  This is usually the same as the type of DECL_RESULT,
    but (1) it may be a wider integer type and
    (2) it remains valid, for the sake of inlining, even after the
    function's compilation is done.
   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 non-zero 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", "d", 0)
DEFTREECODE (LABEL_DECL, "label_decl", "d", 0)
DEFTREECODE (CONST_DECL, "const_decl", "d", 0)
DEFTREECODE (TYPE_DECL, "type_decl", "d", 0)
DEFTREECODE (VAR_DECL, "var_decl", "d", 0)
DEFTREECODE (PARM_DECL, "parm_decl", "d", 0)
DEFTREECODE (RESULT_DECL, "result_decl", "d", 0)