tree.def

这是完整的gcc源代码

/* 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 1, 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).
   "s" for a statement code.
   "t" for a type object code.

   "c" for codes for constants.
   "d" for codes for declarations (also serving as variable refs).
   "r" for codes for references to storage.
   "e" for codes for other kinds of expressions.  */

/* For `r', `e' 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", 7)

/* 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)

/* 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 some units.
   The TYPE_SIZE_UNIT component is the number of bits in a unit.
   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 TREE_CHAIN of a ..._TYPE node is normally used to put
   every type onto permanent_type_chain or temporary_type_chain (see tree.c).
   One exception is 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)

/* All statement types have fields STMT_SOURCE_FILE and STMT_SOURCE_LINE.  */
/* Consecutive statements within a compound statement are chained together
   through the TREE_CHAIN field.  */

/* A label definition, encapsulated as a statement.
   STMT_BODY is the LABEL_DECL node for the label that appears here.  */
DEFTREECODE (LABEL_STMT, "label_stmt", "s", 1)

/* GOTO, in any language.  STMT_BODY is a LABEL_DECL node.  */
DEFTREECODE (GOTO_STMT, "goto_stmt", "s", 1)

/* RETURN, in any language.
   Evaluates the expression STMT_BODY, then returns from the current function.
   Presumably STMT_BODY is an assignment that stores into the
   RESULT_DECL that hold the value to be returned.
   STMT_BODY may be zero.  */
DEFTREECODE (RETURN_STMT, "return_stmt", "s", 1)

/* Statement that evaluates an expression.  STMT_BODY is the expression.  */
DEFTREECODE (EXPR_STMT, "expr_stmt", "s", 1)

/* Pascal WITH statement.
   Contains a chain of variables (..._DECL nodes) in the STMT_VARS
   and a chain of statements (the STMT_BODY).
   STMT_SUPERCONTEXT points to the containing declaration scope.  */
DEFTREECODE (WITH_STMT, "with_stmt", "s", 5)

/* Declare variables whose scope is less than a function.
   This is used for C brace-pairs that contain declarations.
   Contains a chain of variables (..._DECL nodes) in the STMT_VARS
   and a chain of statements (the STMT_BODY).
   STMT_SUPERCONTEXT points to the containing declaration scope.
   STMT_BIND_SIZE is an expression for the size of local storage here.
   STMT_TYPE_TAGS is a list (chain of TREE_LIST nodes)
    pairing struct, union and enum tag names with the types they mean,
    for tags defined in this context.

   A LET_STMT can be used as an expression.  Its STMT_BODY is expanded
   in its stead.  Its TREE_USED is set if it is expanded.

   A LET_STMT whose TREE_USED is not set is ignored when symbols
   are output.  If the LET_STMT is passed to expand_expr but it
   should not be ignored, set its TREE_USED by hand.  */
DEFTREECODE (LET_STMT, "let_stmt", "s", 6)

/* if-then-else statements in C and other languages.
   STMT_COND is the condition (an expression).
   STMT_THEN is the then-branch (a statement or chain of statements).
   STMT_ELSE is the else-branch (a statement or chain of statements).  */
DEFTREECODE (IF_STMT, "if_stmt", "s", 3)

/* if-else-exit; used in building parts of iterations.
   STMT_BODY is the condition (an expression).
   Exit if the iteration if the condition is FALSE.  */
DEFTREECODE (EXIT_STMT, "exit_stmt", "s", 1)

/* STMT_CASE_INDEX is an expression for the value to dispatch on.
   STMT_CASE_LIST is a list (a chain of TREE_LIST nodes)
    of the branches of the dispatch.
   Each such TREE_LIST node has the case it is for (a constant expression)
   as the TREE_PURPOSE
   and the label to go to (a LABEL_DECL) as the TREE_VALUE. 

   Normally, the labels reside inside a COMPOUND_STMT
   which contains ths CASE_STMT as its first statement.  */
DEFTREECODE (CASE_STMT, "case_stmt", "s", 3)

/* STMT_BODY contains a chain of statements to be executed repeatedly.  */
DEFTREECODE (LOOP_STMT, "loop_stmt", "s", 1)

/* Contains as its STMT_BODY a chain of substatements.  */
DEFTREECODE (COMPOUND_STMT, "compound_stmt", "s", 1)

/* Contains as its STMT_BODY a string of assembly code.  */
DEFTREECODE (ASM_STMT, "asm_stmt", "s", 1)

/* 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 belongs to;
    for other kinds of decl nodes, this is a LET_STMT node or the ROOT_NODE.
   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, DECL_SIZE_UNIT
    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.