gcc/tree.def

   1 /* This file contains the definitions and documentation for the
   2    tree codes used in the GNU C compiler.
   3    Copyright (C) 1987, 1988, 1993, 1995, 1997, 1998, 2000, 2001 Free Software Foundation, Inc.
   4
   5 This file is part of GNU CC.
   6
   7 GNU CC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2, or (at your option)
  10 any later version.
  11
  12 GNU CC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU CC; see the file COPYING.  If not, write to
  19 the Free Software Foundation, 59 Temple Place - Suite 330,
  20 Boston, MA 02111-1307, USA.  */
  21
  22
  23 /* The third argument can be:
  24    'x' for an exceptional code (fits no category).
  25    't' for a type object code.
  26    'b' for a lexical block.
  27    'c' for codes for constants.
  28    'd' for codes for declarations (also serving as variable refs).
  29    'r' for codes for references to storage.
  30    '<' for codes for comparison expressions.
  31    '1' for codes for unary arithmetic expressions.
  32    '2' for codes for binary arithmetic expressions.
  33    's' for codes for expressions with inherent side effects.
  34    'e' for codes for other kinds of expressions.  */
  35
  36 /* For `r', `e', `<', `1', `2', `s' and `x' nodes,
  37    the 4th element is the number of argument slots to allocate.
  38    This determines the size of the tree node object.  */
  39
  40 /* Any erroneous construct is parsed into a node of this type.
  41    This type of node is accepted without complaint in all contexts
  42    by later parsing activities, to avoid multiple error messages
  43    for one error.
  44    No fields in these nodes are used except the TREE_CODE.  */
  45 DEFTREECODE (ERROR_MARK, "error_mark", 'x', 0)
  46
  47 /* Used to represent a name (such as, in the DECL_NAME of a decl node).
  48    Internally it looks like a STRING_CST node.
  49    There is only one IDENTIFIER_NODE ever made for any particular name.
  50    Use `get_identifier' to get it (or create it, the first time).  */
  51 DEFTREECODE (IDENTIFIER_NODE, "identifier_node", 'x', -1)
  52
  53 /* Used to hold information to identify an operator (or combination
  54    of two operators) considered as a `noun' rather than a `verb'.
  55    The first operand is encoded in the TREE_TYPE field.  */
  56 DEFTREECODE (OP_IDENTIFIER, "op_identifier", 'x', 2)
  57
  58 /* Has the TREE_VALUE and TREE_PURPOSE fields.  */
  59 /* These nodes are made into lists by chaining through the
  60    TREE_CHAIN field.  The elements of the list live in the
  61    TREE_VALUE fields, while TREE_PURPOSE fields are occasionally
  62    used as well to get the effect of Lisp association lists.  */
  63 DEFTREECODE (TREE_LIST, "tree_list", 'x', 2)
  64
  65 /* These nodes contain an array of tree nodes.  */
  66 DEFTREECODE (TREE_VEC, "tree_vec", 'x', 2)
  67
  68 /* A symbol binding block.  These are arranged in a tree,
  69    where the BLOCK_SUBBLOCKS field contains a chain of subblocks
  70    chained through the BLOCK_CHAIN field.
  71    BLOCK_SUPERCONTEXT points to the parent block.
  72      For a block which represents the outermost scope of a function, it
  73      points to the FUNCTION_DECL node.
  74    BLOCK_VARS points to a chain of decl nodes.
  75    BLOCK_TYPE_TAGS points to a chain of types which have their own names.
  76    BLOCK_CHAIN points to the next BLOCK at the same level.
  77    BLOCK_ABSTRACT_ORIGIN points to the original (abstract) tree node which
  78    this block is an instance of, or else is NULL to indicate that this
  79    block is not an instance of anything else.  When non-NULL, the value
  80    could either point to another BLOCK node or it could point to a
  81    FUNCTION_DECL node (e.g. in the case of a block representing the
  82    outermost scope of a particular inlining of a function).
  83    BLOCK_ABSTRACT is non-zero if the block represents an abstract
  84    instance of a block (i.e. one which is nested within an abstract
  85    instance of an inline function).
  86    TREE_ASM_WRITTEN is non-zero if the block was actually referenced
  87    in the generated assembly.  */
  88 DEFTREECODE (BLOCK, "block", 'b', 0)
  89 \f
  90 /* Each data type is represented by a tree node whose code is one of
  91    the following:  */
  92 /* Each node that represents a data type has a component TYPE_SIZE
  93    containing a tree that is an expression for the size in bits.
  94    The TYPE_MODE contains the machine mode for values of this type.
  95    The TYPE_POINTER_TO field contains a type for a pointer to this type,
  96      or zero if no such has been created yet.
  97    The TYPE_NEXT_VARIANT field is used to chain together types
  98      that are variants made by type modifiers such as "const" and "volatile".
  99    The TYPE_MAIN_VARIANT field, in any member of such a chain,
 100      points to the start of the chain.
 101    The TYPE_NONCOPIED_PARTS field is a list specifying which parts
 102      of an object of this type should *not* be copied by assignment.
 103      The TREE_VALUE of each is a FIELD_DECL that should not be
 104      copied.  The TREE_PURPOSE is an initial value for that field when
 105      an object of this type is initialized via an INIT_EXPR.  It may
 106      be NULL if no special value is required.  Even the things in this
 107      list are copied if the right-hand side of an assignment is known
 108      to be a complete object (rather than being, perhaps, a subobject
 109      of some other object.)  The determination of what constitutes a
 110      complete object is done by fixed_type_p.
 111    The TYPE_NAME field contains info on the name used in the program
 112      for this type (for GDB symbol table output).  It is either a
 113      TYPE_DECL node, for types that are typedefs, or an IDENTIFIER_NODE
 114      in the case of structs, unions or enums that are known with a tag,
 115      or zero for types that have no special name.
 116    The TYPE_CONTEXT for any sort of type which could have a name or
 117     which could have named members (e.g. tagged types in C/C++) will
 118     point to the node which represents the scope of the given type, or
 119     will be NULL_TREE if the type has "file scope".  For most types, this
 120     will point to a BLOCK node or a FUNCTION_DECL node, but it could also
 121     point to a FUNCTION_TYPE node (for types whose scope is limited to the
 122     formal parameter list of some function type specification) or it
 123     could point to a RECORD_TYPE, UNION_TYPE or QUAL_UNION_TYPE node
 124     (for C++ "member" types).
 125     For non-tagged-types, TYPE_CONTEXT need not be set to anything in
 126     particular, since any type which is of some type category  (e.g.
 127     an array type or a function type) which cannot either have a name
 128     itself or have named members doesn't really have a "scope" per se.
 129   The TREE_CHAIN field is used as a forward-references to names for
 130     ENUMERAL_TYPE, RECORD_TYPE, UNION_TYPE, and QUAL_UNION_TYPE nodes;
 131     see below.  */
 132
 133 DEFTREECODE (VOID_TYPE, "void_type", 't', 0)    /* The void type in C */
 134
 135 /* Integer types in all languages, including char in C.
 136    Also used for sub-ranges of other discrete types.
 137    Has components TYPE_MIN_VALUE, TYPE_MAX_VALUE (expressions, inclusive)
 138    and TYPE_PRECISION (number of bits used by this type).
 139    In the case of a subrange type in Pascal, the TREE_TYPE
 140    of this will point at the supertype (another INTEGER_TYPE,
 141    or an ENUMERAL_TYPE, CHAR_TYPE, or BOOLEAN_TYPE).
 142    Otherwise, the TREE_TYPE is zero.  */
 143 DEFTREECODE (INTEGER_TYPE, "integer_type", 't', 0)
 144
 145 /* C's float and double.  Different floating types are distinguished
 146    by machine mode and by the TYPE_SIZE and the TYPE_PRECISION.  */
 147 DEFTREECODE (REAL_TYPE, "real_type", 't', 0)
 148
 149 /* Complex number types.  The TREE_TYPE field is the data type
 150    of the real and imaginary parts.  */
 151 DEFTREECODE (COMPLEX_TYPE, "complex_type", 't', 0)
 152
 153 /* Vector types.  The TREE_TYPE field is the data type of the vector
 154    elements.  */
 155 DEFTREECODE (VECTOR_TYPE, "vector_type", 't', 0)
 156
 157 /* C enums.  The type node looks just like an INTEGER_TYPE node.
 158    The symbols for the values of the enum type are defined by
 159    CONST_DECL nodes, but the type does not point to them;
 160    however, the TYPE_VALUES is a list in which each element's TREE_PURPOSE
 161    is a name and the TREE_VALUE is the value (an INTEGER_CST node).  */
 162 /* A forward reference `enum foo' when no enum named foo is defined yet
 163    has zero (a null pointer) in its TYPE_SIZE.  The tag name is in
 164    the TYPE_NAME field.  If the type is later defined, the normal
 165    fields are filled in.
 166    RECORD_TYPE, UNION_TYPE, and QUAL_UNION_TYPE forward refs are
 167    treated similarly.  */
 168 DEFTREECODE (ENUMERAL_TYPE, "enumeral_type", 't', 0)
 169
 170 /* Pascal's boolean type (true or false are the only values);
 171    no special fields needed.  */
 172 DEFTREECODE (BOOLEAN_TYPE, "boolean_type", 't', 0)
 173
 174 /* CHAR in Pascal; not used in C.
 175    No special fields needed.  */
 176 DEFTREECODE (CHAR_TYPE, "char_type", 't', 0)
 177
 178 /* All pointer-to-x types have code POINTER_TYPE.
 179    The TREE_TYPE points to the node for the type pointed to.  */
 180 DEFTREECODE (POINTER_TYPE, "pointer_type", 't', 0)
 181
 182 /* An offset is a pointer relative to an object.
 183    The TREE_TYPE field is the type of the object at the offset.
 184    The TYPE_OFFSET_BASETYPE points to the node for the type of object
 185    that the offset is relative to.  */
 186 DEFTREECODE (OFFSET_TYPE, "offset_type", 't', 0)
 187
 188 /* A reference is like a pointer except that it is coerced
 189    automatically to the value it points to.  Used in C++.  */
 190 DEFTREECODE (REFERENCE_TYPE, "reference_type", 't', 0)
 191
 192 /* METHOD_TYPE is the type of a function which takes an extra first
 193    argument for "self", which is not present in the declared argument list.
 194    The TREE_TYPE is the return type of the method.  The TYPE_METHOD_BASETYPE
 195    is the type of "self".  TYPE_ARG_TYPES is the real argument list, which
 196    includes the hidden argument for "self".  */
 197 DEFTREECODE (METHOD_TYPE, "method_type", 't', 0)
 198
 199 /* Used for Pascal; details not determined right now.  */
 200 DEFTREECODE (FILE_TYPE, "file_type", 't', 0)
 201
 202 /* Types of arrays.  Special fields:
 203    TREE_TYPE              Type of an array element.
 204    TYPE_DOMAIN            Type to index by.
 205                             Its range of values specifies the array length.
 206    TYPE_SEP               Expression for units from one elt to the next.
 207    TYPE_SEP_UNIT          Number of bits in a unit for previous.
 208  The field TYPE_POINTER_TO (TREE_TYPE (array_type)) is always nonzero
 209  and holds the type to coerce a value of that array type to in C.
 210  TYPE_STRING_FLAG indicates a string (in contrast to an array of chars)
 211  in languages (such as Chill) that make a distinction. */
 212 /* Array types in C or Pascal */
 213 DEFTREECODE (ARRAY_TYPE, "array_type", 't', 0)
 214
 215 /* Types of sets for Pascal.  Special fields are the same as
 216    in an array type.  The target type is always a boolean type.
 217    Used for both bitstrings and powersets in Chill;
 218    TYPE_STRING_FLAG indicates a bitstring. */
 219 DEFTREECODE (SET_TYPE, "set_type", 't', 0)
 220
 221 /* Struct in C, or record in Pascal.  */
 222 /* Special fields:
 223    TYPE_FIELDS  chain of FIELD_DECLs for the fields of the struct,
 224      and VAR_DECLs, TYPE_DECLs and CONST_DECLs for record-scope variables,
 225      types and enumerators.
 226    A few may need to be added for Pascal.  */
 227 /* See the comment above, before ENUMERAL_TYPE, for how
 228    forward references to struct tags are handled in C.  */
 229 DEFTREECODE (RECORD_TYPE, "record_type", 't', 0)
 230
 231 /* Union in C.  Like a struct, except that the offsets of the fields
 232    will all be zero.  */
 233 /* See the comment above, before ENUMERAL_TYPE, for how
 234    forward references to union tags are handled in C.  */
 235 DEFTREECODE (UNION_TYPE, "union_type", 't', 0)  /* C union type */
 236
 237 /* Similar to UNION_TYPE, except that the expressions in DECL_QUALIFIER
 238    in each FIELD_DECL determine what the union contains.  The first
 239    field whose DECL_QUALIFIER expression is true is deemed to occupy
 240    the union.  */
 241 DEFTREECODE (QUAL_UNION_TYPE, "qual_union_type", 't', 0)
 242
 243 /* Type of functions.  Special fields:
 244    TREE_TYPE                type of value returned.
 245    TYPE_ARG_TYPES      list of types of arguments expected.
 246         this list is made of TREE_LIST nodes.
 247    Types of "Procedures" in languages where they are different from functions
 248    have code FUNCTION_TYPE also, but then TREE_TYPE is zero or void type.  */
 249 DEFTREECODE (FUNCTION_TYPE, "function_type", 't', 0)
 250
 251 /* This is a language-specific kind of type.
 252    Its meaning is defined by the language front end.
 253    layout_type does not know how to lay this out,
 254    so the front-end must do so manually.  */
 255 DEFTREECODE (LANG_TYPE, "lang_type", 't', 0)
 256 \f
 257 /* Expressions */
 258
 259 /* First, the constants.  */
 260
 261 /* Contents are in TREE_INT_CST_LOW and TREE_INT_CST_HIGH fields,
 262    32 bits each, giving us a 64 bit constant capability.
 263    Note: constants of type char in Pascal are INTEGER_CST,
 264    and so are pointer constants such as nil in Pascal or NULL in C.
 265    `(int *) 1' in C also results in an INTEGER_CST.  */
 266 DEFTREECODE (INTEGER_CST, "integer_cst", 'c', 2)
 267
 268 /* Contents are in TREE_REAL_CST field.  Also there is TREE_CST_RTL.  */
 269 DEFTREECODE (REAL_CST, "real_cst", 'c', 3)
 270
 271 /* Contents are in TREE_REALPART and TREE_IMAGPART fields,
 272    whose contents are other constant nodes.
 273    Also there is TREE_CST_RTL.  */
 274 DEFTREECODE (COMPLEX_CST, "complex_cst", 'c', 3)
 275
 276 /* Contents are TREE_STRING_LENGTH and TREE_STRING_POINTER fields.
 277    Also there is TREE_CST_RTL.  */
 278 DEFTREECODE (STRING_CST, "string_cst", 'c', 3)
 279
 280 /* Declarations.  All references to names are represented as ..._DECL nodes.
 281    The decls in one binding context are chained through the TREE_CHAIN field.
 282    Each DECL has a DECL_NAME field which contains an IDENTIFIER_NODE.
 283     (Some decls, most often labels, may have zero as the DECL_NAME).
 284    DECL_CONTEXT points to the node representing the context in which
 285     this declaration has its scope.  For FIELD_DECLs, this is the
 286     RECORD_TYPE, UNION_TYPE, or QUAL_UNION_TYPE node that the field
 287     is a member of.  For VAR_DECL, PARM_DECL, FUNCTION_DECL, LABEL_DECL,
 288     and CONST_DECL nodes, this points to either the FUNCTION_DECL for the
 289     containing function, the RECORD_TYPE or UNION_TYPE for the containing
 290     type, or NULL_TREE if the given decl has "file scope".
 291    DECL_ABSTRACT_ORIGIN, if non-NULL, points to the original (abstract)
 292     ..._DECL node of which this decl is an (inlined or template expanded)
 293     instance.
 294    The TREE_TYPE field holds the data type of the object, when relevant.
 295     LABEL_DECLs have no data type.  For TYPE_DECL, the TREE_TYPE field
 296     contents are the type whose name is being declared.
 297    The DECL_ALIGN, DECL_SIZE,
 298     and DECL_MODE fields exist in decl nodes just as in type nodes.
 299     They are unused in LABEL_DECL, TYPE_DECL and CONST_DECL nodes.
 300
 301    DECL_OFFSET holds an integer number of bits offset for the location.
 302    DECL_VOFFSET holds an expression for a variable offset; it is
 303    to be multiplied by DECL_VOFFSET_UNIT (an integer).
 304    These fields are relevant only in FIELD_DECLs and PARM_DECLs.
 305
 306    DECL_INITIAL holds the value to initialize a variable to,
 307    or the value of a constant.  For a function, it holds the body
 308    (a node of type BLOCK representing the function's binding contour
 309    and whose body contains the function's statements.)  For a LABEL_DECL
 310    in C, it is a flag, nonzero if the label's definition has been seen.
 311
 312    PARM_DECLs use a special field:
 313    DECL_ARG_TYPE is the type in which the argument is actually
 314     passed, which may be different from its type within the function.
 315
 316    FUNCTION_DECLs use four special fields:
 317    DECL_ARGUMENTS holds a chain of PARM_DECL nodes for the arguments.
 318    DECL_RESULT holds a RESULT_DECL node for the value of a function,
 319     or it is 0 for a function that returns no value.
 320     (C functions returning void have zero here.)
 321     The TREE_TYPE field is the type in which the result is actually
 322     returned.  This is usually the same as the return type of the
 323     FUNCTION_DECL, but it may be a wider integer type because of
 324     promotion.
 325    DECL_FUNCTION_CODE is a code number that is nonzero for
 326     built-in functions.  Its value is an enum built_in_function
 327     that says which built-in function it is.
 328
 329    DECL_SOURCE_FILE holds a filename string and DECL_SOURCE_LINE
 330    holds a line number.  In some cases these can be the location of
 331    a reference, if no definition has been seen.
 332
 333    DECL_ABSTRACT is non-zero if the decl represents an abstract instance
 334    of a decl (i.e. one which is nested within an abstract instance of a
 335    inline function.  */
 336
 337 DEFTREECODE (FUNCTION_DECL, "function_decl", 'd', 0)
 338 DEFTREECODE (LABEL_DECL, "label_decl", 'd', 0)
 339 DEFTREECODE (CONST_DECL, "const_decl", 'd', 0)
 340 DEFTREECODE (TYPE_DECL, "type_decl", 'd', 0)
 341 DEFTREECODE (VAR_DECL, "var_decl", 'd', 0)
 342 DEFTREECODE (PARM_DECL, "parm_decl", 'd', 0)
 343 DEFTREECODE (RESULT_DECL, "result_decl", 'd', 0)
 344 DEFTREECODE (FIELD_DECL, "field_decl", 'd', 0)
 345
 346 /* A namespace declaration.  Namespaces appear in DECL_CONTEXT of other
 347    _DECLs, providing a hierarchy of names.  */
 348 DEFTREECODE (NAMESPACE_DECL, "namespace_decl", 'd', 0)
 349 \f
 350 /* References to storage.  */
 351
 352 /* Value is structure or union component.
 353    Operand 0 is the structure or union (an expression);
 354    operand 1 is the field (a node of type FIELD_DECL).  */
 355 DEFTREECODE (COMPONENT_REF, "component_ref", 'r', 2)
 356
 357 /* Reference to a group of bits within an object.  Similar to COMPONENT_REF
 358    except the position is given explicitly rather than via a FIELD_DECL.
 359    Operand 0 is the structure or union expression;
 360    operand 1 is a tree giving the number of bits being referenced;
 361    operand 2 is a tree giving the position of the first referenced bit.
 362    The field can be either a signed or unsigned field;
 363    TREE_UNSIGNED says which.  */
 364 DEFTREECODE (BIT_FIELD_REF, "bit_field_ref", 'r', 3)
 365
 366 /* C unary `*' or Pascal `^'.  One operand, an expression for a pointer.  */
 367 DEFTREECODE (INDIRECT_REF, "indirect_ref", 'r', 1)
 368
 369 /* Pascal `^` on a file.  One operand, an expression for the file.  */
 370 DEFTREECODE (BUFFER_REF, "buffer_ref", 'r', 1)
 371
 372 /* Array indexing in languages other than C.
 373    Operand 0 is the array; operand 1 is a (single) array index. */
 374 DEFTREECODE (ARRAY_REF, "array_ref", 'r', 2)
 375
 376 /* Constructor: return an aggregate value made from specified components.
 377    In C, this is used only for structure and array initializers.
 378    Also used for SET_TYPE in Chill (and potentially Pascal).
 379    The first "operand" is really a pointer to the RTL,
 380    for constant constructors only.
 381    The second operand is a list of component values
 382    made out of a chain of TREE_LIST nodes.
 383
 384    For ARRAY_TYPE:
 385    The TREE_PURPOSE of each node is the corresponding index.
 386    If the TREE_PURPOSE is a RANGE_EXPR, it is a short-hand for many nodes,
 387    one for each index in the range.  (If the corresponding TREE_VALUE
 388    has side-effects, they are evaluated once for each element.  Wrap the
 389    value in a SAVE_EXPR if you want to evaluate side effects only once.)
 390
 391    For RECORD_TYPE, UNION_TYPE, or QUAL_UNION_TYPE:
 392    The TREE_PURPOSE of each node is a FIELD_DECL.
 393
 394    For SET_TYPE:
 395    The TREE_VALUE specifies a value (index) in the set that is true.
 396    If TREE_PURPOSE is non-NULL, it specifies the lower limit of a
 397    range of true values.  Elements not listed are false (not in the set).  */
 398 DEFTREECODE (CONSTRUCTOR, "constructor", 'e', 2)
 399
 400 /* The expression types are mostly straightforward, with the fourth argument
 401    of DEFTREECODE saying how many operands there are.
 402    Unless otherwise specified, the operands are expressions and the
 403    types of all the operands and the expression must all be the same.  */
 404
 405 /* Contains two expressions to compute, one followed by the other.
 406    the first value is ignored.  The second one's value is used.  The
 407    type of the first expression need not agree with the other types.  */
 408 DEFTREECODE (COMPOUND_EXPR, "compound_expr", 'e', 2)
 409
 410 /* Assignment expression.  Operand 0 is the what to set; 1, the new value.  */
 411 DEFTREECODE (MODIFY_EXPR, "modify_expr", 'e', 2)
 412
 413 /* Initialization expression.  Operand 0 is the variable to initialize;
 414    Operand 1 is the initializer.  */
 415 DEFTREECODE (INIT_EXPR, "init_expr", 'e', 2)
 416
 417 /* For TARGET_EXPR, operand 0 is the target of an initialization,
 418    operand 1 is the initializer for the target,
 419    and operand 2 is the cleanup for this node, if any.
 420    and operand 3 is the saved initializer after this node has been
 421    expanded once, this is so we can re-expand the tree later.  */
 422 DEFTREECODE (TARGET_EXPR, "target_expr", 'e', 4)
 423
 424 /* Conditional expression ( ... ? ... : ...  in C).
 425    Operand 0 is the condition.
 426    Operand 1 is the then-value.
 427    Operand 2 is the else-value.
 428    Operand 0 may be of any type.
 429    Operand 1 must have the same type as the entire expression, unless
 430    it unconditionally throws an exception, in which case it should
 431    have VOID_TYPE.  The same constraints apply to operand 2.  */
 432 DEFTREECODE (COND_EXPR, "cond_expr", 'e', 3)
 433
 434 /* Declare local variables, including making RTL and allocating space.
 435    Operand 0 is a chain of VAR_DECL nodes for the variables.
 436    Operand 1 is the body, the expression to be computed using
 437    the variables.  The value of operand 1 becomes that of the BIND_EXPR.
 438    Operand 2 is the BLOCK that corresponds to these bindings
 439    for debugging purposes.  If this BIND_EXPR is actually expanded,
 440    that sets the TREE_USED flag in the BLOCK.
 441
 442    The BIND_EXPR is not responsible for informing parsers
 443    about these variables.  If the body is coming from the input file,
 444    then the code that creates the BIND_EXPR is also responsible for
 445    informing the parser of the variables.
 446
 447    If the BIND_EXPR is ever expanded, its TREE_USED flag is set.
 448    This tells the code for debugging symbol tables not to ignore the BIND_EXPR.
 449    If the BIND_EXPR should be output for debugging but will not be expanded,
 450    set the TREE_USED flag by hand.
 451
 452    In order for the BIND_EXPR to be known at all, the code that creates it
 453    must also install it as a subblock in the tree of BLOCK
 454    nodes for the function.  */
 455 DEFTREECODE (BIND_EXPR, "bind_expr", 'e', 3)
 456
 457 /* Function call.  Operand 0 is the function.
 458    Operand 1 is the argument list, a list of expressions
 459    made out of a chain of TREE_LIST nodes.  */
 460 DEFTREECODE (CALL_EXPR, "call_expr", 'e', 2)
 461
 462 /* Call a method.  Operand 0 is the method, whose type is a METHOD_TYPE.
 463    Operand 1 is the expression for "self".
 464    Operand 2 is the list of explicit arguments.  */
 465 DEFTREECODE (METHOD_CALL_EXPR, "method_call_expr", 'e', 4)
 466
 467 /* Specify a value to compute along with its corresponding cleanup.
 468    Operand 0 argument is an expression whose value needs a cleanup.
 469    Operand 1 is an RTL_EXPR which will eventually represent that value.
 470    Operand 2 is the cleanup expression for the object.
 471      The RTL_EXPR is used in this expression, which is how the expression
 472      manages to act on the proper value.
 473    The cleanup is executed by the first enclosing CLEANUP_POINT_EXPR, if
 474    it exists, otherwise it is the responsibility of the caller to manually
 475    call expand_start_target_temps/expand_end_target_temps, as needed.
 476
 477    This differs from TRY_CATCH_EXPR in that operand 2 is always
 478    evaluated when an exception isn't thrown when cleanups are run.  */
 479 DEFTREECODE (WITH_CLEANUP_EXPR, "with_cleanup_expr", 'e', 3)
 480
 481 /* Specify a cleanup point.
 482    Operand 0 is an expression that may have cleanups.  If it does, those
 483    cleanups are executed after the expression is expanded.
 484
 485    Note that if the expression is a reference to storage, it is forced out
 486    of memory before the cleanups are run.  This is necessary to handle
 487    cases where the cleanups modify the storage referenced; in the
 488    expression 't.i', if 't' is a struct with an integer member 'i' and a
 489    cleanup which modifies 'i', the value of the expression depends on
 490    whether the cleanup is run before or after 't.i' is evaluated.  When
 491    expand_expr is run on 't.i', it returns a MEM.  This is not good enough;
 492    the value of 't.i' must be forced out of memory.
 493
 494    As a consequence, the operand of a CLEANUP_POINT_EXPR must not have
 495    BLKmode, because it will not be forced out of memory.  */
 496 DEFTREECODE (CLEANUP_POINT_EXPR, "cleanup_point_expr", 'e', 1)
 497
 498 /* The following two codes are used in languages that have types where
 499    some field in an object of the type contains a value that is used in
 500    the computation of another field's offset or size and/or the size of
 501    the type.  The positions and/or sizes of fields can vary from object
 502    to object of the same type.
 503
 504    Record types with discriminants in Ada or schema types in Pascal are
 505    examples of such types.  This mechanism is also used to create "fat
 506    pointers" for unconstrained array types in Ada; the fat pointer is a
 507    structure one of whose fields is a pointer to the actual array type
 508    and the other field is a pointer to a template, which is a structure
 509    containing the bounds of the array.  The bounds in the type pointed
 510    to by the first field in the fat pointer refer to the values in the
 511    template.
 512
 513    When you wish to construct such a type you need "self-references"
 514    that allow you to reference the object having this type from the
 515    TYPE node, i.e. without having a variable instantiating this type.
 516
 517    Such a "self-references" is done using a PLACEHOLDER_EXPR.  This is
 518    a node that will later be replaced with the object being referenced.
 519    Its type is that of the object and selects which object to use from
 520    a chain of references (see below).  No other slots are used in the
 521    PLACEHOLDER_EXPR.
 522
 523    For example, if your type FOO is a RECORD_TYPE with a field BAR,
 524    and you need the value of <variable>.BAR to calculate TYPE_SIZE
 525    (FOO), just substitute <variable> above with a PLACEHOLDER_EXPR
 526    what contains both the expression we wish to
 527    evaluate and an expression within which the object may be found.
 528    The latter expression is the object itself in the simple case of an
 529    Ada record with discriminant, but it can be the array in the case of
 530    an unconstrained array.
 531
 532    In the latter case, we need the fat pointer, because the bounds of
 533    the array can only be accessed from it.  However, we rely here on the
 534    fact that the expression for the array contains the dereference of
 535    the fat pointer that obtained the array pointer.
 536
 537    Accordingly, when looking for the object to substitute in place of
 538    a PLACEHOLDER_EXPR, we look down the first operand of the expression
 539    passed as the second operand to WITH_RECORD_EXPR until we find
 540    something of the desired type or reach a constant.  */
 541
 542 /* Denotes a record to later be supplied with a WITH_RECORD_EXPR when
 543    evaluating this expression.  The type of this expression is used to
 544    find the record to replace it.  */
 545 DEFTREECODE (PLACEHOLDER_EXPR, "placeholder_expr", 'x', 0)
 546
 547 /* Provide an expression that references a record to be used in place
 548    of a PLACEHOLDER_EXPR.  The record to be used is the record within
 549    operand 1 that has the same type as the PLACEHOLDER_EXPR in
 550    operand 0.  */
 551 DEFTREECODE (WITH_RECORD_EXPR, "with_record_expr", 'e', 2)
 552
 553 /* Simple arithmetic.  */
 554 DEFTREECODE (PLUS_EXPR, "plus_expr", '2', 2)
 555 DEFTREECODE (MINUS_EXPR, "minus_expr", '2', 2)
 556 DEFTREECODE (MULT_EXPR, "mult_expr", '2', 2)
 557
 558 /* Division for integer result that rounds the quotient toward zero.  */
 559 DEFTREECODE (TRUNC_DIV_EXPR, "trunc_div_expr", '2', 2)
 560
 561 /* Division for integer result that rounds the quotient toward infinity.  */
 562 DEFTREECODE (CEIL_DIV_EXPR, "ceil_div_expr", '2', 2)
 563
 564 /* Division for integer result that rounds toward minus infinity.  */
 565 DEFTREECODE (FLOOR_DIV_EXPR, "floor_div_expr", '2', 2)
 566
 567 /* Division for integer result that rounds toward nearest integer.  */
 568 DEFTREECODE (ROUND_DIV_EXPR, "round_div_expr", '2', 2)
 569
 570 /* Four kinds of remainder that go with the four kinds of division.  */
 571 DEFTREECODE (TRUNC_MOD_EXPR, "trunc_mod_expr", '2', 2)
 572 DEFTREECODE (CEIL_MOD_EXPR, "ceil_mod_expr", '2', 2)
 573 DEFTREECODE (FLOOR_MOD_EXPR, "floor_mod_expr", '2', 2)
 574 DEFTREECODE (ROUND_MOD_EXPR, "round_mod_expr", '2', 2)
 575
 576 /* Division for real result.  */
 577 DEFTREECODE (RDIV_EXPR, "rdiv_expr", '2', 2)
 578
 579 /* Division which is not supposed to need rounding.
 580    Used for pointer subtraction in C.  */
 581 DEFTREECODE (EXACT_DIV_EXPR, "exact_div_expr", '2', 2)
 582
 583 /* Conversion of real to fixed point: four ways to round,
 584    like the four ways to divide.
 585    CONVERT_EXPR can also be used to convert a real to an integer,
 586    and that is what is used in languages that do not have ways of
 587    specifying which of these is wanted.  Maybe these are not needed.  */
 588 DEFTREECODE (FIX_TRUNC_EXPR, "fix_trunc_expr", '1', 1)
 589 DEFTREECODE (FIX_CEIL_EXPR, "fix_ceil_expr", '1', 1)
 590 DEFTREECODE (FIX_FLOOR_EXPR, "fix_floor_expr", '1', 1)
 591 DEFTREECODE (FIX_ROUND_EXPR, "fix_round_expr", '1', 1)
 592
 593 /* Conversion of an integer to a real.  */
 594 DEFTREECODE (FLOAT_EXPR, "float_expr", '1', 1)
 595
 596 /* Exponentiation.  Operands may have any types;
 597    constraints on value type are not known yet.  */
 598 DEFTREECODE (EXPON_EXPR, "expon_expr", '2', 2)
 599
 600 /* Unary negation.  */
 601 DEFTREECODE (NEGATE_EXPR, "negate_expr", '1', 1)
 602
 603 DEFTREECODE (MIN_EXPR, "min_expr", '2', 2)
 604 DEFTREECODE (MAX_EXPR, "max_expr", '2', 2)
 605
 606 /* Represents the absolute value of the operand.
 607
 608    An ABS_EXPR must have either an INTEGER_TYPE or a REAL_TYPE.  The
 609    operand of the ABS_EXPR must have the same type.  */
 610 DEFTREECODE (ABS_EXPR, "abs_expr", '1', 1)
 611
 612 DEFTREECODE (FFS_EXPR, "ffs_expr", '1', 1)
 613
 614 /* Shift operations for shift and rotate.
 615    Shift means logical shift if done on an
 616    unsigned type, arithmetic shift if done on a signed type.
 617    The second operand is the number of bits to
 618    shift by; it need not be the same type as the first operand and result.  */
 619 DEFTREECODE (LSHIFT_EXPR, "lshift_expr", '2', 2)
 620 DEFTREECODE (RSHIFT_EXPR, "rshift_expr", '2', 2)
 621 DEFTREECODE (LROTATE_EXPR, "lrotate_expr", '2', 2)
 622 DEFTREECODE (RROTATE_EXPR, "rrotate_expr", '2', 2)
 623
 624 /* Bitwise operations.  Operands have same mode as result.  */
 625 DEFTREECODE (BIT_IOR_EXPR, "bit_ior_expr", '2', 2)
 626 DEFTREECODE (BIT_XOR_EXPR, "bit_xor_expr", '2', 2)
 627 DEFTREECODE (BIT_AND_EXPR, "bit_and_expr", '2', 2)
 628 DEFTREECODE (BIT_ANDTC_EXPR, "bit_andtc_expr", '2', 2)
 629 DEFTREECODE (BIT_NOT_EXPR, "bit_not_expr", '1', 1)
 630
 631 /* ANDIF and ORIF allow the second operand not to be computed if the
 632    value of the expression is determined from the first operand.  AND,
 633    OR, and XOR always compute the second operand whether its value is
 634    needed or not (for side effects).  The operand may have
 635    BOOLEAN_TYPE or INTEGER_TYPE.  In either case, the argument will be
 636    either zero or one.  For example, a TRUTH_NOT_EXPR will never have
 637    a INTEGER_TYPE VAR_DECL as its argument; instead, a NE_EXPR will be
 638    used to compare the VAR_DECL to zero, thereby obtaining a node with
 639    value zero or one.  */
 640 DEFTREECODE (TRUTH_ANDIF_EXPR, "truth_andif_expr", 'e', 2)
 641 DEFTREECODE (TRUTH_ORIF_EXPR, "truth_orif_expr", 'e', 2)
 642 DEFTREECODE (TRUTH_AND_EXPR, "truth_and_expr", 'e', 2)
 643 DEFTREECODE (TRUTH_OR_EXPR, "truth_or_expr", 'e', 2)
 644 DEFTREECODE (TRUTH_XOR_EXPR, "truth_xor_expr", 'e', 2)
 645 DEFTREECODE (TRUTH_NOT_EXPR, "truth_not_expr", 'e', 1)
 646
 647 /* Relational operators.
 648    `EQ_EXPR' and `NE_EXPR' are allowed for any types.
 649    The others are allowed only for integer (or pointer or enumeral)
 650    or real types.
 651    In all cases the operands will have the same type,
 652    and the value is always the type used by the language for booleans.  */
 653 DEFTREECODE (LT_EXPR, "lt_expr", '<', 2)
 654 DEFTREECODE (LE_EXPR, "le_expr", '<', 2)
 655 DEFTREECODE (GT_EXPR, "gt_expr", '<', 2)
 656 DEFTREECODE (GE_EXPR, "ge_expr", '<', 2)
 657 DEFTREECODE (EQ_EXPR, "eq_expr", '<', 2)
 658 DEFTREECODE (NE_EXPR, "ne_expr", '<', 2)
 659
 660 /* Additional relational operators for floating point unordered.  */
 661 DEFTREECODE (UNORDERED_EXPR, "unordered_expr", '<', 2)
 662 DEFTREECODE (ORDERED_EXPR, "ordered_expr", '<', 2)
 663
 664 /* These are equivalent to unordered or ... */
 665 DEFTREECODE (UNLT_EXPR, "unlt_expr", '<', 2)
 666 DEFTREECODE (UNLE_EXPR, "unle_expr", '<', 2)
 667 DEFTREECODE (UNGT_EXPR, "ungt_expr", '<', 2)
 668 DEFTREECODE (UNGE_EXPR, "unge_expr", '<', 2)
 669 DEFTREECODE (UNEQ_EXPR, "uneq_expr", '<', 2)
 670
 671 /* Operations for Pascal sets.  Not used now.  */
 672 DEFTREECODE (IN_EXPR, "in_expr", '2', 2)
 673 DEFTREECODE (SET_LE_EXPR, "set_le_expr", '<', 2)
 674 DEFTREECODE (CARD_EXPR, "card_expr", '1', 1)
 675 DEFTREECODE (RANGE_EXPR, "range_expr", '2', 2)
 676
 677 /* Represents a conversion of type of a value.
 678    All conversions, including implicit ones, must be
 679    represented by CONVERT_EXPR or NOP_EXPR nodes.  */
 680 DEFTREECODE (CONVERT_EXPR, "convert_expr", '1', 1)
 681
 682 /* Represents a conversion expected to require no code to be generated.  */
 683 DEFTREECODE (NOP_EXPR, "nop_expr", '1', 1)
 684
 685 /* Value is same as argument, but guaranteed not an lvalue.  */
 686 DEFTREECODE (NON_LVALUE_EXPR, "non_lvalue_expr", '1', 1)
 687
 688 /* Represents something we computed once and will use multiple times.
 689    First operand is that expression.  Second is the function decl
 690    in which the SAVE_EXPR was created.  The third operand is the RTL,
 691    nonzero only after the expression has been computed.  */
 692 DEFTREECODE (SAVE_EXPR, "save_expr", 'e', 3)
 693
 694 /* For a UNSAVE_EXPR, operand 0 is the value to unsave.  By unsave, we
 695    mean that all _EXPRs such as TARGET_EXPRs, SAVE_EXPRs,
 696    CALL_EXPRs and RTL_EXPRs, that are protected
 697    from being evaluated more than once should be reset so that a new
 698    expand_expr call of this expr will cause those to be re-evaluated.
 699    This is useful when we want to reuse a tree in different places,
 700    but where we must re-expand.  */
 701 DEFTREECODE (UNSAVE_EXPR, "unsave_expr", 'e', 1)
 702
 703 /* Represents something whose RTL has already been expanded as a
 704    sequence which should be emitted when this expression is expanded.
 705    The first operand is the RTL to emit.  It is the first of a chain
 706    of insns.  The second is the RTL expression for the result.  Any
 707    temporaries created during the building of the RTL_EXPR can be
 708    reused once the RTL_EXPR has been expanded, with the exception of
 709    the RTL_EXPR_RTL.  */
 710 DEFTREECODE (RTL_EXPR, "rtl_expr", 'e', 2)
 711
 712 /* & in C.  Value is the address at which the operand's value resides.
 713    Operand may have any mode.  Result mode is Pmode.  */
 714 DEFTREECODE (ADDR_EXPR, "addr_expr", 'e', 1)
 715
 716 /* Non-lvalue reference or pointer to an object.  */
 717 DEFTREECODE (REFERENCE_EXPR, "reference_expr", 'e', 1)
 718
 719 /* Operand is a function constant; result is a function variable value
 720    of typeEPmode.  Used only for languages that need static chains.  */
 721 DEFTREECODE (ENTRY_VALUE_EXPR, "entry_value_expr", 'e', 1)
 722
 723 /* Given two real or integer operands of the same type,
 724    returns a complex value of the corresponding complex type.  */
 725 DEFTREECODE (COMPLEX_EXPR, "complex_expr", '2', 2)
 726
 727 /* Complex conjugate of operand.  Used only on complex types.  */
 728 DEFTREECODE (CONJ_EXPR, "conj_expr", '1', 1)
 729
 730 /* Used only on an operand of complex type, these return
 731    a value of the corresponding component type.  */
 732 DEFTREECODE (REALPART_EXPR, "realpart_expr", '1', 1)
 733 DEFTREECODE (IMAGPART_EXPR, "imagpart_expr", '1', 1)
 734
 735 /* Nodes for ++ and -- in C.
 736    The second arg is how much to increment or decrement by.
 737    For a pointer, it would be the size of the object pointed to.  */
 738 DEFTREECODE (PREDECREMENT_EXPR, "predecrement_expr", 'e', 2)
 739 DEFTREECODE (PREINCREMENT_EXPR, "preincrement_expr", 'e', 2)
 740 DEFTREECODE (POSTDECREMENT_EXPR, "postdecrement_expr", 'e', 2)
 741 DEFTREECODE (POSTINCREMENT_EXPR, "postincrement_expr", 'e', 2)
 742
 743 /* Used to implement `va_arg'.  */
 744 DEFTREECODE (VA_ARG_EXPR, "va_arg_expr", 'e', 1)
 745
 746 /* Evaluate operand 1.  If and only if an exception is thrown during
 747    the evaluation of operand 1, evaluate operand 2.
 748
 749    This differs from WITH_CLEANUP_EXPR, in that operand 2 is never
 750    evaluated unless an exception is throw.  */
 751 DEFTREECODE (TRY_CATCH_EXPR, "try_catch_expr", 'e', 2)
 752
 753 /* Evaluate the first operand.
 754    The second operand is a a cleanup expression which is evaluated
 755    before an exit (normal, exception, or jump out) from this expression.
 756
 757    Like a CLEANUP_POINT_EXPR/WITH_CLEANUP_EXPR combination, but those
 758    always copy the cleanup expression where needed.  In contrast,
 759    TRY_FINALLY_EXPR generates a jump to a cleanup subroutine.
 760    (At least conceptually; the optimizer could inline the cleanup
 761    subroutine in the same way it could inline normal subroutines.)
 762    TRY_FINALLY_EXPR should be used when the cleanup is actual statements
 763    in the source of the current function (which people might want to
 764    set breakpoints in).  */
 765 DEFTREECODE (TRY_FINALLY_EXPR, "try_finally", 'e', 2)
 766
 767 /* Used internally for cleanups in the implementation of TRY_FINALLY_EXPR.
 768    (Specifically, it is created by expand_expr, not front-ends.)
 769    Operand 0 is the rtx for the start of the subroutine we need to call.
 770    Operand 1 is the rtx for a variable in which to store the address
 771    of where the subroutine should return to.  */
 772 DEFTREECODE (GOTO_SUBROUTINE_EXPR, "goto_subroutine", 'e', 2)
 773 \f
 774 /* These types of expressions have no useful value,
 775    and always have side effects.  */
 776
 777 /* A label definition, encapsulated as a statement.
 778    Operand 0 is the LABEL_DECL node for the label that appears here.
 779    The type should be void and the value should be ignored.  */
 780 DEFTREECODE (LABEL_EXPR, "label_expr", 's', 1)
 781
 782 /* GOTO.  Operand 0 is a LABEL_DECL node or an expression.
 783    The type should be void and the value should be ignored.  */
 784 DEFTREECODE (GOTO_EXPR, "goto_expr", 's', 1)
 785
 786 /* RETURN.  Evaluates operand 0, then returns from the current function.
 787    Presumably that operand is an assignment that stores into the
 788    RESULT_DECL that hold the value to be returned.
 789    The operand may be null.
 790    The type should be void and the value should be ignored.  */
 791 DEFTREECODE (RETURN_EXPR, "return_expr", 's', 1)
 792
 793 /* Exit the inner most loop conditionally.  Operand 0 is the condition.
 794    The type should be void and the value should be ignored.  */
 795 DEFTREECODE (EXIT_EXPR, "exit_expr", 's', 1)
 796
 797 /* A loop.  Operand 0 is the body of the loop.
 798    It must contain an EXIT_EXPR or is an infinite loop.
 799    The type should be void and the value should be ignored.  */
 800 DEFTREECODE (LOOP_EXPR, "loop_expr", 's', 1)
 801
 802 /* A labeled block. Operand 0 is the label that will be generated to
 803    mark the end of the block.
 804    Operand 1 is the labeled block body.  */
 805 DEFTREECODE (LABELED_BLOCK_EXPR, "labeled_block_expr", 'e', 2)
 806
 807 /* Exit a labeled block, possibly returning a value.  Operand 0 is a
 808    LABELED_BLOCK_EXPR to exit.  Operand 1 is the value to return. It
 809    may be left null.  */
 810 DEFTREECODE (EXIT_BLOCK_EXPR, "exit_block_expr", 'e', 2)
 811
 812 /* Annotates a tree node (usually an expression) with source location
 813    information: a file name (EXPR_WFL_FILENAME);  a line number
 814    (EXPR_WFL_LINENO); and column number (EXPR_WFL_COLNO).  It is
 815    expanded as the contained node (EXPR_WFL_NODE);  a line note should
 816    be emitted first if EXPR_WFL_EMIT_LINE_NOTE.
 817    The third operand is only used in the Java front-end, and will
 818    eventually be removed.  */
 819 DEFTREECODE (EXPR_WITH_FILE_LOCATION, "expr_with_file_location", 'e', 3)
 820
 821 /* Switch expression.
 822    Operand 0 is the expression used to perform the branch,
 823    Operand 1 contains the case values. The way they're organized is
 824    front-end implementation defined. */
 825 DEFTREECODE (SWITCH_EXPR, "switch_expr", 'e', 2)
 826
 827 /* The exception object from the runtime.  */
 828 DEFTREECODE (EXC_PTR_EXPR, "exc_ptr_expr", 'e', 0)
 829
 830 /*
 831 Local variables:
 832 mode:c
 833 End:
 834 */