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