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    DECL_RESULT_TYPE holds the type in which the result is actually
 310     returned.  This is usually the same as the type of DECL_RESULT,
 311     but (1) it may be a wider integer type and
 312     (2) it remains valid, for the sake of inlining, even after the
 313     function's compilation is done.
 314    DECL_FUNCTION_CODE is a code number that is nonzero for
 315     built-in functions.  Its value is an enum built_in_function
 316     that says which built-in function it is.
 317
 318    DECL_SOURCE_FILE holds a filename string and DECL_SOURCE_LINE
 319    holds a line number.  In some cases these can be the location of
 320    a reference, if no definition has been seen.
 321
 322    DECL_ABSTRACT is non-zero if the decl represents an abstract instance
 323    of a decl (i.e. one which is nested within an abstract instance of a
 324    inline function.  */
 325
 326 DEFTREECODE (FUNCTION_DECL, "function_decl", 'd', 0)
 327 DEFTREECODE (LABEL_DECL, "label_decl", 'd', 0)
 328 DEFTREECODE (CONST_DECL, "const_decl", 'd', 0)
 329 DEFTREECODE (TYPE_DECL, "type_decl", 'd', 0)
 330 DEFTREECODE (VAR_DECL, "var_decl", 'd', 0)
 331 DEFTREECODE (PARM_DECL, "parm_decl", 'd', 0)
 332 DEFTREECODE (RESULT_DECL, "result_decl", 'd', 0)
 333 DEFTREECODE (FIELD_DECL, "field_decl", 'd', 0)
 334
 335 /* A namespace declaration.  Namespaces appear in DECL_CONTEXT of other
 336    _DECLs, providing a hierarchy of names.  */
 337 DEFTREECODE (NAMESPACE_DECL, "namespace_decl", 'd', 0)
 338 \f
 339 /* References to storage.  */
 340
 341 /* Value is structure or union component.
 342    Operand 0 is the structure or union (an expression);
 343    operand 1 is the field (a node of type FIELD_DECL).  */
 344 DEFTREECODE (COMPONENT_REF, "component_ref", 'r', 2)
 345
 346 /* Reference to a group of bits within an object.  Similar to COMPONENT_REF
 347    except the position is given explicitly rather than via a FIELD_DECL.
 348    Operand 0 is the structure or union expression;
 349    operand 1 is a tree giving the number of bits being referenced;
 350    operand 2 is a tree giving the position of the first referenced bit.
 351    The field can be either a signed or unsigned field;
 352    TREE_UNSIGNED says which.  */
 353 DEFTREECODE (BIT_FIELD_REF, "bit_field_ref", 'r', 3)
 354
 355 /* C unary `*' or Pascal `^'.  One operand, an expression for a pointer.  */
 356 DEFTREECODE (INDIRECT_REF, "indirect_ref", 'r', 1)
 357
 358 /* Pascal `^` on a file.  One operand, an expression for the file.  */
 359 DEFTREECODE (BUFFER_REF, "buffer_ref", 'r', 1)
 360
 361 /* Array indexing in languages other than C.
 362    Operand 0 is the array; operand 1 is a list of indices
 363    stored as a chain of TREE_LIST nodes.  */
 364 DEFTREECODE (ARRAY_REF, "array_ref", 'r', 2)
 365
 366 /* Constructor: return an aggregate value made from specified components.
 367    In C, this is used only for structure and array initializers.
 368    Also used for SET_TYPE in Chill (and potentially Pascal).
 369    The first "operand" is really a pointer to the RTL,
 370    for constant constructors only.
 371    The second operand is a list of component values
 372    made out of a chain of TREE_LIST nodes.
 373
 374    For ARRAY_TYPE:
 375    The TREE_PURPOSE of each node is the corresponding index.
 376    If the TREE_PURPOSE is a RANGE_EXPR, it is a short-hand for many nodes,
 377    one for each index in the range.  (If the corresponding TREE_VALUE
 378    has side-effects, they are evaluated once for each element.  Wrap the
 379    value in a SAVE_EXPR if you want to evaluate side effects only once.)
 380
 381    For RECORD_TYPE, UNION_TYPE, or QUAL_UNION_TYPE:
 382    The TREE_PURPOSE of each node is a FIELD_DECL.
 383
 384    For SET_TYPE:
 385    The TREE_VALUE specifies a value (index) in the set that is true.
 386    If TREE_PURPOSE is non-NULL, it specifies the lower limit of a
 387    range of true values.  Elements not listed are false (not in the set).  */
 388 DEFTREECODE (CONSTRUCTOR, "constructor", 'e', 2)
 389
 390 /* The expression types are mostly straightforward, with the fourth argument
 391    of DEFTREECODE saying how many operands there are.
 392    Unless otherwise specified, the operands are expressions and the
 393    types of all the operands and the expression must all be the same.  */
 394
 395 /* Contains two expressions to compute, one followed by the other.
 396    the first value is ignored.  The second one's value is used.  The
 397    type of the first expression need not agree with the other types.  */
 398 DEFTREECODE (COMPOUND_EXPR, "compound_expr", 'e', 2)
 399
 400 /* Assignment expression.  Operand 0 is the what to set; 1, the new value.  */
 401 DEFTREECODE (MODIFY_EXPR, "modify_expr", 'e', 2)
 402
 403 /* Initialization expression.  Operand 0 is the variable to initialize;
 404    Operand 1 is the initializer.  */
 405 DEFTREECODE (INIT_EXPR, "init_expr", 'e', 2)
 406
 407 /* For TARGET_EXPR, operand 0 is the target of an initialization,
 408    operand 1 is the initializer for the target,
 409    and operand 2 is the cleanup for this node, if any.
 410    and operand 3 is the saved initializer after this node has been
 411    expanded once, this is so we can re-expand the tree later.  */
 412 DEFTREECODE (TARGET_EXPR, "target_expr", 'e', 4)
 413
 414 /* Conditional expression ( ... ? ... : ...  in C).
 415    Operand 0 is the condition.
 416    Operand 1 is the then-value.
 417    Operand 2 is the else-value.
 418    Operand 0 may be of any type, but the types of operands 1 and 2
 419    must be the same and the same as the type of this expression.  */
 420 DEFTREECODE (COND_EXPR, "cond_expr", 'e', 3)
 421
 422 /* Declare local variables, including making RTL and allocating space.
 423    Operand 0 is a chain of VAR_DECL nodes for the variables.
 424    Operand 1 is the body, the expression to be computed using
 425    the variables.  The value of operand 1 becomes that of the BIND_EXPR.
 426    Operand 2 is the BLOCK that corresponds to these bindings
 427    for debugging purposes.  If this BIND_EXPR is actually expanded,
 428    that sets the TREE_USED flag in the BLOCK.
 429
 430    The BIND_EXPR is not responsible for informing parsers
 431    about these variables.  If the body is coming from the input file,
 432    then the code that creates the BIND_EXPR is also responsible for
 433    informing the parser of the variables.
 434
 435    If the BIND_EXPR is ever expanded, its TREE_USED flag is set.
 436    This tells the code for debugging symbol tables not to ignore the BIND_EXPR.
 437    If the BIND_EXPR should be output for debugging but will not be expanded,
 438    set the TREE_USED flag by hand.
 439
 440    In order for the BIND_EXPR to be known at all, the code that creates it
 441    must also install it as a subblock in the tree of BLOCK
 442    nodes for the function.  */
 443 DEFTREECODE (BIND_EXPR, "bind_expr", 'e', 3)
 444
 445 /* Function call.  Operand 0 is the function.
 446    Operand 1 is the argument list, a list of expressions
 447    made out of a chain of TREE_LIST nodes.
 448    There is no operand 2.  That slot is used for the
 449    CALL_EXPR_RTL macro (see preexpand_calls).  */
 450 DEFTREECODE (CALL_EXPR, "call_expr", 'e', 3)
 451
 452 /* Call a method.  Operand 0 is the method, whose type is a METHOD_TYPE.
 453    Operand 1 is the expression for "self".
 454    Operand 2 is the list of explicit arguments.  */
 455 DEFTREECODE (METHOD_CALL_EXPR, "method_call_expr", 'e', 4)
 456
 457 /* Specify a value to compute along with its corresponding cleanup.
 458    Operand 0 argument is an expression whose value needs a cleanup.
 459    Operand 1 is an RTL_EXPR which will eventually represent that value.
 460    Operand 2 is the cleanup expression for the object.
 461      The RTL_EXPR is used in this expression, which is how the expression
 462      manages to act on the proper value.
 463    The cleanup is executed by the first enclosing CLEANUP_POINT_EXPR, if
 464    it exists, otherwise it is the responsibility of the caller to manually
 465    call expand_start_target_temps/expand_end_target_temps, as needed.
 466
 467    This differs from TRY_CATCH_EXPR in that operand 2 is always
 468    evaluated when an exception isn't thrown when cleanups are run.  */
 469 DEFTREECODE (WITH_CLEANUP_EXPR, "with_cleanup_expr", 'e', 3)
 470
 471 /* Specify a cleanup point.
 472    Operand 0 is an expression that may have cleanups.  If it does, those
 473    cleanups are executed after the expression is expanded.
 474
 475    Note that if the expression is a reference to storage, it is forced out
 476    of memory before the cleanups are run.  This is necessary to handle
 477    cases where the cleanups modify the storage referenced; in the
 478    expression 't.i', if 't' is a struct with an integer member 'i' and a
 479    cleanup which modifies 'i', the value of the expression depends on
 480    whether the cleanup is run before or after 't.i' is evaluated.  When
 481    expand_expr is run on 't.i', it returns a MEM.  This is not good enough;
 482    the value of 't.i' must be forced out of memory.
 483
 484    As a consequence, the operand of a CLEANUP_POINT_EXPR must not have
 485    BLKmode, because it will not be forced out of memory.  */
 486 DEFTREECODE (CLEANUP_POINT_EXPR, "cleanup_point_expr", 'e', 1)
 487
 488 /* The following two codes are used in languages that have types where
 489    the position and/or sizes of fields vary from object to object of the
 490    same type, i.e., where some other field in the object contains a value
 491    that is used in the computation of another field's offset or size.
 492
 493    For example, a record type with a discriminant in Ada is such a type.
 494    This mechanism is also used to create "fat pointers" for unconstrained
 495    array types in Ada; the fat pointer is a structure one of whose fields is
 496    a pointer to the actual array type and the other field is a pointer to a
 497    template, which is a structure containing the bounds of the array.  The
 498    bounds in the type pointed to by the first field in the fat pointer refer
 499    to the values in the template.
 500
 501    These "self-references" are doing using a PLACEHOLDER_EXPR.  This is a
 502    node that will later be replaced with the object being referenced.  Its type
 503    is that of the object and selects which object to use from a chain of
 504    references (see below).
 505
 506    When we wish to evaluate a size or offset, we check it is contains a
 507    placeholder.  If it does, we construct a WITH_RECORD_EXPR that contains
 508    both the expression we wish to evaluate and an expression within which the
 509    object may be found.  The latter expression is the object itself in
 510    the simple case of an Ada record with discriminant, but it can be the
 511    array in the case of an unconstrained array.
 512
 513    In the latter case, we need the fat pointer, because the bounds of the
 514    array can only be accessed from it.  However, we rely here on the fact that
 515    the expression for the array contains the dereference of the fat pointer
 516    that obtained the array pointer.
 517
 518    Accordingly, when looking for the object to substitute in place of
 519    a PLACEHOLDER_EXPR, we look down the first operand of the expression
 520    passed as the second operand to WITH_RECORD_EXPR until we find something
 521    of the desired type or reach a constant.  */
 522
 523 /* Denotes a record to later be supplied with a WITH_RECORD_EXPR when
 524    evaluating this expression.  The type of this expression is used to
 525    find the record to replace it.  */
 526 DEFTREECODE (PLACEHOLDER_EXPR, "placeholder_expr", 'x', 0)
 527
 528 /* Provide an expression that references a record to be used in place
 529    of a PLACEHOLDER_EXPR.  The record to be used is the record within
 530    operand 1 that has the same type as the PLACEHOLDER_EXPR in
 531    operand 0.  */
 532 DEFTREECODE (WITH_RECORD_EXPR, "with_record_expr", 'e', 2)
 533
 534 /* Simple arithmetic.  */
 535 DEFTREECODE (PLUS_EXPR, "plus_expr", '2', 2)
 536 DEFTREECODE (MINUS_EXPR, "minus_expr", '2', 2)
 537 DEFTREECODE (MULT_EXPR, "mult_expr", '2', 2)
 538
 539 /* Division for integer result that rounds the quotient toward zero.  */
 540 DEFTREECODE (TRUNC_DIV_EXPR, "trunc_div_expr", '2', 2)
 541
 542 /* Division for integer result that rounds the quotient toward infinity.  */
 543 DEFTREECODE (CEIL_DIV_EXPR, "ceil_div_expr", '2', 2)
 544
 545 /* Division for integer result that rounds toward minus infinity.  */
 546 DEFTREECODE (FLOOR_DIV_EXPR, "floor_div_expr", '2', 2)
 547
 548 /* Division for integer result that rounds toward nearest integer.  */
 549 DEFTREECODE (ROUND_DIV_EXPR, "round_div_expr", '2', 2)
 550
 551 /* Four kinds of remainder that go with the four kinds of division.  */
 552 DEFTREECODE (TRUNC_MOD_EXPR, "trunc_mod_expr", '2', 2)
 553 DEFTREECODE (CEIL_MOD_EXPR, "ceil_mod_expr", '2', 2)
 554 DEFTREECODE (FLOOR_MOD_EXPR, "floor_mod_expr", '2', 2)
 555 DEFTREECODE (ROUND_MOD_EXPR, "round_mod_expr", '2', 2)
 556
 557 /* Division for real result.  */
 558 DEFTREECODE (RDIV_EXPR, "rdiv_expr", '2', 2)
 559
 560 /* Division which is not supposed to need rounding.
 561    Used for pointer subtraction in C.  */
 562 DEFTREECODE (EXACT_DIV_EXPR, "exact_div_expr", '2', 2)
 563
 564 /* Conversion of real to fixed point: four ways to round,
 565    like the four ways to divide.
 566    CONVERT_EXPR can also be used to convert a real to an integer,
 567    and that is what is used in languages that do not have ways of
 568    specifying which of these is wanted.  Maybe these are not needed.  */
 569 DEFTREECODE (FIX_TRUNC_EXPR, "fix_trunc_expr", '1', 1)
 570 DEFTREECODE (FIX_CEIL_EXPR, "fix_ceil_expr", '1', 1)
 571 DEFTREECODE (FIX_FLOOR_EXPR, "fix_floor_expr", '1', 1)
 572 DEFTREECODE (FIX_ROUND_EXPR, "fix_round_expr", '1', 1)
 573
 574 /* Conversion of an integer to a real.  */
 575 DEFTREECODE (FLOAT_EXPR, "float_expr", '1', 1)
 576
 577 /* Exponentiation.  Operands may have any types;
 578    constraints on value type are not known yet.  */
 579 DEFTREECODE (EXPON_EXPR, "expon_expr", '2', 2)
 580
 581 /* Unary negation.  */
 582 DEFTREECODE (NEGATE_EXPR, "negate_expr", '1', 1)
 583
 584 DEFTREECODE (MIN_EXPR, "min_expr", '2', 2)
 585 DEFTREECODE (MAX_EXPR, "max_expr", '2', 2)
 586 DEFTREECODE (ABS_EXPR, "abs_expr", '1', 1)
 587 DEFTREECODE (FFS_EXPR, "ffs_expr", '1', 1)
 588
 589 /* Shift operations for shift and rotate.
 590    Shift is supposed to mean logical shift if done on an
 591    unsigned type, arithmetic shift on a signed type.
 592    The second operand is the number of bits to
 593    shift by; it need not be the same type as the first operand and result.  */
 594 DEFTREECODE (LSHIFT_EXPR, "lshift_expr", '2', 2)
 595 DEFTREECODE (RSHIFT_EXPR, "rshift_expr", '2', 2)
 596 DEFTREECODE (LROTATE_EXPR, "lrotate_expr", '2', 2)
 597 DEFTREECODE (RROTATE_EXPR, "rrotate_expr", '2', 2)
 598
 599 /* Bitwise operations.  Operands have same mode as result.  */
 600 DEFTREECODE (BIT_IOR_EXPR, "bit_ior_expr", '2', 2)
 601 DEFTREECODE (BIT_XOR_EXPR, "bit_xor_expr", '2', 2)
 602 DEFTREECODE (BIT_AND_EXPR, "bit_and_expr", '2', 2)
 603 DEFTREECODE (BIT_ANDTC_EXPR, "bit_andtc_expr", '2', 2)
 604 DEFTREECODE (BIT_NOT_EXPR, "bit_not_expr", '1', 1)
 605
 606 /* Combination of boolean values or of integers considered only
 607    as zero or nonzero.  ANDIF and ORIF allow the second operand
 608    not to be computed if the value of the expression is determined
 609    from the first operand.  AND, OR, and XOR always compute the second
 610    operand whether its value is needed or not (for side effects).  */
 611 DEFTREECODE (TRUTH_ANDIF_EXPR, "truth_andif_expr", 'e', 2)
 612 DEFTREECODE (TRUTH_ORIF_EXPR, "truth_orif_expr", 'e', 2)
 613 DEFTREECODE (TRUTH_AND_EXPR, "truth_and_expr", 'e', 2)
 614 DEFTREECODE (TRUTH_OR_EXPR, "truth_or_expr", 'e', 2)
 615 DEFTREECODE (TRUTH_XOR_EXPR, "truth_xor_expr", 'e', 2)
 616 DEFTREECODE (TRUTH_NOT_EXPR, "truth_not_expr", 'e', 1)
 617
 618 /* Relational operators.
 619    `EQ_EXPR' and `NE_EXPR' are allowed for any types.
 620    The others are allowed only for integer (or pointer or enumeral)
 621    or real types.
 622    In all cases the operands will have the same type,
 623    and the value is always the type used by the language for booleans.  */
 624 DEFTREECODE (LT_EXPR, "lt_expr", '<', 2)
 625 DEFTREECODE (LE_EXPR, "le_expr", '<', 2)
 626 DEFTREECODE (GT_EXPR, "gt_expr", '<', 2)
 627 DEFTREECODE (GE_EXPR, "ge_expr", '<', 2)
 628 DEFTREECODE (EQ_EXPR, "eq_expr", '<', 2)
 629 DEFTREECODE (NE_EXPR, "ne_expr", '<', 2)
 630
 631 /* Operations for Pascal sets.  Not used now.  */
 632 DEFTREECODE (IN_EXPR, "in_expr", '2', 2)
 633 DEFTREECODE (SET_LE_EXPR, "set_le_expr", '<', 2)
 634 DEFTREECODE (CARD_EXPR, "card_expr", '1', 1)
 635 DEFTREECODE (RANGE_EXPR, "range_expr", '2', 2)
 636
 637 /* Represents a conversion of type of a value.
 638    All conversions, including implicit ones, must be
 639    represented by CONVERT_EXPR or NOP_EXPR nodes.  */
 640 DEFTREECODE (CONVERT_EXPR, "convert_expr", '1', 1)
 641
 642 /* Represents a conversion expected to require no code to be generated.  */
 643 DEFTREECODE (NOP_EXPR, "nop_expr", '1', 1)
 644
 645 /* Value is same as argument, but guaranteed not an lvalue.  */
 646 DEFTREECODE (NON_LVALUE_EXPR, "non_lvalue_expr", '1', 1)
 647
 648 /* Represents something we computed once and will use multiple times.
 649    First operand is that expression.  Second is the function decl
 650    in which the SAVE_EXPR was created.  The third operand is the RTL,
 651    nonzero only after the expression has been computed.  */
 652 DEFTREECODE (SAVE_EXPR, "save_expr", 'e', 3)
 653
 654 /* For a UNSAVE_EXPR, operand 0 is the value to unsave.  By unsave, we
 655    mean that all _EXPRs such as TARGET_EXPRs, SAVE_EXPRs,
 656    CALL_EXPRs and RTL_EXPRs, that are protected
 657    from being evaluated more than once should be reset so that a new
 658    expand_expr call of this expr will cause those to be re-evaluated.
 659    This is useful when we want to reuse a tree in different places,
 660    but where we must re-expand.  */
 661 DEFTREECODE (UNSAVE_EXPR, "unsave_expr", 'e', 1)
 662
 663 /* Represents something whose RTL has already been expanded
 664    as a sequence which should be emitted when this expression is expanded.
 665    The first operand is the RTL to emit.  It is the first of a chain of insns.
 666    The second is the RTL expression for the result.  */
 667 DEFTREECODE (RTL_EXPR, "rtl_expr", 'e', 2)
 668
 669 /* & in C.  Value is the address at which the operand's value resides.
 670    Operand may have any mode.  Result mode is Pmode.  */
 671 DEFTREECODE (ADDR_EXPR, "addr_expr", 'e', 1)
 672
 673 /* Non-lvalue reference or pointer to an object.  */
 674 DEFTREECODE (REFERENCE_EXPR, "reference_expr", 'e', 1)
 675
 676 /* Operand is a function constant; result is a function variable value
 677    of typeEPmode.  Used only for languages that need static chains.  */
 678 DEFTREECODE (ENTRY_VALUE_EXPR, "entry_value_expr", 'e', 1)
 679
 680 /* Given two real or integer operands of the same type,
 681    returns a complex value of the corresponding complex type.  */
 682 DEFTREECODE (COMPLEX_EXPR, "complex_expr", '2', 2)
 683
 684 /* Complex conjugate of operand.  Used only on complex types.  */
 685 DEFTREECODE (CONJ_EXPR, "conj_expr", '1', 1)
 686
 687 /* Used only on an operand of complex type, these return
 688    a value of the corresponding component type.  */
 689 DEFTREECODE (REALPART_EXPR, "realpart_expr", '1', 1)
 690 DEFTREECODE (IMAGPART_EXPR, "imagpart_expr", '1', 1)
 691
 692 /* Nodes for ++ and -- in C.
 693    The second arg is how much to increment or decrement by.
 694    For a pointer, it would be the size of the object pointed to.  */
 695 DEFTREECODE (PREDECREMENT_EXPR, "predecrement_expr", 'e', 2)
 696 DEFTREECODE (PREINCREMENT_EXPR, "preincrement_expr", 'e', 2)
 697 DEFTREECODE (POSTDECREMENT_EXPR, "postdecrement_expr", 'e', 2)
 698 DEFTREECODE (POSTINCREMENT_EXPR, "postincrement_expr", 'e', 2)
 699
 700 /* Evaluate operand 1.  If and only if an exception is thrown during
 701    the evaluation of operand 1, evaluate operand 2.
 702
 703    This differs from WITH_CLEANUP_EXPR, in that operand 2 is never
 704    evaluated unless an exception is throw.  */
 705 DEFTREECODE (TRY_CATCH_EXPR, "try_catch_expr", 'e', 2)
 706
 707 /* Pop the top element off the dynamic handler chain.  Used in
 708    conjunction with setjmp/longjmp based exception handling, see
 709    except.c for more details.  This is meant to be used only by the
 710    exception handling backend, expand_dhc_cleanup specifically.  */
 711 DEFTREECODE (POPDHC_EXPR, "popdhc_expr", 's', 0)
 712
 713 /* Pop the top element off the dynamic cleanup chain.  Used in
 714    conjunction with the exception handling.  This is meant to be used
 715    only by the exception handling backend.  */
 716 DEFTREECODE (POPDCC_EXPR, "popdcc_expr", 's', 0)
 717 \f
 718 /* These types of expressions have no useful value,
 719    and always have side effects.  */
 720
 721 /* A label definition, encapsulated as a statement.
 722    Operand 0 is the LABEL_DECL node for the label that appears here.
 723    The type should be void and the value should be ignored.  */
 724 DEFTREECODE (LABEL_EXPR, "label_expr", 's', 1)
 725
 726 /* GOTO.  Operand 0 is a LABEL_DECL node.
 727    The type should be void and the value should be ignored.  */
 728 DEFTREECODE (GOTO_EXPR, "goto_expr", 's', 1)
 729
 730 /* RETURN.  Evaluates operand 0, then returns from the current function.
 731    Presumably that operand is an assignment that stores into the
 732    RESULT_DECL that hold the value to be returned.
 733    The operand may be null.
 734    The type should be void and the value should be ignored.  */
 735 DEFTREECODE (RETURN_EXPR, "return_expr", 's', 1)
 736
 737 /* Exit the inner most loop conditionally.  Operand 0 is the condition.
 738    The type should be void and the value should be ignored.  */
 739 DEFTREECODE (EXIT_EXPR, "exit_expr", 's', 1)
 740
 741 /* A loop.  Operand 0 is the body of the loop.
 742    It must contain an EXIT_EXPR or is an infinite loop.
 743    The type should be void and the value should be ignored.  */
 744 DEFTREECODE (LOOP_EXPR, "loop_expr", 's', 1)
 745
 746 /* Used to represent a tree node, such as IDENTIFIER_NODE or an EXPR
 747    node, adding several location information: a file name, a line
 748    number and column number. It is expanded as the node it refers to
 749    and can be considered a no-op "conversion" with an annotation.  */
 750 DEFTREECODE (EXPR_WITH_FILE_LOCATION, "expr_with_file_location", '1', 2)
 751 /*
 752 Local variables:
 753 mode:c
 754 End:
 755 */