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 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    A few may need to be added for Pascal.  */
 213 /* See the comment above, before ENUMERAL_TYPE, for how
 214    forward references to struct tags are handled in C.  */
 215 DEFTREECODE (RECORD_TYPE, "record_type", "t", 0)
 216
 217 /* Union in C.  Like a struct, except that the offsets of the fields
 218    will all be zero.  */
 219 /* See the comment above, before ENUMERAL_TYPE, for how
 220    forward references to union tags are handled in C.  */
 221 DEFTREECODE (UNION_TYPE, "union_type", "t", 0)  /* C union type */
 222
 223 /* Similar to UNION_TYPE, except that the expressions in DECL_QUALIFIER
 224    in each FIELD_DECL determine what the union contains.  The first
 225    field whose DECL_QUALIFIER expression is true is deemed to occupy
 226    the union.  */
 227 DEFTREECODE (QUAL_UNION_TYPE, "qual_union_type", "t", 0)
 228
 229 /* Type of functions.  Special fields:
 230    TREE_TYPE                type of value returned.
 231    TYPE_ARG_TYPES      list of types of arguments expected.
 232         this list is made of TREE_LIST nodes.
 233    Types of "Procedures" in languages where they are different from functions
 234    have code FUNCTION_TYPE also, but then TREE_TYPE is zero or void type.  */
 235 DEFTREECODE (FUNCTION_TYPE, "function_type", "t", 0)
 236
 237 /* This is a language-specific kind of type.
 238    Its meaning is defined by the language front end.
 239    layout_type does not know how to lay this out,
 240    so the front-end must do so manually.  */
 241 DEFTREECODE (LANG_TYPE, "lang_type", "t", 0)
 242 \f
 243 /* Expressions */
 244
 245 /* First, the constants.  */
 246
 247 /* Contents are in TREE_INT_CST_LOW and TREE_INT_CST_HIGH fields,
 248    32 bits each, giving us a 64 bit constant capability.
 249    Note: constants of type char in Pascal are INTEGER_CST,
 250    and so are pointer constants such as nil in Pascal or NULL in C.
 251    `(int *) 1' in C also results in an INTEGER_CST.  */
 252 DEFTREECODE (INTEGER_CST, "integer_cst", "c", 2)
 253
 254 /* Contents are in TREE_REAL_CST field.  Also there is TREE_CST_RTL.  */
 255 DEFTREECODE (REAL_CST, "real_cst", "c", 3)
 256
 257 /* Contents are in TREE_REALPART and TREE_IMAGPART fields,
 258    whose contents are other constant nodes.
 259    Also there is TREE_CST_RTL.  */
 260 DEFTREECODE (COMPLEX_CST, "complex_cst", "c", 3)
 261
 262 /* Contents are TREE_STRING_LENGTH and TREE_STRING_POINTER fields.
 263    Also there is TREE_CST_RTL.  */
 264 DEFTREECODE (STRING_CST, "string_cst", "c", 3)
 265
 266 /* Declarations.  All references to names are represented as ..._DECL nodes.
 267    The decls in one binding context are chained through the TREE_CHAIN field.
 268    Each DECL has a DECL_NAME field which contains an IDENTIFIER_NODE.
 269     (Some decls, most often labels, may have zero as the DECL_NAME).
 270    DECL_CONTEXT points to the node representing the context in which
 271     this declaration has its scope.  For FIELD_DECLs, this is the
 272     RECORD_TYPE, UNION_TYPE, or QUAL_UNION_TYPE node that the field
 273     is a member of.  For VAR_DECL, PARM_DECL, FUNCTION_DECL, LABEL_DECL,
 274     and CONST_DECL nodes, this points to the FUNCTION_DECL for the
 275     containing function, or else yields NULL_TREE if the given decl
 276     has "file scope".
 277    DECL_ABSTRACT_ORIGIN, if non-NULL, points to the original (abstract)
 278     ..._DECL node of which this decl is an (inlined or template expanded)
 279     instance.
 280    The TREE_TYPE field holds the data type of the object, when relevant.
 281     LABEL_DECLs have no data type.  For TYPE_DECL, the TREE_TYPE field
 282     contents are the type whose name is being declared.
 283    The DECL_ALIGN, DECL_SIZE,
 284     and DECL_MODE fields exist in decl nodes just as in type nodes.
 285     They are unused in LABEL_DECL, TYPE_DECL and CONST_DECL nodes.
 286
 287    DECL_OFFSET holds an integer number of bits offset for the location.
 288    DECL_VOFFSET holds an expression for a variable offset; it is
 289    to be multiplied by DECL_VOFFSET_UNIT (an integer).
 290    These fields are relevant only in FIELD_DECLs and PARM_DECLs.
 291
 292    DECL_INITIAL holds the value to initialize a variable to,
 293    or the value of a constant.  For a function, it holds the body
 294    (a node of type BLOCK representing the function's binding contour
 295    and whose body contains the function's statements.)  For a LABEL_DECL
 296    in C, it is a flag, nonzero if the label's definition has been seen.
 297
 298    PARM_DECLs use a special field:
 299    DECL_ARG_TYPE is the type in which the argument is actually
 300     passed, which may be different from its type within the function.
 301
 302    FUNCTION_DECLs use four special fields:
 303    DECL_ARGUMENTS holds a chain of PARM_DECL nodes for the arguments.
 304    DECL_RESULT holds a RESULT_DECL node for the value of a function,
 305     or it is 0 for a function that returns no value.
 306     (C functions returning void have zero here.)
 307    DECL_RESULT_TYPE holds the type in which the result is actually
 308     returned.  This is usually the same as the type of DECL_RESULT,
 309     but (1) it may be a wider integer type and
 310     (2) it remains valid, for the sake of inlining, even after the
 311     function's compilation is done.
 312    DECL_FUNCTION_CODE is a code number that is nonzero for
 313     built-in functions.  Its value is an enum built_in_function
 314     that says which built-in function it is.
 315
 316    DECL_SOURCE_FILE holds a filename string and DECL_SOURCE_LINE
 317    holds a line number.  In some cases these can be the location of
 318    a reference, if no definition has been seen.
 319
 320    DECL_ABSTRACT is non-zero if the decl represents an abstract instance
 321    of a decl (i.e. one which is nested within an abstract instance of a
 322    inline function.  */
 323
 324 DEFTREECODE (FUNCTION_DECL, "function_decl", "d", 0)
 325 DEFTREECODE (LABEL_DECL, "label_decl", "d", 0)
 326 DEFTREECODE (CONST_DECL, "const_decl", "d", 0)
 327 DEFTREECODE (TYPE_DECL, "type_decl", "d", 0)
 328 DEFTREECODE (VAR_DECL, "var_decl", "d", 0)
 329 DEFTREECODE (PARM_DECL, "parm_decl", "d", 0)
 330 DEFTREECODE (RESULT_DECL, "result_decl", "d", 0)
 331 DEFTREECODE (FIELD_DECL, "field_decl", "d", 0)
 332 \f
 333 /* References to storage.  */
 334
 335 /* Value is structure or union component.
 336    Operand 0 is the structure or union (an expression);
 337    operand 1 is the field (a node of type FIELD_DECL).  */
 338 DEFTREECODE (COMPONENT_REF, "component_ref", "r", 2)
 339
 340 /* Reference to a group of bits within an object.  Similar to COMPONENT_REF
 341    except the position is given explicitly rather than via a FIELD_DECL.
 342    Operand 0 is the structure or union expression;
 343    operand 1 is a tree giving the number of bits being referenced;
 344    operand 2 is a tree giving the position of the first referenced bit.
 345    The field can be either a signed or unsigned field;
 346    TREE_UNSIGNED says which.  */
 347 DEFTREECODE (BIT_FIELD_REF, "bit_field_ref", "r", 3)
 348
 349 /* C unary `*' or Pascal `^'.  One operand, an expression for a pointer.  */
 350 DEFTREECODE (INDIRECT_REF, "indirect_ref", "r", 1)
 351
 352 /* Reference to the contents of an offset
 353    (a value whose type is an OFFSET_TYPE).
 354    Operand 0 is the object within which the offset is taken.
 355    Operand 1 is the offset.  */
 356 DEFTREECODE (OFFSET_REF, "offset_ref", "r", 2)
 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 DEFTREECODE (TARGET_EXPR, "target_expr", "e", 3)
 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 types, but the types of operands 1 and 2
 417    must be the same and the same as the the 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_cleanups_to, as needed.  */
 464 DEFTREECODE (WITH_CLEANUP_EXPR, "with_cleanup_expr", "e", 3)
 465
 466 /* Specify a cleanup point.
 467    Operand 0 is an expression that may have cleanups.  If it does, those
 468    cleanups are executed after the expression is expanded.
 469
 470    Note that if the expression is a reference to storage, it is forced out
 471    of memory before the cleanups are run.  This is necessary to handle
 472    cases where the cleanups modify the storage referenced; in the
 473    expression 't.i', if 't' is a struct with an integer member 'i' and a
 474    cleanup which modifies 'i', the value of the expression depends on
 475    whether the cleanup is run before or after 't.i' is evaluated.  When
 476    expand_expr is run on 't.i', it returns a MEM.  This is not good enough;
 477    the value of 't.i' must be forced out of memory.
 478
 479    As a consequence, the operand of a CLEANUP_POINT_EXPR must not have
 480    BLKmode, because it will not be forced out of memory.  */
 481 DEFTREECODE (CLEANUP_POINT_EXPR, "cleanup_point_expr", "e", 1)
 482
 483 /* The following two codes are used in languages that have types where
 484    the position and/or sizes of fields vary from object to object of the
 485    same type, i.e., where some other field in the object contains a value
 486    that is used in the computation of another field's offset or size.
 487
 488    For example, a record type with a discriminant in Ada is such a type.
 489    This mechanism is also used to create "fat pointers" for unconstrained
 490    array types in Ada; the fat pointer is a structure one of whose fields is
 491    a pointer to the actual array type and the other field is a pointer to a
 492    template, which is a structure containing the bounds of the array.  The
 493    bounds in the type pointed to by the first field in the fat pointer refer
 494    to the values in the template.
 495
 496    These "self-references" are doing using a PLACEHOLDER_EXPR.  This is a
 497    node that will later be replaced with the object being referenced.  Its type
 498    is that of the object and selects which object to use from a chain of
 499    references (see below).
 500
 501    When we wish to evaluate a size or offset, we check it is contains a
 502    placeholder.  If it does, we construct a WITH_RECORD_EXPR that contains
 503    both the expression we wish to evaluate and an expression within which the
 504    object may be found.  The latter expression is the object itself in
 505    the simple case of an Ada record with discriminant, but it can be the
 506    array in the case of an unconstrained array.
 507
 508    In the latter case, we need the fat pointer, because the bounds of the
 509    array can only be accessed from it.  However, we rely here on the fact that
 510    the expression for the array contains the dereference of the fat pointer
 511    that obtained the array pointer.
 512
 513    Accordingly, when looking for the object to substitute in place of
 514    a PLACEHOLDER_EXPR, we look down the first operand of the expression
 515    passed as the second operand to WITH_RECORD_EXPR until we find something
 516    of the desired type or reach a constant.  */
 517
 518 /* Denotes a record to later be supplied with a WITH_RECORD_EXPR when
 519    evaluating this expression.  The type of this expression is used to
 520    find the record to replace it.  */
 521 DEFTREECODE (PLACEHOLDER_EXPR, "placeholder_expr", "x", 0)
 522
 523 /* Provide an expression that references a record to be used in place
 524    of a PLACEHOLDER_EXPR.  The record to be used is the record within
 525    operand 1 that has the same type as the PLACEHOLDER_EXPR in
 526    operand 0.  */
 527 DEFTREECODE (WITH_RECORD_EXPR, "with_record_expr", "e", 2)
 528
 529 /* Simple arithmetic.  */
 530 DEFTREECODE (PLUS_EXPR, "plus_expr", "2", 2)
 531 DEFTREECODE (MINUS_EXPR, "minus_expr", "2", 2)
 532 DEFTREECODE (MULT_EXPR, "mult_expr", "2", 2)
 533
 534 /* Division for integer result that rounds the quotient toward zero.  */
 535 DEFTREECODE (TRUNC_DIV_EXPR, "trunc_div_expr", "2", 2)
 536
 537 /* Division for integer result that rounds the quotient toward infinity.  */
 538 DEFTREECODE (CEIL_DIV_EXPR, "ceil_div_expr", "2", 2)
 539
 540 /* Division for integer result that rounds toward minus infinity.  */
 541 DEFTREECODE (FLOOR_DIV_EXPR, "floor_div_expr", "2", 2)
 542
 543 /* Division for integer result that rounds toward nearest integer.  */
 544 DEFTREECODE (ROUND_DIV_EXPR, "round_div_expr", "2", 2)
 545
 546 /* Four kinds of remainder that go with the four kinds of division.  */
 547 DEFTREECODE (TRUNC_MOD_EXPR, "trunc_mod_expr", "2", 2)
 548 DEFTREECODE (CEIL_MOD_EXPR, "ceil_mod_expr", "2", 2)
 549 DEFTREECODE (FLOOR_MOD_EXPR, "floor_mod_expr", "2", 2)
 550 DEFTREECODE (ROUND_MOD_EXPR, "round_mod_expr", "2", 2)
 551
 552 /* Division for real result.  */
 553 DEFTREECODE (RDIV_EXPR, "rdiv_expr", "2", 2)
 554
 555 /* Division which is not supposed to need rounding.
 556    Used for pointer subtraction in C.  */
 557 DEFTREECODE (EXACT_DIV_EXPR, "exact_div_expr", "2", 2)
 558
 559 /* Conversion of real to fixed point: four ways to round,
 560    like the four ways to divide.
 561    CONVERT_EXPR can also be used to convert a real to an integer,
 562    and that is what is used in languages that do not have ways of
 563    specifying which of these is wanted.  Maybe these are not needed.  */
 564 DEFTREECODE (FIX_TRUNC_EXPR, "fix_trunc_expr", "1", 1)
 565 DEFTREECODE (FIX_CEIL_EXPR, "fix_ceil_expr", "1", 1)
 566 DEFTREECODE (FIX_FLOOR_EXPR, "fix_floor_expr", "1", 1)
 567 DEFTREECODE (FIX_ROUND_EXPR, "fix_round_expr", "1", 1)
 568
 569 /* Conversion of an integer to a real.  */
 570 DEFTREECODE (FLOAT_EXPR, "float_expr", "1", 1)
 571
 572 /* Exponentiation.  Operands may have any types;
 573    constraints on value type are not known yet.  */
 574 DEFTREECODE (EXPON_EXPR, "expon_expr", "2", 2)
 575
 576 /* Unary negation.  */
 577 DEFTREECODE (NEGATE_EXPR, "negate_expr", "1", 1)
 578
 579 DEFTREECODE (MIN_EXPR, "min_expr", "2", 2)
 580 DEFTREECODE (MAX_EXPR, "max_expr", "2", 2)
 581 DEFTREECODE (ABS_EXPR, "abs_expr", "1", 1)
 582 DEFTREECODE (FFS_EXPR, "ffs_expr", "1", 1)
 583
 584 /* Shift operations for shift and rotate.
 585    Shift is supposed to mean logical shift if done on an
 586    unsigned type, arithmetic shift on a signed type.
 587    The second operand is the number of bits to
 588    shift by; it need not be the same type as the first operand and result.  */
 589 DEFTREECODE (LSHIFT_EXPR, "alshift_expr", "2", 2)
 590 DEFTREECODE (RSHIFT_EXPR, "arshift_expr", "2", 2)
 591 DEFTREECODE (LROTATE_EXPR, "lrotate_expr", "2", 2)
 592 DEFTREECODE (RROTATE_EXPR, "rrotate_expr", "2", 2)
 593
 594 /* Bitwise operations.  Operands have same mode as result.  */
 595 DEFTREECODE (BIT_IOR_EXPR, "bit_ior_expr", "2", 2)
 596 DEFTREECODE (BIT_XOR_EXPR, "bit_xor_expr", "2", 2)
 597 DEFTREECODE (BIT_AND_EXPR, "bit_and_expr", "2", 2)
 598 DEFTREECODE (BIT_ANDTC_EXPR, "bit_andtc_expr", "2", 2)
 599 DEFTREECODE (BIT_NOT_EXPR, "bit_not_expr", "1", 1)
 600
 601 /* Combination of boolean values or of integers considered only
 602    as zero or nonzero.  ANDIF and ORIF allow the second operand
 603    not to be computed if the value of the expression is determined
 604    from the first operand.  AND, OR, and XOR always compute the second
 605    operand whether its value is needed or not (for side effects).  */
 606 DEFTREECODE (TRUTH_ANDIF_EXPR, "truth_andif_expr", "e", 2)
 607 DEFTREECODE (TRUTH_ORIF_EXPR, "truth_orif_expr", "e", 2)
 608 DEFTREECODE (TRUTH_AND_EXPR, "truth_and_expr", "e", 2)
 609 DEFTREECODE (TRUTH_OR_EXPR, "truth_or_expr", "e", 2)
 610 DEFTREECODE (TRUTH_XOR_EXPR, "truth_xor_expr", "e", 2)
 611 DEFTREECODE (TRUTH_NOT_EXPR, "truth_not_expr", "e", 1)
 612
 613 /* Relational operators.
 614    `EQ_EXPR' and `NE_EXPR' are allowed for any types.
 615    The others are allowed only for integer (or pointer or enumeral)
 616    or real types.
 617    In all cases the operands will have the same type,
 618    and the value is always the type used by the language for booleans.  */
 619 DEFTREECODE (LT_EXPR, "lt_expr", "<", 2)
 620 DEFTREECODE (LE_EXPR, "le_expr", "<", 2)
 621 DEFTREECODE (GT_EXPR, "gt_expr", "<", 2)
 622 DEFTREECODE (GE_EXPR, "ge_expr", "<", 2)
 623 DEFTREECODE (EQ_EXPR, "eq_expr", "<", 2)
 624 DEFTREECODE (NE_EXPR, "ne_expr", "<", 2)
 625
 626 /* Operations for Pascal sets.  Not used now.  */
 627 DEFTREECODE (IN_EXPR, "in_expr", "2", 2)
 628 DEFTREECODE (SET_LE_EXPR, "set_le_expr", "<", 2)
 629 DEFTREECODE (CARD_EXPR, "card_expr", "1", 1)
 630 DEFTREECODE (RANGE_EXPR, "range_expr", "2", 2)
 631
 632 /* Represents a conversion of type of a value.
 633    All conversions, including implicit ones, must be
 634    represented by CONVERT_EXPR or NOP_EXPR nodes.  */
 635 DEFTREECODE (CONVERT_EXPR, "convert_expr", "1", 1)
 636
 637 /* Represents a conversion expected to require no code to be generated.  */
 638 DEFTREECODE (NOP_EXPR, "nop_expr", "1", 1)
 639
 640 /* Value is same as argument, but guaranteed not an lvalue.  */
 641 DEFTREECODE (NON_LVALUE_EXPR, "non_lvalue_expr", "1", 1)
 642
 643 /* Represents something we computed once and will use multiple times.
 644    First operand is that expression.  Second is the function decl
 645    in which the SAVE_EXPR was created.  The third operand is the RTL,
 646    nonzero only after the expression has been computed.  */
 647 DEFTREECODE (SAVE_EXPR, "save_expr", "e", 3)
 648
 649 /* For a UNSAVE_EXPR, operand 0 is the value to unsave.  By unsave, we
 650    mean that all _EXPRs such as TARGET_EXPRs, SAVE_EXPRs,
 651    CALL_EXPRs and RTL_EXPRs, that are protected
 652    from being evaluated more than once should be reset so that a new
 653    expand_expr call of this expr will cause those to be re-evaluated.
 654    This is useful when we want to reuse a tree in different places,
 655    but where we must re-expand.  */
 656 DEFTREECODE (UNSAVE_EXPR, "unsave_expr", "e", 1)
 657
 658 /* Represents something whose RTL has already been expanded
 659    as a sequence which should be emitted when this expression is expanded.
 660    The first operand is the RTL to emit.  It is the first of a chain of insns.
 661    The second is the RTL expression for the result.  */
 662 DEFTREECODE (RTL_EXPR, "rtl_expr", "e", 2)
 663
 664 /* & in C.  Value is the address at which the operand's value resides.
 665    Operand may have any mode.  Result mode is Pmode.  */
 666 DEFTREECODE (ADDR_EXPR, "addr_expr", "e", 1)
 667
 668 /* Non-lvalue reference or pointer to an object.  */
 669 DEFTREECODE (REFERENCE_EXPR, "reference_expr", "e", 1)
 670
 671 /* Operand is a function constant; result is a function variable value
 672    of typeEPmode.  Used only for languages that need static chains.  */
 673 DEFTREECODE (ENTRY_VALUE_EXPR, "entry_value_expr", "e", 1)
 674
 675 /* Given two real or integer operands of the same type,
 676    returns a complex value of the corresponding complex type.  */
 677 DEFTREECODE (COMPLEX_EXPR, "complex_expr", "2", 2)
 678
 679 /* Complex conjugate of operand.  Used only on complex types.  */
 680 DEFTREECODE (CONJ_EXPR, "conj_expr", "1", 1)
 681
 682 /* Used only on an operand of complex type, these return
 683    a value of the corresponding component type.  */
 684 DEFTREECODE (REALPART_EXPR, "realpart_expr", "1", 1)
 685 DEFTREECODE (IMAGPART_EXPR, "imagpart_expr", "1", 1)
 686
 687 /* Nodes for ++ and -- in C.
 688    The second arg is how much to increment or decrement by.
 689    For a pointer, it would be the size of the object pointed to.  */
 690 DEFTREECODE (PREDECREMENT_EXPR, "predecrement_expr", "e", 2)
 691 DEFTREECODE (PREINCREMENT_EXPR, "preincrement_expr", "e", 2)
 692 DEFTREECODE (POSTDECREMENT_EXPR, "postdecrement_expr", "e", 2)
 693 DEFTREECODE (POSTINCREMENT_EXPR, "postincrement_expr", "e", 2)
 694 \f
 695 /* These types of expressions have no useful value,
 696    and always have side effects.  */
 697
 698 /* A label definition, encapsulated as a statement.
 699    Operand 0 is the LABEL_DECL node for the label that appears here.
 700    The type should be void and the value should be ignored.  */
 701 DEFTREECODE (LABEL_EXPR, "label_expr", "s", 1)
 702
 703 /* GOTO.  Operand 0 is a LABEL_DECL node.
 704    The type should be void and the value should be ignored.  */
 705 DEFTREECODE (GOTO_EXPR, "goto_expr", "s", 1)
 706
 707 /* RETURN.  Evaluates operand 0, then returns from the current function.
 708    Presumably that operand is an assignment that stores into the
 709    RESULT_DECL that hold the value to be returned.
 710    The operand may be null.
 711    The type should be void and the value should be ignored.  */
 712 DEFTREECODE (RETURN_EXPR, "return_expr", "s", 1)
 713
 714 /* Exit the inner most loop conditionally.  Operand 0 is the condition.
 715    The type should be void and the value should be ignored.  */
 716 DEFTREECODE (EXIT_EXPR, "exit_expr", "s", 1)
 717
 718 /* A loop.  Operand 0 is the body of the loop.
 719    It must contain an EXIT_EXPR or is an infinite loop.
 720    The type should be void and the value should be ignored.  */
 721 DEFTREECODE (LOOP_EXPR, "loop_expr", "s", 1)
 722
 723 /*
 724 Local variables:
 725 mode:c
 726 End:
 727 */