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.
5 This file is part of GNU CC.
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)
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.
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. */
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. */
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. */
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
44 No fields in these nodes are used except the TREE_CODE. */
45 DEFTREECODE (ERROR_MARK, "error_mark", 'x', 0)
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)
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)
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)
65 /* These nodes contain an array of tree nodes. */
66 DEFTREECODE (TREE_VEC, "tree_vec", 'x', 2)
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)
88 /* Each data type is represented by a tree node whose code is one of
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;
125 DEFTREECODE (VOID_TYPE, "void_type", 't', 0) /* The void type in C */
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)
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)
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)
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)
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)
162 /* CHAR in Pascal; not used in C.
163 No special fields needed. */
164 DEFTREECODE (CHAR_TYPE, "char_type", 't', 0)
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)
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)
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)
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)
187 /* Used for Pascal; details not determined right now. */
188 DEFTREECODE (FILE_TYPE, "file_type", 't', 0)
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)
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)
209 /* Struct in C, or record in Pascal. */
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)
219 /* Union in C. Like a struct, except that the offsets of the fields
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 */
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
229 DEFTREECODE (QUAL_UNION_TYPE, "qual_union_type", 't', 0)
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)
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)
247 /* First, the constants. */
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)
256 /* Contents are in TREE_REAL_CST field. Also there is TREE_CST_RTL. */
257 DEFTREECODE (REAL_CST, "real_cst", 'c', 3)
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)
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)
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)
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.
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.
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.
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.
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
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.
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.
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
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)
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)
338 /* References to storage. */
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)
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)
354 /* C unary `*' or Pascal `^'. One operand, an expression for a pointer. */
355 DEFTREECODE (INDIRECT_REF, "indirect_ref", 'r', 1)
357 /* Pascal `^` on a file. One operand, an expression for the file. */
358 DEFTREECODE (BUFFER_REF, "buffer_ref", 'r', 1)
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)
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.
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.)
379 For RECORD_TYPE, UNION_TYPE, or QUAL_UNION_TYPE:
380 The TREE_PURPOSE of each node is a FIELD_DECL.
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)
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. */
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)
398 /* Assignment expression. Operand 0 is the what to set; 1, the new value. */
399 DEFTREECODE (MODIFY_EXPR, "modify_expr", 'e', 2)
401 /* Initialization expression. Operand 0 is the variable to initialize;
402 Operand 1 is the initializer. */
403 DEFTREECODE (INIT_EXPR, "init_expr", 'e', 2)
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)
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)
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.
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.
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.
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)
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)
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)
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.
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)
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.
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.
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)
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.
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.
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).
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.
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.
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. */
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)
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
530 DEFTREECODE (WITH_RECORD_EXPR, "with_record_expr", 'e', 2)
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)
537 /* Division for integer result that rounds the quotient toward zero. */
538 DEFTREECODE (TRUNC_DIV_EXPR, "trunc_div_expr", '2', 2)
540 /* Division for integer result that rounds the quotient toward infinity. */
541 DEFTREECODE (CEIL_DIV_EXPR, "ceil_div_expr", '2', 2)
543 /* Division for integer result that rounds toward minus infinity. */
544 DEFTREECODE (FLOOR_DIV_EXPR, "floor_div_expr", '2', 2)
546 /* Division for integer result that rounds toward nearest integer. */
547 DEFTREECODE (ROUND_DIV_EXPR, "round_div_expr", '2', 2)
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)
555 /* Division for real result. */
556 DEFTREECODE (RDIV_EXPR, "rdiv_expr", '2', 2)
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)
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)
572 /* Conversion of an integer to a real. */
573 DEFTREECODE (FLOAT_EXPR, "float_expr", '1', 1)
575 /* Exponentiation. Operands may have any types;
576 constraints on value type are not known yet. */
577 DEFTREECODE (EXPON_EXPR, "expon_expr", '2', 2)
579 /* Unary negation. */
580 DEFTREECODE (NEGATE_EXPR, "negate_expr", '1', 1)
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)
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)
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)
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)
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)
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)
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)
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)
640 /* Represents a conversion expected to require no code to be generated. */
641 DEFTREECODE (NOP_EXPR, "nop_expr", '1', 1)
643 /* Value is same as argument, but guaranteed not an lvalue. */
644 DEFTREECODE (NON_LVALUE_EXPR, "non_lvalue_expr", '1', 1)
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)
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)
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)
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)
671 /* Non-lvalue reference or pointer to an object. */
672 DEFTREECODE (REFERENCE_EXPR, "reference_expr", 'e', 1)
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)
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)
682 /* Complex conjugate of operand. Used only on complex types. */
683 DEFTREECODE (CONJ_EXPR, "conj_expr", '1', 1)
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)
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)
698 /* Evaluate operand 1. If and only if an exception is thrown during
699 the evaluation of operand 1, evaluate operand 2.
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)
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)
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)
716 /* These types of expressions have no useful value,
717 and always have side effects. */
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)
724 /* GOTO. Operand 0 is a LABEL_DECL node or an expression.
725 The type should be void and the value should be ignored. */
726 DEFTREECODE (GOTO_EXPR, "goto_expr", 's', 1)
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)
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)
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)
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)
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
752 DEFTREECODE (EXIT_BLOCK_EXPR, "exit_block_expr", 'e', 2)
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)
761 /* Switch expression.
762 Operand 0 is the expression used to perform the branch,
763 Operand 1 contains the case values. The way they're organized is
764 front-end implementation defined. */
765 DEFTREECODE (SWITCH_EXPR, "switch_expr", 'e', 2)
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