1 /* Functions to analyze and validate GIMPLE trees.
2 Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>
4 Rewritten by Jason Merrill <jason@redhat.com>
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2, or (at your option)
13 GCC is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING. If not, write to
20 the Free Software Foundation, 59 Temple Place - Suite 330,
21 Boston, MA 02111-1307, USA. */
25 #include "coretypes.h"
29 #include "tree-gimple.h"
30 #include "tree-flow.h"
36 /* GCC GIMPLE structure
38 Inspired by the SIMPLE C grammar at
40 http://www-acaps.cs.mcgill.ca/info/McCAT/McCAT.html
42 function : FUNCTION_DECL
43 DECL_SAVED_TREE -> compound-stmt
45 compound-stmt: STATEMENT_LIST
60 BIND_EXPR_VARS -> chain of DECLs
61 BIND_EXPR_BLOCK -> BLOCK
62 BIND_EXPR_BODY -> compound-stmt
69 switch-stmt : SWITCH_EXPR
72 op2 -> TREE_VEC of CASE_LABEL_EXPRs
73 The CASE_LABEL_EXPRs are sorted by CASE_LOW,
77 op0 -> LABEL_DECL | val
79 return-stmt : RETURN_EXPR
90 label-stmt : LABEL_EXPR
93 try-stmt : TRY_CATCH_EXPR
104 catch-seq : STATEMENT_LIST
105 members -> CATCH_EXPR
107 modify-stmt : MODIFY_EXPR
111 call-stmt : CALL_EXPR
112 op0 -> val | OBJ_TYPE_REF
115 call-arg-list: TREE_LIST
121 addressable : addr-expr-arg
124 with-size-arg: addressable
127 indirectref : INDIRECT_REF
139 bitfieldref : BIT_FIELD_REF
144 compref : inner-compref
150 inner-compref: min-lval
191 static inline bool is_gimple_id (tree);
193 /* Validation of GIMPLE expressions. */
195 /* Return true if T is a GIMPLE RHS for an assignment to a temporary. */
198 is_gimple_formal_tmp_rhs (tree t)
200 enum tree_code code = TREE_CODE (t);
202 switch (TREE_CODE_CLASS (code))
235 return is_gimple_lvalue (t) || is_gimple_val (t);
238 /* Returns true iff T is a valid RHS for an assignment to a renamed
239 user -- or front-end generated artificial -- variable. */
242 is_gimple_reg_rhs (tree t)
244 /* If the RHS of the MODIFY_EXPR may throw or make a nonlocal goto
245 and the LHS is a user variable, then we need to introduce a formal
246 temporary. This way the optimizers can determine that the user
247 variable is only modified if evaluation of the RHS does not throw.
249 Don't force a temp of a non-renamable type; the copy could be
250 arbitrarily expensive. Instead we will generate a V_MAY_DEF for
253 if (is_gimple_reg_type (TREE_TYPE (t))
254 && ((TREE_CODE (t) == CALL_EXPR && TREE_SIDE_EFFECTS (t))
255 || tree_could_throw_p (t)))
258 return is_gimple_formal_tmp_rhs (t);
261 /* Returns true iff T is a valid RHS for an assignment to an un-renamed
262 LHS, or for a call argument. */
265 is_gimple_mem_rhs (tree t)
267 /* If we're dealing with a renamable type, either source or dest
268 must be a renamed variable. */
269 if (is_gimple_reg_type (TREE_TYPE (t)))
270 return is_gimple_val (t);
272 return is_gimple_formal_tmp_rhs (t);
275 /* Returns the appropriate RHS predicate for this LHS. */
278 rhs_predicate_for (tree lhs)
280 if (is_gimple_formal_tmp_var (lhs))
281 return is_gimple_formal_tmp_rhs;
282 else if (is_gimple_reg (lhs))
283 return is_gimple_reg_rhs;
285 return is_gimple_mem_rhs;
288 /* Returns true if T is a valid CONSTRUCTOR component in GIMPLE, either
289 a val or another CONSTRUCTOR. */
292 is_gimple_constructor_elt (tree t)
294 return (is_gimple_val (t)
295 || TREE_CODE (t) == CONSTRUCTOR);
298 /* Return true if T is a valid LHS for a GIMPLE assignment expression. */
301 is_gimple_lvalue (tree t)
303 return (is_gimple_addressable (t)
304 || TREE_CODE (t) == WITH_SIZE_EXPR
305 /* These are complex lvalues, but don't have addresses, so they
307 || TREE_CODE (t) == BIT_FIELD_REF);
310 /* Return true if T is a GIMPLE condition. */
313 is_gimple_condexpr (tree t)
315 return (is_gimple_val (t) || COMPARISON_CLASS_P (t));
318 /* Return true if T is something whose address can be taken. */
321 is_gimple_addressable (tree t)
323 return (is_gimple_id (t) || handled_component_p (t)
324 || TREE_CODE (t) == REALPART_EXPR
325 || TREE_CODE (t) == IMAGPART_EXPR
326 || TREE_CODE (t) == INDIRECT_REF
327 || TREE_CODE (t) == ALIGN_INDIRECT_REF
328 || TREE_CODE (t) == MISALIGNED_INDIRECT_REF);
331 /* Return true if T is function invariant. Or rather a restricted
332 form of function invariant. */
335 is_gimple_min_invariant (tree t)
337 switch (TREE_CODE (t))
340 return TREE_INVARIANT (t);
347 return !TREE_OVERFLOW (t);
354 /* Return true if T looks like a valid GIMPLE statement. */
357 is_gimple_stmt (tree t)
359 enum tree_code code = TREE_CODE (t);
361 if (IS_EMPTY_STMT (t))
368 /* These are only valid if they're void. */
369 return TREE_TYPE (t) == NULL || VOID_TYPE_P (TREE_TYPE (t));
375 case CASE_LABEL_EXPR:
377 case TRY_FINALLY_EXPR:
384 /* These are always void. */
389 /* These are valid regardless of their type. */
397 /* Return true if T is a variable. */
400 is_gimple_variable (tree t)
402 return (TREE_CODE (t) == VAR_DECL
403 || TREE_CODE (t) == PARM_DECL
404 || TREE_CODE (t) == RESULT_DECL
405 || TREE_CODE (t) == SSA_NAME);
408 /* Return true if T is a GIMPLE identifier (something with an address). */
411 is_gimple_id (tree t)
413 return (is_gimple_variable (t)
414 || TREE_CODE (t) == FUNCTION_DECL
415 || TREE_CODE (t) == LABEL_DECL
416 || TREE_CODE (t) == CONST_DECL
417 /* Allow string constants, since they are addressable. */
418 || TREE_CODE (t) == STRING_CST);
421 /* Return true if TYPE is a suitable type for a scalar register variable. */
424 is_gimple_reg_type (tree type)
426 return (!AGGREGATE_TYPE_P (type)
427 && TREE_CODE (type) != COMPLEX_TYPE);
431 /* Return true if T is a scalar register variable. */
434 is_gimple_reg (tree t)
436 if (TREE_CODE (t) == SSA_NAME)
437 t = SSA_NAME_VAR (t);
439 return (is_gimple_variable (t)
440 && is_gimple_reg_type (TREE_TYPE (t))
441 /* A volatile decl is not acceptable because we can't reuse it as
442 needed. We need to copy it into a temp first. */
443 && ! TREE_THIS_VOLATILE (t)
444 && ! needs_to_live_in_memory (t));
447 /* Returns true if T is a GIMPLE formal temporary variable. */
450 is_gimple_formal_tmp_var (tree t)
452 if (TREE_CODE (t) == SSA_NAME)
455 return TREE_CODE (t) == VAR_DECL && DECL_GIMPLE_FORMAL_TEMP_P (t);
458 /* Returns true if T is a GIMPLE formal temporary register variable. */
461 is_gimple_formal_tmp_reg (tree t)
463 /* The intent of this is to get hold of a value that won't change.
464 An SSA_NAME qualifies no matter if its of a user variable or not. */
465 if (TREE_CODE (t) == SSA_NAME)
468 /* We don't know the lifetime characteristics of user variables. */
469 if (!is_gimple_formal_tmp_var (t))
472 /* Finally, it must be capable of being placed in a register. */
473 return is_gimple_reg (t);
476 /* Return true if T is a GIMPLE variable whose address is not needed. */
479 is_gimple_non_addressable (tree t)
481 if (TREE_CODE (t) == SSA_NAME)
482 t = SSA_NAME_VAR (t);
484 return (is_gimple_variable (t) && ! needs_to_live_in_memory (t));
487 /* Return true if T is a GIMPLE rvalue, i.e. an identifier or a constant. */
490 is_gimple_val (tree t)
492 /* Make loads from volatiles and memory vars explicit. */
493 if (is_gimple_variable (t)
494 && is_gimple_reg_type (TREE_TYPE (t))
495 && !is_gimple_reg (t))
498 /* FIXME make these decls. That can happen only when we expose the
499 entire landing-pad construct at the tree level. */
500 if (TREE_CODE (t) == EXC_PTR_EXPR || TREE_CODE (t) == FILTER_EXPR)
503 return (is_gimple_variable (t) || is_gimple_min_invariant (t));
507 /* Return true if T is a GIMPLE minimal lvalue. */
510 is_gimple_min_lval (tree t)
512 return (is_gimple_id (t)
513 || TREE_CODE (t) == INDIRECT_REF);
516 /* Return true if T is a typecast operation. */
519 is_gimple_cast (tree t)
521 return (TREE_CODE (t) == NOP_EXPR
522 || TREE_CODE (t) == CONVERT_EXPR
523 || TREE_CODE (t) == FIX_TRUNC_EXPR
524 || TREE_CODE (t) == FIX_CEIL_EXPR
525 || TREE_CODE (t) == FIX_FLOOR_EXPR
526 || TREE_CODE (t) == FIX_ROUND_EXPR);
529 /* Return true if T is a valid op0 of a CALL_EXPR. */
532 is_gimple_call_addr (tree t)
534 return (TREE_CODE (t) == OBJ_TYPE_REF
535 || is_gimple_val (t));
538 /* If T makes a function call, return the corresponding CALL_EXPR operand.
539 Otherwise, return NULL_TREE. */
542 get_call_expr_in (tree t)
544 if (TREE_CODE (t) == MODIFY_EXPR)
545 t = TREE_OPERAND (t, 1);
546 if (TREE_CODE (t) == WITH_SIZE_EXPR)
547 t = TREE_OPERAND (t, 0);
548 if (TREE_CODE (t) == CALL_EXPR)
553 /* Given a memory reference expression, return the base address. Note that,
554 in contrast with get_base_var, this will not recurse inside INDIRECT_REF
555 expressions. Therefore, given the reference PTR->FIELD, this function
556 will return *PTR. Whereas get_base_var would've returned PTR. */
559 get_base_address (tree t)
561 while (TREE_CODE (t) == REALPART_EXPR || TREE_CODE (t) == IMAGPART_EXPR
562 || handled_component_p (t))
563 t = TREE_OPERAND (t, 0);
566 || TREE_CODE (t) == STRING_CST
567 || TREE_CODE (t) == CONSTRUCTOR
568 || TREE_CODE (t) == MISALIGNED_INDIRECT_REF
569 || TREE_CODE (t) == ALIGN_INDIRECT_REF
570 || TREE_CODE (t) == INDIRECT_REF)
577 recalculate_side_effects (tree t)
579 enum tree_code code = TREE_CODE (t);
580 int fro = first_rtl_op (code);
583 switch (TREE_CODE_CLASS (code))
591 case PREDECREMENT_EXPR:
592 case PREINCREMENT_EXPR:
593 case POSTDECREMENT_EXPR:
594 case POSTINCREMENT_EXPR:
595 /* All of these have side-effects, no matter what their
604 case tcc_comparison: /* a comparison expression */
605 case tcc_unary: /* a unary arithmetic expression */
606 case tcc_binary: /* a binary arithmetic expression */
607 case tcc_reference: /* a reference */
608 TREE_SIDE_EFFECTS (t) = TREE_THIS_VOLATILE (t);
609 for (i = 0; i < fro; ++i)
611 tree op = TREE_OPERAND (t, i);
612 if (op && TREE_SIDE_EFFECTS (op))
613 TREE_SIDE_EFFECTS (t) = 1;
618 /* Can never be used with non-expressions. */