1 /* Functions to analyze and validate GIMPLE trees.
2 Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007
3 Free Software Foundation, Inc.
4 Contributed by Diego Novillo <dnovillo@redhat.com>
5 Rewritten by Jason Merrill <jason@redhat.com>
7 This file is part of GCC.
9 GCC is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 3, or (at your option)
14 GCC is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with GCC; see the file COPYING3. If not see
21 <http://www.gnu.org/licenses/>. */
25 #include "coretypes.h"
29 #include "tree-gimple.h"
30 #include "tree-flow.h"
36 /* For the definitive definition of GIMPLE, see doc/tree-ssa.texi. */
38 /* Validation of GIMPLE expressions. */
40 /* Return true if T is a GIMPLE RHS for an assignment to a temporary. */
43 is_gimple_formal_tmp_rhs (tree t)
45 enum tree_code code = TREE_CODE (t);
47 switch (TREE_CODE_CLASS (code))
83 return is_gimple_lvalue (t) || is_gimple_val (t);
86 /* Returns true iff T is a valid RHS for an assignment to a renamed
87 user -- or front-end generated artificial -- variable. */
90 is_gimple_reg_rhs (tree t)
92 /* If the RHS of the GIMPLE_MODIFY_STMT may throw or make a nonlocal goto
93 and the LHS is a user variable, then we need to introduce a formal
94 temporary. This way the optimizers can determine that the user
95 variable is only modified if evaluation of the RHS does not throw.
97 Don't force a temp of a non-renamable type; the copy could be
98 arbitrarily expensive. Instead we will generate a VDEF for
101 if (is_gimple_reg_type (TREE_TYPE (t))
102 && ((TREE_CODE (t) == CALL_EXPR && TREE_SIDE_EFFECTS (t))
103 || tree_could_throw_p (t)))
106 return is_gimple_formal_tmp_rhs (t);
109 /* Returns true iff T is a valid RHS for an assignment to an un-renamed
110 LHS, or for a call argument. */
113 is_gimple_mem_rhs (tree t)
115 /* If we're dealing with a renamable type, either source or dest must be
116 a renamed variable. Also force a temporary if the type doesn't need
117 to be stored in memory, since it's cheap and prevents erroneous
118 tailcalls (PR 17526). */
119 if (is_gimple_reg_type (TREE_TYPE (t))
120 || (TYPE_MODE (TREE_TYPE (t)) != BLKmode
121 && (TREE_CODE (t) != CALL_EXPR
122 || ! aggregate_value_p (t, t))))
123 return is_gimple_val (t);
125 return is_gimple_formal_tmp_rhs (t);
128 /* Returns the appropriate RHS predicate for this LHS. */
131 rhs_predicate_for (tree lhs)
133 if (is_gimple_formal_tmp_var (lhs))
134 return is_gimple_formal_tmp_rhs;
135 else if (is_gimple_reg (lhs))
136 return is_gimple_reg_rhs;
138 return is_gimple_mem_rhs;
141 /* Return true if T is a valid LHS for a GIMPLE assignment expression. */
144 is_gimple_lvalue (tree t)
146 return (is_gimple_addressable (t)
147 || TREE_CODE (t) == WITH_SIZE_EXPR
148 /* These are complex lvalues, but don't have addresses, so they
150 || TREE_CODE (t) == BIT_FIELD_REF);
153 /* Return true if T is a GIMPLE condition. */
156 is_gimple_condexpr (tree t)
158 return (is_gimple_val (t) || COMPARISON_CLASS_P (t));
161 /* Return true if T is something whose address can be taken. */
164 is_gimple_addressable (tree t)
166 return (is_gimple_id (t) || handled_component_p (t)
167 || INDIRECT_REF_P (t));
170 /* Return true if T is a valid gimple constant. */
173 is_gimple_constant (const_tree t)
175 switch (TREE_CODE (t))
185 /* Vector constant constructors are gimple invariant. */
187 if (TREE_TYPE (t) && TREE_CODE (TREE_TYPE (t)) == VECTOR_TYPE)
188 return TREE_CONSTANT (t);
197 /* Return true if T is a gimple address. */
200 is_gimple_address (const_tree t)
204 if (TREE_CODE (t) != ADDR_EXPR)
207 op = TREE_OPERAND (t, 0);
208 while (handled_component_p (op))
210 if ((TREE_CODE (op) == ARRAY_REF
211 || TREE_CODE (op) == ARRAY_RANGE_REF)
212 && !is_gimple_val (TREE_OPERAND (op, 1)))
215 op = TREE_OPERAND (op, 0);
218 if (CONSTANT_CLASS_P (op) || INDIRECT_REF_P (op))
221 switch (TREE_CODE (op))
236 /* Return true if T is a gimple invariant address. */
239 is_gimple_invariant_address (const_tree t)
243 if (TREE_CODE (t) != ADDR_EXPR)
246 op = TREE_OPERAND (t, 0);
247 while (handled_component_p (op))
249 switch (TREE_CODE (op))
252 case ARRAY_RANGE_REF:
253 if (!is_gimple_constant (TREE_OPERAND (op, 1))
254 || TREE_OPERAND (op, 2) != NULL_TREE
255 || TREE_OPERAND (op, 3) != NULL_TREE)
260 if (TREE_OPERAND (op, 2) != NULL_TREE)
266 op = TREE_OPERAND (op, 0);
269 return CONSTANT_CLASS_P (op) || decl_address_invariant_p (op);
272 /* Return true if T is a GIMPLE minimal invariant. It's a restricted
273 form of function invariant. */
276 is_gimple_min_invariant (const_tree t)
278 if (TREE_CODE (t) == ADDR_EXPR)
279 return is_gimple_invariant_address (t);
281 return is_gimple_constant (t);
284 /* Return true if T looks like a valid GIMPLE statement. */
287 is_gimple_stmt (tree t)
289 const enum tree_code code = TREE_CODE (t);
294 /* The only valid NOP_EXPR is the empty statement. */
295 return IS_EMPTY_STMT (t);
299 /* These are only valid if they're void. */
300 return TREE_TYPE (t) == NULL || VOID_TYPE_P (TREE_TYPE (t));
306 case CASE_LABEL_EXPR:
308 case TRY_FINALLY_EXPR:
311 case CHANGE_DYNAMIC_TYPE_EXPR:
319 case OMP_SECTIONS_SWITCH:
327 case OMP_ATOMIC_LOAD:
328 case OMP_ATOMIC_STORE:
329 /* These are always void. */
333 case GIMPLE_MODIFY_STMT:
335 /* These are valid regardless of their type. */
343 /* Return true if T is a variable. */
346 is_gimple_variable (tree t)
348 return (TREE_CODE (t) == VAR_DECL
349 || TREE_CODE (t) == PARM_DECL
350 || TREE_CODE (t) == RESULT_DECL
351 || TREE_CODE (t) == SSA_NAME);
354 /* Return true if T is a GIMPLE identifier (something with an address). */
357 is_gimple_id (tree t)
359 return (is_gimple_variable (t)
360 || TREE_CODE (t) == FUNCTION_DECL
361 || TREE_CODE (t) == LABEL_DECL
362 || TREE_CODE (t) == CONST_DECL
363 /* Allow string constants, since they are addressable. */
364 || TREE_CODE (t) == STRING_CST);
367 /* Return true if TYPE is a suitable type for a scalar register variable. */
370 is_gimple_reg_type (tree type)
372 /* In addition to aggregate types, we also exclude complex types if not
373 optimizing because they can be subject to partial stores in GNU C by
374 means of the __real__ and __imag__ operators and we cannot promote
375 them to total stores (see gimplify_modify_expr_complex_part). */
376 return !(AGGREGATE_TYPE_P (type)
377 || (TREE_CODE (type) == COMPLEX_TYPE && !optimize));
381 /* Return true if T is a non-aggregate register variable. */
384 is_gimple_reg (tree t)
386 if (TREE_CODE (t) == SSA_NAME)
387 t = SSA_NAME_VAR (t);
392 if (!is_gimple_variable (t))
395 if (!is_gimple_reg_type (TREE_TYPE (t)))
398 /* A volatile decl is not acceptable because we can't reuse it as
399 needed. We need to copy it into a temp first. */
400 if (TREE_THIS_VOLATILE (t))
403 /* We define "registers" as things that can be renamed as needed,
404 which with our infrastructure does not apply to memory. */
405 if (needs_to_live_in_memory (t))
408 /* Hard register variables are an interesting case. For those that
409 are call-clobbered, we don't know where all the calls are, since
410 we don't (want to) take into account which operations will turn
411 into libcalls at the rtl level. For those that are call-saved,
412 we don't currently model the fact that calls may in fact change
413 global hard registers, nor do we examine ASM_CLOBBERS at the tree
414 level, and so miss variable changes that might imply. All around,
415 it seems safest to not do too much optimization with these at the
416 tree level at all. We'll have to rely on the rtl optimizers to
417 clean this up, as there we've got all the appropriate bits exposed. */
418 if (TREE_CODE (t) == VAR_DECL && DECL_HARD_REGISTER (t))
421 /* Complex and vector values must have been put into SSA-like form.
422 That is, no assignments to the individual components. */
423 if (TREE_CODE (TREE_TYPE (t)) == COMPLEX_TYPE
424 || TREE_CODE (TREE_TYPE (t)) == VECTOR_TYPE)
425 return DECL_GIMPLE_REG_P (t);
431 /* Returns true if T is a GIMPLE formal temporary variable. */
434 is_gimple_formal_tmp_var (tree t)
436 if (TREE_CODE (t) == SSA_NAME)
439 return TREE_CODE (t) == VAR_DECL && DECL_GIMPLE_FORMAL_TEMP_P (t);
442 /* Returns true if T is a GIMPLE formal temporary register variable. */
445 is_gimple_formal_tmp_reg (tree t)
447 /* The intent of this is to get hold of a value that won't change.
448 An SSA_NAME qualifies no matter if its of a user variable or not. */
449 if (TREE_CODE (t) == SSA_NAME)
452 /* We don't know the lifetime characteristics of user variables. */
453 if (!is_gimple_formal_tmp_var (t))
456 /* Finally, it must be capable of being placed in a register. */
457 return is_gimple_reg (t);
460 /* Return true if T is a GIMPLE variable whose address is not needed. */
463 is_gimple_non_addressable (tree t)
465 if (TREE_CODE (t) == SSA_NAME)
466 t = SSA_NAME_VAR (t);
468 return (is_gimple_variable (t) && ! needs_to_live_in_memory (t));
471 /* Return true if T is a GIMPLE rvalue, i.e. an identifier or a constant. */
474 is_gimple_val (tree t)
476 /* Make loads from volatiles and memory vars explicit. */
477 if (is_gimple_variable (t)
478 && is_gimple_reg_type (TREE_TYPE (t))
479 && !is_gimple_reg (t))
482 /* FIXME make these decls. That can happen only when we expose the
483 entire landing-pad construct at the tree level. */
484 if (TREE_CODE (t) == EXC_PTR_EXPR || TREE_CODE (t) == FILTER_EXPR)
487 return (is_gimple_variable (t) || is_gimple_min_invariant (t));
490 /* Similarly, but accept hard registers as inputs to asm statements. */
493 is_gimple_asm_val (tree t)
495 if (TREE_CODE (t) == VAR_DECL && DECL_HARD_REGISTER (t))
498 return is_gimple_val (t);
501 /* Return true if T is a GIMPLE minimal lvalue. */
504 is_gimple_min_lval (tree t)
506 return (is_gimple_id (t)
507 || TREE_CODE (t) == INDIRECT_REF);
510 /* Return true if T is a typecast operation. */
513 is_gimple_cast (tree t)
515 return (TREE_CODE (t) == NOP_EXPR
516 || TREE_CODE (t) == CONVERT_EXPR
517 || TREE_CODE (t) == FIX_TRUNC_EXPR);
520 /* Return true if T is a valid function operand of a CALL_EXPR. */
523 is_gimple_call_addr (tree t)
525 return (TREE_CODE (t) == OBJ_TYPE_REF
526 || is_gimple_val (t));
529 /* If T makes a function call, return the corresponding CALL_EXPR operand.
530 Otherwise, return NULL_TREE. */
533 get_call_expr_in (tree t)
535 /* FIXME tuples: delete the assertion below when conversion complete. */
536 gcc_assert (TREE_CODE (t) != MODIFY_EXPR);
537 if (TREE_CODE (t) == GIMPLE_MODIFY_STMT)
538 t = GIMPLE_STMT_OPERAND (t, 1);
539 if (TREE_CODE (t) == WITH_SIZE_EXPR)
540 t = TREE_OPERAND (t, 0);
541 if (TREE_CODE (t) == CALL_EXPR)
546 /* Given a memory reference expression T, return its base address.
547 The base address of a memory reference expression is the main
548 object being referenced. For instance, the base address for
549 'array[i].fld[j]' is 'array'. You can think of this as stripping
550 away the offset part from a memory address.
552 This function calls handled_component_p to strip away all the inner
553 parts of the memory reference until it reaches the base object. */
556 get_base_address (tree t)
558 while (handled_component_p (t))
559 t = TREE_OPERAND (t, 0);
562 || TREE_CODE (t) == STRING_CST
563 || TREE_CODE (t) == CONSTRUCTOR
564 || INDIRECT_REF_P (t))
571 recalculate_side_effects (tree t)
573 enum tree_code code = TREE_CODE (t);
574 int len = TREE_OPERAND_LENGTH (t);
577 switch (TREE_CODE_CLASS (code))
583 case GIMPLE_MODIFY_STMT:
585 case PREDECREMENT_EXPR:
586 case PREINCREMENT_EXPR:
587 case POSTDECREMENT_EXPR:
588 case POSTINCREMENT_EXPR:
589 /* All of these have side-effects, no matter what their
598 case tcc_comparison: /* a comparison expression */
599 case tcc_unary: /* a unary arithmetic expression */
600 case tcc_binary: /* a binary arithmetic expression */
601 case tcc_reference: /* a reference */
602 case tcc_vl_exp: /* a function call */
603 TREE_SIDE_EFFECTS (t) = TREE_THIS_VOLATILE (t);
604 for (i = 0; i < len; ++i)
606 tree op = TREE_OPERAND (t, i);
607 if (op && TREE_SIDE_EFFECTS (op))
608 TREE_SIDE_EFFECTS (t) = 1;
613 /* Can never be used with non-expressions. */
618 /* Canonicalize a tree T for use in a COND_EXPR as conditional. Returns
619 a canonicalized tree that is valid for a COND_EXPR or NULL_TREE, if
620 we failed to create one. */
623 canonicalize_cond_expr_cond (tree t)
625 /* For (bool)x use x != 0. */
626 if (TREE_CODE (t) == NOP_EXPR
627 && TREE_TYPE (t) == boolean_type_node)
629 tree top0 = TREE_OPERAND (t, 0);
630 t = build2 (NE_EXPR, TREE_TYPE (t),
631 top0, build_int_cst (TREE_TYPE (top0), 0));
633 /* For !x use x == 0. */
634 else if (TREE_CODE (t) == TRUTH_NOT_EXPR)
636 tree top0 = TREE_OPERAND (t, 0);
637 t = build2 (EQ_EXPR, TREE_TYPE (t),
638 top0, build_int_cst (TREE_TYPE (top0), 0));
640 /* For cmp ? 1 : 0 use cmp. */
641 else if (TREE_CODE (t) == COND_EXPR
642 && COMPARISON_CLASS_P (TREE_OPERAND (t, 0))
643 && integer_onep (TREE_OPERAND (t, 1))
644 && integer_zerop (TREE_OPERAND (t, 2)))
646 tree top0 = TREE_OPERAND (t, 0);
647 t = build2 (TREE_CODE (top0), TREE_TYPE (t),
648 TREE_OPERAND (top0, 0), TREE_OPERAND (top0, 1));
651 /* A valid conditional for a COND_EXPR is either a gimple value
652 or a comparison with two gimple value operands. */
653 if (is_gimple_val (t)
654 || (COMPARISON_CLASS_P (t)
655 && is_gimple_val (TREE_OPERAND (t, 0))
656 && is_gimple_val (TREE_OPERAND (t, 1))))