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 invariant address. */
200 is_gimple_invariant_address (const_tree t)
204 if (TREE_CODE (t) != ADDR_EXPR)
207 op = TREE_OPERAND (t, 0);
208 while (handled_component_p (op))
210 switch (TREE_CODE (op))
213 case ARRAY_RANGE_REF:
214 if (!is_gimple_constant (TREE_OPERAND (op, 1))
215 || TREE_OPERAND (op, 2) != NULL_TREE
216 || TREE_OPERAND (op, 3) != NULL_TREE)
221 if (TREE_OPERAND (op, 2) != NULL_TREE)
227 op = TREE_OPERAND (op, 0);
230 if (CONSTANT_CLASS_P (op))
233 if (INDIRECT_REF_P (op))
236 switch (TREE_CODE (op))
245 if (((TREE_STATIC (op) || DECL_EXTERNAL (op))
246 && ! DECL_DLLIMPORT_P (op))
247 || DECL_THREAD_LOCAL_P (op)
248 || DECL_CONTEXT (op) == current_function_decl
249 || decl_function_context (op) == current_function_decl)
254 if ((TREE_STATIC (op) || DECL_EXTERNAL (op))
255 || decl_function_context (op) == current_function_decl)
266 /* Return true if T is a GIMPLE minimal invariant. It's a restricted
267 form of function invariant. */
270 is_gimple_min_invariant (const_tree t)
272 if (TREE_CODE (t) == ADDR_EXPR)
273 return is_gimple_invariant_address (t);
275 return is_gimple_constant (t);
278 /* Return true if T looks like a valid GIMPLE statement. */
281 is_gimple_stmt (tree t)
283 const enum tree_code code = TREE_CODE (t);
288 /* The only valid NOP_EXPR is the empty statement. */
289 return IS_EMPTY_STMT (t);
293 /* These are only valid if they're void. */
294 return TREE_TYPE (t) == NULL || VOID_TYPE_P (TREE_TYPE (t));
300 case CASE_LABEL_EXPR:
302 case TRY_FINALLY_EXPR:
305 case CHANGE_DYNAMIC_TYPE_EXPR:
313 case OMP_SECTIONS_SWITCH:
321 case OMP_ATOMIC_LOAD:
322 case OMP_ATOMIC_STORE:
323 /* These are always void. */
327 case GIMPLE_MODIFY_STMT:
328 /* These are valid regardless of their type. */
336 /* Return true if T is a variable. */
339 is_gimple_variable (tree t)
341 return (TREE_CODE (t) == VAR_DECL
342 || TREE_CODE (t) == PARM_DECL
343 || TREE_CODE (t) == RESULT_DECL
344 || TREE_CODE (t) == SSA_NAME);
347 /* Return true if T is a GIMPLE identifier (something with an address). */
350 is_gimple_id (tree t)
352 return (is_gimple_variable (t)
353 || TREE_CODE (t) == FUNCTION_DECL
354 || TREE_CODE (t) == LABEL_DECL
355 || TREE_CODE (t) == CONST_DECL
356 /* Allow string constants, since they are addressable. */
357 || TREE_CODE (t) == STRING_CST);
360 /* Return true if TYPE is a suitable type for a scalar register variable. */
363 is_gimple_reg_type (tree type)
365 /* In addition to aggregate types, we also exclude complex types if not
366 optimizing because they can be subject to partial stores in GNU C by
367 means of the __real__ and __imag__ operators and we cannot promote
368 them to total stores (see gimplify_modify_expr_complex_part). */
369 return !(AGGREGATE_TYPE_P (type)
370 || (TREE_CODE (type) == COMPLEX_TYPE && !optimize));
374 /* Return true if T is a non-aggregate register variable. */
377 is_gimple_reg (tree t)
379 if (TREE_CODE (t) == SSA_NAME)
380 t = SSA_NAME_VAR (t);
385 if (!is_gimple_variable (t))
388 if (!is_gimple_reg_type (TREE_TYPE (t)))
391 /* A volatile decl is not acceptable because we can't reuse it as
392 needed. We need to copy it into a temp first. */
393 if (TREE_THIS_VOLATILE (t))
396 /* We define "registers" as things that can be renamed as needed,
397 which with our infrastructure does not apply to memory. */
398 if (needs_to_live_in_memory (t))
401 /* Hard register variables are an interesting case. For those that
402 are call-clobbered, we don't know where all the calls are, since
403 we don't (want to) take into account which operations will turn
404 into libcalls at the rtl level. For those that are call-saved,
405 we don't currently model the fact that calls may in fact change
406 global hard registers, nor do we examine ASM_CLOBBERS at the tree
407 level, and so miss variable changes that might imply. All around,
408 it seems safest to not do too much optimization with these at the
409 tree level at all. We'll have to rely on the rtl optimizers to
410 clean this up, as there we've got all the appropriate bits exposed. */
411 if (TREE_CODE (t) == VAR_DECL && DECL_HARD_REGISTER (t))
414 /* Complex and vector values must have been put into SSA-like form.
415 That is, no assignments to the individual components. */
416 if (TREE_CODE (TREE_TYPE (t)) == COMPLEX_TYPE
417 || TREE_CODE (TREE_TYPE (t)) == VECTOR_TYPE)
418 return DECL_GIMPLE_REG_P (t);
424 /* Returns true if T is a GIMPLE formal temporary variable. */
427 is_gimple_formal_tmp_var (tree t)
429 if (TREE_CODE (t) == SSA_NAME)
432 return TREE_CODE (t) == VAR_DECL && DECL_GIMPLE_FORMAL_TEMP_P (t);
435 /* Returns true if T is a GIMPLE formal temporary register variable. */
438 is_gimple_formal_tmp_reg (tree t)
440 /* The intent of this is to get hold of a value that won't change.
441 An SSA_NAME qualifies no matter if its of a user variable or not. */
442 if (TREE_CODE (t) == SSA_NAME)
445 /* We don't know the lifetime characteristics of user variables. */
446 if (!is_gimple_formal_tmp_var (t))
449 /* Finally, it must be capable of being placed in a register. */
450 return is_gimple_reg (t);
453 /* Return true if T is a GIMPLE variable whose address is not needed. */
456 is_gimple_non_addressable (tree t)
458 if (TREE_CODE (t) == SSA_NAME)
459 t = SSA_NAME_VAR (t);
461 return (is_gimple_variable (t) && ! needs_to_live_in_memory (t));
464 /* Return true if T is a GIMPLE rvalue, i.e. an identifier or a constant. */
467 is_gimple_val (tree t)
469 /* Make loads from volatiles and memory vars explicit. */
470 if (is_gimple_variable (t)
471 && is_gimple_reg_type (TREE_TYPE (t))
472 && !is_gimple_reg (t))
475 /* FIXME make these decls. That can happen only when we expose the
476 entire landing-pad construct at the tree level. */
477 if (TREE_CODE (t) == EXC_PTR_EXPR || TREE_CODE (t) == FILTER_EXPR)
480 return (is_gimple_variable (t) || is_gimple_min_invariant (t));
483 /* Similarly, but accept hard registers as inputs to asm statements. */
486 is_gimple_asm_val (tree t)
488 if (TREE_CODE (t) == VAR_DECL && DECL_HARD_REGISTER (t))
491 return is_gimple_val (t);
494 /* Return true if T is a GIMPLE minimal lvalue. */
497 is_gimple_min_lval (tree t)
499 return (is_gimple_id (t)
500 || TREE_CODE (t) == INDIRECT_REF);
503 /* Return true if T is a typecast operation. */
506 is_gimple_cast (tree t)
508 return (TREE_CODE (t) == NOP_EXPR
509 || TREE_CODE (t) == CONVERT_EXPR
510 || TREE_CODE (t) == FIX_TRUNC_EXPR);
513 /* Return true if T is a valid function operand of a CALL_EXPR. */
516 is_gimple_call_addr (tree t)
518 return (TREE_CODE (t) == OBJ_TYPE_REF
519 || is_gimple_val (t));
522 /* If T makes a function call, return the corresponding CALL_EXPR operand.
523 Otherwise, return NULL_TREE. */
526 get_call_expr_in (tree t)
528 /* FIXME tuples: delete the assertion below when conversion complete. */
529 gcc_assert (TREE_CODE (t) != MODIFY_EXPR);
530 if (TREE_CODE (t) == GIMPLE_MODIFY_STMT)
531 t = GIMPLE_STMT_OPERAND (t, 1);
532 if (TREE_CODE (t) == WITH_SIZE_EXPR)
533 t = TREE_OPERAND (t, 0);
534 if (TREE_CODE (t) == CALL_EXPR)
539 /* Given a memory reference expression T, return its base address.
540 The base address of a memory reference expression is the main
541 object being referenced. For instance, the base address for
542 'array[i].fld[j]' is 'array'. You can think of this as stripping
543 away the offset part from a memory address.
545 This function calls handled_component_p to strip away all the inner
546 parts of the memory reference until it reaches the base object. */
549 get_base_address (tree t)
551 while (handled_component_p (t))
552 t = TREE_OPERAND (t, 0);
555 || TREE_CODE (t) == STRING_CST
556 || TREE_CODE (t) == CONSTRUCTOR
557 || INDIRECT_REF_P (t))
564 recalculate_side_effects (tree t)
566 enum tree_code code = TREE_CODE (t);
567 int len = TREE_OPERAND_LENGTH (t);
570 switch (TREE_CODE_CLASS (code))
576 case GIMPLE_MODIFY_STMT:
578 case PREDECREMENT_EXPR:
579 case PREINCREMENT_EXPR:
580 case POSTDECREMENT_EXPR:
581 case POSTINCREMENT_EXPR:
582 /* All of these have side-effects, no matter what their
591 case tcc_comparison: /* a comparison expression */
592 case tcc_unary: /* a unary arithmetic expression */
593 case tcc_binary: /* a binary arithmetic expression */
594 case tcc_reference: /* a reference */
595 case tcc_vl_exp: /* a function call */
596 TREE_SIDE_EFFECTS (t) = TREE_THIS_VOLATILE (t);
597 for (i = 0; i < len; ++i)
599 tree op = TREE_OPERAND (t, i);
600 if (op && TREE_SIDE_EFFECTS (op))
601 TREE_SIDE_EFFECTS (t) = 1;
606 /* Can never be used with non-expressions. */
611 /* Canonicalize a tree T for use in a COND_EXPR as conditional. Returns
612 a canonicalized tree that is valid for a COND_EXPR or NULL_TREE, if
613 we failed to create one. */
616 canonicalize_cond_expr_cond (tree t)
618 /* For (bool)x use x != 0. */
619 if (TREE_CODE (t) == NOP_EXPR
620 && TREE_TYPE (t) == boolean_type_node)
622 tree top0 = TREE_OPERAND (t, 0);
623 t = build2 (NE_EXPR, TREE_TYPE (t),
624 top0, build_int_cst (TREE_TYPE (top0), 0));
626 /* For !x use x == 0. */
627 else if (TREE_CODE (t) == TRUTH_NOT_EXPR)
629 tree top0 = TREE_OPERAND (t, 0);
630 t = build2 (EQ_EXPR, TREE_TYPE (t),
631 top0, build_int_cst (TREE_TYPE (top0), 0));
633 /* For cmp ? 1 : 0 use cmp. */
634 else if (TREE_CODE (t) == COND_EXPR
635 && COMPARISON_CLASS_P (TREE_OPERAND (t, 0))
636 && integer_onep (TREE_OPERAND (t, 1))
637 && integer_zerop (TREE_OPERAND (t, 2)))
639 tree top0 = TREE_OPERAND (t, 0);
640 t = build2 (TREE_CODE (top0), TREE_TYPE (t),
641 TREE_OPERAND (top0, 0), TREE_OPERAND (top0, 1));
644 /* A valid conditional for a COND_EXPR is either a gimple value
645 or a comparison with two gimple value operands. */
646 if (is_gimple_val (t)
647 || (COMPARISON_CLASS_P (t)
648 && is_gimple_val (TREE_OPERAND (t, 0))
649 && is_gimple_val (TREE_OPERAND (t, 1))))