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. */
117 if (is_gimple_reg_type (TREE_TYPE (t)))
118 return is_gimple_val (t);
120 return is_gimple_formal_tmp_rhs (t);
123 /* Returns the appropriate RHS predicate for this LHS. */
126 rhs_predicate_for (tree lhs)
128 if (is_gimple_formal_tmp_var (lhs))
129 return is_gimple_formal_tmp_rhs;
130 else if (is_gimple_reg (lhs))
131 return is_gimple_reg_rhs;
133 return is_gimple_mem_rhs;
136 /* Return true if T is a valid LHS for a GIMPLE assignment expression. */
139 is_gimple_lvalue (tree t)
141 return (is_gimple_addressable (t)
142 || TREE_CODE (t) == WITH_SIZE_EXPR
143 /* These are complex lvalues, but don't have addresses, so they
145 || TREE_CODE (t) == BIT_FIELD_REF);
148 /* Return true if T is a GIMPLE condition. */
151 is_gimple_condexpr (tree t)
153 return (is_gimple_val (t) || (COMPARISON_CLASS_P (t)
154 && !tree_could_trap_p (t)
155 && is_gimple_val (TREE_OPERAND (t, 0))
156 && is_gimple_val (TREE_OPERAND (t, 1))));
159 /* Return true if T is something whose address can be taken. */
162 is_gimple_addressable (tree t)
164 return (is_gimple_id (t) || handled_component_p (t)
165 || INDIRECT_REF_P (t));
168 /* Return true if T is a valid gimple constant. */
171 is_gimple_constant (const_tree t)
173 switch (TREE_CODE (t))
183 /* Vector constant constructors are gimple invariant. */
185 if (TREE_TYPE (t) && TREE_CODE (TREE_TYPE (t)) == VECTOR_TYPE)
186 return TREE_CONSTANT (t);
195 /* Return true if T is a gimple address. */
198 is_gimple_address (const_tree t)
202 if (TREE_CODE (t) != ADDR_EXPR)
205 op = TREE_OPERAND (t, 0);
206 while (handled_component_p (op))
208 if ((TREE_CODE (op) == ARRAY_REF
209 || TREE_CODE (op) == ARRAY_RANGE_REF)
210 && !is_gimple_val (TREE_OPERAND (op, 1)))
213 op = TREE_OPERAND (op, 0);
216 if (CONSTANT_CLASS_P (op) || INDIRECT_REF_P (op))
219 switch (TREE_CODE (op))
234 /* Return true if T is a gimple invariant address. */
237 is_gimple_invariant_address (const_tree t)
241 if (TREE_CODE (t) != ADDR_EXPR)
244 op = TREE_OPERAND (t, 0);
245 while (handled_component_p (op))
247 switch (TREE_CODE (op))
250 case ARRAY_RANGE_REF:
251 if (!is_gimple_constant (TREE_OPERAND (op, 1))
252 || TREE_OPERAND (op, 2) != NULL_TREE
253 || TREE_OPERAND (op, 3) != NULL_TREE)
258 if (TREE_OPERAND (op, 2) != NULL_TREE)
264 op = TREE_OPERAND (op, 0);
267 return CONSTANT_CLASS_P (op) || decl_address_invariant_p (op);
270 /* Return true if T is a GIMPLE minimal invariant. It's a restricted
271 form of function invariant. */
274 is_gimple_min_invariant (const_tree t)
276 if (TREE_CODE (t) == ADDR_EXPR)
277 return is_gimple_invariant_address (t);
279 return is_gimple_constant (t);
282 /* Return true if T looks like a valid GIMPLE statement. */
285 is_gimple_stmt (tree t)
287 const enum tree_code code = TREE_CODE (t);
292 /* The only valid NOP_EXPR is the empty statement. */
293 return IS_EMPTY_STMT (t);
297 /* These are only valid if they're void. */
298 return TREE_TYPE (t) == NULL || VOID_TYPE_P (TREE_TYPE (t));
304 case CASE_LABEL_EXPR:
306 case TRY_FINALLY_EXPR:
309 case CHANGE_DYNAMIC_TYPE_EXPR:
317 case OMP_SECTIONS_SWITCH:
325 case OMP_ATOMIC_LOAD:
326 case OMP_ATOMIC_STORE:
327 /* These are always void. */
331 case GIMPLE_MODIFY_STMT:
333 /* These are valid regardless of their type. */
341 /* Return true if T is a variable. */
344 is_gimple_variable (tree t)
346 return (TREE_CODE (t) == VAR_DECL
347 || TREE_CODE (t) == PARM_DECL
348 || TREE_CODE (t) == RESULT_DECL
349 || TREE_CODE (t) == SSA_NAME);
352 /* Return true if T is a GIMPLE identifier (something with an address). */
355 is_gimple_id (tree t)
357 return (is_gimple_variable (t)
358 || TREE_CODE (t) == FUNCTION_DECL
359 || TREE_CODE (t) == LABEL_DECL
360 || TREE_CODE (t) == CONST_DECL
361 /* Allow string constants, since they are addressable. */
362 || TREE_CODE (t) == STRING_CST);
365 /* Return true if TYPE is a suitable type for a scalar register variable. */
368 is_gimple_reg_type (tree type)
370 /* In addition to aggregate types, we also exclude complex types if not
371 optimizing because they can be subject to partial stores in GNU C by
372 means of the __real__ and __imag__ operators and we cannot promote
373 them to total stores (see gimplify_modify_expr_complex_part). */
374 return !(AGGREGATE_TYPE_P (type)
375 || (TREE_CODE (type) == COMPLEX_TYPE && !optimize));
379 /* Return true if T is a non-aggregate register variable. */
382 is_gimple_reg (tree t)
384 if (TREE_CODE (t) == SSA_NAME)
385 t = SSA_NAME_VAR (t);
390 if (!is_gimple_variable (t))
393 if (!is_gimple_reg_type (TREE_TYPE (t)))
396 /* A volatile decl is not acceptable because we can't reuse it as
397 needed. We need to copy it into a temp first. */
398 if (TREE_THIS_VOLATILE (t))
401 /* We define "registers" as things that can be renamed as needed,
402 which with our infrastructure does not apply to memory. */
403 if (needs_to_live_in_memory (t))
406 /* Hard register variables are an interesting case. For those that
407 are call-clobbered, we don't know where all the calls are, since
408 we don't (want to) take into account which operations will turn
409 into libcalls at the rtl level. For those that are call-saved,
410 we don't currently model the fact that calls may in fact change
411 global hard registers, nor do we examine ASM_CLOBBERS at the tree
412 level, and so miss variable changes that might imply. All around,
413 it seems safest to not do too much optimization with these at the
414 tree level at all. We'll have to rely on the rtl optimizers to
415 clean this up, as there we've got all the appropriate bits exposed. */
416 if (TREE_CODE (t) == VAR_DECL && DECL_HARD_REGISTER (t))
419 /* Complex and vector values must have been put into SSA-like form.
420 That is, no assignments to the individual components. */
421 if (TREE_CODE (TREE_TYPE (t)) == COMPLEX_TYPE
422 || TREE_CODE (TREE_TYPE (t)) == VECTOR_TYPE)
423 return DECL_GIMPLE_REG_P (t);
429 /* Returns true if T is a GIMPLE formal temporary variable. */
432 is_gimple_formal_tmp_var (tree t)
434 if (TREE_CODE (t) == SSA_NAME)
437 return TREE_CODE (t) == VAR_DECL && DECL_GIMPLE_FORMAL_TEMP_P (t);
440 /* Returns true if T is a GIMPLE formal temporary register variable. */
443 is_gimple_formal_tmp_reg (tree t)
445 /* The intent of this is to get hold of a value that won't change.
446 An SSA_NAME qualifies no matter if its of a user variable or not. */
447 if (TREE_CODE (t) == SSA_NAME)
450 /* We don't know the lifetime characteristics of user variables. */
451 if (!is_gimple_formal_tmp_var (t))
454 /* Finally, it must be capable of being placed in a register. */
455 return is_gimple_reg (t);
458 /* Return true if T is a GIMPLE variable whose address is not needed. */
461 is_gimple_non_addressable (tree t)
463 if (TREE_CODE (t) == SSA_NAME)
464 t = SSA_NAME_VAR (t);
466 return (is_gimple_variable (t) && ! needs_to_live_in_memory (t));
469 /* Return true if T is a GIMPLE rvalue, i.e. an identifier or a constant. */
472 is_gimple_val (tree t)
474 /* Make loads from volatiles and memory vars explicit. */
475 if (is_gimple_variable (t)
476 && is_gimple_reg_type (TREE_TYPE (t))
477 && !is_gimple_reg (t))
480 /* FIXME make these decls. That can happen only when we expose the
481 entire landing-pad construct at the tree level. */
482 if (TREE_CODE (t) == EXC_PTR_EXPR || TREE_CODE (t) == FILTER_EXPR)
485 return (is_gimple_variable (t) || is_gimple_min_invariant (t));
488 /* Similarly, but accept hard registers as inputs to asm statements. */
491 is_gimple_asm_val (tree t)
493 if (TREE_CODE (t) == VAR_DECL && DECL_HARD_REGISTER (t))
496 return is_gimple_val (t);
499 /* Return true if T is a GIMPLE minimal lvalue. */
502 is_gimple_min_lval (tree t)
504 return (is_gimple_id (t)
505 || TREE_CODE (t) == INDIRECT_REF);
508 /* Return true if T is a typecast operation. */
511 is_gimple_cast (tree t)
513 return (CONVERT_EXPR_P (t)
514 || TREE_CODE (t) == FIX_TRUNC_EXPR);
517 /* Return true if T is a valid function operand of a CALL_EXPR. */
520 is_gimple_call_addr (tree t)
522 return (TREE_CODE (t) == OBJ_TYPE_REF
523 || is_gimple_val (t));
526 /* If T makes a function call, return the corresponding CALL_EXPR operand.
527 Otherwise, return NULL_TREE. */
530 get_call_expr_in (tree t)
532 /* FIXME tuples: delete the assertion below when conversion complete. */
533 gcc_assert (TREE_CODE (t) != MODIFY_EXPR);
534 if (TREE_CODE (t) == GIMPLE_MODIFY_STMT)
535 t = GIMPLE_STMT_OPERAND (t, 1);
536 if (TREE_CODE (t) == WITH_SIZE_EXPR)
537 t = TREE_OPERAND (t, 0);
538 if (TREE_CODE (t) == CALL_EXPR)
543 /* Given a memory reference expression T, return its base address.
544 The base address of a memory reference expression is the main
545 object being referenced. For instance, the base address for
546 'array[i].fld[j]' is 'array'. You can think of this as stripping
547 away the offset part from a memory address.
549 This function calls handled_component_p to strip away all the inner
550 parts of the memory reference until it reaches the base object. */
553 get_base_address (tree t)
555 while (handled_component_p (t))
556 t = TREE_OPERAND (t, 0);
559 || TREE_CODE (t) == STRING_CST
560 || TREE_CODE (t) == CONSTRUCTOR
561 || INDIRECT_REF_P (t))
568 recalculate_side_effects (tree t)
570 enum tree_code code = TREE_CODE (t);
571 int len = TREE_OPERAND_LENGTH (t);
574 switch (TREE_CODE_CLASS (code))
580 case GIMPLE_MODIFY_STMT:
582 case PREDECREMENT_EXPR:
583 case PREINCREMENT_EXPR:
584 case POSTDECREMENT_EXPR:
585 case POSTINCREMENT_EXPR:
586 /* All of these have side-effects, no matter what their
595 case tcc_comparison: /* a comparison expression */
596 case tcc_unary: /* a unary arithmetic expression */
597 case tcc_binary: /* a binary arithmetic expression */
598 case tcc_reference: /* a reference */
599 case tcc_vl_exp: /* a function call */
600 TREE_SIDE_EFFECTS (t) = TREE_THIS_VOLATILE (t);
601 for (i = 0; i < len; ++i)
603 tree op = TREE_OPERAND (t, i);
604 if (op && TREE_SIDE_EFFECTS (op))
605 TREE_SIDE_EFFECTS (t) = 1;
610 /* Can never be used with non-expressions. */
615 /* Canonicalize a tree T for use in a COND_EXPR as conditional. Returns
616 a canonicalized tree that is valid for a COND_EXPR or NULL_TREE, if
617 we failed to create one. */
620 canonicalize_cond_expr_cond (tree t)
622 /* For (bool)x use x != 0. */
623 if (TREE_CODE (t) == NOP_EXPR
624 && TREE_TYPE (t) == boolean_type_node)
626 tree top0 = TREE_OPERAND (t, 0);
627 t = build2 (NE_EXPR, TREE_TYPE (t),
628 top0, build_int_cst (TREE_TYPE (top0), 0));
630 /* For !x use x == 0. */
631 else if (TREE_CODE (t) == TRUTH_NOT_EXPR)
633 tree top0 = TREE_OPERAND (t, 0);
634 t = build2 (EQ_EXPR, TREE_TYPE (t),
635 top0, build_int_cst (TREE_TYPE (top0), 0));
637 /* For cmp ? 1 : 0 use cmp. */
638 else if (TREE_CODE (t) == COND_EXPR
639 && COMPARISON_CLASS_P (TREE_OPERAND (t, 0))
640 && integer_onep (TREE_OPERAND (t, 1))
641 && integer_zerop (TREE_OPERAND (t, 2)))
643 tree top0 = TREE_OPERAND (t, 0);
644 t = build2 (TREE_CODE (top0), TREE_TYPE (t),
645 TREE_OPERAND (top0, 0), TREE_OPERAND (top0, 1));
648 if (is_gimple_condexpr (t))