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)
159 && !tree_could_trap_p (t)
160 && is_gimple_val (TREE_OPERAND (t, 0))
161 && is_gimple_val (TREE_OPERAND (t, 1))));
164 /* Return true if T is something whose address can be taken. */
167 is_gimple_addressable (tree t)
169 return (is_gimple_id (t) || handled_component_p (t)
170 || INDIRECT_REF_P (t));
173 /* Return true if T is a valid gimple constant. */
176 is_gimple_constant (const_tree t)
178 switch (TREE_CODE (t))
188 /* Vector constant constructors are gimple invariant. */
190 if (TREE_TYPE (t) && TREE_CODE (TREE_TYPE (t)) == VECTOR_TYPE)
191 return TREE_CONSTANT (t);
200 /* Return true if T is a gimple address. */
203 is_gimple_address (const_tree t)
207 if (TREE_CODE (t) != ADDR_EXPR)
210 op = TREE_OPERAND (t, 0);
211 while (handled_component_p (op))
213 if ((TREE_CODE (op) == ARRAY_REF
214 || TREE_CODE (op) == ARRAY_RANGE_REF)
215 && !is_gimple_val (TREE_OPERAND (op, 1)))
218 op = TREE_OPERAND (op, 0);
221 if (CONSTANT_CLASS_P (op) || INDIRECT_REF_P (op))
224 switch (TREE_CODE (op))
239 /* Return true if T is a gimple invariant address. */
242 is_gimple_invariant_address (const_tree t)
246 if (TREE_CODE (t) != ADDR_EXPR)
249 op = TREE_OPERAND (t, 0);
250 while (handled_component_p (op))
252 switch (TREE_CODE (op))
255 case ARRAY_RANGE_REF:
256 if (!is_gimple_constant (TREE_OPERAND (op, 1))
257 || TREE_OPERAND (op, 2) != NULL_TREE
258 || TREE_OPERAND (op, 3) != NULL_TREE)
263 if (TREE_OPERAND (op, 2) != NULL_TREE)
269 op = TREE_OPERAND (op, 0);
272 return CONSTANT_CLASS_P (op) || decl_address_invariant_p (op);
275 /* Return true if T is a GIMPLE minimal invariant. It's a restricted
276 form of function invariant. */
279 is_gimple_min_invariant (const_tree t)
281 if (TREE_CODE (t) == ADDR_EXPR)
282 return is_gimple_invariant_address (t);
284 return is_gimple_constant (t);
287 /* Return true if T looks like a valid GIMPLE statement. */
290 is_gimple_stmt (tree t)
292 const enum tree_code code = TREE_CODE (t);
297 /* The only valid NOP_EXPR is the empty statement. */
298 return IS_EMPTY_STMT (t);
302 /* These are only valid if they're void. */
303 return TREE_TYPE (t) == NULL || VOID_TYPE_P (TREE_TYPE (t));
309 case CASE_LABEL_EXPR:
311 case TRY_FINALLY_EXPR:
314 case CHANGE_DYNAMIC_TYPE_EXPR:
322 case OMP_SECTIONS_SWITCH:
330 case OMP_ATOMIC_LOAD:
331 case OMP_ATOMIC_STORE:
332 /* These are always void. */
336 case GIMPLE_MODIFY_STMT:
338 /* These are valid regardless of their type. */
346 /* Return true if T is a variable. */
349 is_gimple_variable (tree t)
351 return (TREE_CODE (t) == VAR_DECL
352 || TREE_CODE (t) == PARM_DECL
353 || TREE_CODE (t) == RESULT_DECL
354 || TREE_CODE (t) == SSA_NAME);
357 /* Return true if T is a GIMPLE identifier (something with an address). */
360 is_gimple_id (tree t)
362 return (is_gimple_variable (t)
363 || TREE_CODE (t) == FUNCTION_DECL
364 || TREE_CODE (t) == LABEL_DECL
365 || TREE_CODE (t) == CONST_DECL
366 /* Allow string constants, since they are addressable. */
367 || TREE_CODE (t) == STRING_CST);
370 /* Return true if TYPE is a suitable type for a scalar register variable. */
373 is_gimple_reg_type (tree type)
375 /* In addition to aggregate types, we also exclude complex types if not
376 optimizing because they can be subject to partial stores in GNU C by
377 means of the __real__ and __imag__ operators and we cannot promote
378 them to total stores (see gimplify_modify_expr_complex_part). */
379 return !(AGGREGATE_TYPE_P (type)
380 || (TREE_CODE (type) == COMPLEX_TYPE && !optimize));
384 /* Return true if T is a non-aggregate register variable. */
387 is_gimple_reg (tree t)
389 if (TREE_CODE (t) == SSA_NAME)
390 t = SSA_NAME_VAR (t);
395 if (!is_gimple_variable (t))
398 if (!is_gimple_reg_type (TREE_TYPE (t)))
401 /* A volatile decl is not acceptable because we can't reuse it as
402 needed. We need to copy it into a temp first. */
403 if (TREE_THIS_VOLATILE (t))
406 /* We define "registers" as things that can be renamed as needed,
407 which with our infrastructure does not apply to memory. */
408 if (needs_to_live_in_memory (t))
411 /* Hard register variables are an interesting case. For those that
412 are call-clobbered, we don't know where all the calls are, since
413 we don't (want to) take into account which operations will turn
414 into libcalls at the rtl level. For those that are call-saved,
415 we don't currently model the fact that calls may in fact change
416 global hard registers, nor do we examine ASM_CLOBBERS at the tree
417 level, and so miss variable changes that might imply. All around,
418 it seems safest to not do too much optimization with these at the
419 tree level at all. We'll have to rely on the rtl optimizers to
420 clean this up, as there we've got all the appropriate bits exposed. */
421 if (TREE_CODE (t) == VAR_DECL && DECL_HARD_REGISTER (t))
424 /* Complex and vector values must have been put into SSA-like form.
425 That is, no assignments to the individual components. */
426 if (TREE_CODE (TREE_TYPE (t)) == COMPLEX_TYPE
427 || TREE_CODE (TREE_TYPE (t)) == VECTOR_TYPE)
428 return DECL_GIMPLE_REG_P (t);
434 /* Returns true if T is a GIMPLE formal temporary variable. */
437 is_gimple_formal_tmp_var (tree t)
439 if (TREE_CODE (t) == SSA_NAME)
442 return TREE_CODE (t) == VAR_DECL && DECL_GIMPLE_FORMAL_TEMP_P (t);
445 /* Returns true if T is a GIMPLE formal temporary register variable. */
448 is_gimple_formal_tmp_reg (tree t)
450 /* The intent of this is to get hold of a value that won't change.
451 An SSA_NAME qualifies no matter if its of a user variable or not. */
452 if (TREE_CODE (t) == SSA_NAME)
455 /* We don't know the lifetime characteristics of user variables. */
456 if (!is_gimple_formal_tmp_var (t))
459 /* Finally, it must be capable of being placed in a register. */
460 return is_gimple_reg (t);
463 /* Return true if T is a GIMPLE variable whose address is not needed. */
466 is_gimple_non_addressable (tree t)
468 if (TREE_CODE (t) == SSA_NAME)
469 t = SSA_NAME_VAR (t);
471 return (is_gimple_variable (t) && ! needs_to_live_in_memory (t));
474 /* Return true if T is a GIMPLE rvalue, i.e. an identifier or a constant. */
477 is_gimple_val (tree t)
479 /* Make loads from volatiles and memory vars explicit. */
480 if (is_gimple_variable (t)
481 && is_gimple_reg_type (TREE_TYPE (t))
482 && !is_gimple_reg (t))
485 /* FIXME make these decls. That can happen only when we expose the
486 entire landing-pad construct at the tree level. */
487 if (TREE_CODE (t) == EXC_PTR_EXPR || TREE_CODE (t) == FILTER_EXPR)
490 return (is_gimple_variable (t) || is_gimple_min_invariant (t));
493 /* Similarly, but accept hard registers as inputs to asm statements. */
496 is_gimple_asm_val (tree t)
498 if (TREE_CODE (t) == VAR_DECL && DECL_HARD_REGISTER (t))
501 return is_gimple_val (t);
504 /* Return true if T is a GIMPLE minimal lvalue. */
507 is_gimple_min_lval (tree t)
509 return (is_gimple_id (t)
510 || TREE_CODE (t) == INDIRECT_REF);
513 /* Return true if T is a typecast operation. */
516 is_gimple_cast (tree t)
518 return (CONVERT_EXPR_P (t)
519 || TREE_CODE (t) == FIX_TRUNC_EXPR);
522 /* Return true if T is a valid function operand of a CALL_EXPR. */
525 is_gimple_call_addr (tree t)
527 return (TREE_CODE (t) == OBJ_TYPE_REF
528 || is_gimple_val (t));
531 /* If T makes a function call, return the corresponding CALL_EXPR operand.
532 Otherwise, return NULL_TREE. */
535 get_call_expr_in (tree t)
537 /* FIXME tuples: delete the assertion below when conversion complete. */
538 gcc_assert (TREE_CODE (t) != MODIFY_EXPR);
539 if (TREE_CODE (t) == GIMPLE_MODIFY_STMT)
540 t = GIMPLE_STMT_OPERAND (t, 1);
541 if (TREE_CODE (t) == WITH_SIZE_EXPR)
542 t = TREE_OPERAND (t, 0);
543 if (TREE_CODE (t) == CALL_EXPR)
548 /* Given a memory reference expression T, return its base address.
549 The base address of a memory reference expression is the main
550 object being referenced. For instance, the base address for
551 'array[i].fld[j]' is 'array'. You can think of this as stripping
552 away the offset part from a memory address.
554 This function calls handled_component_p to strip away all the inner
555 parts of the memory reference until it reaches the base object. */
558 get_base_address (tree t)
560 while (handled_component_p (t))
561 t = TREE_OPERAND (t, 0);
564 || TREE_CODE (t) == STRING_CST
565 || TREE_CODE (t) == CONSTRUCTOR
566 || INDIRECT_REF_P (t))
573 recalculate_side_effects (tree t)
575 enum tree_code code = TREE_CODE (t);
576 int len = TREE_OPERAND_LENGTH (t);
579 switch (TREE_CODE_CLASS (code))
585 case GIMPLE_MODIFY_STMT:
587 case PREDECREMENT_EXPR:
588 case PREINCREMENT_EXPR:
589 case POSTDECREMENT_EXPR:
590 case POSTINCREMENT_EXPR:
591 /* All of these have side-effects, no matter what their
600 case tcc_comparison: /* a comparison expression */
601 case tcc_unary: /* a unary arithmetic expression */
602 case tcc_binary: /* a binary arithmetic expression */
603 case tcc_reference: /* a reference */
604 case tcc_vl_exp: /* a function call */
605 TREE_SIDE_EFFECTS (t) = TREE_THIS_VOLATILE (t);
606 for (i = 0; i < len; ++i)
608 tree op = TREE_OPERAND (t, i);
609 if (op && TREE_SIDE_EFFECTS (op))
610 TREE_SIDE_EFFECTS (t) = 1;
615 /* Can never be used with non-expressions. */
620 /* Canonicalize a tree T for use in a COND_EXPR as conditional. Returns
621 a canonicalized tree that is valid for a COND_EXPR or NULL_TREE, if
622 we failed to create one. */
625 canonicalize_cond_expr_cond (tree t)
627 /* For (bool)x use x != 0. */
628 if (TREE_CODE (t) == NOP_EXPR
629 && TREE_TYPE (t) == boolean_type_node)
631 tree top0 = TREE_OPERAND (t, 0);
632 t = build2 (NE_EXPR, TREE_TYPE (t),
633 top0, build_int_cst (TREE_TYPE (top0), 0));
635 /* For !x use x == 0. */
636 else if (TREE_CODE (t) == TRUTH_NOT_EXPR)
638 tree top0 = TREE_OPERAND (t, 0);
639 t = build2 (EQ_EXPR, TREE_TYPE (t),
640 top0, build_int_cst (TREE_TYPE (top0), 0));
642 /* For cmp ? 1 : 0 use cmp. */
643 else if (TREE_CODE (t) == COND_EXPR
644 && COMPARISON_CLASS_P (TREE_OPERAND (t, 0))
645 && integer_onep (TREE_OPERAND (t, 1))
646 && integer_zerop (TREE_OPERAND (t, 2)))
648 tree top0 = TREE_OPERAND (t, 0);
649 t = build2 (TREE_CODE (top0), TREE_TYPE (t),
650 TREE_OPERAND (top0, 0), TREE_OPERAND (top0, 1));
653 if (is_gimple_condexpr (t))