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))
81 return is_gimple_lvalue (t) || is_gimple_val (t);
84 /* Returns true iff T is a valid RHS for an assignment to a renamed
85 user -- or front-end generated artificial -- variable. */
88 is_gimple_reg_rhs (tree t)
90 /* If the RHS of the GIMPLE_MODIFY_STMT may throw or make a nonlocal goto
91 and the LHS is a user variable, then we need to introduce a formal
92 temporary. This way the optimizers can determine that the user
93 variable is only modified if evaluation of the RHS does not throw.
95 Don't force a temp of a non-renamable type; the copy could be
96 arbitrarily expensive. Instead we will generate a VDEF for
99 if (is_gimple_reg_type (TREE_TYPE (t))
100 && ((TREE_CODE (t) == CALL_EXPR && TREE_SIDE_EFFECTS (t))
101 || tree_could_throw_p (t)))
104 return is_gimple_formal_tmp_rhs (t);
107 /* Returns true iff T is a valid RHS for an assignment to an un-renamed
108 LHS, or for a call argument. */
111 is_gimple_mem_rhs (tree t)
113 /* If we're dealing with a renamable type, either source or dest must be
114 a renamed variable. Also force a temporary if the type doesn't need
115 to be stored in memory, since it's cheap and prevents erroneous
116 tailcalls (PR 17526). */
117 if (is_gimple_reg_type (TREE_TYPE (t))
118 || (TYPE_MODE (TREE_TYPE (t)) != BLKmode
119 && (TREE_CODE (t) != CALL_EXPR
120 || ! aggregate_value_p (t, t))))
121 return is_gimple_val (t);
123 return is_gimple_formal_tmp_rhs (t);
126 /* Returns the appropriate RHS predicate for this LHS. */
129 rhs_predicate_for (tree lhs)
131 if (is_gimple_formal_tmp_var (lhs))
132 return is_gimple_formal_tmp_rhs;
133 else if (is_gimple_reg (lhs))
134 return is_gimple_reg_rhs;
136 return is_gimple_mem_rhs;
139 /* Return true if T is a valid LHS for a GIMPLE assignment expression. */
142 is_gimple_lvalue (tree t)
144 return (is_gimple_addressable (t)
145 || TREE_CODE (t) == WITH_SIZE_EXPR
146 /* These are complex lvalues, but don't have addresses, so they
148 || TREE_CODE (t) == BIT_FIELD_REF);
151 /* Return true if T is a GIMPLE condition. */
154 is_gimple_condexpr (tree t)
156 return (is_gimple_val (t) || COMPARISON_CLASS_P (t));
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 GIMPLE minimal invariant. It's a restricted
169 form of function invariant. */
172 is_gimple_min_invariant (const_tree t)
174 switch (TREE_CODE (t))
177 return TREE_INVARIANT (t);
186 /* Vector constant constructors are gimple invariant. */
188 if (TREE_TYPE (t) && TREE_CODE (TREE_TYPE (t)) == VECTOR_TYPE)
189 return TREE_CONSTANT (t);
198 /* Return true if T looks like a valid GIMPLE statement. */
201 is_gimple_stmt (tree t)
203 enum tree_code code = TREE_CODE (t);
208 /* The only valid NOP_EXPR is the empty statement. */
209 return IS_EMPTY_STMT (t);
213 /* These are only valid if they're void. */
214 return TREE_TYPE (t) == NULL || VOID_TYPE_P (TREE_TYPE (t));
220 case CASE_LABEL_EXPR:
222 case TRY_FINALLY_EXPR:
225 case CHANGE_DYNAMIC_TYPE_EXPR:
240 /* These are always void. */
244 case GIMPLE_MODIFY_STMT:
245 /* These are valid regardless of their type. */
253 /* Return true if T is a variable. */
256 is_gimple_variable (tree t)
258 return (TREE_CODE (t) == VAR_DECL
259 || TREE_CODE (t) == PARM_DECL
260 || TREE_CODE (t) == RESULT_DECL
261 || TREE_CODE (t) == SSA_NAME);
264 /* Return true if T is a GIMPLE identifier (something with an address). */
267 is_gimple_id (tree t)
269 return (is_gimple_variable (t)
270 || TREE_CODE (t) == FUNCTION_DECL
271 || TREE_CODE (t) == LABEL_DECL
272 || TREE_CODE (t) == CONST_DECL
273 /* Allow string constants, since they are addressable. */
274 || TREE_CODE (t) == STRING_CST);
277 /* Return true if TYPE is a suitable type for a scalar register variable. */
280 is_gimple_reg_type (tree type)
282 return !AGGREGATE_TYPE_P (type);
285 /* Return true if T is a non-aggregate register variable. */
288 is_gimple_reg (tree t)
290 if (TREE_CODE (t) == SSA_NAME)
291 t = SSA_NAME_VAR (t);
296 if (!is_gimple_variable (t))
299 if (!is_gimple_reg_type (TREE_TYPE (t)))
302 /* A volatile decl is not acceptable because we can't reuse it as
303 needed. We need to copy it into a temp first. */
304 if (TREE_THIS_VOLATILE (t))
307 /* We define "registers" as things that can be renamed as needed,
308 which with our infrastructure does not apply to memory. */
309 if (needs_to_live_in_memory (t))
312 /* Hard register variables are an interesting case. For those that
313 are call-clobbered, we don't know where all the calls are, since
314 we don't (want to) take into account which operations will turn
315 into libcalls at the rtl level. For those that are call-saved,
316 we don't currently model the fact that calls may in fact change
317 global hard registers, nor do we examine ASM_CLOBBERS at the tree
318 level, and so miss variable changes that might imply. All around,
319 it seems safest to not do too much optimization with these at the
320 tree level at all. We'll have to rely on the rtl optimizers to
321 clean this up, as there we've got all the appropriate bits exposed. */
322 if (TREE_CODE (t) == VAR_DECL && DECL_HARD_REGISTER (t))
325 /* Complex values must have been put into ssa form. That is, no
326 assignments to the individual components. */
327 if (TREE_CODE (TREE_TYPE (t)) == COMPLEX_TYPE
328 || TREE_CODE (TREE_TYPE (t)) == VECTOR_TYPE)
329 return DECL_GIMPLE_REG_P (t);
335 /* Returns true if T is a GIMPLE formal temporary variable. */
338 is_gimple_formal_tmp_var (tree t)
340 if (TREE_CODE (t) == SSA_NAME)
343 return TREE_CODE (t) == VAR_DECL && DECL_GIMPLE_FORMAL_TEMP_P (t);
346 /* Returns true if T is a GIMPLE formal temporary register variable. */
349 is_gimple_formal_tmp_reg (tree t)
351 /* The intent of this is to get hold of a value that won't change.
352 An SSA_NAME qualifies no matter if its of a user variable or not. */
353 if (TREE_CODE (t) == SSA_NAME)
356 /* We don't know the lifetime characteristics of user variables. */
357 if (!is_gimple_formal_tmp_var (t))
360 /* Finally, it must be capable of being placed in a register. */
361 return is_gimple_reg (t);
364 /* Return true if T is a GIMPLE variable whose address is not needed. */
367 is_gimple_non_addressable (tree t)
369 if (TREE_CODE (t) == SSA_NAME)
370 t = SSA_NAME_VAR (t);
372 return (is_gimple_variable (t) && ! needs_to_live_in_memory (t));
375 /* Return true if T is a GIMPLE rvalue, i.e. an identifier or a constant. */
378 is_gimple_val (tree t)
380 /* Make loads from volatiles and memory vars explicit. */
381 if (is_gimple_variable (t)
382 && is_gimple_reg_type (TREE_TYPE (t))
383 && !is_gimple_reg (t))
386 /* FIXME make these decls. That can happen only when we expose the
387 entire landing-pad construct at the tree level. */
388 if (TREE_CODE (t) == EXC_PTR_EXPR || TREE_CODE (t) == FILTER_EXPR)
391 return (is_gimple_variable (t) || is_gimple_min_invariant (t));
394 /* Similarly, but accept hard registers as inputs to asm statements. */
397 is_gimple_asm_val (tree t)
399 if (TREE_CODE (t) == VAR_DECL && DECL_HARD_REGISTER (t))
402 return is_gimple_val (t);
405 /* Return true if T is a GIMPLE minimal lvalue. */
408 is_gimple_min_lval (tree t)
410 return (is_gimple_id (t)
411 || TREE_CODE (t) == INDIRECT_REF);
414 /* Return true if T is a typecast operation. */
417 is_gimple_cast (tree t)
419 return (TREE_CODE (t) == NOP_EXPR
420 || TREE_CODE (t) == CONVERT_EXPR
421 || TREE_CODE (t) == FIX_TRUNC_EXPR);
424 /* Return true if T is a valid function operand of a CALL_EXPR. */
427 is_gimple_call_addr (tree t)
429 return (TREE_CODE (t) == OBJ_TYPE_REF
430 || is_gimple_val (t));
433 /* If T makes a function call, return the corresponding CALL_EXPR operand.
434 Otherwise, return NULL_TREE. */
437 get_call_expr_in (tree t)
439 /* FIXME tuples: delete the assertion below when conversion complete. */
440 gcc_assert (TREE_CODE (t) != MODIFY_EXPR);
441 if (TREE_CODE (t) == GIMPLE_MODIFY_STMT)
442 t = GIMPLE_STMT_OPERAND (t, 1);
443 if (TREE_CODE (t) == WITH_SIZE_EXPR)
444 t = TREE_OPERAND (t, 0);
445 if (TREE_CODE (t) == CALL_EXPR)
450 /* Given a memory reference expression T, return its base address.
451 The base address of a memory reference expression is the main
452 object being referenced. For instance, the base address for
453 'array[i].fld[j]' is 'array'. You can think of this as stripping
454 away the offset part from a memory address.
456 This function calls handled_component_p to strip away all the inner
457 parts of the memory reference until it reaches the base object. */
460 get_base_address (tree t)
462 while (handled_component_p (t))
463 t = TREE_OPERAND (t, 0);
466 || TREE_CODE (t) == STRING_CST
467 || TREE_CODE (t) == CONSTRUCTOR
468 || INDIRECT_REF_P (t))
475 recalculate_side_effects (tree t)
477 enum tree_code code = TREE_CODE (t);
478 int len = TREE_OPERAND_LENGTH (t);
481 switch (TREE_CODE_CLASS (code))
487 case GIMPLE_MODIFY_STMT:
489 case PREDECREMENT_EXPR:
490 case PREINCREMENT_EXPR:
491 case POSTDECREMENT_EXPR:
492 case POSTINCREMENT_EXPR:
493 /* All of these have side-effects, no matter what their
502 case tcc_comparison: /* a comparison expression */
503 case tcc_unary: /* a unary arithmetic expression */
504 case tcc_binary: /* a binary arithmetic expression */
505 case tcc_reference: /* a reference */
506 case tcc_vl_exp: /* a function call */
507 TREE_SIDE_EFFECTS (t) = TREE_THIS_VOLATILE (t);
508 for (i = 0; i < len; ++i)
510 tree op = TREE_OPERAND (t, i);
511 if (op && TREE_SIDE_EFFECTS (op))
512 TREE_SIDE_EFFECTS (t) = 1;
517 /* Can never be used with non-expressions. */