1 /* Functions to analyze and validate GIMPLE trees.
2 Copyright (C) 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>
4 Rewritten by Jason Merrill <jason@redhat.com>
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2, or (at your option)
13 GCC is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING. If not, write to
20 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
21 Boston, MA 02110-1301, USA. */
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 static inline bool is_gimple_id (tree);
40 /* Validation of GIMPLE expressions. */
42 /* Return true if T is a GIMPLE RHS for an assignment to a temporary. */
45 is_gimple_formal_tmp_rhs (tree t)
47 enum tree_code code = TREE_CODE (t);
49 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 MODIFY_EXPR 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 V_MAY_DEF 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 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 function invariant. Or rather a restricted
169 form of function invariant. */
172 is_gimple_min_invariant (tree t)
174 switch (TREE_CODE (t))
177 return TREE_INVARIANT (t);
191 /* Return true if T looks like a valid GIMPLE statement. */
194 is_gimple_stmt (tree t)
196 enum tree_code code = TREE_CODE (t);
198 if (IS_EMPTY_STMT (t))
205 /* These are only valid if they're void. */
206 return TREE_TYPE (t) == NULL || VOID_TYPE_P (TREE_TYPE (t));
212 case CASE_LABEL_EXPR:
214 case TRY_FINALLY_EXPR:
221 /* These are always void. */
226 /* These are valid regardless of their type. */
234 /* Return true if T is a variable. */
237 is_gimple_variable (tree t)
239 return (TREE_CODE (t) == VAR_DECL
240 || TREE_CODE (t) == PARM_DECL
241 || TREE_CODE (t) == RESULT_DECL
242 || TREE_CODE (t) == SSA_NAME);
245 /* Return true if T is a GIMPLE identifier (something with an address). */
248 is_gimple_id (tree t)
250 return (is_gimple_variable (t)
251 || TREE_CODE (t) == FUNCTION_DECL
252 || TREE_CODE (t) == LABEL_DECL
253 || TREE_CODE (t) == CONST_DECL
254 /* Allow string constants, since they are addressable. */
255 || TREE_CODE (t) == STRING_CST);
258 /* Return true if TYPE is a suitable type for a scalar register variable. */
261 is_gimple_reg_type (tree type)
263 return !AGGREGATE_TYPE_P (type);
266 /* Return true if T is a non-aggregate register variable. */
269 is_gimple_reg (tree t)
271 if (TREE_CODE (t) == SSA_NAME)
272 t = SSA_NAME_VAR (t);
274 if (!is_gimple_variable (t))
277 if (!is_gimple_reg_type (TREE_TYPE (t)))
280 /* A volatile decl is not acceptable because we can't reuse it as
281 needed. We need to copy it into a temp first. */
282 if (TREE_THIS_VOLATILE (t))
285 /* We define "registers" as things that can be renamed as needed,
286 which with our infrastructure does not apply to memory. */
287 if (needs_to_live_in_memory (t))
290 /* Hard register variables are an interesting case. For those that
291 are call-clobbered, we don't know where all the calls are, since
292 we don't (want to) take into account which operations will turn
293 into libcalls at the rtl level. For those that are call-saved,
294 we don't currently model the fact that calls may in fact change
295 global hard registers, nor do we examine ASM_CLOBBERS at the tree
296 level, and so miss variable changes that might imply. All around,
297 it seems safest to not do too much optimization with these at the
298 tree level at all. We'll have to rely on the rtl optimizers to
299 clean this up, as there we've got all the appropriate bits exposed. */
300 if (TREE_CODE (t) == VAR_DECL && DECL_HARD_REGISTER (t))
303 /* Complex values must have been put into ssa form. That is, no
304 assignments to the individual components. */
305 if (TREE_CODE (TREE_TYPE (t)) == COMPLEX_TYPE)
306 return DECL_COMPLEX_GIMPLE_REG_P (t);
311 /* Returns true if T is a GIMPLE formal temporary variable. */
314 is_gimple_formal_tmp_var (tree t)
316 if (TREE_CODE (t) == SSA_NAME)
319 return TREE_CODE (t) == VAR_DECL && DECL_GIMPLE_FORMAL_TEMP_P (t);
322 /* Returns true if T is a GIMPLE formal temporary register variable. */
325 is_gimple_formal_tmp_reg (tree t)
327 /* The intent of this is to get hold of a value that won't change.
328 An SSA_NAME qualifies no matter if its of a user variable or not. */
329 if (TREE_CODE (t) == SSA_NAME)
332 /* We don't know the lifetime characteristics of user variables. */
333 if (!is_gimple_formal_tmp_var (t))
336 /* Finally, it must be capable of being placed in a register. */
337 return is_gimple_reg (t);
340 /* Return true if T is a GIMPLE variable whose address is not needed. */
343 is_gimple_non_addressable (tree t)
345 if (TREE_CODE (t) == SSA_NAME)
346 t = SSA_NAME_VAR (t);
348 return (is_gimple_variable (t) && ! needs_to_live_in_memory (t));
351 /* Return true if T is a GIMPLE rvalue, i.e. an identifier or a constant. */
354 is_gimple_val (tree t)
356 /* Make loads from volatiles and memory vars explicit. */
357 if (is_gimple_variable (t)
358 && is_gimple_reg_type (TREE_TYPE (t))
359 && !is_gimple_reg (t))
362 /* FIXME make these decls. That can happen only when we expose the
363 entire landing-pad construct at the tree level. */
364 if (TREE_CODE (t) == EXC_PTR_EXPR || TREE_CODE (t) == FILTER_EXPR)
367 return (is_gimple_variable (t) || is_gimple_min_invariant (t));
370 /* Similarly, but accept hard registers as inputs to asm statements. */
373 is_gimple_asm_val (tree t)
375 if (TREE_CODE (t) == VAR_DECL && DECL_HARD_REGISTER (t))
378 return is_gimple_val (t);
381 /* Return true if T is a GIMPLE minimal lvalue. */
384 is_gimple_min_lval (tree t)
386 return (is_gimple_id (t)
387 || TREE_CODE (t) == INDIRECT_REF);
390 /* Return true if T is a typecast operation. */
393 is_gimple_cast (tree t)
395 return (TREE_CODE (t) == NOP_EXPR
396 || TREE_CODE (t) == CONVERT_EXPR
397 || TREE_CODE (t) == FIX_TRUNC_EXPR
398 || TREE_CODE (t) == FIX_CEIL_EXPR
399 || TREE_CODE (t) == FIX_FLOOR_EXPR
400 || TREE_CODE (t) == FIX_ROUND_EXPR);
403 /* Return true if T is a valid op0 of a CALL_EXPR. */
406 is_gimple_call_addr (tree t)
408 return (TREE_CODE (t) == OBJ_TYPE_REF
409 || is_gimple_val (t));
412 /* If T makes a function call, return the corresponding CALL_EXPR operand.
413 Otherwise, return NULL_TREE. */
416 get_call_expr_in (tree t)
418 if (TREE_CODE (t) == MODIFY_EXPR)
419 t = TREE_OPERAND (t, 1);
420 if (TREE_CODE (t) == WITH_SIZE_EXPR)
421 t = TREE_OPERAND (t, 0);
422 if (TREE_CODE (t) == CALL_EXPR)
427 /* Given a memory reference expression T, return its base address.
428 The base address of a memory reference expression is the main
429 object being referenced. For instance, the base address for
430 'array[i].fld[j]' is 'array'. You can think of this as stripping
431 away the offset part from a memory address.
433 This function calls handled_component_p to strip away all the inner
434 parts of the memory reference until it reaches the base object. */
437 get_base_address (tree t)
439 while (handled_component_p (t))
440 t = TREE_OPERAND (t, 0);
443 || TREE_CODE (t) == STRING_CST
444 || TREE_CODE (t) == CONSTRUCTOR
445 || INDIRECT_REF_P (t))
452 recalculate_side_effects (tree t)
454 enum tree_code code = TREE_CODE (t);
455 int len = TREE_CODE_LENGTH (code);
458 switch (TREE_CODE_CLASS (code))
466 case PREDECREMENT_EXPR:
467 case PREINCREMENT_EXPR:
468 case POSTDECREMENT_EXPR:
469 case POSTINCREMENT_EXPR:
470 /* All of these have side-effects, no matter what their
479 case tcc_comparison: /* a comparison expression */
480 case tcc_unary: /* a unary arithmetic expression */
481 case tcc_binary: /* a binary arithmetic expression */
482 case tcc_reference: /* a reference */
483 TREE_SIDE_EFFECTS (t) = TREE_THIS_VOLATILE (t);
484 for (i = 0; i < len; ++i)
486 tree op = TREE_OPERAND (t, i);
487 if (op && TREE_SIDE_EFFECTS (op))
488 TREE_SIDE_EFFECTS (t) = 1;
493 /* Can never be used with non-expressions. */