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[official-gcc.git] / gcc / tree-gimple.c
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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)
11 any later version.
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. */
23 #include "config.h"
24 #include "system.h"
25 #include "coretypes.h"
26 #include "ggc.h"
27 #include "tm.h"
28 #include "tree.h"
29 #include "tree-gimple.h"
30 #include "tree-flow.h"
31 #include "output.h"
32 #include "rtl.h"
33 #include "expr.h"
34 #include "bitmap.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. */
42 bool
43 is_gimple_formal_tmp_rhs (tree t)
45 enum tree_code code = TREE_CODE (t);
47 switch (TREE_CODE_CLASS (code))
49 case tcc_unary:
50 case tcc_binary:
51 case tcc_comparison:
52 return true;
54 default:
55 break;
58 switch (code)
60 case TRUTH_NOT_EXPR:
61 case TRUTH_AND_EXPR:
62 case TRUTH_OR_EXPR:
63 case TRUTH_XOR_EXPR:
64 case ADDR_EXPR:
65 case CALL_EXPR:
66 case CONSTRUCTOR:
67 case COMPLEX_EXPR:
68 case INTEGER_CST:
69 case REAL_CST:
70 case STRING_CST:
71 case COMPLEX_CST:
72 case VECTOR_CST:
73 case OBJ_TYPE_REF:
74 case ASSERT_EXPR:
75 return true;
77 default:
78 break;
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. */
87 bool
88 is_gimple_reg_rhs (tree t)
90 /* If the RHS of the MODIFY_EXPR 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 V_MAY_DEF for
97 the assignment. */
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)))
102 return false;
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. */
110 bool
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);
122 else
123 return is_gimple_formal_tmp_rhs (t);
126 /* Returns the appropriate RHS predicate for this LHS. */
128 gimple_predicate
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;
135 else
136 return is_gimple_mem_rhs;
139 /* Return true if T is a valid LHS for a GIMPLE assignment expression. */
141 bool
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
147 go here. */
148 || TREE_CODE (t) == BIT_FIELD_REF);
151 /* Return true if T is a GIMPLE condition. */
153 bool
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. */
161 bool
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. */
171 bool
172 is_gimple_min_invariant (tree t)
174 switch (TREE_CODE (t))
176 case ADDR_EXPR:
177 return TREE_INVARIANT (t);
179 case INTEGER_CST:
180 case REAL_CST:
181 case STRING_CST:
182 case COMPLEX_CST:
183 case VECTOR_CST:
184 return true;
186 default:
187 return false;
191 /* Return true if T looks like a valid GIMPLE statement. */
193 bool
194 is_gimple_stmt (tree t)
196 enum tree_code code = TREE_CODE (t);
198 switch (code)
200 case NOP_EXPR:
201 /* The only valid NOP_EXPR is the empty statement. */
202 return IS_EMPTY_STMT (t);
204 case BIND_EXPR:
205 case COND_EXPR:
206 /* These are only valid if they're void. */
207 return TREE_TYPE (t) == NULL || VOID_TYPE_P (TREE_TYPE (t));
209 case SWITCH_EXPR:
210 case GOTO_EXPR:
211 case RETURN_EXPR:
212 case LABEL_EXPR:
213 case CASE_LABEL_EXPR:
214 case TRY_CATCH_EXPR:
215 case TRY_FINALLY_EXPR:
216 case EH_FILTER_EXPR:
217 case CATCH_EXPR:
218 case ASM_EXPR:
219 case RESX_EXPR:
220 case PHI_NODE:
221 case STATEMENT_LIST:
222 case OMP_PARALLEL:
223 case OMP_FOR:
224 case OMP_SECTIONS:
225 case OMP_SECTION:
226 case OMP_SINGLE:
227 case OMP_MASTER:
228 case OMP_ORDERED:
229 case OMP_CRITICAL:
230 case OMP_RETURN:
231 case OMP_CONTINUE:
232 /* These are always void. */
233 return true;
235 case CALL_EXPR:
236 case MODIFY_EXPR:
237 /* These are valid regardless of their type. */
238 return true;
240 default:
241 return false;
245 /* Return true if T is a variable. */
247 bool
248 is_gimple_variable (tree t)
250 return (TREE_CODE (t) == VAR_DECL
251 || TREE_CODE (t) == PARM_DECL
252 || TREE_CODE (t) == RESULT_DECL
253 || TREE_CODE (t) == SSA_NAME);
256 /* Return true if T is a GIMPLE identifier (something with an address). */
258 bool
259 is_gimple_id (tree t)
261 return (is_gimple_variable (t)
262 || TREE_CODE (t) == FUNCTION_DECL
263 || TREE_CODE (t) == LABEL_DECL
264 || TREE_CODE (t) == CONST_DECL
265 /* Allow string constants, since they are addressable. */
266 || TREE_CODE (t) == STRING_CST);
269 /* Return true if TYPE is a suitable type for a scalar register variable. */
271 bool
272 is_gimple_reg_type (tree type)
274 return !AGGREGATE_TYPE_P (type);
277 /* Return true if T is a non-aggregate register variable. */
279 bool
280 is_gimple_reg (tree t)
282 if (TREE_CODE (t) == SSA_NAME)
283 t = SSA_NAME_VAR (t);
285 if (MTAG_P (t))
286 return false;
288 if (!is_gimple_variable (t))
289 return false;
291 if (!is_gimple_reg_type (TREE_TYPE (t)))
292 return false;
294 /* A volatile decl is not acceptable because we can't reuse it as
295 needed. We need to copy it into a temp first. */
296 if (TREE_THIS_VOLATILE (t))
297 return false;
299 /* We define "registers" as things that can be renamed as needed,
300 which with our infrastructure does not apply to memory. */
301 if (needs_to_live_in_memory (t))
302 return false;
304 /* Hard register variables are an interesting case. For those that
305 are call-clobbered, we don't know where all the calls are, since
306 we don't (want to) take into account which operations will turn
307 into libcalls at the rtl level. For those that are call-saved,
308 we don't currently model the fact that calls may in fact change
309 global hard registers, nor do we examine ASM_CLOBBERS at the tree
310 level, and so miss variable changes that might imply. All around,
311 it seems safest to not do too much optimization with these at the
312 tree level at all. We'll have to rely on the rtl optimizers to
313 clean this up, as there we've got all the appropriate bits exposed. */
314 if (TREE_CODE (t) == VAR_DECL && DECL_HARD_REGISTER (t))
315 return false;
317 /* Complex values must have been put into ssa form. That is, no
318 assignments to the individual components. */
319 if (TREE_CODE (TREE_TYPE (t)) == COMPLEX_TYPE)
320 return DECL_COMPLEX_GIMPLE_REG_P (t);
322 return true;
326 /* Returns true if T is a GIMPLE formal temporary variable. */
328 bool
329 is_gimple_formal_tmp_var (tree t)
331 if (TREE_CODE (t) == SSA_NAME)
332 return true;
334 return TREE_CODE (t) == VAR_DECL && DECL_GIMPLE_FORMAL_TEMP_P (t);
337 /* Returns true if T is a GIMPLE formal temporary register variable. */
339 bool
340 is_gimple_formal_tmp_reg (tree t)
342 /* The intent of this is to get hold of a value that won't change.
343 An SSA_NAME qualifies no matter if its of a user variable or not. */
344 if (TREE_CODE (t) == SSA_NAME)
345 return true;
347 /* We don't know the lifetime characteristics of user variables. */
348 if (!is_gimple_formal_tmp_var (t))
349 return false;
351 /* Finally, it must be capable of being placed in a register. */
352 return is_gimple_reg (t);
355 /* Return true if T is a GIMPLE variable whose address is not needed. */
357 bool
358 is_gimple_non_addressable (tree t)
360 if (TREE_CODE (t) == SSA_NAME)
361 t = SSA_NAME_VAR (t);
363 return (is_gimple_variable (t) && ! needs_to_live_in_memory (t));
366 /* Return true if T is a GIMPLE rvalue, i.e. an identifier or a constant. */
368 bool
369 is_gimple_val (tree t)
371 /* Make loads from volatiles and memory vars explicit. */
372 if (is_gimple_variable (t)
373 && is_gimple_reg_type (TREE_TYPE (t))
374 && !is_gimple_reg (t))
375 return false;
377 /* FIXME make these decls. That can happen only when we expose the
378 entire landing-pad construct at the tree level. */
379 if (TREE_CODE (t) == EXC_PTR_EXPR || TREE_CODE (t) == FILTER_EXPR)
380 return 1;
382 return (is_gimple_variable (t) || is_gimple_min_invariant (t));
385 /* Similarly, but accept hard registers as inputs to asm statements. */
387 bool
388 is_gimple_asm_val (tree t)
390 if (TREE_CODE (t) == VAR_DECL && DECL_HARD_REGISTER (t))
391 return true;
393 return is_gimple_val (t);
396 /* Return true if T is a GIMPLE minimal lvalue. */
398 bool
399 is_gimple_min_lval (tree t)
401 return (is_gimple_id (t)
402 || TREE_CODE (t) == INDIRECT_REF);
405 /* Return true if T is a typecast operation. */
407 bool
408 is_gimple_cast (tree t)
410 return (TREE_CODE (t) == NOP_EXPR
411 || TREE_CODE (t) == CONVERT_EXPR
412 || TREE_CODE (t) == FIX_TRUNC_EXPR
413 || TREE_CODE (t) == FIX_CEIL_EXPR
414 || TREE_CODE (t) == FIX_FLOOR_EXPR
415 || TREE_CODE (t) == FIX_ROUND_EXPR);
418 /* Return true if T is a valid op0 of a CALL_EXPR. */
420 bool
421 is_gimple_call_addr (tree t)
423 return (TREE_CODE (t) == OBJ_TYPE_REF
424 || is_gimple_val (t));
427 /* If T makes a function call, return the corresponding CALL_EXPR operand.
428 Otherwise, return NULL_TREE. */
430 tree
431 get_call_expr_in (tree t)
433 if (TREE_CODE (t) == MODIFY_EXPR)
434 t = TREE_OPERAND (t, 1);
435 if (TREE_CODE (t) == WITH_SIZE_EXPR)
436 t = TREE_OPERAND (t, 0);
437 if (TREE_CODE (t) == CALL_EXPR)
438 return t;
439 return NULL_TREE;
442 /* Given a memory reference expression T, return its base address.
443 The base address of a memory reference expression is the main
444 object being referenced. For instance, the base address for
445 'array[i].fld[j]' is 'array'. You can think of this as stripping
446 away the offset part from a memory address.
448 This function calls handled_component_p to strip away all the inner
449 parts of the memory reference until it reaches the base object. */
451 tree
452 get_base_address (tree t)
454 while (handled_component_p (t))
455 t = TREE_OPERAND (t, 0);
457 if (SSA_VAR_P (t)
458 || TREE_CODE (t) == STRING_CST
459 || TREE_CODE (t) == CONSTRUCTOR
460 || INDIRECT_REF_P (t))
461 return t;
462 else
463 return NULL_TREE;
466 void
467 recalculate_side_effects (tree t)
469 enum tree_code code = TREE_CODE (t);
470 int len = TREE_CODE_LENGTH (code);
471 int i;
473 switch (TREE_CODE_CLASS (code))
475 case tcc_expression:
476 switch (code)
478 case INIT_EXPR:
479 case MODIFY_EXPR:
480 case VA_ARG_EXPR:
481 case PREDECREMENT_EXPR:
482 case PREINCREMENT_EXPR:
483 case POSTDECREMENT_EXPR:
484 case POSTINCREMENT_EXPR:
485 /* All of these have side-effects, no matter what their
486 operands are. */
487 return;
489 default:
490 break;
492 /* Fall through. */
494 case tcc_comparison: /* a comparison expression */
495 case tcc_unary: /* a unary arithmetic expression */
496 case tcc_binary: /* a binary arithmetic expression */
497 case tcc_reference: /* a reference */
498 TREE_SIDE_EFFECTS (t) = TREE_THIS_VOLATILE (t);
499 for (i = 0; i < len; ++i)
501 tree op = TREE_OPERAND (t, i);
502 if (op && TREE_SIDE_EFFECTS (op))
503 TREE_SIDE_EFFECTS (t) = 1;
505 break;
507 default:
508 /* Can never be used with non-expressions. */
509 gcc_unreachable ();