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 /* 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 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
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 return is_gimple_val (t
);
121 return is_gimple_formal_tmp_rhs (t
);
124 /* Returns the appropriate RHS predicate for this LHS. */
127 rhs_predicate_for (tree lhs
)
129 if (is_gimple_formal_tmp_var (lhs
))
130 return is_gimple_formal_tmp_rhs
;
131 else if (is_gimple_reg (lhs
))
132 return is_gimple_reg_rhs
;
134 return is_gimple_mem_rhs
;
137 /* Return true if T is a valid LHS for a GIMPLE assignment expression. */
140 is_gimple_lvalue (tree t
)
142 return (is_gimple_addressable (t
)
143 || TREE_CODE (t
) == WITH_SIZE_EXPR
144 /* These are complex lvalues, but don't have addresses, so they
146 || TREE_CODE (t
) == BIT_FIELD_REF
);
149 /* Return true if T is a GIMPLE condition. */
152 is_gimple_condexpr (tree t
)
154 return (is_gimple_val (t
) || COMPARISON_CLASS_P (t
));
157 /* Return true if T is something whose address can be taken. */
160 is_gimple_addressable (tree t
)
162 return (is_gimple_id (t
) || handled_component_p (t
)
163 || INDIRECT_REF_P (t
));
166 /* Return true if T is function invariant. Or rather a restricted
167 form of function invariant. */
170 is_gimple_min_invariant (tree t
)
172 switch (TREE_CODE (t
))
175 return TREE_INVARIANT (t
);
189 /* Return true if T looks like a valid GIMPLE statement. */
192 is_gimple_stmt (tree t
)
194 enum tree_code code
= TREE_CODE (t
);
196 if (IS_EMPTY_STMT (t
))
203 /* These are only valid if they're void. */
204 return TREE_TYPE (t
) == NULL
|| VOID_TYPE_P (TREE_TYPE (t
));
210 case CASE_LABEL_EXPR
:
212 case TRY_FINALLY_EXPR
:
219 /* These are always void. */
224 /* These are valid regardless of their type. */
232 /* Return true if T is a variable. */
235 is_gimple_variable (tree t
)
237 return (TREE_CODE (t
) == VAR_DECL
238 || TREE_CODE (t
) == PARM_DECL
239 || TREE_CODE (t
) == RESULT_DECL
240 || TREE_CODE (t
) == SSA_NAME
);
243 /* Return true if T is a GIMPLE identifier (something with an address). */
246 is_gimple_id (tree t
)
248 return (is_gimple_variable (t
)
249 || TREE_CODE (t
) == FUNCTION_DECL
250 || TREE_CODE (t
) == LABEL_DECL
251 || TREE_CODE (t
) == CONST_DECL
252 /* Allow string constants, since they are addressable. */
253 || TREE_CODE (t
) == STRING_CST
);
256 /* Return true if TYPE is a suitable type for a scalar register variable. */
259 is_gimple_reg_type (tree type
)
261 return !AGGREGATE_TYPE_P (type
);
264 /* Return true if T is a non-aggregate register variable. */
267 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
);
308 /* Some compiler temporaries are created to be used exclusively in
309 virtual operands (currently memory tags and sub-variables).
310 These variables should never be considered GIMPLE registers. */
311 if (DECL_ARTIFICIAL (t
) && (ann
= var_ann (t
)) != NULL
)
312 return ann
->mem_tag_kind
== NOT_A_TAG
;
318 /* Returns true if T is a GIMPLE formal temporary variable. */
321 is_gimple_formal_tmp_var (tree t
)
323 if (TREE_CODE (t
) == SSA_NAME
)
326 return TREE_CODE (t
) == VAR_DECL
&& DECL_GIMPLE_FORMAL_TEMP_P (t
);
329 /* Returns true if T is a GIMPLE formal temporary register variable. */
332 is_gimple_formal_tmp_reg (tree t
)
334 /* The intent of this is to get hold of a value that won't change.
335 An SSA_NAME qualifies no matter if its of a user variable or not. */
336 if (TREE_CODE (t
) == SSA_NAME
)
339 /* We don't know the lifetime characteristics of user variables. */
340 if (!is_gimple_formal_tmp_var (t
))
343 /* Finally, it must be capable of being placed in a register. */
344 return is_gimple_reg (t
);
347 /* Return true if T is a GIMPLE variable whose address is not needed. */
350 is_gimple_non_addressable (tree t
)
352 if (TREE_CODE (t
) == SSA_NAME
)
353 t
= SSA_NAME_VAR (t
);
355 return (is_gimple_variable (t
) && ! needs_to_live_in_memory (t
));
358 /* Return true if T is a GIMPLE rvalue, i.e. an identifier or a constant. */
361 is_gimple_val (tree t
)
363 /* Make loads from volatiles and memory vars explicit. */
364 if (is_gimple_variable (t
)
365 && is_gimple_reg_type (TREE_TYPE (t
))
366 && !is_gimple_reg (t
))
369 /* FIXME make these decls. That can happen only when we expose the
370 entire landing-pad construct at the tree level. */
371 if (TREE_CODE (t
) == EXC_PTR_EXPR
|| TREE_CODE (t
) == FILTER_EXPR
)
374 return (is_gimple_variable (t
) || is_gimple_min_invariant (t
));
377 /* Similarly, but accept hard registers as inputs to asm statements. */
380 is_gimple_asm_val (tree t
)
382 if (TREE_CODE (t
) == VAR_DECL
&& DECL_HARD_REGISTER (t
))
385 return is_gimple_val (t
);
388 /* Return true if T is a GIMPLE minimal lvalue. */
391 is_gimple_min_lval (tree t
)
393 return (is_gimple_id (t
)
394 || TREE_CODE (t
) == INDIRECT_REF
);
397 /* Return true if T is a typecast operation. */
400 is_gimple_cast (tree t
)
402 return (TREE_CODE (t
) == NOP_EXPR
403 || TREE_CODE (t
) == CONVERT_EXPR
404 || TREE_CODE (t
) == FIX_TRUNC_EXPR
405 || TREE_CODE (t
) == FIX_CEIL_EXPR
406 || TREE_CODE (t
) == FIX_FLOOR_EXPR
407 || TREE_CODE (t
) == FIX_ROUND_EXPR
);
410 /* Return true if T is a valid op0 of a CALL_EXPR. */
413 is_gimple_call_addr (tree t
)
415 return (TREE_CODE (t
) == OBJ_TYPE_REF
416 || is_gimple_val (t
));
419 /* If T makes a function call, return the corresponding CALL_EXPR operand.
420 Otherwise, return NULL_TREE. */
423 get_call_expr_in (tree t
)
425 if (TREE_CODE (t
) == MODIFY_EXPR
)
426 t
= TREE_OPERAND (t
, 1);
427 if (TREE_CODE (t
) == WITH_SIZE_EXPR
)
428 t
= TREE_OPERAND (t
, 0);
429 if (TREE_CODE (t
) == CALL_EXPR
)
434 /* Given a memory reference expression T, return its base address.
435 The base address of a memory reference expression is the main
436 object being referenced. For instance, the base address for
437 'array[i].fld[j]' is 'array'. You can think of this as stripping
438 away the offset part from a memory address.
440 This function calls handled_component_p to strip away all the inner
441 parts of the memory reference until it reaches the base object. */
444 get_base_address (tree t
)
446 while (handled_component_p (t
))
447 t
= TREE_OPERAND (t
, 0);
450 || TREE_CODE (t
) == STRING_CST
451 || TREE_CODE (t
) == CONSTRUCTOR
452 || INDIRECT_REF_P (t
))
459 recalculate_side_effects (tree t
)
461 enum tree_code code
= TREE_CODE (t
);
462 int len
= TREE_CODE_LENGTH (code
);
465 switch (TREE_CODE_CLASS (code
))
473 case PREDECREMENT_EXPR
:
474 case PREINCREMENT_EXPR
:
475 case POSTDECREMENT_EXPR
:
476 case POSTINCREMENT_EXPR
:
477 /* All of these have side-effects, no matter what their
486 case tcc_comparison
: /* a comparison expression */
487 case tcc_unary
: /* a unary arithmetic expression */
488 case tcc_binary
: /* a binary arithmetic expression */
489 case tcc_reference
: /* a reference */
490 TREE_SIDE_EFFECTS (t
) = TREE_THIS_VOLATILE (t
);
491 for (i
= 0; i
< len
; ++i
)
493 tree op
= TREE_OPERAND (t
, i
);
494 if (op
&& TREE_SIDE_EFFECTS (op
))
495 TREE_SIDE_EFFECTS (t
) = 1;
500 /* Can never be used with non-expressions. */