1 /* Tree based points-to analysis
2 Copyright (C) 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
3 Contributed by Daniel Berlin <dberlin@dberlin.org>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
23 #include "coretypes.h"
31 #include "hard-reg-set.h"
32 #include "basic-block.h"
35 #include "tree-flow.h"
36 #include "tree-inline.h"
38 #include "diagnostic.h"
44 #include "tree-pass.h"
46 #include "alloc-pool.h"
47 #include "splay-tree.h"
51 #include "pointer-set.h"
53 /* The idea behind this analyzer is to generate set constraints from the
54 program, then solve the resulting constraints in order to generate the
57 Set constraints are a way of modeling program analysis problems that
58 involve sets. They consist of an inclusion constraint language,
59 describing the variables (each variable is a set) and operations that
60 are involved on the variables, and a set of rules that derive facts
61 from these operations. To solve a system of set constraints, you derive
62 all possible facts under the rules, which gives you the correct sets
65 See "Efficient Field-sensitive pointer analysis for C" by "David
66 J. Pearce and Paul H. J. Kelly and Chris Hankin, at
67 http://citeseer.ist.psu.edu/pearce04efficient.html
69 Also see "Ultra-fast Aliasing Analysis using CLA: A Million Lines
70 of C Code in a Second" by ""Nevin Heintze and Olivier Tardieu" at
71 http://citeseer.ist.psu.edu/heintze01ultrafast.html
73 There are three types of real constraint expressions, DEREF,
74 ADDRESSOF, and SCALAR. Each constraint expression consists
75 of a constraint type, a variable, and an offset.
77 SCALAR is a constraint expression type used to represent x, whether
78 it appears on the LHS or the RHS of a statement.
79 DEREF is a constraint expression type used to represent *x, whether
80 it appears on the LHS or the RHS of a statement.
81 ADDRESSOF is a constraint expression used to represent &x, whether
82 it appears on the LHS or the RHS of a statement.
84 Each pointer variable in the program is assigned an integer id, and
85 each field of a structure variable is assigned an integer id as well.
87 Structure variables are linked to their list of fields through a "next
88 field" in each variable that points to the next field in offset
90 Each variable for a structure field has
92 1. "size", that tells the size in bits of that field.
93 2. "fullsize, that tells the size in bits of the entire structure.
94 3. "offset", that tells the offset in bits from the beginning of the
95 structure to this field.
107 foo.a -> id 1, size 32, offset 0, fullsize 64, next foo.b
108 foo.b -> id 2, size 32, offset 32, fullsize 64, next NULL
109 bar -> id 3, size 32, offset 0, fullsize 32, next NULL
112 In order to solve the system of set constraints, the following is
115 1. Each constraint variable x has a solution set associated with it,
118 2. Constraints are separated into direct, copy, and complex.
119 Direct constraints are ADDRESSOF constraints that require no extra
120 processing, such as P = &Q
121 Copy constraints are those of the form P = Q.
122 Complex constraints are all the constraints involving dereferences
123 and offsets (including offsetted copies).
125 3. All direct constraints of the form P = &Q are processed, such
126 that Q is added to Sol(P)
128 4. All complex constraints for a given constraint variable are stored in a
129 linked list attached to that variable's node.
131 5. A directed graph is built out of the copy constraints. Each
132 constraint variable is a node in the graph, and an edge from
133 Q to P is added for each copy constraint of the form P = Q
135 6. The graph is then walked, and solution sets are
136 propagated along the copy edges, such that an edge from Q to P
137 causes Sol(P) <- Sol(P) union Sol(Q).
139 7. As we visit each node, all complex constraints associated with
140 that node are processed by adding appropriate copy edges to the graph, or the
141 appropriate variables to the solution set.
143 8. The process of walking the graph is iterated until no solution
146 Prior to walking the graph in steps 6 and 7, We perform static
147 cycle elimination on the constraint graph, as well
148 as off-line variable substitution.
150 TODO: Adding offsets to pointer-to-structures can be handled (IE not punted
151 on and turned into anything), but isn't. You can just see what offset
152 inside the pointed-to struct it's going to access.
154 TODO: Constant bounded arrays can be handled as if they were structs of the
155 same number of elements.
157 TODO: Modeling heap and incoming pointers becomes much better if we
158 add fields to them as we discover them, which we could do.
160 TODO: We could handle unions, but to be honest, it's probably not
161 worth the pain or slowdown. */
163 static GTY ((if_marked ("tree_map_marked_p"), param_is (struct tree_map)))
164 htab_t heapvar_for_stmt;
166 static bool use_field_sensitive = true;
167 static int in_ipa_mode = 0;
169 /* Used for predecessor bitmaps. */
170 static bitmap_obstack predbitmap_obstack;
172 /* Used for points-to sets. */
173 static bitmap_obstack pta_obstack;
175 /* Used for oldsolution members of variables. */
176 static bitmap_obstack oldpta_obstack;
178 /* Used for per-solver-iteration bitmaps. */
179 static bitmap_obstack iteration_obstack;
181 static unsigned int create_variable_info_for (tree, const char *);
182 typedef struct constraint_graph *constraint_graph_t;
183 static void unify_nodes (constraint_graph_t, unsigned int, unsigned int, bool);
186 typedef struct constraint *constraint_t;
188 DEF_VEC_P(constraint_t);
189 DEF_VEC_ALLOC_P(constraint_t,heap);
191 #define EXECUTE_IF_IN_NONNULL_BITMAP(a, b, c, d) \
193 EXECUTE_IF_SET_IN_BITMAP (a, b, c, d)
195 static struct constraint_stats
197 unsigned int total_vars;
198 unsigned int nonpointer_vars;
199 unsigned int unified_vars_static;
200 unsigned int unified_vars_dynamic;
201 unsigned int iterations;
202 unsigned int num_edges;
203 unsigned int num_implicit_edges;
204 unsigned int points_to_sets_created;
209 /* ID of this variable */
212 /* True if this is a variable created by the constraint analysis, such as
213 heap variables and constraints we had to break up. */
214 unsigned int is_artificial_var:1;
216 /* True if this is a special variable whose solution set should not be
218 unsigned int is_special_var:1;
220 /* True for variables whose size is not known or variable. */
221 unsigned int is_unknown_size_var:1;
223 /* True for (sub-)fields that represent a whole variable. */
224 unsigned int is_full_var : 1;
226 /* True if this is a heap variable. */
227 unsigned int is_heap_var:1;
229 /* True if this field may contain pointers. */
230 unsigned int may_have_pointers : 1;
232 /* A link to the variable for the next field in this structure. */
233 struct variable_info *next;
235 /* Offset of this variable, in bits, from the base variable */
236 unsigned HOST_WIDE_INT offset;
238 /* Size of the variable, in bits. */
239 unsigned HOST_WIDE_INT size;
241 /* Full size of the base variable, in bits. */
242 unsigned HOST_WIDE_INT fullsize;
244 /* Name of this variable */
247 /* Tree that this variable is associated with. */
250 /* Points-to set for this variable. */
253 /* Old points-to set for this variable. */
256 typedef struct variable_info *varinfo_t;
258 static varinfo_t first_vi_for_offset (varinfo_t, unsigned HOST_WIDE_INT);
259 static varinfo_t first_or_preceding_vi_for_offset (varinfo_t,
260 unsigned HOST_WIDE_INT);
261 static varinfo_t lookup_vi_for_tree (tree);
263 /* Pool of variable info structures. */
264 static alloc_pool variable_info_pool;
266 DEF_VEC_P(varinfo_t);
268 DEF_VEC_ALLOC_P(varinfo_t, heap);
270 /* Table of variable info structures for constraint variables.
271 Indexed directly by variable info id. */
272 static VEC(varinfo_t,heap) *varmap;
274 /* Return the varmap element N */
276 static inline varinfo_t
277 get_varinfo (unsigned int n)
279 return VEC_index (varinfo_t, varmap, n);
282 /* Static IDs for the special variables. */
283 enum { nothing_id = 0, anything_id = 1, readonly_id = 2,
284 escaped_id = 3, nonlocal_id = 4, callused_id = 5,
285 storedanything_id = 6, integer_id = 7 };
287 /* Variable that represents the unknown pointer. */
288 static varinfo_t var_anything;
289 static tree anything_tree;
291 /* Variable that represents the NULL pointer. */
292 static varinfo_t var_nothing;
293 static tree nothing_tree;
295 /* Variable that represents read only memory. */
296 static varinfo_t var_readonly;
297 static tree readonly_tree;
299 /* Variable that represents escaped memory. */
300 static varinfo_t var_escaped;
301 static tree escaped_tree;
303 /* Variable that represents nonlocal memory. */
304 static varinfo_t var_nonlocal;
305 static tree nonlocal_tree;
307 /* Variable that represents call-used memory. */
308 static varinfo_t var_callused;
309 static tree callused_tree;
311 /* Variable that represents variables that are stored to anything. */
312 static varinfo_t var_storedanything;
313 static tree storedanything_tree;
315 /* Variable that represents integers. This is used for when people do things
317 static varinfo_t var_integer;
318 static tree integer_tree;
320 /* Lookup a heap var for FROM, and return it if we find one. */
323 heapvar_lookup (tree from)
325 struct tree_map *h, in;
328 h = (struct tree_map *) htab_find_with_hash (heapvar_for_stmt, &in,
329 htab_hash_pointer (from));
335 /* Insert a mapping FROM->TO in the heap var for statement
339 heapvar_insert (tree from, tree to)
344 h = GGC_NEW (struct tree_map);
345 h->hash = htab_hash_pointer (from);
348 loc = htab_find_slot_with_hash (heapvar_for_stmt, h, h->hash, INSERT);
349 *(struct tree_map **) loc = h;
352 /* Return a new variable info structure consisting for a variable
353 named NAME, and using constraint graph node NODE. */
356 new_var_info (tree t, unsigned int id, const char *name)
358 varinfo_t ret = (varinfo_t) pool_alloc (variable_info_pool);
363 ret->is_artificial_var = false;
364 ret->is_heap_var = false;
365 ret->is_special_var = false;
366 ret->is_unknown_size_var = false;
367 ret->is_full_var = false;
368 ret->may_have_pointers = true;
369 ret->solution = BITMAP_ALLOC (&pta_obstack);
370 ret->oldsolution = BITMAP_ALLOC (&oldpta_obstack);
375 typedef enum {SCALAR, DEREF, ADDRESSOF} constraint_expr_type;
377 /* An expression that appears in a constraint. */
379 struct constraint_expr
381 /* Constraint type. */
382 constraint_expr_type type;
384 /* Variable we are referring to in the constraint. */
387 /* Offset, in bits, of this constraint from the beginning of
388 variables it ends up referring to.
390 IOW, in a deref constraint, we would deref, get the result set,
391 then add OFFSET to each member. */
392 HOST_WIDE_INT offset;
395 /* Use 0x8000... as special unknown offset. */
396 #define UNKNOWN_OFFSET ((HOST_WIDE_INT)-1 << (HOST_BITS_PER_WIDE_INT-1))
398 typedef struct constraint_expr ce_s;
400 DEF_VEC_ALLOC_O(ce_s, heap);
401 static void get_constraint_for_1 (tree, VEC(ce_s, heap) **, bool);
402 static void get_constraint_for (tree, VEC(ce_s, heap) **);
403 static void do_deref (VEC (ce_s, heap) **);
405 /* Our set constraints are made up of two constraint expressions, one
408 As described in the introduction, our set constraints each represent an
409 operation between set valued variables.
413 struct constraint_expr lhs;
414 struct constraint_expr rhs;
417 /* List of constraints that we use to build the constraint graph from. */
419 static VEC(constraint_t,heap) *constraints;
420 static alloc_pool constraint_pool;
424 DEF_VEC_ALLOC_I(int, heap);
426 /* The constraint graph is represented as an array of bitmaps
427 containing successor nodes. */
429 struct constraint_graph
431 /* Size of this graph, which may be different than the number of
432 nodes in the variable map. */
435 /* Explicit successors of each node. */
438 /* Implicit predecessors of each node (Used for variable
440 bitmap *implicit_preds;
442 /* Explicit predecessors of each node (Used for variable substitution). */
445 /* Indirect cycle representatives, or -1 if the node has no indirect
447 int *indirect_cycles;
449 /* Representative node for a node. rep[a] == a unless the node has
453 /* Equivalence class representative for a label. This is used for
454 variable substitution. */
457 /* Pointer equivalence label for a node. All nodes with the same
458 pointer equivalence label can be unified together at some point
459 (either during constraint optimization or after the constraint
463 /* Pointer equivalence representative for a label. This is used to
464 handle nodes that are pointer equivalent but not location
465 equivalent. We can unite these once the addressof constraints
466 are transformed into initial points-to sets. */
469 /* Pointer equivalence label for each node, used during variable
471 unsigned int *pointer_label;
473 /* Location equivalence label for each node, used during location
474 equivalence finding. */
475 unsigned int *loc_label;
477 /* Pointed-by set for each node, used during location equivalence
478 finding. This is pointed-by rather than pointed-to, because it
479 is constructed using the predecessor graph. */
482 /* Points to sets for pointer equivalence. This is *not* the actual
483 points-to sets for nodes. */
486 /* Bitmap of nodes where the bit is set if the node is a direct
487 node. Used for variable substitution. */
488 sbitmap direct_nodes;
490 /* Bitmap of nodes where the bit is set if the node is address
491 taken. Used for variable substitution. */
492 bitmap address_taken;
494 /* Vector of complex constraints for each graph node. Complex
495 constraints are those involving dereferences or offsets that are
497 VEC(constraint_t,heap) **complex;
500 static constraint_graph_t graph;
502 /* During variable substitution and the offline version of indirect
503 cycle finding, we create nodes to represent dereferences and
504 address taken constraints. These represent where these start and
506 #define FIRST_REF_NODE (VEC_length (varinfo_t, varmap))
507 #define LAST_REF_NODE (FIRST_REF_NODE + (FIRST_REF_NODE - 1))
509 /* Return the representative node for NODE, if NODE has been unioned
511 This function performs path compression along the way to finding
512 the representative. */
515 find (unsigned int node)
517 gcc_assert (node < graph->size);
518 if (graph->rep[node] != node)
519 return graph->rep[node] = find (graph->rep[node]);
523 /* Union the TO and FROM nodes to the TO nodes.
524 Note that at some point in the future, we may want to do
525 union-by-rank, in which case we are going to have to return the
526 node we unified to. */
529 unite (unsigned int to, unsigned int from)
531 gcc_assert (to < graph->size && from < graph->size);
532 if (to != from && graph->rep[from] != to)
534 graph->rep[from] = to;
540 /* Create a new constraint consisting of LHS and RHS expressions. */
543 new_constraint (const struct constraint_expr lhs,
544 const struct constraint_expr rhs)
546 constraint_t ret = (constraint_t) pool_alloc (constraint_pool);
552 /* Print out constraint C to FILE. */
555 dump_constraint (FILE *file, constraint_t c)
557 if (c->lhs.type == ADDRESSOF)
559 else if (c->lhs.type == DEREF)
561 fprintf (file, "%s", get_varinfo (c->lhs.var)->name);
562 if (c->lhs.offset == UNKNOWN_OFFSET)
563 fprintf (file, " + UNKNOWN");
564 else if (c->lhs.offset != 0)
565 fprintf (file, " + " HOST_WIDE_INT_PRINT_DEC, c->lhs.offset);
566 fprintf (file, " = ");
567 if (c->rhs.type == ADDRESSOF)
569 else if (c->rhs.type == DEREF)
571 fprintf (file, "%s", get_varinfo (c->rhs.var)->name);
572 if (c->rhs.offset == UNKNOWN_OFFSET)
573 fprintf (file, " + UNKNOWN");
574 else if (c->rhs.offset != 0)
575 fprintf (file, " + " HOST_WIDE_INT_PRINT_DEC, c->rhs.offset);
576 fprintf (file, "\n");
580 void debug_constraint (constraint_t);
581 void debug_constraints (void);
582 void debug_constraint_graph (void);
583 void debug_solution_for_var (unsigned int);
584 void debug_sa_points_to_info (void);
586 /* Print out constraint C to stderr. */
589 debug_constraint (constraint_t c)
591 dump_constraint (stderr, c);
594 /* Print out all constraints to FILE */
597 dump_constraints (FILE *file)
601 for (i = 0; VEC_iterate (constraint_t, constraints, i, c); i++)
602 dump_constraint (file, c);
605 /* Print out all constraints to stderr. */
608 debug_constraints (void)
610 dump_constraints (stderr);
613 /* Print out to FILE the edge in the constraint graph that is created by
614 constraint c. The edge may have a label, depending on the type of
615 constraint that it represents. If complex1, e.g: a = *b, then the label
616 is "=*", if complex2, e.g: *a = b, then the label is "*=", if
617 complex with an offset, e.g: a = b + 8, then the label is "+".
618 Otherwise the edge has no label. */
621 dump_constraint_edge (FILE *file, constraint_t c)
623 if (c->rhs.type != ADDRESSOF)
625 const char *src = get_varinfo (c->rhs.var)->name;
626 const char *dst = get_varinfo (c->lhs.var)->name;
627 fprintf (file, " \"%s\" -> \"%s\" ", src, dst);
628 /* Due to preprocessing of constraints, instructions like *a = *b are
629 illegal; thus, we do not have to handle such cases. */
630 if (c->lhs.type == DEREF)
631 fprintf (file, " [ label=\"*=\" ] ;\n");
632 else if (c->rhs.type == DEREF)
633 fprintf (file, " [ label=\"=*\" ] ;\n");
636 /* We must check the case where the constraint is an offset.
637 In this case, it is treated as a complex constraint. */
638 if (c->rhs.offset != c->lhs.offset)
639 fprintf (file, " [ label=\"+\" ] ;\n");
641 fprintf (file, " ;\n");
646 /* Print the constraint graph in dot format. */
649 dump_constraint_graph (FILE *file)
651 unsigned int i=0, size;
654 /* Only print the graph if it has already been initialized: */
658 /* Print the constraints used to produce the constraint graph. The
659 constraints will be printed as comments in the dot file: */
660 fprintf (file, "\n\n/* Constraints used in the constraint graph:\n");
661 dump_constraints (file);
662 fprintf (file, "*/\n");
664 /* Prints the header of the dot file: */
665 fprintf (file, "\n\n// The constraint graph in dot format:\n");
666 fprintf (file, "strict digraph {\n");
667 fprintf (file, " node [\n shape = box\n ]\n");
668 fprintf (file, " edge [\n fontsize = \"12\"\n ]\n");
669 fprintf (file, "\n // List of nodes in the constraint graph:\n");
671 /* The next lines print the nodes in the graph. In order to get the
672 number of nodes in the graph, we must choose the minimum between the
673 vector VEC (varinfo_t, varmap) and graph->size. If the graph has not
674 yet been initialized, then graph->size == 0, otherwise we must only
675 read nodes that have an entry in VEC (varinfo_t, varmap). */
676 size = VEC_length (varinfo_t, varmap);
677 size = size < graph->size ? size : graph->size;
678 for (i = 0; i < size; i++)
680 const char *name = get_varinfo (graph->rep[i])->name;
681 fprintf (file, " \"%s\" ;\n", name);
684 /* Go over the list of constraints printing the edges in the constraint
686 fprintf (file, "\n // The constraint edges:\n");
687 for (i = 0; VEC_iterate (constraint_t, constraints, i, c); i++)
689 dump_constraint_edge (file, c);
691 /* Prints the tail of the dot file. By now, only the closing bracket. */
692 fprintf (file, "}\n\n\n");
695 /* Print out the constraint graph to stderr. */
698 debug_constraint_graph (void)
700 dump_constraint_graph (stderr);
705 The solver is a simple worklist solver, that works on the following
708 sbitmap changed_nodes = all zeroes;
710 For each node that is not already collapsed:
712 set bit in changed nodes
714 while (changed_count > 0)
716 compute topological ordering for constraint graph
718 find and collapse cycles in the constraint graph (updating
719 changed if necessary)
721 for each node (n) in the graph in topological order:
724 Process each complex constraint associated with the node,
725 updating changed if necessary.
727 For each outgoing edge from n, propagate the solution from n to
728 the destination of the edge, updating changed as necessary.
732 /* Return true if two constraint expressions A and B are equal. */
735 constraint_expr_equal (struct constraint_expr a, struct constraint_expr b)
737 return a.type == b.type && a.var == b.var && a.offset == b.offset;
740 /* Return true if constraint expression A is less than constraint expression
741 B. This is just arbitrary, but consistent, in order to give them an
745 constraint_expr_less (struct constraint_expr a, struct constraint_expr b)
747 if (a.type == b.type)
750 return a.offset < b.offset;
752 return a.var < b.var;
755 return a.type < b.type;
758 /* Return true if constraint A is less than constraint B. This is just
759 arbitrary, but consistent, in order to give them an ordering. */
762 constraint_less (const constraint_t a, const constraint_t b)
764 if (constraint_expr_less (a->lhs, b->lhs))
766 else if (constraint_expr_less (b->lhs, a->lhs))
769 return constraint_expr_less (a->rhs, b->rhs);
772 /* Return true if two constraints A and B are equal. */
775 constraint_equal (struct constraint a, struct constraint b)
777 return constraint_expr_equal (a.lhs, b.lhs)
778 && constraint_expr_equal (a.rhs, b.rhs);
782 /* Find a constraint LOOKFOR in the sorted constraint vector VEC */
785 constraint_vec_find (VEC(constraint_t,heap) *vec,
786 struct constraint lookfor)
794 place = VEC_lower_bound (constraint_t, vec, &lookfor, constraint_less);
795 if (place >= VEC_length (constraint_t, vec))
797 found = VEC_index (constraint_t, vec, place);
798 if (!constraint_equal (*found, lookfor))
803 /* Union two constraint vectors, TO and FROM. Put the result in TO. */
806 constraint_set_union (VEC(constraint_t,heap) **to,
807 VEC(constraint_t,heap) **from)
812 for (i = 0; VEC_iterate (constraint_t, *from, i, c); i++)
814 if (constraint_vec_find (*to, *c) == NULL)
816 unsigned int place = VEC_lower_bound (constraint_t, *to, c,
818 VEC_safe_insert (constraint_t, heap, *to, place, c);
823 /* Expands the solution in SET to all sub-fields of variables included.
824 Union the expanded result into RESULT. */
827 solution_set_expand (bitmap result, bitmap set)
833 /* In a first pass record all variables we need to add all
834 sub-fields off. This avoids quadratic behavior. */
835 EXECUTE_IF_SET_IN_BITMAP (set, 0, j, bi)
837 varinfo_t v = get_varinfo (j);
838 if (v->is_artificial_var
841 v = lookup_vi_for_tree (v->decl);
843 vars = BITMAP_ALLOC (NULL);
844 bitmap_set_bit (vars, v->id);
847 /* In the second pass now do the addition to the solution and
848 to speed up solving add it to the delta as well. */
851 EXECUTE_IF_SET_IN_BITMAP (vars, 0, j, bi)
853 varinfo_t v = get_varinfo (j);
854 for (; v != NULL; v = v->next)
855 bitmap_set_bit (result, v->id);
861 /* Take a solution set SET, add OFFSET to each member of the set, and
862 overwrite SET with the result when done. */
865 solution_set_add (bitmap set, HOST_WIDE_INT offset)
867 bitmap result = BITMAP_ALLOC (&iteration_obstack);
871 /* If the offset is unknown we have to expand the solution to
873 if (offset == UNKNOWN_OFFSET)
875 solution_set_expand (set, set);
879 EXECUTE_IF_SET_IN_BITMAP (set, 0, i, bi)
881 varinfo_t vi = get_varinfo (i);
883 /* If this is a variable with just one field just set its bit
885 if (vi->is_artificial_var
886 || vi->is_unknown_size_var
888 bitmap_set_bit (result, i);
891 unsigned HOST_WIDE_INT fieldoffset = vi->offset + offset;
893 /* If the offset makes the pointer point to before the
894 variable use offset zero for the field lookup. */
896 && fieldoffset > vi->offset)
900 vi = first_or_preceding_vi_for_offset (vi, fieldoffset);
902 bitmap_set_bit (result, vi->id);
903 /* If the result is not exactly at fieldoffset include the next
904 field as well. See get_constraint_for_ptr_offset for more
906 if (vi->offset != fieldoffset
908 bitmap_set_bit (result, vi->next->id);
912 bitmap_copy (set, result);
913 BITMAP_FREE (result);
916 /* Union solution sets TO and FROM, and add INC to each member of FROM in the
920 set_union_with_increment (bitmap to, bitmap from, HOST_WIDE_INT inc)
923 return bitmap_ior_into (to, from);
929 tmp = BITMAP_ALLOC (&iteration_obstack);
930 bitmap_copy (tmp, from);
931 solution_set_add (tmp, inc);
932 res = bitmap_ior_into (to, tmp);
938 /* Insert constraint C into the list of complex constraints for graph
942 insert_into_complex (constraint_graph_t graph,
943 unsigned int var, constraint_t c)
945 VEC (constraint_t, heap) *complex = graph->complex[var];
946 unsigned int place = VEC_lower_bound (constraint_t, complex, c,
949 /* Only insert constraints that do not already exist. */
950 if (place >= VEC_length (constraint_t, complex)
951 || !constraint_equal (*c, *VEC_index (constraint_t, complex, place)))
952 VEC_safe_insert (constraint_t, heap, graph->complex[var], place, c);
956 /* Condense two variable nodes into a single variable node, by moving
957 all associated info from SRC to TO. */
960 merge_node_constraints (constraint_graph_t graph, unsigned int to,
966 gcc_assert (find (from) == to);
968 /* Move all complex constraints from src node into to node */
969 for (i = 0; VEC_iterate (constraint_t, graph->complex[from], i, c); i++)
971 /* In complex constraints for node src, we may have either
972 a = *src, and *src = a, or an offseted constraint which are
973 always added to the rhs node's constraints. */
975 if (c->rhs.type == DEREF)
977 else if (c->lhs.type == DEREF)
982 constraint_set_union (&graph->complex[to], &graph->complex[from]);
983 VEC_free (constraint_t, heap, graph->complex[from]);
984 graph->complex[from] = NULL;
988 /* Remove edges involving NODE from GRAPH. */
991 clear_edges_for_node (constraint_graph_t graph, unsigned int node)
993 if (graph->succs[node])
994 BITMAP_FREE (graph->succs[node]);
997 /* Merge GRAPH nodes FROM and TO into node TO. */
1000 merge_graph_nodes (constraint_graph_t graph, unsigned int to,
1003 if (graph->indirect_cycles[from] != -1)
1005 /* If we have indirect cycles with the from node, and we have
1006 none on the to node, the to node has indirect cycles from the
1007 from node now that they are unified.
1008 If indirect cycles exist on both, unify the nodes that they
1009 are in a cycle with, since we know they are in a cycle with
1011 if (graph->indirect_cycles[to] == -1)
1012 graph->indirect_cycles[to] = graph->indirect_cycles[from];
1015 /* Merge all the successor edges. */
1016 if (graph->succs[from])
1018 if (!graph->succs[to])
1019 graph->succs[to] = BITMAP_ALLOC (&pta_obstack);
1020 bitmap_ior_into (graph->succs[to],
1021 graph->succs[from]);
1024 clear_edges_for_node (graph, from);
1028 /* Add an indirect graph edge to GRAPH, going from TO to FROM if
1029 it doesn't exist in the graph already. */
1032 add_implicit_graph_edge (constraint_graph_t graph, unsigned int to,
1038 if (!graph->implicit_preds[to])
1039 graph->implicit_preds[to] = BITMAP_ALLOC (&predbitmap_obstack);
1041 if (bitmap_set_bit (graph->implicit_preds[to], from))
1042 stats.num_implicit_edges++;
1045 /* Add a predecessor graph edge to GRAPH, going from TO to FROM if
1046 it doesn't exist in the graph already.
1047 Return false if the edge already existed, true otherwise. */
1050 add_pred_graph_edge (constraint_graph_t graph, unsigned int to,
1053 if (!graph->preds[to])
1054 graph->preds[to] = BITMAP_ALLOC (&predbitmap_obstack);
1055 bitmap_set_bit (graph->preds[to], from);
1058 /* Add a graph edge to GRAPH, going from FROM to TO if
1059 it doesn't exist in the graph already.
1060 Return false if the edge already existed, true otherwise. */
1063 add_graph_edge (constraint_graph_t graph, unsigned int to,
1074 if (!graph->succs[from])
1075 graph->succs[from] = BITMAP_ALLOC (&pta_obstack);
1076 if (bitmap_set_bit (graph->succs[from], to))
1079 if (to < FIRST_REF_NODE && from < FIRST_REF_NODE)
1087 /* Return true if {DEST.SRC} is an existing graph edge in GRAPH. */
1090 valid_graph_edge (constraint_graph_t graph, unsigned int src,
1093 return (graph->succs[dest]
1094 && bitmap_bit_p (graph->succs[dest], src));
1097 /* Initialize the constraint graph structure to contain SIZE nodes. */
1100 init_graph (unsigned int size)
1104 graph = XCNEW (struct constraint_graph);
1106 graph->succs = XCNEWVEC (bitmap, graph->size);
1107 graph->indirect_cycles = XNEWVEC (int, graph->size);
1108 graph->rep = XNEWVEC (unsigned int, graph->size);
1109 graph->complex = XCNEWVEC (VEC(constraint_t, heap) *, size);
1110 graph->pe = XCNEWVEC (unsigned int, graph->size);
1111 graph->pe_rep = XNEWVEC (int, graph->size);
1113 for (j = 0; j < graph->size; j++)
1116 graph->pe_rep[j] = -1;
1117 graph->indirect_cycles[j] = -1;
1121 /* Build the constraint graph, adding only predecessor edges right now. */
1124 build_pred_graph (void)
1130 graph->implicit_preds = XCNEWVEC (bitmap, graph->size);
1131 graph->preds = XCNEWVEC (bitmap, graph->size);
1132 graph->pointer_label = XCNEWVEC (unsigned int, graph->size);
1133 graph->loc_label = XCNEWVEC (unsigned int, graph->size);
1134 graph->pointed_by = XCNEWVEC (bitmap, graph->size);
1135 graph->points_to = XCNEWVEC (bitmap, graph->size);
1136 graph->eq_rep = XNEWVEC (int, graph->size);
1137 graph->direct_nodes = sbitmap_alloc (graph->size);
1138 graph->address_taken = BITMAP_ALLOC (&predbitmap_obstack);
1139 sbitmap_zero (graph->direct_nodes);
1141 for (j = 0; j < FIRST_REF_NODE; j++)
1143 if (!get_varinfo (j)->is_special_var)
1144 SET_BIT (graph->direct_nodes, j);
1147 for (j = 0; j < graph->size; j++)
1148 graph->eq_rep[j] = -1;
1150 for (j = 0; j < VEC_length (varinfo_t, varmap); j++)
1151 graph->indirect_cycles[j] = -1;
1153 for (i = 0; VEC_iterate (constraint_t, constraints, i, c); i++)
1155 struct constraint_expr lhs = c->lhs;
1156 struct constraint_expr rhs = c->rhs;
1157 unsigned int lhsvar = lhs.var;
1158 unsigned int rhsvar = rhs.var;
1160 if (lhs.type == DEREF)
1163 if (rhs.offset == 0 && lhs.offset == 0 && rhs.type == SCALAR)
1164 add_pred_graph_edge (graph, FIRST_REF_NODE + lhsvar, rhsvar);
1166 else if (rhs.type == DEREF)
1169 if (rhs.offset == 0 && lhs.offset == 0 && lhs.type == SCALAR)
1170 add_pred_graph_edge (graph, lhsvar, FIRST_REF_NODE + rhsvar);
1172 RESET_BIT (graph->direct_nodes, lhsvar);
1174 else if (rhs.type == ADDRESSOF)
1179 if (graph->points_to[lhsvar] == NULL)
1180 graph->points_to[lhsvar] = BITMAP_ALLOC (&predbitmap_obstack);
1181 bitmap_set_bit (graph->points_to[lhsvar], rhsvar);
1183 if (graph->pointed_by[rhsvar] == NULL)
1184 graph->pointed_by[rhsvar] = BITMAP_ALLOC (&predbitmap_obstack);
1185 bitmap_set_bit (graph->pointed_by[rhsvar], lhsvar);
1187 /* Implicitly, *x = y */
1188 add_implicit_graph_edge (graph, FIRST_REF_NODE + lhsvar, rhsvar);
1190 /* All related variables are no longer direct nodes. */
1191 RESET_BIT (graph->direct_nodes, rhsvar);
1192 v = get_varinfo (rhsvar);
1193 if (!v->is_full_var)
1195 v = lookup_vi_for_tree (v->decl);
1198 RESET_BIT (graph->direct_nodes, v->id);
1203 bitmap_set_bit (graph->address_taken, rhsvar);
1205 else if (lhsvar > anything_id
1206 && lhsvar != rhsvar && lhs.offset == 0 && rhs.offset == 0)
1209 add_pred_graph_edge (graph, lhsvar, rhsvar);
1210 /* Implicitly, *x = *y */
1211 add_implicit_graph_edge (graph, FIRST_REF_NODE + lhsvar,
1212 FIRST_REF_NODE + rhsvar);
1214 else if (lhs.offset != 0 || rhs.offset != 0)
1216 if (rhs.offset != 0)
1217 RESET_BIT (graph->direct_nodes, lhs.var);
1218 else if (lhs.offset != 0)
1219 RESET_BIT (graph->direct_nodes, rhs.var);
1224 /* Build the constraint graph, adding successor edges. */
1227 build_succ_graph (void)
1232 for (i = 0; VEC_iterate (constraint_t, constraints, i, c); i++)
1234 struct constraint_expr lhs;
1235 struct constraint_expr rhs;
1236 unsigned int lhsvar;
1237 unsigned int rhsvar;
1244 lhsvar = find (lhs.var);
1245 rhsvar = find (rhs.var);
1247 if (lhs.type == DEREF)
1249 if (rhs.offset == 0 && lhs.offset == 0 && rhs.type == SCALAR)
1250 add_graph_edge (graph, FIRST_REF_NODE + lhsvar, rhsvar);
1252 else if (rhs.type == DEREF)
1254 if (rhs.offset == 0 && lhs.offset == 0 && lhs.type == SCALAR)
1255 add_graph_edge (graph, lhsvar, FIRST_REF_NODE + rhsvar);
1257 else if (rhs.type == ADDRESSOF)
1260 gcc_assert (find (rhs.var) == rhs.var);
1261 bitmap_set_bit (get_varinfo (lhsvar)->solution, rhsvar);
1263 else if (lhsvar > anything_id
1264 && lhsvar != rhsvar && lhs.offset == 0 && rhs.offset == 0)
1266 add_graph_edge (graph, lhsvar, rhsvar);
1270 /* Add edges from STOREDANYTHING to all non-direct nodes. */
1271 t = find (storedanything_id);
1272 for (i = integer_id + 1; i < FIRST_REF_NODE; ++i)
1274 if (!TEST_BIT (graph->direct_nodes, i))
1275 add_graph_edge (graph, find (i), t);
1280 /* Changed variables on the last iteration. */
1281 static unsigned int changed_count;
1282 static sbitmap changed;
1284 DEF_VEC_I(unsigned);
1285 DEF_VEC_ALLOC_I(unsigned,heap);
1288 /* Strongly Connected Component visitation info. */
1295 unsigned int *node_mapping;
1297 VEC(unsigned,heap) *scc_stack;
1301 /* Recursive routine to find strongly connected components in GRAPH.
1302 SI is the SCC info to store the information in, and N is the id of current
1303 graph node we are processing.
1305 This is Tarjan's strongly connected component finding algorithm, as
1306 modified by Nuutila to keep only non-root nodes on the stack.
1307 The algorithm can be found in "On finding the strongly connected
1308 connected components in a directed graph" by Esko Nuutila and Eljas
1309 Soisalon-Soininen, in Information Processing Letters volume 49,
1310 number 1, pages 9-14. */
1313 scc_visit (constraint_graph_t graph, struct scc_info *si, unsigned int n)
1317 unsigned int my_dfs;
1319 SET_BIT (si->visited, n);
1320 si->dfs[n] = si->current_index ++;
1321 my_dfs = si->dfs[n];
1323 /* Visit all the successors. */
1324 EXECUTE_IF_IN_NONNULL_BITMAP (graph->succs[n], 0, i, bi)
1328 if (i > LAST_REF_NODE)
1332 if (TEST_BIT (si->deleted, w))
1335 if (!TEST_BIT (si->visited, w))
1336 scc_visit (graph, si, w);
1338 unsigned int t = find (w);
1339 unsigned int nnode = find (n);
1340 gcc_assert (nnode == n);
1342 if (si->dfs[t] < si->dfs[nnode])
1343 si->dfs[n] = si->dfs[t];
1347 /* See if any components have been identified. */
1348 if (si->dfs[n] == my_dfs)
1350 if (VEC_length (unsigned, si->scc_stack) > 0
1351 && si->dfs[VEC_last (unsigned, si->scc_stack)] >= my_dfs)
1353 bitmap scc = BITMAP_ALLOC (NULL);
1354 bool have_ref_node = n >= FIRST_REF_NODE;
1355 unsigned int lowest_node;
1358 bitmap_set_bit (scc, n);
1360 while (VEC_length (unsigned, si->scc_stack) != 0
1361 && si->dfs[VEC_last (unsigned, si->scc_stack)] >= my_dfs)
1363 unsigned int w = VEC_pop (unsigned, si->scc_stack);
1365 bitmap_set_bit (scc, w);
1366 if (w >= FIRST_REF_NODE)
1367 have_ref_node = true;
1370 lowest_node = bitmap_first_set_bit (scc);
1371 gcc_assert (lowest_node < FIRST_REF_NODE);
1373 /* Collapse the SCC nodes into a single node, and mark the
1375 EXECUTE_IF_SET_IN_BITMAP (scc, 0, i, bi)
1377 if (i < FIRST_REF_NODE)
1379 if (unite (lowest_node, i))
1380 unify_nodes (graph, lowest_node, i, false);
1384 unite (lowest_node, i);
1385 graph->indirect_cycles[i - FIRST_REF_NODE] = lowest_node;
1389 SET_BIT (si->deleted, n);
1392 VEC_safe_push (unsigned, heap, si->scc_stack, n);
1395 /* Unify node FROM into node TO, updating the changed count if
1396 necessary when UPDATE_CHANGED is true. */
1399 unify_nodes (constraint_graph_t graph, unsigned int to, unsigned int from,
1400 bool update_changed)
1403 gcc_assert (to != from && find (to) == to);
1404 if (dump_file && (dump_flags & TDF_DETAILS))
1405 fprintf (dump_file, "Unifying %s to %s\n",
1406 get_varinfo (from)->name,
1407 get_varinfo (to)->name);
1410 stats.unified_vars_dynamic++;
1412 stats.unified_vars_static++;
1414 merge_graph_nodes (graph, to, from);
1415 merge_node_constraints (graph, to, from);
1417 /* Mark TO as changed if FROM was changed. If TO was already marked
1418 as changed, decrease the changed count. */
1420 if (update_changed && TEST_BIT (changed, from))
1422 RESET_BIT (changed, from);
1423 if (!TEST_BIT (changed, to))
1424 SET_BIT (changed, to);
1427 gcc_assert (changed_count > 0);
1431 if (get_varinfo (from)->solution)
1433 /* If the solution changes because of the merging, we need to mark
1434 the variable as changed. */
1435 if (bitmap_ior_into (get_varinfo (to)->solution,
1436 get_varinfo (from)->solution))
1438 if (update_changed && !TEST_BIT (changed, to))
1440 SET_BIT (changed, to);
1445 BITMAP_FREE (get_varinfo (from)->solution);
1446 BITMAP_FREE (get_varinfo (from)->oldsolution);
1448 if (stats.iterations > 0)
1450 BITMAP_FREE (get_varinfo (to)->oldsolution);
1451 get_varinfo (to)->oldsolution = BITMAP_ALLOC (&oldpta_obstack);
1454 if (valid_graph_edge (graph, to, to))
1456 if (graph->succs[to])
1457 bitmap_clear_bit (graph->succs[to], to);
1461 /* Information needed to compute the topological ordering of a graph. */
1465 /* sbitmap of visited nodes. */
1467 /* Array that stores the topological order of the graph, *in
1469 VEC(unsigned,heap) *topo_order;
1473 /* Initialize and return a topological info structure. */
1475 static struct topo_info *
1476 init_topo_info (void)
1478 size_t size = graph->size;
1479 struct topo_info *ti = XNEW (struct topo_info);
1480 ti->visited = sbitmap_alloc (size);
1481 sbitmap_zero (ti->visited);
1482 ti->topo_order = VEC_alloc (unsigned, heap, 1);
1487 /* Free the topological sort info pointed to by TI. */
1490 free_topo_info (struct topo_info *ti)
1492 sbitmap_free (ti->visited);
1493 VEC_free (unsigned, heap, ti->topo_order);
1497 /* Visit the graph in topological order, and store the order in the
1498 topo_info structure. */
1501 topo_visit (constraint_graph_t graph, struct topo_info *ti,
1507 SET_BIT (ti->visited, n);
1509 if (graph->succs[n])
1510 EXECUTE_IF_SET_IN_BITMAP (graph->succs[n], 0, j, bi)
1512 if (!TEST_BIT (ti->visited, j))
1513 topo_visit (graph, ti, j);
1516 VEC_safe_push (unsigned, heap, ti->topo_order, n);
1519 /* Process a constraint C that represents x = *(y + off), using DELTA as the
1520 starting solution for y. */
1523 do_sd_constraint (constraint_graph_t graph, constraint_t c,
1526 unsigned int lhs = c->lhs.var;
1528 bitmap sol = get_varinfo (lhs)->solution;
1531 HOST_WIDE_INT roffset = c->rhs.offset;
1533 /* Our IL does not allow this. */
1534 gcc_assert (c->lhs.offset == 0);
1536 /* If the solution of Y contains anything it is good enough to transfer
1538 if (bitmap_bit_p (delta, anything_id))
1540 flag |= bitmap_set_bit (sol, anything_id);
1544 /* If we do not know at with offset the rhs is dereferenced compute
1545 the reachability set of DELTA, conservatively assuming it is
1546 dereferenced at all valid offsets. */
1547 if (roffset == UNKNOWN_OFFSET)
1549 solution_set_expand (delta, delta);
1550 /* No further offset processing is necessary. */
1554 /* For each variable j in delta (Sol(y)), add
1555 an edge in the graph from j to x, and union Sol(j) into Sol(x). */
1556 EXECUTE_IF_SET_IN_BITMAP (delta, 0, j, bi)
1558 varinfo_t v = get_varinfo (j);
1559 HOST_WIDE_INT fieldoffset = v->offset + roffset;
1563 fieldoffset = v->offset;
1564 else if (roffset != 0)
1565 v = first_vi_for_offset (v, fieldoffset);
1566 /* If the access is outside of the variable we can ignore it. */
1574 /* Adding edges from the special vars is pointless.
1575 They don't have sets that can change. */
1576 if (get_varinfo (t)->is_special_var)
1577 flag |= bitmap_ior_into (sol, get_varinfo (t)->solution);
1578 /* Merging the solution from ESCAPED needlessly increases
1579 the set. Use ESCAPED as representative instead. */
1580 else if (v->id == escaped_id)
1581 flag |= bitmap_set_bit (sol, escaped_id);
1582 else if (add_graph_edge (graph, lhs, t))
1583 flag |= bitmap_ior_into (sol, get_varinfo (t)->solution);
1585 /* If the variable is not exactly at the requested offset
1586 we have to include the next one. */
1587 if (v->offset == (unsigned HOST_WIDE_INT)fieldoffset
1592 fieldoffset = v->offset;
1598 /* If the LHS solution changed, mark the var as changed. */
1601 get_varinfo (lhs)->solution = sol;
1602 if (!TEST_BIT (changed, lhs))
1604 SET_BIT (changed, lhs);
1610 /* Process a constraint C that represents *(x + off) = y using DELTA
1611 as the starting solution for x. */
1614 do_ds_constraint (constraint_t c, bitmap delta)
1616 unsigned int rhs = c->rhs.var;
1617 bitmap sol = get_varinfo (rhs)->solution;
1620 HOST_WIDE_INT loff = c->lhs.offset;
1622 /* Our IL does not allow this. */
1623 gcc_assert (c->rhs.offset == 0);
1625 /* If the solution of y contains ANYTHING simply use the ANYTHING
1626 solution. This avoids needlessly increasing the points-to sets. */
1627 if (bitmap_bit_p (sol, anything_id))
1628 sol = get_varinfo (find (anything_id))->solution;
1630 /* If the solution for x contains ANYTHING we have to merge the
1631 solution of y into all pointer variables which we do via
1633 if (bitmap_bit_p (delta, anything_id))
1635 unsigned t = find (storedanything_id);
1636 if (add_graph_edge (graph, t, rhs))
1638 if (bitmap_ior_into (get_varinfo (t)->solution, sol))
1640 if (!TEST_BIT (changed, t))
1642 SET_BIT (changed, t);
1650 /* If we do not know at with offset the rhs is dereferenced compute
1651 the reachability set of DELTA, conservatively assuming it is
1652 dereferenced at all valid offsets. */
1653 if (loff == UNKNOWN_OFFSET)
1655 solution_set_expand (delta, delta);
1659 /* For each member j of delta (Sol(x)), add an edge from y to j and
1660 union Sol(y) into Sol(j) */
1661 EXECUTE_IF_SET_IN_BITMAP (delta, 0, j, bi)
1663 varinfo_t v = get_varinfo (j);
1665 HOST_WIDE_INT fieldoffset = v->offset + loff;
1667 if (v->is_special_var)
1671 fieldoffset = v->offset;
1673 v = first_vi_for_offset (v, fieldoffset);
1674 /* If the access is outside of the variable we can ignore it. */
1680 if (v->may_have_pointers)
1683 if (add_graph_edge (graph, t, rhs))
1685 if (bitmap_ior_into (get_varinfo (t)->solution, sol))
1688 sol = get_varinfo (rhs)->solution;
1689 if (!TEST_BIT (changed, t))
1691 SET_BIT (changed, t);
1698 /* If the variable is not exactly at the requested offset
1699 we have to include the next one. */
1700 if (v->offset == (unsigned HOST_WIDE_INT)fieldoffset
1705 fieldoffset = v->offset;
1711 /* Handle a non-simple (simple meaning requires no iteration),
1712 constraint (IE *x = &y, x = *y, *x = y, and x = y with offsets involved). */
1715 do_complex_constraint (constraint_graph_t graph, constraint_t c, bitmap delta)
1717 if (c->lhs.type == DEREF)
1719 if (c->rhs.type == ADDRESSOF)
1726 do_ds_constraint (c, delta);
1729 else if (c->rhs.type == DEREF)
1732 if (!(get_varinfo (c->lhs.var)->is_special_var))
1733 do_sd_constraint (graph, c, delta);
1741 gcc_assert (c->rhs.type == SCALAR && c->lhs.type == SCALAR);
1742 solution = get_varinfo (c->rhs.var)->solution;
1743 tmp = get_varinfo (c->lhs.var)->solution;
1745 flag = set_union_with_increment (tmp, solution, c->rhs.offset);
1749 get_varinfo (c->lhs.var)->solution = tmp;
1750 if (!TEST_BIT (changed, c->lhs.var))
1752 SET_BIT (changed, c->lhs.var);
1759 /* Initialize and return a new SCC info structure. */
1761 static struct scc_info *
1762 init_scc_info (size_t size)
1764 struct scc_info *si = XNEW (struct scc_info);
1767 si->current_index = 0;
1768 si->visited = sbitmap_alloc (size);
1769 sbitmap_zero (si->visited);
1770 si->deleted = sbitmap_alloc (size);
1771 sbitmap_zero (si->deleted);
1772 si->node_mapping = XNEWVEC (unsigned int, size);
1773 si->dfs = XCNEWVEC (unsigned int, size);
1775 for (i = 0; i < size; i++)
1776 si->node_mapping[i] = i;
1778 si->scc_stack = VEC_alloc (unsigned, heap, 1);
1782 /* Free an SCC info structure pointed to by SI */
1785 free_scc_info (struct scc_info *si)
1787 sbitmap_free (si->visited);
1788 sbitmap_free (si->deleted);
1789 free (si->node_mapping);
1791 VEC_free (unsigned, heap, si->scc_stack);
1796 /* Find indirect cycles in GRAPH that occur, using strongly connected
1797 components, and note them in the indirect cycles map.
1799 This technique comes from Ben Hardekopf and Calvin Lin,
1800 "It Pays to be Lazy: Fast and Accurate Pointer Analysis for Millions of
1801 Lines of Code", submitted to PLDI 2007. */
1804 find_indirect_cycles (constraint_graph_t graph)
1807 unsigned int size = graph->size;
1808 struct scc_info *si = init_scc_info (size);
1810 for (i = 0; i < MIN (LAST_REF_NODE, size); i ++ )
1811 if (!TEST_BIT (si->visited, i) && find (i) == i)
1812 scc_visit (graph, si, i);
1817 /* Compute a topological ordering for GRAPH, and store the result in the
1818 topo_info structure TI. */
1821 compute_topo_order (constraint_graph_t graph,
1822 struct topo_info *ti)
1825 unsigned int size = graph->size;
1827 for (i = 0; i != size; ++i)
1828 if (!TEST_BIT (ti->visited, i) && find (i) == i)
1829 topo_visit (graph, ti, i);
1832 /* Structure used to for hash value numbering of pointer equivalence
1835 typedef struct equiv_class_label
1838 unsigned int equivalence_class;
1840 } *equiv_class_label_t;
1841 typedef const struct equiv_class_label *const_equiv_class_label_t;
1843 /* A hashtable for mapping a bitmap of labels->pointer equivalence
1845 static htab_t pointer_equiv_class_table;
1847 /* A hashtable for mapping a bitmap of labels->location equivalence
1849 static htab_t location_equiv_class_table;
1851 /* Hash function for a equiv_class_label_t */
1854 equiv_class_label_hash (const void *p)
1856 const_equiv_class_label_t const ecl = (const_equiv_class_label_t) p;
1857 return ecl->hashcode;
1860 /* Equality function for two equiv_class_label_t's. */
1863 equiv_class_label_eq (const void *p1, const void *p2)
1865 const_equiv_class_label_t const eql1 = (const_equiv_class_label_t) p1;
1866 const_equiv_class_label_t const eql2 = (const_equiv_class_label_t) p2;
1867 return (eql1->hashcode == eql2->hashcode
1868 && bitmap_equal_p (eql1->labels, eql2->labels));
1871 /* Lookup a equivalence class in TABLE by the bitmap of LABELS it
1875 equiv_class_lookup (htab_t table, bitmap labels)
1878 struct equiv_class_label ecl;
1880 ecl.labels = labels;
1881 ecl.hashcode = bitmap_hash (labels);
1883 slot = htab_find_slot_with_hash (table, &ecl,
1884 ecl.hashcode, NO_INSERT);
1888 return ((equiv_class_label_t) *slot)->equivalence_class;
1892 /* Add an equivalence class named EQUIVALENCE_CLASS with labels LABELS
1896 equiv_class_add (htab_t table, unsigned int equivalence_class,
1900 equiv_class_label_t ecl = XNEW (struct equiv_class_label);
1902 ecl->labels = labels;
1903 ecl->equivalence_class = equivalence_class;
1904 ecl->hashcode = bitmap_hash (labels);
1906 slot = htab_find_slot_with_hash (table, ecl,
1907 ecl->hashcode, INSERT);
1908 gcc_assert (!*slot);
1909 *slot = (void *) ecl;
1912 /* Perform offline variable substitution.
1914 This is a worst case quadratic time way of identifying variables
1915 that must have equivalent points-to sets, including those caused by
1916 static cycles, and single entry subgraphs, in the constraint graph.
1918 The technique is described in "Exploiting Pointer and Location
1919 Equivalence to Optimize Pointer Analysis. In the 14th International
1920 Static Analysis Symposium (SAS), August 2007." It is known as the
1921 "HU" algorithm, and is equivalent to value numbering the collapsed
1922 constraint graph including evaluating unions.
1924 The general method of finding equivalence classes is as follows:
1925 Add fake nodes (REF nodes) and edges for *a = b and a = *b constraints.
1926 Initialize all non-REF nodes to be direct nodes.
1927 For each constraint a = a U {b}, we set pts(a) = pts(a) u {fresh
1929 For each constraint containing the dereference, we also do the same
1932 We then compute SCC's in the graph and unify nodes in the same SCC,
1935 For each non-collapsed node x:
1936 Visit all unvisited explicit incoming edges.
1937 Ignoring all non-pointers, set pts(x) = Union of pts(a) for y
1939 Lookup the equivalence class for pts(x).
1940 If we found one, equivalence_class(x) = found class.
1941 Otherwise, equivalence_class(x) = new class, and new_class is
1942 added to the lookup table.
1944 All direct nodes with the same equivalence class can be replaced
1945 with a single representative node.
1946 All unlabeled nodes (label == 0) are not pointers and all edges
1947 involving them can be eliminated.
1948 We perform these optimizations during rewrite_constraints
1950 In addition to pointer equivalence class finding, we also perform
1951 location equivalence class finding. This is the set of variables
1952 that always appear together in points-to sets. We use this to
1953 compress the size of the points-to sets. */
1955 /* Current maximum pointer equivalence class id. */
1956 static int pointer_equiv_class;
1958 /* Current maximum location equivalence class id. */
1959 static int location_equiv_class;
1961 /* Recursive routine to find strongly connected components in GRAPH,
1962 and label it's nodes with DFS numbers. */
1965 condense_visit (constraint_graph_t graph, struct scc_info *si, unsigned int n)
1969 unsigned int my_dfs;
1971 gcc_assert (si->node_mapping[n] == n);
1972 SET_BIT (si->visited, n);
1973 si->dfs[n] = si->current_index ++;
1974 my_dfs = si->dfs[n];
1976 /* Visit all the successors. */
1977 EXECUTE_IF_IN_NONNULL_BITMAP (graph->preds[n], 0, i, bi)
1979 unsigned int w = si->node_mapping[i];
1981 if (TEST_BIT (si->deleted, w))
1984 if (!TEST_BIT (si->visited, w))
1985 condense_visit (graph, si, w);
1987 unsigned int t = si->node_mapping[w];
1988 unsigned int nnode = si->node_mapping[n];
1989 gcc_assert (nnode == n);
1991 if (si->dfs[t] < si->dfs[nnode])
1992 si->dfs[n] = si->dfs[t];
1996 /* Visit all the implicit predecessors. */
1997 EXECUTE_IF_IN_NONNULL_BITMAP (graph->implicit_preds[n], 0, i, bi)
1999 unsigned int w = si->node_mapping[i];
2001 if (TEST_BIT (si->deleted, w))
2004 if (!TEST_BIT (si->visited, w))
2005 condense_visit (graph, si, w);
2007 unsigned int t = si->node_mapping[w];
2008 unsigned int nnode = si->node_mapping[n];
2009 gcc_assert (nnode == n);
2011 if (si->dfs[t] < si->dfs[nnode])
2012 si->dfs[n] = si->dfs[t];
2016 /* See if any components have been identified. */
2017 if (si->dfs[n] == my_dfs)
2019 while (VEC_length (unsigned, si->scc_stack) != 0
2020 && si->dfs[VEC_last (unsigned, si->scc_stack)] >= my_dfs)
2022 unsigned int w = VEC_pop (unsigned, si->scc_stack);
2023 si->node_mapping[w] = n;
2025 if (!TEST_BIT (graph->direct_nodes, w))
2026 RESET_BIT (graph->direct_nodes, n);
2028 /* Unify our nodes. */
2029 if (graph->preds[w])
2031 if (!graph->preds[n])
2032 graph->preds[n] = BITMAP_ALLOC (&predbitmap_obstack);
2033 bitmap_ior_into (graph->preds[n], graph->preds[w]);
2035 if (graph->implicit_preds[w])
2037 if (!graph->implicit_preds[n])
2038 graph->implicit_preds[n] = BITMAP_ALLOC (&predbitmap_obstack);
2039 bitmap_ior_into (graph->implicit_preds[n],
2040 graph->implicit_preds[w]);
2042 if (graph->points_to[w])
2044 if (!graph->points_to[n])
2045 graph->points_to[n] = BITMAP_ALLOC (&predbitmap_obstack);
2046 bitmap_ior_into (graph->points_to[n],
2047 graph->points_to[w]);
2050 SET_BIT (si->deleted, n);
2053 VEC_safe_push (unsigned, heap, si->scc_stack, n);
2056 /* Label pointer equivalences. */
2059 label_visit (constraint_graph_t graph, struct scc_info *si, unsigned int n)
2063 SET_BIT (si->visited, n);
2065 if (!graph->points_to[n])
2066 graph->points_to[n] = BITMAP_ALLOC (&predbitmap_obstack);
2068 /* Label and union our incoming edges's points to sets. */
2069 EXECUTE_IF_IN_NONNULL_BITMAP (graph->preds[n], 0, i, bi)
2071 unsigned int w = si->node_mapping[i];
2072 if (!TEST_BIT (si->visited, w))
2073 label_visit (graph, si, w);
2075 /* Skip unused edges */
2076 if (w == n || graph->pointer_label[w] == 0)
2079 if (graph->points_to[w])
2080 bitmap_ior_into(graph->points_to[n], graph->points_to[w]);
2082 /* Indirect nodes get fresh variables. */
2083 if (!TEST_BIT (graph->direct_nodes, n))
2084 bitmap_set_bit (graph->points_to[n], FIRST_REF_NODE + n);
2086 if (!bitmap_empty_p (graph->points_to[n]))
2088 unsigned int label = equiv_class_lookup (pointer_equiv_class_table,
2089 graph->points_to[n]);
2092 label = pointer_equiv_class++;
2093 equiv_class_add (pointer_equiv_class_table,
2094 label, graph->points_to[n]);
2096 graph->pointer_label[n] = label;
2100 /* Perform offline variable substitution, discovering equivalence
2101 classes, and eliminating non-pointer variables. */
2103 static struct scc_info *
2104 perform_var_substitution (constraint_graph_t graph)
2107 unsigned int size = graph->size;
2108 struct scc_info *si = init_scc_info (size);
2110 bitmap_obstack_initialize (&iteration_obstack);
2111 pointer_equiv_class_table = htab_create (511, equiv_class_label_hash,
2112 equiv_class_label_eq, free);
2113 location_equiv_class_table = htab_create (511, equiv_class_label_hash,
2114 equiv_class_label_eq, free);
2115 pointer_equiv_class = 1;
2116 location_equiv_class = 1;
2118 /* Condense the nodes, which means to find SCC's, count incoming
2119 predecessors, and unite nodes in SCC's. */
2120 for (i = 0; i < FIRST_REF_NODE; i++)
2121 if (!TEST_BIT (si->visited, si->node_mapping[i]))
2122 condense_visit (graph, si, si->node_mapping[i]);
2124 sbitmap_zero (si->visited);
2125 /* Actually the label the nodes for pointer equivalences */
2126 for (i = 0; i < FIRST_REF_NODE; i++)
2127 if (!TEST_BIT (si->visited, si->node_mapping[i]))
2128 label_visit (graph, si, si->node_mapping[i]);
2130 /* Calculate location equivalence labels. */
2131 for (i = 0; i < FIRST_REF_NODE; i++)
2138 if (!graph->pointed_by[i])
2140 pointed_by = BITMAP_ALLOC (&iteration_obstack);
2142 /* Translate the pointed-by mapping for pointer equivalence
2144 EXECUTE_IF_SET_IN_BITMAP (graph->pointed_by[i], 0, j, bi)
2146 bitmap_set_bit (pointed_by,
2147 graph->pointer_label[si->node_mapping[j]]);
2149 /* The original pointed_by is now dead. */
2150 BITMAP_FREE (graph->pointed_by[i]);
2152 /* Look up the location equivalence label if one exists, or make
2154 label = equiv_class_lookup (location_equiv_class_table,
2158 label = location_equiv_class++;
2159 equiv_class_add (location_equiv_class_table,
2164 if (dump_file && (dump_flags & TDF_DETAILS))
2165 fprintf (dump_file, "Found location equivalence for node %s\n",
2166 get_varinfo (i)->name);
2167 BITMAP_FREE (pointed_by);
2169 graph->loc_label[i] = label;
2173 if (dump_file && (dump_flags & TDF_DETAILS))
2174 for (i = 0; i < FIRST_REF_NODE; i++)
2176 bool direct_node = TEST_BIT (graph->direct_nodes, i);
2178 "Equivalence classes for %s node id %d:%s are pointer: %d"
2180 direct_node ? "Direct node" : "Indirect node", i,
2181 get_varinfo (i)->name,
2182 graph->pointer_label[si->node_mapping[i]],
2183 graph->loc_label[si->node_mapping[i]]);
2186 /* Quickly eliminate our non-pointer variables. */
2188 for (i = 0; i < FIRST_REF_NODE; i++)
2190 unsigned int node = si->node_mapping[i];
2192 if (graph->pointer_label[node] == 0)
2194 if (dump_file && (dump_flags & TDF_DETAILS))
2196 "%s is a non-pointer variable, eliminating edges.\n",
2197 get_varinfo (node)->name);
2198 stats.nonpointer_vars++;
2199 clear_edges_for_node (graph, node);
2206 /* Free information that was only necessary for variable
2210 free_var_substitution_info (struct scc_info *si)
2213 free (graph->pointer_label);
2214 free (graph->loc_label);
2215 free (graph->pointed_by);
2216 free (graph->points_to);
2217 free (graph->eq_rep);
2218 sbitmap_free (graph->direct_nodes);
2219 htab_delete (pointer_equiv_class_table);
2220 htab_delete (location_equiv_class_table);
2221 bitmap_obstack_release (&iteration_obstack);
2224 /* Return an existing node that is equivalent to NODE, which has
2225 equivalence class LABEL, if one exists. Return NODE otherwise. */
2228 find_equivalent_node (constraint_graph_t graph,
2229 unsigned int node, unsigned int label)
2231 /* If the address version of this variable is unused, we can
2232 substitute it for anything else with the same label.
2233 Otherwise, we know the pointers are equivalent, but not the
2234 locations, and we can unite them later. */
2236 if (!bitmap_bit_p (graph->address_taken, node))
2238 gcc_assert (label < graph->size);
2240 if (graph->eq_rep[label] != -1)
2242 /* Unify the two variables since we know they are equivalent. */
2243 if (unite (graph->eq_rep[label], node))
2244 unify_nodes (graph, graph->eq_rep[label], node, false);
2245 return graph->eq_rep[label];
2249 graph->eq_rep[label] = node;
2250 graph->pe_rep[label] = node;
2255 gcc_assert (label < graph->size);
2256 graph->pe[node] = label;
2257 if (graph->pe_rep[label] == -1)
2258 graph->pe_rep[label] = node;
2264 /* Unite pointer equivalent but not location equivalent nodes in
2265 GRAPH. This may only be performed once variable substitution is
2269 unite_pointer_equivalences (constraint_graph_t graph)
2273 /* Go through the pointer equivalences and unite them to their
2274 representative, if they aren't already. */
2275 for (i = 0; i < FIRST_REF_NODE; i++)
2277 unsigned int label = graph->pe[i];
2280 int label_rep = graph->pe_rep[label];
2282 if (label_rep == -1)
2285 label_rep = find (label_rep);
2286 if (label_rep >= 0 && unite (label_rep, find (i)))
2287 unify_nodes (graph, label_rep, i, false);
2292 /* Move complex constraints to the GRAPH nodes they belong to. */
2295 move_complex_constraints (constraint_graph_t graph)
2300 for (i = 0; VEC_iterate (constraint_t, constraints, i, c); i++)
2304 struct constraint_expr lhs = c->lhs;
2305 struct constraint_expr rhs = c->rhs;
2307 if (lhs.type == DEREF)
2309 insert_into_complex (graph, lhs.var, c);
2311 else if (rhs.type == DEREF)
2313 if (!(get_varinfo (lhs.var)->is_special_var))
2314 insert_into_complex (graph, rhs.var, c);
2316 else if (rhs.type != ADDRESSOF && lhs.var > anything_id
2317 && (lhs.offset != 0 || rhs.offset != 0))
2319 insert_into_complex (graph, rhs.var, c);
2326 /* Optimize and rewrite complex constraints while performing
2327 collapsing of equivalent nodes. SI is the SCC_INFO that is the
2328 result of perform_variable_substitution. */
2331 rewrite_constraints (constraint_graph_t graph,
2332 struct scc_info *si)
2338 for (j = 0; j < graph->size; j++)
2339 gcc_assert (find (j) == j);
2341 for (i = 0; VEC_iterate (constraint_t, constraints, i, c); i++)
2343 struct constraint_expr lhs = c->lhs;
2344 struct constraint_expr rhs = c->rhs;
2345 unsigned int lhsvar = find (lhs.var);
2346 unsigned int rhsvar = find (rhs.var);
2347 unsigned int lhsnode, rhsnode;
2348 unsigned int lhslabel, rhslabel;
2350 lhsnode = si->node_mapping[lhsvar];
2351 rhsnode = si->node_mapping[rhsvar];
2352 lhslabel = graph->pointer_label[lhsnode];
2353 rhslabel = graph->pointer_label[rhsnode];
2355 /* See if it is really a non-pointer variable, and if so, ignore
2359 if (dump_file && (dump_flags & TDF_DETAILS))
2362 fprintf (dump_file, "%s is a non-pointer variable,"
2363 "ignoring constraint:",
2364 get_varinfo (lhs.var)->name);
2365 dump_constraint (dump_file, c);
2367 VEC_replace (constraint_t, constraints, i, NULL);
2373 if (dump_file && (dump_flags & TDF_DETAILS))
2376 fprintf (dump_file, "%s is a non-pointer variable,"
2377 "ignoring constraint:",
2378 get_varinfo (rhs.var)->name);
2379 dump_constraint (dump_file, c);
2381 VEC_replace (constraint_t, constraints, i, NULL);
2385 lhsvar = find_equivalent_node (graph, lhsvar, lhslabel);
2386 rhsvar = find_equivalent_node (graph, rhsvar, rhslabel);
2387 c->lhs.var = lhsvar;
2388 c->rhs.var = rhsvar;
2393 /* Eliminate indirect cycles involving NODE. Return true if NODE was
2394 part of an SCC, false otherwise. */
2397 eliminate_indirect_cycles (unsigned int node)
2399 if (graph->indirect_cycles[node] != -1
2400 && !bitmap_empty_p (get_varinfo (node)->solution))
2403 VEC(unsigned,heap) *queue = NULL;
2405 unsigned int to = find (graph->indirect_cycles[node]);
2408 /* We can't touch the solution set and call unify_nodes
2409 at the same time, because unify_nodes is going to do
2410 bitmap unions into it. */
2412 EXECUTE_IF_SET_IN_BITMAP (get_varinfo (node)->solution, 0, i, bi)
2414 if (find (i) == i && i != to)
2417 VEC_safe_push (unsigned, heap, queue, i);
2422 VEC_iterate (unsigned, queue, queuepos, i);
2425 unify_nodes (graph, to, i, true);
2427 VEC_free (unsigned, heap, queue);
2433 /* Solve the constraint graph GRAPH using our worklist solver.
2434 This is based on the PW* family of solvers from the "Efficient Field
2435 Sensitive Pointer Analysis for C" paper.
2436 It works by iterating over all the graph nodes, processing the complex
2437 constraints and propagating the copy constraints, until everything stops
2438 changed. This corresponds to steps 6-8 in the solving list given above. */
2441 solve_graph (constraint_graph_t graph)
2443 unsigned int size = graph->size;
2448 changed = sbitmap_alloc (size);
2449 sbitmap_zero (changed);
2451 /* Mark all initial non-collapsed nodes as changed. */
2452 for (i = 0; i < size; i++)
2454 varinfo_t ivi = get_varinfo (i);
2455 if (find (i) == i && !bitmap_empty_p (ivi->solution)
2456 && ((graph->succs[i] && !bitmap_empty_p (graph->succs[i]))
2457 || VEC_length (constraint_t, graph->complex[i]) > 0))
2459 SET_BIT (changed, i);
2464 /* Allocate a bitmap to be used to store the changed bits. */
2465 pts = BITMAP_ALLOC (&pta_obstack);
2467 while (changed_count > 0)
2470 struct topo_info *ti = init_topo_info ();
2473 bitmap_obstack_initialize (&iteration_obstack);
2475 compute_topo_order (graph, ti);
2477 while (VEC_length (unsigned, ti->topo_order) != 0)
2480 i = VEC_pop (unsigned, ti->topo_order);
2482 /* If this variable is not a representative, skip it. */
2486 /* In certain indirect cycle cases, we may merge this
2487 variable to another. */
2488 if (eliminate_indirect_cycles (i) && find (i) != i)
2491 /* If the node has changed, we need to process the
2492 complex constraints and outgoing edges again. */
2493 if (TEST_BIT (changed, i))
2498 VEC(constraint_t,heap) *complex = graph->complex[i];
2499 bool solution_empty;
2501 RESET_BIT (changed, i);
2504 /* Compute the changed set of solution bits. */
2505 bitmap_and_compl (pts, get_varinfo (i)->solution,
2506 get_varinfo (i)->oldsolution);
2508 if (bitmap_empty_p (pts))
2511 bitmap_ior_into (get_varinfo (i)->oldsolution, pts);
2513 solution = get_varinfo (i)->solution;
2514 solution_empty = bitmap_empty_p (solution);
2516 /* Process the complex constraints */
2517 for (j = 0; VEC_iterate (constraint_t, complex, j, c); j++)
2519 /* XXX: This is going to unsort the constraints in
2520 some cases, which will occasionally add duplicate
2521 constraints during unification. This does not
2522 affect correctness. */
2523 c->lhs.var = find (c->lhs.var);
2524 c->rhs.var = find (c->rhs.var);
2526 /* The only complex constraint that can change our
2527 solution to non-empty, given an empty solution,
2528 is a constraint where the lhs side is receiving
2529 some set from elsewhere. */
2530 if (!solution_empty || c->lhs.type != DEREF)
2531 do_complex_constraint (graph, c, pts);
2534 solution_empty = bitmap_empty_p (solution);
2536 if (!solution_empty)
2539 unsigned eff_escaped_id = find (escaped_id);
2541 /* Propagate solution to all successors. */
2542 EXECUTE_IF_IN_NONNULL_BITMAP (graph->succs[i],
2548 unsigned int to = find (j);
2549 tmp = get_varinfo (to)->solution;
2552 /* Don't try to propagate to ourselves. */
2556 /* If we propagate from ESCAPED use ESCAPED as
2558 if (i == eff_escaped_id)
2559 flag = bitmap_set_bit (tmp, escaped_id);
2561 flag = set_union_with_increment (tmp, pts, 0);
2565 get_varinfo (to)->solution = tmp;
2566 if (!TEST_BIT (changed, to))
2568 SET_BIT (changed, to);
2576 free_topo_info (ti);
2577 bitmap_obstack_release (&iteration_obstack);
2581 sbitmap_free (changed);
2582 bitmap_obstack_release (&oldpta_obstack);
2585 /* Map from trees to variable infos. */
2586 static struct pointer_map_t *vi_for_tree;
2589 /* Insert ID as the variable id for tree T in the vi_for_tree map. */
2592 insert_vi_for_tree (tree t, varinfo_t vi)
2594 void **slot = pointer_map_insert (vi_for_tree, t);
2596 gcc_assert (*slot == NULL);
2600 /* Find the variable info for tree T in VI_FOR_TREE. If T does not
2601 exist in the map, return NULL, otherwise, return the varinfo we found. */
2604 lookup_vi_for_tree (tree t)
2606 void **slot = pointer_map_contains (vi_for_tree, t);
2610 return (varinfo_t) *slot;
2613 /* Return a printable name for DECL */
2616 alias_get_name (tree decl)
2618 const char *res = get_name (decl);
2620 int num_printed = 0;
2629 if (TREE_CODE (decl) == SSA_NAME)
2631 num_printed = asprintf (&temp, "%s_%u",
2632 alias_get_name (SSA_NAME_VAR (decl)),
2633 SSA_NAME_VERSION (decl));
2635 else if (DECL_P (decl))
2637 num_printed = asprintf (&temp, "D.%u", DECL_UID (decl));
2639 if (num_printed > 0)
2641 res = ggc_strdup (temp);
2647 /* Find the variable id for tree T in the map.
2648 If T doesn't exist in the map, create an entry for it and return it. */
2651 get_vi_for_tree (tree t)
2653 void **slot = pointer_map_contains (vi_for_tree, t);
2655 return get_varinfo (create_variable_info_for (t, alias_get_name (t)));
2657 return (varinfo_t) *slot;
2660 /* Get a constraint expression for a new temporary variable. */
2662 static struct constraint_expr
2663 get_constraint_exp_for_temp (tree t)
2665 struct constraint_expr cexpr;
2667 gcc_assert (SSA_VAR_P (t));
2669 cexpr.type = SCALAR;
2670 cexpr.var = get_vi_for_tree (t)->id;
2676 /* Get a constraint expression vector from an SSA_VAR_P node.
2677 If address_p is true, the result will be taken its address of. */
2680 get_constraint_for_ssa_var (tree t, VEC(ce_s, heap) **results, bool address_p)
2682 struct constraint_expr cexpr;
2685 /* We allow FUNCTION_DECLs here even though it doesn't make much sense. */
2686 gcc_assert (SSA_VAR_P (t) || DECL_P (t));
2688 /* For parameters, get at the points-to set for the actual parm
2690 if (TREE_CODE (t) == SSA_NAME
2691 && TREE_CODE (SSA_NAME_VAR (t)) == PARM_DECL
2692 && SSA_NAME_IS_DEFAULT_DEF (t))
2694 get_constraint_for_ssa_var (SSA_NAME_VAR (t), results, address_p);
2698 vi = get_vi_for_tree (t);
2700 cexpr.type = SCALAR;
2702 /* If we determine the result is "anything", and we know this is readonly,
2703 say it points to readonly memory instead. */
2704 if (cexpr.var == anything_id && TREE_READONLY (t))
2707 cexpr.type = ADDRESSOF;
2708 cexpr.var = readonly_id;
2711 /* If we are not taking the address of the constraint expr, add all
2712 sub-fiels of the variable as well. */
2715 for (; vi; vi = vi->next)
2718 VEC_safe_push (ce_s, heap, *results, &cexpr);
2723 VEC_safe_push (ce_s, heap, *results, &cexpr);
2726 /* Process constraint T, performing various simplifications and then
2727 adding it to our list of overall constraints. */
2730 process_constraint (constraint_t t)
2732 struct constraint_expr rhs = t->rhs;
2733 struct constraint_expr lhs = t->lhs;
2735 gcc_assert (rhs.var < VEC_length (varinfo_t, varmap));
2736 gcc_assert (lhs.var < VEC_length (varinfo_t, varmap));
2738 /* If we didn't get any useful constraint from the lhs we get
2739 &ANYTHING as fallback from get_constraint_for. Deal with
2740 it here by turning it into *ANYTHING. */
2741 if (lhs.type == ADDRESSOF
2742 && lhs.var == anything_id)
2745 /* ADDRESSOF on the lhs is invalid. */
2746 gcc_assert (lhs.type != ADDRESSOF);
2748 /* This can happen in our IR with things like n->a = *p */
2749 if (rhs.type == DEREF && lhs.type == DEREF && rhs.var != anything_id)
2751 /* Split into tmp = *rhs, *lhs = tmp */
2752 tree rhsdecl = get_varinfo (rhs.var)->decl;
2753 tree pointertype = TREE_TYPE (rhsdecl);
2754 tree pointedtotype = TREE_TYPE (pointertype);
2755 tree tmpvar = create_tmp_var_raw (pointedtotype, "doubledereftmp");
2756 struct constraint_expr tmplhs = get_constraint_exp_for_temp (tmpvar);
2758 process_constraint (new_constraint (tmplhs, rhs));
2759 process_constraint (new_constraint (lhs, tmplhs));
2761 else if (rhs.type == ADDRESSOF && lhs.type == DEREF)
2763 /* Split into tmp = &rhs, *lhs = tmp */
2764 tree rhsdecl = get_varinfo (rhs.var)->decl;
2765 tree pointertype = TREE_TYPE (rhsdecl);
2766 tree tmpvar = create_tmp_var_raw (pointertype, "derefaddrtmp");
2767 struct constraint_expr tmplhs = get_constraint_exp_for_temp (tmpvar);
2769 process_constraint (new_constraint (tmplhs, rhs));
2770 process_constraint (new_constraint (lhs, tmplhs));
2774 gcc_assert (rhs.type != ADDRESSOF || rhs.offset == 0);
2775 VEC_safe_push (constraint_t, heap, constraints, t);
2779 /* Return true if T is a type that could contain pointers. */
2782 type_could_have_pointers (tree type)
2784 if (POINTER_TYPE_P (type))
2787 if (TREE_CODE (type) == ARRAY_TYPE)
2788 return type_could_have_pointers (TREE_TYPE (type));
2790 return AGGREGATE_TYPE_P (type);
2793 /* Return true if T is a variable of a type that could contain
2797 could_have_pointers (tree t)
2799 return type_could_have_pointers (TREE_TYPE (t));
2802 /* Return the position, in bits, of FIELD_DECL from the beginning of its
2805 static HOST_WIDE_INT
2806 bitpos_of_field (const tree fdecl)
2809 if (!host_integerp (DECL_FIELD_OFFSET (fdecl), 0)
2810 || !host_integerp (DECL_FIELD_BIT_OFFSET (fdecl), 0))
2813 return (TREE_INT_CST_LOW (DECL_FIELD_OFFSET (fdecl)) * 8
2814 + TREE_INT_CST_LOW (DECL_FIELD_BIT_OFFSET (fdecl)));
2818 /* Get constraint expressions for offsetting PTR by OFFSET. Stores the
2819 resulting constraint expressions in *RESULTS. */
2822 get_constraint_for_ptr_offset (tree ptr, tree offset,
2823 VEC (ce_s, heap) **results)
2825 struct constraint_expr *c;
2827 HOST_WIDE_INT rhsunitoffset, rhsoffset;
2829 /* If we do not do field-sensitive PTA adding offsets to pointers
2830 does not change the points-to solution. */
2831 if (!use_field_sensitive)
2833 get_constraint_for (ptr, results);
2837 /* If the offset is not a non-negative integer constant that fits
2838 in a HOST_WIDE_INT, we have to fall back to a conservative
2839 solution which includes all sub-fields of all pointed-to
2840 variables of ptr. */
2841 if (!host_integerp (offset, 0))
2842 rhsoffset = UNKNOWN_OFFSET;
2845 /* Make sure the bit-offset also fits. */
2846 rhsunitoffset = TREE_INT_CST_LOW (offset);
2847 rhsoffset = rhsunitoffset * BITS_PER_UNIT;
2848 if (rhsunitoffset != rhsoffset / BITS_PER_UNIT)
2849 rhsoffset = UNKNOWN_OFFSET;
2852 get_constraint_for (ptr, results);
2856 /* As we are eventually appending to the solution do not use
2857 VEC_iterate here. */
2858 n = VEC_length (ce_s, *results);
2859 for (j = 0; j < n; j++)
2862 c = VEC_index (ce_s, *results, j);
2863 curr = get_varinfo (c->var);
2865 if (c->type == ADDRESSOF
2866 /* If this varinfo represents a full variable just use it. */
2867 && curr->is_full_var)
2869 else if (c->type == ADDRESSOF
2870 /* If we do not know the offset add all subfields. */
2871 && rhsoffset == UNKNOWN_OFFSET)
2873 varinfo_t temp = lookup_vi_for_tree (curr->decl);
2876 struct constraint_expr c2;
2878 c2.type = ADDRESSOF;
2880 VEC_safe_push (ce_s, heap, *results, &c2);
2885 else if (c->type == ADDRESSOF)
2888 unsigned HOST_WIDE_INT offset = curr->offset + rhsoffset;
2890 /* Search the sub-field which overlaps with the
2891 pointed-to offset. If the result is outside of the variable
2892 we have to provide a conservative result, as the variable is
2893 still reachable from the resulting pointer (even though it
2894 technically cannot point to anything). The last and first
2895 sub-fields are such conservative results.
2896 ??? If we always had a sub-field for &object + 1 then
2897 we could represent this in a more precise way. */
2899 && curr->offset < offset)
2901 temp = first_or_preceding_vi_for_offset (curr, offset);
2903 /* If the found variable is not exactly at the pointed to
2904 result, we have to include the next variable in the
2905 solution as well. Otherwise two increments by offset / 2
2906 do not result in the same or a conservative superset
2908 if (temp->offset != offset
2909 && temp->next != NULL)
2911 struct constraint_expr c2;
2912 c2.var = temp->next->id;
2913 c2.type = ADDRESSOF;
2915 VEC_safe_push (ce_s, heap, *results, &c2);
2921 c->offset = rhsoffset;
2926 /* Given a COMPONENT_REF T, return the constraint_expr vector for it.
2927 If address_p is true the result will be taken its address of. */
2930 get_constraint_for_component_ref (tree t, VEC(ce_s, heap) **results,
2934 HOST_WIDE_INT bitsize = -1;
2935 HOST_WIDE_INT bitmaxsize = -1;
2936 HOST_WIDE_INT bitpos;
2938 struct constraint_expr *result;
2940 /* Some people like to do cute things like take the address of
2943 while (!SSA_VAR_P (forzero) && !CONSTANT_CLASS_P (forzero))
2944 forzero = TREE_OPERAND (forzero, 0);
2946 if (CONSTANT_CLASS_P (forzero) && integer_zerop (forzero))
2948 struct constraint_expr temp;
2951 temp.var = integer_id;
2953 VEC_safe_push (ce_s, heap, *results, &temp);
2957 t = get_ref_base_and_extent (t, &bitpos, &bitsize, &bitmaxsize);
2959 /* Pretend to take the address of the base, we'll take care of
2960 adding the required subset of sub-fields below. */
2961 get_constraint_for_1 (t, results, true);
2962 gcc_assert (VEC_length (ce_s, *results) == 1);
2963 result = VEC_last (ce_s, *results);
2965 if (result->type == SCALAR
2966 && get_varinfo (result->var)->is_full_var)
2967 /* For single-field vars do not bother about the offset. */
2969 else if (result->type == SCALAR)
2971 /* In languages like C, you can access one past the end of an
2972 array. You aren't allowed to dereference it, so we can
2973 ignore this constraint. When we handle pointer subtraction,
2974 we may have to do something cute here. */
2976 if ((unsigned HOST_WIDE_INT)bitpos < get_varinfo (result->var)->fullsize
2979 /* It's also not true that the constraint will actually start at the
2980 right offset, it may start in some padding. We only care about
2981 setting the constraint to the first actual field it touches, so
2983 struct constraint_expr cexpr = *result;
2985 VEC_pop (ce_s, *results);
2987 for (curr = get_varinfo (cexpr.var); curr; curr = curr->next)
2989 if (ranges_overlap_p (curr->offset, curr->size,
2990 bitpos, bitmaxsize))
2992 cexpr.var = curr->id;
2993 VEC_safe_push (ce_s, heap, *results, &cexpr);
2998 /* If we are going to take the address of this field then
2999 to be able to compute reachability correctly add at least
3000 the last field of the variable. */
3002 && VEC_length (ce_s, *results) == 0)
3004 curr = get_varinfo (cexpr.var);
3005 while (curr->next != NULL)
3007 cexpr.var = curr->id;
3008 VEC_safe_push (ce_s, heap, *results, &cexpr);
3011 /* Assert that we found *some* field there. The user couldn't be
3012 accessing *only* padding. */
3013 /* Still the user could access one past the end of an array
3014 embedded in a struct resulting in accessing *only* padding. */
3015 gcc_assert (VEC_length (ce_s, *results) >= 1
3016 || ref_contains_array_ref (orig_t));
3018 else if (bitmaxsize == 0)
3020 if (dump_file && (dump_flags & TDF_DETAILS))
3021 fprintf (dump_file, "Access to zero-sized part of variable,"
3025 if (dump_file && (dump_flags & TDF_DETAILS))
3026 fprintf (dump_file, "Access to past the end of variable, ignoring\n");
3028 else if (result->type == DEREF)
3030 /* If we do not know exactly where the access goes say so. Note
3031 that only for non-structure accesses we know that we access
3032 at most one subfiled of any variable. */
3034 || bitsize != bitmaxsize
3035 || AGGREGATE_TYPE_P (TREE_TYPE (orig_t)))
3036 result->offset = UNKNOWN_OFFSET;
3038 result->offset = bitpos;
3040 else if (result->type == ADDRESSOF)
3042 /* We can end up here for component references on a
3043 VIEW_CONVERT_EXPR <>(&foobar). */
3044 result->type = SCALAR;
3045 result->var = anything_id;
3053 /* Dereference the constraint expression CONS, and return the result.
3054 DEREF (ADDRESSOF) = SCALAR
3055 DEREF (SCALAR) = DEREF
3056 DEREF (DEREF) = (temp = DEREF1; result = DEREF(temp))
3057 This is needed so that we can handle dereferencing DEREF constraints. */
3060 do_deref (VEC (ce_s, heap) **constraints)
3062 struct constraint_expr *c;
3065 for (i = 0; VEC_iterate (ce_s, *constraints, i, c); i++)
3067 if (c->type == SCALAR)
3069 else if (c->type == ADDRESSOF)
3071 else if (c->type == DEREF)
3073 tree tmpvar = create_tmp_var_raw (ptr_type_node, "dereftmp");
3074 struct constraint_expr tmplhs = get_constraint_exp_for_temp (tmpvar);
3075 process_constraint (new_constraint (tmplhs, *c));
3076 c->var = tmplhs.var;
3083 /* Given a tree T, return the constraint expression for it. */
3086 get_constraint_for_1 (tree t, VEC (ce_s, heap) **results, bool address_p)
3088 struct constraint_expr temp;
3090 /* x = integer is all glommed to a single variable, which doesn't
3091 point to anything by itself. That is, of course, unless it is an
3092 integer constant being treated as a pointer, in which case, we
3093 will return that this is really the addressof anything. This
3094 happens below, since it will fall into the default case. The only
3095 case we know something about an integer treated like a pointer is
3096 when it is the NULL pointer, and then we just say it points to
3099 Do not do that if -fno-delete-null-pointer-checks though, because
3100 in that case *NULL does not fail, so it _should_ alias *anything.
3101 It is not worth adding a new option or renaming the existing one,
3102 since this case is relatively obscure. */
3103 if (flag_delete_null_pointer_checks
3104 && ((TREE_CODE (t) == INTEGER_CST
3105 && integer_zerop (t))
3106 /* The only valid CONSTRUCTORs in gimple with pointer typed
3107 elements are zero-initializer. */
3108 || TREE_CODE (t) == CONSTRUCTOR))
3110 temp.var = nothing_id;
3111 temp.type = ADDRESSOF;
3113 VEC_safe_push (ce_s, heap, *results, &temp);
3117 /* String constants are read-only. */
3118 if (TREE_CODE (t) == STRING_CST)
3120 temp.var = readonly_id;
3123 VEC_safe_push (ce_s, heap, *results, &temp);
3127 switch (TREE_CODE_CLASS (TREE_CODE (t)))
3129 case tcc_expression:
3131 switch (TREE_CODE (t))
3135 struct constraint_expr *c;
3137 tree exp = TREE_OPERAND (t, 0);
3139 get_constraint_for_1 (exp, results, true);
3141 for (i = 0; VEC_iterate (ce_s, *results, i, c); i++)
3143 if (c->type == DEREF)
3146 c->type = ADDRESSOF;
3157 switch (TREE_CODE (t))
3161 get_constraint_for_1 (TREE_OPERAND (t, 0), results, address_p);
3166 case ARRAY_RANGE_REF:
3168 get_constraint_for_component_ref (t, results, address_p);
3170 case VIEW_CONVERT_EXPR:
3171 get_constraint_for_1 (TREE_OPERAND (t, 0), results, address_p);
3173 /* We are missing handling for TARGET_MEM_REF here. */
3178 case tcc_exceptional:
3180 switch (TREE_CODE (t))
3184 get_constraint_for_ssa_var (t, results, address_p);
3191 case tcc_declaration:
3193 get_constraint_for_ssa_var (t, results, address_p);
3199 /* The default fallback is a constraint from anything. */
3200 temp.type = ADDRESSOF;
3201 temp.var = anything_id;
3203 VEC_safe_push (ce_s, heap, *results, &temp);
3206 /* Given a gimple tree T, return the constraint expression vector for it. */
3209 get_constraint_for (tree t, VEC (ce_s, heap) **results)
3211 gcc_assert (VEC_length (ce_s, *results) == 0);
3213 get_constraint_for_1 (t, results, false);
3216 /* Handle aggregate copies by expanding into copies of the respective
3217 fields of the structures. */
3220 do_structure_copy (tree lhsop, tree rhsop)
3222 struct constraint_expr *lhsp, *rhsp;
3223 VEC (ce_s, heap) *lhsc = NULL, *rhsc = NULL;
3226 get_constraint_for (lhsop, &lhsc);
3227 get_constraint_for (rhsop, &rhsc);
3228 lhsp = VEC_index (ce_s, lhsc, 0);
3229 rhsp = VEC_index (ce_s, rhsc, 0);
3230 if (lhsp->type == DEREF
3231 || (lhsp->type == ADDRESSOF && lhsp->var == anything_id)
3232 || rhsp->type == DEREF)
3234 struct constraint_expr tmp;
3235 tree tmpvar = create_tmp_var_raw (ptr_type_node,
3236 "structcopydereftmp");
3237 tmp.var = get_vi_for_tree (tmpvar)->id;
3240 for (j = 0; VEC_iterate (ce_s, rhsc, j, rhsp); ++j)
3241 process_constraint (new_constraint (tmp, *rhsp));
3242 for (j = 0; VEC_iterate (ce_s, lhsc, j, lhsp); ++j)
3243 process_constraint (new_constraint (*lhsp, tmp));
3245 else if (lhsp->type == SCALAR
3246 && (rhsp->type == SCALAR
3247 || rhsp->type == ADDRESSOF))
3249 tree lhsbase, rhsbase;
3250 HOST_WIDE_INT lhssize, lhsmaxsize, lhsoffset;
3251 HOST_WIDE_INT rhssize, rhsmaxsize, rhsoffset;
3253 lhsbase = get_ref_base_and_extent (lhsop, &lhsoffset,
3254 &lhssize, &lhsmaxsize);
3255 rhsbase = get_ref_base_and_extent (rhsop, &rhsoffset,
3256 &rhssize, &rhsmaxsize);
3257 for (j = 0; VEC_iterate (ce_s, lhsc, j, lhsp);)
3259 varinfo_t lhsv, rhsv;
3260 rhsp = VEC_index (ce_s, rhsc, k);
3261 lhsv = get_varinfo (lhsp->var);
3262 rhsv = get_varinfo (rhsp->var);
3263 if (lhsv->may_have_pointers
3264 && ranges_overlap_p (lhsv->offset + rhsoffset, lhsv->size,
3265 rhsv->offset + lhsoffset, rhsv->size))
3266 process_constraint (new_constraint (*lhsp, *rhsp));
3267 if (lhsv->offset + rhsoffset + lhsv->size
3268 > rhsv->offset + lhsoffset + rhsv->size)
3271 if (k >= VEC_length (ce_s, rhsc))
3281 VEC_free (ce_s, heap, lhsc);
3282 VEC_free (ce_s, heap, rhsc);
3285 /* Create a constraint ID = OP. */
3288 make_constraint_to (unsigned id, tree op)
3290 VEC(ce_s, heap) *rhsc = NULL;
3291 struct constraint_expr *c;
3292 struct constraint_expr includes;
3296 includes.offset = 0;
3297 includes.type = SCALAR;
3299 get_constraint_for (op, &rhsc);
3300 for (j = 0; VEC_iterate (ce_s, rhsc, j, c); j++)
3301 process_constraint (new_constraint (includes, *c));
3302 VEC_free (ce_s, heap, rhsc);
3305 /* Make constraints necessary to make OP escape. */
3308 make_escape_constraint (tree op)
3310 make_constraint_to (escaped_id, op);
3313 /* For non-IPA mode, generate constraints necessary for a call on the
3317 handle_rhs_call (gimple stmt, VEC(ce_s, heap) **results)
3319 struct constraint_expr rhsc;
3322 for (i = 0; i < gimple_call_num_args (stmt); ++i)
3324 tree arg = gimple_call_arg (stmt, i);
3326 /* Find those pointers being passed, and make sure they end up
3327 pointing to anything. */
3328 if (could_have_pointers (arg))
3329 make_escape_constraint (arg);
3332 /* The static chain escapes as well. */
3333 if (gimple_call_chain (stmt))
3334 make_escape_constraint (gimple_call_chain (stmt));
3336 /* Regular functions return nonlocal memory. */
3337 rhsc.var = nonlocal_id;
3340 VEC_safe_push (ce_s, heap, *results, &rhsc);
3343 /* For non-IPA mode, generate constraints necessary for a call
3344 that returns a pointer and assigns it to LHS. This simply makes
3345 the LHS point to global and escaped variables. */
3348 handle_lhs_call (tree lhs, int flags, VEC(ce_s, heap) *rhsc)
3350 VEC(ce_s, heap) *lhsc = NULL;
3352 struct constraint_expr *lhsp;
3354 get_constraint_for (lhs, &lhsc);
3356 if (flags & ECF_MALLOC)
3358 struct constraint_expr rhsc;
3359 tree heapvar = heapvar_lookup (lhs);
3362 if (heapvar == NULL)
3364 heapvar = create_tmp_var_raw (ptr_type_node, "HEAP");
3365 DECL_EXTERNAL (heapvar) = 1;
3366 get_var_ann (heapvar)->is_heapvar = 1;
3367 if (gimple_referenced_vars (cfun))
3368 add_referenced_var (heapvar);
3369 heapvar_insert (lhs, heapvar);
3372 rhsc.var = create_variable_info_for (heapvar,
3373 alias_get_name (heapvar));
3374 vi = get_varinfo (rhsc.var);
3375 vi->is_artificial_var = 1;
3376 vi->is_heap_var = 1;
3377 vi->is_unknown_size_var = true;
3380 rhsc.type = ADDRESSOF;
3382 for (j = 0; VEC_iterate (ce_s, lhsc, j, lhsp); j++)
3383 process_constraint (new_constraint (*lhsp, rhsc));
3385 else if (VEC_length (ce_s, rhsc) > 0)
3387 struct constraint_expr *lhsp, *rhsp;
3389 /* If the store is to a global decl make sure to
3390 add proper escape constraints. */
3391 lhs = get_base_address (lhs);
3394 && is_global_var (lhs))
3396 struct constraint_expr tmpc;
3397 tmpc.var = escaped_id;
3400 VEC_safe_push (ce_s, heap, lhsc, &tmpc);
3402 for (i = 0; VEC_iterate (ce_s, lhsc, i, lhsp); ++i)
3403 for (j = 0; VEC_iterate (ce_s, rhsc, j, rhsp); ++j)
3404 process_constraint (new_constraint (*lhsp, *rhsp));
3406 VEC_free (ce_s, heap, lhsc);
3409 /* For non-IPA mode, generate constraints necessary for a call of a
3410 const function that returns a pointer in the statement STMT. */
3413 handle_const_call (gimple stmt, VEC(ce_s, heap) **results)
3415 struct constraint_expr rhsc, tmpc = {SCALAR, 0, 0};
3416 tree tmpvar = NULL_TREE;
3419 /* Treat nested const functions the same as pure functions as far
3420 as the static chain is concerned. */
3421 if (gimple_call_chain (stmt))
3423 make_constraint_to (callused_id, gimple_call_chain (stmt));
3424 rhsc.var = callused_id;
3427 VEC_safe_push (ce_s, heap, *results, &rhsc);
3430 /* May return arguments. */
3431 for (k = 0; k < gimple_call_num_args (stmt); ++k)
3433 tree arg = gimple_call_arg (stmt, k);
3435 if (could_have_pointers (arg))
3437 VEC(ce_s, heap) *argc = NULL;
3438 struct constraint_expr *argp;
3441 /* We always use a temporary here, otherwise we end up with
3442 a quadratic amount of constraints for
3443 large_struct = const_call (large_struct);
3444 with field-sensitive PTA. */
3445 if (tmpvar == NULL_TREE)
3447 tmpvar = create_tmp_var_raw (ptr_type_node, "consttmp");
3448 tmpc = get_constraint_exp_for_temp (tmpvar);
3451 get_constraint_for (arg, &argc);
3452 for (i = 0; VEC_iterate (ce_s, argc, i, argp); i++)
3453 process_constraint (new_constraint (tmpc, *argp));
3454 VEC_free (ce_s, heap, argc);
3457 if (tmpvar != NULL_TREE)
3458 VEC_safe_push (ce_s, heap, *results, &tmpc);
3460 /* May return addresses of globals. */
3461 rhsc.var = nonlocal_id;
3463 rhsc.type = ADDRESSOF;
3464 VEC_safe_push (ce_s, heap, *results, &rhsc);
3467 /* For non-IPA mode, generate constraints necessary for a call to a
3468 pure function in statement STMT. */
3471 handle_pure_call (gimple stmt, VEC(ce_s, heap) **results)
3473 struct constraint_expr rhsc;
3475 bool need_callused = false;
3477 /* Memory reached from pointer arguments is call-used. */
3478 for (i = 0; i < gimple_call_num_args (stmt); ++i)
3480 tree arg = gimple_call_arg (stmt, i);
3482 if (could_have_pointers (arg))
3484 make_constraint_to (callused_id, arg);
3485 need_callused = true;
3489 /* The static chain is used as well. */
3490 if (gimple_call_chain (stmt))
3492 make_constraint_to (callused_id, gimple_call_chain (stmt));
3493 need_callused = true;
3496 /* Pure functions may return callused and nonlocal memory. */
3499 rhsc.var = callused_id;
3502 VEC_safe_push (ce_s, heap, *results, &rhsc);
3504 rhsc.var = nonlocal_id;
3507 VEC_safe_push (ce_s, heap, *results, &rhsc);
3510 /* Walk statement T setting up aliasing constraints according to the
3511 references found in T. This function is the main part of the
3512 constraint builder. AI points to auxiliary alias information used
3513 when building alias sets and computing alias grouping heuristics. */
3516 find_func_aliases (gimple origt)
3519 VEC(ce_s, heap) *lhsc = NULL;
3520 VEC(ce_s, heap) *rhsc = NULL;
3521 struct constraint_expr *c;
3522 enum escape_type stmt_escape_type;
3524 /* Now build constraints expressions. */
3525 if (gimple_code (t) == GIMPLE_PHI)
3527 gcc_assert (!AGGREGATE_TYPE_P (TREE_TYPE (gimple_phi_result (t))));
3529 /* Only care about pointers and structures containing
3531 if (could_have_pointers (gimple_phi_result (t)))
3536 /* For a phi node, assign all the arguments to
3538 get_constraint_for (gimple_phi_result (t), &lhsc);
3539 for (i = 0; i < gimple_phi_num_args (t); i++)
3542 tree strippedrhs = PHI_ARG_DEF (t, i);
3544 STRIP_NOPS (strippedrhs);
3545 rhstype = TREE_TYPE (strippedrhs);
3546 get_constraint_for (gimple_phi_arg_def (t, i), &rhsc);
3548 for (j = 0; VEC_iterate (ce_s, lhsc, j, c); j++)
3550 struct constraint_expr *c2;
3551 while (VEC_length (ce_s, rhsc) > 0)
3553 c2 = VEC_last (ce_s, rhsc);
3554 process_constraint (new_constraint (*c, *c2));
3555 VEC_pop (ce_s, rhsc);
3561 /* In IPA mode, we need to generate constraints to pass call
3562 arguments through their calls. There are two cases,
3563 either a GIMPLE_CALL returning a value, or just a plain
3564 GIMPLE_CALL when we are not.
3566 In non-ipa mode, we need to generate constraints for each
3567 pointer passed by address. */
3568 else if (is_gimple_call (t))
3572 VEC(ce_s, heap) *rhsc = NULL;
3573 int flags = gimple_call_flags (t);
3575 /* Const functions can return their arguments and addresses
3576 of global memory but not of escaped memory. */
3577 if (flags & (ECF_CONST|ECF_NOVOPS))
3579 if (gimple_call_lhs (t)
3580 && could_have_pointers (gimple_call_lhs (t)))
3581 handle_const_call (t, &rhsc);
3583 /* Pure functions can return addresses in and of memory
3584 reachable from their arguments, but they are not an escape
3585 point for reachable memory of their arguments. */
3586 else if (flags & (ECF_PURE|ECF_LOOPING_CONST_OR_PURE))
3587 handle_pure_call (t, &rhsc);
3589 handle_rhs_call (t, &rhsc);
3590 if (gimple_call_lhs (t)
3591 && could_have_pointers (gimple_call_lhs (t)))
3592 handle_lhs_call (gimple_call_lhs (t), flags, rhsc);
3593 VEC_free (ce_s, heap, rhsc);
3603 lhsop = gimple_call_lhs (t);
3604 decl = gimple_call_fndecl (t);
3606 /* If we can directly resolve the function being called, do so.
3607 Otherwise, it must be some sort of indirect expression that
3608 we should still be able to handle. */
3610 fi = get_vi_for_tree (decl);
3613 decl = gimple_call_fn (t);
3614 fi = get_vi_for_tree (decl);
3617 /* Assign all the passed arguments to the appropriate incoming
3618 parameters of the function. */
3619 for (j = 0; j < gimple_call_num_args (t); j++)
3621 struct constraint_expr lhs ;
3622 struct constraint_expr *rhsp;
3623 tree arg = gimple_call_arg (t, j);
3625 get_constraint_for (arg, &rhsc);
3626 if (TREE_CODE (decl) != FUNCTION_DECL)
3635 lhs.var = first_vi_for_offset (fi, i)->id;
3638 while (VEC_length (ce_s, rhsc) != 0)
3640 rhsp = VEC_last (ce_s, rhsc);
3641 process_constraint (new_constraint (lhs, *rhsp));
3642 VEC_pop (ce_s, rhsc);
3647 /* If we are returning a value, assign it to the result. */
3650 struct constraint_expr rhs;
3651 struct constraint_expr *lhsp;
3654 get_constraint_for (lhsop, &lhsc);
3655 if (TREE_CODE (decl) != FUNCTION_DECL)
3664 rhs.var = first_vi_for_offset (fi, i)->id;
3667 for (j = 0; VEC_iterate (ce_s, lhsc, j, lhsp); j++)
3668 process_constraint (new_constraint (*lhsp, rhs));
3672 /* Otherwise, just a regular assignment statement. Only care about
3673 operations with pointer result, others are dealt with as escape
3674 points if they have pointer operands. */
3675 else if (is_gimple_assign (t)
3676 && could_have_pointers (gimple_assign_lhs (t)))
3678 /* Otherwise, just a regular assignment statement. */
3679 tree lhsop = gimple_assign_lhs (t);
3680 tree rhsop = (gimple_num_ops (t) == 2) ? gimple_assign_rhs1 (t) : NULL;
3682 if (rhsop && AGGREGATE_TYPE_P (TREE_TYPE (lhsop)))
3683 do_structure_copy (lhsop, rhsop);
3687 struct constraint_expr temp;
3688 get_constraint_for (lhsop, &lhsc);
3690 if (gimple_assign_rhs_code (t) == POINTER_PLUS_EXPR)
3691 get_constraint_for_ptr_offset (gimple_assign_rhs1 (t),
3692 gimple_assign_rhs2 (t), &rhsc);
3693 else if ((CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (t))
3694 && !(POINTER_TYPE_P (gimple_expr_type (t))
3695 && !POINTER_TYPE_P (TREE_TYPE (rhsop))))
3696 || gimple_assign_single_p (t))
3697 get_constraint_for (rhsop, &rhsc);
3700 temp.type = ADDRESSOF;
3701 temp.var = anything_id;
3703 VEC_safe_push (ce_s, heap, rhsc, &temp);
3705 for (j = 0; VEC_iterate (ce_s, lhsc, j, c); j++)
3707 struct constraint_expr *c2;
3710 for (k = 0; VEC_iterate (ce_s, rhsc, k, c2); k++)
3711 process_constraint (new_constraint (*c, *c2));
3716 stmt_escape_type = is_escape_site (t);
3717 if (stmt_escape_type == ESCAPE_STORED_IN_GLOBAL)
3719 gcc_assert (is_gimple_assign (t));
3720 if (gimple_assign_rhs_code (t) == ADDR_EXPR)
3722 tree rhs = gimple_assign_rhs1 (t);
3723 tree base = get_base_address (TREE_OPERAND (rhs, 0));
3726 || !is_global_var (base)))
3727 make_escape_constraint (rhs);
3729 else if (get_gimple_rhs_class (gimple_assign_rhs_code (t))
3730 == GIMPLE_SINGLE_RHS)
3732 if (could_have_pointers (gimple_assign_rhs1 (t)))
3733 make_escape_constraint (gimple_assign_rhs1 (t));
3738 else if (stmt_escape_type == ESCAPE_BAD_CAST)
3740 gcc_assert (is_gimple_assign (t));
3741 gcc_assert (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (t))
3742 || gimple_assign_rhs_code (t) == VIEW_CONVERT_EXPR);
3743 make_escape_constraint (gimple_assign_rhs1 (t));
3745 else if (stmt_escape_type == ESCAPE_TO_ASM)
3747 unsigned i, noutputs;
3748 const char **oconstraints;
3749 const char *constraint;
3750 bool allows_mem, allows_reg, is_inout;
3752 noutputs = gimple_asm_noutputs (t);
3753 oconstraints = XALLOCAVEC (const char *, noutputs);
3755 for (i = 0; i < noutputs; ++i)
3757 tree link = gimple_asm_output_op (t, i);
3758 tree op = TREE_VALUE (link);
3760 constraint = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (link)));
3761 oconstraints[i] = constraint;
3762 parse_output_constraint (&constraint, i, 0, 0, &allows_mem,
3763 &allows_reg, &is_inout);
3765 /* A memory constraint makes the address of the operand escape. */
3766 if (!allows_reg && allows_mem)
3767 make_escape_constraint (build_fold_addr_expr (op));
3769 /* The asm may read global memory, so outputs may point to
3770 any global memory. */
3771 if (op && could_have_pointers (op))
3773 VEC(ce_s, heap) *lhsc = NULL;
3774 struct constraint_expr rhsc, *lhsp;
3776 get_constraint_for (op, &lhsc);
3777 rhsc.var = nonlocal_id;
3780 for (j = 0; VEC_iterate (ce_s, lhsc, j, lhsp); j++)
3781 process_constraint (new_constraint (*lhsp, rhsc));
3782 VEC_free (ce_s, heap, lhsc);
3785 for (i = 0; i < gimple_asm_ninputs (t); ++i)
3787 tree link = gimple_asm_input_op (t, i);
3788 tree op = TREE_VALUE (link);
3790 constraint = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (link)));
3792 parse_input_constraint (&constraint, 0, 0, noutputs, 0, oconstraints,
3793 &allows_mem, &allows_reg);
3795 /* A memory constraint makes the address of the operand escape. */
3796 if (!allows_reg && allows_mem)
3797 make_escape_constraint (build_fold_addr_expr (op));
3798 /* Strictly we'd only need the constraint to ESCAPED if
3799 the asm clobbers memory, otherwise using CALLUSED
3801 else if (op && could_have_pointers (op))
3802 make_escape_constraint (op);
3806 VEC_free (ce_s, heap, rhsc);
3807 VEC_free (ce_s, heap, lhsc);
3811 /* Find the first varinfo in the same variable as START that overlaps with
3812 OFFSET. Return NULL if we can't find one. */
3815 first_vi_for_offset (varinfo_t start, unsigned HOST_WIDE_INT offset)
3817 /* If the offset is outside of the variable, bail out. */
3818 if (offset >= start->fullsize)
3821 /* If we cannot reach offset from start, lookup the first field
3822 and start from there. */
3823 if (start->offset > offset)
3824 start = lookup_vi_for_tree (start->decl);
3828 /* We may not find a variable in the field list with the actual
3829 offset when when we have glommed a structure to a variable.
3830 In that case, however, offset should still be within the size
3832 if (offset >= start->offset
3833 && offset < (start->offset + start->size))
3842 /* Find the first varinfo in the same variable as START that overlaps with
3843 OFFSET. If there is no such varinfo the varinfo directly preceding
3844 OFFSET is returned. */
3847 first_or_preceding_vi_for_offset (varinfo_t start,
3848 unsigned HOST_WIDE_INT offset)
3850 /* If we cannot reach offset from start, lookup the first field
3851 and start from there. */
3852 if (start->offset > offset)
3853 start = lookup_vi_for_tree (start->decl);
3855 /* We may not find a variable in the field list with the actual
3856 offset when when we have glommed a structure to a variable.
3857 In that case, however, offset should still be within the size
3859 If we got beyond the offset we look for return the field
3860 directly preceding offset which may be the last field. */
3862 && offset >= start->offset
3863 && !(offset < (start->offset + start->size)))
3864 start = start->next;
3870 /* Insert the varinfo FIELD into the field list for BASE, at the front
3874 insert_into_field_list (varinfo_t base, varinfo_t field)
3876 varinfo_t prev = base;
3877 varinfo_t curr = base->next;
3883 /* Insert the varinfo FIELD into the field list for BASE, ordered by
3887 insert_into_field_list_sorted (varinfo_t base, varinfo_t field)
3889 varinfo_t prev = base;
3890 varinfo_t curr = base->next;
3901 if (field->offset <= curr->offset)
3906 field->next = prev->next;
3911 /* This structure is used during pushing fields onto the fieldstack
3912 to track the offset of the field, since bitpos_of_field gives it
3913 relative to its immediate containing type, and we want it relative
3914 to the ultimate containing object. */
3918 /* Offset from the base of the base containing object to this field. */
3919 HOST_WIDE_INT offset;
3921 /* Size, in bits, of the field. */
3922 unsigned HOST_WIDE_INT size;
3924 unsigned has_unknown_size : 1;
3926 unsigned may_have_pointers : 1;
3928 typedef struct fieldoff fieldoff_s;
3930 DEF_VEC_O(fieldoff_s);
3931 DEF_VEC_ALLOC_O(fieldoff_s,heap);
3933 /* qsort comparison function for two fieldoff's PA and PB */
3936 fieldoff_compare (const void *pa, const void *pb)
3938 const fieldoff_s *foa = (const fieldoff_s *)pa;
3939 const fieldoff_s *fob = (const fieldoff_s *)pb;
3940 unsigned HOST_WIDE_INT foasize, fobsize;
3942 if (foa->offset < fob->offset)
3944 else if (foa->offset > fob->offset)
3947 foasize = foa->size;
3948 fobsize = fob->size;
3949 if (foasize < fobsize)
3951 else if (foasize > fobsize)
3956 /* Sort a fieldstack according to the field offset and sizes. */
3958 sort_fieldstack (VEC(fieldoff_s,heap) *fieldstack)
3960 qsort (VEC_address (fieldoff_s, fieldstack),
3961 VEC_length (fieldoff_s, fieldstack),
3962 sizeof (fieldoff_s),
3966 /* Return true if V is a tree that we can have subvars for.
3967 Normally, this is any aggregate type. Also complex
3968 types which are not gimple registers can have subvars. */
3971 var_can_have_subvars (const_tree v)
3973 /* Volatile variables should never have subvars. */
3974 if (TREE_THIS_VOLATILE (v))
3977 /* Non decls or memory tags can never have subvars. */
3981 /* Aggregates without overlapping fields can have subvars. */
3982 if (TREE_CODE (TREE_TYPE (v)) == RECORD_TYPE)
3988 /* Given a TYPE, and a vector of field offsets FIELDSTACK, push all
3989 the fields of TYPE onto fieldstack, recording their offsets along
3992 OFFSET is used to keep track of the offset in this entire
3993 structure, rather than just the immediately containing structure.
3994 Returns the number of fields pushed. */
3997 push_fields_onto_fieldstack (tree type, VEC(fieldoff_s,heap) **fieldstack,
3998 HOST_WIDE_INT offset)
4003 if (TREE_CODE (type) != RECORD_TYPE)
4006 /* If the vector of fields is growing too big, bail out early.
4007 Callers check for VEC_length <= MAX_FIELDS_FOR_FIELD_SENSITIVE, make
4009 if (VEC_length (fieldoff_s, *fieldstack) > MAX_FIELDS_FOR_FIELD_SENSITIVE)
4012 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
4013 if (TREE_CODE (field) == FIELD_DECL)
4017 HOST_WIDE_INT foff = bitpos_of_field (field);
4019 if (!var_can_have_subvars (field)
4020 || TREE_CODE (TREE_TYPE (field)) == QUAL_UNION_TYPE
4021 || TREE_CODE (TREE_TYPE (field)) == UNION_TYPE)
4023 else if (!(pushed = push_fields_onto_fieldstack
4024 (TREE_TYPE (field), fieldstack, offset + foff))
4025 && (DECL_SIZE (field)
4026 && !integer_zerop (DECL_SIZE (field))))
4027 /* Empty structures may have actual size, like in C++. So
4028 see if we didn't push any subfields and the size is
4029 nonzero, push the field onto the stack. */
4034 fieldoff_s *pair = NULL;
4035 bool has_unknown_size = false;
4037 if (!VEC_empty (fieldoff_s, *fieldstack))
4038 pair = VEC_last (fieldoff_s, *fieldstack);
4040 if (!DECL_SIZE (field)
4041 || !host_integerp (DECL_SIZE (field), 1))
4042 has_unknown_size = true;
4044 /* If adjacent fields do not contain pointers merge them. */
4046 && !pair->may_have_pointers
4047 && !could_have_pointers (field)
4048 && !pair->has_unknown_size
4049 && !has_unknown_size
4050 && pair->offset + (HOST_WIDE_INT)pair->size == offset + foff)
4052 pair = VEC_last (fieldoff_s, *fieldstack);
4053 pair->size += TREE_INT_CST_LOW (DECL_SIZE (field));
4057 pair = VEC_safe_push (fieldoff_s, heap, *fieldstack, NULL);
4058 pair->offset = offset + foff;
4059 pair->has_unknown_size = has_unknown_size;
4060 if (!has_unknown_size)
4061 pair->size = TREE_INT_CST_LOW (DECL_SIZE (field));
4064 pair->may_have_pointers = could_have_pointers (field);
4075 /* Create a constraint ID = &FROM. */
4078 make_constraint_from (varinfo_t vi, int from)
4080 struct constraint_expr lhs, rhs;
4088 rhs.type = ADDRESSOF;
4089 process_constraint (new_constraint (lhs, rhs));
4092 /* Create a constraint ID = FROM. */
4095 make_copy_constraint (varinfo_t vi, int from)
4097 struct constraint_expr lhs, rhs;
4106 process_constraint (new_constraint (lhs, rhs));
4109 /* Count the number of arguments DECL has, and set IS_VARARGS to true
4110 if it is a varargs function. */
4113 count_num_arguments (tree decl, bool *is_varargs)
4118 for (t = TYPE_ARG_TYPES (TREE_TYPE (decl));
4122 if (TREE_VALUE (t) == void_type_node)
4132 /* Creation function node for DECL, using NAME, and return the index
4133 of the variable we've created for the function. */
4136 create_function_info_for (tree decl, const char *name)
4138 unsigned int index = VEC_length (varinfo_t, varmap);
4142 bool is_varargs = false;
4144 /* Create the variable info. */
4146 vi = new_var_info (decl, index, name);
4150 vi->fullsize = count_num_arguments (decl, &is_varargs) + 1;
4151 insert_vi_for_tree (vi->decl, vi);
4152 VEC_safe_push (varinfo_t, heap, varmap, vi);
4156 /* If it's varargs, we don't know how many arguments it has, so we
4162 vi->is_unknown_size_var = true;
4167 arg = DECL_ARGUMENTS (decl);
4169 /* Set up variables for each argument. */
4170 for (i = 1; i < vi->fullsize; i++)
4173 const char *newname;
4175 unsigned int newindex;
4176 tree argdecl = decl;
4181 newindex = VEC_length (varinfo_t, varmap);
4182 asprintf (&tempname, "%s.arg%d", name, i-1);
4183 newname = ggc_strdup (tempname);
4186 argvi = new_var_info (argdecl, newindex, newname);
4187 argvi->decl = argdecl;
4188 VEC_safe_push (varinfo_t, heap, varmap, argvi);
4191 argvi->is_full_var = true;
4192 argvi->fullsize = vi->fullsize;
4193 insert_into_field_list_sorted (vi, argvi);
4194 stats.total_vars ++;
4197 insert_vi_for_tree (arg, argvi);
4198 arg = TREE_CHAIN (arg);
4202 /* Create a variable for the return var. */
4203 if (DECL_RESULT (decl) != NULL
4204 || !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (decl))))
4207 const char *newname;
4209 unsigned int newindex;
4210 tree resultdecl = decl;
4214 if (DECL_RESULT (decl))
4215 resultdecl = DECL_RESULT (decl);
4217 newindex = VEC_length (varinfo_t, varmap);
4218 asprintf (&tempname, "%s.result", name);
4219 newname = ggc_strdup (tempname);
4222 resultvi = new_var_info (resultdecl, newindex, newname);
4223 resultvi->decl = resultdecl;
4224 VEC_safe_push (varinfo_t, heap, varmap, resultvi);
4225 resultvi->offset = i;
4227 resultvi->fullsize = vi->fullsize;
4228 resultvi->is_full_var = true;
4229 insert_into_field_list_sorted (vi, resultvi);
4230 stats.total_vars ++;
4231 if (DECL_RESULT (decl))
4232 insert_vi_for_tree (DECL_RESULT (decl), resultvi);
4238 /* Return true if FIELDSTACK contains fields that overlap.
4239 FIELDSTACK is assumed to be sorted by offset. */
4242 check_for_overlaps (VEC (fieldoff_s,heap) *fieldstack)
4244 fieldoff_s *fo = NULL;
4246 HOST_WIDE_INT lastoffset = -1;
4248 for (i = 0; VEC_iterate (fieldoff_s, fieldstack, i, fo); i++)
4250 if (fo->offset == lastoffset)
4252 lastoffset = fo->offset;
4257 /* Create a varinfo structure for NAME and DECL, and add it to VARMAP.
4258 This will also create any varinfo structures necessary for fields
4262 create_variable_info_for (tree decl, const char *name)
4264 unsigned int index = VEC_length (varinfo_t, varmap);
4266 tree decl_type = TREE_TYPE (decl);
4267 tree declsize = DECL_P (decl) ? DECL_SIZE (decl) : TYPE_SIZE (decl_type);
4268 bool is_global = DECL_P (decl) ? is_global_var (decl) : false;
4269 VEC (fieldoff_s,heap) *fieldstack = NULL;
4271 if (TREE_CODE (decl) == FUNCTION_DECL && in_ipa_mode)
4272 return create_function_info_for (decl, name);
4274 if (var_can_have_subvars (decl) && use_field_sensitive
4276 || var_ann (decl)->noalias_state == 0)
4278 || !var_ann (decl)->is_heapvar))
4279 push_fields_onto_fieldstack (decl_type, &fieldstack, 0);
4281 /* If the variable doesn't have subvars, we may end up needing to
4282 sort the field list and create fake variables for all the
4284 vi = new_var_info (decl, index, name);
4287 vi->may_have_pointers = could_have_pointers (decl);
4289 || !host_integerp (declsize, 1))
4291 vi->is_unknown_size_var = true;
4297 vi->fullsize = TREE_INT_CST_LOW (declsize);
4298 vi->size = vi->fullsize;
4301 insert_vi_for_tree (vi->decl, vi);
4302 VEC_safe_push (varinfo_t, heap, varmap, vi);
4303 if (is_global && (!flag_whole_program || !in_ipa_mode)
4304 && vi->may_have_pointers)
4307 && var_ann (decl)->noalias_state == NO_ALIAS_ANYTHING)
4308 make_constraint_from (vi, vi->id);
4310 make_copy_constraint (vi, nonlocal_id);
4314 if (use_field_sensitive
4315 && !vi->is_unknown_size_var
4316 && var_can_have_subvars (decl)
4317 && VEC_length (fieldoff_s, fieldstack) > 1
4318 && VEC_length (fieldoff_s, fieldstack) <= MAX_FIELDS_FOR_FIELD_SENSITIVE)
4320 unsigned int newindex = VEC_length (varinfo_t, varmap);
4321 fieldoff_s *fo = NULL;
4322 bool notokay = false;
4325 for (i = 0; !notokay && VEC_iterate (fieldoff_s, fieldstack, i, fo); i++)
4327 if (fo->has_unknown_size
4335 /* We can't sort them if we have a field with a variable sized type,
4336 which will make notokay = true. In that case, we are going to return
4337 without creating varinfos for the fields anyway, so sorting them is a
4341 sort_fieldstack (fieldstack);
4342 /* Due to some C++ FE issues, like PR 22488, we might end up
4343 what appear to be overlapping fields even though they,
4344 in reality, do not overlap. Until the C++ FE is fixed,
4345 we will simply disable field-sensitivity for these cases. */
4346 notokay = check_for_overlaps (fieldstack);
4350 if (VEC_length (fieldoff_s, fieldstack) != 0)
4351 fo = VEC_index (fieldoff_s, fieldstack, 0);
4353 if (fo == NULL || notokay)
4355 vi->is_unknown_size_var = 1;
4358 vi->is_full_var = true;
4359 VEC_free (fieldoff_s, heap, fieldstack);
4363 vi->size = fo->size;
4364 vi->offset = fo->offset;
4365 vi->may_have_pointers = fo->may_have_pointers;
4366 for (i = VEC_length (fieldoff_s, fieldstack) - 1;
4367 i >= 1 && VEC_iterate (fieldoff_s, fieldstack, i, fo);
4371 const char *newname = "NULL";
4374 newindex = VEC_length (varinfo_t, varmap);
4377 asprintf (&tempname, "%s." HOST_WIDE_INT_PRINT_DEC
4378 "+" HOST_WIDE_INT_PRINT_DEC,
4379 vi->name, fo->offset, fo->size);
4380 newname = ggc_strdup (tempname);
4383 newvi = new_var_info (decl, newindex, newname);
4384 newvi->offset = fo->offset;
4385 newvi->size = fo->size;
4386 newvi->fullsize = vi->fullsize;
4387 newvi->may_have_pointers = fo->may_have_pointers;
4388 insert_into_field_list (vi, newvi);
4389 VEC_safe_push (varinfo_t, heap, varmap, newvi);
4390 if (is_global && (!flag_whole_program || !in_ipa_mode)
4391 && newvi->may_have_pointers)
4392 make_copy_constraint (newvi, nonlocal_id);
4398 vi->is_full_var = true;
4400 VEC_free (fieldoff_s, heap, fieldstack);
4405 /* Print out the points-to solution for VAR to FILE. */
4408 dump_solution_for_var (FILE *file, unsigned int var)
4410 varinfo_t vi = get_varinfo (var);
4414 if (find (var) != var)
4416 varinfo_t vipt = get_varinfo (find (var));
4417 fprintf (file, "%s = same as %s\n", vi->name, vipt->name);
4421 fprintf (file, "%s = { ", vi->name);
4422 EXECUTE_IF_SET_IN_BITMAP (vi->solution, 0, i, bi)
4424 fprintf (file, "%s ", get_varinfo (i)->name);
4426 fprintf (file, "}\n");
4430 /* Print the points-to solution for VAR to stdout. */
4433 debug_solution_for_var (unsigned int var)
4435 dump_solution_for_var (stdout, var);
4438 /* Create varinfo structures for all of the variables in the
4439 function for intraprocedural mode. */
4442 intra_create_variable_infos (void)
4445 struct constraint_expr lhs, rhs;
4447 /* For each incoming pointer argument arg, create the constraint ARG
4448 = NONLOCAL or a dummy variable if flag_argument_noalias is set. */
4449 for (t = DECL_ARGUMENTS (current_function_decl); t; t = TREE_CHAIN (t))
4453 if (!could_have_pointers (t))
4456 /* If flag_argument_noalias is set, then function pointer
4457 arguments are guaranteed not to point to each other. In that
4458 case, create an artificial variable PARM_NOALIAS and the
4459 constraint ARG = &PARM_NOALIAS. */
4460 if (POINTER_TYPE_P (TREE_TYPE (t)) && flag_argument_noalias > 0)
4463 tree heapvar = heapvar_lookup (t);
4467 lhs.var = get_vi_for_tree (t)->id;
4469 if (heapvar == NULL_TREE)
4472 heapvar = create_tmp_var_raw (ptr_type_node,
4474 DECL_EXTERNAL (heapvar) = 1;
4475 if (gimple_referenced_vars (cfun))
4476 add_referenced_var (heapvar);
4478 heapvar_insert (t, heapvar);
4480 ann = get_var_ann (heapvar);
4481 ann->is_heapvar = 1;
4482 if (flag_argument_noalias == 1)
4483 ann->noalias_state = NO_ALIAS;
4484 else if (flag_argument_noalias == 2)
4485 ann->noalias_state = NO_ALIAS_GLOBAL;
4486 else if (flag_argument_noalias == 3)
4487 ann->noalias_state = NO_ALIAS_ANYTHING;
4492 vi = get_vi_for_tree (heapvar);
4493 vi->is_artificial_var = 1;
4494 vi->is_heap_var = 1;
4495 vi->is_unknown_size_var = true;
4499 rhs.type = ADDRESSOF;
4501 for (p = get_varinfo (lhs.var); p; p = p->next)
4503 struct constraint_expr temp = lhs;
4505 process_constraint (new_constraint (temp, rhs));
4510 varinfo_t arg_vi = get_vi_for_tree (t);
4512 for (p = arg_vi; p; p = p->next)
4513 make_constraint_from (p, nonlocal_id);
4517 /* Add a constraint for a result decl that is passed by reference. */
4518 if (DECL_RESULT (cfun->decl)
4519 && DECL_BY_REFERENCE (DECL_RESULT (cfun->decl)))
4521 varinfo_t p, result_vi = get_vi_for_tree (DECL_RESULT (cfun->decl));
4523 for (p = result_vi; p; p = p->next)
4524 make_constraint_from (p, nonlocal_id);
4527 /* Add a constraint for the incoming static chain parameter. */
4528 if (cfun->static_chain_decl != NULL_TREE)
4530 varinfo_t p, chain_vi = get_vi_for_tree (cfun->static_chain_decl);
4532 for (p = chain_vi; p; p = p->next)
4533 make_constraint_from (p, nonlocal_id);
4537 /* Structure used to put solution bitmaps in a hashtable so they can
4538 be shared among variables with the same points-to set. */
4540 typedef struct shared_bitmap_info
4544 } *shared_bitmap_info_t;
4545 typedef const struct shared_bitmap_info *const_shared_bitmap_info_t;
4547 static htab_t shared_bitmap_table;
4549 /* Hash function for a shared_bitmap_info_t */
4552 shared_bitmap_hash (const void *p)
4554 const_shared_bitmap_info_t const bi = (const_shared_bitmap_info_t) p;
4555 return bi->hashcode;
4558 /* Equality function for two shared_bitmap_info_t's. */
4561 shared_bitmap_eq (const void *p1, const void *p2)
4563 const_shared_bitmap_info_t const sbi1 = (const_shared_bitmap_info_t) p1;
4564 const_shared_bitmap_info_t const sbi2 = (const_shared_bitmap_info_t) p2;
4565 return bitmap_equal_p (sbi1->pt_vars, sbi2->pt_vars);
4568 /* Lookup a bitmap in the shared bitmap hashtable, and return an already
4569 existing instance if there is one, NULL otherwise. */
4572 shared_bitmap_lookup (bitmap pt_vars)
4575 struct shared_bitmap_info sbi;
4577 sbi.pt_vars = pt_vars;
4578 sbi.hashcode = bitmap_hash (pt_vars);
4580 slot = htab_find_slot_with_hash (shared_bitmap_table, &sbi,
4581 sbi.hashcode, NO_INSERT);
4585 return ((shared_bitmap_info_t) *slot)->pt_vars;
4589 /* Add a bitmap to the shared bitmap hashtable. */
4592 shared_bitmap_add (bitmap pt_vars)
4595 shared_bitmap_info_t sbi = XNEW (struct shared_bitmap_info);
4597 sbi->pt_vars = pt_vars;
4598 sbi->hashcode = bitmap_hash (pt_vars);
4600 slot = htab_find_slot_with_hash (shared_bitmap_table, sbi,
4601 sbi->hashcode, INSERT);
4602 gcc_assert (!*slot);
4603 *slot = (void *) sbi;
4607 /* Set bits in INTO corresponding to the variable uids in solution set FROM. */
4610 set_uids_in_ptset (bitmap into, bitmap from, struct pt_solution *pt)
4615 EXECUTE_IF_SET_IN_BITMAP (from, 0, i, bi)
4617 varinfo_t vi = get_varinfo (i);
4619 /* The only artificial variables that are allowed in a may-alias
4620 set are heap variables. */
4621 if (vi->is_artificial_var && !vi->is_heap_var)
4624 if (TREE_CODE (vi->decl) == VAR_DECL
4625 || TREE_CODE (vi->decl) == PARM_DECL
4626 || TREE_CODE (vi->decl) == RESULT_DECL)
4628 /* Add the decl to the points-to set. Note that the points-to
4629 set contains global variables. */
4630 bitmap_set_bit (into, DECL_UID (vi->decl));
4631 if (is_global_var (vi->decl))
4632 pt->vars_contains_global = true;
4638 static bool have_alias_info = false;
4640 /* Compute the points-to solution *PT for the variable VI. */
4643 find_what_var_points_to (varinfo_t vi, struct pt_solution *pt)
4647 bitmap finished_solution;
4649 tree ptr = vi->decl;
4651 memset (pt, 0, sizeof (struct pt_solution));
4653 /* This variable may have been collapsed, let's get the real
4655 vi = get_varinfo (find (vi->id));
4657 /* Translate artificial variables into SSA_NAME_PTR_INFO
4659 EXECUTE_IF_SET_IN_BITMAP (vi->solution, 0, i, bi)
4661 varinfo_t vi = get_varinfo (i);
4663 if (vi->is_artificial_var)
4665 if (vi->id == nothing_id)
4667 else if (vi->id == escaped_id)
4669 else if (vi->id == callused_id)
4671 else if (vi->id == nonlocal_id)
4673 else if (vi->is_heap_var)
4674 /* We represent heapvars in the points-to set properly. */
4676 else if (vi->id == anything_id
4677 || vi->id == readonly_id
4678 || vi->id == integer_id)
4683 /* Instead of doing extra work, simply do not create
4684 elaborate points-to information for pt_anything pointers. */
4688 /* Share the final set of variables when possible. */
4689 finished_solution = BITMAP_GGC_ALLOC ();
4690 stats.points_to_sets_created++;
4692 if (TREE_CODE (ptr) == SSA_NAME)
4693 ptr = SSA_NAME_VAR (ptr);
4695 set_uids_in_ptset (finished_solution, vi->solution, pt);
4696 result = shared_bitmap_lookup (finished_solution);
4699 shared_bitmap_add (finished_solution);
4700 pt->vars = finished_solution;
4705 bitmap_clear (finished_solution);
4709 /* Given a pointer variable P, fill in its points-to set. */
4712 find_what_p_points_to (tree p)
4714 struct ptr_info_def *pi;
4718 /* For parameters, get at the points-to set for the actual parm
4720 if (TREE_CODE (p) == SSA_NAME
4721 && TREE_CODE (SSA_NAME_VAR (p)) == PARM_DECL
4722 && SSA_NAME_IS_DEFAULT_DEF (p))
4723 lookup_p = SSA_NAME_VAR (p);
4725 vi = lookup_vi_for_tree (lookup_p);
4729 pi = get_ptr_info (p);
4730 find_what_var_points_to (vi, &pi->pt);
4734 /* Query statistics for points-to solutions. */
4737 unsigned HOST_WIDE_INT pt_solution_includes_may_alias;
4738 unsigned HOST_WIDE_INT pt_solution_includes_no_alias;
4739 unsigned HOST_WIDE_INT pt_solutions_intersect_may_alias;
4740 unsigned HOST_WIDE_INT pt_solutions_intersect_no_alias;
4744 dump_pta_stats (FILE *s)
4746 fprintf (s, "\nPTA query stats:\n");
4747 fprintf (s, " pt_solution_includes: "
4748 HOST_WIDE_INT_PRINT_DEC" disambiguations, "
4749 HOST_WIDE_INT_PRINT_DEC" queries\n",
4750 pta_stats.pt_solution_includes_no_alias,
4751 pta_stats.pt_solution_includes_no_alias
4752 + pta_stats.pt_solution_includes_may_alias);
4753 fprintf (s, " pt_solutions_intersect: "
4754 HOST_WIDE_INT_PRINT_DEC" disambiguations, "
4755 HOST_WIDE_INT_PRINT_DEC" queries\n",
4756 pta_stats.pt_solutions_intersect_no_alias,
4757 pta_stats.pt_solutions_intersect_no_alias
4758 + pta_stats.pt_solutions_intersect_may_alias);
4762 /* Reset the points-to solution *PT to a conservative default
4763 (point to anything). */
4766 pt_solution_reset (struct pt_solution *pt)
4768 memset (pt, 0, sizeof (struct pt_solution));
4769 pt->anything = true;
4772 /* Return true if the points-to solution *PT is empty. */
4775 pt_solution_empty_p (struct pt_solution *pt)
4782 && !bitmap_empty_p (pt->vars))
4785 /* If the solution includes ESCAPED, check if that is empty. */
4787 && !pt_solution_empty_p (&cfun->gimple_df->escaped))
4793 /* Return true if the points-to solution *PT includes global memory. */
4796 pt_solution_includes_global (struct pt_solution *pt)
4800 || pt->vars_contains_global)
4804 return pt_solution_includes_global (&cfun->gimple_df->escaped);
4809 /* Return true if the points-to solution *PT includes the variable
4810 declaration DECL. */
4813 pt_solution_includes_1 (struct pt_solution *pt, const_tree decl)
4819 && is_global_var (decl))
4823 && bitmap_bit_p (pt->vars, DECL_UID (decl)))
4826 /* If the solution includes ESCAPED, check it. */
4828 && pt_solution_includes_1 (&cfun->gimple_df->escaped, decl))
4835 pt_solution_includes (struct pt_solution *pt, const_tree decl)
4837 bool res = pt_solution_includes_1 (pt, decl);
4839 ++pta_stats.pt_solution_includes_may_alias;
4841 ++pta_stats.pt_solution_includes_no_alias;
4845 /* Return true if both points-to solutions PT1 and PT2 have a non-empty
4849 pt_solutions_intersect_1 (struct pt_solution *pt1, struct pt_solution *pt2)
4851 if (pt1->anything || pt2->anything)
4854 /* If either points to unknown global memory and the other points to
4855 any global memory they alias. */
4858 || pt2->vars_contains_global))
4860 && pt1->vars_contains_global))
4863 /* Check the escaped solution if required. */
4864 if ((pt1->escaped || pt2->escaped)
4865 && !pt_solution_empty_p (&cfun->gimple_df->escaped))
4867 /* If both point to escaped memory and that solution
4868 is not empty they alias. */
4869 if (pt1->escaped && pt2->escaped)
4872 /* If either points to escaped memory see if the escaped solution
4873 intersects with the other. */
4875 && pt_solutions_intersect_1 (&cfun->gimple_df->escaped, pt2))
4877 && pt_solutions_intersect_1 (&cfun->gimple_df->escaped, pt1)))
4881 /* Now both pointers alias if their points-to solution intersects. */
4884 && bitmap_intersect_p (pt1->vars, pt2->vars));
4888 pt_solutions_intersect (struct pt_solution *pt1, struct pt_solution *pt2)
4890 bool res = pt_solutions_intersect_1 (pt1, pt2);
4892 ++pta_stats.pt_solutions_intersect_may_alias;
4894 ++pta_stats.pt_solutions_intersect_no_alias;
4899 /* Dump points-to information to OUTFILE. */
4902 dump_sa_points_to_info (FILE *outfile)
4906 fprintf (outfile, "\nPoints-to sets\n\n");
4908 if (dump_flags & TDF_STATS)
4910 fprintf (outfile, "Stats:\n");
4911 fprintf (outfile, "Total vars: %d\n", stats.total_vars);
4912 fprintf (outfile, "Non-pointer vars: %d\n",
4913 stats.nonpointer_vars);
4914 fprintf (outfile, "Statically unified vars: %d\n",
4915 stats.unified_vars_static);
4916 fprintf (outfile, "Dynamically unified vars: %d\n",
4917 stats.unified_vars_dynamic);
4918 fprintf (outfile, "Iterations: %d\n", stats.iterations);
4919 fprintf (outfile, "Number of edges: %d\n", stats.num_edges);
4920 fprintf (outfile, "Number of implicit edges: %d\n",
4921 stats.num_implicit_edges);
4924 for (i = 0; i < VEC_length (varinfo_t, varmap); i++)
4925 dump_solution_for_var (outfile, i);
4929 /* Debug points-to information to stderr. */
4932 debug_sa_points_to_info (void)
4934 dump_sa_points_to_info (stderr);
4938 /* Initialize the always-existing constraint variables for NULL
4939 ANYTHING, READONLY, and INTEGER */
4942 init_base_vars (void)
4944 struct constraint_expr lhs, rhs;
4946 /* Create the NULL variable, used to represent that a variable points
4948 nothing_tree = create_tmp_var_raw (void_type_node, "NULL");
4949 var_nothing = new_var_info (nothing_tree, nothing_id, "NULL");
4950 insert_vi_for_tree (nothing_tree, var_nothing);
4951 var_nothing->is_artificial_var = 1;
4952 var_nothing->offset = 0;
4953 var_nothing->size = ~0;
4954 var_nothing->fullsize = ~0;
4955 var_nothing->is_special_var = 1;
4956 VEC_safe_push (varinfo_t, heap, varmap, var_nothing);
4958 /* Create the ANYTHING variable, used to represent that a variable
4959 points to some unknown piece of memory. */
4960 anything_tree = create_tmp_var_raw (ptr_type_node, "ANYTHING");
4961 var_anything = new_var_info (anything_tree, anything_id, "ANYTHING");
4962 insert_vi_for_tree (anything_tree, var_anything);
4963 var_anything->is_artificial_var = 1;
4964 var_anything->size = ~0;
4965 var_anything->offset = 0;
4966 var_anything->next = NULL;
4967 var_anything->fullsize = ~0;
4968 var_anything->is_special_var = 1;
4970 /* Anything points to anything. This makes deref constraints just
4971 work in the presence of linked list and other p = *p type loops,
4972 by saying that *ANYTHING = ANYTHING. */
4973 VEC_safe_push (varinfo_t, heap, varmap, var_anything);
4975 lhs.var = anything_id;
4977 rhs.type = ADDRESSOF;
4978 rhs.var = anything_id;
4981 /* This specifically does not use process_constraint because
4982 process_constraint ignores all anything = anything constraints, since all
4983 but this one are redundant. */
4984 VEC_safe_push (constraint_t, heap, constraints, new_constraint (lhs, rhs));
4986 /* Create the READONLY variable, used to represent that a variable
4987 points to readonly memory. */
4988 readonly_tree = create_tmp_var_raw (ptr_type_node, "READONLY");
4989 var_readonly = new_var_info (readonly_tree, readonly_id, "READONLY");
4990 var_readonly->is_artificial_var = 1;
4991 var_readonly->offset = 0;
4992 var_readonly->size = ~0;
4993 var_readonly->fullsize = ~0;
4994 var_readonly->next = NULL;
4995 var_readonly->is_special_var = 1;
4996 insert_vi_for_tree (readonly_tree, var_readonly);
4997 VEC_safe_push (varinfo_t, heap, varmap, var_readonly);
4999 /* readonly memory points to anything, in order to make deref
5000 easier. In reality, it points to anything the particular
5001 readonly variable can point to, but we don't track this
5004 lhs.var = readonly_id;
5006 rhs.type = ADDRESSOF;
5007 rhs.var = readonly_id; /* FIXME */
5009 process_constraint (new_constraint (lhs, rhs));
5011 /* Create the ESCAPED variable, used to represent the set of escaped
5013 escaped_tree = create_tmp_var_raw (ptr_type_node, "ESCAPED");
5014 var_escaped = new_var_info (escaped_tree, escaped_id, "ESCAPED");
5015 insert_vi_for_tree (escaped_tree, var_escaped);
5016 var_escaped->is_artificial_var = 1;
5017 var_escaped->offset = 0;
5018 var_escaped->size = ~0;
5019 var_escaped->fullsize = ~0;
5020 var_escaped->is_special_var = 0;
5021 VEC_safe_push (varinfo_t, heap, varmap, var_escaped);
5022 gcc_assert (VEC_index (varinfo_t, varmap, 3) == var_escaped);
5024 /* Create the NONLOCAL variable, used to represent the set of nonlocal
5026 nonlocal_tree = create_tmp_var_raw (ptr_type_node, "NONLOCAL");
5027 var_nonlocal = new_var_info (nonlocal_tree, nonlocal_id, "NONLOCAL");
5028 insert_vi_for_tree (nonlocal_tree, var_nonlocal);
5029 var_nonlocal->is_artificial_var = 1;
5030 var_nonlocal->offset = 0;
5031 var_nonlocal->size = ~0;
5032 var_nonlocal->fullsize = ~0;
5033 var_nonlocal->is_special_var = 1;
5034 VEC_safe_push (varinfo_t, heap, varmap, var_nonlocal);
5036 /* ESCAPED = *ESCAPED, because escaped is may-deref'd at calls, etc. */
5038 lhs.var = escaped_id;
5041 rhs.var = escaped_id;
5043 process_constraint (new_constraint (lhs, rhs));
5045 /* ESCAPED = ESCAPED + UNKNOWN_OFFSET, because if a sub-field escapes the
5046 whole variable escapes. */
5048 lhs.var = escaped_id;
5051 rhs.var = escaped_id;
5052 rhs.offset = UNKNOWN_OFFSET;
5053 process_constraint (new_constraint (lhs, rhs));
5055 /* *ESCAPED = NONLOCAL. This is true because we have to assume
5056 everything pointed to by escaped points to what global memory can
5059 lhs.var = escaped_id;
5062 rhs.var = nonlocal_id;
5064 process_constraint (new_constraint (lhs, rhs));
5066 /* NONLOCAL = &NONLOCAL, NONLOCAL = &ESCAPED. This is true because
5067 global memory may point to global memory and escaped memory. */
5069 lhs.var = nonlocal_id;
5071 rhs.type = ADDRESSOF;
5072 rhs.var = nonlocal_id;
5074 process_constraint (new_constraint (lhs, rhs));
5075 rhs.type = ADDRESSOF;
5076 rhs.var = escaped_id;
5078 process_constraint (new_constraint (lhs, rhs));
5080 /* Create the CALLUSED variable, used to represent the set of call-used
5082 callused_tree = create_tmp_var_raw (ptr_type_node, "CALLUSED");
5083 var_callused = new_var_info (callused_tree, callused_id, "CALLUSED");
5084 insert_vi_for_tree (callused_tree, var_callused);
5085 var_callused->is_artificial_var = 1;
5086 var_callused->offset = 0;
5087 var_callused->size = ~0;
5088 var_callused->fullsize = ~0;
5089 var_callused->is_special_var = 0;
5090 VEC_safe_push (varinfo_t, heap, varmap, var_callused);
5092 /* CALLUSED = *CALLUSED, because call-used is may-deref'd at calls, etc. */
5094 lhs.var = callused_id;
5097 rhs.var = callused_id;
5099 process_constraint (new_constraint (lhs, rhs));
5101 /* CALLUSED = CALLUSED + UNKNOWN, because if a sub-field is call-used the
5102 whole variable is call-used. */
5104 lhs.var = callused_id;
5107 rhs.var = callused_id;
5108 rhs.offset = UNKNOWN_OFFSET;
5109 process_constraint (new_constraint (lhs, rhs));
5111 /* Create the STOREDANYTHING variable, used to represent the set of
5112 variables stored to *ANYTHING. */
5113 storedanything_tree = create_tmp_var_raw (ptr_type_node, "STOREDANYTHING");
5114 var_storedanything = new_var_info (storedanything_tree, storedanything_id,
5116 insert_vi_for_tree (storedanything_tree, var_storedanything);
5117 var_storedanything->is_artificial_var = 1;
5118 var_storedanything->offset = 0;
5119 var_storedanything->size = ~0;
5120 var_storedanything->fullsize = ~0;
5121 var_storedanything->is_special_var = 0;
5122 VEC_safe_push (varinfo_t, heap, varmap, var_storedanything);
5124 /* Create the INTEGER variable, used to represent that a variable points
5125 to what an INTEGER "points to". */
5126 integer_tree = create_tmp_var_raw (ptr_type_node, "INTEGER");
5127 var_integer = new_var_info (integer_tree, integer_id, "INTEGER");
5128 insert_vi_for_tree (integer_tree, var_integer);
5129 var_integer->is_artificial_var = 1;
5130 var_integer->size = ~0;
5131 var_integer->fullsize = ~0;
5132 var_integer->offset = 0;
5133 var_integer->next = NULL;
5134 var_integer->is_special_var = 1;
5135 VEC_safe_push (varinfo_t, heap, varmap, var_integer);
5137 /* INTEGER = ANYTHING, because we don't know where a dereference of
5138 a random integer will point to. */
5140 lhs.var = integer_id;
5142 rhs.type = ADDRESSOF;
5143 rhs.var = anything_id;
5145 process_constraint (new_constraint (lhs, rhs));
5148 /* Initialize things necessary to perform PTA */
5151 init_alias_vars (void)
5153 use_field_sensitive = (MAX_FIELDS_FOR_FIELD_SENSITIVE > 1);
5155 bitmap_obstack_initialize (&pta_obstack);
5156 bitmap_obstack_initialize (&oldpta_obstack);
5157 bitmap_obstack_initialize (&predbitmap_obstack);
5159 constraint_pool = create_alloc_pool ("Constraint pool",
5160 sizeof (struct constraint), 30);
5161 variable_info_pool = create_alloc_pool ("Variable info pool",
5162 sizeof (struct variable_info), 30);
5163 constraints = VEC_alloc (constraint_t, heap, 8);
5164 varmap = VEC_alloc (varinfo_t, heap, 8);
5165 vi_for_tree = pointer_map_create ();
5167 memset (&stats, 0, sizeof (stats));
5168 shared_bitmap_table = htab_create (511, shared_bitmap_hash,
5169 shared_bitmap_eq, free);
5173 /* Remove the REF and ADDRESS edges from GRAPH, as well as all the
5174 predecessor edges. */
5177 remove_preds_and_fake_succs (constraint_graph_t graph)
5181 /* Clear the implicit ref and address nodes from the successor
5183 for (i = 0; i < FIRST_REF_NODE; i++)
5185 if (graph->succs[i])
5186 bitmap_clear_range (graph->succs[i], FIRST_REF_NODE,
5187 FIRST_REF_NODE * 2);
5190 /* Free the successor list for the non-ref nodes. */
5191 for (i = FIRST_REF_NODE; i < graph->size; i++)
5193 if (graph->succs[i])
5194 BITMAP_FREE (graph->succs[i]);
5197 /* Now reallocate the size of the successor list as, and blow away
5198 the predecessor bitmaps. */
5199 graph->size = VEC_length (varinfo_t, varmap);
5200 graph->succs = XRESIZEVEC (bitmap, graph->succs, graph->size);
5202 free (graph->implicit_preds);
5203 graph->implicit_preds = NULL;
5204 free (graph->preds);
5205 graph->preds = NULL;
5206 bitmap_obstack_release (&predbitmap_obstack);
5209 /* Initialize the heapvar for statement mapping. */
5212 init_alias_heapvars (void)
5214 if (!heapvar_for_stmt)
5215 heapvar_for_stmt = htab_create_ggc (11, tree_map_hash, tree_map_eq,
5219 /* Delete the heapvar for statement mapping. */
5222 delete_alias_heapvars (void)
5224 if (heapvar_for_stmt)
5225 htab_delete (heapvar_for_stmt);
5226 heapvar_for_stmt = NULL;
5229 /* Create points-to sets for the current function. See the comments
5230 at the start of the file for an algorithmic overview. */
5233 compute_points_to_sets (void)
5235 struct scc_info *si;
5239 timevar_push (TV_TREE_PTA);
5242 init_alias_heapvars ();
5244 intra_create_variable_infos ();
5246 /* Now walk all statements and derive aliases. */
5249 gimple_stmt_iterator gsi;
5251 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
5253 gimple phi = gsi_stmt (gsi);
5255 if (is_gimple_reg (gimple_phi_result (phi)))
5256 find_func_aliases (phi);
5259 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
5261 gimple stmt = gsi_stmt (gsi);
5263 find_func_aliases (stmt);
5269 fprintf (dump_file, "Points-to analysis\n\nConstraints:\n\n");
5270 dump_constraints (dump_file);
5275 "\nCollapsing static cycles and doing variable "
5278 init_graph (VEC_length (varinfo_t, varmap) * 2);
5281 fprintf (dump_file, "Building predecessor graph\n");
5282 build_pred_graph ();
5285 fprintf (dump_file, "Detecting pointer and location "
5287 si = perform_var_substitution (graph);
5290 fprintf (dump_file, "Rewriting constraints and unifying "
5292 rewrite_constraints (graph, si);
5294 build_succ_graph ();
5295 free_var_substitution_info (si);
5297 if (dump_file && (dump_flags & TDF_GRAPH))
5298 dump_constraint_graph (dump_file);
5300 move_complex_constraints (graph);
5303 fprintf (dump_file, "Uniting pointer but not location equivalent "
5305 unite_pointer_equivalences (graph);
5308 fprintf (dump_file, "Finding indirect cycles\n");
5309 find_indirect_cycles (graph);
5311 /* Implicit nodes and predecessors are no longer necessary at this
5313 remove_preds_and_fake_succs (graph);
5316 fprintf (dump_file, "Solving graph\n");
5318 solve_graph (graph);
5321 dump_sa_points_to_info (dump_file);
5323 /* Compute the points-to sets for ESCAPED and CALLUSED used for
5324 call-clobber analysis. */
5325 find_what_var_points_to (var_escaped, &cfun->gimple_df->escaped);
5326 find_what_var_points_to (var_callused, &cfun->gimple_df->callused);
5328 /* Make sure the ESCAPED solution (which is used as placeholder in
5329 other solutions) does not reference itself. This simplifies
5330 points-to solution queries. */
5331 cfun->gimple_df->escaped.escaped = 0;
5333 /* Compute the points-to sets for pointer SSA_NAMEs. */
5334 for (i = 0; i < num_ssa_names; ++i)
5336 tree ptr = ssa_name (i);
5338 && POINTER_TYPE_P (TREE_TYPE (ptr)))
5339 find_what_p_points_to (ptr);
5342 timevar_pop (TV_TREE_PTA);
5344 have_alias_info = true;
5348 /* Delete created points-to sets. */
5351 delete_points_to_sets (void)
5355 htab_delete (shared_bitmap_table);
5356 if (dump_file && (dump_flags & TDF_STATS))
5357 fprintf (dump_file, "Points to sets created:%d\n",
5358 stats.points_to_sets_created);
5360 pointer_map_destroy (vi_for_tree);
5361 bitmap_obstack_release (&pta_obstack);
5362 VEC_free (constraint_t, heap, constraints);
5364 for (i = 0; i < graph->size; i++)
5365 VEC_free (constraint_t, heap, graph->complex[i]);
5366 free (graph->complex);
5369 free (graph->succs);
5371 free (graph->pe_rep);
5372 free (graph->indirect_cycles);
5375 VEC_free (varinfo_t, heap, varmap);
5376 free_alloc_pool (variable_info_pool);
5377 free_alloc_pool (constraint_pool);
5378 have_alias_info = false;
5382 /* Compute points-to information for every SSA_NAME pointer in the
5383 current function and compute the transitive closure of escaped
5384 variables to re-initialize the call-clobber states of local variables. */
5387 compute_may_aliases (void)
5389 /* For each pointer P_i, determine the sets of variables that P_i may
5390 point-to. Compute the reachability set of escaped and call-used
5392 compute_points_to_sets ();
5394 /* Debugging dumps. */
5397 dump_alias_info (dump_file);
5399 if (dump_flags & TDF_DETAILS)
5400 dump_referenced_vars (dump_file);
5403 /* Deallocate memory used by aliasing data structures and the internal
5404 points-to solution. */
5405 delete_points_to_sets ();
5407 gcc_assert (!need_ssa_update_p (cfun));
5413 gate_tree_pta (void)
5415 return flag_tree_pta;
5418 /* A dummy pass to cause points-to information to be computed via
5419 TODO_rebuild_alias. */
5421 struct gimple_opt_pass pass_build_alias =
5426 gate_tree_pta, /* gate */
5430 0, /* static_pass_number */
5431 TV_NONE, /* tv_id */
5432 PROP_cfg | PROP_ssa, /* properties_required */
5433 0, /* properties_provided */
5434 0, /* properties_destroyed */
5435 0, /* todo_flags_start */
5436 TODO_rebuild_alias | TODO_dump_func /* todo_flags_finish */
5440 /* A dummy pass to cause points-to information to be computed via
5441 TODO_rebuild_alias. */
5443 struct gimple_opt_pass pass_build_ealias =
5447 "ealias", /* name */
5448 gate_tree_pta, /* gate */
5452 0, /* static_pass_number */
5453 TV_NONE, /* tv_id */
5454 PROP_cfg | PROP_ssa, /* properties_required */
5455 0, /* properties_provided */
5456 0, /* properties_destroyed */
5457 0, /* todo_flags_start */
5458 TODO_rebuild_alias | TODO_dump_func /* todo_flags_finish */
5463 /* Return true if we should execute IPA PTA. */
5467 return (flag_ipa_pta
5468 /* Don't bother doing anything if the program has errors. */
5469 && !(errorcount || sorrycount));
5472 /* Execute the driver for IPA PTA. */
5474 ipa_pta_execute (void)
5476 struct cgraph_node *node;
5477 struct scc_info *si;
5480 init_alias_heapvars ();
5483 for (node = cgraph_nodes; node; node = node->next)
5487 varid = create_function_info_for (node->decl,
5488 cgraph_node_name (node));
5489 if (node->local.externally_visible)
5491 varinfo_t fi = get_varinfo (varid);
5492 for (; fi; fi = fi->next)
5493 make_constraint_from (fi, anything_id);
5496 for (node = cgraph_nodes; node; node = node->next)
5500 struct function *func = DECL_STRUCT_FUNCTION (node->decl);
5502 tree old_func_decl = current_function_decl;
5505 "Generating constraints for %s\n",
5506 cgraph_node_name (node));
5508 current_function_decl = node->decl;
5510 FOR_EACH_BB_FN (bb, func)
5512 gimple_stmt_iterator gsi;
5514 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi);
5517 gimple phi = gsi_stmt (gsi);
5519 if (is_gimple_reg (gimple_phi_result (phi)))
5520 find_func_aliases (phi);
5523 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
5524 find_func_aliases (gsi_stmt (gsi));
5526 current_function_decl = old_func_decl;
5531 /* Make point to anything. */
5537 fprintf (dump_file, "Points-to analysis\n\nConstraints:\n\n");
5538 dump_constraints (dump_file);
5543 "\nCollapsing static cycles and doing variable "
5546 init_graph (VEC_length (varinfo_t, varmap) * 2);
5547 build_pred_graph ();
5548 si = perform_var_substitution (graph);
5549 rewrite_constraints (graph, si);
5551 build_succ_graph ();
5552 free_var_substitution_info (si);
5553 move_complex_constraints (graph);
5554 unite_pointer_equivalences (graph);
5555 find_indirect_cycles (graph);
5557 /* Implicit nodes and predecessors are no longer necessary at this
5559 remove_preds_and_fake_succs (graph);
5562 fprintf (dump_file, "\nSolving graph\n");
5564 solve_graph (graph);
5567 dump_sa_points_to_info (dump_file);
5570 delete_alias_heapvars ();
5571 delete_points_to_sets ();
5575 struct simple_ipa_opt_pass pass_ipa_pta =
5580 gate_ipa_pta, /* gate */
5581 ipa_pta_execute, /* execute */
5584 0, /* static_pass_number */
5585 TV_IPA_PTA, /* tv_id */
5586 0, /* properties_required */
5587 0, /* properties_provided */
5588 0, /* properties_destroyed */
5589 0, /* todo_flags_start */
5590 TODO_update_ssa /* todo_flags_finish */
5595 #include "gt-tree-ssa-structalias.h"