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 is a variable tracking a restrict pointer source. */
230 unsigned int is_restrict_var : 1;
232 /* True if this field may contain pointers. */
233 unsigned int may_have_pointers : 1;
235 /* True if this represents a global variable. */
236 unsigned int is_global_var : 1;
238 /* A link to the variable for the next field in this structure. */
239 struct variable_info *next;
241 /* Offset of this variable, in bits, from the base variable */
242 unsigned HOST_WIDE_INT offset;
244 /* Size of the variable, in bits. */
245 unsigned HOST_WIDE_INT size;
247 /* Full size of the base variable, in bits. */
248 unsigned HOST_WIDE_INT fullsize;
250 /* Name of this variable */
253 /* Tree that this variable is associated with. */
256 /* Points-to set for this variable. */
259 /* Old points-to set for this variable. */
262 typedef struct variable_info *varinfo_t;
264 static varinfo_t first_vi_for_offset (varinfo_t, unsigned HOST_WIDE_INT);
265 static varinfo_t first_or_preceding_vi_for_offset (varinfo_t,
266 unsigned HOST_WIDE_INT);
267 static varinfo_t lookup_vi_for_tree (tree);
269 /* Pool of variable info structures. */
270 static alloc_pool variable_info_pool;
272 DEF_VEC_P(varinfo_t);
274 DEF_VEC_ALLOC_P(varinfo_t, heap);
276 /* Table of variable info structures for constraint variables.
277 Indexed directly by variable info id. */
278 static VEC(varinfo_t,heap) *varmap;
280 /* Return the varmap element N */
282 static inline varinfo_t
283 get_varinfo (unsigned int n)
285 return VEC_index (varinfo_t, varmap, n);
288 /* Static IDs for the special variables. */
289 enum { nothing_id = 0, anything_id = 1, readonly_id = 2,
290 escaped_id = 3, nonlocal_id = 4, callused_id = 5,
291 storedanything_id = 6, integer_id = 7 };
293 struct GTY(()) heapvar_map {
295 unsigned HOST_WIDE_INT offset;
299 heapvar_map_eq (const void *p1, const void *p2)
301 const struct heapvar_map *h1 = (const struct heapvar_map *)p1;
302 const struct heapvar_map *h2 = (const struct heapvar_map *)p2;
303 return (h1->map.base.from == h2->map.base.from
304 && h1->offset == h2->offset);
308 heapvar_map_hash (struct heapvar_map *h)
310 return iterative_hash_host_wide_int (h->offset,
311 htab_hash_pointer (h->map.base.from));
314 /* Lookup a heap var for FROM, and return it if we find one. */
317 heapvar_lookup (tree from, unsigned HOST_WIDE_INT offset)
319 struct heapvar_map *h, in;
320 in.map.base.from = from;
322 h = (struct heapvar_map *) htab_find_with_hash (heapvar_for_stmt, &in,
323 heapvar_map_hash (&in));
329 /* Insert a mapping FROM->TO in the heap var for statement
333 heapvar_insert (tree from, unsigned HOST_WIDE_INT offset, tree to)
335 struct heapvar_map *h;
338 h = GGC_NEW (struct heapvar_map);
339 h->map.base.from = from;
341 h->map.hash = heapvar_map_hash (h);
343 loc = htab_find_slot_with_hash (heapvar_for_stmt, h, h->map.hash, INSERT);
344 gcc_assert (*loc == NULL);
345 *(struct heapvar_map **) loc = h;
348 /* Return a new variable info structure consisting for a variable
349 named NAME, and using constraint graph node NODE. Append it
350 to the vector of variable info structures. */
353 new_var_info (tree t, const char *name)
355 unsigned index = VEC_length (varinfo_t, varmap);
356 varinfo_t ret = (varinfo_t) pool_alloc (variable_info_pool);
361 /* Vars without decl are artificial and do not have sub-variables. */
362 ret->is_artificial_var = (t == NULL_TREE);
363 ret->is_special_var = false;
364 ret->is_unknown_size_var = false;
365 ret->is_full_var = (t == NULL_TREE);
366 ret->is_heap_var = false;
367 ret->is_restrict_var = false;
368 ret->may_have_pointers = true;
369 ret->is_global_var = (t == NULL_TREE);
371 ret->is_global_var = is_global_var (t);
372 ret->solution = BITMAP_ALLOC (&pta_obstack);
373 ret->oldsolution = BITMAP_ALLOC (&oldpta_obstack);
376 VEC_safe_push (varinfo_t, heap, varmap, ret);
381 typedef enum {SCALAR, DEREF, ADDRESSOF} constraint_expr_type;
383 /* An expression that appears in a constraint. */
385 struct constraint_expr
387 /* Constraint type. */
388 constraint_expr_type type;
390 /* Variable we are referring to in the constraint. */
393 /* Offset, in bits, of this constraint from the beginning of
394 variables it ends up referring to.
396 IOW, in a deref constraint, we would deref, get the result set,
397 then add OFFSET to each member. */
398 HOST_WIDE_INT offset;
401 /* Use 0x8000... as special unknown offset. */
402 #define UNKNOWN_OFFSET ((HOST_WIDE_INT)-1 << (HOST_BITS_PER_WIDE_INT-1))
404 typedef struct constraint_expr ce_s;
406 DEF_VEC_ALLOC_O(ce_s, heap);
407 static void get_constraint_for_1 (tree, VEC(ce_s, heap) **, bool);
408 static void get_constraint_for (tree, VEC(ce_s, heap) **);
409 static void do_deref (VEC (ce_s, heap) **);
411 /* Our set constraints are made up of two constraint expressions, one
414 As described in the introduction, our set constraints each represent an
415 operation between set valued variables.
419 struct constraint_expr lhs;
420 struct constraint_expr rhs;
423 /* List of constraints that we use to build the constraint graph from. */
425 static VEC(constraint_t,heap) *constraints;
426 static alloc_pool constraint_pool;
428 /* The constraint graph is represented as an array of bitmaps
429 containing successor nodes. */
431 struct constraint_graph
433 /* Size of this graph, which may be different than the number of
434 nodes in the variable map. */
437 /* Explicit successors of each node. */
440 /* Implicit predecessors of each node (Used for variable
442 bitmap *implicit_preds;
444 /* Explicit predecessors of each node (Used for variable substitution). */
447 /* Indirect cycle representatives, or -1 if the node has no indirect
449 int *indirect_cycles;
451 /* Representative node for a node. rep[a] == a unless the node has
455 /* Equivalence class representative for a label. This is used for
456 variable substitution. */
459 /* Pointer equivalence label for a node. All nodes with the same
460 pointer equivalence label can be unified together at some point
461 (either during constraint optimization or after the constraint
465 /* Pointer equivalence representative for a label. This is used to
466 handle nodes that are pointer equivalent but not location
467 equivalent. We can unite these once the addressof constraints
468 are transformed into initial points-to sets. */
471 /* Pointer equivalence label for each node, used during variable
473 unsigned int *pointer_label;
475 /* Location equivalence label for each node, used during location
476 equivalence finding. */
477 unsigned int *loc_label;
479 /* Pointed-by set for each node, used during location equivalence
480 finding. This is pointed-by rather than pointed-to, because it
481 is constructed using the predecessor graph. */
484 /* Points to sets for pointer equivalence. This is *not* the actual
485 points-to sets for nodes. */
488 /* Bitmap of nodes where the bit is set if the node is a direct
489 node. Used for variable substitution. */
490 sbitmap direct_nodes;
492 /* Bitmap of nodes where the bit is set if the node is address
493 taken. Used for variable substitution. */
494 bitmap address_taken;
496 /* Vector of complex constraints for each graph node. Complex
497 constraints are those involving dereferences or offsets that are
499 VEC(constraint_t,heap) **complex;
502 static constraint_graph_t graph;
504 /* During variable substitution and the offline version of indirect
505 cycle finding, we create nodes to represent dereferences and
506 address taken constraints. These represent where these start and
508 #define FIRST_REF_NODE (VEC_length (varinfo_t, varmap))
509 #define LAST_REF_NODE (FIRST_REF_NODE + (FIRST_REF_NODE - 1))
511 /* Return the representative node for NODE, if NODE has been unioned
513 This function performs path compression along the way to finding
514 the representative. */
517 find (unsigned int node)
519 gcc_assert (node < graph->size);
520 if (graph->rep[node] != node)
521 return graph->rep[node] = find (graph->rep[node]);
525 /* Union the TO and FROM nodes to the TO nodes.
526 Note that at some point in the future, we may want to do
527 union-by-rank, in which case we are going to have to return the
528 node we unified to. */
531 unite (unsigned int to, unsigned int from)
533 gcc_assert (to < graph->size && from < graph->size);
534 if (to != from && graph->rep[from] != to)
536 graph->rep[from] = to;
542 /* Create a new constraint consisting of LHS and RHS expressions. */
545 new_constraint (const struct constraint_expr lhs,
546 const struct constraint_expr rhs)
548 constraint_t ret = (constraint_t) pool_alloc (constraint_pool);
554 /* Print out constraint C to FILE. */
557 dump_constraint (FILE *file, constraint_t c)
559 if (c->lhs.type == ADDRESSOF)
561 else if (c->lhs.type == DEREF)
563 fprintf (file, "%s", get_varinfo (c->lhs.var)->name);
564 if (c->lhs.offset == UNKNOWN_OFFSET)
565 fprintf (file, " + UNKNOWN");
566 else if (c->lhs.offset != 0)
567 fprintf (file, " + " HOST_WIDE_INT_PRINT_DEC, c->lhs.offset);
568 fprintf (file, " = ");
569 if (c->rhs.type == ADDRESSOF)
571 else if (c->rhs.type == DEREF)
573 fprintf (file, "%s", get_varinfo (c->rhs.var)->name);
574 if (c->rhs.offset == UNKNOWN_OFFSET)
575 fprintf (file, " + UNKNOWN");
576 else if (c->rhs.offset != 0)
577 fprintf (file, " + " HOST_WIDE_INT_PRINT_DEC, c->rhs.offset);
578 fprintf (file, "\n");
582 void debug_constraint (constraint_t);
583 void debug_constraints (void);
584 void debug_constraint_graph (void);
585 void debug_solution_for_var (unsigned int);
586 void debug_sa_points_to_info (void);
588 /* Print out constraint C to stderr. */
591 debug_constraint (constraint_t c)
593 dump_constraint (stderr, c);
596 /* Print out all constraints to FILE */
599 dump_constraints (FILE *file)
603 for (i = 0; VEC_iterate (constraint_t, constraints, i, c); i++)
604 dump_constraint (file, c);
607 /* Print out all constraints to stderr. */
610 debug_constraints (void)
612 dump_constraints (stderr);
615 /* Print out to FILE the edge in the constraint graph that is created by
616 constraint c. The edge may have a label, depending on the type of
617 constraint that it represents. If complex1, e.g: a = *b, then the label
618 is "=*", if complex2, e.g: *a = b, then the label is "*=", if
619 complex with an offset, e.g: a = b + 8, then the label is "+".
620 Otherwise the edge has no label. */
623 dump_constraint_edge (FILE *file, constraint_t c)
625 if (c->rhs.type != ADDRESSOF)
627 const char *src = get_varinfo (c->rhs.var)->name;
628 const char *dst = get_varinfo (c->lhs.var)->name;
629 fprintf (file, " \"%s\" -> \"%s\" ", src, dst);
630 /* Due to preprocessing of constraints, instructions like *a = *b are
631 illegal; thus, we do not have to handle such cases. */
632 if (c->lhs.type == DEREF)
633 fprintf (file, " [ label=\"*=\" ] ;\n");
634 else if (c->rhs.type == DEREF)
635 fprintf (file, " [ label=\"=*\" ] ;\n");
638 /* We must check the case where the constraint is an offset.
639 In this case, it is treated as a complex constraint. */
640 if (c->rhs.offset != c->lhs.offset)
641 fprintf (file, " [ label=\"+\" ] ;\n");
643 fprintf (file, " ;\n");
648 /* Print the constraint graph in dot format. */
651 dump_constraint_graph (FILE *file)
653 unsigned int i=0, size;
656 /* Only print the graph if it has already been initialized: */
660 /* Print the constraints used to produce the constraint graph. The
661 constraints will be printed as comments in the dot file: */
662 fprintf (file, "\n\n/* Constraints used in the constraint graph:\n");
663 dump_constraints (file);
664 fprintf (file, "*/\n");
666 /* Prints the header of the dot file: */
667 fprintf (file, "\n\n// The constraint graph in dot format:\n");
668 fprintf (file, "strict digraph {\n");
669 fprintf (file, " node [\n shape = box\n ]\n");
670 fprintf (file, " edge [\n fontsize = \"12\"\n ]\n");
671 fprintf (file, "\n // List of nodes in the constraint graph:\n");
673 /* The next lines print the nodes in the graph. In order to get the
674 number of nodes in the graph, we must choose the minimum between the
675 vector VEC (varinfo_t, varmap) and graph->size. If the graph has not
676 yet been initialized, then graph->size == 0, otherwise we must only
677 read nodes that have an entry in VEC (varinfo_t, varmap). */
678 size = VEC_length (varinfo_t, varmap);
679 size = size < graph->size ? size : graph->size;
680 for (i = 0; i < size; i++)
682 const char *name = get_varinfo (graph->rep[i])->name;
683 fprintf (file, " \"%s\" ;\n", name);
686 /* Go over the list of constraints printing the edges in the constraint
688 fprintf (file, "\n // The constraint edges:\n");
689 for (i = 0; VEC_iterate (constraint_t, constraints, i, c); i++)
691 dump_constraint_edge (file, c);
693 /* Prints the tail of the dot file. By now, only the closing bracket. */
694 fprintf (file, "}\n\n\n");
697 /* Print out the constraint graph to stderr. */
700 debug_constraint_graph (void)
702 dump_constraint_graph (stderr);
707 The solver is a simple worklist solver, that works on the following
710 sbitmap changed_nodes = all zeroes;
712 For each node that is not already collapsed:
714 set bit in changed nodes
716 while (changed_count > 0)
718 compute topological ordering for constraint graph
720 find and collapse cycles in the constraint graph (updating
721 changed if necessary)
723 for each node (n) in the graph in topological order:
726 Process each complex constraint associated with the node,
727 updating changed if necessary.
729 For each outgoing edge from n, propagate the solution from n to
730 the destination of the edge, updating changed as necessary.
734 /* Return true if two constraint expressions A and B are equal. */
737 constraint_expr_equal (struct constraint_expr a, struct constraint_expr b)
739 return a.type == b.type && a.var == b.var && a.offset == b.offset;
742 /* Return true if constraint expression A is less than constraint expression
743 B. This is just arbitrary, but consistent, in order to give them an
747 constraint_expr_less (struct constraint_expr a, struct constraint_expr b)
749 if (a.type == b.type)
752 return a.offset < b.offset;
754 return a.var < b.var;
757 return a.type < b.type;
760 /* Return true if constraint A is less than constraint B. This is just
761 arbitrary, but consistent, in order to give them an ordering. */
764 constraint_less (const constraint_t a, const constraint_t b)
766 if (constraint_expr_less (a->lhs, b->lhs))
768 else if (constraint_expr_less (b->lhs, a->lhs))
771 return constraint_expr_less (a->rhs, b->rhs);
774 /* Return true if two constraints A and B are equal. */
777 constraint_equal (struct constraint a, struct constraint b)
779 return constraint_expr_equal (a.lhs, b.lhs)
780 && constraint_expr_equal (a.rhs, b.rhs);
784 /* Find a constraint LOOKFOR in the sorted constraint vector VEC */
787 constraint_vec_find (VEC(constraint_t,heap) *vec,
788 struct constraint lookfor)
796 place = VEC_lower_bound (constraint_t, vec, &lookfor, constraint_less);
797 if (place >= VEC_length (constraint_t, vec))
799 found = VEC_index (constraint_t, vec, place);
800 if (!constraint_equal (*found, lookfor))
805 /* Union two constraint vectors, TO and FROM. Put the result in TO. */
808 constraint_set_union (VEC(constraint_t,heap) **to,
809 VEC(constraint_t,heap) **from)
814 for (i = 0; VEC_iterate (constraint_t, *from, i, c); i++)
816 if (constraint_vec_find (*to, *c) == NULL)
818 unsigned int place = VEC_lower_bound (constraint_t, *to, c,
820 VEC_safe_insert (constraint_t, heap, *to, place, c);
825 /* Expands the solution in SET to all sub-fields of variables included.
826 Union the expanded result into RESULT. */
829 solution_set_expand (bitmap result, bitmap set)
835 /* In a first pass record all variables we need to add all
836 sub-fields off. This avoids quadratic behavior. */
837 EXECUTE_IF_SET_IN_BITMAP (set, 0, j, bi)
839 varinfo_t v = get_varinfo (j);
840 if (v->is_artificial_var
843 v = lookup_vi_for_tree (v->decl);
845 vars = BITMAP_ALLOC (NULL);
846 bitmap_set_bit (vars, v->id);
849 /* In the second pass now do the addition to the solution and
850 to speed up solving add it to the delta as well. */
853 EXECUTE_IF_SET_IN_BITMAP (vars, 0, j, bi)
855 varinfo_t v = get_varinfo (j);
856 for (; v != NULL; v = v->next)
857 bitmap_set_bit (result, v->id);
863 /* Take a solution set SET, add OFFSET to each member of the set, and
864 overwrite SET with the result when done. */
867 solution_set_add (bitmap set, HOST_WIDE_INT offset)
869 bitmap result = BITMAP_ALLOC (&iteration_obstack);
873 /* If the offset is unknown we have to expand the solution to
875 if (offset == UNKNOWN_OFFSET)
877 solution_set_expand (set, set);
881 EXECUTE_IF_SET_IN_BITMAP (set, 0, i, bi)
883 varinfo_t vi = get_varinfo (i);
885 /* If this is a variable with just one field just set its bit
887 if (vi->is_artificial_var
888 || vi->is_unknown_size_var
890 bitmap_set_bit (result, i);
893 unsigned HOST_WIDE_INT fieldoffset = vi->offset + offset;
895 /* If the offset makes the pointer point to before the
896 variable use offset zero for the field lookup. */
898 && fieldoffset > vi->offset)
902 vi = first_or_preceding_vi_for_offset (vi, fieldoffset);
904 bitmap_set_bit (result, vi->id);
905 /* If the result is not exactly at fieldoffset include the next
906 field as well. See get_constraint_for_ptr_offset for more
908 if (vi->offset != fieldoffset
910 bitmap_set_bit (result, vi->next->id);
914 bitmap_copy (set, result);
915 BITMAP_FREE (result);
918 /* Union solution sets TO and FROM, and add INC to each member of FROM in the
922 set_union_with_increment (bitmap to, bitmap from, HOST_WIDE_INT inc)
925 return bitmap_ior_into (to, from);
931 tmp = BITMAP_ALLOC (&iteration_obstack);
932 bitmap_copy (tmp, from);
933 solution_set_add (tmp, inc);
934 res = bitmap_ior_into (to, tmp);
940 /* Insert constraint C into the list of complex constraints for graph
944 insert_into_complex (constraint_graph_t graph,
945 unsigned int var, constraint_t c)
947 VEC (constraint_t, heap) *complex = graph->complex[var];
948 unsigned int place = VEC_lower_bound (constraint_t, complex, c,
951 /* Only insert constraints that do not already exist. */
952 if (place >= VEC_length (constraint_t, complex)
953 || !constraint_equal (*c, *VEC_index (constraint_t, complex, place)))
954 VEC_safe_insert (constraint_t, heap, graph->complex[var], place, c);
958 /* Condense two variable nodes into a single variable node, by moving
959 all associated info from SRC to TO. */
962 merge_node_constraints (constraint_graph_t graph, unsigned int to,
968 gcc_assert (find (from) == to);
970 /* Move all complex constraints from src node into to node */
971 for (i = 0; VEC_iterate (constraint_t, graph->complex[from], i, c); i++)
973 /* In complex constraints for node src, we may have either
974 a = *src, and *src = a, or an offseted constraint which are
975 always added to the rhs node's constraints. */
977 if (c->rhs.type == DEREF)
979 else if (c->lhs.type == DEREF)
984 constraint_set_union (&graph->complex[to], &graph->complex[from]);
985 VEC_free (constraint_t, heap, graph->complex[from]);
986 graph->complex[from] = NULL;
990 /* Remove edges involving NODE from GRAPH. */
993 clear_edges_for_node (constraint_graph_t graph, unsigned int node)
995 if (graph->succs[node])
996 BITMAP_FREE (graph->succs[node]);
999 /* Merge GRAPH nodes FROM and TO into node TO. */
1002 merge_graph_nodes (constraint_graph_t graph, unsigned int to,
1005 if (graph->indirect_cycles[from] != -1)
1007 /* If we have indirect cycles with the from node, and we have
1008 none on the to node, the to node has indirect cycles from the
1009 from node now that they are unified.
1010 If indirect cycles exist on both, unify the nodes that they
1011 are in a cycle with, since we know they are in a cycle with
1013 if (graph->indirect_cycles[to] == -1)
1014 graph->indirect_cycles[to] = graph->indirect_cycles[from];
1017 /* Merge all the successor edges. */
1018 if (graph->succs[from])
1020 if (!graph->succs[to])
1021 graph->succs[to] = BITMAP_ALLOC (&pta_obstack);
1022 bitmap_ior_into (graph->succs[to],
1023 graph->succs[from]);
1026 clear_edges_for_node (graph, from);
1030 /* Add an indirect graph edge to GRAPH, going from TO to FROM if
1031 it doesn't exist in the graph already. */
1034 add_implicit_graph_edge (constraint_graph_t graph, unsigned int to,
1040 if (!graph->implicit_preds[to])
1041 graph->implicit_preds[to] = BITMAP_ALLOC (&predbitmap_obstack);
1043 if (bitmap_set_bit (graph->implicit_preds[to], from))
1044 stats.num_implicit_edges++;
1047 /* Add a predecessor graph edge to GRAPH, going from TO to FROM if
1048 it doesn't exist in the graph already.
1049 Return false if the edge already existed, true otherwise. */
1052 add_pred_graph_edge (constraint_graph_t graph, unsigned int to,
1055 if (!graph->preds[to])
1056 graph->preds[to] = BITMAP_ALLOC (&predbitmap_obstack);
1057 bitmap_set_bit (graph->preds[to], from);
1060 /* Add a graph edge to GRAPH, going from FROM to TO if
1061 it doesn't exist in the graph already.
1062 Return false if the edge already existed, true otherwise. */
1065 add_graph_edge (constraint_graph_t graph, unsigned int to,
1076 if (!graph->succs[from])
1077 graph->succs[from] = BITMAP_ALLOC (&pta_obstack);
1078 if (bitmap_set_bit (graph->succs[from], to))
1081 if (to < FIRST_REF_NODE && from < FIRST_REF_NODE)
1089 /* Return true if {DEST.SRC} is an existing graph edge in GRAPH. */
1092 valid_graph_edge (constraint_graph_t graph, unsigned int src,
1095 return (graph->succs[dest]
1096 && bitmap_bit_p (graph->succs[dest], src));
1099 /* Initialize the constraint graph structure to contain SIZE nodes. */
1102 init_graph (unsigned int size)
1106 graph = XCNEW (struct constraint_graph);
1108 graph->succs = XCNEWVEC (bitmap, graph->size);
1109 graph->indirect_cycles = XNEWVEC (int, graph->size);
1110 graph->rep = XNEWVEC (unsigned int, graph->size);
1111 graph->complex = XCNEWVEC (VEC(constraint_t, heap) *, size);
1112 graph->pe = XCNEWVEC (unsigned int, graph->size);
1113 graph->pe_rep = XNEWVEC (int, graph->size);
1115 for (j = 0; j < graph->size; j++)
1118 graph->pe_rep[j] = -1;
1119 graph->indirect_cycles[j] = -1;
1123 /* Build the constraint graph, adding only predecessor edges right now. */
1126 build_pred_graph (void)
1132 graph->implicit_preds = XCNEWVEC (bitmap, graph->size);
1133 graph->preds = XCNEWVEC (bitmap, graph->size);
1134 graph->pointer_label = XCNEWVEC (unsigned int, graph->size);
1135 graph->loc_label = XCNEWVEC (unsigned int, graph->size);
1136 graph->pointed_by = XCNEWVEC (bitmap, graph->size);
1137 graph->points_to = XCNEWVEC (bitmap, graph->size);
1138 graph->eq_rep = XNEWVEC (int, graph->size);
1139 graph->direct_nodes = sbitmap_alloc (graph->size);
1140 graph->address_taken = BITMAP_ALLOC (&predbitmap_obstack);
1141 sbitmap_zero (graph->direct_nodes);
1143 for (j = 0; j < FIRST_REF_NODE; j++)
1145 if (!get_varinfo (j)->is_special_var)
1146 SET_BIT (graph->direct_nodes, j);
1149 for (j = 0; j < graph->size; j++)
1150 graph->eq_rep[j] = -1;
1152 for (j = 0; j < VEC_length (varinfo_t, varmap); j++)
1153 graph->indirect_cycles[j] = -1;
1155 for (i = 0; VEC_iterate (constraint_t, constraints, i, c); i++)
1157 struct constraint_expr lhs = c->lhs;
1158 struct constraint_expr rhs = c->rhs;
1159 unsigned int lhsvar = lhs.var;
1160 unsigned int rhsvar = rhs.var;
1162 if (lhs.type == DEREF)
1165 if (rhs.offset == 0 && lhs.offset == 0 && rhs.type == SCALAR)
1166 add_pred_graph_edge (graph, FIRST_REF_NODE + lhsvar, rhsvar);
1168 else if (rhs.type == DEREF)
1171 if (rhs.offset == 0 && lhs.offset == 0 && lhs.type == SCALAR)
1172 add_pred_graph_edge (graph, lhsvar, FIRST_REF_NODE + rhsvar);
1174 RESET_BIT (graph->direct_nodes, lhsvar);
1176 else if (rhs.type == ADDRESSOF)
1181 if (graph->points_to[lhsvar] == NULL)
1182 graph->points_to[lhsvar] = BITMAP_ALLOC (&predbitmap_obstack);
1183 bitmap_set_bit (graph->points_to[lhsvar], rhsvar);
1185 if (graph->pointed_by[rhsvar] == NULL)
1186 graph->pointed_by[rhsvar] = BITMAP_ALLOC (&predbitmap_obstack);
1187 bitmap_set_bit (graph->pointed_by[rhsvar], lhsvar);
1189 /* Implicitly, *x = y */
1190 add_implicit_graph_edge (graph, FIRST_REF_NODE + lhsvar, rhsvar);
1192 /* All related variables are no longer direct nodes. */
1193 RESET_BIT (graph->direct_nodes, rhsvar);
1194 v = get_varinfo (rhsvar);
1195 if (!v->is_full_var)
1197 v = lookup_vi_for_tree (v->decl);
1200 RESET_BIT (graph->direct_nodes, v->id);
1205 bitmap_set_bit (graph->address_taken, rhsvar);
1207 else if (lhsvar > anything_id
1208 && lhsvar != rhsvar && lhs.offset == 0 && rhs.offset == 0)
1211 add_pred_graph_edge (graph, lhsvar, rhsvar);
1212 /* Implicitly, *x = *y */
1213 add_implicit_graph_edge (graph, FIRST_REF_NODE + lhsvar,
1214 FIRST_REF_NODE + rhsvar);
1216 else if (lhs.offset != 0 || rhs.offset != 0)
1218 if (rhs.offset != 0)
1219 RESET_BIT (graph->direct_nodes, lhs.var);
1220 else if (lhs.offset != 0)
1221 RESET_BIT (graph->direct_nodes, rhs.var);
1226 /* Build the constraint graph, adding successor edges. */
1229 build_succ_graph (void)
1234 for (i = 0; VEC_iterate (constraint_t, constraints, i, c); i++)
1236 struct constraint_expr lhs;
1237 struct constraint_expr rhs;
1238 unsigned int lhsvar;
1239 unsigned int rhsvar;
1246 lhsvar = find (lhs.var);
1247 rhsvar = find (rhs.var);
1249 if (lhs.type == DEREF)
1251 if (rhs.offset == 0 && lhs.offset == 0 && rhs.type == SCALAR)
1252 add_graph_edge (graph, FIRST_REF_NODE + lhsvar, rhsvar);
1254 else if (rhs.type == DEREF)
1256 if (rhs.offset == 0 && lhs.offset == 0 && lhs.type == SCALAR)
1257 add_graph_edge (graph, lhsvar, FIRST_REF_NODE + rhsvar);
1259 else if (rhs.type == ADDRESSOF)
1262 gcc_assert (find (rhs.var) == rhs.var);
1263 bitmap_set_bit (get_varinfo (lhsvar)->solution, rhsvar);
1265 else if (lhsvar > anything_id
1266 && lhsvar != rhsvar && lhs.offset == 0 && rhs.offset == 0)
1268 add_graph_edge (graph, lhsvar, rhsvar);
1272 /* Add edges from STOREDANYTHING to all non-direct nodes. */
1273 t = find (storedanything_id);
1274 for (i = integer_id + 1; i < FIRST_REF_NODE; ++i)
1276 if (!TEST_BIT (graph->direct_nodes, i))
1277 add_graph_edge (graph, find (i), t);
1282 /* Changed variables on the last iteration. */
1283 static unsigned int changed_count;
1284 static sbitmap changed;
1286 /* Strongly Connected Component visitation info. */
1293 unsigned int *node_mapping;
1295 VEC(unsigned,heap) *scc_stack;
1299 /* Recursive routine to find strongly connected components in GRAPH.
1300 SI is the SCC info to store the information in, and N is the id of current
1301 graph node we are processing.
1303 This is Tarjan's strongly connected component finding algorithm, as
1304 modified by Nuutila to keep only non-root nodes on the stack.
1305 The algorithm can be found in "On finding the strongly connected
1306 connected components in a directed graph" by Esko Nuutila and Eljas
1307 Soisalon-Soininen, in Information Processing Letters volume 49,
1308 number 1, pages 9-14. */
1311 scc_visit (constraint_graph_t graph, struct scc_info *si, unsigned int n)
1315 unsigned int my_dfs;
1317 SET_BIT (si->visited, n);
1318 si->dfs[n] = si->current_index ++;
1319 my_dfs = si->dfs[n];
1321 /* Visit all the successors. */
1322 EXECUTE_IF_IN_NONNULL_BITMAP (graph->succs[n], 0, i, bi)
1326 if (i > LAST_REF_NODE)
1330 if (TEST_BIT (si->deleted, w))
1333 if (!TEST_BIT (si->visited, w))
1334 scc_visit (graph, si, w);
1336 unsigned int t = find (w);
1337 unsigned int nnode = find (n);
1338 gcc_assert (nnode == n);
1340 if (si->dfs[t] < si->dfs[nnode])
1341 si->dfs[n] = si->dfs[t];
1345 /* See if any components have been identified. */
1346 if (si->dfs[n] == my_dfs)
1348 if (VEC_length (unsigned, si->scc_stack) > 0
1349 && si->dfs[VEC_last (unsigned, si->scc_stack)] >= my_dfs)
1351 bitmap scc = BITMAP_ALLOC (NULL);
1352 bool have_ref_node = n >= FIRST_REF_NODE;
1353 unsigned int lowest_node;
1356 bitmap_set_bit (scc, n);
1358 while (VEC_length (unsigned, si->scc_stack) != 0
1359 && si->dfs[VEC_last (unsigned, si->scc_stack)] >= my_dfs)
1361 unsigned int w = VEC_pop (unsigned, si->scc_stack);
1363 bitmap_set_bit (scc, w);
1364 if (w >= FIRST_REF_NODE)
1365 have_ref_node = true;
1368 lowest_node = bitmap_first_set_bit (scc);
1369 gcc_assert (lowest_node < FIRST_REF_NODE);
1371 /* Collapse the SCC nodes into a single node, and mark the
1373 EXECUTE_IF_SET_IN_BITMAP (scc, 0, i, bi)
1375 if (i < FIRST_REF_NODE)
1377 if (unite (lowest_node, i))
1378 unify_nodes (graph, lowest_node, i, false);
1382 unite (lowest_node, i);
1383 graph->indirect_cycles[i - FIRST_REF_NODE] = lowest_node;
1387 SET_BIT (si->deleted, n);
1390 VEC_safe_push (unsigned, heap, si->scc_stack, n);
1393 /* Unify node FROM into node TO, updating the changed count if
1394 necessary when UPDATE_CHANGED is true. */
1397 unify_nodes (constraint_graph_t graph, unsigned int to, unsigned int from,
1398 bool update_changed)
1401 gcc_assert (to != from && find (to) == to);
1402 if (dump_file && (dump_flags & TDF_DETAILS))
1403 fprintf (dump_file, "Unifying %s to %s\n",
1404 get_varinfo (from)->name,
1405 get_varinfo (to)->name);
1408 stats.unified_vars_dynamic++;
1410 stats.unified_vars_static++;
1412 merge_graph_nodes (graph, to, from);
1413 merge_node_constraints (graph, to, from);
1415 /* Mark TO as changed if FROM was changed. If TO was already marked
1416 as changed, decrease the changed count. */
1418 if (update_changed && TEST_BIT (changed, from))
1420 RESET_BIT (changed, from);
1421 if (!TEST_BIT (changed, to))
1422 SET_BIT (changed, to);
1425 gcc_assert (changed_count > 0);
1429 if (get_varinfo (from)->solution)
1431 /* If the solution changes because of the merging, we need to mark
1432 the variable as changed. */
1433 if (bitmap_ior_into (get_varinfo (to)->solution,
1434 get_varinfo (from)->solution))
1436 if (update_changed && !TEST_BIT (changed, to))
1438 SET_BIT (changed, to);
1443 BITMAP_FREE (get_varinfo (from)->solution);
1444 BITMAP_FREE (get_varinfo (from)->oldsolution);
1446 if (stats.iterations > 0)
1448 BITMAP_FREE (get_varinfo (to)->oldsolution);
1449 get_varinfo (to)->oldsolution = BITMAP_ALLOC (&oldpta_obstack);
1452 if (valid_graph_edge (graph, to, to))
1454 if (graph->succs[to])
1455 bitmap_clear_bit (graph->succs[to], to);
1459 /* Information needed to compute the topological ordering of a graph. */
1463 /* sbitmap of visited nodes. */
1465 /* Array that stores the topological order of the graph, *in
1467 VEC(unsigned,heap) *topo_order;
1471 /* Initialize and return a topological info structure. */
1473 static struct topo_info *
1474 init_topo_info (void)
1476 size_t size = graph->size;
1477 struct topo_info *ti = XNEW (struct topo_info);
1478 ti->visited = sbitmap_alloc (size);
1479 sbitmap_zero (ti->visited);
1480 ti->topo_order = VEC_alloc (unsigned, heap, 1);
1485 /* Free the topological sort info pointed to by TI. */
1488 free_topo_info (struct topo_info *ti)
1490 sbitmap_free (ti->visited);
1491 VEC_free (unsigned, heap, ti->topo_order);
1495 /* Visit the graph in topological order, and store the order in the
1496 topo_info structure. */
1499 topo_visit (constraint_graph_t graph, struct topo_info *ti,
1505 SET_BIT (ti->visited, n);
1507 if (graph->succs[n])
1508 EXECUTE_IF_SET_IN_BITMAP (graph->succs[n], 0, j, bi)
1510 if (!TEST_BIT (ti->visited, j))
1511 topo_visit (graph, ti, j);
1514 VEC_safe_push (unsigned, heap, ti->topo_order, n);
1517 /* Process a constraint C that represents x = *(y + off), using DELTA as the
1518 starting solution for y. */
1521 do_sd_constraint (constraint_graph_t graph, constraint_t c,
1524 unsigned int lhs = c->lhs.var;
1526 bitmap sol = get_varinfo (lhs)->solution;
1529 HOST_WIDE_INT roffset = c->rhs.offset;
1531 /* Our IL does not allow this. */
1532 gcc_assert (c->lhs.offset == 0);
1534 /* If the solution of Y contains anything it is good enough to transfer
1536 if (bitmap_bit_p (delta, anything_id))
1538 flag |= bitmap_set_bit (sol, anything_id);
1542 /* If we do not know at with offset the rhs is dereferenced compute
1543 the reachability set of DELTA, conservatively assuming it is
1544 dereferenced at all valid offsets. */
1545 if (roffset == UNKNOWN_OFFSET)
1547 solution_set_expand (delta, delta);
1548 /* No further offset processing is necessary. */
1552 /* For each variable j in delta (Sol(y)), add
1553 an edge in the graph from j to x, and union Sol(j) into Sol(x). */
1554 EXECUTE_IF_SET_IN_BITMAP (delta, 0, j, bi)
1556 varinfo_t v = get_varinfo (j);
1557 HOST_WIDE_INT fieldoffset = v->offset + roffset;
1561 fieldoffset = v->offset;
1562 else if (roffset != 0)
1563 v = first_vi_for_offset (v, fieldoffset);
1564 /* If the access is outside of the variable we can ignore it. */
1572 /* Adding edges from the special vars is pointless.
1573 They don't have sets that can change. */
1574 if (get_varinfo (t)->is_special_var)
1575 flag |= bitmap_ior_into (sol, get_varinfo (t)->solution);
1576 /* Merging the solution from ESCAPED needlessly increases
1577 the set. Use ESCAPED as representative instead. */
1578 else if (v->id == escaped_id)
1579 flag |= bitmap_set_bit (sol, escaped_id);
1580 else if (add_graph_edge (graph, lhs, t))
1581 flag |= bitmap_ior_into (sol, get_varinfo (t)->solution);
1583 /* If the variable is not exactly at the requested offset
1584 we have to include the next one. */
1585 if (v->offset == (unsigned HOST_WIDE_INT)fieldoffset
1590 fieldoffset = v->offset;
1596 /* If the LHS solution changed, mark the var as changed. */
1599 get_varinfo (lhs)->solution = sol;
1600 if (!TEST_BIT (changed, lhs))
1602 SET_BIT (changed, lhs);
1608 /* Process a constraint C that represents *(x + off) = y using DELTA
1609 as the starting solution for x. */
1612 do_ds_constraint (constraint_t c, bitmap delta)
1614 unsigned int rhs = c->rhs.var;
1615 bitmap sol = get_varinfo (rhs)->solution;
1618 HOST_WIDE_INT loff = c->lhs.offset;
1620 /* Our IL does not allow this. */
1621 gcc_assert (c->rhs.offset == 0);
1623 /* If the solution of y contains ANYTHING simply use the ANYTHING
1624 solution. This avoids needlessly increasing the points-to sets. */
1625 if (bitmap_bit_p (sol, anything_id))
1626 sol = get_varinfo (find (anything_id))->solution;
1628 /* If the solution for x contains ANYTHING we have to merge the
1629 solution of y into all pointer variables which we do via
1631 if (bitmap_bit_p (delta, anything_id))
1633 unsigned t = find (storedanything_id);
1634 if (add_graph_edge (graph, t, rhs))
1636 if (bitmap_ior_into (get_varinfo (t)->solution, sol))
1638 if (!TEST_BIT (changed, t))
1640 SET_BIT (changed, t);
1648 /* If we do not know at with offset the rhs is dereferenced compute
1649 the reachability set of DELTA, conservatively assuming it is
1650 dereferenced at all valid offsets. */
1651 if (loff == UNKNOWN_OFFSET)
1653 solution_set_expand (delta, delta);
1657 /* For each member j of delta (Sol(x)), add an edge from y to j and
1658 union Sol(y) into Sol(j) */
1659 EXECUTE_IF_SET_IN_BITMAP (delta, 0, j, bi)
1661 varinfo_t v = get_varinfo (j);
1663 HOST_WIDE_INT fieldoffset = v->offset + loff;
1665 /* If v is a global variable then this is an escape point. */
1666 if (v->is_global_var)
1668 t = find (escaped_id);
1669 if (add_graph_edge (graph, t, rhs)
1670 && bitmap_ior_into (get_varinfo (t)->solution, sol)
1671 && !TEST_BIT (changed, t))
1673 SET_BIT (changed, t);
1678 if (v->is_special_var)
1682 fieldoffset = v->offset;
1684 v = first_vi_for_offset (v, fieldoffset);
1685 /* If the access is outside of the variable we can ignore it. */
1691 if (v->may_have_pointers)
1694 if (add_graph_edge (graph, t, rhs)
1695 && bitmap_ior_into (get_varinfo (t)->solution, sol)
1696 && !TEST_BIT (changed, t))
1698 SET_BIT (changed, t);
1703 /* If the variable is not exactly at the requested offset
1704 we have to include the next one. */
1705 if (v->offset == (unsigned HOST_WIDE_INT)fieldoffset
1710 fieldoffset = v->offset;
1716 /* Handle a non-simple (simple meaning requires no iteration),
1717 constraint (IE *x = &y, x = *y, *x = y, and x = y with offsets involved). */
1720 do_complex_constraint (constraint_graph_t graph, constraint_t c, bitmap delta)
1722 if (c->lhs.type == DEREF)
1724 if (c->rhs.type == ADDRESSOF)
1731 do_ds_constraint (c, delta);
1734 else if (c->rhs.type == DEREF)
1737 if (!(get_varinfo (c->lhs.var)->is_special_var))
1738 do_sd_constraint (graph, c, delta);
1746 gcc_assert (c->rhs.type == SCALAR && c->lhs.type == SCALAR);
1747 solution = get_varinfo (c->rhs.var)->solution;
1748 tmp = get_varinfo (c->lhs.var)->solution;
1750 flag = set_union_with_increment (tmp, solution, c->rhs.offset);
1754 get_varinfo (c->lhs.var)->solution = tmp;
1755 if (!TEST_BIT (changed, c->lhs.var))
1757 SET_BIT (changed, c->lhs.var);
1764 /* Initialize and return a new SCC info structure. */
1766 static struct scc_info *
1767 init_scc_info (size_t size)
1769 struct scc_info *si = XNEW (struct scc_info);
1772 si->current_index = 0;
1773 si->visited = sbitmap_alloc (size);
1774 sbitmap_zero (si->visited);
1775 si->deleted = sbitmap_alloc (size);
1776 sbitmap_zero (si->deleted);
1777 si->node_mapping = XNEWVEC (unsigned int, size);
1778 si->dfs = XCNEWVEC (unsigned int, size);
1780 for (i = 0; i < size; i++)
1781 si->node_mapping[i] = i;
1783 si->scc_stack = VEC_alloc (unsigned, heap, 1);
1787 /* Free an SCC info structure pointed to by SI */
1790 free_scc_info (struct scc_info *si)
1792 sbitmap_free (si->visited);
1793 sbitmap_free (si->deleted);
1794 free (si->node_mapping);
1796 VEC_free (unsigned, heap, si->scc_stack);
1801 /* Find indirect cycles in GRAPH that occur, using strongly connected
1802 components, and note them in the indirect cycles map.
1804 This technique comes from Ben Hardekopf and Calvin Lin,
1805 "It Pays to be Lazy: Fast and Accurate Pointer Analysis for Millions of
1806 Lines of Code", submitted to PLDI 2007. */
1809 find_indirect_cycles (constraint_graph_t graph)
1812 unsigned int size = graph->size;
1813 struct scc_info *si = init_scc_info (size);
1815 for (i = 0; i < MIN (LAST_REF_NODE, size); i ++ )
1816 if (!TEST_BIT (si->visited, i) && find (i) == i)
1817 scc_visit (graph, si, i);
1822 /* Compute a topological ordering for GRAPH, and store the result in the
1823 topo_info structure TI. */
1826 compute_topo_order (constraint_graph_t graph,
1827 struct topo_info *ti)
1830 unsigned int size = graph->size;
1832 for (i = 0; i != size; ++i)
1833 if (!TEST_BIT (ti->visited, i) && find (i) == i)
1834 topo_visit (graph, ti, i);
1837 /* Structure used to for hash value numbering of pointer equivalence
1840 typedef struct equiv_class_label
1843 unsigned int equivalence_class;
1845 } *equiv_class_label_t;
1846 typedef const struct equiv_class_label *const_equiv_class_label_t;
1848 /* A hashtable for mapping a bitmap of labels->pointer equivalence
1850 static htab_t pointer_equiv_class_table;
1852 /* A hashtable for mapping a bitmap of labels->location equivalence
1854 static htab_t location_equiv_class_table;
1856 /* Hash function for a equiv_class_label_t */
1859 equiv_class_label_hash (const void *p)
1861 const_equiv_class_label_t const ecl = (const_equiv_class_label_t) p;
1862 return ecl->hashcode;
1865 /* Equality function for two equiv_class_label_t's. */
1868 equiv_class_label_eq (const void *p1, const void *p2)
1870 const_equiv_class_label_t const eql1 = (const_equiv_class_label_t) p1;
1871 const_equiv_class_label_t const eql2 = (const_equiv_class_label_t) p2;
1872 return (eql1->hashcode == eql2->hashcode
1873 && bitmap_equal_p (eql1->labels, eql2->labels));
1876 /* Lookup a equivalence class in TABLE by the bitmap of LABELS it
1880 equiv_class_lookup (htab_t table, bitmap labels)
1883 struct equiv_class_label ecl;
1885 ecl.labels = labels;
1886 ecl.hashcode = bitmap_hash (labels);
1888 slot = htab_find_slot_with_hash (table, &ecl,
1889 ecl.hashcode, NO_INSERT);
1893 return ((equiv_class_label_t) *slot)->equivalence_class;
1897 /* Add an equivalence class named EQUIVALENCE_CLASS with labels LABELS
1901 equiv_class_add (htab_t table, unsigned int equivalence_class,
1905 equiv_class_label_t ecl = XNEW (struct equiv_class_label);
1907 ecl->labels = labels;
1908 ecl->equivalence_class = equivalence_class;
1909 ecl->hashcode = bitmap_hash (labels);
1911 slot = htab_find_slot_with_hash (table, ecl,
1912 ecl->hashcode, INSERT);
1913 gcc_assert (!*slot);
1914 *slot = (void *) ecl;
1917 /* Perform offline variable substitution.
1919 This is a worst case quadratic time way of identifying variables
1920 that must have equivalent points-to sets, including those caused by
1921 static cycles, and single entry subgraphs, in the constraint graph.
1923 The technique is described in "Exploiting Pointer and Location
1924 Equivalence to Optimize Pointer Analysis. In the 14th International
1925 Static Analysis Symposium (SAS), August 2007." It is known as the
1926 "HU" algorithm, and is equivalent to value numbering the collapsed
1927 constraint graph including evaluating unions.
1929 The general method of finding equivalence classes is as follows:
1930 Add fake nodes (REF nodes) and edges for *a = b and a = *b constraints.
1931 Initialize all non-REF nodes to be direct nodes.
1932 For each constraint a = a U {b}, we set pts(a) = pts(a) u {fresh
1934 For each constraint containing the dereference, we also do the same
1937 We then compute SCC's in the graph and unify nodes in the same SCC,
1940 For each non-collapsed node x:
1941 Visit all unvisited explicit incoming edges.
1942 Ignoring all non-pointers, set pts(x) = Union of pts(a) for y
1944 Lookup the equivalence class for pts(x).
1945 If we found one, equivalence_class(x) = found class.
1946 Otherwise, equivalence_class(x) = new class, and new_class is
1947 added to the lookup table.
1949 All direct nodes with the same equivalence class can be replaced
1950 with a single representative node.
1951 All unlabeled nodes (label == 0) are not pointers and all edges
1952 involving them can be eliminated.
1953 We perform these optimizations during rewrite_constraints
1955 In addition to pointer equivalence class finding, we also perform
1956 location equivalence class finding. This is the set of variables
1957 that always appear together in points-to sets. We use this to
1958 compress the size of the points-to sets. */
1960 /* Current maximum pointer equivalence class id. */
1961 static int pointer_equiv_class;
1963 /* Current maximum location equivalence class id. */
1964 static int location_equiv_class;
1966 /* Recursive routine to find strongly connected components in GRAPH,
1967 and label it's nodes with DFS numbers. */
1970 condense_visit (constraint_graph_t graph, struct scc_info *si, unsigned int n)
1974 unsigned int my_dfs;
1976 gcc_assert (si->node_mapping[n] == n);
1977 SET_BIT (si->visited, n);
1978 si->dfs[n] = si->current_index ++;
1979 my_dfs = si->dfs[n];
1981 /* Visit all the successors. */
1982 EXECUTE_IF_IN_NONNULL_BITMAP (graph->preds[n], 0, i, bi)
1984 unsigned int w = si->node_mapping[i];
1986 if (TEST_BIT (si->deleted, w))
1989 if (!TEST_BIT (si->visited, w))
1990 condense_visit (graph, si, w);
1992 unsigned int t = si->node_mapping[w];
1993 unsigned int nnode = si->node_mapping[n];
1994 gcc_assert (nnode == n);
1996 if (si->dfs[t] < si->dfs[nnode])
1997 si->dfs[n] = si->dfs[t];
2001 /* Visit all the implicit predecessors. */
2002 EXECUTE_IF_IN_NONNULL_BITMAP (graph->implicit_preds[n], 0, i, bi)
2004 unsigned int w = si->node_mapping[i];
2006 if (TEST_BIT (si->deleted, w))
2009 if (!TEST_BIT (si->visited, w))
2010 condense_visit (graph, si, w);
2012 unsigned int t = si->node_mapping[w];
2013 unsigned int nnode = si->node_mapping[n];
2014 gcc_assert (nnode == n);
2016 if (si->dfs[t] < si->dfs[nnode])
2017 si->dfs[n] = si->dfs[t];
2021 /* See if any components have been identified. */
2022 if (si->dfs[n] == my_dfs)
2024 while (VEC_length (unsigned, si->scc_stack) != 0
2025 && si->dfs[VEC_last (unsigned, si->scc_stack)] >= my_dfs)
2027 unsigned int w = VEC_pop (unsigned, si->scc_stack);
2028 si->node_mapping[w] = n;
2030 if (!TEST_BIT (graph->direct_nodes, w))
2031 RESET_BIT (graph->direct_nodes, n);
2033 /* Unify our nodes. */
2034 if (graph->preds[w])
2036 if (!graph->preds[n])
2037 graph->preds[n] = BITMAP_ALLOC (&predbitmap_obstack);
2038 bitmap_ior_into (graph->preds[n], graph->preds[w]);
2040 if (graph->implicit_preds[w])
2042 if (!graph->implicit_preds[n])
2043 graph->implicit_preds[n] = BITMAP_ALLOC (&predbitmap_obstack);
2044 bitmap_ior_into (graph->implicit_preds[n],
2045 graph->implicit_preds[w]);
2047 if (graph->points_to[w])
2049 if (!graph->points_to[n])
2050 graph->points_to[n] = BITMAP_ALLOC (&predbitmap_obstack);
2051 bitmap_ior_into (graph->points_to[n],
2052 graph->points_to[w]);
2055 SET_BIT (si->deleted, n);
2058 VEC_safe_push (unsigned, heap, si->scc_stack, n);
2061 /* Label pointer equivalences. */
2064 label_visit (constraint_graph_t graph, struct scc_info *si, unsigned int n)
2068 SET_BIT (si->visited, n);
2070 if (!graph->points_to[n])
2071 graph->points_to[n] = BITMAP_ALLOC (&predbitmap_obstack);
2073 /* Label and union our incoming edges's points to sets. */
2074 EXECUTE_IF_IN_NONNULL_BITMAP (graph->preds[n], 0, i, bi)
2076 unsigned int w = si->node_mapping[i];
2077 if (!TEST_BIT (si->visited, w))
2078 label_visit (graph, si, w);
2080 /* Skip unused edges */
2081 if (w == n || graph->pointer_label[w] == 0)
2084 if (graph->points_to[w])
2085 bitmap_ior_into(graph->points_to[n], graph->points_to[w]);
2087 /* Indirect nodes get fresh variables. */
2088 if (!TEST_BIT (graph->direct_nodes, n))
2089 bitmap_set_bit (graph->points_to[n], FIRST_REF_NODE + n);
2091 if (!bitmap_empty_p (graph->points_to[n]))
2093 unsigned int label = equiv_class_lookup (pointer_equiv_class_table,
2094 graph->points_to[n]);
2097 label = pointer_equiv_class++;
2098 equiv_class_add (pointer_equiv_class_table,
2099 label, graph->points_to[n]);
2101 graph->pointer_label[n] = label;
2105 /* Perform offline variable substitution, discovering equivalence
2106 classes, and eliminating non-pointer variables. */
2108 static struct scc_info *
2109 perform_var_substitution (constraint_graph_t graph)
2112 unsigned int size = graph->size;
2113 struct scc_info *si = init_scc_info (size);
2115 bitmap_obstack_initialize (&iteration_obstack);
2116 pointer_equiv_class_table = htab_create (511, equiv_class_label_hash,
2117 equiv_class_label_eq, free);
2118 location_equiv_class_table = htab_create (511, equiv_class_label_hash,
2119 equiv_class_label_eq, free);
2120 pointer_equiv_class = 1;
2121 location_equiv_class = 1;
2123 /* Condense the nodes, which means to find SCC's, count incoming
2124 predecessors, and unite nodes in SCC's. */
2125 for (i = 0; i < FIRST_REF_NODE; i++)
2126 if (!TEST_BIT (si->visited, si->node_mapping[i]))
2127 condense_visit (graph, si, si->node_mapping[i]);
2129 sbitmap_zero (si->visited);
2130 /* Actually the label the nodes for pointer equivalences */
2131 for (i = 0; i < FIRST_REF_NODE; i++)
2132 if (!TEST_BIT (si->visited, si->node_mapping[i]))
2133 label_visit (graph, si, si->node_mapping[i]);
2135 /* Calculate location equivalence labels. */
2136 for (i = 0; i < FIRST_REF_NODE; i++)
2143 if (!graph->pointed_by[i])
2145 pointed_by = BITMAP_ALLOC (&iteration_obstack);
2147 /* Translate the pointed-by mapping for pointer equivalence
2149 EXECUTE_IF_SET_IN_BITMAP (graph->pointed_by[i], 0, j, bi)
2151 bitmap_set_bit (pointed_by,
2152 graph->pointer_label[si->node_mapping[j]]);
2154 /* The original pointed_by is now dead. */
2155 BITMAP_FREE (graph->pointed_by[i]);
2157 /* Look up the location equivalence label if one exists, or make
2159 label = equiv_class_lookup (location_equiv_class_table,
2163 label = location_equiv_class++;
2164 equiv_class_add (location_equiv_class_table,
2169 if (dump_file && (dump_flags & TDF_DETAILS))
2170 fprintf (dump_file, "Found location equivalence for node %s\n",
2171 get_varinfo (i)->name);
2172 BITMAP_FREE (pointed_by);
2174 graph->loc_label[i] = label;
2178 if (dump_file && (dump_flags & TDF_DETAILS))
2179 for (i = 0; i < FIRST_REF_NODE; i++)
2181 bool direct_node = TEST_BIT (graph->direct_nodes, i);
2183 "Equivalence classes for %s node id %d:%s are pointer: %d"
2185 direct_node ? "Direct node" : "Indirect node", i,
2186 get_varinfo (i)->name,
2187 graph->pointer_label[si->node_mapping[i]],
2188 graph->loc_label[si->node_mapping[i]]);
2191 /* Quickly eliminate our non-pointer variables. */
2193 for (i = 0; i < FIRST_REF_NODE; i++)
2195 unsigned int node = si->node_mapping[i];
2197 if (graph->pointer_label[node] == 0)
2199 if (dump_file && (dump_flags & TDF_DETAILS))
2201 "%s is a non-pointer variable, eliminating edges.\n",
2202 get_varinfo (node)->name);
2203 stats.nonpointer_vars++;
2204 clear_edges_for_node (graph, node);
2211 /* Free information that was only necessary for variable
2215 free_var_substitution_info (struct scc_info *si)
2218 free (graph->pointer_label);
2219 free (graph->loc_label);
2220 free (graph->pointed_by);
2221 free (graph->points_to);
2222 free (graph->eq_rep);
2223 sbitmap_free (graph->direct_nodes);
2224 htab_delete (pointer_equiv_class_table);
2225 htab_delete (location_equiv_class_table);
2226 bitmap_obstack_release (&iteration_obstack);
2229 /* Return an existing node that is equivalent to NODE, which has
2230 equivalence class LABEL, if one exists. Return NODE otherwise. */
2233 find_equivalent_node (constraint_graph_t graph,
2234 unsigned int node, unsigned int label)
2236 /* If the address version of this variable is unused, we can
2237 substitute it for anything else with the same label.
2238 Otherwise, we know the pointers are equivalent, but not the
2239 locations, and we can unite them later. */
2241 if (!bitmap_bit_p (graph->address_taken, node))
2243 gcc_assert (label < graph->size);
2245 if (graph->eq_rep[label] != -1)
2247 /* Unify the two variables since we know they are equivalent. */
2248 if (unite (graph->eq_rep[label], node))
2249 unify_nodes (graph, graph->eq_rep[label], node, false);
2250 return graph->eq_rep[label];
2254 graph->eq_rep[label] = node;
2255 graph->pe_rep[label] = node;
2260 gcc_assert (label < graph->size);
2261 graph->pe[node] = label;
2262 if (graph->pe_rep[label] == -1)
2263 graph->pe_rep[label] = node;
2269 /* Unite pointer equivalent but not location equivalent nodes in
2270 GRAPH. This may only be performed once variable substitution is
2274 unite_pointer_equivalences (constraint_graph_t graph)
2278 /* Go through the pointer equivalences and unite them to their
2279 representative, if they aren't already. */
2280 for (i = 0; i < FIRST_REF_NODE; i++)
2282 unsigned int label = graph->pe[i];
2285 int label_rep = graph->pe_rep[label];
2287 if (label_rep == -1)
2290 label_rep = find (label_rep);
2291 if (label_rep >= 0 && unite (label_rep, find (i)))
2292 unify_nodes (graph, label_rep, i, false);
2297 /* Move complex constraints to the GRAPH nodes they belong to. */
2300 move_complex_constraints (constraint_graph_t graph)
2305 for (i = 0; VEC_iterate (constraint_t, constraints, i, c); i++)
2309 struct constraint_expr lhs = c->lhs;
2310 struct constraint_expr rhs = c->rhs;
2312 if (lhs.type == DEREF)
2314 insert_into_complex (graph, lhs.var, c);
2316 else if (rhs.type == DEREF)
2318 if (!(get_varinfo (lhs.var)->is_special_var))
2319 insert_into_complex (graph, rhs.var, c);
2321 else if (rhs.type != ADDRESSOF && lhs.var > anything_id
2322 && (lhs.offset != 0 || rhs.offset != 0))
2324 insert_into_complex (graph, rhs.var, c);
2331 /* Optimize and rewrite complex constraints while performing
2332 collapsing of equivalent nodes. SI is the SCC_INFO that is the
2333 result of perform_variable_substitution. */
2336 rewrite_constraints (constraint_graph_t graph,
2337 struct scc_info *si)
2343 for (j = 0; j < graph->size; j++)
2344 gcc_assert (find (j) == j);
2346 for (i = 0; VEC_iterate (constraint_t, constraints, i, c); i++)
2348 struct constraint_expr lhs = c->lhs;
2349 struct constraint_expr rhs = c->rhs;
2350 unsigned int lhsvar = find (lhs.var);
2351 unsigned int rhsvar = find (rhs.var);
2352 unsigned int lhsnode, rhsnode;
2353 unsigned int lhslabel, rhslabel;
2355 lhsnode = si->node_mapping[lhsvar];
2356 rhsnode = si->node_mapping[rhsvar];
2357 lhslabel = graph->pointer_label[lhsnode];
2358 rhslabel = graph->pointer_label[rhsnode];
2360 /* See if it is really a non-pointer variable, and if so, ignore
2364 if (dump_file && (dump_flags & TDF_DETAILS))
2367 fprintf (dump_file, "%s is a non-pointer variable,"
2368 "ignoring constraint:",
2369 get_varinfo (lhs.var)->name);
2370 dump_constraint (dump_file, c);
2372 VEC_replace (constraint_t, constraints, i, NULL);
2378 if (dump_file && (dump_flags & TDF_DETAILS))
2381 fprintf (dump_file, "%s is a non-pointer variable,"
2382 "ignoring constraint:",
2383 get_varinfo (rhs.var)->name);
2384 dump_constraint (dump_file, c);
2386 VEC_replace (constraint_t, constraints, i, NULL);
2390 lhsvar = find_equivalent_node (graph, lhsvar, lhslabel);
2391 rhsvar = find_equivalent_node (graph, rhsvar, rhslabel);
2392 c->lhs.var = lhsvar;
2393 c->rhs.var = rhsvar;
2398 /* Eliminate indirect cycles involving NODE. Return true if NODE was
2399 part of an SCC, false otherwise. */
2402 eliminate_indirect_cycles (unsigned int node)
2404 if (graph->indirect_cycles[node] != -1
2405 && !bitmap_empty_p (get_varinfo (node)->solution))
2408 VEC(unsigned,heap) *queue = NULL;
2410 unsigned int to = find (graph->indirect_cycles[node]);
2413 /* We can't touch the solution set and call unify_nodes
2414 at the same time, because unify_nodes is going to do
2415 bitmap unions into it. */
2417 EXECUTE_IF_SET_IN_BITMAP (get_varinfo (node)->solution, 0, i, bi)
2419 if (find (i) == i && i != to)
2422 VEC_safe_push (unsigned, heap, queue, i);
2427 VEC_iterate (unsigned, queue, queuepos, i);
2430 unify_nodes (graph, to, i, true);
2432 VEC_free (unsigned, heap, queue);
2438 /* Solve the constraint graph GRAPH using our worklist solver.
2439 This is based on the PW* family of solvers from the "Efficient Field
2440 Sensitive Pointer Analysis for C" paper.
2441 It works by iterating over all the graph nodes, processing the complex
2442 constraints and propagating the copy constraints, until everything stops
2443 changed. This corresponds to steps 6-8 in the solving list given above. */
2446 solve_graph (constraint_graph_t graph)
2448 unsigned int size = graph->size;
2453 changed = sbitmap_alloc (size);
2454 sbitmap_zero (changed);
2456 /* Mark all initial non-collapsed nodes as changed. */
2457 for (i = 0; i < size; i++)
2459 varinfo_t ivi = get_varinfo (i);
2460 if (find (i) == i && !bitmap_empty_p (ivi->solution)
2461 && ((graph->succs[i] && !bitmap_empty_p (graph->succs[i]))
2462 || VEC_length (constraint_t, graph->complex[i]) > 0))
2464 SET_BIT (changed, i);
2469 /* Allocate a bitmap to be used to store the changed bits. */
2470 pts = BITMAP_ALLOC (&pta_obstack);
2472 while (changed_count > 0)
2475 struct topo_info *ti = init_topo_info ();
2478 bitmap_obstack_initialize (&iteration_obstack);
2480 compute_topo_order (graph, ti);
2482 while (VEC_length (unsigned, ti->topo_order) != 0)
2485 i = VEC_pop (unsigned, ti->topo_order);
2487 /* If this variable is not a representative, skip it. */
2491 /* In certain indirect cycle cases, we may merge this
2492 variable to another. */
2493 if (eliminate_indirect_cycles (i) && find (i) != i)
2496 /* If the node has changed, we need to process the
2497 complex constraints and outgoing edges again. */
2498 if (TEST_BIT (changed, i))
2503 VEC(constraint_t,heap) *complex = graph->complex[i];
2504 bool solution_empty;
2506 RESET_BIT (changed, i);
2509 /* Compute the changed set of solution bits. */
2510 bitmap_and_compl (pts, get_varinfo (i)->solution,
2511 get_varinfo (i)->oldsolution);
2513 if (bitmap_empty_p (pts))
2516 bitmap_ior_into (get_varinfo (i)->oldsolution, pts);
2518 solution = get_varinfo (i)->solution;
2519 solution_empty = bitmap_empty_p (solution);
2521 /* Process the complex constraints */
2522 for (j = 0; VEC_iterate (constraint_t, complex, j, c); j++)
2524 /* XXX: This is going to unsort the constraints in
2525 some cases, which will occasionally add duplicate
2526 constraints during unification. This does not
2527 affect correctness. */
2528 c->lhs.var = find (c->lhs.var);
2529 c->rhs.var = find (c->rhs.var);
2531 /* The only complex constraint that can change our
2532 solution to non-empty, given an empty solution,
2533 is a constraint where the lhs side is receiving
2534 some set from elsewhere. */
2535 if (!solution_empty || c->lhs.type != DEREF)
2536 do_complex_constraint (graph, c, pts);
2539 solution_empty = bitmap_empty_p (solution);
2541 if (!solution_empty)
2544 unsigned eff_escaped_id = find (escaped_id);
2546 /* Propagate solution to all successors. */
2547 EXECUTE_IF_IN_NONNULL_BITMAP (graph->succs[i],
2553 unsigned int to = find (j);
2554 tmp = get_varinfo (to)->solution;
2557 /* Don't try to propagate to ourselves. */
2561 /* If we propagate from ESCAPED use ESCAPED as
2563 if (i == eff_escaped_id)
2564 flag = bitmap_set_bit (tmp, escaped_id);
2566 flag = set_union_with_increment (tmp, pts, 0);
2570 get_varinfo (to)->solution = tmp;
2571 if (!TEST_BIT (changed, to))
2573 SET_BIT (changed, to);
2581 free_topo_info (ti);
2582 bitmap_obstack_release (&iteration_obstack);
2586 sbitmap_free (changed);
2587 bitmap_obstack_release (&oldpta_obstack);
2590 /* Map from trees to variable infos. */
2591 static struct pointer_map_t *vi_for_tree;
2594 /* Insert ID as the variable id for tree T in the vi_for_tree map. */
2597 insert_vi_for_tree (tree t, varinfo_t vi)
2599 void **slot = pointer_map_insert (vi_for_tree, t);
2601 gcc_assert (*slot == NULL);
2605 /* Find the variable info for tree T in VI_FOR_TREE. If T does not
2606 exist in the map, return NULL, otherwise, return the varinfo we found. */
2609 lookup_vi_for_tree (tree t)
2611 void **slot = pointer_map_contains (vi_for_tree, t);
2615 return (varinfo_t) *slot;
2618 /* Return a printable name for DECL */
2621 alias_get_name (tree decl)
2623 const char *res = get_name (decl);
2625 int num_printed = 0;
2634 if (TREE_CODE (decl) == SSA_NAME)
2636 num_printed = asprintf (&temp, "%s_%u",
2637 alias_get_name (SSA_NAME_VAR (decl)),
2638 SSA_NAME_VERSION (decl));
2640 else if (DECL_P (decl))
2642 num_printed = asprintf (&temp, "D.%u", DECL_UID (decl));
2644 if (num_printed > 0)
2646 res = ggc_strdup (temp);
2652 /* Find the variable id for tree T in the map.
2653 If T doesn't exist in the map, create an entry for it and return it. */
2656 get_vi_for_tree (tree t)
2658 void **slot = pointer_map_contains (vi_for_tree, t);
2660 return get_varinfo (create_variable_info_for (t, alias_get_name (t)));
2662 return (varinfo_t) *slot;
2665 /* Get a scalar constraint expression for a new temporary variable. */
2667 static struct constraint_expr
2668 new_scalar_tmp_constraint_exp (const char *name)
2670 struct constraint_expr tmp;
2673 vi = new_var_info (NULL_TREE, name);
2677 vi->is_full_var = 1;
2686 /* Get a constraint expression vector from an SSA_VAR_P node.
2687 If address_p is true, the result will be taken its address of. */
2690 get_constraint_for_ssa_var (tree t, VEC(ce_s, heap) **results, bool address_p)
2692 struct constraint_expr cexpr;
2695 /* We allow FUNCTION_DECLs here even though it doesn't make much sense. */
2696 gcc_assert (SSA_VAR_P (t) || DECL_P (t));
2698 /* For parameters, get at the points-to set for the actual parm
2700 if (TREE_CODE (t) == SSA_NAME
2701 && TREE_CODE (SSA_NAME_VAR (t)) == PARM_DECL
2702 && SSA_NAME_IS_DEFAULT_DEF (t))
2704 get_constraint_for_ssa_var (SSA_NAME_VAR (t), results, address_p);
2708 vi = get_vi_for_tree (t);
2710 cexpr.type = SCALAR;
2712 /* If we determine the result is "anything", and we know this is readonly,
2713 say it points to readonly memory instead. */
2714 if (cexpr.var == anything_id && TREE_READONLY (t))
2717 cexpr.type = ADDRESSOF;
2718 cexpr.var = readonly_id;
2721 /* If we are not taking the address of the constraint expr, add all
2722 sub-fiels of the variable as well. */
2725 for (; vi; vi = vi->next)
2728 VEC_safe_push (ce_s, heap, *results, &cexpr);
2733 VEC_safe_push (ce_s, heap, *results, &cexpr);
2736 /* Process constraint T, performing various simplifications and then
2737 adding it to our list of overall constraints. */
2740 process_constraint (constraint_t t)
2742 struct constraint_expr rhs = t->rhs;
2743 struct constraint_expr lhs = t->lhs;
2745 gcc_assert (rhs.var < VEC_length (varinfo_t, varmap));
2746 gcc_assert (lhs.var < VEC_length (varinfo_t, varmap));
2748 /* If we didn't get any useful constraint from the lhs we get
2749 &ANYTHING as fallback from get_constraint_for. Deal with
2750 it here by turning it into *ANYTHING. */
2751 if (lhs.type == ADDRESSOF
2752 && lhs.var == anything_id)
2755 /* ADDRESSOF on the lhs is invalid. */
2756 gcc_assert (lhs.type != ADDRESSOF);
2758 /* This can happen in our IR with things like n->a = *p */
2759 if (rhs.type == DEREF && lhs.type == DEREF && rhs.var != anything_id)
2761 /* Split into tmp = *rhs, *lhs = tmp */
2762 struct constraint_expr tmplhs;
2763 tmplhs = new_scalar_tmp_constraint_exp ("doubledereftmp");
2764 process_constraint (new_constraint (tmplhs, rhs));
2765 process_constraint (new_constraint (lhs, tmplhs));
2767 else if (rhs.type == ADDRESSOF && lhs.type == DEREF)
2769 /* Split into tmp = &rhs, *lhs = tmp */
2770 struct constraint_expr tmplhs;
2771 tmplhs = new_scalar_tmp_constraint_exp ("derefaddrtmp");
2772 process_constraint (new_constraint (tmplhs, rhs));
2773 process_constraint (new_constraint (lhs, tmplhs));
2777 gcc_assert (rhs.type != ADDRESSOF || rhs.offset == 0);
2778 VEC_safe_push (constraint_t, heap, constraints, t);
2782 /* Return true if T is a type that could contain pointers. */
2785 type_could_have_pointers (tree type)
2787 if (POINTER_TYPE_P (type))
2790 if (TREE_CODE (type) == ARRAY_TYPE)
2791 return type_could_have_pointers (TREE_TYPE (type));
2793 return AGGREGATE_TYPE_P (type);
2796 /* Return true if T is a variable of a type that could contain
2800 could_have_pointers (tree t)
2802 return type_could_have_pointers (TREE_TYPE (t));
2805 /* Return the position, in bits, of FIELD_DECL from the beginning of its
2808 static HOST_WIDE_INT
2809 bitpos_of_field (const tree fdecl)
2812 if (!host_integerp (DECL_FIELD_OFFSET (fdecl), 0)
2813 || !host_integerp (DECL_FIELD_BIT_OFFSET (fdecl), 0))
2816 return (TREE_INT_CST_LOW (DECL_FIELD_OFFSET (fdecl)) * 8
2817 + TREE_INT_CST_LOW (DECL_FIELD_BIT_OFFSET (fdecl)));
2821 /* Get constraint expressions for offsetting PTR by OFFSET. Stores the
2822 resulting constraint expressions in *RESULTS. */
2825 get_constraint_for_ptr_offset (tree ptr, tree offset,
2826 VEC (ce_s, heap) **results)
2828 struct constraint_expr c;
2830 HOST_WIDE_INT rhsunitoffset, rhsoffset;
2832 /* If we do not do field-sensitive PTA adding offsets to pointers
2833 does not change the points-to solution. */
2834 if (!use_field_sensitive)
2836 get_constraint_for (ptr, results);
2840 /* If the offset is not a non-negative integer constant that fits
2841 in a HOST_WIDE_INT, we have to fall back to a conservative
2842 solution which includes all sub-fields of all pointed-to
2843 variables of ptr. */
2844 if (offset == NULL_TREE
2845 || !host_integerp (offset, 0))
2846 rhsoffset = UNKNOWN_OFFSET;
2849 /* Make sure the bit-offset also fits. */
2850 rhsunitoffset = TREE_INT_CST_LOW (offset);
2851 rhsoffset = rhsunitoffset * BITS_PER_UNIT;
2852 if (rhsunitoffset != rhsoffset / BITS_PER_UNIT)
2853 rhsoffset = UNKNOWN_OFFSET;
2856 get_constraint_for (ptr, results);
2860 /* As we are eventually appending to the solution do not use
2861 VEC_iterate here. */
2862 n = VEC_length (ce_s, *results);
2863 for (j = 0; j < n; j++)
2866 c = *VEC_index (ce_s, *results, j);
2867 curr = get_varinfo (c.var);
2869 if (c.type == ADDRESSOF
2870 /* If this varinfo represents a full variable just use it. */
2871 && curr->is_full_var)
2873 else if (c.type == ADDRESSOF
2874 /* If we do not know the offset add all subfields. */
2875 && rhsoffset == UNKNOWN_OFFSET)
2877 varinfo_t temp = lookup_vi_for_tree (curr->decl);
2880 struct constraint_expr c2;
2882 c2.type = ADDRESSOF;
2884 if (c2.var != c.var)
2885 VEC_safe_push (ce_s, heap, *results, &c2);
2890 else if (c.type == ADDRESSOF)
2893 unsigned HOST_WIDE_INT offset = curr->offset + rhsoffset;
2895 /* Search the sub-field which overlaps with the
2896 pointed-to offset. If the result is outside of the variable
2897 we have to provide a conservative result, as the variable is
2898 still reachable from the resulting pointer (even though it
2899 technically cannot point to anything). The last and first
2900 sub-fields are such conservative results.
2901 ??? If we always had a sub-field for &object + 1 then
2902 we could represent this in a more precise way. */
2904 && curr->offset < offset)
2906 temp = first_or_preceding_vi_for_offset (curr, offset);
2908 /* If the found variable is not exactly at the pointed to
2909 result, we have to include the next variable in the
2910 solution as well. Otherwise two increments by offset / 2
2911 do not result in the same or a conservative superset
2913 if (temp->offset != offset
2914 && temp->next != NULL)
2916 struct constraint_expr c2;
2917 c2.var = temp->next->id;
2918 c2.type = ADDRESSOF;
2920 VEC_safe_push (ce_s, heap, *results, &c2);
2926 c.offset = rhsoffset;
2928 VEC_replace (ce_s, *results, j, &c);
2933 /* Given a COMPONENT_REF T, return the constraint_expr vector for it.
2934 If address_p is true the result will be taken its address of. */
2937 get_constraint_for_component_ref (tree t, VEC(ce_s, heap) **results,
2941 HOST_WIDE_INT bitsize = -1;
2942 HOST_WIDE_INT bitmaxsize = -1;
2943 HOST_WIDE_INT bitpos;
2945 struct constraint_expr *result;
2947 /* Some people like to do cute things like take the address of
2950 while (!SSA_VAR_P (forzero) && !CONSTANT_CLASS_P (forzero))
2951 forzero = TREE_OPERAND (forzero, 0);
2953 if (CONSTANT_CLASS_P (forzero) && integer_zerop (forzero))
2955 struct constraint_expr temp;
2958 temp.var = integer_id;
2960 VEC_safe_push (ce_s, heap, *results, &temp);
2964 t = get_ref_base_and_extent (t, &bitpos, &bitsize, &bitmaxsize);
2966 /* Pretend to take the address of the base, we'll take care of
2967 adding the required subset of sub-fields below. */
2968 get_constraint_for_1 (t, results, true);
2969 gcc_assert (VEC_length (ce_s, *results) == 1);
2970 result = VEC_last (ce_s, *results);
2972 if (result->type == SCALAR
2973 && get_varinfo (result->var)->is_full_var)
2974 /* For single-field vars do not bother about the offset. */
2976 else if (result->type == SCALAR)
2978 /* In languages like C, you can access one past the end of an
2979 array. You aren't allowed to dereference it, so we can
2980 ignore this constraint. When we handle pointer subtraction,
2981 we may have to do something cute here. */
2983 if ((unsigned HOST_WIDE_INT)bitpos < get_varinfo (result->var)->fullsize
2986 /* It's also not true that the constraint will actually start at the
2987 right offset, it may start in some padding. We only care about
2988 setting the constraint to the first actual field it touches, so
2990 struct constraint_expr cexpr = *result;
2992 VEC_pop (ce_s, *results);
2994 for (curr = get_varinfo (cexpr.var); curr; curr = curr->next)
2996 if (ranges_overlap_p (curr->offset, curr->size,
2997 bitpos, bitmaxsize))
2999 cexpr.var = curr->id;
3000 VEC_safe_push (ce_s, heap, *results, &cexpr);
3005 /* If we are going to take the address of this field then
3006 to be able to compute reachability correctly add at least
3007 the last field of the variable. */
3009 && VEC_length (ce_s, *results) == 0)
3011 curr = get_varinfo (cexpr.var);
3012 while (curr->next != NULL)
3014 cexpr.var = curr->id;
3015 VEC_safe_push (ce_s, heap, *results, &cexpr);
3018 /* Assert that we found *some* field there. The user couldn't be
3019 accessing *only* padding. */
3020 /* Still the user could access one past the end of an array
3021 embedded in a struct resulting in accessing *only* padding. */
3022 gcc_assert (VEC_length (ce_s, *results) >= 1
3023 || ref_contains_array_ref (orig_t));
3025 else if (bitmaxsize == 0)
3027 if (dump_file && (dump_flags & TDF_DETAILS))
3028 fprintf (dump_file, "Access to zero-sized part of variable,"
3032 if (dump_file && (dump_flags & TDF_DETAILS))
3033 fprintf (dump_file, "Access to past the end of variable, ignoring\n");
3035 else if (result->type == DEREF)
3037 /* If we do not know exactly where the access goes say so. Note
3038 that only for non-structure accesses we know that we access
3039 at most one subfiled of any variable. */
3041 || bitsize != bitmaxsize
3042 || AGGREGATE_TYPE_P (TREE_TYPE (orig_t)))
3043 result->offset = UNKNOWN_OFFSET;
3045 result->offset = bitpos;
3047 else if (result->type == ADDRESSOF)
3049 /* We can end up here for component references on a
3050 VIEW_CONVERT_EXPR <>(&foobar). */
3051 result->type = SCALAR;
3052 result->var = anything_id;
3060 /* Dereference the constraint expression CONS, and return the result.
3061 DEREF (ADDRESSOF) = SCALAR
3062 DEREF (SCALAR) = DEREF
3063 DEREF (DEREF) = (temp = DEREF1; result = DEREF(temp))
3064 This is needed so that we can handle dereferencing DEREF constraints. */
3067 do_deref (VEC (ce_s, heap) **constraints)
3069 struct constraint_expr *c;
3072 for (i = 0; VEC_iterate (ce_s, *constraints, i, c); i++)
3074 if (c->type == SCALAR)
3076 else if (c->type == ADDRESSOF)
3078 else if (c->type == DEREF)
3080 struct constraint_expr tmplhs;
3081 tmplhs = new_scalar_tmp_constraint_exp ("dereftmp");
3082 process_constraint (new_constraint (tmplhs, *c));
3083 c->var = tmplhs.var;
3090 static void get_constraint_for_1 (tree, VEC (ce_s, heap) **, bool);
3092 /* Given a tree T, return the constraint expression for taking the
3096 get_constraint_for_address_of (tree t, VEC (ce_s, heap) **results)
3098 struct constraint_expr *c;
3101 get_constraint_for_1 (t, results, true);
3103 for (i = 0; VEC_iterate (ce_s, *results, i, c); i++)
3105 if (c->type == DEREF)
3108 c->type = ADDRESSOF;
3112 /* Given a tree T, return the constraint expression for it. */
3115 get_constraint_for_1 (tree t, VEC (ce_s, heap) **results, bool address_p)
3117 struct constraint_expr temp;
3119 /* x = integer is all glommed to a single variable, which doesn't
3120 point to anything by itself. That is, of course, unless it is an
3121 integer constant being treated as a pointer, in which case, we
3122 will return that this is really the addressof anything. This
3123 happens below, since it will fall into the default case. The only
3124 case we know something about an integer treated like a pointer is
3125 when it is the NULL pointer, and then we just say it points to
3128 Do not do that if -fno-delete-null-pointer-checks though, because
3129 in that case *NULL does not fail, so it _should_ alias *anything.
3130 It is not worth adding a new option or renaming the existing one,
3131 since this case is relatively obscure. */
3132 if (flag_delete_null_pointer_checks
3133 && ((TREE_CODE (t) == INTEGER_CST
3134 && integer_zerop (t))
3135 /* The only valid CONSTRUCTORs in gimple with pointer typed
3136 elements are zero-initializer. */
3137 || TREE_CODE (t) == CONSTRUCTOR))
3139 temp.var = nothing_id;
3140 temp.type = ADDRESSOF;
3142 VEC_safe_push (ce_s, heap, *results, &temp);
3146 /* String constants are read-only. */
3147 if (TREE_CODE (t) == STRING_CST)
3149 temp.var = readonly_id;
3152 VEC_safe_push (ce_s, heap, *results, &temp);
3156 switch (TREE_CODE_CLASS (TREE_CODE (t)))
3158 case tcc_expression:
3160 switch (TREE_CODE (t))
3163 get_constraint_for_address_of (TREE_OPERAND (t, 0), results);
3171 switch (TREE_CODE (t))
3175 get_constraint_for_1 (TREE_OPERAND (t, 0), results, address_p);
3180 case ARRAY_RANGE_REF:
3182 get_constraint_for_component_ref (t, results, address_p);
3184 case VIEW_CONVERT_EXPR:
3185 get_constraint_for_1 (TREE_OPERAND (t, 0), results, address_p);
3187 /* We are missing handling for TARGET_MEM_REF here. */
3192 case tcc_exceptional:
3194 switch (TREE_CODE (t))
3198 get_constraint_for_ssa_var (t, results, address_p);
3205 case tcc_declaration:
3207 get_constraint_for_ssa_var (t, results, address_p);
3213 /* The default fallback is a constraint from anything. */
3214 temp.type = ADDRESSOF;
3215 temp.var = anything_id;
3217 VEC_safe_push (ce_s, heap, *results, &temp);
3220 /* Given a gimple tree T, return the constraint expression vector for it. */
3223 get_constraint_for (tree t, VEC (ce_s, heap) **results)
3225 gcc_assert (VEC_length (ce_s, *results) == 0);
3227 get_constraint_for_1 (t, results, false);
3231 /* Efficiently generates constraints from all entries in *RHSC to all
3232 entries in *LHSC. */
3235 process_all_all_constraints (VEC (ce_s, heap) *lhsc, VEC (ce_s, heap) *rhsc)
3237 struct constraint_expr *lhsp, *rhsp;
3240 if (VEC_length (ce_s, lhsc) <= 1
3241 || VEC_length (ce_s, rhsc) <= 1)
3243 for (i = 0; VEC_iterate (ce_s, lhsc, i, lhsp); ++i)
3244 for (j = 0; VEC_iterate (ce_s, rhsc, j, rhsp); ++j)
3245 process_constraint (new_constraint (*lhsp, *rhsp));
3249 struct constraint_expr tmp;
3250 tmp = new_scalar_tmp_constraint_exp ("allalltmp");
3251 for (i = 0; VEC_iterate (ce_s, rhsc, i, rhsp); ++i)
3252 process_constraint (new_constraint (tmp, *rhsp));
3253 for (i = 0; VEC_iterate (ce_s, lhsc, i, lhsp); ++i)
3254 process_constraint (new_constraint (*lhsp, tmp));
3258 /* Handle aggregate copies by expanding into copies of the respective
3259 fields of the structures. */
3262 do_structure_copy (tree lhsop, tree rhsop)
3264 struct constraint_expr *lhsp, *rhsp;
3265 VEC (ce_s, heap) *lhsc = NULL, *rhsc = NULL;
3268 get_constraint_for (lhsop, &lhsc);
3269 get_constraint_for (rhsop, &rhsc);
3270 lhsp = VEC_index (ce_s, lhsc, 0);
3271 rhsp = VEC_index (ce_s, rhsc, 0);
3272 if (lhsp->type == DEREF
3273 || (lhsp->type == ADDRESSOF && lhsp->var == anything_id)
3274 || rhsp->type == DEREF)
3275 process_all_all_constraints (lhsc, rhsc);
3276 else if (lhsp->type == SCALAR
3277 && (rhsp->type == SCALAR
3278 || rhsp->type == ADDRESSOF))
3280 tree lhsbase, rhsbase;
3281 HOST_WIDE_INT lhssize, lhsmaxsize, lhsoffset;
3282 HOST_WIDE_INT rhssize, rhsmaxsize, rhsoffset;
3284 lhsbase = get_ref_base_and_extent (lhsop, &lhsoffset,
3285 &lhssize, &lhsmaxsize);
3286 rhsbase = get_ref_base_and_extent (rhsop, &rhsoffset,
3287 &rhssize, &rhsmaxsize);
3288 for (j = 0; VEC_iterate (ce_s, lhsc, j, lhsp);)
3290 varinfo_t lhsv, rhsv;
3291 rhsp = VEC_index (ce_s, rhsc, k);
3292 lhsv = get_varinfo (lhsp->var);
3293 rhsv = get_varinfo (rhsp->var);
3294 if (lhsv->may_have_pointers
3295 && ranges_overlap_p (lhsv->offset + rhsoffset, lhsv->size,
3296 rhsv->offset + lhsoffset, rhsv->size))
3297 process_constraint (new_constraint (*lhsp, *rhsp));
3298 if (lhsv->offset + rhsoffset + lhsv->size
3299 > rhsv->offset + lhsoffset + rhsv->size)
3302 if (k >= VEC_length (ce_s, rhsc))
3312 VEC_free (ce_s, heap, lhsc);
3313 VEC_free (ce_s, heap, rhsc);
3316 /* Create a constraint ID = OP. */
3319 make_constraint_to (unsigned id, tree op)
3321 VEC(ce_s, heap) *rhsc = NULL;
3322 struct constraint_expr *c;
3323 struct constraint_expr includes;
3327 includes.offset = 0;
3328 includes.type = SCALAR;
3330 get_constraint_for (op, &rhsc);
3331 for (j = 0; VEC_iterate (ce_s, rhsc, j, c); j++)
3332 process_constraint (new_constraint (includes, *c));
3333 VEC_free (ce_s, heap, rhsc);
3336 /* Create a constraint ID = &FROM. */
3339 make_constraint_from (varinfo_t vi, int from)
3341 struct constraint_expr lhs, rhs;
3349 rhs.type = ADDRESSOF;
3350 process_constraint (new_constraint (lhs, rhs));
3353 /* Create a constraint ID = FROM. */
3356 make_copy_constraint (varinfo_t vi, int from)
3358 struct constraint_expr lhs, rhs;
3367 process_constraint (new_constraint (lhs, rhs));
3370 /* Make constraints necessary to make OP escape. */
3373 make_escape_constraint (tree op)
3375 make_constraint_to (escaped_id, op);
3378 /* Create a new artificial heap variable with NAME and make a
3379 constraint from it to LHS. Return the created variable. */
3382 make_constraint_from_heapvar (varinfo_t lhs, const char *name)
3385 tree heapvar = heapvar_lookup (lhs->decl, lhs->offset);
3387 if (heapvar == NULL_TREE)
3390 heapvar = create_tmp_var_raw (ptr_type_node, name);
3391 DECL_EXTERNAL (heapvar) = 1;
3393 heapvar_insert (lhs->decl, lhs->offset, heapvar);
3395 ann = get_var_ann (heapvar);
3396 ann->is_heapvar = 1;
3399 /* For global vars we need to add a heapvar to the list of referenced
3400 vars of a different function than it was created for originally. */
3401 if (gimple_referenced_vars (cfun))
3402 add_referenced_var (heapvar);
3404 vi = new_var_info (heapvar, name);
3405 vi->is_artificial_var = true;
3406 vi->is_heap_var = true;
3407 vi->is_unknown_size_var = true;
3411 vi->is_full_var = true;
3412 insert_vi_for_tree (heapvar, vi);
3414 make_constraint_from (lhs, vi->id);
3419 /* Create a new artificial heap variable with NAME and make a
3420 constraint from it to LHS. Set flags according to a tag used
3421 for tracking restrict pointers. */
3424 make_constraint_from_restrict (varinfo_t lhs, const char *name)
3427 vi = make_constraint_from_heapvar (lhs, name);
3428 vi->is_restrict_var = 1;
3429 vi->is_global_var = 0;
3430 vi->is_special_var = 1;
3431 vi->may_have_pointers = 0;
3434 /* For non-IPA mode, generate constraints necessary for a call on the
3438 handle_rhs_call (gimple stmt, VEC(ce_s, heap) **results)
3440 struct constraint_expr rhsc;
3443 for (i = 0; i < gimple_call_num_args (stmt); ++i)
3445 tree arg = gimple_call_arg (stmt, i);
3447 /* Find those pointers being passed, and make sure they end up
3448 pointing to anything. */
3449 if (could_have_pointers (arg))
3450 make_escape_constraint (arg);
3453 /* The static chain escapes as well. */
3454 if (gimple_call_chain (stmt))
3455 make_escape_constraint (gimple_call_chain (stmt));
3457 /* And if we applied NRV the address of the return slot escapes as well. */
3458 if (gimple_call_return_slot_opt_p (stmt)
3459 && gimple_call_lhs (stmt) != NULL_TREE
3460 && TREE_ADDRESSABLE (TREE_TYPE (gimple_call_lhs (stmt))))
3462 VEC(ce_s, heap) *tmpc = NULL;
3463 struct constraint_expr lhsc, *c;
3464 get_constraint_for_address_of (gimple_call_lhs (stmt), &tmpc);
3465 lhsc.var = escaped_id;
3468 for (i = 0; VEC_iterate (ce_s, tmpc, i, c); ++i)
3469 process_constraint (new_constraint (lhsc, *c));
3470 VEC_free(ce_s, heap, tmpc);
3473 /* Regular functions return nonlocal memory. */
3474 rhsc.var = nonlocal_id;
3477 VEC_safe_push (ce_s, heap, *results, &rhsc);
3480 /* For non-IPA mode, generate constraints necessary for a call
3481 that returns a pointer and assigns it to LHS. This simply makes
3482 the LHS point to global and escaped variables. */
3485 handle_lhs_call (tree lhs, int flags, VEC(ce_s, heap) *rhsc)
3487 VEC(ce_s, heap) *lhsc = NULL;
3489 get_constraint_for (lhs, &lhsc);
3491 if (flags & ECF_MALLOC)
3494 vi = make_constraint_from_heapvar (get_vi_for_tree (lhs), "HEAP");
3495 /* We delay marking allocated storage global until we know if
3497 DECL_EXTERNAL (vi->decl) = 0;
3498 vi->is_global_var = 0;
3500 else if (VEC_length (ce_s, rhsc) > 0)
3502 /* If the store is to a global decl make sure to
3503 add proper escape constraints. */
3504 lhs = get_base_address (lhs);
3507 && is_global_var (lhs))
3509 struct constraint_expr tmpc;
3510 tmpc.var = escaped_id;
3513 VEC_safe_push (ce_s, heap, lhsc, &tmpc);
3515 process_all_all_constraints (lhsc, rhsc);
3517 VEC_free (ce_s, heap, lhsc);
3520 /* For non-IPA mode, generate constraints necessary for a call of a
3521 const function that returns a pointer in the statement STMT. */
3524 handle_const_call (gimple stmt, VEC(ce_s, heap) **results)
3526 struct constraint_expr rhsc;
3529 /* Treat nested const functions the same as pure functions as far
3530 as the static chain is concerned. */
3531 if (gimple_call_chain (stmt))
3533 make_constraint_to (callused_id, gimple_call_chain (stmt));
3534 rhsc.var = callused_id;
3537 VEC_safe_push (ce_s, heap, *results, &rhsc);
3540 /* May return arguments. */
3541 for (k = 0; k < gimple_call_num_args (stmt); ++k)
3543 tree arg = gimple_call_arg (stmt, k);
3545 if (could_have_pointers (arg))
3547 VEC(ce_s, heap) *argc = NULL;
3549 struct constraint_expr *argp;
3550 get_constraint_for (arg, &argc);
3551 for (i = 0; VEC_iterate (ce_s, argc, i, argp); ++i)
3552 VEC_safe_push (ce_s, heap, *results, argp);
3553 VEC_free(ce_s, heap, argc);
3557 /* May return addresses of globals. */
3558 rhsc.var = nonlocal_id;
3560 rhsc.type = ADDRESSOF;
3561 VEC_safe_push (ce_s, heap, *results, &rhsc);
3564 /* For non-IPA mode, generate constraints necessary for a call to a
3565 pure function in statement STMT. */
3568 handle_pure_call (gimple stmt, VEC(ce_s, heap) **results)
3570 struct constraint_expr rhsc;
3572 bool need_callused = false;
3574 /* Memory reached from pointer arguments is call-used. */
3575 for (i = 0; i < gimple_call_num_args (stmt); ++i)
3577 tree arg = gimple_call_arg (stmt, i);
3579 if (could_have_pointers (arg))
3581 make_constraint_to (callused_id, arg);
3582 need_callused = true;
3586 /* The static chain is used as well. */
3587 if (gimple_call_chain (stmt))
3589 make_constraint_to (callused_id, gimple_call_chain (stmt));
3590 need_callused = true;
3593 /* Pure functions may return callused and nonlocal memory. */
3596 rhsc.var = callused_id;
3599 VEC_safe_push (ce_s, heap, *results, &rhsc);
3601 rhsc.var = nonlocal_id;
3604 VEC_safe_push (ce_s, heap, *results, &rhsc);
3607 /* Walk statement T setting up aliasing constraints according to the
3608 references found in T. This function is the main part of the
3609 constraint builder. AI points to auxiliary alias information used
3610 when building alias sets and computing alias grouping heuristics. */
3613 find_func_aliases (gimple origt)
3616 VEC(ce_s, heap) *lhsc = NULL;
3617 VEC(ce_s, heap) *rhsc = NULL;
3618 struct constraint_expr *c;
3620 /* Now build constraints expressions. */
3621 if (gimple_code (t) == GIMPLE_PHI)
3623 gcc_assert (!AGGREGATE_TYPE_P (TREE_TYPE (gimple_phi_result (t))));
3625 /* Only care about pointers and structures containing
3627 if (could_have_pointers (gimple_phi_result (t)))
3632 /* For a phi node, assign all the arguments to
3634 get_constraint_for (gimple_phi_result (t), &lhsc);
3635 for (i = 0; i < gimple_phi_num_args (t); i++)
3638 tree strippedrhs = PHI_ARG_DEF (t, i);
3640 STRIP_NOPS (strippedrhs);
3641 rhstype = TREE_TYPE (strippedrhs);
3642 get_constraint_for (gimple_phi_arg_def (t, i), &rhsc);
3644 for (j = 0; VEC_iterate (ce_s, lhsc, j, c); j++)
3646 struct constraint_expr *c2;
3647 while (VEC_length (ce_s, rhsc) > 0)
3649 c2 = VEC_last (ce_s, rhsc);
3650 process_constraint (new_constraint (*c, *c2));
3651 VEC_pop (ce_s, rhsc);
3657 /* In IPA mode, we need to generate constraints to pass call
3658 arguments through their calls. There are two cases,
3659 either a GIMPLE_CALL returning a value, or just a plain
3660 GIMPLE_CALL when we are not.
3662 In non-ipa mode, we need to generate constraints for each
3663 pointer passed by address. */
3664 else if (is_gimple_call (t))
3666 tree fndecl = gimple_call_fndecl (t);
3667 if (fndecl != NULL_TREE
3668 && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL)
3669 /* ??? All builtins that are handled here need to be handled
3670 in the alias-oracle query functions explicitly! */
3671 switch (DECL_FUNCTION_CODE (fndecl))
3673 /* All the following functions return a pointer to the same object
3674 as their first argument points to. The functions do not add
3675 to the ESCAPED solution. The functions make the first argument
3676 pointed to memory point to what the second argument pointed to
3677 memory points to. */
3678 case BUILT_IN_STRCPY:
3679 case BUILT_IN_STRNCPY:
3680 case BUILT_IN_BCOPY:
3681 case BUILT_IN_MEMCPY:
3682 case BUILT_IN_MEMMOVE:
3683 case BUILT_IN_MEMPCPY:
3684 case BUILT_IN_STPCPY:
3685 case BUILT_IN_STPNCPY:
3686 case BUILT_IN_STRCAT:
3687 case BUILT_IN_STRNCAT:
3689 tree res = gimple_call_lhs (t);
3690 tree dest = gimple_call_arg (t, (DECL_FUNCTION_CODE (fndecl)
3691 == BUILT_IN_BCOPY ? 1 : 0));
3692 tree src = gimple_call_arg (t, (DECL_FUNCTION_CODE (fndecl)
3693 == BUILT_IN_BCOPY ? 0 : 1));
3694 if (res != NULL_TREE)
3696 get_constraint_for (res, &lhsc);
3697 if (DECL_FUNCTION_CODE (fndecl) == BUILT_IN_MEMPCPY
3698 || DECL_FUNCTION_CODE (fndecl) == BUILT_IN_STPCPY
3699 || DECL_FUNCTION_CODE (fndecl) == BUILT_IN_STPNCPY)
3700 get_constraint_for_ptr_offset (dest, NULL_TREE, &rhsc);
3702 get_constraint_for (dest, &rhsc);
3703 process_all_all_constraints (lhsc, rhsc);
3704 VEC_free (ce_s, heap, lhsc);
3705 VEC_free (ce_s, heap, rhsc);
3707 get_constraint_for_ptr_offset (dest, NULL_TREE, &lhsc);
3708 get_constraint_for_ptr_offset (src, NULL_TREE, &rhsc);
3711 process_all_all_constraints (lhsc, rhsc);
3712 VEC_free (ce_s, heap, lhsc);
3713 VEC_free (ce_s, heap, rhsc);
3716 case BUILT_IN_MEMSET:
3718 tree res = gimple_call_lhs (t);
3719 tree dest = gimple_call_arg (t, 0);
3722 struct constraint_expr ac;
3723 if (res != NULL_TREE)
3725 get_constraint_for (res, &lhsc);
3726 get_constraint_for (dest, &rhsc);
3727 process_all_all_constraints (lhsc, rhsc);
3728 VEC_free (ce_s, heap, lhsc);
3729 VEC_free (ce_s, heap, rhsc);
3731 get_constraint_for_ptr_offset (dest, NULL_TREE, &lhsc);
3733 if (flag_delete_null_pointer_checks
3734 && integer_zerop (gimple_call_arg (t, 1)))
3736 ac.type = ADDRESSOF;
3737 ac.var = nothing_id;
3742 ac.var = integer_id;
3745 for (i = 0; VEC_iterate (ce_s, lhsc, i, lhsp); ++i)
3746 process_constraint (new_constraint (*lhsp, ac));
3747 VEC_free (ce_s, heap, lhsc);
3750 /* All the following functions do not return pointers, do not
3751 modify the points-to sets of memory reachable from their
3752 arguments and do not add to the ESCAPED solution. */
3753 case BUILT_IN_SINCOS:
3754 case BUILT_IN_SINCOSF:
3755 case BUILT_IN_SINCOSL:
3756 case BUILT_IN_FREXP:
3757 case BUILT_IN_FREXPF:
3758 case BUILT_IN_FREXPL:
3759 case BUILT_IN_GAMMA_R:
3760 case BUILT_IN_GAMMAF_R:
3761 case BUILT_IN_GAMMAL_R:
3762 case BUILT_IN_LGAMMA_R:
3763 case BUILT_IN_LGAMMAF_R:
3764 case BUILT_IN_LGAMMAL_R:
3766 case BUILT_IN_MODFF:
3767 case BUILT_IN_MODFL:
3768 case BUILT_IN_REMQUO:
3769 case BUILT_IN_REMQUOF:
3770 case BUILT_IN_REMQUOL:
3773 /* printf-style functions may have hooks to set pointers to
3774 point to somewhere into the generated string. Leave them
3775 for a later excercise... */
3777 /* Fallthru to general call handling. */;
3781 && !lookup_vi_for_tree (fndecl)))
3783 VEC(ce_s, heap) *rhsc = NULL;
3784 int flags = gimple_call_flags (t);
3786 /* Const functions can return their arguments and addresses
3787 of global memory but not of escaped memory. */
3788 if (flags & (ECF_CONST|ECF_NOVOPS))
3790 if (gimple_call_lhs (t)
3791 && could_have_pointers (gimple_call_lhs (t)))
3792 handle_const_call (t, &rhsc);
3794 /* Pure functions can return addresses in and of memory
3795 reachable from their arguments, but they are not an escape
3796 point for reachable memory of their arguments. */
3797 else if (flags & (ECF_PURE|ECF_LOOPING_CONST_OR_PURE))
3798 handle_pure_call (t, &rhsc);
3800 handle_rhs_call (t, &rhsc);
3801 if (gimple_call_lhs (t)
3802 && could_have_pointers (gimple_call_lhs (t)))
3803 handle_lhs_call (gimple_call_lhs (t), flags, rhsc);
3804 VEC_free (ce_s, heap, rhsc);
3814 lhsop = gimple_call_lhs (t);
3815 decl = gimple_call_fndecl (t);
3817 /* If we can directly resolve the function being called, do so.
3818 Otherwise, it must be some sort of indirect expression that
3819 we should still be able to handle. */
3821 fi = get_vi_for_tree (decl);
3824 decl = gimple_call_fn (t);
3825 fi = get_vi_for_tree (decl);
3828 /* Assign all the passed arguments to the appropriate incoming
3829 parameters of the function. */
3830 for (j = 0; j < gimple_call_num_args (t); j++)
3832 struct constraint_expr lhs ;
3833 struct constraint_expr *rhsp;
3834 tree arg = gimple_call_arg (t, j);
3836 get_constraint_for (arg, &rhsc);
3837 if (TREE_CODE (decl) != FUNCTION_DECL)
3846 lhs.var = first_vi_for_offset (fi, i)->id;
3849 while (VEC_length (ce_s, rhsc) != 0)
3851 rhsp = VEC_last (ce_s, rhsc);
3852 process_constraint (new_constraint (lhs, *rhsp));
3853 VEC_pop (ce_s, rhsc);
3858 /* If we are returning a value, assign it to the result. */
3861 struct constraint_expr rhs;
3862 struct constraint_expr *lhsp;
3865 get_constraint_for (lhsop, &lhsc);
3866 if (TREE_CODE (decl) != FUNCTION_DECL)
3875 rhs.var = first_vi_for_offset (fi, i)->id;
3878 for (j = 0; VEC_iterate (ce_s, lhsc, j, lhsp); j++)
3879 process_constraint (new_constraint (*lhsp, rhs));
3883 /* Otherwise, just a regular assignment statement. Only care about
3884 operations with pointer result, others are dealt with as escape
3885 points if they have pointer operands. */
3886 else if (is_gimple_assign (t)
3887 && could_have_pointers (gimple_assign_lhs (t)))
3889 /* Otherwise, just a regular assignment statement. */
3890 tree lhsop = gimple_assign_lhs (t);
3891 tree rhsop = (gimple_num_ops (t) == 2) ? gimple_assign_rhs1 (t) : NULL;
3893 if (rhsop && AGGREGATE_TYPE_P (TREE_TYPE (lhsop)))
3894 do_structure_copy (lhsop, rhsop);
3897 struct constraint_expr temp;
3898 get_constraint_for (lhsop, &lhsc);
3900 if (gimple_assign_rhs_code (t) == POINTER_PLUS_EXPR)
3901 get_constraint_for_ptr_offset (gimple_assign_rhs1 (t),
3902 gimple_assign_rhs2 (t), &rhsc);
3903 else if ((CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (t))
3904 && !(POINTER_TYPE_P (gimple_expr_type (t))
3905 && !POINTER_TYPE_P (TREE_TYPE (rhsop))))
3906 || gimple_assign_single_p (t))
3907 get_constraint_for (rhsop, &rhsc);
3910 temp.type = ADDRESSOF;
3911 temp.var = anything_id;
3913 VEC_safe_push (ce_s, heap, rhsc, &temp);
3915 process_all_all_constraints (lhsc, rhsc);
3917 /* If there is a store to a global variable the rhs escapes. */
3918 if ((lhsop = get_base_address (lhsop)) != NULL_TREE
3920 && is_global_var (lhsop))
3921 make_escape_constraint (rhsop);
3922 /* If this is a conversion of a non-restrict pointer to a
3923 restrict pointer track it with a new heapvar. */
3924 else if (gimple_assign_cast_p (t)
3925 && POINTER_TYPE_P (TREE_TYPE (rhsop))
3926 && POINTER_TYPE_P (TREE_TYPE (lhsop))
3927 && !TYPE_RESTRICT (TREE_TYPE (rhsop))
3928 && TYPE_RESTRICT (TREE_TYPE (lhsop)))
3929 make_constraint_from_restrict (get_vi_for_tree (lhsop),
3932 /* For conversions of pointers to non-pointers the pointer escapes. */
3933 else if (gimple_assign_cast_p (t)
3934 && POINTER_TYPE_P (TREE_TYPE (gimple_assign_rhs1 (t)))
3935 && !POINTER_TYPE_P (TREE_TYPE (gimple_assign_lhs (t))))
3937 make_escape_constraint (gimple_assign_rhs1 (t));
3939 /* Handle escapes through return. */
3940 else if (gimple_code (t) == GIMPLE_RETURN
3941 && gimple_return_retval (t) != NULL_TREE
3942 && could_have_pointers (gimple_return_retval (t)))
3944 make_escape_constraint (gimple_return_retval (t));
3946 /* Handle asms conservatively by adding escape constraints to everything. */
3947 else if (gimple_code (t) == GIMPLE_ASM)
3949 unsigned i, noutputs;
3950 const char **oconstraints;
3951 const char *constraint;
3952 bool allows_mem, allows_reg, is_inout;
3954 noutputs = gimple_asm_noutputs (t);
3955 oconstraints = XALLOCAVEC (const char *, noutputs);
3957 for (i = 0; i < noutputs; ++i)
3959 tree link = gimple_asm_output_op (t, i);
3960 tree op = TREE_VALUE (link);
3962 constraint = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (link)));
3963 oconstraints[i] = constraint;
3964 parse_output_constraint (&constraint, i, 0, 0, &allows_mem,
3965 &allows_reg, &is_inout);
3967 /* A memory constraint makes the address of the operand escape. */
3968 if (!allows_reg && allows_mem)
3969 make_escape_constraint (build_fold_addr_expr (op));
3971 /* The asm may read global memory, so outputs may point to
3972 any global memory. */
3973 if (op && could_have_pointers (op))
3975 VEC(ce_s, heap) *lhsc = NULL;
3976 struct constraint_expr rhsc, *lhsp;
3978 get_constraint_for (op, &lhsc);
3979 rhsc.var = nonlocal_id;
3982 for (j = 0; VEC_iterate (ce_s, lhsc, j, lhsp); j++)
3983 process_constraint (new_constraint (*lhsp, rhsc));
3984 VEC_free (ce_s, heap, lhsc);
3987 for (i = 0; i < gimple_asm_ninputs (t); ++i)
3989 tree link = gimple_asm_input_op (t, i);
3990 tree op = TREE_VALUE (link);
3992 constraint = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (link)));
3994 parse_input_constraint (&constraint, 0, 0, noutputs, 0, oconstraints,
3995 &allows_mem, &allows_reg);
3997 /* A memory constraint makes the address of the operand escape. */
3998 if (!allows_reg && allows_mem)
3999 make_escape_constraint (build_fold_addr_expr (op));
4000 /* Strictly we'd only need the constraint to ESCAPED if
4001 the asm clobbers memory, otherwise using CALLUSED
4003 else if (op && could_have_pointers (op))
4004 make_escape_constraint (op);
4008 VEC_free (ce_s, heap, rhsc);
4009 VEC_free (ce_s, heap, lhsc);
4013 /* Find the first varinfo in the same variable as START that overlaps with
4014 OFFSET. Return NULL if we can't find one. */
4017 first_vi_for_offset (varinfo_t start, unsigned HOST_WIDE_INT offset)
4019 /* If the offset is outside of the variable, bail out. */
4020 if (offset >= start->fullsize)
4023 /* If we cannot reach offset from start, lookup the first field
4024 and start from there. */
4025 if (start->offset > offset)
4026 start = lookup_vi_for_tree (start->decl);
4030 /* We may not find a variable in the field list with the actual
4031 offset when when we have glommed a structure to a variable.
4032 In that case, however, offset should still be within the size
4034 if (offset >= start->offset
4035 && offset < (start->offset + start->size))
4044 /* Find the first varinfo in the same variable as START that overlaps with
4045 OFFSET. If there is no such varinfo the varinfo directly preceding
4046 OFFSET is returned. */
4049 first_or_preceding_vi_for_offset (varinfo_t start,
4050 unsigned HOST_WIDE_INT offset)
4052 /* If we cannot reach offset from start, lookup the first field
4053 and start from there. */
4054 if (start->offset > offset)
4055 start = lookup_vi_for_tree (start->decl);
4057 /* We may not find a variable in the field list with the actual
4058 offset when when we have glommed a structure to a variable.
4059 In that case, however, offset should still be within the size
4061 If we got beyond the offset we look for return the field
4062 directly preceding offset which may be the last field. */
4064 && offset >= start->offset
4065 && !(offset < (start->offset + start->size)))
4066 start = start->next;
4072 /* Insert the varinfo FIELD into the field list for BASE, at the front
4076 insert_into_field_list (varinfo_t base, varinfo_t field)
4078 varinfo_t prev = base;
4079 varinfo_t curr = base->next;
4085 /* Insert the varinfo FIELD into the field list for BASE, ordered by
4089 insert_into_field_list_sorted (varinfo_t base, varinfo_t field)
4091 varinfo_t prev = base;
4092 varinfo_t curr = base->next;
4103 if (field->offset <= curr->offset)
4108 field->next = prev->next;
4113 /* This structure is used during pushing fields onto the fieldstack
4114 to track the offset of the field, since bitpos_of_field gives it
4115 relative to its immediate containing type, and we want it relative
4116 to the ultimate containing object. */
4120 /* Offset from the base of the base containing object to this field. */
4121 HOST_WIDE_INT offset;
4123 /* Size, in bits, of the field. */
4124 unsigned HOST_WIDE_INT size;
4126 unsigned has_unknown_size : 1;
4128 unsigned may_have_pointers : 1;
4130 unsigned only_restrict_pointers : 1;
4132 typedef struct fieldoff fieldoff_s;
4134 DEF_VEC_O(fieldoff_s);
4135 DEF_VEC_ALLOC_O(fieldoff_s,heap);
4137 /* qsort comparison function for two fieldoff's PA and PB */
4140 fieldoff_compare (const void *pa, const void *pb)
4142 const fieldoff_s *foa = (const fieldoff_s *)pa;
4143 const fieldoff_s *fob = (const fieldoff_s *)pb;
4144 unsigned HOST_WIDE_INT foasize, fobsize;
4146 if (foa->offset < fob->offset)
4148 else if (foa->offset > fob->offset)
4151 foasize = foa->size;
4152 fobsize = fob->size;
4153 if (foasize < fobsize)
4155 else if (foasize > fobsize)
4160 /* Sort a fieldstack according to the field offset and sizes. */
4162 sort_fieldstack (VEC(fieldoff_s,heap) *fieldstack)
4164 qsort (VEC_address (fieldoff_s, fieldstack),
4165 VEC_length (fieldoff_s, fieldstack),
4166 sizeof (fieldoff_s),
4170 /* Return true if V is a tree that we can have subvars for.
4171 Normally, this is any aggregate type. Also complex
4172 types which are not gimple registers can have subvars. */
4175 var_can_have_subvars (const_tree v)
4177 /* Volatile variables should never have subvars. */
4178 if (TREE_THIS_VOLATILE (v))
4181 /* Non decls or memory tags can never have subvars. */
4185 /* Aggregates without overlapping fields can have subvars. */
4186 if (TREE_CODE (TREE_TYPE (v)) == RECORD_TYPE)
4192 /* Given a TYPE, and a vector of field offsets FIELDSTACK, push all
4193 the fields of TYPE onto fieldstack, recording their offsets along
4196 OFFSET is used to keep track of the offset in this entire
4197 structure, rather than just the immediately containing structure.
4198 Returns the number of fields pushed. */
4201 push_fields_onto_fieldstack (tree type, VEC(fieldoff_s,heap) **fieldstack,
4202 HOST_WIDE_INT offset)
4207 if (TREE_CODE (type) != RECORD_TYPE)
4210 /* If the vector of fields is growing too big, bail out early.
4211 Callers check for VEC_length <= MAX_FIELDS_FOR_FIELD_SENSITIVE, make
4213 if (VEC_length (fieldoff_s, *fieldstack) > MAX_FIELDS_FOR_FIELD_SENSITIVE)
4216 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
4217 if (TREE_CODE (field) == FIELD_DECL)
4221 HOST_WIDE_INT foff = bitpos_of_field (field);
4223 if (!var_can_have_subvars (field)
4224 || TREE_CODE (TREE_TYPE (field)) == QUAL_UNION_TYPE
4225 || TREE_CODE (TREE_TYPE (field)) == UNION_TYPE)
4227 else if (!(pushed = push_fields_onto_fieldstack
4228 (TREE_TYPE (field), fieldstack, offset + foff))
4229 && (DECL_SIZE (field)
4230 && !integer_zerop (DECL_SIZE (field))))
4231 /* Empty structures may have actual size, like in C++. So
4232 see if we didn't push any subfields and the size is
4233 nonzero, push the field onto the stack. */
4238 fieldoff_s *pair = NULL;
4239 bool has_unknown_size = false;
4241 if (!VEC_empty (fieldoff_s, *fieldstack))
4242 pair = VEC_last (fieldoff_s, *fieldstack);
4244 if (!DECL_SIZE (field)
4245 || !host_integerp (DECL_SIZE (field), 1))
4246 has_unknown_size = true;
4248 /* If adjacent fields do not contain pointers merge them. */
4250 && !pair->may_have_pointers
4251 && !could_have_pointers (field)
4252 && !pair->has_unknown_size
4253 && !has_unknown_size
4254 && pair->offset + (HOST_WIDE_INT)pair->size == offset + foff)
4256 pair = VEC_last (fieldoff_s, *fieldstack);
4257 pair->size += TREE_INT_CST_LOW (DECL_SIZE (field));
4261 pair = VEC_safe_push (fieldoff_s, heap, *fieldstack, NULL);
4262 pair->offset = offset + foff;
4263 pair->has_unknown_size = has_unknown_size;
4264 if (!has_unknown_size)
4265 pair->size = TREE_INT_CST_LOW (DECL_SIZE (field));
4268 pair->may_have_pointers = could_have_pointers (field);
4269 pair->only_restrict_pointers
4270 = (!has_unknown_size
4271 && POINTER_TYPE_P (TREE_TYPE (field))
4272 && TYPE_RESTRICT (TREE_TYPE (field)));
4283 /* Count the number of arguments DECL has, and set IS_VARARGS to true
4284 if it is a varargs function. */
4287 count_num_arguments (tree decl, bool *is_varargs)
4292 for (t = TYPE_ARG_TYPES (TREE_TYPE (decl));
4296 if (TREE_VALUE (t) == void_type_node)
4306 /* Creation function node for DECL, using NAME, and return the index
4307 of the variable we've created for the function. */
4310 create_function_info_for (tree decl, const char *name)
4315 bool is_varargs = false;
4317 /* Create the variable info. */
4319 vi = new_var_info (decl, name);
4322 vi->fullsize = count_num_arguments (decl, &is_varargs) + 1;
4323 insert_vi_for_tree (vi->decl, vi);
4327 /* If it's varargs, we don't know how many arguments it has, so we
4333 vi->is_unknown_size_var = true;
4337 arg = DECL_ARGUMENTS (decl);
4339 /* Set up variables for each argument. */
4340 for (i = 1; i < vi->fullsize; i++)
4343 const char *newname;
4345 tree argdecl = decl;
4350 asprintf (&tempname, "%s.arg%d", name, i-1);
4351 newname = ggc_strdup (tempname);
4354 argvi = new_var_info (argdecl, newname);
4357 argvi->is_full_var = true;
4358 argvi->fullsize = vi->fullsize;
4359 insert_into_field_list_sorted (vi, argvi);
4360 stats.total_vars ++;
4363 insert_vi_for_tree (arg, argvi);
4364 arg = TREE_CHAIN (arg);
4368 /* Create a variable for the return var. */
4369 if (DECL_RESULT (decl) != NULL
4370 || !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (decl))))
4373 const char *newname;
4375 tree resultdecl = decl;
4379 if (DECL_RESULT (decl))
4380 resultdecl = DECL_RESULT (decl);
4382 asprintf (&tempname, "%s.result", name);
4383 newname = ggc_strdup (tempname);
4386 resultvi = new_var_info (resultdecl, newname);
4387 resultvi->offset = i;
4389 resultvi->fullsize = vi->fullsize;
4390 resultvi->is_full_var = true;
4391 insert_into_field_list_sorted (vi, resultvi);
4392 stats.total_vars ++;
4393 if (DECL_RESULT (decl))
4394 insert_vi_for_tree (DECL_RESULT (decl), resultvi);
4401 /* Return true if FIELDSTACK contains fields that overlap.
4402 FIELDSTACK is assumed to be sorted by offset. */
4405 check_for_overlaps (VEC (fieldoff_s,heap) *fieldstack)
4407 fieldoff_s *fo = NULL;
4409 HOST_WIDE_INT lastoffset = -1;
4411 for (i = 0; VEC_iterate (fieldoff_s, fieldstack, i, fo); i++)
4413 if (fo->offset == lastoffset)
4415 lastoffset = fo->offset;
4420 /* Create a varinfo structure for NAME and DECL, and add it to VARMAP.
4421 This will also create any varinfo structures necessary for fields
4425 create_variable_info_for (tree decl, const char *name)
4428 tree decl_type = TREE_TYPE (decl);
4429 tree declsize = DECL_P (decl) ? DECL_SIZE (decl) : TYPE_SIZE (decl_type);
4430 VEC (fieldoff_s,heap) *fieldstack = NULL;
4432 if (var_can_have_subvars (decl) && use_field_sensitive)
4433 push_fields_onto_fieldstack (decl_type, &fieldstack, 0);
4435 /* If the variable doesn't have subvars, we may end up needing to
4436 sort the field list and create fake variables for all the
4438 vi = new_var_info (decl, name);
4440 vi->may_have_pointers = could_have_pointers (decl);
4442 || !host_integerp (declsize, 1))
4444 vi->is_unknown_size_var = true;
4450 vi->fullsize = TREE_INT_CST_LOW (declsize);
4451 vi->size = vi->fullsize;
4454 insert_vi_for_tree (vi->decl, vi);
4455 if (vi->is_global_var
4456 && (!flag_whole_program || !in_ipa_mode)
4457 && vi->may_have_pointers)
4459 if (POINTER_TYPE_P (TREE_TYPE (decl))
4460 && TYPE_RESTRICT (TREE_TYPE (decl)))
4461 make_constraint_from_restrict (vi, "GLOBAL_RESTRICT");
4462 make_copy_constraint (vi, nonlocal_id);
4466 if (use_field_sensitive
4467 && !vi->is_unknown_size_var
4468 && var_can_have_subvars (decl)
4469 && VEC_length (fieldoff_s, fieldstack) > 1
4470 && VEC_length (fieldoff_s, fieldstack) <= MAX_FIELDS_FOR_FIELD_SENSITIVE)
4472 fieldoff_s *fo = NULL;
4473 bool notokay = false;
4476 for (i = 0; !notokay && VEC_iterate (fieldoff_s, fieldstack, i, fo); i++)
4478 if (fo->has_unknown_size
4486 /* We can't sort them if we have a field with a variable sized type,
4487 which will make notokay = true. In that case, we are going to return
4488 without creating varinfos for the fields anyway, so sorting them is a
4492 sort_fieldstack (fieldstack);
4493 /* Due to some C++ FE issues, like PR 22488, we might end up
4494 what appear to be overlapping fields even though they,
4495 in reality, do not overlap. Until the C++ FE is fixed,
4496 we will simply disable field-sensitivity for these cases. */
4497 notokay = check_for_overlaps (fieldstack);
4501 if (VEC_length (fieldoff_s, fieldstack) != 0)
4502 fo = VEC_index (fieldoff_s, fieldstack, 0);
4504 if (fo == NULL || notokay)
4506 vi->is_unknown_size_var = 1;
4509 vi->is_full_var = true;
4510 VEC_free (fieldoff_s, heap, fieldstack);
4514 vi->size = fo->size;
4515 vi->offset = fo->offset;
4516 vi->may_have_pointers = fo->may_have_pointers;
4517 if (vi->is_global_var
4518 && (!flag_whole_program || !in_ipa_mode)
4519 && vi->may_have_pointers)
4521 if (fo->only_restrict_pointers)
4522 make_constraint_from_restrict (vi, "GLOBAL_RESTRICT");
4524 for (i = VEC_length (fieldoff_s, fieldstack) - 1;
4525 i >= 1 && VEC_iterate (fieldoff_s, fieldstack, i, fo);
4529 const char *newname = "NULL";
4534 asprintf (&tempname, "%s." HOST_WIDE_INT_PRINT_DEC
4535 "+" HOST_WIDE_INT_PRINT_DEC,
4536 vi->name, fo->offset, fo->size);
4537 newname = ggc_strdup (tempname);
4540 newvi = new_var_info (decl, newname);
4541 newvi->offset = fo->offset;
4542 newvi->size = fo->size;
4543 newvi->fullsize = vi->fullsize;
4544 newvi->may_have_pointers = fo->may_have_pointers;
4545 insert_into_field_list (vi, newvi);
4546 if ((newvi->is_global_var || TREE_CODE (decl) == PARM_DECL)
4547 && newvi->may_have_pointers)
4549 if (fo->only_restrict_pointers)
4550 make_constraint_from_restrict (newvi, "GLOBAL_RESTRICT");
4551 if (newvi->is_global_var && !in_ipa_mode)
4552 make_copy_constraint (newvi, nonlocal_id);
4559 vi->is_full_var = true;
4561 VEC_free (fieldoff_s, heap, fieldstack);
4566 /* Print out the points-to solution for VAR to FILE. */
4569 dump_solution_for_var (FILE *file, unsigned int var)
4571 varinfo_t vi = get_varinfo (var);
4575 if (find (var) != var)
4577 varinfo_t vipt = get_varinfo (find (var));
4578 fprintf (file, "%s = same as %s\n", vi->name, vipt->name);
4582 fprintf (file, "%s = { ", vi->name);
4583 EXECUTE_IF_SET_IN_BITMAP (vi->solution, 0, i, bi)
4585 fprintf (file, "%s ", get_varinfo (i)->name);
4587 fprintf (file, "}\n");
4591 /* Print the points-to solution for VAR to stdout. */
4594 debug_solution_for_var (unsigned int var)
4596 dump_solution_for_var (stdout, var);
4599 /* Create varinfo structures for all of the variables in the
4600 function for intraprocedural mode. */
4603 intra_create_variable_infos (void)
4607 /* For each incoming pointer argument arg, create the constraint ARG
4608 = NONLOCAL or a dummy variable if flag_argument_noalias is set. */
4609 for (t = DECL_ARGUMENTS (current_function_decl); t; t = TREE_CHAIN (t))
4613 if (!could_have_pointers (t))
4616 /* For restrict qualified pointers to objects passed by
4617 reference build a real representative for the pointed-to object. */
4618 if (DECL_BY_REFERENCE (t)
4619 && POINTER_TYPE_P (TREE_TYPE (t))
4620 && TYPE_RESTRICT (TREE_TYPE (t)))
4622 struct constraint_expr lhsc, rhsc;
4624 tree heapvar = heapvar_lookup (t, 0);
4625 if (heapvar == NULL_TREE)
4628 heapvar = create_tmp_var_raw (TREE_TYPE (TREE_TYPE (t)),
4630 DECL_EXTERNAL (heapvar) = 1;
4631 heapvar_insert (t, 0, heapvar);
4632 ann = get_var_ann (heapvar);
4633 ann->is_heapvar = 1;
4635 if (gimple_referenced_vars (cfun))
4636 add_referenced_var (heapvar);
4637 lhsc.var = get_vi_for_tree (t)->id;
4640 rhsc.var = (vi = get_vi_for_tree (heapvar))->id;
4641 rhsc.type = ADDRESSOF;
4643 process_constraint (new_constraint (lhsc, rhsc));
4644 vi->is_restrict_var = 1;
4648 for (p = get_vi_for_tree (t); p; p = p->next)
4649 if (p->may_have_pointers)
4650 make_constraint_from (p, nonlocal_id);
4651 if (POINTER_TYPE_P (TREE_TYPE (t))
4652 && TYPE_RESTRICT (TREE_TYPE (t)))
4653 make_constraint_from_restrict (get_vi_for_tree (t), "PARM_RESTRICT");
4656 /* Add a constraint for a result decl that is passed by reference. */
4657 if (DECL_RESULT (cfun->decl)
4658 && DECL_BY_REFERENCE (DECL_RESULT (cfun->decl)))
4660 varinfo_t p, result_vi = get_vi_for_tree (DECL_RESULT (cfun->decl));
4662 for (p = result_vi; p; p = p->next)
4663 make_constraint_from (p, nonlocal_id);
4666 /* Add a constraint for the incoming static chain parameter. */
4667 if (cfun->static_chain_decl != NULL_TREE)
4669 varinfo_t p, chain_vi = get_vi_for_tree (cfun->static_chain_decl);
4671 for (p = chain_vi; p; p = p->next)
4672 make_constraint_from (p, nonlocal_id);
4676 /* Structure used to put solution bitmaps in a hashtable so they can
4677 be shared among variables with the same points-to set. */
4679 typedef struct shared_bitmap_info
4683 } *shared_bitmap_info_t;
4684 typedef const struct shared_bitmap_info *const_shared_bitmap_info_t;
4686 static htab_t shared_bitmap_table;
4688 /* Hash function for a shared_bitmap_info_t */
4691 shared_bitmap_hash (const void *p)
4693 const_shared_bitmap_info_t const bi = (const_shared_bitmap_info_t) p;
4694 return bi->hashcode;
4697 /* Equality function for two shared_bitmap_info_t's. */
4700 shared_bitmap_eq (const void *p1, const void *p2)
4702 const_shared_bitmap_info_t const sbi1 = (const_shared_bitmap_info_t) p1;
4703 const_shared_bitmap_info_t const sbi2 = (const_shared_bitmap_info_t) p2;
4704 return bitmap_equal_p (sbi1->pt_vars, sbi2->pt_vars);
4707 /* Lookup a bitmap in the shared bitmap hashtable, and return an already
4708 existing instance if there is one, NULL otherwise. */
4711 shared_bitmap_lookup (bitmap pt_vars)
4714 struct shared_bitmap_info sbi;
4716 sbi.pt_vars = pt_vars;
4717 sbi.hashcode = bitmap_hash (pt_vars);
4719 slot = htab_find_slot_with_hash (shared_bitmap_table, &sbi,
4720 sbi.hashcode, NO_INSERT);
4724 return ((shared_bitmap_info_t) *slot)->pt_vars;
4728 /* Add a bitmap to the shared bitmap hashtable. */
4731 shared_bitmap_add (bitmap pt_vars)
4734 shared_bitmap_info_t sbi = XNEW (struct shared_bitmap_info);
4736 sbi->pt_vars = pt_vars;
4737 sbi->hashcode = bitmap_hash (pt_vars);
4739 slot = htab_find_slot_with_hash (shared_bitmap_table, sbi,
4740 sbi->hashcode, INSERT);
4741 gcc_assert (!*slot);
4742 *slot = (void *) sbi;
4746 /* Set bits in INTO corresponding to the variable uids in solution set FROM. */
4749 set_uids_in_ptset (bitmap into, bitmap from, struct pt_solution *pt)
4754 EXECUTE_IF_SET_IN_BITMAP (from, 0, i, bi)
4756 varinfo_t vi = get_varinfo (i);
4758 /* The only artificial variables that are allowed in a may-alias
4759 set are heap variables. */
4760 if (vi->is_artificial_var && !vi->is_heap_var)
4763 if (TREE_CODE (vi->decl) == VAR_DECL
4764 || TREE_CODE (vi->decl) == PARM_DECL
4765 || TREE_CODE (vi->decl) == RESULT_DECL)
4767 /* Add the decl to the points-to set. Note that the points-to
4768 set contains global variables. */
4769 bitmap_set_bit (into, DECL_UID (vi->decl));
4770 if (vi->is_global_var)
4771 pt->vars_contains_global = true;
4777 /* Compute the points-to solution *PT for the variable VI. */
4780 find_what_var_points_to (varinfo_t vi, struct pt_solution *pt)
4784 bitmap finished_solution;
4787 memset (pt, 0, sizeof (struct pt_solution));
4789 /* This variable may have been collapsed, let's get the real
4791 vi = get_varinfo (find (vi->id));
4793 /* Translate artificial variables into SSA_NAME_PTR_INFO
4795 EXECUTE_IF_SET_IN_BITMAP (vi->solution, 0, i, bi)
4797 varinfo_t vi = get_varinfo (i);
4799 if (vi->is_artificial_var)
4801 if (vi->id == nothing_id)
4803 else if (vi->id == escaped_id)
4805 else if (vi->id == callused_id)
4807 else if (vi->id == nonlocal_id)
4809 else if (vi->is_heap_var)
4810 /* We represent heapvars in the points-to set properly. */
4812 else if (vi->id == readonly_id)
4815 else if (vi->id == anything_id
4816 || vi->id == integer_id)
4819 if (vi->is_restrict_var)
4820 pt->vars_contains_restrict = true;
4823 /* Instead of doing extra work, simply do not create
4824 elaborate points-to information for pt_anything pointers. */
4826 && (vi->is_artificial_var
4827 || !pt->vars_contains_restrict))
4830 /* Share the final set of variables when possible. */
4831 finished_solution = BITMAP_GGC_ALLOC ();
4832 stats.points_to_sets_created++;
4834 set_uids_in_ptset (finished_solution, vi->solution, pt);
4835 result = shared_bitmap_lookup (finished_solution);
4838 shared_bitmap_add (finished_solution);
4839 pt->vars = finished_solution;
4844 bitmap_clear (finished_solution);
4848 /* Given a pointer variable P, fill in its points-to set. */
4851 find_what_p_points_to (tree p)
4853 struct ptr_info_def *pi;
4857 /* For parameters, get at the points-to set for the actual parm
4859 if (TREE_CODE (p) == SSA_NAME
4860 && TREE_CODE (SSA_NAME_VAR (p)) == PARM_DECL
4861 && SSA_NAME_IS_DEFAULT_DEF (p))
4862 lookup_p = SSA_NAME_VAR (p);
4864 vi = lookup_vi_for_tree (lookup_p);
4868 pi = get_ptr_info (p);
4869 find_what_var_points_to (vi, &pi->pt);
4873 /* Query statistics for points-to solutions. */
4876 unsigned HOST_WIDE_INT pt_solution_includes_may_alias;
4877 unsigned HOST_WIDE_INT pt_solution_includes_no_alias;
4878 unsigned HOST_WIDE_INT pt_solutions_intersect_may_alias;
4879 unsigned HOST_WIDE_INT pt_solutions_intersect_no_alias;
4883 dump_pta_stats (FILE *s)
4885 fprintf (s, "\nPTA query stats:\n");
4886 fprintf (s, " pt_solution_includes: "
4887 HOST_WIDE_INT_PRINT_DEC" disambiguations, "
4888 HOST_WIDE_INT_PRINT_DEC" queries\n",
4889 pta_stats.pt_solution_includes_no_alias,
4890 pta_stats.pt_solution_includes_no_alias
4891 + pta_stats.pt_solution_includes_may_alias);
4892 fprintf (s, " pt_solutions_intersect: "
4893 HOST_WIDE_INT_PRINT_DEC" disambiguations, "
4894 HOST_WIDE_INT_PRINT_DEC" queries\n",
4895 pta_stats.pt_solutions_intersect_no_alias,
4896 pta_stats.pt_solutions_intersect_no_alias
4897 + pta_stats.pt_solutions_intersect_may_alias);
4901 /* Reset the points-to solution *PT to a conservative default
4902 (point to anything). */
4905 pt_solution_reset (struct pt_solution *pt)
4907 memset (pt, 0, sizeof (struct pt_solution));
4908 pt->anything = true;
4911 /* Set the points-to solution *PT to point only to the variables
4915 pt_solution_set (struct pt_solution *pt, bitmap vars)
4920 memset (pt, 0, sizeof (struct pt_solution));
4922 EXECUTE_IF_SET_IN_BITMAP (vars, 0, i, bi)
4924 tree var = referenced_var_lookup (i);
4925 if (is_global_var (var))
4927 pt->vars_contains_global = true;
4933 /* Return true if the points-to solution *PT is empty. */
4936 pt_solution_empty_p (struct pt_solution *pt)
4943 && !bitmap_empty_p (pt->vars))
4946 /* If the solution includes ESCAPED, check if that is empty. */
4948 && !pt_solution_empty_p (&cfun->gimple_df->escaped))
4954 /* Return true if the points-to solution *PT includes global memory. */
4957 pt_solution_includes_global (struct pt_solution *pt)
4961 || pt->vars_contains_global)
4965 return pt_solution_includes_global (&cfun->gimple_df->escaped);
4970 /* Return true if the points-to solution *PT includes the variable
4971 declaration DECL. */
4974 pt_solution_includes_1 (struct pt_solution *pt, const_tree decl)
4980 && is_global_var (decl))
4984 && bitmap_bit_p (pt->vars, DECL_UID (decl)))
4987 /* If the solution includes ESCAPED, check it. */
4989 && pt_solution_includes_1 (&cfun->gimple_df->escaped, decl))
4996 pt_solution_includes (struct pt_solution *pt, const_tree decl)
4998 bool res = pt_solution_includes_1 (pt, decl);
5000 ++pta_stats.pt_solution_includes_may_alias;
5002 ++pta_stats.pt_solution_includes_no_alias;
5006 /* Return true if both points-to solutions PT1 and PT2 have a non-empty
5010 pt_solutions_intersect_1 (struct pt_solution *pt1, struct pt_solution *pt2)
5012 if (pt1->anything || pt2->anything)
5015 /* If either points to unknown global memory and the other points to
5016 any global memory they alias. */
5019 || pt2->vars_contains_global))
5021 && pt1->vars_contains_global))
5024 /* Check the escaped solution if required. */
5025 if ((pt1->escaped || pt2->escaped)
5026 && !pt_solution_empty_p (&cfun->gimple_df->escaped))
5028 /* If both point to escaped memory and that solution
5029 is not empty they alias. */
5030 if (pt1->escaped && pt2->escaped)
5033 /* If either points to escaped memory see if the escaped solution
5034 intersects with the other. */
5036 && pt_solutions_intersect_1 (&cfun->gimple_df->escaped, pt2))
5038 && pt_solutions_intersect_1 (&cfun->gimple_df->escaped, pt1)))
5042 /* Now both pointers alias if their points-to solution intersects. */
5045 && bitmap_intersect_p (pt1->vars, pt2->vars));
5049 pt_solutions_intersect (struct pt_solution *pt1, struct pt_solution *pt2)
5051 bool res = pt_solutions_intersect_1 (pt1, pt2);
5053 ++pta_stats.pt_solutions_intersect_may_alias;
5055 ++pta_stats.pt_solutions_intersect_no_alias;
5059 /* Return true if both points-to solutions PT1 and PT2 for two restrict
5060 qualified pointers are possibly based on the same pointer. */
5063 pt_solutions_same_restrict_base (struct pt_solution *pt1,
5064 struct pt_solution *pt2)
5066 /* If we deal with points-to solutions of two restrict qualified
5067 pointers solely rely on the pointed-to variable bitmap intersection.
5068 For two pointers that are based on each other the bitmaps will
5070 if (pt1->vars_contains_restrict
5071 && pt2->vars_contains_restrict)
5073 gcc_assert (pt1->vars && pt2->vars);
5074 return bitmap_intersect_p (pt1->vars, pt2->vars);
5081 /* Dump points-to information to OUTFILE. */
5084 dump_sa_points_to_info (FILE *outfile)
5088 fprintf (outfile, "\nPoints-to sets\n\n");
5090 if (dump_flags & TDF_STATS)
5092 fprintf (outfile, "Stats:\n");
5093 fprintf (outfile, "Total vars: %d\n", stats.total_vars);
5094 fprintf (outfile, "Non-pointer vars: %d\n",
5095 stats.nonpointer_vars);
5096 fprintf (outfile, "Statically unified vars: %d\n",
5097 stats.unified_vars_static);
5098 fprintf (outfile, "Dynamically unified vars: %d\n",
5099 stats.unified_vars_dynamic);
5100 fprintf (outfile, "Iterations: %d\n", stats.iterations);
5101 fprintf (outfile, "Number of edges: %d\n", stats.num_edges);
5102 fprintf (outfile, "Number of implicit edges: %d\n",
5103 stats.num_implicit_edges);
5106 for (i = 0; i < VEC_length (varinfo_t, varmap); i++)
5107 dump_solution_for_var (outfile, i);
5111 /* Debug points-to information to stderr. */
5114 debug_sa_points_to_info (void)
5116 dump_sa_points_to_info (stderr);
5120 /* Initialize the always-existing constraint variables for NULL
5121 ANYTHING, READONLY, and INTEGER */
5124 init_base_vars (void)
5126 struct constraint_expr lhs, rhs;
5127 varinfo_t var_anything;
5128 varinfo_t var_nothing;
5129 varinfo_t var_readonly;
5130 varinfo_t var_escaped;
5131 varinfo_t var_nonlocal;
5132 varinfo_t var_callused;
5133 varinfo_t var_storedanything;
5134 varinfo_t var_integer;
5136 /* Create the NULL variable, used to represent that a variable points
5138 var_nothing = new_var_info (NULL_TREE, "NULL");
5139 gcc_assert (var_nothing->id == nothing_id);
5140 var_nothing->is_artificial_var = 1;
5141 var_nothing->offset = 0;
5142 var_nothing->size = ~0;
5143 var_nothing->fullsize = ~0;
5144 var_nothing->is_special_var = 1;
5146 /* Create the ANYTHING variable, used to represent that a variable
5147 points to some unknown piece of memory. */
5148 var_anything = new_var_info (NULL_TREE, "ANYTHING");
5149 gcc_assert (var_anything->id == anything_id);
5150 var_anything->is_artificial_var = 1;
5151 var_anything->size = ~0;
5152 var_anything->offset = 0;
5153 var_anything->next = NULL;
5154 var_anything->fullsize = ~0;
5155 var_anything->is_special_var = 1;
5157 /* Anything points to anything. This makes deref constraints just
5158 work in the presence of linked list and other p = *p type loops,
5159 by saying that *ANYTHING = ANYTHING. */
5161 lhs.var = anything_id;
5163 rhs.type = ADDRESSOF;
5164 rhs.var = anything_id;
5167 /* This specifically does not use process_constraint because
5168 process_constraint ignores all anything = anything constraints, since all
5169 but this one are redundant. */
5170 VEC_safe_push (constraint_t, heap, constraints, new_constraint (lhs, rhs));
5172 /* Create the READONLY variable, used to represent that a variable
5173 points to readonly memory. */
5174 var_readonly = new_var_info (NULL_TREE, "READONLY");
5175 gcc_assert (var_readonly->id == readonly_id);
5176 var_readonly->is_artificial_var = 1;
5177 var_readonly->offset = 0;
5178 var_readonly->size = ~0;
5179 var_readonly->fullsize = ~0;
5180 var_readonly->next = NULL;
5181 var_readonly->is_special_var = 1;
5183 /* readonly memory points to anything, in order to make deref
5184 easier. In reality, it points to anything the particular
5185 readonly variable can point to, but we don't track this
5188 lhs.var = readonly_id;
5190 rhs.type = ADDRESSOF;
5191 rhs.var = readonly_id; /* FIXME */
5193 process_constraint (new_constraint (lhs, rhs));
5195 /* Create the ESCAPED variable, used to represent the set of escaped
5197 var_escaped = new_var_info (NULL_TREE, "ESCAPED");
5198 gcc_assert (var_escaped->id == escaped_id);
5199 var_escaped->is_artificial_var = 1;
5200 var_escaped->offset = 0;
5201 var_escaped->size = ~0;
5202 var_escaped->fullsize = ~0;
5203 var_escaped->is_special_var = 0;
5205 /* Create the NONLOCAL variable, used to represent the set of nonlocal
5207 var_nonlocal = new_var_info (NULL_TREE, "NONLOCAL");
5208 gcc_assert (var_nonlocal->id == nonlocal_id);
5209 var_nonlocal->is_artificial_var = 1;
5210 var_nonlocal->offset = 0;
5211 var_nonlocal->size = ~0;
5212 var_nonlocal->fullsize = ~0;
5213 var_nonlocal->is_special_var = 1;
5215 /* ESCAPED = *ESCAPED, because escaped is may-deref'd at calls, etc. */
5217 lhs.var = escaped_id;
5220 rhs.var = escaped_id;
5222 process_constraint (new_constraint (lhs, rhs));
5224 /* ESCAPED = ESCAPED + UNKNOWN_OFFSET, because if a sub-field escapes the
5225 whole variable escapes. */
5227 lhs.var = escaped_id;
5230 rhs.var = escaped_id;
5231 rhs.offset = UNKNOWN_OFFSET;
5232 process_constraint (new_constraint (lhs, rhs));
5234 /* *ESCAPED = NONLOCAL. This is true because we have to assume
5235 everything pointed to by escaped points to what global memory can
5238 lhs.var = escaped_id;
5241 rhs.var = nonlocal_id;
5243 process_constraint (new_constraint (lhs, rhs));
5245 /* NONLOCAL = &NONLOCAL, NONLOCAL = &ESCAPED. This is true because
5246 global memory may point to global memory and escaped memory. */
5248 lhs.var = nonlocal_id;
5250 rhs.type = ADDRESSOF;
5251 rhs.var = nonlocal_id;
5253 process_constraint (new_constraint (lhs, rhs));
5254 rhs.type = ADDRESSOF;
5255 rhs.var = escaped_id;
5257 process_constraint (new_constraint (lhs, rhs));
5259 /* Create the CALLUSED variable, used to represent the set of call-used
5261 var_callused = new_var_info (NULL_TREE, "CALLUSED");
5262 gcc_assert (var_callused->id == callused_id);
5263 var_callused->is_artificial_var = 1;
5264 var_callused->offset = 0;
5265 var_callused->size = ~0;
5266 var_callused->fullsize = ~0;
5267 var_callused->is_special_var = 0;
5269 /* CALLUSED = *CALLUSED, because call-used is may-deref'd at calls, etc. */
5271 lhs.var = callused_id;
5274 rhs.var = callused_id;
5276 process_constraint (new_constraint (lhs, rhs));
5278 /* CALLUSED = CALLUSED + UNKNOWN, because if a sub-field is call-used the
5279 whole variable is call-used. */
5281 lhs.var = callused_id;
5284 rhs.var = callused_id;
5285 rhs.offset = UNKNOWN_OFFSET;
5286 process_constraint (new_constraint (lhs, rhs));
5288 /* Create the STOREDANYTHING variable, used to represent the set of
5289 variables stored to *ANYTHING. */
5290 var_storedanything = new_var_info (NULL_TREE, "STOREDANYTHING");
5291 gcc_assert (var_storedanything->id == storedanything_id);
5292 var_storedanything->is_artificial_var = 1;
5293 var_storedanything->offset = 0;
5294 var_storedanything->size = ~0;
5295 var_storedanything->fullsize = ~0;
5296 var_storedanything->is_special_var = 0;
5298 /* Create the INTEGER variable, used to represent that a variable points
5299 to what an INTEGER "points to". */
5300 var_integer = new_var_info (NULL_TREE, "INTEGER");
5301 gcc_assert (var_integer->id == integer_id);
5302 var_integer->is_artificial_var = 1;
5303 var_integer->size = ~0;
5304 var_integer->fullsize = ~0;
5305 var_integer->offset = 0;
5306 var_integer->next = NULL;
5307 var_integer->is_special_var = 1;
5309 /* INTEGER = ANYTHING, because we don't know where a dereference of
5310 a random integer will point to. */
5312 lhs.var = integer_id;
5314 rhs.type = ADDRESSOF;
5315 rhs.var = anything_id;
5317 process_constraint (new_constraint (lhs, rhs));
5320 /* Initialize things necessary to perform PTA */
5323 init_alias_vars (void)
5325 use_field_sensitive = (MAX_FIELDS_FOR_FIELD_SENSITIVE > 1);
5327 bitmap_obstack_initialize (&pta_obstack);
5328 bitmap_obstack_initialize (&oldpta_obstack);
5329 bitmap_obstack_initialize (&predbitmap_obstack);
5331 constraint_pool = create_alloc_pool ("Constraint pool",
5332 sizeof (struct constraint), 30);
5333 variable_info_pool = create_alloc_pool ("Variable info pool",
5334 sizeof (struct variable_info), 30);
5335 constraints = VEC_alloc (constraint_t, heap, 8);
5336 varmap = VEC_alloc (varinfo_t, heap, 8);
5337 vi_for_tree = pointer_map_create ();
5339 memset (&stats, 0, sizeof (stats));
5340 shared_bitmap_table = htab_create (511, shared_bitmap_hash,
5341 shared_bitmap_eq, free);
5345 /* Remove the REF and ADDRESS edges from GRAPH, as well as all the
5346 predecessor edges. */
5349 remove_preds_and_fake_succs (constraint_graph_t graph)
5353 /* Clear the implicit ref and address nodes from the successor
5355 for (i = 0; i < FIRST_REF_NODE; i++)
5357 if (graph->succs[i])
5358 bitmap_clear_range (graph->succs[i], FIRST_REF_NODE,
5359 FIRST_REF_NODE * 2);
5362 /* Free the successor list for the non-ref nodes. */
5363 for (i = FIRST_REF_NODE; i < graph->size; i++)
5365 if (graph->succs[i])
5366 BITMAP_FREE (graph->succs[i]);
5369 /* Now reallocate the size of the successor list as, and blow away
5370 the predecessor bitmaps. */
5371 graph->size = VEC_length (varinfo_t, varmap);
5372 graph->succs = XRESIZEVEC (bitmap, graph->succs, graph->size);
5374 free (graph->implicit_preds);
5375 graph->implicit_preds = NULL;
5376 free (graph->preds);
5377 graph->preds = NULL;
5378 bitmap_obstack_release (&predbitmap_obstack);
5381 /* Initialize the heapvar for statement mapping. */
5384 init_alias_heapvars (void)
5386 if (!heapvar_for_stmt)
5387 heapvar_for_stmt = htab_create_ggc (11, tree_map_hash, heapvar_map_eq,
5391 /* Delete the heapvar for statement mapping. */
5394 delete_alias_heapvars (void)
5396 if (heapvar_for_stmt)
5397 htab_delete (heapvar_for_stmt);
5398 heapvar_for_stmt = NULL;
5401 /* Solve the constraint set. */
5404 solve_constraints (void)
5406 struct scc_info *si;
5410 fprintf (dump_file, "Points-to analysis\n\nConstraints:\n\n");
5411 dump_constraints (dump_file);
5416 "\nCollapsing static cycles and doing variable "
5419 init_graph (VEC_length (varinfo_t, varmap) * 2);
5422 fprintf (dump_file, "Building predecessor graph\n");
5423 build_pred_graph ();
5426 fprintf (dump_file, "Detecting pointer and location "
5428 si = perform_var_substitution (graph);
5431 fprintf (dump_file, "Rewriting constraints and unifying "
5433 rewrite_constraints (graph, si);
5435 build_succ_graph ();
5436 free_var_substitution_info (si);
5438 if (dump_file && (dump_flags & TDF_GRAPH))
5439 dump_constraint_graph (dump_file);
5441 move_complex_constraints (graph);
5444 fprintf (dump_file, "Uniting pointer but not location equivalent "
5446 unite_pointer_equivalences (graph);
5449 fprintf (dump_file, "Finding indirect cycles\n");
5450 find_indirect_cycles (graph);
5452 /* Implicit nodes and predecessors are no longer necessary at this
5454 remove_preds_and_fake_succs (graph);
5457 fprintf (dump_file, "Solving graph\n");
5459 solve_graph (graph);
5462 dump_sa_points_to_info (dump_file);
5465 /* Create points-to sets for the current function. See the comments
5466 at the start of the file for an algorithmic overview. */
5469 compute_points_to_sets (void)
5475 timevar_push (TV_TREE_PTA);
5478 init_alias_heapvars ();
5480 intra_create_variable_infos ();
5482 /* Now walk all statements and derive aliases. */
5485 gimple_stmt_iterator gsi;
5487 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
5489 gimple phi = gsi_stmt (gsi);
5491 if (is_gimple_reg (gimple_phi_result (phi)))
5492 find_func_aliases (phi);
5495 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
5497 gimple stmt = gsi_stmt (gsi);
5499 find_func_aliases (stmt);
5503 /* From the constraints compute the points-to sets. */
5504 solve_constraints ();
5506 /* Compute the points-to sets for ESCAPED and CALLUSED used for
5507 call-clobber analysis. */
5508 find_what_var_points_to (get_varinfo (escaped_id),
5509 &cfun->gimple_df->escaped);
5510 find_what_var_points_to (get_varinfo (callused_id),
5511 &cfun->gimple_df->callused);
5513 /* Make sure the ESCAPED solution (which is used as placeholder in
5514 other solutions) does not reference itself. This simplifies
5515 points-to solution queries. */
5516 cfun->gimple_df->escaped.escaped = 0;
5518 /* Mark escaped HEAP variables as global. */
5519 for (i = 0; VEC_iterate (varinfo_t, varmap, i, vi); ++i)
5521 && !vi->is_restrict_var
5522 && !vi->is_global_var)
5523 DECL_EXTERNAL (vi->decl) = vi->is_global_var
5524 = pt_solution_includes (&cfun->gimple_df->escaped, vi->decl);
5526 /* Compute the points-to sets for pointer SSA_NAMEs. */
5527 for (i = 0; i < num_ssa_names; ++i)
5529 tree ptr = ssa_name (i);
5531 && POINTER_TYPE_P (TREE_TYPE (ptr)))
5532 find_what_p_points_to (ptr);
5535 timevar_pop (TV_TREE_PTA);
5539 /* Delete created points-to sets. */
5542 delete_points_to_sets (void)
5546 htab_delete (shared_bitmap_table);
5547 if (dump_file && (dump_flags & TDF_STATS))
5548 fprintf (dump_file, "Points to sets created:%d\n",
5549 stats.points_to_sets_created);
5551 pointer_map_destroy (vi_for_tree);
5552 bitmap_obstack_release (&pta_obstack);
5553 VEC_free (constraint_t, heap, constraints);
5555 for (i = 0; i < graph->size; i++)
5556 VEC_free (constraint_t, heap, graph->complex[i]);
5557 free (graph->complex);
5560 free (graph->succs);
5562 free (graph->pe_rep);
5563 free (graph->indirect_cycles);
5566 VEC_free (varinfo_t, heap, varmap);
5567 free_alloc_pool (variable_info_pool);
5568 free_alloc_pool (constraint_pool);
5572 /* Compute points-to information for every SSA_NAME pointer in the
5573 current function and compute the transitive closure of escaped
5574 variables to re-initialize the call-clobber states of local variables. */
5577 compute_may_aliases (void)
5579 /* For each pointer P_i, determine the sets of variables that P_i may
5580 point-to. Compute the reachability set of escaped and call-used
5582 compute_points_to_sets ();
5584 /* Debugging dumps. */
5587 dump_alias_info (dump_file);
5589 if (dump_flags & TDF_DETAILS)
5590 dump_referenced_vars (dump_file);
5593 /* Deallocate memory used by aliasing data structures and the internal
5594 points-to solution. */
5595 delete_points_to_sets ();
5597 gcc_assert (!need_ssa_update_p (cfun));
5603 gate_tree_pta (void)
5605 return flag_tree_pta;
5608 /* A dummy pass to cause points-to information to be computed via
5609 TODO_rebuild_alias. */
5611 struct gimple_opt_pass pass_build_alias =
5616 gate_tree_pta, /* gate */
5620 0, /* static_pass_number */
5621 TV_NONE, /* tv_id */
5622 PROP_cfg | PROP_ssa, /* properties_required */
5623 0, /* properties_provided */
5624 0, /* properties_destroyed */
5625 0, /* todo_flags_start */
5626 TODO_rebuild_alias | TODO_dump_func /* todo_flags_finish */
5630 /* A dummy pass to cause points-to information to be computed via
5631 TODO_rebuild_alias. */
5633 struct gimple_opt_pass pass_build_ealias =
5637 "ealias", /* name */
5638 gate_tree_pta, /* gate */
5642 0, /* static_pass_number */
5643 TV_NONE, /* tv_id */
5644 PROP_cfg | PROP_ssa, /* properties_required */
5645 0, /* properties_provided */
5646 0, /* properties_destroyed */
5647 0, /* todo_flags_start */
5648 TODO_rebuild_alias | TODO_dump_func /* todo_flags_finish */
5653 /* Return true if we should execute IPA PTA. */
5657 return (flag_ipa_pta
5658 /* Don't bother doing anything if the program has errors. */
5659 && !(errorcount || sorrycount));
5662 /* Execute the driver for IPA PTA. */
5664 ipa_pta_execute (void)
5666 struct cgraph_node *node;
5670 init_alias_heapvars ();
5673 /* Build the constraints. */
5674 for (node = cgraph_nodes; node; node = node->next)
5678 /* Nodes without a body are not interesting. Especially do not
5679 visit clones at this point for now - we get duplicate decls
5680 there for inline clones at least. */
5681 if (!gimple_has_body_p (node->decl)
5685 /* It does not make sense to have graph edges into or out of
5686 externally visible functions. There is no extra information
5687 we can gather from them. */
5688 if (node->local.externally_visible)
5691 varid = create_function_info_for (node->decl,
5692 cgraph_node_name (node));
5695 for (node = cgraph_nodes; node; node = node->next)
5697 struct function *func;
5701 /* Nodes without a body are not interesting. */
5702 if (!gimple_has_body_p (node->decl)
5708 "Generating constraints for %s\n",
5709 cgraph_node_name (node));
5711 func = DECL_STRUCT_FUNCTION (node->decl);
5712 old_func_decl = current_function_decl;
5714 current_function_decl = node->decl;
5716 /* For externally visible functions use local constraints for
5717 their arguments. For local functions we see all callers
5718 and thus do not need initial constraints for parameters. */
5719 if (node->local.externally_visible)
5720 intra_create_variable_infos ();
5722 /* Build constriants for the function body. */
5723 FOR_EACH_BB_FN (bb, func)
5725 gimple_stmt_iterator gsi;
5727 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi);
5730 gimple phi = gsi_stmt (gsi);
5732 if (is_gimple_reg (gimple_phi_result (phi)))
5733 find_func_aliases (phi);
5736 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
5738 gimple stmt = gsi_stmt (gsi);
5740 find_func_aliases (stmt);
5744 current_function_decl = old_func_decl;
5748 /* From the constraints compute the points-to sets. */
5749 solve_constraints ();
5751 delete_points_to_sets ();
5758 struct simple_ipa_opt_pass pass_ipa_pta =
5763 gate_ipa_pta, /* gate */
5764 ipa_pta_execute, /* execute */
5767 0, /* static_pass_number */
5768 TV_IPA_PTA, /* tv_id */
5769 0, /* properties_required */
5770 0, /* properties_provided */
5771 0, /* properties_destroyed */
5772 0, /* todo_flags_start */
5773 TODO_update_ssa /* todo_flags_finish */
5778 #include "gt-tree-ssa-structalias.h"