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 that can
1273 receive pointers. */
1274 t = find (storedanything_id);
1275 for (i = integer_id + 1; i < FIRST_REF_NODE; ++i)
1277 if (!TEST_BIT (graph->direct_nodes, i)
1278 && get_varinfo (i)->may_have_pointers)
1279 add_graph_edge (graph, find (i), t);
1282 /* Everything stored to ANYTHING also potentially escapes. */
1283 add_graph_edge (graph, find (escaped_id), t);
1287 /* Changed variables on the last iteration. */
1288 static unsigned int changed_count;
1289 static sbitmap changed;
1291 /* Strongly Connected Component visitation info. */
1298 unsigned int *node_mapping;
1300 VEC(unsigned,heap) *scc_stack;
1304 /* Recursive routine to find strongly connected components in GRAPH.
1305 SI is the SCC info to store the information in, and N is the id of current
1306 graph node we are processing.
1308 This is Tarjan's strongly connected component finding algorithm, as
1309 modified by Nuutila to keep only non-root nodes on the stack.
1310 The algorithm can be found in "On finding the strongly connected
1311 connected components in a directed graph" by Esko Nuutila and Eljas
1312 Soisalon-Soininen, in Information Processing Letters volume 49,
1313 number 1, pages 9-14. */
1316 scc_visit (constraint_graph_t graph, struct scc_info *si, unsigned int n)
1320 unsigned int my_dfs;
1322 SET_BIT (si->visited, n);
1323 si->dfs[n] = si->current_index ++;
1324 my_dfs = si->dfs[n];
1326 /* Visit all the successors. */
1327 EXECUTE_IF_IN_NONNULL_BITMAP (graph->succs[n], 0, i, bi)
1331 if (i > LAST_REF_NODE)
1335 if (TEST_BIT (si->deleted, w))
1338 if (!TEST_BIT (si->visited, w))
1339 scc_visit (graph, si, w);
1341 unsigned int t = find (w);
1342 unsigned int nnode = find (n);
1343 gcc_assert (nnode == n);
1345 if (si->dfs[t] < si->dfs[nnode])
1346 si->dfs[n] = si->dfs[t];
1350 /* See if any components have been identified. */
1351 if (si->dfs[n] == my_dfs)
1353 if (VEC_length (unsigned, si->scc_stack) > 0
1354 && si->dfs[VEC_last (unsigned, si->scc_stack)] >= my_dfs)
1356 bitmap scc = BITMAP_ALLOC (NULL);
1357 bool have_ref_node = n >= FIRST_REF_NODE;
1358 unsigned int lowest_node;
1361 bitmap_set_bit (scc, n);
1363 while (VEC_length (unsigned, si->scc_stack) != 0
1364 && si->dfs[VEC_last (unsigned, si->scc_stack)] >= my_dfs)
1366 unsigned int w = VEC_pop (unsigned, si->scc_stack);
1368 bitmap_set_bit (scc, w);
1369 if (w >= FIRST_REF_NODE)
1370 have_ref_node = true;
1373 lowest_node = bitmap_first_set_bit (scc);
1374 gcc_assert (lowest_node < FIRST_REF_NODE);
1376 /* Collapse the SCC nodes into a single node, and mark the
1378 EXECUTE_IF_SET_IN_BITMAP (scc, 0, i, bi)
1380 if (i < FIRST_REF_NODE)
1382 if (unite (lowest_node, i))
1383 unify_nodes (graph, lowest_node, i, false);
1387 unite (lowest_node, i);
1388 graph->indirect_cycles[i - FIRST_REF_NODE] = lowest_node;
1392 SET_BIT (si->deleted, n);
1395 VEC_safe_push (unsigned, heap, si->scc_stack, n);
1398 /* Unify node FROM into node TO, updating the changed count if
1399 necessary when UPDATE_CHANGED is true. */
1402 unify_nodes (constraint_graph_t graph, unsigned int to, unsigned int from,
1403 bool update_changed)
1406 gcc_assert (to != from && find (to) == to);
1407 if (dump_file && (dump_flags & TDF_DETAILS))
1408 fprintf (dump_file, "Unifying %s to %s\n",
1409 get_varinfo (from)->name,
1410 get_varinfo (to)->name);
1413 stats.unified_vars_dynamic++;
1415 stats.unified_vars_static++;
1417 merge_graph_nodes (graph, to, from);
1418 merge_node_constraints (graph, to, from);
1420 /* Mark TO as changed if FROM was changed. If TO was already marked
1421 as changed, decrease the changed count. */
1423 if (update_changed && TEST_BIT (changed, from))
1425 RESET_BIT (changed, from);
1426 if (!TEST_BIT (changed, to))
1427 SET_BIT (changed, to);
1430 gcc_assert (changed_count > 0);
1434 if (get_varinfo (from)->solution)
1436 /* If the solution changes because of the merging, we need to mark
1437 the variable as changed. */
1438 if (bitmap_ior_into (get_varinfo (to)->solution,
1439 get_varinfo (from)->solution))
1441 if (update_changed && !TEST_BIT (changed, to))
1443 SET_BIT (changed, to);
1448 BITMAP_FREE (get_varinfo (from)->solution);
1449 BITMAP_FREE (get_varinfo (from)->oldsolution);
1451 if (stats.iterations > 0)
1453 BITMAP_FREE (get_varinfo (to)->oldsolution);
1454 get_varinfo (to)->oldsolution = BITMAP_ALLOC (&oldpta_obstack);
1457 if (valid_graph_edge (graph, to, to))
1459 if (graph->succs[to])
1460 bitmap_clear_bit (graph->succs[to], to);
1464 /* Information needed to compute the topological ordering of a graph. */
1468 /* sbitmap of visited nodes. */
1470 /* Array that stores the topological order of the graph, *in
1472 VEC(unsigned,heap) *topo_order;
1476 /* Initialize and return a topological info structure. */
1478 static struct topo_info *
1479 init_topo_info (void)
1481 size_t size = graph->size;
1482 struct topo_info *ti = XNEW (struct topo_info);
1483 ti->visited = sbitmap_alloc (size);
1484 sbitmap_zero (ti->visited);
1485 ti->topo_order = VEC_alloc (unsigned, heap, 1);
1490 /* Free the topological sort info pointed to by TI. */
1493 free_topo_info (struct topo_info *ti)
1495 sbitmap_free (ti->visited);
1496 VEC_free (unsigned, heap, ti->topo_order);
1500 /* Visit the graph in topological order, and store the order in the
1501 topo_info structure. */
1504 topo_visit (constraint_graph_t graph, struct topo_info *ti,
1510 SET_BIT (ti->visited, n);
1512 if (graph->succs[n])
1513 EXECUTE_IF_SET_IN_BITMAP (graph->succs[n], 0, j, bi)
1515 if (!TEST_BIT (ti->visited, j))
1516 topo_visit (graph, ti, j);
1519 VEC_safe_push (unsigned, heap, ti->topo_order, n);
1522 /* Process a constraint C that represents x = *(y + off), using DELTA as the
1523 starting solution for y. */
1526 do_sd_constraint (constraint_graph_t graph, constraint_t c,
1529 unsigned int lhs = c->lhs.var;
1531 bitmap sol = get_varinfo (lhs)->solution;
1534 HOST_WIDE_INT roffset = c->rhs.offset;
1536 /* Our IL does not allow this. */
1537 gcc_assert (c->lhs.offset == 0);
1539 /* If the solution of Y contains anything it is good enough to transfer
1541 if (bitmap_bit_p (delta, anything_id))
1543 flag |= bitmap_set_bit (sol, anything_id);
1547 /* If we do not know at with offset the rhs is dereferenced compute
1548 the reachability set of DELTA, conservatively assuming it is
1549 dereferenced at all valid offsets. */
1550 if (roffset == UNKNOWN_OFFSET)
1552 solution_set_expand (delta, delta);
1553 /* No further offset processing is necessary. */
1557 /* For each variable j in delta (Sol(y)), add
1558 an edge in the graph from j to x, and union Sol(j) into Sol(x). */
1559 EXECUTE_IF_SET_IN_BITMAP (delta, 0, j, bi)
1561 varinfo_t v = get_varinfo (j);
1562 HOST_WIDE_INT fieldoffset = v->offset + roffset;
1566 fieldoffset = v->offset;
1567 else if (roffset != 0)
1568 v = first_vi_for_offset (v, fieldoffset);
1569 /* If the access is outside of the variable we can ignore it. */
1577 /* Adding edges from the special vars is pointless.
1578 They don't have sets that can change. */
1579 if (get_varinfo (t)->is_special_var)
1580 flag |= bitmap_ior_into (sol, get_varinfo (t)->solution);
1581 /* Merging the solution from ESCAPED needlessly increases
1582 the set. Use ESCAPED as representative instead. */
1583 else if (v->id == escaped_id)
1584 flag |= bitmap_set_bit (sol, escaped_id);
1585 else if (add_graph_edge (graph, lhs, t))
1586 flag |= bitmap_ior_into (sol, get_varinfo (t)->solution);
1588 /* If the variable is not exactly at the requested offset
1589 we have to include the next one. */
1590 if (v->offset == (unsigned HOST_WIDE_INT)fieldoffset
1595 fieldoffset = v->offset;
1601 /* If the LHS solution changed, mark the var as changed. */
1604 get_varinfo (lhs)->solution = sol;
1605 if (!TEST_BIT (changed, lhs))
1607 SET_BIT (changed, lhs);
1613 /* Process a constraint C that represents *(x + off) = y using DELTA
1614 as the starting solution for x. */
1617 do_ds_constraint (constraint_t c, bitmap delta)
1619 unsigned int rhs = c->rhs.var;
1620 bitmap sol = get_varinfo (rhs)->solution;
1623 HOST_WIDE_INT loff = c->lhs.offset;
1625 /* Our IL does not allow this. */
1626 gcc_assert (c->rhs.offset == 0);
1628 /* If the solution of y contains ANYTHING simply use the ANYTHING
1629 solution. This avoids needlessly increasing the points-to sets. */
1630 if (bitmap_bit_p (sol, anything_id))
1631 sol = get_varinfo (find (anything_id))->solution;
1633 /* If the solution for x contains ANYTHING we have to merge the
1634 solution of y into all pointer variables which we do via
1636 if (bitmap_bit_p (delta, anything_id))
1638 unsigned t = find (storedanything_id);
1639 if (add_graph_edge (graph, t, rhs))
1641 if (bitmap_ior_into (get_varinfo (t)->solution, sol))
1643 if (!TEST_BIT (changed, t))
1645 SET_BIT (changed, t);
1653 /* If we do not know at with offset the rhs is dereferenced compute
1654 the reachability set of DELTA, conservatively assuming it is
1655 dereferenced at all valid offsets. */
1656 if (loff == UNKNOWN_OFFSET)
1658 solution_set_expand (delta, delta);
1662 /* For each member j of delta (Sol(x)), add an edge from y to j and
1663 union Sol(y) into Sol(j) */
1664 EXECUTE_IF_SET_IN_BITMAP (delta, 0, j, bi)
1666 varinfo_t v = get_varinfo (j);
1668 HOST_WIDE_INT fieldoffset = v->offset + loff;
1670 /* If v is a global variable then this is an escape point. */
1671 if (v->is_global_var)
1673 t = find (escaped_id);
1674 if (add_graph_edge (graph, t, rhs)
1675 && bitmap_ior_into (get_varinfo (t)->solution, sol)
1676 && !TEST_BIT (changed, t))
1678 SET_BIT (changed, t);
1683 if (v->is_special_var)
1687 fieldoffset = v->offset;
1689 v = first_vi_for_offset (v, fieldoffset);
1690 /* If the access is outside of the variable we can ignore it. */
1696 if (v->may_have_pointers)
1699 if (add_graph_edge (graph, t, rhs)
1700 && bitmap_ior_into (get_varinfo (t)->solution, sol)
1701 && !TEST_BIT (changed, t))
1703 SET_BIT (changed, t);
1708 /* If the variable is not exactly at the requested offset
1709 we have to include the next one. */
1710 if (v->offset == (unsigned HOST_WIDE_INT)fieldoffset
1715 fieldoffset = v->offset;
1721 /* Handle a non-simple (simple meaning requires no iteration),
1722 constraint (IE *x = &y, x = *y, *x = y, and x = y with offsets involved). */
1725 do_complex_constraint (constraint_graph_t graph, constraint_t c, bitmap delta)
1727 if (c->lhs.type == DEREF)
1729 if (c->rhs.type == ADDRESSOF)
1736 do_ds_constraint (c, delta);
1739 else if (c->rhs.type == DEREF)
1742 if (!(get_varinfo (c->lhs.var)->is_special_var))
1743 do_sd_constraint (graph, c, delta);
1751 gcc_assert (c->rhs.type == SCALAR && c->lhs.type == SCALAR);
1752 solution = get_varinfo (c->rhs.var)->solution;
1753 tmp = get_varinfo (c->lhs.var)->solution;
1755 flag = set_union_with_increment (tmp, solution, c->rhs.offset);
1759 get_varinfo (c->lhs.var)->solution = tmp;
1760 if (!TEST_BIT (changed, c->lhs.var))
1762 SET_BIT (changed, c->lhs.var);
1769 /* Initialize and return a new SCC info structure. */
1771 static struct scc_info *
1772 init_scc_info (size_t size)
1774 struct scc_info *si = XNEW (struct scc_info);
1777 si->current_index = 0;
1778 si->visited = sbitmap_alloc (size);
1779 sbitmap_zero (si->visited);
1780 si->deleted = sbitmap_alloc (size);
1781 sbitmap_zero (si->deleted);
1782 si->node_mapping = XNEWVEC (unsigned int, size);
1783 si->dfs = XCNEWVEC (unsigned int, size);
1785 for (i = 0; i < size; i++)
1786 si->node_mapping[i] = i;
1788 si->scc_stack = VEC_alloc (unsigned, heap, 1);
1792 /* Free an SCC info structure pointed to by SI */
1795 free_scc_info (struct scc_info *si)
1797 sbitmap_free (si->visited);
1798 sbitmap_free (si->deleted);
1799 free (si->node_mapping);
1801 VEC_free (unsigned, heap, si->scc_stack);
1806 /* Find indirect cycles in GRAPH that occur, using strongly connected
1807 components, and note them in the indirect cycles map.
1809 This technique comes from Ben Hardekopf and Calvin Lin,
1810 "It Pays to be Lazy: Fast and Accurate Pointer Analysis for Millions of
1811 Lines of Code", submitted to PLDI 2007. */
1814 find_indirect_cycles (constraint_graph_t graph)
1817 unsigned int size = graph->size;
1818 struct scc_info *si = init_scc_info (size);
1820 for (i = 0; i < MIN (LAST_REF_NODE, size); i ++ )
1821 if (!TEST_BIT (si->visited, i) && find (i) == i)
1822 scc_visit (graph, si, i);
1827 /* Compute a topological ordering for GRAPH, and store the result in the
1828 topo_info structure TI. */
1831 compute_topo_order (constraint_graph_t graph,
1832 struct topo_info *ti)
1835 unsigned int size = graph->size;
1837 for (i = 0; i != size; ++i)
1838 if (!TEST_BIT (ti->visited, i) && find (i) == i)
1839 topo_visit (graph, ti, i);
1842 /* Structure used to for hash value numbering of pointer equivalence
1845 typedef struct equiv_class_label
1848 unsigned int equivalence_class;
1850 } *equiv_class_label_t;
1851 typedef const struct equiv_class_label *const_equiv_class_label_t;
1853 /* A hashtable for mapping a bitmap of labels->pointer equivalence
1855 static htab_t pointer_equiv_class_table;
1857 /* A hashtable for mapping a bitmap of labels->location equivalence
1859 static htab_t location_equiv_class_table;
1861 /* Hash function for a equiv_class_label_t */
1864 equiv_class_label_hash (const void *p)
1866 const_equiv_class_label_t const ecl = (const_equiv_class_label_t) p;
1867 return ecl->hashcode;
1870 /* Equality function for two equiv_class_label_t's. */
1873 equiv_class_label_eq (const void *p1, const void *p2)
1875 const_equiv_class_label_t const eql1 = (const_equiv_class_label_t) p1;
1876 const_equiv_class_label_t const eql2 = (const_equiv_class_label_t) p2;
1877 return (eql1->hashcode == eql2->hashcode
1878 && bitmap_equal_p (eql1->labels, eql2->labels));
1881 /* Lookup a equivalence class in TABLE by the bitmap of LABELS it
1885 equiv_class_lookup (htab_t table, bitmap labels)
1888 struct equiv_class_label ecl;
1890 ecl.labels = labels;
1891 ecl.hashcode = bitmap_hash (labels);
1893 slot = htab_find_slot_with_hash (table, &ecl,
1894 ecl.hashcode, NO_INSERT);
1898 return ((equiv_class_label_t) *slot)->equivalence_class;
1902 /* Add an equivalence class named EQUIVALENCE_CLASS with labels LABELS
1906 equiv_class_add (htab_t table, unsigned int equivalence_class,
1910 equiv_class_label_t ecl = XNEW (struct equiv_class_label);
1912 ecl->labels = labels;
1913 ecl->equivalence_class = equivalence_class;
1914 ecl->hashcode = bitmap_hash (labels);
1916 slot = htab_find_slot_with_hash (table, ecl,
1917 ecl->hashcode, INSERT);
1918 gcc_assert (!*slot);
1919 *slot = (void *) ecl;
1922 /* Perform offline variable substitution.
1924 This is a worst case quadratic time way of identifying variables
1925 that must have equivalent points-to sets, including those caused by
1926 static cycles, and single entry subgraphs, in the constraint graph.
1928 The technique is described in "Exploiting Pointer and Location
1929 Equivalence to Optimize Pointer Analysis. In the 14th International
1930 Static Analysis Symposium (SAS), August 2007." It is known as the
1931 "HU" algorithm, and is equivalent to value numbering the collapsed
1932 constraint graph including evaluating unions.
1934 The general method of finding equivalence classes is as follows:
1935 Add fake nodes (REF nodes) and edges for *a = b and a = *b constraints.
1936 Initialize all non-REF nodes to be direct nodes.
1937 For each constraint a = a U {b}, we set pts(a) = pts(a) u {fresh
1939 For each constraint containing the dereference, we also do the same
1942 We then compute SCC's in the graph and unify nodes in the same SCC,
1945 For each non-collapsed node x:
1946 Visit all unvisited explicit incoming edges.
1947 Ignoring all non-pointers, set pts(x) = Union of pts(a) for y
1949 Lookup the equivalence class for pts(x).
1950 If we found one, equivalence_class(x) = found class.
1951 Otherwise, equivalence_class(x) = new class, and new_class is
1952 added to the lookup table.
1954 All direct nodes with the same equivalence class can be replaced
1955 with a single representative node.
1956 All unlabeled nodes (label == 0) are not pointers and all edges
1957 involving them can be eliminated.
1958 We perform these optimizations during rewrite_constraints
1960 In addition to pointer equivalence class finding, we also perform
1961 location equivalence class finding. This is the set of variables
1962 that always appear together in points-to sets. We use this to
1963 compress the size of the points-to sets. */
1965 /* Current maximum pointer equivalence class id. */
1966 static int pointer_equiv_class;
1968 /* Current maximum location equivalence class id. */
1969 static int location_equiv_class;
1971 /* Recursive routine to find strongly connected components in GRAPH,
1972 and label it's nodes with DFS numbers. */
1975 condense_visit (constraint_graph_t graph, struct scc_info *si, unsigned int n)
1979 unsigned int my_dfs;
1981 gcc_assert (si->node_mapping[n] == n);
1982 SET_BIT (si->visited, n);
1983 si->dfs[n] = si->current_index ++;
1984 my_dfs = si->dfs[n];
1986 /* Visit all the successors. */
1987 EXECUTE_IF_IN_NONNULL_BITMAP (graph->preds[n], 0, i, bi)
1989 unsigned int w = si->node_mapping[i];
1991 if (TEST_BIT (si->deleted, w))
1994 if (!TEST_BIT (si->visited, w))
1995 condense_visit (graph, si, w);
1997 unsigned int t = si->node_mapping[w];
1998 unsigned int nnode = si->node_mapping[n];
1999 gcc_assert (nnode == n);
2001 if (si->dfs[t] < si->dfs[nnode])
2002 si->dfs[n] = si->dfs[t];
2006 /* Visit all the implicit predecessors. */
2007 EXECUTE_IF_IN_NONNULL_BITMAP (graph->implicit_preds[n], 0, i, bi)
2009 unsigned int w = si->node_mapping[i];
2011 if (TEST_BIT (si->deleted, w))
2014 if (!TEST_BIT (si->visited, w))
2015 condense_visit (graph, si, w);
2017 unsigned int t = si->node_mapping[w];
2018 unsigned int nnode = si->node_mapping[n];
2019 gcc_assert (nnode == n);
2021 if (si->dfs[t] < si->dfs[nnode])
2022 si->dfs[n] = si->dfs[t];
2026 /* See if any components have been identified. */
2027 if (si->dfs[n] == my_dfs)
2029 while (VEC_length (unsigned, si->scc_stack) != 0
2030 && si->dfs[VEC_last (unsigned, si->scc_stack)] >= my_dfs)
2032 unsigned int w = VEC_pop (unsigned, si->scc_stack);
2033 si->node_mapping[w] = n;
2035 if (!TEST_BIT (graph->direct_nodes, w))
2036 RESET_BIT (graph->direct_nodes, n);
2038 /* Unify our nodes. */
2039 if (graph->preds[w])
2041 if (!graph->preds[n])
2042 graph->preds[n] = BITMAP_ALLOC (&predbitmap_obstack);
2043 bitmap_ior_into (graph->preds[n], graph->preds[w]);
2045 if (graph->implicit_preds[w])
2047 if (!graph->implicit_preds[n])
2048 graph->implicit_preds[n] = BITMAP_ALLOC (&predbitmap_obstack);
2049 bitmap_ior_into (graph->implicit_preds[n],
2050 graph->implicit_preds[w]);
2052 if (graph->points_to[w])
2054 if (!graph->points_to[n])
2055 graph->points_to[n] = BITMAP_ALLOC (&predbitmap_obstack);
2056 bitmap_ior_into (graph->points_to[n],
2057 graph->points_to[w]);
2060 SET_BIT (si->deleted, n);
2063 VEC_safe_push (unsigned, heap, si->scc_stack, n);
2066 /* Label pointer equivalences. */
2069 label_visit (constraint_graph_t graph, struct scc_info *si, unsigned int n)
2073 SET_BIT (si->visited, n);
2075 if (!graph->points_to[n])
2076 graph->points_to[n] = BITMAP_ALLOC (&predbitmap_obstack);
2078 /* Label and union our incoming edges's points to sets. */
2079 EXECUTE_IF_IN_NONNULL_BITMAP (graph->preds[n], 0, i, bi)
2081 unsigned int w = si->node_mapping[i];
2082 if (!TEST_BIT (si->visited, w))
2083 label_visit (graph, si, w);
2085 /* Skip unused edges */
2086 if (w == n || graph->pointer_label[w] == 0)
2089 if (graph->points_to[w])
2090 bitmap_ior_into(graph->points_to[n], graph->points_to[w]);
2092 /* Indirect nodes get fresh variables. */
2093 if (!TEST_BIT (graph->direct_nodes, n))
2094 bitmap_set_bit (graph->points_to[n], FIRST_REF_NODE + n);
2096 if (!bitmap_empty_p (graph->points_to[n]))
2098 unsigned int label = equiv_class_lookup (pointer_equiv_class_table,
2099 graph->points_to[n]);
2102 label = pointer_equiv_class++;
2103 equiv_class_add (pointer_equiv_class_table,
2104 label, graph->points_to[n]);
2106 graph->pointer_label[n] = label;
2110 /* Perform offline variable substitution, discovering equivalence
2111 classes, and eliminating non-pointer variables. */
2113 static struct scc_info *
2114 perform_var_substitution (constraint_graph_t graph)
2117 unsigned int size = graph->size;
2118 struct scc_info *si = init_scc_info (size);
2120 bitmap_obstack_initialize (&iteration_obstack);
2121 pointer_equiv_class_table = htab_create (511, equiv_class_label_hash,
2122 equiv_class_label_eq, free);
2123 location_equiv_class_table = htab_create (511, equiv_class_label_hash,
2124 equiv_class_label_eq, free);
2125 pointer_equiv_class = 1;
2126 location_equiv_class = 1;
2128 /* Condense the nodes, which means to find SCC's, count incoming
2129 predecessors, and unite nodes in SCC's. */
2130 for (i = 0; i < FIRST_REF_NODE; i++)
2131 if (!TEST_BIT (si->visited, si->node_mapping[i]))
2132 condense_visit (graph, si, si->node_mapping[i]);
2134 sbitmap_zero (si->visited);
2135 /* Actually the label the nodes for pointer equivalences */
2136 for (i = 0; i < FIRST_REF_NODE; i++)
2137 if (!TEST_BIT (si->visited, si->node_mapping[i]))
2138 label_visit (graph, si, si->node_mapping[i]);
2140 /* Calculate location equivalence labels. */
2141 for (i = 0; i < FIRST_REF_NODE; i++)
2148 if (!graph->pointed_by[i])
2150 pointed_by = BITMAP_ALLOC (&iteration_obstack);
2152 /* Translate the pointed-by mapping for pointer equivalence
2154 EXECUTE_IF_SET_IN_BITMAP (graph->pointed_by[i], 0, j, bi)
2156 bitmap_set_bit (pointed_by,
2157 graph->pointer_label[si->node_mapping[j]]);
2159 /* The original pointed_by is now dead. */
2160 BITMAP_FREE (graph->pointed_by[i]);
2162 /* Look up the location equivalence label if one exists, or make
2164 label = equiv_class_lookup (location_equiv_class_table,
2168 label = location_equiv_class++;
2169 equiv_class_add (location_equiv_class_table,
2174 if (dump_file && (dump_flags & TDF_DETAILS))
2175 fprintf (dump_file, "Found location equivalence for node %s\n",
2176 get_varinfo (i)->name);
2177 BITMAP_FREE (pointed_by);
2179 graph->loc_label[i] = label;
2183 if (dump_file && (dump_flags & TDF_DETAILS))
2184 for (i = 0; i < FIRST_REF_NODE; i++)
2186 bool direct_node = TEST_BIT (graph->direct_nodes, i);
2188 "Equivalence classes for %s node id %d:%s are pointer: %d"
2190 direct_node ? "Direct node" : "Indirect node", i,
2191 get_varinfo (i)->name,
2192 graph->pointer_label[si->node_mapping[i]],
2193 graph->loc_label[si->node_mapping[i]]);
2196 /* Quickly eliminate our non-pointer variables. */
2198 for (i = 0; i < FIRST_REF_NODE; i++)
2200 unsigned int node = si->node_mapping[i];
2202 if (graph->pointer_label[node] == 0)
2204 if (dump_file && (dump_flags & TDF_DETAILS))
2206 "%s is a non-pointer variable, eliminating edges.\n",
2207 get_varinfo (node)->name);
2208 stats.nonpointer_vars++;
2209 clear_edges_for_node (graph, node);
2216 /* Free information that was only necessary for variable
2220 free_var_substitution_info (struct scc_info *si)
2223 free (graph->pointer_label);
2224 free (graph->loc_label);
2225 free (graph->pointed_by);
2226 free (graph->points_to);
2227 free (graph->eq_rep);
2228 sbitmap_free (graph->direct_nodes);
2229 htab_delete (pointer_equiv_class_table);
2230 htab_delete (location_equiv_class_table);
2231 bitmap_obstack_release (&iteration_obstack);
2234 /* Return an existing node that is equivalent to NODE, which has
2235 equivalence class LABEL, if one exists. Return NODE otherwise. */
2238 find_equivalent_node (constraint_graph_t graph,
2239 unsigned int node, unsigned int label)
2241 /* If the address version of this variable is unused, we can
2242 substitute it for anything else with the same label.
2243 Otherwise, we know the pointers are equivalent, but not the
2244 locations, and we can unite them later. */
2246 if (!bitmap_bit_p (graph->address_taken, node))
2248 gcc_assert (label < graph->size);
2250 if (graph->eq_rep[label] != -1)
2252 /* Unify the two variables since we know they are equivalent. */
2253 if (unite (graph->eq_rep[label], node))
2254 unify_nodes (graph, graph->eq_rep[label], node, false);
2255 return graph->eq_rep[label];
2259 graph->eq_rep[label] = node;
2260 graph->pe_rep[label] = node;
2265 gcc_assert (label < graph->size);
2266 graph->pe[node] = label;
2267 if (graph->pe_rep[label] == -1)
2268 graph->pe_rep[label] = node;
2274 /* Unite pointer equivalent but not location equivalent nodes in
2275 GRAPH. This may only be performed once variable substitution is
2279 unite_pointer_equivalences (constraint_graph_t graph)
2283 /* Go through the pointer equivalences and unite them to their
2284 representative, if they aren't already. */
2285 for (i = 0; i < FIRST_REF_NODE; i++)
2287 unsigned int label = graph->pe[i];
2290 int label_rep = graph->pe_rep[label];
2292 if (label_rep == -1)
2295 label_rep = find (label_rep);
2296 if (label_rep >= 0 && unite (label_rep, find (i)))
2297 unify_nodes (graph, label_rep, i, false);
2302 /* Move complex constraints to the GRAPH nodes they belong to. */
2305 move_complex_constraints (constraint_graph_t graph)
2310 for (i = 0; VEC_iterate (constraint_t, constraints, i, c); i++)
2314 struct constraint_expr lhs = c->lhs;
2315 struct constraint_expr rhs = c->rhs;
2317 if (lhs.type == DEREF)
2319 insert_into_complex (graph, lhs.var, c);
2321 else if (rhs.type == DEREF)
2323 if (!(get_varinfo (lhs.var)->is_special_var))
2324 insert_into_complex (graph, rhs.var, c);
2326 else if (rhs.type != ADDRESSOF && lhs.var > anything_id
2327 && (lhs.offset != 0 || rhs.offset != 0))
2329 insert_into_complex (graph, rhs.var, c);
2336 /* Optimize and rewrite complex constraints while performing
2337 collapsing of equivalent nodes. SI is the SCC_INFO that is the
2338 result of perform_variable_substitution. */
2341 rewrite_constraints (constraint_graph_t graph,
2342 struct scc_info *si)
2348 for (j = 0; j < graph->size; j++)
2349 gcc_assert (find (j) == j);
2351 for (i = 0; VEC_iterate (constraint_t, constraints, i, c); i++)
2353 struct constraint_expr lhs = c->lhs;
2354 struct constraint_expr rhs = c->rhs;
2355 unsigned int lhsvar = find (lhs.var);
2356 unsigned int rhsvar = find (rhs.var);
2357 unsigned int lhsnode, rhsnode;
2358 unsigned int lhslabel, rhslabel;
2360 lhsnode = si->node_mapping[lhsvar];
2361 rhsnode = si->node_mapping[rhsvar];
2362 lhslabel = graph->pointer_label[lhsnode];
2363 rhslabel = graph->pointer_label[rhsnode];
2365 /* See if it is really a non-pointer variable, and if so, ignore
2369 if (dump_file && (dump_flags & TDF_DETAILS))
2372 fprintf (dump_file, "%s is a non-pointer variable,"
2373 "ignoring constraint:",
2374 get_varinfo (lhs.var)->name);
2375 dump_constraint (dump_file, c);
2377 VEC_replace (constraint_t, constraints, i, NULL);
2383 if (dump_file && (dump_flags & TDF_DETAILS))
2386 fprintf (dump_file, "%s is a non-pointer variable,"
2387 "ignoring constraint:",
2388 get_varinfo (rhs.var)->name);
2389 dump_constraint (dump_file, c);
2391 VEC_replace (constraint_t, constraints, i, NULL);
2395 lhsvar = find_equivalent_node (graph, lhsvar, lhslabel);
2396 rhsvar = find_equivalent_node (graph, rhsvar, rhslabel);
2397 c->lhs.var = lhsvar;
2398 c->rhs.var = rhsvar;
2403 /* Eliminate indirect cycles involving NODE. Return true if NODE was
2404 part of an SCC, false otherwise. */
2407 eliminate_indirect_cycles (unsigned int node)
2409 if (graph->indirect_cycles[node] != -1
2410 && !bitmap_empty_p (get_varinfo (node)->solution))
2413 VEC(unsigned,heap) *queue = NULL;
2415 unsigned int to = find (graph->indirect_cycles[node]);
2418 /* We can't touch the solution set and call unify_nodes
2419 at the same time, because unify_nodes is going to do
2420 bitmap unions into it. */
2422 EXECUTE_IF_SET_IN_BITMAP (get_varinfo (node)->solution, 0, i, bi)
2424 if (find (i) == i && i != to)
2427 VEC_safe_push (unsigned, heap, queue, i);
2432 VEC_iterate (unsigned, queue, queuepos, i);
2435 unify_nodes (graph, to, i, true);
2437 VEC_free (unsigned, heap, queue);
2443 /* Solve the constraint graph GRAPH using our worklist solver.
2444 This is based on the PW* family of solvers from the "Efficient Field
2445 Sensitive Pointer Analysis for C" paper.
2446 It works by iterating over all the graph nodes, processing the complex
2447 constraints and propagating the copy constraints, until everything stops
2448 changed. This corresponds to steps 6-8 in the solving list given above. */
2451 solve_graph (constraint_graph_t graph)
2453 unsigned int size = graph->size;
2458 changed = sbitmap_alloc (size);
2459 sbitmap_zero (changed);
2461 /* Mark all initial non-collapsed nodes as changed. */
2462 for (i = 0; i < size; i++)
2464 varinfo_t ivi = get_varinfo (i);
2465 if (find (i) == i && !bitmap_empty_p (ivi->solution)
2466 && ((graph->succs[i] && !bitmap_empty_p (graph->succs[i]))
2467 || VEC_length (constraint_t, graph->complex[i]) > 0))
2469 SET_BIT (changed, i);
2474 /* Allocate a bitmap to be used to store the changed bits. */
2475 pts = BITMAP_ALLOC (&pta_obstack);
2477 while (changed_count > 0)
2480 struct topo_info *ti = init_topo_info ();
2483 bitmap_obstack_initialize (&iteration_obstack);
2485 compute_topo_order (graph, ti);
2487 while (VEC_length (unsigned, ti->topo_order) != 0)
2490 i = VEC_pop (unsigned, ti->topo_order);
2492 /* If this variable is not a representative, skip it. */
2496 /* In certain indirect cycle cases, we may merge this
2497 variable to another. */
2498 if (eliminate_indirect_cycles (i) && find (i) != i)
2501 /* If the node has changed, we need to process the
2502 complex constraints and outgoing edges again. */
2503 if (TEST_BIT (changed, i))
2508 VEC(constraint_t,heap) *complex = graph->complex[i];
2509 bool solution_empty;
2511 RESET_BIT (changed, i);
2514 /* Compute the changed set of solution bits. */
2515 bitmap_and_compl (pts, get_varinfo (i)->solution,
2516 get_varinfo (i)->oldsolution);
2518 if (bitmap_empty_p (pts))
2521 bitmap_ior_into (get_varinfo (i)->oldsolution, pts);
2523 solution = get_varinfo (i)->solution;
2524 solution_empty = bitmap_empty_p (solution);
2526 /* Process the complex constraints */
2527 for (j = 0; VEC_iterate (constraint_t, complex, j, c); j++)
2529 /* XXX: This is going to unsort the constraints in
2530 some cases, which will occasionally add duplicate
2531 constraints during unification. This does not
2532 affect correctness. */
2533 c->lhs.var = find (c->lhs.var);
2534 c->rhs.var = find (c->rhs.var);
2536 /* The only complex constraint that can change our
2537 solution to non-empty, given an empty solution,
2538 is a constraint where the lhs side is receiving
2539 some set from elsewhere. */
2540 if (!solution_empty || c->lhs.type != DEREF)
2541 do_complex_constraint (graph, c, pts);
2544 solution_empty = bitmap_empty_p (solution);
2546 if (!solution_empty)
2549 unsigned eff_escaped_id = find (escaped_id);
2551 /* Propagate solution to all successors. */
2552 EXECUTE_IF_IN_NONNULL_BITMAP (graph->succs[i],
2558 unsigned int to = find (j);
2559 tmp = get_varinfo (to)->solution;
2562 /* Don't try to propagate to ourselves. */
2566 /* If we propagate from ESCAPED use ESCAPED as
2568 if (i == eff_escaped_id)
2569 flag = bitmap_set_bit (tmp, escaped_id);
2571 flag = set_union_with_increment (tmp, pts, 0);
2575 get_varinfo (to)->solution = tmp;
2576 if (!TEST_BIT (changed, to))
2578 SET_BIT (changed, to);
2586 free_topo_info (ti);
2587 bitmap_obstack_release (&iteration_obstack);
2591 sbitmap_free (changed);
2592 bitmap_obstack_release (&oldpta_obstack);
2595 /* Map from trees to variable infos. */
2596 static struct pointer_map_t *vi_for_tree;
2599 /* Insert ID as the variable id for tree T in the vi_for_tree map. */
2602 insert_vi_for_tree (tree t, varinfo_t vi)
2604 void **slot = pointer_map_insert (vi_for_tree, t);
2606 gcc_assert (*slot == NULL);
2610 /* Find the variable info for tree T in VI_FOR_TREE. If T does not
2611 exist in the map, return NULL, otherwise, return the varinfo we found. */
2614 lookup_vi_for_tree (tree t)
2616 void **slot = pointer_map_contains (vi_for_tree, t);
2620 return (varinfo_t) *slot;
2623 /* Return a printable name for DECL */
2626 alias_get_name (tree decl)
2628 const char *res = get_name (decl);
2630 int num_printed = 0;
2639 if (TREE_CODE (decl) == SSA_NAME)
2641 num_printed = asprintf (&temp, "%s_%u",
2642 alias_get_name (SSA_NAME_VAR (decl)),
2643 SSA_NAME_VERSION (decl));
2645 else if (DECL_P (decl))
2647 num_printed = asprintf (&temp, "D.%u", DECL_UID (decl));
2649 if (num_printed > 0)
2651 res = ggc_strdup (temp);
2657 /* Find the variable id for tree T in the map.
2658 If T doesn't exist in the map, create an entry for it and return it. */
2661 get_vi_for_tree (tree t)
2663 void **slot = pointer_map_contains (vi_for_tree, t);
2665 return get_varinfo (create_variable_info_for (t, alias_get_name (t)));
2667 return (varinfo_t) *slot;
2670 /* Get a scalar constraint expression for a new temporary variable. */
2672 static struct constraint_expr
2673 new_scalar_tmp_constraint_exp (const char *name)
2675 struct constraint_expr tmp;
2678 vi = new_var_info (NULL_TREE, name);
2682 vi->is_full_var = 1;
2691 /* Get a constraint expression vector from an SSA_VAR_P node.
2692 If address_p is true, the result will be taken its address of. */
2695 get_constraint_for_ssa_var (tree t, VEC(ce_s, heap) **results, bool address_p)
2697 struct constraint_expr cexpr;
2700 /* We allow FUNCTION_DECLs here even though it doesn't make much sense. */
2701 gcc_assert (SSA_VAR_P (t) || DECL_P (t));
2703 /* For parameters, get at the points-to set for the actual parm
2705 if (TREE_CODE (t) == SSA_NAME
2706 && TREE_CODE (SSA_NAME_VAR (t)) == PARM_DECL
2707 && SSA_NAME_IS_DEFAULT_DEF (t))
2709 get_constraint_for_ssa_var (SSA_NAME_VAR (t), results, address_p);
2713 vi = get_vi_for_tree (t);
2715 cexpr.type = SCALAR;
2717 /* If we determine the result is "anything", and we know this is readonly,
2718 say it points to readonly memory instead. */
2719 if (cexpr.var == anything_id && TREE_READONLY (t))
2722 cexpr.type = ADDRESSOF;
2723 cexpr.var = readonly_id;
2726 /* If we are not taking the address of the constraint expr, add all
2727 sub-fiels of the variable as well. */
2729 && !vi->is_full_var)
2731 for (; vi; vi = vi->next)
2734 VEC_safe_push (ce_s, heap, *results, &cexpr);
2739 VEC_safe_push (ce_s, heap, *results, &cexpr);
2742 /* Process constraint T, performing various simplifications and then
2743 adding it to our list of overall constraints. */
2746 process_constraint (constraint_t t)
2748 struct constraint_expr rhs = t->rhs;
2749 struct constraint_expr lhs = t->lhs;
2751 gcc_assert (rhs.var < VEC_length (varinfo_t, varmap));
2752 gcc_assert (lhs.var < VEC_length (varinfo_t, varmap));
2754 /* If we didn't get any useful constraint from the lhs we get
2755 &ANYTHING as fallback from get_constraint_for. Deal with
2756 it here by turning it into *ANYTHING. */
2757 if (lhs.type == ADDRESSOF
2758 && lhs.var == anything_id)
2761 /* ADDRESSOF on the lhs is invalid. */
2762 gcc_assert (lhs.type != ADDRESSOF);
2764 /* This can happen in our IR with things like n->a = *p */
2765 if (rhs.type == DEREF && lhs.type == DEREF && rhs.var != anything_id)
2767 /* Split into tmp = *rhs, *lhs = tmp */
2768 struct constraint_expr tmplhs;
2769 tmplhs = new_scalar_tmp_constraint_exp ("doubledereftmp");
2770 process_constraint (new_constraint (tmplhs, rhs));
2771 process_constraint (new_constraint (lhs, tmplhs));
2773 else if (rhs.type == ADDRESSOF && lhs.type == DEREF)
2775 /* Split into tmp = &rhs, *lhs = tmp */
2776 struct constraint_expr tmplhs;
2777 tmplhs = new_scalar_tmp_constraint_exp ("derefaddrtmp");
2778 process_constraint (new_constraint (tmplhs, rhs));
2779 process_constraint (new_constraint (lhs, tmplhs));
2783 gcc_assert (rhs.type != ADDRESSOF || rhs.offset == 0);
2784 VEC_safe_push (constraint_t, heap, constraints, t);
2788 /* Return true if T is a type that could contain pointers. */
2791 type_could_have_pointers (tree type)
2793 if (POINTER_TYPE_P (type))
2796 if (TREE_CODE (type) == ARRAY_TYPE)
2797 return type_could_have_pointers (TREE_TYPE (type));
2799 return AGGREGATE_TYPE_P (type);
2802 /* Return true if T is a variable of a type that could contain
2806 could_have_pointers (tree t)
2808 return type_could_have_pointers (TREE_TYPE (t));
2811 /* Return the position, in bits, of FIELD_DECL from the beginning of its
2814 static HOST_WIDE_INT
2815 bitpos_of_field (const tree fdecl)
2818 if (!host_integerp (DECL_FIELD_OFFSET (fdecl), 0)
2819 || !host_integerp (DECL_FIELD_BIT_OFFSET (fdecl), 0))
2822 return (TREE_INT_CST_LOW (DECL_FIELD_OFFSET (fdecl)) * 8
2823 + TREE_INT_CST_LOW (DECL_FIELD_BIT_OFFSET (fdecl)));
2827 /* Get constraint expressions for offsetting PTR by OFFSET. Stores the
2828 resulting constraint expressions in *RESULTS. */
2831 get_constraint_for_ptr_offset (tree ptr, tree offset,
2832 VEC (ce_s, heap) **results)
2834 struct constraint_expr c;
2836 HOST_WIDE_INT rhsunitoffset, rhsoffset;
2838 /* If we do not do field-sensitive PTA adding offsets to pointers
2839 does not change the points-to solution. */
2840 if (!use_field_sensitive)
2842 get_constraint_for (ptr, results);
2846 /* If the offset is not a non-negative integer constant that fits
2847 in a HOST_WIDE_INT, we have to fall back to a conservative
2848 solution which includes all sub-fields of all pointed-to
2849 variables of ptr. */
2850 if (offset == NULL_TREE
2851 || !host_integerp (offset, 0))
2852 rhsoffset = UNKNOWN_OFFSET;
2855 /* Make sure the bit-offset also fits. */
2856 rhsunitoffset = TREE_INT_CST_LOW (offset);
2857 rhsoffset = rhsunitoffset * BITS_PER_UNIT;
2858 if (rhsunitoffset != rhsoffset / BITS_PER_UNIT)
2859 rhsoffset = UNKNOWN_OFFSET;
2862 get_constraint_for (ptr, results);
2866 /* As we are eventually appending to the solution do not use
2867 VEC_iterate here. */
2868 n = VEC_length (ce_s, *results);
2869 for (j = 0; j < n; j++)
2872 c = *VEC_index (ce_s, *results, j);
2873 curr = get_varinfo (c.var);
2875 if (c.type == ADDRESSOF
2876 /* If this varinfo represents a full variable just use it. */
2877 && curr->is_full_var)
2879 else if (c.type == ADDRESSOF
2880 /* If we do not know the offset add all subfields. */
2881 && rhsoffset == UNKNOWN_OFFSET)
2883 varinfo_t temp = lookup_vi_for_tree (curr->decl);
2886 struct constraint_expr c2;
2888 c2.type = ADDRESSOF;
2890 if (c2.var != c.var)
2891 VEC_safe_push (ce_s, heap, *results, &c2);
2896 else if (c.type == ADDRESSOF)
2899 unsigned HOST_WIDE_INT offset = curr->offset + rhsoffset;
2901 /* Search the sub-field which overlaps with the
2902 pointed-to offset. If the result is outside of the variable
2903 we have to provide a conservative result, as the variable is
2904 still reachable from the resulting pointer (even though it
2905 technically cannot point to anything). The last and first
2906 sub-fields are such conservative results.
2907 ??? If we always had a sub-field for &object + 1 then
2908 we could represent this in a more precise way. */
2910 && curr->offset < offset)
2912 temp = first_or_preceding_vi_for_offset (curr, offset);
2914 /* If the found variable is not exactly at the pointed to
2915 result, we have to include the next variable in the
2916 solution as well. Otherwise two increments by offset / 2
2917 do not result in the same or a conservative superset
2919 if (temp->offset != offset
2920 && temp->next != NULL)
2922 struct constraint_expr c2;
2923 c2.var = temp->next->id;
2924 c2.type = ADDRESSOF;
2926 VEC_safe_push (ce_s, heap, *results, &c2);
2932 c.offset = rhsoffset;
2934 VEC_replace (ce_s, *results, j, &c);
2939 /* Given a COMPONENT_REF T, return the constraint_expr vector for it.
2940 If address_p is true the result will be taken its address of. */
2943 get_constraint_for_component_ref (tree t, VEC(ce_s, heap) **results,
2947 HOST_WIDE_INT bitsize = -1;
2948 HOST_WIDE_INT bitmaxsize = -1;
2949 HOST_WIDE_INT bitpos;
2951 struct constraint_expr *result;
2953 /* Some people like to do cute things like take the address of
2956 while (!SSA_VAR_P (forzero) && !CONSTANT_CLASS_P (forzero))
2957 forzero = TREE_OPERAND (forzero, 0);
2959 if (CONSTANT_CLASS_P (forzero) && integer_zerop (forzero))
2961 struct constraint_expr temp;
2964 temp.var = integer_id;
2966 VEC_safe_push (ce_s, heap, *results, &temp);
2970 t = get_ref_base_and_extent (t, &bitpos, &bitsize, &bitmaxsize);
2972 /* Pretend to take the address of the base, we'll take care of
2973 adding the required subset of sub-fields below. */
2974 get_constraint_for_1 (t, results, true);
2975 gcc_assert (VEC_length (ce_s, *results) == 1);
2976 result = VEC_last (ce_s, *results);
2978 if (result->type == SCALAR
2979 && get_varinfo (result->var)->is_full_var)
2980 /* For single-field vars do not bother about the offset. */
2982 else if (result->type == SCALAR)
2984 /* In languages like C, you can access one past the end of an
2985 array. You aren't allowed to dereference it, so we can
2986 ignore this constraint. When we handle pointer subtraction,
2987 we may have to do something cute here. */
2989 if ((unsigned HOST_WIDE_INT)bitpos < get_varinfo (result->var)->fullsize
2992 /* It's also not true that the constraint will actually start at the
2993 right offset, it may start in some padding. We only care about
2994 setting the constraint to the first actual field it touches, so
2996 struct constraint_expr cexpr = *result;
2998 VEC_pop (ce_s, *results);
3000 for (curr = get_varinfo (cexpr.var); curr; curr = curr->next)
3002 if (ranges_overlap_p (curr->offset, curr->size,
3003 bitpos, bitmaxsize))
3005 cexpr.var = curr->id;
3006 VEC_safe_push (ce_s, heap, *results, &cexpr);
3011 /* If we are going to take the address of this field then
3012 to be able to compute reachability correctly add at least
3013 the last field of the variable. */
3015 && VEC_length (ce_s, *results) == 0)
3017 curr = get_varinfo (cexpr.var);
3018 while (curr->next != NULL)
3020 cexpr.var = curr->id;
3021 VEC_safe_push (ce_s, heap, *results, &cexpr);
3024 /* Assert that we found *some* field there. The user couldn't be
3025 accessing *only* padding. */
3026 /* Still the user could access one past the end of an array
3027 embedded in a struct resulting in accessing *only* padding. */
3028 gcc_assert (VEC_length (ce_s, *results) >= 1
3029 || ref_contains_array_ref (orig_t));
3031 else if (bitmaxsize == 0)
3033 if (dump_file && (dump_flags & TDF_DETAILS))
3034 fprintf (dump_file, "Access to zero-sized part of variable,"
3038 if (dump_file && (dump_flags & TDF_DETAILS))
3039 fprintf (dump_file, "Access to past the end of variable, ignoring\n");
3041 else if (result->type == DEREF)
3043 /* If we do not know exactly where the access goes say so. Note
3044 that only for non-structure accesses we know that we access
3045 at most one subfiled of any variable. */
3047 || bitsize != bitmaxsize
3048 || AGGREGATE_TYPE_P (TREE_TYPE (orig_t)))
3049 result->offset = UNKNOWN_OFFSET;
3051 result->offset = bitpos;
3053 else if (result->type == ADDRESSOF)
3055 /* We can end up here for component references on a
3056 VIEW_CONVERT_EXPR <>(&foobar). */
3057 result->type = SCALAR;
3058 result->var = anything_id;
3066 /* Dereference the constraint expression CONS, and return the result.
3067 DEREF (ADDRESSOF) = SCALAR
3068 DEREF (SCALAR) = DEREF
3069 DEREF (DEREF) = (temp = DEREF1; result = DEREF(temp))
3070 This is needed so that we can handle dereferencing DEREF constraints. */
3073 do_deref (VEC (ce_s, heap) **constraints)
3075 struct constraint_expr *c;
3078 for (i = 0; VEC_iterate (ce_s, *constraints, i, c); i++)
3080 if (c->type == SCALAR)
3082 else if (c->type == ADDRESSOF)
3084 else if (c->type == DEREF)
3086 struct constraint_expr tmplhs;
3087 tmplhs = new_scalar_tmp_constraint_exp ("dereftmp");
3088 process_constraint (new_constraint (tmplhs, *c));
3089 c->var = tmplhs.var;
3096 static void get_constraint_for_1 (tree, VEC (ce_s, heap) **, bool);
3098 /* Given a tree T, return the constraint expression for taking the
3102 get_constraint_for_address_of (tree t, VEC (ce_s, heap) **results)
3104 struct constraint_expr *c;
3107 get_constraint_for_1 (t, results, true);
3109 for (i = 0; VEC_iterate (ce_s, *results, i, c); i++)
3111 if (c->type == DEREF)
3114 c->type = ADDRESSOF;
3118 /* Given a tree T, return the constraint expression for it. */
3121 get_constraint_for_1 (tree t, VEC (ce_s, heap) **results, bool address_p)
3123 struct constraint_expr temp;
3125 /* x = integer is all glommed to a single variable, which doesn't
3126 point to anything by itself. That is, of course, unless it is an
3127 integer constant being treated as a pointer, in which case, we
3128 will return that this is really the addressof anything. This
3129 happens below, since it will fall into the default case. The only
3130 case we know something about an integer treated like a pointer is
3131 when it is the NULL pointer, and then we just say it points to
3134 Do not do that if -fno-delete-null-pointer-checks though, because
3135 in that case *NULL does not fail, so it _should_ alias *anything.
3136 It is not worth adding a new option or renaming the existing one,
3137 since this case is relatively obscure. */
3138 if (flag_delete_null_pointer_checks
3139 && ((TREE_CODE (t) == INTEGER_CST
3140 && integer_zerop (t))
3141 /* The only valid CONSTRUCTORs in gimple with pointer typed
3142 elements are zero-initializer. */
3143 || TREE_CODE (t) == CONSTRUCTOR))
3145 temp.var = nothing_id;
3146 temp.type = ADDRESSOF;
3148 VEC_safe_push (ce_s, heap, *results, &temp);
3152 /* String constants are read-only. */
3153 if (TREE_CODE (t) == STRING_CST)
3155 temp.var = readonly_id;
3158 VEC_safe_push (ce_s, heap, *results, &temp);
3162 switch (TREE_CODE_CLASS (TREE_CODE (t)))
3164 case tcc_expression:
3166 switch (TREE_CODE (t))
3169 get_constraint_for_address_of (TREE_OPERAND (t, 0), results);
3177 switch (TREE_CODE (t))
3181 get_constraint_for_1 (TREE_OPERAND (t, 0), results, address_p);
3186 case ARRAY_RANGE_REF:
3188 get_constraint_for_component_ref (t, results, address_p);
3190 case VIEW_CONVERT_EXPR:
3191 get_constraint_for_1 (TREE_OPERAND (t, 0), results, address_p);
3193 /* We are missing handling for TARGET_MEM_REF here. */
3198 case tcc_exceptional:
3200 switch (TREE_CODE (t))
3204 get_constraint_for_ssa_var (t, results, address_p);
3211 case tcc_declaration:
3213 get_constraint_for_ssa_var (t, results, address_p);
3219 /* The default fallback is a constraint from anything. */
3220 temp.type = ADDRESSOF;
3221 temp.var = anything_id;
3223 VEC_safe_push (ce_s, heap, *results, &temp);
3226 /* Given a gimple tree T, return the constraint expression vector for it. */
3229 get_constraint_for (tree t, VEC (ce_s, heap) **results)
3231 gcc_assert (VEC_length (ce_s, *results) == 0);
3233 get_constraint_for_1 (t, results, false);
3237 /* Efficiently generates constraints from all entries in *RHSC to all
3238 entries in *LHSC. */
3241 process_all_all_constraints (VEC (ce_s, heap) *lhsc, VEC (ce_s, heap) *rhsc)
3243 struct constraint_expr *lhsp, *rhsp;
3246 if (VEC_length (ce_s, lhsc) <= 1
3247 || VEC_length (ce_s, rhsc) <= 1)
3249 for (i = 0; VEC_iterate (ce_s, lhsc, i, lhsp); ++i)
3250 for (j = 0; VEC_iterate (ce_s, rhsc, j, rhsp); ++j)
3251 process_constraint (new_constraint (*lhsp, *rhsp));
3255 struct constraint_expr tmp;
3256 tmp = new_scalar_tmp_constraint_exp ("allalltmp");
3257 for (i = 0; VEC_iterate (ce_s, rhsc, i, rhsp); ++i)
3258 process_constraint (new_constraint (tmp, *rhsp));
3259 for (i = 0; VEC_iterate (ce_s, lhsc, i, lhsp); ++i)
3260 process_constraint (new_constraint (*lhsp, tmp));
3264 /* Handle aggregate copies by expanding into copies of the respective
3265 fields of the structures. */
3268 do_structure_copy (tree lhsop, tree rhsop)
3270 struct constraint_expr *lhsp, *rhsp;
3271 VEC (ce_s, heap) *lhsc = NULL, *rhsc = NULL;
3274 get_constraint_for (lhsop, &lhsc);
3275 get_constraint_for (rhsop, &rhsc);
3276 lhsp = VEC_index (ce_s, lhsc, 0);
3277 rhsp = VEC_index (ce_s, rhsc, 0);
3278 if (lhsp->type == DEREF
3279 || (lhsp->type == ADDRESSOF && lhsp->var == anything_id)
3280 || rhsp->type == DEREF)
3281 process_all_all_constraints (lhsc, rhsc);
3282 else if (lhsp->type == SCALAR
3283 && (rhsp->type == SCALAR
3284 || rhsp->type == ADDRESSOF))
3286 tree lhsbase, rhsbase;
3287 HOST_WIDE_INT lhssize, lhsmaxsize, lhsoffset;
3288 HOST_WIDE_INT rhssize, rhsmaxsize, rhsoffset;
3290 lhsbase = get_ref_base_and_extent (lhsop, &lhsoffset,
3291 &lhssize, &lhsmaxsize);
3292 rhsbase = get_ref_base_and_extent (rhsop, &rhsoffset,
3293 &rhssize, &rhsmaxsize);
3294 for (j = 0; VEC_iterate (ce_s, lhsc, j, lhsp);)
3296 varinfo_t lhsv, rhsv;
3297 rhsp = VEC_index (ce_s, rhsc, k);
3298 lhsv = get_varinfo (lhsp->var);
3299 rhsv = get_varinfo (rhsp->var);
3300 if (lhsv->may_have_pointers
3301 && ranges_overlap_p (lhsv->offset + rhsoffset, lhsv->size,
3302 rhsv->offset + lhsoffset, rhsv->size))
3303 process_constraint (new_constraint (*lhsp, *rhsp));
3304 if (lhsv->offset + rhsoffset + lhsv->size
3305 > rhsv->offset + lhsoffset + rhsv->size)
3308 if (k >= VEC_length (ce_s, rhsc))
3318 VEC_free (ce_s, heap, lhsc);
3319 VEC_free (ce_s, heap, rhsc);
3322 /* Create a constraint ID = OP. */
3325 make_constraint_to (unsigned id, tree op)
3327 VEC(ce_s, heap) *rhsc = NULL;
3328 struct constraint_expr *c;
3329 struct constraint_expr includes;
3333 includes.offset = 0;
3334 includes.type = SCALAR;
3336 get_constraint_for (op, &rhsc);
3337 for (j = 0; VEC_iterate (ce_s, rhsc, j, c); j++)
3338 process_constraint (new_constraint (includes, *c));
3339 VEC_free (ce_s, heap, rhsc);
3342 /* Create a constraint ID = &FROM. */
3345 make_constraint_from (varinfo_t vi, int from)
3347 struct constraint_expr lhs, rhs;
3355 rhs.type = ADDRESSOF;
3356 process_constraint (new_constraint (lhs, rhs));
3359 /* Create a constraint ID = FROM. */
3362 make_copy_constraint (varinfo_t vi, int from)
3364 struct constraint_expr lhs, rhs;
3373 process_constraint (new_constraint (lhs, rhs));
3376 /* Make constraints necessary to make OP escape. */
3379 make_escape_constraint (tree op)
3381 make_constraint_to (escaped_id, op);
3384 /* Create a new artificial heap variable with NAME and make a
3385 constraint from it to LHS. Return the created variable. */
3388 make_constraint_from_heapvar (varinfo_t lhs, const char *name)
3391 tree heapvar = heapvar_lookup (lhs->decl, lhs->offset);
3393 if (heapvar == NULL_TREE)
3396 heapvar = create_tmp_var_raw (ptr_type_node, name);
3397 DECL_EXTERNAL (heapvar) = 1;
3399 heapvar_insert (lhs->decl, lhs->offset, heapvar);
3401 ann = get_var_ann (heapvar);
3402 ann->is_heapvar = 1;
3405 /* For global vars we need to add a heapvar to the list of referenced
3406 vars of a different function than it was created for originally. */
3407 if (gimple_referenced_vars (cfun))
3408 add_referenced_var (heapvar);
3410 vi = new_var_info (heapvar, name);
3411 vi->is_artificial_var = true;
3412 vi->is_heap_var = true;
3413 vi->is_unknown_size_var = true;
3417 vi->is_full_var = true;
3418 insert_vi_for_tree (heapvar, vi);
3420 make_constraint_from (lhs, vi->id);
3425 /* Create a new artificial heap variable with NAME and make a
3426 constraint from it to LHS. Set flags according to a tag used
3427 for tracking restrict pointers. */
3430 make_constraint_from_restrict (varinfo_t lhs, const char *name)
3433 vi = make_constraint_from_heapvar (lhs, name);
3434 vi->is_restrict_var = 1;
3435 vi->is_global_var = 0;
3436 vi->is_special_var = 1;
3437 vi->may_have_pointers = 0;
3440 /* For non-IPA mode, generate constraints necessary for a call on the
3444 handle_rhs_call (gimple stmt, VEC(ce_s, heap) **results)
3446 struct constraint_expr rhsc;
3449 for (i = 0; i < gimple_call_num_args (stmt); ++i)
3451 tree arg = gimple_call_arg (stmt, i);
3453 /* Find those pointers being passed, and make sure they end up
3454 pointing to anything. */
3455 if (could_have_pointers (arg))
3456 make_escape_constraint (arg);
3459 /* The static chain escapes as well. */
3460 if (gimple_call_chain (stmt))
3461 make_escape_constraint (gimple_call_chain (stmt));
3463 /* And if we applied NRV the address of the return slot escapes as well. */
3464 if (gimple_call_return_slot_opt_p (stmt)
3465 && gimple_call_lhs (stmt) != NULL_TREE
3466 && TREE_ADDRESSABLE (TREE_TYPE (gimple_call_lhs (stmt))))
3468 VEC(ce_s, heap) *tmpc = NULL;
3469 struct constraint_expr lhsc, *c;
3470 get_constraint_for_address_of (gimple_call_lhs (stmt), &tmpc);
3471 lhsc.var = escaped_id;
3474 for (i = 0; VEC_iterate (ce_s, tmpc, i, c); ++i)
3475 process_constraint (new_constraint (lhsc, *c));
3476 VEC_free(ce_s, heap, tmpc);
3479 /* Regular functions return nonlocal memory. */
3480 rhsc.var = nonlocal_id;
3483 VEC_safe_push (ce_s, heap, *results, &rhsc);
3486 /* For non-IPA mode, generate constraints necessary for a call
3487 that returns a pointer and assigns it to LHS. This simply makes
3488 the LHS point to global and escaped variables. */
3491 handle_lhs_call (tree lhs, int flags, VEC(ce_s, heap) *rhsc)
3493 VEC(ce_s, heap) *lhsc = NULL;
3495 get_constraint_for (lhs, &lhsc);
3497 if (flags & ECF_MALLOC)
3500 vi = make_constraint_from_heapvar (get_vi_for_tree (lhs), "HEAP");
3501 /* We delay marking allocated storage global until we know if
3503 DECL_EXTERNAL (vi->decl) = 0;
3504 vi->is_global_var = 0;
3506 else if (VEC_length (ce_s, rhsc) > 0)
3508 /* If the store is to a global decl make sure to
3509 add proper escape constraints. */
3510 lhs = get_base_address (lhs);
3513 && is_global_var (lhs))
3515 struct constraint_expr tmpc;
3516 tmpc.var = escaped_id;
3519 VEC_safe_push (ce_s, heap, lhsc, &tmpc);
3521 process_all_all_constraints (lhsc, rhsc);
3523 VEC_free (ce_s, heap, lhsc);
3526 /* For non-IPA mode, generate constraints necessary for a call of a
3527 const function that returns a pointer in the statement STMT. */
3530 handle_const_call (gimple stmt, VEC(ce_s, heap) **results)
3532 struct constraint_expr rhsc;
3535 /* Treat nested const functions the same as pure functions as far
3536 as the static chain is concerned. */
3537 if (gimple_call_chain (stmt))
3539 make_constraint_to (callused_id, gimple_call_chain (stmt));
3540 rhsc.var = callused_id;
3543 VEC_safe_push (ce_s, heap, *results, &rhsc);
3546 /* May return arguments. */
3547 for (k = 0; k < gimple_call_num_args (stmt); ++k)
3549 tree arg = gimple_call_arg (stmt, k);
3551 if (could_have_pointers (arg))
3553 VEC(ce_s, heap) *argc = NULL;
3555 struct constraint_expr *argp;
3556 get_constraint_for (arg, &argc);
3557 for (i = 0; VEC_iterate (ce_s, argc, i, argp); ++i)
3558 VEC_safe_push (ce_s, heap, *results, argp);
3559 VEC_free(ce_s, heap, argc);
3563 /* May return addresses of globals. */
3564 rhsc.var = nonlocal_id;
3566 rhsc.type = ADDRESSOF;
3567 VEC_safe_push (ce_s, heap, *results, &rhsc);
3570 /* For non-IPA mode, generate constraints necessary for a call to a
3571 pure function in statement STMT. */
3574 handle_pure_call (gimple stmt, VEC(ce_s, heap) **results)
3576 struct constraint_expr rhsc;
3578 bool need_callused = false;
3580 /* Memory reached from pointer arguments is call-used. */
3581 for (i = 0; i < gimple_call_num_args (stmt); ++i)
3583 tree arg = gimple_call_arg (stmt, i);
3585 if (could_have_pointers (arg))
3587 make_constraint_to (callused_id, arg);
3588 need_callused = true;
3592 /* The static chain is used as well. */
3593 if (gimple_call_chain (stmt))
3595 make_constraint_to (callused_id, gimple_call_chain (stmt));
3596 need_callused = true;
3599 /* Pure functions may return callused and nonlocal memory. */
3602 rhsc.var = callused_id;
3605 VEC_safe_push (ce_s, heap, *results, &rhsc);
3607 rhsc.var = nonlocal_id;
3610 VEC_safe_push (ce_s, heap, *results, &rhsc);
3613 /* Walk statement T setting up aliasing constraints according to the
3614 references found in T. This function is the main part of the
3615 constraint builder. AI points to auxiliary alias information used
3616 when building alias sets and computing alias grouping heuristics. */
3619 find_func_aliases (gimple origt)
3622 VEC(ce_s, heap) *lhsc = NULL;
3623 VEC(ce_s, heap) *rhsc = NULL;
3624 struct constraint_expr *c;
3626 /* Now build constraints expressions. */
3627 if (gimple_code (t) == GIMPLE_PHI)
3629 gcc_assert (!AGGREGATE_TYPE_P (TREE_TYPE (gimple_phi_result (t))));
3631 /* Only care about pointers and structures containing
3633 if (could_have_pointers (gimple_phi_result (t)))
3638 /* For a phi node, assign all the arguments to
3640 get_constraint_for (gimple_phi_result (t), &lhsc);
3641 for (i = 0; i < gimple_phi_num_args (t); i++)
3644 tree strippedrhs = PHI_ARG_DEF (t, i);
3646 STRIP_NOPS (strippedrhs);
3647 rhstype = TREE_TYPE (strippedrhs);
3648 get_constraint_for (gimple_phi_arg_def (t, i), &rhsc);
3650 for (j = 0; VEC_iterate (ce_s, lhsc, j, c); j++)
3652 struct constraint_expr *c2;
3653 while (VEC_length (ce_s, rhsc) > 0)
3655 c2 = VEC_last (ce_s, rhsc);
3656 process_constraint (new_constraint (*c, *c2));
3657 VEC_pop (ce_s, rhsc);
3663 /* In IPA mode, we need to generate constraints to pass call
3664 arguments through their calls. There are two cases,
3665 either a GIMPLE_CALL returning a value, or just a plain
3666 GIMPLE_CALL when we are not.
3668 In non-ipa mode, we need to generate constraints for each
3669 pointer passed by address. */
3670 else if (is_gimple_call (t))
3672 tree fndecl = gimple_call_fndecl (t);
3673 if (fndecl != NULL_TREE
3674 && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL)
3675 /* ??? All builtins that are handled here need to be handled
3676 in the alias-oracle query functions explicitly! */
3677 switch (DECL_FUNCTION_CODE (fndecl))
3679 /* All the following functions return a pointer to the same object
3680 as their first argument points to. The functions do not add
3681 to the ESCAPED solution. The functions make the first argument
3682 pointed to memory point to what the second argument pointed to
3683 memory points to. */
3684 case BUILT_IN_STRCPY:
3685 case BUILT_IN_STRNCPY:
3686 case BUILT_IN_BCOPY:
3687 case BUILT_IN_MEMCPY:
3688 case BUILT_IN_MEMMOVE:
3689 case BUILT_IN_MEMPCPY:
3690 case BUILT_IN_STPCPY:
3691 case BUILT_IN_STPNCPY:
3692 case BUILT_IN_STRCAT:
3693 case BUILT_IN_STRNCAT:
3695 tree res = gimple_call_lhs (t);
3696 tree dest = gimple_call_arg (t, (DECL_FUNCTION_CODE (fndecl)
3697 == BUILT_IN_BCOPY ? 1 : 0));
3698 tree src = gimple_call_arg (t, (DECL_FUNCTION_CODE (fndecl)
3699 == BUILT_IN_BCOPY ? 0 : 1));
3700 if (res != NULL_TREE)
3702 get_constraint_for (res, &lhsc);
3703 if (DECL_FUNCTION_CODE (fndecl) == BUILT_IN_MEMPCPY
3704 || DECL_FUNCTION_CODE (fndecl) == BUILT_IN_STPCPY
3705 || DECL_FUNCTION_CODE (fndecl) == BUILT_IN_STPNCPY)
3706 get_constraint_for_ptr_offset (dest, NULL_TREE, &rhsc);
3708 get_constraint_for (dest, &rhsc);
3709 process_all_all_constraints (lhsc, rhsc);
3710 VEC_free (ce_s, heap, lhsc);
3711 VEC_free (ce_s, heap, rhsc);
3713 get_constraint_for_ptr_offset (dest, NULL_TREE, &lhsc);
3714 get_constraint_for_ptr_offset (src, NULL_TREE, &rhsc);
3717 process_all_all_constraints (lhsc, rhsc);
3718 VEC_free (ce_s, heap, lhsc);
3719 VEC_free (ce_s, heap, rhsc);
3722 case BUILT_IN_MEMSET:
3724 tree res = gimple_call_lhs (t);
3725 tree dest = gimple_call_arg (t, 0);
3728 struct constraint_expr ac;
3729 if (res != NULL_TREE)
3731 get_constraint_for (res, &lhsc);
3732 get_constraint_for (dest, &rhsc);
3733 process_all_all_constraints (lhsc, rhsc);
3734 VEC_free (ce_s, heap, lhsc);
3735 VEC_free (ce_s, heap, rhsc);
3737 get_constraint_for_ptr_offset (dest, NULL_TREE, &lhsc);
3739 if (flag_delete_null_pointer_checks
3740 && integer_zerop (gimple_call_arg (t, 1)))
3742 ac.type = ADDRESSOF;
3743 ac.var = nothing_id;
3748 ac.var = integer_id;
3751 for (i = 0; VEC_iterate (ce_s, lhsc, i, lhsp); ++i)
3752 process_constraint (new_constraint (*lhsp, ac));
3753 VEC_free (ce_s, heap, lhsc);
3756 /* All the following functions do not return pointers, do not
3757 modify the points-to sets of memory reachable from their
3758 arguments and do not add to the ESCAPED solution. */
3759 case BUILT_IN_SINCOS:
3760 case BUILT_IN_SINCOSF:
3761 case BUILT_IN_SINCOSL:
3762 case BUILT_IN_FREXP:
3763 case BUILT_IN_FREXPF:
3764 case BUILT_IN_FREXPL:
3765 case BUILT_IN_GAMMA_R:
3766 case BUILT_IN_GAMMAF_R:
3767 case BUILT_IN_GAMMAL_R:
3768 case BUILT_IN_LGAMMA_R:
3769 case BUILT_IN_LGAMMAF_R:
3770 case BUILT_IN_LGAMMAL_R:
3772 case BUILT_IN_MODFF:
3773 case BUILT_IN_MODFL:
3774 case BUILT_IN_REMQUO:
3775 case BUILT_IN_REMQUOF:
3776 case BUILT_IN_REMQUOL:
3779 /* printf-style functions may have hooks to set pointers to
3780 point to somewhere into the generated string. Leave them
3781 for a later excercise... */
3783 /* Fallthru to general call handling. */;
3787 && !lookup_vi_for_tree (fndecl)))
3789 VEC(ce_s, heap) *rhsc = NULL;
3790 int flags = gimple_call_flags (t);
3792 /* Const functions can return their arguments and addresses
3793 of global memory but not of escaped memory. */
3794 if (flags & (ECF_CONST|ECF_NOVOPS))
3796 if (gimple_call_lhs (t)
3797 && could_have_pointers (gimple_call_lhs (t)))
3798 handle_const_call (t, &rhsc);
3800 /* Pure functions can return addresses in and of memory
3801 reachable from their arguments, but they are not an escape
3802 point for reachable memory of their arguments. */
3803 else if (flags & (ECF_PURE|ECF_LOOPING_CONST_OR_PURE))
3804 handle_pure_call (t, &rhsc);
3806 handle_rhs_call (t, &rhsc);
3807 if (gimple_call_lhs (t)
3808 && could_have_pointers (gimple_call_lhs (t)))
3809 handle_lhs_call (gimple_call_lhs (t), flags, rhsc);
3810 VEC_free (ce_s, heap, rhsc);
3820 lhsop = gimple_call_lhs (t);
3821 decl = gimple_call_fndecl (t);
3823 /* If we can directly resolve the function being called, do so.
3824 Otherwise, it must be some sort of indirect expression that
3825 we should still be able to handle. */
3827 fi = get_vi_for_tree (decl);
3830 decl = gimple_call_fn (t);
3831 fi = get_vi_for_tree (decl);
3834 /* Assign all the passed arguments to the appropriate incoming
3835 parameters of the function. */
3836 for (j = 0; j < gimple_call_num_args (t); j++)
3838 struct constraint_expr lhs ;
3839 struct constraint_expr *rhsp;
3840 tree arg = gimple_call_arg (t, j);
3842 get_constraint_for (arg, &rhsc);
3843 if (TREE_CODE (decl) != FUNCTION_DECL)
3852 lhs.var = first_vi_for_offset (fi, i)->id;
3855 while (VEC_length (ce_s, rhsc) != 0)
3857 rhsp = VEC_last (ce_s, rhsc);
3858 process_constraint (new_constraint (lhs, *rhsp));
3859 VEC_pop (ce_s, rhsc);
3864 /* If we are returning a value, assign it to the result. */
3867 struct constraint_expr rhs;
3868 struct constraint_expr *lhsp;
3871 get_constraint_for (lhsop, &lhsc);
3872 if (TREE_CODE (decl) != FUNCTION_DECL)
3881 rhs.var = first_vi_for_offset (fi, i)->id;
3884 for (j = 0; VEC_iterate (ce_s, lhsc, j, lhsp); j++)
3885 process_constraint (new_constraint (*lhsp, rhs));
3889 /* Otherwise, just a regular assignment statement. Only care about
3890 operations with pointer result, others are dealt with as escape
3891 points if they have pointer operands. */
3892 else if (is_gimple_assign (t)
3893 && could_have_pointers (gimple_assign_lhs (t)))
3895 /* Otherwise, just a regular assignment statement. */
3896 tree lhsop = gimple_assign_lhs (t);
3897 tree rhsop = (gimple_num_ops (t) == 2) ? gimple_assign_rhs1 (t) : NULL;
3899 if (rhsop && AGGREGATE_TYPE_P (TREE_TYPE (lhsop)))
3900 do_structure_copy (lhsop, rhsop);
3903 struct constraint_expr temp;
3904 get_constraint_for (lhsop, &lhsc);
3906 if (gimple_assign_rhs_code (t) == POINTER_PLUS_EXPR)
3907 get_constraint_for_ptr_offset (gimple_assign_rhs1 (t),
3908 gimple_assign_rhs2 (t), &rhsc);
3909 else if ((CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (t))
3910 && !(POINTER_TYPE_P (gimple_expr_type (t))
3911 && !POINTER_TYPE_P (TREE_TYPE (rhsop))))
3912 || gimple_assign_single_p (t))
3913 get_constraint_for (rhsop, &rhsc);
3916 temp.type = ADDRESSOF;
3917 temp.var = anything_id;
3919 VEC_safe_push (ce_s, heap, rhsc, &temp);
3921 process_all_all_constraints (lhsc, rhsc);
3923 /* If there is a store to a global variable the rhs escapes. */
3924 if ((lhsop = get_base_address (lhsop)) != NULL_TREE
3926 && is_global_var (lhsop))
3927 make_escape_constraint (rhsop);
3928 /* If this is a conversion of a non-restrict pointer to a
3929 restrict pointer track it with a new heapvar. */
3930 else if (gimple_assign_cast_p (t)
3931 && POINTER_TYPE_P (TREE_TYPE (rhsop))
3932 && POINTER_TYPE_P (TREE_TYPE (lhsop))
3933 && !TYPE_RESTRICT (TREE_TYPE (rhsop))
3934 && TYPE_RESTRICT (TREE_TYPE (lhsop)))
3935 make_constraint_from_restrict (get_vi_for_tree (lhsop),
3938 /* For conversions of pointers to non-pointers the pointer escapes. */
3939 else if (gimple_assign_cast_p (t)
3940 && POINTER_TYPE_P (TREE_TYPE (gimple_assign_rhs1 (t)))
3941 && !POINTER_TYPE_P (TREE_TYPE (gimple_assign_lhs (t))))
3943 make_escape_constraint (gimple_assign_rhs1 (t));
3945 /* Handle escapes through return. */
3946 else if (gimple_code (t) == GIMPLE_RETURN
3947 && gimple_return_retval (t) != NULL_TREE
3948 && could_have_pointers (gimple_return_retval (t)))
3950 make_escape_constraint (gimple_return_retval (t));
3952 /* Handle asms conservatively by adding escape constraints to everything. */
3953 else if (gimple_code (t) == GIMPLE_ASM)
3955 unsigned i, noutputs;
3956 const char **oconstraints;
3957 const char *constraint;
3958 bool allows_mem, allows_reg, is_inout;
3960 noutputs = gimple_asm_noutputs (t);
3961 oconstraints = XALLOCAVEC (const char *, noutputs);
3963 for (i = 0; i < noutputs; ++i)
3965 tree link = gimple_asm_output_op (t, i);
3966 tree op = TREE_VALUE (link);
3968 constraint = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (link)));
3969 oconstraints[i] = constraint;
3970 parse_output_constraint (&constraint, i, 0, 0, &allows_mem,
3971 &allows_reg, &is_inout);
3973 /* A memory constraint makes the address of the operand escape. */
3974 if (!allows_reg && allows_mem)
3975 make_escape_constraint (build_fold_addr_expr (op));
3977 /* The asm may read global memory, so outputs may point to
3978 any global memory. */
3979 if (op && could_have_pointers (op))
3981 VEC(ce_s, heap) *lhsc = NULL;
3982 struct constraint_expr rhsc, *lhsp;
3984 get_constraint_for (op, &lhsc);
3985 rhsc.var = nonlocal_id;
3988 for (j = 0; VEC_iterate (ce_s, lhsc, j, lhsp); j++)
3989 process_constraint (new_constraint (*lhsp, rhsc));
3990 VEC_free (ce_s, heap, lhsc);
3993 for (i = 0; i < gimple_asm_ninputs (t); ++i)
3995 tree link = gimple_asm_input_op (t, i);
3996 tree op = TREE_VALUE (link);
3998 constraint = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (link)));
4000 parse_input_constraint (&constraint, 0, 0, noutputs, 0, oconstraints,
4001 &allows_mem, &allows_reg);
4003 /* A memory constraint makes the address of the operand escape. */
4004 if (!allows_reg && allows_mem)
4005 make_escape_constraint (build_fold_addr_expr (op));
4006 /* Strictly we'd only need the constraint to ESCAPED if
4007 the asm clobbers memory, otherwise using CALLUSED
4009 else if (op && could_have_pointers (op))
4010 make_escape_constraint (op);
4014 VEC_free (ce_s, heap, rhsc);
4015 VEC_free (ce_s, heap, lhsc);
4019 /* Find the first varinfo in the same variable as START that overlaps with
4020 OFFSET. Return NULL if we can't find one. */
4023 first_vi_for_offset (varinfo_t start, unsigned HOST_WIDE_INT offset)
4025 /* If the offset is outside of the variable, bail out. */
4026 if (offset >= start->fullsize)
4029 /* If we cannot reach offset from start, lookup the first field
4030 and start from there. */
4031 if (start->offset > offset)
4032 start = lookup_vi_for_tree (start->decl);
4036 /* We may not find a variable in the field list with the actual
4037 offset when when we have glommed a structure to a variable.
4038 In that case, however, offset should still be within the size
4040 if (offset >= start->offset
4041 && (offset - start->offset) < start->size)
4050 /* Find the first varinfo in the same variable as START that overlaps with
4051 OFFSET. If there is no such varinfo the varinfo directly preceding
4052 OFFSET is returned. */
4055 first_or_preceding_vi_for_offset (varinfo_t start,
4056 unsigned HOST_WIDE_INT offset)
4058 /* If we cannot reach offset from start, lookup the first field
4059 and start from there. */
4060 if (start->offset > offset)
4061 start = lookup_vi_for_tree (start->decl);
4063 /* We may not find a variable in the field list with the actual
4064 offset when when we have glommed a structure to a variable.
4065 In that case, however, offset should still be within the size
4067 If we got beyond the offset we look for return the field
4068 directly preceding offset which may be the last field. */
4070 && offset >= start->offset
4071 && !((offset - start->offset) < start->size))
4072 start = start->next;
4078 /* Insert the varinfo FIELD into the field list for BASE, at the front
4082 insert_into_field_list (varinfo_t base, varinfo_t field)
4084 varinfo_t prev = base;
4085 varinfo_t curr = base->next;
4091 /* Insert the varinfo FIELD into the field list for BASE, ordered by
4095 insert_into_field_list_sorted (varinfo_t base, varinfo_t field)
4097 varinfo_t prev = base;
4098 varinfo_t curr = base->next;
4109 if (field->offset <= curr->offset)
4114 field->next = prev->next;
4119 /* This structure is used during pushing fields onto the fieldstack
4120 to track the offset of the field, since bitpos_of_field gives it
4121 relative to its immediate containing type, and we want it relative
4122 to the ultimate containing object. */
4126 /* Offset from the base of the base containing object to this field. */
4127 HOST_WIDE_INT offset;
4129 /* Size, in bits, of the field. */
4130 unsigned HOST_WIDE_INT size;
4132 unsigned has_unknown_size : 1;
4134 unsigned may_have_pointers : 1;
4136 unsigned only_restrict_pointers : 1;
4138 typedef struct fieldoff fieldoff_s;
4140 DEF_VEC_O(fieldoff_s);
4141 DEF_VEC_ALLOC_O(fieldoff_s,heap);
4143 /* qsort comparison function for two fieldoff's PA and PB */
4146 fieldoff_compare (const void *pa, const void *pb)
4148 const fieldoff_s *foa = (const fieldoff_s *)pa;
4149 const fieldoff_s *fob = (const fieldoff_s *)pb;
4150 unsigned HOST_WIDE_INT foasize, fobsize;
4152 if (foa->offset < fob->offset)
4154 else if (foa->offset > fob->offset)
4157 foasize = foa->size;
4158 fobsize = fob->size;
4159 if (foasize < fobsize)
4161 else if (foasize > fobsize)
4166 /* Sort a fieldstack according to the field offset and sizes. */
4168 sort_fieldstack (VEC(fieldoff_s,heap) *fieldstack)
4170 qsort (VEC_address (fieldoff_s, fieldstack),
4171 VEC_length (fieldoff_s, fieldstack),
4172 sizeof (fieldoff_s),
4176 /* Return true if V is a tree that we can have subvars for.
4177 Normally, this is any aggregate type. Also complex
4178 types which are not gimple registers can have subvars. */
4181 var_can_have_subvars (const_tree v)
4183 /* Volatile variables should never have subvars. */
4184 if (TREE_THIS_VOLATILE (v))
4187 /* Non decls or memory tags can never have subvars. */
4191 /* Aggregates without overlapping fields can have subvars. */
4192 if (TREE_CODE (TREE_TYPE (v)) == RECORD_TYPE)
4198 /* Given a TYPE, and a vector of field offsets FIELDSTACK, push all
4199 the fields of TYPE onto fieldstack, recording their offsets along
4202 OFFSET is used to keep track of the offset in this entire
4203 structure, rather than just the immediately containing structure.
4204 Returns the number of fields pushed. */
4207 push_fields_onto_fieldstack (tree type, VEC(fieldoff_s,heap) **fieldstack,
4208 HOST_WIDE_INT offset)
4213 if (TREE_CODE (type) != RECORD_TYPE)
4216 /* If the vector of fields is growing too big, bail out early.
4217 Callers check for VEC_length <= MAX_FIELDS_FOR_FIELD_SENSITIVE, make
4219 if (VEC_length (fieldoff_s, *fieldstack) > MAX_FIELDS_FOR_FIELD_SENSITIVE)
4222 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
4223 if (TREE_CODE (field) == FIELD_DECL)
4227 HOST_WIDE_INT foff = bitpos_of_field (field);
4229 if (!var_can_have_subvars (field)
4230 || TREE_CODE (TREE_TYPE (field)) == QUAL_UNION_TYPE
4231 || TREE_CODE (TREE_TYPE (field)) == UNION_TYPE)
4233 else if (!(pushed = push_fields_onto_fieldstack
4234 (TREE_TYPE (field), fieldstack, offset + foff))
4235 && (DECL_SIZE (field)
4236 && !integer_zerop (DECL_SIZE (field))))
4237 /* Empty structures may have actual size, like in C++. So
4238 see if we didn't push any subfields and the size is
4239 nonzero, push the field onto the stack. */
4244 fieldoff_s *pair = NULL;
4245 bool has_unknown_size = false;
4247 if (!VEC_empty (fieldoff_s, *fieldstack))
4248 pair = VEC_last (fieldoff_s, *fieldstack);
4250 if (!DECL_SIZE (field)
4251 || !host_integerp (DECL_SIZE (field), 1))
4252 has_unknown_size = true;
4254 /* If adjacent fields do not contain pointers merge them. */
4256 && !pair->may_have_pointers
4257 && !could_have_pointers (field)
4258 && !pair->has_unknown_size
4259 && !has_unknown_size
4260 && pair->offset + (HOST_WIDE_INT)pair->size == offset + foff)
4262 pair = VEC_last (fieldoff_s, *fieldstack);
4263 pair->size += TREE_INT_CST_LOW (DECL_SIZE (field));
4267 pair = VEC_safe_push (fieldoff_s, heap, *fieldstack, NULL);
4268 pair->offset = offset + foff;
4269 pair->has_unknown_size = has_unknown_size;
4270 if (!has_unknown_size)
4271 pair->size = TREE_INT_CST_LOW (DECL_SIZE (field));
4274 pair->may_have_pointers = could_have_pointers (field);
4275 pair->only_restrict_pointers
4276 = (!has_unknown_size
4277 && POINTER_TYPE_P (TREE_TYPE (field))
4278 && TYPE_RESTRICT (TREE_TYPE (field)));
4289 /* Count the number of arguments DECL has, and set IS_VARARGS to true
4290 if it is a varargs function. */
4293 count_num_arguments (tree decl, bool *is_varargs)
4295 unsigned int num = 0;
4298 /* Capture named arguments for K&R functions. They do not
4299 have a prototype and thus no TYPE_ARG_TYPES. */
4300 for (t = DECL_ARGUMENTS (decl); t; t = TREE_CHAIN (t))
4303 /* Check if the function has variadic arguments. */
4304 for (t = TYPE_ARG_TYPES (TREE_TYPE (decl)); t; t = TREE_CHAIN (t))
4305 if (TREE_VALUE (t) == void_type_node)
4313 /* Creation function node for DECL, using NAME, and return the index
4314 of the variable we've created for the function. */
4317 create_function_info_for (tree decl, const char *name)
4322 bool is_varargs = false;
4324 /* Create the variable info. */
4326 vi = new_var_info (decl, name);
4329 vi->fullsize = count_num_arguments (decl, &is_varargs) + 1;
4330 insert_vi_for_tree (vi->decl, vi);
4334 /* If it's varargs, we don't know how many arguments it has, so we
4340 vi->is_unknown_size_var = true;
4344 arg = DECL_ARGUMENTS (decl);
4346 /* Set up variables for each argument. */
4347 for (i = 1; i < vi->fullsize; i++)
4350 const char *newname;
4352 tree argdecl = decl;
4357 asprintf (&tempname, "%s.arg%d", name, i-1);
4358 newname = ggc_strdup (tempname);
4361 argvi = new_var_info (argdecl, newname);
4364 argvi->is_full_var = true;
4365 argvi->fullsize = vi->fullsize;
4366 insert_into_field_list_sorted (vi, argvi);
4367 stats.total_vars ++;
4370 insert_vi_for_tree (arg, argvi);
4371 arg = TREE_CHAIN (arg);
4375 /* Create a variable for the return var. */
4376 if (DECL_RESULT (decl) != NULL
4377 || !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (decl))))
4380 const char *newname;
4382 tree resultdecl = decl;
4386 if (DECL_RESULT (decl))
4387 resultdecl = DECL_RESULT (decl);
4389 asprintf (&tempname, "%s.result", name);
4390 newname = ggc_strdup (tempname);
4393 resultvi = new_var_info (resultdecl, newname);
4394 resultvi->offset = i;
4396 resultvi->fullsize = vi->fullsize;
4397 resultvi->is_full_var = true;
4398 insert_into_field_list_sorted (vi, resultvi);
4399 stats.total_vars ++;
4400 if (DECL_RESULT (decl))
4401 insert_vi_for_tree (DECL_RESULT (decl), resultvi);
4408 /* Return true if FIELDSTACK contains fields that overlap.
4409 FIELDSTACK is assumed to be sorted by offset. */
4412 check_for_overlaps (VEC (fieldoff_s,heap) *fieldstack)
4414 fieldoff_s *fo = NULL;
4416 HOST_WIDE_INT lastoffset = -1;
4418 for (i = 0; VEC_iterate (fieldoff_s, fieldstack, i, fo); i++)
4420 if (fo->offset == lastoffset)
4422 lastoffset = fo->offset;
4427 /* Create a varinfo structure for NAME and DECL, and add it to VARMAP.
4428 This will also create any varinfo structures necessary for fields
4432 create_variable_info_for (tree decl, const char *name)
4435 tree decl_type = TREE_TYPE (decl);
4436 tree declsize = DECL_P (decl) ? DECL_SIZE (decl) : TYPE_SIZE (decl_type);
4437 VEC (fieldoff_s,heap) *fieldstack = NULL;
4439 if (var_can_have_subvars (decl) && use_field_sensitive)
4440 push_fields_onto_fieldstack (decl_type, &fieldstack, 0);
4442 /* If the variable doesn't have subvars, we may end up needing to
4443 sort the field list and create fake variables for all the
4445 vi = new_var_info (decl, name);
4447 vi->may_have_pointers = could_have_pointers (decl);
4449 || !host_integerp (declsize, 1))
4451 vi->is_unknown_size_var = true;
4457 vi->fullsize = TREE_INT_CST_LOW (declsize);
4458 vi->size = vi->fullsize;
4461 insert_vi_for_tree (vi->decl, vi);
4462 if (vi->is_global_var
4463 && (!flag_whole_program || !in_ipa_mode)
4464 && vi->may_have_pointers)
4466 if (POINTER_TYPE_P (TREE_TYPE (decl))
4467 && TYPE_RESTRICT (TREE_TYPE (decl)))
4468 make_constraint_from_restrict (vi, "GLOBAL_RESTRICT");
4469 make_copy_constraint (vi, nonlocal_id);
4473 if (use_field_sensitive
4474 && !vi->is_unknown_size_var
4475 && var_can_have_subvars (decl)
4476 && VEC_length (fieldoff_s, fieldstack) > 1
4477 && VEC_length (fieldoff_s, fieldstack) <= MAX_FIELDS_FOR_FIELD_SENSITIVE)
4479 fieldoff_s *fo = NULL;
4480 bool notokay = false;
4483 for (i = 0; !notokay && VEC_iterate (fieldoff_s, fieldstack, i, fo); i++)
4485 if (fo->has_unknown_size
4493 /* We can't sort them if we have a field with a variable sized type,
4494 which will make notokay = true. In that case, we are going to return
4495 without creating varinfos for the fields anyway, so sorting them is a
4499 sort_fieldstack (fieldstack);
4500 /* Due to some C++ FE issues, like PR 22488, we might end up
4501 what appear to be overlapping fields even though they,
4502 in reality, do not overlap. Until the C++ FE is fixed,
4503 we will simply disable field-sensitivity for these cases. */
4504 notokay = check_for_overlaps (fieldstack);
4508 if (VEC_length (fieldoff_s, fieldstack) != 0)
4509 fo = VEC_index (fieldoff_s, fieldstack, 0);
4511 if (fo == NULL || notokay)
4513 vi->is_unknown_size_var = 1;
4516 vi->is_full_var = true;
4517 VEC_free (fieldoff_s, heap, fieldstack);
4521 vi->size = fo->size;
4522 vi->offset = fo->offset;
4523 vi->may_have_pointers = fo->may_have_pointers;
4524 if (vi->is_global_var
4525 && (!flag_whole_program || !in_ipa_mode)
4526 && vi->may_have_pointers)
4528 if (fo->only_restrict_pointers)
4529 make_constraint_from_restrict (vi, "GLOBAL_RESTRICT");
4531 for (i = VEC_length (fieldoff_s, fieldstack) - 1;
4532 i >= 1 && VEC_iterate (fieldoff_s, fieldstack, i, fo);
4536 const char *newname = "NULL";
4541 asprintf (&tempname, "%s." HOST_WIDE_INT_PRINT_DEC
4542 "+" HOST_WIDE_INT_PRINT_DEC,
4543 vi->name, fo->offset, fo->size);
4544 newname = ggc_strdup (tempname);
4547 newvi = new_var_info (decl, newname);
4548 newvi->offset = fo->offset;
4549 newvi->size = fo->size;
4550 newvi->fullsize = vi->fullsize;
4551 newvi->may_have_pointers = fo->may_have_pointers;
4552 insert_into_field_list (vi, newvi);
4553 if ((newvi->is_global_var || TREE_CODE (decl) == PARM_DECL)
4554 && newvi->may_have_pointers)
4556 if (fo->only_restrict_pointers)
4557 make_constraint_from_restrict (newvi, "GLOBAL_RESTRICT");
4558 if (newvi->is_global_var && !in_ipa_mode)
4559 make_copy_constraint (newvi, nonlocal_id);
4566 vi->is_full_var = true;
4568 VEC_free (fieldoff_s, heap, fieldstack);
4573 /* Print out the points-to solution for VAR to FILE. */
4576 dump_solution_for_var (FILE *file, unsigned int var)
4578 varinfo_t vi = get_varinfo (var);
4582 if (find (var) != var)
4584 varinfo_t vipt = get_varinfo (find (var));
4585 fprintf (file, "%s = same as %s\n", vi->name, vipt->name);
4589 fprintf (file, "%s = { ", vi->name);
4590 EXECUTE_IF_SET_IN_BITMAP (vi->solution, 0, i, bi)
4592 fprintf (file, "%s ", get_varinfo (i)->name);
4594 fprintf (file, "}\n");
4598 /* Print the points-to solution for VAR to stdout. */
4601 debug_solution_for_var (unsigned int var)
4603 dump_solution_for_var (stdout, var);
4606 /* Create varinfo structures for all of the variables in the
4607 function for intraprocedural mode. */
4610 intra_create_variable_infos (void)
4614 /* For each incoming pointer argument arg, create the constraint ARG
4615 = NONLOCAL or a dummy variable if flag_argument_noalias is set. */
4616 for (t = DECL_ARGUMENTS (current_function_decl); t; t = TREE_CHAIN (t))
4620 if (!could_have_pointers (t))
4623 /* For restrict qualified pointers to objects passed by
4624 reference build a real representative for the pointed-to object. */
4625 if (DECL_BY_REFERENCE (t)
4626 && POINTER_TYPE_P (TREE_TYPE (t))
4627 && TYPE_RESTRICT (TREE_TYPE (t)))
4629 struct constraint_expr lhsc, rhsc;
4631 tree heapvar = heapvar_lookup (t, 0);
4632 if (heapvar == NULL_TREE)
4635 heapvar = create_tmp_var_raw (TREE_TYPE (TREE_TYPE (t)),
4637 DECL_EXTERNAL (heapvar) = 1;
4638 heapvar_insert (t, 0, heapvar);
4639 ann = get_var_ann (heapvar);
4640 ann->is_heapvar = 1;
4642 if (gimple_referenced_vars (cfun))
4643 add_referenced_var (heapvar);
4644 lhsc.var = get_vi_for_tree (t)->id;
4647 rhsc.var = (vi = get_vi_for_tree (heapvar))->id;
4648 rhsc.type = ADDRESSOF;
4650 process_constraint (new_constraint (lhsc, rhsc));
4651 vi->is_restrict_var = 1;
4655 for (p = get_vi_for_tree (t); p; p = p->next)
4656 if (p->may_have_pointers)
4657 make_constraint_from (p, nonlocal_id);
4658 if (POINTER_TYPE_P (TREE_TYPE (t))
4659 && TYPE_RESTRICT (TREE_TYPE (t)))
4660 make_constraint_from_restrict (get_vi_for_tree (t), "PARM_RESTRICT");
4663 /* Add a constraint for a result decl that is passed by reference. */
4664 if (DECL_RESULT (cfun->decl)
4665 && DECL_BY_REFERENCE (DECL_RESULT (cfun->decl)))
4667 varinfo_t p, result_vi = get_vi_for_tree (DECL_RESULT (cfun->decl));
4669 for (p = result_vi; p; p = p->next)
4670 make_constraint_from (p, nonlocal_id);
4673 /* Add a constraint for the incoming static chain parameter. */
4674 if (cfun->static_chain_decl != NULL_TREE)
4676 varinfo_t p, chain_vi = get_vi_for_tree (cfun->static_chain_decl);
4678 for (p = chain_vi; p; p = p->next)
4679 make_constraint_from (p, nonlocal_id);
4683 /* Structure used to put solution bitmaps in a hashtable so they can
4684 be shared among variables with the same points-to set. */
4686 typedef struct shared_bitmap_info
4690 } *shared_bitmap_info_t;
4691 typedef const struct shared_bitmap_info *const_shared_bitmap_info_t;
4693 static htab_t shared_bitmap_table;
4695 /* Hash function for a shared_bitmap_info_t */
4698 shared_bitmap_hash (const void *p)
4700 const_shared_bitmap_info_t const bi = (const_shared_bitmap_info_t) p;
4701 return bi->hashcode;
4704 /* Equality function for two shared_bitmap_info_t's. */
4707 shared_bitmap_eq (const void *p1, const void *p2)
4709 const_shared_bitmap_info_t const sbi1 = (const_shared_bitmap_info_t) p1;
4710 const_shared_bitmap_info_t const sbi2 = (const_shared_bitmap_info_t) p2;
4711 return bitmap_equal_p (sbi1->pt_vars, sbi2->pt_vars);
4714 /* Lookup a bitmap in the shared bitmap hashtable, and return an already
4715 existing instance if there is one, NULL otherwise. */
4718 shared_bitmap_lookup (bitmap pt_vars)
4721 struct shared_bitmap_info sbi;
4723 sbi.pt_vars = pt_vars;
4724 sbi.hashcode = bitmap_hash (pt_vars);
4726 slot = htab_find_slot_with_hash (shared_bitmap_table, &sbi,
4727 sbi.hashcode, NO_INSERT);
4731 return ((shared_bitmap_info_t) *slot)->pt_vars;
4735 /* Add a bitmap to the shared bitmap hashtable. */
4738 shared_bitmap_add (bitmap pt_vars)
4741 shared_bitmap_info_t sbi = XNEW (struct shared_bitmap_info);
4743 sbi->pt_vars = pt_vars;
4744 sbi->hashcode = bitmap_hash (pt_vars);
4746 slot = htab_find_slot_with_hash (shared_bitmap_table, sbi,
4747 sbi->hashcode, INSERT);
4748 gcc_assert (!*slot);
4749 *slot = (void *) sbi;
4753 /* Set bits in INTO corresponding to the variable uids in solution set FROM. */
4756 set_uids_in_ptset (bitmap into, bitmap from, struct pt_solution *pt)
4761 EXECUTE_IF_SET_IN_BITMAP (from, 0, i, bi)
4763 varinfo_t vi = get_varinfo (i);
4765 /* The only artificial variables that are allowed in a may-alias
4766 set are heap variables. */
4767 if (vi->is_artificial_var && !vi->is_heap_var)
4770 if (TREE_CODE (vi->decl) == VAR_DECL
4771 || TREE_CODE (vi->decl) == PARM_DECL
4772 || TREE_CODE (vi->decl) == RESULT_DECL)
4774 /* Add the decl to the points-to set. Note that the points-to
4775 set contains global variables. */
4776 bitmap_set_bit (into, DECL_UID (vi->decl));
4777 if (vi->is_global_var)
4778 pt->vars_contains_global = true;
4784 /* Compute the points-to solution *PT for the variable VI. */
4787 find_what_var_points_to (varinfo_t vi, struct pt_solution *pt)
4791 bitmap finished_solution;
4794 memset (pt, 0, sizeof (struct pt_solution));
4796 /* This variable may have been collapsed, let's get the real
4798 vi = get_varinfo (find (vi->id));
4800 /* Translate artificial variables into SSA_NAME_PTR_INFO
4802 EXECUTE_IF_SET_IN_BITMAP (vi->solution, 0, i, bi)
4804 varinfo_t vi = get_varinfo (i);
4806 if (vi->is_artificial_var)
4808 if (vi->id == nothing_id)
4810 else if (vi->id == escaped_id)
4812 else if (vi->id == callused_id)
4814 else if (vi->id == nonlocal_id)
4816 else if (vi->is_heap_var)
4817 /* We represent heapvars in the points-to set properly. */
4819 else if (vi->id == readonly_id)
4822 else if (vi->id == anything_id
4823 || vi->id == integer_id)
4826 if (vi->is_restrict_var)
4827 pt->vars_contains_restrict = true;
4830 /* Instead of doing extra work, simply do not create
4831 elaborate points-to information for pt_anything pointers. */
4833 && (vi->is_artificial_var
4834 || !pt->vars_contains_restrict))
4837 /* Share the final set of variables when possible. */
4838 finished_solution = BITMAP_GGC_ALLOC ();
4839 stats.points_to_sets_created++;
4841 set_uids_in_ptset (finished_solution, vi->solution, pt);
4842 result = shared_bitmap_lookup (finished_solution);
4845 shared_bitmap_add (finished_solution);
4846 pt->vars = finished_solution;
4851 bitmap_clear (finished_solution);
4855 /* Given a pointer variable P, fill in its points-to set. */
4858 find_what_p_points_to (tree p)
4860 struct ptr_info_def *pi;
4864 /* For parameters, get at the points-to set for the actual parm
4866 if (TREE_CODE (p) == SSA_NAME
4867 && TREE_CODE (SSA_NAME_VAR (p)) == PARM_DECL
4868 && SSA_NAME_IS_DEFAULT_DEF (p))
4869 lookup_p = SSA_NAME_VAR (p);
4871 vi = lookup_vi_for_tree (lookup_p);
4875 pi = get_ptr_info (p);
4876 find_what_var_points_to (vi, &pi->pt);
4880 /* Query statistics for points-to solutions. */
4883 unsigned HOST_WIDE_INT pt_solution_includes_may_alias;
4884 unsigned HOST_WIDE_INT pt_solution_includes_no_alias;
4885 unsigned HOST_WIDE_INT pt_solutions_intersect_may_alias;
4886 unsigned HOST_WIDE_INT pt_solutions_intersect_no_alias;
4890 dump_pta_stats (FILE *s)
4892 fprintf (s, "\nPTA query stats:\n");
4893 fprintf (s, " pt_solution_includes: "
4894 HOST_WIDE_INT_PRINT_DEC" disambiguations, "
4895 HOST_WIDE_INT_PRINT_DEC" queries\n",
4896 pta_stats.pt_solution_includes_no_alias,
4897 pta_stats.pt_solution_includes_no_alias
4898 + pta_stats.pt_solution_includes_may_alias);
4899 fprintf (s, " pt_solutions_intersect: "
4900 HOST_WIDE_INT_PRINT_DEC" disambiguations, "
4901 HOST_WIDE_INT_PRINT_DEC" queries\n",
4902 pta_stats.pt_solutions_intersect_no_alias,
4903 pta_stats.pt_solutions_intersect_no_alias
4904 + pta_stats.pt_solutions_intersect_may_alias);
4908 /* Reset the points-to solution *PT to a conservative default
4909 (point to anything). */
4912 pt_solution_reset (struct pt_solution *pt)
4914 memset (pt, 0, sizeof (struct pt_solution));
4915 pt->anything = true;
4918 /* Set the points-to solution *PT to point only to the variables
4922 pt_solution_set (struct pt_solution *pt, bitmap vars)
4927 memset (pt, 0, sizeof (struct pt_solution));
4929 EXECUTE_IF_SET_IN_BITMAP (vars, 0, i, bi)
4931 tree var = referenced_var_lookup (i);
4932 if (is_global_var (var))
4934 pt->vars_contains_global = true;
4940 /* Return true if the points-to solution *PT is empty. */
4943 pt_solution_empty_p (struct pt_solution *pt)
4950 && !bitmap_empty_p (pt->vars))
4953 /* If the solution includes ESCAPED, check if that is empty. */
4955 && !pt_solution_empty_p (&cfun->gimple_df->escaped))
4961 /* Return true if the points-to solution *PT includes global memory. */
4964 pt_solution_includes_global (struct pt_solution *pt)
4968 || pt->vars_contains_global)
4972 return pt_solution_includes_global (&cfun->gimple_df->escaped);
4977 /* Return true if the points-to solution *PT includes the variable
4978 declaration DECL. */
4981 pt_solution_includes_1 (struct pt_solution *pt, const_tree decl)
4987 && is_global_var (decl))
4991 && bitmap_bit_p (pt->vars, DECL_UID (decl)))
4994 /* If the solution includes ESCAPED, check it. */
4996 && pt_solution_includes_1 (&cfun->gimple_df->escaped, decl))
5003 pt_solution_includes (struct pt_solution *pt, const_tree decl)
5005 bool res = pt_solution_includes_1 (pt, decl);
5007 ++pta_stats.pt_solution_includes_may_alias;
5009 ++pta_stats.pt_solution_includes_no_alias;
5013 /* Return true if both points-to solutions PT1 and PT2 have a non-empty
5017 pt_solutions_intersect_1 (struct pt_solution *pt1, struct pt_solution *pt2)
5019 if (pt1->anything || pt2->anything)
5022 /* If either points to unknown global memory and the other points to
5023 any global memory they alias. */
5026 || pt2->vars_contains_global))
5028 && pt1->vars_contains_global))
5031 /* Check the escaped solution if required. */
5032 if ((pt1->escaped || pt2->escaped)
5033 && !pt_solution_empty_p (&cfun->gimple_df->escaped))
5035 /* If both point to escaped memory and that solution
5036 is not empty they alias. */
5037 if (pt1->escaped && pt2->escaped)
5040 /* If either points to escaped memory see if the escaped solution
5041 intersects with the other. */
5043 && pt_solutions_intersect_1 (&cfun->gimple_df->escaped, pt2))
5045 && pt_solutions_intersect_1 (&cfun->gimple_df->escaped, pt1)))
5049 /* Now both pointers alias if their points-to solution intersects. */
5052 && bitmap_intersect_p (pt1->vars, pt2->vars));
5056 pt_solutions_intersect (struct pt_solution *pt1, struct pt_solution *pt2)
5058 bool res = pt_solutions_intersect_1 (pt1, pt2);
5060 ++pta_stats.pt_solutions_intersect_may_alias;
5062 ++pta_stats.pt_solutions_intersect_no_alias;
5066 /* Return true if both points-to solutions PT1 and PT2 for two restrict
5067 qualified pointers are possibly based on the same pointer. */
5070 pt_solutions_same_restrict_base (struct pt_solution *pt1,
5071 struct pt_solution *pt2)
5073 /* If we deal with points-to solutions of two restrict qualified
5074 pointers solely rely on the pointed-to variable bitmap intersection.
5075 For two pointers that are based on each other the bitmaps will
5077 if (pt1->vars_contains_restrict
5078 && pt2->vars_contains_restrict)
5080 gcc_assert (pt1->vars && pt2->vars);
5081 return bitmap_intersect_p (pt1->vars, pt2->vars);
5088 /* Dump points-to information to OUTFILE. */
5091 dump_sa_points_to_info (FILE *outfile)
5095 fprintf (outfile, "\nPoints-to sets\n\n");
5097 if (dump_flags & TDF_STATS)
5099 fprintf (outfile, "Stats:\n");
5100 fprintf (outfile, "Total vars: %d\n", stats.total_vars);
5101 fprintf (outfile, "Non-pointer vars: %d\n",
5102 stats.nonpointer_vars);
5103 fprintf (outfile, "Statically unified vars: %d\n",
5104 stats.unified_vars_static);
5105 fprintf (outfile, "Dynamically unified vars: %d\n",
5106 stats.unified_vars_dynamic);
5107 fprintf (outfile, "Iterations: %d\n", stats.iterations);
5108 fprintf (outfile, "Number of edges: %d\n", stats.num_edges);
5109 fprintf (outfile, "Number of implicit edges: %d\n",
5110 stats.num_implicit_edges);
5113 for (i = 0; i < VEC_length (varinfo_t, varmap); i++)
5114 dump_solution_for_var (outfile, i);
5118 /* Debug points-to information to stderr. */
5121 debug_sa_points_to_info (void)
5123 dump_sa_points_to_info (stderr);
5127 /* Initialize the always-existing constraint variables for NULL
5128 ANYTHING, READONLY, and INTEGER */
5131 init_base_vars (void)
5133 struct constraint_expr lhs, rhs;
5134 varinfo_t var_anything;
5135 varinfo_t var_nothing;
5136 varinfo_t var_readonly;
5137 varinfo_t var_escaped;
5138 varinfo_t var_nonlocal;
5139 varinfo_t var_callused;
5140 varinfo_t var_storedanything;
5141 varinfo_t var_integer;
5143 /* Create the NULL variable, used to represent that a variable points
5145 var_nothing = new_var_info (NULL_TREE, "NULL");
5146 gcc_assert (var_nothing->id == nothing_id);
5147 var_nothing->is_artificial_var = 1;
5148 var_nothing->offset = 0;
5149 var_nothing->size = ~0;
5150 var_nothing->fullsize = ~0;
5151 var_nothing->is_special_var = 1;
5153 /* Create the ANYTHING variable, used to represent that a variable
5154 points to some unknown piece of memory. */
5155 var_anything = new_var_info (NULL_TREE, "ANYTHING");
5156 gcc_assert (var_anything->id == anything_id);
5157 var_anything->is_artificial_var = 1;
5158 var_anything->size = ~0;
5159 var_anything->offset = 0;
5160 var_anything->next = NULL;
5161 var_anything->fullsize = ~0;
5162 var_anything->is_special_var = 1;
5164 /* Anything points to anything. This makes deref constraints just
5165 work in the presence of linked list and other p = *p type loops,
5166 by saying that *ANYTHING = ANYTHING. */
5168 lhs.var = anything_id;
5170 rhs.type = ADDRESSOF;
5171 rhs.var = anything_id;
5174 /* This specifically does not use process_constraint because
5175 process_constraint ignores all anything = anything constraints, since all
5176 but this one are redundant. */
5177 VEC_safe_push (constraint_t, heap, constraints, new_constraint (lhs, rhs));
5179 /* Create the READONLY variable, used to represent that a variable
5180 points to readonly memory. */
5181 var_readonly = new_var_info (NULL_TREE, "READONLY");
5182 gcc_assert (var_readonly->id == readonly_id);
5183 var_readonly->is_artificial_var = 1;
5184 var_readonly->offset = 0;
5185 var_readonly->size = ~0;
5186 var_readonly->fullsize = ~0;
5187 var_readonly->next = NULL;
5188 var_readonly->is_special_var = 1;
5190 /* readonly memory points to anything, in order to make deref
5191 easier. In reality, it points to anything the particular
5192 readonly variable can point to, but we don't track this
5195 lhs.var = readonly_id;
5197 rhs.type = ADDRESSOF;
5198 rhs.var = readonly_id; /* FIXME */
5200 process_constraint (new_constraint (lhs, rhs));
5202 /* Create the ESCAPED variable, used to represent the set of escaped
5204 var_escaped = new_var_info (NULL_TREE, "ESCAPED");
5205 gcc_assert (var_escaped->id == escaped_id);
5206 var_escaped->is_artificial_var = 1;
5207 var_escaped->offset = 0;
5208 var_escaped->size = ~0;
5209 var_escaped->fullsize = ~0;
5210 var_escaped->is_special_var = 0;
5212 /* Create the NONLOCAL variable, used to represent the set of nonlocal
5214 var_nonlocal = new_var_info (NULL_TREE, "NONLOCAL");
5215 gcc_assert (var_nonlocal->id == nonlocal_id);
5216 var_nonlocal->is_artificial_var = 1;
5217 var_nonlocal->offset = 0;
5218 var_nonlocal->size = ~0;
5219 var_nonlocal->fullsize = ~0;
5220 var_nonlocal->is_special_var = 1;
5222 /* ESCAPED = *ESCAPED, because escaped is may-deref'd at calls, etc. */
5224 lhs.var = escaped_id;
5227 rhs.var = escaped_id;
5229 process_constraint (new_constraint (lhs, rhs));
5231 /* ESCAPED = ESCAPED + UNKNOWN_OFFSET, because if a sub-field escapes the
5232 whole variable escapes. */
5234 lhs.var = escaped_id;
5237 rhs.var = escaped_id;
5238 rhs.offset = UNKNOWN_OFFSET;
5239 process_constraint (new_constraint (lhs, rhs));
5241 /* *ESCAPED = NONLOCAL. This is true because we have to assume
5242 everything pointed to by escaped points to what global memory can
5245 lhs.var = escaped_id;
5248 rhs.var = nonlocal_id;
5250 process_constraint (new_constraint (lhs, rhs));
5252 /* NONLOCAL = &NONLOCAL, NONLOCAL = &ESCAPED. This is true because
5253 global memory may point to global memory and escaped memory. */
5255 lhs.var = nonlocal_id;
5257 rhs.type = ADDRESSOF;
5258 rhs.var = nonlocal_id;
5260 process_constraint (new_constraint (lhs, rhs));
5261 rhs.type = ADDRESSOF;
5262 rhs.var = escaped_id;
5264 process_constraint (new_constraint (lhs, rhs));
5266 /* Create the CALLUSED variable, used to represent the set of call-used
5268 var_callused = new_var_info (NULL_TREE, "CALLUSED");
5269 gcc_assert (var_callused->id == callused_id);
5270 var_callused->is_artificial_var = 1;
5271 var_callused->offset = 0;
5272 var_callused->size = ~0;
5273 var_callused->fullsize = ~0;
5274 var_callused->is_special_var = 0;
5276 /* CALLUSED = *CALLUSED, because call-used is may-deref'd at calls, etc. */
5278 lhs.var = callused_id;
5281 rhs.var = callused_id;
5283 process_constraint (new_constraint (lhs, rhs));
5285 /* CALLUSED = CALLUSED + UNKNOWN, because if a sub-field is call-used the
5286 whole variable is call-used. */
5288 lhs.var = callused_id;
5291 rhs.var = callused_id;
5292 rhs.offset = UNKNOWN_OFFSET;
5293 process_constraint (new_constraint (lhs, rhs));
5295 /* Create the STOREDANYTHING variable, used to represent the set of
5296 variables stored to *ANYTHING. */
5297 var_storedanything = new_var_info (NULL_TREE, "STOREDANYTHING");
5298 gcc_assert (var_storedanything->id == storedanything_id);
5299 var_storedanything->is_artificial_var = 1;
5300 var_storedanything->offset = 0;
5301 var_storedanything->size = ~0;
5302 var_storedanything->fullsize = ~0;
5303 var_storedanything->is_special_var = 0;
5305 /* Create the INTEGER variable, used to represent that a variable points
5306 to what an INTEGER "points to". */
5307 var_integer = new_var_info (NULL_TREE, "INTEGER");
5308 gcc_assert (var_integer->id == integer_id);
5309 var_integer->is_artificial_var = 1;
5310 var_integer->size = ~0;
5311 var_integer->fullsize = ~0;
5312 var_integer->offset = 0;
5313 var_integer->next = NULL;
5314 var_integer->is_special_var = 1;
5316 /* INTEGER = ANYTHING, because we don't know where a dereference of
5317 a random integer will point to. */
5319 lhs.var = integer_id;
5321 rhs.type = ADDRESSOF;
5322 rhs.var = anything_id;
5324 process_constraint (new_constraint (lhs, rhs));
5327 /* Initialize things necessary to perform PTA */
5330 init_alias_vars (void)
5332 use_field_sensitive = (MAX_FIELDS_FOR_FIELD_SENSITIVE > 1);
5334 bitmap_obstack_initialize (&pta_obstack);
5335 bitmap_obstack_initialize (&oldpta_obstack);
5336 bitmap_obstack_initialize (&predbitmap_obstack);
5338 constraint_pool = create_alloc_pool ("Constraint pool",
5339 sizeof (struct constraint), 30);
5340 variable_info_pool = create_alloc_pool ("Variable info pool",
5341 sizeof (struct variable_info), 30);
5342 constraints = VEC_alloc (constraint_t, heap, 8);
5343 varmap = VEC_alloc (varinfo_t, heap, 8);
5344 vi_for_tree = pointer_map_create ();
5346 memset (&stats, 0, sizeof (stats));
5347 shared_bitmap_table = htab_create (511, shared_bitmap_hash,
5348 shared_bitmap_eq, free);
5352 /* Remove the REF and ADDRESS edges from GRAPH, as well as all the
5353 predecessor edges. */
5356 remove_preds_and_fake_succs (constraint_graph_t graph)
5360 /* Clear the implicit ref and address nodes from the successor
5362 for (i = 0; i < FIRST_REF_NODE; i++)
5364 if (graph->succs[i])
5365 bitmap_clear_range (graph->succs[i], FIRST_REF_NODE,
5366 FIRST_REF_NODE * 2);
5369 /* Free the successor list for the non-ref nodes. */
5370 for (i = FIRST_REF_NODE; i < graph->size; i++)
5372 if (graph->succs[i])
5373 BITMAP_FREE (graph->succs[i]);
5376 /* Now reallocate the size of the successor list as, and blow away
5377 the predecessor bitmaps. */
5378 graph->size = VEC_length (varinfo_t, varmap);
5379 graph->succs = XRESIZEVEC (bitmap, graph->succs, graph->size);
5381 free (graph->implicit_preds);
5382 graph->implicit_preds = NULL;
5383 free (graph->preds);
5384 graph->preds = NULL;
5385 bitmap_obstack_release (&predbitmap_obstack);
5388 /* Initialize the heapvar for statement mapping. */
5391 init_alias_heapvars (void)
5393 if (!heapvar_for_stmt)
5394 heapvar_for_stmt = htab_create_ggc (11, tree_map_hash, heapvar_map_eq,
5398 /* Delete the heapvar for statement mapping. */
5401 delete_alias_heapvars (void)
5403 if (heapvar_for_stmt)
5404 htab_delete (heapvar_for_stmt);
5405 heapvar_for_stmt = NULL;
5408 /* Solve the constraint set. */
5411 solve_constraints (void)
5413 struct scc_info *si;
5417 fprintf (dump_file, "Points-to analysis\n\nConstraints:\n\n");
5418 dump_constraints (dump_file);
5423 "\nCollapsing static cycles and doing variable "
5426 init_graph (VEC_length (varinfo_t, varmap) * 2);
5429 fprintf (dump_file, "Building predecessor graph\n");
5430 build_pred_graph ();
5433 fprintf (dump_file, "Detecting pointer and location "
5435 si = perform_var_substitution (graph);
5438 fprintf (dump_file, "Rewriting constraints and unifying "
5440 rewrite_constraints (graph, si);
5442 build_succ_graph ();
5443 free_var_substitution_info (si);
5445 if (dump_file && (dump_flags & TDF_GRAPH))
5446 dump_constraint_graph (dump_file);
5448 move_complex_constraints (graph);
5451 fprintf (dump_file, "Uniting pointer but not location equivalent "
5453 unite_pointer_equivalences (graph);
5456 fprintf (dump_file, "Finding indirect cycles\n");
5457 find_indirect_cycles (graph);
5459 /* Implicit nodes and predecessors are no longer necessary at this
5461 remove_preds_and_fake_succs (graph);
5464 fprintf (dump_file, "Solving graph\n");
5466 solve_graph (graph);
5469 dump_sa_points_to_info (dump_file);
5472 /* Create points-to sets for the current function. See the comments
5473 at the start of the file for an algorithmic overview. */
5476 compute_points_to_sets (void)
5482 timevar_push (TV_TREE_PTA);
5485 init_alias_heapvars ();
5487 intra_create_variable_infos ();
5489 /* Now walk all statements and derive aliases. */
5492 gimple_stmt_iterator gsi;
5494 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
5496 gimple phi = gsi_stmt (gsi);
5498 if (is_gimple_reg (gimple_phi_result (phi)))
5499 find_func_aliases (phi);
5502 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
5504 gimple stmt = gsi_stmt (gsi);
5506 find_func_aliases (stmt);
5510 /* From the constraints compute the points-to sets. */
5511 solve_constraints ();
5513 /* Compute the points-to sets for ESCAPED and CALLUSED used for
5514 call-clobber analysis. */
5515 find_what_var_points_to (get_varinfo (escaped_id),
5516 &cfun->gimple_df->escaped);
5517 find_what_var_points_to (get_varinfo (callused_id),
5518 &cfun->gimple_df->callused);
5520 /* Make sure the ESCAPED solution (which is used as placeholder in
5521 other solutions) does not reference itself. This simplifies
5522 points-to solution queries. */
5523 cfun->gimple_df->escaped.escaped = 0;
5525 /* Mark escaped HEAP variables as global. */
5526 for (i = 0; VEC_iterate (varinfo_t, varmap, i, vi); ++i)
5528 && !vi->is_restrict_var
5529 && !vi->is_global_var)
5530 DECL_EXTERNAL (vi->decl) = vi->is_global_var
5531 = pt_solution_includes (&cfun->gimple_df->escaped, vi->decl);
5533 /* Compute the points-to sets for pointer SSA_NAMEs. */
5534 for (i = 0; i < num_ssa_names; ++i)
5536 tree ptr = ssa_name (i);
5538 && POINTER_TYPE_P (TREE_TYPE (ptr)))
5539 find_what_p_points_to (ptr);
5542 timevar_pop (TV_TREE_PTA);
5546 /* Delete created points-to sets. */
5549 delete_points_to_sets (void)
5553 htab_delete (shared_bitmap_table);
5554 if (dump_file && (dump_flags & TDF_STATS))
5555 fprintf (dump_file, "Points to sets created:%d\n",
5556 stats.points_to_sets_created);
5558 pointer_map_destroy (vi_for_tree);
5559 bitmap_obstack_release (&pta_obstack);
5560 VEC_free (constraint_t, heap, constraints);
5562 for (i = 0; i < graph->size; i++)
5563 VEC_free (constraint_t, heap, graph->complex[i]);
5564 free (graph->complex);
5567 free (graph->succs);
5569 free (graph->pe_rep);
5570 free (graph->indirect_cycles);
5573 VEC_free (varinfo_t, heap, varmap);
5574 free_alloc_pool (variable_info_pool);
5575 free_alloc_pool (constraint_pool);
5579 /* Compute points-to information for every SSA_NAME pointer in the
5580 current function and compute the transitive closure of escaped
5581 variables to re-initialize the call-clobber states of local variables. */
5584 compute_may_aliases (void)
5586 /* For each pointer P_i, determine the sets of variables that P_i may
5587 point-to. Compute the reachability set of escaped and call-used
5589 compute_points_to_sets ();
5591 /* Debugging dumps. */
5594 dump_alias_info (dump_file);
5596 if (dump_flags & TDF_DETAILS)
5597 dump_referenced_vars (dump_file);
5600 /* Deallocate memory used by aliasing data structures and the internal
5601 points-to solution. */
5602 delete_points_to_sets ();
5604 gcc_assert (!need_ssa_update_p (cfun));
5610 gate_tree_pta (void)
5612 return flag_tree_pta;
5615 /* A dummy pass to cause points-to information to be computed via
5616 TODO_rebuild_alias. */
5618 struct gimple_opt_pass pass_build_alias =
5623 gate_tree_pta, /* gate */
5627 0, /* static_pass_number */
5628 TV_NONE, /* tv_id */
5629 PROP_cfg | PROP_ssa, /* properties_required */
5630 0, /* properties_provided */
5631 0, /* properties_destroyed */
5632 0, /* todo_flags_start */
5633 TODO_rebuild_alias | TODO_dump_func /* todo_flags_finish */
5637 /* A dummy pass to cause points-to information to be computed via
5638 TODO_rebuild_alias. */
5640 struct gimple_opt_pass pass_build_ealias =
5644 "ealias", /* name */
5645 gate_tree_pta, /* gate */
5649 0, /* static_pass_number */
5650 TV_NONE, /* tv_id */
5651 PROP_cfg | PROP_ssa, /* properties_required */
5652 0, /* properties_provided */
5653 0, /* properties_destroyed */
5654 0, /* todo_flags_start */
5655 TODO_rebuild_alias | TODO_dump_func /* todo_flags_finish */
5660 /* Return true if we should execute IPA PTA. */
5666 /* Don't bother doing anything if the program has errors. */
5667 && !(errorcount || sorrycount));
5670 /* Execute the driver for IPA PTA. */
5672 ipa_pta_execute (void)
5674 struct cgraph_node *node;
5678 init_alias_heapvars ();
5681 /* Build the constraints. */
5682 for (node = cgraph_nodes; node; node = node->next)
5686 /* Nodes without a body are not interesting. Especially do not
5687 visit clones at this point for now - we get duplicate decls
5688 there for inline clones at least. */
5689 if (!gimple_has_body_p (node->decl)
5693 /* It does not make sense to have graph edges into or out of
5694 externally visible functions. There is no extra information
5695 we can gather from them. */
5696 if (node->local.externally_visible)
5699 varid = create_function_info_for (node->decl,
5700 cgraph_node_name (node));
5703 for (node = cgraph_nodes; node; node = node->next)
5705 struct function *func;
5709 /* Nodes without a body are not interesting. */
5710 if (!gimple_has_body_p (node->decl)
5716 "Generating constraints for %s\n",
5717 cgraph_node_name (node));
5719 func = DECL_STRUCT_FUNCTION (node->decl);
5720 old_func_decl = current_function_decl;
5722 current_function_decl = node->decl;
5724 /* For externally visible functions use local constraints for
5725 their arguments. For local functions we see all callers
5726 and thus do not need initial constraints for parameters. */
5727 if (node->local.externally_visible)
5728 intra_create_variable_infos ();
5730 /* Build constriants for the function body. */
5731 FOR_EACH_BB_FN (bb, func)
5733 gimple_stmt_iterator gsi;
5735 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi);
5738 gimple phi = gsi_stmt (gsi);
5740 if (is_gimple_reg (gimple_phi_result (phi)))
5741 find_func_aliases (phi);
5744 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
5746 gimple stmt = gsi_stmt (gsi);
5748 find_func_aliases (stmt);
5752 current_function_decl = old_func_decl;
5756 /* From the constraints compute the points-to sets. */
5757 solve_constraints ();
5759 delete_points_to_sets ();
5766 struct simple_ipa_opt_pass pass_ipa_pta =
5771 gate_ipa_pta, /* gate */
5772 ipa_pta_execute, /* execute */
5775 0, /* static_pass_number */
5776 TV_IPA_PTA, /* tv_id */
5777 0, /* properties_required */
5778 0, /* properties_provided */
5779 0, /* properties_destroyed */
5780 0, /* todo_flags_start */
5781 TODO_update_ssa /* todo_flags_finish */
5786 #include "gt-tree-ssa-structalias.h"