1 /* Tree based points-to analysis
2 Copyright (C) 2005, 2006, 2007 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 "diagnostic.h"
38 #include "tree-flow.h"
39 #include "tree-inline.h"
42 #include "tree-gimple.h"
46 #include "tree-pass.h"
48 #include "alloc-pool.h"
49 #include "splay-tree.h"
51 #include "tree-ssa-structalias.h"
54 #include "pointer-set.h"
56 /* The idea behind this analyzer is to generate set constraints from the
57 program, then solve the resulting constraints in order to generate the
60 Set constraints are a way of modeling program analysis problems that
61 involve sets. They consist of an inclusion constraint language,
62 describing the variables (each variable is a set) and operations that
63 are involved on the variables, and a set of rules that derive facts
64 from these operations. To solve a system of set constraints, you derive
65 all possible facts under the rules, which gives you the correct sets
68 See "Efficient Field-sensitive pointer analysis for C" by "David
69 J. Pearce and Paul H. J. Kelly and Chris Hankin, at
70 http://citeseer.ist.psu.edu/pearce04efficient.html
72 Also see "Ultra-fast Aliasing Analysis using CLA: A Million Lines
73 of C Code in a Second" by ""Nevin Heintze and Olivier Tardieu" at
74 http://citeseer.ist.psu.edu/heintze01ultrafast.html
76 There are three types of real constraint expressions, DEREF,
77 ADDRESSOF, and SCALAR. Each constraint expression consists
78 of a constraint type, a variable, and an offset.
80 SCALAR is a constraint expression type used to represent x, whether
81 it appears on the LHS or the RHS of a statement.
82 DEREF is a constraint expression type used to represent *x, whether
83 it appears on the LHS or the RHS of a statement.
84 ADDRESSOF is a constraint expression used to represent &x, whether
85 it appears on the LHS or the RHS of a statement.
87 Each pointer variable in the program is assigned an integer id, and
88 each field of a structure variable is assigned an integer id as well.
90 Structure variables are linked to their list of fields through a "next
91 field" in each variable that points to the next field in offset
93 Each variable for a structure field has
95 1. "size", that tells the size in bits of that field.
96 2. "fullsize, that tells the size in bits of the entire structure.
97 3. "offset", that tells the offset in bits from the beginning of the
98 structure to this field.
110 foo.a -> id 1, size 32, offset 0, fullsize 64, next foo.b
111 foo.b -> id 2, size 32, offset 32, fullsize 64, next NULL
112 bar -> id 3, size 32, offset 0, fullsize 32, next NULL
115 In order to solve the system of set constraints, the following is
118 1. Each constraint variable x has a solution set associated with it,
121 2. Constraints are separated into direct, copy, and complex.
122 Direct constraints are ADDRESSOF constraints that require no extra
123 processing, such as P = &Q
124 Copy constraints are those of the form P = Q.
125 Complex constraints are all the constraints involving dereferences
126 and offsets (including offsetted copies).
128 3. All direct constraints of the form P = &Q are processed, such
129 that Q is added to Sol(P)
131 4. All complex constraints for a given constraint variable are stored in a
132 linked list attached to that variable's node.
134 5. A directed graph is built out of the copy constraints. Each
135 constraint variable is a node in the graph, and an edge from
136 Q to P is added for each copy constraint of the form P = Q
138 6. The graph is then walked, and solution sets are
139 propagated along the copy edges, such that an edge from Q to P
140 causes Sol(P) <- Sol(P) union Sol(Q).
142 7. As we visit each node, all complex constraints associated with
143 that node are processed by adding appropriate copy edges to the graph, or the
144 appropriate variables to the solution set.
146 8. The process of walking the graph is iterated until no solution
149 Prior to walking the graph in steps 6 and 7, We perform static
150 cycle elimination on the constraint graph, as well
151 as off-line variable substitution.
153 TODO: Adding offsets to pointer-to-structures can be handled (IE not punted
154 on and turned into anything), but isn't. You can just see what offset
155 inside the pointed-to struct it's going to access.
157 TODO: Constant bounded arrays can be handled as if they were structs of the
158 same number of elements.
160 TODO: Modeling heap and incoming pointers becomes much better if we
161 add fields to them as we discover them, which we could do.
163 TODO: We could handle unions, but to be honest, it's probably not
164 worth the pain or slowdown. */
166 static GTY ((if_marked ("tree_map_marked_p"), param_is (struct tree_map)))
167 htab_t heapvar_for_stmt;
169 static bool use_field_sensitive = true;
170 static int in_ipa_mode = 0;
172 /* Used for predecessor bitmaps. */
173 static bitmap_obstack predbitmap_obstack;
175 /* Used for points-to sets. */
176 static bitmap_obstack pta_obstack;
178 /* Used for oldsolution members of variables. */
179 static bitmap_obstack oldpta_obstack;
181 /* Used for per-solver-iteration bitmaps. */
182 static bitmap_obstack iteration_obstack;
184 static unsigned int create_variable_info_for (tree, const char *);
185 typedef struct constraint_graph *constraint_graph_t;
186 static void unify_nodes (constraint_graph_t, unsigned int, unsigned int, bool);
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 /* Name of this variable */
215 /* Tree that this variable is associated with. */
218 /* Offset of this variable, in bits, from the base variable */
219 unsigned HOST_WIDE_INT offset;
221 /* Size of the variable, in bits. */
222 unsigned HOST_WIDE_INT size;
224 /* Full size of the base variable, in bits. */
225 unsigned HOST_WIDE_INT fullsize;
227 /* A link to the variable for the next field in this structure. */
228 struct variable_info *next;
230 /* True if the variable is directly the target of a dereference.
231 This is used to track which variables are *actually* dereferenced
232 so we can prune their points to listed. */
233 unsigned int directly_dereferenced:1;
235 /* True if this is a variable created by the constraint analysis, such as
236 heap variables and constraints we had to break up. */
237 unsigned int is_artificial_var:1;
239 /* True if this is a special variable whose solution set should not be
241 unsigned int is_special_var:1;
243 /* True for variables whose size is not known or variable. */
244 unsigned int is_unknown_size_var:1;
246 /* True for variables that have unions somewhere in them. */
247 unsigned int has_union:1;
249 /* True if this is a heap variable. */
250 unsigned int is_heap_var:1;
252 /* True if we may not use TBAA to prune references to this
253 variable. This is used for C++ placement new. */
254 unsigned int no_tbaa_pruning : 1;
256 /* Points-to set for this variable. */
259 /* Old points-to set for this variable. */
262 /* Variable id this was collapsed to due to type unsafety. This
263 should be unused completely after build_succ_graph, or something
265 struct variable_info *collapsed_to;
267 typedef struct variable_info *varinfo_t;
269 static varinfo_t first_vi_for_offset (varinfo_t, unsigned HOST_WIDE_INT);
271 /* Pool of variable info structures. */
272 static alloc_pool variable_info_pool;
274 DEF_VEC_P(varinfo_t);
276 DEF_VEC_ALLOC_P(varinfo_t, heap);
278 /* Table of variable info structures for constraint variables.
279 Indexed directly by variable info id. */
280 static VEC(varinfo_t,heap) *varmap;
282 /* Return the varmap element N */
284 static inline varinfo_t
285 get_varinfo (unsigned int n)
287 return VEC_index (varinfo_t, varmap, n);
290 /* Return the varmap element N, following the collapsed_to link. */
292 static inline varinfo_t
293 get_varinfo_fc (unsigned int n)
295 varinfo_t v = VEC_index (varinfo_t, varmap, n);
298 return v->collapsed_to;
302 /* Variable that represents the unknown pointer. */
303 static varinfo_t var_anything;
304 static tree anything_tree;
305 static unsigned int anything_id;
307 /* Variable that represents the NULL pointer. */
308 static varinfo_t var_nothing;
309 static tree nothing_tree;
310 static unsigned int nothing_id;
312 /* Variable that represents read only memory. */
313 static varinfo_t var_readonly;
314 static tree readonly_tree;
315 static unsigned int readonly_id;
317 /* Variable that represents integers. This is used for when people do things
319 static varinfo_t var_integer;
320 static tree integer_tree;
321 static unsigned int integer_id;
323 /* Lookup a heap var for FROM, and return it if we find one. */
326 heapvar_lookup (tree from)
328 struct tree_map *h, in;
331 h = (struct tree_map *) htab_find_with_hash (heapvar_for_stmt, &in,
332 htab_hash_pointer (from));
338 /* Insert a mapping FROM->TO in the heap var for statement
342 heapvar_insert (tree from, tree to)
347 h = GGC_NEW (struct tree_map);
348 h->hash = htab_hash_pointer (from);
351 loc = htab_find_slot_with_hash (heapvar_for_stmt, h, h->hash, INSERT);
352 *(struct tree_map **) loc = h;
355 /* Return a new variable info structure consisting for a variable
356 named NAME, and using constraint graph node NODE. */
359 new_var_info (tree t, unsigned int id, const char *name)
361 varinfo_t ret = (varinfo_t) pool_alloc (variable_info_pool);
367 ret->directly_dereferenced = false;
368 ret->is_artificial_var = false;
369 ret->is_heap_var = false;
370 ret->is_special_var = false;
371 ret->is_unknown_size_var = false;
372 ret->has_union = false;
374 if (TREE_CODE (var) == SSA_NAME)
375 var = SSA_NAME_VAR (var);
376 ret->no_tbaa_pruning = (DECL_P (var)
377 && POINTER_TYPE_P (TREE_TYPE (var))
378 && DECL_NO_TBAA_P (var));
379 ret->solution = BITMAP_ALLOC (&pta_obstack);
380 ret->oldsolution = BITMAP_ALLOC (&oldpta_obstack);
382 ret->collapsed_to = NULL;
386 typedef enum {SCALAR, DEREF, ADDRESSOF} constraint_expr_type;
388 /* An expression that appears in a constraint. */
390 struct constraint_expr
392 /* Constraint type. */
393 constraint_expr_type type;
395 /* Variable we are referring to in the constraint. */
398 /* Offset, in bits, of this constraint from the beginning of
399 variables it ends up referring to.
401 IOW, in a deref constraint, we would deref, get the result set,
402 then add OFFSET to each member. */
403 unsigned HOST_WIDE_INT offset;
406 typedef struct constraint_expr ce_s;
408 DEF_VEC_ALLOC_O(ce_s, heap);
409 static void get_constraint_for (tree, VEC(ce_s, heap) **);
410 static void do_deref (VEC (ce_s, heap) **);
412 /* Our set constraints are made up of two constraint expressions, one
415 As described in the introduction, our set constraints each represent an
416 operation between set valued variables.
420 struct constraint_expr lhs;
421 struct constraint_expr rhs;
424 /* List of constraints that we use to build the constraint graph from. */
426 static VEC(constraint_t,heap) *constraints;
427 static alloc_pool constraint_pool;
431 DEF_VEC_ALLOC_I(int, heap);
433 /* The constraint graph is represented as an array of bitmaps
434 containing successor nodes. */
436 struct constraint_graph
438 /* Size of this graph, which may be different than the number of
439 nodes in the variable map. */
442 /* Explicit successors of each node. */
445 /* Implicit predecessors of each node (Used for variable
447 bitmap *implicit_preds;
449 /* Explicit predecessors of each node (Used for variable substitution). */
452 /* Indirect cycle representatives, or -1 if the node has no indirect
454 int *indirect_cycles;
456 /* Representative node for a node. rep[a] == a unless the node has
460 /* Equivalence class representative for a label. This is used for
461 variable substitution. */
464 /* Pointer equivalence label for a node. All nodes with the same
465 pointer equivalence label can be unified together at some point
466 (either during constraint optimization or after the constraint
470 /* Pointer equivalence representative for a label. This is used to
471 handle nodes that are pointer equivalent but not location
472 equivalent. We can unite these once the addressof constraints
473 are transformed into initial points-to sets. */
476 /* Pointer equivalence label for each node, used during variable
478 unsigned int *pointer_label;
480 /* Location equivalence label for each node, used during location
481 equivalence finding. */
482 unsigned int *loc_label;
484 /* Pointed-by set for each node, used during location equivalence
485 finding. This is pointed-by rather than pointed-to, because it
486 is constructed using the predecessor graph. */
489 /* Points to sets for pointer equivalence. This is *not* the actual
490 points-to sets for nodes. */
493 /* Bitmap of nodes where the bit is set if the node is a direct
494 node. Used for variable substitution. */
495 sbitmap direct_nodes;
497 /* Bitmap of nodes where the bit is set if the node is address
498 taken. Used for variable substitution. */
499 bitmap address_taken;
501 /* True if points_to bitmap for this node is stored in the hash
505 /* Number of incoming edges remaining to be processed by pointer
507 Used for variable substitution. */
508 unsigned int *number_incoming;
511 /* Vector of complex constraints for each graph node. Complex
512 constraints are those involving dereferences or offsets that are
514 VEC(constraint_t,heap) **complex;
517 static constraint_graph_t graph;
519 /* During variable substitution and the offline version of indirect
520 cycle finding, we create nodes to represent dereferences and
521 address taken constraints. These represent where these start and
523 #define FIRST_REF_NODE (VEC_length (varinfo_t, varmap))
524 #define LAST_REF_NODE (FIRST_REF_NODE + (FIRST_REF_NODE - 1))
526 /* Return the representative node for NODE, if NODE has been unioned
528 This function performs path compression along the way to finding
529 the representative. */
532 find (unsigned int node)
534 gcc_assert (node < graph->size);
535 if (graph->rep[node] != node)
536 return graph->rep[node] = find (graph->rep[node]);
540 /* Union the TO and FROM nodes to the TO nodes.
541 Note that at some point in the future, we may want to do
542 union-by-rank, in which case we are going to have to return the
543 node we unified to. */
546 unite (unsigned int to, unsigned int from)
548 gcc_assert (to < graph->size && from < graph->size);
549 if (to != from && graph->rep[from] != to)
551 graph->rep[from] = to;
557 /* Create a new constraint consisting of LHS and RHS expressions. */
560 new_constraint (const struct constraint_expr lhs,
561 const struct constraint_expr rhs)
563 constraint_t ret = (constraint_t) pool_alloc (constraint_pool);
569 /* Print out constraint C to FILE. */
572 dump_constraint (FILE *file, constraint_t c)
574 if (c->lhs.type == ADDRESSOF)
576 else if (c->lhs.type == DEREF)
578 fprintf (file, "%s", get_varinfo_fc (c->lhs.var)->name);
579 if (c->lhs.offset != 0)
580 fprintf (file, " + " HOST_WIDE_INT_PRINT_DEC, c->lhs.offset);
581 fprintf (file, " = ");
582 if (c->rhs.type == ADDRESSOF)
584 else if (c->rhs.type == DEREF)
586 fprintf (file, "%s", get_varinfo_fc (c->rhs.var)->name);
587 if (c->rhs.offset != 0)
588 fprintf (file, " + " HOST_WIDE_INT_PRINT_DEC, c->rhs.offset);
589 fprintf (file, "\n");
592 /* Print out constraint C to stderr. */
595 debug_constraint (constraint_t c)
597 dump_constraint (stderr, c);
600 /* Print out all constraints to FILE */
603 dump_constraints (FILE *file)
607 for (i = 0; VEC_iterate (constraint_t, constraints, i, c); i++)
608 dump_constraint (file, c);
611 /* Print out all constraints to stderr. */
614 debug_constraints (void)
616 dump_constraints (stderr);
621 The solver is a simple worklist solver, that works on the following
624 sbitmap changed_nodes = all zeroes;
626 For each node that is not already collapsed:
628 set bit in changed nodes
630 while (changed_count > 0)
632 compute topological ordering for constraint graph
634 find and collapse cycles in the constraint graph (updating
635 changed if necessary)
637 for each node (n) in the graph in topological order:
640 Process each complex constraint associated with the node,
641 updating changed if necessary.
643 For each outgoing edge from n, propagate the solution from n to
644 the destination of the edge, updating changed as necessary.
648 /* Return true if two constraint expressions A and B are equal. */
651 constraint_expr_equal (struct constraint_expr a, struct constraint_expr b)
653 return a.type == b.type && a.var == b.var && a.offset == b.offset;
656 /* Return true if constraint expression A is less than constraint expression
657 B. This is just arbitrary, but consistent, in order to give them an
661 constraint_expr_less (struct constraint_expr a, struct constraint_expr b)
663 if (a.type == b.type)
666 return a.offset < b.offset;
668 return a.var < b.var;
671 return a.type < b.type;
674 /* Return true if constraint A is less than constraint B. This is just
675 arbitrary, but consistent, in order to give them an ordering. */
678 constraint_less (const constraint_t a, const constraint_t b)
680 if (constraint_expr_less (a->lhs, b->lhs))
682 else if (constraint_expr_less (b->lhs, a->lhs))
685 return constraint_expr_less (a->rhs, b->rhs);
688 /* Return true if two constraints A and B are equal. */
691 constraint_equal (struct constraint a, struct constraint b)
693 return constraint_expr_equal (a.lhs, b.lhs)
694 && constraint_expr_equal (a.rhs, b.rhs);
698 /* Find a constraint LOOKFOR in the sorted constraint vector VEC */
701 constraint_vec_find (VEC(constraint_t,heap) *vec,
702 struct constraint lookfor)
710 place = VEC_lower_bound (constraint_t, vec, &lookfor, constraint_less);
711 if (place >= VEC_length (constraint_t, vec))
713 found = VEC_index (constraint_t, vec, place);
714 if (!constraint_equal (*found, lookfor))
719 /* Union two constraint vectors, TO and FROM. Put the result in TO. */
722 constraint_set_union (VEC(constraint_t,heap) **to,
723 VEC(constraint_t,heap) **from)
728 for (i = 0; VEC_iterate (constraint_t, *from, i, c); i++)
730 if (constraint_vec_find (*to, *c) == NULL)
732 unsigned int place = VEC_lower_bound (constraint_t, *to, c,
734 VEC_safe_insert (constraint_t, heap, *to, place, c);
739 /* Take a solution set SET, add OFFSET to each member of the set, and
740 overwrite SET with the result when done. */
743 solution_set_add (bitmap set, unsigned HOST_WIDE_INT offset)
745 bitmap result = BITMAP_ALLOC (&iteration_obstack);
749 EXECUTE_IF_SET_IN_BITMAP (set, 0, i, bi)
751 /* If this is a properly sized variable, only add offset if it's
752 less than end. Otherwise, it is globbed to a single
755 if ((get_varinfo (i)->offset + offset) < get_varinfo (i)->fullsize)
757 unsigned HOST_WIDE_INT fieldoffset = get_varinfo (i)->offset + offset;
758 varinfo_t v = first_vi_for_offset (get_varinfo (i), fieldoffset);
761 bitmap_set_bit (result, v->id);
763 else if (get_varinfo (i)->is_artificial_var
764 || get_varinfo (i)->has_union
765 || get_varinfo (i)->is_unknown_size_var)
767 bitmap_set_bit (result, i);
771 bitmap_copy (set, result);
772 BITMAP_FREE (result);
775 /* Union solution sets TO and FROM, and add INC to each member of FROM in the
779 set_union_with_increment (bitmap to, bitmap from, unsigned HOST_WIDE_INT inc)
782 return bitmap_ior_into (to, from);
788 tmp = BITMAP_ALLOC (&iteration_obstack);
789 bitmap_copy (tmp, from);
790 solution_set_add (tmp, inc);
791 res = bitmap_ior_into (to, tmp);
797 /* Insert constraint C into the list of complex constraints for graph
801 insert_into_complex (constraint_graph_t graph,
802 unsigned int var, constraint_t c)
804 VEC (constraint_t, heap) *complex = graph->complex[var];
805 unsigned int place = VEC_lower_bound (constraint_t, complex, c,
808 /* Only insert constraints that do not already exist. */
809 if (place >= VEC_length (constraint_t, complex)
810 || !constraint_equal (*c, *VEC_index (constraint_t, complex, place)))
811 VEC_safe_insert (constraint_t, heap, graph->complex[var], place, c);
815 /* Condense two variable nodes into a single variable node, by moving
816 all associated info from SRC to TO. */
819 merge_node_constraints (constraint_graph_t graph, unsigned int to,
825 gcc_assert (find (from) == to);
827 /* Move all complex constraints from src node into to node */
828 for (i = 0; VEC_iterate (constraint_t, graph->complex[from], i, c); i++)
830 /* In complex constraints for node src, we may have either
831 a = *src, and *src = a, or an offseted constraint which are
832 always added to the rhs node's constraints. */
834 if (c->rhs.type == DEREF)
836 else if (c->lhs.type == DEREF)
841 constraint_set_union (&graph->complex[to], &graph->complex[from]);
842 VEC_free (constraint_t, heap, graph->complex[from]);
843 graph->complex[from] = NULL;
847 /* Remove edges involving NODE from GRAPH. */
850 clear_edges_for_node (constraint_graph_t graph, unsigned int node)
852 if (graph->succs[node])
853 BITMAP_FREE (graph->succs[node]);
856 /* Merge GRAPH nodes FROM and TO into node TO. */
859 merge_graph_nodes (constraint_graph_t graph, unsigned int to,
862 if (graph->indirect_cycles[from] != -1)
864 /* If we have indirect cycles with the from node, and we have
865 none on the to node, the to node has indirect cycles from the
866 from node now that they are unified.
867 If indirect cycles exist on both, unify the nodes that they
868 are in a cycle with, since we know they are in a cycle with
870 if (graph->indirect_cycles[to] == -1)
871 graph->indirect_cycles[to] = graph->indirect_cycles[from];
874 /* Merge all the successor edges. */
875 if (graph->succs[from])
877 if (!graph->succs[to])
878 graph->succs[to] = BITMAP_ALLOC (&pta_obstack);
879 bitmap_ior_into (graph->succs[to],
883 clear_edges_for_node (graph, from);
887 /* Add an indirect graph edge to GRAPH, going from TO to FROM if
888 it doesn't exist in the graph already. */
891 add_implicit_graph_edge (constraint_graph_t graph, unsigned int to,
897 if (!graph->implicit_preds[to])
898 graph->implicit_preds[to] = BITMAP_ALLOC (&predbitmap_obstack);
900 if (!bitmap_bit_p (graph->implicit_preds[to], from))
902 stats.num_implicit_edges++;
903 bitmap_set_bit (graph->implicit_preds[to], from);
907 /* Add a predecessor graph edge to GRAPH, going from TO to FROM if
908 it doesn't exist in the graph already.
909 Return false if the edge already existed, true otherwise. */
912 add_pred_graph_edge (constraint_graph_t graph, unsigned int to,
915 if (!graph->preds[to])
916 graph->preds[to] = BITMAP_ALLOC (&predbitmap_obstack);
917 if (!bitmap_bit_p (graph->preds[to], from))
918 bitmap_set_bit (graph->preds[to], from);
921 /* Add a graph edge to GRAPH, going from FROM to TO if
922 it doesn't exist in the graph already.
923 Return false if the edge already existed, true otherwise. */
926 add_graph_edge (constraint_graph_t graph, unsigned int to,
937 if (!graph->succs[from])
938 graph->succs[from] = BITMAP_ALLOC (&pta_obstack);
939 if (!bitmap_bit_p (graph->succs[from], to))
942 if (to < FIRST_REF_NODE && from < FIRST_REF_NODE)
944 bitmap_set_bit (graph->succs[from], to);
951 /* Return true if {DEST.SRC} is an existing graph edge in GRAPH. */
954 valid_graph_edge (constraint_graph_t graph, unsigned int src,
957 return (graph->succs[dest]
958 && bitmap_bit_p (graph->succs[dest], src));
961 /* Initialize the constraint graph structure to contain SIZE nodes. */
964 init_graph (unsigned int size)
968 graph = XCNEW (struct constraint_graph);
970 graph->succs = XCNEWVEC (bitmap, graph->size);
971 graph->indirect_cycles = XNEWVEC (int, graph->size);
972 graph->rep = XNEWVEC (unsigned int, graph->size);
973 graph->complex = XCNEWVEC (VEC(constraint_t, heap) *, size);
974 graph->pe = XCNEWVEC (unsigned int, graph->size);
975 graph->pe_rep = XNEWVEC (int, graph->size);
977 for (j = 0; j < graph->size; j++)
980 graph->pe_rep[j] = -1;
981 graph->indirect_cycles[j] = -1;
985 /* Build the constraint graph, adding only predecessor edges right now. */
988 build_pred_graph (void)
994 graph->implicit_preds = XCNEWVEC (bitmap, graph->size);
995 graph->preds = XCNEWVEC (bitmap, graph->size);
996 graph->pointer_label = XCNEWVEC (unsigned int, graph->size);
997 graph->loc_label = XCNEWVEC (unsigned int, graph->size);
998 graph->pointed_by = XCNEWVEC (bitmap, graph->size);
999 graph->points_to = XCNEWVEC (bitmap, graph->size);
1000 graph->eq_rep = XNEWVEC (int, graph->size);
1001 graph->direct_nodes = sbitmap_alloc (graph->size);
1002 graph->pt_used = sbitmap_alloc (graph->size);
1003 graph->address_taken = BITMAP_ALLOC (&predbitmap_obstack);
1004 graph->number_incoming = XCNEWVEC (unsigned int, graph->size);
1005 sbitmap_zero (graph->direct_nodes);
1006 sbitmap_zero (graph->pt_used);
1008 for (j = 0; j < FIRST_REF_NODE; j++)
1010 if (!get_varinfo (j)->is_special_var)
1011 SET_BIT (graph->direct_nodes, j);
1014 for (j = 0; j < graph->size; j++)
1015 graph->eq_rep[j] = -1;
1017 for (j = 0; j < VEC_length (varinfo_t, varmap); j++)
1018 graph->indirect_cycles[j] = -1;
1020 for (i = 0; VEC_iterate (constraint_t, constraints, i, c); i++)
1022 struct constraint_expr lhs = c->lhs;
1023 struct constraint_expr rhs = c->rhs;
1024 unsigned int lhsvar = get_varinfo_fc (lhs.var)->id;
1025 unsigned int rhsvar = get_varinfo_fc (rhs.var)->id;
1027 if (lhs.type == DEREF)
1030 if (rhs.offset == 0 && lhs.offset == 0 && rhs.type == SCALAR)
1031 add_pred_graph_edge (graph, FIRST_REF_NODE + lhsvar, rhsvar);
1033 else if (rhs.type == DEREF)
1036 if (rhs.offset == 0 && lhs.offset == 0 && lhs.type == SCALAR)
1037 add_pred_graph_edge (graph, lhsvar, FIRST_REF_NODE + rhsvar);
1039 RESET_BIT (graph->direct_nodes, lhsvar);
1041 else if (rhs.type == ADDRESSOF)
1044 if (graph->points_to[lhsvar] == NULL)
1045 graph->points_to[lhsvar] = BITMAP_ALLOC (&predbitmap_obstack);
1046 bitmap_set_bit (graph->points_to[lhsvar], rhsvar);
1048 if (graph->pointed_by[rhsvar] == NULL)
1049 graph->pointed_by[rhsvar] = BITMAP_ALLOC (&predbitmap_obstack);
1050 bitmap_set_bit (graph->pointed_by[rhsvar], lhsvar);
1052 /* Implicitly, *x = y */
1053 add_implicit_graph_edge (graph, FIRST_REF_NODE + lhsvar, rhsvar);
1055 RESET_BIT (graph->direct_nodes, rhsvar);
1056 bitmap_set_bit (graph->address_taken, rhsvar);
1058 else if (lhsvar > anything_id
1059 && lhsvar != rhsvar && lhs.offset == 0 && rhs.offset == 0)
1062 add_pred_graph_edge (graph, lhsvar, rhsvar);
1063 /* Implicitly, *x = *y */
1064 add_implicit_graph_edge (graph, FIRST_REF_NODE + lhsvar,
1065 FIRST_REF_NODE + rhsvar);
1067 else if (lhs.offset != 0 || rhs.offset != 0)
1069 if (rhs.offset != 0)
1070 RESET_BIT (graph->direct_nodes, lhs.var);
1071 else if (lhs.offset != 0)
1072 RESET_BIT (graph->direct_nodes, rhs.var);
1077 /* Build the constraint graph, adding successor edges. */
1080 build_succ_graph (void)
1085 for (i = 0; VEC_iterate (constraint_t, constraints, i, c); i++)
1087 struct constraint_expr lhs;
1088 struct constraint_expr rhs;
1089 unsigned int lhsvar;
1090 unsigned int rhsvar;
1097 lhsvar = find (get_varinfo_fc (lhs.var)->id);
1098 rhsvar = find (get_varinfo_fc (rhs.var)->id);
1100 if (lhs.type == DEREF)
1102 if (rhs.offset == 0 && lhs.offset == 0 && rhs.type == SCALAR)
1103 add_graph_edge (graph, FIRST_REF_NODE + lhsvar, rhsvar);
1105 else if (rhs.type == DEREF)
1107 if (rhs.offset == 0 && lhs.offset == 0 && lhs.type == SCALAR)
1108 add_graph_edge (graph, lhsvar, FIRST_REF_NODE + rhsvar);
1110 else if (rhs.type == ADDRESSOF)
1113 gcc_assert (find (get_varinfo_fc (rhs.var)->id)
1114 == get_varinfo_fc (rhs.var)->id);
1115 bitmap_set_bit (get_varinfo (lhsvar)->solution, rhsvar);
1117 else if (lhsvar > anything_id
1118 && lhsvar != rhsvar && lhs.offset == 0 && rhs.offset == 0)
1120 add_graph_edge (graph, lhsvar, rhsvar);
1126 /* Changed variables on the last iteration. */
1127 static unsigned int changed_count;
1128 static sbitmap changed;
1130 DEF_VEC_I(unsigned);
1131 DEF_VEC_ALLOC_I(unsigned,heap);
1134 /* Strongly Connected Component visitation info. */
1141 unsigned int *node_mapping;
1143 VEC(unsigned,heap) *scc_stack;
1147 /* Recursive routine to find strongly connected components in GRAPH.
1148 SI is the SCC info to store the information in, and N is the id of current
1149 graph node we are processing.
1151 This is Tarjan's strongly connected component finding algorithm, as
1152 modified by Nuutila to keep only non-root nodes on the stack.
1153 The algorithm can be found in "On finding the strongly connected
1154 connected components in a directed graph" by Esko Nuutila and Eljas
1155 Soisalon-Soininen, in Information Processing Letters volume 49,
1156 number 1, pages 9-14. */
1159 scc_visit (constraint_graph_t graph, struct scc_info *si, unsigned int n)
1163 unsigned int my_dfs;
1165 SET_BIT (si->visited, n);
1166 si->dfs[n] = si->current_index ++;
1167 my_dfs = si->dfs[n];
1169 /* Visit all the successors. */
1170 EXECUTE_IF_IN_NONNULL_BITMAP (graph->succs[n], 0, i, bi)
1174 if (i > LAST_REF_NODE)
1178 if (TEST_BIT (si->deleted, w))
1181 if (!TEST_BIT (si->visited, w))
1182 scc_visit (graph, si, w);
1184 unsigned int t = find (w);
1185 unsigned int nnode = find (n);
1186 gcc_assert (nnode == n);
1188 if (si->dfs[t] < si->dfs[nnode])
1189 si->dfs[n] = si->dfs[t];
1193 /* See if any components have been identified. */
1194 if (si->dfs[n] == my_dfs)
1196 if (VEC_length (unsigned, si->scc_stack) > 0
1197 && si->dfs[VEC_last (unsigned, si->scc_stack)] >= my_dfs)
1199 bitmap scc = BITMAP_ALLOC (NULL);
1200 bool have_ref_node = n >= FIRST_REF_NODE;
1201 unsigned int lowest_node;
1204 bitmap_set_bit (scc, n);
1206 while (VEC_length (unsigned, si->scc_stack) != 0
1207 && si->dfs[VEC_last (unsigned, si->scc_stack)] >= my_dfs)
1209 unsigned int w = VEC_pop (unsigned, si->scc_stack);
1211 bitmap_set_bit (scc, w);
1212 if (w >= FIRST_REF_NODE)
1213 have_ref_node = true;
1216 lowest_node = bitmap_first_set_bit (scc);
1217 gcc_assert (lowest_node < FIRST_REF_NODE);
1219 /* Collapse the SCC nodes into a single node, and mark the
1221 EXECUTE_IF_SET_IN_BITMAP (scc, 0, i, bi)
1223 if (i < FIRST_REF_NODE)
1225 if (unite (lowest_node, i))
1226 unify_nodes (graph, lowest_node, i, false);
1230 unite (lowest_node, i);
1231 graph->indirect_cycles[i - FIRST_REF_NODE] = lowest_node;
1235 SET_BIT (si->deleted, n);
1238 VEC_safe_push (unsigned, heap, si->scc_stack, n);
1241 /* Unify node FROM into node TO, updating the changed count if
1242 necessary when UPDATE_CHANGED is true. */
1245 unify_nodes (constraint_graph_t graph, unsigned int to, unsigned int from,
1246 bool update_changed)
1249 gcc_assert (to != from && find (to) == to);
1250 if (dump_file && (dump_flags & TDF_DETAILS))
1251 fprintf (dump_file, "Unifying %s to %s\n",
1252 get_varinfo (from)->name,
1253 get_varinfo (to)->name);
1256 stats.unified_vars_dynamic++;
1258 stats.unified_vars_static++;
1260 merge_graph_nodes (graph, to, from);
1261 merge_node_constraints (graph, to, from);
1263 if (get_varinfo (from)->no_tbaa_pruning)
1264 get_varinfo (to)->no_tbaa_pruning = true;
1266 /* Mark TO as changed if FROM was changed. If TO was already marked
1267 as changed, decrease the changed count. */
1269 if (update_changed && TEST_BIT (changed, from))
1271 RESET_BIT (changed, from);
1272 if (!TEST_BIT (changed, to))
1273 SET_BIT (changed, to);
1276 gcc_assert (changed_count > 0);
1280 if (get_varinfo (from)->solution)
1282 /* If the solution changes because of the merging, we need to mark
1283 the variable as changed. */
1284 if (bitmap_ior_into (get_varinfo (to)->solution,
1285 get_varinfo (from)->solution))
1287 if (update_changed && !TEST_BIT (changed, to))
1289 SET_BIT (changed, to);
1294 BITMAP_FREE (get_varinfo (from)->solution);
1295 BITMAP_FREE (get_varinfo (from)->oldsolution);
1297 if (stats.iterations > 0)
1299 BITMAP_FREE (get_varinfo (to)->oldsolution);
1300 get_varinfo (to)->oldsolution = BITMAP_ALLOC (&oldpta_obstack);
1303 if (valid_graph_edge (graph, to, to))
1305 if (graph->succs[to])
1306 bitmap_clear_bit (graph->succs[to], to);
1310 /* Information needed to compute the topological ordering of a graph. */
1314 /* sbitmap of visited nodes. */
1316 /* Array that stores the topological order of the graph, *in
1318 VEC(unsigned,heap) *topo_order;
1322 /* Initialize and return a topological info structure. */
1324 static struct topo_info *
1325 init_topo_info (void)
1327 size_t size = graph->size;
1328 struct topo_info *ti = XNEW (struct topo_info);
1329 ti->visited = sbitmap_alloc (size);
1330 sbitmap_zero (ti->visited);
1331 ti->topo_order = VEC_alloc (unsigned, heap, 1);
1336 /* Free the topological sort info pointed to by TI. */
1339 free_topo_info (struct topo_info *ti)
1341 sbitmap_free (ti->visited);
1342 VEC_free (unsigned, heap, ti->topo_order);
1346 /* Visit the graph in topological order, and store the order in the
1347 topo_info structure. */
1350 topo_visit (constraint_graph_t graph, struct topo_info *ti,
1356 SET_BIT (ti->visited, n);
1358 if (graph->succs[n])
1359 EXECUTE_IF_SET_IN_BITMAP (graph->succs[n], 0, j, bi)
1361 if (!TEST_BIT (ti->visited, j))
1362 topo_visit (graph, ti, j);
1365 VEC_safe_push (unsigned, heap, ti->topo_order, n);
1368 /* Return true if variable N + OFFSET is a legal field of N. */
1371 type_safe (unsigned int n, unsigned HOST_WIDE_INT *offset)
1373 varinfo_t ninfo = get_varinfo (n);
1375 /* For things we've globbed to single variables, any offset into the
1376 variable acts like the entire variable, so that it becomes offset
1378 if (ninfo->is_special_var
1379 || ninfo->is_artificial_var
1380 || ninfo->is_unknown_size_var)
1385 return (get_varinfo (n)->offset + *offset) < get_varinfo (n)->fullsize;
1388 /* Process a constraint C that represents x = *y, using DELTA as the
1389 starting solution. */
1392 do_sd_constraint (constraint_graph_t graph, constraint_t c,
1395 unsigned int lhs = c->lhs.var;
1397 bitmap sol = get_varinfo (lhs)->solution;
1401 if (bitmap_bit_p (delta, anything_id))
1403 flag = !bitmap_bit_p (sol, anything_id);
1405 bitmap_set_bit (sol, anything_id);
1408 /* For each variable j in delta (Sol(y)), add
1409 an edge in the graph from j to x, and union Sol(j) into Sol(x). */
1410 EXECUTE_IF_SET_IN_BITMAP (delta, 0, j, bi)
1412 unsigned HOST_WIDE_INT roffset = c->rhs.offset;
1413 if (type_safe (j, &roffset))
1416 unsigned HOST_WIDE_INT fieldoffset = get_varinfo (j)->offset + roffset;
1419 v = first_vi_for_offset (get_varinfo (j), fieldoffset);
1424 /* Adding edges from the special vars is pointless.
1425 They don't have sets that can change. */
1426 if (get_varinfo (t) ->is_special_var)
1427 flag |= bitmap_ior_into (sol, get_varinfo (t)->solution);
1428 else if (add_graph_edge (graph, lhs, t))
1429 flag |= bitmap_ior_into (sol, get_varinfo (t)->solution);
1431 else if (0 && dump_file && !(get_varinfo (j)->is_special_var))
1432 fprintf (dump_file, "Untypesafe usage in do_sd_constraint\n");
1437 /* If the LHS solution changed, mark the var as changed. */
1440 get_varinfo (lhs)->solution = sol;
1441 if (!TEST_BIT (changed, lhs))
1443 SET_BIT (changed, lhs);
1449 /* Process a constraint C that represents *x = y. */
1452 do_ds_constraint (constraint_t c, bitmap delta)
1454 unsigned int rhs = c->rhs.var;
1455 bitmap sol = get_varinfo (rhs)->solution;
1459 if (bitmap_bit_p (sol, anything_id))
1461 EXECUTE_IF_SET_IN_BITMAP (delta, 0, j, bi)
1463 varinfo_t jvi = get_varinfo (j);
1465 unsigned int loff = c->lhs.offset;
1466 unsigned HOST_WIDE_INT fieldoffset = jvi->offset + loff;
1469 v = first_vi_for_offset (get_varinfo (j), fieldoffset);
1474 if (!bitmap_bit_p (get_varinfo (t)->solution, anything_id))
1476 bitmap_set_bit (get_varinfo (t)->solution, anything_id);
1477 if (!TEST_BIT (changed, t))
1479 SET_BIT (changed, t);
1487 /* For each member j of delta (Sol(x)), add an edge from y to j and
1488 union Sol(y) into Sol(j) */
1489 EXECUTE_IF_SET_IN_BITMAP (delta, 0, j, bi)
1491 unsigned HOST_WIDE_INT loff = c->lhs.offset;
1492 if (type_safe (j, &loff) && !(get_varinfo (j)->is_special_var))
1496 unsigned HOST_WIDE_INT fieldoffset = get_varinfo (j)->offset + loff;
1499 v = first_vi_for_offset (get_varinfo (j), fieldoffset);
1503 tmp = get_varinfo (t)->solution;
1505 if (set_union_with_increment (tmp, sol, 0))
1507 get_varinfo (t)->solution = tmp;
1509 sol = get_varinfo (rhs)->solution;
1510 if (!TEST_BIT (changed, t))
1512 SET_BIT (changed, t);
1517 else if (0 && dump_file && !(get_varinfo (j)->is_special_var))
1518 fprintf (dump_file, "Untypesafe usage in do_ds_constraint\n");
1522 /* Handle a non-simple (simple meaning requires no iteration),
1523 constraint (IE *x = &y, x = *y, *x = y, and x = y with offsets involved). */
1526 do_complex_constraint (constraint_graph_t graph, constraint_t c, bitmap delta)
1528 if (c->lhs.type == DEREF)
1530 if (c->rhs.type == ADDRESSOF)
1537 do_ds_constraint (c, delta);
1540 else if (c->rhs.type == DEREF)
1543 if (!(get_varinfo (c->lhs.var)->is_special_var))
1544 do_sd_constraint (graph, c, delta);
1552 gcc_assert (c->rhs.type == SCALAR && c->lhs.type == SCALAR);
1553 solution = get_varinfo (c->rhs.var)->solution;
1554 tmp = get_varinfo (c->lhs.var)->solution;
1556 flag = set_union_with_increment (tmp, solution, c->rhs.offset);
1560 get_varinfo (c->lhs.var)->solution = tmp;
1561 if (!TEST_BIT (changed, c->lhs.var))
1563 SET_BIT (changed, c->lhs.var);
1570 /* Initialize and return a new SCC info structure. */
1572 static struct scc_info *
1573 init_scc_info (size_t size)
1575 struct scc_info *si = XNEW (struct scc_info);
1578 si->current_index = 0;
1579 si->visited = sbitmap_alloc (size);
1580 sbitmap_zero (si->visited);
1581 si->deleted = sbitmap_alloc (size);
1582 sbitmap_zero (si->deleted);
1583 si->node_mapping = XNEWVEC (unsigned int, size);
1584 si->dfs = XCNEWVEC (unsigned int, size);
1586 for (i = 0; i < size; i++)
1587 si->node_mapping[i] = i;
1589 si->scc_stack = VEC_alloc (unsigned, heap, 1);
1593 /* Free an SCC info structure pointed to by SI */
1596 free_scc_info (struct scc_info *si)
1598 sbitmap_free (si->visited);
1599 sbitmap_free (si->deleted);
1600 free (si->node_mapping);
1602 VEC_free (unsigned, heap, si->scc_stack);
1607 /* Find indirect cycles in GRAPH that occur, using strongly connected
1608 components, and note them in the indirect cycles map.
1610 This technique comes from Ben Hardekopf and Calvin Lin,
1611 "It Pays to be Lazy: Fast and Accurate Pointer Analysis for Millions of
1612 Lines of Code", submitted to PLDI 2007. */
1615 find_indirect_cycles (constraint_graph_t graph)
1618 unsigned int size = graph->size;
1619 struct scc_info *si = init_scc_info (size);
1621 for (i = 0; i < MIN (LAST_REF_NODE, size); i ++ )
1622 if (!TEST_BIT (si->visited, i) && find (i) == i)
1623 scc_visit (graph, si, i);
1628 /* Compute a topological ordering for GRAPH, and store the result in the
1629 topo_info structure TI. */
1632 compute_topo_order (constraint_graph_t graph,
1633 struct topo_info *ti)
1636 unsigned int size = graph->size;
1638 for (i = 0; i != size; ++i)
1639 if (!TEST_BIT (ti->visited, i) && find (i) == i)
1640 topo_visit (graph, ti, i);
1643 /* Structure used to for hash value numbering of pointer equivalence
1646 typedef struct equiv_class_label
1648 unsigned int equivalence_class;
1651 } *equiv_class_label_t;
1652 typedef const struct equiv_class_label *const_equiv_class_label_t;
1654 /* A hashtable for mapping a bitmap of labels->pointer equivalence
1656 static htab_t pointer_equiv_class_table;
1658 /* A hashtable for mapping a bitmap of labels->location equivalence
1660 static htab_t location_equiv_class_table;
1662 /* Hash function for a equiv_class_label_t */
1665 equiv_class_label_hash (const void *p)
1667 const_equiv_class_label_t const ecl = (const_equiv_class_label_t) p;
1668 return ecl->hashcode;
1671 /* Equality function for two equiv_class_label_t's. */
1674 equiv_class_label_eq (const void *p1, const void *p2)
1676 const_equiv_class_label_t const eql1 = (const_equiv_class_label_t) p1;
1677 const_equiv_class_label_t const eql2 = (const_equiv_class_label_t) p2;
1678 return bitmap_equal_p (eql1->labels, eql2->labels);
1681 /* Lookup a equivalence class in TABLE by the bitmap of LABELS it
1685 equiv_class_lookup (htab_t table, bitmap labels)
1688 struct equiv_class_label ecl;
1690 ecl.labels = labels;
1691 ecl.hashcode = bitmap_hash (labels);
1693 slot = htab_find_slot_with_hash (table, &ecl,
1694 ecl.hashcode, NO_INSERT);
1698 return ((equiv_class_label_t) *slot)->equivalence_class;
1702 /* Add an equivalence class named EQUIVALENCE_CLASS with labels LABELS
1706 equiv_class_add (htab_t table, unsigned int equivalence_class,
1710 equiv_class_label_t ecl = XNEW (struct equiv_class_label);
1712 ecl->labels = labels;
1713 ecl->equivalence_class = equivalence_class;
1714 ecl->hashcode = bitmap_hash (labels);
1716 slot = htab_find_slot_with_hash (table, ecl,
1717 ecl->hashcode, INSERT);
1718 gcc_assert (!*slot);
1719 *slot = (void *) ecl;
1722 /* Perform offline variable substitution.
1724 This is a worst case quadratic time way of identifying variables
1725 that must have equivalent points-to sets, including those caused by
1726 static cycles, and single entry subgraphs, in the constraint graph.
1728 The technique is described in "Exploiting Pointer and Location
1729 Equivalence to Optimize Pointer Analysis. In the 14th International
1730 Static Analysis Symposium (SAS), August 2007." It is known as the
1731 "HU" algorithm, and is equivalent to value numbering the collapsed
1732 constraint graph including evaluating unions.
1734 The general method of finding equivalence classes is as follows:
1735 Add fake nodes (REF nodes) and edges for *a = b and a = *b constraints.
1736 Initialize all non-REF nodes to be direct nodes.
1737 For each constraint a = a U {b}, we set pts(a) = pts(a) u {fresh
1739 For each constraint containing the dereference, we also do the same
1742 We then compute SCC's in the graph and unify nodes in the same SCC,
1745 For each non-collapsed node x:
1746 Visit all unvisited explicit incoming edges.
1747 Ignoring all non-pointers, set pts(x) = Union of pts(a) for y
1749 Lookup the equivalence class for pts(x).
1750 If we found one, equivalence_class(x) = found class.
1751 Otherwise, equivalence_class(x) = new class, and new_class is
1752 added to the lookup table.
1754 All direct nodes with the same equivalence class can be replaced
1755 with a single representative node.
1756 All unlabeled nodes (label == 0) are not pointers and all edges
1757 involving them can be eliminated.
1758 We perform these optimizations during rewrite_constraints
1760 In addition to pointer equivalence class finding, we also perform
1761 location equivalence class finding. This is the set of variables
1762 that always appear together in points-to sets. We use this to
1763 compress the size of the points-to sets. */
1765 /* Current maximum pointer equivalence class id. */
1766 static int pointer_equiv_class;
1768 /* Current maximum location equivalence class id. */
1769 static int location_equiv_class;
1771 /* Recursive routine to find strongly connected components in GRAPH,
1772 and label it's nodes with DFS numbers. */
1775 condense_visit (constraint_graph_t graph, struct scc_info *si, unsigned int n)
1779 unsigned int my_dfs;
1781 gcc_assert (si->node_mapping[n] == n);
1782 SET_BIT (si->visited, n);
1783 si->dfs[n] = si->current_index ++;
1784 my_dfs = si->dfs[n];
1786 /* Visit all the successors. */
1787 EXECUTE_IF_IN_NONNULL_BITMAP (graph->preds[n], 0, i, bi)
1789 unsigned int w = si->node_mapping[i];
1791 if (TEST_BIT (si->deleted, w))
1794 if (!TEST_BIT (si->visited, w))
1795 condense_visit (graph, si, w);
1797 unsigned int t = si->node_mapping[w];
1798 unsigned int nnode = si->node_mapping[n];
1799 gcc_assert (nnode == n);
1801 if (si->dfs[t] < si->dfs[nnode])
1802 si->dfs[n] = si->dfs[t];
1806 /* Visit all the implicit predecessors. */
1807 EXECUTE_IF_IN_NONNULL_BITMAP (graph->implicit_preds[n], 0, i, bi)
1809 unsigned int w = si->node_mapping[i];
1811 if (TEST_BIT (si->deleted, w))
1814 if (!TEST_BIT (si->visited, w))
1815 condense_visit (graph, si, w);
1817 unsigned int t = si->node_mapping[w];
1818 unsigned int nnode = si->node_mapping[n];
1819 gcc_assert (nnode == n);
1821 if (si->dfs[t] < si->dfs[nnode])
1822 si->dfs[n] = si->dfs[t];
1826 /* See if any components have been identified. */
1827 if (si->dfs[n] == my_dfs)
1829 while (VEC_length (unsigned, si->scc_stack) != 0
1830 && si->dfs[VEC_last (unsigned, si->scc_stack)] >= my_dfs)
1832 unsigned int w = VEC_pop (unsigned, si->scc_stack);
1833 si->node_mapping[w] = n;
1835 if (!TEST_BIT (graph->direct_nodes, w))
1836 RESET_BIT (graph->direct_nodes, n);
1838 /* Unify our nodes. */
1839 if (graph->preds[w])
1841 if (!graph->preds[n])
1842 graph->preds[n] = BITMAP_ALLOC (&predbitmap_obstack);
1843 bitmap_ior_into (graph->preds[n], graph->preds[w]);
1845 if (graph->implicit_preds[w])
1847 if (!graph->implicit_preds[n])
1848 graph->implicit_preds[n] = BITMAP_ALLOC (&predbitmap_obstack);
1849 bitmap_ior_into (graph->implicit_preds[n],
1850 graph->implicit_preds[w]);
1852 if (graph->points_to[w])
1854 if (!graph->points_to[n])
1855 graph->points_to[n] = BITMAP_ALLOC (&predbitmap_obstack);
1856 bitmap_ior_into (graph->points_to[n],
1857 graph->points_to[w]);
1859 EXECUTE_IF_IN_NONNULL_BITMAP (graph->preds[n], 0, i, bi)
1861 unsigned int rep = si->node_mapping[i];
1862 graph->number_incoming[rep]++;
1865 SET_BIT (si->deleted, n);
1868 VEC_safe_push (unsigned, heap, si->scc_stack, n);
1871 /* Label pointer equivalences. */
1874 label_visit (constraint_graph_t graph, struct scc_info *si, unsigned int n)
1878 SET_BIT (si->visited, n);
1880 if (!graph->points_to[n])
1881 graph->points_to[n] = BITMAP_ALLOC (&predbitmap_obstack);
1883 /* Label and union our incoming edges's points to sets. */
1884 EXECUTE_IF_IN_NONNULL_BITMAP (graph->preds[n], 0, i, bi)
1886 unsigned int w = si->node_mapping[i];
1887 if (!TEST_BIT (si->visited, w))
1888 label_visit (graph, si, w);
1890 /* Skip unused edges */
1891 if (w == n || graph->pointer_label[w] == 0)
1893 graph->number_incoming[w]--;
1896 if (graph->points_to[w])
1897 bitmap_ior_into(graph->points_to[n], graph->points_to[w]);
1899 /* If all incoming edges to w have been processed and
1900 graph->points_to[w] was not stored in the hash table, we can
1902 graph->number_incoming[w]--;
1903 if (!graph->number_incoming[w] && !TEST_BIT (graph->pt_used, w))
1905 BITMAP_FREE (graph->points_to[w]);
1908 /* Indirect nodes get fresh variables. */
1909 if (!TEST_BIT (graph->direct_nodes, n))
1910 bitmap_set_bit (graph->points_to[n], FIRST_REF_NODE + n);
1912 if (!bitmap_empty_p (graph->points_to[n]))
1914 unsigned int label = equiv_class_lookup (pointer_equiv_class_table,
1915 graph->points_to[n]);
1918 SET_BIT (graph->pt_used, n);
1919 label = pointer_equiv_class++;
1920 equiv_class_add (pointer_equiv_class_table,
1921 label, graph->points_to[n]);
1923 graph->pointer_label[n] = label;
1927 /* Perform offline variable substitution, discovering equivalence
1928 classes, and eliminating non-pointer variables. */
1930 static struct scc_info *
1931 perform_var_substitution (constraint_graph_t graph)
1934 unsigned int size = graph->size;
1935 struct scc_info *si = init_scc_info (size);
1937 bitmap_obstack_initialize (&iteration_obstack);
1938 pointer_equiv_class_table = htab_create (511, equiv_class_label_hash,
1939 equiv_class_label_eq, free);
1940 location_equiv_class_table = htab_create (511, equiv_class_label_hash,
1941 equiv_class_label_eq, free);
1942 pointer_equiv_class = 1;
1943 location_equiv_class = 1;
1945 /* Condense the nodes, which means to find SCC's, count incoming
1946 predecessors, and unite nodes in SCC's. */
1947 for (i = 0; i < FIRST_REF_NODE; i++)
1948 if (!TEST_BIT (si->visited, si->node_mapping[i]))
1949 condense_visit (graph, si, si->node_mapping[i]);
1951 sbitmap_zero (si->visited);
1952 /* Actually the label the nodes for pointer equivalences */
1953 for (i = 0; i < FIRST_REF_NODE; i++)
1954 if (!TEST_BIT (si->visited, si->node_mapping[i]))
1955 label_visit (graph, si, si->node_mapping[i]);
1957 /* Calculate location equivalence labels. */
1958 for (i = 0; i < FIRST_REF_NODE; i++)
1965 if (!graph->pointed_by[i])
1967 pointed_by = BITMAP_ALLOC (&iteration_obstack);
1969 /* Translate the pointed-by mapping for pointer equivalence
1971 EXECUTE_IF_SET_IN_BITMAP (graph->pointed_by[i], 0, j, bi)
1973 bitmap_set_bit (pointed_by,
1974 graph->pointer_label[si->node_mapping[j]]);
1976 /* The original pointed_by is now dead. */
1977 BITMAP_FREE (graph->pointed_by[i]);
1979 /* Look up the location equivalence label if one exists, or make
1981 label = equiv_class_lookup (location_equiv_class_table,
1985 label = location_equiv_class++;
1986 equiv_class_add (location_equiv_class_table,
1991 if (dump_file && (dump_flags & TDF_DETAILS))
1992 fprintf (dump_file, "Found location equivalence for node %s\n",
1993 get_varinfo (i)->name);
1994 BITMAP_FREE (pointed_by);
1996 graph->loc_label[i] = label;
2000 if (dump_file && (dump_flags & TDF_DETAILS))
2001 for (i = 0; i < FIRST_REF_NODE; i++)
2003 bool direct_node = TEST_BIT (graph->direct_nodes, i);
2005 "Equivalence classes for %s node id %d:%s are pointer: %d"
2007 direct_node ? "Direct node" : "Indirect node", i,
2008 get_varinfo (i)->name,
2009 graph->pointer_label[si->node_mapping[i]],
2010 graph->loc_label[si->node_mapping[i]]);
2013 /* Quickly eliminate our non-pointer variables. */
2015 for (i = 0; i < FIRST_REF_NODE; i++)
2017 unsigned int node = si->node_mapping[i];
2019 if (graph->pointer_label[node] == 0)
2021 if (dump_file && (dump_flags & TDF_DETAILS))
2023 "%s is a non-pointer variable, eliminating edges.\n",
2024 get_varinfo (node)->name);
2025 stats.nonpointer_vars++;
2026 clear_edges_for_node (graph, node);
2033 /* Free information that was only necessary for variable
2037 free_var_substitution_info (struct scc_info *si)
2040 free (graph->pointer_label);
2041 free (graph->loc_label);
2042 free (graph->pointed_by);
2043 free (graph->points_to);
2044 free (graph->number_incoming);
2045 free (graph->eq_rep);
2046 sbitmap_free (graph->direct_nodes);
2047 sbitmap_free (graph->pt_used);
2048 htab_delete (pointer_equiv_class_table);
2049 htab_delete (location_equiv_class_table);
2050 bitmap_obstack_release (&iteration_obstack);
2053 /* Return an existing node that is equivalent to NODE, which has
2054 equivalence class LABEL, if one exists. Return NODE otherwise. */
2057 find_equivalent_node (constraint_graph_t graph,
2058 unsigned int node, unsigned int label)
2060 /* If the address version of this variable is unused, we can
2061 substitute it for anything else with the same label.
2062 Otherwise, we know the pointers are equivalent, but not the
2063 locations, and we can unite them later. */
2065 if (!bitmap_bit_p (graph->address_taken, node))
2067 gcc_assert (label < graph->size);
2069 if (graph->eq_rep[label] != -1)
2071 /* Unify the two variables since we know they are equivalent. */
2072 if (unite (graph->eq_rep[label], node))
2073 unify_nodes (graph, graph->eq_rep[label], node, false);
2074 return graph->eq_rep[label];
2078 graph->eq_rep[label] = node;
2079 graph->pe_rep[label] = node;
2084 gcc_assert (label < graph->size);
2085 graph->pe[node] = label;
2086 if (graph->pe_rep[label] == -1)
2087 graph->pe_rep[label] = node;
2093 /* Unite pointer equivalent but not location equivalent nodes in
2094 GRAPH. This may only be performed once variable substitution is
2098 unite_pointer_equivalences (constraint_graph_t graph)
2102 /* Go through the pointer equivalences and unite them to their
2103 representative, if they aren't already. */
2104 for (i = 0; i < FIRST_REF_NODE; i++)
2106 unsigned int label = graph->pe[i];
2109 int label_rep = graph->pe_rep[label];
2111 if (label_rep == -1)
2114 label_rep = find (label_rep);
2115 if (label_rep >= 0 && unite (label_rep, find (i)))
2116 unify_nodes (graph, label_rep, i, false);
2121 /* Move complex constraints to the GRAPH nodes they belong to. */
2124 move_complex_constraints (constraint_graph_t graph)
2129 for (i = 0; VEC_iterate (constraint_t, constraints, i, c); i++)
2133 struct constraint_expr lhs = c->lhs;
2134 struct constraint_expr rhs = c->rhs;
2136 if (lhs.type == DEREF)
2138 insert_into_complex (graph, lhs.var, c);
2140 else if (rhs.type == DEREF)
2142 if (!(get_varinfo (lhs.var)->is_special_var))
2143 insert_into_complex (graph, rhs.var, c);
2145 else if (rhs.type != ADDRESSOF && lhs.var > anything_id
2146 && (lhs.offset != 0 || rhs.offset != 0))
2148 insert_into_complex (graph, rhs.var, c);
2155 /* Optimize and rewrite complex constraints while performing
2156 collapsing of equivalent nodes. SI is the SCC_INFO that is the
2157 result of perform_variable_substitution. */
2160 rewrite_constraints (constraint_graph_t graph,
2161 struct scc_info *si)
2167 for (j = 0; j < graph->size; j++)
2168 gcc_assert (find (j) == j);
2170 for (i = 0; VEC_iterate (constraint_t, constraints, i, c); i++)
2172 struct constraint_expr lhs = c->lhs;
2173 struct constraint_expr rhs = c->rhs;
2174 unsigned int lhsvar = find (get_varinfo_fc (lhs.var)->id);
2175 unsigned int rhsvar = find (get_varinfo_fc (rhs.var)->id);
2176 unsigned int lhsnode, rhsnode;
2177 unsigned int lhslabel, rhslabel;
2179 lhsnode = si->node_mapping[lhsvar];
2180 rhsnode = si->node_mapping[rhsvar];
2181 lhslabel = graph->pointer_label[lhsnode];
2182 rhslabel = graph->pointer_label[rhsnode];
2184 /* See if it is really a non-pointer variable, and if so, ignore
2188 if (dump_file && (dump_flags & TDF_DETAILS))
2191 fprintf (dump_file, "%s is a non-pointer variable,"
2192 "ignoring constraint:",
2193 get_varinfo (lhs.var)->name);
2194 dump_constraint (dump_file, c);
2196 VEC_replace (constraint_t, constraints, i, NULL);
2202 if (dump_file && (dump_flags & TDF_DETAILS))
2205 fprintf (dump_file, "%s is a non-pointer variable,"
2206 "ignoring constraint:",
2207 get_varinfo (rhs.var)->name);
2208 dump_constraint (dump_file, c);
2210 VEC_replace (constraint_t, constraints, i, NULL);
2214 lhsvar = find_equivalent_node (graph, lhsvar, lhslabel);
2215 rhsvar = find_equivalent_node (graph, rhsvar, rhslabel);
2216 c->lhs.var = lhsvar;
2217 c->rhs.var = rhsvar;
2222 /* Eliminate indirect cycles involving NODE. Return true if NODE was
2223 part of an SCC, false otherwise. */
2226 eliminate_indirect_cycles (unsigned int node)
2228 if (graph->indirect_cycles[node] != -1
2229 && !bitmap_empty_p (get_varinfo (node)->solution))
2232 VEC(unsigned,heap) *queue = NULL;
2234 unsigned int to = find (graph->indirect_cycles[node]);
2237 /* We can't touch the solution set and call unify_nodes
2238 at the same time, because unify_nodes is going to do
2239 bitmap unions into it. */
2241 EXECUTE_IF_SET_IN_BITMAP (get_varinfo (node)->solution, 0, i, bi)
2243 if (find (i) == i && i != to)
2246 VEC_safe_push (unsigned, heap, queue, i);
2251 VEC_iterate (unsigned, queue, queuepos, i);
2254 unify_nodes (graph, to, i, true);
2256 VEC_free (unsigned, heap, queue);
2262 /* Solve the constraint graph GRAPH using our worklist solver.
2263 This is based on the PW* family of solvers from the "Efficient Field
2264 Sensitive Pointer Analysis for C" paper.
2265 It works by iterating over all the graph nodes, processing the complex
2266 constraints and propagating the copy constraints, until everything stops
2267 changed. This corresponds to steps 6-8 in the solving list given above. */
2270 solve_graph (constraint_graph_t graph)
2272 unsigned int size = graph->size;
2277 changed = sbitmap_alloc (size);
2278 sbitmap_zero (changed);
2280 /* Mark all initial non-collapsed nodes as changed. */
2281 for (i = 0; i < size; i++)
2283 varinfo_t ivi = get_varinfo (i);
2284 if (find (i) == i && !bitmap_empty_p (ivi->solution)
2285 && ((graph->succs[i] && !bitmap_empty_p (graph->succs[i]))
2286 || VEC_length (constraint_t, graph->complex[i]) > 0))
2288 SET_BIT (changed, i);
2293 /* Allocate a bitmap to be used to store the changed bits. */
2294 pts = BITMAP_ALLOC (&pta_obstack);
2296 while (changed_count > 0)
2299 struct topo_info *ti = init_topo_info ();
2302 bitmap_obstack_initialize (&iteration_obstack);
2304 compute_topo_order (graph, ti);
2306 while (VEC_length (unsigned, ti->topo_order) != 0)
2309 i = VEC_pop (unsigned, ti->topo_order);
2311 /* If this variable is not a representative, skip it. */
2315 /* In certain indirect cycle cases, we may merge this
2316 variable to another. */
2317 if (eliminate_indirect_cycles (i) && find (i) != i)
2320 /* If the node has changed, we need to process the
2321 complex constraints and outgoing edges again. */
2322 if (TEST_BIT (changed, i))
2327 VEC(constraint_t,heap) *complex = graph->complex[i];
2328 bool solution_empty;
2330 RESET_BIT (changed, i);
2333 /* Compute the changed set of solution bits. */
2334 bitmap_and_compl (pts, get_varinfo (i)->solution,
2335 get_varinfo (i)->oldsolution);
2337 if (bitmap_empty_p (pts))
2340 bitmap_ior_into (get_varinfo (i)->oldsolution, pts);
2342 solution = get_varinfo (i)->solution;
2343 solution_empty = bitmap_empty_p (solution);
2345 /* Process the complex constraints */
2346 for (j = 0; VEC_iterate (constraint_t, complex, j, c); j++)
2348 /* XXX: This is going to unsort the constraints in
2349 some cases, which will occasionally add duplicate
2350 constraints during unification. This does not
2351 affect correctness. */
2352 c->lhs.var = find (c->lhs.var);
2353 c->rhs.var = find (c->rhs.var);
2355 /* The only complex constraint that can change our
2356 solution to non-empty, given an empty solution,
2357 is a constraint where the lhs side is receiving
2358 some set from elsewhere. */
2359 if (!solution_empty || c->lhs.type != DEREF)
2360 do_complex_constraint (graph, c, pts);
2363 solution_empty = bitmap_empty_p (solution);
2365 if (!solution_empty)
2369 /* Propagate solution to all successors. */
2370 EXECUTE_IF_IN_NONNULL_BITMAP (graph->succs[i],
2376 unsigned int to = find (j);
2377 tmp = get_varinfo (to)->solution;
2380 /* Don't try to propagate to ourselves. */
2384 flag = set_union_with_increment (tmp, pts, 0);
2388 get_varinfo (to)->solution = tmp;
2389 if (!TEST_BIT (changed, to))
2391 SET_BIT (changed, to);
2399 free_topo_info (ti);
2400 bitmap_obstack_release (&iteration_obstack);
2404 sbitmap_free (changed);
2405 bitmap_obstack_release (&oldpta_obstack);
2408 /* Map from trees to variable infos. */
2409 static struct pointer_map_t *vi_for_tree;
2412 /* Insert ID as the variable id for tree T in the vi_for_tree map. */
2415 insert_vi_for_tree (tree t, varinfo_t vi)
2417 void **slot = pointer_map_insert (vi_for_tree, t);
2419 gcc_assert (*slot == NULL);
2423 /* Find the variable info for tree T in VI_FOR_TREE. If T does not
2424 exist in the map, return NULL, otherwise, return the varinfo we found. */
2427 lookup_vi_for_tree (tree t)
2429 void **slot = pointer_map_contains (vi_for_tree, t);
2433 return (varinfo_t) *slot;
2436 /* Return a printable name for DECL */
2439 alias_get_name (tree decl)
2441 const char *res = get_name (decl);
2443 int num_printed = 0;
2452 if (TREE_CODE (decl) == SSA_NAME)
2454 num_printed = asprintf (&temp, "%s_%u",
2455 alias_get_name (SSA_NAME_VAR (decl)),
2456 SSA_NAME_VERSION (decl));
2458 else if (DECL_P (decl))
2460 num_printed = asprintf (&temp, "D.%u", DECL_UID (decl));
2462 if (num_printed > 0)
2464 res = ggc_strdup (temp);
2470 /* Find the variable id for tree T in the map.
2471 If T doesn't exist in the map, create an entry for it and return it. */
2474 get_vi_for_tree (tree t)
2476 void **slot = pointer_map_contains (vi_for_tree, t);
2478 return get_varinfo (create_variable_info_for (t, alias_get_name (t)));
2480 return (varinfo_t) *slot;
2483 /* Get a constraint expression from an SSA_VAR_P node. */
2485 static struct constraint_expr
2486 get_constraint_exp_from_ssa_var (tree t)
2488 struct constraint_expr cexpr;
2490 gcc_assert (SSA_VAR_P (t) || DECL_P (t));
2492 /* For parameters, get at the points-to set for the actual parm
2494 if (TREE_CODE (t) == SSA_NAME
2495 && TREE_CODE (SSA_NAME_VAR (t)) == PARM_DECL
2496 && SSA_NAME_IS_DEFAULT_DEF (t))
2497 return get_constraint_exp_from_ssa_var (SSA_NAME_VAR (t));
2499 cexpr.type = SCALAR;
2501 cexpr.var = get_vi_for_tree (t)->id;
2502 /* If we determine the result is "anything", and we know this is readonly,
2503 say it points to readonly memory instead. */
2504 if (cexpr.var == anything_id && TREE_READONLY (t))
2506 cexpr.type = ADDRESSOF;
2507 cexpr.var = readonly_id;
2514 /* Process a completed constraint T, and add it to the constraint
2515 list. FROM_CALL is true if this is a constraint coming from a
2516 call, which means any DEREFs we see are "may-deref's", not
2520 process_constraint_1 (constraint_t t, bool from_call)
2522 struct constraint_expr rhs = t->rhs;
2523 struct constraint_expr lhs = t->lhs;
2525 gcc_assert (rhs.var < VEC_length (varinfo_t, varmap));
2526 gcc_assert (lhs.var < VEC_length (varinfo_t, varmap));
2530 if (lhs.type == DEREF)
2531 get_varinfo (lhs.var)->directly_dereferenced = true;
2532 if (rhs.type == DEREF)
2533 get_varinfo (rhs.var)->directly_dereferenced = true;
2536 if (!use_field_sensitive)
2542 /* ANYTHING == ANYTHING is pointless. */
2543 if (lhs.var == anything_id && rhs.var == anything_id)
2546 /* If we have &ANYTHING = something, convert to SOMETHING = &ANYTHING) */
2547 else if (lhs.var == anything_id && lhs.type == ADDRESSOF)
2552 process_constraint_1 (t, from_call);
2554 /* This can happen in our IR with things like n->a = *p */
2555 else if (rhs.type == DEREF && lhs.type == DEREF && rhs.var != anything_id)
2557 /* Split into tmp = *rhs, *lhs = tmp */
2558 tree rhsdecl = get_varinfo (rhs.var)->decl;
2559 tree pointertype = TREE_TYPE (rhsdecl);
2560 tree pointedtotype = TREE_TYPE (pointertype);
2561 tree tmpvar = create_tmp_var_raw (pointedtotype, "doubledereftmp");
2562 struct constraint_expr tmplhs = get_constraint_exp_from_ssa_var (tmpvar);
2564 /* If this is an aggregate of known size, we should have passed
2565 this off to do_structure_copy, and it should have broken it
2567 gcc_assert (!AGGREGATE_TYPE_P (pointedtotype)
2568 || get_varinfo (rhs.var)->is_unknown_size_var);
2570 process_constraint_1 (new_constraint (tmplhs, rhs), from_call);
2571 process_constraint_1 (new_constraint (lhs, tmplhs), from_call);
2573 else if (rhs.type == ADDRESSOF && lhs.type == DEREF)
2575 /* Split into tmp = &rhs, *lhs = tmp */
2576 tree rhsdecl = get_varinfo (rhs.var)->decl;
2577 tree pointertype = TREE_TYPE (rhsdecl);
2578 tree tmpvar = create_tmp_var_raw (pointertype, "derefaddrtmp");
2579 struct constraint_expr tmplhs = get_constraint_exp_from_ssa_var (tmpvar);
2581 process_constraint_1 (new_constraint (tmplhs, rhs), from_call);
2582 process_constraint_1 (new_constraint (lhs, tmplhs), from_call);
2586 gcc_assert (rhs.type != ADDRESSOF || rhs.offset == 0);
2587 VEC_safe_push (constraint_t, heap, constraints, t);
2592 /* Process constraint T, performing various simplifications and then
2593 adding it to our list of overall constraints. */
2596 process_constraint (constraint_t t)
2598 process_constraint_1 (t, false);
2601 /* Return true if T is a variable of a type that could contain
2605 could_have_pointers (tree t)
2607 tree type = TREE_TYPE (t);
2609 if (POINTER_TYPE_P (type)
2610 || AGGREGATE_TYPE_P (type)
2611 || TREE_CODE (type) == COMPLEX_TYPE)
2617 /* Return the position, in bits, of FIELD_DECL from the beginning of its
2620 static unsigned HOST_WIDE_INT
2621 bitpos_of_field (const tree fdecl)
2624 if (TREE_CODE (DECL_FIELD_OFFSET (fdecl)) != INTEGER_CST
2625 || TREE_CODE (DECL_FIELD_BIT_OFFSET (fdecl)) != INTEGER_CST)
2628 return (tree_low_cst (DECL_FIELD_OFFSET (fdecl), 1) * 8)
2629 + tree_low_cst (DECL_FIELD_BIT_OFFSET (fdecl), 1);
2633 /* Return true if an access to [ACCESSPOS, ACCESSSIZE]
2634 overlaps with a field at [FIELDPOS, FIELDSIZE] */
2637 offset_overlaps_with_access (const unsigned HOST_WIDE_INT fieldpos,
2638 const unsigned HOST_WIDE_INT fieldsize,
2639 const unsigned HOST_WIDE_INT accesspos,
2640 const unsigned HOST_WIDE_INT accesssize)
2642 if (fieldpos == accesspos && fieldsize == accesssize)
2644 if (accesspos >= fieldpos && accesspos < (fieldpos + fieldsize))
2646 if (accesspos < fieldpos && (accesspos + accesssize > fieldpos))
2652 /* Given a COMPONENT_REF T, return the constraint_expr for it. */
2655 get_constraint_for_component_ref (tree t, VEC(ce_s, heap) **results)
2658 HOST_WIDE_INT bitsize = -1;
2659 HOST_WIDE_INT bitmaxsize = -1;
2660 HOST_WIDE_INT bitpos;
2662 struct constraint_expr *result;
2663 unsigned int beforelength = VEC_length (ce_s, *results);
2665 /* Some people like to do cute things like take the address of
2668 while (!SSA_VAR_P (forzero) && !CONSTANT_CLASS_P (forzero))
2669 forzero = TREE_OPERAND (forzero, 0);
2671 if (CONSTANT_CLASS_P (forzero) && integer_zerop (forzero))
2673 struct constraint_expr temp;
2676 temp.var = integer_id;
2678 VEC_safe_push (ce_s, heap, *results, &temp);
2682 t = get_ref_base_and_extent (t, &bitpos, &bitsize, &bitmaxsize);
2684 /* String constants are readonly, so there is nothing to really do
2686 if (TREE_CODE (t) == STRING_CST)
2689 get_constraint_for (t, results);
2690 result = VEC_last (ce_s, *results);
2691 result->offset = bitpos;
2693 gcc_assert (beforelength + 1 == VEC_length (ce_s, *results));
2695 /* This can also happen due to weird offsetof type macros. */
2696 if (TREE_CODE (t) != ADDR_EXPR && result->type == ADDRESSOF)
2697 result->type = SCALAR;
2699 if (result->type == SCALAR)
2701 /* In languages like C, you can access one past the end of an
2702 array. You aren't allowed to dereference it, so we can
2703 ignore this constraint. When we handle pointer subtraction,
2704 we may have to do something cute here. */
2706 if (result->offset < get_varinfo (result->var)->fullsize
2709 /* It's also not true that the constraint will actually start at the
2710 right offset, it may start in some padding. We only care about
2711 setting the constraint to the first actual field it touches, so
2714 for (curr = get_varinfo (result->var); curr; curr = curr->next)
2716 if (offset_overlaps_with_access (curr->offset, curr->size,
2717 result->offset, bitmaxsize))
2719 result->var = curr->id;
2723 /* assert that we found *some* field there. The user couldn't be
2724 accessing *only* padding. */
2725 /* Still the user could access one past the end of an array
2726 embedded in a struct resulting in accessing *only* padding. */
2727 gcc_assert (curr || ref_contains_array_ref (orig_t));
2729 else if (bitmaxsize == 0)
2731 if (dump_file && (dump_flags & TDF_DETAILS))
2732 fprintf (dump_file, "Access to zero-sized part of variable,"
2736 if (dump_file && (dump_flags & TDF_DETAILS))
2737 fprintf (dump_file, "Access to past the end of variable, ignoring\n");
2741 else if (bitmaxsize == -1)
2743 /* We can't handle DEREF constraints with unknown size, we'll
2744 get the wrong answer. Punt and return anything. */
2745 result->var = anything_id;
2751 /* Dereference the constraint expression CONS, and return the result.
2752 DEREF (ADDRESSOF) = SCALAR
2753 DEREF (SCALAR) = DEREF
2754 DEREF (DEREF) = (temp = DEREF1; result = DEREF(temp))
2755 This is needed so that we can handle dereferencing DEREF constraints. */
2758 do_deref (VEC (ce_s, heap) **constraints)
2760 struct constraint_expr *c;
2763 for (i = 0; VEC_iterate (ce_s, *constraints, i, c); i++)
2765 if (c->type == SCALAR)
2767 else if (c->type == ADDRESSOF)
2769 else if (c->type == DEREF)
2771 tree tmpvar = create_tmp_var_raw (ptr_type_node, "dereftmp");
2772 struct constraint_expr tmplhs = get_constraint_exp_from_ssa_var (tmpvar);
2773 process_constraint (new_constraint (tmplhs, *c));
2774 c->var = tmplhs.var;
2781 /* Given a tree T, return the constraint expression for it. */
2784 get_constraint_for (tree t, VEC (ce_s, heap) **results)
2786 struct constraint_expr temp;
2788 /* x = integer is all glommed to a single variable, which doesn't
2789 point to anything by itself. That is, of course, unless it is an
2790 integer constant being treated as a pointer, in which case, we
2791 will return that this is really the addressof anything. This
2792 happens below, since it will fall into the default case. The only
2793 case we know something about an integer treated like a pointer is
2794 when it is the NULL pointer, and then we just say it points to
2796 if (TREE_CODE (t) == INTEGER_CST
2797 && integer_zerop (t))
2799 temp.var = nothing_id;
2800 temp.type = ADDRESSOF;
2802 VEC_safe_push (ce_s, heap, *results, &temp);
2806 switch (TREE_CODE_CLASS (TREE_CODE (t)))
2808 case tcc_expression:
2811 switch (TREE_CODE (t))
2815 struct constraint_expr *c;
2817 tree exp = TREE_OPERAND (t, 0);
2818 tree pttype = TREE_TYPE (TREE_TYPE (t));
2820 get_constraint_for (exp, results);
2823 /* Complex types are special. Taking the address of one
2824 allows you to access either part of it through that
2826 if (VEC_length (ce_s, *results) == 1 &&
2827 TREE_CODE (pttype) == COMPLEX_TYPE)
2829 struct constraint_expr *origrhs;
2831 struct constraint_expr tmp;
2833 gcc_assert (VEC_length (ce_s, *results) == 1);
2834 origrhs = VEC_last (ce_s, *results);
2836 VEC_pop (ce_s, *results);
2837 origvar = get_varinfo (origrhs->var);
2838 for (; origvar; origvar = origvar->next)
2840 tmp.var = origvar->id;
2841 VEC_safe_push (ce_s, heap, *results, &tmp);
2845 for (i = 0; VEC_iterate (ce_s, *results, i, c); i++)
2847 if (c->type == DEREF)
2850 c->type = ADDRESSOF;
2856 /* XXX: In interprocedural mode, if we didn't have the
2857 body, we would need to do *each pointer argument =
2859 if (call_expr_flags (t) & (ECF_MALLOC | ECF_MAY_BE_ALLOCA))
2862 tree heapvar = heapvar_lookup (t);
2864 if (heapvar == NULL)
2866 heapvar = create_tmp_var_raw (ptr_type_node, "HEAP");
2867 DECL_EXTERNAL (heapvar) = 1;
2868 get_var_ann (heapvar)->is_heapvar = 1;
2869 if (gimple_referenced_vars (cfun))
2870 add_referenced_var (heapvar);
2871 heapvar_insert (t, heapvar);
2874 temp.var = create_variable_info_for (heapvar,
2875 alias_get_name (heapvar));
2877 vi = get_varinfo (temp.var);
2878 vi->is_artificial_var = 1;
2879 vi->is_heap_var = 1;
2880 temp.type = ADDRESSOF;
2882 VEC_safe_push (ce_s, heap, *results, &temp);
2887 temp.var = anything_id;
2890 VEC_safe_push (ce_s, heap, *results, &temp);
2896 temp.type = ADDRESSOF;
2897 temp.var = anything_id;
2899 VEC_safe_push (ce_s, heap, *results, &temp);
2906 switch (TREE_CODE (t))
2910 get_constraint_for (TREE_OPERAND (t, 0), results);
2915 case ARRAY_RANGE_REF:
2917 get_constraint_for_component_ref (t, results);
2921 temp.type = ADDRESSOF;
2922 temp.var = anything_id;
2924 VEC_safe_push (ce_s, heap, *results, &temp);
2931 switch (TREE_CODE (t))
2935 case NON_LVALUE_EXPR:
2937 tree op = TREE_OPERAND (t, 0);
2939 /* Cast from non-pointer to pointers are bad news for us.
2940 Anything else, we see through */
2941 if (!(POINTER_TYPE_P (TREE_TYPE (t))
2942 && ! POINTER_TYPE_P (TREE_TYPE (op))))
2944 get_constraint_for (op, results);
2952 temp.type = ADDRESSOF;
2953 temp.var = anything_id;
2955 VEC_safe_push (ce_s, heap, *results, &temp);
2960 case tcc_exceptional:
2962 switch (TREE_CODE (t))
2966 get_constraint_for (PHI_RESULT (t), results);
2972 struct constraint_expr temp;
2973 temp = get_constraint_exp_from_ssa_var (t);
2974 VEC_safe_push (ce_s, heap, *results, &temp);
2980 temp.type = ADDRESSOF;
2981 temp.var = anything_id;
2983 VEC_safe_push (ce_s, heap, *results, &temp);
2988 case tcc_declaration:
2990 struct constraint_expr temp;
2991 temp = get_constraint_exp_from_ssa_var (t);
2992 VEC_safe_push (ce_s, heap, *results, &temp);
2997 temp.type = ADDRESSOF;
2998 temp.var = anything_id;
3000 VEC_safe_push (ce_s, heap, *results, &temp);
3007 /* Handle the structure copy case where we have a simple structure copy
3008 between LHS and RHS that is of SIZE (in bits)
3010 For each field of the lhs variable (lhsfield)
3011 For each field of the rhs variable at lhsfield.offset (rhsfield)
3012 add the constraint lhsfield = rhsfield
3014 If we fail due to some kind of type unsafety or other thing we
3015 can't handle, return false. We expect the caller to collapse the
3016 variable in that case. */
3019 do_simple_structure_copy (const struct constraint_expr lhs,
3020 const struct constraint_expr rhs,
3021 const unsigned HOST_WIDE_INT size)
3023 varinfo_t p = get_varinfo (lhs.var);
3024 unsigned HOST_WIDE_INT pstart, last;
3026 last = p->offset + size;
3027 for (; p && p->offset < last; p = p->next)
3030 struct constraint_expr templhs = lhs;
3031 struct constraint_expr temprhs = rhs;
3032 unsigned HOST_WIDE_INT fieldoffset;
3034 templhs.var = p->id;
3035 q = get_varinfo (temprhs.var);
3036 fieldoffset = p->offset - pstart;
3037 q = first_vi_for_offset (q, q->offset + fieldoffset);
3040 temprhs.var = q->id;
3041 process_constraint (new_constraint (templhs, temprhs));
3047 /* Handle the structure copy case where we have a structure copy between a
3048 aggregate on the LHS and a dereference of a pointer on the RHS
3049 that is of SIZE (in bits)
3051 For each field of the lhs variable (lhsfield)
3052 rhs.offset = lhsfield->offset
3053 add the constraint lhsfield = rhs
3057 do_rhs_deref_structure_copy (const struct constraint_expr lhs,
3058 const struct constraint_expr rhs,
3059 const unsigned HOST_WIDE_INT size)
3061 varinfo_t p = get_varinfo (lhs.var);
3062 unsigned HOST_WIDE_INT pstart,last;
3064 last = p->offset + size;
3066 for (; p && p->offset < last; p = p->next)
3069 struct constraint_expr templhs = lhs;
3070 struct constraint_expr temprhs = rhs;
3071 unsigned HOST_WIDE_INT fieldoffset;
3074 if (templhs.type == SCALAR)
3075 templhs.var = p->id;
3077 templhs.offset = p->offset;
3079 q = get_varinfo (temprhs.var);
3080 fieldoffset = p->offset - pstart;
3081 temprhs.offset += fieldoffset;
3082 process_constraint (new_constraint (templhs, temprhs));
3086 /* Handle the structure copy case where we have a structure copy
3087 between an aggregate on the RHS and a dereference of a pointer on
3088 the LHS that is of SIZE (in bits)
3090 For each field of the rhs variable (rhsfield)
3091 lhs.offset = rhsfield->offset
3092 add the constraint lhs = rhsfield
3096 do_lhs_deref_structure_copy (const struct constraint_expr lhs,
3097 const struct constraint_expr rhs,
3098 const unsigned HOST_WIDE_INT size)
3100 varinfo_t p = get_varinfo (rhs.var);
3101 unsigned HOST_WIDE_INT pstart,last;
3103 last = p->offset + size;
3105 for (; p && p->offset < last; p = p->next)
3108 struct constraint_expr templhs = lhs;
3109 struct constraint_expr temprhs = rhs;
3110 unsigned HOST_WIDE_INT fieldoffset;
3113 if (temprhs.type == SCALAR)
3114 temprhs.var = p->id;
3116 temprhs.offset = p->offset;
3118 q = get_varinfo (templhs.var);
3119 fieldoffset = p->offset - pstart;
3120 templhs.offset += fieldoffset;
3121 process_constraint (new_constraint (templhs, temprhs));
3125 /* Sometimes, frontends like to give us bad type information. This
3126 function will collapse all the fields from VAR to the end of VAR,
3127 into VAR, so that we treat those fields as a single variable.
3128 We return the variable they were collapsed into. */
3131 collapse_rest_of_var (unsigned int var)
3133 varinfo_t currvar = get_varinfo (var);
3136 for (field = currvar->next; field; field = field->next)
3139 fprintf (dump_file, "Type safety: Collapsing var %s into %s\n",
3140 field->name, currvar->name);
3142 gcc_assert (!field->collapsed_to);
3143 field->collapsed_to = currvar;
3146 currvar->next = NULL;
3147 currvar->size = currvar->fullsize - currvar->offset;
3152 /* Handle aggregate copies by expanding into copies of the respective
3153 fields of the structures. */
3156 do_structure_copy (tree lhsop, tree rhsop)
3158 struct constraint_expr lhs, rhs, tmp;
3159 VEC (ce_s, heap) *lhsc = NULL, *rhsc = NULL;
3161 unsigned HOST_WIDE_INT lhssize;
3162 unsigned HOST_WIDE_INT rhssize;
3164 get_constraint_for (lhsop, &lhsc);
3165 get_constraint_for (rhsop, &rhsc);
3166 gcc_assert (VEC_length (ce_s, lhsc) == 1);
3167 gcc_assert (VEC_length (ce_s, rhsc) == 1);
3168 lhs = *(VEC_last (ce_s, lhsc));
3169 rhs = *(VEC_last (ce_s, rhsc));
3171 VEC_free (ce_s, heap, lhsc);
3172 VEC_free (ce_s, heap, rhsc);
3174 /* If we have special var = x, swap it around. */
3175 if (lhs.var <= integer_id && !(get_varinfo (rhs.var)->is_special_var))
3182 /* This is fairly conservative for the RHS == ADDRESSOF case, in that it's
3183 possible it's something we could handle. However, most cases falling
3184 into this are dealing with transparent unions, which are slightly
3186 if (rhs.type == ADDRESSOF && !(get_varinfo (rhs.var)->is_special_var))
3188 rhs.type = ADDRESSOF;
3189 rhs.var = anything_id;
3192 /* If the RHS is a special var, or an addressof, set all the LHS fields to
3193 that special var. */
3194 if (rhs.var <= integer_id)
3196 for (p = get_varinfo (lhs.var); p; p = p->next)
3198 struct constraint_expr templhs = lhs;
3199 struct constraint_expr temprhs = rhs;
3201 if (templhs.type == SCALAR )
3202 templhs.var = p->id;
3204 templhs.offset += p->offset;
3205 process_constraint (new_constraint (templhs, temprhs));
3210 tree rhstype = TREE_TYPE (rhsop);
3211 tree lhstype = TREE_TYPE (lhsop);
3215 lhstypesize = DECL_P (lhsop) ? DECL_SIZE (lhsop) : TYPE_SIZE (lhstype);
3216 rhstypesize = DECL_P (rhsop) ? DECL_SIZE (rhsop) : TYPE_SIZE (rhstype);
3218 /* If we have a variably sized types on the rhs or lhs, and a deref
3219 constraint, add the constraint, lhsconstraint = &ANYTHING.
3220 This is conservatively correct because either the lhs is an unknown
3221 sized var (if the constraint is SCALAR), or the lhs is a DEREF
3222 constraint, and every variable it can point to must be unknown sized
3223 anyway, so we don't need to worry about fields at all. */
3224 if ((rhs.type == DEREF && TREE_CODE (rhstypesize) != INTEGER_CST)
3225 || (lhs.type == DEREF && TREE_CODE (lhstypesize) != INTEGER_CST))
3227 rhs.var = anything_id;
3228 rhs.type = ADDRESSOF;
3230 process_constraint (new_constraint (lhs, rhs));
3234 /* The size only really matters insofar as we don't set more or less of
3235 the variable. If we hit an unknown size var, the size should be the
3236 whole darn thing. */
3237 if (get_varinfo (rhs.var)->is_unknown_size_var)
3240 rhssize = TREE_INT_CST_LOW (rhstypesize);
3242 if (get_varinfo (lhs.var)->is_unknown_size_var)
3245 lhssize = TREE_INT_CST_LOW (lhstypesize);
3248 if (rhs.type == SCALAR && lhs.type == SCALAR)
3250 if (!do_simple_structure_copy (lhs, rhs, MIN (lhssize, rhssize)))
3252 lhs.var = collapse_rest_of_var (lhs.var);
3253 rhs.var = collapse_rest_of_var (rhs.var);
3258 process_constraint (new_constraint (lhs, rhs));
3261 else if (lhs.type != DEREF && rhs.type == DEREF)
3262 do_rhs_deref_structure_copy (lhs, rhs, MIN (lhssize, rhssize));
3263 else if (lhs.type == DEREF && rhs.type != DEREF)
3264 do_lhs_deref_structure_copy (lhs, rhs, MIN (lhssize, rhssize));
3267 tree pointedtotype = lhstype;
3270 gcc_assert (rhs.type == DEREF && lhs.type == DEREF);
3271 tmpvar = create_tmp_var_raw (pointedtotype, "structcopydereftmp");
3272 do_structure_copy (tmpvar, rhsop);
3273 do_structure_copy (lhsop, tmpvar);
3279 /* Update related alias information kept in AI. This is used when
3280 building name tags, alias sets and deciding grouping heuristics.
3281 STMT is the statement to process. This function also updates
3282 ADDRESSABLE_VARS. */
3285 update_alias_info (tree stmt, struct alias_info *ai)
3288 use_operand_p use_p;
3290 bool stmt_dereferences_ptr_p;
3291 enum escape_type stmt_escape_type = is_escape_site (stmt);
3292 struct mem_ref_stats_d *mem_ref_stats = gimple_mem_ref_stats (cfun);
3294 stmt_dereferences_ptr_p = false;
3296 if (stmt_escape_type == ESCAPE_TO_CALL
3297 || stmt_escape_type == ESCAPE_TO_PURE_CONST)
3299 mem_ref_stats->num_call_sites++;
3300 if (stmt_escape_type == ESCAPE_TO_PURE_CONST)
3301 mem_ref_stats->num_pure_const_call_sites++;
3303 else if (stmt_escape_type == ESCAPE_TO_ASM)
3304 mem_ref_stats->num_asm_sites++;
3306 /* Mark all the variables whose address are taken by the statement. */
3307 addr_taken = addresses_taken (stmt);
3310 bitmap_ior_into (gimple_addressable_vars (cfun), addr_taken);
3312 /* If STMT is an escape point, all the addresses taken by it are
3314 if (stmt_escape_type != NO_ESCAPE)
3316 referenced_var_iterator ri;
3319 FOR_EACH_REFERENCED_VAR_IN_BITMAP (addr_taken, rvar, ri)
3321 if (!unmodifiable_var_p (rvar))
3322 mark_call_clobbered (rvar, stmt_escape_type);
3327 /* Process each operand use. For pointers, determine whether they
3328 are dereferenced by the statement, or whether their value
3330 FOR_EACH_PHI_OR_STMT_USE (use_p, stmt, iter, SSA_OP_USE)
3334 struct ptr_info_def *pi;
3335 unsigned num_uses, num_loads, num_stores;
3337 op = USE_FROM_PTR (use_p);
3339 /* If STMT is a PHI node, OP may be an ADDR_EXPR. If so, add it
3340 to the set of addressable variables. */
3341 if (TREE_CODE (op) == ADDR_EXPR)
3343 bitmap addressable_vars = gimple_addressable_vars (cfun);
3345 gcc_assert (TREE_CODE (stmt) == PHI_NODE);
3346 gcc_assert (addressable_vars);
3348 /* PHI nodes don't have annotations for pinning the set
3349 of addresses taken, so we collect them here.
3351 FIXME, should we allow PHI nodes to have annotations
3352 so that they can be treated like regular statements?
3353 Currently, they are treated as second-class
3355 add_to_addressable_set (TREE_OPERAND (op, 0), &addressable_vars);
3359 /* Ignore constants (they may occur in PHI node arguments). */
3360 if (TREE_CODE (op) != SSA_NAME)
3363 var = SSA_NAME_VAR (op);
3364 v_ann = var_ann (var);
3366 /* The base variable of an SSA name must be a GIMPLE register, and thus
3367 it cannot be aliased. */
3368 gcc_assert (!may_be_aliased (var));
3370 /* We are only interested in pointers. */
3371 if (!POINTER_TYPE_P (TREE_TYPE (op)))
3374 pi = get_ptr_info (op);
3376 /* Add OP to AI->PROCESSED_PTRS, if it's not there already. */
3377 if (!TEST_BIT (ai->ssa_names_visited, SSA_NAME_VERSION (op)))
3379 SET_BIT (ai->ssa_names_visited, SSA_NAME_VERSION (op));
3380 VEC_safe_push (tree, heap, ai->processed_ptrs, op);
3383 /* If STMT is a PHI node, then it will not have pointer
3384 dereferences and it will not be an escape point. */
3385 if (TREE_CODE (stmt) == PHI_NODE)
3388 /* Determine whether OP is a dereferenced pointer, and if STMT
3389 is an escape point, whether OP escapes. */
3390 count_uses_and_derefs (op, stmt, &num_uses, &num_loads, &num_stores);
3392 /* Handle a corner case involving address expressions of the
3393 form '&PTR->FLD'. The problem with these expressions is that
3394 they do not represent a dereference of PTR. However, if some
3395 other transformation propagates them into an INDIRECT_REF
3396 expression, we end up with '*(&PTR->FLD)' which is folded
3399 So, if the original code had no other dereferences of PTR,
3400 the aliaser will not create memory tags for it, and when
3401 &PTR->FLD gets propagated to INDIRECT_REF expressions, the
3402 memory operations will receive no VDEF/VUSE operands.
3404 One solution would be to have count_uses_and_derefs consider
3405 &PTR->FLD a dereference of PTR. But that is wrong, since it
3406 is not really a dereference but an offset calculation.
3408 What we do here is to recognize these special ADDR_EXPR
3409 nodes. Since these expressions are never GIMPLE values (they
3410 are not GIMPLE invariants), they can only appear on the RHS
3411 of an assignment and their base address is always an
3412 INDIRECT_REF expression. */
3413 if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
3414 && TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == ADDR_EXPR
3415 && !is_gimple_val (GIMPLE_STMT_OPERAND (stmt, 1)))
3417 /* If the RHS if of the form &PTR->FLD and PTR == OP, then
3418 this represents a potential dereference of PTR. */
3419 tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
3420 tree base = get_base_address (TREE_OPERAND (rhs, 0));
3421 if (TREE_CODE (base) == INDIRECT_REF
3422 && TREE_OPERAND (base, 0) == op)
3426 if (num_loads + num_stores > 0)
3428 /* Mark OP as dereferenced. In a subsequent pass,
3429 dereferenced pointers that point to a set of
3430 variables will be assigned a name tag to alias
3431 all the variables OP points to. */
3432 pi->is_dereferenced = 1;
3434 /* If this is a store operation, mark OP as being
3435 dereferenced to store, otherwise mark it as being
3436 dereferenced to load. */
3438 pointer_set_insert (ai->dereferenced_ptrs_store, var);
3440 pointer_set_insert (ai->dereferenced_ptrs_load, var);
3442 /* Update the frequency estimate for all the dereferences of
3444 update_mem_sym_stats_from_stmt (op, stmt, num_loads, num_stores);
3446 /* Indicate that STMT contains pointer dereferences. */
3447 stmt_dereferences_ptr_p = true;
3450 if (stmt_escape_type != NO_ESCAPE && num_loads + num_stores < num_uses)
3452 /* If STMT is an escape point and STMT contains at
3453 least one direct use of OP, then the value of OP
3454 escapes and so the pointed-to variables need to
3455 be marked call-clobbered. */
3456 pi->value_escapes_p = 1;
3457 pi->escape_mask |= stmt_escape_type;
3459 /* If the statement makes a function call, assume
3460 that pointer OP will be dereferenced in a store
3461 operation inside the called function. */
3462 if (get_call_expr_in (stmt)
3463 || stmt_escape_type == ESCAPE_STORED_IN_GLOBAL)
3465 pointer_set_insert (ai->dereferenced_ptrs_store, var);
3466 pi->is_dereferenced = 1;
3471 if (TREE_CODE (stmt) == PHI_NODE)
3474 /* Mark stored variables in STMT as being written to and update the
3475 memory reference stats for all memory symbols referenced by STMT. */
3476 if (stmt_references_memory_p (stmt))
3478 referenced_var_iterator ri;
3481 mem_ref_stats->num_mem_stmts++;
3483 /* Notice that we only update memory reference stats for symbols
3484 loaded and stored by the statement if the statement does not
3485 contain pointer dereferences and it is not a call/asm site.
3486 This is to avoid double accounting problems when creating
3487 memory partitions. After computing points-to information,
3488 pointer dereference statistics are used to update the
3489 reference stats of the pointed-to variables, so here we
3490 should only update direct references to symbols.
3492 Indirect references are not updated here for two reasons: (1)
3493 The first time we compute alias information, the sets
3494 LOADED/STORED are empty for pointer dereferences, (2) After
3495 partitioning, LOADED/STORED may have references to
3496 partitions, not the original pointed-to variables. So, if we
3497 always counted LOADED/STORED here and during partitioning, we
3498 would count many symbols more than once.
3500 This does cause some imprecision when a statement has a
3501 combination of direct symbol references and pointer
3502 dereferences (e.g., MEMORY_VAR = *PTR) or if a call site has
3503 memory symbols in its argument list, but these cases do not
3504 occur so frequently as to constitute a serious problem. */
3505 if (STORED_SYMS (stmt))
3506 FOR_EACH_REFERENCED_VAR_IN_BITMAP (STORED_SYMS (stmt), sym, ri)
3508 pointer_set_insert (ai->written_vars, sym);
3509 if (!stmt_dereferences_ptr_p
3510 && stmt_escape_type != ESCAPE_TO_CALL
3511 && stmt_escape_type != ESCAPE_TO_PURE_CONST
3512 && stmt_escape_type != ESCAPE_TO_ASM)
3513 update_mem_sym_stats_from_stmt (sym, stmt, 0, 1);
3516 if (!stmt_dereferences_ptr_p
3517 && LOADED_SYMS (stmt)
3518 && stmt_escape_type != ESCAPE_TO_CALL
3519 && stmt_escape_type != ESCAPE_TO_PURE_CONST
3520 && stmt_escape_type != ESCAPE_TO_ASM)
3521 FOR_EACH_REFERENCED_VAR_IN_BITMAP (LOADED_SYMS (stmt), sym, ri)
3522 update_mem_sym_stats_from_stmt (sym, stmt, 1, 0);
3527 /* Handle pointer arithmetic EXPR when creating aliasing constraints.
3528 Expressions of the type PTR + CST can be handled in two ways:
3530 1- If the constraint for PTR is ADDRESSOF for a non-structure
3531 variable, then we can use it directly because adding or
3532 subtracting a constant may not alter the original ADDRESSOF
3533 constraint (i.e., pointer arithmetic may not legally go outside
3534 an object's boundaries).
3536 2- If the constraint for PTR is ADDRESSOF for a structure variable,
3537 then if CST is a compile-time constant that can be used as an
3538 offset, we can determine which sub-variable will be pointed-to
3541 Return true if the expression is handled. For any other kind of
3542 expression, return false so that each operand can be added as a
3543 separate constraint by the caller. */
3546 handle_ptr_arith (VEC (ce_s, heap) *lhsc, tree expr)
3549 struct constraint_expr *c, *c2;
3552 VEC (ce_s, heap) *temp = NULL;
3553 unsigned int rhsoffset = 0;
3554 bool unknown_addend = false;
3556 if (TREE_CODE (expr) != POINTER_PLUS_EXPR)
3559 op0 = TREE_OPERAND (expr, 0);
3560 op1 = TREE_OPERAND (expr, 1);
3561 gcc_assert (POINTER_TYPE_P (TREE_TYPE (op0)));
3563 get_constraint_for (op0, &temp);
3565 /* Handle non-constants by making constraints from integer. */
3566 if (TREE_CODE (op1) == INTEGER_CST)
3567 rhsoffset = TREE_INT_CST_LOW (op1) * BITS_PER_UNIT;
3569 unknown_addend = true;
3571 for (i = 0; VEC_iterate (ce_s, lhsc, i, c); i++)
3572 for (j = 0; VEC_iterate (ce_s, temp, j, c2); j++)
3574 if (c2->type == ADDRESSOF && rhsoffset != 0)
3576 varinfo_t temp = get_varinfo (c2->var);
3578 /* An access one after the end of an array is valid,
3579 so simply punt on accesses we cannot resolve. */
3580 temp = first_vi_for_offset (temp, rhsoffset);
3586 else if (unknown_addend)
3588 /* Can't handle *a + integer where integer is unknown. */
3589 if (c2->type != SCALAR)
3591 struct constraint_expr intc;
3592 intc.var = integer_id;
3595 process_constraint (new_constraint (*c, intc));
3599 /* We known it lives somewhere within c2->var. */
3600 varinfo_t tmp = get_varinfo (c2->var);
3601 for (; tmp; tmp = tmp->next)
3603 struct constraint_expr tmpc = *c2;
3606 process_constraint (new_constraint (*c, tmpc));
3611 c2->offset = rhsoffset;
3612 process_constraint (new_constraint (*c, *c2));
3615 VEC_free (ce_s, heap, temp);
3620 /* For non-IPA mode, generate constraints necessary for a call on the
3624 handle_rhs_call (tree rhs)
3627 call_expr_arg_iterator iter;
3628 struct constraint_expr rhsc;
3630 rhsc.var = anything_id;
3632 rhsc.type = ADDRESSOF;
3634 FOR_EACH_CALL_EXPR_ARG (arg, iter, rhs)
3636 VEC(ce_s, heap) *lhsc = NULL;
3638 /* Find those pointers being passed, and make sure they end up
3639 pointing to anything. */
3640 if (POINTER_TYPE_P (TREE_TYPE (arg)))
3643 struct constraint_expr *lhsp;
3645 get_constraint_for (arg, &lhsc);
3647 for (j = 0; VEC_iterate (ce_s, lhsc, j, lhsp); j++)
3648 process_constraint_1 (new_constraint (*lhsp, rhsc), true);
3649 VEC_free (ce_s, heap, lhsc);
3654 /* For non-IPA mode, generate constraints necessary for a call
3655 that returns a pointer and assigns it to LHS. This simply makes
3656 the LHS point to anything. */
3659 handle_lhs_call (tree lhs)
3661 VEC(ce_s, heap) *lhsc = NULL;
3662 struct constraint_expr rhsc;
3664 struct constraint_expr *lhsp;
3666 rhsc.var = anything_id;
3668 rhsc.type = ADDRESSOF;
3669 get_constraint_for (lhs, &lhsc);
3670 for (j = 0; VEC_iterate (ce_s, lhsc, j, lhsp); j++)
3671 process_constraint_1 (new_constraint (*lhsp, rhsc), true);
3672 VEC_free (ce_s, heap, lhsc);
3675 /* Walk statement T setting up aliasing constraints according to the
3676 references found in T. This function is the main part of the
3677 constraint builder. AI points to auxiliary alias information used
3678 when building alias sets and computing alias grouping heuristics. */
3681 find_func_aliases (tree origt)
3684 VEC(ce_s, heap) *lhsc = NULL;
3685 VEC(ce_s, heap) *rhsc = NULL;
3686 struct constraint_expr *c;
3688 if (TREE_CODE (t) == RETURN_EXPR && TREE_OPERAND (t, 0))
3689 t = TREE_OPERAND (t, 0);
3691 /* Now build constraints expressions. */
3692 if (TREE_CODE (t) == PHI_NODE)
3694 gcc_assert (!AGGREGATE_TYPE_P (TREE_TYPE (PHI_RESULT (t))));
3696 /* Only care about pointers and structures containing
3698 if (could_have_pointers (PHI_RESULT (t)))
3703 /* For a phi node, assign all the arguments to
3705 get_constraint_for (PHI_RESULT (t), &lhsc);
3706 for (i = 0; i < PHI_NUM_ARGS (t); i++)
3709 tree strippedrhs = PHI_ARG_DEF (t, i);
3711 STRIP_NOPS (strippedrhs);
3712 rhstype = TREE_TYPE (strippedrhs);
3713 get_constraint_for (PHI_ARG_DEF (t, i), &rhsc);
3715 for (j = 0; VEC_iterate (ce_s, lhsc, j, c); j++)
3717 struct constraint_expr *c2;
3718 while (VEC_length (ce_s, rhsc) > 0)
3720 c2 = VEC_last (ce_s, rhsc);
3721 process_constraint (new_constraint (*c, *c2));
3722 VEC_pop (ce_s, rhsc);
3728 /* In IPA mode, we need to generate constraints to pass call
3729 arguments through their calls. There are two cases, either a
3730 GIMPLE_MODIFY_STMT when we are returning a value, or just a plain
3731 CALL_EXPR when we are not.
3733 In non-ipa mode, we need to generate constraints for each
3734 pointer passed by address. */
3735 else if (((TREE_CODE (t) == GIMPLE_MODIFY_STMT
3736 && TREE_CODE (GIMPLE_STMT_OPERAND (t, 1)) == CALL_EXPR
3737 && !(call_expr_flags (GIMPLE_STMT_OPERAND (t, 1))
3738 & (ECF_MALLOC | ECF_MAY_BE_ALLOCA)))
3739 || (TREE_CODE (t) == CALL_EXPR
3740 && !(call_expr_flags (t)
3741 & (ECF_MALLOC | ECF_MAY_BE_ALLOCA)))))
3745 if (TREE_CODE (t) == GIMPLE_MODIFY_STMT)
3747 handle_rhs_call (GIMPLE_STMT_OPERAND (t, 1));
3748 if (POINTER_TYPE_P (TREE_TYPE (GIMPLE_STMT_OPERAND (t, 1))))
3749 handle_lhs_call (GIMPLE_STMT_OPERAND (t, 0));
3752 handle_rhs_call (t);
3759 call_expr_arg_iterator iter;
3763 if (TREE_CODE (t) == GIMPLE_MODIFY_STMT)
3765 lhsop = GIMPLE_STMT_OPERAND (t, 0);
3766 rhsop = GIMPLE_STMT_OPERAND (t, 1);
3773 decl = get_callee_fndecl (rhsop);
3775 /* If we can directly resolve the function being called, do so.
3776 Otherwise, it must be some sort of indirect expression that
3777 we should still be able to handle. */
3780 fi = get_vi_for_tree (decl);
3784 decl = CALL_EXPR_FN (rhsop);
3785 fi = get_vi_for_tree (decl);
3788 /* Assign all the passed arguments to the appropriate incoming
3789 parameters of the function. */
3791 FOR_EACH_CALL_EXPR_ARG (arg, iter, rhsop)
3793 struct constraint_expr lhs ;
3794 struct constraint_expr *rhsp;
3796 get_constraint_for (arg, &rhsc);
3797 if (TREE_CODE (decl) != FUNCTION_DECL)
3806 lhs.var = first_vi_for_offset (fi, i)->id;
3809 while (VEC_length (ce_s, rhsc) != 0)
3811 rhsp = VEC_last (ce_s, rhsc);
3812 process_constraint (new_constraint (lhs, *rhsp));
3813 VEC_pop (ce_s, rhsc);
3818 /* If we are returning a value, assign it to the result. */
3821 struct constraint_expr rhs;
3822 struct constraint_expr *lhsp;
3825 get_constraint_for (lhsop, &lhsc);
3826 if (TREE_CODE (decl) != FUNCTION_DECL)
3835 rhs.var = first_vi_for_offset (fi, i)->id;
3838 for (j = 0; VEC_iterate (ce_s, lhsc, j, lhsp); j++)
3839 process_constraint (new_constraint (*lhsp, rhs));
3843 /* Otherwise, just a regular assignment statement. */
3844 else if (TREE_CODE (t) == GIMPLE_MODIFY_STMT)
3846 tree lhsop = GIMPLE_STMT_OPERAND (t, 0);
3847 tree rhsop = GIMPLE_STMT_OPERAND (t, 1);
3850 if ((AGGREGATE_TYPE_P (TREE_TYPE (lhsop))
3851 || TREE_CODE (TREE_TYPE (lhsop)) == COMPLEX_TYPE)
3852 && (AGGREGATE_TYPE_P (TREE_TYPE (rhsop))
3853 || TREE_CODE (TREE_TYPE (lhsop)) == COMPLEX_TYPE))
3855 do_structure_copy (lhsop, rhsop);
3859 /* Only care about operations with pointers, structures
3860 containing pointers, dereferences, and call expressions. */
3861 if (could_have_pointers (lhsop)
3862 || TREE_CODE (rhsop) == CALL_EXPR)
3864 get_constraint_for (lhsop, &lhsc);
3865 switch (TREE_CODE_CLASS (TREE_CODE (rhsop)))
3867 /* RHS that consist of unary operations,
3868 exceptional types, or bare decls/constants, get
3869 handled directly by get_constraint_for. */
3871 case tcc_declaration:
3873 case tcc_exceptional:
3874 case tcc_expression:
3880 get_constraint_for (rhsop, &rhsc);
3881 for (j = 0; VEC_iterate (ce_s, lhsc, j, c); j++)
3883 struct constraint_expr *c2;
3886 for (k = 0; VEC_iterate (ce_s, rhsc, k, c2); k++)
3887 process_constraint (new_constraint (*c, *c2));
3895 /* For pointer arithmetic of the form
3896 PTR + CST, we can simply use PTR's
3897 constraint because pointer arithmetic is
3898 not allowed to go out of bounds. */
3899 if (handle_ptr_arith (lhsc, rhsop))
3904 /* Otherwise, walk each operand. Notice that we
3905 can't use the operand interface because we need
3906 to process expressions other than simple operands
3907 (e.g. INDIRECT_REF, ADDR_EXPR, CALL_EXPR). */
3909 for (i = 0; i < TREE_OPERAND_LENGTH (rhsop); i++)
3911 tree op = TREE_OPERAND (rhsop, i);
3914 gcc_assert (VEC_length (ce_s, rhsc) == 0);
3915 get_constraint_for (op, &rhsc);
3916 for (j = 0; VEC_iterate (ce_s, lhsc, j, c); j++)
3918 struct constraint_expr *c2;
3919 while (VEC_length (ce_s, rhsc) > 0)
3921 c2 = VEC_last (ce_s, rhsc);
3922 process_constraint (new_constraint (*c, *c2));
3923 VEC_pop (ce_s, rhsc);
3931 else if (TREE_CODE (t) == CHANGE_DYNAMIC_TYPE_EXPR)
3935 get_constraint_for (CHANGE_DYNAMIC_TYPE_LOCATION (t), &lhsc);
3936 for (j = 0; VEC_iterate (ce_s, lhsc, j, c); ++j)
3937 get_varinfo (c->var)->no_tbaa_pruning = true;
3940 /* After promoting variables and computing aliasing we will
3941 need to re-scan most statements. FIXME: Try to minimize the
3942 number of statements re-scanned. It's not really necessary to
3943 re-scan *all* statements. */
3944 mark_stmt_modified (origt);
3945 VEC_free (ce_s, heap, rhsc);
3946 VEC_free (ce_s, heap, lhsc);
3950 /* Find the first varinfo in the same variable as START that overlaps with
3952 Effectively, walk the chain of fields for the variable START to find the
3953 first field that overlaps with OFFSET.
3954 Return NULL if we can't find one. */
3957 first_vi_for_offset (varinfo_t start, unsigned HOST_WIDE_INT offset)
3959 varinfo_t curr = start;
3962 /* We may not find a variable in the field list with the actual
3963 offset when when we have glommed a structure to a variable.
3964 In that case, however, offset should still be within the size
3966 if (offset >= curr->offset && offset < (curr->offset + curr->size))
3974 /* Insert the varinfo FIELD into the field list for BASE, at the front
3978 insert_into_field_list (varinfo_t base, varinfo_t field)
3980 varinfo_t prev = base;
3981 varinfo_t curr = base->next;
3987 /* Insert the varinfo FIELD into the field list for BASE, ordered by
3991 insert_into_field_list_sorted (varinfo_t base, varinfo_t field)
3993 varinfo_t prev = base;
3994 varinfo_t curr = base->next;
4005 if (field->offset <= curr->offset)
4010 field->next = prev->next;
4015 /* qsort comparison function for two fieldoff's PA and PB */
4018 fieldoff_compare (const void *pa, const void *pb)
4020 const fieldoff_s *foa = (const fieldoff_s *)pa;
4021 const fieldoff_s *fob = (const fieldoff_s *)pb;
4022 HOST_WIDE_INT foasize, fobsize;
4024 if (foa->offset != fob->offset)
4025 return foa->offset - fob->offset;
4027 foasize = TREE_INT_CST_LOW (foa->size);
4028 fobsize = TREE_INT_CST_LOW (fob->size);
4029 return foasize - fobsize;
4032 /* Sort a fieldstack according to the field offset and sizes. */
4034 sort_fieldstack (VEC(fieldoff_s,heap) *fieldstack)
4036 qsort (VEC_address (fieldoff_s, fieldstack),
4037 VEC_length (fieldoff_s, fieldstack),
4038 sizeof (fieldoff_s),
4042 /* Given a TYPE, and a vector of field offsets FIELDSTACK, push all
4043 the fields of TYPE onto fieldstack, recording their offsets along
4046 OFFSET is used to keep track of the offset in this entire
4047 structure, rather than just the immediately containing structure.
4048 Returns the number of fields pushed.
4050 HAS_UNION is set to true if we find a union type as a field of
4053 ADDRESSABLE_TYPE is the type of the outermost object that could
4054 have its address taken. */
4057 push_fields_onto_fieldstack (tree type, VEC(fieldoff_s,heap) **fieldstack,
4058 HOST_WIDE_INT offset, bool *has_union,
4059 tree addressable_type)
4063 unsigned int first_element = VEC_length (fieldoff_s, *fieldstack);
4065 /* If the vector of fields is growing too big, bail out early.
4066 Callers check for VEC_length <= MAX_FIELDS_FOR_FIELD_SENSITIVE, make
4068 if (first_element > MAX_FIELDS_FOR_FIELD_SENSITIVE)
4071 if (TREE_CODE (type) == COMPLEX_TYPE)
4073 fieldoff_s *real_part, *img_part;
4074 real_part = VEC_safe_push (fieldoff_s, heap, *fieldstack, NULL);
4075 real_part->type = TREE_TYPE (type);
4076 real_part->size = TYPE_SIZE (TREE_TYPE (type));
4077 real_part->offset = offset;
4078 real_part->decl = NULL_TREE;
4079 real_part->alias_set = -1;
4080 real_part->base_for_components = false;
4082 img_part = VEC_safe_push (fieldoff_s, heap, *fieldstack, NULL);
4083 img_part->type = TREE_TYPE (type);
4084 img_part->size = TYPE_SIZE (TREE_TYPE (type));
4085 img_part->offset = offset + TREE_INT_CST_LOW (TYPE_SIZE (TREE_TYPE (type)));
4086 img_part->decl = NULL_TREE;
4087 img_part->alias_set = -1;
4088 img_part->base_for_components = false;
4093 else if (TREE_CODE (type) == ARRAY_TYPE)
4095 tree sz = TYPE_SIZE (type);
4096 tree elsz = TYPE_SIZE (TREE_TYPE (type));
4101 || ! host_integerp (sz, 1)
4102 || TREE_INT_CST_LOW (sz) == 0
4104 || ! host_integerp (elsz, 1)
4105 || TREE_INT_CST_LOW (elsz) == 0)
4108 nr = TREE_INT_CST_LOW (sz) / TREE_INT_CST_LOW (elsz);
4109 if (nr > SALIAS_MAX_ARRAY_ELEMENTS)
4112 for (i = 0; i < nr; ++i)
4118 && (TREE_CODE (TREE_TYPE (type)) == QUAL_UNION_TYPE
4119 || TREE_CODE (TREE_TYPE (type)) == UNION_TYPE))
4122 if (!AGGREGATE_TYPE_P (TREE_TYPE (type))) /* var_can_have_subvars */
4124 else if (!(pushed = push_fields_onto_fieldstack
4127 offset + i * TREE_INT_CST_LOW (elsz),
4129 (TYPE_NONALIASED_COMPONENT (type)
4131 : TREE_TYPE (type)))))
4132 /* Empty structures may have actual size, like in C++. So
4133 see if we didn't push any subfields and the size is
4134 nonzero, push the field onto the stack */
4141 pair = VEC_safe_push (fieldoff_s, heap, *fieldstack, NULL);
4142 pair->type = TREE_TYPE (type);
4144 pair->decl = NULL_TREE;
4145 pair->offset = offset + i * TREE_INT_CST_LOW (elsz);
4146 if (TYPE_NONALIASED_COMPONENT (type))
4147 pair->alias_set = get_alias_set (addressable_type);
4149 pair->alias_set = -1;
4150 pair->base_for_components = false;
4160 for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
4161 if (TREE_CODE (field) == FIELD_DECL)
4167 && (TREE_CODE (TREE_TYPE (field)) == QUAL_UNION_TYPE
4168 || TREE_CODE (TREE_TYPE (field)) == UNION_TYPE))
4171 if (!var_can_have_subvars (field))
4173 else if (!(pushed = push_fields_onto_fieldstack
4176 offset + bitpos_of_field (field),
4178 (DECL_NONADDRESSABLE_P (field)
4180 : TREE_TYPE (field))))
4181 && DECL_SIZE (field)
4182 && !integer_zerop (DECL_SIZE (field)))
4183 /* Empty structures may have actual size, like in C++. So
4184 see if we didn't push any subfields and the size is
4185 nonzero, push the field onto the stack */
4192 pair = VEC_safe_push (fieldoff_s, heap, *fieldstack, NULL);
4193 pair->type = TREE_TYPE (field);
4194 pair->size = DECL_SIZE (field);
4196 pair->offset = offset + bitpos_of_field (field);
4197 if (DECL_NONADDRESSABLE_P (field))
4198 pair->alias_set = get_alias_set (addressable_type);
4200 pair->alias_set = -1;
4201 pair->base_for_components = false;
4209 /* Make sure the first pushed field is marked as eligible for
4210 being a base for component references. */
4212 VEC_index (fieldoff_s, *fieldstack, first_element)->base_for_components = true;
4217 /* Create a constraint from ANYTHING variable to VI. */
4219 make_constraint_from_anything (varinfo_t vi)
4221 struct constraint_expr lhs, rhs;
4227 rhs.var = anything_id;
4229 rhs.type = ADDRESSOF;
4230 process_constraint (new_constraint (lhs, rhs));
4233 /* Count the number of arguments DECL has, and set IS_VARARGS to true
4234 if it is a varargs function. */
4237 count_num_arguments (tree decl, bool *is_varargs)
4242 for (t = TYPE_ARG_TYPES (TREE_TYPE (decl));
4246 if (TREE_VALUE (t) == void_type_node)
4256 /* Creation function node for DECL, using NAME, and return the index
4257 of the variable we've created for the function. */
4260 create_function_info_for (tree decl, const char *name)
4262 unsigned int index = VEC_length (varinfo_t, varmap);
4266 bool is_varargs = false;
4268 /* Create the variable info. */
4270 vi = new_var_info (decl, index, name);
4275 vi->fullsize = count_num_arguments (decl, &is_varargs) + 1;
4276 insert_vi_for_tree (vi->decl, vi);
4277 VEC_safe_push (varinfo_t, heap, varmap, vi);
4281 /* If it's varargs, we don't know how many arguments it has, so we
4288 vi->is_unknown_size_var = true;
4293 arg = DECL_ARGUMENTS (decl);
4295 /* Set up variables for each argument. */
4296 for (i = 1; i < vi->fullsize; i++)
4299 const char *newname;
4301 unsigned int newindex;
4302 tree argdecl = decl;
4307 newindex = VEC_length (varinfo_t, varmap);
4308 asprintf (&tempname, "%s.arg%d", name, i-1);
4309 newname = ggc_strdup (tempname);
4312 argvi = new_var_info (argdecl, newindex, newname);
4313 argvi->decl = argdecl;
4314 VEC_safe_push (varinfo_t, heap, varmap, argvi);
4317 argvi->fullsize = vi->fullsize;
4318 argvi->has_union = false;
4319 insert_into_field_list_sorted (vi, argvi);
4320 stats.total_vars ++;
4323 insert_vi_for_tree (arg, argvi);
4324 arg = TREE_CHAIN (arg);
4328 /* Create a variable for the return var. */
4329 if (DECL_RESULT (decl) != NULL
4330 || !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (decl))))
4333 const char *newname;
4335 unsigned int newindex;
4336 tree resultdecl = decl;
4340 if (DECL_RESULT (decl))
4341 resultdecl = DECL_RESULT (decl);
4343 newindex = VEC_length (varinfo_t, varmap);
4344 asprintf (&tempname, "%s.result", name);
4345 newname = ggc_strdup (tempname);
4348 resultvi = new_var_info (resultdecl, newindex, newname);
4349 resultvi->decl = resultdecl;
4350 VEC_safe_push (varinfo_t, heap, varmap, resultvi);
4351 resultvi->offset = i;
4353 resultvi->fullsize = vi->fullsize;
4354 resultvi->has_union = false;
4355 insert_into_field_list_sorted (vi, resultvi);
4356 stats.total_vars ++;
4357 if (DECL_RESULT (decl))
4358 insert_vi_for_tree (DECL_RESULT (decl), resultvi);
4364 /* Return true if FIELDSTACK contains fields that overlap.
4365 FIELDSTACK is assumed to be sorted by offset. */
4368 check_for_overlaps (VEC (fieldoff_s,heap) *fieldstack)
4370 fieldoff_s *fo = NULL;
4372 HOST_WIDE_INT lastoffset = -1;
4374 for (i = 0; VEC_iterate (fieldoff_s, fieldstack, i, fo); i++)
4376 if (fo->offset == lastoffset)
4378 lastoffset = fo->offset;
4383 /* Create a varinfo structure for NAME and DECL, and add it to VARMAP.
4384 This will also create any varinfo structures necessary for fields
4388 create_variable_info_for (tree decl, const char *name)
4390 unsigned int index = VEC_length (varinfo_t, varmap);
4392 tree decltype = TREE_TYPE (decl);
4393 tree declsize = DECL_P (decl) ? DECL_SIZE (decl) : TYPE_SIZE (decltype);
4394 bool notokay = false;
4396 bool is_global = DECL_P (decl) ? is_global_var (decl) : false;
4397 VEC (fieldoff_s,heap) *fieldstack = NULL;
4399 if (TREE_CODE (decl) == FUNCTION_DECL && in_ipa_mode)
4400 return create_function_info_for (decl, name);
4402 hasunion = TREE_CODE (decltype) == UNION_TYPE
4403 || TREE_CODE (decltype) == QUAL_UNION_TYPE;
4404 if (var_can_have_subvars (decl) && use_field_sensitive && !hasunion)
4406 push_fields_onto_fieldstack (decltype, &fieldstack, 0, &hasunion,
4410 VEC_free (fieldoff_s, heap, fieldstack);
4416 /* If the variable doesn't have subvars, we may end up needing to
4417 sort the field list and create fake variables for all the
4419 vi = new_var_info (decl, index, name);
4422 vi->has_union = hasunion;
4424 || TREE_CODE (declsize) != INTEGER_CST
4425 || TREE_CODE (decltype) == UNION_TYPE
4426 || TREE_CODE (decltype) == QUAL_UNION_TYPE)
4428 vi->is_unknown_size_var = true;
4434 vi->fullsize = TREE_INT_CST_LOW (declsize);
4435 vi->size = vi->fullsize;
4438 insert_vi_for_tree (vi->decl, vi);
4439 VEC_safe_push (varinfo_t, heap, varmap, vi);
4440 if (is_global && (!flag_whole_program || !in_ipa_mode))
4441 make_constraint_from_anything (vi);
4444 if (use_field_sensitive
4446 && !vi->is_unknown_size_var
4447 && var_can_have_subvars (decl)
4448 && VEC_length (fieldoff_s, fieldstack) > 1
4449 && VEC_length (fieldoff_s, fieldstack) <= MAX_FIELDS_FOR_FIELD_SENSITIVE)
4451 unsigned int newindex = VEC_length (varinfo_t, varmap);
4452 fieldoff_s *fo = NULL;
4455 for (i = 0; !notokay && VEC_iterate (fieldoff_s, fieldstack, i, fo); i++)
4458 || TREE_CODE (fo->size) != INTEGER_CST
4466 /* We can't sort them if we have a field with a variable sized type,
4467 which will make notokay = true. In that case, we are going to return
4468 without creating varinfos for the fields anyway, so sorting them is a
4472 sort_fieldstack (fieldstack);
4473 /* Due to some C++ FE issues, like PR 22488, we might end up
4474 what appear to be overlapping fields even though they,
4475 in reality, do not overlap. Until the C++ FE is fixed,
4476 we will simply disable field-sensitivity for these cases. */
4477 notokay = check_for_overlaps (fieldstack);
4481 if (VEC_length (fieldoff_s, fieldstack) != 0)
4482 fo = VEC_index (fieldoff_s, fieldstack, 0);
4484 if (fo == NULL || notokay)
4486 vi->is_unknown_size_var = 1;
4489 VEC_free (fieldoff_s, heap, fieldstack);
4493 vi->size = TREE_INT_CST_LOW (fo->size);
4494 vi->offset = fo->offset;
4495 for (i = VEC_length (fieldoff_s, fieldstack) - 1;
4496 i >= 1 && VEC_iterate (fieldoff_s, fieldstack, i, fo);
4500 const char *newname = "NULL";
4503 newindex = VEC_length (varinfo_t, varmap);
4507 asprintf (&tempname, "%s.%s",
4508 vi->name, alias_get_name (fo->decl));
4510 asprintf (&tempname, "%s." HOST_WIDE_INT_PRINT_DEC,
4511 vi->name, fo->offset);
4512 newname = ggc_strdup (tempname);
4515 newvi = new_var_info (decl, newindex, newname);
4516 newvi->offset = fo->offset;
4517 newvi->size = TREE_INT_CST_LOW (fo->size);
4518 newvi->fullsize = vi->fullsize;
4519 insert_into_field_list (vi, newvi);
4520 VEC_safe_push (varinfo_t, heap, varmap, newvi);
4521 if (is_global && (!flag_whole_program || !in_ipa_mode))
4522 make_constraint_from_anything (newvi);
4528 VEC_free (fieldoff_s, heap, fieldstack);
4533 /* Print out the points-to solution for VAR to FILE. */
4536 dump_solution_for_var (FILE *file, unsigned int var)
4538 varinfo_t vi = get_varinfo (var);
4542 if (find (var) != var)
4544 varinfo_t vipt = get_varinfo (find (var));
4545 fprintf (file, "%s = same as %s\n", vi->name, vipt->name);
4549 fprintf (file, "%s = { ", vi->name);
4550 EXECUTE_IF_SET_IN_BITMAP (vi->solution, 0, i, bi)
4552 fprintf (file, "%s ", get_varinfo (i)->name);
4554 fprintf (file, "}");
4555 if (vi->no_tbaa_pruning)
4556 fprintf (file, " no-tbaa-pruning");
4557 fprintf (file, "\n");
4561 /* Print the points-to solution for VAR to stdout. */
4564 debug_solution_for_var (unsigned int var)
4566 dump_solution_for_var (stdout, var);
4569 /* Create varinfo structures for all of the variables in the
4570 function for intraprocedural mode. */
4573 intra_create_variable_infos (void)
4576 struct constraint_expr lhs, rhs;
4578 /* For each incoming pointer argument arg, create the constraint ARG
4579 = ANYTHING or a dummy variable if flag_argument_noalias is set. */
4580 for (t = DECL_ARGUMENTS (current_function_decl); t; t = TREE_CHAIN (t))
4584 if (!could_have_pointers (t))
4587 /* If flag_argument_noalias is set, then function pointer
4588 arguments are guaranteed not to point to each other. In that
4589 case, create an artificial variable PARM_NOALIAS and the
4590 constraint ARG = &PARM_NOALIAS. */
4591 if (POINTER_TYPE_P (TREE_TYPE (t)) && flag_argument_noalias > 0)
4594 tree heapvar = heapvar_lookup (t);
4598 lhs.var = get_vi_for_tree (t)->id;
4600 if (heapvar == NULL_TREE)
4603 heapvar = create_tmp_var_raw (TREE_TYPE (TREE_TYPE (t)),
4605 DECL_EXTERNAL (heapvar) = 1;
4606 if (gimple_referenced_vars (cfun))
4607 add_referenced_var (heapvar);
4609 heapvar_insert (t, heapvar);
4611 ann = get_var_ann (heapvar);
4612 if (flag_argument_noalias == 1)
4613 ann->noalias_state = NO_ALIAS;
4614 else if (flag_argument_noalias == 2)
4615 ann->noalias_state = NO_ALIAS_GLOBAL;
4616 else if (flag_argument_noalias == 3)
4617 ann->noalias_state = NO_ALIAS_ANYTHING;
4622 vi = get_vi_for_tree (heapvar);
4623 vi->is_artificial_var = 1;
4624 vi->is_heap_var = 1;
4626 rhs.type = ADDRESSOF;
4628 for (p = get_varinfo (lhs.var); p; p = p->next)
4630 struct constraint_expr temp = lhs;
4632 process_constraint (new_constraint (temp, rhs));
4637 varinfo_t arg_vi = get_vi_for_tree (t);
4639 for (p = arg_vi; p; p = p->next)
4640 make_constraint_from_anything (p);
4645 /* Structure used to put solution bitmaps in a hashtable so they can
4646 be shared among variables with the same points-to set. */
4648 typedef struct shared_bitmap_info
4652 } *shared_bitmap_info_t;
4653 typedef const struct shared_bitmap_info *const_shared_bitmap_info_t;
4655 static htab_t shared_bitmap_table;
4657 /* Hash function for a shared_bitmap_info_t */
4660 shared_bitmap_hash (const void *p)
4662 const_shared_bitmap_info_t const bi = (const_shared_bitmap_info_t) p;
4663 return bi->hashcode;
4666 /* Equality function for two shared_bitmap_info_t's. */
4669 shared_bitmap_eq (const void *p1, const void *p2)
4671 const_shared_bitmap_info_t const sbi1 = (const_shared_bitmap_info_t) p1;
4672 const_shared_bitmap_info_t const sbi2 = (const_shared_bitmap_info_t) p2;
4673 return bitmap_equal_p (sbi1->pt_vars, sbi2->pt_vars);
4676 /* Lookup a bitmap in the shared bitmap hashtable, and return an already
4677 existing instance if there is one, NULL otherwise. */
4680 shared_bitmap_lookup (bitmap pt_vars)
4683 struct shared_bitmap_info sbi;
4685 sbi.pt_vars = pt_vars;
4686 sbi.hashcode = bitmap_hash (pt_vars);
4688 slot = htab_find_slot_with_hash (shared_bitmap_table, &sbi,
4689 sbi.hashcode, NO_INSERT);
4693 return ((shared_bitmap_info_t) *slot)->pt_vars;
4697 /* Add a bitmap to the shared bitmap hashtable. */
4700 shared_bitmap_add (bitmap pt_vars)
4703 shared_bitmap_info_t sbi = XNEW (struct shared_bitmap_info);
4705 sbi->pt_vars = pt_vars;
4706 sbi->hashcode = bitmap_hash (pt_vars);
4708 slot = htab_find_slot_with_hash (shared_bitmap_table, sbi,
4709 sbi->hashcode, INSERT);
4710 gcc_assert (!*slot);
4711 *slot = (void *) sbi;
4715 /* Set bits in INTO corresponding to the variable uids in solution set
4716 FROM, which came from variable PTR.
4717 For variables that are actually dereferenced, we also use type
4718 based alias analysis to prune the points-to sets.
4719 IS_DEREFED is true if PTR was directly dereferenced, which we use to
4720 help determine whether we are we are allowed to prune using TBAA.
4721 If NO_TBAA_PRUNING is true, we do not perform any TBAA pruning of
4725 set_uids_in_ptset (tree ptr, bitmap into, bitmap from, bool is_derefed,
4726 bool no_tbaa_pruning)
4730 alias_set_type ptr_alias_set;
4732 gcc_assert (POINTER_TYPE_P (TREE_TYPE (ptr)));
4733 ptr_alias_set = get_alias_set (TREE_TYPE (TREE_TYPE (ptr)));
4735 EXECUTE_IF_SET_IN_BITMAP (from, 0, i, bi)
4737 varinfo_t vi = get_varinfo (i);
4738 alias_set_type var_alias_set;
4740 /* The only artificial variables that are allowed in a may-alias
4741 set are heap variables. */
4742 if (vi->is_artificial_var && !vi->is_heap_var)
4745 if (vi->has_union && get_subvars_for_var (vi->decl) != NULL)
4749 subvar_t sv = get_subvars_for_var (vi->decl);
4751 /* Variables containing unions may need to be converted to
4752 their SFT's, because SFT's can have unions and we cannot. */
4753 for (i = 0; VEC_iterate (tree, sv, i, subvar); ++i)
4754 bitmap_set_bit (into, DECL_UID (subvar));
4756 else if (TREE_CODE (vi->decl) == VAR_DECL
4757 || TREE_CODE (vi->decl) == PARM_DECL
4758 || TREE_CODE (vi->decl) == RESULT_DECL)
4761 if (var_can_have_subvars (vi->decl)
4762 && (sv = get_subvars_for_var (vi->decl)))
4764 /* If VI->DECL is an aggregate for which we created
4765 SFTs, add the SFT corresponding to VI->OFFSET.
4766 If we didn't do field-sensitive PTA we need to to
4767 add all overlapping SFTs. */
4769 tree sft = get_first_overlapping_subvar (sv, vi->offset,
4772 for (; VEC_iterate (tree, sv, j, sft); ++j)
4774 if (SFT_OFFSET (sft) > vi->offset
4775 && vi->size <= SFT_OFFSET (sft) - vi->offset)
4778 var_alias_set = get_alias_set (sft);
4780 || (!is_derefed && !vi->directly_dereferenced)
4781 || alias_sets_conflict_p (ptr_alias_set, var_alias_set))
4783 bitmap_set_bit (into, DECL_UID (sft));
4785 /* Pointed-to SFTs are needed by the operand scanner
4786 to adjust offsets when adding operands to memory
4787 expressions that dereference PTR. This means
4788 that memory partitioning may not partition
4789 this SFT because the operand scanner will not
4790 be able to find the other SFTs next to this
4791 one. But we only need to do this if the pointed
4792 to type is aggregate. */
4793 if (SFT_BASE_FOR_COMPONENTS_P (sft))
4794 SFT_UNPARTITIONABLE_P (sft) = true;
4800 /* Otherwise, just add VI->DECL to the alias set.
4801 Don't type prune artificial vars. */
4802 if (vi->is_artificial_var)
4803 bitmap_set_bit (into, DECL_UID (vi->decl));
4806 var_alias_set = get_alias_set (vi->decl);
4808 || (!is_derefed && !vi->directly_dereferenced)
4809 || alias_sets_conflict_p (ptr_alias_set, var_alias_set))
4810 bitmap_set_bit (into, DECL_UID (vi->decl));
4818 static bool have_alias_info = false;
4820 /* The list of SMT's that are in use by our pointer variables. This
4821 is the set of SMT's for all pointers that can point to anything. */
4822 static bitmap used_smts;
4824 /* Due to the ordering of points-to set calculation and SMT
4825 calculation being a bit co-dependent, we can't just calculate SMT
4826 used info whenever we want, we have to calculate it around the time
4827 that find_what_p_points_to is called. */
4829 /* Mark which SMT's are in use by points-to anything variables. */
4832 set_used_smts (void)
4836 used_smts = BITMAP_ALLOC (&pta_obstack);
4838 for (i = 0; VEC_iterate (varinfo_t, varmap, i, vi); i++)
4840 tree var = vi->decl;
4841 varinfo_t withsolution = get_varinfo (find (i));
4844 struct ptr_info_def *pi = NULL;
4846 /* For parm decls, the pointer info may be under the default
4848 if (TREE_CODE (vi->decl) == PARM_DECL
4849 && gimple_default_def (cfun, var))
4850 pi = SSA_NAME_PTR_INFO (gimple_default_def (cfun, var));
4851 else if (TREE_CODE (var) == SSA_NAME)
4852 pi = SSA_NAME_PTR_INFO (var);
4854 /* Skip the special variables and those that can't be aliased. */
4855 if (vi->is_special_var
4857 || (pi && !pi->is_dereferenced)
4858 || (TREE_CODE (var) == VAR_DECL && !may_be_aliased (var))
4859 || !POINTER_TYPE_P (TREE_TYPE (var)))
4862 if (TREE_CODE (var) == SSA_NAME)
4863 var = SSA_NAME_VAR (var);
4869 smt = va->symbol_mem_tag;
4870 if (smt && bitmap_bit_p (withsolution->solution, anything_id))
4871 bitmap_set_bit (used_smts, DECL_UID (smt));
4875 /* Merge the necessary SMT's into the bitmap INTO, which is
4876 P's varinfo. This involves merging all SMT's that are a subset of
4877 the SMT necessary for P. */
4880 merge_smts_into (tree p, bitmap solution)
4886 if (TREE_CODE (p) == SSA_NAME)
4887 var = SSA_NAME_VAR (p);
4889 smt = var_ann (var)->symbol_mem_tag;
4892 alias_set_type smtset = get_alias_set (TREE_TYPE (smt));
4893 referenced_var_iterator ri;
4896 /* Need to set the SMT subsets first before this
4897 will work properly. */
4898 bitmap_set_bit (solution, DECL_UID (smt));
4899 FOR_EACH_REFERENCED_VAR_IN_BITMAP (used_smts, newsmt, ri)
4901 tree newsmttype = TREE_TYPE (newsmt);
4903 if (alias_set_subset_of (get_alias_set (newsmttype),
4905 bitmap_set_bit (solution, DECL_UID (newsmt));
4908 aliases = MTAG_ALIASES (smt);
4910 bitmap_ior_into (solution, aliases);
4914 /* Given a pointer variable P, fill in its points-to set, or return
4916 Rather than return false for variables that point-to anything, we
4917 instead find the corresponding SMT, and merge in its aliases. In
4918 addition to these aliases, we also set the bits for the SMT's
4919 themselves and their subsets, as SMT's are still in use by
4920 non-SSA_NAME's, and pruning may eliminate every one of their
4921 aliases. In such a case, if we did not include the right set of
4922 SMT's in the points-to set of the variable, we'd end up with
4923 statements that do not conflict but should. */
4926 find_what_p_points_to (tree p)
4931 if (!have_alias_info)
4934 /* For parameters, get at the points-to set for the actual parm
4936 if (TREE_CODE (p) == SSA_NAME
4937 && TREE_CODE (SSA_NAME_VAR (p)) == PARM_DECL
4938 && SSA_NAME_IS_DEFAULT_DEF (p))
4939 lookup_p = SSA_NAME_VAR (p);
4941 vi = lookup_vi_for_tree (lookup_p);
4944 if (vi->is_artificial_var)
4947 /* See if this is a field or a structure. */
4948 if (vi->size != vi->fullsize)
4950 /* Nothing currently asks about structure fields directly,
4951 but when they do, we need code here to hand back the
4953 if (!var_can_have_subvars (vi->decl)
4954 || get_subvars_for_var (vi->decl) == NULL)
4959 struct ptr_info_def *pi = get_ptr_info (p);
4962 bool was_pt_anything = false;
4963 bitmap finished_solution;
4966 if (!pi->is_dereferenced)
4969 /* This variable may have been collapsed, let's get the real
4971 vi = get_varinfo (find (vi->id));
4973 /* Translate artificial variables into SSA_NAME_PTR_INFO
4975 EXECUTE_IF_SET_IN_BITMAP (vi->solution, 0, i, bi)
4977 varinfo_t vi = get_varinfo (i);
4979 if (vi->is_artificial_var)
4981 /* FIXME. READONLY should be handled better so that
4982 flow insensitive aliasing can disregard writable
4984 if (vi->id == nothing_id)
4986 else if (vi->id == anything_id)
4987 was_pt_anything = 1;
4988 else if (vi->id == readonly_id)
4989 was_pt_anything = 1;
4990 else if (vi->id == integer_id)
4991 was_pt_anything = 1;
4992 else if (vi->is_heap_var)
4993 pi->pt_global_mem = 1;
4997 /* Share the final set of variables when possible. */
4998 finished_solution = BITMAP_GGC_ALLOC ();
4999 stats.points_to_sets_created++;
5001 /* Instead of using pt_anything, we merge in the SMT aliases
5002 for the underlying SMT. In addition, if they could have
5003 pointed to anything, they could point to global memory.
5004 But we cannot do that for ref-all pointers because these
5005 aliases have not been computed yet. */
5006 if (was_pt_anything)
5008 if (PTR_IS_REF_ALL (p))
5010 pi->pt_anything = 1;
5014 merge_smts_into (p, finished_solution);
5015 pi->pt_global_mem = 1;
5018 set_uids_in_ptset (p, finished_solution, vi->solution,
5019 vi->directly_dereferenced,
5020 vi->no_tbaa_pruning);
5021 result = shared_bitmap_lookup (finished_solution);
5025 shared_bitmap_add (finished_solution);
5026 pi->pt_vars = finished_solution;
5030 pi->pt_vars = result;
5031 bitmap_clear (finished_solution);
5034 if (bitmap_empty_p (pi->pt_vars))
5046 /* Dump points-to information to OUTFILE. */
5049 dump_sa_points_to_info (FILE *outfile)
5053 fprintf (outfile, "\nPoints-to sets\n\n");
5055 if (dump_flags & TDF_STATS)
5057 fprintf (outfile, "Stats:\n");
5058 fprintf (outfile, "Total vars: %d\n", stats.total_vars);
5059 fprintf (outfile, "Non-pointer vars: %d\n",
5060 stats.nonpointer_vars);
5061 fprintf (outfile, "Statically unified vars: %d\n",
5062 stats.unified_vars_static);
5063 fprintf (outfile, "Dynamically unified vars: %d\n",
5064 stats.unified_vars_dynamic);
5065 fprintf (outfile, "Iterations: %d\n", stats.iterations);
5066 fprintf (outfile, "Number of edges: %d\n", stats.num_edges);
5067 fprintf (outfile, "Number of implicit edges: %d\n",
5068 stats.num_implicit_edges);
5071 for (i = 0; i < VEC_length (varinfo_t, varmap); i++)
5072 dump_solution_for_var (outfile, i);
5076 /* Debug points-to information to stderr. */
5079 debug_sa_points_to_info (void)
5081 dump_sa_points_to_info (stderr);
5085 /* Initialize the always-existing constraint variables for NULL
5086 ANYTHING, READONLY, and INTEGER */
5089 init_base_vars (void)
5091 struct constraint_expr lhs, rhs;
5093 /* Create the NULL variable, used to represent that a variable points
5095 nothing_tree = create_tmp_var_raw (void_type_node, "NULL");
5096 var_nothing = new_var_info (nothing_tree, 0, "NULL");
5097 insert_vi_for_tree (nothing_tree, var_nothing);
5098 var_nothing->is_artificial_var = 1;
5099 var_nothing->offset = 0;
5100 var_nothing->size = ~0;
5101 var_nothing->fullsize = ~0;
5102 var_nothing->is_special_var = 1;
5104 VEC_safe_push (varinfo_t, heap, varmap, var_nothing);
5106 /* Create the ANYTHING variable, used to represent that a variable
5107 points to some unknown piece of memory. */
5108 anything_tree = create_tmp_var_raw (void_type_node, "ANYTHING");
5109 var_anything = new_var_info (anything_tree, 1, "ANYTHING");
5110 insert_vi_for_tree (anything_tree, var_anything);
5111 var_anything->is_artificial_var = 1;
5112 var_anything->size = ~0;
5113 var_anything->offset = 0;
5114 var_anything->next = NULL;
5115 var_anything->fullsize = ~0;
5116 var_anything->is_special_var = 1;
5119 /* Anything points to anything. This makes deref constraints just
5120 work in the presence of linked list and other p = *p type loops,
5121 by saying that *ANYTHING = ANYTHING. */
5122 VEC_safe_push (varinfo_t, heap, varmap, var_anything);
5124 lhs.var = anything_id;
5126 rhs.type = ADDRESSOF;
5127 rhs.var = anything_id;
5130 /* This specifically does not use process_constraint because
5131 process_constraint ignores all anything = anything constraints, since all
5132 but this one are redundant. */
5133 VEC_safe_push (constraint_t, heap, constraints, new_constraint (lhs, rhs));
5135 /* Create the READONLY variable, used to represent that a variable
5136 points to readonly memory. */
5137 readonly_tree = create_tmp_var_raw (void_type_node, "READONLY");
5138 var_readonly = new_var_info (readonly_tree, 2, "READONLY");
5139 var_readonly->is_artificial_var = 1;
5140 var_readonly->offset = 0;
5141 var_readonly->size = ~0;
5142 var_readonly->fullsize = ~0;
5143 var_readonly->next = NULL;
5144 var_readonly->is_special_var = 1;
5145 insert_vi_for_tree (readonly_tree, var_readonly);
5147 VEC_safe_push (varinfo_t, heap, varmap, var_readonly);
5149 /* readonly memory points to anything, in order to make deref
5150 easier. In reality, it points to anything the particular
5151 readonly variable can point to, but we don't track this
5154 lhs.var = readonly_id;
5156 rhs.type = ADDRESSOF;
5157 rhs.var = anything_id;
5160 process_constraint (new_constraint (lhs, rhs));
5162 /* Create the INTEGER variable, used to represent that a variable points
5164 integer_tree = create_tmp_var_raw (void_type_node, "INTEGER");
5165 var_integer = new_var_info (integer_tree, 3, "INTEGER");
5166 insert_vi_for_tree (integer_tree, var_integer);
5167 var_integer->is_artificial_var = 1;
5168 var_integer->size = ~0;
5169 var_integer->fullsize = ~0;
5170 var_integer->offset = 0;
5171 var_integer->next = NULL;
5172 var_integer->is_special_var = 1;
5174 VEC_safe_push (varinfo_t, heap, varmap, var_integer);
5176 /* INTEGER = ANYTHING, because we don't know where a dereference of
5177 a random integer will point to. */
5179 lhs.var = integer_id;
5181 rhs.type = ADDRESSOF;
5182 rhs.var = anything_id;
5184 process_constraint (new_constraint (lhs, rhs));
5187 /* Initialize things necessary to perform PTA */
5190 init_alias_vars (void)
5192 bitmap_obstack_initialize (&pta_obstack);
5193 bitmap_obstack_initialize (&oldpta_obstack);
5194 bitmap_obstack_initialize (&predbitmap_obstack);
5196 constraint_pool = create_alloc_pool ("Constraint pool",
5197 sizeof (struct constraint), 30);
5198 variable_info_pool = create_alloc_pool ("Variable info pool",
5199 sizeof (struct variable_info), 30);
5200 constraints = VEC_alloc (constraint_t, heap, 8);
5201 varmap = VEC_alloc (varinfo_t, heap, 8);
5202 vi_for_tree = pointer_map_create ();
5204 memset (&stats, 0, sizeof (stats));
5205 shared_bitmap_table = htab_create (511, shared_bitmap_hash,
5206 shared_bitmap_eq, free);
5210 /* Remove the REF and ADDRESS edges from GRAPH, as well as all the
5211 predecessor edges. */
5214 remove_preds_and_fake_succs (constraint_graph_t graph)
5218 /* Clear the implicit ref and address nodes from the successor
5220 for (i = 0; i < FIRST_REF_NODE; i++)
5222 if (graph->succs[i])
5223 bitmap_clear_range (graph->succs[i], FIRST_REF_NODE,
5224 FIRST_REF_NODE * 2);
5227 /* Free the successor list for the non-ref nodes. */
5228 for (i = FIRST_REF_NODE; i < graph->size; i++)
5230 if (graph->succs[i])
5231 BITMAP_FREE (graph->succs[i]);
5234 /* Now reallocate the size of the successor list as, and blow away
5235 the predecessor bitmaps. */
5236 graph->size = VEC_length (varinfo_t, varmap);
5237 graph->succs = XRESIZEVEC (bitmap, graph->succs, graph->size);
5239 free (graph->implicit_preds);
5240 graph->implicit_preds = NULL;
5241 free (graph->preds);
5242 graph->preds = NULL;
5243 bitmap_obstack_release (&predbitmap_obstack);
5246 /* Compute the set of variables we can't TBAA prune. */
5249 compute_tbaa_pruning (void)
5251 unsigned int size = VEC_length (varinfo_t, varmap);
5256 changed = sbitmap_alloc (size);
5257 sbitmap_zero (changed);
5259 /* Mark all initial no_tbaa_pruning nodes as changed. */
5261 for (i = 0; i < size; ++i)
5263 varinfo_t ivi = get_varinfo (i);
5265 if (find (i) == i && ivi->no_tbaa_pruning)
5268 if ((graph->succs[i] && !bitmap_empty_p (graph->succs[i]))
5269 || VEC_length (constraint_t, graph->complex[i]) > 0)
5271 SET_BIT (changed, i);
5277 while (changed_count > 0)
5279 struct topo_info *ti = init_topo_info ();
5282 compute_topo_order (graph, ti);
5284 while (VEC_length (unsigned, ti->topo_order) != 0)
5288 i = VEC_pop (unsigned, ti->topo_order);
5290 /* If this variable is not a representative, skip it. */
5294 /* If the node has changed, we need to process the complex
5295 constraints and outgoing edges again. */
5296 if (TEST_BIT (changed, i))
5300 VEC(constraint_t,heap) *complex = graph->complex[i];
5302 RESET_BIT (changed, i);
5305 /* Process the complex copy constraints. */
5306 for (j = 0; VEC_iterate (constraint_t, complex, j, c); ++j)
5308 if (c->lhs.type == SCALAR && c->rhs.type == SCALAR)
5310 varinfo_t lhsvi = get_varinfo (find (c->lhs.var));
5312 if (!lhsvi->no_tbaa_pruning)
5314 lhsvi->no_tbaa_pruning = true;
5315 if (!TEST_BIT (changed, lhsvi->id))
5317 SET_BIT (changed, lhsvi->id);
5324 /* Propagate to all successors. */
5325 EXECUTE_IF_IN_NONNULL_BITMAP (graph->succs[i], 0, j, bi)
5327 unsigned int to = find (j);
5328 varinfo_t tovi = get_varinfo (to);
5330 /* Don't propagate to ourselves. */
5334 if (!tovi->no_tbaa_pruning)
5336 tovi->no_tbaa_pruning = true;
5337 if (!TEST_BIT (changed, to))
5339 SET_BIT (changed, to);
5347 free_topo_info (ti);
5350 sbitmap_free (changed);
5354 for (i = 0; i < size; ++i)
5356 varinfo_t ivi = get_varinfo (i);
5357 varinfo_t ivip = get_varinfo (find (i));
5359 if (ivip->no_tbaa_pruning)
5361 tree var = ivi->decl;
5363 if (TREE_CODE (var) == SSA_NAME)
5364 var = SSA_NAME_VAR (var);
5366 if (POINTER_TYPE_P (TREE_TYPE (var)))
5368 DECL_NO_TBAA_P (var) = 1;
5370 /* Tell the RTL layer that this pointer can alias
5372 DECL_POINTER_ALIAS_SET (var) = 0;
5379 /* Create points-to sets for the current function. See the comments
5380 at the start of the file for an algorithmic overview. */
5383 compute_points_to_sets (struct alias_info *ai)
5385 struct scc_info *si;
5388 timevar_push (TV_TREE_PTA);
5391 init_alias_heapvars ();
5393 intra_create_variable_infos ();
5395 /* Now walk all statements and derive aliases. */
5398 block_stmt_iterator bsi;
5401 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
5403 if (is_gimple_reg (PHI_RESULT (phi)))
5405 find_func_aliases (phi);
5407 /* Update various related attributes like escaped
5408 addresses, pointer dereferences for loads and stores.
5409 This is used when creating name tags and alias
5411 update_alias_info (phi, ai);
5415 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
5417 tree stmt = bsi_stmt (bsi);
5419 find_func_aliases (stmt);
5421 /* Update various related attributes like escaped
5422 addresses, pointer dereferences for loads and stores.
5423 This is used when creating name tags and alias
5425 update_alias_info (stmt, ai);
5427 /* The information in CHANGE_DYNAMIC_TYPE_EXPR nodes has now
5428 been captured, and we can remove them. */
5429 if (TREE_CODE (stmt) == CHANGE_DYNAMIC_TYPE_EXPR)
5430 bsi_remove (&bsi, true);
5439 fprintf (dump_file, "Points-to analysis\n\nConstraints:\n\n");
5440 dump_constraints (dump_file);
5445 "\nCollapsing static cycles and doing variable "
5448 init_graph (VEC_length (varinfo_t, varmap) * 2);
5451 fprintf (dump_file, "Building predecessor graph\n");
5452 build_pred_graph ();
5455 fprintf (dump_file, "Detecting pointer and location "
5457 si = perform_var_substitution (graph);
5460 fprintf (dump_file, "Rewriting constraints and unifying "
5462 rewrite_constraints (graph, si);
5463 free_var_substitution_info (si);
5465 build_succ_graph ();
5466 move_complex_constraints (graph);
5469 fprintf (dump_file, "Uniting pointer but not location equivalent "
5471 unite_pointer_equivalences (graph);
5474 fprintf (dump_file, "Finding indirect cycles\n");
5475 find_indirect_cycles (graph);
5477 /* Implicit nodes and predecessors are no longer necessary at this
5479 remove_preds_and_fake_succs (graph);
5482 fprintf (dump_file, "Solving graph\n");
5484 solve_graph (graph);
5486 compute_tbaa_pruning ();
5489 dump_sa_points_to_info (dump_file);
5491 have_alias_info = true;
5493 timevar_pop (TV_TREE_PTA);
5497 /* Delete created points-to sets. */
5500 delete_points_to_sets (void)
5504 htab_delete (shared_bitmap_table);
5505 if (dump_file && (dump_flags & TDF_STATS))
5506 fprintf (dump_file, "Points to sets created:%d\n",
5507 stats.points_to_sets_created);
5509 pointer_map_destroy (vi_for_tree);
5510 bitmap_obstack_release (&pta_obstack);
5511 VEC_free (constraint_t, heap, constraints);
5513 for (i = 0; i < graph->size; i++)
5514 VEC_free (constraint_t, heap, graph->complex[i]);
5515 free (graph->complex);
5518 free (graph->succs);
5520 free (graph->pe_rep);
5521 free (graph->indirect_cycles);
5524 VEC_free (varinfo_t, heap, varmap);
5525 free_alloc_pool (variable_info_pool);
5526 free_alloc_pool (constraint_pool);
5527 have_alias_info = false;
5530 /* Return true if we should execute IPA PTA. */
5534 return (flag_unit_at_a_time != 0
5536 /* Don't bother doing anything if the program has errors. */
5537 && !(errorcount || sorrycount));
5540 /* Execute the driver for IPA PTA. */
5542 ipa_pta_execute (void)
5544 struct cgraph_node *node;
5545 struct scc_info *si;
5548 init_alias_heapvars ();
5551 for (node = cgraph_nodes; node; node = node->next)
5553 if (!node->analyzed || cgraph_is_master_clone (node))
5557 varid = create_function_info_for (node->decl,
5558 cgraph_node_name (node));
5559 if (node->local.externally_visible)
5561 varinfo_t fi = get_varinfo (varid);
5562 for (; fi; fi = fi->next)
5563 make_constraint_from_anything (fi);
5567 for (node = cgraph_nodes; node; node = node->next)
5569 if (node->analyzed && cgraph_is_master_clone (node))
5571 struct function *func = DECL_STRUCT_FUNCTION (node->decl);
5573 tree old_func_decl = current_function_decl;
5576 "Generating constraints for %s\n",
5577 cgraph_node_name (node));
5579 current_function_decl = node->decl;
5581 FOR_EACH_BB_FN (bb, func)
5583 block_stmt_iterator bsi;
5586 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
5588 if (is_gimple_reg (PHI_RESULT (phi)))
5590 find_func_aliases (phi);
5594 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
5596 tree stmt = bsi_stmt (bsi);
5597 find_func_aliases (stmt);
5600 current_function_decl = old_func_decl;
5605 /* Make point to anything. */
5611 fprintf (dump_file, "Points-to analysis\n\nConstraints:\n\n");
5612 dump_constraints (dump_file);
5617 "\nCollapsing static cycles and doing variable "
5620 init_graph (VEC_length (varinfo_t, varmap) * 2);
5621 build_pred_graph ();
5622 si = perform_var_substitution (graph);
5623 rewrite_constraints (graph, si);
5624 free_var_substitution_info (si);
5626 build_succ_graph ();
5627 move_complex_constraints (graph);
5628 unite_pointer_equivalences (graph);
5629 find_indirect_cycles (graph);
5631 /* Implicit nodes and predecessors are no longer necessary at this
5633 remove_preds_and_fake_succs (graph);
5636 fprintf (dump_file, "\nSolving graph\n");
5638 solve_graph (graph);
5641 dump_sa_points_to_info (dump_file);
5644 delete_alias_heapvars ();
5645 delete_points_to_sets ();
5649 struct tree_opt_pass pass_ipa_pta =
5652 gate_ipa_pta, /* gate */
5653 ipa_pta_execute, /* execute */
5656 0, /* static_pass_number */
5657 TV_IPA_PTA, /* tv_id */
5658 0, /* properties_required */
5659 0, /* properties_provided */
5660 0, /* properties_destroyed */
5661 0, /* todo_flags_start */
5662 TODO_update_ssa, /* todo_flags_finish */
5666 /* Initialize the heapvar for statement mapping. */
5668 init_alias_heapvars (void)
5670 if (!heapvar_for_stmt)
5671 heapvar_for_stmt = htab_create_ggc (11, tree_map_hash, tree_map_eq,
5676 delete_alias_heapvars (void)
5678 htab_delete (heapvar_for_stmt);
5679 heapvar_for_stmt = NULL;
5683 #include "gt-tree-ssa-structalias.h"