1 /* Callgraph based analysis of static variables.
2 Copyright (C) 2004, 2005, 2007, 2008 Free Software Foundation, Inc.
3 Contributed by Kenneth Zadeck <zadeck@naturalbridge.com>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 3, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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/>. */
21 /* This file gathers information about how variables whose scope is
22 confined to the compilation unit are used.
24 There are two categories of information produced by this pass:
26 1) The addressable (TREE_ADDRESSABLE) bit and readonly
27 (TREE_READONLY) bit associated with these variables is properly set
28 based on scanning all of the code withing the compilation unit.
30 2) The transitive call site specific clobber effects are computed
31 for the variables whose scope is contained within this compilation
34 First each function and static variable initialization is analyzed
35 to determine which local static variables are either read, written,
36 or have their address taken. Any local static that has its address
37 taken is removed from consideration. Once the local read and
38 writes are determined, a transitive closure of this information is
39 performed over the call graph to determine the worst case set of
40 side effects of each call. In later parts of the compiler, these
41 local and global sets are examined to make the call clobbering less
42 traumatic, promote some statics to registers, and improve aliasing
45 Currently must be run after inlining decisions have been made since
46 otherwise, the local sets will not contain information that is
47 consistent with post inlined state. The global sets are not prone
48 to this problem since they are by definition transitive. */
52 #include "coretypes.h"
55 #include "tree-flow.h"
56 #include "tree-inline.h"
57 #include "tree-pass.h"
58 #include "langhooks.h"
59 #include "pointer-set.h"
61 #include "ipa-utils.h"
62 #include "ipa-reference.h"
69 #include "diagnostic.h"
70 #include "langhooks.h"
72 /* The static variables defined within the compilation unit that are
73 loaded or stored directly by function that owns this structure. */
75 struct ipa_reference_local_vars_info_d
78 bitmap statics_written;
80 /* Set when this function calls another function external to the
81 compilation unit or if the function has a asm clobber of memory.
82 In general, such calls are modeled as reading and writing all
83 variables (both bits on) but sometime there are attributes on the
84 called function so we can do better. */
89 /* Statics that are read and written by some set of functions. The
90 local ones are based on the loads and stores local to the function.
91 The global ones are based on the local info as well as the
92 transitive closure of the functions that are called. The
93 structures are separated to allow the global structures to be
94 shared between several functions since every function within a
95 strongly connected component will have the same information. This
96 sharing saves both time and space in the computation of the vectors
97 as well as their translation from decl_uid form to ann_uid
100 struct ipa_reference_global_vars_info_d
103 bitmap statics_written;
104 bitmap statics_not_read;
105 bitmap statics_not_written;
108 typedef struct ipa_reference_local_vars_info_d *ipa_reference_local_vars_info_t;
109 typedef struct ipa_reference_global_vars_info_d *ipa_reference_global_vars_info_t;
110 struct ipa_reference_vars_info_d
112 ipa_reference_local_vars_info_t local;
113 ipa_reference_global_vars_info_t global;
116 typedef struct ipa_reference_vars_info_d *ipa_reference_vars_info_t;
118 /* This splay tree contains all of the static variables that are
119 being considered by the compilation level alias analysis. For
120 module_at_a_time compilation, this is the set of static but not
121 public variables. Any variables that either have their address
122 taken or participate in otherwise unsavory operations are deleted
124 static GTY((param1_is(int), param2_is(tree)))
125 splay_tree reference_vars_to_consider;
127 /* This bitmap is used to knock out the module static variables whose
128 addresses have been taken and passed around. */
129 static bitmap module_statics_escape;
131 /* This bitmap is used to knock out the module static variables that
133 static bitmap module_statics_written;
135 /* A bit is set for every module static we are considering. This is
136 ored into the local info when asm code is found that clobbers all
138 static bitmap all_module_statics;
140 static struct pointer_set_t *visited_nodes;
142 /* Obstack holding bitmaps of local analysis (live from analysis to
144 static bitmap_obstack local_info_obstack;
145 /* Obstack holding global analysis live forever. */
146 static bitmap_obstack global_info_obstack;
148 /* Holders of ipa cgraph hooks: */
149 static struct cgraph_node_hook_list *function_insertion_hook_holder;
150 static struct cgraph_2node_hook_list *node_duplication_hook_holder;
151 static struct cgraph_node_hook_list *node_removal_hook_holder;
153 enum initialization_status_t
160 tree memory_identifier_string;
162 /* Vector where the reference var infos are actually stored. */
163 DEF_VEC_P (ipa_reference_vars_info_t);
164 DEF_VEC_ALLOC_P (ipa_reference_vars_info_t, heap);
165 static VEC (ipa_reference_vars_info_t, heap) *ipa_reference_vars_vector;
167 /* Return the ipa_reference_vars structure starting from the cgraph NODE. */
168 static inline ipa_reference_vars_info_t
169 get_reference_vars_info (struct cgraph_node *node)
171 if (!ipa_reference_vars_vector
172 || VEC_length (ipa_reference_vars_info_t, ipa_reference_vars_vector) <= (unsigned int)node->uid)
174 return VEC_index (ipa_reference_vars_info_t, ipa_reference_vars_vector, node->uid);
177 /* Return the ipa_reference_vars structure starting from the cgraph NODE. */
179 set_reference_vars_info (struct cgraph_node *node, ipa_reference_vars_info_t info)
181 if (!ipa_reference_vars_vector
182 || VEC_length (ipa_reference_vars_info_t, ipa_reference_vars_vector) <= (unsigned int)node->uid)
183 VEC_safe_grow_cleared (ipa_reference_vars_info_t, heap, ipa_reference_vars_vector, node->uid + 1);
184 VEC_replace (ipa_reference_vars_info_t, ipa_reference_vars_vector, node->uid, info);
187 /* Get a bitmap that contains all of the locally referenced static
188 variables for function FN. */
189 static ipa_reference_local_vars_info_t
190 get_local_reference_vars_info (struct cgraph_node *fn)
192 ipa_reference_vars_info_t info = get_reference_vars_info (fn);
197 /* This phase was not run. */
201 /* Get a bitmap that contains all of the globally referenced static
202 variables for function FN. */
204 static ipa_reference_global_vars_info_t
205 get_global_reference_vars_info (struct cgraph_node *fn)
207 ipa_reference_vars_info_t info = get_reference_vars_info (fn);
212 /* This phase was not run. */
216 /* Return a bitmap indexed by VAR_DECL uid for the static variables
217 that are read during the execution of the function FN. Returns
218 NULL if no data is available. */
221 ipa_reference_get_read_global (struct cgraph_node *fn)
223 ipa_reference_global_vars_info_t g = get_global_reference_vars_info (fn);
225 return g->statics_read;
230 /* Return a bitmap indexed by VAR_DECL uid for the static variables
231 that are written during the execution of the function FN. Note
232 that variables written may or may not be read during the function
233 call. Returns NULL if no data is available. */
236 ipa_reference_get_written_global (struct cgraph_node *fn)
238 ipa_reference_global_vars_info_t g = get_global_reference_vars_info (fn);
240 return g->statics_written;
245 /* Return a bitmap indexed by_DECL_UID uid for the static variables
246 that are not read during the execution of the function FN. Returns
247 NULL if no data is available. */
250 ipa_reference_get_not_read_global (struct cgraph_node *fn)
252 ipa_reference_global_vars_info_t g = get_global_reference_vars_info (fn);
254 return g->statics_not_read;
259 /* Return a bitmap indexed by DECL_UID uid for the static variables
260 that are not written during the execution of the function FN. Note
261 that variables written may or may not be read during the function
262 call. Returns NULL if no data is available. */
265 ipa_reference_get_not_written_global (struct cgraph_node *fn)
267 ipa_reference_global_vars_info_t g = get_global_reference_vars_info (fn);
269 return g->statics_not_written;
276 /* Add VAR to all_module_statics and the two
277 reference_vars_to_consider* sets. */
280 add_static_var (tree var)
282 int uid = DECL_UID (var);
283 gcc_assert (TREE_CODE (var) == VAR_DECL);
284 if (!bitmap_bit_p (all_module_statics, uid))
286 splay_tree_insert (reference_vars_to_consider,
287 uid, (splay_tree_value)var);
288 bitmap_set_bit (all_module_statics, uid);
292 /* Return true if the variable T is the right kind of static variable to
293 perform compilation unit scope escape analysis. */
296 has_proper_scope_for_analysis (tree t)
298 /* If the variable has the "used" attribute, treat it as if it had a
299 been touched by the devil. */
300 if (lookup_attribute ("used", DECL_ATTRIBUTES (t)))
303 /* Do not want to do anything with volatile except mark any
304 function that uses one to be not const or pure. */
305 if (TREE_THIS_VOLATILE (t))
308 /* Do not care about a local automatic that is not static. */
309 if (!TREE_STATIC (t) && !DECL_EXTERNAL (t))
312 if (DECL_EXTERNAL (t) || TREE_PUBLIC (t))
315 /* We cannot touch decls where the type needs constructing. */
316 if (TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (t)))
319 /* This is a variable we care about. Check if we have seen it
320 before, and if not add it the set of variables we care about. */
321 if (!bitmap_bit_p (all_module_statics, DECL_UID (t)))
327 /* Mark tree T as having address taken. */
330 mark_address_taken (tree x)
332 if (TREE_CODE (x) == VAR_DECL
333 && module_statics_escape && has_proper_scope_for_analysis (x))
334 bitmap_set_bit (module_statics_escape, DECL_UID (x));
337 /* Mark load of T. */
340 mark_load (ipa_reference_local_vars_info_t local,
343 if (TREE_CODE (t) == VAR_DECL
344 && has_proper_scope_for_analysis (t))
345 bitmap_set_bit (local->statics_read, DECL_UID (t));
348 /* Mark store of T. */
351 mark_store (ipa_reference_local_vars_info_t local,
354 if (TREE_CODE (t) == VAR_DECL
355 && has_proper_scope_for_analysis (t))
358 bitmap_set_bit (local->statics_written, DECL_UID (t));
359 /* Mark the write so we can tell which statics are
361 if (module_statics_written)
362 bitmap_set_bit (module_statics_written, DECL_UID (t));
366 /* Look for memory clobber and set read_all/write_all if present. */
369 check_asm_memory_clobber (ipa_reference_local_vars_info_t local, gimple stmt)
374 for (i = 0; i < gimple_asm_nclobbers (stmt); i++)
376 op = gimple_asm_clobber_op (stmt, i);
377 if (simple_cst_equal(TREE_VALUE (op), memory_identifier_string) == 1)
379 /* Abandon all hope, ye who enter here. */
380 local->calls_read_all = true;
381 local->calls_write_all = true;
386 /* Look for external calls and set read_all/write_all correspondingly. */
389 check_call (ipa_reference_local_vars_info_t local, gimple stmt)
391 int flags = gimple_call_flags (stmt);
392 tree callee_t = gimple_call_fndecl (stmt);
393 enum availability avail = AVAIL_NOT_AVAILABLE;
397 struct cgraph_node* callee = cgraph_node(callee_t);
398 avail = cgraph_function_body_availability (callee);
401 if (avail <= AVAIL_OVERWRITABLE)
404 if (flags & ECF_CONST)
406 else if (flags & ECF_PURE)
407 local->calls_read_all = true;
410 local->calls_read_all = true;
411 local->calls_write_all = true;
414 /* TODO: To be able to produce sane results, we should also handle
415 common builtins, in particular throw.
416 Indirect calls hsould be only counted and as inliner is replacing them
417 by direct calls, we can conclude if any indirect calls are left in body */
420 /* TP is the part of the tree currently under the microscope.
421 WALK_SUBTREES is part of the walk_tree api but is unused here.
422 DATA is cgraph_node of the function being walked. */
425 scan_stmt_for_static_refs (gimple_stmt_iterator *gsip,
426 struct cgraph_node *fn)
428 gimple stmt = gsi_stmt (*gsip);
429 ipa_reference_local_vars_info_t local = NULL;
434 local = get_reference_vars_info (fn)->local;
436 /* Look for direct loads and stores. */
437 if (gimple_has_lhs (stmt))
439 tree lhs = get_base_address (gimple_get_lhs (stmt));
440 if (lhs && DECL_P (lhs))
441 mark_store (local, lhs);
443 if (gimple_assign_single_p (stmt))
445 tree rhs = get_base_address (gimple_assign_rhs1 (stmt));
446 if (rhs && DECL_P (rhs))
447 mark_load (local, rhs);
449 else if (is_gimple_call (stmt))
451 for (i = 0; i < gimple_call_num_args (stmt); ++i)
453 tree rhs = get_base_address (gimple_call_arg (stmt, i));
454 if (rhs && DECL_P (rhs))
455 mark_load (local, rhs);
457 check_call (local, stmt);
459 else if (gimple_code (stmt) == GIMPLE_ASM)
461 for (i = 0; i < gimple_asm_ninputs (stmt); ++i)
463 tree op = TREE_VALUE (gimple_asm_input_op (stmt, i));
464 op = get_base_address (op);
465 if (op && DECL_P (op))
466 mark_load (local, op);
468 for (i = 0; i < gimple_asm_noutputs (stmt); ++i)
470 tree op = TREE_VALUE (gimple_asm_output_op (stmt, i));
471 op = get_base_address (op);
472 if (op && DECL_P (op))
473 mark_store (local, op);
475 check_asm_memory_clobber (local, stmt);
478 if (gimple_addresses_taken (stmt))
479 EXECUTE_IF_SET_IN_BITMAP (gimple_addresses_taken (stmt), 0, i, bi)
480 mark_address_taken (referenced_var_lookup (i));
485 /* Call-back to scan variable initializers for static references.
486 Called using walk_tree. */
489 scan_initializer_for_static_refs (tree *tp, int *walk_subtrees,
490 void *data ATTRIBUTE_UNUSED)
494 if (TREE_CODE (t) == ADDR_EXPR)
496 mark_address_taken (get_base_var (t));
499 /* Save some cycles by not walking types and declaration as we
500 won't find anything useful there anyway. */
501 else if (IS_TYPE_OR_DECL_P (*tp))
507 /* Lookup the tree node for the static variable that has UID. */
509 get_static_decl (int index)
511 splay_tree_node stn =
512 splay_tree_lookup (reference_vars_to_consider, index);
514 return (tree)stn->value;
518 /* Lookup the tree node for the static variable that has UID and
519 convert the name to a string for debugging. */
522 get_static_name (int index)
524 splay_tree_node stn =
525 splay_tree_lookup (reference_vars_to_consider, index);
527 return lang_hooks.decl_printable_name ((tree)(stn->value), 2);
531 /* Or in all of the bits from every callee of X into X_GLOBAL, the caller's cycle,
532 bit vector. There are several cases to check to avoid the sparse
536 propagate_bits (ipa_reference_global_vars_info_t x_global, struct cgraph_node *x)
538 struct cgraph_edge *e;
539 for (e = x->callees; e; e = e->next_callee)
541 struct cgraph_node *y = e->callee;
543 /* Only look at the master nodes and skip external nodes. */
544 if (cgraph_function_body_availability (e->callee) > AVAIL_OVERWRITABLE)
546 if (get_reference_vars_info (y))
548 ipa_reference_vars_info_t y_info
549 = get_reference_vars_info (y);
550 ipa_reference_global_vars_info_t y_global = y_info->global;
552 /* Calls in current cycle do not have global computed yet. */
556 if (x_global->statics_read
557 != all_module_statics)
559 if (y_global->statics_read
560 == all_module_statics)
562 BITMAP_FREE (x_global->statics_read);
563 x_global->statics_read
564 = all_module_statics;
566 /* Skip bitmaps that are pointer equal to node's bitmap
567 (no reason to spin within the cycle). */
568 else if (x_global->statics_read
569 != y_global->statics_read)
570 bitmap_ior_into (x_global->statics_read,
571 y_global->statics_read);
574 if (x_global->statics_written
575 != all_module_statics)
577 if (y_global->statics_written
578 == all_module_statics)
580 BITMAP_FREE (x_global->statics_written);
581 x_global->statics_written
582 = all_module_statics;
584 /* Skip bitmaps that are pointer equal to node's bitmap
585 (no reason to spin within the cycle). */
586 else if (x_global->statics_written
587 != y_global->statics_written)
588 bitmap_ior_into (x_global->statics_written,
589 y_global->statics_written);
598 /* The init routine for analyzing global static variable usage. See
599 comments at top for description. */
603 memory_identifier_string = build_string(7, "memory");
605 reference_vars_to_consider =
606 splay_tree_new_ggc (splay_tree_compare_ints);
608 bitmap_obstack_initialize (&local_info_obstack);
609 bitmap_obstack_initialize (&global_info_obstack);
610 module_statics_escape = BITMAP_ALLOC (&local_info_obstack);
611 module_statics_written = BITMAP_ALLOC (&local_info_obstack);
612 all_module_statics = BITMAP_ALLOC (&global_info_obstack);
614 /* There are some shared nodes, in particular the initializers on
615 static declarations. We do not need to scan them more than once
616 since all we would be interested in are the addressof
618 visited_nodes = pointer_set_create ();
621 /* Check out the rhs of a static or global initialization VNODE to see
622 if any of them contain addressof operations. Note that some of
623 these variables may not even be referenced in the code in this
624 compilation unit but their right hand sides may contain references
625 to variables defined within this unit. */
628 analyze_variable (struct varpool_node *vnode)
630 struct walk_stmt_info wi;
631 tree global = vnode->decl;
633 memset (&wi, 0, sizeof (wi));
634 wi.pset = visited_nodes;
635 walk_tree (&DECL_INITIAL (global), scan_initializer_for_static_refs,
639 /* Set up the persistent info for FN. */
641 static ipa_reference_local_vars_info_t
642 init_function_info (struct cgraph_node *fn)
644 ipa_reference_vars_info_t info
645 = XCNEW (struct ipa_reference_vars_info_d);
646 ipa_reference_local_vars_info_t l
647 = XCNEW (struct ipa_reference_local_vars_info_d);
649 /* Add the info to the tree's annotation. */
650 set_reference_vars_info (fn, info);
653 l->statics_read = BITMAP_ALLOC (&local_info_obstack);
654 l->statics_written = BITMAP_ALLOC (&local_info_obstack);
659 /* This is the main routine for finding the reference patterns for
660 global variables within a function FN. */
663 analyze_function (struct cgraph_node *fn)
665 tree decl = fn->decl;
666 struct function *this_cfun = DECL_STRUCT_FUNCTION (decl);
667 basic_block this_block;
668 #ifdef ENABLE_CHECKING
673 fprintf (dump_file, "\n local analysis of %s\n", cgraph_node_name (fn));
675 push_cfun (DECL_STRUCT_FUNCTION (decl));
676 current_function_decl = decl;
678 init_function_info (fn);
679 FOR_EACH_BB_FN (this_block, this_cfun)
681 gimple_stmt_iterator gsi;
687 /* Find the addresses taken in phi node arguments. */
688 for (gsi = gsi_start_phis (this_block);
692 phi = gsi_stmt (gsi);
693 FOR_EACH_PHI_ARG (use, phi, iter, SSA_OP_USE)
695 op = USE_FROM_PTR (use);
696 if (TREE_CODE (op) == ADDR_EXPR)
697 mark_address_taken (get_base_var (op));
701 for (gsi = gsi_start_bb (this_block); !gsi_end_p (gsi); gsi_next (&gsi))
702 scan_stmt_for_static_refs (&gsi, fn);
705 #ifdef ENABLE_CHECKING
706 /* Verify that all local initializers was expanded by gimplifier. */
707 for (step = DECL_STRUCT_FUNCTION (decl)->local_decls;
709 step = TREE_CHAIN (step))
711 tree var = TREE_VALUE (step);
712 if (TREE_CODE (var) == VAR_DECL
713 && DECL_INITIAL (var)
714 && !TREE_STATIC (var))
719 current_function_decl = NULL;
722 /* Remove local data associated with function FN. */
724 clean_function_local_data (struct cgraph_node *fn)
726 ipa_reference_vars_info_t info = get_reference_vars_info (fn);
727 ipa_reference_local_vars_info_t l = info->local;
731 && l->statics_read != all_module_statics)
732 BITMAP_FREE (l->statics_read);
733 if (l->statics_written
734 &&l->statics_written != all_module_statics)
735 BITMAP_FREE (l->statics_written);
741 /* Remove all data associated with function FN. */
744 clean_function (struct cgraph_node *fn)
746 ipa_reference_vars_info_t info = get_reference_vars_info (fn);
747 ipa_reference_global_vars_info_t g = info->global;
749 clean_function_local_data (fn);
753 && g->statics_read != all_module_statics)
754 BITMAP_FREE (g->statics_read);
756 if (g->statics_written
757 && g->statics_written != all_module_statics)
758 BITMAP_FREE (g->statics_written);
760 if (g->statics_not_read
761 && g->statics_not_read != all_module_statics)
762 BITMAP_FREE (g->statics_not_read);
764 if (g->statics_not_written
765 && g->statics_not_written != all_module_statics)
766 BITMAP_FREE (g->statics_not_written);
771 free (get_reference_vars_info (fn));
772 set_reference_vars_info (fn, NULL);
775 /* Called when new function is inserted to callgraph late. */
777 add_new_function (struct cgraph_node *node, void *data ATTRIBUTE_UNUSED)
779 /* There are some shared nodes, in particular the initializers on
780 static declarations. We do not need to scan them more than once
781 since all we would be interested in are the addressof
783 analyze_function (node);
784 visited_nodes = NULL;
788 copy_local_bitmap (bitmap src)
793 if (src == all_module_statics)
794 return all_module_statics;
795 dst = BITMAP_ALLOC (&local_info_obstack);
796 bitmap_copy (dst, src);
801 copy_global_bitmap (bitmap src)
806 if (src == all_module_statics)
807 return all_module_statics;
808 dst = BITMAP_ALLOC (&global_info_obstack);
809 bitmap_copy (dst, src);
813 /* Called when new clone is inserted to callgraph late. */
816 duplicate_node_data (struct cgraph_node *src, struct cgraph_node *dst,
817 void *data ATTRIBUTE_UNUSED)
819 ipa_reference_global_vars_info_t ginfo;
820 ipa_reference_local_vars_info_t linfo;
821 ipa_reference_global_vars_info_t dst_ginfo;
822 ipa_reference_local_vars_info_t dst_linfo;
824 ginfo = get_global_reference_vars_info (src);
825 linfo = get_local_reference_vars_info (src);
826 if (!linfo && !ginfo)
828 init_function_info (dst);
831 dst_linfo = get_local_reference_vars_info (dst);
832 dst_linfo->statics_read = copy_local_bitmap (linfo->statics_read);
833 dst_linfo->statics_written = copy_local_bitmap (linfo->statics_written);
834 dst_linfo->calls_read_all = linfo->calls_read_all;
835 dst_linfo->calls_write_all = linfo->calls_write_all;
839 get_reference_vars_info (dst)->global = XCNEW (struct ipa_reference_global_vars_info_d);
840 dst_ginfo = get_global_reference_vars_info (dst);
841 dst_ginfo->statics_read = copy_global_bitmap (ginfo->statics_read);
842 dst_ginfo->statics_written = copy_global_bitmap (ginfo->statics_written);
843 dst_ginfo->statics_not_read = copy_global_bitmap (ginfo->statics_not_read);
844 dst_ginfo->statics_not_written = copy_global_bitmap (ginfo->statics_not_written);
848 /* Called when node is removed. */
851 remove_node_data (struct cgraph_node *node, void *data ATTRIBUTE_UNUSED)
853 if (get_reference_vars_info (node))
854 clean_function (node);
857 /* Analyze each function in the cgraph to see which global or statics
858 are read or written. */
861 generate_summary (void)
863 struct cgraph_node *node;
864 struct varpool_node *vnode;
867 bitmap module_statics_readonly;
870 function_insertion_hook_holder =
871 cgraph_add_function_insertion_hook (&add_new_function, NULL);
872 node_removal_hook_holder =
873 cgraph_add_node_removal_hook (&remove_node_data, NULL);
874 node_duplication_hook_holder =
875 cgraph_add_node_duplication_hook (&duplicate_node_data, NULL);
877 module_statics_readonly = BITMAP_ALLOC (&local_info_obstack);
878 bm_temp = BITMAP_ALLOC (&local_info_obstack);
880 /* Process all of the variables first. */
881 FOR_EACH_STATIC_INITIALIZER (vnode)
882 analyze_variable (vnode);
884 /* Process all of the functions next.
886 We do not want to process any of the clones so we check that this
887 is a master clone. However, we do need to process any
888 AVAIL_OVERWRITABLE functions (these are never clones) because
889 they may cause a static variable to escape. The code that can
890 overwrite such a function cannot access the statics because it
891 would not be in the same compilation unit. When the analysis is
892 finished, the computed information of these AVAIL_OVERWRITABLE is
893 replaced with worst case info.
895 for (node = cgraph_nodes; node; node = node->next)
896 if (cgraph_function_body_availability (node) >= AVAIL_OVERWRITABLE)
897 analyze_function (node);
899 pointer_set_destroy (visited_nodes);
900 visited_nodes = NULL;
902 /* Prune out the variables that were found to behave badly
903 (i.e. have their address taken). */
904 EXECUTE_IF_SET_IN_BITMAP (module_statics_escape, 0, index, bi)
906 splay_tree_remove (reference_vars_to_consider, index);
909 bitmap_and_compl_into (all_module_statics,
910 module_statics_escape);
912 bitmap_and_compl (module_statics_readonly, all_module_statics,
913 module_statics_written);
915 /* If the address is not taken, we can unset the addressable bit
917 EXECUTE_IF_SET_IN_BITMAP (all_module_statics, 0, index, bi)
919 tree var = get_static_decl (index);
920 TREE_ADDRESSABLE (var) = 0;
922 fprintf (dump_file, "Not TREE_ADDRESSABLE var %s\n",
923 get_static_name (index));
926 /* If the variable is never written, we can set the TREE_READONLY
927 flag. Additionally if it has a DECL_INITIAL that is made up of
928 constants we can treat the entire global as a constant. */
930 bitmap_and_compl (module_statics_readonly, all_module_statics,
931 module_statics_written);
932 EXECUTE_IF_SET_IN_BITMAP (module_statics_readonly, 0, index, bi)
934 tree var = get_static_decl (index);
936 /* Ignore variables in named sections - changing TREE_READONLY
937 changes the section flags, potentially causing conflicts with
938 other variables in the same named section. */
939 if (DECL_SECTION_NAME (var) == NULL_TREE)
941 TREE_READONLY (var) = 1;
943 fprintf (dump_file, "read-only var %s\n",
944 get_static_name (index));
948 BITMAP_FREE(module_statics_escape);
949 BITMAP_FREE(module_statics_written);
950 module_statics_escape = NULL;
951 module_statics_written = NULL;
954 EXECUTE_IF_SET_IN_BITMAP (all_module_statics, 0, index, bi)
956 fprintf (dump_file, "\nPromotable global:%s",
957 get_static_name (index));
960 for (node = cgraph_nodes; node; node = node->next)
961 if (cgraph_function_body_availability (node) >= AVAIL_OVERWRITABLE)
963 ipa_reference_local_vars_info_t l;
964 l = get_reference_vars_info (node)->local;
966 /* Any variables that are not in all_module_statics are
967 removed from the local maps. This will include all of the
968 variables that were found to escape in the function
970 bitmap_and_into (l->statics_read,
972 bitmap_and_into (l->statics_written,
976 BITMAP_FREE(module_statics_readonly);
977 BITMAP_FREE(bm_temp);
980 for (node = cgraph_nodes; node; node = node->next)
981 if (cgraph_function_body_availability (node) >= AVAIL_OVERWRITABLE)
983 ipa_reference_local_vars_info_t l;
987 l = get_reference_vars_info (node)->local;
989 "\nFunction name:%s/%i:",
990 cgraph_node_name (node), node->uid);
991 fprintf (dump_file, "\n locals read: ");
992 EXECUTE_IF_SET_IN_BITMAP (l->statics_read,
995 fprintf (dump_file, "%s ",
996 get_static_name (index));
998 fprintf (dump_file, "\n locals written: ");
999 EXECUTE_IF_SET_IN_BITMAP (l->statics_written,
1002 fprintf(dump_file, "%s ",
1003 get_static_name (index));
1005 if (l->calls_read_all)
1006 fprintf (dump_file, "\n calls read all: ");
1007 if (l->calls_write_all)
1008 fprintf (dump_file, "\n calls read all: ");
1012 /* Produce the global information by preforming a transitive closure
1013 on the local information that was produced by ipa_analyze_function
1014 and ipa_analyze_variable. */
1019 struct cgraph_node *node;
1020 struct cgraph_node *w;
1021 struct cgraph_node **order =
1022 XCNEWVEC (struct cgraph_node *, cgraph_n_nodes);
1023 int order_pos = ipa_utils_reduced_inorder (order, false, true);
1026 cgraph_remove_function_insertion_hook (function_insertion_hook_holder);
1028 dump_cgraph (dump_file);
1030 /* Propagate the local information thru the call graph to produce
1031 the global information. All the nodes within a cycle will have
1032 the same info so we collapse cycles first. Then we can do the
1033 propagation in one pass from the leaves to the roots. */
1034 order_pos = ipa_utils_reduced_inorder (order, true, true);
1036 ipa_utils_print_order(dump_file, "reduced", order, order_pos);
1038 for (i = 0; i < order_pos; i++ )
1040 ipa_reference_vars_info_t node_info;
1041 ipa_reference_global_vars_info_t node_g =
1042 XCNEW (struct ipa_reference_global_vars_info_d);
1043 ipa_reference_local_vars_info_t node_l;
1047 struct ipa_dfs_info * w_info;
1050 node_info = get_reference_vars_info (node);
1053 dump_cgraph_node (stderr, node);
1054 dump_cgraph (stderr);
1058 gcc_assert (!node_info->global);
1059 node_l = node_info->local;
1061 read_all = node_l->calls_read_all;
1062 write_all = node_l->calls_write_all;
1064 /* If any node in a cycle is calls_read_all or calls_write_all
1066 w_info = (struct ipa_dfs_info *) node->aux;
1067 w = w_info->next_cycle;
1070 ipa_reference_local_vars_info_t w_l =
1071 get_reference_vars_info (w)->local;
1072 read_all |= w_l->calls_read_all;
1073 write_all |= w_l->calls_write_all;
1075 w_info = (struct ipa_dfs_info *) w->aux;
1076 w = w_info->next_cycle;
1079 /* Initialized the bitmaps for the reduced nodes */
1081 node_g->statics_read = all_module_statics;
1084 node_g->statics_read = BITMAP_ALLOC (&global_info_obstack);
1085 bitmap_copy (node_g->statics_read,
1086 node_l->statics_read);
1090 node_g->statics_written = all_module_statics;
1093 node_g->statics_written = BITMAP_ALLOC (&global_info_obstack);
1094 bitmap_copy (node_g->statics_written,
1095 node_l->statics_written);
1098 propagate_bits (node_g, node);
1099 w_info = (struct ipa_dfs_info *) node->aux;
1100 w = w_info->next_cycle;
1103 ipa_reference_vars_info_t w_ri =
1104 get_reference_vars_info (w);
1105 ipa_reference_local_vars_info_t w_l = w_ri->local;
1107 /* These global bitmaps are initialized from the local info
1108 of all of the nodes in the region. However there is no
1109 need to do any work if the bitmaps were set to
1110 all_module_statics. */
1112 bitmap_ior_into (node_g->statics_read,
1115 bitmap_ior_into (node_g->statics_written,
1116 w_l->statics_written);
1117 propagate_bits (node_g, w);
1118 w_info = (struct ipa_dfs_info *) w->aux;
1119 w = w_info->next_cycle;
1122 /* All nodes within a cycle have the same global info bitmaps. */
1123 node_info->global = node_g;
1124 w_info = (struct ipa_dfs_info *) node->aux;
1125 w = w_info->next_cycle;
1128 ipa_reference_vars_info_t w_ri =
1129 get_reference_vars_info (w);
1131 gcc_assert (!w_ri->global);
1132 w_ri->global = XCNEW (struct ipa_reference_global_vars_info_d);
1133 w_ri->global->statics_read = copy_global_bitmap (node_g->statics_read);
1134 w_ri->global->statics_written = copy_global_bitmap (node_g->statics_written);
1136 w_info = (struct ipa_dfs_info *) w->aux;
1137 w = w_info->next_cycle;
1143 for (i = 0; i < order_pos; i++ )
1145 ipa_reference_vars_info_t node_info;
1146 ipa_reference_global_vars_info_t node_g;
1147 ipa_reference_local_vars_info_t node_l;
1150 struct ipa_dfs_info * w_info;
1153 node_info = get_reference_vars_info (node);
1154 node_g = node_info->global;
1155 node_l = node_info->local;
1157 "\nFunction name:%s/%i:",
1158 cgraph_node_name (node), node->uid);
1159 fprintf (dump_file, "\n locals read: ");
1160 EXECUTE_IF_SET_IN_BITMAP (node_l->statics_read,
1163 fprintf (dump_file, "%s ",
1164 get_static_name (index));
1166 fprintf (dump_file, "\n locals written: ");
1167 EXECUTE_IF_SET_IN_BITMAP (node_l->statics_written,
1170 fprintf(dump_file, "%s ",
1171 get_static_name (index));
1174 w_info = (struct ipa_dfs_info *) node->aux;
1175 w = w_info->next_cycle;
1178 ipa_reference_vars_info_t w_ri =
1179 get_reference_vars_info (w);
1180 ipa_reference_local_vars_info_t w_l = w_ri->local;
1181 fprintf (dump_file, "\n next cycle: %s/%i ",
1182 cgraph_node_name (w), w->uid);
1183 fprintf (dump_file, "\n locals read: ");
1184 EXECUTE_IF_SET_IN_BITMAP (w_l->statics_read,
1187 fprintf (dump_file, "%s ",
1188 get_static_name (index));
1191 fprintf (dump_file, "\n locals written: ");
1192 EXECUTE_IF_SET_IN_BITMAP (w_l->statics_written,
1195 fprintf(dump_file, "%s ",
1196 get_static_name (index));
1200 w_info = (struct ipa_dfs_info *) w->aux;
1201 w = w_info->next_cycle;
1203 fprintf (dump_file, "\n globals read: ");
1204 EXECUTE_IF_SET_IN_BITMAP (node_g->statics_read,
1207 fprintf (dump_file, "%s ",
1208 get_static_name (index));
1210 fprintf (dump_file, "\n globals written: ");
1211 EXECUTE_IF_SET_IN_BITMAP (node_g->statics_written,
1214 fprintf (dump_file, "%s ",
1215 get_static_name (index));
1221 for (i = 0; i < order_pos; i++ )
1223 ipa_reference_vars_info_t node_info;
1224 ipa_reference_global_vars_info_t node_g;
1226 node_info = get_reference_vars_info (node);
1227 node_g = node_info->global;
1229 /* Create the complimentary sets. These are more useful for
1231 node_g->statics_not_read = BITMAP_ALLOC (&global_info_obstack);
1232 node_g->statics_not_written = BITMAP_ALLOC (&global_info_obstack);
1234 if (node_g->statics_read != all_module_statics)
1235 bitmap_and_compl (node_g->statics_not_read,
1237 node_g->statics_read);
1239 if (node_g->statics_written
1240 != all_module_statics)
1241 bitmap_and_compl (node_g->statics_not_written,
1243 node_g->statics_written);
1248 for (node = cgraph_nodes; node; node = node->next)
1250 ipa_reference_vars_info_t node_info;
1251 node_info = get_reference_vars_info (node);
1252 /* Get rid of the aux information. */
1260 if (cgraph_function_body_availability (node) == AVAIL_OVERWRITABLE)
1261 clean_function (node);
1263 clean_function_local_data (node);
1265 bitmap_obstack_release (&local_info_obstack);
1271 gate_reference (void)
1273 return (flag_ipa_reference
1274 /* Don't bother doing anything if the program has errors. */
1275 && !(errorcount || sorrycount));
1278 struct ipa_opt_pass pass_ipa_reference =
1282 "static-var", /* name */
1283 gate_reference, /* gate */
1284 propagate, /* execute */
1287 0, /* static_pass_number */
1288 TV_IPA_REFERENCE, /* tv_id */
1289 0, /* properties_required */
1290 0, /* properties_provided */
1291 0, /* properties_destroyed */
1292 0, /* todo_flags_start */
1293 0 /* todo_flags_finish */
1295 generate_summary, /* generate_summary */
1296 NULL, /* write_summary */
1297 NULL, /* read_summary */
1298 NULL, /* function_read_summary */
1300 NULL, /* function_transform */
1301 NULL /* variable_transform */
1304 #include "gt-ipa-reference.h"