1 /* Interprocedural constant propagation
2 Copyright (C) 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
3 Contributed by Razya Ladelsky <RAZYA@il.ibm.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 /* Interprocedural constant propagation. The aim of interprocedural constant
22 propagation (IPCP) is to find which function's argument has the same
23 constant value in each invocation throughout the whole program. For example,
24 consider the following program:
28 printf ("value is %d",y);
48 The IPCP algorithm will find that g's formal argument y is always called
51 The algorithm used is based on "Interprocedural Constant Propagation", by
52 Challahan David, Keith D Cooper, Ken Kennedy, Linda Torczon, Comp86, pg
55 The optimization is divided into three stages:
57 First stage - intraprocedural analysis
58 =======================================
59 This phase computes jump_function and modification flags.
61 A jump function for a callsite represents the values passed as an actual
62 arguments of a given callsite. There are three types of values:
63 Pass through - the caller's formal parameter is passed as an actual argument.
64 Constant - a constant is passed as an actual argument.
65 Unknown - neither of the above.
67 The jump function info, ipa_jump_func, is stored in ipa_edge_args
68 structure (defined in ipa_prop.h and pointed to by cgraph_node->aux)
69 modified_flags are defined in ipa_node_params structure
70 (defined in ipa_prop.h and pointed to by cgraph_edge->aux).
72 -ipcp_init_stage() is the first stage driver.
74 Second stage - interprocedural analysis
75 ========================================
76 This phase does the interprocedural constant propagation.
77 It computes lattices for all formal parameters in the program
78 and their value that may be:
80 BOTTOM - non constant.
81 CONSTANT - constant value.
83 Lattice describing a formal parameter p will have a constant value if all
84 callsites invoking this function have the same constant value passed to p.
86 The lattices are stored in ipcp_lattice which is itself in ipa_node_params
87 structure (defined in ipa_prop.h and pointed to by cgraph_edge->aux).
89 -ipcp_iterate_stage() is the second stage driver.
91 Third phase - transformation of function code
92 ============================================
93 Propagates the constant-valued formals into the function.
94 For each function whose parameters are constants, we create its clone.
96 Then we process the clone in two ways:
97 1. We insert an assignment statement 'parameter = const' at the beginning
98 of the cloned function.
99 2. For read-only parameters that do not live in memory, we replace all their
100 uses with the constant.
102 We also need to modify some callsites to call the cloned functions instead
103 of the original ones. For a callsite passing an argument found to be a
104 constant by IPCP, there are two different cases to handle:
105 1. A constant is passed as an argument. In this case the callsite in the
106 should be redirected to call the cloned callee.
107 2. A parameter (of the caller) passed as an argument (pass through
108 argument). In such cases both the caller and the callee have clones and
109 only the callsite in the cloned caller is redirected to call to the
112 This update is done in two steps: First all cloned functions are created
113 during a traversal of the call graph, during which all callsites are
114 redirected to call the cloned function. Then the callsites are traversed
115 and many calls redirected back to fit the description above.
117 -ipcp_insert_stage() is the third phase driver.
123 #include "coretypes.h"
127 #include "ipa-prop.h"
128 #include "tree-flow.h"
129 #include "tree-pass.h"
132 #include "diagnostic.h"
133 #include "tree-dump.h"
134 #include "tree-inline.h"
138 /* Number of functions identified as candidates for cloning. When not cloning
139 we can simplify iterate stage not forcing it to go through the decision
140 on what is profitable and what not. */
141 static int n_cloning_candidates;
143 /* Maximal count found in program. */
144 static gcov_type max_count;
146 /* Cgraph nodes that has been completely replaced by cloning during iterate
147 * stage and will be removed after ipcp is finished. */
148 static bitmap dead_nodes;
150 static void ipcp_print_profile_data (FILE *);
151 static void ipcp_function_scale_print (FILE *);
153 /* Get the original node field of ipa_node_params associated with node NODE. */
154 static inline struct cgraph_node *
155 ipcp_get_orig_node (struct cgraph_node *node)
157 return IPA_NODE_REF (node)->ipcp_orig_node;
160 /* Return true if NODE describes a cloned/versioned function. */
162 ipcp_node_is_clone (struct cgraph_node *node)
164 return (ipcp_get_orig_node (node) != NULL);
167 /* Create ipa_node_params and its data structures for NEW_NODE. Set ORIG_NODE
168 as the ipcp_orig_node field in ipa_node_params. */
170 ipcp_init_cloned_node (struct cgraph_node *orig_node,
171 struct cgraph_node *new_node)
173 ipa_check_create_node_params ();
174 ipa_initialize_node_params (new_node);
175 IPA_NODE_REF (new_node)->ipcp_orig_node = orig_node;
178 /* Perform intraprocedrual analysis needed for ipcp. */
180 ipcp_analyze_node (struct cgraph_node *node)
182 /* Unreachable nodes should have been eliminated before ipcp. */
183 gcc_assert (node->needed || node->reachable);
185 ipa_initialize_node_params (node);
186 ipa_detect_param_modifications (node);
189 /* Return scale for NODE. */
190 static inline gcov_type
191 ipcp_get_node_scale (struct cgraph_node *node)
193 return IPA_NODE_REF (node)->count_scale;
196 /* Set COUNT as scale for NODE. */
198 ipcp_set_node_scale (struct cgraph_node *node, gcov_type count)
200 IPA_NODE_REF (node)->count_scale = count;
203 /* Return whether LAT is a constant lattice. */
205 ipcp_lat_is_const (struct ipcp_lattice *lat)
207 if (lat->type == IPA_CONST_VALUE)
213 /* Return whether LAT is a constant lattice that ipa-cp can actually insert
214 into the code (i.e. constants excluding member pointers and pointers). */
216 ipcp_lat_is_insertable (struct ipcp_lattice *lat)
218 return lat->type == IPA_CONST_VALUE;
221 /* Return true if LAT1 and LAT2 are equal. */
223 ipcp_lats_are_equal (struct ipcp_lattice *lat1, struct ipcp_lattice *lat2)
225 gcc_assert (ipcp_lat_is_const (lat1) && ipcp_lat_is_const (lat2));
226 if (lat1->type != lat2->type)
229 if (operand_equal_p (lat1->constant, lat2->constant, 0))
235 /* Compute Meet arithmetics:
236 Meet (IPA_BOTTOM, x) = IPA_BOTTOM
238 Meet (const_a,const_b) = IPA_BOTTOM, if const_a != const_b.
239 MEET (const_a,const_b) = const_a, if const_a == const_b.*/
241 ipa_lattice_meet (struct ipcp_lattice *res, struct ipcp_lattice *lat1,
242 struct ipcp_lattice *lat2)
244 if (lat1->type == IPA_BOTTOM || lat2->type == IPA_BOTTOM)
246 res->type = IPA_BOTTOM;
249 if (lat1->type == IPA_TOP)
251 res->type = lat2->type;
252 res->constant = lat2->constant;
255 if (lat2->type == IPA_TOP)
257 res->type = lat1->type;
258 res->constant = lat1->constant;
261 if (!ipcp_lats_are_equal (lat1, lat2))
263 res->type = IPA_BOTTOM;
266 res->type = lat1->type;
267 res->constant = lat1->constant;
270 /* Return the lattice corresponding to the Ith formal parameter of the function
271 described by INFO. */
272 static inline struct ipcp_lattice *
273 ipcp_get_lattice (struct ipa_node_params *info, int i)
275 return &(info->params[i].ipcp_lattice);
278 /* Given the jump function JFUNC, compute the lattice LAT that describes the
279 value coming down the callsite. INFO describes the caller node so that
280 pass-through jump functions can be evaluated. */
282 ipcp_lattice_from_jfunc (struct ipa_node_params *info, struct ipcp_lattice *lat,
283 struct ipa_jump_func *jfunc)
285 if (jfunc->type == IPA_JF_CONST)
287 lat->type = IPA_CONST_VALUE;
288 lat->constant = jfunc->value.constant;
290 else if (jfunc->type == IPA_JF_PASS_THROUGH)
292 struct ipcp_lattice *caller_lat;
294 caller_lat = ipcp_get_lattice (info, jfunc->value.formal_id);
295 lat->type = caller_lat->type;
296 lat->constant = caller_lat->constant;
299 lat->type = IPA_BOTTOM;
302 /* True when OLD_LAT and NEW_LAT values are not the same. */
305 ipcp_lattice_changed (struct ipcp_lattice *old_lat,
306 struct ipcp_lattice *new_lat)
308 if (old_lat->type == new_lat->type)
310 if (!ipcp_lat_is_const (old_lat))
312 if (ipcp_lats_are_equal (old_lat, new_lat))
318 /* Print all ipcp_lattices of all functions to F. */
320 ipcp_print_all_lattices (FILE * f)
322 struct cgraph_node *node;
325 fprintf (f, "\nLattice:\n");
326 for (node = cgraph_nodes; node; node = node->next)
328 struct ipa_node_params *info;
332 info = IPA_NODE_REF (node);
333 fprintf (f, " Node: %s:\n", cgraph_node_name (node));
334 count = ipa_get_param_count (info);
335 for (i = 0; i < count; i++)
337 struct ipcp_lattice *lat = ipcp_get_lattice (info, i);
339 fprintf (f, " param [%d]: ", i);
340 if (lat->type == IPA_CONST_VALUE)
342 fprintf (f, "type is CONST ");
343 print_generic_expr (f, lat->constant, 0);
346 else if (lat->type == IPA_TOP)
347 fprintf (f, "type is TOP\n");
349 fprintf (f, "type is BOTTOM\n");
354 /* Return true if this NODE is viable candidate for cloning. */
356 ipcp_cloning_candidate_p (struct cgraph_node *node)
360 gcov_type direct_call_sum = 0;
361 struct cgraph_edge *e;
363 /* We never clone functions that are not visible from outside.
364 FIXME: in future we should clone such functions when they are called with
365 different constants, but current ipcp implementation is not good on this.
367 if (!node->needed || !node->analyzed)
370 if (cgraph_function_body_availability (node) <= AVAIL_OVERWRITABLE)
373 fprintf (dump_file, "Not considering %s for cloning; body is overwrittable.\n",
374 cgraph_node_name (node));
377 if (!tree_versionable_function_p (node->decl))
380 fprintf (dump_file, "Not considering %s for cloning; body is not versionable.\n",
381 cgraph_node_name (node));
384 for (e = node->callers; e; e = e->next_caller)
386 direct_call_sum += e->count;
388 if (cgraph_maybe_hot_edge_p (e))
395 fprintf (dump_file, "Not considering %s for cloning; no direct calls.\n",
396 cgraph_node_name (node));
399 if (node->local.inline_summary.self_insns < n_calls)
402 fprintf (dump_file, "Considering %s for cloning; code would shrink.\n",
403 cgraph_node_name (node));
407 if (!flag_ipa_cp_clone)
410 fprintf (dump_file, "Not considering %s for cloning; -fipa-cp-clone disabled.\n",
411 cgraph_node_name (node));
415 if (!optimize_function_for_speed_p (DECL_STRUCT_FUNCTION (node->decl)))
418 fprintf (dump_file, "Not considering %s for cloning; optimizing it for size.\n",
419 cgraph_node_name (node));
423 /* When profile is available and function is hot, propagate into it even if
424 calls seems cold; constant propagation can improve function's speed
428 if (direct_call_sum > node->count * 90 / 100)
431 fprintf (dump_file, "Considering %s for cloning; usually called directly.\n",
432 cgraph_node_name (node));
439 fprintf (dump_file, "Not considering %s for cloning; no hot calls.\n",
440 cgraph_node_name (node));
444 fprintf (dump_file, "Considering %s for cloning.\n",
445 cgraph_node_name (node));
449 /* Initialize ipcp_lattices array. The lattices corresponding to supported
450 types (integers, real types and Fortran constants defined as const_decls)
451 are initialized to IPA_TOP, the rest of them to IPA_BOTTOM. */
453 ipcp_initialize_node_lattices (struct cgraph_node *node)
456 struct ipa_node_params *info = IPA_NODE_REF (node);
457 enum ipa_lattice_type type;
459 if (ipa_is_called_with_var_arguments (info))
461 else if (!node->needed)
463 /* When cloning is allowed, we can assume that externally visible functions
464 are not called. We will compensate this by cloning later. */
465 else if (ipcp_cloning_candidate_p (node))
466 type = IPA_TOP, n_cloning_candidates ++;
470 for (i = 0; i < ipa_get_param_count (info) ; i++)
471 ipcp_get_lattice (info, i)->type = type;
474 /* build INTEGER_CST tree with type TREE_TYPE and value according to LAT.
477 build_const_val (struct ipcp_lattice *lat, tree tree_type)
481 gcc_assert (ipcp_lat_is_const (lat));
484 if (!useless_type_conversion_p (tree_type, TREE_TYPE (val)))
486 if (fold_convertible_p (tree_type, val))
487 return fold_build1 (NOP_EXPR, tree_type, val);
489 return fold_build1 (VIEW_CONVERT_EXPR, tree_type, val);
494 /* Compute the proper scale for NODE. It is the ratio between the number of
495 direct calls (represented on the incoming cgraph_edges) and sum of all
496 invocations of NODE (represented as count in cgraph_node). */
498 ipcp_compute_node_scale (struct cgraph_node *node)
501 struct cgraph_edge *cs;
504 /* Compute sum of all counts of callers. */
505 for (cs = node->callers; cs != NULL; cs = cs->next_caller)
507 if (node->count == 0)
508 ipcp_set_node_scale (node, 0);
510 ipcp_set_node_scale (node, sum * REG_BR_PROB_BASE / node->count);
513 /* Initialization and computation of IPCP data structures. This is the initial
514 intraprocedural analysis of functions, which gathers information to be
515 propagated later on. */
517 ipcp_init_stage (void)
519 struct cgraph_node *node;
520 struct cgraph_edge *cs;
522 for (node = cgraph_nodes; node; node = node->next)
524 ipcp_analyze_node (node);
525 for (node = cgraph_nodes; node; node = node->next)
529 /* building jump functions */
530 for (cs = node->callees; cs; cs = cs->next_callee)
532 if (!cs->callee->analyzed)
534 ipa_count_arguments (cs);
535 if (ipa_get_cs_argument_count (IPA_EDGE_REF (cs))
536 != ipa_get_param_count (IPA_NODE_REF (cs->callee)))
538 /* Handle cases of functions with
539 a variable number of parameters. */
540 ipa_set_called_with_variable_arg (IPA_NODE_REF (cs->callee));
541 if (flag_indirect_inlining)
542 ipa_compute_jump_functions (cs);
545 ipa_compute_jump_functions (cs);
550 /* Return true if there are some formal parameters whose value is IPA_TOP (in
551 the whole compilation unit). Change their values to IPA_BOTTOM, since they
552 most probably get their values from outside of this compilation unit. */
554 ipcp_change_tops_to_bottom (void)
557 struct cgraph_node *node;
561 for (node = cgraph_nodes; node; node = node->next)
563 struct ipa_node_params *info = IPA_NODE_REF (node);
564 count = ipa_get_param_count (info);
565 for (i = 0; i < count; i++)
567 struct ipcp_lattice *lat = ipcp_get_lattice (info, i);
568 if (lat->type == IPA_TOP)
573 fprintf (dump_file, "Forcing param ");
574 print_generic_expr (dump_file, ipa_get_param (info, i), 0);
575 fprintf (dump_file, " of node %s to bottom.\n",
576 cgraph_node_name (node));
578 lat->type = IPA_BOTTOM;
585 /* Interprocedural analysis. The algorithm propagates constants from the
586 caller's parameters to the callee's arguments. */
588 ipcp_propagate_stage (void)
591 struct ipcp_lattice inc_lat = { IPA_BOTTOM, NULL };
592 struct ipcp_lattice new_lat = { IPA_BOTTOM, NULL };
593 struct ipcp_lattice *dest_lat;
594 struct cgraph_edge *cs;
595 struct ipa_jump_func *jump_func;
596 struct ipa_func_list *wl;
599 ipa_check_create_node_params ();
600 ipa_check_create_edge_args ();
602 /* Initialize worklist to contain all functions. */
603 wl = ipa_init_func_list ();
606 struct cgraph_node *node = ipa_pop_func_from_list (&wl);
607 struct ipa_node_params *info = IPA_NODE_REF (node);
609 for (cs = node->callees; cs; cs = cs->next_callee)
611 struct ipa_node_params *callee_info = IPA_NODE_REF (cs->callee);
612 struct ipa_edge_args *args = IPA_EDGE_REF (cs);
614 if (ipa_is_called_with_var_arguments (callee_info))
617 count = ipa_get_cs_argument_count (args);
618 for (i = 0; i < count; i++)
620 jump_func = ipa_get_ith_jump_func (args, i);
621 ipcp_lattice_from_jfunc (info, &inc_lat, jump_func);
622 dest_lat = ipcp_get_lattice (callee_info, i);
623 ipa_lattice_meet (&new_lat, &inc_lat, dest_lat);
624 if (ipcp_lattice_changed (&new_lat, dest_lat))
626 dest_lat->type = new_lat.type;
627 dest_lat->constant = new_lat.constant;
628 ipa_push_func_to_list (&wl, cs->callee);
635 /* Call the constant propagation algorithm and re-call it if necessary
636 (if there are undetermined values left). */
638 ipcp_iterate_stage (void)
640 struct cgraph_node *node;
641 n_cloning_candidates = 0;
644 fprintf (dump_file, "\nIPA iterate stage:\n\n");
645 for (node = cgraph_nodes; node; node = node->next)
647 ipcp_initialize_node_lattices (node);
648 ipcp_compute_node_scale (node);
650 if (dump_file && (dump_flags & TDF_DETAILS))
652 ipcp_print_all_lattices (dump_file);
653 ipcp_function_scale_print (dump_file);
656 ipcp_propagate_stage ();
657 if (ipcp_change_tops_to_bottom ())
658 /* Some lattices have changed from IPA_TOP to IPA_BOTTOM.
659 This change should be propagated. */
661 gcc_assert (n_cloning_candidates);
662 ipcp_propagate_stage ();
666 fprintf (dump_file, "\nIPA lattices after propagation:\n");
667 ipcp_print_all_lattices (dump_file);
668 if (dump_flags & TDF_DETAILS)
669 ipcp_print_profile_data (dump_file);
673 /* Check conditions to forbid constant insertion to function described by
676 ipcp_node_modifiable_p (struct cgraph_node *node)
678 /* Once we will be able to do in-place replacement, we can be more
680 return tree_versionable_function_p (node->decl);
683 /* Print count scale data structures. */
685 ipcp_function_scale_print (FILE * f)
687 struct cgraph_node *node;
689 for (node = cgraph_nodes; node; node = node->next)
693 fprintf (f, "printing scale for %s: ", cgraph_node_name (node));
694 fprintf (f, "value is " HOST_WIDE_INT_PRINT_DEC
695 " \n", (HOST_WIDE_INT) ipcp_get_node_scale (node));
699 /* Print counts of all cgraph nodes. */
701 ipcp_print_func_profile_counts (FILE * f)
703 struct cgraph_node *node;
705 for (node = cgraph_nodes; node; node = node->next)
707 fprintf (f, "function %s: ", cgraph_node_name (node));
708 fprintf (f, "count is " HOST_WIDE_INT_PRINT_DEC
709 " \n", (HOST_WIDE_INT) node->count);
713 /* Print counts of all cgraph edges. */
715 ipcp_print_call_profile_counts (FILE * f)
717 struct cgraph_node *node;
718 struct cgraph_edge *cs;
720 for (node = cgraph_nodes; node; node = node->next)
722 for (cs = node->callees; cs; cs = cs->next_callee)
724 fprintf (f, "%s -> %s ", cgraph_node_name (cs->caller),
725 cgraph_node_name (cs->callee));
726 fprintf (f, "count is " HOST_WIDE_INT_PRINT_DEC " \n",
727 (HOST_WIDE_INT) cs->count);
732 /* Print profile info for all functions. */
734 ipcp_print_profile_data (FILE * f)
736 fprintf (f, "\nNODE COUNTS :\n");
737 ipcp_print_func_profile_counts (f);
738 fprintf (f, "\nCS COUNTS stage:\n");
739 ipcp_print_call_profile_counts (f);
742 /* Build and initialize ipa_replace_map struct according to LAT. This struct is
743 processed by versioning, which operates according to the flags set.
744 PARM_TREE is the formal parameter found to be constant. LAT represents the
746 static struct ipa_replace_map *
747 ipcp_create_replace_map (tree parm_tree, struct ipcp_lattice *lat)
749 struct ipa_replace_map *replace_map;
752 replace_map = GGC_NEW (struct ipa_replace_map);
753 const_val = build_const_val (lat, TREE_TYPE (parm_tree));
756 fprintf (dump_file, " replacing param ");
757 print_generic_expr (dump_file, parm_tree, 0);
758 fprintf (dump_file, " with const ");
759 print_generic_expr (dump_file, const_val, 0);
760 fprintf (dump_file, "\n");
762 replace_map->old_tree = parm_tree;
763 replace_map->new_tree = const_val;
764 replace_map->replace_p = true;
765 replace_map->ref_p = false;
770 /* Return true if this callsite should be redirected to the original callee
771 (instead of the cloned one). */
773 ipcp_need_redirect_p (struct cgraph_edge *cs)
775 struct ipa_node_params *orig_callee_info;
777 struct ipa_jump_func *jump_func;
778 struct cgraph_node *node = cs->callee, *orig;
780 if (!n_cloning_candidates)
783 if ((orig = ipcp_get_orig_node (node)) != NULL)
785 if (ipcp_get_orig_node (cs->caller))
788 orig_callee_info = IPA_NODE_REF (node);
789 count = ipa_get_param_count (orig_callee_info);
790 for (i = 0; i < count; i++)
792 struct ipcp_lattice *lat = ipcp_get_lattice (orig_callee_info, i);
793 if (ipcp_lat_is_const (lat))
795 jump_func = ipa_get_ith_jump_func (IPA_EDGE_REF (cs), i);
796 if (jump_func->type != IPA_JF_CONST)
804 /* Fix the callsites and the call graph after function cloning was done. */
806 ipcp_update_callgraph (void)
808 struct cgraph_node *node;
810 for (node = cgraph_nodes; node; node = node->next)
811 if (node->analyzed && ipcp_node_is_clone (node))
813 bitmap args_to_skip = BITMAP_ALLOC (NULL);
814 struct cgraph_node *orig_node = ipcp_get_orig_node (node);
815 struct ipa_node_params *info = IPA_NODE_REF (orig_node);
816 int i, count = ipa_get_param_count (info);
817 struct cgraph_edge *cs, *next;
819 for (i = 0; i < count; i++)
821 struct ipcp_lattice *lat = ipcp_get_lattice (info, i);
822 tree parm_tree = ipa_get_param (info, i);
824 /* We can proactively remove obviously unused arguments. */
825 if (is_gimple_reg (parm_tree)
826 && !gimple_default_def (DECL_STRUCT_FUNCTION (orig_node->decl),
829 bitmap_set_bit (args_to_skip, i);
833 if (lat->type == IPA_CONST_VALUE)
834 bitmap_set_bit (args_to_skip, i);
836 for (cs = node->callers; cs; cs = next)
838 next = cs->next_caller;
839 if (!ipcp_node_is_clone (cs->caller) && ipcp_need_redirect_p (cs))
841 cgraph_redirect_edge_callee (cs, orig_node);
842 gimple_call_set_fndecl (cs->call_stmt, orig_node->decl);
848 /* Update profiling info for versioned functions and the functions they were
851 ipcp_update_profiling (void)
853 struct cgraph_node *node, *orig_node;
854 gcov_type scale, scale_complement;
855 struct cgraph_edge *cs;
857 for (node = cgraph_nodes; node; node = node->next)
859 if (ipcp_node_is_clone (node))
861 orig_node = ipcp_get_orig_node (node);
862 scale = ipcp_get_node_scale (orig_node);
863 node->count = orig_node->count * scale / REG_BR_PROB_BASE;
864 scale_complement = REG_BR_PROB_BASE - scale;
866 orig_node->count * scale_complement / REG_BR_PROB_BASE;
867 for (cs = node->callees; cs; cs = cs->next_callee)
868 cs->count = cs->count * scale / REG_BR_PROB_BASE;
869 for (cs = orig_node->callees; cs; cs = cs->next_callee)
870 cs->count = cs->count * scale_complement / REG_BR_PROB_BASE;
875 /* If NODE was cloned, how much would program grow? */
877 ipcp_estimate_growth (struct cgraph_node *node)
879 struct cgraph_edge *cs;
880 int redirectable_node_callers = 0;
881 int removable_args = 0;
882 bool need_original = node->needed;
883 struct ipa_node_params *info;
887 for (cs = node->callers; cs != NULL; cs = cs->next_caller)
888 if (cs->caller == node || !ipcp_need_redirect_p (cs))
889 redirectable_node_callers++;
891 need_original = true;
893 /* If we will be able to fully replace orignal node, we never increase
898 info = IPA_NODE_REF (node);
899 count = ipa_get_param_count (info);
900 for (i = 0; i < count; i++)
902 struct ipcp_lattice *lat = ipcp_get_lattice (info, i);
903 tree parm_tree = ipa_get_param (info, i);
905 /* We can proactively remove obviously unused arguments. */
906 if (is_gimple_reg (parm_tree)
907 && !gimple_default_def (DECL_STRUCT_FUNCTION (node->decl),
911 if (lat->type == IPA_CONST_VALUE)
915 /* We make just very simple estimate of savings for removal of operand from
916 call site. Precise cost is dificult to get, as our size metric counts
917 constants and moves as free. Generally we are looking for cases that
918 small function is called very many times. */
919 growth = node->local.inline_summary.self_insns
920 - removable_args * redirectable_node_callers;
927 /* Estimate cost of cloning NODE. */
929 ipcp_estimate_cloning_cost (struct cgraph_node *node)
932 gcov_type count_sum = 1;
933 struct cgraph_edge *e;
936 cost = ipcp_estimate_growth (node) * 1000;
940 fprintf (dump_file, "Versioning of %s will save code size\n",
941 cgraph_node_name (node));
945 for (e = node->callers; e; e = e->next_caller)
946 if (!bitmap_bit_p (dead_nodes, e->caller->uid)
947 && !ipcp_need_redirect_p (e))
949 count_sum += e->count;
950 freq_sum += e->frequency + 1;
954 cost /= count_sum * 1000 / max_count + 1;
956 cost /= freq_sum * 1000 / REG_BR_PROB_BASE + 1;
958 fprintf (dump_file, "Cost of versioning %s is %i, (size: %i, freq: %i)\n",
959 cgraph_node_name (node), cost, node->local.inline_summary.self_insns,
964 /* Return number of live constant parameters. */
966 ipcp_const_param_count (struct cgraph_node *node)
969 struct ipa_node_params *info = IPA_NODE_REF (node);
970 int count = ipa_get_param_count (info);
973 for (i = 0; i < count; i++)
975 struct ipcp_lattice *lat = ipcp_get_lattice (info, i);
976 tree parm_tree = ipa_get_param (info, i);
977 if (ipcp_lat_is_insertable (lat)
978 /* Do not count obviously unused arguments. */
979 && (!is_gimple_reg (parm_tree)
980 || gimple_default_def (DECL_STRUCT_FUNCTION (node->decl),
987 /* Propagate the constant parameters found by ipcp_iterate_stage()
988 to the function's code. */
990 ipcp_insert_stage (void)
992 struct cgraph_node *node, *node1 = NULL;
994 VEC (cgraph_edge_p, heap) * redirect_callers;
995 VEC (ipa_replace_map_p,gc)* replace_trees;
996 int node_callers, count;
998 struct ipa_replace_map *replace_param;
1000 long overall_size = 0, new_size = 0;
1003 ipa_check_create_node_params ();
1004 ipa_check_create_edge_args ();
1006 fprintf (dump_file, "\nIPA insert stage:\n\n");
1008 dead_nodes = BITMAP_ALLOC (NULL);
1010 for (node = cgraph_nodes; node; node = node->next)
1013 if (node->count > max_count)
1014 max_count = node->count;
1015 overall_size += node->local.inline_summary.self_insns;
1018 max_new_size = overall_size;
1019 if (max_new_size < PARAM_VALUE (PARAM_LARGE_UNIT_INSNS))
1020 max_new_size = PARAM_VALUE (PARAM_LARGE_UNIT_INSNS);
1021 max_new_size = max_new_size * PARAM_VALUE (PARAM_IPCP_UNIT_GROWTH) / 100 + 1;
1023 /* First collect all functions we proved to have constant arguments to heap. */
1024 heap = fibheap_new ();
1025 for (node = cgraph_nodes; node; node = node->next)
1027 struct ipa_node_params *info;
1028 /* Propagation of the constant is forbidden in certain conditions. */
1029 if (!node->analyzed || !ipcp_node_modifiable_p (node))
1031 info = IPA_NODE_REF (node);
1032 if (ipa_is_called_with_var_arguments (info))
1034 if (ipcp_const_param_count (node))
1035 node->aux = fibheap_insert (heap, ipcp_estimate_cloning_cost (node), node);
1038 /* Now clone in priority order until code size growth limits are met or
1040 while (!fibheap_empty (heap))
1042 struct ipa_node_params *info;
1044 bitmap args_to_skip;
1045 struct cgraph_edge *cs;
1047 node = (struct cgraph_node *)fibheap_extract_min (heap);
1050 fprintf (dump_file, "considering function %s\n",
1051 cgraph_node_name (node));
1053 growth = ipcp_estimate_growth (node);
1055 if (new_size + growth > max_new_size)
1058 && optimize_function_for_size_p (DECL_STRUCT_FUNCTION (node->decl)))
1061 fprintf (dump_file, "Not versioning, cold code would grow");
1067 /* Look if original function becomes dead after clonning. */
1068 for (cs = node->callers; cs != NULL; cs = cs->next_caller)
1069 if (cs->caller == node || ipcp_need_redirect_p (cs))
1071 if (!cs && !node->needed)
1072 bitmap_set_bit (dead_nodes, node->uid);
1074 info = IPA_NODE_REF (node);
1075 count = ipa_get_param_count (info);
1077 replace_trees = VEC_alloc (ipa_replace_map_p, gc, 1);
1078 args_to_skip = BITMAP_GGC_ALLOC ();
1079 for (i = 0; i < count; i++)
1081 struct ipcp_lattice *lat = ipcp_get_lattice (info, i);
1082 parm_tree = ipa_get_param (info, i);
1084 /* We can proactively remove obviously unused arguments. */
1085 if (is_gimple_reg (parm_tree)
1086 && !gimple_default_def (DECL_STRUCT_FUNCTION (node->decl),
1089 bitmap_set_bit (args_to_skip, i);
1093 if (lat->type == IPA_CONST_VALUE)
1096 ipcp_create_replace_map (parm_tree, lat);
1097 VEC_safe_push (ipa_replace_map_p, gc, replace_trees, replace_param);
1098 bitmap_set_bit (args_to_skip, i);
1102 /* Compute how many callers node has. */
1104 for (cs = node->callers; cs != NULL; cs = cs->next_caller)
1106 redirect_callers = VEC_alloc (cgraph_edge_p, heap, node_callers);
1107 for (cs = node->callers; cs != NULL; cs = cs->next_caller)
1108 VEC_quick_push (cgraph_edge_p, redirect_callers, cs);
1110 /* Redirecting all the callers of the node to the
1111 new versioned node. */
1113 cgraph_create_virtual_clone (node, redirect_callers, replace_trees,
1115 args_to_skip = NULL;
1116 VEC_free (cgraph_edge_p, heap, redirect_callers);
1117 replace_trees = NULL;
1122 fprintf (dump_file, "versioned function %s with growth %i, overall %i\n",
1123 cgraph_node_name (node), (int)growth, (int)new_size);
1124 ipcp_init_cloned_node (node, node1);
1126 /* TODO: We can use indirect inlning info to produce new calls. */
1129 dump_function_to_file (node1->decl, dump_file, dump_flags);
1131 for (cs = node->callees; cs; cs = cs->next_callee)
1132 if (cs->callee->aux)
1134 fibheap_delete_node (heap, (fibnode_t) cs->callee->aux);
1135 cs->callee->aux = fibheap_insert (heap,
1136 ipcp_estimate_cloning_cost (cs->callee),
1141 while (!fibheap_empty (heap))
1144 fprintf (dump_file, "skipping function %s\n",
1145 cgraph_node_name (node));
1146 node = (struct cgraph_node *) fibheap_extract_min (heap);
1149 fibheap_delete (heap);
1150 BITMAP_FREE (dead_nodes);
1151 ipcp_update_callgraph ();
1152 ipcp_update_profiling ();
1155 /* The IPCP driver. */
1159 cgraph_remove_unreachable_nodes (true,dump_file);
1162 fprintf (dump_file, "\nIPA structures before propagation:\n");
1163 if (dump_flags & TDF_DETAILS)
1164 ipa_print_all_params (dump_file);
1165 ipa_print_all_jump_functions (dump_file);
1167 /* 2. Do the interprocedural propagation. */
1168 ipcp_iterate_stage ();
1169 /* 3. Insert the constants found to the functions. */
1170 ipcp_insert_stage ();
1171 if (dump_file && (dump_flags & TDF_DETAILS))
1173 fprintf (dump_file, "\nProfiling info after insert stage:\n");
1174 ipcp_print_profile_data (dump_file);
1176 /* Free all IPCP structures. */
1177 free_all_ipa_structures_after_ipa_cp ();
1179 fprintf (dump_file, "\nIPA constant propagation end\n");
1183 /* Note function body size. */
1185 ipcp_generate_summary (void)
1188 fprintf (dump_file, "\nIPA constant propagation start:\n");
1189 ipa_check_create_node_params ();
1190 ipa_check_create_edge_args ();
1191 ipa_register_cgraph_hooks ();
1192 /* 1. Call the init stage to initialize
1193 the ipa_node_params and ipa_edge_args structures. */
1197 /* Gate for IPCP optimization. */
1199 cgraph_gate_cp (void)
1204 struct ipa_opt_pass pass_ipa_cp =
1209 cgraph_gate_cp, /* gate */
1210 ipcp_driver, /* execute */
1213 0, /* static_pass_number */
1214 TV_IPA_CONSTANT_PROP, /* tv_id */
1215 0, /* properties_required */
1216 0, /* properties_provided */
1217 0, /* properties_destroyed */
1218 0, /* todo_flags_start */
1219 TODO_dump_cgraph | TODO_dump_func |
1220 TODO_remove_functions /* todo_flags_finish */
1222 ipcp_generate_summary, /* generate_summary */
1223 NULL, /* write_summary */
1224 NULL, /* read_summary */
1225 NULL, /* function_read_summary */
1227 NULL, /* function_transform */
1228 NULL, /* variable_transform */