1 /* Interprocedural constant propagation
2 Copyright (C) 2005, 2006, 2007, 2008, 2009 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;
295 caller_lat = ipcp_get_lattice (info, jfunc->value.pass_through.formal_id);
296 lat->type = caller_lat->type;
297 if (caller_lat->type != IPA_CONST_VALUE)
299 cst = caller_lat->constant;
301 if (jfunc->value.pass_through.operation != NOP_EXPR)
302 cst = fold_binary (jfunc->value.pass_through.operation,
303 TREE_TYPE (cst), cst,
304 jfunc->value.pass_through.operand);
305 gcc_assert (cst && is_gimple_ip_invariant (cst));
308 else if (jfunc->type == IPA_JF_ANCESTOR)
310 struct ipcp_lattice *caller_lat;
314 caller_lat = ipcp_get_lattice (info, jfunc->value.ancestor.formal_id);
315 lat->type = caller_lat->type;
316 if (caller_lat->type != IPA_CONST_VALUE)
318 if (TREE_CODE (caller_lat->constant) != ADDR_EXPR)
320 /* This can happen when the constant is a NULL pointer. */
321 lat->type = IPA_BOTTOM;
324 t = TREE_OPERAND (caller_lat->constant, 0);
325 ok = build_ref_for_offset (&t, TREE_TYPE (t),
326 jfunc->value.ancestor.offset,
327 jfunc->value.ancestor.type, false);
329 lat->constant = build_fold_addr_expr (t);
332 lat->type = IPA_BOTTOM;
335 /* True when OLD_LAT and NEW_LAT values are not the same. */
338 ipcp_lattice_changed (struct ipcp_lattice *old_lat,
339 struct ipcp_lattice *new_lat)
341 if (old_lat->type == new_lat->type)
343 if (!ipcp_lat_is_const (old_lat))
345 if (ipcp_lats_are_equal (old_lat, new_lat))
351 /* Print all ipcp_lattices of all functions to F. */
353 ipcp_print_all_lattices (FILE * f)
355 struct cgraph_node *node;
358 fprintf (f, "\nLattice:\n");
359 for (node = cgraph_nodes; node; node = node->next)
361 struct ipa_node_params *info;
365 info = IPA_NODE_REF (node);
366 fprintf (f, " Node: %s:\n", cgraph_node_name (node));
367 count = ipa_get_param_count (info);
368 for (i = 0; i < count; i++)
370 struct ipcp_lattice *lat = ipcp_get_lattice (info, i);
372 fprintf (f, " param [%d]: ", i);
373 if (lat->type == IPA_CONST_VALUE)
375 fprintf (f, "type is CONST ");
376 print_generic_expr (f, lat->constant, 0);
379 else if (lat->type == IPA_TOP)
380 fprintf (f, "type is TOP\n");
382 fprintf (f, "type is BOTTOM\n");
387 /* Return true if ipcp algorithms would allow cloning NODE. */
390 ipcp_versionable_function_p (struct cgraph_node *node)
392 tree decl = node->decl;
395 /* There are a number of generic reasons functions cannot be versioned. */
396 if (!tree_versionable_function_p (decl))
399 /* Removing arguments doesn't work if the function takes varargs. */
400 if (DECL_STRUCT_FUNCTION (decl)->stdarg)
403 /* Removing arguments doesn't work if we use __builtin_apply_args. */
404 FOR_EACH_BB_FN (bb, DECL_STRUCT_FUNCTION (decl))
406 gimple_stmt_iterator gsi;
407 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
409 const_gimple stmt = gsi_stmt (gsi);
412 if (!is_gimple_call (stmt))
414 t = gimple_call_fndecl (stmt);
417 if (DECL_BUILT_IN_CLASS (t) == BUILT_IN_NORMAL
418 && DECL_FUNCTION_CODE (t) == BUILT_IN_APPLY_ARGS)
426 /* Return true if this NODE is viable candidate for cloning. */
428 ipcp_cloning_candidate_p (struct cgraph_node *node)
432 gcov_type direct_call_sum = 0;
433 struct cgraph_edge *e;
435 /* We never clone functions that are not visible from outside.
436 FIXME: in future we should clone such functions when they are called with
437 different constants, but current ipcp implementation is not good on this.
439 if (!node->needed || !node->analyzed)
442 if (cgraph_function_body_availability (node) <= AVAIL_OVERWRITABLE)
445 fprintf (dump_file, "Not considering %s for cloning; body is overwrittable.\n",
446 cgraph_node_name (node));
449 if (!ipcp_versionable_function_p (node))
452 fprintf (dump_file, "Not considering %s for cloning; body is not versionable.\n",
453 cgraph_node_name (node));
456 for (e = node->callers; e; e = e->next_caller)
458 direct_call_sum += e->count;
460 if (cgraph_maybe_hot_edge_p (e))
467 fprintf (dump_file, "Not considering %s for cloning; no direct calls.\n",
468 cgraph_node_name (node));
471 if (node->local.inline_summary.self_size < n_calls)
474 fprintf (dump_file, "Considering %s for cloning; code would shrink.\n",
475 cgraph_node_name (node));
479 if (!flag_ipa_cp_clone)
482 fprintf (dump_file, "Not considering %s for cloning; -fipa-cp-clone disabled.\n",
483 cgraph_node_name (node));
487 if (!optimize_function_for_speed_p (DECL_STRUCT_FUNCTION (node->decl)))
490 fprintf (dump_file, "Not considering %s for cloning; optimizing it for size.\n",
491 cgraph_node_name (node));
495 /* When profile is available and function is hot, propagate into it even if
496 calls seems cold; constant propagation can improve function's speed
500 if (direct_call_sum > node->count * 90 / 100)
503 fprintf (dump_file, "Considering %s for cloning; usually called directly.\n",
504 cgraph_node_name (node));
511 fprintf (dump_file, "Not considering %s for cloning; no hot calls.\n",
512 cgraph_node_name (node));
516 fprintf (dump_file, "Considering %s for cloning.\n",
517 cgraph_node_name (node));
521 /* Initialize ipcp_lattices array. The lattices corresponding to supported
522 types (integers, real types and Fortran constants defined as const_decls)
523 are initialized to IPA_TOP, the rest of them to IPA_BOTTOM. */
525 ipcp_initialize_node_lattices (struct cgraph_node *node)
528 struct ipa_node_params *info = IPA_NODE_REF (node);
529 enum ipa_lattice_type type;
531 if (ipa_is_called_with_var_arguments (info))
533 else if (!node->needed)
535 /* When cloning is allowed, we can assume that externally visible functions
536 are not called. We will compensate this by cloning later. */
537 else if (ipcp_cloning_candidate_p (node))
538 type = IPA_TOP, n_cloning_candidates ++;
542 for (i = 0; i < ipa_get_param_count (info) ; i++)
543 ipcp_get_lattice (info, i)->type = type;
546 /* build INTEGER_CST tree with type TREE_TYPE and value according to LAT.
549 build_const_val (struct ipcp_lattice *lat, tree tree_type)
553 gcc_assert (ipcp_lat_is_const (lat));
556 if (!useless_type_conversion_p (tree_type, TREE_TYPE (val)))
558 if (fold_convertible_p (tree_type, val))
559 return fold_build1 (NOP_EXPR, tree_type, val);
561 return fold_build1 (VIEW_CONVERT_EXPR, tree_type, val);
566 /* Compute the proper scale for NODE. It is the ratio between the number of
567 direct calls (represented on the incoming cgraph_edges) and sum of all
568 invocations of NODE (represented as count in cgraph_node). */
570 ipcp_compute_node_scale (struct cgraph_node *node)
573 struct cgraph_edge *cs;
576 /* Compute sum of all counts of callers. */
577 for (cs = node->callers; cs != NULL; cs = cs->next_caller)
579 if (node->count == 0)
580 ipcp_set_node_scale (node, 0);
582 ipcp_set_node_scale (node, sum * REG_BR_PROB_BASE / node->count);
585 /* Initialization and computation of IPCP data structures. This is the initial
586 intraprocedural analysis of functions, which gathers information to be
587 propagated later on. */
589 ipcp_init_stage (void)
591 struct cgraph_node *node;
592 struct cgraph_edge *cs;
594 for (node = cgraph_nodes; node; node = node->next)
596 ipcp_analyze_node (node);
597 for (node = cgraph_nodes; node; node = node->next)
601 /* building jump functions */
602 for (cs = node->callees; cs; cs = cs->next_callee)
604 if (!cs->callee->analyzed)
606 ipa_count_arguments (cs);
607 if (ipa_get_cs_argument_count (IPA_EDGE_REF (cs))
608 != ipa_get_param_count (IPA_NODE_REF (cs->callee)))
610 /* Handle cases of functions with
611 a variable number of parameters. */
612 ipa_set_called_with_variable_arg (IPA_NODE_REF (cs->callee));
613 if (flag_indirect_inlining)
614 ipa_compute_jump_functions (cs);
617 ipa_compute_jump_functions (cs);
622 /* Return true if there are some formal parameters whose value is IPA_TOP (in
623 the whole compilation unit). Change their values to IPA_BOTTOM, since they
624 most probably get their values from outside of this compilation unit. */
626 ipcp_change_tops_to_bottom (void)
629 struct cgraph_node *node;
633 for (node = cgraph_nodes; node; node = node->next)
635 struct ipa_node_params *info = IPA_NODE_REF (node);
636 count = ipa_get_param_count (info);
637 for (i = 0; i < count; i++)
639 struct ipcp_lattice *lat = ipcp_get_lattice (info, i);
640 if (lat->type == IPA_TOP)
645 fprintf (dump_file, "Forcing param ");
646 print_generic_expr (dump_file, ipa_get_param (info, i), 0);
647 fprintf (dump_file, " of node %s to bottom.\n",
648 cgraph_node_name (node));
650 lat->type = IPA_BOTTOM;
657 /* Interprocedural analysis. The algorithm propagates constants from the
658 caller's parameters to the callee's arguments. */
660 ipcp_propagate_stage (void)
663 struct ipcp_lattice inc_lat = { IPA_BOTTOM, NULL };
664 struct ipcp_lattice new_lat = { IPA_BOTTOM, NULL };
665 struct ipcp_lattice *dest_lat;
666 struct cgraph_edge *cs;
667 struct ipa_jump_func *jump_func;
668 struct ipa_func_list *wl;
671 ipa_check_create_node_params ();
672 ipa_check_create_edge_args ();
674 /* Initialize worklist to contain all functions. */
675 wl = ipa_init_func_list ();
678 struct cgraph_node *node = ipa_pop_func_from_list (&wl);
679 struct ipa_node_params *info = IPA_NODE_REF (node);
681 for (cs = node->callees; cs; cs = cs->next_callee)
683 struct ipa_node_params *callee_info = IPA_NODE_REF (cs->callee);
684 struct ipa_edge_args *args = IPA_EDGE_REF (cs);
686 if (ipa_is_called_with_var_arguments (callee_info))
689 count = ipa_get_cs_argument_count (args);
690 for (i = 0; i < count; i++)
692 jump_func = ipa_get_ith_jump_func (args, i);
693 ipcp_lattice_from_jfunc (info, &inc_lat, jump_func);
694 dest_lat = ipcp_get_lattice (callee_info, i);
695 ipa_lattice_meet (&new_lat, &inc_lat, dest_lat);
696 if (ipcp_lattice_changed (&new_lat, dest_lat))
698 dest_lat->type = new_lat.type;
699 dest_lat->constant = new_lat.constant;
700 ipa_push_func_to_list (&wl, cs->callee);
707 /* Call the constant propagation algorithm and re-call it if necessary
708 (if there are undetermined values left). */
710 ipcp_iterate_stage (void)
712 struct cgraph_node *node;
713 n_cloning_candidates = 0;
716 fprintf (dump_file, "\nIPA iterate stage:\n\n");
717 for (node = cgraph_nodes; node; node = node->next)
719 ipcp_initialize_node_lattices (node);
720 ipcp_compute_node_scale (node);
722 if (dump_file && (dump_flags & TDF_DETAILS))
724 ipcp_print_all_lattices (dump_file);
725 ipcp_function_scale_print (dump_file);
728 ipcp_propagate_stage ();
729 if (ipcp_change_tops_to_bottom ())
730 /* Some lattices have changed from IPA_TOP to IPA_BOTTOM.
731 This change should be propagated. */
733 gcc_assert (n_cloning_candidates);
734 ipcp_propagate_stage ();
738 fprintf (dump_file, "\nIPA lattices after propagation:\n");
739 ipcp_print_all_lattices (dump_file);
740 if (dump_flags & TDF_DETAILS)
741 ipcp_print_profile_data (dump_file);
745 /* Check conditions to forbid constant insertion to function described by
748 ipcp_node_modifiable_p (struct cgraph_node *node)
750 /* Once we will be able to do in-place replacement, we can be more
752 return ipcp_versionable_function_p (node);
755 /* Print count scale data structures. */
757 ipcp_function_scale_print (FILE * f)
759 struct cgraph_node *node;
761 for (node = cgraph_nodes; node; node = node->next)
765 fprintf (f, "printing scale for %s: ", cgraph_node_name (node));
766 fprintf (f, "value is " HOST_WIDE_INT_PRINT_DEC
767 " \n", (HOST_WIDE_INT) ipcp_get_node_scale (node));
771 /* Print counts of all cgraph nodes. */
773 ipcp_print_func_profile_counts (FILE * f)
775 struct cgraph_node *node;
777 for (node = cgraph_nodes; node; node = node->next)
779 fprintf (f, "function %s: ", cgraph_node_name (node));
780 fprintf (f, "count is " HOST_WIDE_INT_PRINT_DEC
781 " \n", (HOST_WIDE_INT) node->count);
785 /* Print counts of all cgraph edges. */
787 ipcp_print_call_profile_counts (FILE * f)
789 struct cgraph_node *node;
790 struct cgraph_edge *cs;
792 for (node = cgraph_nodes; node; node = node->next)
794 for (cs = node->callees; cs; cs = cs->next_callee)
796 fprintf (f, "%s -> %s ", cgraph_node_name (cs->caller),
797 cgraph_node_name (cs->callee));
798 fprintf (f, "count is " HOST_WIDE_INT_PRINT_DEC " \n",
799 (HOST_WIDE_INT) cs->count);
804 /* Print profile info for all functions. */
806 ipcp_print_profile_data (FILE * f)
808 fprintf (f, "\nNODE COUNTS :\n");
809 ipcp_print_func_profile_counts (f);
810 fprintf (f, "\nCS COUNTS stage:\n");
811 ipcp_print_call_profile_counts (f);
814 /* Build and initialize ipa_replace_map struct according to LAT. This struct is
815 processed by versioning, which operates according to the flags set.
816 PARM_TREE is the formal parameter found to be constant. LAT represents the
818 static struct ipa_replace_map *
819 ipcp_create_replace_map (tree parm_tree, struct ipcp_lattice *lat)
821 struct ipa_replace_map *replace_map;
824 replace_map = GGC_NEW (struct ipa_replace_map);
825 const_val = build_const_val (lat, TREE_TYPE (parm_tree));
828 fprintf (dump_file, " replacing param ");
829 print_generic_expr (dump_file, parm_tree, 0);
830 fprintf (dump_file, " with const ");
831 print_generic_expr (dump_file, const_val, 0);
832 fprintf (dump_file, "\n");
834 replace_map->old_tree = parm_tree;
835 replace_map->new_tree = const_val;
836 replace_map->replace_p = true;
837 replace_map->ref_p = false;
842 /* Return true if this callsite should be redirected to the original callee
843 (instead of the cloned one). */
845 ipcp_need_redirect_p (struct cgraph_edge *cs)
847 struct ipa_node_params *orig_callee_info;
849 struct ipa_jump_func *jump_func;
850 struct cgraph_node *node = cs->callee, *orig;
852 if (!n_cloning_candidates)
855 if ((orig = ipcp_get_orig_node (node)) != NULL)
857 if (ipcp_get_orig_node (cs->caller))
860 orig_callee_info = IPA_NODE_REF (node);
861 count = ipa_get_param_count (orig_callee_info);
862 for (i = 0; i < count; i++)
864 struct ipcp_lattice *lat = ipcp_get_lattice (orig_callee_info, i);
865 if (ipcp_lat_is_const (lat))
867 jump_func = ipa_get_ith_jump_func (IPA_EDGE_REF (cs), i);
868 if (jump_func->type != IPA_JF_CONST)
876 /* Fix the callsites and the call graph after function cloning was done. */
878 ipcp_update_callgraph (void)
880 struct cgraph_node *node;
882 for (node = cgraph_nodes; node; node = node->next)
883 if (node->analyzed && ipcp_node_is_clone (node))
885 bitmap args_to_skip = BITMAP_ALLOC (NULL);
886 struct cgraph_node *orig_node = ipcp_get_orig_node (node);
887 struct ipa_node_params *info = IPA_NODE_REF (orig_node);
888 int i, count = ipa_get_param_count (info);
889 struct cgraph_edge *cs, *next;
891 for (i = 0; i < count; i++)
893 struct ipcp_lattice *lat = ipcp_get_lattice (info, i);
894 tree parm_tree = ipa_get_param (info, i);
896 /* We can proactively remove obviously unused arguments. */
897 if (is_gimple_reg (parm_tree)
898 && !gimple_default_def (DECL_STRUCT_FUNCTION (orig_node->decl),
901 bitmap_set_bit (args_to_skip, i);
905 if (lat->type == IPA_CONST_VALUE)
906 bitmap_set_bit (args_to_skip, i);
908 for (cs = node->callers; cs; cs = next)
910 next = cs->next_caller;
911 if (!ipcp_node_is_clone (cs->caller) && ipcp_need_redirect_p (cs))
912 cgraph_redirect_edge_callee (cs, orig_node);
917 /* Update profiling info for versioned functions and the functions they were
920 ipcp_update_profiling (void)
922 struct cgraph_node *node, *orig_node;
923 gcov_type scale, scale_complement;
924 struct cgraph_edge *cs;
926 for (node = cgraph_nodes; node; node = node->next)
928 if (ipcp_node_is_clone (node))
930 orig_node = ipcp_get_orig_node (node);
931 scale = ipcp_get_node_scale (orig_node);
932 node->count = orig_node->count * scale / REG_BR_PROB_BASE;
933 scale_complement = REG_BR_PROB_BASE - scale;
935 orig_node->count * scale_complement / REG_BR_PROB_BASE;
936 for (cs = node->callees; cs; cs = cs->next_callee)
937 cs->count = cs->count * scale / REG_BR_PROB_BASE;
938 for (cs = orig_node->callees; cs; cs = cs->next_callee)
939 cs->count = cs->count * scale_complement / REG_BR_PROB_BASE;
944 /* If NODE was cloned, how much would program grow? */
946 ipcp_estimate_growth (struct cgraph_node *node)
948 struct cgraph_edge *cs;
949 int redirectable_node_callers = 0;
950 int removable_args = 0;
951 bool need_original = node->needed;
952 struct ipa_node_params *info;
956 for (cs = node->callers; cs != NULL; cs = cs->next_caller)
957 if (cs->caller == node || !ipcp_need_redirect_p (cs))
958 redirectable_node_callers++;
960 need_original = true;
962 /* If we will be able to fully replace orignal node, we never increase
967 info = IPA_NODE_REF (node);
968 count = ipa_get_param_count (info);
969 for (i = 0; i < count; i++)
971 struct ipcp_lattice *lat = ipcp_get_lattice (info, i);
972 tree parm_tree = ipa_get_param (info, i);
974 /* We can proactively remove obviously unused arguments. */
975 if (is_gimple_reg (parm_tree)
976 && !gimple_default_def (DECL_STRUCT_FUNCTION (node->decl),
980 if (lat->type == IPA_CONST_VALUE)
984 /* We make just very simple estimate of savings for removal of operand from
985 call site. Precise cost is dificult to get, as our size metric counts
986 constants and moves as free. Generally we are looking for cases that
987 small function is called very many times. */
988 growth = node->local.inline_summary.self_size
989 - removable_args * redirectable_node_callers;
996 /* Estimate cost of cloning NODE. */
998 ipcp_estimate_cloning_cost (struct cgraph_node *node)
1001 gcov_type count_sum = 1;
1002 struct cgraph_edge *e;
1005 cost = ipcp_estimate_growth (node) * 1000;
1009 fprintf (dump_file, "Versioning of %s will save code size\n",
1010 cgraph_node_name (node));
1014 for (e = node->callers; e; e = e->next_caller)
1015 if (!bitmap_bit_p (dead_nodes, e->caller->uid)
1016 && !ipcp_need_redirect_p (e))
1018 count_sum += e->count;
1019 freq_sum += e->frequency + 1;
1023 cost /= count_sum * 1000 / max_count + 1;
1025 cost /= freq_sum * 1000 / REG_BR_PROB_BASE + 1;
1027 fprintf (dump_file, "Cost of versioning %s is %i, (size: %i, freq: %i)\n",
1028 cgraph_node_name (node), cost, node->local.inline_summary.self_size,
1033 /* Return number of live constant parameters. */
1035 ipcp_const_param_count (struct cgraph_node *node)
1037 int const_param = 0;
1038 struct ipa_node_params *info = IPA_NODE_REF (node);
1039 int count = ipa_get_param_count (info);
1042 for (i = 0; i < count; i++)
1044 struct ipcp_lattice *lat = ipcp_get_lattice (info, i);
1045 tree parm_tree = ipa_get_param (info, i);
1046 if (ipcp_lat_is_insertable (lat)
1047 /* Do not count obviously unused arguments. */
1048 && (!is_gimple_reg (parm_tree)
1049 || gimple_default_def (DECL_STRUCT_FUNCTION (node->decl),
1056 /* Propagate the constant parameters found by ipcp_iterate_stage()
1057 to the function's code. */
1059 ipcp_insert_stage (void)
1061 struct cgraph_node *node, *node1 = NULL;
1063 VEC (cgraph_edge_p, heap) * redirect_callers;
1064 VEC (ipa_replace_map_p,gc)* replace_trees;
1065 int node_callers, count;
1067 struct ipa_replace_map *replace_param;
1069 long overall_size = 0, new_size = 0;
1072 ipa_check_create_node_params ();
1073 ipa_check_create_edge_args ();
1075 fprintf (dump_file, "\nIPA insert stage:\n\n");
1077 dead_nodes = BITMAP_ALLOC (NULL);
1079 for (node = cgraph_nodes; node; node = node->next)
1082 if (node->count > max_count)
1083 max_count = node->count;
1084 overall_size += node->local.inline_summary.self_size;
1087 max_new_size = overall_size;
1088 if (max_new_size < PARAM_VALUE (PARAM_LARGE_UNIT_INSNS))
1089 max_new_size = PARAM_VALUE (PARAM_LARGE_UNIT_INSNS);
1090 max_new_size = max_new_size * PARAM_VALUE (PARAM_IPCP_UNIT_GROWTH) / 100 + 1;
1092 /* First collect all functions we proved to have constant arguments to heap. */
1093 heap = fibheap_new ();
1094 for (node = cgraph_nodes; node; node = node->next)
1096 struct ipa_node_params *info;
1097 /* Propagation of the constant is forbidden in certain conditions. */
1098 if (!node->analyzed || !ipcp_node_modifiable_p (node))
1100 info = IPA_NODE_REF (node);
1101 if (ipa_is_called_with_var_arguments (info))
1103 if (ipcp_const_param_count (node))
1104 node->aux = fibheap_insert (heap, ipcp_estimate_cloning_cost (node), node);
1107 /* Now clone in priority order until code size growth limits are met or
1109 while (!fibheap_empty (heap))
1111 struct ipa_node_params *info;
1113 bitmap args_to_skip;
1114 struct cgraph_edge *cs;
1116 node = (struct cgraph_node *)fibheap_extract_min (heap);
1119 fprintf (dump_file, "considering function %s\n",
1120 cgraph_node_name (node));
1122 growth = ipcp_estimate_growth (node);
1124 if (new_size + growth > max_new_size)
1127 && optimize_function_for_size_p (DECL_STRUCT_FUNCTION (node->decl)))
1130 fprintf (dump_file, "Not versioning, cold code would grow");
1136 /* Look if original function becomes dead after clonning. */
1137 for (cs = node->callers; cs != NULL; cs = cs->next_caller)
1138 if (cs->caller == node || ipcp_need_redirect_p (cs))
1140 if (!cs && !node->needed)
1141 bitmap_set_bit (dead_nodes, node->uid);
1143 info = IPA_NODE_REF (node);
1144 count = ipa_get_param_count (info);
1146 replace_trees = VEC_alloc (ipa_replace_map_p, gc, 1);
1147 args_to_skip = BITMAP_GGC_ALLOC ();
1148 for (i = 0; i < count; i++)
1150 struct ipcp_lattice *lat = ipcp_get_lattice (info, i);
1151 parm_tree = ipa_get_param (info, i);
1153 /* We can proactively remove obviously unused arguments. */
1154 if (is_gimple_reg (parm_tree)
1155 && !gimple_default_def (DECL_STRUCT_FUNCTION (node->decl),
1158 bitmap_set_bit (args_to_skip, i);
1162 if (lat->type == IPA_CONST_VALUE)
1165 ipcp_create_replace_map (parm_tree, lat);
1166 VEC_safe_push (ipa_replace_map_p, gc, replace_trees, replace_param);
1167 bitmap_set_bit (args_to_skip, i);
1171 /* Compute how many callers node has. */
1173 for (cs = node->callers; cs != NULL; cs = cs->next_caller)
1175 redirect_callers = VEC_alloc (cgraph_edge_p, heap, node_callers);
1176 for (cs = node->callers; cs != NULL; cs = cs->next_caller)
1177 VEC_quick_push (cgraph_edge_p, redirect_callers, cs);
1179 /* Redirecting all the callers of the node to the
1180 new versioned node. */
1182 cgraph_create_virtual_clone (node, redirect_callers, replace_trees,
1184 args_to_skip = NULL;
1185 VEC_free (cgraph_edge_p, heap, redirect_callers);
1186 replace_trees = NULL;
1191 fprintf (dump_file, "versioned function %s with growth %i, overall %i\n",
1192 cgraph_node_name (node), (int)growth, (int)new_size);
1193 ipcp_init_cloned_node (node, node1);
1195 /* TODO: We can use indirect inlning info to produce new calls. */
1198 dump_function_to_file (node1->decl, dump_file, dump_flags);
1200 for (cs = node->callees; cs; cs = cs->next_callee)
1201 if (cs->callee->aux)
1203 fibheap_delete_node (heap, (fibnode_t) cs->callee->aux);
1204 cs->callee->aux = fibheap_insert (heap,
1205 ipcp_estimate_cloning_cost (cs->callee),
1210 while (!fibheap_empty (heap))
1213 fprintf (dump_file, "skipping function %s\n",
1214 cgraph_node_name (node));
1215 node = (struct cgraph_node *) fibheap_extract_min (heap);
1218 fibheap_delete (heap);
1219 BITMAP_FREE (dead_nodes);
1220 ipcp_update_callgraph ();
1221 ipcp_update_profiling ();
1224 /* The IPCP driver. */
1228 cgraph_remove_unreachable_nodes (true,dump_file);
1231 fprintf (dump_file, "\nIPA structures before propagation:\n");
1232 if (dump_flags & TDF_DETAILS)
1233 ipa_print_all_params (dump_file);
1234 ipa_print_all_jump_functions (dump_file);
1236 /* 2. Do the interprocedural propagation. */
1237 ipcp_iterate_stage ();
1238 /* 3. Insert the constants found to the functions. */
1239 ipcp_insert_stage ();
1240 if (dump_file && (dump_flags & TDF_DETAILS))
1242 fprintf (dump_file, "\nProfiling info after insert stage:\n");
1243 ipcp_print_profile_data (dump_file);
1245 /* Free all IPCP structures. */
1246 free_all_ipa_structures_after_ipa_cp ();
1248 fprintf (dump_file, "\nIPA constant propagation end\n");
1252 /* Note function body size. */
1254 ipcp_generate_summary (void)
1257 fprintf (dump_file, "\nIPA constant propagation start:\n");
1258 ipa_check_create_node_params ();
1259 ipa_check_create_edge_args ();
1260 ipa_register_cgraph_hooks ();
1261 /* 1. Call the init stage to initialize
1262 the ipa_node_params and ipa_edge_args structures. */
1266 /* Gate for IPCP optimization. */
1268 cgraph_gate_cp (void)
1273 struct ipa_opt_pass_d pass_ipa_cp =
1278 cgraph_gate_cp, /* gate */
1279 ipcp_driver, /* execute */
1282 0, /* static_pass_number */
1283 TV_IPA_CONSTANT_PROP, /* tv_id */
1284 0, /* properties_required */
1285 0, /* properties_provided */
1286 0, /* properties_destroyed */
1287 0, /* todo_flags_start */
1288 TODO_dump_cgraph | TODO_dump_func |
1289 TODO_remove_functions /* todo_flags_finish */
1291 ipcp_generate_summary, /* generate_summary */
1292 NULL, /* write_summary */
1293 NULL, /* read_summary */
1294 NULL, /* function_read_summary */
1296 NULL, /* function_transform */
1297 NULL, /* variable_transform */