1 /* Interprocedural constant propagation
2 Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010
3 Free Software Foundation, Inc.
4 Contributed by Razya Ladelsky <RAZYA@il.ibm.com>
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
22 /* Interprocedural constant propagation. The aim of interprocedural constant
23 propagation (IPCP) is to find which function's argument has the same
24 constant value in each invocation throughout the whole program. For example,
25 consider the following program:
29 printf ("value is %d",y);
49 The IPCP algorithm will find that g's formal argument y is always called
52 The algorithm used is based on "Interprocedural Constant Propagation", by
53 Challahan David, Keith D Cooper, Ken Kennedy, Linda Torczon, Comp86, pg
56 The optimization is divided into three stages:
58 First stage - intraprocedural analysis
59 =======================================
60 This phase computes jump_function and modification flags.
62 A jump function for a callsite represents the values passed as an actual
63 arguments of a given callsite. There are three types of values:
64 Pass through - the caller's formal parameter is passed as an actual argument.
65 Constant - a constant is passed as an actual argument.
66 Unknown - neither of the above.
68 The jump function info, ipa_jump_func, is stored in ipa_edge_args
69 structure (defined in ipa_prop.h and pointed to by cgraph_node->aux)
70 modified_flags are defined in ipa_node_params structure
71 (defined in ipa_prop.h and pointed to by cgraph_edge->aux).
73 -ipcp_init_stage() is the first stage driver.
75 Second stage - interprocedural analysis
76 ========================================
77 This phase does the interprocedural constant propagation.
78 It computes lattices for all formal parameters in the program
79 and their value that may be:
81 BOTTOM - non constant.
82 CONSTANT - constant value.
84 Lattice describing a formal parameter p will have a constant value if all
85 callsites invoking this function have the same constant value passed to p.
87 The lattices are stored in ipcp_lattice which is itself in ipa_node_params
88 structure (defined in ipa_prop.h and pointed to by cgraph_edge->aux).
90 -ipcp_iterate_stage() is the second stage driver.
92 Third phase - transformation of function code
93 ============================================
94 Propagates the constant-valued formals into the function.
95 For each function whose parameters are constants, we create its clone.
97 Then we process the clone in two ways:
98 1. We insert an assignment statement 'parameter = const' at the beginning
99 of the cloned function.
100 2. For read-only parameters that do not live in memory, we replace all their
101 uses with the constant.
103 We also need to modify some callsites to call the cloned functions instead
104 of the original ones. For a callsite passing an argument found to be a
105 constant by IPCP, there are two different cases to handle:
106 1. A constant is passed as an argument. In this case the callsite in the
107 should be redirected to call the cloned callee.
108 2. A parameter (of the caller) passed as an argument (pass through
109 argument). In such cases both the caller and the callee have clones and
110 only the callsite in the cloned caller is redirected to call to the
113 This update is done in two steps: First all cloned functions are created
114 during a traversal of the call graph, during which all callsites are
115 redirected to call the cloned function. Then the callsites are traversed
116 and many calls redirected back to fit the description above.
118 -ipcp_insert_stage() is the third phase driver.
124 #include "coretypes.h"
128 #include "ipa-prop.h"
129 #include "tree-flow.h"
130 #include "tree-pass.h"
133 #include "diagnostic.h"
134 #include "tree-dump.h"
135 #include "tree-inline.h"
139 /* Number of functions identified as candidates for cloning. When not cloning
140 we can simplify iterate stage not forcing it to go through the decision
141 on what is profitable and what not. */
142 static int n_cloning_candidates;
144 /* Maximal count found in program. */
145 static gcov_type max_count;
147 /* Cgraph nodes that has been completely replaced by cloning during iterate
148 * stage and will be removed after ipcp is finished. */
149 static bitmap dead_nodes;
151 static void ipcp_print_profile_data (FILE *);
152 static void ipcp_function_scale_print (FILE *);
154 /* Get the original node field of ipa_node_params associated with node NODE. */
155 static inline struct cgraph_node *
156 ipcp_get_orig_node (struct cgraph_node *node)
158 return IPA_NODE_REF (node)->ipcp_orig_node;
161 /* Return true if NODE describes a cloned/versioned function. */
163 ipcp_node_is_clone (struct cgraph_node *node)
165 return (ipcp_get_orig_node (node) != NULL);
168 /* Create ipa_node_params and its data structures for NEW_NODE. Set ORIG_NODE
169 as the ipcp_orig_node field in ipa_node_params. */
171 ipcp_init_cloned_node (struct cgraph_node *orig_node,
172 struct cgraph_node *new_node)
174 ipa_check_create_node_params ();
175 ipa_initialize_node_params (new_node);
176 IPA_NODE_REF (new_node)->ipcp_orig_node = orig_node;
179 /* Perform intraprocedrual analysis needed for ipcp. */
181 ipcp_analyze_node (struct cgraph_node *node)
183 /* Unreachable nodes should have been eliminated before ipcp. */
184 gcc_assert (node->needed || node->reachable);
186 node->local.versionable = tree_versionable_function_p (node->decl);
187 ipa_initialize_node_params (node);
188 ipa_detect_param_modifications (node);
191 /* Return scale for NODE. */
192 static inline gcov_type
193 ipcp_get_node_scale (struct cgraph_node *node)
195 return IPA_NODE_REF (node)->count_scale;
198 /* Set COUNT as scale for NODE. */
200 ipcp_set_node_scale (struct cgraph_node *node, gcov_type count)
202 IPA_NODE_REF (node)->count_scale = count;
205 /* Return whether LAT is a constant lattice. */
207 ipcp_lat_is_const (struct ipcp_lattice *lat)
209 if (lat->type == IPA_CONST_VALUE)
215 /* Return whether LAT is a constant lattice that ipa-cp can actually insert
216 into the code (i.e. constants excluding member pointers and pointers). */
218 ipcp_lat_is_insertable (struct ipcp_lattice *lat)
220 return lat->type == IPA_CONST_VALUE;
223 /* Return true if LAT1 and LAT2 are equal. */
225 ipcp_lats_are_equal (struct ipcp_lattice *lat1, struct ipcp_lattice *lat2)
227 gcc_assert (ipcp_lat_is_const (lat1) && ipcp_lat_is_const (lat2));
228 if (lat1->type != lat2->type)
231 if (TREE_CODE (lat1->constant) == ADDR_EXPR
232 && TREE_CODE (lat2->constant) == ADDR_EXPR
233 && TREE_CODE (TREE_OPERAND (lat1->constant, 0)) == CONST_DECL
234 && TREE_CODE (TREE_OPERAND (lat2->constant, 0)) == CONST_DECL)
235 return operand_equal_p (DECL_INITIAL (TREE_OPERAND (lat1->constant, 0)),
236 DECL_INITIAL (TREE_OPERAND (lat2->constant, 0)), 0);
238 return operand_equal_p (lat1->constant, lat2->constant, 0);
241 /* Compute Meet arithmetics:
242 Meet (IPA_BOTTOM, x) = IPA_BOTTOM
244 Meet (const_a,const_b) = IPA_BOTTOM, if const_a != const_b.
245 MEET (const_a,const_b) = const_a, if const_a == const_b.*/
247 ipa_lattice_meet (struct ipcp_lattice *res, struct ipcp_lattice *lat1,
248 struct ipcp_lattice *lat2)
250 if (lat1->type == IPA_BOTTOM || lat2->type == IPA_BOTTOM)
252 res->type = IPA_BOTTOM;
255 if (lat1->type == IPA_TOP)
257 res->type = lat2->type;
258 res->constant = lat2->constant;
261 if (lat2->type == IPA_TOP)
263 res->type = lat1->type;
264 res->constant = lat1->constant;
267 if (!ipcp_lats_are_equal (lat1, lat2))
269 res->type = IPA_BOTTOM;
272 res->type = lat1->type;
273 res->constant = lat1->constant;
276 /* Return the lattice corresponding to the Ith formal parameter of the function
277 described by INFO. */
278 static inline struct ipcp_lattice *
279 ipcp_get_lattice (struct ipa_node_params *info, int i)
281 return &(info->params[i].ipcp_lattice);
284 /* Given the jump function JFUNC, compute the lattice LAT that describes the
285 value coming down the callsite. INFO describes the caller node so that
286 pass-through jump functions can be evaluated. */
288 ipcp_lattice_from_jfunc (struct ipa_node_params *info, struct ipcp_lattice *lat,
289 struct ipa_jump_func *jfunc)
291 if (jfunc->type == IPA_JF_CONST)
293 lat->type = IPA_CONST_VALUE;
294 lat->constant = jfunc->value.constant;
296 else if (jfunc->type == IPA_JF_PASS_THROUGH)
298 struct ipcp_lattice *caller_lat;
301 caller_lat = ipcp_get_lattice (info, jfunc->value.pass_through.formal_id);
302 lat->type = caller_lat->type;
303 if (caller_lat->type != IPA_CONST_VALUE)
305 cst = caller_lat->constant;
307 if (jfunc->value.pass_through.operation != NOP_EXPR)
310 if (TREE_CODE_CLASS (jfunc->value.pass_through.operation)
312 restype = boolean_type_node;
314 restype = TREE_TYPE (cst);
315 cst = fold_binary (jfunc->value.pass_through.operation,
316 restype, cst, jfunc->value.pass_through.operand);
318 if (!cst || !is_gimple_ip_invariant (cst))
319 lat->type = IPA_BOTTOM;
322 else if (jfunc->type == IPA_JF_ANCESTOR)
324 struct ipcp_lattice *caller_lat;
328 caller_lat = ipcp_get_lattice (info, jfunc->value.ancestor.formal_id);
329 lat->type = caller_lat->type;
330 if (caller_lat->type != IPA_CONST_VALUE)
332 if (TREE_CODE (caller_lat->constant) != ADDR_EXPR)
334 /* This can happen when the constant is a NULL pointer. */
335 lat->type = IPA_BOTTOM;
338 t = TREE_OPERAND (caller_lat->constant, 0);
339 ok = build_ref_for_offset (&t, TREE_TYPE (t),
340 jfunc->value.ancestor.offset,
341 jfunc->value.ancestor.type, false);
344 lat->type = IPA_BOTTOM;
345 lat->constant = NULL_TREE;
348 lat->constant = build_fold_addr_expr (t);
351 lat->type = IPA_BOTTOM;
354 /* True when OLD_LAT and NEW_LAT values are not the same. */
357 ipcp_lattice_changed (struct ipcp_lattice *old_lat,
358 struct ipcp_lattice *new_lat)
360 if (old_lat->type == new_lat->type)
362 if (!ipcp_lat_is_const (old_lat))
364 if (ipcp_lats_are_equal (old_lat, new_lat))
370 /* Print all ipcp_lattices of all functions to F. */
372 ipcp_print_all_lattices (FILE * f)
374 struct cgraph_node *node;
377 fprintf (f, "\nLattice:\n");
378 for (node = cgraph_nodes; node; node = node->next)
380 struct ipa_node_params *info;
384 info = IPA_NODE_REF (node);
385 fprintf (f, " Node: %s:\n", cgraph_node_name (node));
386 count = ipa_get_param_count (info);
387 for (i = 0; i < count; i++)
389 struct ipcp_lattice *lat = ipcp_get_lattice (info, i);
391 fprintf (f, " param [%d]: ", i);
392 if (lat->type == IPA_CONST_VALUE)
394 tree cst = lat->constant;
395 fprintf (f, "type is CONST ");
396 print_generic_expr (f, cst, 0);
397 if (TREE_CODE (cst) == ADDR_EXPR
398 && TREE_CODE (TREE_OPERAND (cst, 0)) == CONST_DECL)
401 print_generic_expr (f, DECL_INITIAL (TREE_OPERAND (cst, 0)),
406 else if (lat->type == IPA_TOP)
407 fprintf (f, "type is TOP\n");
409 fprintf (f, "type is BOTTOM\n");
414 /* Return true if ipcp algorithms would allow cloning NODE. */
417 ipcp_versionable_function_p (struct cgraph_node *node)
419 tree decl = node->decl;
422 /* There are a number of generic reasons functions cannot be versioned. */
423 if (!node->local.versionable)
426 /* Removing arguments doesn't work if the function takes varargs. */
427 if (DECL_STRUCT_FUNCTION (decl)->stdarg)
430 /* Removing arguments doesn't work if we use __builtin_apply_args. */
431 FOR_EACH_BB_FN (bb, DECL_STRUCT_FUNCTION (decl))
433 gimple_stmt_iterator gsi;
434 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
436 const_gimple stmt = gsi_stmt (gsi);
439 if (!is_gimple_call (stmt))
441 t = gimple_call_fndecl (stmt);
444 if (DECL_BUILT_IN_CLASS (t) == BUILT_IN_NORMAL
445 && DECL_FUNCTION_CODE (t) == BUILT_IN_APPLY_ARGS)
453 /* Return true if this NODE is viable candidate for cloning. */
455 ipcp_cloning_candidate_p (struct cgraph_node *node)
459 gcov_type direct_call_sum = 0;
460 struct cgraph_edge *e;
462 /* We never clone functions that are not visible from outside.
463 FIXME: in future we should clone such functions when they are called with
464 different constants, but current ipcp implementation is not good on this.
466 if (cgraph_only_called_directly_p (node) || !node->analyzed)
469 if (cgraph_function_body_availability (node) <= AVAIL_OVERWRITABLE)
472 fprintf (dump_file, "Not considering %s for cloning; body is overwrittable.\n",
473 cgraph_node_name (node));
476 if (!ipcp_versionable_function_p (node))
479 fprintf (dump_file, "Not considering %s for cloning; body is not versionable.\n",
480 cgraph_node_name (node));
483 for (e = node->callers; e; e = e->next_caller)
485 direct_call_sum += e->count;
487 if (cgraph_maybe_hot_edge_p (e))
494 fprintf (dump_file, "Not considering %s for cloning; no direct calls.\n",
495 cgraph_node_name (node));
498 if (node->local.inline_summary.self_size < n_calls)
501 fprintf (dump_file, "Considering %s for cloning; code would shrink.\n",
502 cgraph_node_name (node));
506 if (!flag_ipa_cp_clone)
509 fprintf (dump_file, "Not considering %s for cloning; -fipa-cp-clone disabled.\n",
510 cgraph_node_name (node));
514 if (!optimize_function_for_speed_p (DECL_STRUCT_FUNCTION (node->decl)))
517 fprintf (dump_file, "Not considering %s for cloning; optimizing it for size.\n",
518 cgraph_node_name (node));
522 /* When profile is available and function is hot, propagate into it even if
523 calls seems cold; constant propagation can improve function's speed
527 if (direct_call_sum > node->count * 90 / 100)
530 fprintf (dump_file, "Considering %s for cloning; usually called directly.\n",
531 cgraph_node_name (node));
538 fprintf (dump_file, "Not considering %s for cloning; no hot calls.\n",
539 cgraph_node_name (node));
543 fprintf (dump_file, "Considering %s for cloning.\n",
544 cgraph_node_name (node));
548 /* Initialize ipcp_lattices array. The lattices corresponding to supported
549 types (integers, real types and Fortran constants defined as const_decls)
550 are initialized to IPA_TOP, the rest of them to IPA_BOTTOM. */
552 ipcp_initialize_node_lattices (struct cgraph_node *node)
555 struct ipa_node_params *info = IPA_NODE_REF (node);
556 enum ipa_lattice_type type;
558 if (ipa_is_called_with_var_arguments (info))
560 else if (cgraph_only_called_directly_p (node))
562 /* When cloning is allowed, we can assume that externally visible functions
563 are not called. We will compensate this by cloning later. */
564 else if (ipcp_cloning_candidate_p (node))
565 type = IPA_TOP, n_cloning_candidates ++;
569 for (i = 0; i < ipa_get_param_count (info) ; i++)
570 ipcp_get_lattice (info, i)->type = type;
573 /* build INTEGER_CST tree with type TREE_TYPE and value according to LAT.
576 build_const_val (struct ipcp_lattice *lat, tree tree_type)
580 gcc_assert (ipcp_lat_is_const (lat));
583 if (!useless_type_conversion_p (tree_type, TREE_TYPE (val)))
585 if (fold_convertible_p (tree_type, val))
586 return fold_build1 (NOP_EXPR, tree_type, val);
588 return fold_build1 (VIEW_CONVERT_EXPR, tree_type, val);
593 /* Compute the proper scale for NODE. It is the ratio between the number of
594 direct calls (represented on the incoming cgraph_edges) and sum of all
595 invocations of NODE (represented as count in cgraph_node).
597 FIXME: This code is wrong. Since the callers can be also clones and
598 the clones are not scaled yet, the sums gets unrealistically high.
599 To properly compute the counts, we would need to do propagation across
600 callgraph (as external call to A might imply call to non-clonned B
601 if A's clone calls clonned B). */
603 ipcp_compute_node_scale (struct cgraph_node *node)
606 struct cgraph_edge *cs;
609 /* Compute sum of all counts of callers. */
610 for (cs = node->callers; cs != NULL; cs = cs->next_caller)
612 /* Work around the unrealistically high sum problem. We just don't want
613 the non-cloned body to have negative or very low frequency. Since
614 majority of execution time will be spent in clones anyway, this should
615 give good enough profile. */
616 if (sum > node->count * 9 / 10)
617 sum = node->count * 9 / 10;
618 if (node->count == 0)
619 ipcp_set_node_scale (node, 0);
621 ipcp_set_node_scale (node, sum * REG_BR_PROB_BASE / node->count);
624 /* Initialization and computation of IPCP data structures. This is the initial
625 intraprocedural analysis of functions, which gathers information to be
626 propagated later on. */
628 ipcp_init_stage (void)
630 struct cgraph_node *node;
631 struct cgraph_edge *cs;
633 for (node = cgraph_nodes; node; node = node->next)
635 ipcp_analyze_node (node);
636 for (node = cgraph_nodes; node; node = node->next)
640 /* building jump functions */
641 for (cs = node->callees; cs; cs = cs->next_callee)
643 /* We do not need to bother analyzing calls to unknown
644 functions unless they may become known during lto/whopr. */
645 if (!cs->callee->analyzed && !flag_lto && !flag_whopr)
647 ipa_count_arguments (cs);
648 if (ipa_get_cs_argument_count (IPA_EDGE_REF (cs))
649 != ipa_get_param_count (IPA_NODE_REF (cs->callee)))
650 ipa_set_called_with_variable_arg (IPA_NODE_REF (cs->callee));
651 ipa_compute_jump_functions (cs);
656 /* Return true if there are some formal parameters whose value is IPA_TOP (in
657 the whole compilation unit). Change their values to IPA_BOTTOM, since they
658 most probably get their values from outside of this compilation unit. */
660 ipcp_change_tops_to_bottom (void)
663 struct cgraph_node *node;
667 for (node = cgraph_nodes; node; node = node->next)
669 struct ipa_node_params *info = IPA_NODE_REF (node);
670 count = ipa_get_param_count (info);
671 for (i = 0; i < count; i++)
673 struct ipcp_lattice *lat = ipcp_get_lattice (info, i);
674 if (lat->type == IPA_TOP)
679 fprintf (dump_file, "Forcing param ");
680 print_generic_expr (dump_file, ipa_get_param (info, i), 0);
681 fprintf (dump_file, " of node %s to bottom.\n",
682 cgraph_node_name (node));
684 lat->type = IPA_BOTTOM;
691 /* Interprocedural analysis. The algorithm propagates constants from the
692 caller's parameters to the callee's arguments. */
694 ipcp_propagate_stage (void)
697 struct ipcp_lattice inc_lat = { IPA_BOTTOM, NULL };
698 struct ipcp_lattice new_lat = { IPA_BOTTOM, NULL };
699 struct ipcp_lattice *dest_lat;
700 struct cgraph_edge *cs;
701 struct ipa_jump_func *jump_func;
702 struct ipa_func_list *wl;
705 ipa_check_create_node_params ();
706 ipa_check_create_edge_args ();
708 /* Initialize worklist to contain all functions. */
709 wl = ipa_init_func_list ();
712 struct cgraph_node *node = ipa_pop_func_from_list (&wl);
713 struct ipa_node_params *info = IPA_NODE_REF (node);
715 for (cs = node->callees; cs; cs = cs->next_callee)
717 struct ipa_node_params *callee_info = IPA_NODE_REF (cs->callee);
718 struct ipa_edge_args *args = IPA_EDGE_REF (cs);
720 if (ipa_is_called_with_var_arguments (callee_info)
721 || !cs->callee->analyzed
722 || ipa_is_called_with_var_arguments (callee_info))
725 count = ipa_get_cs_argument_count (args);
726 for (i = 0; i < count; i++)
728 jump_func = ipa_get_ith_jump_func (args, i);
729 ipcp_lattice_from_jfunc (info, &inc_lat, jump_func);
730 dest_lat = ipcp_get_lattice (callee_info, i);
731 ipa_lattice_meet (&new_lat, &inc_lat, dest_lat);
732 if (ipcp_lattice_changed (&new_lat, dest_lat))
734 dest_lat->type = new_lat.type;
735 dest_lat->constant = new_lat.constant;
736 ipa_push_func_to_list (&wl, cs->callee);
743 /* Call the constant propagation algorithm and re-call it if necessary
744 (if there are undetermined values left). */
746 ipcp_iterate_stage (void)
748 struct cgraph_node *node;
749 n_cloning_candidates = 0;
752 fprintf (dump_file, "\nIPA iterate stage:\n\n");
755 ipa_update_after_lto_read ();
757 for (node = cgraph_nodes; node; node = node->next)
759 ipcp_initialize_node_lattices (node);
760 ipcp_compute_node_scale (node);
762 if (dump_file && (dump_flags & TDF_DETAILS))
764 ipcp_print_all_lattices (dump_file);
765 ipcp_function_scale_print (dump_file);
768 ipcp_propagate_stage ();
769 if (ipcp_change_tops_to_bottom ())
770 /* Some lattices have changed from IPA_TOP to IPA_BOTTOM.
771 This change should be propagated. */
773 gcc_assert (n_cloning_candidates);
774 ipcp_propagate_stage ();
778 fprintf (dump_file, "\nIPA lattices after propagation:\n");
779 ipcp_print_all_lattices (dump_file);
780 if (dump_flags & TDF_DETAILS)
781 ipcp_print_profile_data (dump_file);
785 /* Check conditions to forbid constant insertion to function described by
788 ipcp_node_modifiable_p (struct cgraph_node *node)
790 /* Once we will be able to do in-place replacement, we can be more
792 return ipcp_versionable_function_p (node);
795 /* Print count scale data structures. */
797 ipcp_function_scale_print (FILE * f)
799 struct cgraph_node *node;
801 for (node = cgraph_nodes; node; node = node->next)
805 fprintf (f, "printing scale for %s: ", cgraph_node_name (node));
806 fprintf (f, "value is " HOST_WIDE_INT_PRINT_DEC
807 " \n", (HOST_WIDE_INT) ipcp_get_node_scale (node));
811 /* Print counts of all cgraph nodes. */
813 ipcp_print_func_profile_counts (FILE * f)
815 struct cgraph_node *node;
817 for (node = cgraph_nodes; node; node = node->next)
819 fprintf (f, "function %s: ", cgraph_node_name (node));
820 fprintf (f, "count is " HOST_WIDE_INT_PRINT_DEC
821 " \n", (HOST_WIDE_INT) node->count);
825 /* Print counts of all cgraph edges. */
827 ipcp_print_call_profile_counts (FILE * f)
829 struct cgraph_node *node;
830 struct cgraph_edge *cs;
832 for (node = cgraph_nodes; node; node = node->next)
834 for (cs = node->callees; cs; cs = cs->next_callee)
836 fprintf (f, "%s -> %s ", cgraph_node_name (cs->caller),
837 cgraph_node_name (cs->callee));
838 fprintf (f, "count is " HOST_WIDE_INT_PRINT_DEC " \n",
839 (HOST_WIDE_INT) cs->count);
844 /* Print profile info for all functions. */
846 ipcp_print_profile_data (FILE * f)
848 fprintf (f, "\nNODE COUNTS :\n");
849 ipcp_print_func_profile_counts (f);
850 fprintf (f, "\nCS COUNTS stage:\n");
851 ipcp_print_call_profile_counts (f);
854 /* Build and initialize ipa_replace_map struct according to LAT. This struct is
855 processed by versioning, which operates according to the flags set.
856 PARM_TREE is the formal parameter found to be constant. LAT represents the
858 static struct ipa_replace_map *
859 ipcp_create_replace_map (tree parm_tree, struct ipcp_lattice *lat)
861 struct ipa_replace_map *replace_map;
864 replace_map = GGC_NEW (struct ipa_replace_map);
865 const_val = build_const_val (lat, TREE_TYPE (parm_tree));
868 fprintf (dump_file, " replacing param ");
869 print_generic_expr (dump_file, parm_tree, 0);
870 fprintf (dump_file, " with const ");
871 print_generic_expr (dump_file, const_val, 0);
872 fprintf (dump_file, "\n");
874 replace_map->old_tree = parm_tree;
875 replace_map->new_tree = const_val;
876 replace_map->replace_p = true;
877 replace_map->ref_p = false;
882 /* Return true if this callsite should be redirected to the original callee
883 (instead of the cloned one). */
885 ipcp_need_redirect_p (struct cgraph_edge *cs)
887 struct ipa_node_params *orig_callee_info;
889 struct ipa_jump_func *jump_func;
890 struct cgraph_node *node = cs->callee, *orig;
892 if (!n_cloning_candidates)
895 if ((orig = ipcp_get_orig_node (node)) != NULL)
897 if (ipcp_get_orig_node (cs->caller))
900 orig_callee_info = IPA_NODE_REF (node);
901 count = ipa_get_param_count (orig_callee_info);
902 for (i = 0; i < count; i++)
904 struct ipcp_lattice *lat = ipcp_get_lattice (orig_callee_info, i);
905 if (ipcp_lat_is_const (lat))
907 jump_func = ipa_get_ith_jump_func (IPA_EDGE_REF (cs), i);
908 if (jump_func->type != IPA_JF_CONST)
916 /* Fix the callsites and the call graph after function cloning was done. */
918 ipcp_update_callgraph (void)
920 struct cgraph_node *node;
922 for (node = cgraph_nodes; node; node = node->next)
923 if (node->analyzed && ipcp_node_is_clone (node))
925 bitmap args_to_skip = BITMAP_ALLOC (NULL);
926 struct cgraph_node *orig_node = ipcp_get_orig_node (node);
927 struct ipa_node_params *info = IPA_NODE_REF (orig_node);
928 int i, count = ipa_get_param_count (info);
929 struct cgraph_edge *cs, *next;
931 for (i = 0; i < count; i++)
933 struct ipcp_lattice *lat = ipcp_get_lattice (info, i);
934 tree parm_tree = ipa_get_param (info, i);
936 /* We can proactively remove obviously unused arguments. */
937 if (is_gimple_reg (parm_tree)
938 && !gimple_default_def (DECL_STRUCT_FUNCTION (orig_node->decl),
941 bitmap_set_bit (args_to_skip, i);
945 if (lat->type == IPA_CONST_VALUE)
946 bitmap_set_bit (args_to_skip, i);
948 for (cs = node->callers; cs; cs = next)
950 next = cs->next_caller;
951 if (!ipcp_node_is_clone (cs->caller) && ipcp_need_redirect_p (cs))
952 cgraph_redirect_edge_callee (cs, orig_node);
957 /* Update profiling info for versioned functions and the functions they were
960 ipcp_update_profiling (void)
962 struct cgraph_node *node, *orig_node;
963 gcov_type scale, scale_complement;
964 struct cgraph_edge *cs;
966 for (node = cgraph_nodes; node; node = node->next)
968 if (ipcp_node_is_clone (node))
970 orig_node = ipcp_get_orig_node (node);
971 scale = ipcp_get_node_scale (orig_node);
972 node->count = orig_node->count * scale / REG_BR_PROB_BASE;
973 scale_complement = REG_BR_PROB_BASE - scale;
975 orig_node->count * scale_complement / REG_BR_PROB_BASE;
976 for (cs = node->callees; cs; cs = cs->next_callee)
977 cs->count = cs->count * scale / REG_BR_PROB_BASE;
978 for (cs = orig_node->callees; cs; cs = cs->next_callee)
979 cs->count = cs->count * scale_complement / REG_BR_PROB_BASE;
984 /* If NODE was cloned, how much would program grow? */
986 ipcp_estimate_growth (struct cgraph_node *node)
988 struct cgraph_edge *cs;
989 int redirectable_node_callers = 0;
990 int removable_args = 0;
991 bool need_original = !cgraph_only_called_directly_p (node);
992 struct ipa_node_params *info;
996 for (cs = node->callers; cs != NULL; cs = cs->next_caller)
997 if (cs->caller == node || !ipcp_need_redirect_p (cs))
998 redirectable_node_callers++;
1000 need_original = true;
1002 /* If we will be able to fully replace orignal node, we never increase
1007 info = IPA_NODE_REF (node);
1008 count = ipa_get_param_count (info);
1009 for (i = 0; i < count; i++)
1011 struct ipcp_lattice *lat = ipcp_get_lattice (info, i);
1012 tree parm_tree = ipa_get_param (info, i);
1014 /* We can proactively remove obviously unused arguments. */
1015 if (is_gimple_reg (parm_tree)
1016 && !gimple_default_def (DECL_STRUCT_FUNCTION (node->decl),
1020 if (lat->type == IPA_CONST_VALUE)
1024 /* We make just very simple estimate of savings for removal of operand from
1025 call site. Precise cost is dificult to get, as our size metric counts
1026 constants and moves as free. Generally we are looking for cases that
1027 small function is called very many times. */
1028 growth = node->local.inline_summary.self_size
1029 - removable_args * redirectable_node_callers;
1036 /* Estimate cost of cloning NODE. */
1038 ipcp_estimate_cloning_cost (struct cgraph_node *node)
1041 gcov_type count_sum = 1;
1042 struct cgraph_edge *e;
1045 cost = ipcp_estimate_growth (node) * 1000;
1049 fprintf (dump_file, "Versioning of %s will save code size\n",
1050 cgraph_node_name (node));
1054 for (e = node->callers; e; e = e->next_caller)
1055 if (!bitmap_bit_p (dead_nodes, e->caller->uid)
1056 && !ipcp_need_redirect_p (e))
1058 count_sum += e->count;
1059 freq_sum += e->frequency + 1;
1063 cost /= count_sum * 1000 / max_count + 1;
1065 cost /= freq_sum * 1000 / REG_BR_PROB_BASE + 1;
1067 fprintf (dump_file, "Cost of versioning %s is %i, (size: %i, freq: %i)\n",
1068 cgraph_node_name (node), cost, node->local.inline_summary.self_size,
1073 /* Return number of live constant parameters. */
1075 ipcp_const_param_count (struct cgraph_node *node)
1077 int const_param = 0;
1078 struct ipa_node_params *info = IPA_NODE_REF (node);
1079 int count = ipa_get_param_count (info);
1082 for (i = 0; i < count; i++)
1084 struct ipcp_lattice *lat = ipcp_get_lattice (info, i);
1085 tree parm_tree = ipa_get_param (info, i);
1086 if (ipcp_lat_is_insertable (lat)
1087 /* Do not count obviously unused arguments. */
1088 && (!is_gimple_reg (parm_tree)
1089 || gimple_default_def (DECL_STRUCT_FUNCTION (node->decl),
1096 /* Propagate the constant parameters found by ipcp_iterate_stage()
1097 to the function's code. */
1099 ipcp_insert_stage (void)
1101 struct cgraph_node *node, *node1 = NULL;
1103 VEC (cgraph_edge_p, heap) * redirect_callers;
1104 VEC (ipa_replace_map_p,gc)* replace_trees;
1105 int node_callers, count;
1107 struct ipa_replace_map *replace_param;
1109 long overall_size = 0, new_size = 0;
1112 ipa_check_create_node_params ();
1113 ipa_check_create_edge_args ();
1115 fprintf (dump_file, "\nIPA insert stage:\n\n");
1117 dead_nodes = BITMAP_ALLOC (NULL);
1119 for (node = cgraph_nodes; node; node = node->next)
1122 if (node->count > max_count)
1123 max_count = node->count;
1124 overall_size += node->local.inline_summary.self_size;
1127 max_new_size = overall_size;
1128 if (max_new_size < PARAM_VALUE (PARAM_LARGE_UNIT_INSNS))
1129 max_new_size = PARAM_VALUE (PARAM_LARGE_UNIT_INSNS);
1130 max_new_size = max_new_size * PARAM_VALUE (PARAM_IPCP_UNIT_GROWTH) / 100 + 1;
1132 /* First collect all functions we proved to have constant arguments to heap. */
1133 heap = fibheap_new ();
1134 for (node = cgraph_nodes; node; node = node->next)
1136 struct ipa_node_params *info;
1137 /* Propagation of the constant is forbidden in certain conditions. */
1138 if (!node->analyzed || !ipcp_node_modifiable_p (node))
1140 info = IPA_NODE_REF (node);
1141 if (ipa_is_called_with_var_arguments (info))
1143 if (ipcp_const_param_count (node))
1144 node->aux = fibheap_insert (heap, ipcp_estimate_cloning_cost (node), node);
1147 /* Now clone in priority order until code size growth limits are met or
1149 while (!fibheap_empty (heap))
1151 struct ipa_node_params *info;
1153 bitmap args_to_skip;
1154 struct cgraph_edge *cs;
1156 node = (struct cgraph_node *)fibheap_extract_min (heap);
1159 fprintf (dump_file, "considering function %s\n",
1160 cgraph_node_name (node));
1162 growth = ipcp_estimate_growth (node);
1164 if (new_size + growth > max_new_size)
1167 && optimize_function_for_size_p (DECL_STRUCT_FUNCTION (node->decl)))
1170 fprintf (dump_file, "Not versioning, cold code would grow");
1176 /* Look if original function becomes dead after clonning. */
1177 for (cs = node->callers; cs != NULL; cs = cs->next_caller)
1178 if (cs->caller == node || ipcp_need_redirect_p (cs))
1180 if (!cs && cgraph_only_called_directly_p (node))
1181 bitmap_set_bit (dead_nodes, node->uid);
1183 info = IPA_NODE_REF (node);
1184 count = ipa_get_param_count (info);
1186 replace_trees = VEC_alloc (ipa_replace_map_p, gc, 1);
1187 args_to_skip = BITMAP_GGC_ALLOC ();
1188 for (i = 0; i < count; i++)
1190 struct ipcp_lattice *lat = ipcp_get_lattice (info, i);
1191 parm_tree = ipa_get_param (info, i);
1193 /* We can proactively remove obviously unused arguments. */
1194 if (is_gimple_reg (parm_tree)
1195 && !gimple_default_def (DECL_STRUCT_FUNCTION (node->decl),
1198 bitmap_set_bit (args_to_skip, i);
1202 if (lat->type == IPA_CONST_VALUE)
1205 ipcp_create_replace_map (parm_tree, lat);
1206 VEC_safe_push (ipa_replace_map_p, gc, replace_trees, replace_param);
1207 bitmap_set_bit (args_to_skip, i);
1211 /* Compute how many callers node has. */
1213 for (cs = node->callers; cs != NULL; cs = cs->next_caller)
1215 redirect_callers = VEC_alloc (cgraph_edge_p, heap, node_callers);
1216 for (cs = node->callers; cs != NULL; cs = cs->next_caller)
1217 VEC_quick_push (cgraph_edge_p, redirect_callers, cs);
1219 /* Redirecting all the callers of the node to the
1220 new versioned node. */
1222 cgraph_create_virtual_clone (node, redirect_callers, replace_trees,
1224 args_to_skip = NULL;
1225 VEC_free (cgraph_edge_p, heap, redirect_callers);
1226 replace_trees = NULL;
1231 fprintf (dump_file, "versioned function %s with growth %i, overall %i\n",
1232 cgraph_node_name (node), (int)growth, (int)new_size);
1233 ipcp_init_cloned_node (node, node1);
1235 /* TODO: We can use indirect inlning info to produce new calls. */
1238 dump_function_to_file (node1->decl, dump_file, dump_flags);
1240 for (cs = node->callees; cs; cs = cs->next_callee)
1241 if (cs->callee->aux)
1243 fibheap_delete_node (heap, (fibnode_t) cs->callee->aux);
1244 cs->callee->aux = fibheap_insert (heap,
1245 ipcp_estimate_cloning_cost (cs->callee),
1250 while (!fibheap_empty (heap))
1253 fprintf (dump_file, "skipping function %s\n",
1254 cgraph_node_name (node));
1255 node = (struct cgraph_node *) fibheap_extract_min (heap);
1258 fibheap_delete (heap);
1259 BITMAP_FREE (dead_nodes);
1260 ipcp_update_callgraph ();
1261 ipcp_update_profiling ();
1264 /* The IPCP driver. */
1268 cgraph_remove_unreachable_nodes (true,dump_file);
1271 fprintf (dump_file, "\nIPA structures before propagation:\n");
1272 if (dump_flags & TDF_DETAILS)
1273 ipa_print_all_params (dump_file);
1274 ipa_print_all_jump_functions (dump_file);
1276 /* 2. Do the interprocedural propagation. */
1277 ipcp_iterate_stage ();
1278 /* 3. Insert the constants found to the functions. */
1279 ipcp_insert_stage ();
1280 if (dump_file && (dump_flags & TDF_DETAILS))
1282 fprintf (dump_file, "\nProfiling info after insert stage:\n");
1283 ipcp_print_profile_data (dump_file);
1285 /* Free all IPCP structures. */
1286 ipa_free_all_structures_after_ipa_cp ();
1288 fprintf (dump_file, "\nIPA constant propagation end\n");
1292 /* Note function body size. */
1294 ipcp_generate_summary (void)
1297 fprintf (dump_file, "\nIPA constant propagation start:\n");
1298 ipa_check_create_node_params ();
1299 ipa_check_create_edge_args ();
1300 ipa_register_cgraph_hooks ();
1301 /* 1. Call the init stage to initialize
1302 the ipa_node_params and ipa_edge_args structures. */
1306 /* Write ipcp summary for nodes in SET. */
1308 ipcp_write_summary (cgraph_node_set set,
1309 varpool_node_set vset ATTRIBUTE_UNUSED)
1311 ipa_prop_write_jump_functions (set);
1314 /* Read ipcp summary. */
1316 ipcp_read_summary (void)
1318 ipa_prop_read_jump_functions ();
1321 /* Gate for IPCP optimization. */
1323 cgraph_gate_cp (void)
1328 struct ipa_opt_pass_d pass_ipa_cp =
1333 cgraph_gate_cp, /* gate */
1334 ipcp_driver, /* execute */
1337 0, /* static_pass_number */
1338 TV_IPA_CONSTANT_PROP, /* tv_id */
1339 0, /* properties_required */
1340 0, /* properties_provided */
1341 0, /* properties_destroyed */
1342 0, /* todo_flags_start */
1343 TODO_dump_cgraph | TODO_dump_func |
1344 TODO_remove_functions | TODO_ggc_collect /* todo_flags_finish */
1346 ipcp_generate_summary, /* generate_summary */
1347 ipcp_write_summary, /* write_summary */
1348 ipcp_read_summary, /* read_summary */
1349 NULL, /* write_optimization_summary */
1350 NULL, /* read_optimization_summary */
1351 NULL, /* stmt_fixup */
1353 NULL, /* function_transform */
1354 NULL, /* variable_transform */