2 * Copyright (C) 1995-2008 University of Karlsruhe. All right reserved.
4 * This file is part of libFirm.
6 * This file may be distributed and/or modified under the terms of the
7 * GNU General Public License version 2 as published by the Free Software
8 * Foundation and appearing in the file LICENSE.GPL included in the
9 * packaging of this file.
11 * Licensees holding valid libFirm Professional Edition licenses may use
12 * this file in accordance with the libFirm Commercial License.
13 * Agreement provided with the Software.
15 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
16 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * @brief Optimization of function calls.
23 * @author Michael Beck
28 #include <adt/raw_bitset.h>
30 #include "funccall_t.h"
33 #include "irgraph_t.h"
37 #include "dbginfo_t.h"
41 #include "iredges_t.h"
42 #include "analyze_irg_args.h"
46 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
49 * The walker environment for updating function calls.
51 typedef struct _env_t {
52 unsigned n_calls_SymConst;
54 ir_node *float_const_call_list; /**< The list of all floating const function calls that will be changed. */
55 ir_node *nonfloat_const_call_list; /**< The list of all non-floating const function calls that will be changed. */
56 ir_node *pure_call_list; /**< The list of all pure function calls that will be changed. */
57 ir_node *nothrow_call_list; /**< The list of all nothrow function calls that will be changed. */
58 ir_node *proj_list; /**< The list of all potential Proj nodes that must be fixed. */
61 /** If non-null, evaluates entities for being a heap alloc. */
62 static check_alloc_entity_func is_alloc_entity = NULL;
64 /** Ready IRG's are marked in the ready set. */
65 static unsigned *ready_set;
67 /** IRG's that are in progress are marked here. */
68 static unsigned *busy_set;
71 * We misuse the mtp_property_inherited flag as temporary here.
72 * The is ok, as we cannot set or get it anyway using the
73 * get_addtional_properties API.
75 #define mtp_temporary mtp_property_inherited
78 * Walker: Collect all calls to const and pure functions
79 * to lists. Collect all Proj(Call) nodes into a Proj list.
81 static void collect_const_and_pure_calls(ir_node *node, void *env) {
85 unsigned and_prop, or_prop, prop;
90 /* set the link to NULL for all non-const/pure calls */
91 set_irn_link(call, NULL);
92 ptr = get_Call_ptr(call);
94 ent = get_Global_entity(ptr);
96 prop = get_entity_additional_properties(ent);
97 if ((prop & (mtp_property_const|mtp_property_pure)) == 0)
99 ++ctx->n_calls_SymConst;
100 } else if (get_opt_closed_world() &&
102 get_irg_callee_info_state(current_ir_graph) == irg_callee_info_consistent) {
103 /* If all possible callees are const functions, we can remove the memory edge. */
104 int i, n_callees = get_Call_n_callees(call);
105 if (n_callees == 0) {
106 /* This is kind of strange: dying code or a Call that will raise an exception
107 when executed as there is no implementation to call. So better not
112 /* note that const function are a subset of pure ones */
113 and_prop = mtp_property_const | mtp_property_pure;
115 for (i = 0; i < n_callees; ++i) {
116 ent = get_Call_callee(call, i);
117 if (ent == unknown_entity) {
118 /* we don't know which entity is called here */
121 prop = get_entity_additional_properties(ent);
124 if (and_prop == mtp_no_property)
127 prop = and_prop | (or_prop & mtp_property_has_loop);
132 /* ok, if we get here we found a call to a const or a pure function */
133 if (prop & mtp_property_pure) {
134 set_irn_link(call, ctx->pure_call_list);
135 ctx->pure_call_list = call;
137 if (prop & mtp_property_has_loop) {
138 set_irn_link(call, ctx->nonfloat_const_call_list);
139 ctx->nonfloat_const_call_list = call;
141 set_irn_link(call, ctx->float_const_call_list);
142 ctx->float_const_call_list = call;
145 } else if (is_Proj(node)) {
147 * Collect all memory and exception Proj's from
150 call = get_Proj_pred(node);
154 /* collect the Proj's in the Proj list */
155 switch (get_Proj_proj(node)) {
156 case pn_Call_M_regular:
157 case pn_Call_X_except:
158 case pn_Call_X_regular:
159 case pn_Call_M_except:
160 set_irn_link(node, ctx->proj_list);
161 ctx->proj_list = node;
167 } /* collect_const_and_pure_calls */
170 * Fix the list of collected Calls.
172 * @param irg the graph that contained calls to pure functions
175 static void fix_const_call_lists(ir_graph *irg, env_t *ctx) {
176 ir_node *call, *next, *mem, *proj;
178 ir_graph *rem = current_ir_graph;
180 current_ir_graph = irg;
182 /* First step: fix all calls by removing their memory input and let
184 * The original memory input is preserved in their link fields. */
185 for (call = ctx->float_const_call_list; call != NULL; call = next) {
186 next = get_irn_link(call);
187 mem = get_Call_mem(call);
189 set_irn_link(call, mem);
190 set_Call_mem(call, get_irg_no_mem(irg));
193 * Unfortunately we cannot simply set the node to 'float'.
194 * There is a reason for that:
196 * - The call might be inside a loop/if that is NOT entered
197 * and calls a endless function. Setting the call to float
198 * would allow to move it out from the loop/if causing this
199 * function be called even if the loop/if is not entered ...
201 * This could be fixed using post-dominators for calls and Pin nodes
202 * but need some more analyzes to ensure that a call that potential
203 * never returns is not executed before some code that generates
204 * observable states...
207 /* finally, this call can float */
208 set_irn_pinned(call, op_pin_state_floats);
209 hook_func_call(irg, call);
212 /* Last step: fix all Proj's */
213 for (proj = ctx->proj_list; proj != NULL; proj = next) {
214 next = get_irn_link(proj);
215 call = get_Proj_pred(proj);
216 mem = get_irn_link(call);
218 /* beware of calls in the pure call list */
219 if (!mem || is_Call(mem))
221 assert(get_irn_mode(mem) == mode_M);
223 switch (get_Proj_proj(proj)) {
224 case pn_Call_M_regular: {
225 /* in dead code there might be cycles where proj == mem */
230 case pn_Call_X_except:
231 case pn_Call_M_except:
233 exchange(proj, get_irg_bad(irg));
235 case pn_Call_X_regular: {
236 ir_node *block = get_nodes_block(call);
238 exchange(proj, new_r_Jmp(block));
246 /* changes were done ... */
247 set_irg_outs_inconsistent(irg);
248 set_irg_loopinfo_state(irg, loopinfo_cf_inconsistent);
251 /* ... including exception edges */
252 set_irg_doms_inconsistent(irg);
254 current_ir_graph = rem;
255 } /* fix_const_call_list */
258 * Walker: Collect all calls to nothrow functions
259 * to lists. Collect all Proj(Call) nodes into a Proj list.
261 static void collect_nothrow_calls(ir_node *node, void *env) {
270 /* set the link to NULL for all non-const/pure calls */
271 set_irn_link(call, NULL);
272 ptr = get_Call_ptr(call);
273 if (is_Global(ptr)) {
274 ent = get_Global_entity(ptr);
276 prop = get_entity_additional_properties(ent);
277 if ((prop & mtp_property_nothrow) == 0)
279 ++ctx->n_calls_SymConst;
280 } else if (get_opt_closed_world() &&
282 get_irg_callee_info_state(current_ir_graph) == irg_callee_info_consistent) {
283 /* If all possible callees are nothrow functions, we can remove the exception edge. */
284 int i, n_callees = get_Call_n_callees(call);
285 if (n_callees == 0) {
286 /* This is kind of strange: dying code or a Call that will raise an exception
287 when executed as there is no implementation to call. So better not
292 /* note that const function are a subset of pure ones */
293 prop = mtp_property_nothrow;
294 for (i = 0; i < n_callees; ++i) {
295 ent = get_Call_callee(call, i);
296 if (ent == unknown_entity) {
297 /* we don't know which entity is called here */
300 prop &= get_entity_additional_properties(ent);
301 if (prop == mtp_no_property)
308 /* ok, if we get here we found a call to a nothrow function */
309 set_irn_link(call, ctx->nothrow_call_list);
310 ctx->nothrow_call_list = call;
311 } else if (is_Proj(node)) {
313 * Collect all memory and exception Proj's from
316 call = get_Proj_pred(node);
320 /* collect the Proj's in the Proj list */
321 switch (get_Proj_proj(node)) {
322 case pn_Call_M_regular:
323 case pn_Call_X_except:
324 case pn_Call_X_regular:
325 case pn_Call_M_except:
326 set_irn_link(node, ctx->proj_list);
327 ctx->proj_list = node;
333 } /* collect_nothrow_calls */
336 * Fix the list of collected nothrow Calls.
338 * @param irg the graph that contained calls to pure functions
339 * @param call_list the list of all call sites of const functions
340 * @param proj_list the list of all memory/exception Proj's of this call sites
342 static void fix_nothrow_call_list(ir_graph *irg, ir_node *call_list, ir_node *proj_list) {
343 ir_node *call, *next, *proj;
345 ir_graph *rem = current_ir_graph;
347 current_ir_graph = irg;
349 /* First step: go through the list of calls and mark them. */
350 for (call = call_list; call; call = next) {
351 next = get_irn_link(call);
353 /* current_ir_graph is in memory anyway, so it's a good marker */
354 set_irn_link(call, ¤t_ir_graph);
355 hook_func_call(irg, call);
358 /* Second step: Remove all exception Proj's */
359 for (proj = proj_list; proj; proj = next) {
360 next = get_irn_link(proj);
361 call = get_Proj_pred(proj);
363 /* handle only marked calls */
364 if (get_irn_link(call) != ¤t_ir_graph)
367 /* kill any exception flow */
368 switch (get_Proj_proj(proj)) {
369 case pn_Call_X_except:
370 case pn_Call_M_except:
372 exchange(proj, get_irg_bad(irg));
374 case pn_Call_X_regular: {
375 ir_node *block = get_nodes_block(call);
377 exchange(proj, new_r_Jmp(block));
385 /* changes were done ... */
386 set_irg_outs_inconsistent(irg);
387 set_irg_loopinfo_state(irg, loopinfo_cf_inconsistent);
390 /* ... including exception edges */
391 set_irg_doms_inconsistent(irg);
393 current_ir_graph = rem;
394 } /* fix_nothrow_call_list */
397 #define SET_IRG_READY(irg) rbitset_set(ready_set, get_irg_idx(irg))
398 #define IS_IRG_READY(irg) rbitset_is_set(ready_set, get_irg_idx(irg))
399 #define SET_IRG_BUSY(irg) rbitset_set(busy_set, get_irg_idx(irg))
400 #define CLEAR_IRG_BUSY(irg) rbitset_clear(busy_set, get_irg_idx(irg))
401 #define IS_IRG_BUSY(irg) rbitset_is_set(busy_set, get_irg_idx(irg))
404 static unsigned check_const_or_pure_function(ir_graph *irg, int top);
405 static unsigned check_nothrow_or_malloc(ir_graph *irg, int top);
408 * Calculate the bigger property of two. Handle the temporary flag right.
410 static unsigned max_property(unsigned a, unsigned b) {
411 unsigned r, t = (a | b) & mtp_temporary;
415 if (a == mtp_no_property || b == mtp_no_property)
416 return mtp_no_property;
422 * Follow the memory chain starting at node and determine
425 * @return mtp_property_const if only calls of const functions are detected
426 * mtp_property_pure if only Loads and const/pure calls detected
427 * mtp_no_property else
429 static unsigned _follow_mem(ir_node *node) {
430 unsigned m, mode = mtp_property_const;
435 if (mode == mtp_no_property)
436 return mtp_no_property;
438 if (irn_visited_else_mark(node))
441 switch (get_irn_opcode(node)) {
443 node = get_Proj_pred(node);
452 /* do a dfs search */
453 for (i = get_irn_arity(node) - 1; i >= 0; --i) {
454 m = _follow_mem(get_irn_n(node, i));
455 mode = max_property(mode, m);
456 if (mode == mtp_no_property)
457 return mtp_no_property;
462 /* Beware volatile Loads are NOT allowed in pure functions. */
463 if (get_Load_volatility(node) == volatility_is_volatile)
464 return mtp_no_property;
465 mode = max_property(mode, mtp_property_pure);
466 node = get_Load_mem(node);
470 /* A call is only tolerable if its either constant or pure. */
471 ptr = get_Call_ptr(node);
472 if (is_SymConst_addr_ent(ptr)) {
473 ir_entity *ent = get_SymConst_entity(ptr);
474 ir_graph *irg = get_entity_irg(ent);
476 if (irg == current_ir_graph) {
477 /* A self-recursive call. The property did not depend on this call. */
478 } else if (irg == NULL) {
479 m = get_entity_additional_properties(ent) & (mtp_property_const|mtp_property_pure);
480 mode = max_property(mode, m);
481 } else if (irg != NULL) {
482 /* we have a graph, analyze it. */
483 m = check_const_or_pure_function(irg, /*top=*/0);
484 mode = max_property(mode, m);
487 return mtp_no_property;
488 node = get_Call_mem(node);
492 return mtp_no_property;
498 * Follow the memory chain starting at node and determine
501 * @return mtp_property_const if only calls of const functions are detected
502 * mtp_property_pure if only Loads and const/pure calls detected
503 * mtp_no_property else
505 static unsigned follow_mem(ir_node *node, unsigned mode) {
508 m = _follow_mem(node);
509 return max_property(mode, m);
513 * Check if a graph represents a const or a pure function.
515 * @param irg the graph to check
516 * @param top if set, this is the top call
518 static unsigned check_const_or_pure_function(ir_graph *irg, int top) {
519 ir_node *end, *endbl;
521 unsigned prop = get_irg_additional_properties(irg);
522 ir_graph *rem = current_ir_graph;
524 if (prop & mtp_property_const) {
525 /* already marked as a const function */
526 return mtp_property_const;
528 if (prop & mtp_property_pure) {
529 /* already marked as a pure function */
530 return mtp_property_pure;
533 if (IS_IRG_READY(irg)) {
534 /* already checked */
535 return mtp_no_property;
537 if (IS_IRG_BUSY(irg)) {
538 /* we are still evaluate this method. Be optimistic,
539 return the best possible so far but mark the result as temporary. */
540 return mtp_temporary | mtp_property_const;
544 end = get_irg_end(irg);
545 endbl = get_nodes_block(end);
546 prop = mtp_property_const;
548 current_ir_graph = irg;
550 ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED);
551 inc_irg_visited(irg);
552 /* mark the initial mem: recursion of follow_mem() stops here */
553 mark_irn_visited(get_irg_initial_mem(irg));
555 /* visit every Return */
556 for (j = get_Block_n_cfgpreds(endbl) - 1; j >= 0; --j) {
557 ir_node *node = get_Block_cfgpred(endbl, j);
558 ir_opcode code = get_irn_opcode(node);
561 /* Bad nodes usually do NOT produce anything, so it's ok */
565 if (code == iro_Return) {
566 mem = get_Return_mem(node);
568 /* Bad nodes usually do NOT produce anything, so it's ok */
572 if (mem != get_irg_initial_mem(irg))
573 prop = max_property(prop, follow_mem(mem, prop));
575 /* Exception found. Cannot be const or pure. */
576 prop = mtp_no_property;
579 if (prop == mtp_no_property)
583 if (prop != mtp_no_property) {
584 /* check, if a keep-alive exists */
585 for (j = get_End_n_keepalives(end) - 1; j >= 0; --j) {
586 ir_node *kept = get_End_keepalive(end, j);
588 if (is_Block(kept)) {
589 prop = mtp_no_property;
593 if (mode_M != get_irn_mode(kept))
596 prop = max_property(prop, follow_mem(kept, prop));
597 if (prop == mtp_no_property)
602 if (prop != mtp_no_property) {
603 if (top || (prop & mtp_temporary) == 0) {
604 /* We use the temporary flag here to mark optimistic result.
605 Set the property only if we are sure that it does NOT base on
606 temporary results OR if we are at top-level. */
607 set_irg_additional_property(irg, prop & ~mtp_temporary);
614 ir_free_resources(irg, IR_RESOURCE_IRN_VISITED);
615 current_ir_graph = rem;
617 } /* check_const_or_pure_function */
620 * Handle calls to const functions.
624 static void handle_const_Calls(env_t *ctx) {
627 ctx->n_calls_SymConst = 0;
628 ctx->n_calls_Sel = 0;
630 /* all calls of const functions can be transformed */
631 for (i = get_irp_n_irgs() - 1; i >= 0; --i) {
632 ir_graph *irg = get_irp_irg(i);
634 ctx->float_const_call_list = NULL;
635 ctx->nonfloat_const_call_list = NULL;
636 ctx->pure_call_list = NULL;
637 ctx->proj_list = NULL;
639 ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK);
640 irg_walk_graph(irg, NULL, collect_const_and_pure_calls, ctx);
642 if (ctx->float_const_call_list != NULL)
643 fix_const_call_lists(irg, ctx);
644 ir_free_resources(irg, IR_RESOURCE_IRN_LINK);
646 } /* handle_const_Calls */
649 * Handle calls to nothrow functions.
653 static void handle_nothrow_Calls(env_t *ctx) {
656 ctx->n_calls_SymConst = 0;
657 ctx->n_calls_Sel = 0;
659 /* all calls of const functions can be transformed */
660 for (i = get_irp_n_irgs() - 1; i >= 0; --i) {
661 ir_graph *irg = get_irp_irg(i);
663 ctx->nothrow_call_list = NULL;
664 ctx->proj_list = NULL;
666 ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK);
667 irg_walk_graph(irg, NULL, collect_nothrow_calls, ctx);
669 if (ctx->nothrow_call_list)
670 fix_nothrow_call_list(irg, ctx->nothrow_call_list, ctx->proj_list);
671 ir_free_resources(irg, IR_RESOURCE_IRN_LINK);
676 * Check, whether a given node represents a return value of
677 * a malloc like function (ie, new heap allocated memory).
679 * @param node the node to check
681 static int is_malloc_call_result(const ir_node *node) {
682 if (is_Alloc(node) && get_Alloc_where(node) == heap_alloc) {
683 /* Firm style high-level allocation */
686 if (is_alloc_entity != NULL && is_Call(node)) {
687 ir_node *ptr = get_Call_ptr(node);
689 if (is_Global(ptr)) {
690 ir_entity *ent = get_Global_entity(ptr);
691 return is_alloc_entity(ent);
695 } /* is_malloc_call_result */
698 * Update a property depending on a call property.
700 static unsigned update_property(unsigned orig_prop, unsigned call_prop) {
701 unsigned t = (orig_prop | call_prop) & mtp_temporary;
702 unsigned r = orig_prop & call_prop;
704 } /** update_property */
707 * Check if a node is stored.
709 static int is_stored(const ir_node *n) {
710 const ir_edge_t *edge;
713 foreach_out_edge(n, edge) {
714 const ir_node *succ = get_edge_src_irn(edge);
716 switch (get_irn_opcode(succ)) {
723 if (get_Store_value(succ) == n)
725 /* ok if its only the address input */
734 ptr = get_Call_ptr(succ);
735 if (is_Global(ptr)) {
736 ir_entity *ent = get_Global_entity(ptr);
739 /* we know the called entity */
740 for (i = get_Call_n_params(succ) - 1; i >= 0; --i) {
741 if (get_Call_param(succ, i) == n) {
742 /* n is the i'th param of the call */
743 if (get_method_param_access(ent, i) & ptr_access_store) {
744 /* n is store in ent */
750 /* unknown call address */
755 /* bad, potential alias */
763 * Check that the return value of an irg is not stored anywhere.
765 * return ~mtp_property_malloc if return values are stored, ~0 else
767 static unsigned check_stored_result(ir_graph *irg) {
768 ir_node *end_blk = get_irg_end_block(irg);
771 int old_edges = edges_assure_kind(irg, EDGE_KIND_NORMAL);
773 for (i = get_Block_n_cfgpreds(end_blk) - 1; i >= 0; --i) {
774 ir_node *pred = get_Block_cfgpred(end_blk, i);
776 if (! is_Return(pred))
778 for (j = get_Return_n_ress(pred) - 1; j >= 0; --j) {
779 const ir_node *irn = get_Return_res(pred, j);
781 if (is_stored(irn)) {
782 /* bad, might create an alias */
783 res = ~mtp_property_malloc;
790 edges_deactivate_kind(irg, EDGE_KIND_NORMAL);
792 } /* check_stored_result */
795 * Check if a graph represents a nothrow or a malloc function.
797 * @param irg the graph to check
798 * @param top if set, this is the top call
800 static unsigned check_nothrow_or_malloc(ir_graph *irg, int top) {
801 ir_node *end_blk = get_irg_end_block(irg);
805 unsigned curr_prop = mtp_property_malloc | mtp_property_nothrow;
807 if (IS_IRG_READY(irg)) {
808 /* already checked */
809 return get_irg_additional_properties(irg);
811 if (IS_IRG_BUSY(irg)) {
812 /* we are still evaluate this method. Be optimistic,
813 return the best possible so far but mark the result as temporary. */
814 return mtp_temporary | mtp_property_malloc | mtp_property_nothrow;
818 ent = get_irg_entity(irg);
819 mtp = get_entity_type(ent);
821 if (get_method_n_ress(mtp) <= 0)
822 curr_prop &= ~mtp_property_malloc;
824 for (i = get_Block_n_cfgpreds(end_blk) - 1; i >= 0; --i) {
825 ir_node *pred = get_Block_cfgpred(end_blk, i);
827 if (is_Return(pred)) {
828 if (curr_prop & mtp_property_malloc) {
829 /* check, if malloc is called here */
830 for (j = get_Return_n_ress(pred) - 1; j >= 0; --j) {
831 ir_node *res = get_Return_res(pred, j);
833 /* skip Confirms and Casts */
834 res = skip_HighLevel_ops(res);
837 res = get_Proj_pred(res);
838 if (is_malloc_call_result(res)) {
839 /* ok, this is a malloc */
840 } else if (is_Call(res)) {
841 ir_node *ptr = get_Call_ptr(res);
843 if (is_Global(ptr)) {
845 ir_entity *ent = get_Global_entity(ptr);
846 ir_graph *callee = get_entity_irg(ent);
849 /* A self-recursive call. The property did not depend on this call. */
850 } else if (callee != NULL) {
851 unsigned prop = check_nothrow_or_malloc(callee, /*top=*/0);
852 curr_prop = update_property(curr_prop, prop);
854 curr_prop = update_property(curr_prop, get_entity_additional_properties(ent));
856 } else if (get_opt_closed_world() &&
858 get_irg_callee_info_state(irg) == irg_callee_info_consistent) {
859 /* check if all possible callees are malloc functions. */
860 int i, n_callees = get_Call_n_callees(res);
861 if (n_callees == 0) {
862 /* This is kind of strange: dying code or a Call that will raise an exception
863 when executed as there is no implementation to call. So better not
865 curr_prop &= ~mtp_property_malloc;
869 for (i = 0; i < n_callees; ++i) {
870 ir_entity *ent = get_Call_callee(res, i);
871 if (ent == unknown_entity) {
872 /* we don't know which entity is called here */
873 curr_prop &= ~mtp_property_malloc;
876 if ((get_entity_additional_properties(ent) & mtp_property_malloc) == 0) {
877 curr_prop &= ~mtp_property_malloc;
881 /* if we pass the for cycle, malloc is still ok */
884 curr_prop &= ~mtp_property_malloc;
887 /* unknown return value */
888 curr_prop &= ~mtp_property_malloc;
892 } else if (curr_prop & mtp_property_nothrow) {
893 /* exception flow detected */
894 pred = skip_Proj(pred);
897 ir_node *ptr = get_Call_ptr(pred);
899 if (is_Global(ptr)) {
901 ir_entity *ent = get_Global_entity(ptr);
902 ir_graph *callee = get_entity_irg(ent);
905 /* A self-recursive call. The property did not depend on this call. */
906 } else if (callee != NULL) {
907 /* Note: we check here for nothrow only, so do NOT reset the malloc property */
908 unsigned prop = check_nothrow_or_malloc(callee, /*top=*/0) | mtp_property_malloc;
909 curr_prop = update_property(curr_prop, prop);
911 if ((get_entity_additional_properties(ent) & mtp_property_nothrow) == 0)
912 curr_prop &= ~mtp_property_nothrow;
914 } else if (get_opt_closed_world() &&
916 get_irg_callee_info_state(irg) == irg_callee_info_consistent) {
917 /* check if all possible callees are nothrow functions. */
918 int i, n_callees = get_Call_n_callees(pred);
919 if (n_callees == 0) {
920 /* This is kind of strange: dying code or a Call that will raise an exception
921 when executed as there is no implementation to call. So better not
923 curr_prop &= ~mtp_property_nothrow;
927 for (i = 0; i < n_callees; ++i) {
928 ir_entity *ent = get_Call_callee(pred, i);
929 if (ent == unknown_entity) {
930 /* we don't know which entity is called here */
931 curr_prop &= ~mtp_property_nothrow;
934 if ((get_entity_additional_properties(ent) & mtp_property_nothrow) == 0) {
935 curr_prop &= ~mtp_property_nothrow;
939 /* if we pass the for cycle, nothrow is still ok */
942 curr_prop &= ~mtp_property_nothrow;
945 /* real exception flow possible. */
946 curr_prop &= ~mtp_property_nothrow;
949 if ((curr_prop & ~mtp_temporary) == mtp_no_property) {
950 /* no need to search further */
955 if (curr_prop & mtp_property_malloc) {
957 * Note that the malloc property means not only return newly allocated
958 * memory, but also that this memory is ALIAS FREE.
959 * To ensure that, we do NOT allow that the returned memory is somewhere
962 curr_prop &= check_stored_result(irg);
965 if (curr_prop != mtp_no_property) {
966 if (top || (curr_prop & mtp_temporary) == 0) {
967 /* We use the temporary flag here to mark an optimistic result.
968 Set the property only if we are sure that it does NOT base on
969 temporary results OR if we are at top-level. */
970 set_irg_additional_property(irg, curr_prop & ~mtp_temporary);
978 } /* check_nothrow_or_malloc */
981 * When a function was detected as "const", it might be moved out of loops.
982 * This might be dangerous if the graph can contain endless loops.
984 static void check_for_possible_endless_loops(ir_graph *irg) {
988 root_loop = get_irg_loop(irg);
989 if (root_loop->flags & loop_outer_loop)
990 set_irg_additional_property(irg, mtp_property_has_loop);
994 * optimize function calls by handling const functions
996 void optimize_funccalls(int force_run, check_alloc_entity_func callback)
999 unsigned num_const = 0;
1000 unsigned num_pure = 0;
1001 unsigned num_nothrow = 0;
1002 unsigned num_malloc = 0;
1004 is_alloc_entity = callback;
1006 /* prepare: mark all graphs as not analyzed */
1007 last_idx = get_irp_last_idx();
1008 ready_set = rbitset_malloc(last_idx);
1009 busy_set = rbitset_malloc(last_idx);
1011 /* first step: detect, which functions are nothrow or malloc */
1012 DB((dbg, LEVEL_2, "Detecting nothrow and malloc properties ...\n"));
1013 for (i = get_irp_n_irgs() - 1; i >= 0; --i) {
1014 ir_graph *irg = get_irp_irg(i);
1015 unsigned prop = check_nothrow_or_malloc(irg, /*top=*/1);
1017 if (prop & mtp_property_nothrow) {
1019 DB((dbg, LEVEL_2, "%+F has the nothrow property\n", irg));
1020 } else if (prop & mtp_property_malloc) {
1022 DB((dbg, LEVEL_2, "%+F has the malloc property\n", irg));
1026 /* second step: remove exception edges: this must be done before the
1027 detection of const and pure functions take place. */
1028 if (force_run || num_nothrow > 0) {
1031 handle_nothrow_Calls(&ctx);
1032 DB((dbg, LEVEL_1, "Detected %u nothrow graphs, %u malloc graphs.\n", num_nothrow, num_malloc));
1033 DB((dbg, LEVEL_1, "Optimizes %u(SymConst) + %u(Sel) calls to nothrow functions.\n",
1034 ctx.n_calls_SymConst, ctx.n_calls_Sel));
1036 DB((dbg, LEVEL_1, "No graphs without side effects detected\n"));
1039 rbitset_clear_all(ready_set, last_idx);
1040 rbitset_clear_all(busy_set, last_idx);
1042 /* third step: detect, which functions are const or pure */
1043 DB((dbg, LEVEL_2, "Detecting const and pure properties ...\n"));
1044 for (i = get_irp_n_irgs() - 1; i >= 0; --i) {
1045 ir_graph *irg = get_irp_irg(i);
1046 unsigned prop = check_const_or_pure_function(irg, /*top=*/1);
1048 if (prop & mtp_property_const) {
1050 DB((dbg, LEVEL_2, "%+F has the const property\n", irg));
1051 check_for_possible_endless_loops(irg);
1052 } else if (prop & mtp_property_pure) {
1054 DB((dbg, LEVEL_2, "%+F has the pure property\n", irg));
1058 if (force_run || num_const > 0) {
1061 handle_const_Calls(&ctx);
1062 DB((dbg, LEVEL_1, "Detected %u const graphs, %u pure graphs.\n", num_const, num_pure));
1063 DB((dbg, LEVEL_1, "Optimizes %u(SymConst) + %u(Sel) calls to const functions.\n",
1064 ctx.n_calls_SymConst, ctx.n_calls_Sel));
1066 DB((dbg, LEVEL_1, "No graphs without side effects detected\n"));
1070 } /* optimize_funccalls */
1072 /* initialize the funccall optimization */
1073 void firm_init_funccalls(void) {
1074 FIRM_DBG_REGISTER(dbg, "firm.opt.funccalls");
1075 } /* firm_init_funccalls */