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 * File name: ir/opt/escape_ana.c
23 * Purpose: escape analysis and optimization
24 * Author: Michael Beck
28 * Copyright: (c) 1999-2005 Universität Karlsruhe
34 * A fast and simple Escape analysis.
40 #include "iroptimize.h"
42 #include "irgraph_t.h"
47 #include "analyze_irg_args.h"
56 typedef struct _walk_env {
57 ir_node *found_allocs; /**< list of all found non-escaped allocs */
58 ir_node *dead_allocs; /**< list of all found dead alloc */
59 check_alloc_entity_func callback; /**< callback that checks a given entity for allocation */
60 unsigned nr_removed; /**< number of removed allocs (placed of frame) */
61 unsigned nr_changed; /**< number of changed allocs (allocated on stack now) */
62 unsigned nr_deads; /**< number of dead allocs */
64 /* these fields are only used in the global escape analysis */
65 ir_graph *irg; /**< the irg for this environment */
66 struct _walk_env *next; /**< for linking environments */
71 DEBUG_ONLY(firm_dbg_module_t *dbgHandle;)
74 * checks whether a Raise leaves a method
76 static int is_method_leaving_raise(ir_node *raise)
82 for (i = get_irn_n_outs(raise) - 1; i >= 0; --i) {
83 ir_node *succ = get_irn_out(raise, i);
85 /* there should be only one ProjX node */
86 if (get_Proj_proj(succ) == pn_Raise_X) {
93 /* Hmm: no ProjX from a Raise? This should be a verification
94 * error. For now we just assert and return.
96 assert(! "No ProjX after Raise found");
100 if (get_irn_n_outs(proj) != 1) {
101 /* Hmm: more than one user of ProjX: This is a verification
104 assert(! "More than one user of ProjX");
108 n = get_irn_out(proj, 0);
109 assert(is_Block(n) && "Argh: user of ProjX is no block");
111 if (n == get_irg_end_block(get_irn_irg(n)))
114 /* ok, we get here so the raise will not leave the function */
119 * returns an Alloc node if the node adr Select
122 static ir_node *is_depend_alloc(ir_node *adr) {
128 /* should be a simple Sel */
129 if (get_Sel_n_indexs(adr) != 0)
132 alloc = skip_Proj(get_Sel_ptr(adr));
133 if (!is_Alloc(alloc))
136 /* hmm, we depend on this Alloc */
137 ir_printf("depend alloc %+F\n", alloc);
143 * determine if a value calculated by n "escape", ie
144 * is stored somewhere we could not track
146 static int can_escape(ir_node *n) {
149 /* should always be pointer mode or we made some mistake */
150 assert(mode_is_reference(get_irn_mode(n)));
152 for (i = get_irn_n_outs(n) - 1; i >= 0; --i) {
153 ir_node *succ = get_irn_out(n, i);
155 switch (get_irn_opcode(succ)) {
157 if (get_Store_value(succ) == n) {
158 ir_node *adr = get_Store_ptr(succ);
161 * if this Alloc depends on another one,
164 if (is_depend_alloc(adr))
168 * We are storing n. As long as we do not further
169 * evaluate things, the pointer 'escape' here
177 * Should not happen, but if it does we leave the pointer
178 * path and do not track further
182 case iro_Call: { /* most complicated case */
183 ir_node *ptr = get_Call_ptr(succ);
186 if (is_SymConst_addr_ent(ptr)) {
187 ent = get_SymConst_entity(ptr);
189 /* we know the called entity */
190 for (j = get_Call_n_params(succ) - 1; j >= 0; --j) {
191 if (get_Call_param(succ, j) == n) {
192 /* n is the j'th param of the call */
193 if (get_method_param_access(ent, j) & ptr_access_store)
194 /* n is store in ent */
199 else if (is_Sel(ptr)) {
200 /* go through all possible callees */
201 for (k = get_Call_n_callees(succ) - 1; k >= 0; --k) {
202 ent = get_Call_callee(succ, k);
204 if (ent == unknown_entity) {
205 /* we don't know what will be called, a possible escape */
209 for (j = get_Call_n_params(succ) - 1; j >= 0; --j) {
210 if (get_Call_param(succ, j) == n) {
211 /* n is the j'th param of the call */
212 if (get_method_param_access(ent, j) & ptr_access_store)
213 /* n is store in ent */
219 else /* we don't know want will called */
226 /* Bad: the allocate object is returned */
230 /* Hmm: if we do NOT leave the method, it's local */
231 if (is_method_leaving_raise(succ))
238 /* Bad: trace the tuple backwards */
239 for (j = get_irn_arity(succ) - 1; j >= 0; --j)
240 if (get_irn_n(succ, j) == n)
246 for (k = get_irn_n_outs(succ); k >= 0; --k) {
247 proj = get_irn_out(succ, k);
249 if (get_Proj_proj(proj) == j) {
250 /* we found the right Proj */
257 * If we haven't found the right Proj, succ is still
258 * the Tuple and the search will end here.
268 if (! mode_is_reference(get_irn_mode(succ)))
271 if (can_escape(succ))
278 * walker: search for Alloc nodes and follow the usages
280 static void find_allocations(ir_node *alloc, void *ctx)
284 walk_env_t *env = ctx;
286 if (! is_Alloc(alloc))
289 /* we searching only for heap allocations */
290 if (get_Alloc_where(alloc) != heap_alloc)
294 for (i = get_irn_n_outs(alloc) - 1; i >= 0; --i) {
295 ir_node *proj = get_irn_out(alloc, i);
297 if (get_Proj_proj(proj) == pn_Alloc_res) {
305 * bad: no-one wants the result, should NOT happen but
306 * if it does we could delete it.
308 set_irn_link(alloc, env->dead_allocs);
309 env->dead_allocs = alloc;
314 if (! can_escape(adr)) {
315 set_irn_link(alloc, env->found_allocs);
316 env->found_allocs = alloc;
321 * walker: search for allocation Call nodes and follow the usages
323 static void find_allocation_calls(ir_node *call, void *ctx)
328 walk_env_t *env = ctx;
332 adr = get_Call_ptr(call);
333 if (! is_SymConst_addr_ent(adr))
335 ent = get_SymConst_entity(adr);
336 if (! env->callback(ent))
340 for (i = get_irn_n_outs(call) - 1; i >= 0; --i) {
341 ir_node *res_proj = get_irn_out(call, i);
343 if (get_Proj_proj(res_proj) == pn_Call_T_result) {
344 for (i = get_irn_n_outs(res_proj) - 1; i >= 0; --i) {
345 ir_node *proj = get_irn_out(res_proj, i);
347 if (get_Proj_proj(proj) == 0) {
348 /* found first result */
359 * bad: no-one wants the result, should NOT happen but
360 * if it does we could delete it.
362 set_irn_link(call, env->dead_allocs);
363 env->dead_allocs = call;
368 if (! can_escape(adr)) {
369 set_irn_link(call, env->found_allocs);
370 env->found_allocs = call;
375 * Do the necessary graph transformations to transform
378 static void transform_allocs(ir_graph *irg, walk_env_t *env)
380 ir_node *alloc, *next, *mem, *sel, *size, *blk;
381 ir_type *ftp, *atp, *tp;
387 /* kill all dead allocs */
388 for (alloc = env->dead_allocs; alloc; alloc = next) {
389 next = get_irn_link(alloc);
391 DBG((dbgHandle, LEVEL_1, "%+F allocation of %+F unused, deleted.\n", irg, alloc));
393 mem = get_Alloc_mem(alloc);
394 blk = get_nodes_block(alloc);
395 turn_into_tuple(alloc, pn_Alloc_max);
396 set_Tuple_pred(alloc, pn_Alloc_M, mem);
397 set_Tuple_pred(alloc, pn_Alloc_X_regular, new_r_Jmp(irg, blk));
398 set_Tuple_pred(alloc, pn_Alloc_X_except, new_r_Bad(irg));
403 /* convert all non-escaped heap allocs into frame variables */
404 ftp = get_irg_frame_type(irg);
405 for (alloc = env->found_allocs; alloc; alloc = next) {
406 next = get_irn_link(alloc);
407 size = get_Alloc_size(alloc);
408 atp = get_Alloc_type(alloc);
411 if (is_SymConst(size) && get_SymConst_kind(size) == symconst_type_size) {
412 /* if the size is a type size and the types matched */
413 assert(atp == get_SymConst_type(size));
416 else if (is_Const(size)) {
417 tarval *tv = get_Const_tarval(size);
419 if (tv != tarval_bad && tarval_is_long(tv) &&
420 get_type_state(atp) == layout_fixed &&
421 (unsigned)get_tarval_long(tv) == get_type_size_bytes(atp)) {
422 /* a already lowered type size */
427 if (tp && tp != firm_unknown_type) {
428 /* we could determine the type, so we could place it on the frame */
429 dbg = get_irn_dbg_info(alloc);
430 blk = get_nodes_block(alloc);
432 DBG((dbgHandle, LEVEL_DEFAULT, "%+F allocation of %+F type %+F placed on frame\n", irg, alloc, tp));
434 snprintf(name, sizeof(name), "%s_NE_%u", get_entity_name(get_irg_entity(irg)), nr++);
435 name[sizeof(name) - 1] = '\0';
436 ent = new_d_entity(ftp, new_id_from_str(name), get_Alloc_type(alloc), dbg);
438 sel = new_rd_simpleSel(dbg, irg, get_nodes_block(alloc),
439 get_irg_no_mem(irg), get_irg_frame(irg), ent);
440 mem = get_Alloc_mem(alloc);
442 turn_into_tuple(alloc, pn_Alloc_max);
443 set_Tuple_pred(alloc, pn_Alloc_M, mem);
444 set_Tuple_pred(alloc, pn_Alloc_X_regular, new_r_Jmp(irg, blk));
445 set_Tuple_pred(alloc, pn_Alloc_X_except, new_r_Bad(irg));
446 set_Tuple_pred(alloc, pn_Alloc_res, sel);
452 * We could not determine the type or it is variable size.
453 * At least, we could place it on the stack
455 DBG((dbgHandle, LEVEL_DEFAULT, "%+F allocation of %+F type %+F placed on stack\n", irg, alloc));
456 set_Alloc_where(alloc, stack_alloc);
462 /* if allocs were removed somehow */
463 if (env->nr_removed | env->nr_deads) {
464 set_irg_outs_inconsistent(irg);
467 /* exception control flow might have been changed */
468 set_irg_doms_inconsistent(irg);
474 * Do the necessary graph transformations to transform
477 static void transform_alloc_calls(ir_graph *irg, walk_env_t *env)
479 ir_node *call, *next, *mem, *blk;
482 /* kill all dead allocs */
483 for (call = env->dead_allocs; call; call = next) {
484 next = get_irn_link(call);
486 DBG((dbgHandle, LEVEL_1, "%+F allocation of %+F unused, deleted.\n", irg, call));
488 mem = get_Call_mem(call);
489 blk = get_nodes_block(call);
490 turn_into_tuple(call, pn_Call_max);
491 set_Tuple_pred(call, pn_Call_M_regular, mem);
492 set_Tuple_pred(call, pn_Call_X_regular, new_r_Jmp(irg, blk));
493 set_Tuple_pred(call, pn_Call_X_except, new_r_Bad(irg));
494 set_Tuple_pred(call, pn_Call_T_result, new_r_Bad(irg));
495 set_Tuple_pred(call, pn_Call_M_except, mem);
496 set_Tuple_pred(call, pn_Call_P_value_res_base, new_r_Bad(irg));
501 /* convert all non-escaped heap allocs into frame variables */
502 ftp = get_irg_frame_type(irg);
503 for (call = env->found_allocs; call; call = next) {
504 next = get_irn_link(call);
509 /* Do simple and fast escape analysis for one graph. */
510 void escape_enalysis_irg(ir_graph *irg, check_alloc_entity_func callback)
514 if (get_irg_callee_info_state(irg) != irg_callee_info_consistent) {
515 /* no way yet to calculate this for one irg */
516 assert(! "need callee info");
520 if (get_irg_outs_state(irg) != outs_consistent)
521 compute_irg_outs(irg);
523 env.found_allocs = NULL;
524 env.dead_allocs = NULL;
525 env.callback = callback;
531 /* search for Calls */
532 irg_walk_graph(irg, NULL, find_allocation_calls, &env);
533 transform_alloc_calls(irg, &env);
535 /* search for Alloc nodes */
536 irg_walk_graph(irg, NULL, find_allocations, &env);
537 transform_allocs(irg, &env);
541 /* Do simple and fast escape analysis for all graphs. */
542 void escape_analysis(int run_scalar_replace, check_alloc_entity_func callback)
547 walk_env_t *env, *elist;
548 (void) run_scalar_replace;
550 if (get_irp_callee_info_state() != irg_callee_info_consistent) {
551 assert(! "need callee info");
555 FIRM_DBG_REGISTER(dbgHandle, "firm.opt.escape_ana");
558 * We treat memory for speed: we first collect all info in a
559 * list of environments, than do the transformation.
560 * Doing it this way, no analysis info gets invalid while we run
566 env = obstack_alloc(&obst, sizeof(*env));
567 env->found_allocs = NULL;
568 env->dead_allocs = NULL;
569 env->callback = callback;
571 for (i = get_irp_n_irgs() - 1; i >= 0; --i) {
572 irg = get_irp_irg(i);
574 assure_irg_outs(irg);
577 /* search for Calls */
578 irg_walk_graph(irg, NULL, find_allocation_calls, env);
580 /* search for Alloc nodes */
581 irg_walk_graph(irg, NULL, find_allocations, env);
584 if (env->found_allocs || env->dead_allocs) {
592 env = obstack_alloc(&obst, sizeof(*env));
593 env->found_allocs = NULL;
594 env->dead_allocs = NULL;
595 env->callback = callback;
600 for (env = elist; env; env = env->next) {
601 transform_alloc_calls(env->irg, env);
604 for (env = elist; env; env = env->next) {
605 transform_allocs(env->irg, env);
609 obstack_free(&obst, NULL);