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.
38 #include "iroptimize.h"
40 #include "irgraph_t.h"
45 #include "analyze_irg_args.h"
54 typedef struct _walk_env {
55 ir_node *found_allocs; /**< list of all found non-escaped allocs */
56 ir_node *dead_allocs; /**< list of all found dead alloc */
57 check_alloc_entity_func callback; /**< callback that checks a given entity for allocation */
58 unsigned nr_removed; /**< number of removed allocs (placed of frame) */
59 unsigned nr_changed; /**< number of changed allocs (allocated on stack now) */
60 unsigned nr_deads; /**< number of dead allocs */
62 /* these fields are only used in the global escape analysis */
63 ir_graph *irg; /**< the irg for this environment */
64 struct _walk_env *next; /**< for linking environments */
69 DEBUG_ONLY(firm_dbg_module_t *dbgHandle;)
72 * checks whether a Raise leaves a method
74 static int is_method_leaving_raise(ir_node *raise)
80 for (i = get_irn_n_outs(raise) - 1; i >= 0; --i) {
81 ir_node *succ = get_irn_out(raise, i);
83 /* there should be only one ProjX node */
84 if (get_Proj_proj(succ) == pn_Raise_X) {
91 /* Hmm: no ProjX from a Raise? This should be a verification
92 * error. For now we just assert and return.
94 assert(! "No ProjX after Raise found");
98 if (get_irn_n_outs(proj) != 1) {
99 /* Hmm: more than one user of ProjX: This is a verification
102 assert(! "More than one user of ProjX");
106 n = get_irn_out(proj, 0);
107 assert(is_Block(n) && "Argh: user of ProjX is no block");
109 if (n == get_irg_end_block(get_irn_irg(n)))
112 /* ok, we get here so the raise will not leave the function */
117 * returns an Alloc node if the node adr Select
120 static ir_node *is_depend_alloc(ir_node *adr) {
126 /* should be a simple Sel */
127 if (get_Sel_n_indexs(adr) != 0)
130 alloc = skip_Proj(get_Sel_ptr(adr));
131 if (!is_Alloc(alloc))
134 /* hmm, we depend on this Alloc */
135 ir_printf("depend alloc %+F\n", alloc);
141 * determine if a value calculated by n "escape", ie
142 * is stored somewhere we could not track
144 static int can_escape(ir_node *n) {
147 /* should always be pointer mode or we made some mistake */
148 assert(mode_is_reference(get_irn_mode(n)));
150 for (i = get_irn_n_outs(n) - 1; i >= 0; --i) {
151 ir_node *succ = get_irn_out(n, i);
153 switch (get_irn_opcode(succ)) {
155 if (get_Store_value(succ) == n) {
156 ir_node *adr = get_Store_ptr(succ);
159 * if this Alloc depends on another one,
162 if (is_depend_alloc(adr))
166 * We are storing n. As long as we do not further
167 * evaluate things, the pointer 'escape' here
175 * Should not happen, but if it does we leave the pointer
176 * path and do not track further
180 case iro_Call: { /* most complicated case */
181 ir_node *ptr = get_Call_ptr(succ);
184 if (is_SymConst_addr_ent(ptr)) {
185 ent = get_SymConst_entity(ptr);
187 /* we know the called entity */
188 for (j = get_Call_n_params(succ) - 1; j >= 0; --j) {
189 if (get_Call_param(succ, j) == n) {
190 /* n is the j'th param of the call */
191 if (get_method_param_access(ent, j) & ptr_access_store)
192 /* n is store in ent */
197 else if (is_Sel(ptr)) {
198 /* go through all possible callees */
199 for (k = get_Call_n_callees(succ) - 1; k >= 0; --k) {
200 ent = get_Call_callee(succ, k);
202 if (ent == unknown_entity) {
203 /* we don't know what will be called, a possible escape */
207 for (j = get_Call_n_params(succ) - 1; j >= 0; --j) {
208 if (get_Call_param(succ, j) == n) {
209 /* n is the j'th param of the call */
210 if (get_method_param_access(ent, j) & ptr_access_store)
211 /* n is store in ent */
217 else /* we don't know want will called */
224 /* Bad: the allocate object is returned */
228 /* Hmm: if we do NOT leave the method, it's local */
229 if (is_method_leaving_raise(succ))
236 /* Bad: trace the tuple backwards */
237 for (j = get_irn_arity(succ) - 1; j >= 0; --j)
238 if (get_irn_n(succ, j) == n)
244 for (k = get_irn_n_outs(succ); k >= 0; --k) {
245 proj = get_irn_out(succ, k);
247 if (get_Proj_proj(proj) == j) {
248 /* we found the right Proj */
255 * If we haven't found the right Proj, succ is still
256 * the Tuple and the search will end here.
266 if (! mode_is_reference(get_irn_mode(succ)))
269 if (can_escape(succ))
276 * walker: search for Alloc nodes and follow the usages
278 static void find_allocations(ir_node *alloc, void *ctx)
282 walk_env_t *env = ctx;
284 if (! is_Alloc(alloc))
287 /* we searching only for heap allocations */
288 if (get_Alloc_where(alloc) != heap_alloc)
292 for (i = get_irn_n_outs(alloc) - 1; i >= 0; --i) {
293 ir_node *proj = get_irn_out(alloc, i);
295 if (get_Proj_proj(proj) == pn_Alloc_res) {
303 * bad: no-one wants the result, should NOT happen but
304 * if it does we could delete it.
306 set_irn_link(alloc, env->dead_allocs);
307 env->dead_allocs = alloc;
312 if (! can_escape(adr)) {
313 set_irn_link(alloc, env->found_allocs);
314 env->found_allocs = alloc;
319 * walker: search for allocation Call nodes and follow the usages
321 static void find_allocation_calls(ir_node *call, void *ctx)
326 walk_env_t *env = ctx;
330 adr = get_Call_ptr(call);
331 if (! is_SymConst_addr_ent(adr))
333 ent = get_SymConst_entity(adr);
334 if (! env->callback(ent))
338 for (i = get_irn_n_outs(call) - 1; i >= 0; --i) {
339 ir_node *res_proj = get_irn_out(call, i);
341 if (get_Proj_proj(res_proj) == pn_Call_T_result) {
342 for (i = get_irn_n_outs(res_proj) - 1; i >= 0; --i) {
343 ir_node *proj = get_irn_out(res_proj, i);
345 if (get_Proj_proj(proj) == 0) {
346 /* found first result */
357 * bad: no-one wants the result, should NOT happen but
358 * if it does we could delete it.
360 set_irn_link(call, env->dead_allocs);
361 env->dead_allocs = call;
366 if (! can_escape(adr)) {
367 set_irn_link(call, env->found_allocs);
368 env->found_allocs = call;
373 * Do the necessary graph transformations to transform
376 static void transform_allocs(ir_graph *irg, walk_env_t *env)
378 ir_node *alloc, *next, *mem, *sel, *size, *blk;
379 ir_type *ftp, *atp, *tp;
385 /* kill all dead allocs */
386 for (alloc = env->dead_allocs; alloc; alloc = next) {
387 next = get_irn_link(alloc);
389 DBG((dbgHandle, LEVEL_1, "%+F allocation of %+F unused, deleted.\n", irg, alloc));
391 mem = get_Alloc_mem(alloc);
392 blk = get_nodes_block(alloc);
393 turn_into_tuple(alloc, pn_Alloc_max);
394 set_Tuple_pred(alloc, pn_Alloc_M, mem);
395 set_Tuple_pred(alloc, pn_Alloc_X_regular, new_r_Jmp(blk));
396 set_Tuple_pred(alloc, pn_Alloc_X_except, new_r_Bad(irg));
401 /* convert all non-escaped heap allocs into frame variables */
402 ftp = get_irg_frame_type(irg);
403 for (alloc = env->found_allocs; alloc; alloc = next) {
404 next = get_irn_link(alloc);
405 size = get_Alloc_size(alloc);
406 atp = get_Alloc_type(alloc);
409 if (is_SymConst(size) && get_SymConst_kind(size) == symconst_type_size) {
410 /* if the size is a type size and the types matched */
411 assert(atp == get_SymConst_type(size));
414 else if (is_Const(size)) {
415 tarval *tv = get_Const_tarval(size);
417 if (tv != tarval_bad && tarval_is_long(tv) &&
418 get_type_state(atp) == layout_fixed &&
419 (unsigned)get_tarval_long(tv) == get_type_size_bytes(atp)) {
420 /* a already lowered type size */
425 if (tp && tp != firm_unknown_type) {
426 /* we could determine the type, so we could place it on the frame */
427 dbg = get_irn_dbg_info(alloc);
428 blk = get_nodes_block(alloc);
430 DBG((dbgHandle, LEVEL_DEFAULT, "%+F allocation of %+F type %+F placed on frame\n", irg, alloc, tp));
432 snprintf(name, sizeof(name), "%s_NE_%u", get_entity_name(get_irg_entity(irg)), nr++);
433 name[sizeof(name) - 1] = '\0';
434 ent = new_d_entity(ftp, new_id_from_str(name), get_Alloc_type(alloc), dbg);
436 sel = new_rd_simpleSel(dbg, get_nodes_block(alloc), get_irg_no_mem(irg), get_irg_frame(irg), ent);
437 mem = get_Alloc_mem(alloc);
439 turn_into_tuple(alloc, pn_Alloc_max);
440 set_Tuple_pred(alloc, pn_Alloc_M, mem);
441 set_Tuple_pred(alloc, pn_Alloc_X_regular, new_r_Jmp(blk));
442 set_Tuple_pred(alloc, pn_Alloc_X_except, new_r_Bad(irg));
443 set_Tuple_pred(alloc, pn_Alloc_res, sel);
449 * We could not determine the type or it is variable size.
450 * At least, we could place it on the stack
452 DBG((dbgHandle, LEVEL_DEFAULT, "%+F allocation of %+F type %+F placed on stack\n", irg, alloc));
453 set_Alloc_where(alloc, stack_alloc);
459 /* if allocs were removed somehow */
460 if (env->nr_removed | env->nr_deads) {
461 set_irg_outs_inconsistent(irg);
464 /* exception control flow might have been changed */
465 set_irg_doms_inconsistent(irg);
471 * Do the necessary graph transformations to transform
474 static void transform_alloc_calls(ir_graph *irg, walk_env_t *env)
476 ir_node *call, *next, *mem, *blk;
479 /* kill all dead allocs */
480 for (call = env->dead_allocs; call; call = next) {
481 next = get_irn_link(call);
483 DBG((dbgHandle, LEVEL_1, "%+F allocation of %+F unused, deleted.\n", irg, call));
485 mem = get_Call_mem(call);
486 blk = get_nodes_block(call);
487 turn_into_tuple(call, pn_Call_max);
488 set_Tuple_pred(call, pn_Call_M_regular, mem);
489 set_Tuple_pred(call, pn_Call_X_regular, new_r_Jmp(blk));
490 set_Tuple_pred(call, pn_Call_X_except, new_r_Bad(irg));
491 set_Tuple_pred(call, pn_Call_T_result, new_r_Bad(irg));
492 set_Tuple_pred(call, pn_Call_M_except, mem);
493 set_Tuple_pred(call, pn_Call_P_value_res_base, new_r_Bad(irg));
498 /* convert all non-escaped heap allocs into frame variables */
499 ftp = get_irg_frame_type(irg);
500 for (call = env->found_allocs; call; call = next) {
501 next = get_irn_link(call);
506 /* Do simple and fast escape analysis for one graph. */
507 void escape_enalysis_irg(ir_graph *irg, check_alloc_entity_func callback)
511 if (get_irg_callee_info_state(irg) != irg_callee_info_consistent) {
512 /* no way yet to calculate this for one irg */
513 assert(! "need callee info");
517 if (get_irg_outs_state(irg) != outs_consistent)
518 compute_irg_outs(irg);
520 env.found_allocs = NULL;
521 env.dead_allocs = NULL;
522 env.callback = callback;
528 /* search for Calls */
529 irg_walk_graph(irg, NULL, find_allocation_calls, &env);
530 transform_alloc_calls(irg, &env);
532 /* search for Alloc nodes */
533 irg_walk_graph(irg, NULL, find_allocations, &env);
534 transform_allocs(irg, &env);
538 /* Do simple and fast escape analysis for all graphs. */
539 void escape_analysis(int run_scalar_replace, check_alloc_entity_func callback)
544 walk_env_t *env, *elist;
545 (void) run_scalar_replace;
547 if (get_irp_callee_info_state() != irg_callee_info_consistent) {
548 assert(! "need callee info");
552 FIRM_DBG_REGISTER(dbgHandle, "firm.opt.escape_ana");
555 * We treat memory for speed: we first collect all info in a
556 * list of environments, than do the transformation.
557 * Doing it this way, no analysis info gets invalid while we run
563 env = obstack_alloc(&obst, sizeof(*env));
564 env->found_allocs = NULL;
565 env->dead_allocs = NULL;
566 env->callback = callback;
568 for (i = get_irp_n_irgs() - 1; i >= 0; --i) {
569 irg = get_irp_irg(i);
571 assure_irg_outs(irg);
574 /* search for Calls */
575 irg_walk_graph(irg, NULL, find_allocation_calls, env);
577 /* search for Alloc nodes */
578 irg_walk_graph(irg, NULL, find_allocations, env);
581 if (env->found_allocs || env->dead_allocs) {
589 env = obstack_alloc(&obst, sizeof(*env));
590 env->found_allocs = NULL;
591 env->dead_allocs = NULL;
592 env->callback = callback;
597 for (env = elist; env; env = env->next) {
598 transform_alloc_calls(env->irg, env);
601 for (env = elist; env; env = env->next) {
602 transform_allocs(env->irg, env);
606 obstack_free(&obst, NULL);