2 * Copyright (C) 1995-2011 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"
55 typedef struct walk_env {
56 ir_node *found_allocs; /**< list of all found non-escaped allocs */
57 ir_node *dead_allocs; /**< list of all found dead alloc */
58 check_alloc_entity_func callback; /**< callback that checks a given entity for allocation */
59 unsigned nr_removed; /**< number of removed allocs (placed of frame) */
60 unsigned nr_changed; /**< number of changed allocs (allocated on stack now) */
61 unsigned nr_deads; /**< number of dead allocs */
63 /* these fields are only used in the global escape analysis */
64 ir_graph *irg; /**< the irg for this environment */
65 struct walk_env *next; /**< for linking environments */
70 DEBUG_ONLY(firm_dbg_module_t *dbgHandle;)
73 * checks whether a Raise leaves a method
75 static int is_method_leaving_raise(ir_node *raise)
81 for (i = get_irn_n_outs(raise) - 1; i >= 0; --i) {
82 ir_node *succ = get_irn_out(raise, i);
84 /* there should be only one ProjX node */
85 if (get_Proj_proj(succ) == pn_Raise_X) {
92 /* Hmm: no ProjX from a Raise? This should be a verification
93 * error. For now we just assert and return.
95 panic("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 panic("More than one user of ProjX");
105 n = get_irn_out(proj, 0);
106 assert(is_Block(n) && "Argh: user of ProjX is no block");
108 if (n == get_irg_end_block(get_irn_irg(n)))
111 /* ok, we get here so the raise will not leave the function */
116 * returns an Alloc node if the node adr Select
119 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)
148 /* should always be pointer mode or we made some mistake */
149 assert(mode_is_reference(get_irn_mode(n)));
151 for (i = get_irn_n_outs(n) - 1; i >= 0; --i) {
152 ir_node *succ = get_irn_out(n, i);
154 switch (get_irn_opcode(succ)) {
156 if (get_Store_value(succ) == n) {
157 ir_node *adr = get_Store_ptr(succ);
160 * if this Alloc depends on another one,
163 if (is_depend_alloc(adr))
167 * We are storing n. As long as we do not further
168 * evaluate things, the pointer 'escape' here
176 * Should not happen, but if it does we leave the pointer
177 * path and do not track further
181 case iro_Call: { /* most complicated case */
182 ir_node *ptr = get_Call_ptr(succ);
185 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); j > 0;) {
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 */
198 } else if (is_Sel(ptr)) {
201 /* go through all possible callees */
202 for (k = get_Call_n_callees(succ); k > 0;) {
204 ent = get_Call_callee(succ, --k);
206 if (ent == unknown_entity) {
207 /* we don't know what will be called, a possible escape */
211 for (j = get_Call_n_params(succ); j > 0;) {
212 if (get_Call_param(succ, --j) == n) {
213 /* n is the j'th param of the call */
214 if (get_method_param_access(ent, j) & ptr_access_store)
215 /* n is store in ent */
220 } else /* we don't know want will called */
227 /* Bad: the allocate object is returned */
231 /* Hmm: if we do NOT leave the method, it's local */
232 if (is_method_leaving_raise(succ))
240 /* Bad: trace the tuple backwards */
241 for (j = get_irn_arity(succ) - 1; j >= 0; --j)
242 if (get_irn_n(succ, j) == n)
248 for (k = get_irn_n_outs(succ); k >= 0; --k) {
249 proj = get_irn_out(succ, k);
251 if (get_Proj_proj(proj) == j) {
252 /* we found the right Proj */
259 * If we haven't found the right Proj, succ is still
260 * the Tuple and the search will end here.
270 if (! mode_is_reference(get_irn_mode(succ)))
273 if (can_escape(succ))
280 * walker: search for Alloc nodes and follow the usages
282 static void find_allocations(ir_node *alloc, void *ctx)
284 walk_env_t *env = (walk_env_t*)ctx;
288 if (! is_Alloc(alloc))
291 /* we searching only for heap allocations */
292 if (get_Alloc_where(alloc) != heap_alloc)
296 for (i = get_irn_n_outs(alloc) - 1; i >= 0; --i) {
297 ir_node *proj = get_irn_out(alloc, i);
299 if (get_Proj_proj(proj) == pn_Alloc_res) {
307 * bad: no-one wants the result, should NOT happen but
308 * if it does we could delete it.
310 set_irn_link(alloc, env->dead_allocs);
311 env->dead_allocs = alloc;
316 if (! can_escape(adr)) {
317 set_irn_link(alloc, env->found_allocs);
318 env->found_allocs = alloc;
323 * walker: search for allocation Call nodes and follow the usages
325 static void find_allocation_calls(ir_node *call, void *ctx)
327 walk_env_t *env = (walk_env_t*)ctx;
334 adr = get_Call_ptr(call);
335 if (! is_SymConst_addr_ent(adr))
337 ent = get_SymConst_entity(adr);
338 if (! env->callback(ent))
342 for (i = get_irn_n_outs(call) - 1; i >= 0; --i) {
343 ir_node *res_proj = get_irn_out(call, i);
345 if (get_Proj_proj(res_proj) == pn_Call_T_result) {
346 for (i = get_irn_n_outs(res_proj) - 1; i >= 0; --i) {
347 ir_node *proj = get_irn_out(res_proj, i);
349 if (get_Proj_proj(proj) == 0) {
350 /* found first result */
361 * bad: no-one wants the result, should NOT happen but
362 * if it does we could delete it.
364 set_irn_link(call, env->dead_allocs);
365 env->dead_allocs = call;
370 if (! can_escape(adr)) {
371 set_irn_link(call, env->found_allocs);
372 env->found_allocs = call;
377 * Do the necessary graph transformations to transform
380 static void transform_allocs(ir_graph *irg, walk_env_t *env)
382 ir_node *alloc, *next, *mem, *sel, *size, *blk;
383 ir_type *ftp, *atp, *tp;
389 /* kill all dead allocs */
390 for (alloc = env->dead_allocs; alloc; alloc = next) {
391 next = (ir_node*)get_irn_link(alloc);
393 DBG((dbgHandle, LEVEL_1, "%+F allocation of %+F unused, deleted.\n", irg, alloc));
395 mem = get_Alloc_mem(alloc);
396 blk = get_nodes_block(alloc);
397 turn_into_tuple(alloc, pn_Alloc_max);
398 set_Tuple_pred(alloc, pn_Alloc_M, mem);
399 set_Tuple_pred(alloc, pn_Alloc_X_regular, new_r_Jmp(blk));
400 set_Tuple_pred(alloc, pn_Alloc_X_except, new_r_Bad(irg, mode_X));
405 /* convert all non-escaped heap allocs into frame variables */
406 ftp = get_irg_frame_type(irg);
407 for (alloc = env->found_allocs; alloc; alloc = next) {
408 next = (ir_node*)get_irn_link(alloc);
409 size = get_Alloc_count(alloc);
410 atp = get_Alloc_type(alloc);
413 if (is_SymConst(size) && get_SymConst_kind(size) == symconst_type_size) {
414 /* if the size is a type size and the types matched */
415 assert(atp == get_SymConst_type(size));
417 } else if (is_Const(size)) {
418 ir_tarval *tv = get_Const_tarval(size);
420 if (tv != tarval_bad && tarval_is_long(tv) &&
421 get_type_state(atp) == layout_fixed &&
422 (unsigned)get_tarval_long(tv) == get_type_size_bytes(atp)) {
423 /* a already lowered type size */
428 if (tp && tp != firm_unknown_type) {
429 /* we could determine the type, so we could place it on the frame */
430 dbg = get_irn_dbg_info(alloc);
431 blk = get_nodes_block(alloc);
433 DBG((dbgHandle, LEVEL_DEFAULT, "%+F allocation of %+F type %+F placed on frame\n", irg, alloc, tp));
435 snprintf(name, sizeof(name), "%s_NE_%u", get_entity_name(get_irg_entity(irg)), nr++);
436 name[sizeof(name) - 1] = '\0';
437 ent = new_d_entity(ftp, new_id_from_str(name), get_Alloc_type(alloc), dbg);
439 sel = new_rd_simpleSel(dbg, get_nodes_block(alloc), 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(blk));
445 set_Tuple_pred(alloc, pn_Alloc_X_except, new_r_Bad(irg, mode_X));
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 /* exception control flow might have been changed */
465 set_irg_doms_inconsistent(irg);
470 * Do the necessary graph transformations to transform
473 static void transform_alloc_calls(ir_graph *irg, walk_env_t *env)
475 ir_node *call, *next, *mem, *blk;
478 /* kill all dead allocs */
479 for (call = env->dead_allocs; call; call = next) {
480 next = (ir_node*)get_irn_link(call);
482 DBG((dbgHandle, LEVEL_1, "%+F allocation of %+F unused, deleted.\n", irg, call));
484 mem = get_Call_mem(call);
485 blk = get_nodes_block(call);
486 turn_into_tuple(call, pn_Call_max);
487 set_Tuple_pred(call, pn_Call_M, mem);
488 set_Tuple_pred(call, pn_Call_X_regular, new_r_Jmp(blk));
489 set_Tuple_pred(call, pn_Call_X_except, new_r_Bad(irg, mode_X));
490 set_Tuple_pred(call, pn_Call_T_result, new_r_Bad(irg, mode_T));
495 /* convert all non-escaped heap allocs into frame variables */
496 ftp = get_irg_frame_type(irg);
497 for (call = env->found_allocs; call; call = next) {
498 next = (ir_node*)get_irn_link(call);
503 /* Do simple and fast escape analysis for one graph. */
504 void escape_enalysis_irg(ir_graph *irg, check_alloc_entity_func callback)
508 if (get_irg_callee_info_state(irg) != irg_callee_info_consistent) {
509 /* no way yet to calculate this for one irg */
510 assert(! "need callee info");
514 if (get_irg_outs_state(irg) != outs_consistent)
515 compute_irg_outs(irg);
517 env.found_allocs = NULL;
518 env.dead_allocs = NULL;
519 env.callback = callback;
525 /* search for Calls */
526 irg_walk_graph(irg, NULL, find_allocation_calls, &env);
527 transform_alloc_calls(irg, &env);
529 /* search for Alloc nodes */
530 irg_walk_graph(irg, NULL, find_allocations, &env);
531 transform_allocs(irg, &env);
535 /* Do simple and fast escape analysis for all graphs. */
536 void escape_analysis(int run_scalar_replace, check_alloc_entity_func callback)
540 walk_env_t *env, *elist;
541 (void) run_scalar_replace;
543 if (get_irp_callee_info_state() != irg_callee_info_consistent) {
544 assert(! "need callee info");
548 FIRM_DBG_REGISTER(dbgHandle, "firm.opt.escape_ana");
551 * We treat memory for speed: we first collect all info in a
552 * list of environments, than do the transformation.
553 * Doing it this way, no analysis info gets invalid while we run
559 env = OALLOC(&obst, walk_env_t);
560 env->found_allocs = NULL;
561 env->dead_allocs = NULL;
562 env->callback = callback;
564 for (i = 0, n = get_irp_n_irgs(); i < n; ++i) {
565 ir_graph *irg = get_irp_irg(i);
567 assure_irg_outs(irg);
570 /* search for Calls */
571 irg_walk_graph(irg, NULL, find_allocation_calls, env);
573 /* search for Alloc nodes */
574 irg_walk_graph(irg, NULL, find_allocations, env);
577 if (env->found_allocs || env->dead_allocs) {
585 env = OALLOC(&obst, walk_env_t);
586 env->found_allocs = NULL;
587 env->dead_allocs = NULL;
588 env->callback = callback;
593 for (env = elist; env; env = env->next) {
594 transform_alloc_calls(env->irg, env);
597 for (env = elist; env; env = env->next) {
598 transform_allocs(env->irg, env);
602 obstack_free(&obst, NULL);