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
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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 */
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 panic("No ProjX after Raise found");
97 if (get_irn_n_outs(proj) != 1) {
98 /* Hmm: more than one user of ProjX: This is a verification
101 panic("More than one user of ProjX");
104 n = get_irn_out(proj, 0);
105 assert(is_Block(n) && "Argh: user of ProjX is no block");
107 if (n == get_irg_end_block(get_irn_irg(n)))
110 /* ok, we get here so the raise will not leave the function */
115 * returns an Alloc node if the node adr Select
118 static ir_node *is_depend_alloc(ir_node *adr)
125 /* should be a simple Sel */
126 if (get_Sel_n_indexs(adr) != 0)
129 alloc = skip_Proj(get_Sel_ptr(adr));
130 if (!is_Alloc(alloc))
133 /* hmm, we depend on this Alloc */
134 ir_printf("depend alloc %+F\n", alloc);
140 * determine if a value calculated by n "escape", ie
141 * is stored somewhere we could not track
143 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)) {
186 ent = get_SymConst_entity(ptr);
188 /* we know the called entity */
189 for (j = get_Call_n_params(succ); j > 0;) {
190 if (get_Call_param(succ, --j) == n) {
191 /* n is the j'th param of the call */
192 if (get_method_param_access(ent, j) & ptr_access_store)
193 /* n is store in ent */
197 } else if (is_Sel(ptr)) {
200 /* go through all possible callees */
201 for (k = get_Call_n_callees(succ); k > 0;) {
203 ent = get_Call_callee(succ, --k);
205 if (ent == unknown_entity) {
206 /* we don't know what will be called, a possible escape */
210 for (j = get_Call_n_params(succ); j > 0;) {
211 if (get_Call_param(succ, --j) == n) {
212 /* n is the j'th param of the call */
213 if (get_method_param_access(ent, j) & ptr_access_store)
214 /* 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))
239 /* Bad: trace the tuple backwards */
240 for (j = get_irn_arity(succ) - 1; j >= 0; --j)
241 if (get_irn_n(succ, j) == n)
247 for (k = get_irn_n_outs(succ); k >= 0; --k) {
248 proj = get_irn_out(succ, k);
250 if (get_Proj_proj(proj) == j) {
251 /* we found the right Proj */
258 * If we haven't found the right Proj, succ is still
259 * the Tuple and the search will end here.
269 if (! mode_is_reference(get_irn_mode(succ)))
272 if (can_escape(succ))
279 * walker: search for Alloc nodes and follow the usages
281 static void find_allocations(ir_node *alloc, void *ctx)
283 walk_env_t *env = (walk_env_t*)ctx;
287 if (! is_Alloc(alloc))
290 /* we searching only for heap allocations */
291 if (get_Alloc_where(alloc) != heap_alloc)
295 for (i = get_irn_n_outs(alloc) - 1; i >= 0; --i) {
296 ir_node *proj = get_irn_out(alloc, i);
298 if (get_Proj_proj(proj) == pn_Alloc_res) {
306 * bad: no-one wants the result, should NOT happen but
307 * if it does we could delete it.
309 set_irn_link(alloc, env->dead_allocs);
310 env->dead_allocs = alloc;
315 if (! can_escape(adr)) {
316 set_irn_link(alloc, env->found_allocs);
317 env->found_allocs = alloc;
322 * walker: search for allocation Call nodes and follow the usages
324 static void find_allocation_calls(ir_node *call, void *ctx)
326 walk_env_t *env = (walk_env_t*)ctx;
333 adr = get_Call_ptr(call);
334 if (! is_SymConst_addr_ent(adr))
336 ent = get_SymConst_entity(adr);
337 if (! env->callback(ent))
341 for (i = get_irn_n_outs(call) - 1; i >= 0; --i) {
342 ir_node *res_proj = get_irn_out(call, i);
344 if (get_Proj_proj(res_proj) == pn_Call_T_result) {
345 for (i = get_irn_n_outs(res_proj) - 1; i >= 0; --i) {
346 ir_node *proj = get_irn_out(res_proj, i);
348 if (get_Proj_proj(proj) == 0) {
349 /* found first result */
360 * bad: no-one wants the result, should NOT happen but
361 * if it does we could delete it.
363 set_irn_link(call, env->dead_allocs);
364 env->dead_allocs = call;
369 if (! can_escape(adr)) {
370 set_irn_link(call, env->found_allocs);
371 env->found_allocs = call;
376 * Do the necessary graph transformations to transform
379 static void transform_allocs(ir_graph *irg, walk_env_t *env)
381 ir_node *alloc, *next, *mem, *sel, *size, *blk;
382 ir_type *ftp, *atp, *tp;
388 /* kill all dead allocs */
389 for (alloc = env->dead_allocs; alloc; alloc = next) {
390 next = (ir_node*)get_irn_link(alloc);
392 DBG((dbgHandle, LEVEL_1, "%+F allocation of %+F unused, deleted.\n", irg, alloc));
394 mem = get_Alloc_mem(alloc);
395 blk = get_nodes_block(alloc);
396 turn_into_tuple(alloc, pn_Alloc_max);
397 set_Tuple_pred(alloc, pn_Alloc_M, mem);
398 set_Tuple_pred(alloc, pn_Alloc_X_regular, new_r_Jmp(blk));
399 set_Tuple_pred(alloc, pn_Alloc_X_except, new_r_Bad(irg, mode_X));
404 /* convert all non-escaped heap allocs into frame variables */
405 ftp = get_irg_frame_type(irg);
406 for (alloc = env->found_allocs; alloc; alloc = next) {
407 next = (ir_node*)get_irn_link(alloc);
408 size = get_Alloc_count(alloc);
409 atp = get_Alloc_type(alloc);
412 if (is_SymConst(size) && get_SymConst_kind(size) == symconst_type_size) {
413 /* if the size is a type size and the types matched */
414 assert(atp == get_SymConst_type(size));
416 } else if (is_Const(size)) {
417 ir_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, get_nodes_block(alloc), get_irg_no_mem(irg), get_irg_frame(irg), ent);
439 mem = get_Alloc_mem(alloc);
441 turn_into_tuple(alloc, pn_Alloc_max);
442 set_Tuple_pred(alloc, pn_Alloc_M, mem);
443 set_Tuple_pred(alloc, pn_Alloc_X_regular, new_r_Jmp(blk));
444 set_Tuple_pred(alloc, pn_Alloc_X_except, new_r_Bad(irg, mode_X));
445 set_Tuple_pred(alloc, pn_Alloc_res, sel);
451 * We could not determine the type or it is variable size.
452 * At least, we could place it on the stack
454 DBG((dbgHandle, LEVEL_DEFAULT, "%+F allocation of %+F type %+F placed on stack\n", irg, alloc));
455 set_Alloc_where(alloc, stack_alloc);
461 /* if allocs were removed somehow */
462 if (env->nr_removed && env->nr_deads) {
463 /* exception control flow might have been changed */
464 set_irg_doms_inconsistent(irg);
469 * Do the necessary graph transformations to transform
472 static void transform_alloc_calls(ir_graph *irg, walk_env_t *env)
474 ir_node *call, *next, *mem, *blk;
477 /* kill all dead allocs */
478 for (call = env->dead_allocs; call; call = next) {
479 next = (ir_node*)get_irn_link(call);
481 DBG((dbgHandle, LEVEL_1, "%+F allocation of %+F unused, deleted.\n", irg, call));
483 mem = get_Call_mem(call);
484 blk = get_nodes_block(call);
485 turn_into_tuple(call, pn_Call_max);
486 set_Tuple_pred(call, pn_Call_M, mem);
487 set_Tuple_pred(call, pn_Call_X_regular, new_r_Jmp(blk));
488 set_Tuple_pred(call, pn_Call_X_except, new_r_Bad(irg, mode_X));
489 set_Tuple_pred(call, pn_Call_T_result, new_r_Bad(irg, mode_T));
494 /* convert all non-escaped heap allocs into frame variables */
495 ftp = get_irg_frame_type(irg);
496 for (call = env->found_allocs; call; call = next) {
497 next = (ir_node*)get_irn_link(call);
502 /* Do simple and fast escape analysis for one graph. */
503 void escape_enalysis_irg(ir_graph *irg, check_alloc_entity_func callback)
507 if (get_irg_callee_info_state(irg) != irg_callee_info_consistent) {
508 /* no way yet to calculate this for one irg */
509 assert(! "need callee info");
513 if (get_irg_outs_state(irg) != outs_consistent)
514 compute_irg_outs(irg);
516 env.found_allocs = NULL;
517 env.dead_allocs = NULL;
518 env.callback = callback;
524 /* search for Calls */
525 irg_walk_graph(irg, NULL, find_allocation_calls, &env);
526 transform_alloc_calls(irg, &env);
528 /* search for Alloc nodes */
529 irg_walk_graph(irg, NULL, find_allocations, &env);
530 transform_allocs(irg, &env);
534 /* Do simple and fast escape analysis for all graphs. */
535 void escape_analysis(int run_scalar_replace, check_alloc_entity_func callback)
539 walk_env_t *env, *elist;
540 (void) run_scalar_replace;
542 if (get_irp_callee_info_state() != irg_callee_info_consistent) {
543 assert(! "need callee info");
547 FIRM_DBG_REGISTER(dbgHandle, "firm.opt.escape_ana");
550 * We treat memory for speed: we first collect all info in a
551 * list of environments, than do the transformation.
552 * Doing it this way, no analysis info gets invalid while we run
558 env = OALLOC(&obst, walk_env_t);
559 env->found_allocs = NULL;
560 env->dead_allocs = NULL;
561 env->callback = callback;
563 for (i = 0, n = get_irp_n_irgs(); i < n; ++i) {
564 ir_graph *irg = get_irp_irg(i);
566 assure_irg_outs(irg);
569 /* search for Calls */
570 irg_walk_graph(irg, NULL, find_allocation_calls, env);
572 /* search for Alloc nodes */
573 irg_walk_graph(irg, NULL, find_allocations, env);
576 if (env->found_allocs || env->dead_allocs) {
584 env = OALLOC(&obst, walk_env_t);
585 env->found_allocs = NULL;
586 env->dead_allocs = NULL;
587 env->callback = callback;
592 for (env = elist; env; env = env->next) {
593 transform_alloc_calls(env->irg, env);
596 for (env = elist; env; env = env->next) {
597 transform_allocs(env->irg, env);
601 obstack_free(&obst, NULL);