start register allocator again, fix typo
[libfirm] / ir / be / bespillmorgan.c
1 /*
2  * Author:      Matthias Braun
3  * Date:                05.05.2006
4  * Copyright:   (c) Universitaet Karlsruhe
5  * License:     This file is protected by GPL -  GNU GENERAL PUBLIC LICENSE.
6  *
7  */
8 #ifdef HAVE_CONFIG_H
9 #include "config.h"
10 #endif
11
12 #include "bespillmorgan.h"
13
14 #include "bechordal_t.h"
15 #include "bespill.h"
16 #include "belive_t.h"
17 #include "beabi.h"
18 #include "irgwalk.h"
19 #include "besched.h"
20 #include "beutil.h"
21 #include "irloop_t.h"
22 #include "irgraph_t.h"
23 #include "irprintf.h"
24 #include "obstack.h"
25
26 #include "bespillbelady.h"
27 #include "beverify.h"
28 #include "benodesets.h"
29
30 #define DBG_LIVE                1
31 #define DBG_LOOPANA             2
32 #define DBG_PRESSURE    4
33 #define DBG_SPILLS      8
34 #define DBG_CHOOSE              16
35 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
36
37 typedef struct morgan_env {
38         const be_chordal_env_t *cenv;
39         const arch_env_t *arch;
40         const arch_register_class_t *cls;
41         ir_graph *irg;
42         struct obstack obst;
43         /** maximum safe register pressure */
44         int registers_available;
45
46         spill_env_t *senv;
47
48         set *loop_attr_set;
49         set *block_attr_set;
50 } morgan_env_t;
51
52 typedef struct loop_edge {
53         ir_node *block;
54         int pos;
55 } loop_edge_t;
56
57 typedef struct loop_attr {
58         const ir_loop *loop;
59         set *out_edges;
60         set *in_edges;
61         /** The set of all values that are live in the loop but not used in the loop */
62         bitset_t *livethrough_unused;
63 } loop_attr_t;
64
65 typedef struct block_attr {
66         const ir_node *block;
67         /** set of all values that are live in the block but not used in the block */
68         bitset_t *livethrough_unused;
69 } block_attr_t;
70
71 //---------------------------------------------------------------------------
72
73 static int loop_edge_cmp(const void* p1, const void* p2, size_t s) {
74         loop_edge_t *e1 = (loop_edge_t*) p1;
75         loop_edge_t *e2 = (loop_edge_t*) p2;
76
77         return e1->block != e2->block || e1->pos != e2->pos;
78 }
79
80 static int loop_attr_cmp(const void *e1, const void *e2, size_t s) {
81         loop_attr_t *la1 = (loop_attr_t*) e1;
82         loop_attr_t *la2 = (loop_attr_t*) e2;
83
84         return la1->loop != la2->loop;
85 }
86
87 static int block_attr_cmp(const void *e1, const void *e2, size_t s) {
88         block_attr_t *b1 = (block_attr_t*) e1;
89         block_attr_t *b2 = (block_attr_t*) e2;
90
91         return b1->block != b2->block;
92 }
93
94 static INLINE int loop_attr_hash(const loop_attr_t *a) {
95 #ifdef DEBUG_libfirm
96         return a->loop->loop_nr;
97 #else
98         return HASH_PTR(a->loop);
99 #endif
100 }
101
102 static INLINE int block_attr_hash(const block_attr_t *b) {
103         return nodeset_hash(b->block);
104 }
105
106 static INLINE int loop_edge_hash(const loop_edge_t *e) {
107         return nodeset_hash(e->block) ^ (e->pos * 31);
108 }
109
110 static INLINE loop_attr_t *get_loop_attr(morgan_env_t *env, const ir_loop *loop) {
111         loop_attr_t l_attr, *res;
112         int hash;
113         l_attr.loop = loop;
114
115         hash = loop_attr_hash(&l_attr);
116         res = set_find(env->loop_attr_set, &l_attr, sizeof(l_attr), hash);
117
118         // create new loop_attr if none exists yet
119         if (res == NULL) {
120                 l_attr.out_edges = new_set(loop_edge_cmp, 1);
121                 l_attr.in_edges = new_set(loop_edge_cmp, 1);
122                 l_attr.livethrough_unused = bitset_obstack_alloc(&env->obst, get_irg_last_idx(env->irg));
123                 res = set_insert(env->loop_attr_set, &l_attr, sizeof(l_attr), hash);
124         }
125
126         return res;
127 }
128
129 static INLINE block_attr_t *get_block_attr(morgan_env_t *env, const ir_node *block) {
130         block_attr_t b_attr, *res;
131         int hash;
132         b_attr.block = block;
133
134         hash = block_attr_hash(&b_attr);
135         res = set_find(env->block_attr_set, &b_attr, sizeof(b_attr), hash);
136
137         if(res == NULL) {
138                 b_attr.livethrough_unused = NULL;
139                 res = set_insert(env->block_attr_set, &b_attr, sizeof(b_attr), hash);
140         }
141
142         return res;
143 }
144
145 //---------------------------------------------------------------------------
146
147 static INLINE int consider_for_spilling(const arch_env_t *env, const arch_register_class_t *cls, const ir_node *node) {
148         if(!arch_irn_has_reg_class(env, node, -1, cls))
149                 return 0;
150
151         return !(arch_irn_get_flags(env, node) & (arch_irn_flags_ignore | arch_irn_flags_dont_spill));
152 }
153
154 /**
155  * Determine edges going out of a loop (= edges that go to a block that is not
156  * inside the loop or one of its subloops)
157  */
158 static INLINE void construct_loop_edges(ir_node *block, void *data) {
159         morgan_env_t *env = data;
160         int n_cfgpreds = get_Block_n_cfgpreds(block);
161         int i;
162         ir_loop* loop = get_irn_loop(block);
163         DBG((dbg, DBG_LOOPANA, "Loop for %+F: %d (depth %d)\n", block, loop->loop_nr, loop->depth));
164
165         for(i = 0; i < n_cfgpreds; ++i) {
166                 loop_edge_t edge;
167                 int hash;
168                 ir_node* cfgpred = get_Block_cfgpred(block, i);
169                 ir_node* cfgpred_block = get_nodes_block(cfgpred);
170                 ir_loop* cfgpred_loop = get_irn_loop(cfgpred_block);
171
172                 if(cfgpred_loop == loop)
173                         continue;
174
175                 assert(get_loop_depth(cfgpred_loop) != get_loop_depth(loop));
176
177                 edge.block = block;
178                 edge.pos = i;
179                 hash = loop_edge_hash(&edge);
180
181                 // edge out of a loop?
182                 if(get_loop_depth(cfgpred_loop) > get_loop_depth(loop)) {
183                         ir_loop *l;
184
185                         DBG((dbg, DBG_LOOPANA, "Loop out edge from %+F (loop %d) to %+F (loop %d)\n", block, get_loop_loop_nr(loop),
186                              cfgpred_block, get_loop_loop_nr(cfgpred_loop)));
187
188                         /* this might be a jump out of multiple loops, so add this to all
189                      * needed outedge sets */
190                         l = cfgpred_loop;
191                         do {
192                                 loop_attr_t *l_attr = get_loop_attr(env, l);
193                                 set_insert(l_attr->out_edges, &edge, sizeof(edge), hash);
194
195                                 l = get_loop_outer_loop(l);
196                                 assert(l != NULL);
197                         } while(l != loop);
198                 } else {
199                         ir_loop *l;
200
201                         // edge into a loop
202                         DBG((dbg, DBG_LOOPANA, "Loop in edge from %+F (loop %d) to %+F (loop %d)\n", block, get_loop_loop_nr(loop),
203                              cfgpred_block, get_loop_loop_nr(cfgpred_loop)));
204
205                         l = loop;
206                         do {
207                                 loop_attr_t *l_attr = get_loop_attr(env, l);
208                                 set_insert(l_attr->in_edges, &edge, sizeof(edge), hash);
209
210                                 l = get_loop_outer_loop(l);
211                         } while(l != cfgpred_loop);
212                 }
213         }
214 }
215
216 static void free_loop_edges(morgan_env_t *env) {
217         loop_attr_t *l_attr;
218
219         for(l_attr = set_first(env->loop_attr_set); l_attr != NULL; l_attr = set_next(env->loop_attr_set)) {
220                 del_set(l_attr->out_edges);
221                 del_set(l_attr->in_edges);
222         }
223 }
224
225 #if 0
226 /**
227  * Debugging help, shows all nodes in a (node-)bitset
228  */
229 static void show_nodebitset(ir_graph* irg, const bitset_t* bitset) {
230         int i;
231
232         bitset_foreach(bitset, i) {
233                 ir_node* node = get_idx_irn(irg, i);
234                 ir_fprintf(stderr, " %+F", node);
235         }
236         fprintf(stderr, "\n");
237 }
238 #endif
239
240 static INLINE void init_livethrough_unuseds(block_attr_t *attr, morgan_env_t *env) {
241         const ir_node *block;
242         int i;
243         be_lv_t *lv = env->cenv->birg->lv;
244
245         if(attr->livethrough_unused != NULL)
246                 return;
247
248         block = attr->block;
249
250         attr->livethrough_unused = bitset_obstack_alloc(&env->obst, get_irg_last_idx(env->irg));
251
252         // copy all live-outs into the livethrough_unused set
253         be_lv_foreach(lv, block, be_lv_state_in | be_lv_state_out, i) {
254                 ir_node *irn = be_lv_get_irn(lv, block, i);
255                 int node_idx;
256
257                 if(!consider_for_spilling(env->arch, env->cls, irn))
258                         continue;
259
260                 node_idx = get_irn_idx(irn);
261                 bitset_set(attr->livethrough_unused, node_idx);
262         }
263 }
264
265 /**
266  * Construct the livethrough unused set for a block
267  */
268 static void construct_block_livethrough_unused(ir_node *block, void *data) {
269         morgan_env_t* env = data;
270         block_attr_t *block_attr = get_block_attr(env, block);
271         ir_node *node;
272         int n_cfgpreds;
273         block_attr_t **pred_attrs = NULL;
274         int i;
275
276         init_livethrough_unuseds(block_attr, env);
277
278         DBG((dbg, DBG_LIVE, "Processing block %d\n", get_irn_node_nr(block)));
279
280         n_cfgpreds = get_Block_n_cfgpreds(block);
281         if(n_cfgpreds > 1) {
282                 pred_attrs = alloca(sizeof(pred_attrs[0]) * n_cfgpreds);
283                 for(i = 0; i < n_cfgpreds; ++i) {
284                         ir_node *pred_block = get_Block_cfgpred_block(block, i);
285                         pred_attrs[i] = get_block_attr(env, pred_block);
286                         init_livethrough_unuseds(pred_attrs[i], env);
287                 }
288         }
289
290         /*
291          * All values that are used within the block are not unused (and therefore not
292          * livethrough_unused)
293          */
294         sched_foreach(block, node) {
295                 int i, arity;
296
297                 // phis are really uses in the pred block
298                 if(is_Phi(node)) {
299                         int j;
300                         for(j = 0; j < n_cfgpreds; ++j) {
301                                 ir_node *used_value = get_Phi_pred(node, j);
302                                 int idx = get_irn_idx(used_value);
303                                 block_attr_t *pred_attr = pred_attrs[j];
304
305                                 bitset_clear(pred_attr->livethrough_unused, idx);
306                         }
307                 } else {
308                         // mark all used values as used
309                         for(i = 0, arity = get_irn_arity(node); i < arity; ++i) {
310                                 int idx = get_irn_idx(get_irn_n(node, i));
311                                 bitset_clear(block_attr->livethrough_unused, idx);
312                         }
313                 }
314         }
315 }
316
317 /**
318  * Construct the livethrough unused set for a loop (and all its subloops+blocks)
319  */
320 static bitset_t *construct_loop_livethrough_unused(morgan_env_t *env, const ir_loop *loop) {
321         int i;
322         loop_attr_t* loop_attr = get_loop_attr(env, loop);
323
324         DBG((dbg, DBG_LIVE, "Processing Loop %d\n", loop->loop_nr));
325         assert(get_loop_n_elements(loop) > 0);
326         for(i = 0; i < get_loop_n_elements(loop); ++i) {
327                 loop_element elem = get_loop_element(loop, i);
328                 switch (*elem.kind) {
329                 case k_ir_node: {
330                         ir_node *block = elem.node;
331                         block_attr_t *block_attr = get_block_attr(env, block);
332                         bitset_t *livethrough_block_unused = block_attr->livethrough_unused;
333
334                         assert(is_Block(elem.node));
335                         assert(livethrough_block_unused != NULL);
336
337                         if(i == 0) {
338                                 bitset_copy(loop_attr->livethrough_unused, livethrough_block_unused);
339                         } else {
340                                 bitset_and(loop_attr->livethrough_unused, livethrough_block_unused);
341                         }
342                         break;
343                 }
344                 case k_ir_loop: {
345                         bitset_t *livethrough_son_unused;
346
347                         livethrough_son_unused = construct_loop_livethrough_unused(env, elem.son);
348                         if(i == 0) {
349                                 bitset_copy(loop_attr->livethrough_unused, livethrough_son_unused);
350                         } else {
351                                 bitset_and(loop_attr->livethrough_unused, livethrough_son_unused);
352                         }
353                         break;
354                 }
355             default:
356                         assert(0);
357                         break;
358                 }
359     }
360         DBG((dbg, DBG_LIVE, "Done with loop %d\n", loop->loop_nr));
361
362         // remove all unused livethroughs that are remembered for this loop from child loops and blocks
363         for(i = 0; i < get_loop_n_elements(loop); ++i) {
364                 const loop_element elem = get_loop_element(loop, i);
365
366                 if(*elem.kind == k_ir_loop) {
367                         loop_attr_t *son_attr = get_loop_attr(env, elem.son);
368                         bitset_andnot(son_attr->livethrough_unused, loop_attr->livethrough_unused);
369
370                         DBG((dbg, DBG_LIVE, "Livethroughs for loop %d:\n", loop->loop_nr));
371                 } else if(*elem.kind == k_ir_node) {
372                         block_attr_t *block_attr = get_block_attr(env, elem.node);
373                         bitset_andnot(block_attr->livethrough_unused, loop_attr->livethrough_unused);
374
375                         DBG((dbg, DBG_LIVE, "Livethroughs for block %+F\n", elem.node));
376                 } else {
377                         assert(0);
378                 }
379         }
380
381         return loop_attr->livethrough_unused;
382 }
383
384 /*---------------------------------------------------------------------------*/
385
386 typedef struct _spillcandidate_t {
387         ir_node *node;
388         int cost;
389 } spillcandidate_t;
390
391 static int compare_spillcandidates(const void *d1, const void *d2) {
392         const spillcandidate_t *cand1 = d1;
393         const spillcandidate_t *cand2 = d2;
394
395         return cand1->cost - cand2->cost;
396 }
397
398 static void spill_values(morgan_env_t *env, const loop_attr_t *loop_attr, int spills) {
399         const bitset_t *cand_bitset = loop_attr->livethrough_unused;
400         int candidatecount = bitset_popcnt(cand_bitset);
401         spillcandidate_t *candidates;
402         int i, c;
403         loop_edge_t *edge;
404
405         assert(spills <= candidatecount);
406
407         candidates = alloca(sizeof(candidates[0]) * candidatecount);
408
409         DBG((dbg, DBG_CHOOSE, "Candidates for loop %d\n", get_loop_loop_nr(loop_attr->loop)));
410         // build candidiatelist
411         c = 0;
412         bitset_foreach(cand_bitset, i) {
413                 ir_node *node = get_idx_irn(env->irg, i);
414                 candidates[c].node = node;
415                 candidates[c].cost = 0;
416
417                 for(edge = set_first(loop_attr->out_edges); edge != NULL; edge = set_next(loop_attr->out_edges)) {
418                         candidates[c].cost += be_get_reload_costs_on_edge(env->senv, node, edge->block, edge->pos);
419                 }
420                 DBG((dbg, DBG_CHOOSE, "%+F has costs %d\n", node, candidates[c].cost));
421
422                 c++;
423         }
424         assert(c == candidatecount);
425
426         // sort list
427         qsort(candidates, candidatecount, sizeof(candidates[0]), compare_spillcandidates);
428
429         // spill values
430         for(i = 0; i < spills; ++i) {
431                 ir_node *to_spill = candidates[i].node;
432                 DBG((dbg, DBG_CHOOSE, "Spilling %+F ", to_spill));
433
434                 for(edge = set_first(loop_attr->out_edges); edge != NULL; edge = set_next(loop_attr->out_edges)) {
435                         be_add_reload_on_edge(env->senv, to_spill, edge->block, edge->pos, env->cls);
436                 }
437         }
438 }
439
440 static int reduce_register_pressure_in_block(morgan_env_t *env, const ir_node* block, int loop_unused_spills_possible) {
441         ir_node *node;
442         int max_pressure;
443         int loop_unused_spills_needed;
444         pset *live_nodes = pset_new_ptr_default();
445         be_lv_t *lv = env->cenv->birg->lv;
446
447         be_liveness_end_of_block(lv, env->arch, env->cls, block, live_nodes);
448         max_pressure = pset_count(live_nodes);
449
450         DBG((dbg, DBG_LIVE, "Reduce pressure to %d In Block %+F:\n", env->registers_available, block));
451
452         /**
453          * Determine register pressure in block
454          */
455         sched_foreach_reverse(block, node) {
456                 int pressure;
457
458                 if(is_Phi(node))
459                         break;
460
461                 be_liveness_transfer(env->arch, env->cls, node, live_nodes);
462                 pressure = pset_count(live_nodes);
463                 if(pressure > max_pressure)
464                         max_pressure = pressure;
465         }
466         del_pset(live_nodes);
467
468         loop_unused_spills_needed = max_pressure - env->registers_available;
469
470         if(loop_unused_spills_needed < 0) {
471                 loop_unused_spills_needed = 0;
472         } else if(loop_unused_spills_needed > loop_unused_spills_possible) {
473                 loop_unused_spills_needed = loop_unused_spills_possible;
474         }
475
476         DBG((dbg, DBG_PRESSURE, "Block %+F: max-pressure %d spills possible: %d spills used: %d\n",
477                  block, max_pressure, loop_unused_spills_possible, loop_unused_spills_needed));
478         return loop_unused_spills_needed;
479 }
480
481 /**
482  * Reduce register pressure in a loop
483  *
484  * @param unused_spills_possible        Number of spills from livethrough_unused variables possible in outer loops
485  * @return                                                      Number of spills of livethrough_unused variables needed in outer loops
486  */
487 static int reduce_register_pressure_in_loop(morgan_env_t *env, const ir_loop *loop, int outer_spills_possible) {
488         int i;
489         loop_attr_t* loop_attr = get_loop_attr(env, loop);
490         int spills_needed = 0;
491         int spills_possible = outer_spills_possible + bitset_popcnt(loop_attr->livethrough_unused);
492         int outer_spills_needed;
493
494         DBG((dbg, DBG_PRESSURE, "Reducing Pressure in loop %d\n", loop->loop_nr));
495         for(i = 0; i < get_loop_n_elements(loop); ++i) {
496                 loop_element elem = get_loop_element(loop, i);
497                 switch (*elem.kind) {
498                 case k_ir_node: {
499                         int needed;
500                         assert(is_Block(elem.node));
501                         needed = reduce_register_pressure_in_block(env, elem.node, spills_possible);
502                         assert(needed >= 0);
503                         assert(needed <= spills_possible);
504                         if(needed > spills_needed)
505                                 spills_needed = needed;
506                         break;
507                 }
508                 case k_ir_loop: {
509                         int needed = reduce_register_pressure_in_loop(env, elem.son, spills_possible);
510                         assert(needed >= 0);
511                         assert(needed <= spills_possible);
512                         if(needed > spills_needed)
513                                 spills_needed = needed;
514                         break;
515                 }
516             default:
517                         assert(0);
518                         break;
519                 }
520     }
521
522         /* calculate number of spills needed in outer loop and spill
523          * unused livethrough nodes around this loop */
524         if(spills_needed > outer_spills_possible) {
525                 int spills_to_place;
526                 outer_spills_needed = outer_spills_possible;
527                 spills_needed -= outer_spills_possible;
528
529                 spills_to_place = spills_needed;
530
531                 DBG((dbg, DBG_SPILLS, "%d values unused in loop %d, spilling %d\n",
532                  spills_possible - outer_spills_possible, loop->loop_nr, spills_to_place));
533
534                 spill_values(env, loop_attr, spills_to_place);
535         } else {
536                 outer_spills_needed = spills_needed;
537         }
538
539         return outer_spills_needed;
540 }
541
542 void be_spill_morgan(be_chordal_env_t *chordal_env) {
543         ir_graph *irg = chordal_env->irg;
544         morgan_env_t env;
545
546         FIRM_DBG_REGISTER(dbg, "ir.be.spillmorgan");
547         //firm_dbg_set_mask(dbg, DBG_SPILLS | DBG_LOOPANA);
548
549         env.cenv = chordal_env;
550         env.arch = chordal_env->birg->main_env->arch_env;
551         env.irg = chordal_env->irg;
552         env.cls = chordal_env->cls;
553         env.senv = be_new_spill_env(chordal_env);
554         DEBUG_ONLY(be_set_spill_env_dbg_module(env.senv, dbg);)
555
556         obstack_init(&env.obst);
557
558         env.registers_available = env.cls->n_regs - be_put_ignore_regs(chordal_env->birg, env.cls, NULL);
559
560         env.loop_attr_set = new_set(loop_attr_cmp, 5);
561         env.block_attr_set = new_set(block_attr_cmp, 20);
562
563         /*-- Part1: Analysis --*/
564         //Matze: I hope liveness information is up to date at this point...
565         //be_liveness_recompute(chordal_env->lv);
566
567         /* construct control flow loop tree */
568         if(! (get_irg_loopinfo_state(irg) & loopinfo_cf_consistent)) {
569                 construct_cf_backedges(irg);
570         }
571
572         /* construct loop out edges and livethrough_unused sets for loops and blocks */
573         irg_block_walk_graph(irg, construct_block_livethrough_unused, construct_loop_edges, &env);
574         construct_loop_livethrough_unused(&env, get_irg_loop(irg));
575
576         /*-- Part2: Transformation --*/
577
578         /* spill unused livethrough values around loops and blocks where
579          * the pressure is too high
580          */
581         reduce_register_pressure_in_loop(&env, get_irg_loop(irg), 0);
582
583         /* Insert real spill/reload nodes and fix usages */
584         be_insert_spills_reloads(env.senv);
585
586         /* Verify the result */
587         if (chordal_env->opts->vrfy_option == BE_CH_VRFY_WARN) {
588                 be_verify_schedule(irg);
589         } else if (chordal_env->opts->vrfy_option == BE_CH_VRFY_ASSERT) {
590                 assert(be_verify_schedule(irg));
591         }
592
593         if (chordal_env->opts->dump_flags & BE_CH_DUMP_SPILL)
594                 be_dump(irg, "-spillmorgan", dump_ir_block_graph_sched);
595
596         /* cleanup */
597         free_loop_edges(&env);
598         del_set(env.loop_attr_set);
599         del_set(env.block_attr_set);
600
601         /* fix the remaining places with too high register pressure with beladies algorithm */
602         be_spill_belady_spill_env(chordal_env, env.senv);
603
604         be_delete_spill_env(env.senv);
605         obstack_free(&env.obst, NULL);
606 }