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 * @brief Chordal register allocation.
23 * @author Sebastian Hack
28 #include "bechordal_common.h"
29 #include "bechordal_draw.h"
30 #include "bechordal_t.h"
32 #include "beintlive_t.h"
38 #define USE_HUNGARIAN 0
41 #include "hungarian.h"
43 #include "bipartite.h"
46 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
48 typedef struct be_chordal_alloc_env_t {
49 be_chordal_env_t *chordal_env;
50 bitset_t *live; /**< A liveness bitset. */
51 bitset_t *tmp_colors; /**< An auxiliary bitset which is as long as the number of colors in the class. */
52 bitset_t *colors; /**< The color mask. */
53 } be_chordal_alloc_env_t;
55 static int get_next_free_reg(be_chordal_alloc_env_t const *const alloc_env, bitset_t *const colors)
57 bitset_t *tmp = alloc_env->tmp_colors;
58 bitset_copy(tmp, colors);
60 bitset_and(tmp, alloc_env->chordal_env->allocatable_regs);
61 return bitset_next_set(tmp, 0);
64 static bitset_t const *get_decisive_partner_regs(be_operand_t const *const o1)
66 be_operand_t const *const o2 = o1->partner;
67 assert(!o2 || o1->req->cls == o2->req->cls);
69 if (!o2 || bitset_contains(o1->regs, o2->regs)) {
71 } else if (bitset_contains(o2->regs, o1->regs)) {
78 static void pair_up_operands(be_chordal_env_t const *const env, be_insn_t *const insn)
80 /* For each out operand, try to find an in operand which can be assigned the
81 * same register as the out operand. */
82 int const n_regs = env->cls->n_regs;
83 bitset_t *const bs = bitset_alloca(n_regs);
84 be_lv_t *const lv = be_get_irg_liveness(env->irg);
85 for (int j = 0; j < insn->use_start; ++j) {
86 /* Try to find an in operand which has ... */
87 be_operand_t *smallest = NULL;
88 int smallest_n_regs = n_regs + 1;
89 be_operand_t *const out_op = &insn->ops[j];
90 for (int i = insn->use_start; i < insn->n_ops; ++i) {
91 be_operand_t *const op = &insn->ops[i];
92 if (op->partner || be_values_interfere(lv, op->irn, op->carrier))
95 bitset_copy(bs, op->regs);
96 bitset_and(bs, out_op->regs);
97 int const n_total = bitset_popcount(op->regs);
98 if (!bitset_is_empty(bs) && n_total < smallest_n_regs) {
100 smallest_n_regs = n_total;
104 if (smallest != NULL) {
105 for (int i = insn->use_start; i < insn->n_ops; ++i) {
106 if (insn->ops[i].carrier == smallest->carrier)
107 insn->ops[i].partner = out_op;
110 out_op->partner = smallest;
111 smallest->partner = out_op;
116 static bool list_contains_irn(ir_node *const *const list, size_t const n, ir_node *const irn)
118 for (ir_node *const *i = list; i != list + n; ++i) {
125 static void handle_constraints(be_chordal_alloc_env_t *const alloc_env, ir_node *const irn)
127 be_chordal_env_t *const env = alloc_env->chordal_env;
128 void *const base = obstack_base(env->obst);
129 be_insn_t *insn = be_scan_insn(env, irn);
131 /* Perms inserted before the constraint handling phase are considered to be
132 * correctly precolored. These Perms arise during the ABI handling phase. */
133 if (!insn->has_constraints || is_Phi(irn))
136 /* Prepare the constraint handling of this node.
137 * Perms are constructed and Copies are created for constrained values
138 * interfering with the instruction. */
139 ir_node *const perm = pre_process_constraints(env, &insn);
141 /* find suitable in operands to the out operands of the node. */
142 pair_up_operands(env, insn);
144 /* Look at the in/out operands and add each operand (and its possible partner)
145 * to a bipartite graph (left: nodes with partners, right: admissible colors). */
147 int const n_regs = env->cls->n_regs;
148 ir_node **const alloc_nodes = ALLOCAN(ir_node*, n_regs);
149 pmap *const partners = pmap_create();
151 hungarian_problem_t *const bp = hungarian_new(n_regs, n_regs, HUNGARIAN_MATCH_PERFECT);
153 bipartite_t *const bp = bipartite_new(n_regs, n_regs);
155 for (int i = 0; i < insn->n_ops; ++i) {
156 /* If the operand has no partner or the partner has not been marked
157 * for allocation, determine the admissible registers and mark it
158 * for allocation by associating the node and its partner with the
159 * set of admissible registers via a bipartite graph. */
160 be_operand_t *const op = &insn->ops[i];
161 if (op->partner && pmap_contains(partners, op->partner->carrier))
164 ir_node *const partner = op->partner ? op->partner->carrier : NULL;
165 pmap_insert(partners, op->carrier, partner);
167 pmap_insert(partners, partner, op->carrier);
169 /* Don't insert a node twice. */
170 if (list_contains_irn(alloc_nodes, n_alloc, op->carrier))
173 alloc_nodes[n_alloc] = op->carrier;
175 DBG((dbg, LEVEL_2, "\tassociating %+F and %+F\n", op->carrier, partner));
177 bitset_t const *const bs = get_decisive_partner_regs(op);
179 DBG((dbg, LEVEL_2, "\tallowed registers for %+F: %B\n", op->carrier, bs));
181 bitset_foreach(bs, col) {
183 hungarian_add(bp, n_alloc, col, 1);
185 bipartite_add(bp, n_alloc, col);
189 DBG((dbg, LEVEL_2, "\tallowed registers for %+F: none\n", op->carrier));
195 /* Put all nodes which live through the constrained instruction also to the
196 * allocation bipartite graph. They are considered unconstrained. */
198 be_lv_t *const lv = be_get_irg_liveness(env->irg);
199 foreach_out_edge(perm, edge) {
200 ir_node *const proj = get_edge_src_irn(edge);
201 assert(is_Proj(proj));
203 if (!be_values_interfere(lv, proj, irn) || pmap_contains(partners, proj))
206 /* Don't insert a node twice. */
207 if (list_contains_irn(alloc_nodes, n_alloc, proj))
210 assert(n_alloc < n_regs);
212 alloc_nodes[n_alloc] = proj;
213 pmap_insert(partners, proj, NULL);
215 bitset_foreach(env->allocatable_regs, col) {
217 hungarian_add(bp, n_alloc, col, 1);
219 bipartite_add(bp, n_alloc, col);
227 /* Compute a valid register allocation. */
228 int *const assignment = ALLOCAN(int, n_regs);
230 hungarian_prepare_cost_matrix(bp, HUNGARIAN_MODE_MAXIMIZE_UTIL);
231 int const match_res = hungarian_solve(bp, assignment, NULL, 1);
232 assert(match_res == 0 && "matching failed");
234 bipartite_matching(bp, assignment);
237 /* Assign colors obtained from the matching. */
238 for (int i = 0; i < n_alloc; ++i) {
239 assert(assignment[i] >= 0 && "there must have been a register assigned (node not register pressure faithful?)");
240 arch_register_t const *const reg = arch_register_for_index(env->cls, assignment[i]);
242 ir_node *const irn = alloc_nodes[i];
244 arch_set_irn_register(irn, reg);
245 DBG((dbg, LEVEL_2, "\tsetting %+F to register %s\n", irn, reg->name));
248 ir_node *const partner = pmap_get(ir_node, partners, alloc_nodes[i]);
249 if (partner != NULL) {
250 arch_set_irn_register(partner, reg);
251 DBG((dbg, LEVEL_2, "\tsetting %+F to register %s\n", partner, reg->name));
255 /* Allocate the non-constrained Projs of the Perm. */
257 bitset_t *const bs = bitset_alloca(n_regs);
259 /* Put the colors of all Projs in a bitset. */
260 foreach_out_edge(perm, edge) {
261 ir_node *const proj = get_edge_src_irn(edge);
262 arch_register_t const *const reg = arch_get_irn_register(proj);
264 bitset_set(bs, reg->index);
267 /* Assign the not yet assigned Projs of the Perm a suitable color. */
268 foreach_out_edge(perm, edge) {
269 ir_node *const proj = get_edge_src_irn(edge);
270 arch_register_t const *const reg = arch_get_irn_register(proj);
272 DBG((dbg, LEVEL_2, "\tchecking reg of %+F: %s\n", proj, reg ? reg->name : "<none>"));
275 size_t const col = get_next_free_reg(alloc_env, bs);
276 arch_register_t const *const new_reg = arch_register_for_index(env->cls, col);
277 bitset_set(bs, new_reg->index);
278 arch_set_irn_register(proj, new_reg);
279 DBG((dbg, LEVEL_2, "\tsetting %+F to register %s\n", proj, new_reg->name));
289 pmap_destroy(partners);
292 obstack_free(env->obst, base);
296 * Handle constraint nodes in each basic block.
297 * handle_constraints() inserts Perm nodes which perm
298 * over all values live at the constrained node right in front
299 * of the constrained node. These Perms signal a constrained node.
300 * For further comments, refer to handle_constraints().
302 static void constraints(ir_node *const bl, void *const data)
304 be_chordal_alloc_env_t *const env = (be_chordal_alloc_env_t*)data;
305 for (ir_node *irn = sched_first(bl); !sched_is_end(irn);) {
306 ir_node *const next = sched_next(irn);
307 handle_constraints(env, irn);
312 static void assign(ir_node *const block, void *const env_ptr)
314 be_chordal_alloc_env_t *const alloc_env = (be_chordal_alloc_env_t*)env_ptr;
315 be_chordal_env_t *const env = alloc_env->chordal_env;
316 bitset_t *const live = alloc_env->live;
317 bitset_t *const colors = alloc_env->colors;
318 struct list_head *const head = get_block_border_head(env, block);
319 be_lv_t *const lv = be_get_irg_liveness(env->irg);
321 bitset_clear_all(colors);
322 bitset_clear_all(live);
324 DBG((dbg, LEVEL_4, "Assigning colors for block %+F\n", block));
325 DBG((dbg, LEVEL_4, "\tusedef chain for block\n"));
326 foreach_border_head(head, b) {
327 DBG((dbg, LEVEL_4, "\t%s %+F/%d\n", b->is_def ? "def" : "use",
328 b->irn, get_irn_idx(b->irn)));
331 /* Add initial defs for all values live in.
332 * Since their colors have already been assigned (The dominators were
333 * allocated before), we have to mark their colors as used also. */
334 be_lv_foreach(lv, block, be_lv_state_in, irn) {
335 if (arch_irn_consider_in_reg_alloc(env->cls, irn)) {
336 arch_register_t const *const reg = arch_get_irn_register(irn);
338 assert(reg && "Node must have been assigned a register");
339 DBG((dbg, LEVEL_4, "%+F has reg %s\n", irn, reg->name));
341 /* Mark the color of the live in value as used. */
342 bitset_set(colors, reg->index);
344 /* Mark the value live in. */
345 bitset_set(live, get_irn_idx(irn));
349 /* Mind that the sequence of defs from back to front defines a perfect
350 * elimination order. So, coloring the definitions from first to last
352 foreach_border_head(head, b) {
353 ir_node *const irn = b->irn;
354 int const nr = get_irn_idx(irn);
356 /* Assign a color, if it is a local def. Global defs already have a
359 /* Clear the color upon a use. */
360 arch_register_t const *const reg = arch_get_irn_register(irn);
361 assert(reg && "Register must have been assigned");
362 bitset_clear(colors, reg->index);
363 bitset_clear(live, nr);
364 } else if (!be_is_live_in(lv, block, irn)) {
366 arch_register_t const *reg = arch_get_irn_register(irn);
369 assert(!bitset_is_set(colors, col) && "pre-colored register must be free");
371 assert(!arch_irn_is_ignore(irn));
372 col = get_next_free_reg(alloc_env, colors);
373 reg = arch_register_for_index(env->cls, col);
374 arch_set_irn_register(irn, reg);
376 bitset_set(colors, col);
378 DBG((dbg, LEVEL_1, "\tassigning register %s(%d) to %+F\n", reg->name, col, irn));
380 assert(!bitset_is_set(live, nr) && "Value's definition must not have been encountered");
381 bitset_set(live, nr);
386 static void be_ra_chordal_color(be_chordal_env_t *const chordal_env)
389 ir_graph *const irg = chordal_env->irg;
390 be_assure_live_sets(irg);
393 arch_register_class_t const *const cls = chordal_env->cls;
394 int const colors_n = arch_register_class_n_regs(cls);
395 be_chordal_alloc_env_t env;
396 env.chordal_env = chordal_env;
397 env.colors = bitset_alloca(colors_n);
398 env.tmp_colors = bitset_alloca(colors_n);
400 be_timer_push(T_SPLIT);
401 if (chordal_env->opts->dump_flags & BE_CH_DUMP_SPLIT) {
402 snprintf(buf, sizeof(buf), "%s-split", cls->name);
403 dump_ir_graph(irg, buf);
405 be_timer_pop(T_SPLIT);
407 be_timer_push(T_CONSTR);
409 /* Handle register targeting constraints */
410 dom_tree_walk_irg(irg, constraints, NULL, &env);
412 if (chordal_env->opts->dump_flags & BE_CH_DUMP_CONSTR) {
413 snprintf(buf, sizeof(buf), "%s-constr", cls->name);
414 dump_ir_graph(irg, buf);
417 be_timer_pop(T_CONSTR);
419 env.live = bitset_malloc(get_irg_last_idx(irg));
421 /* First, determine the pressure */
422 dom_tree_walk_irg(irg, create_borders, NULL, chordal_env);
424 /* Assign the colors */
425 dom_tree_walk_irg(irg, assign, NULL, &env);
427 if (chordal_env->opts->dump_flags & BE_CH_DUMP_TREE_INTV) {
428 ir_snprintf(buf, sizeof(buf), "ifg_%s_%F.eps", cls->name, irg);
429 plotter_t *const plotter = new_plotter_ps(buf);
430 draw_interval_tree(&draw_chordal_def_opts, chordal_env, plotter);
431 plotter_free(plotter);
434 bitset_free(env.live);
437 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_chordal)
438 void be_init_chordal(void)
440 static be_ra_chordal_coloring_t coloring = {
443 FIRM_DBG_REGISTER(dbg, "firm.be.chordal");
445 be_register_chordal_coloring("default", &coloring);