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 *tmp_colors; /**< An auxiliary bitset which is as long as the number of colors in the class. */
51 bitset_t *colors; /**< The color mask. */
52 } be_chordal_alloc_env_t;
54 static int get_next_free_reg(be_chordal_alloc_env_t const *const alloc_env, bitset_t *const colors)
56 bitset_t *tmp = alloc_env->tmp_colors;
57 bitset_copy(tmp, colors);
59 bitset_and(tmp, alloc_env->chordal_env->allocatable_regs);
60 return bitset_next_set(tmp, 0);
63 static bitset_t const *get_decisive_partner_regs(be_operand_t const *const o1)
65 be_operand_t const *const o2 = o1->partner;
66 assert(!o2 || o1->req->cls == o2->req->cls);
68 if (!o2 || bitset_contains(o1->regs, o2->regs)) {
70 } else if (bitset_contains(o2->regs, o1->regs)) {
77 static void pair_up_operands(be_chordal_env_t const *const env, be_insn_t *const insn)
79 /* For each out operand, try to find an in operand which can be assigned the
80 * same register as the out operand. */
81 int const n_regs = env->cls->n_regs;
82 bitset_t *const bs = bitset_alloca(n_regs);
83 be_lv_t *const lv = be_get_irg_liveness(env->irg);
84 for (int j = 0; j < insn->use_start; ++j) {
85 /* Try to find an in operand which has ... */
86 be_operand_t *smallest = NULL;
87 int smallest_n_regs = n_regs + 1;
88 be_operand_t *const out_op = &insn->ops[j];
89 for (int i = insn->use_start; i < insn->n_ops; ++i) {
90 be_operand_t *const op = &insn->ops[i];
91 if (op->partner || be_values_interfere(lv, op->irn, op->carrier))
94 bitset_copy(bs, op->regs);
95 bitset_and(bs, out_op->regs);
96 int const n_total = bitset_popcount(op->regs);
97 if (!bitset_is_empty(bs) && n_total < smallest_n_regs) {
99 smallest_n_regs = n_total;
103 if (smallest != NULL) {
104 for (int i = insn->use_start; i < insn->n_ops; ++i) {
105 if (insn->ops[i].carrier == smallest->carrier)
106 insn->ops[i].partner = out_op;
109 out_op->partner = smallest;
110 smallest->partner = out_op;
115 static bool list_contains_irn(ir_node *const *const list, size_t const n, ir_node *const irn)
117 for (ir_node *const *i = list; i != list + n; ++i) {
124 static void handle_constraints(be_chordal_alloc_env_t *const alloc_env, ir_node *const irn)
126 be_chordal_env_t *const env = alloc_env->chordal_env;
127 void *const base = obstack_base(env->obst);
128 be_insn_t *insn = be_scan_insn(env, irn);
130 /* Perms inserted before the constraint handling phase are considered to be
131 * correctly precolored. These Perms arise during the ABI handling phase. */
132 if (!insn->has_constraints || is_Phi(irn))
135 /* Prepare the constraint handling of this node.
136 * Perms are constructed and Copies are created for constrained values
137 * interfering with the instruction. */
138 ir_node *const perm = pre_process_constraints(env, &insn);
140 /* find suitable in operands to the out operands of the node. */
141 pair_up_operands(env, insn);
143 /* Look at the in/out operands and add each operand (and its possible partner)
144 * to a bipartite graph (left: nodes with partners, right: admissible colors). */
146 int const n_regs = env->cls->n_regs;
147 ir_node **const alloc_nodes = ALLOCAN(ir_node*, n_regs);
148 pmap *const partners = pmap_create();
150 hungarian_problem_t *const bp = hungarian_new(n_regs, n_regs, HUNGARIAN_MATCH_PERFECT);
152 bipartite_t *const bp = bipartite_new(n_regs, n_regs);
154 for (int i = 0; i < insn->n_ops; ++i) {
155 /* If the operand has no partner or the partner has not been marked
156 * for allocation, determine the admissible registers and mark it
157 * for allocation by associating the node and its partner with the
158 * set of admissible registers via a bipartite graph. */
159 be_operand_t *const op = &insn->ops[i];
160 if (op->partner && pmap_contains(partners, op->partner->carrier))
163 ir_node *const partner = op->partner ? op->partner->carrier : NULL;
164 pmap_insert(partners, op->carrier, partner);
166 pmap_insert(partners, partner, op->carrier);
168 /* Don't insert a node twice. */
169 if (list_contains_irn(alloc_nodes, n_alloc, op->carrier))
172 alloc_nodes[n_alloc] = op->carrier;
174 DBG((dbg, LEVEL_2, "\tassociating %+F and %+F\n", op->carrier, partner));
176 bitset_t const *const bs = get_decisive_partner_regs(op);
178 DBG((dbg, LEVEL_2, "\tallowed registers for %+F: %B\n", op->carrier, bs));
180 bitset_foreach(bs, col) {
182 hungarian_add(bp, n_alloc, col, 1);
184 bipartite_add(bp, n_alloc, col);
188 DBG((dbg, LEVEL_2, "\tallowed registers for %+F: none\n", op->carrier));
194 /* Put all nodes which live through the constrained instruction also to the
195 * allocation bipartite graph. They are considered unconstrained. */
197 be_lv_t *const lv = be_get_irg_liveness(env->irg);
198 foreach_out_edge(perm, edge) {
199 ir_node *const proj = get_edge_src_irn(edge);
200 assert(is_Proj(proj));
202 if (!be_values_interfere(lv, proj, irn) || pmap_contains(partners, proj))
205 /* Don't insert a node twice. */
206 if (list_contains_irn(alloc_nodes, n_alloc, proj))
209 assert(n_alloc < n_regs);
211 alloc_nodes[n_alloc] = proj;
212 pmap_insert(partners, proj, NULL);
214 bitset_foreach(env->allocatable_regs, col) {
216 hungarian_add(bp, n_alloc, col, 1);
218 bipartite_add(bp, n_alloc, col);
226 /* Compute a valid register allocation. */
227 int *const assignment = ALLOCAN(int, n_regs);
229 hungarian_prepare_cost_matrix(bp, HUNGARIAN_MODE_MAXIMIZE_UTIL);
230 int const match_res = hungarian_solve(bp, assignment, NULL, 1);
231 assert(match_res == 0 && "matching failed");
233 bipartite_matching(bp, assignment);
236 /* Assign colors obtained from the matching. */
237 for (int i = 0; i < n_alloc; ++i) {
238 assert(assignment[i] >= 0 && "there must have been a register assigned (node not register pressure faithful?)");
239 arch_register_t const *const reg = arch_register_for_index(env->cls, assignment[i]);
241 ir_node *const irn = alloc_nodes[i];
243 arch_set_irn_register(irn, reg);
244 DBG((dbg, LEVEL_2, "\tsetting %+F to register %s\n", irn, reg->name));
247 ir_node *const partner = pmap_get(ir_node, partners, alloc_nodes[i]);
248 if (partner != NULL) {
249 arch_set_irn_register(partner, reg);
250 DBG((dbg, LEVEL_2, "\tsetting %+F to register %s\n", partner, reg->name));
254 /* Allocate the non-constrained Projs of the Perm. */
256 bitset_t *const bs = bitset_alloca(n_regs);
258 /* Put the colors of all Projs in a bitset. */
259 foreach_out_edge(perm, edge) {
260 ir_node *const proj = get_edge_src_irn(edge);
261 arch_register_t const *const reg = arch_get_irn_register(proj);
263 bitset_set(bs, reg->index);
266 /* Assign the not yet assigned Projs of the Perm a suitable color. */
267 foreach_out_edge(perm, edge) {
268 ir_node *const proj = get_edge_src_irn(edge);
269 arch_register_t const *const reg = arch_get_irn_register(proj);
271 DBG((dbg, LEVEL_2, "\tchecking reg of %+F: %s\n", proj, reg ? reg->name : "<none>"));
274 size_t const col = get_next_free_reg(alloc_env, bs);
275 arch_register_t const *const new_reg = arch_register_for_index(env->cls, col);
276 bitset_set(bs, new_reg->index);
277 arch_set_irn_register(proj, new_reg);
278 DBG((dbg, LEVEL_2, "\tsetting %+F to register %s\n", proj, new_reg->name));
288 pmap_destroy(partners);
291 obstack_free(env->obst, base);
295 * Handle constraint nodes in each basic block.
296 * handle_constraints() inserts Perm nodes which perm
297 * over all values live at the constrained node right in front
298 * of the constrained node. These Perms signal a constrained node.
299 * For further comments, refer to handle_constraints().
301 static void constraints(ir_node *const bl, void *const data)
303 be_chordal_alloc_env_t *const env = (be_chordal_alloc_env_t*)data;
304 for (ir_node *irn = sched_first(bl); !sched_is_end(irn);) {
305 ir_node *const next = sched_next(irn);
306 handle_constraints(env, irn);
311 static void assign(ir_node *const block, void *const env_ptr)
313 be_chordal_alloc_env_t *const alloc_env = (be_chordal_alloc_env_t*)env_ptr;
314 be_chordal_env_t *const env = alloc_env->chordal_env;
315 bitset_t *const colors = alloc_env->colors;
316 struct list_head *const head = get_block_border_head(env, block);
317 be_lv_t *const lv = be_get_irg_liveness(env->irg);
319 bitset_clear_all(colors);
321 DBG((dbg, LEVEL_4, "Assigning colors for block %+F\n", block));
322 DBG((dbg, LEVEL_4, "\tusedef chain for block\n"));
323 foreach_border_head(head, b) {
324 DBG((dbg, LEVEL_4, "\t%s %+F/%d\n", b->is_def ? "def" : "use",
325 b->irn, get_irn_idx(b->irn)));
328 /* Add initial defs for all values live in.
329 * Since their colors have already been assigned (The dominators were
330 * allocated before), we have to mark their colors as used also. */
331 be_lv_foreach(lv, block, be_lv_state_in, irn) {
332 if (arch_irn_consider_in_reg_alloc(env->cls, irn)) {
333 arch_register_t const *const reg = arch_get_irn_register(irn);
335 assert(reg && "Node must have been assigned a register");
336 DBG((dbg, LEVEL_4, "%+F has reg %s\n", irn, reg->name));
338 /* Mark the color of the live in value as used. */
339 bitset_set(colors, reg->index);
343 /* Mind that the sequence of defs from back to front defines a perfect
344 * elimination order. So, coloring the definitions from first to last
346 foreach_border_head(head, b) {
347 ir_node *const irn = b->irn;
349 /* Assign a color, if it is a local def. Global defs already have a
352 /* Clear the color upon a use. */
353 arch_register_t const *const reg = arch_get_irn_register(irn);
354 assert(reg && "Register must have been assigned");
355 bitset_clear(colors, reg->index);
356 } else if (!be_is_live_in(lv, block, irn)) {
358 arch_register_t const *reg = arch_get_irn_register(irn);
361 assert(!bitset_is_set(colors, col) && "pre-colored register must be free");
363 assert(!arch_irn_is_ignore(irn));
364 col = get_next_free_reg(alloc_env, colors);
365 reg = arch_register_for_index(env->cls, col);
366 arch_set_irn_register(irn, reg);
368 bitset_set(colors, col);
370 DBG((dbg, LEVEL_1, "\tassigning register %s(%d) to %+F\n", reg->name, col, irn));
375 static void be_ra_chordal_color(be_chordal_env_t *const chordal_env)
378 ir_graph *const irg = chordal_env->irg;
379 be_assure_live_sets(irg);
382 arch_register_class_t const *const cls = chordal_env->cls;
383 int const colors_n = arch_register_class_n_regs(cls);
384 be_chordal_alloc_env_t env;
385 env.chordal_env = chordal_env;
386 env.colors = bitset_alloca(colors_n);
387 env.tmp_colors = bitset_alloca(colors_n);
389 be_timer_push(T_SPLIT);
390 if (chordal_env->opts->dump_flags & BE_CH_DUMP_SPLIT) {
391 snprintf(buf, sizeof(buf), "%s-split", cls->name);
392 dump_ir_graph(irg, buf);
394 be_timer_pop(T_SPLIT);
396 be_timer_push(T_CONSTR);
398 /* Handle register targeting constraints */
399 dom_tree_walk_irg(irg, constraints, NULL, &env);
401 if (chordal_env->opts->dump_flags & BE_CH_DUMP_CONSTR) {
402 snprintf(buf, sizeof(buf), "%s-constr", cls->name);
403 dump_ir_graph(irg, buf);
406 be_timer_pop(T_CONSTR);
408 /* First, determine the pressure */
409 dom_tree_walk_irg(irg, create_borders, NULL, chordal_env);
411 /* Assign the colors */
412 dom_tree_walk_irg(irg, assign, NULL, &env);
414 if (chordal_env->opts->dump_flags & BE_CH_DUMP_TREE_INTV) {
415 ir_snprintf(buf, sizeof(buf), "ifg_%s_%F.eps", cls->name, irg);
416 plotter_t *const plotter = new_plotter_ps(buf);
417 draw_interval_tree(&draw_chordal_def_opts, chordal_env, plotter);
418 plotter_free(plotter);
422 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_chordal)
423 void be_init_chordal(void)
425 static be_ra_chordal_coloring_t coloring = {
428 FIRM_DBG_REGISTER(dbg, "firm.be.chordal");
430 be_register_chordal_coloring("default", &coloring);