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 *colors; /**< The color mask. */
51 } be_chordal_alloc_env_t;
53 static int get_next_free_reg(bitset_t *const available)
55 return bitset_next_set(available, 0);
58 static bitset_t const *get_decisive_partner_regs(be_operand_t const *const o1)
60 be_operand_t const *const o2 = o1->partner;
61 assert(!o2 || o1->req->cls == o2->req->cls);
63 if (!o2 || bitset_contains(o1->regs, o2->regs)) {
65 } else if (bitset_contains(o2->regs, o1->regs)) {
72 static void pair_up_operands(be_chordal_env_t const *const env, be_insn_t *const insn)
74 /* For each out operand, try to find an in operand which can be assigned the
75 * same register as the out operand. */
76 int const n_regs = env->cls->n_regs;
77 bitset_t *const bs = bitset_alloca(n_regs);
78 be_lv_t *const lv = be_get_irg_liveness(env->irg);
79 for (int j = 0; j < insn->use_start; ++j) {
80 /* Try to find an in operand which has ... */
81 be_operand_t *smallest = NULL;
82 int smallest_n_regs = n_regs + 1;
83 be_operand_t *const out_op = &insn->ops[j];
84 for (int i = insn->use_start; i < insn->n_ops; ++i) {
85 be_operand_t *const op = &insn->ops[i];
86 if (op->partner || be_values_interfere(lv, op->irn, op->carrier))
89 bitset_copy(bs, op->regs);
90 bitset_and(bs, out_op->regs);
91 int const n_total = bitset_popcount(op->regs);
92 if (!bitset_is_empty(bs) && n_total < smallest_n_regs) {
94 smallest_n_regs = n_total;
98 if (smallest != NULL) {
99 for (int i = insn->use_start; i < insn->n_ops; ++i) {
100 if (insn->ops[i].carrier == smallest->carrier)
101 insn->ops[i].partner = out_op;
104 out_op->partner = smallest;
105 smallest->partner = out_op;
110 static bool list_contains_irn(ir_node *const *const list, size_t const n, ir_node *const irn)
112 for (ir_node *const *i = list; i != list + n; ++i) {
119 static void handle_constraints(be_chordal_env_t *const env, ir_node *const irn)
121 void *const base = obstack_base(env->obst);
122 be_insn_t *insn = be_scan_insn(env, irn);
124 /* Perms inserted before the constraint handling phase are considered to be
125 * correctly precolored. These Perms arise during the ABI handling phase. */
126 if (!insn->has_constraints || is_Phi(irn))
129 /* Prepare the constraint handling of this node.
130 * Perms are constructed and Copies are created for constrained values
131 * interfering with the instruction. */
132 ir_node *const perm = pre_process_constraints(env, &insn);
134 /* find suitable in operands to the out operands of the node. */
135 pair_up_operands(env, insn);
137 /* Look at the in/out operands and add each operand (and its possible partner)
138 * to a bipartite graph (left: nodes with partners, right: admissible colors). */
140 int const n_regs = env->cls->n_regs;
141 ir_node **const alloc_nodes = ALLOCAN(ir_node*, n_regs);
142 pmap *const partners = pmap_create();
144 hungarian_problem_t *const bp = hungarian_new(n_regs, n_regs, HUNGARIAN_MATCH_PERFECT);
146 bipartite_t *const bp = bipartite_new(n_regs, n_regs);
148 for (int i = 0; i < insn->n_ops; ++i) {
149 /* If the operand has no partner or the partner has not been marked
150 * for allocation, determine the admissible registers and mark it
151 * for allocation by associating the node and its partner with the
152 * set of admissible registers via a bipartite graph. */
153 be_operand_t *const op = &insn->ops[i];
154 if (op->partner && pmap_contains(partners, op->partner->carrier))
157 ir_node *const partner = op->partner ? op->partner->carrier : NULL;
158 pmap_insert(partners, op->carrier, partner);
160 pmap_insert(partners, partner, op->carrier);
162 /* Don't insert a node twice. */
163 if (list_contains_irn(alloc_nodes, n_alloc, op->carrier))
166 alloc_nodes[n_alloc] = op->carrier;
168 DBG((dbg, LEVEL_2, "\tassociating %+F and %+F\n", op->carrier, partner));
170 bitset_t const *const bs = get_decisive_partner_regs(op);
172 DBG((dbg, LEVEL_2, "\tallowed registers for %+F: %B\n", op->carrier, bs));
174 bitset_foreach(bs, col) {
176 hungarian_add(bp, n_alloc, col, 1);
178 bipartite_add(bp, n_alloc, col);
182 DBG((dbg, LEVEL_2, "\tallowed registers for %+F: none\n", op->carrier));
188 /* Put all nodes which live through the constrained instruction also to the
189 * allocation bipartite graph. They are considered unconstrained. */
191 be_lv_t *const lv = be_get_irg_liveness(env->irg);
192 foreach_out_edge(perm, edge) {
193 ir_node *const proj = get_edge_src_irn(edge);
194 assert(is_Proj(proj));
196 if (!be_values_interfere(lv, proj, irn) || pmap_contains(partners, proj))
199 /* Don't insert a node twice. */
200 if (list_contains_irn(alloc_nodes, n_alloc, proj))
203 assert(n_alloc < n_regs);
205 alloc_nodes[n_alloc] = proj;
206 pmap_insert(partners, proj, NULL);
208 bitset_foreach(env->allocatable_regs, col) {
210 hungarian_add(bp, n_alloc, col, 1);
212 bipartite_add(bp, n_alloc, col);
220 /* Compute a valid register allocation. */
221 int *const assignment = ALLOCAN(int, n_regs);
223 hungarian_prepare_cost_matrix(bp, HUNGARIAN_MODE_MAXIMIZE_UTIL);
224 int const match_res = hungarian_solve(bp, assignment, NULL, 1);
225 assert(match_res == 0 && "matching failed");
227 bipartite_matching(bp, assignment);
230 /* Assign colors obtained from the matching. */
231 for (int i = 0; i < n_alloc; ++i) {
232 assert(assignment[i] >= 0 && "there must have been a register assigned (node not register pressure faithful?)");
233 arch_register_t const *const reg = arch_register_for_index(env->cls, assignment[i]);
235 ir_node *const irn = alloc_nodes[i];
237 arch_set_irn_register(irn, reg);
238 DBG((dbg, LEVEL_2, "\tsetting %+F to register %s\n", irn, reg->name));
241 ir_node *const partner = pmap_get(ir_node, partners, alloc_nodes[i]);
242 if (partner != NULL) {
243 arch_set_irn_register(partner, reg);
244 DBG((dbg, LEVEL_2, "\tsetting %+F to register %s\n", partner, reg->name));
248 /* Allocate the non-constrained Projs of the Perm. */
250 bitset_t *const available = bitset_alloca(n_regs);
251 bitset_copy(available, env->allocatable_regs);
253 /* Put the colors of all Projs in a bitset. */
254 foreach_out_edge(perm, edge) {
255 ir_node *const proj = get_edge_src_irn(edge);
256 arch_register_t const *const reg = arch_get_irn_register(proj);
258 bitset_clear(available, reg->index);
261 /* Assign the not yet assigned Projs of the Perm a suitable color. */
262 foreach_out_edge(perm, edge) {
263 ir_node *const proj = get_edge_src_irn(edge);
264 arch_register_t const *const reg = arch_get_irn_register(proj);
266 DBG((dbg, LEVEL_2, "\tchecking reg of %+F: %s\n", proj, reg ? reg->name : "<none>"));
269 size_t const col = get_next_free_reg(available);
270 arch_register_t const *const new_reg = arch_register_for_index(env->cls, col);
271 bitset_clear(available, new_reg->index);
272 arch_set_irn_register(proj, new_reg);
273 DBG((dbg, LEVEL_2, "\tsetting %+F to register %s\n", proj, new_reg->name));
283 pmap_destroy(partners);
286 obstack_free(env->obst, base);
290 * Handle constraint nodes in each basic block.
291 * handle_constraints() inserts Perm nodes which perm
292 * over all values live at the constrained node right in front
293 * of the constrained node. These Perms signal a constrained node.
294 * For further comments, refer to handle_constraints().
296 static void constraints(ir_node *const bl, void *const data)
298 be_chordal_env_t *const env = (be_chordal_env_t*)data;
299 for (ir_node *irn = sched_first(bl); !sched_is_end(irn);) {
300 ir_node *const next = sched_next(irn);
301 handle_constraints(env, irn);
306 static void assign(ir_node *const block, void *const env_ptr)
308 be_chordal_alloc_env_t *const alloc_env = (be_chordal_alloc_env_t*)env_ptr;
309 be_chordal_env_t *const env = alloc_env->chordal_env;
310 struct list_head *const head = get_block_border_head(env, block);
311 be_lv_t *const lv = be_get_irg_liveness(env->irg);
313 DBG((dbg, LEVEL_4, "Assigning colors for block %+F\n", block));
314 DBG((dbg, LEVEL_4, "\tusedef chain for block\n"));
315 foreach_border_head(head, b) {
316 DBG((dbg, LEVEL_4, "\t%s %+F/%d\n", b->is_def ? "def" : "use",
317 b->irn, get_irn_idx(b->irn)));
320 bitset_t *const available = alloc_env->colors;
321 bitset_copy(available, env->allocatable_regs);
323 /* Add initial defs for all values live in.
324 * Since their colors have already been assigned (The dominators were
325 * allocated before), we have to mark their colors as used also. */
326 be_lv_foreach(lv, block, be_lv_state_in, irn) {
327 if (arch_irn_consider_in_reg_alloc(env->cls, irn)) {
328 arch_register_t const *const reg = arch_get_irn_register(irn);
330 assert(reg && "Node must have been assigned a register");
331 DBG((dbg, LEVEL_4, "%+F has reg %s\n", irn, reg->name));
333 /* Mark the color of the live in value as used. */
334 bitset_clear(available, reg->index);
338 /* Mind that the sequence of defs from back to front defines a perfect
339 * elimination order. So, coloring the definitions from first to last
341 foreach_border_head(head, b) {
342 ir_node *const irn = b->irn;
344 /* Assign a color, if it is a local def. Global defs already have a
347 /* Make the color available upon a use. */
348 arch_register_t const *const reg = arch_get_irn_register(irn);
349 assert(reg && "Register must have been assigned");
350 bitset_set(available, reg->index);
351 } else if (!be_is_live_in(lv, block, irn)) {
353 arch_register_t const *reg = arch_get_irn_register(irn);
356 assert(bitset_is_set(available, col) && "pre-colored register must be free");
358 assert(!arch_irn_is_ignore(irn));
359 col = get_next_free_reg(available);
360 reg = arch_register_for_index(env->cls, col);
361 arch_set_irn_register(irn, reg);
363 bitset_clear(available, col);
365 DBG((dbg, LEVEL_1, "\tassigning register %s(%d) to %+F\n", reg->name, col, irn));
370 static void be_ra_chordal_color(be_chordal_env_t *const chordal_env)
373 ir_graph *const irg = chordal_env->irg;
374 be_assure_live_sets(irg);
377 arch_register_class_t const *const cls = chordal_env->cls;
378 int const colors_n = arch_register_class_n_regs(cls);
379 be_chordal_alloc_env_t env;
380 env.chordal_env = chordal_env;
381 env.colors = bitset_alloca(colors_n);
383 be_timer_push(T_SPLIT);
384 if (chordal_env->opts->dump_flags & BE_CH_DUMP_SPLIT) {
385 snprintf(buf, sizeof(buf), "%s-split", cls->name);
386 dump_ir_graph(irg, buf);
388 be_timer_pop(T_SPLIT);
390 be_timer_push(T_CONSTR);
392 /* Handle register targeting constraints */
393 dom_tree_walk_irg(irg, constraints, NULL, chordal_env);
395 if (chordal_env->opts->dump_flags & BE_CH_DUMP_CONSTR) {
396 snprintf(buf, sizeof(buf), "%s-constr", cls->name);
397 dump_ir_graph(irg, buf);
400 be_timer_pop(T_CONSTR);
402 /* First, determine the pressure */
403 dom_tree_walk_irg(irg, create_borders, NULL, chordal_env);
405 /* Assign the colors */
406 dom_tree_walk_irg(irg, assign, NULL, &env);
408 if (chordal_env->opts->dump_flags & BE_CH_DUMP_TREE_INTV) {
409 ir_snprintf(buf, sizeof(buf), "ifg_%s_%F.eps", cls->name, irg);
410 plotter_t *const plotter = new_plotter_ps(buf);
411 draw_interval_tree(&draw_chordal_def_opts, chordal_env, plotter);
412 plotter_free(plotter);
416 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_chordal)
417 void be_init_chordal(void)
419 static be_ra_chordal_coloring_t coloring = {
422 FIRM_DBG_REGISTER(dbg, "firm.be.chordal");
424 be_register_chordal_coloring("default", &coloring);