2 * liveness.c: liveness analysis
5 * Dietmar Maurer (dietmar@ximian.com)
7 * (C) 2002 Ximian, Inc.
13 //#define DEBUG_LIVENESS
15 extern guint8 mono_burg_arity [];
17 /* mono_bitset_mp_new:
19 * allocates a MonoBitSet inside a memory pool
22 mono_bitset_mp_new (MonoMemPool *mp, guint32 max_size)
24 int size = mono_bitset_alloc_size (max_size, 0);
27 mem = mono_mempool_alloc0 (mp, size);
28 return mono_bitset_mem_new (mem, max_size, MONO_BITSET_DONT_FREE);
31 G_GNUC_UNUSED static void
32 mono_bitset_print (MonoBitSet *set)
37 for (i = 0; i < mono_bitset_size (set); i++) {
39 if (mono_bitset_test (set, i))
47 update_live_range (MonoCompile *cfg, int idx, int block_dfn, int tree_pos)
49 MonoLiveRange *range = &MONO_VARINFO (cfg, idx)->range;
50 guint32 abs_pos = (block_dfn << 16) | tree_pos;
52 if (range->first_use.abs_pos > abs_pos)
53 range->first_use.abs_pos = abs_pos;
55 if (range->last_use.abs_pos < abs_pos)
56 range->last_use.abs_pos = abs_pos;
60 update_gen_kill_set (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *inst, int inst_num)
62 int arity = mono_burg_arity [inst->opcode];
63 int max_vars = cfg->num_varinfo;
66 update_gen_kill_set (cfg, bb, inst->inst_i0, inst_num);
69 update_gen_kill_set (cfg, bb, inst->inst_i1, inst_num);
71 if (inst->ssa_op == MONO_SSA_LOAD) {
72 int idx = inst->inst_i0->inst_c0;
73 MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
74 g_assert (idx < max_vars);
75 if (bb->region != -1) {
77 * Variables used in exception regions can't be allocated to
80 cfg->varinfo [vi->idx]->flags |= MONO_INST_VOLATILE;
82 update_live_range (cfg, idx, bb->dfn, inst_num);
83 if (!mono_bitset_test (bb->kill_set, idx))
84 mono_bitset_set (bb->gen_set, idx);
85 vi->spill_costs += 1 + (bb->nesting * 2);
86 } else if (inst->ssa_op == MONO_SSA_STORE) {
87 int idx = inst->inst_i0->inst_c0;
88 MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
89 g_assert (idx < max_vars);
90 g_assert (inst->inst_i1->opcode != OP_PHI);
91 if (bb->region != -1) {
93 * Variables used in exception regions can't be allocated to
96 cfg->varinfo [vi->idx]->flags |= MONO_INST_VOLATILE;
98 update_live_range (cfg, idx, bb->dfn, inst_num);
99 mono_bitset_set (bb->kill_set, idx);
100 vi->spill_costs += 1 + (bb->nesting * 2);
105 update_volatile (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *inst, int inst_num)
107 int arity = mono_burg_arity [inst->opcode];
108 int max_vars = cfg->num_varinfo;
111 update_volatile (cfg, bb, inst->inst_i0, inst_num);
114 update_volatile (cfg, bb, inst->inst_i1, inst_num);
116 if ((inst->ssa_op == MONO_SSA_LOAD) || (inst->ssa_op == MONO_SSA_STORE)) {
117 int idx = inst->inst_i0->inst_c0;
118 MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
119 g_assert (idx < max_vars);
120 cfg->varinfo [vi->idx]->flags |= MONO_INST_VOLATILE;
125 visit_bb (MonoCompile *cfg, MonoBasicBlock *bb, GSList **visited)
130 if (g_slist_find (*visited, bb))
133 for (tree_num = 0, inst = bb->code; inst; inst = inst->next, tree_num++) {
134 update_volatile (cfg, bb, inst, tree_num);
137 *visited = g_slist_append (*visited, bb);
140 * Need to visit all bblocks reachable from this one since they can be
141 * reached during exception handling.
143 for (i = 0; i < bb->out_count; ++i) {
144 visit_bb (cfg, bb->out_bb [i], visited);
149 handle_exception_clauses (MonoCompile *cfg)
152 GSList *visited = NULL;
155 * Variables in exception handler register cannot be allocated to registers
156 * so make them volatile. See bug #42136. This will not be neccessary when
157 * the back ends could guarantee that the variables will be in the
158 * correct registers when a handler is called.
160 for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
161 if (bb->region == -1)
164 visit_bb (cfg, bb, &visited);
166 g_slist_free (visited);
169 /* generic liveness analysis code. CFG specific parts are
170 * in update_gen_kill_set()
173 mono_analyze_liveness (MonoCompile *cfg)
175 MonoBitSet *old_live_in_set, *old_live_out_set, *tmp_in_set;
177 int i, j, max_vars = cfg->num_varinfo;
178 int iterations, out_iter, in_iter;
179 gboolean *changed_in, *changed_out, *new_changed_in, *in_worklist;
180 MonoBasicBlock **worklist;
181 guint32 l_begin, l_end;
182 static int count = 0;
184 #ifdef DEBUG_LIVENESS
185 printf ("LIVENESS %s\n", mono_method_full_name (cfg->method, TRUE));
188 g_assert (!(cfg->comp_done & MONO_COMP_LIVENESS));
190 cfg->comp_done |= MONO_COMP_LIVENESS;
195 for (i = 0; i < cfg->num_bblocks; ++i) {
196 MonoBasicBlock *bb = cfg->bblocks [i];
198 bb->gen_set = mono_bitset_mp_new (cfg->mempool, max_vars);
199 bb->kill_set = mono_bitset_mp_new (cfg->mempool, max_vars);
200 bb->live_in_set = mono_bitset_mp_new (cfg->mempool, max_vars);
201 bb->live_out_set = mono_bitset_mp_new (cfg->mempool, max_vars);
204 for (i = 0; i < cfg->num_bblocks; ++i) {
205 MonoBasicBlock *bb = cfg->bblocks [i];
209 for (tree_num = 0, inst = bb->code; inst; inst = inst->next, tree_num++) {
210 //mono_print_tree (inst); printf ("\n");
211 update_gen_kill_set (cfg, bb, inst, tree_num);
214 #ifdef DEBUG_LIVENESS
215 printf ("BLOCK BB%d (", bb->block_num);
216 for (j = 0; j < bb->out_count; j++)
217 printf ("BB%d, ", bb->out_bb [j]->block_num);
220 printf ("GEN BB%d: ", bb->block_num); mono_bitset_print (bb->gen_set);
221 printf ("KILL BB%d: ", bb->block_num); mono_bitset_print (bb->kill_set);
225 old_live_in_set = mono_bitset_new (max_vars, 0);
226 old_live_out_set = mono_bitset_new (max_vars, 0);
227 tmp_in_set = mono_bitset_new (max_vars, 0);
228 changed_in = g_new0 (gboolean, cfg->num_bblocks + 1);
229 changed_out = g_new0 (gboolean, cfg->num_bblocks + 1);
230 in_worklist = g_new0 (gboolean, cfg->num_bblocks + 1);
231 new_changed_in = g_new0 (gboolean, cfg->num_bblocks + 1);
233 for (i = 0; i < cfg->num_bblocks + 1; ++i) {
234 changed_in [i] = TRUE;
235 changed_out [i] = TRUE;
240 worklist = g_new0 (MonoBasicBlock *, cfg->num_bblocks + 1);
244 for (i = cfg->num_bblocks - 1; i >= 0; i--) {
245 MonoBasicBlock *bb = cfg->bblocks [i];
247 worklist [l_end ++] = bb;
248 in_worklist [bb->dfn] = TRUE;
258 while (l_begin != l_end) {
259 MonoBasicBlock *bb = worklist [l_begin ++];
261 in_worklist [bb->dfn] = FALSE;
263 if (l_begin == cfg->num_bblocks + 1)
266 if (bb->out_count > 0) {
268 mono_bitset_copyto (bb->live_out_set, old_live_out_set);
270 for (j = 0; j < bb->out_count; j++) {
271 MonoBasicBlock *out_bb = bb->out_bb [j];
273 mono_bitset_copyto (out_bb->live_out_set, tmp_in_set);
274 mono_bitset_sub (tmp_in_set, out_bb->kill_set);
275 mono_bitset_union (tmp_in_set, out_bb->gen_set);
277 mono_bitset_union (bb->live_out_set, tmp_in_set);
281 changed_out [bb->dfn] = !mono_bitset_equal (old_live_out_set, bb->live_out_set);
282 if (changed_out [bb->dfn]) {
283 for (j = 0; j < bb->in_count; j++) {
284 MonoBasicBlock *in_bb = bb->in_bb [j];
286 * Some basic blocks do not seem to be in the
287 * cfg->bblocks array...
289 if (in_bb->live_in_set)
290 if (!in_worklist [in_bb->dfn]) {
291 worklist [l_end ++] = in_bb;
292 if (l_end == cfg->num_bblocks + 1)
294 in_worklist [in_bb->dfn] = TRUE;
304 //printf ("IT: %d %d %d.\n", iterations, in_iter, out_iter);
306 mono_bitset_free (old_live_in_set);
307 mono_bitset_free (old_live_out_set);
308 mono_bitset_free (tmp_in_set);
311 g_free (changed_out);
312 g_free (new_changed_in);
314 g_free (in_worklist);
316 for (i = cfg->num_bblocks - 1; i >= 0; i--) {
317 MonoBasicBlock *bb = cfg->bblocks [i];
319 mono_bitset_copyto (bb->live_out_set, bb->live_in_set);
320 mono_bitset_sub (bb->live_in_set, bb->kill_set);
321 mono_bitset_union (bb->live_in_set, bb->gen_set);
325 * This code can be slow for large methods so inline the calls to
328 for (i = 0; i < cfg->num_bblocks; ++i) {
329 MonoBasicBlock *bb = cfg->bblocks [i];
333 for (j = 0; j < (max_vars / 32) + 1; ++j) {
338 if (j > (max_vars / 32))
341 if (j == (max_vars / 32))
346 bits_in = mono_bitset_test_bulk (bb->live_in_set, j * 32);
347 bits_out = mono_bitset_test_bulk (bb->live_out_set, j * 32);
348 for (k = 0; k < nbits; ++k) {
349 if (bits_in & (1 << k))
350 update_live_range (cfg, (j * 32) + k, bb->dfn, 0);
351 if (bits_out & (1 << k))
352 update_live_range (cfg, (j * 32) + k, bb->dfn, 0xffff);
357 handle_exception_clauses (cfg);
359 #ifdef DEBUG_LIVENESS
360 for (i = cfg->num_bblocks - 1; i >= 0; i--) {
361 MonoBasicBlock *bb = cfg->bblocks [i];
363 printf ("LIVE IN BB%d: ", bb->block_num);
364 mono_bitset_print (bb->live_in_set);
365 printf ("LIVE OUT BB%d: ", bb->block_num);
366 mono_bitset_print (bb->live_out_set);