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 Optimizations for a whole ir graph, i.e., a procedure.
23 * @author Christian Schaefer, Goetz Lindenmaier, Sebastian Felis,
32 #include "irgraph_t.h"
34 #include "iroptimize.h"
44 #include "iredges_t.h"
47 /*------------------------------------------------------------------*/
48 /* apply optimizations of iropt to all nodes. */
49 /*------------------------------------------------------------------*/
52 * A wrapper around optimize_inplace_2() to be called from a walker.
54 static void optimize_in_place_wrapper(ir_node *n, void *env)
56 ir_node *optimized = optimize_in_place_2(n);
60 exchange(n, optimized);
65 * Do local optimizations for a node.
67 * @param n the IR-node where to start. Typically the End node
70 * @note current_ir_graph must be set
72 static inline void do_local_optimize(ir_node *n)
74 ir_graph *irg = get_irn_irg(n);
76 /* Handle graph state */
77 assert(get_irg_phase_state(irg) != phase_building);
79 if (get_opt_global_cse())
80 set_irg_pinned(irg, op_pin_state_floats);
81 set_irg_outs_inconsistent(irg);
82 set_irg_doms_inconsistent(irg);
83 set_irg_loopinfo_inconsistent(irg);
85 /* Clean the value_table in irg for the CSE. */
88 /* walk over the graph */
89 irg_walk(n, firm_clear_link, optimize_in_place_wrapper, NULL);
92 /* Applies local optimizations (see iropt.h) to all nodes reachable from node n */
93 void local_optimize_node(ir_node *n)
95 ir_graph *rem = current_ir_graph;
96 current_ir_graph = get_irn_irg(n);
100 current_ir_graph = rem;
104 * Enqueue all users of a node to a wait queue.
105 * Handles mode_T nodes.
107 static void enqueue_users(ir_node *n, pdeq *waitq)
109 const ir_edge_t *edge;
111 foreach_out_edge(n, edge) {
112 ir_node *succ = get_edge_src_irn(edge);
114 if (get_irn_link(succ) != waitq) {
115 pdeq_putr(waitq, succ);
116 set_irn_link(succ, waitq);
118 if (get_irn_mode(succ) == mode_T) {
119 /* A mode_T node has Proj's. Because most optimizations
120 run on the Proj's we have to enqueue them also. */
121 enqueue_users(succ, waitq);
127 * Block-Walker: uses dominance depth to mark dead blocks.
129 static void kill_dead_blocks(ir_node *block, void *env)
131 pdeq *waitq = (pdeq*) env;
133 if (get_Block_dom_depth(block) < 0) {
135 * Note that the new dominance code correctly handles
136 * the End block, i.e. it is always reachable from Start
138 ir_graph *irg = get_irn_irg(block);
139 enqueue_users(block, waitq);
140 exchange(block, new_r_Bad(irg, mode_BB));
144 /* Applies local optimizations (see iropt.h) to all nodes reachable from node n. */
145 void local_optimize_graph(ir_graph *irg)
147 ir_graph *rem = current_ir_graph;
148 current_ir_graph = irg;
150 do_local_optimize(get_irg_end(irg));
152 current_ir_graph = rem;
156 * Data flow optimization walker.
157 * Optimizes all nodes and enqueue its users
160 static void opt_walker(ir_node *n, void *env)
162 pdeq *waitq = (pdeq*)env;
165 optimized = optimize_in_place_2(n);
166 set_irn_link(optimized, NULL);
168 if (optimized != n) {
169 enqueue_users(n, waitq);
170 exchange(n, optimized);
174 static void clear_block_phis(ir_node *node, void *env) {
176 if (is_Block(node)) {
177 set_Block_phis(node, NULL);
181 static void collect_block_phis(ir_node *node, void *env) {
184 add_Block_phi(get_nodes_block(node), node);
188 static int count_non_bads(ir_node *node) {
189 int arity = get_irn_arity(node);
192 for (i=0; i<arity; ++i) {
193 if (!is_Bad(get_irn_n(node, i)))
199 static void block_remove_bads(ir_node *block, int *changed) {
202 const int max = get_irn_arity(block);
203 const int new_max = count_non_bads(block);
204 assert (max >= new_max);
206 if (is_Bad(block) || max == new_max) return;
208 new_in = ALLOCAN(ir_node*, new_max);
211 assert (get_Block_dom_depth(block) >= 0);
213 /* 1. Create a new block without Bad inputs */
215 for (i = 0; i < max; ++i) {
216 ir_node *block_pred = get_irn_n(block, i);
217 if (!is_Bad(block_pred)) {
218 new_in[j++] = block_pred;
221 assert (j == new_max);
223 /* If the end block is unreachable, it might have zero predecessors. */
224 ir_node *end_block = get_irg_end_block(get_irn_irg(block));
225 if (new_max == 0 && block == end_block) {
226 set_irn_in(block, new_max, new_in);
230 ir_node *new_block = new_r_Block(get_irn_irg(block), new_max, new_in);
232 /* 2. Remove inputs on Phis, where the block input is Bad. */
233 ir_node *phi = get_Block_phis(block);
236 ir_node* next = get_Phi_next(phi);
237 if (get_irn_arity(phi) != new_max) {
239 for (i = 0; i < max; ++i) {
240 ir_node *block_pred = get_irn_n(block, i);
242 if (!is_Bad(block_pred)) {
243 ir_node *pred = get_irn_n(phi, i);
247 assert (j == new_max);
249 ir_node *new_phi = new_r_Phi(new_block, new_max, new_in, get_irn_mode(phi));
250 exchange(phi, new_phi);
253 } while (phi != NULL);
256 exchange(block, new_block);
259 /* Remove Bad nodes from Phi and Block inputs.
261 * Precondition: No unreachable code.
262 * Postcondition: No Bad nodes.
264 static int remove_Bads(ir_graph *irg) {
266 /* build phi list per block */
267 irg_walk_graph(irg, clear_block_phis, collect_block_phis, NULL);
269 /* actually remove Bads */
270 irg_block_walk_graph(irg, NULL, (void (*)(struct ir_node *, void *)) block_remove_bads, &changed);
275 /* Applies local optimizations to all nodes in the graph until fixpoint. */
276 int optimize_graph_df(ir_graph *irg)
278 pdeq *waitq = new_pdeq();
279 ir_graph *rem = current_ir_graph;
283 current_ir_graph = irg;
285 state = edges_assure(irg);
287 /* Clean the value_table in irg for the CSE. */
290 if (get_opt_global_cse()) {
291 set_irg_pinned(irg, op_pin_state_floats);
294 /* The following enables unreachable code elimination (=Blocks may be
296 set_irg_state(irg, IR_GRAPH_STATE_BAD_BLOCK);
298 /* invalidate info */
299 set_irg_outs_inconsistent(irg);
300 set_irg_doms_inconsistent(irg);
301 set_irg_loopinfo_inconsistent(irg);
303 ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK);
305 /* walk over the graph, but don't touch keep-alives */
306 irg_walk_graph(irg, NULL, opt_walker, waitq);
308 /* any optimized nodes are stored in the wait queue,
309 * so if it's not empty, the graph has been changed */
310 changed = !pdeq_empty(waitq);
313 /* finish the wait queue */
314 while (! pdeq_empty(waitq)) {
315 ir_node *n = (ir_node*)pdeq_getl(waitq);
316 opt_walker(n, waitq);
318 /* kill newly generated unreachable code */
319 set_irg_outs_inconsistent(irg);
321 irg_block_walk_graph(irg, NULL, kill_dead_blocks, waitq);
322 } while (! pdeq_empty(waitq));
326 ir_free_resources(irg, IR_RESOURCE_IRN_LINK);
329 edges_deactivate(irg);
331 /* Finally kill BAD and doublets from the keep alives.
332 Doing this AFTER edges where deactivated saves cycles */
333 end = get_irg_end(irg);
334 remove_End_Bads_and_doublets(end);
336 if (remove_Bads(irg))
337 edges_deactivate(irg);
339 clear_irg_state(irg, IR_GRAPH_STATE_BAD_BLOCK);
341 current_ir_graph = rem;
345 /* Creates an ir_graph pass for optimize_graph_df. */
346 ir_graph_pass_t *optimize_graph_df_pass(const char *name)
348 return def_graph_pass_ret(name ? name : "optimize_graph_df", optimize_graph_df);
349 } /* optimize_graph_df_pass */