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 Simple SSA destruction.
23 * @author Daniel Grund
42 #include "irprintf_t.h"
44 #include "irgraph_t.h"
46 #include "iredges_t.h"
54 #include "besched_t.h"
59 #include "bessadestrsimple.h"
63 typedef struct _ssa_destr_env_t {
65 const arch_register_class_t *cls;
69 #define pset_foreach(pset, irn) for(irn=pset_first(pset); irn; irn=pset_next(pset))
70 #define set_foreach(set, e) for(e=set_first(set); e; e=set_next(set))
72 static phi_classes_t *pc = NULL;
74 /******************************************************************************
76 \ \ / / | | |__ \ \ \ / /
77 \ \ / /_ _| |___ ) | \ \ / /_ _ _ __ ___
78 \ \/ / _` | / __| / / \ \/ / _` | '__/ __|
79 \ / (_| | \__ \ / /_ \ / (_| | | \__ \
80 \/ \__,_|_|___/ |____| \/ \__,_|_| |___/
81 *****************************************************************************/
84 * The link field of an irn points to the var_info struct
85 * representing the corresponding variable.
87 #define set_var_info(irn, vi) set_irn_link(irn, vi)
89 #define HASH_VAR_NR(var_nr) var_nr
91 static int compare_var_infos(const void *e1, const void *e2, size_t size) {
92 const be_var_info_t *v1 = e1;
93 const be_var_info_t *v2 = e2;
95 if (v1->var_nr == SET_REMOVED || v2->var_nr == SET_REMOVED)
98 return v1->var_nr != v2->var_nr;
101 be_var_info_t *be_var_find(set *vars, int var_nr) {
105 return set_find(vars, &vi, sizeof(vi), HASH_VAR_NR(var_nr));
108 be_var_info_t *be_var_find_or_insert(set *vars, int var_nr) {
109 be_var_info_t vi, *found;
110 memset(&vi, 0, sizeof(vi));
113 found = set_insert(vars, &vi, sizeof(vi), HASH_VAR_NR(var_nr));
116 found->values = pset_new_ptr(1);
122 * Adds a value to a variable. Sets all pointers accordingly.
124 be_var_info_t *be_var_add_value(set *vars, int var_nr, ir_node *irn) {
125 be_var_info_t *vi = be_var_find_or_insert(vars, var_nr);
127 /* var 2 value mapping */
128 pset_insert_ptr(vi->values, irn);
130 /* value 2 var mapping */
131 set_var_info(irn, vi);
136 pset *be_get_var_values(set *vars, int var_nr) {
137 be_var_info_t *vi = be_var_find(vars, var_nr);
138 assert(vi && "Variable does not exist");
142 static INLINE ir_node *get_first_phi(ir_node **s) {
145 for (i = ARR_LEN(s) - 1; i >= 0; --i) {
150 assert(0 && "There must be a phi in this");
156 * Define variables (numbers) for all SSA-values.
157 * All values in a phi class get assigned the same variable name.
158 * The link field maps values to the var-name
160 static void values_to_vars(ir_node *irn, void *env) {
161 ssa_destr_env_t *sde = env;
162 int nr, i, build_vals = 0;
165 if (arch_get_irn_reg_class(irn, -1) == NULL)
168 vals = get_phi_class(pc, irn);
171 nr = get_irn_node_nr(get_first_phi(vals));
173 /* not a phi class member, value == var */
174 nr = get_irn_node_nr(irn);
175 vals = NEW_ARR_F(ir_node *, 1);
180 /* values <--> var mapping */
181 for (i = ARR_LEN(vals) - 1; i >= 0; --i) {
182 be_var_add_value(sde->vars, nr, vals[i]);
189 /******************************************************************************
191 / ____/ ____| /\ | __ \ | |
192 | (___| (___ / \ ______| | | | ___ ___| |_ _ __
193 \___ \\___ \ / /\ \______| | | |/ _ \/ __| __| '__|
194 ____) |___) / ____ \ | |__| | __/\__ \ |_| |
195 |_____/_____/_/ \_\ |_____/ \___||___/\__|_|
197 *****************************************************************************/
199 #define mark_as_done(irn, pos) set_irn_link(irn, INT_TO_PTR(pos+1))
200 #define has_been_done(irn, pos) (PTR_TO_INT(get_irn_link(irn)) > pos)
203 * Insert a copy for the argument of @p start_phi found at position @p pos.
204 * Also searches a phi-loop of arbitrary length to detect and resolve
205 * the class of phi-swap-problems. To search for a loop recursion is used.
207 * 1) Simplest case (phi with a non-phi arg):
208 * A single copy is inserted.
210 * 2) Phi chain (phi (with phi-arg)* with non-phi arg):
211 * Several copies are placed, each after returning from recursion.
214 * On detection a loop breaker is inserted, which is a copy of the start_phi.
215 * This copy then pretends beeing the argumnent of the last phi.
216 * Now case 2) can be used.
218 * The values of @p start_phi and @p pos never change during recursion.
220 * @p start_phi Phi node to process
221 * @p pos Argument position to insert copy/copies for
222 * @p curr_phi Phi node currently processed during recursion. Equals start_phi on initial call
224 * @return NULL If no copy is necessary
225 * NULL If the phi has already been processed at this pos
226 * Link field is used to keep track of processed positions
227 * In all other cases the ir_node *copy which was placed is returned.
229 static ir_node *insert_copies(ssa_destr_env_t *sde, const arch_register_class_t *cls, ir_node *start_phi, int pos, ir_node *curr_phi) {
230 ir_node *arg = get_irn_n(curr_phi, pos);
231 ir_node *arg_blk = get_nodes_block(arg);
232 ir_node *pred_blk = get_Block_cfgpred_block(get_nodes_block(curr_phi), pos);
233 ir_node *curr_cpy, *last_cpy;
235 assert(is_Phi(start_phi) && is_Phi(curr_phi));
237 if (has_been_done(start_phi, pos))
240 /* In case this is a 'normal' phi we insert at the
241 * end of the pred block before cf nodes */
242 last_cpy = sched_skip(pred_blk, 0, sched_skip_cf_predicator, NULL);
243 last_cpy = sched_next(last_cpy);
245 /* If we detect a loop stop recursion. */
246 if (arg == start_phi) {
247 ir_node *loop_breaker;
248 if (start_phi == curr_phi) {
249 /* Phi directly uses itself. No copy necessary */
253 /* At least 2 phis are involved */
254 /* Insert a loop breaking copy (an additional variable T) */
255 loop_breaker = be_new_Copy(cls, sde->irg, pred_blk, start_phi);
256 sched_add_before(last_cpy, loop_breaker);
261 /* If arg is a phi in the same block we have to continue search */
262 if (is_Phi(arg) && arg_blk == get_nodes_block(start_phi))
263 last_cpy = insert_copies(sde, cls, start_phi, pos, arg);
265 /* Insert copy of argument (may be the loop-breaker) */
266 curr_cpy = be_new_Copy(cls, sde->irg, pred_blk, arg);
267 set_irn_n(curr_phi, pos, curr_cpy);
268 mark_as_done(curr_phi, pos);
269 sched_add_before(last_cpy, curr_cpy);
275 * Perform simple SSA-destruction with copies.
276 * The order of processing _must_ be
277 * for all positions {
282 * else the magic to keep track of processed phi-positions will fail in
283 * function 'insert_copies'
285 static void ssa_destr_simple_walker(ir_node *blk, void *env) {
286 ssa_destr_env_t *sde = env;
289 const arch_register_class_t *cls;
291 /* for all argument positions of the phis */
292 for (pos=0, max=get_irn_arity(blk); pos<max; ++pos) {
294 /* for all phi nodes (which are scheduled first) */
295 sched_foreach(blk, phi) {
299 if (arch_irn_is(phi, ignore))
302 cls = arch_get_irn_reg_class(phi, -1);
303 insert_copies(sde, cls, phi, pos, phi);
309 set *be_ssa_destr_simple(ir_graph *irg)
314 sde.vars = new_set(compare_var_infos, 16);
317 irg_block_walk_graph(irg, ssa_destr_simple_walker, NULL, &sde);
319 /* Mapping of SSA-Values <--> Variables */
320 pc = phi_class_new_from_irg(irg, 0);
322 irg_walk_graph(irg, values_to_vars, NULL, &sde);
327 void free_ssa_destr_simple(set *vars)
331 set_foreach(vars, vi)
332 del_pset(vi->values);
338 #endif /* NOT_PORTED */