1 /*
2 * Copyright (C) 1995-2011 University of Karlsruhe. All right reserved.
3 *
4 * This file is part of libFirm.
5 *
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.
10 *
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.
14 *
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
17 * PURPOSE.
18 */
19
20 /**
21 * @file
22 * @brief Peephole optimisation framework keeps track of which registers contain which values
23 * @author Matthias Braun
24 */
25 #include "config.h"
26
27 #include "array_t.h"
28 #include "bepeephole.h"
29
30 #include "iredges_t.h"
31 #include "irgwalk.h"
32 #include "irprintf.h"
33 #include "ircons.h"
34 #include "irgmod.h"
35 #include "heights.h"
36 #include "error.h"
37
38 #include "beirg.h"
39 #include "belive_t.h"
40 #include "bearch.h"
41 #include "beintlive_t.h"
42 #include "benode.h"
43 #include "besched.h"
44 #include "bemodule.h"
45
46 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
47
48 static const arch_env_t *arch_env;
49 static be_lv_t *lv;
50 static ir_node *current_node;
51 ir_node **register_values;
52
clear_reg_value(ir_node * node)53 static void clear_reg_value(ir_node *node)
54 {
55 const arch_register_t *reg;
56 unsigned reg_idx;
57
58 if (!mode_is_data(get_irn_mode(node)))
59 return;
60
61 reg = arch_get_irn_register(node);
62 if (reg == NULL) {
63 panic("No register assigned at %+F", node);
64 }
65 if (reg->type & arch_register_type_virtual)
66 return;
67 reg_idx = reg->global_index;
68
69 DB((dbg, LEVEL_1, "Clear Register %s\n", reg->name));
70 register_values[reg_idx] = NULL;
71 }
72
set_reg_value(ir_node * node)73 static void set_reg_value(ir_node *node)
74 {
75 const arch_register_t *reg;
76 unsigned reg_idx;
77
78 if (!mode_is_data(get_irn_mode(node)))
79 return;
80
81 reg = arch_get_irn_register(node);
82 if (reg == NULL) {
83 panic("No register assigned at %+F", node);
84 }
85 if (reg->type & arch_register_type_virtual)
86 return;
87 reg_idx = reg->global_index;
88
89 DB((dbg, LEVEL_1, "Set Register %s: %+F\n", reg->name, node));
90 register_values[reg_idx] = node;
91 }
92
clear_defs(ir_node * node)93 static void clear_defs(ir_node *node)
94 {
95 /* clear values defined */
96 if (get_irn_mode(node) == mode_T) {
97 foreach_out_edge(node, edge) {
98 ir_node *proj = get_edge_src_irn(edge);
99 clear_reg_value(proj);
100 }
101 } else {
102 clear_reg_value(node);
103 }
104 }
105
set_uses(ir_node * node)106 static void set_uses(ir_node *node)
107 {
108 int i, arity;
109
110 /* set values used */
111 arity = get_irn_arity(node);
112 for (i = 0; i < arity; ++i) {
113 ir_node *in = get_irn_n(node, i);
114 set_reg_value(in);
115 }
116 }
117
be_peephole_new_node(ir_node * nw)118 void be_peephole_new_node(ir_node * nw)
119 {
120 be_liveness_introduce(lv, nw);
121 }
122
123 /**
124 * must be called from peephole optimisations before a node will be killed
125 * and its users will be redirected to new_node.
126 * so bepeephole can update its internal state.
127 *
128 * Note: killing a node and rewiring is only allowed if new_node produces
129 * the same registers as old_node.
130 */
be_peephole_before_exchange(const ir_node * old_node,ir_node * new_node)131 static void be_peephole_before_exchange(const ir_node *old_node,
132 ir_node *new_node)
133 {
134 const arch_register_t *reg;
135 unsigned reg_idx;
136 bool old_is_current = false;
137
138 DB((dbg, LEVEL_1, "About to exchange and kill %+F with %+F\n", old_node, new_node));
139
140 assert(sched_is_scheduled(skip_Proj_const(old_node)));
141 assert(sched_is_scheduled(skip_Proj(new_node)));
142
143 if (current_node == old_node) {
144 old_is_current = true;
145
146 /* next node to be processed will be killed. Its scheduling predecessor
147 * must be processed next. */
148 current_node = sched_next(current_node);
149 assert (!is_Bad(current_node));
150
151 /* we can't handle liveness updates correctly when exchange current node
152 * with something behind it */
153 assert(value_dominates(skip_Proj(new_node), skip_Proj_const(old_node)));
154 }
155
156 if (!mode_is_data(get_irn_mode(old_node)))
157 return;
158
159 reg = arch_get_irn_register(old_node);
160 if (reg == NULL) {
161 panic("No register assigned at %+F", old_node);
162 }
163 assert(reg == arch_get_irn_register(new_node) &&
164 "KILLING a node and replacing by different register is not allowed");
165
166 reg_idx = reg->global_index;
167 if (register_values[reg_idx] == old_node || old_is_current) {
168 register_values[reg_idx] = new_node;
169 }
170
171 be_liveness_remove(lv, old_node);
172 }
173
be_peephole_exchange(ir_node * old,ir_node * nw)174 void be_peephole_exchange(ir_node *old, ir_node *nw)
175 {
176 be_peephole_before_exchange(old, nw);
177 sched_remove(old);
178 exchange(old, nw);
179 be_peephole_new_node(nw);
180 }
181
182 /**
183 * block-walker: run peephole optimization on the given block.
184 */
process_block(ir_node * block,void * data)185 static void process_block(ir_node *block, void *data)
186 {
187 (void) data;
188
189 /* construct initial register assignment */
190 memset(register_values, 0, sizeof(ir_node*) * arch_env->n_registers);
191
192 assert(lv->sets_valid && "live sets must be computed");
193 DB((dbg, LEVEL_1, "\nProcessing block %+F (from end)\n", block));
194 be_lv_foreach(lv, block, be_lv_state_end, node) {
195 set_reg_value(node);
196 }
197 DB((dbg, LEVEL_1, "\nstart processing\n"));
198
199 /* walk the block from last insn to the first */
200 current_node = sched_last(block);
201 for ( ; !sched_is_begin(current_node);
202 current_node = sched_prev(current_node)) {
203 ir_op *op;
204 peephole_opt_func peephole_node;
205
206 assert(!is_Bad(current_node));
207 if (is_Phi(current_node))
208 break;
209
210 clear_defs(current_node);
211 set_uses(current_node);
212
213 op = get_irn_op(current_node);
214 peephole_node = (peephole_opt_func)op->ops.generic;
215 if (peephole_node == NULL)
216 continue;
217
218 DB((dbg, LEVEL_2, "optimize %+F\n", current_node));
219 peephole_node(current_node);
220 assert(!is_Bad(current_node));
221 }
222 }
223
224 /**
225 * Check whether the node has only one user. Explicitly ignore the anchor.
226 */
be_has_only_one_user(ir_node * node)227 bool be_has_only_one_user(ir_node *node)
228 {
229 int n = get_irn_n_edges(node);
230 int n_users;
231
232 if (n <= 1)
233 return 1;
234
235 n_users = 0;
236 foreach_out_edge(node, edge) {
237 ir_node *src = get_edge_src_irn(edge);
238 /* ignore anchor and keep-alive edges */
239 if (is_Anchor(src) || is_End(src))
240 continue;
241 n_users++;
242 }
243
244 return n_users == 1;
245 }
246
overlapping_regs(const arch_register_t * reg0,const arch_register_req_t * req0,const arch_register_t * reg1,const arch_register_req_t * req1)247 static inline bool overlapping_regs(const arch_register_t *reg0,
248 const arch_register_req_t *req0, const arch_register_t *reg1,
249 const arch_register_req_t *req1)
250 {
251 if (reg0 == NULL || reg1 == NULL)
252 return false;
253 return reg0->global_index < (unsigned)reg1->global_index + req1->width
254 && reg1->global_index < (unsigned)reg0->global_index + req0->width;
255 }
256
be_can_move_down(ir_heights_t * heights,const ir_node * node,const ir_node * before)257 bool be_can_move_down(ir_heights_t *heights, const ir_node *node,
258 const ir_node *before)
259 {
260 assert(get_nodes_block(node) == get_nodes_block(before));
261 assert(sched_get_time_step(node) < sched_get_time_step(before));
262
263 int node_arity = get_irn_arity(node);
264 ir_node *schedpoint = sched_next(node);
265
266 while (schedpoint != before) {
267 /* schedpoint must not use our computed values */
268 if (heights_reachable_in_block(heights, schedpoint, node))
269 return false;
270
271 /* schedpoint must not overwrite registers of our inputs */
272 unsigned n_outs = arch_get_irn_n_outs(schedpoint);
273 for (int i = 0; i < node_arity; ++i) {
274 ir_node *in = get_irn_n(node, i);
275 const arch_register_t *reg = arch_get_irn_register(in);
276 if (reg == NULL)
277 continue;
278 const arch_register_req_t *in_req
279 = arch_get_irn_register_req_in(node, i);
280 for (unsigned o = 0; o < n_outs; ++o) {
281 const arch_register_t *outreg
282 = arch_get_irn_register_out(schedpoint, o);
283 const arch_register_req_t *outreq
284 = arch_get_irn_register_req_out(schedpoint, o);
285 if (overlapping_regs(reg, in_req, outreg, outreq))
286 return false;
287 }
288 }
289
290 schedpoint = sched_next(schedpoint);
291 }
292 return true;
293 }
294
be_can_move_up(ir_heights_t * heights,const ir_node * node,const ir_node * after)295 bool be_can_move_up(ir_heights_t *heights, const ir_node *node,
296 const ir_node *after)
297 {
298 unsigned n_outs = arch_get_irn_n_outs(node);
299 const ir_node *node_block = get_nodes_block(node);
300 const ir_node *after_block = get_block_const(after);
301 const ir_node *schedpoint;
302 if (node_block != after_block) {
303 /* currently we can move up exactly 1 block */
304 assert(get_Block_cfgpred_block(node_block, 0) == after_block);
305 ir_node *first = sched_first(node_block);
306
307 /* do not move nodes changing memory */
308 if (is_memop(node)) {
309 ir_node *meminput = get_memop_mem(node);
310 if (!is_NoMem(meminput))
311 return false;
312 }
313
314 /* make sure we can move to the beginning of the succ block */
315 if (node != first && !be_can_move_up(heights, node, sched_prev(first)))
316 return false;
317
318 /* check if node overrides any of live-in values of other successors */
319 ir_graph *irg = get_irn_irg(node);
320 be_lv_t *lv = be_get_irg_liveness(irg);
321 foreach_block_succ(after_block, edge) {
322 ir_node *succ = get_edge_src_irn(edge);
323 if (succ == node_block)
324 continue;
325
326 be_lv_foreach(lv, succ, be_lv_state_in, live_node) {
327 const arch_register_t *reg = arch_get_irn_register(live_node);
328 const arch_register_req_t *req = arch_get_irn_register_req(live_node);
329 for (unsigned o = 0; o < n_outs; ++o) {
330 const arch_register_t *outreg
331 = arch_get_irn_register_out(node, o);
332 const arch_register_req_t *outreq
333 = arch_get_irn_register_req_out(node, o);
334 if (overlapping_regs(outreg, outreq, reg, req))
335 return false;
336 }
337 }
338 sched_foreach(succ, phi) {
339 if (!is_Phi(phi))
340 break;
341 const arch_register_t *reg = arch_get_irn_register(phi);
342 const arch_register_req_t *req = arch_get_irn_register_req(phi);
343 for (unsigned o = 0; o < n_outs; ++o) {
344 const arch_register_t *outreg
345 = arch_get_irn_register_out(node, o);
346 const arch_register_req_t *outreq
347 = arch_get_irn_register_req_out(node, o);
348 if (overlapping_regs(outreg, outreq, reg, req))
349 return false;
350 }
351 }
352 }
353 schedpoint = sched_last(after_block);
354 } else {
355 schedpoint = sched_prev(node);
356 }
357
358 /* move schedule upwards until we hit the "after" node */
359 while (schedpoint != after) {
360 /* TODO: the following heights query only works for nodes in the same
361 * block, otherwise we have to be conservative here */
362 if (get_nodes_block(node) != get_nodes_block(schedpoint))
363 return false;
364 /* node must not depend on schedpoint */
365 if (heights_reachable_in_block(heights, node, schedpoint))
366 return false;
367
368 /* node must not overwrite registers used by schedpoint */
369 int arity = get_irn_arity(schedpoint);
370 for (int i = 0; i < arity; ++i) {
371 const arch_register_t *reg
372 = arch_get_irn_register_in(schedpoint, i);
373 if (reg == NULL)
374 continue;
375 const arch_register_req_t *in_req
376 = arch_get_irn_register_req_in(schedpoint, i);
377 for (unsigned o = 0; o < n_outs; ++o) {
378 const arch_register_t *outreg
379 = arch_get_irn_register_out(node, o);
380 const arch_register_req_t *outreq
381 = arch_get_irn_register_req_out(node, o);
382 if (overlapping_regs(outreg, outreq, reg, in_req))
383 return false;
384 }
385 }
386
387 schedpoint = sched_prev(schedpoint);
388 }
389 return true;
390 }
391
392 /*
393 * Tries to optimize a beIncSP node with its previous IncSP node.
394 * Must be run from a be_peephole_opt() context.
395 */
be_peephole_IncSP_IncSP(ir_node * node)396 ir_node *be_peephole_IncSP_IncSP(ir_node *node)
397 {
398 int pred_offs;
399 int curr_offs;
400 int offs;
401 ir_node *pred = be_get_IncSP_pred(node);
402
403 if (!be_is_IncSP(pred))
404 return node;
405
406 if (!be_has_only_one_user(pred))
407 return node;
408
409 pred_offs = be_get_IncSP_offset(pred);
410 curr_offs = be_get_IncSP_offset(node);
411 offs = curr_offs + pred_offs;
412
413 /* add node offset to pred and remove our IncSP */
414 be_set_IncSP_offset(pred, offs);
415
416 be_peephole_exchange(node, pred);
417 return pred;
418 }
419
be_peephole_opt(ir_graph * irg)420 void be_peephole_opt(ir_graph *irg)
421 {
422 #if 0
423 /* we sometimes find BadE nodes in float apps like optest_float.c or
424 * kahansum.c for example... */
425 be_invalidate_live_sets(irg);
426 #endif
427 be_assure_live_sets(irg);
428
429 arch_env = be_get_irg_arch_env(irg);
430 lv = be_get_irg_liveness(irg);
431
432 register_values = XMALLOCN(ir_node*, arch_env->n_registers);
433
434 irg_block_walk_graph(irg, process_block, NULL, NULL);
435
436 xfree(register_values);
437 }
438
BE_REGISTER_MODULE_CONSTRUCTOR(be_init_peephole)439 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_peephole)
440 void be_init_peephole(void)
441 {
442 FIRM_DBG_REGISTER(dbg, "firm.be.peephole");
443 }
444