2 * Copyright (C) 1995-2007 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 Optimization of function calls.
23 * @author Michael Beck
30 #include <adt/raw_bitset.h>
32 #include "funccall_t.h"
35 #include "irgraph_t.h"
39 #include "dbginfo_t.h"
45 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
48 * The walker environment for rem_mem_from_const_fkt_calls
50 typedef struct _env_t {
51 unsigned n_calls_SymConst;
53 ir_node *const_call_list; /**< The list of all const function calls that will be changed. */
54 ir_node *pure_call_list; /**< The list of all pure function calls that will be changed. */
55 ir_node *proj_list; /**< The list of all potential Proj nodes that must be fixed. */
58 /** Ready IRG's are marked in the ready set. */
59 static unsigned *ready_set;
61 /** IRG's that are in progress are marked here. */
62 static unsigned *busy_set;
65 * We misuse the mtp_temporary flag as temporary here.
66 * The is ok, as we cannot set or get it anyway.
68 #define mtp_temporary mtp_property_inherited
71 * Collect all calls to const and pure functions
72 * to lists. Collect all Proj(Call) nodes into a Proj list.
74 static void collect_calls(ir_node *node, void *env) {
83 /* set the link to NULL for all non-const/pure calls */
84 set_irn_link(call, NULL);
85 ptr = get_Call_ptr(call);
86 if (is_SymConst(ptr) && get_SymConst_kind(ptr) == symconst_addr_ent) {
87 ent = get_SymConst_entity(ptr);
89 mode = get_entity_additional_properties(ent);
90 if ((mode & (mtp_property_const|mtp_property_pure)) == 0)
92 ++ctx->n_calls_SymConst;
93 } else if (get_opt_closed_world() &&
95 get_irg_callee_info_state(current_ir_graph) == irg_callee_info_consistent) {
96 /* If all possible callees are const functions, we can remove the memory edge. */
97 int i, n_callees = get_Call_n_callees(call);
99 /* This is kind of strange: dying code or a Call that will raise an exception
100 when executed as there is no implementation to call. So better not
105 /* note that const function are a subset of pure ones */
106 mode = mtp_property_const | mtp_property_pure;
107 for (i = 0; i < n_callees; ++i) {
108 ent = get_Call_callee(call, i);
109 if (ent == unknown_entity) {
110 /* we don't know which entity is called here */
113 mode &= get_entity_additional_properties(ent);
121 /* ok, if we get here we found a call to a const or a pure function */
122 if (mode & mtp_property_pure) {
123 set_irn_link(call, ctx->pure_call_list);
124 ctx->pure_call_list = call;
126 set_irn_link(call, ctx->const_call_list);
127 ctx->const_call_list = call;
129 } else if (is_Proj(node)) {
131 * Collect all memory and exception Proj's from
134 call = get_Proj_pred(node);
138 /* collect the Proj's in the Proj list */
139 switch (get_Proj_proj(node)) {
140 case pn_Call_M_regular:
141 case pn_Call_X_except:
142 case pn_Call_M_except:
143 set_irn_link(node, ctx->proj_list);
144 ctx->proj_list = node;
150 } /* collect_calls */
153 * Fix the list of collected Calls.
155 * @param irg the graph that contained calls to pure functions
156 * @param call_list the list of all call sites of const functions
157 * @param proj_list the list of all memory/exception Proj's of this call sites
159 static void fix_const_call_list(ir_graph *irg, ir_node *call_list, ir_node *proj_list) {
160 ir_node *call, *next, *mem, *proj;
162 ir_graph *rem = current_ir_graph;
164 current_ir_graph = irg;
166 /* First step: fix all calls by removing it's memory input.
167 It's original memory input is preserved in their link fields. */
168 for (call = call_list; call; call = next) {
169 next = get_irn_link(call);
170 mem = get_Call_mem(call);
172 set_irn_link(call, mem);
173 set_Call_mem(call, get_irg_no_mem(irg));
176 * Sorrily we cannot simply set the node to 'float'.
177 * There is a reason for that:
179 * - The call might be inside a loop/if that is NOT entered
180 * and calls a endless function. Setting the call to float
181 * would allow to move it out from the loop/if causing this
182 * function be called even if the loop/if is not entered ...
184 * This could be fixed using post-dominators for calls and Pin nodes
185 * but need some more analyzes to ensure that a call that potential
186 * never returns is not executed before some code that generates
187 * observable states...
190 /* finally, this call can float
191 set_irn_pinned(call, op_pin_state_floats); */
192 hook_func_call(irg, call);
195 /* Second step: fix all Proj's */
196 for (proj = proj_list; proj; proj = next) {
197 next = get_irn_link(proj);
198 call = get_Proj_pred(proj);
199 mem = get_irn_link(call);
201 /* beware of calls in the pure call list */
202 if (! mem || get_irn_op(mem) == op_Call)
204 assert(get_irn_mode(mem) == mode_M);
206 switch (get_Proj_proj(proj)) {
207 case pn_Call_M_regular: {
208 /* in dead code there might be cycles where proj == mem */
212 case pn_Call_X_except:
213 case pn_Call_M_except:
215 exchange(proj, get_irg_bad(irg));
222 /* changes were done ... */
223 set_irg_outs_inconsistent(irg);
224 set_irg_loopinfo_state(irg, loopinfo_cf_inconsistent);
227 /* ... including exception edges */
228 set_irg_doms_inconsistent(irg);
230 current_ir_graph = rem;
231 } /* fix_call_list */
234 #define SET_IRG_READY(irg) rbitset_set(ready_set, get_irg_idx(irg))
235 #define IS_IRG_READY(irg) rbitset_is_set(ready_set, get_irg_idx(irg))
236 #define SET_IRG_BUSY(irg) rbitset_set(busy_set, get_irg_idx(irg))
237 #define CLEAR_IRG_BUSY(irg) rbitset_clear(busy_set, get_irg_idx(irg))
238 #define IS_IRG_BUSY(irg) rbitset_is_set(busy_set, get_irg_idx(irg))
241 static unsigned check_const_or_pure_function(ir_graph *irg, int top);
244 * Calculate the bigger mode of two. Handle the temporary flag right.
246 static unsigned mode_max(unsigned a, unsigned b) {
247 unsigned r, t = (a | b) & mtp_temporary;
251 if (a == mtp_no_property || b == mtp_no_property)
252 return mtp_no_property;
258 * Follow the memory chain starting at node and determine
261 * @return mtp_property_const if only calls of const functions are detected
262 * mtp_property_pure if only Loads and const/pure
264 * mtp_no_property else
266 static unsigned _follow_mem(ir_node *node) {
267 unsigned m, mode = mtp_property_const;
272 if (mode == mtp_no_property)
273 return mtp_no_property;
275 if (irn_visited(node))
278 mark_irn_visited(node);
280 switch (get_irn_opcode(node)) {
282 node = get_Proj_pred(node);
291 /* do a dfs search */
292 for (i = get_irn_arity(node) - 1; i >= 0; --i) {
293 m = _follow_mem(get_irn_n(node, i));
294 mode = mode_max(mode, m);
295 if (mode == mtp_no_property)
296 return mtp_no_property;
301 /* Beware volatile Loads are NOT allowed in pure functions. */
302 if (get_Load_volatility(node) == volatility_is_volatile)
303 return mtp_no_property;
304 mode = mode_max(mode, mtp_property_pure);
305 node = get_Load_mem(node);
309 /* A call is only tolerable if its either constant or pure. */
310 ptr = get_Call_ptr(node);
311 if (get_irn_op(ptr) == op_SymConst &&
312 get_SymConst_kind(ptr) == symconst_addr_ent) {
313 ir_entity *ent = get_SymConst_entity(ptr);
314 ir_graph *irg = get_entity_irg(ent);
316 if (irg == current_ir_graph) {
317 /* A self-recursive call. The mode did not depend on this call. */
318 } else if (irg == NULL) {
319 m = get_entity_additional_properties(ent) & (mtp_property_const|mtp_property_pure);
320 mode = mode_max(mode, m);
321 } else if (irg != NULL) {
322 /* we have a graph, analyze it. */
323 m = check_const_or_pure_function(irg, /*top=*/0);
324 mode = mode_max(mode, m);
327 return mtp_no_property;
328 node = get_Call_mem(node);
332 return mtp_no_property;
338 * Follow the memory chain starting at node and determine
341 * @return mtp_property_const if only calls of const functions are detected
342 * mtp_property_pure if only Loads and const/pure calls detected
343 * mtp_no_property else
345 static unsigned follow_mem(ir_node *node, unsigned mode) {
348 m = _follow_mem(node);
349 return mode_max(mode, m);
353 * Check if a graph represents a const function.
355 * @param irg the graph
356 * @param top top call
358 static unsigned check_const_or_pure_function(ir_graph *irg, int top) {
359 ir_node *end, *endbl;
361 unsigned mode = get_irg_additional_properties(irg);
362 ir_graph *rem = current_ir_graph;
364 if (mode & mtp_property_const) {
365 /* already marked as a const function */
366 return mtp_property_const;
368 if (mode & mtp_property_pure) {
369 /* already marked as a pure function */
370 return mtp_property_pure;
373 if (IS_IRG_READY(irg)) {
374 /* already checked */
375 return mtp_no_property;
377 if (IS_IRG_BUSY(irg)) {
378 /* we are still evaluate this method. Be optimistic,
379 return the best possible so far but mark the result as temporary. */
380 return mtp_temporary | mtp_property_const;
384 end = get_irg_end(irg);
385 endbl = get_nodes_block(end);
386 mode = mtp_property_const;
388 current_ir_graph = irg;
390 inc_irg_visited(irg);
391 /* mark the initial mem: recursion of follow_mem stops here */
392 mark_irn_visited(get_irg_initial_mem(irg));
394 /* visit every Return */
395 for (j = get_Block_n_cfgpreds(endbl) - 1; j >= 0; --j) {
396 ir_node *node = get_Block_cfgpred(endbl, j);
397 ir_op *op = get_irn_op(node);
400 /* Bad nodes usually do NOT produce anything, so it's ok */
404 if (op == op_Return) {
405 mem = get_Return_mem(node);
407 /* Bad nodes usually do NOT produce anything, so it's ok */
411 if (mem != get_irg_initial_mem(irg))
412 mode = mode_max(mode, follow_mem(mem, mode));
414 /* Exception found. Cannot be const or pure. */
415 mode = mtp_no_property;
418 if (mode == mtp_no_property)
422 if (mode != mtp_no_property) {
423 /* check, if a keep-alive exists */
424 for (j = get_End_n_keepalives(end) - 1; j >= 0; --j) {
425 ir_node *mem = get_End_keepalive(end, j);
427 if (mode_M != get_irn_mode(mem))
430 mode = mode_max(mode, follow_mem(mem, mode));
431 if (mode == mtp_no_property)
436 if (mode != mtp_no_property) {
437 if (top || (mode & mtp_temporary) == 0) {
438 /* We use the temporary flag here to mark optimistic result.
439 Set the property only if we are sure that it does NOT base on
440 temporary results OR if we are at top-level. */
441 set_irg_additional_property(irg, mode & ~mtp_temporary);
448 current_ir_graph = rem;
450 } /* check_const_or_pure_function */
453 * Handle calls to const functions.
455 static void handle_const_Calls(env_t *ctx) {
458 ctx->n_calls_SymConst = 0;
459 ctx->n_calls_Sel = 0;
461 /* all calls of const functions can be transformed */
462 for (i = get_irp_n_irgs() - 1; i >= 0; --i) {
463 ir_graph *irg = get_irp_irg(i);
465 ctx->const_call_list = NULL;
466 ctx->pure_call_list = NULL;
467 ctx->proj_list = NULL;
468 irg_walk_graph(irg, NULL, collect_calls, ctx);
470 if (ctx->const_call_list)
471 fix_const_call_list(irg, ctx->const_call_list, ctx->proj_list);
473 } /* handle_const_Calls */
476 * optimize function calls by handling const functions
478 void optimize_funccalls(int force_run)
481 unsigned num_const = 0;
482 unsigned num_pure = 0;
484 /* prepare: mark all graphs as not analyzed */
485 n = get_irp_last_idx();
486 ready_set = rbitset_malloc(n);
487 busy_set = rbitset_malloc(n);
489 /* first step: detect, which functions are const, i.e. do NOT touch any memory */
490 DBG((dbg, LEVEL_2, "Detecting const and pure properties ...\n"));
491 for (i = n - 1; i >= 0; --i) {
492 ir_graph *irg = get_irp_irg(i);
493 unsigned mode = check_const_or_pure_function(irg, /*top=*/1);
495 if (mode & mtp_property_const) {
497 DBG((dbg, LEVEL_2, "%+F has the const property\n", irg));
498 } else if (mode & mtp_property_pure) {
500 DBG((dbg, LEVEL_2, "%+F has the pure property\n", irg));
504 if (force_run || num_const > 0) {
507 handle_const_Calls(&ctx);
508 if (get_firm_verbosity()) {
509 DBG((dbg, LEVEL_1, "Detected %u const graphs, %u pure graphs.\n", num_const, num_pure));
510 DBG((dbg, LEVEL_1, "Optimizes %u(SymConst) + %u(Sel) calls to const functions.\n",
511 ctx.n_calls_SymConst, ctx.n_calls_Sel));
514 DBG((dbg, LEVEL_1, "No graphs without side effects detected\n"));
518 } /* optimize_funccalls */
520 /* initialize the funccall optimization */
521 void firm_init_funccalls(void)
523 FIRM_DBG_REGISTER(dbg, "firm.opt.funccalls");
524 } /* firm_init_funccalls */