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5d94cf4d | 1 | /* Tail call optimization on trees. |
d353bf18 | 2 | Copyright (C) 2003-2015 Free Software Foundation, Inc. |
4ee9c684 | 3 | |
4 | This file is part of GCC. | |
5 | ||
6 | GCC is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8c4c00c1 | 8 | the Free Software Foundation; either version 3, or (at your option) |
4ee9c684 | 9 | any later version. |
10 | ||
11 | GCC is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
8c4c00c1 | 17 | along with GCC; see the file COPYING3. If not see |
18 | <http://www.gnu.org/licenses/>. */ | |
4ee9c684 | 19 | |
20 | #include "config.h" | |
21 | #include "system.h" | |
22 | #include "coretypes.h" | |
9ef16211 | 23 | #include "backend.h" |
7c29e30e | 24 | #include "target.h" |
25 | #include "rtl.h" | |
4ee9c684 | 26 | #include "tree.h" |
9ef16211 | 27 | #include "gimple.h" |
7c29e30e | 28 | #include "cfghooks.h" |
29 | #include "tree-pass.h" | |
30 | #include "tm_p.h" | |
9ef16211 | 31 | #include "ssa.h" |
7c29e30e | 32 | #include "expmed.h" |
33 | #include "insn-config.h" | |
34 | #include "emit-rtl.h" | |
35 | #include "cgraph.h" | |
36 | #include "gimple-pretty-print.h" | |
9ef16211 | 37 | #include "alias.h" |
b20a8bb4 | 38 | #include "fold-const.h" |
9ed99284 | 39 | #include "stor-layout.h" |
bc61cadb | 40 | #include "internal-fn.h" |
dcf1a1ec | 41 | #include "gimple-iterator.h" |
e795d6e1 | 42 | #include "gimplify-me.h" |
073c1fd5 | 43 | #include "tree-cfg.h" |
073c1fd5 | 44 | #include "tree-into-ssa.h" |
d53441c8 | 45 | #include "flags.h" |
d53441c8 | 46 | #include "dojump.h" |
47 | #include "explow.h" | |
48 | #include "calls.h" | |
d53441c8 | 49 | #include "varasm.h" |
50 | #include "stmt.h" | |
9ed99284 | 51 | #include "expr.h" |
073c1fd5 | 52 | #include "tree-dfa.h" |
4ee9c684 | 53 | #include "except.h" |
4ee9c684 | 54 | #include "langhooks.h" |
3072d30e | 55 | #include "dbgcnt.h" |
8ff30f9a | 56 | #include "cfgloop.h" |
218e3e4e | 57 | #include "common/common-target.h" |
e9de52cc | 58 | #include "ipa-utils.h" |
4ee9c684 | 59 | |
60 | /* The file implements the tail recursion elimination. It is also used to | |
365db11e | 61 | analyze the tail calls in general, passing the results to the rtl level |
4ee9c684 | 62 | where they are used for sibcall optimization. |
63 | ||
64 | In addition to the standard tail recursion elimination, we handle the most | |
65 | trivial cases of making the call tail recursive by creating accumulators. | |
66 | For example the following function | |
67 | ||
68 | int sum (int n) | |
69 | { | |
70 | if (n > 0) | |
71 | return n + sum (n - 1); | |
72 | else | |
73 | return 0; | |
74 | } | |
75 | ||
76 | is transformed into | |
77 | ||
78 | int sum (int n) | |
79 | { | |
80 | int acc = 0; | |
81 | ||
82 | while (n > 0) | |
83 | acc += n--; | |
84 | ||
85 | return acc; | |
86 | } | |
87 | ||
48e1416a | 88 | To do this, we maintain two accumulators (a_acc and m_acc) that indicate |
4ee9c684 | 89 | when we reach the return x statement, we should return a_acc + x * m_acc |
90 | instead. They are initially initialized to 0 and 1, respectively, | |
91 | so the semantics of the function is obviously preserved. If we are | |
92 | guaranteed that the value of the accumulator never change, we | |
93 | omit the accumulator. | |
94 | ||
95 | There are three cases how the function may exit. The first one is | |
fbac255a | 96 | handled in adjust_return_value, the other two in adjust_accumulator_values |
4ee9c684 | 97 | (the second case is actually a special case of the third one and we |
98 | present it separately just for clarity): | |
99 | ||
100 | 1) Just return x, where x is not in any of the remaining special shapes. | |
101 | We rewrite this to a gimple equivalent of return m_acc * x + a_acc. | |
48e1416a | 102 | |
4ee9c684 | 103 | 2) return f (...), where f is the current function, is rewritten in a |
365db11e | 104 | classical tail-recursion elimination way, into assignment of arguments |
4ee9c684 | 105 | and jump to the start of the function. Values of the accumulators |
106 | are unchanged. | |
48e1416a | 107 | |
4ee9c684 | 108 | 3) return a + m * f(...), where a and m do not depend on call to f. |
109 | To preserve the semantics described before we want this to be rewritten | |
110 | in such a way that we finally return | |
111 | ||
112 | a_acc + (a + m * f(...)) * m_acc = (a_acc + a * m_acc) + (m * m_acc) * f(...). | |
113 | ||
114 | I.e. we increase a_acc by a * m_acc, multiply m_acc by m and | |
115 | eliminate the tail call to f. Special cases when the value is just | |
116 | added or just multiplied are obtained by setting a = 0 or m = 1. | |
117 | ||
118 | TODO -- it is possible to do similar tricks for other operations. */ | |
119 | ||
120 | /* A structure that describes the tailcall. */ | |
121 | ||
122 | struct tailcall | |
123 | { | |
4ee9c684 | 124 | /* The iterator pointing to the call statement. */ |
75a70cf9 | 125 | gimple_stmt_iterator call_gsi; |
4ee9c684 | 126 | |
127 | /* True if it is a call to the current function. */ | |
128 | bool tail_recursion; | |
129 | ||
130 | /* The return value of the caller is mult * f + add, where f is the return | |
131 | value of the call. */ | |
132 | tree mult, add; | |
133 | ||
134 | /* Next tailcall in the chain. */ | |
135 | struct tailcall *next; | |
136 | }; | |
137 | ||
138 | /* The variables holding the value of multiplicative and additive | |
139 | accumulator. */ | |
140 | static tree m_acc, a_acc; | |
141 | ||
4ee9c684 | 142 | static bool optimize_tail_call (struct tailcall *, bool); |
143 | static void eliminate_tail_call (struct tailcall *); | |
4ee9c684 | 144 | |
145 | /* Returns false when the function is not suitable for tail call optimization | |
146 | from some reason (e.g. if it takes variable number of arguments). */ | |
147 | ||
148 | static bool | |
149 | suitable_for_tail_opt_p (void) | |
150 | { | |
18d50ae6 | 151 | if (cfun->stdarg) |
4ee9c684 | 152 | return false; |
153 | ||
4ee9c684 | 154 | return true; |
155 | } | |
156 | /* Returns false when the function is not suitable for tail call optimization | |
5c72dbe7 | 157 | for some reason (e.g. if it takes variable number of arguments). |
4ee9c684 | 158 | This test must pass in addition to suitable_for_tail_opt_p in order to make |
159 | tail call discovery happen. */ | |
160 | ||
161 | static bool | |
162 | suitable_for_tail_call_opt_p (void) | |
163 | { | |
6070c035 | 164 | tree param; |
165 | ||
4ee9c684 | 166 | /* alloca (until we have stack slot life analysis) inhibits |
167 | sibling call optimizations, but not tail recursion. */ | |
18d50ae6 | 168 | if (cfun->calls_alloca) |
4ee9c684 | 169 | return false; |
170 | ||
171 | /* If we are using sjlj exceptions, we may need to add a call to | |
172 | _Unwind_SjLj_Unregister at exit of the function. Which means | |
173 | that we cannot do any sibcall transformations. */ | |
218e3e4e | 174 | if (targetm_common.except_unwind_info (&global_options) == UI_SJLJ |
cc7d6aed | 175 | && current_function_has_exception_handlers ()) |
4ee9c684 | 176 | return false; |
177 | ||
178 | /* Any function that calls setjmp might have longjmp called from | |
179 | any called function. ??? We really should represent this | |
180 | properly in the CFG so that this needn't be special cased. */ | |
18d50ae6 | 181 | if (cfun->calls_setjmp) |
4ee9c684 | 182 | return false; |
183 | ||
6070c035 | 184 | /* ??? It is OK if the argument of a function is taken in some cases, |
185 | but not in all cases. See PR15387 and PR19616. Revisit for 4.1. */ | |
186 | for (param = DECL_ARGUMENTS (current_function_decl); | |
187 | param; | |
1767a056 | 188 | param = DECL_CHAIN (param)) |
6070c035 | 189 | if (TREE_ADDRESSABLE (param)) |
190 | return false; | |
191 | ||
4ee9c684 | 192 | return true; |
193 | } | |
194 | ||
195 | /* Checks whether the expression EXPR in stmt AT is independent of the | |
75a70cf9 | 196 | statement pointed to by GSI (in a sense that we already know EXPR's value |
197 | at GSI). We use the fact that we are only called from the chain of | |
4ee9c684 | 198 | basic blocks that have only single successor. Returns the expression |
75a70cf9 | 199 | containing the value of EXPR at GSI. */ |
4ee9c684 | 200 | |
201 | static tree | |
42acab1c | 202 | independent_of_stmt_p (tree expr, gimple *at, gimple_stmt_iterator gsi) |
4ee9c684 | 203 | { |
204 | basic_block bb, call_bb, at_bb; | |
205 | edge e; | |
cd665a06 | 206 | edge_iterator ei; |
4ee9c684 | 207 | |
208 | if (is_gimple_min_invariant (expr)) | |
209 | return expr; | |
210 | ||
211 | if (TREE_CODE (expr) != SSA_NAME) | |
212 | return NULL_TREE; | |
213 | ||
214 | /* Mark the blocks in the chain leading to the end. */ | |
75a70cf9 | 215 | at_bb = gimple_bb (at); |
216 | call_bb = gimple_bb (gsi_stmt (gsi)); | |
ea091dfd | 217 | for (bb = call_bb; bb != at_bb; bb = single_succ (bb)) |
4ee9c684 | 218 | bb->aux = &bb->aux; |
219 | bb->aux = &bb->aux; | |
220 | ||
221 | while (1) | |
48e1416a | 222 | { |
4ee9c684 | 223 | at = SSA_NAME_DEF_STMT (expr); |
75a70cf9 | 224 | bb = gimple_bb (at); |
4ee9c684 | 225 | |
2c763ed4 | 226 | /* The default definition or defined before the chain. */ |
4ee9c684 | 227 | if (!bb || !bb->aux) |
228 | break; | |
229 | ||
230 | if (bb == call_bb) | |
231 | { | |
75a70cf9 | 232 | for (; !gsi_end_p (gsi); gsi_next (&gsi)) |
233 | if (gsi_stmt (gsi) == at) | |
4ee9c684 | 234 | break; |
235 | ||
75a70cf9 | 236 | if (!gsi_end_p (gsi)) |
4ee9c684 | 237 | expr = NULL_TREE; |
238 | break; | |
239 | } | |
240 | ||
75a70cf9 | 241 | if (gimple_code (at) != GIMPLE_PHI) |
4ee9c684 | 242 | { |
243 | expr = NULL_TREE; | |
244 | break; | |
245 | } | |
246 | ||
cd665a06 | 247 | FOR_EACH_EDGE (e, ei, bb->preds) |
4ee9c684 | 248 | if (e->src->aux) |
249 | break; | |
8c0963c4 | 250 | gcc_assert (e); |
4ee9c684 | 251 | |
56004dc5 | 252 | expr = PHI_ARG_DEF_FROM_EDGE (at, e); |
634f6ce0 | 253 | if (TREE_CODE (expr) != SSA_NAME) |
254 | { | |
255 | /* The value is a constant. */ | |
256 | break; | |
257 | } | |
4ee9c684 | 258 | } |
259 | ||
260 | /* Unmark the blocks. */ | |
ea091dfd | 261 | for (bb = call_bb; bb != at_bb; bb = single_succ (bb)) |
4ee9c684 | 262 | bb->aux = NULL; |
263 | bb->aux = NULL; | |
264 | ||
265 | return expr; | |
266 | } | |
267 | ||
75a70cf9 | 268 | /* Simulates the effect of an assignment STMT on the return value of the tail |
269 | recursive CALL passed in ASS_VAR. M and A are the multiplicative and the | |
270 | additive factor for the real return value. */ | |
4ee9c684 | 271 | |
272 | static bool | |
1a91d914 | 273 | process_assignment (gassign *stmt, gimple_stmt_iterator call, tree *m, |
4ee9c684 | 274 | tree *a, tree *ass_var) |
275 | { | |
dd8277d9 | 276 | tree op0, op1 = NULL_TREE, non_ass_var = NULL_TREE; |
75a70cf9 | 277 | tree dest = gimple_assign_lhs (stmt); |
278 | enum tree_code code = gimple_assign_rhs_code (stmt); | |
279 | enum gimple_rhs_class rhs_class = get_gimple_rhs_class (code); | |
280 | tree src_var = gimple_assign_rhs1 (stmt); | |
48e1416a | 281 | |
cefc957d | 282 | /* See if this is a simple copy operation of an SSA name to the function |
283 | result. In that case we may have a simple tail call. Ignore type | |
284 | conversions that can never produce extra code between the function | |
285 | call and the function return. */ | |
75a70cf9 | 286 | if ((rhs_class == GIMPLE_SINGLE_RHS || gimple_assign_cast_p (stmt)) |
287 | && (TREE_CODE (src_var) == SSA_NAME)) | |
4ee9c684 | 288 | { |
75a70cf9 | 289 | /* Reject a tailcall if the type conversion might need |
290 | additional code. */ | |
b1562bbb | 291 | if (gimple_assign_cast_p (stmt)) |
292 | { | |
293 | if (TYPE_MODE (TREE_TYPE (dest)) != TYPE_MODE (TREE_TYPE (src_var))) | |
294 | return false; | |
295 | ||
296 | /* Even if the type modes are the same, if the precision of the | |
297 | type is smaller than mode's precision, | |
298 | reduce_to_bit_field_precision would generate additional code. */ | |
299 | if (INTEGRAL_TYPE_P (TREE_TYPE (dest)) | |
300 | && (GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (dest))) | |
301 | > TYPE_PRECISION (TREE_TYPE (dest)))) | |
302 | return false; | |
303 | } | |
75a70cf9 | 304 | |
cefc957d | 305 | if (src_var != *ass_var) |
4ee9c684 | 306 | return false; |
307 | ||
308 | *ass_var = dest; | |
309 | return true; | |
310 | } | |
311 | ||
dd8277d9 | 312 | switch (rhs_class) |
313 | { | |
314 | case GIMPLE_BINARY_RHS: | |
315 | op1 = gimple_assign_rhs2 (stmt); | |
316 | ||
317 | /* Fall through. */ | |
318 | ||
319 | case GIMPLE_UNARY_RHS: | |
320 | op0 = gimple_assign_rhs1 (stmt); | |
321 | break; | |
322 | ||
323 | default: | |
324 | return false; | |
325 | } | |
4ee9c684 | 326 | |
9cff5cbd | 327 | /* Accumulator optimizations will reverse the order of operations. |
328 | We can only do that for floating-point types if we're assuming | |
329 | that addition and multiplication are associative. */ | |
49d060d7 | 330 | if (!flag_associative_math) |
9cff5cbd | 331 | if (FLOAT_TYPE_P (TREE_TYPE (DECL_RESULT (current_function_decl)))) |
332 | return false; | |
333 | ||
dd8277d9 | 334 | if (rhs_class == GIMPLE_UNARY_RHS) |
335 | ; | |
336 | else if (op0 == *ass_var | |
a6f8b9b9 | 337 | && (non_ass_var = independent_of_stmt_p (op1, stmt, call))) |
4ee9c684 | 338 | ; |
339 | else if (op1 == *ass_var | |
340 | && (non_ass_var = independent_of_stmt_p (op0, stmt, call))) | |
341 | ; | |
342 | else | |
343 | return false; | |
344 | ||
cefc957d | 345 | switch (code) |
4ee9c684 | 346 | { |
347 | case PLUS_EXPR: | |
4ee9c684 | 348 | *a = non_ass_var; |
349 | *ass_var = dest; | |
350 | return true; | |
351 | ||
a6f8b9b9 | 352 | case POINTER_PLUS_EXPR: |
353 | if (op0 != *ass_var) | |
354 | return false; | |
355 | *a = non_ass_var; | |
356 | *ass_var = dest; | |
357 | return true; | |
358 | ||
4ee9c684 | 359 | case MULT_EXPR: |
4ee9c684 | 360 | *m = non_ass_var; |
361 | *ass_var = dest; | |
362 | return true; | |
363 | ||
dd8277d9 | 364 | case NEGATE_EXPR: |
e53c294c | 365 | *m = build_minus_one_cst (TREE_TYPE (op0)); |
dd8277d9 | 366 | *ass_var = dest; |
367 | return true; | |
368 | ||
369 | case MINUS_EXPR: | |
370 | if (*ass_var == op0) | |
371 | *a = fold_build1 (NEGATE_EXPR, TREE_TYPE (non_ass_var), non_ass_var); | |
372 | else | |
373 | { | |
e53c294c | 374 | *m = build_minus_one_cst (TREE_TYPE (non_ass_var)); |
dd8277d9 | 375 | *a = fold_build1 (NEGATE_EXPR, TREE_TYPE (non_ass_var), non_ass_var); |
376 | } | |
377 | ||
378 | *ass_var = dest; | |
379 | return true; | |
380 | ||
381 | /* TODO -- Handle POINTER_PLUS_EXPR. */ | |
4ee9c684 | 382 | |
383 | default: | |
384 | return false; | |
385 | } | |
386 | } | |
387 | ||
388 | /* Propagate VAR through phis on edge E. */ | |
389 | ||
390 | static tree | |
391 | propagate_through_phis (tree var, edge e) | |
392 | { | |
393 | basic_block dest = e->dest; | |
1a91d914 | 394 | gphi_iterator gsi; |
48e1416a | 395 | |
75a70cf9 | 396 | for (gsi = gsi_start_phis (dest); !gsi_end_p (gsi); gsi_next (&gsi)) |
397 | { | |
1a91d914 | 398 | gphi *phi = gsi.phi (); |
75a70cf9 | 399 | if (PHI_ARG_DEF_FROM_EDGE (phi, e) == var) |
400 | return PHI_RESULT (phi); | |
401 | } | |
4ee9c684 | 402 | return var; |
403 | } | |
404 | ||
405 | /* Finds tailcalls falling into basic block BB. The list of found tailcalls is | |
406 | added to the start of RET. */ | |
407 | ||
408 | static void | |
409 | find_tail_calls (basic_block bb, struct tailcall **ret) | |
410 | { | |
75a70cf9 | 411 | tree ass_var = NULL_TREE, ret_var, func, param; |
42acab1c | 412 | gimple *stmt; |
1a91d914 | 413 | gcall *call = NULL; |
75a70cf9 | 414 | gimple_stmt_iterator gsi, agsi; |
4ee9c684 | 415 | bool tail_recursion; |
416 | struct tailcall *nw; | |
417 | edge e; | |
418 | tree m, a; | |
419 | basic_block abb; | |
75a70cf9 | 420 | size_t idx; |
4debfcfc | 421 | tree var; |
4ee9c684 | 422 | |
ea091dfd | 423 | if (!single_succ_p (bb)) |
4ee9c684 | 424 | return; |
425 | ||
75a70cf9 | 426 | for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi); gsi_prev (&gsi)) |
4ee9c684 | 427 | { |
75a70cf9 | 428 | stmt = gsi_stmt (gsi); |
4ee9c684 | 429 | |
97effc09 | 430 | /* Ignore labels, returns, clobbers and debug stmts. */ |
2109076a | 431 | if (gimple_code (stmt) == GIMPLE_LABEL |
432 | || gimple_code (stmt) == GIMPLE_RETURN | |
97effc09 | 433 | || gimple_clobber_p (stmt) |
2109076a | 434 | || is_gimple_debug (stmt)) |
4ee9c684 | 435 | continue; |
436 | ||
4ee9c684 | 437 | /* Check for a call. */ |
75a70cf9 | 438 | if (is_gimple_call (stmt)) |
4ee9c684 | 439 | { |
1a91d914 | 440 | call = as_a <gcall *> (stmt); |
441 | ass_var = gimple_call_lhs (call); | |
75a70cf9 | 442 | break; |
4ee9c684 | 443 | } |
444 | ||
dd277d48 | 445 | /* If the statement references memory or volatile operands, fail. */ |
446 | if (gimple_references_memory_p (stmt) | |
447 | || gimple_has_volatile_ops (stmt)) | |
4ee9c684 | 448 | return; |
449 | } | |
450 | ||
75a70cf9 | 451 | if (gsi_end_p (gsi)) |
4ee9c684 | 452 | { |
cd665a06 | 453 | edge_iterator ei; |
4ee9c684 | 454 | /* Recurse to the predecessors. */ |
cd665a06 | 455 | FOR_EACH_EDGE (e, ei, bb->preds) |
4ee9c684 | 456 | find_tail_calls (e->src, ret); |
457 | ||
458 | return; | |
459 | } | |
460 | ||
48e1416a | 461 | /* If the LHS of our call is not just a simple register, we can't |
7528fb13 | 462 | transform this into a tail or sibling call. This situation happens, |
463 | in (e.g.) "*p = foo()" where foo returns a struct. In this case | |
464 | we won't have a temporary here, but we need to carry out the side | |
465 | effect anyway, so tailcall is impossible. | |
466 | ||
467 | ??? In some situations (when the struct is returned in memory via | |
468 | invisible argument) we could deal with this, e.g. by passing 'p' | |
469 | itself as that argument to foo, but it's too early to do this here, | |
470 | and expand_call() will not handle it anyway. If it ever can, then | |
471 | we need to revisit this here, to allow that situation. */ | |
472 | if (ass_var && !is_gimple_reg (ass_var)) | |
473 | return; | |
474 | ||
4ee9c684 | 475 | /* We found the call, check whether it is suitable. */ |
476 | tail_recursion = false; | |
75a70cf9 | 477 | func = gimple_call_fndecl (call); |
89432048 | 478 | if (func |
479 | && !DECL_BUILT_IN (func) | |
480 | && recursive_call_p (current_function_decl, func)) | |
4ee9c684 | 481 | { |
4debfcfc | 482 | tree arg; |
cb245216 | 483 | |
75a70cf9 | 484 | for (param = DECL_ARGUMENTS (func), idx = 0; |
485 | param && idx < gimple_call_num_args (call); | |
1767a056 | 486 | param = DECL_CHAIN (param), idx ++) |
4ee9c684 | 487 | { |
75a70cf9 | 488 | arg = gimple_call_arg (call, idx); |
d4e3bde0 | 489 | if (param != arg) |
490 | { | |
491 | /* Make sure there are no problems with copying. The parameter | |
4ee9c684 | 492 | have a copyable type and the two arguments must have reasonably |
493 | equivalent types. The latter requirement could be relaxed if | |
494 | we emitted a suitable type conversion statement. */ | |
d4e3bde0 | 495 | if (!is_gimple_reg_type (TREE_TYPE (param)) |
c8ca3ee7 | 496 | || !useless_type_conversion_p (TREE_TYPE (param), |
75a70cf9 | 497 | TREE_TYPE (arg))) |
d4e3bde0 | 498 | break; |
499 | ||
500 | /* The parameter should be a real operand, so that phi node | |
501 | created for it at the start of the function has the meaning | |
502 | of copying the value. This test implies is_gimple_reg_type | |
503 | from the previous condition, however this one could be | |
504 | relaxed by being more careful with copying the new value | |
75a70cf9 | 505 | of the parameter (emitting appropriate GIMPLE_ASSIGN and |
d4e3bde0 | 506 | updating the virtual operands). */ |
507 | if (!is_gimple_reg (param)) | |
508 | break; | |
509 | } | |
4ee9c684 | 510 | } |
75a70cf9 | 511 | if (idx == gimple_call_num_args (call) && !param) |
4ee9c684 | 512 | tail_recursion = true; |
4debfcfc | 513 | } |
cb245216 | 514 | |
4debfcfc | 515 | /* Make sure the tail invocation of this function does not refer |
516 | to local variables. */ | |
24ccd9c6 | 517 | FOR_EACH_LOCAL_DECL (cfun, idx, var) |
4debfcfc | 518 | { |
8081b5e7 | 519 | if (TREE_CODE (var) != PARM_DECL |
520 | && auto_var_in_fn_p (var, cfun->decl) | |
40a61243 | 521 | && (ref_maybe_used_by_stmt_p (call, var) |
522 | || call_may_clobber_ref_p (call, var))) | |
4debfcfc | 523 | return; |
4ee9c684 | 524 | } |
525 | ||
526 | /* Now check the statements after the call. None of them has virtual | |
527 | operands, so they may only depend on the call through its return | |
528 | value. The return value should also be dependent on each of them, | |
529 | since we are running after dce. */ | |
530 | m = NULL_TREE; | |
531 | a = NULL_TREE; | |
532 | ||
533 | abb = bb; | |
75a70cf9 | 534 | agsi = gsi; |
4ee9c684 | 535 | while (1) |
536 | { | |
4e32b1c1 | 537 | tree tmp_a = NULL_TREE; |
538 | tree tmp_m = NULL_TREE; | |
75a70cf9 | 539 | gsi_next (&agsi); |
4ee9c684 | 540 | |
75a70cf9 | 541 | while (gsi_end_p (agsi)) |
4ee9c684 | 542 | { |
ea091dfd | 543 | ass_var = propagate_through_phis (ass_var, single_succ_edge (abb)); |
544 | abb = single_succ (abb); | |
75a70cf9 | 545 | agsi = gsi_start_bb (abb); |
4ee9c684 | 546 | } |
547 | ||
75a70cf9 | 548 | stmt = gsi_stmt (agsi); |
4ee9c684 | 549 | |
75a70cf9 | 550 | if (gimple_code (stmt) == GIMPLE_LABEL) |
4ee9c684 | 551 | continue; |
552 | ||
75a70cf9 | 553 | if (gimple_code (stmt) == GIMPLE_RETURN) |
4ee9c684 | 554 | break; |
555 | ||
97effc09 | 556 | if (gimple_clobber_p (stmt)) |
557 | continue; | |
558 | ||
9845d120 | 559 | if (is_gimple_debug (stmt)) |
560 | continue; | |
561 | ||
75a70cf9 | 562 | if (gimple_code (stmt) != GIMPLE_ASSIGN) |
4ee9c684 | 563 | return; |
564 | ||
75a70cf9 | 565 | /* This is a gimple assign. */ |
1a91d914 | 566 | if (! process_assignment (as_a <gassign *> (stmt), gsi, &tmp_m, |
567 | &tmp_a, &ass_var)) | |
4ee9c684 | 568 | return; |
4e32b1c1 | 569 | |
570 | if (tmp_a) | |
571 | { | |
17297953 | 572 | tree type = TREE_TYPE (tmp_a); |
4e32b1c1 | 573 | if (a) |
17297953 | 574 | a = fold_build2 (PLUS_EXPR, type, fold_convert (type, a), tmp_a); |
4e32b1c1 | 575 | else |
576 | a = tmp_a; | |
577 | } | |
578 | if (tmp_m) | |
579 | { | |
17297953 | 580 | tree type = TREE_TYPE (tmp_m); |
4e32b1c1 | 581 | if (m) |
17297953 | 582 | m = fold_build2 (MULT_EXPR, type, fold_convert (type, m), tmp_m); |
4e32b1c1 | 583 | else |
584 | m = tmp_m; | |
585 | ||
586 | if (a) | |
17297953 | 587 | a = fold_build2 (MULT_EXPR, type, fold_convert (type, a), tmp_m); |
4e32b1c1 | 588 | } |
4ee9c684 | 589 | } |
590 | ||
cefc957d | 591 | /* See if this is a tail call we can handle. */ |
1a91d914 | 592 | ret_var = gimple_return_retval (as_a <greturn *> (stmt)); |
4ee9c684 | 593 | |
594 | /* We may proceed if there either is no return value, or the return value | |
595 | is identical to the call's return. */ | |
596 | if (ret_var | |
597 | && (ret_var != ass_var)) | |
598 | return; | |
599 | ||
6108f5dd | 600 | /* If this is not a tail recursive call, we cannot handle addends or |
601 | multiplicands. */ | |
602 | if (!tail_recursion && (m || a)) | |
603 | return; | |
604 | ||
a6f8b9b9 | 605 | /* For pointers only allow additions. */ |
606 | if (m && POINTER_TYPE_P (TREE_TYPE (DECL_RESULT (current_function_decl)))) | |
607 | return; | |
608 | ||
945865c5 | 609 | nw = XNEW (struct tailcall); |
4ee9c684 | 610 | |
75a70cf9 | 611 | nw->call_gsi = gsi; |
4ee9c684 | 612 | |
613 | nw->tail_recursion = tail_recursion; | |
614 | ||
615 | nw->mult = m; | |
616 | nw->add = a; | |
617 | ||
618 | nw->next = *ret; | |
619 | *ret = nw; | |
620 | } | |
621 | ||
75a70cf9 | 622 | /* Helper to insert PHI_ARGH to the phi of VAR in the destination of edge E. */ |
4ee9c684 | 623 | |
624 | static void | |
75a70cf9 | 625 | add_successor_phi_arg (edge e, tree var, tree phi_arg) |
626 | { | |
1a91d914 | 627 | gphi_iterator gsi; |
75a70cf9 | 628 | |
629 | for (gsi = gsi_start_phis (e->dest); !gsi_end_p (gsi); gsi_next (&gsi)) | |
1a91d914 | 630 | if (PHI_RESULT (gsi.phi ()) == var) |
75a70cf9 | 631 | break; |
632 | ||
633 | gcc_assert (!gsi_end_p (gsi)); | |
1a91d914 | 634 | add_phi_arg (gsi.phi (), phi_arg, e, UNKNOWN_LOCATION); |
75a70cf9 | 635 | } |
636 | ||
637 | /* Creates a GIMPLE statement which computes the operation specified by | |
f5c4bbcd | 638 | CODE, ACC and OP1 to a new variable with name LABEL and inserts the |
639 | statement in the position specified by GSI. Returns the | |
75a70cf9 | 640 | tree node of the statement's result. */ |
641 | ||
642 | static tree | |
48e1416a | 643 | adjust_return_value_with_ops (enum tree_code code, const char *label, |
bc56c183 | 644 | tree acc, tree op1, gimple_stmt_iterator gsi) |
4ee9c684 | 645 | { |
75a70cf9 | 646 | |
4ee9c684 | 647 | tree ret_type = TREE_TYPE (DECL_RESULT (current_function_decl)); |
03d37e4e | 648 | tree result = make_temp_ssa_name (ret_type, NULL, label); |
1a91d914 | 649 | gassign *stmt; |
75a70cf9 | 650 | |
a6f8b9b9 | 651 | if (POINTER_TYPE_P (ret_type)) |
652 | { | |
653 | gcc_assert (code == PLUS_EXPR && TREE_TYPE (acc) == sizetype); | |
654 | code = POINTER_PLUS_EXPR; | |
655 | } | |
656 | if (types_compatible_p (TREE_TYPE (acc), TREE_TYPE (op1)) | |
657 | && code != POINTER_PLUS_EXPR) | |
e9cf809e | 658 | stmt = gimple_build_assign (result, code, acc, op1); |
bc56c183 | 659 | else |
660 | { | |
a6f8b9b9 | 661 | tree tem; |
662 | if (code == POINTER_PLUS_EXPR) | |
663 | tem = fold_build2 (code, TREE_TYPE (op1), op1, acc); | |
664 | else | |
665 | tem = fold_build2 (code, TREE_TYPE (op1), | |
666 | fold_convert (TREE_TYPE (op1), acc), op1); | |
667 | tree rhs = fold_convert (ret_type, tem); | |
bc56c183 | 668 | rhs = force_gimple_operand_gsi (&gsi, rhs, |
f5c4bbcd | 669 | false, NULL, true, GSI_SAME_STMT); |
03d37e4e | 670 | stmt = gimple_build_assign (result, rhs); |
bc56c183 | 671 | } |
672 | ||
bc56c183 | 673 | gsi_insert_before (&gsi, stmt, GSI_NEW_STMT); |
75a70cf9 | 674 | return result; |
675 | } | |
676 | ||
48e1416a | 677 | /* Creates a new GIMPLE statement that adjusts the value of accumulator ACC by |
75a70cf9 | 678 | the computation specified by CODE and OP1 and insert the statement |
679 | at the position specified by GSI as a new statement. Returns new SSA name | |
680 | of updated accumulator. */ | |
681 | ||
682 | static tree | |
683 | update_accumulator_with_ops (enum tree_code code, tree acc, tree op1, | |
684 | gimple_stmt_iterator gsi) | |
685 | { | |
1a91d914 | 686 | gassign *stmt; |
f9e245b2 | 687 | tree var = copy_ssa_name (acc); |
bc56c183 | 688 | if (types_compatible_p (TREE_TYPE (acc), TREE_TYPE (op1))) |
e9cf809e | 689 | stmt = gimple_build_assign (var, code, acc, op1); |
bc56c183 | 690 | else |
691 | { | |
692 | tree rhs = fold_convert (TREE_TYPE (acc), | |
693 | fold_build2 (code, | |
694 | TREE_TYPE (op1), | |
695 | fold_convert (TREE_TYPE (op1), acc), | |
696 | op1)); | |
697 | rhs = force_gimple_operand_gsi (&gsi, rhs, | |
698 | false, NULL, false, GSI_CONTINUE_LINKING); | |
874117c8 | 699 | stmt = gimple_build_assign (var, rhs); |
bc56c183 | 700 | } |
75a70cf9 | 701 | gsi_insert_after (&gsi, stmt, GSI_NEW_STMT); |
702 | return var; | |
703 | } | |
704 | ||
705 | /* Adjust the accumulator values according to A and M after GSI, and update | |
706 | the phi nodes on edge BACK. */ | |
707 | ||
708 | static void | |
709 | adjust_accumulator_values (gimple_stmt_iterator gsi, tree m, tree a, edge back) | |
710 | { | |
4e32b1c1 | 711 | tree var, a_acc_arg, m_acc_arg; |
712 | ||
713 | if (m) | |
714 | m = force_gimple_operand_gsi (&gsi, m, true, NULL, true, GSI_SAME_STMT); | |
715 | if (a) | |
716 | a = force_gimple_operand_gsi (&gsi, a, true, NULL, true, GSI_SAME_STMT); | |
4ee9c684 | 717 | |
4e32b1c1 | 718 | a_acc_arg = a_acc; |
719 | m_acc_arg = m_acc; | |
4ee9c684 | 720 | if (a) |
721 | { | |
722 | if (m_acc) | |
723 | { | |
724 | if (integer_onep (a)) | |
725 | var = m_acc; | |
726 | else | |
75a70cf9 | 727 | var = adjust_return_value_with_ops (MULT_EXPR, "acc_tmp", m_acc, |
bc56c183 | 728 | a, gsi); |
4ee9c684 | 729 | } |
730 | else | |
731 | var = a; | |
732 | ||
75a70cf9 | 733 | a_acc_arg = update_accumulator_with_ops (PLUS_EXPR, a_acc, var, gsi); |
4ee9c684 | 734 | } |
735 | ||
736 | if (m) | |
75a70cf9 | 737 | m_acc_arg = update_accumulator_with_ops (MULT_EXPR, m_acc, m, gsi); |
4ee9c684 | 738 | |
739 | if (a_acc) | |
75a70cf9 | 740 | add_successor_phi_arg (back, a_acc, a_acc_arg); |
4ee9c684 | 741 | |
742 | if (m_acc) | |
75a70cf9 | 743 | add_successor_phi_arg (back, m_acc, m_acc_arg); |
4ee9c684 | 744 | } |
745 | ||
365db11e | 746 | /* Adjust value of the return at the end of BB according to M and A |
4ee9c684 | 747 | accumulators. */ |
748 | ||
749 | static void | |
750 | adjust_return_value (basic_block bb, tree m, tree a) | |
751 | { | |
75a70cf9 | 752 | tree retval; |
1a91d914 | 753 | greturn *ret_stmt = as_a <greturn *> (gimple_seq_last_stmt (bb_seq (bb))); |
75a70cf9 | 754 | gimple_stmt_iterator gsi = gsi_last_bb (bb); |
4ee9c684 | 755 | |
75a70cf9 | 756 | gcc_assert (gimple_code (ret_stmt) == GIMPLE_RETURN); |
4ee9c684 | 757 | |
75a70cf9 | 758 | retval = gimple_return_retval (ret_stmt); |
759 | if (!retval || retval == error_mark_node) | |
4ee9c684 | 760 | return; |
761 | ||
4ee9c684 | 762 | if (m) |
75a70cf9 | 763 | retval = adjust_return_value_with_ops (MULT_EXPR, "mul_tmp", m_acc, retval, |
bc56c183 | 764 | gsi); |
4ee9c684 | 765 | if (a) |
75a70cf9 | 766 | retval = adjust_return_value_with_ops (PLUS_EXPR, "acc_tmp", a_acc, retval, |
bc56c183 | 767 | gsi); |
75a70cf9 | 768 | gimple_return_set_retval (ret_stmt, retval); |
22aa74c4 | 769 | update_stmt (ret_stmt); |
4ee9c684 | 770 | } |
771 | ||
8dc7fca4 | 772 | /* Subtract COUNT and FREQUENCY from the basic block and it's |
773 | outgoing edge. */ | |
774 | static void | |
775 | decrease_profile (basic_block bb, gcov_type count, int frequency) | |
776 | { | |
777 | edge e; | |
778 | bb->count -= count; | |
779 | if (bb->count < 0) | |
780 | bb->count = 0; | |
781 | bb->frequency -= frequency; | |
782 | if (bb->frequency < 0) | |
783 | bb->frequency = 0; | |
784 | if (!single_succ_p (bb)) | |
785 | { | |
786 | gcc_assert (!EDGE_COUNT (bb->succs)); | |
787 | return; | |
788 | } | |
789 | e = single_succ_edge (bb); | |
790 | e->count -= count; | |
791 | if (e->count < 0) | |
792 | e->count = 0; | |
793 | } | |
794 | ||
4304657c | 795 | /* Returns true if argument PARAM of the tail recursive call needs to be copied |
796 | when the call is eliminated. */ | |
797 | ||
798 | static bool | |
799 | arg_needs_copy_p (tree param) | |
800 | { | |
801 | tree def; | |
802 | ||
4ae5778c | 803 | if (!is_gimple_reg (param)) |
4304657c | 804 | return false; |
48e1416a | 805 | |
4304657c | 806 | /* Parameters that are only defined but never used need not be copied. */ |
c6dfe037 | 807 | def = ssa_default_def (cfun, param); |
4304657c | 808 | if (!def) |
809 | return false; | |
810 | ||
811 | return true; | |
812 | } | |
813 | ||
4ee9c684 | 814 | /* Eliminates tail call described by T. TMP_VARS is a list of |
815 | temporary variables used to copy the function arguments. */ | |
816 | ||
817 | static void | |
818 | eliminate_tail_call (struct tailcall *t) | |
819 | { | |
75a70cf9 | 820 | tree param, rslt; |
42acab1c | 821 | gimple *stmt, *call; |
c2f47e15 | 822 | tree arg; |
75a70cf9 | 823 | size_t idx; |
4ee9c684 | 824 | basic_block bb, first; |
825 | edge e; | |
1a91d914 | 826 | gphi *phi; |
827 | gphi_iterator gpi; | |
75a70cf9 | 828 | gimple_stmt_iterator gsi; |
42acab1c | 829 | gimple *orig_stmt; |
4ee9c684 | 830 | |
75a70cf9 | 831 | stmt = orig_stmt = gsi_stmt (t->call_gsi); |
832 | bb = gsi_bb (t->call_gsi); | |
4ee9c684 | 833 | |
834 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
835 | { | |
836 | fprintf (dump_file, "Eliminated tail recursion in bb %d : ", | |
837 | bb->index); | |
75a70cf9 | 838 | print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM); |
4ee9c684 | 839 | fprintf (dump_file, "\n"); |
840 | } | |
841 | ||
75a70cf9 | 842 | gcc_assert (is_gimple_call (stmt)); |
4ee9c684 | 843 | |
34154e27 | 844 | first = single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun)); |
4ee9c684 | 845 | |
75a70cf9 | 846 | /* Remove the code after call_gsi that will become unreachable. The |
18a87dc5 | 847 | possibly unreachable code in other blocks is removed later in |
848 | cfg cleanup. */ | |
75a70cf9 | 849 | gsi = t->call_gsi; |
df8d8dce | 850 | gimple_stmt_iterator gsi2 = gsi_last_bb (gimple_bb (gsi_stmt (gsi))); |
851 | while (gsi_stmt (gsi2) != gsi_stmt (gsi)) | |
18a87dc5 | 852 | { |
df8d8dce | 853 | gimple *t = gsi_stmt (gsi2); |
18a87dc5 | 854 | /* Do not remove the return statement, so that redirect_edge_and_branch |
855 | sees how the block ends. */ | |
df8d8dce | 856 | if (gimple_code (t) != GIMPLE_RETURN) |
857 | { | |
858 | gimple_stmt_iterator gsi3 = gsi2; | |
859 | gsi_prev (&gsi2); | |
860 | gsi_remove (&gsi3, true); | |
861 | release_defs (t); | |
862 | } | |
863 | else | |
864 | gsi_prev (&gsi2); | |
18a87dc5 | 865 | } |
866 | ||
8dc7fca4 | 867 | /* Number of executions of function has reduced by the tailcall. */ |
75a70cf9 | 868 | e = single_succ_edge (gsi_bb (t->call_gsi)); |
34154e27 | 869 | decrease_profile (EXIT_BLOCK_PTR_FOR_FN (cfun), e->count, EDGE_FREQUENCY (e)); |
870 | decrease_profile (ENTRY_BLOCK_PTR_FOR_FN (cfun), e->count, | |
871 | EDGE_FREQUENCY (e)); | |
872 | if (e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun)) | |
8dc7fca4 | 873 | decrease_profile (e->dest, e->count, EDGE_FREQUENCY (e)); |
874 | ||
4ee9c684 | 875 | /* Replace the call by a jump to the start of function. */ |
75a70cf9 | 876 | e = redirect_edge_and_branch (single_succ_edge (gsi_bb (t->call_gsi)), |
877 | first); | |
8c0963c4 | 878 | gcc_assert (e); |
75a70cf9 | 879 | PENDING_STMT (e) = NULL; |
4ee9c684 | 880 | |
4304657c | 881 | /* Add phi node entries for arguments. The ordering of the phi nodes should |
882 | be the same as the ordering of the arguments. */ | |
4ee9c684 | 883 | for (param = DECL_ARGUMENTS (current_function_decl), |
1a91d914 | 884 | idx = 0, gpi = gsi_start_phis (first); |
4ee9c684 | 885 | param; |
1767a056 | 886 | param = DECL_CHAIN (param), idx++) |
4ee9c684 | 887 | { |
4304657c | 888 | if (!arg_needs_copy_p (param)) |
4ee9c684 | 889 | continue; |
75a70cf9 | 890 | |
891 | arg = gimple_call_arg (stmt, idx); | |
1a91d914 | 892 | phi = gpi.phi (); |
4304657c | 893 | gcc_assert (param == SSA_NAME_VAR (PHI_RESULT (phi))); |
4ee9c684 | 894 | |
60d535d2 | 895 | add_phi_arg (phi, arg, e, gimple_location (stmt)); |
1a91d914 | 896 | gsi_next (&gpi); |
4ee9c684 | 897 | } |
898 | ||
899 | /* Update the values of accumulators. */ | |
75a70cf9 | 900 | adjust_accumulator_values (t->call_gsi, t->mult, t->add, e); |
4ee9c684 | 901 | |
75a70cf9 | 902 | call = gsi_stmt (t->call_gsi); |
903 | rslt = gimple_call_lhs (call); | |
904 | if (rslt != NULL_TREE) | |
4ee9c684 | 905 | { |
4ee9c684 | 906 | /* Result of the call will no longer be defined. So adjust the |
907 | SSA_NAME_DEF_STMT accordingly. */ | |
75a70cf9 | 908 | SSA_NAME_DEF_STMT (rslt) = gimple_build_nop (); |
4ee9c684 | 909 | } |
910 | ||
75a70cf9 | 911 | gsi_remove (&t->call_gsi, true); |
2d1c5976 | 912 | release_defs (call); |
4ee9c684 | 913 | } |
914 | ||
915 | /* Optimizes the tailcall described by T. If OPT_TAILCALLS is true, also | |
916 | mark the tailcalls for the sibcall optimization. */ | |
917 | ||
918 | static bool | |
919 | optimize_tail_call (struct tailcall *t, bool opt_tailcalls) | |
920 | { | |
921 | if (t->tail_recursion) | |
922 | { | |
923 | eliminate_tail_call (t); | |
924 | return true; | |
925 | } | |
926 | ||
927 | if (opt_tailcalls) | |
928 | { | |
1a91d914 | 929 | gcall *stmt = as_a <gcall *> (gsi_stmt (t->call_gsi)); |
4ee9c684 | 930 | |
75a70cf9 | 931 | gimple_call_set_tail (stmt, true); |
dc7cdd37 | 932 | cfun->tail_call_marked = true; |
4ee9c684 | 933 | if (dump_file && (dump_flags & TDF_DETAILS)) |
934 | { | |
935 | fprintf (dump_file, "Found tail call "); | |
75a70cf9 | 936 | print_gimple_stmt (dump_file, stmt, 0, dump_flags); |
937 | fprintf (dump_file, " in bb %i\n", (gsi_bb (t->call_gsi))->index); | |
4ee9c684 | 938 | } |
939 | } | |
940 | ||
941 | return false; | |
942 | } | |
943 | ||
75a70cf9 | 944 | /* Creates a tail-call accumulator of the same type as the return type of the |
945 | current function. LABEL is the name used to creating the temporary | |
946 | variable for the accumulator. The accumulator will be inserted in the | |
947 | phis of a basic block BB with single predecessor with an initial value | |
948 | INIT converted to the current function return type. */ | |
949 | ||
950 | static tree | |
951 | create_tailcall_accumulator (const char *label, basic_block bb, tree init) | |
952 | { | |
953 | tree ret_type = TREE_TYPE (DECL_RESULT (current_function_decl)); | |
a6f8b9b9 | 954 | if (POINTER_TYPE_P (ret_type)) |
955 | ret_type = sizetype; | |
956 | ||
03d37e4e | 957 | tree tmp = make_temp_ssa_name (ret_type, NULL, label); |
1a91d914 | 958 | gphi *phi; |
75a70cf9 | 959 | |
75a70cf9 | 960 | phi = create_phi_node (tmp, bb); |
961 | /* RET_TYPE can be a float when -ffast-maths is enabled. */ | |
efbcb6de | 962 | add_phi_arg (phi, fold_convert (ret_type, init), single_pred_edge (bb), |
60d535d2 | 963 | UNKNOWN_LOCATION); |
75a70cf9 | 964 | return PHI_RESULT (phi); |
965 | } | |
48e1416a | 966 | |
4ee9c684 | 967 | /* Optimizes tail calls in the function, turning the tail recursion |
968 | into iteration. */ | |
969 | ||
6fa78c7b | 970 | static unsigned int |
4ee9c684 | 971 | tree_optimize_tail_calls_1 (bool opt_tailcalls) |
972 | { | |
973 | edge e; | |
974 | bool phis_constructed = false; | |
975 | struct tailcall *tailcalls = NULL, *act, *next; | |
976 | bool changed = false; | |
34154e27 | 977 | basic_block first = single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun)); |
75a70cf9 | 978 | tree param; |
42acab1c | 979 | gimple *stmt; |
cd665a06 | 980 | edge_iterator ei; |
4ee9c684 | 981 | |
982 | if (!suitable_for_tail_opt_p ()) | |
6fa78c7b | 983 | return 0; |
4ee9c684 | 984 | if (opt_tailcalls) |
985 | opt_tailcalls = suitable_for_tail_call_opt_p (); | |
986 | ||
34154e27 | 987 | FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR_FOR_FN (cfun)->preds) |
4ee9c684 | 988 | { |
989 | /* Only traverse the normal exits, i.e. those that end with return | |
990 | statement. */ | |
991 | stmt = last_stmt (e->src); | |
992 | ||
993 | if (stmt | |
75a70cf9 | 994 | && gimple_code (stmt) == GIMPLE_RETURN) |
4ee9c684 | 995 | find_tail_calls (e->src, &tailcalls); |
996 | } | |
997 | ||
998 | /* Construct the phi nodes and accumulators if necessary. */ | |
999 | a_acc = m_acc = NULL_TREE; | |
1000 | for (act = tailcalls; act; act = act->next) | |
1001 | { | |
1002 | if (!act->tail_recursion) | |
1003 | continue; | |
1004 | ||
1005 | if (!phis_constructed) | |
1006 | { | |
dd277d48 | 1007 | /* Ensure that there is only one predecessor of the block |
1008 | or if there are existing degenerate PHI nodes. */ | |
1009 | if (!single_pred_p (first) | |
1010 | || !gimple_seq_empty_p (phi_nodes (first))) | |
34154e27 | 1011 | first = |
1012 | split_edge (single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun))); | |
4ee9c684 | 1013 | |
1014 | /* Copy the args if needed. */ | |
1015 | for (param = DECL_ARGUMENTS (current_function_decl); | |
1016 | param; | |
1767a056 | 1017 | param = DECL_CHAIN (param)) |
4304657c | 1018 | if (arg_needs_copy_p (param)) |
1019 | { | |
c6dfe037 | 1020 | tree name = ssa_default_def (cfun, param); |
4304657c | 1021 | tree new_name = make_ssa_name (param, SSA_NAME_DEF_STMT (name)); |
1a91d914 | 1022 | gphi *phi; |
4304657c | 1023 | |
c6dfe037 | 1024 | set_ssa_default_def (cfun, param, new_name); |
4304657c | 1025 | phi = create_phi_node (name, first); |
48e1416a | 1026 | add_phi_arg (phi, new_name, single_pred_edge (first), |
60d535d2 | 1027 | EXPR_LOCATION (param)); |
4304657c | 1028 | } |
4ee9c684 | 1029 | phis_constructed = true; |
1030 | } | |
1031 | ||
1032 | if (act->add && !a_acc) | |
75a70cf9 | 1033 | a_acc = create_tailcall_accumulator ("add_acc", first, |
1034 | integer_zero_node); | |
4ee9c684 | 1035 | |
1036 | if (act->mult && !m_acc) | |
75a70cf9 | 1037 | m_acc = create_tailcall_accumulator ("mult_acc", first, |
1038 | integer_one_node); | |
4304657c | 1039 | } |
1040 | ||
f09431f1 | 1041 | if (a_acc || m_acc) |
1042 | { | |
1043 | /* When the tail call elimination using accumulators is performed, | |
1044 | statements adding the accumulated value are inserted at all exits. | |
1045 | This turns all other tail calls to non-tail ones. */ | |
1046 | opt_tailcalls = false; | |
1047 | } | |
1048 | ||
4ee9c684 | 1049 | for (; tailcalls; tailcalls = next) |
1050 | { | |
1051 | next = tailcalls->next; | |
1052 | changed |= optimize_tail_call (tailcalls, opt_tailcalls); | |
1053 | free (tailcalls); | |
1054 | } | |
1055 | ||
1056 | if (a_acc || m_acc) | |
1057 | { | |
1058 | /* Modify the remaining return statements. */ | |
34154e27 | 1059 | FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR_FOR_FN (cfun)->preds) |
4ee9c684 | 1060 | { |
1061 | stmt = last_stmt (e->src); | |
1062 | ||
1063 | if (stmt | |
75a70cf9 | 1064 | && gimple_code (stmt) == GIMPLE_RETURN) |
4ee9c684 | 1065 | adjust_return_value (e->src, m_acc, a_acc); |
1066 | } | |
1067 | } | |
1068 | ||
1069 | if (changed) | |
8ff30f9a | 1070 | { |
1071 | /* We may have created new loops. Make them magically appear. */ | |
b3083327 | 1072 | loops_state_set (LOOPS_NEED_FIXUP); |
8ff30f9a | 1073 | free_dominance_info (CDI_DOMINATORS); |
1074 | } | |
4304657c | 1075 | |
24ccd9c6 | 1076 | /* Add phi nodes for the virtual operands defined in the function to the |
1077 | header of the loop created by tail recursion elimination. Do so | |
1078 | by triggering the SSA renamer. */ | |
4304657c | 1079 | if (phis_constructed) |
278611f2 | 1080 | mark_virtual_operands_for_renaming (cfun); |
24ccd9c6 | 1081 | |
6fa78c7b | 1082 | if (changed) |
1083 | return TODO_cleanup_cfg | TODO_update_ssa_only_virtuals; | |
1084 | return 0; | |
4ee9c684 | 1085 | } |
1086 | ||
4ee9c684 | 1087 | static bool |
1088 | gate_tail_calls (void) | |
1089 | { | |
3072d30e | 1090 | return flag_optimize_sibling_calls != 0 && dbg_cnt (tail_call); |
4ee9c684 | 1091 | } |
1092 | ||
2a1990e9 | 1093 | static unsigned int |
4ee9c684 | 1094 | execute_tail_calls (void) |
1095 | { | |
6fa78c7b | 1096 | return tree_optimize_tail_calls_1 (true); |
4ee9c684 | 1097 | } |
1098 | ||
7620bc82 | 1099 | namespace { |
1100 | ||
1101 | const pass_data pass_data_tail_recursion = | |
4ee9c684 | 1102 | { |
cbe8bda8 | 1103 | GIMPLE_PASS, /* type */ |
1104 | "tailr", /* name */ | |
1105 | OPTGROUP_NONE, /* optinfo_flags */ | |
cbe8bda8 | 1106 | TV_NONE, /* tv_id */ |
1107 | ( PROP_cfg | PROP_ssa ), /* properties_required */ | |
1108 | 0, /* properties_provided */ | |
1109 | 0, /* properties_destroyed */ | |
1110 | 0, /* todo_flags_start */ | |
8b88439e | 1111 | 0, /* todo_flags_finish */ |
4ee9c684 | 1112 | }; |
1113 | ||
7620bc82 | 1114 | class pass_tail_recursion : public gimple_opt_pass |
cbe8bda8 | 1115 | { |
1116 | public: | |
9af5ce0c | 1117 | pass_tail_recursion (gcc::context *ctxt) |
1118 | : gimple_opt_pass (pass_data_tail_recursion, ctxt) | |
cbe8bda8 | 1119 | {} |
1120 | ||
1121 | /* opt_pass methods: */ | |
ae84f584 | 1122 | opt_pass * clone () { return new pass_tail_recursion (m_ctxt); } |
31315c24 | 1123 | virtual bool gate (function *) { return gate_tail_calls (); } |
65b0537f | 1124 | virtual unsigned int execute (function *) |
1125 | { | |
1126 | return tree_optimize_tail_calls_1 (false); | |
1127 | } | |
cbe8bda8 | 1128 | |
1129 | }; // class pass_tail_recursion | |
1130 | ||
7620bc82 | 1131 | } // anon namespace |
1132 | ||
cbe8bda8 | 1133 | gimple_opt_pass * |
1134 | make_pass_tail_recursion (gcc::context *ctxt) | |
1135 | { | |
1136 | return new pass_tail_recursion (ctxt); | |
1137 | } | |
1138 | ||
7620bc82 | 1139 | namespace { |
1140 | ||
1141 | const pass_data pass_data_tail_calls = | |
4ee9c684 | 1142 | { |
cbe8bda8 | 1143 | GIMPLE_PASS, /* type */ |
1144 | "tailc", /* name */ | |
1145 | OPTGROUP_NONE, /* optinfo_flags */ | |
cbe8bda8 | 1146 | TV_NONE, /* tv_id */ |
1147 | ( PROP_cfg | PROP_ssa ), /* properties_required */ | |
1148 | 0, /* properties_provided */ | |
1149 | 0, /* properties_destroyed */ | |
1150 | 0, /* todo_flags_start */ | |
8b88439e | 1151 | 0, /* todo_flags_finish */ |
4ee9c684 | 1152 | }; |
cbe8bda8 | 1153 | |
7620bc82 | 1154 | class pass_tail_calls : public gimple_opt_pass |
cbe8bda8 | 1155 | { |
1156 | public: | |
9af5ce0c | 1157 | pass_tail_calls (gcc::context *ctxt) |
1158 | : gimple_opt_pass (pass_data_tail_calls, ctxt) | |
cbe8bda8 | 1159 | {} |
1160 | ||
1161 | /* opt_pass methods: */ | |
31315c24 | 1162 | virtual bool gate (function *) { return gate_tail_calls (); } |
65b0537f | 1163 | virtual unsigned int execute (function *) { return execute_tail_calls (); } |
cbe8bda8 | 1164 | |
1165 | }; // class pass_tail_calls | |
1166 | ||
7620bc82 | 1167 | } // anon namespace |
1168 | ||
cbe8bda8 | 1169 | gimple_opt_pass * |
1170 | make_pass_tail_calls (gcc::context *ctxt) | |
1171 | { | |
1172 | return new pass_tail_calls (ctxt); | |
1173 | } |