1 /* Conditional constant propagation pass for the GNU compiler.
2 Copyright (C) 2000-2018 Free Software Foundation, Inc.
3 Adapted from original RTL SSA-CCP by Daniel Berlin <dberlin@dberlin.org>
4 Adapted to GIMPLE trees by Diego Novillo <dnovillo@redhat.com>
5
6 This file is part of GCC.
7
8 GCC is free software; you can redistribute it and/or modify it
9 under the terms of the GNU General Public License as published by the
10 Free Software Foundation; either version 3, or (at your option) any
11 later version.
12
13 GCC is distributed in the hope that it will be useful, but WITHOUT
14 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 for more details.
17
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
21
22 /* Conditional constant propagation (CCP) is based on the SSA
23 propagation engine (tree-ssa-propagate.c). Constant assignments of
24 the form VAR = CST are propagated from the assignments into uses of
25 VAR, which in turn may generate new constants. The simulation uses
26 a four level lattice to keep track of constant values associated
27 with SSA names. Given an SSA name V_i, it may take one of the
28 following values:
29
30 UNINITIALIZED -> the initial state of the value. This value
31 is replaced with a correct initial value
32 the first time the value is used, so the
33 rest of the pass does not need to care about
34 it. Using this value simplifies initialization
35 of the pass, and prevents us from needlessly
36 scanning statements that are never reached.
37
38 UNDEFINED -> V_i is a local variable whose definition
39 has not been processed yet. Therefore we
40 don't yet know if its value is a constant
41 or not.
42
43 CONSTANT -> V_i has been found to hold a constant
44 value C.
45
46 VARYING -> V_i cannot take a constant value, or if it
47 does, it is not possible to determine it
48 at compile time.
49
50 The core of SSA-CCP is in ccp_visit_stmt and ccp_visit_phi_node:
51
52 1- In ccp_visit_stmt, we are interested in assignments whose RHS
53 evaluates into a constant and conditional jumps whose predicate
54 evaluates into a boolean true or false. When an assignment of
55 the form V_i = CONST is found, V_i's lattice value is set to
56 CONSTANT and CONST is associated with it. This causes the
57 propagation engine to add all the SSA edges coming out the
58 assignment into the worklists, so that statements that use V_i
59 can be visited.
60
61 If the statement is a conditional with a constant predicate, we
62 mark the outgoing edges as executable or not executable
63 depending on the predicate's value. This is then used when
64 visiting PHI nodes to know when a PHI argument can be ignored.
65
66
67 2- In ccp_visit_phi_node, if all the PHI arguments evaluate to the
68 same constant C, then the LHS of the PHI is set to C. This
69 evaluation is known as the "meet operation". Since one of the
70 goals of this evaluation is to optimistically return constant
71 values as often as possible, it uses two main short cuts:
72
73 - If an argument is flowing in through a non-executable edge, it
74 is ignored. This is useful in cases like this:
75
76 if (PRED)
77 a_9 = 3;
78 else
79 a_10 = 100;
80 a_11 = PHI (a_9, a_10)
81
82 If PRED is known to always evaluate to false, then we can
83 assume that a_11 will always take its value from a_10, meaning
84 that instead of consider it VARYING (a_9 and a_10 have
85 different values), we can consider it CONSTANT 100.
86
87 - If an argument has an UNDEFINED value, then it does not affect
88 the outcome of the meet operation. If a variable V_i has an
89 UNDEFINED value, it means that either its defining statement
90 hasn't been visited yet or V_i has no defining statement, in
91 which case the original symbol 'V' is being used
92 uninitialized. Since 'V' is a local variable, the compiler
93 may assume any initial value for it.
94
95
96 After propagation, every variable V_i that ends up with a lattice
97 value of CONSTANT will have the associated constant value in the
98 array CONST_VAL[i].VALUE. That is fed into substitute_and_fold for
99 final substitution and folding.
100
101 This algorithm uses wide-ints at the max precision of the target.
102 This means that, with one uninteresting exception, variables with
103 UNSIGNED types never go to VARYING because the bits above the
104 precision of the type of the variable are always zero. The
105 uninteresting case is a variable of UNSIGNED type that has the
106 maximum precision of the target. Such variables can go to VARYING,
107 but this causes no loss of infomation since these variables will
108 never be extended.
109
110 References:
111
112 Constant propagation with conditional branches,
113 Wegman and Zadeck, ACM TOPLAS 13(2):181-210.
114
115 Building an Optimizing Compiler,
116 Robert Morgan, Butterworth-Heinemann, 1998, Section 8.9.
117
118 Advanced Compiler Design and Implementation,
119 Steven Muchnick, Morgan Kaufmann, 1997, Section 12.6 */
120
121 #include "config.h"
122 #include "system.h"
123 #include "coretypes.h"
124 #include "backend.h"
125 #include "target.h"
126 #include "tree.h"
127 #include "gimple.h"
128 #include "tree-pass.h"
129 #include "ssa.h"
130 #include "gimple-pretty-print.h"
131 #include "fold-const.h"
132 #include "gimple-fold.h"
133 #include "tree-eh.h"
134 #include "gimplify.h"
135 #include "gimple-iterator.h"
136 #include "tree-cfg.h"
137 #include "tree-ssa-propagate.h"
138 #include "dbgcnt.h"
139 #include "params.h"
140 #include "builtins.h"
141 #include "tree-chkp.h"
142 #include "cfgloop.h"
143 #include "stor-layout.h"
144 #include "optabs-query.h"
145 #include "tree-ssa-ccp.h"
146 #include "tree-dfa.h"
147 #include "diagnostic-core.h"
148 #include "stringpool.h"
149 #include "attribs.h"
150 #include "tree-vector-builder.h"
151
152 /* Possible lattice values. */
153 typedef enum
154 {
155 UNINITIALIZED,
156 UNDEFINED,
157 CONSTANT,
158 VARYING
159 } ccp_lattice_t;
160
161 struct ccp_prop_value_t {
162 /* Lattice value. */
163 ccp_lattice_t lattice_val;
164
165 /* Propagated value. */
166 tree value;
167
168 /* Mask that applies to the propagated value during CCP. For X
169 with a CONSTANT lattice value X & ~mask == value & ~mask. The
170 zero bits in the mask cover constant values. The ones mean no
171 information. */
172 widest_int mask;
173 };
174
175 class ccp_propagate : public ssa_propagation_engine
176 {
177 public:
178 enum ssa_prop_result visit_stmt (gimple *, edge *, tree *) FINAL OVERRIDE;
179 enum ssa_prop_result visit_phi (gphi *) FINAL OVERRIDE;
180 };
181
182 /* Array of propagated constant values. After propagation,
183 CONST_VAL[I].VALUE holds the constant value for SSA_NAME(I). If
184 the constant is held in an SSA name representing a memory store
185 (i.e., a VDEF), CONST_VAL[I].MEM_REF will contain the actual
186 memory reference used to store (i.e., the LHS of the assignment
187 doing the store). */
188 static ccp_prop_value_t *const_val;
189 static unsigned n_const_val;
190
191 static void canonicalize_value (ccp_prop_value_t *);
192 static void ccp_lattice_meet (ccp_prop_value_t *, ccp_prop_value_t *);
193
194 /* Dump constant propagation value VAL to file OUTF prefixed by PREFIX. */
195
196 static void
dump_lattice_value(FILE * outf,const char * prefix,ccp_prop_value_t val)197 dump_lattice_value (FILE *outf, const char *prefix, ccp_prop_value_t val)
198 {
199 switch (val.lattice_val)
200 {
201 case UNINITIALIZED:
202 fprintf (outf, "%sUNINITIALIZED", prefix);
203 break;
204 case UNDEFINED:
205 fprintf (outf, "%sUNDEFINED", prefix);
206 break;
207 case VARYING:
208 fprintf (outf, "%sVARYING", prefix);
209 break;
210 case CONSTANT:
211 if (TREE_CODE (val.value) != INTEGER_CST
212 || val.mask == 0)
213 {
214 fprintf (outf, "%sCONSTANT ", prefix);
215 print_generic_expr (outf, val.value, dump_flags);
216 }
217 else
218 {
219 widest_int cval = wi::bit_and_not (wi::to_widest (val.value),
220 val.mask);
221 fprintf (outf, "%sCONSTANT ", prefix);
222 print_hex (cval, outf);
223 fprintf (outf, " (");
224 print_hex (val.mask, outf);
225 fprintf (outf, ")");
226 }
227 break;
228 default:
229 gcc_unreachable ();
230 }
231 }
232
233
234 /* Print lattice value VAL to stderr. */
235
236 void debug_lattice_value (ccp_prop_value_t val);
237
238 DEBUG_FUNCTION void
debug_lattice_value(ccp_prop_value_t val)239 debug_lattice_value (ccp_prop_value_t val)
240 {
241 dump_lattice_value (stderr, "", val);
242 fprintf (stderr, "\n");
243 }
244
245 /* Extend NONZERO_BITS to a full mask, based on sgn. */
246
247 static widest_int
extend_mask(const wide_int & nonzero_bits,signop sgn)248 extend_mask (const wide_int &nonzero_bits, signop sgn)
249 {
250 return widest_int::from (nonzero_bits, sgn);
251 }
252
253 /* Compute a default value for variable VAR and store it in the
254 CONST_VAL array. The following rules are used to get default
255 values:
256
257 1- Global and static variables that are declared constant are
258 considered CONSTANT.
259
260 2- Any other value is considered UNDEFINED. This is useful when
261 considering PHI nodes. PHI arguments that are undefined do not
262 change the constant value of the PHI node, which allows for more
263 constants to be propagated.
264
265 3- Variables defined by statements other than assignments and PHI
266 nodes are considered VARYING.
267
268 4- Initial values of variables that are not GIMPLE registers are
269 considered VARYING. */
270
271 static ccp_prop_value_t
get_default_value(tree var)272 get_default_value (tree var)
273 {
274 ccp_prop_value_t val = { UNINITIALIZED, NULL_TREE, 0 };
275 gimple *stmt;
276
277 stmt = SSA_NAME_DEF_STMT (var);
278
279 if (gimple_nop_p (stmt))
280 {
281 /* Variables defined by an empty statement are those used
282 before being initialized. If VAR is a local variable, we
283 can assume initially that it is UNDEFINED, otherwise we must
284 consider it VARYING. */
285 if (!virtual_operand_p (var)
286 && SSA_NAME_VAR (var)
287 && TREE_CODE (SSA_NAME_VAR (var)) == VAR_DECL)
288 val.lattice_val = UNDEFINED;
289 else
290 {
291 val.lattice_val = VARYING;
292 val.mask = -1;
293 if (flag_tree_bit_ccp)
294 {
295 wide_int nonzero_bits = get_nonzero_bits (var);
296 if (nonzero_bits != -1)
297 {
298 val.lattice_val = CONSTANT;
299 val.value = build_zero_cst (TREE_TYPE (var));
300 val.mask = extend_mask (nonzero_bits, TYPE_SIGN (TREE_TYPE (var)));
301 }
302 }
303 }
304 }
305 else if (is_gimple_assign (stmt))
306 {
307 tree cst;
308 if (gimple_assign_single_p (stmt)
309 && DECL_P (gimple_assign_rhs1 (stmt))
310 && (cst = get_symbol_constant_value (gimple_assign_rhs1 (stmt))))
311 {
312 val.lattice_val = CONSTANT;
313 val.value = cst;
314 }
315 else
316 {
317 /* Any other variable defined by an assignment is considered
318 UNDEFINED. */
319 val.lattice_val = UNDEFINED;
320 }
321 }
322 else if ((is_gimple_call (stmt)
323 && gimple_call_lhs (stmt) != NULL_TREE)
324 || gimple_code (stmt) == GIMPLE_PHI)
325 {
326 /* A variable defined by a call or a PHI node is considered
327 UNDEFINED. */
328 val.lattice_val = UNDEFINED;
329 }
330 else
331 {
332 /* Otherwise, VAR will never take on a constant value. */
333 val.lattice_val = VARYING;
334 val.mask = -1;
335 }
336
337 return val;
338 }
339
340
341 /* Get the constant value associated with variable VAR. */
342
343 static inline ccp_prop_value_t *
get_value(tree var)344 get_value (tree var)
345 {
346 ccp_prop_value_t *val;
347
348 if (const_val == NULL
349 || SSA_NAME_VERSION (var) >= n_const_val)
350 return NULL;
351
352 val = &const_val[SSA_NAME_VERSION (var)];
353 if (val->lattice_val == UNINITIALIZED)
354 *val = get_default_value (var);
355
356 canonicalize_value (val);
357
358 return val;
359 }
360
361 /* Return the constant tree value associated with VAR. */
362
363 static inline tree
get_constant_value(tree var)364 get_constant_value (tree var)
365 {
366 ccp_prop_value_t *val;
367 if (TREE_CODE (var) != SSA_NAME)
368 {
369 if (is_gimple_min_invariant (var))
370 return var;
371 return NULL_TREE;
372 }
373 val = get_value (var);
374 if (val
375 && val->lattice_val == CONSTANT
376 && (TREE_CODE (val->value) != INTEGER_CST
377 || val->mask == 0))
378 return val->value;
379 return NULL_TREE;
380 }
381
382 /* Sets the value associated with VAR to VARYING. */
383
384 static inline void
set_value_varying(tree var)385 set_value_varying (tree var)
386 {
387 ccp_prop_value_t *val = &const_val[SSA_NAME_VERSION (var)];
388
389 val->lattice_val = VARYING;
390 val->value = NULL_TREE;
391 val->mask = -1;
392 }
393
394 /* For integer constants, make sure to drop TREE_OVERFLOW. */
395
396 static void
canonicalize_value(ccp_prop_value_t * val)397 canonicalize_value (ccp_prop_value_t *val)
398 {
399 if (val->lattice_val != CONSTANT)
400 return;
401
402 if (TREE_OVERFLOW_P (val->value))
403 val->value = drop_tree_overflow (val->value);
404 }
405
406 /* Return whether the lattice transition is valid. */
407
408 static bool
valid_lattice_transition(ccp_prop_value_t old_val,ccp_prop_value_t new_val)409 valid_lattice_transition (ccp_prop_value_t old_val, ccp_prop_value_t new_val)
410 {
411 /* Lattice transitions must always be monotonically increasing in
412 value. */
413 if (old_val.lattice_val < new_val.lattice_val)
414 return true;
415
416 if (old_val.lattice_val != new_val.lattice_val)
417 return false;
418
419 if (!old_val.value && !new_val.value)
420 return true;
421
422 /* Now both lattice values are CONSTANT. */
423
424 /* Allow arbitrary copy changes as we might look through PHI <a_1, ...>
425 when only a single copy edge is executable. */
426 if (TREE_CODE (old_val.value) == SSA_NAME
427 && TREE_CODE (new_val.value) == SSA_NAME)
428 return true;
429
430 /* Allow transitioning from a constant to a copy. */
431 if (is_gimple_min_invariant (old_val.value)
432 && TREE_CODE (new_val.value) == SSA_NAME)
433 return true;
434
435 /* Allow transitioning from PHI <&x, not executable> == &x
436 to PHI <&x, &y> == common alignment. */
437 if (TREE_CODE (old_val.value) != INTEGER_CST
438 && TREE_CODE (new_val.value) == INTEGER_CST)
439 return true;
440
441 /* Bit-lattices have to agree in the still valid bits. */
442 if (TREE_CODE (old_val.value) == INTEGER_CST
443 && TREE_CODE (new_val.value) == INTEGER_CST)
444 return (wi::bit_and_not (wi::to_widest (old_val.value), new_val.mask)
445 == wi::bit_and_not (wi::to_widest (new_val.value), new_val.mask));
446
447 /* Otherwise constant values have to agree. */
448 if (operand_equal_p (old_val.value, new_val.value, 0))
449 return true;
450
451 /* At least the kinds and types should agree now. */
452 if (TREE_CODE (old_val.value) != TREE_CODE (new_val.value)
453 || !types_compatible_p (TREE_TYPE (old_val.value),
454 TREE_TYPE (new_val.value)))
455 return false;
456
457 /* For floats and !HONOR_NANS allow transitions from (partial) NaN
458 to non-NaN. */
459 tree type = TREE_TYPE (new_val.value);
460 if (SCALAR_FLOAT_TYPE_P (type)
461 && !HONOR_NANS (type))
462 {
463 if (REAL_VALUE_ISNAN (TREE_REAL_CST (old_val.value)))
464 return true;
465 }
466 else if (VECTOR_FLOAT_TYPE_P (type)
467 && !HONOR_NANS (type))
468 {
469 unsigned int count
470 = tree_vector_builder::binary_encoded_nelts (old_val.value,
471 new_val.value);
472 for (unsigned int i = 0; i < count; ++i)
473 if (!REAL_VALUE_ISNAN
474 (TREE_REAL_CST (VECTOR_CST_ENCODED_ELT (old_val.value, i)))
475 && !operand_equal_p (VECTOR_CST_ENCODED_ELT (old_val.value, i),
476 VECTOR_CST_ENCODED_ELT (new_val.value, i), 0))
477 return false;
478 return true;
479 }
480 else if (COMPLEX_FLOAT_TYPE_P (type)
481 && !HONOR_NANS (type))
482 {
483 if (!REAL_VALUE_ISNAN (TREE_REAL_CST (TREE_REALPART (old_val.value)))
484 && !operand_equal_p (TREE_REALPART (old_val.value),
485 TREE_REALPART (new_val.value), 0))
486 return false;
487 if (!REAL_VALUE_ISNAN (TREE_REAL_CST (TREE_IMAGPART (old_val.value)))
488 && !operand_equal_p (TREE_IMAGPART (old_val.value),
489 TREE_IMAGPART (new_val.value), 0))
490 return false;
491 return true;
492 }
493 return false;
494 }
495
496 /* Set the value for variable VAR to NEW_VAL. Return true if the new
497 value is different from VAR's previous value. */
498
499 static bool
set_lattice_value(tree var,ccp_prop_value_t * new_val)500 set_lattice_value (tree var, ccp_prop_value_t *new_val)
501 {
502 /* We can deal with old UNINITIALIZED values just fine here. */
503 ccp_prop_value_t *old_val = &const_val[SSA_NAME_VERSION (var)];
504
505 canonicalize_value (new_val);
506
507 /* We have to be careful to not go up the bitwise lattice
508 represented by the mask. Instead of dropping to VARYING
509 use the meet operator to retain a conservative value.
510 Missed optimizations like PR65851 makes this necessary.
511 It also ensures we converge to a stable lattice solution. */
512 if (old_val->lattice_val != UNINITIALIZED)
513 ccp_lattice_meet (new_val, old_val);
514
515 gcc_checking_assert (valid_lattice_transition (*old_val, *new_val));
516
517 /* If *OLD_VAL and NEW_VAL are the same, return false to inform the
518 caller that this was a non-transition. */
519 if (old_val->lattice_val != new_val->lattice_val
520 || (new_val->lattice_val == CONSTANT
521 && (TREE_CODE (new_val->value) != TREE_CODE (old_val->value)
522 || (TREE_CODE (new_val->value) == INTEGER_CST
523 && (new_val->mask != old_val->mask
524 || (wi::bit_and_not (wi::to_widest (old_val->value),
525 new_val->mask)
526 != wi::bit_and_not (wi::to_widest (new_val->value),
527 new_val->mask))))
528 || (TREE_CODE (new_val->value) != INTEGER_CST
529 && !operand_equal_p (new_val->value, old_val->value, 0)))))
530 {
531 /* ??? We would like to delay creation of INTEGER_CSTs from
532 partially constants here. */
533
534 if (dump_file && (dump_flags & TDF_DETAILS))
535 {
536 dump_lattice_value (dump_file, "Lattice value changed to ", *new_val);
537 fprintf (dump_file, ". Adding SSA edges to worklist.\n");
538 }
539
540 *old_val = *new_val;
541
542 gcc_assert (new_val->lattice_val != UNINITIALIZED);
543 return true;
544 }
545
546 return false;
547 }
548
549 static ccp_prop_value_t get_value_for_expr (tree, bool);
550 static ccp_prop_value_t bit_value_binop (enum tree_code, tree, tree, tree);
551 void bit_value_binop (enum tree_code, signop, int, widest_int *, widest_int *,
552 signop, int, const widest_int &, const widest_int &,
553 signop, int, const widest_int &, const widest_int &);
554
555 /* Return a widest_int that can be used for bitwise simplifications
556 from VAL. */
557
558 static widest_int
value_to_wide_int(ccp_prop_value_t val)559 value_to_wide_int (ccp_prop_value_t val)
560 {
561 if (val.value
562 && TREE_CODE (val.value) == INTEGER_CST)
563 return wi::to_widest (val.value);
564
565 return 0;
566 }
567
568 /* Return the value for the address expression EXPR based on alignment
569 information. */
570
571 static ccp_prop_value_t
get_value_from_alignment(tree expr)572 get_value_from_alignment (tree expr)
573 {
574 tree type = TREE_TYPE (expr);
575 ccp_prop_value_t val;
576 unsigned HOST_WIDE_INT bitpos;
577 unsigned int align;
578
579 gcc_assert (TREE_CODE (expr) == ADDR_EXPR);
580
581 get_pointer_alignment_1 (expr, &align, &bitpos);
582 val.mask = wi::bit_and_not
583 (POINTER_TYPE_P (type) || TYPE_UNSIGNED (type)
584 ? wi::mask <widest_int> (TYPE_PRECISION (type), false)
585 : -1,
586 align / BITS_PER_UNIT - 1);
587 val.lattice_val
588 = wi::sext (val.mask, TYPE_PRECISION (type)) == -1 ? VARYING : CONSTANT;
589 if (val.lattice_val == CONSTANT)
590 val.value = build_int_cstu (type, bitpos / BITS_PER_UNIT);
591 else
592 val.value = NULL_TREE;
593
594 return val;
595 }
596
597 /* Return the value for the tree operand EXPR. If FOR_BITS_P is true
598 return constant bits extracted from alignment information for
599 invariant addresses. */
600
601 static ccp_prop_value_t
get_value_for_expr(tree expr,bool for_bits_p)602 get_value_for_expr (tree expr, bool for_bits_p)
603 {
604 ccp_prop_value_t val;
605
606 if (TREE_CODE (expr) == SSA_NAME)
607 {
608 ccp_prop_value_t *val_ = get_value (expr);
609 if (val_)
610 val = *val_;
611 else
612 {
613 val.lattice_val = VARYING;
614 val.value = NULL_TREE;
615 val.mask = -1;
616 }
617 if (for_bits_p
618 && val.lattice_val == CONSTANT
619 && TREE_CODE (val.value) == ADDR_EXPR)
620 val = get_value_from_alignment (val.value);
621 /* Fall back to a copy value. */
622 if (!for_bits_p
623 && val.lattice_val == VARYING
624 && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (expr))
625 {
626 val.lattice_val = CONSTANT;
627 val.value = expr;
628 val.mask = -1;
629 }
630 }
631 else if (is_gimple_min_invariant (expr)
632 && (!for_bits_p || TREE_CODE (expr) == INTEGER_CST))
633 {
634 val.lattice_val = CONSTANT;
635 val.value = expr;
636 val.mask = 0;
637 canonicalize_value (&val);
638 }
639 else if (TREE_CODE (expr) == ADDR_EXPR)
640 val = get_value_from_alignment (expr);
641 else
642 {
643 val.lattice_val = VARYING;
644 val.mask = -1;
645 val.value = NULL_TREE;
646 }
647
648 if (val.lattice_val == VARYING
649 && TYPE_UNSIGNED (TREE_TYPE (expr)))
650 val.mask = wi::zext (val.mask, TYPE_PRECISION (TREE_TYPE (expr)));
651
652 return val;
653 }
654
655 /* Return the likely CCP lattice value for STMT.
656
657 If STMT has no operands, then return CONSTANT.
658
659 Else if undefinedness of operands of STMT cause its value to be
660 undefined, then return UNDEFINED.
661
662 Else if any operands of STMT are constants, then return CONSTANT.
663
664 Else return VARYING. */
665
666 static ccp_lattice_t
likely_value(gimple * stmt)667 likely_value (gimple *stmt)
668 {
669 bool has_constant_operand, has_undefined_operand, all_undefined_operands;
670 bool has_nsa_operand;
671 tree use;
672 ssa_op_iter iter;
673 unsigned i;
674
675 enum gimple_code code = gimple_code (stmt);
676
677 /* This function appears to be called only for assignments, calls,
678 conditionals, and switches, due to the logic in visit_stmt. */
679 gcc_assert (code == GIMPLE_ASSIGN
680 || code == GIMPLE_CALL
681 || code == GIMPLE_COND
682 || code == GIMPLE_SWITCH);
683
684 /* If the statement has volatile operands, it won't fold to a
685 constant value. */
686 if (gimple_has_volatile_ops (stmt))
687 return VARYING;
688
689 /* Arrive here for more complex cases. */
690 has_constant_operand = false;
691 has_undefined_operand = false;
692 all_undefined_operands = true;
693 has_nsa_operand = false;
694 FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE)
695 {
696 ccp_prop_value_t *val = get_value (use);
697
698 if (val && val->lattice_val == UNDEFINED)
699 has_undefined_operand = true;
700 else
701 all_undefined_operands = false;
702
703 if (val && val->lattice_val == CONSTANT)
704 has_constant_operand = true;
705
706 if (SSA_NAME_IS_DEFAULT_DEF (use)
707 || !prop_simulate_again_p (SSA_NAME_DEF_STMT (use)))
708 has_nsa_operand = true;
709 }
710
711 /* There may be constants in regular rhs operands. For calls we
712 have to ignore lhs, fndecl and static chain, otherwise only
713 the lhs. */
714 for (i = (is_gimple_call (stmt) ? 2 : 0) + gimple_has_lhs (stmt);
715 i < gimple_num_ops (stmt); ++i)
716 {
717 tree op = gimple_op (stmt, i);
718 if (!op || TREE_CODE (op) == SSA_NAME)
719 continue;
720 if (is_gimple_min_invariant (op))
721 has_constant_operand = true;
722 }
723
724 if (has_constant_operand)
725 all_undefined_operands = false;
726
727 if (has_undefined_operand
728 && code == GIMPLE_CALL
729 && gimple_call_internal_p (stmt))
730 switch (gimple_call_internal_fn (stmt))
731 {
732 /* These 3 builtins use the first argument just as a magic
733 way how to find out a decl uid. */
734 case IFN_GOMP_SIMD_LANE:
735 case IFN_GOMP_SIMD_VF:
736 case IFN_GOMP_SIMD_LAST_LANE:
737 has_undefined_operand = false;
738 break;
739 default:
740 break;
741 }
742
743 /* If the operation combines operands like COMPLEX_EXPR make sure to
744 not mark the result UNDEFINED if only one part of the result is
745 undefined. */
746 if (has_undefined_operand && all_undefined_operands)
747 return UNDEFINED;
748 else if (code == GIMPLE_ASSIGN && has_undefined_operand)
749 {
750 switch (gimple_assign_rhs_code (stmt))
751 {
752 /* Unary operators are handled with all_undefined_operands. */
753 case PLUS_EXPR:
754 case MINUS_EXPR:
755 case POINTER_PLUS_EXPR:
756 case BIT_XOR_EXPR:
757 /* Not MIN_EXPR, MAX_EXPR. One VARYING operand may be selected.
758 Not bitwise operators, one VARYING operand may specify the
759 result completely.
760 Not logical operators for the same reason, apart from XOR.
761 Not COMPLEX_EXPR as one VARYING operand makes the result partly
762 not UNDEFINED. Not *DIV_EXPR, comparisons and shifts because
763 the undefined operand may be promoted. */
764 return UNDEFINED;
765
766 case ADDR_EXPR:
767 /* If any part of an address is UNDEFINED, like the index
768 of an ARRAY_EXPR, then treat the result as UNDEFINED. */
769 return UNDEFINED;
770
771 default:
772 ;
773 }
774 }
775 /* If there was an UNDEFINED operand but the result may be not UNDEFINED
776 fall back to CONSTANT. During iteration UNDEFINED may still drop
777 to CONSTANT. */
778 if (has_undefined_operand)
779 return CONSTANT;
780
781 /* We do not consider virtual operands here -- load from read-only
782 memory may have only VARYING virtual operands, but still be
783 constant. Also we can combine the stmt with definitions from
784 operands whose definitions are not simulated again. */
785 if (has_constant_operand
786 || has_nsa_operand
787 || gimple_references_memory_p (stmt))
788 return CONSTANT;
789
790 return VARYING;
791 }
792
793 /* Returns true if STMT cannot be constant. */
794
795 static bool
surely_varying_stmt_p(gimple * stmt)796 surely_varying_stmt_p (gimple *stmt)
797 {
798 /* If the statement has operands that we cannot handle, it cannot be
799 constant. */
800 if (gimple_has_volatile_ops (stmt))
801 return true;
802
803 /* If it is a call and does not return a value or is not a
804 builtin and not an indirect call or a call to function with
805 assume_aligned/alloc_align attribute, it is varying. */
806 if (is_gimple_call (stmt))
807 {
808 tree fndecl, fntype = gimple_call_fntype (stmt);
809 if (!gimple_call_lhs (stmt)
810 || ((fndecl = gimple_call_fndecl (stmt)) != NULL_TREE
811 && !DECL_BUILT_IN (fndecl)
812 && !lookup_attribute ("assume_aligned",
813 TYPE_ATTRIBUTES (fntype))
814 && !lookup_attribute ("alloc_align",
815 TYPE_ATTRIBUTES (fntype))))
816 return true;
817 }
818
819 /* Any other store operation is not interesting. */
820 else if (gimple_vdef (stmt))
821 return true;
822
823 /* Anything other than assignments and conditional jumps are not
824 interesting for CCP. */
825 if (gimple_code (stmt) != GIMPLE_ASSIGN
826 && gimple_code (stmt) != GIMPLE_COND
827 && gimple_code (stmt) != GIMPLE_SWITCH
828 && gimple_code (stmt) != GIMPLE_CALL)
829 return true;
830
831 return false;
832 }
833
834 /* Initialize local data structures for CCP. */
835
836 static void
ccp_initialize(void)837 ccp_initialize (void)
838 {
839 basic_block bb;
840
841 n_const_val = num_ssa_names;
842 const_val = XCNEWVEC (ccp_prop_value_t, n_const_val);
843
844 /* Initialize simulation flags for PHI nodes and statements. */
845 FOR_EACH_BB_FN (bb, cfun)
846 {
847 gimple_stmt_iterator i;
848
849 for (i = gsi_start_bb (bb); !gsi_end_p (i); gsi_next (&i))
850 {
851 gimple *stmt = gsi_stmt (i);
852 bool is_varying;
853
854 /* If the statement is a control insn, then we do not
855 want to avoid simulating the statement once. Failure
856 to do so means that those edges will never get added. */
857 if (stmt_ends_bb_p (stmt))
858 is_varying = false;
859 else
860 is_varying = surely_varying_stmt_p (stmt);
861
862 if (is_varying)
863 {
864 tree def;
865 ssa_op_iter iter;
866
867 /* If the statement will not produce a constant, mark
868 all its outputs VARYING. */
869 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
870 set_value_varying (def);
871 }
872 prop_set_simulate_again (stmt, !is_varying);
873 }
874 }
875
876 /* Now process PHI nodes. We never clear the simulate_again flag on
877 phi nodes, since we do not know which edges are executable yet,
878 except for phi nodes for virtual operands when we do not do store ccp. */
879 FOR_EACH_BB_FN (bb, cfun)
880 {
881 gphi_iterator i;
882
883 for (i = gsi_start_phis (bb); !gsi_end_p (i); gsi_next (&i))
884 {
885 gphi *phi = i.phi ();
886
887 if (virtual_operand_p (gimple_phi_result (phi)))
888 prop_set_simulate_again (phi, false);
889 else
890 prop_set_simulate_again (phi, true);
891 }
892 }
893 }
894
895 /* Debug count support. Reset the values of ssa names
896 VARYING when the total number ssa names analyzed is
897 beyond the debug count specified. */
898
899 static void
do_dbg_cnt(void)900 do_dbg_cnt (void)
901 {
902 unsigned i;
903 for (i = 0; i < num_ssa_names; i++)
904 {
905 if (!dbg_cnt (ccp))
906 {
907 const_val[i].lattice_val = VARYING;
908 const_val[i].mask = -1;
909 const_val[i].value = NULL_TREE;
910 }
911 }
912 }
913
914
915 /* We want to provide our own GET_VALUE and FOLD_STMT virtual methods. */
916 class ccp_folder : public substitute_and_fold_engine
917 {
918 public:
919 tree get_value (tree) FINAL OVERRIDE;
920 bool fold_stmt (gimple_stmt_iterator *) FINAL OVERRIDE;
921 };
922
923 /* This method just wraps GET_CONSTANT_VALUE for now. Over time
924 naked calls to GET_CONSTANT_VALUE should be eliminated in favor
925 of calling member functions. */
926
927 tree
get_value(tree op)928 ccp_folder::get_value (tree op)
929 {
930 return get_constant_value (op);
931 }
932
933 /* Do final substitution of propagated values, cleanup the flowgraph and
934 free allocated storage. If NONZERO_P, record nonzero bits.
935
936 Return TRUE when something was optimized. */
937
938 static bool
ccp_finalize(bool nonzero_p)939 ccp_finalize (bool nonzero_p)
940 {
941 bool something_changed;
942 unsigned i;
943 tree name;
944
945 do_dbg_cnt ();
946
947 /* Derive alignment and misalignment information from partially
948 constant pointers in the lattice or nonzero bits from partially
949 constant integers. */
950 FOR_EACH_SSA_NAME (i, name, cfun)
951 {
952 ccp_prop_value_t *val;
953 unsigned int tem, align;
954
955 if (!POINTER_TYPE_P (TREE_TYPE (name))
956 && (!INTEGRAL_TYPE_P (TREE_TYPE (name))
957 /* Don't record nonzero bits before IPA to avoid
958 using too much memory. */
959 || !nonzero_p))
960 continue;
961
962 val = get_value (name);
963 if (val->lattice_val != CONSTANT
964 || TREE_CODE (val->value) != INTEGER_CST
965 || val->mask == 0)
966 continue;
967
968 if (POINTER_TYPE_P (TREE_TYPE (name)))
969 {
970 /* Trailing mask bits specify the alignment, trailing value
971 bits the misalignment. */
972 tem = val->mask.to_uhwi ();
973 align = least_bit_hwi (tem);
974 if (align > 1)
975 set_ptr_info_alignment (get_ptr_info (name), align,
976 (TREE_INT_CST_LOW (val->value)
977 & (align - 1)));
978 }
979 else
980 {
981 unsigned int precision = TYPE_PRECISION (TREE_TYPE (val->value));
982 wide_int nonzero_bits
983 = (wide_int::from (val->mask, precision, UNSIGNED)
984 | wi::to_wide (val->value));
985 nonzero_bits &= get_nonzero_bits (name);
986 set_nonzero_bits (name, nonzero_bits);
987 }
988 }
989
990 /* Perform substitutions based on the known constant values. */
991 class ccp_folder ccp_folder;
992 something_changed = ccp_folder.substitute_and_fold ();
993
994 free (const_val);
995 const_val = NULL;
996 return something_changed;
997 }
998
999
1000 /* Compute the meet operator between *VAL1 and *VAL2. Store the result
1001 in VAL1.
1002
1003 any M UNDEFINED = any
1004 any M VARYING = VARYING
1005 Ci M Cj = Ci if (i == j)
1006 Ci M Cj = VARYING if (i != j)
1007 */
1008
1009 static void
ccp_lattice_meet(ccp_prop_value_t * val1,ccp_prop_value_t * val2)1010 ccp_lattice_meet (ccp_prop_value_t *val1, ccp_prop_value_t *val2)
1011 {
1012 if (val1->lattice_val == UNDEFINED
1013 /* For UNDEFINED M SSA we can't always SSA because its definition
1014 may not dominate the PHI node. Doing optimistic copy propagation
1015 also causes a lot of gcc.dg/uninit-pred*.c FAILs. */
1016 && (val2->lattice_val != CONSTANT
1017 || TREE_CODE (val2->value) != SSA_NAME))
1018 {
1019 /* UNDEFINED M any = any */
1020 *val1 = *val2;
1021 }
1022 else if (val2->lattice_val == UNDEFINED
1023 /* See above. */
1024 && (val1->lattice_val != CONSTANT
1025 || TREE_CODE (val1->value) != SSA_NAME))
1026 {
1027 /* any M UNDEFINED = any
1028 Nothing to do. VAL1 already contains the value we want. */
1029 ;
1030 }
1031 else if (val1->lattice_val == VARYING
1032 || val2->lattice_val == VARYING)
1033 {
1034 /* any M VARYING = VARYING. */
1035 val1->lattice_val = VARYING;
1036 val1->mask = -1;
1037 val1->value = NULL_TREE;
1038 }
1039 else if (val1->lattice_val == CONSTANT
1040 && val2->lattice_val == CONSTANT
1041 && TREE_CODE (val1->value) == INTEGER_CST
1042 && TREE_CODE (val2->value) == INTEGER_CST)
1043 {
1044 /* Ci M Cj = Ci if (i == j)
1045 Ci M Cj = VARYING if (i != j)
1046
1047 For INTEGER_CSTs mask unequal bits. If no equal bits remain,
1048 drop to varying. */
1049 val1->mask = (val1->mask | val2->mask
1050 | (wi::to_widest (val1->value)
1051 ^ wi::to_widest (val2->value)));
1052 if (wi::sext (val1->mask, TYPE_PRECISION (TREE_TYPE (val1->value))) == -1)
1053 {
1054 val1->lattice_val = VARYING;
1055 val1->value = NULL_TREE;
1056 }
1057 }
1058 else if (val1->lattice_val == CONSTANT
1059 && val2->lattice_val == CONSTANT
1060 && operand_equal_p (val1->value, val2->value, 0))
1061 {
1062 /* Ci M Cj = Ci if (i == j)
1063 Ci M Cj = VARYING if (i != j)
1064
1065 VAL1 already contains the value we want for equivalent values. */
1066 }
1067 else if (val1->lattice_val == CONSTANT
1068 && val2->lattice_val == CONSTANT
1069 && (TREE_CODE (val1->value) == ADDR_EXPR
1070 || TREE_CODE (val2->value) == ADDR_EXPR))
1071 {
1072 /* When not equal addresses are involved try meeting for
1073 alignment. */
1074 ccp_prop_value_t tem = *val2;
1075 if (TREE_CODE (val1->value) == ADDR_EXPR)
1076 *val1 = get_value_for_expr (val1->value, true);
1077 if (TREE_CODE (val2->value) == ADDR_EXPR)
1078 tem = get_value_for_expr (val2->value, true);
1079 ccp_lattice_meet (val1, &tem);
1080 }
1081 else
1082 {
1083 /* Any other combination is VARYING. */
1084 val1->lattice_val = VARYING;
1085 val1->mask = -1;
1086 val1->value = NULL_TREE;
1087 }
1088 }
1089
1090
1091 /* Loop through the PHI_NODE's parameters for BLOCK and compare their
1092 lattice values to determine PHI_NODE's lattice value. The value of a
1093 PHI node is determined calling ccp_lattice_meet with all the arguments
1094 of the PHI node that are incoming via executable edges. */
1095
1096 enum ssa_prop_result
visit_phi(gphi * phi)1097 ccp_propagate::visit_phi (gphi *phi)
1098 {
1099 unsigned i;
1100 ccp_prop_value_t new_val;
1101
1102 if (dump_file && (dump_flags & TDF_DETAILS))
1103 {
1104 fprintf (dump_file, "\nVisiting PHI node: ");
1105 print_gimple_stmt (dump_file, phi, 0, dump_flags);
1106 }
1107
1108 new_val.lattice_val = UNDEFINED;
1109 new_val.value = NULL_TREE;
1110 new_val.mask = 0;
1111
1112 bool first = true;
1113 bool non_exec_edge = false;
1114 for (i = 0; i < gimple_phi_num_args (phi); i++)
1115 {
1116 /* Compute the meet operator over all the PHI arguments flowing
1117 through executable edges. */
1118 edge e = gimple_phi_arg_edge (phi, i);
1119
1120 if (dump_file && (dump_flags & TDF_DETAILS))
1121 {
1122 fprintf (dump_file,
1123 "\tArgument #%d (%d -> %d %sexecutable)\n",
1124 i, e->src->index, e->dest->index,
1125 (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
1126 }
1127
1128 /* If the incoming edge is executable, Compute the meet operator for
1129 the existing value of the PHI node and the current PHI argument. */
1130 if (e->flags & EDGE_EXECUTABLE)
1131 {
1132 tree arg = gimple_phi_arg (phi, i)->def;
1133 ccp_prop_value_t arg_val = get_value_for_expr (arg, false);
1134
1135 if (first)
1136 {
1137 new_val = arg_val;
1138 first = false;
1139 }
1140 else
1141 ccp_lattice_meet (&new_val, &arg_val);
1142
1143 if (dump_file && (dump_flags & TDF_DETAILS))
1144 {
1145 fprintf (dump_file, "\t");
1146 print_generic_expr (dump_file, arg, dump_flags);
1147 dump_lattice_value (dump_file, "\tValue: ", arg_val);
1148 fprintf (dump_file, "\n");
1149 }
1150
1151 if (new_val.lattice_val == VARYING)
1152 break;
1153 }
1154 else
1155 non_exec_edge = true;
1156 }
1157
1158 /* In case there were non-executable edges and the value is a copy
1159 make sure its definition dominates the PHI node. */
1160 if (non_exec_edge
1161 && new_val.lattice_val == CONSTANT
1162 && TREE_CODE (new_val.value) == SSA_NAME
1163 && ! SSA_NAME_IS_DEFAULT_DEF (new_val.value)
1164 && ! dominated_by_p (CDI_DOMINATORS, gimple_bb (phi),
1165 gimple_bb (SSA_NAME_DEF_STMT (new_val.value))))
1166 {
1167 new_val.lattice_val = VARYING;
1168 new_val.value = NULL_TREE;
1169 new_val.mask = -1;
1170 }
1171
1172 if (dump_file && (dump_flags & TDF_DETAILS))
1173 {
1174 dump_lattice_value (dump_file, "\n PHI node value: ", new_val);
1175 fprintf (dump_file, "\n\n");
1176 }
1177
1178 /* Make the transition to the new value. */
1179 if (set_lattice_value (gimple_phi_result (phi), &new_val))
1180 {
1181 if (new_val.lattice_val == VARYING)
1182 return SSA_PROP_VARYING;
1183 else
1184 return SSA_PROP_INTERESTING;
1185 }
1186 else
1187 return SSA_PROP_NOT_INTERESTING;
1188 }
1189
1190 /* Return the constant value for OP or OP otherwise. */
1191
1192 static tree
valueize_op(tree op)1193 valueize_op (tree op)
1194 {
1195 if (TREE_CODE (op) == SSA_NAME)
1196 {
1197 tree tem = get_constant_value (op);
1198 if (tem)
1199 return tem;
1200 }
1201 return op;
1202 }
1203
1204 /* Return the constant value for OP, but signal to not follow SSA
1205 edges if the definition may be simulated again. */
1206
1207 static tree
valueize_op_1(tree op)1208 valueize_op_1 (tree op)
1209 {
1210 if (TREE_CODE (op) == SSA_NAME)
1211 {
1212 /* If the definition may be simulated again we cannot follow
1213 this SSA edge as the SSA propagator does not necessarily
1214 re-visit the use. */
1215 gimple *def_stmt = SSA_NAME_DEF_STMT (op);
1216 if (!gimple_nop_p (def_stmt)
1217 && prop_simulate_again_p (def_stmt))
1218 return NULL_TREE;
1219 tree tem = get_constant_value (op);
1220 if (tem)
1221 return tem;
1222 }
1223 return op;
1224 }
1225
1226 /* CCP specific front-end to the non-destructive constant folding
1227 routines.
1228
1229 Attempt to simplify the RHS of STMT knowing that one or more
1230 operands are constants.
1231
1232 If simplification is possible, return the simplified RHS,
1233 otherwise return the original RHS or NULL_TREE. */
1234
1235 static tree
ccp_fold(gimple * stmt)1236 ccp_fold (gimple *stmt)
1237 {
1238 location_t loc = gimple_location (stmt);
1239 switch (gimple_code (stmt))
1240 {
1241 case GIMPLE_COND:
1242 {
1243 /* Handle comparison operators that can appear in GIMPLE form. */
1244 tree op0 = valueize_op (gimple_cond_lhs (stmt));
1245 tree op1 = valueize_op (gimple_cond_rhs (stmt));
1246 enum tree_code code = gimple_cond_code (stmt);
1247 return fold_binary_loc (loc, code, boolean_type_node, op0, op1);
1248 }
1249
1250 case GIMPLE_SWITCH:
1251 {
1252 /* Return the constant switch index. */
1253 return valueize_op (gimple_switch_index (as_a <gswitch *> (stmt)));
1254 }
1255
1256 case GIMPLE_ASSIGN:
1257 case GIMPLE_CALL:
1258 return gimple_fold_stmt_to_constant_1 (stmt,
1259 valueize_op, valueize_op_1);
1260
1261 default:
1262 gcc_unreachable ();
1263 }
1264 }
1265
1266 /* Apply the operation CODE in type TYPE to the value, mask pair
1267 RVAL and RMASK representing a value of type RTYPE and set
1268 the value, mask pair *VAL and *MASK to the result. */
1269
1270 void
bit_value_unop(enum tree_code code,signop type_sgn,int type_precision,widest_int * val,widest_int * mask,signop rtype_sgn,int rtype_precision,const widest_int & rval,const widest_int & rmask)1271 bit_value_unop (enum tree_code code, signop type_sgn, int type_precision,
1272 widest_int *val, widest_int *mask,
1273 signop rtype_sgn, int rtype_precision,
1274 const widest_int &rval, const widest_int &rmask)
1275 {
1276 switch (code)
1277 {
1278 case BIT_NOT_EXPR:
1279 *mask = rmask;
1280 *val = ~rval;
1281 break;
1282
1283 case NEGATE_EXPR:
1284 {
1285 widest_int temv, temm;
1286 /* Return ~rval + 1. */
1287 bit_value_unop (BIT_NOT_EXPR, type_sgn, type_precision, &temv, &temm,
1288 type_sgn, type_precision, rval, rmask);
1289 bit_value_binop (PLUS_EXPR, type_sgn, type_precision, val, mask,
1290 type_sgn, type_precision, temv, temm,
1291 type_sgn, type_precision, 1, 0);
1292 break;
1293 }
1294
1295 CASE_CONVERT:
1296 {
1297 /* First extend mask and value according to the original type. */
1298 *mask = wi::ext (rmask, rtype_precision, rtype_sgn);
1299 *val = wi::ext (rval, rtype_precision, rtype_sgn);
1300
1301 /* Then extend mask and value according to the target type. */
1302 *mask = wi::ext (*mask, type_precision, type_sgn);
1303 *val = wi::ext (*val, type_precision, type_sgn);
1304 break;
1305 }
1306
1307 default:
1308 *mask = -1;
1309 break;
1310 }
1311 }
1312
1313 /* Apply the operation CODE in type TYPE to the value, mask pairs
1314 R1VAL, R1MASK and R2VAL, R2MASK representing a values of type R1TYPE
1315 and R2TYPE and set the value, mask pair *VAL and *MASK to the result. */
1316
1317 void
bit_value_binop(enum tree_code code,signop sgn,int width,widest_int * val,widest_int * mask,signop r1type_sgn,int r1type_precision,const widest_int & r1val,const widest_int & r1mask,signop r2type_sgn,int r2type_precision,const widest_int & r2val,const widest_int & r2mask)1318 bit_value_binop (enum tree_code code, signop sgn, int width,
1319 widest_int *val, widest_int *mask,
1320 signop r1type_sgn, int r1type_precision,
1321 const widest_int &r1val, const widest_int &r1mask,
1322 signop r2type_sgn, int r2type_precision,
1323 const widest_int &r2val, const widest_int &r2mask)
1324 {
1325 bool swap_p = false;
1326
1327 /* Assume we'll get a constant result. Use an initial non varying
1328 value, we fall back to varying in the end if necessary. */
1329 *mask = -1;
1330
1331 switch (code)
1332 {
1333 case BIT_AND_EXPR:
1334 /* The mask is constant where there is a known not
1335 set bit, (m1 | m2) & ((v1 | m1) & (v2 | m2)) */
1336 *mask = (r1mask | r2mask) & (r1val | r1mask) & (r2val | r2mask);
1337 *val = r1val & r2val;
1338 break;
1339
1340 case BIT_IOR_EXPR:
1341 /* The mask is constant where there is a known
1342 set bit, (m1 | m2) & ~((v1 & ~m1) | (v2 & ~m2)). */
1343 *mask = wi::bit_and_not (r1mask | r2mask,
1344 wi::bit_and_not (r1val, r1mask)
1345 | wi::bit_and_not (r2val, r2mask));
1346 *val = r1val | r2val;
1347 break;
1348
1349 case BIT_XOR_EXPR:
1350 /* m1 | m2 */
1351 *mask = r1mask | r2mask;
1352 *val = r1val ^ r2val;
1353 break;
1354
1355 case LROTATE_EXPR:
1356 case RROTATE_EXPR:
1357 if (r2mask == 0)
1358 {
1359 widest_int shift = r2val;
1360 if (shift == 0)
1361 {
1362 *mask = r1mask;
1363 *val = r1val;
1364 }
1365 else
1366 {
1367 if (wi::neg_p (shift))
1368 {
1369 shift = -shift;
1370 if (code == RROTATE_EXPR)
1371 code = LROTATE_EXPR;
1372 else
1373 code = RROTATE_EXPR;
1374 }
1375 if (code == RROTATE_EXPR)
1376 {
1377 *mask = wi::rrotate (r1mask, shift, width);
1378 *val = wi::rrotate (r1val, shift, width);
1379 }
1380 else
1381 {
1382 *mask = wi::lrotate (r1mask, shift, width);
1383 *val = wi::lrotate (r1val, shift, width);
1384 }
1385 }
1386 }
1387 break;
1388
1389 case LSHIFT_EXPR:
1390 case RSHIFT_EXPR:
1391 /* ??? We can handle partially known shift counts if we know
1392 its sign. That way we can tell that (x << (y | 8)) & 255
1393 is zero. */
1394 if (r2mask == 0)
1395 {
1396 widest_int shift = r2val;
1397 if (shift == 0)
1398 {
1399 *mask = r1mask;
1400 *val = r1val;
1401 }
1402 else
1403 {
1404 if (wi::neg_p (shift))
1405 {
1406 shift = -shift;
1407 if (code == RSHIFT_EXPR)
1408 code = LSHIFT_EXPR;
1409 else
1410 code = RSHIFT_EXPR;
1411 }
1412 if (code == RSHIFT_EXPR)
1413 {
1414 *mask = wi::rshift (wi::ext (r1mask, width, sgn), shift, sgn);
1415 *val = wi::rshift (wi::ext (r1val, width, sgn), shift, sgn);
1416 }
1417 else
1418 {
1419 *mask = wi::ext (r1mask << shift, width, sgn);
1420 *val = wi::ext (r1val << shift, width, sgn);
1421 }
1422 }
1423 }
1424 break;
1425
1426 case PLUS_EXPR:
1427 case POINTER_PLUS_EXPR:
1428 {
1429 /* Do the addition with unknown bits set to zero, to give carry-ins of
1430 zero wherever possible. */
1431 widest_int lo = (wi::bit_and_not (r1val, r1mask)
1432 + wi::bit_and_not (r2val, r2mask));
1433 lo = wi::ext (lo, width, sgn);
1434 /* Do the addition with unknown bits set to one, to give carry-ins of
1435 one wherever possible. */
1436 widest_int hi = (r1val | r1mask) + (r2val | r2mask);
1437 hi = wi::ext (hi, width, sgn);
1438 /* Each bit in the result is known if (a) the corresponding bits in
1439 both inputs are known, and (b) the carry-in to that bit position
1440 is known. We can check condition (b) by seeing if we got the same
1441 result with minimised carries as with maximised carries. */
1442 *mask = r1mask | r2mask | (lo ^ hi);
1443 *mask = wi::ext (*mask, width, sgn);
1444 /* It shouldn't matter whether we choose lo or hi here. */
1445 *val = lo;
1446 break;
1447 }
1448
1449 case MINUS_EXPR:
1450 {
1451 widest_int temv, temm;
1452 bit_value_unop (NEGATE_EXPR, r2type_sgn, r2type_precision, &temv, &temm,
1453 r2type_sgn, r2type_precision, r2val, r2mask);
1454 bit_value_binop (PLUS_EXPR, sgn, width, val, mask,
1455 r1type_sgn, r1type_precision, r1val, r1mask,
1456 r2type_sgn, r2type_precision, temv, temm);
1457 break;
1458 }
1459
1460 case MULT_EXPR:
1461 {
1462 /* Just track trailing zeros in both operands and transfer
1463 them to the other. */
1464 int r1tz = wi::ctz (r1val | r1mask);
1465 int r2tz = wi::ctz (r2val | r2mask);
1466 if (r1tz + r2tz >= width)
1467 {
1468 *mask = 0;
1469 *val = 0;
1470 }
1471 else if (r1tz + r2tz > 0)
1472 {
1473 *mask = wi::ext (wi::mask <widest_int> (r1tz + r2tz, true),
1474 width, sgn);
1475 *val = 0;
1476 }
1477 break;
1478 }
1479
1480 case EQ_EXPR:
1481 case NE_EXPR:
1482 {
1483 widest_int m = r1mask | r2mask;
1484 if (wi::bit_and_not (r1val, m) != wi::bit_and_not (r2val, m))
1485 {
1486 *mask = 0;
1487 *val = ((code == EQ_EXPR) ? 0 : 1);
1488 }
1489 else
1490 {
1491 /* We know the result of a comparison is always one or zero. */
1492 *mask = 1;
1493 *val = 0;
1494 }
1495 break;
1496 }
1497
1498 case GE_EXPR:
1499 case GT_EXPR:
1500 swap_p = true;
1501 code = swap_tree_comparison (code);
1502 /* Fall through. */
1503 case LT_EXPR:
1504 case LE_EXPR:
1505 {
1506 int minmax, maxmin;
1507
1508 const widest_int &o1val = swap_p ? r2val : r1val;
1509 const widest_int &o1mask = swap_p ? r2mask : r1mask;
1510 const widest_int &o2val = swap_p ? r1val : r2val;
1511 const widest_int &o2mask = swap_p ? r1mask : r2mask;
1512
1513 /* If the most significant bits are not known we know nothing. */
1514 if (wi::neg_p (o1mask) || wi::neg_p (o2mask))
1515 break;
1516
1517 /* For comparisons the signedness is in the comparison operands. */
1518 sgn = r1type_sgn;
1519
1520 /* If we know the most significant bits we know the values
1521 value ranges by means of treating varying bits as zero
1522 or one. Do a cross comparison of the max/min pairs. */
1523 maxmin = wi::cmp (o1val | o1mask,
1524 wi::bit_and_not (o2val, o2mask), sgn);
1525 minmax = wi::cmp (wi::bit_and_not (o1val, o1mask),
1526 o2val | o2mask, sgn);
1527 if (maxmin < 0) /* o1 is less than o2. */
1528 {
1529 *mask = 0;
1530 *val = 1;
1531 }
1532 else if (minmax > 0) /* o1 is not less or equal to o2. */
1533 {
1534 *mask = 0;
1535 *val = 0;
1536 }
1537 else if (maxmin == minmax) /* o1 and o2 are equal. */
1538 {
1539 /* This probably should never happen as we'd have
1540 folded the thing during fully constant value folding. */
1541 *mask = 0;
1542 *val = (code == LE_EXPR ? 1 : 0);
1543 }
1544 else
1545 {
1546 /* We know the result of a comparison is always one or zero. */
1547 *mask = 1;
1548 *val = 0;
1549 }
1550 break;
1551 }
1552
1553 default:;
1554 }
1555 }
1556
1557 /* Return the propagation value when applying the operation CODE to
1558 the value RHS yielding type TYPE. */
1559
1560 static ccp_prop_value_t
bit_value_unop(enum tree_code code,tree type,tree rhs)1561 bit_value_unop (enum tree_code code, tree type, tree rhs)
1562 {
1563 ccp_prop_value_t rval = get_value_for_expr (rhs, true);
1564 widest_int value, mask;
1565 ccp_prop_value_t val;
1566
1567 if (rval.lattice_val == UNDEFINED)
1568 return rval;
1569
1570 gcc_assert ((rval.lattice_val == CONSTANT
1571 && TREE_CODE (rval.value) == INTEGER_CST)
1572 || wi::sext (rval.mask, TYPE_PRECISION (TREE_TYPE (rhs))) == -1);
1573 bit_value_unop (code, TYPE_SIGN (type), TYPE_PRECISION (type), &value, &mask,
1574 TYPE_SIGN (TREE_TYPE (rhs)), TYPE_PRECISION (TREE_TYPE (rhs)),
1575 value_to_wide_int (rval), rval.mask);
1576 if (wi::sext (mask, TYPE_PRECISION (type)) != -1)
1577 {
1578 val.lattice_val = CONSTANT;
1579 val.mask = mask;
1580 /* ??? Delay building trees here. */
1581 val.value = wide_int_to_tree (type, value);
1582 }
1583 else
1584 {
1585 val.lattice_val = VARYING;
1586 val.value = NULL_TREE;
1587 val.mask = -1;
1588 }
1589 return val;
1590 }
1591
1592 /* Return the propagation value when applying the operation CODE to
1593 the values RHS1 and RHS2 yielding type TYPE. */
1594
1595 static ccp_prop_value_t
bit_value_binop(enum tree_code code,tree type,tree rhs1,tree rhs2)1596 bit_value_binop (enum tree_code code, tree type, tree rhs1, tree rhs2)
1597 {
1598 ccp_prop_value_t r1val = get_value_for_expr (rhs1, true);
1599 ccp_prop_value_t r2val = get_value_for_expr (rhs2, true);
1600 widest_int value, mask;
1601 ccp_prop_value_t val;
1602
1603 if (r1val.lattice_val == UNDEFINED
1604 || r2val.lattice_val == UNDEFINED)
1605 {
1606 val.lattice_val = VARYING;
1607 val.value = NULL_TREE;
1608 val.mask = -1;
1609 return val;
1610 }
1611
1612 gcc_assert ((r1val.lattice_val == CONSTANT
1613 && TREE_CODE (r1val.value) == INTEGER_CST)
1614 || wi::sext (r1val.mask,
1615 TYPE_PRECISION (TREE_TYPE (rhs1))) == -1);
1616 gcc_assert ((r2val.lattice_val == CONSTANT
1617 && TREE_CODE (r2val.value) == INTEGER_CST)
1618 || wi::sext (r2val.mask,
1619 TYPE_PRECISION (TREE_TYPE (rhs2))) == -1);
1620 bit_value_binop (code, TYPE_SIGN (type), TYPE_PRECISION (type), &value, &mask,
1621 TYPE_SIGN (TREE_TYPE (rhs1)), TYPE_PRECISION (TREE_TYPE (rhs1)),
1622 value_to_wide_int (r1val), r1val.mask,
1623 TYPE_SIGN (TREE_TYPE (rhs2)), TYPE_PRECISION (TREE_TYPE (rhs2)),
1624 value_to_wide_int (r2val), r2val.mask);
1625
1626 if (wi::sext (mask, TYPE_PRECISION (type)) != -1)
1627 {
1628 val.lattice_val = CONSTANT;
1629 val.mask = mask;
1630 /* ??? Delay building trees here. */
1631 val.value = wide_int_to_tree (type, value);
1632 }
1633 else
1634 {
1635 val.lattice_val = VARYING;
1636 val.value = NULL_TREE;
1637 val.mask = -1;
1638 }
1639 return val;
1640 }
1641
1642 /* Return the propagation value for __builtin_assume_aligned
1643 and functions with assume_aligned or alloc_aligned attribute.
1644 For __builtin_assume_aligned, ATTR is NULL_TREE,
1645 for assume_aligned attribute ATTR is non-NULL and ALLOC_ALIGNED
1646 is false, for alloc_aligned attribute ATTR is non-NULL and
1647 ALLOC_ALIGNED is true. */
1648
1649 static ccp_prop_value_t
bit_value_assume_aligned(gimple * stmt,tree attr,ccp_prop_value_t ptrval,bool alloc_aligned)1650 bit_value_assume_aligned (gimple *stmt, tree attr, ccp_prop_value_t ptrval,
1651 bool alloc_aligned)
1652 {
1653 tree align, misalign = NULL_TREE, type;
1654 unsigned HOST_WIDE_INT aligni, misaligni = 0;
1655 ccp_prop_value_t alignval;
1656 widest_int value, mask;
1657 ccp_prop_value_t val;
1658
1659 if (attr == NULL_TREE)
1660 {
1661 tree ptr = gimple_call_arg (stmt, 0);
1662 type = TREE_TYPE (ptr);
1663 ptrval = get_value_for_expr (ptr, true);
1664 }
1665 else
1666 {
1667 tree lhs = gimple_call_lhs (stmt);
1668 type = TREE_TYPE (lhs);
1669 }
1670
1671 if (ptrval.lattice_val == UNDEFINED)
1672 return ptrval;
1673 gcc_assert ((ptrval.lattice_val == CONSTANT
1674 && TREE_CODE (ptrval.value) == INTEGER_CST)
1675 || wi::sext (ptrval.mask, TYPE_PRECISION (type)) == -1);
1676 if (attr == NULL_TREE)
1677 {
1678 /* Get aligni and misaligni from __builtin_assume_aligned. */
1679 align = gimple_call_arg (stmt, 1);
1680 if (!tree_fits_uhwi_p (align))
1681 return ptrval;
1682 aligni = tree_to_uhwi (align);
1683 if (gimple_call_num_args (stmt) > 2)
1684 {
1685 misalign = gimple_call_arg (stmt, 2);
1686 if (!tree_fits_uhwi_p (misalign))
1687 return ptrval;
1688 misaligni = tree_to_uhwi (misalign);
1689 }
1690 }
1691 else
1692 {
1693 /* Get aligni and misaligni from assume_aligned or
1694 alloc_align attributes. */
1695 if (TREE_VALUE (attr) == NULL_TREE)
1696 return ptrval;
1697 attr = TREE_VALUE (attr);
1698 align = TREE_VALUE (attr);
1699 if (!tree_fits_uhwi_p (align))
1700 return ptrval;
1701 aligni = tree_to_uhwi (align);
1702 if (alloc_aligned)
1703 {
1704 if (aligni == 0 || aligni > gimple_call_num_args (stmt))
1705 return ptrval;
1706 align = gimple_call_arg (stmt, aligni - 1);
1707 if (!tree_fits_uhwi_p (align))
1708 return ptrval;
1709 aligni = tree_to_uhwi (align);
1710 }
1711 else if (TREE_CHAIN (attr) && TREE_VALUE (TREE_CHAIN (attr)))
1712 {
1713 misalign = TREE_VALUE (TREE_CHAIN (attr));
1714 if (!tree_fits_uhwi_p (misalign))
1715 return ptrval;
1716 misaligni = tree_to_uhwi (misalign);
1717 }
1718 }
1719 if (aligni <= 1 || (aligni & (aligni - 1)) != 0 || misaligni >= aligni)
1720 return ptrval;
1721
1722 align = build_int_cst_type (type, -aligni);
1723 alignval = get_value_for_expr (align, true);
1724 bit_value_binop (BIT_AND_EXPR, TYPE_SIGN (type), TYPE_PRECISION (type), &value, &mask,
1725 TYPE_SIGN (type), TYPE_PRECISION (type), value_to_wide_int (ptrval), ptrval.mask,
1726 TYPE_SIGN (type), TYPE_PRECISION (type), value_to_wide_int (alignval), alignval.mask);
1727
1728 if (wi::sext (mask, TYPE_PRECISION (type)) != -1)
1729 {
1730 val.lattice_val = CONSTANT;
1731 val.mask = mask;
1732 gcc_assert ((mask.to_uhwi () & (aligni - 1)) == 0);
1733 gcc_assert ((value.to_uhwi () & (aligni - 1)) == 0);
1734 value |= misaligni;
1735 /* ??? Delay building trees here. */
1736 val.value = wide_int_to_tree (type, value);
1737 }
1738 else
1739 {
1740 val.lattice_val = VARYING;
1741 val.value = NULL_TREE;
1742 val.mask = -1;
1743 }
1744 return val;
1745 }
1746
1747 /* Evaluate statement STMT.
1748 Valid only for assignments, calls, conditionals, and switches. */
1749
1750 static ccp_prop_value_t
evaluate_stmt(gimple * stmt)1751 evaluate_stmt (gimple *stmt)
1752 {
1753 ccp_prop_value_t val;
1754 tree simplified = NULL_TREE;
1755 ccp_lattice_t likelyvalue = likely_value (stmt);
1756 bool is_constant = false;
1757 unsigned int align;
1758
1759 if (dump_file && (dump_flags & TDF_DETAILS))
1760 {
1761 fprintf (dump_file, "which is likely ");
1762 switch (likelyvalue)
1763 {
1764 case CONSTANT:
1765 fprintf (dump_file, "CONSTANT");
1766 break;
1767 case UNDEFINED:
1768 fprintf (dump_file, "UNDEFINED");
1769 break;
1770 case VARYING:
1771 fprintf (dump_file, "VARYING");
1772 break;
1773 default:;
1774 }
1775 fprintf (dump_file, "\n");
1776 }
1777
1778 /* If the statement is likely to have a CONSTANT result, then try
1779 to fold the statement to determine the constant value. */
1780 /* FIXME. This is the only place that we call ccp_fold.
1781 Since likely_value never returns CONSTANT for calls, we will
1782 not attempt to fold them, including builtins that may profit. */
1783 if (likelyvalue == CONSTANT)
1784 {
1785 fold_defer_overflow_warnings ();
1786 simplified = ccp_fold (stmt);
1787 if (simplified
1788 && TREE_CODE (simplified) == SSA_NAME)
1789 {
1790 /* We may not use values of something that may be simulated again,
1791 see valueize_op_1. */
1792 if (SSA_NAME_IS_DEFAULT_DEF (simplified)
1793 || ! prop_simulate_again_p (SSA_NAME_DEF_STMT (simplified)))
1794 {
1795 ccp_prop_value_t *val = get_value (simplified);
1796 if (val && val->lattice_val != VARYING)
1797 {
1798 fold_undefer_overflow_warnings (true, stmt, 0);
1799 return *val;
1800 }
1801 }
1802 else
1803 /* We may also not place a non-valueized copy in the lattice
1804 as that might become stale if we never re-visit this stmt. */
1805 simplified = NULL_TREE;
1806 }
1807 is_constant = simplified && is_gimple_min_invariant (simplified);
1808 fold_undefer_overflow_warnings (is_constant, stmt, 0);
1809 if (is_constant)
1810 {
1811 /* The statement produced a constant value. */
1812 val.lattice_val = CONSTANT;
1813 val.value = simplified;
1814 val.mask = 0;
1815 return val;
1816 }
1817 }
1818 /* If the statement is likely to have a VARYING result, then do not
1819 bother folding the statement. */
1820 else if (likelyvalue == VARYING)
1821 {
1822 enum gimple_code code = gimple_code (stmt);
1823 if (code == GIMPLE_ASSIGN)
1824 {
1825 enum tree_code subcode = gimple_assign_rhs_code (stmt);
1826
1827 /* Other cases cannot satisfy is_gimple_min_invariant
1828 without folding. */
1829 if (get_gimple_rhs_class (subcode) == GIMPLE_SINGLE_RHS)
1830 simplified = gimple_assign_rhs1 (stmt);
1831 }
1832 else if (code == GIMPLE_SWITCH)
1833 simplified = gimple_switch_index (as_a <gswitch *> (stmt));
1834 else
1835 /* These cannot satisfy is_gimple_min_invariant without folding. */
1836 gcc_assert (code == GIMPLE_CALL || code == GIMPLE_COND);
1837 is_constant = simplified && is_gimple_min_invariant (simplified);
1838 if (is_constant)
1839 {
1840 /* The statement produced a constant value. */
1841 val.lattice_val = CONSTANT;
1842 val.value = simplified;
1843 val.mask = 0;
1844 }
1845 }
1846 /* If the statement result is likely UNDEFINED, make it so. */
1847 else if (likelyvalue == UNDEFINED)
1848 {
1849 val.lattice_val = UNDEFINED;
1850 val.value = NULL_TREE;
1851 val.mask = 0;
1852 return val;
1853 }
1854
1855 /* Resort to simplification for bitwise tracking. */
1856 if (flag_tree_bit_ccp
1857 && (likelyvalue == CONSTANT || is_gimple_call (stmt)
1858 || (gimple_assign_single_p (stmt)
1859 && gimple_assign_rhs_code (stmt) == ADDR_EXPR))
1860 && !is_constant)
1861 {
1862 enum gimple_code code = gimple_code (stmt);
1863 val.lattice_val = VARYING;
1864 val.value = NULL_TREE;
1865 val.mask = -1;
1866 if (code == GIMPLE_ASSIGN)
1867 {
1868 enum tree_code subcode = gimple_assign_rhs_code (stmt);
1869 tree rhs1 = gimple_assign_rhs1 (stmt);
1870 tree lhs = gimple_assign_lhs (stmt);
1871 if ((INTEGRAL_TYPE_P (TREE_TYPE (lhs))
1872 || POINTER_TYPE_P (TREE_TYPE (lhs)))
1873 && (INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
1874 || POINTER_TYPE_P (TREE_TYPE (rhs1))))
1875 switch (get_gimple_rhs_class (subcode))
1876 {
1877 case GIMPLE_SINGLE_RHS:
1878 val = get_value_for_expr (rhs1, true);
1879 break;
1880
1881 case GIMPLE_UNARY_RHS:
1882 val = bit_value_unop (subcode, TREE_TYPE (lhs), rhs1);
1883 break;
1884
1885 case GIMPLE_BINARY_RHS:
1886 val = bit_value_binop (subcode, TREE_TYPE (lhs), rhs1,
1887 gimple_assign_rhs2 (stmt));
1888 break;
1889
1890 default:;
1891 }
1892 }
1893 else if (code == GIMPLE_COND)
1894 {
1895 enum tree_code code = gimple_cond_code (stmt);
1896 tree rhs1 = gimple_cond_lhs (stmt);
1897 tree rhs2 = gimple_cond_rhs (stmt);
1898 if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
1899 || POINTER_TYPE_P (TREE_TYPE (rhs1)))
1900 val = bit_value_binop (code, TREE_TYPE (rhs1), rhs1, rhs2);
1901 }
1902 else if (gimple_call_builtin_p (stmt, BUILT_IN_NORMAL))
1903 {
1904 tree fndecl = gimple_call_fndecl (stmt);
1905 switch (DECL_FUNCTION_CODE (fndecl))
1906 {
1907 case BUILT_IN_MALLOC:
1908 case BUILT_IN_REALLOC:
1909 case BUILT_IN_CALLOC:
1910 case BUILT_IN_STRDUP:
1911 case BUILT_IN_STRNDUP:
1912 val.lattice_val = CONSTANT;
1913 val.value = build_int_cst (TREE_TYPE (gimple_get_lhs (stmt)), 0);
1914 val.mask = ~((HOST_WIDE_INT) MALLOC_ABI_ALIGNMENT
1915 / BITS_PER_UNIT - 1);
1916 break;
1917
1918 CASE_BUILT_IN_ALLOCA:
1919 align = (DECL_FUNCTION_CODE (fndecl) == BUILT_IN_ALLOCA
1920 ? BIGGEST_ALIGNMENT
1921 : TREE_INT_CST_LOW (gimple_call_arg (stmt, 1)));
1922 val.lattice_val = CONSTANT;
1923 val.value = build_int_cst (TREE_TYPE (gimple_get_lhs (stmt)), 0);
1924 val.mask = ~((HOST_WIDE_INT) align / BITS_PER_UNIT - 1);
1925 break;
1926
1927 /* These builtins return their first argument, unmodified. */
1928 case BUILT_IN_MEMCPY:
1929 case BUILT_IN_MEMMOVE:
1930 case BUILT_IN_MEMSET:
1931 case BUILT_IN_STRCPY:
1932 case BUILT_IN_STRNCPY:
1933 case BUILT_IN_MEMCPY_CHK:
1934 case BUILT_IN_MEMMOVE_CHK:
1935 case BUILT_IN_MEMSET_CHK:
1936 case BUILT_IN_STRCPY_CHK:
1937 case BUILT_IN_STRNCPY_CHK:
1938 val = get_value_for_expr (gimple_call_arg (stmt, 0), true);
1939 break;
1940
1941 case BUILT_IN_ASSUME_ALIGNED:
1942 val = bit_value_assume_aligned (stmt, NULL_TREE, val, false);
1943 break;
1944
1945 case BUILT_IN_ALIGNED_ALLOC:
1946 {
1947 tree align = get_constant_value (gimple_call_arg (stmt, 0));
1948 if (align
1949 && tree_fits_uhwi_p (align))
1950 {
1951 unsigned HOST_WIDE_INT aligni = tree_to_uhwi (align);
1952 if (aligni > 1
1953 /* align must be power-of-two */
1954 && (aligni & (aligni - 1)) == 0)
1955 {
1956 val.lattice_val = CONSTANT;
1957 val.value = build_int_cst (ptr_type_node, 0);
1958 val.mask = -aligni;
1959 }
1960 }
1961 break;
1962 }
1963
1964 default:;
1965 }
1966 }
1967 if (is_gimple_call (stmt) && gimple_call_lhs (stmt))
1968 {
1969 tree fntype = gimple_call_fntype (stmt);
1970 if (fntype)
1971 {
1972 tree attrs = lookup_attribute ("assume_aligned",
1973 TYPE_ATTRIBUTES (fntype));
1974 if (attrs)
1975 val = bit_value_assume_aligned (stmt, attrs, val, false);
1976 attrs = lookup_attribute ("alloc_align",
1977 TYPE_ATTRIBUTES (fntype));
1978 if (attrs)
1979 val = bit_value_assume_aligned (stmt, attrs, val, true);
1980 }
1981 }
1982 is_constant = (val.lattice_val == CONSTANT);
1983 }
1984
1985 if (flag_tree_bit_ccp
1986 && ((is_constant && TREE_CODE (val.value) == INTEGER_CST)
1987 || !is_constant)
1988 && gimple_get_lhs (stmt)
1989 && TREE_CODE (gimple_get_lhs (stmt)) == SSA_NAME)
1990 {
1991 tree lhs = gimple_get_lhs (stmt);
1992 wide_int nonzero_bits = get_nonzero_bits (lhs);
1993 if (nonzero_bits != -1)
1994 {
1995 if (!is_constant)
1996 {
1997 val.lattice_val = CONSTANT;
1998 val.value = build_zero_cst (TREE_TYPE (lhs));
1999 val.mask = extend_mask (nonzero_bits, TYPE_SIGN (TREE_TYPE (lhs)));
2000 is_constant = true;
2001 }
2002 else
2003 {
2004 if (wi::bit_and_not (wi::to_wide (val.value), nonzero_bits) != 0)
2005 val.value = wide_int_to_tree (TREE_TYPE (lhs),
2006 nonzero_bits
2007 & wi::to_wide (val.value));
2008 if (nonzero_bits == 0)
2009 val.mask = 0;
2010 else
2011 val.mask = val.mask & extend_mask (nonzero_bits,
2012 TYPE_SIGN (TREE_TYPE (lhs)));
2013 }
2014 }
2015 }
2016
2017 /* The statement produced a nonconstant value. */
2018 if (!is_constant)
2019 {
2020 /* The statement produced a copy. */
2021 if (simplified && TREE_CODE (simplified) == SSA_NAME
2022 && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (simplified))
2023 {
2024 val.lattice_val = CONSTANT;
2025 val.value = simplified;
2026 val.mask = -1;
2027 }
2028 /* The statement is VARYING. */
2029 else
2030 {
2031 val.lattice_val = VARYING;
2032 val.value = NULL_TREE;
2033 val.mask = -1;
2034 }
2035 }
2036
2037 return val;
2038 }
2039
2040 typedef hash_table<nofree_ptr_hash<gimple> > gimple_htab;
2041
2042 /* Given a BUILT_IN_STACK_SAVE value SAVED_VAL, insert a clobber of VAR before
2043 each matching BUILT_IN_STACK_RESTORE. Mark visited phis in VISITED. */
2044
2045 static void
insert_clobber_before_stack_restore(tree saved_val,tree var,gimple_htab ** visited)2046 insert_clobber_before_stack_restore (tree saved_val, tree var,
2047 gimple_htab **visited)
2048 {
2049 gimple *stmt;
2050 gassign *clobber_stmt;
2051 tree clobber;
2052 imm_use_iterator iter;
2053 gimple_stmt_iterator i;
2054 gimple **slot;
2055
2056 FOR_EACH_IMM_USE_STMT (stmt, iter, saved_val)
2057 if (gimple_call_builtin_p (stmt, BUILT_IN_STACK_RESTORE))
2058 {
2059 clobber = build_constructor (TREE_TYPE (var),
2060 NULL);
2061 TREE_THIS_VOLATILE (clobber) = 1;
2062 clobber_stmt = gimple_build_assign (var, clobber);
2063
2064 i = gsi_for_stmt (stmt);
2065 gsi_insert_before (&i, clobber_stmt, GSI_SAME_STMT);
2066 }
2067 else if (gimple_code (stmt) == GIMPLE_PHI)
2068 {
2069 if (!*visited)
2070 *visited = new gimple_htab (10);
2071
2072 slot = (*visited)->find_slot (stmt, INSERT);
2073 if (*slot != NULL)
2074 continue;
2075
2076 *slot = stmt;
2077 insert_clobber_before_stack_restore (gimple_phi_result (stmt), var,
2078 visited);
2079 }
2080 else if (gimple_assign_ssa_name_copy_p (stmt))
2081 insert_clobber_before_stack_restore (gimple_assign_lhs (stmt), var,
2082 visited);
2083 else if (chkp_gimple_call_builtin_p (stmt, BUILT_IN_CHKP_BNDRET))
2084 continue;
2085 }
2086
2087 /* Advance the iterator to the previous non-debug gimple statement in the same
2088 or dominating basic block. */
2089
2090 static inline void
gsi_prev_dom_bb_nondebug(gimple_stmt_iterator * i)2091 gsi_prev_dom_bb_nondebug (gimple_stmt_iterator *i)
2092 {
2093 basic_block dom;
2094
2095 gsi_prev_nondebug (i);
2096 while (gsi_end_p (*i))
2097 {
2098 dom = get_immediate_dominator (CDI_DOMINATORS, i->bb);
2099 if (dom == NULL || dom == ENTRY_BLOCK_PTR_FOR_FN (cfun))
2100 return;
2101
2102 *i = gsi_last_bb (dom);
2103 }
2104 }
2105
2106 /* Find a BUILT_IN_STACK_SAVE dominating gsi_stmt (I), and insert
2107 a clobber of VAR before each matching BUILT_IN_STACK_RESTORE.
2108
2109 It is possible that BUILT_IN_STACK_SAVE cannot be found in a dominator when
2110 a previous pass (such as DOM) duplicated it along multiple paths to a BB.
2111 In that case the function gives up without inserting the clobbers. */
2112
2113 static void
insert_clobbers_for_var(gimple_stmt_iterator i,tree var)2114 insert_clobbers_for_var (gimple_stmt_iterator i, tree var)
2115 {
2116 gimple *stmt;
2117 tree saved_val;
2118 gimple_htab *visited = NULL;
2119
2120 for (; !gsi_end_p (i); gsi_prev_dom_bb_nondebug (&i))
2121 {
2122 stmt = gsi_stmt (i);
2123
2124 if (!gimple_call_builtin_p (stmt, BUILT_IN_STACK_SAVE))
2125 continue;
2126
2127 saved_val = gimple_call_lhs (stmt);
2128 if (saved_val == NULL_TREE)
2129 continue;
2130
2131 insert_clobber_before_stack_restore (saved_val, var, &visited);
2132 break;
2133 }
2134
2135 delete visited;
2136 }
2137
2138 /* Detects a __builtin_alloca_with_align with constant size argument. Declares
2139 fixed-size array and returns the address, if found, otherwise returns
2140 NULL_TREE. */
2141
2142 static tree
fold_builtin_alloca_with_align(gimple * stmt)2143 fold_builtin_alloca_with_align (gimple *stmt)
2144 {
2145 unsigned HOST_WIDE_INT size, threshold, n_elem;
2146 tree lhs, arg, block, var, elem_type, array_type;
2147
2148 /* Get lhs. */
2149 lhs = gimple_call_lhs (stmt);
2150 if (lhs == NULL_TREE)
2151 return NULL_TREE;
2152
2153 /* Detect constant argument. */
2154 arg = get_constant_value (gimple_call_arg (stmt, 0));
2155 if (arg == NULL_TREE
2156 || TREE_CODE (arg) != INTEGER_CST
2157 || !tree_fits_uhwi_p (arg))
2158 return NULL_TREE;
2159
2160 size = tree_to_uhwi (arg);
2161
2162 /* Heuristic: don't fold large allocas. */
2163 threshold = (unsigned HOST_WIDE_INT)PARAM_VALUE (PARAM_LARGE_STACK_FRAME);
2164 /* In case the alloca is located at function entry, it has the same lifetime
2165 as a declared array, so we allow a larger size. */
2166 block = gimple_block (stmt);
2167 if (!(cfun->after_inlining
2168 && block
2169 && TREE_CODE (BLOCK_SUPERCONTEXT (block)) == FUNCTION_DECL))
2170 threshold /= 10;
2171 if (size > threshold)
2172 return NULL_TREE;
2173
2174 /* Declare array. */
2175 elem_type = build_nonstandard_integer_type (BITS_PER_UNIT, 1);
2176 n_elem = size * 8 / BITS_PER_UNIT;
2177 array_type = build_array_type_nelts (elem_type, n_elem);
2178 var = create_tmp_var (array_type);
2179 SET_DECL_ALIGN (var, TREE_INT_CST_LOW (gimple_call_arg (stmt, 1)));
2180 {
2181 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (lhs);
2182 if (pi != NULL && !pi->pt.anything)
2183 {
2184 bool singleton_p;
2185 unsigned uid;
2186 singleton_p = pt_solution_singleton_or_null_p (&pi->pt, &uid);
2187 gcc_assert (singleton_p);
2188 SET_DECL_PT_UID (var, uid);
2189 }
2190 }
2191
2192 /* Fold alloca to the address of the array. */
2193 return fold_convert (TREE_TYPE (lhs), build_fold_addr_expr (var));
2194 }
2195
2196 /* Fold the stmt at *GSI with CCP specific information that propagating
2197 and regular folding does not catch. */
2198
2199 bool
fold_stmt(gimple_stmt_iterator * gsi)2200 ccp_folder::fold_stmt (gimple_stmt_iterator *gsi)
2201 {
2202 gimple *stmt = gsi_stmt (*gsi);
2203
2204 switch (gimple_code (stmt))
2205 {
2206 case GIMPLE_COND:
2207 {
2208 gcond *cond_stmt = as_a <gcond *> (stmt);
2209 ccp_prop_value_t val;
2210 /* Statement evaluation will handle type mismatches in constants
2211 more gracefully than the final propagation. This allows us to
2212 fold more conditionals here. */
2213 val = evaluate_stmt (stmt);
2214 if (val.lattice_val != CONSTANT
2215 || val.mask != 0)
2216 return false;
2217
2218 if (dump_file)
2219 {
2220 fprintf (dump_file, "Folding predicate ");
2221 print_gimple_expr (dump_file, stmt, 0);
2222 fprintf (dump_file, " to ");
2223 print_generic_expr (dump_file, val.value);
2224 fprintf (dump_file, "\n");
2225 }
2226
2227 if (integer_zerop (val.value))
2228 gimple_cond_make_false (cond_stmt);
2229 else
2230 gimple_cond_make_true (cond_stmt);
2231
2232 return true;
2233 }
2234
2235 case GIMPLE_CALL:
2236 {
2237 tree lhs = gimple_call_lhs (stmt);
2238 int flags = gimple_call_flags (stmt);
2239 tree val;
2240 tree argt;
2241 bool changed = false;
2242 unsigned i;
2243
2244 /* If the call was folded into a constant make sure it goes
2245 away even if we cannot propagate into all uses because of
2246 type issues. */
2247 if (lhs
2248 && TREE_CODE (lhs) == SSA_NAME
2249 && (val = get_constant_value (lhs))
2250 /* Don't optimize away calls that have side-effects. */
2251 && (flags & (ECF_CONST|ECF_PURE)) != 0
2252 && (flags & ECF_LOOPING_CONST_OR_PURE) == 0)
2253 {
2254 tree new_rhs = unshare_expr (val);
2255 bool res;
2256 if (!useless_type_conversion_p (TREE_TYPE (lhs),
2257 TREE_TYPE (new_rhs)))
2258 new_rhs = fold_convert (TREE_TYPE (lhs), new_rhs);
2259 res = update_call_from_tree (gsi, new_rhs);
2260 gcc_assert (res);
2261 return true;
2262 }
2263
2264 /* Internal calls provide no argument types, so the extra laxity
2265 for normal calls does not apply. */
2266 if (gimple_call_internal_p (stmt))
2267 return false;
2268
2269 /* The heuristic of fold_builtin_alloca_with_align differs before and
2270 after inlining, so we don't require the arg to be changed into a
2271 constant for folding, but just to be constant. */
2272 if (gimple_call_builtin_p (stmt, BUILT_IN_ALLOCA_WITH_ALIGN)
2273 || gimple_call_builtin_p (stmt, BUILT_IN_ALLOCA_WITH_ALIGN_AND_MAX))
2274 {
2275 tree new_rhs = fold_builtin_alloca_with_align (stmt);
2276 if (new_rhs)
2277 {
2278 bool res = update_call_from_tree (gsi, new_rhs);
2279 tree var = TREE_OPERAND (TREE_OPERAND (new_rhs, 0),0);
2280 gcc_assert (res);
2281 insert_clobbers_for_var (*gsi, var);
2282 return true;
2283 }
2284 }
2285
2286 /* Propagate into the call arguments. Compared to replace_uses_in
2287 this can use the argument slot types for type verification
2288 instead of the current argument type. We also can safely
2289 drop qualifiers here as we are dealing with constants anyway. */
2290 argt = TYPE_ARG_TYPES (gimple_call_fntype (stmt));
2291 for (i = 0; i < gimple_call_num_args (stmt) && argt;
2292 ++i, argt = TREE_CHAIN (argt))
2293 {
2294 tree arg = gimple_call_arg (stmt, i);
2295 if (TREE_CODE (arg) == SSA_NAME
2296 && (val = get_constant_value (arg))
2297 && useless_type_conversion_p
2298 (TYPE_MAIN_VARIANT (TREE_VALUE (argt)),
2299 TYPE_MAIN_VARIANT (TREE_TYPE (val))))
2300 {
2301 gimple_call_set_arg (stmt, i, unshare_expr (val));
2302 changed = true;
2303 }
2304 }
2305
2306 return changed;
2307 }
2308
2309 case GIMPLE_ASSIGN:
2310 {
2311 tree lhs = gimple_assign_lhs (stmt);
2312 tree val;
2313
2314 /* If we have a load that turned out to be constant replace it
2315 as we cannot propagate into all uses in all cases. */
2316 if (gimple_assign_single_p (stmt)
2317 && TREE_CODE (lhs) == SSA_NAME
2318 && (val = get_constant_value (lhs)))
2319 {
2320 tree rhs = unshare_expr (val);
2321 if (!useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (rhs)))
2322 rhs = fold_build1 (VIEW_CONVERT_EXPR, TREE_TYPE (lhs), rhs);
2323 gimple_assign_set_rhs_from_tree (gsi, rhs);
2324 return true;
2325 }
2326
2327 return false;
2328 }
2329
2330 default:
2331 return false;
2332 }
2333 }
2334
2335 /* Visit the assignment statement STMT. Set the value of its LHS to the
2336 value computed by the RHS and store LHS in *OUTPUT_P. If STMT
2337 creates virtual definitions, set the value of each new name to that
2338 of the RHS (if we can derive a constant out of the RHS).
2339 Value-returning call statements also perform an assignment, and
2340 are handled here. */
2341
2342 static enum ssa_prop_result
visit_assignment(gimple * stmt,tree * output_p)2343 visit_assignment (gimple *stmt, tree *output_p)
2344 {
2345 ccp_prop_value_t val;
2346 enum ssa_prop_result retval = SSA_PROP_NOT_INTERESTING;
2347
2348 tree lhs = gimple_get_lhs (stmt);
2349 if (TREE_CODE (lhs) == SSA_NAME)
2350 {
2351 /* Evaluate the statement, which could be
2352 either a GIMPLE_ASSIGN or a GIMPLE_CALL. */
2353 val = evaluate_stmt (stmt);
2354
2355 /* If STMT is an assignment to an SSA_NAME, we only have one
2356 value to set. */
2357 if (set_lattice_value (lhs, &val))
2358 {
2359 *output_p = lhs;
2360 if (val.lattice_val == VARYING)
2361 retval = SSA_PROP_VARYING;
2362 else
2363 retval = SSA_PROP_INTERESTING;
2364 }
2365 }
2366
2367 return retval;
2368 }
2369
2370
2371 /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING
2372 if it can determine which edge will be taken. Otherwise, return
2373 SSA_PROP_VARYING. */
2374
2375 static enum ssa_prop_result
visit_cond_stmt(gimple * stmt,edge * taken_edge_p)2376 visit_cond_stmt (gimple *stmt, edge *taken_edge_p)
2377 {
2378 ccp_prop_value_t val;
2379 basic_block block;
2380
2381 block = gimple_bb (stmt);
2382 val = evaluate_stmt (stmt);
2383 if (val.lattice_val != CONSTANT
2384 || val.mask != 0)
2385 return SSA_PROP_VARYING;
2386
2387 /* Find which edge out of the conditional block will be taken and add it
2388 to the worklist. If no single edge can be determined statically,
2389 return SSA_PROP_VARYING to feed all the outgoing edges to the
2390 propagation engine. */
2391 *taken_edge_p = find_taken_edge (block, val.value);
2392 if (*taken_edge_p)
2393 return SSA_PROP_INTERESTING;
2394 else
2395 return SSA_PROP_VARYING;
2396 }
2397
2398
2399 /* Evaluate statement STMT. If the statement produces an output value and
2400 its evaluation changes the lattice value of its output, return
2401 SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the
2402 output value.
2403
2404 If STMT is a conditional branch and we can determine its truth
2405 value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying
2406 value, return SSA_PROP_VARYING. */
2407
2408 enum ssa_prop_result
visit_stmt(gimple * stmt,edge * taken_edge_p,tree * output_p)2409 ccp_propagate::visit_stmt (gimple *stmt, edge *taken_edge_p, tree *output_p)
2410 {
2411 tree def;
2412 ssa_op_iter iter;
2413
2414 if (dump_file && (dump_flags & TDF_DETAILS))
2415 {
2416 fprintf (dump_file, "\nVisiting statement:\n");
2417 print_gimple_stmt (dump_file, stmt, 0, dump_flags);
2418 }
2419
2420 switch (gimple_code (stmt))
2421 {
2422 case GIMPLE_ASSIGN:
2423 /* If the statement is an assignment that produces a single
2424 output value, evaluate its RHS to see if the lattice value of
2425 its output has changed. */
2426 return visit_assignment (stmt, output_p);
2427
2428 case GIMPLE_CALL:
2429 /* A value-returning call also performs an assignment. */
2430 if (gimple_call_lhs (stmt) != NULL_TREE)
2431 return visit_assignment (stmt, output_p);
2432 break;
2433
2434 case GIMPLE_COND:
2435 case GIMPLE_SWITCH:
2436 /* If STMT is a conditional branch, see if we can determine
2437 which branch will be taken. */
2438 /* FIXME. It appears that we should be able to optimize
2439 computed GOTOs here as well. */
2440 return visit_cond_stmt (stmt, taken_edge_p);
2441
2442 default:
2443 break;
2444 }
2445
2446 /* Any other kind of statement is not interesting for constant
2447 propagation and, therefore, not worth simulating. */
2448 if (dump_file && (dump_flags & TDF_DETAILS))
2449 fprintf (dump_file, "No interesting values produced. Marked VARYING.\n");
2450
2451 /* Definitions made by statements other than assignments to
2452 SSA_NAMEs represent unknown modifications to their outputs.
2453 Mark them VARYING. */
2454 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
2455 set_value_varying (def);
2456
2457 return SSA_PROP_VARYING;
2458 }
2459
2460
2461 /* Main entry point for SSA Conditional Constant Propagation. If NONZERO_P,
2462 record nonzero bits. */
2463
2464 static unsigned int
do_ssa_ccp(bool nonzero_p)2465 do_ssa_ccp (bool nonzero_p)
2466 {
2467 unsigned int todo = 0;
2468 calculate_dominance_info (CDI_DOMINATORS);
2469
2470 ccp_initialize ();
2471 class ccp_propagate ccp_propagate;
2472 ccp_propagate.ssa_propagate ();
2473 if (ccp_finalize (nonzero_p || flag_ipa_bit_cp))
2474 {
2475 todo = (TODO_cleanup_cfg | TODO_update_ssa);
2476
2477 /* ccp_finalize does not preserve loop-closed ssa. */
2478 loops_state_clear (LOOP_CLOSED_SSA);
2479 }
2480
2481 free_dominance_info (CDI_DOMINATORS);
2482 return todo;
2483 }
2484
2485
2486 namespace {
2487
2488 const pass_data pass_data_ccp =
2489 {
2490 GIMPLE_PASS, /* type */
2491 "ccp", /* name */
2492 OPTGROUP_NONE, /* optinfo_flags */
2493 TV_TREE_CCP, /* tv_id */
2494 ( PROP_cfg | PROP_ssa ), /* properties_required */
2495 0, /* properties_provided */
2496 0, /* properties_destroyed */
2497 0, /* todo_flags_start */
2498 TODO_update_address_taken, /* todo_flags_finish */
2499 };
2500
2501 class pass_ccp : public gimple_opt_pass
2502 {
2503 public:
pass_ccp(gcc::context * ctxt)2504 pass_ccp (gcc::context *ctxt)
2505 : gimple_opt_pass (pass_data_ccp, ctxt), nonzero_p (false)
2506 {}
2507
2508 /* opt_pass methods: */
clone()2509 opt_pass * clone () { return new pass_ccp (m_ctxt); }
set_pass_param(unsigned int n,bool param)2510 void set_pass_param (unsigned int n, bool param)
2511 {
2512 gcc_assert (n == 0);
2513 nonzero_p = param;
2514 }
gate(function *)2515 virtual bool gate (function *) { return flag_tree_ccp != 0; }
execute(function *)2516 virtual unsigned int execute (function *) { return do_ssa_ccp (nonzero_p); }
2517
2518 private:
2519 /* Determines whether the pass instance records nonzero bits. */
2520 bool nonzero_p;
2521 }; // class pass_ccp
2522
2523 } // anon namespace
2524
2525 gimple_opt_pass *
make_pass_ccp(gcc::context * ctxt)2526 make_pass_ccp (gcc::context *ctxt)
2527 {
2528 return new pass_ccp (ctxt);
2529 }
2530
2531
2532
2533 /* Try to optimize out __builtin_stack_restore. Optimize it out
2534 if there is another __builtin_stack_restore in the same basic
2535 block and no calls or ASM_EXPRs are in between, or if this block's
2536 only outgoing edge is to EXIT_BLOCK and there are no calls or
2537 ASM_EXPRs after this __builtin_stack_restore. */
2538
2539 static tree
optimize_stack_restore(gimple_stmt_iterator i)2540 optimize_stack_restore (gimple_stmt_iterator i)
2541 {
2542 tree callee;
2543 gimple *stmt;
2544
2545 basic_block bb = gsi_bb (i);
2546 gimple *call = gsi_stmt (i);
2547
2548 if (gimple_code (call) != GIMPLE_CALL
2549 || gimple_call_num_args (call) != 1
2550 || TREE_CODE (gimple_call_arg (call, 0)) != SSA_NAME
2551 || !POINTER_TYPE_P (TREE_TYPE (gimple_call_arg (call, 0))))
2552 return NULL_TREE;
2553
2554 for (gsi_next (&i); !gsi_end_p (i); gsi_next (&i))
2555 {
2556 stmt = gsi_stmt (i);
2557 if (gimple_code (stmt) == GIMPLE_ASM)
2558 return NULL_TREE;
2559 if (gimple_code (stmt) != GIMPLE_CALL)
2560 continue;
2561
2562 callee = gimple_call_fndecl (stmt);
2563 if (!callee
2564 || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL
2565 /* All regular builtins are ok, just obviously not alloca. */
2566 || ALLOCA_FUNCTION_CODE_P (DECL_FUNCTION_CODE (callee)))
2567 return NULL_TREE;
2568
2569 if (DECL_FUNCTION_CODE (callee) == BUILT_IN_STACK_RESTORE)
2570 goto second_stack_restore;
2571 }
2572
2573 if (!gsi_end_p (i))
2574 return NULL_TREE;
2575
2576 /* Allow one successor of the exit block, or zero successors. */
2577 switch (EDGE_COUNT (bb->succs))
2578 {
2579 case 0:
2580 break;
2581 case 1:
2582 if (single_succ_edge (bb)->dest != EXIT_BLOCK_PTR_FOR_FN (cfun))
2583 return NULL_TREE;
2584 break;
2585 default:
2586 return NULL_TREE;
2587 }
2588 second_stack_restore:
2589
2590 /* If there's exactly one use, then zap the call to __builtin_stack_save.
2591 If there are multiple uses, then the last one should remove the call.
2592 In any case, whether the call to __builtin_stack_save can be removed
2593 or not is irrelevant to removing the call to __builtin_stack_restore. */
2594 if (has_single_use (gimple_call_arg (call, 0)))
2595 {
2596 gimple *stack_save = SSA_NAME_DEF_STMT (gimple_call_arg (call, 0));
2597 if (is_gimple_call (stack_save))
2598 {
2599 callee = gimple_call_fndecl (stack_save);
2600 if (callee
2601 && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL
2602 && DECL_FUNCTION_CODE (callee) == BUILT_IN_STACK_SAVE)
2603 {
2604 gimple_stmt_iterator stack_save_gsi;
2605 tree rhs;
2606
2607 stack_save_gsi = gsi_for_stmt (stack_save);
2608 rhs = build_int_cst (TREE_TYPE (gimple_call_arg (call, 0)), 0);
2609 update_call_from_tree (&stack_save_gsi, rhs);
2610 }
2611 }
2612 }
2613
2614 /* No effect, so the statement will be deleted. */
2615 return integer_zero_node;
2616 }
2617
2618 /* If va_list type is a simple pointer and nothing special is needed,
2619 optimize __builtin_va_start (&ap, 0) into ap = __builtin_next_arg (0),
2620 __builtin_va_end (&ap) out as NOP and __builtin_va_copy into a simple
2621 pointer assignment. */
2622
2623 static tree
optimize_stdarg_builtin(gimple * call)2624 optimize_stdarg_builtin (gimple *call)
2625 {
2626 tree callee, lhs, rhs, cfun_va_list;
2627 bool va_list_simple_ptr;
2628 location_t loc = gimple_location (call);
2629
2630 if (gimple_code (call) != GIMPLE_CALL)
2631 return NULL_TREE;
2632
2633 callee = gimple_call_fndecl (call);
2634
2635 cfun_va_list = targetm.fn_abi_va_list (callee);
2636 va_list_simple_ptr = POINTER_TYPE_P (cfun_va_list)
2637 && (TREE_TYPE (cfun_va_list) == void_type_node
2638 || TREE_TYPE (cfun_va_list) == char_type_node);
2639
2640 switch (DECL_FUNCTION_CODE (callee))
2641 {
2642 case BUILT_IN_VA_START:
2643 if (!va_list_simple_ptr
2644 || targetm.expand_builtin_va_start != NULL
2645 || !builtin_decl_explicit_p (BUILT_IN_NEXT_ARG))
2646 return NULL_TREE;
2647
2648 if (gimple_call_num_args (call) != 2)
2649 return NULL_TREE;
2650
2651 lhs = gimple_call_arg (call, 0);
2652 if (!POINTER_TYPE_P (TREE_TYPE (lhs))
2653 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs)))
2654 != TYPE_MAIN_VARIANT (cfun_va_list))
2655 return NULL_TREE;
2656
2657 lhs = build_fold_indirect_ref_loc (loc, lhs);
2658 rhs = build_call_expr_loc (loc, builtin_decl_explicit (BUILT_IN_NEXT_ARG),
2659 1, integer_zero_node);
2660 rhs = fold_convert_loc (loc, TREE_TYPE (lhs), rhs);
2661 return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs);
2662
2663 case BUILT_IN_VA_COPY:
2664 if (!va_list_simple_ptr)
2665 return NULL_TREE;
2666
2667 if (gimple_call_num_args (call) != 2)
2668 return NULL_TREE;
2669
2670 lhs = gimple_call_arg (call, 0);
2671 if (!POINTER_TYPE_P (TREE_TYPE (lhs))
2672 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs)))
2673 != TYPE_MAIN_VARIANT (cfun_va_list))
2674 return NULL_TREE;
2675
2676 lhs = build_fold_indirect_ref_loc (loc, lhs);
2677 rhs = gimple_call_arg (call, 1);
2678 if (TYPE_MAIN_VARIANT (TREE_TYPE (rhs))
2679 != TYPE_MAIN_VARIANT (cfun_va_list))
2680 return NULL_TREE;
2681
2682 rhs = fold_convert_loc (loc, TREE_TYPE (lhs), rhs);
2683 return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs);
2684
2685 case BUILT_IN_VA_END:
2686 /* No effect, so the statement will be deleted. */
2687 return integer_zero_node;
2688
2689 default:
2690 gcc_unreachable ();
2691 }
2692 }
2693
2694 /* Attemp to make the block of __builtin_unreachable I unreachable by changing
2695 the incoming jumps. Return true if at least one jump was changed. */
2696
2697 static bool
optimize_unreachable(gimple_stmt_iterator i)2698 optimize_unreachable (gimple_stmt_iterator i)
2699 {
2700 basic_block bb = gsi_bb (i);
2701 gimple_stmt_iterator gsi;
2702 gimple *stmt;
2703 edge_iterator ei;
2704 edge e;
2705 bool ret;
2706
2707 if (flag_sanitize & SANITIZE_UNREACHABLE)
2708 return false;
2709
2710 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
2711 {
2712 stmt = gsi_stmt (gsi);
2713
2714 if (is_gimple_debug (stmt))
2715 continue;
2716
2717 if (glabel *label_stmt = dyn_cast <glabel *> (stmt))
2718 {
2719 /* Verify we do not need to preserve the label. */
2720 if (FORCED_LABEL (gimple_label_label (label_stmt)))
2721 return false;
2722
2723 continue;
2724 }
2725
2726 /* Only handle the case that __builtin_unreachable is the first statement
2727 in the block. We rely on DCE to remove stmts without side-effects
2728 before __builtin_unreachable. */
2729 if (gsi_stmt (gsi) != gsi_stmt (i))
2730 return false;
2731 }
2732
2733 ret = false;
2734 FOR_EACH_EDGE (e, ei, bb->preds)
2735 {
2736 gsi = gsi_last_bb (e->src);
2737 if (gsi_end_p (gsi))
2738 continue;
2739
2740 stmt = gsi_stmt (gsi);
2741 if (gcond *cond_stmt = dyn_cast <gcond *> (stmt))
2742 {
2743 if (e->flags & EDGE_TRUE_VALUE)
2744 gimple_cond_make_false (cond_stmt);
2745 else if (e->flags & EDGE_FALSE_VALUE)
2746 gimple_cond_make_true (cond_stmt);
2747 else
2748 gcc_unreachable ();
2749 update_stmt (cond_stmt);
2750 }
2751 else
2752 {
2753 /* Todo: handle other cases. Note that unreachable switch case
2754 statements have already been removed. */
2755 continue;
2756 }
2757
2758 ret = true;
2759 }
2760
2761 return ret;
2762 }
2763
2764 /* Optimize
2765 mask_2 = 1 << cnt_1;
2766 _4 = __atomic_fetch_or_* (ptr_6, mask_2, _3);
2767 _5 = _4 & mask_2;
2768 to
2769 _4 = ATOMIC_BIT_TEST_AND_SET (ptr_6, cnt_1, 0, _3);
2770 _5 = _4;
2771 If _5 is only used in _5 != 0 or _5 == 0 comparisons, 1
2772 is passed instead of 0, and the builtin just returns a zero
2773 or 1 value instead of the actual bit.
2774 Similarly for __sync_fetch_and_or_* (without the ", _3" part
2775 in there), and/or if mask_2 is a power of 2 constant.
2776 Similarly for xor instead of or, use ATOMIC_BIT_TEST_AND_COMPLEMENT
2777 in that case. And similarly for and instead of or, except that
2778 the second argument to the builtin needs to be one's complement
2779 of the mask instead of mask. */
2780
2781 static void
optimize_atomic_bit_test_and(gimple_stmt_iterator * gsip,enum internal_fn fn,bool has_model_arg,bool after)2782 optimize_atomic_bit_test_and (gimple_stmt_iterator *gsip,
2783 enum internal_fn fn, bool has_model_arg,
2784 bool after)
2785 {
2786 gimple *call = gsi_stmt (*gsip);
2787 tree lhs = gimple_call_lhs (call);
2788 use_operand_p use_p;
2789 gimple *use_stmt;
2790 tree mask, bit;
2791 optab optab;
2792
2793 if (!flag_inline_atomics
2794 || optimize_debug
2795 || !gimple_call_builtin_p (call, BUILT_IN_NORMAL)
2796 || !lhs
2797 || SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs)
2798 || !single_imm_use (lhs, &use_p, &use_stmt)
2799 || !is_gimple_assign (use_stmt)
2800 || gimple_assign_rhs_code (use_stmt) != BIT_AND_EXPR
2801 || !gimple_vdef (call))
2802 return;
2803
2804 switch (fn)
2805 {
2806 case IFN_ATOMIC_BIT_TEST_AND_SET:
2807 optab = atomic_bit_test_and_set_optab;
2808 break;
2809 case IFN_ATOMIC_BIT_TEST_AND_COMPLEMENT:
2810 optab = atomic_bit_test_and_complement_optab;
2811 break;
2812 case IFN_ATOMIC_BIT_TEST_AND_RESET:
2813 optab = atomic_bit_test_and_reset_optab;
2814 break;
2815 default:
2816 return;
2817 }
2818
2819 if (optab_handler (optab, TYPE_MODE (TREE_TYPE (lhs))) == CODE_FOR_nothing)
2820 return;
2821
2822 mask = gimple_call_arg (call, 1);
2823 tree use_lhs = gimple_assign_lhs (use_stmt);
2824 if (!use_lhs)
2825 return;
2826
2827 if (TREE_CODE (mask) == INTEGER_CST)
2828 {
2829 if (fn == IFN_ATOMIC_BIT_TEST_AND_RESET)
2830 mask = const_unop (BIT_NOT_EXPR, TREE_TYPE (mask), mask);
2831 mask = fold_convert (TREE_TYPE (lhs), mask);
2832 int ibit = tree_log2 (mask);
2833 if (ibit < 0)
2834 return;
2835 bit = build_int_cst (TREE_TYPE (lhs), ibit);
2836 }
2837 else if (TREE_CODE (mask) == SSA_NAME)
2838 {
2839 gimple *g = SSA_NAME_DEF_STMT (mask);
2840 if (fn == IFN_ATOMIC_BIT_TEST_AND_RESET)
2841 {
2842 if (!is_gimple_assign (g)
2843 || gimple_assign_rhs_code (g) != BIT_NOT_EXPR)
2844 return;
2845 mask = gimple_assign_rhs1 (g);
2846 if (TREE_CODE (mask) != SSA_NAME)
2847 return;
2848 g = SSA_NAME_DEF_STMT (mask);
2849 }
2850 if (!is_gimple_assign (g)
2851 || gimple_assign_rhs_code (g) != LSHIFT_EXPR
2852 || !integer_onep (gimple_assign_rhs1 (g)))
2853 return;
2854 bit = gimple_assign_rhs2 (g);
2855 }
2856 else
2857 return;
2858
2859 if (gimple_assign_rhs1 (use_stmt) == lhs)
2860 {
2861 if (!operand_equal_p (gimple_assign_rhs2 (use_stmt), mask, 0))
2862 return;
2863 }
2864 else if (gimple_assign_rhs2 (use_stmt) != lhs
2865 || !operand_equal_p (gimple_assign_rhs1 (use_stmt), mask, 0))
2866 return;
2867
2868 bool use_bool = true;
2869 bool has_debug_uses = false;
2870 imm_use_iterator iter;
2871 gimple *g;
2872
2873 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (use_lhs))
2874 use_bool = false;
2875 FOR_EACH_IMM_USE_STMT (g, iter, use_lhs)
2876 {
2877 enum tree_code code = ERROR_MARK;
2878 tree op0 = NULL_TREE, op1 = NULL_TREE;
2879 if (is_gimple_debug (g))
2880 {
2881 has_debug_uses = true;
2882 continue;
2883 }
2884 else if (is_gimple_assign (g))
2885 switch (gimple_assign_rhs_code (g))
2886 {
2887 case COND_EXPR:
2888 op1 = gimple_assign_rhs1 (g);
2889 code = TREE_CODE (op1);
2890 op0 = TREE_OPERAND (op1, 0);
2891 op1 = TREE_OPERAND (op1, 1);
2892 break;
2893 case EQ_EXPR:
2894 case NE_EXPR:
2895 code = gimple_assign_rhs_code (g);
2896 op0 = gimple_assign_rhs1 (g);
2897 op1 = gimple_assign_rhs2 (g);
2898 break;
2899 default:
2900 break;
2901 }
2902 else if (gimple_code (g) == GIMPLE_COND)
2903 {
2904 code = gimple_cond_code (g);
2905 op0 = gimple_cond_lhs (g);
2906 op1 = gimple_cond_rhs (g);
2907 }
2908
2909 if ((code == EQ_EXPR || code == NE_EXPR)
2910 && op0 == use_lhs
2911 && integer_zerop (op1))
2912 {
2913 use_operand_p use_p;
2914 int n = 0;
2915 FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
2916 n++;
2917 if (n == 1)
2918 continue;
2919 }
2920
2921 use_bool = false;
2922 BREAK_FROM_IMM_USE_STMT (iter);
2923 }
2924
2925 tree new_lhs = make_ssa_name (TREE_TYPE (lhs));
2926 tree flag = build_int_cst (TREE_TYPE (lhs), use_bool);
2927 if (has_model_arg)
2928 g = gimple_build_call_internal (fn, 4, gimple_call_arg (call, 0),
2929 bit, flag, gimple_call_arg (call, 2));
2930 else
2931 g = gimple_build_call_internal (fn, 3, gimple_call_arg (call, 0),
2932 bit, flag);
2933 gimple_call_set_lhs (g, new_lhs);
2934 gimple_set_location (g, gimple_location (call));
2935 gimple_set_vuse (g, gimple_vuse (call));
2936 gimple_set_vdef (g, gimple_vdef (call));
2937 bool throws = stmt_can_throw_internal (call);
2938 gimple_call_set_nothrow (as_a <gcall *> (g),
2939 gimple_call_nothrow_p (as_a <gcall *> (call)));
2940 SSA_NAME_DEF_STMT (gimple_vdef (call)) = g;
2941 gimple_stmt_iterator gsi = *gsip;
2942 gsi_insert_after (&gsi, g, GSI_NEW_STMT);
2943 edge e = NULL;
2944 if (throws)
2945 {
2946 maybe_clean_or_replace_eh_stmt (call, g);
2947 if (after || (use_bool && has_debug_uses))
2948 e = find_fallthru_edge (gsi_bb (gsi)->succs);
2949 }
2950 if (after)
2951 {
2952 /* The internal function returns the value of the specified bit
2953 before the atomic operation. If we are interested in the value
2954 of the specified bit after the atomic operation (makes only sense
2955 for xor, otherwise the bit content is compile time known),
2956 we need to invert the bit. */
2957 g = gimple_build_assign (make_ssa_name (TREE_TYPE (lhs)),
2958 BIT_XOR_EXPR, new_lhs,
2959 use_bool ? build_int_cst (TREE_TYPE (lhs), 1)
2960 : mask);
2961 new_lhs = gimple_assign_lhs (g);
2962 if (throws)
2963 {
2964 gsi_insert_on_edge_immediate (e, g);
2965 gsi = gsi_for_stmt (g);
2966 }
2967 else
2968 gsi_insert_after (&gsi, g, GSI_NEW_STMT);
2969 }
2970 if (use_bool && has_debug_uses)
2971 {
2972 tree temp = NULL_TREE;
2973 if (!throws || after || single_pred_p (e->dest))
2974 {
2975 temp = make_node (DEBUG_EXPR_DECL);
2976 DECL_ARTIFICIAL (temp) = 1;
2977 TREE_TYPE (temp) = TREE_TYPE (lhs);
2978 SET_DECL_MODE (temp, TYPE_MODE (TREE_TYPE (lhs)));
2979 tree t = build2 (LSHIFT_EXPR, TREE_TYPE (lhs), new_lhs, bit);
2980 g = gimple_build_debug_bind (temp, t, g);
2981 if (throws && !after)
2982 {
2983 gsi = gsi_after_labels (e->dest);
2984 gsi_insert_before (&gsi, g, GSI_SAME_STMT);
2985 }
2986 else
2987 gsi_insert_after (&gsi, g, GSI_NEW_STMT);
2988 }
2989 FOR_EACH_IMM_USE_STMT (g, iter, use_lhs)
2990 if (is_gimple_debug (g))
2991 {
2992 use_operand_p use_p;
2993 if (temp == NULL_TREE)
2994 gimple_debug_bind_reset_value (g);
2995 else
2996 FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
2997 SET_USE (use_p, temp);
2998 update_stmt (g);
2999 }
3000 }
3001 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (new_lhs)
3002 = SSA_NAME_OCCURS_IN_ABNORMAL_PHI (use_lhs);
3003 replace_uses_by (use_lhs, new_lhs);
3004 gsi = gsi_for_stmt (use_stmt);
3005 gsi_remove (&gsi, true);
3006 release_defs (use_stmt);
3007 gsi_remove (gsip, true);
3008 release_ssa_name (lhs);
3009 }
3010
3011 /* Optimize
3012 a = {};
3013 b = a;
3014 into
3015 a = {};
3016 b = {};
3017 Similarly for memset (&a, ..., sizeof (a)); instead of a = {};
3018 and/or memcpy (&b, &a, sizeof (a)); instead of b = a; */
3019
3020 static void
optimize_memcpy(gimple_stmt_iterator * gsip,tree dest,tree src,tree len)3021 optimize_memcpy (gimple_stmt_iterator *gsip, tree dest, tree src, tree len)
3022 {
3023 gimple *stmt = gsi_stmt (*gsip);
3024 if (gimple_has_volatile_ops (stmt))
3025 return;
3026
3027 tree vuse = gimple_vuse (stmt);
3028 if (vuse == NULL)
3029 return;
3030
3031 gimple *defstmt = SSA_NAME_DEF_STMT (vuse);
3032 tree src2 = NULL_TREE, len2 = NULL_TREE;
3033 poly_int64 offset, offset2;
3034 tree val = integer_zero_node;
3035 if (gimple_store_p (defstmt)
3036 && gimple_assign_single_p (defstmt)
3037 && TREE_CODE (gimple_assign_rhs1 (defstmt)) == CONSTRUCTOR
3038 && !gimple_clobber_p (defstmt))
3039 src2 = gimple_assign_lhs (defstmt);
3040 else if (gimple_call_builtin_p (defstmt, BUILT_IN_MEMSET)
3041 && TREE_CODE (gimple_call_arg (defstmt, 0)) == ADDR_EXPR
3042 && TREE_CODE (gimple_call_arg (defstmt, 1)) == INTEGER_CST)
3043 {
3044 src2 = TREE_OPERAND (gimple_call_arg (defstmt, 0), 0);
3045 len2 = gimple_call_arg (defstmt, 2);
3046 val = gimple_call_arg (defstmt, 1);
3047 /* For non-0 val, we'd have to transform stmt from assignment
3048 into memset (only if dest is addressable). */
3049 if (!integer_zerop (val) && is_gimple_assign (stmt))
3050 src2 = NULL_TREE;
3051 }
3052
3053 if (src2 == NULL_TREE)
3054 return;
3055
3056 if (len == NULL_TREE)
3057 len = (TREE_CODE (src) == COMPONENT_REF
3058 ? DECL_SIZE_UNIT (TREE_OPERAND (src, 1))
3059 : TYPE_SIZE_UNIT (TREE_TYPE (src)));
3060 if (len2 == NULL_TREE)
3061 len2 = (TREE_CODE (src2) == COMPONENT_REF
3062 ? DECL_SIZE_UNIT (TREE_OPERAND (src2, 1))
3063 : TYPE_SIZE_UNIT (TREE_TYPE (src2)));
3064 if (len == NULL_TREE
3065 || !poly_int_tree_p (len)
3066 || len2 == NULL_TREE
3067 || !poly_int_tree_p (len2))
3068 return;
3069
3070 src = get_addr_base_and_unit_offset (src, &offset);
3071 src2 = get_addr_base_and_unit_offset (src2, &offset2);
3072 if (src == NULL_TREE
3073 || src2 == NULL_TREE
3074 || maybe_lt (offset, offset2))
3075 return;
3076
3077 if (!operand_equal_p (src, src2, 0))
3078 return;
3079
3080 /* [ src + offset2, src + offset2 + len2 - 1 ] is set to val.
3081 Make sure that
3082 [ src + offset, src + offset + len - 1 ] is a subset of that. */
3083 if (maybe_gt (wi::to_poly_offset (len) + (offset - offset2),
3084 wi::to_poly_offset (len2)))
3085 return;
3086
3087 if (dump_file && (dump_flags & TDF_DETAILS))
3088 {
3089 fprintf (dump_file, "Simplified\n ");
3090 print_gimple_stmt (dump_file, stmt, 0, dump_flags);
3091 fprintf (dump_file, "after previous\n ");
3092 print_gimple_stmt (dump_file, defstmt, 0, dump_flags);
3093 }
3094
3095 /* For simplicity, don't change the kind of the stmt,
3096 turn dest = src; into dest = {}; and memcpy (&dest, &src, len);
3097 into memset (&dest, val, len);
3098 In theory we could change dest = src into memset if dest
3099 is addressable (maybe beneficial if val is not 0), or
3100 memcpy (&dest, &src, len) into dest = {} if len is the size
3101 of dest, dest isn't volatile. */
3102 if (is_gimple_assign (stmt))
3103 {
3104 tree ctor = build_constructor (TREE_TYPE (dest), NULL);
3105 gimple_assign_set_rhs_from_tree (gsip, ctor);
3106 update_stmt (stmt);
3107 }
3108 else /* If stmt is memcpy, transform it into memset. */
3109 {
3110 gcall *call = as_a <gcall *> (stmt);
3111 tree fndecl = builtin_decl_implicit (BUILT_IN_MEMSET);
3112 gimple_call_set_fndecl (call, fndecl);
3113 gimple_call_set_fntype (call, TREE_TYPE (fndecl));
3114 gimple_call_set_arg (call, 1, val);
3115 update_stmt (stmt);
3116 }
3117
3118 if (dump_file && (dump_flags & TDF_DETAILS))
3119 {
3120 fprintf (dump_file, "into\n ");
3121 print_gimple_stmt (dump_file, stmt, 0, dump_flags);
3122 }
3123 }
3124
3125 /* A simple pass that attempts to fold all builtin functions. This pass
3126 is run after we've propagated as many constants as we can. */
3127
3128 namespace {
3129
3130 const pass_data pass_data_fold_builtins =
3131 {
3132 GIMPLE_PASS, /* type */
3133 "fab", /* name */
3134 OPTGROUP_NONE, /* optinfo_flags */
3135 TV_NONE, /* tv_id */
3136 ( PROP_cfg | PROP_ssa ), /* properties_required */
3137 0, /* properties_provided */
3138 0, /* properties_destroyed */
3139 0, /* todo_flags_start */
3140 TODO_update_ssa, /* todo_flags_finish */
3141 };
3142
3143 class pass_fold_builtins : public gimple_opt_pass
3144 {
3145 public:
pass_fold_builtins(gcc::context * ctxt)3146 pass_fold_builtins (gcc::context *ctxt)
3147 : gimple_opt_pass (pass_data_fold_builtins, ctxt)
3148 {}
3149
3150 /* opt_pass methods: */
clone()3151 opt_pass * clone () { return new pass_fold_builtins (m_ctxt); }
3152 virtual unsigned int execute (function *);
3153
3154 }; // class pass_fold_builtins
3155
3156 unsigned int
execute(function * fun)3157 pass_fold_builtins::execute (function *fun)
3158 {
3159 bool cfg_changed = false;
3160 basic_block bb;
3161 unsigned int todoflags = 0;
3162
3163 FOR_EACH_BB_FN (bb, fun)
3164 {
3165 gimple_stmt_iterator i;
3166 for (i = gsi_start_bb (bb); !gsi_end_p (i); )
3167 {
3168 gimple *stmt, *old_stmt;
3169 tree callee;
3170 enum built_in_function fcode;
3171
3172 stmt = gsi_stmt (i);
3173
3174 if (gimple_code (stmt) != GIMPLE_CALL)
3175 {
3176 /* Remove all *ssaname_N ={v} {CLOBBER}; stmts,
3177 after the last GIMPLE DSE they aren't needed and might
3178 unnecessarily keep the SSA_NAMEs live. */
3179 if (gimple_clobber_p (stmt))
3180 {
3181 tree lhs = gimple_assign_lhs (stmt);
3182 if (TREE_CODE (lhs) == MEM_REF
3183 && TREE_CODE (TREE_OPERAND (lhs, 0)) == SSA_NAME)
3184 {
3185 unlink_stmt_vdef (stmt);
3186 gsi_remove (&i, true);
3187 release_defs (stmt);
3188 continue;
3189 }
3190 }
3191 else if (gimple_assign_load_p (stmt) && gimple_store_p (stmt))
3192 optimize_memcpy (&i, gimple_assign_lhs (stmt),
3193 gimple_assign_rhs1 (stmt), NULL_TREE);
3194 gsi_next (&i);
3195 continue;
3196 }
3197
3198 callee = gimple_call_fndecl (stmt);
3199 if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL)
3200 {
3201 gsi_next (&i);
3202 continue;
3203 }
3204
3205 fcode = DECL_FUNCTION_CODE (callee);
3206 if (fold_stmt (&i))
3207 ;
3208 else
3209 {
3210 tree result = NULL_TREE;
3211 switch (DECL_FUNCTION_CODE (callee))
3212 {
3213 case BUILT_IN_CONSTANT_P:
3214 /* Resolve __builtin_constant_p. If it hasn't been
3215 folded to integer_one_node by now, it's fairly
3216 certain that the value simply isn't constant. */
3217 result = integer_zero_node;
3218 break;
3219
3220 case BUILT_IN_ASSUME_ALIGNED:
3221 /* Remove __builtin_assume_aligned. */
3222 result = gimple_call_arg (stmt, 0);
3223 break;
3224
3225 case BUILT_IN_STACK_RESTORE:
3226 result = optimize_stack_restore (i);
3227 if (result)
3228 break;
3229 gsi_next (&i);
3230 continue;
3231
3232 case BUILT_IN_UNREACHABLE:
3233 if (optimize_unreachable (i))
3234 cfg_changed = true;
3235 break;
3236
3237 case BUILT_IN_ATOMIC_FETCH_OR_1:
3238 case BUILT_IN_ATOMIC_FETCH_OR_2:
3239 case BUILT_IN_ATOMIC_FETCH_OR_4:
3240 case BUILT_IN_ATOMIC_FETCH_OR_8:
3241 case BUILT_IN_ATOMIC_FETCH_OR_16:
3242 optimize_atomic_bit_test_and (&i,
3243 IFN_ATOMIC_BIT_TEST_AND_SET,
3244 true, false);
3245 break;
3246 case BUILT_IN_SYNC_FETCH_AND_OR_1:
3247 case BUILT_IN_SYNC_FETCH_AND_OR_2:
3248 case BUILT_IN_SYNC_FETCH_AND_OR_4:
3249 case BUILT_IN_SYNC_FETCH_AND_OR_8:
3250 case BUILT_IN_SYNC_FETCH_AND_OR_16:
3251 optimize_atomic_bit_test_and (&i,
3252 IFN_ATOMIC_BIT_TEST_AND_SET,
3253 false, false);
3254 break;
3255
3256 case BUILT_IN_ATOMIC_FETCH_XOR_1:
3257 case BUILT_IN_ATOMIC_FETCH_XOR_2:
3258 case BUILT_IN_ATOMIC_FETCH_XOR_4:
3259 case BUILT_IN_ATOMIC_FETCH_XOR_8:
3260 case BUILT_IN_ATOMIC_FETCH_XOR_16:
3261 optimize_atomic_bit_test_and
3262 (&i, IFN_ATOMIC_BIT_TEST_AND_COMPLEMENT, true, false);
3263 break;
3264 case BUILT_IN_SYNC_FETCH_AND_XOR_1:
3265 case BUILT_IN_SYNC_FETCH_AND_XOR_2:
3266 case BUILT_IN_SYNC_FETCH_AND_XOR_4:
3267 case BUILT_IN_SYNC_FETCH_AND_XOR_8:
3268 case BUILT_IN_SYNC_FETCH_AND_XOR_16:
3269 optimize_atomic_bit_test_and
3270 (&i, IFN_ATOMIC_BIT_TEST_AND_COMPLEMENT, false, false);
3271 break;
3272
3273 case BUILT_IN_ATOMIC_XOR_FETCH_1:
3274 case BUILT_IN_ATOMIC_XOR_FETCH_2:
3275 case BUILT_IN_ATOMIC_XOR_FETCH_4:
3276 case BUILT_IN_ATOMIC_XOR_FETCH_8:
3277 case BUILT_IN_ATOMIC_XOR_FETCH_16:
3278 optimize_atomic_bit_test_and
3279 (&i, IFN_ATOMIC_BIT_TEST_AND_COMPLEMENT, true, true);
3280 break;
3281 case BUILT_IN_SYNC_XOR_AND_FETCH_1:
3282 case BUILT_IN_SYNC_XOR_AND_FETCH_2:
3283 case BUILT_IN_SYNC_XOR_AND_FETCH_4:
3284 case BUILT_IN_SYNC_XOR_AND_FETCH_8:
3285 case BUILT_IN_SYNC_XOR_AND_FETCH_16:
3286 optimize_atomic_bit_test_and
3287 (&i, IFN_ATOMIC_BIT_TEST_AND_COMPLEMENT, false, true);
3288 break;
3289
3290 case BUILT_IN_ATOMIC_FETCH_AND_1:
3291 case BUILT_IN_ATOMIC_FETCH_AND_2:
3292 case BUILT_IN_ATOMIC_FETCH_AND_4:
3293 case BUILT_IN_ATOMIC_FETCH_AND_8:
3294 case BUILT_IN_ATOMIC_FETCH_AND_16:
3295 optimize_atomic_bit_test_and (&i,
3296 IFN_ATOMIC_BIT_TEST_AND_RESET,
3297 true, false);
3298 break;
3299 case BUILT_IN_SYNC_FETCH_AND_AND_1:
3300 case BUILT_IN_SYNC_FETCH_AND_AND_2:
3301 case BUILT_IN_SYNC_FETCH_AND_AND_4:
3302 case BUILT_IN_SYNC_FETCH_AND_AND_8:
3303 case BUILT_IN_SYNC_FETCH_AND_AND_16:
3304 optimize_atomic_bit_test_and (&i,
3305 IFN_ATOMIC_BIT_TEST_AND_RESET,
3306 false, false);
3307 break;
3308
3309 case BUILT_IN_MEMCPY:
3310 if (gimple_call_builtin_p (stmt, BUILT_IN_NORMAL)
3311 && TREE_CODE (gimple_call_arg (stmt, 0)) == ADDR_EXPR
3312 && TREE_CODE (gimple_call_arg (stmt, 1)) == ADDR_EXPR
3313 && TREE_CODE (gimple_call_arg (stmt, 2)) == INTEGER_CST)
3314 {
3315 tree dest = TREE_OPERAND (gimple_call_arg (stmt, 0), 0);
3316 tree src = TREE_OPERAND (gimple_call_arg (stmt, 1), 0);
3317 tree len = gimple_call_arg (stmt, 2);
3318 optimize_memcpy (&i, dest, src, len);
3319 }
3320 break;
3321
3322 case BUILT_IN_VA_START:
3323 case BUILT_IN_VA_END:
3324 case BUILT_IN_VA_COPY:
3325 /* These shouldn't be folded before pass_stdarg. */
3326 result = optimize_stdarg_builtin (stmt);
3327 break;
3328
3329 default:;
3330 }
3331
3332 if (!result)
3333 {
3334 gsi_next (&i);
3335 continue;
3336 }
3337
3338 if (!update_call_from_tree (&i, result))
3339 gimplify_and_update_call_from_tree (&i, result);
3340 }
3341
3342 todoflags |= TODO_update_address_taken;
3343
3344 if (dump_file && (dump_flags & TDF_DETAILS))
3345 {
3346 fprintf (dump_file, "Simplified\n ");
3347 print_gimple_stmt (dump_file, stmt, 0, dump_flags);
3348 }
3349
3350 old_stmt = stmt;
3351 stmt = gsi_stmt (i);
3352 update_stmt (stmt);
3353
3354 if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt)
3355 && gimple_purge_dead_eh_edges (bb))
3356 cfg_changed = true;
3357
3358 if (dump_file && (dump_flags & TDF_DETAILS))
3359 {
3360 fprintf (dump_file, "to\n ");
3361 print_gimple_stmt (dump_file, stmt, 0, dump_flags);
3362 fprintf (dump_file, "\n");
3363 }
3364
3365 /* Retry the same statement if it changed into another
3366 builtin, there might be new opportunities now. */
3367 if (gimple_code (stmt) != GIMPLE_CALL)
3368 {
3369 gsi_next (&i);
3370 continue;
3371 }
3372 callee = gimple_call_fndecl (stmt);
3373 if (!callee
3374 || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL
3375 || DECL_FUNCTION_CODE (callee) == fcode)
3376 gsi_next (&i);
3377 }
3378 }
3379
3380 /* Delete unreachable blocks. */
3381 if (cfg_changed)
3382 todoflags |= TODO_cleanup_cfg;
3383
3384 return todoflags;
3385 }
3386
3387 } // anon namespace
3388
3389 gimple_opt_pass *
make_pass_fold_builtins(gcc::context * ctxt)3390 make_pass_fold_builtins (gcc::context *ctxt)
3391 {
3392 return new pass_fold_builtins (ctxt);
3393 }
3394
3395 /* A simple pass that emits some warnings post IPA. */
3396
3397 namespace {
3398
3399 const pass_data pass_data_post_ipa_warn =
3400 {
3401 GIMPLE_PASS, /* type */
3402 "post_ipa_warn", /* name */
3403 OPTGROUP_NONE, /* optinfo_flags */
3404 TV_NONE, /* tv_id */
3405 ( PROP_cfg | PROP_ssa ), /* properties_required */
3406 0, /* properties_provided */
3407 0, /* properties_destroyed */
3408 0, /* todo_flags_start */
3409 0, /* todo_flags_finish */
3410 };
3411
3412 class pass_post_ipa_warn : public gimple_opt_pass
3413 {
3414 public:
pass_post_ipa_warn(gcc::context * ctxt)3415 pass_post_ipa_warn (gcc::context *ctxt)
3416 : gimple_opt_pass (pass_data_post_ipa_warn, ctxt)
3417 {}
3418
3419 /* opt_pass methods: */
clone()3420 opt_pass * clone () { return new pass_post_ipa_warn (m_ctxt); }
gate(function *)3421 virtual bool gate (function *) { return warn_nonnull != 0; }
3422 virtual unsigned int execute (function *);
3423
3424 }; // class pass_fold_builtins
3425
3426 unsigned int
execute(function * fun)3427 pass_post_ipa_warn::execute (function *fun)
3428 {
3429 basic_block bb;
3430
3431 FOR_EACH_BB_FN (bb, fun)
3432 {
3433 gimple_stmt_iterator gsi;
3434 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
3435 {
3436 gimple *stmt = gsi_stmt (gsi);
3437 if (!is_gimple_call (stmt) || gimple_no_warning_p (stmt))
3438 continue;
3439
3440 if (warn_nonnull)
3441 {
3442 bitmap nonnullargs
3443 = get_nonnull_args (gimple_call_fntype (stmt));
3444 if (nonnullargs)
3445 {
3446 for (unsigned i = 0; i < gimple_call_num_args (stmt); i++)
3447 {
3448 tree arg = gimple_call_arg (stmt, i);
3449 if (TREE_CODE (TREE_TYPE (arg)) != POINTER_TYPE)
3450 continue;
3451 if (!integer_zerop (arg))
3452 continue;
3453 if (!bitmap_empty_p (nonnullargs)
3454 && !bitmap_bit_p (nonnullargs, i))
3455 continue;
3456
3457 location_t loc = gimple_location (stmt);
3458 if (warning_at (loc, OPT_Wnonnull,
3459 "%Gargument %u null where non-null "
3460 "expected", as_a <gcall *>(stmt), i + 1))
3461 {
3462 tree fndecl = gimple_call_fndecl (stmt);
3463 if (fndecl && DECL_IS_BUILTIN (fndecl))
3464 inform (loc, "in a call to built-in function %qD",
3465 fndecl);
3466 else if (fndecl)
3467 inform (DECL_SOURCE_LOCATION (fndecl),
3468 "in a call to function %qD declared here",
3469 fndecl);
3470
3471 }
3472 }
3473 BITMAP_FREE (nonnullargs);
3474 }
3475 }
3476 }
3477 }
3478 return 0;
3479 }
3480
3481 } // anon namespace
3482
3483 gimple_opt_pass *
make_pass_post_ipa_warn(gcc::context * ctxt)3484 make_pass_post_ipa_warn (gcc::context *ctxt)
3485 {
3486 return new pass_post_ipa_warn (ctxt);
3487 }
3488