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