1 /* Chains of recurrences.
2 Copyright (C) 2003-2016 Free Software Foundation, Inc.
3 Contributed by Sebastian Pop <pop@cri.ensmp.fr>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 3, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
21 /* This file implements operations on chains of recurrences. Chains
22 of recurrences are used for modeling evolution functions of scalar
28 #include "coretypes.h"
31 #include "gimple-expr.h"
32 #include "tree-pretty-print.h"
33 #include "fold-const.h"
35 #include "tree-ssa-loop-ivopts.h"
36 #include "tree-ssa-loop-niter.h"
37 #include "tree-chrec.h"
40 #include "tree-scalar-evolution.h"
42 /* Extended folder for chrecs. */
44 /* Determines whether CST is not a constant evolution. */
47 is_not_constant_evolution (const_tree cst)
49 return (TREE_CODE (cst) == POLYNOMIAL_CHREC);
52 /* Fold CODE for a polynomial function and a constant. */
55 chrec_fold_poly_cst (enum tree_code code,
62 gcc_assert (TREE_CODE (poly) == POLYNOMIAL_CHREC);
63 gcc_checking_assert (!is_not_constant_evolution (cst));
64 gcc_checking_assert (useless_type_conversion_p (type, chrec_type (poly)));
69 return build_polynomial_chrec
70 (CHREC_VARIABLE (poly),
71 chrec_fold_plus (type, CHREC_LEFT (poly), cst),
75 return build_polynomial_chrec
76 (CHREC_VARIABLE (poly),
77 chrec_fold_minus (type, CHREC_LEFT (poly), cst),
81 return build_polynomial_chrec
82 (CHREC_VARIABLE (poly),
83 chrec_fold_multiply (type, CHREC_LEFT (poly), cst),
84 chrec_fold_multiply (type, CHREC_RIGHT (poly), cst));
87 return chrec_dont_know;
91 /* Fold the addition of two polynomial functions. */
94 chrec_fold_plus_poly_poly (enum tree_code code,
100 struct loop *loop0 = get_chrec_loop (poly0);
101 struct loop *loop1 = get_chrec_loop (poly1);
102 tree rtype = code == POINTER_PLUS_EXPR ? chrec_type (poly1) : type;
106 gcc_assert (TREE_CODE (poly0) == POLYNOMIAL_CHREC);
107 gcc_assert (TREE_CODE (poly1) == POLYNOMIAL_CHREC);
108 if (POINTER_TYPE_P (chrec_type (poly0)))
109 gcc_checking_assert (ptrofftype_p (chrec_type (poly1))
110 && useless_type_conversion_p (type, chrec_type (poly0)));
112 gcc_checking_assert (useless_type_conversion_p (type, chrec_type (poly0))
113 && useless_type_conversion_p (type, chrec_type (poly1)));
116 {a, +, b}_1 + {c, +, d}_2 -> {{a, +, b}_1 + c, +, d}_2,
117 {a, +, b}_2 + {c, +, d}_1 -> {{c, +, d}_1 + a, +, b}_2,
118 {a, +, b}_x + {c, +, d}_x -> {a+c, +, b+d}_x. */
119 if (flow_loop_nested_p (loop0, loop1))
121 if (code == PLUS_EXPR || code == POINTER_PLUS_EXPR)
122 return build_polynomial_chrec
123 (CHREC_VARIABLE (poly1),
124 chrec_fold_plus (type, poly0, CHREC_LEFT (poly1)),
125 CHREC_RIGHT (poly1));
127 return build_polynomial_chrec
128 (CHREC_VARIABLE (poly1),
129 chrec_fold_minus (type, poly0, CHREC_LEFT (poly1)),
130 chrec_fold_multiply (type, CHREC_RIGHT (poly1),
131 SCALAR_FLOAT_TYPE_P (type)
132 ? build_real (type, dconstm1)
133 : build_int_cst_type (type, -1)));
136 if (flow_loop_nested_p (loop1, loop0))
138 if (code == PLUS_EXPR || code == POINTER_PLUS_EXPR)
139 return build_polynomial_chrec
140 (CHREC_VARIABLE (poly0),
141 chrec_fold_plus (type, CHREC_LEFT (poly0), poly1),
142 CHREC_RIGHT (poly0));
144 return build_polynomial_chrec
145 (CHREC_VARIABLE (poly0),
146 chrec_fold_minus (type, CHREC_LEFT (poly0), poly1),
147 CHREC_RIGHT (poly0));
150 /* This function should never be called for chrecs of loops that
151 do not belong to the same loop nest. */
152 gcc_assert (loop0 == loop1);
154 if (code == PLUS_EXPR || code == POINTER_PLUS_EXPR)
156 left = chrec_fold_plus
157 (type, CHREC_LEFT (poly0), CHREC_LEFT (poly1));
158 right = chrec_fold_plus
159 (rtype, CHREC_RIGHT (poly0), CHREC_RIGHT (poly1));
163 left = chrec_fold_minus
164 (type, CHREC_LEFT (poly0), CHREC_LEFT (poly1));
165 right = chrec_fold_minus
166 (type, CHREC_RIGHT (poly0), CHREC_RIGHT (poly1));
169 if (chrec_zerop (right))
172 return build_polynomial_chrec
173 (CHREC_VARIABLE (poly0), left, right);
178 /* Fold the multiplication of two polynomial functions. */
181 chrec_fold_multiply_poly_poly (tree type,
187 struct loop *loop0 = get_chrec_loop (poly0);
188 struct loop *loop1 = get_chrec_loop (poly1);
192 gcc_assert (TREE_CODE (poly0) == POLYNOMIAL_CHREC);
193 gcc_assert (TREE_CODE (poly1) == POLYNOMIAL_CHREC);
194 gcc_checking_assert (useless_type_conversion_p (type, chrec_type (poly0))
195 && useless_type_conversion_p (type, chrec_type (poly1)));
197 /* {a, +, b}_1 * {c, +, d}_2 -> {c*{a, +, b}_1, +, d}_2,
198 {a, +, b}_2 * {c, +, d}_1 -> {a*{c, +, d}_1, +, b}_2,
199 {a, +, b}_x * {c, +, d}_x -> {a*c, +, a*d + b*c + b*d, +, 2*b*d}_x. */
200 if (flow_loop_nested_p (loop0, loop1))
201 /* poly0 is a constant wrt. poly1. */
202 return build_polynomial_chrec
203 (CHREC_VARIABLE (poly1),
204 chrec_fold_multiply (type, CHREC_LEFT (poly1), poly0),
205 CHREC_RIGHT (poly1));
207 if (flow_loop_nested_p (loop1, loop0))
208 /* poly1 is a constant wrt. poly0. */
209 return build_polynomial_chrec
210 (CHREC_VARIABLE (poly0),
211 chrec_fold_multiply (type, CHREC_LEFT (poly0), poly1),
212 CHREC_RIGHT (poly0));
214 gcc_assert (loop0 == loop1);
216 /* poly0 and poly1 are two polynomials in the same variable,
217 {a, +, b}_x * {c, +, d}_x -> {a*c, +, a*d + b*c + b*d, +, 2*b*d}_x. */
220 t0 = chrec_fold_multiply (type, CHREC_LEFT (poly0), CHREC_LEFT (poly1));
223 t1 = chrec_fold_multiply (type, CHREC_LEFT (poly0), CHREC_RIGHT (poly1));
224 t1 = chrec_fold_plus (type, t1, chrec_fold_multiply (type,
226 CHREC_LEFT (poly1)));
228 t2 = chrec_fold_multiply (type, CHREC_RIGHT (poly0), CHREC_RIGHT (poly1));
229 /* "a*d + b*c + b*d". */
230 t1 = chrec_fold_plus (type, t1, t2);
232 t2 = chrec_fold_multiply (type, SCALAR_FLOAT_TYPE_P (type)
233 ? build_real (type, dconst2)
234 : build_int_cst (type, 2), t2);
236 var = CHREC_VARIABLE (poly0);
237 return build_polynomial_chrec (var, t0,
238 build_polynomial_chrec (var, t1, t2));
241 /* When the operands are automatically_generated_chrec_p, the fold has
242 to respect the semantics of the operands. */
245 chrec_fold_automatically_generated_operands (tree op0,
248 if (op0 == chrec_dont_know
249 || op1 == chrec_dont_know)
250 return chrec_dont_know;
252 if (op0 == chrec_known
253 || op1 == chrec_known)
256 if (op0 == chrec_not_analyzed_yet
257 || op1 == chrec_not_analyzed_yet)
258 return chrec_not_analyzed_yet;
260 /* The default case produces a safe result. */
261 return chrec_dont_know;
264 /* Fold the addition of two chrecs. */
267 chrec_fold_plus_1 (enum tree_code code, tree type,
270 if (automatically_generated_chrec_p (op0)
271 || automatically_generated_chrec_p (op1))
272 return chrec_fold_automatically_generated_operands (op0, op1);
274 switch (TREE_CODE (op0))
276 case POLYNOMIAL_CHREC:
278 (!chrec_contains_symbols_defined_in_loop (op0, CHREC_VARIABLE (op0)));
279 switch (TREE_CODE (op1))
281 case POLYNOMIAL_CHREC:
283 (!chrec_contains_symbols_defined_in_loop (op1,
284 CHREC_VARIABLE (op1)));
285 return chrec_fold_plus_poly_poly (code, type, op0, op1);
288 if (tree_contains_chrecs (op1, NULL))
289 return chrec_dont_know;
293 if (code == PLUS_EXPR || code == POINTER_PLUS_EXPR)
294 return build_polynomial_chrec
295 (CHREC_VARIABLE (op0),
296 chrec_fold_plus (type, CHREC_LEFT (op0), op1),
299 return build_polynomial_chrec
300 (CHREC_VARIABLE (op0),
301 chrec_fold_minus (type, CHREC_LEFT (op0), op1),
306 if (tree_contains_chrecs (op0, NULL))
307 return chrec_dont_know;
311 switch (TREE_CODE (op1))
313 case POLYNOMIAL_CHREC:
315 (!chrec_contains_symbols_defined_in_loop (op1,
316 CHREC_VARIABLE (op1)));
317 if (code == PLUS_EXPR || code == POINTER_PLUS_EXPR)
318 return build_polynomial_chrec
319 (CHREC_VARIABLE (op1),
320 chrec_fold_plus (type, op0, CHREC_LEFT (op1)),
323 return build_polynomial_chrec
324 (CHREC_VARIABLE (op1),
325 chrec_fold_minus (type, op0, CHREC_LEFT (op1)),
326 chrec_fold_multiply (type, CHREC_RIGHT (op1),
327 SCALAR_FLOAT_TYPE_P (type)
328 ? build_real (type, dconstm1)
329 : build_int_cst_type (type, -1)));
332 if (tree_contains_chrecs (op1, NULL))
333 return chrec_dont_know;
339 if ((tree_contains_chrecs (op0, &size)
340 || tree_contains_chrecs (op1, &size))
341 && size < PARAM_VALUE (PARAM_SCEV_MAX_EXPR_SIZE))
342 return build2 (code, type, op0, op1);
343 else if (size < PARAM_VALUE (PARAM_SCEV_MAX_EXPR_SIZE))
345 if (code == POINTER_PLUS_EXPR)
346 return fold_build_pointer_plus (fold_convert (type, op0),
349 return fold_build2 (code, type,
350 fold_convert (type, op0),
351 fold_convert (type, op1));
354 return chrec_dont_know;
360 /* Fold the addition of two chrecs. */
363 chrec_fold_plus (tree type,
368 if (automatically_generated_chrec_p (op0)
369 || automatically_generated_chrec_p (op1))
370 return chrec_fold_automatically_generated_operands (op0, op1);
372 if (integer_zerop (op0))
373 return chrec_convert (type, op1, NULL);
374 if (integer_zerop (op1))
375 return chrec_convert (type, op0, NULL);
377 if (POINTER_TYPE_P (type))
378 code = POINTER_PLUS_EXPR;
382 return chrec_fold_plus_1 (code, type, op0, op1);
385 /* Fold the subtraction of two chrecs. */
388 chrec_fold_minus (tree type,
392 if (automatically_generated_chrec_p (op0)
393 || automatically_generated_chrec_p (op1))
394 return chrec_fold_automatically_generated_operands (op0, op1);
396 if (integer_zerop (op1))
399 return chrec_fold_plus_1 (MINUS_EXPR, type, op0, op1);
402 /* Fold the multiplication of two chrecs. */
405 chrec_fold_multiply (tree type,
409 if (automatically_generated_chrec_p (op0)
410 || automatically_generated_chrec_p (op1))
411 return chrec_fold_automatically_generated_operands (op0, op1);
413 switch (TREE_CODE (op0))
415 case POLYNOMIAL_CHREC:
417 (!chrec_contains_symbols_defined_in_loop (op0, CHREC_VARIABLE (op0)));
418 switch (TREE_CODE (op1))
420 case POLYNOMIAL_CHREC:
422 (!chrec_contains_symbols_defined_in_loop (op1,
423 CHREC_VARIABLE (op1)));
424 return chrec_fold_multiply_poly_poly (type, op0, op1);
427 if (tree_contains_chrecs (op1, NULL))
428 return chrec_dont_know;
432 if (integer_onep (op1))
434 if (integer_zerop (op1))
435 return build_int_cst (type, 0);
437 return build_polynomial_chrec
438 (CHREC_VARIABLE (op0),
439 chrec_fold_multiply (type, CHREC_LEFT (op0), op1),
440 chrec_fold_multiply (type, CHREC_RIGHT (op0), op1));
444 if (tree_contains_chrecs (op0, NULL))
445 return chrec_dont_know;
449 if (integer_onep (op0))
452 if (integer_zerop (op0))
453 return build_int_cst (type, 0);
455 switch (TREE_CODE (op1))
457 case POLYNOMIAL_CHREC:
459 (!chrec_contains_symbols_defined_in_loop (op1,
460 CHREC_VARIABLE (op1)));
461 return build_polynomial_chrec
462 (CHREC_VARIABLE (op1),
463 chrec_fold_multiply (type, CHREC_LEFT (op1), op0),
464 chrec_fold_multiply (type, CHREC_RIGHT (op1), op0));
467 if (tree_contains_chrecs (op1, NULL))
468 return chrec_dont_know;
472 if (integer_onep (op1))
474 if (integer_zerop (op1))
475 return build_int_cst (type, 0);
476 return fold_build2 (MULT_EXPR, type, op0, op1);
485 /* Evaluate the binomial coefficient. Return NULL_TREE if the intermediate
486 calculation overflows, otherwise return C(n,k) with type TYPE. */
489 tree_fold_binomial (tree type, tree n, unsigned int k)
494 /* Handle the most frequent cases. */
496 return build_int_cst (type, 1);
498 return fold_convert (type, n);
500 widest_int num = wi::to_widest (n);
502 /* Check that k <= n. */
503 if (wi::ltu_p (num, k))
506 /* Denominator = 2. */
507 widest_int denom = 2;
509 /* Index = Numerator-1. */
510 widest_int idx = num - 1;
512 /* Numerator = Numerator*Index = n*(n-1). */
513 num = wi::smul (num, idx, &overflow);
517 for (i = 3; i <= k; i++)
522 /* Numerator *= Index. */
523 num = wi::smul (num, idx, &overflow);
527 /* Denominator *= i. */
531 /* Result = Numerator / Denominator. */
532 num = wi::udiv_trunc (num, denom);
533 if (! wi::fits_to_tree_p (num, type))
535 return wide_int_to_tree (type, num);
538 /* Helper function. Use the Newton's interpolating formula for
539 evaluating the value of the evolution function. */
542 chrec_evaluate (unsigned var, tree chrec, tree n, unsigned int k)
544 tree arg0, arg1, binomial_n_k;
545 tree type = TREE_TYPE (chrec);
546 struct loop *var_loop = get_loop (cfun, var);
548 while (TREE_CODE (chrec) == POLYNOMIAL_CHREC
549 && flow_loop_nested_p (var_loop, get_chrec_loop (chrec)))
550 chrec = CHREC_LEFT (chrec);
552 if (TREE_CODE (chrec) == POLYNOMIAL_CHREC
553 && CHREC_VARIABLE (chrec) == var)
555 arg1 = chrec_evaluate (var, CHREC_RIGHT (chrec), n, k + 1);
556 if (arg1 == chrec_dont_know)
557 return chrec_dont_know;
558 binomial_n_k = tree_fold_binomial (type, n, k);
560 return chrec_dont_know;
561 arg0 = fold_build2 (MULT_EXPR, type,
562 CHREC_LEFT (chrec), binomial_n_k);
563 return chrec_fold_plus (type, arg0, arg1);
566 binomial_n_k = tree_fold_binomial (type, n, k);
568 return chrec_dont_know;
570 return fold_build2 (MULT_EXPR, type, chrec, binomial_n_k);
573 /* Evaluates "CHREC (X)" when the varying variable is VAR.
574 Example: Given the following parameters,
580 The result is given by the Newton's interpolating formula:
581 3 * \binom{10}{0} + 4 * \binom{10}{1}.
585 chrec_apply (unsigned var,
589 tree type = chrec_type (chrec);
590 tree res = chrec_dont_know;
592 if (automatically_generated_chrec_p (chrec)
593 || automatically_generated_chrec_p (x)
595 /* When the symbols are defined in an outer loop, it is possible
596 to symbolically compute the apply, since the symbols are
597 constants with respect to the varying loop. */
598 || chrec_contains_symbols_defined_in_loop (chrec, var))
599 return chrec_dont_know;
601 if (dump_file && (dump_flags & TDF_SCEV))
602 fprintf (dump_file, "(chrec_apply \n");
604 if (TREE_CODE (x) == INTEGER_CST && SCALAR_FLOAT_TYPE_P (type))
605 x = build_real_from_int_cst (type, x);
607 switch (TREE_CODE (chrec))
609 case POLYNOMIAL_CHREC:
610 if (evolution_function_is_affine_p (chrec))
612 if (CHREC_VARIABLE (chrec) != var)
613 return build_polynomial_chrec
614 (CHREC_VARIABLE (chrec),
615 chrec_apply (var, CHREC_LEFT (chrec), x),
616 chrec_apply (var, CHREC_RIGHT (chrec), x));
618 /* "{a, +, b} (x)" -> "a + b*x". */
619 x = chrec_convert_rhs (type, x, NULL);
620 res = chrec_fold_multiply (TREE_TYPE (x), CHREC_RIGHT (chrec), x);
621 res = chrec_fold_plus (type, CHREC_LEFT (chrec), res);
623 else if (TREE_CODE (x) == INTEGER_CST
624 && tree_int_cst_sgn (x) == 1)
625 /* testsuite/.../ssa-chrec-38.c. */
626 res = chrec_evaluate (var, chrec, x, 0);
628 res = chrec_dont_know;
632 res = chrec_convert (TREE_TYPE (chrec),
633 chrec_apply (var, TREE_OPERAND (chrec, 0), x),
642 if (dump_file && (dump_flags & TDF_SCEV))
644 fprintf (dump_file, " (varying_loop = %d\n", var);
645 fprintf (dump_file, ")\n (chrec = ");
646 print_generic_expr (dump_file, chrec, 0);
647 fprintf (dump_file, ")\n (x = ");
648 print_generic_expr (dump_file, x, 0);
649 fprintf (dump_file, ")\n (res = ");
650 print_generic_expr (dump_file, res, 0);
651 fprintf (dump_file, "))\n");
657 /* For a given CHREC and an induction variable map IV_MAP that maps
658 (loop->num, expr) for every loop number of the current_loops an
659 expression, calls chrec_apply when the expression is not NULL. */
662 chrec_apply_map (tree chrec, vec<tree> iv_map)
667 FOR_EACH_VEC_ELT (iv_map, i, expr)
669 chrec = chrec_apply (i, chrec, expr);
674 /* Replaces the initial condition in CHREC with INIT_COND. */
677 chrec_replace_initial_condition (tree chrec,
680 if (automatically_generated_chrec_p (chrec))
683 gcc_assert (chrec_type (chrec) == chrec_type (init_cond));
685 switch (TREE_CODE (chrec))
687 case POLYNOMIAL_CHREC:
688 return build_polynomial_chrec
689 (CHREC_VARIABLE (chrec),
690 chrec_replace_initial_condition (CHREC_LEFT (chrec), init_cond),
691 CHREC_RIGHT (chrec));
698 /* Returns the initial condition of a given CHREC. */
701 initial_condition (tree chrec)
703 if (automatically_generated_chrec_p (chrec))
706 if (TREE_CODE (chrec) == POLYNOMIAL_CHREC)
707 return initial_condition (CHREC_LEFT (chrec));
712 /* Returns a univariate function that represents the evolution in
713 LOOP_NUM. Mask the evolution of any other loop. */
716 hide_evolution_in_other_loops_than_loop (tree chrec,
719 struct loop *loop = get_loop (cfun, loop_num), *chloop;
720 if (automatically_generated_chrec_p (chrec))
723 switch (TREE_CODE (chrec))
725 case POLYNOMIAL_CHREC:
726 chloop = get_chrec_loop (chrec);
729 return build_polynomial_chrec
731 hide_evolution_in_other_loops_than_loop (CHREC_LEFT (chrec),
733 CHREC_RIGHT (chrec));
735 else if (flow_loop_nested_p (chloop, loop))
736 /* There is no evolution in this loop. */
737 return initial_condition (chrec);
739 else if (flow_loop_nested_p (loop, chloop))
740 return hide_evolution_in_other_loops_than_loop (CHREC_LEFT (chrec),
744 return chrec_dont_know;
751 /* Returns the evolution part of CHREC in LOOP_NUM when RIGHT is
752 true, otherwise returns the initial condition in LOOP_NUM. */
755 chrec_component_in_loop_num (tree chrec,
760 struct loop *loop = get_loop (cfun, loop_num), *chloop;
762 if (automatically_generated_chrec_p (chrec))
765 switch (TREE_CODE (chrec))
767 case POLYNOMIAL_CHREC:
768 chloop = get_chrec_loop (chrec);
773 component = CHREC_RIGHT (chrec);
775 component = CHREC_LEFT (chrec);
777 if (TREE_CODE (CHREC_LEFT (chrec)) != POLYNOMIAL_CHREC
778 || CHREC_VARIABLE (CHREC_LEFT (chrec)) != CHREC_VARIABLE (chrec))
782 return build_polynomial_chrec
784 chrec_component_in_loop_num (CHREC_LEFT (chrec),
790 else if (flow_loop_nested_p (chloop, loop))
791 /* There is no evolution part in this loop. */
796 gcc_assert (flow_loop_nested_p (loop, chloop));
797 return chrec_component_in_loop_num (CHREC_LEFT (chrec),
810 /* Returns the evolution part in LOOP_NUM. Example: the call
811 evolution_part_in_loop_num ({{0, +, 1}_1, +, 2}_1, 1) returns
815 evolution_part_in_loop_num (tree chrec,
818 return chrec_component_in_loop_num (chrec, loop_num, true);
821 /* Returns the initial condition in LOOP_NUM. Example: the call
822 initial_condition_in_loop_num ({{0, +, 1}_1, +, 2}_2, 2) returns
826 initial_condition_in_loop_num (tree chrec,
829 return chrec_component_in_loop_num (chrec, loop_num, false);
832 /* Set or reset the evolution of CHREC to NEW_EVOL in loop LOOP_NUM.
833 This function is essentially used for setting the evolution to
834 chrec_dont_know, for example after having determined that it is
835 impossible to say how many times a loop will execute. */
838 reset_evolution_in_loop (unsigned loop_num,
842 struct loop *loop = get_loop (cfun, loop_num);
844 if (POINTER_TYPE_P (chrec_type (chrec)))
845 gcc_assert (ptrofftype_p (chrec_type (new_evol)));
847 gcc_assert (chrec_type (chrec) == chrec_type (new_evol));
849 if (TREE_CODE (chrec) == POLYNOMIAL_CHREC
850 && flow_loop_nested_p (loop, get_chrec_loop (chrec)))
852 tree left = reset_evolution_in_loop (loop_num, CHREC_LEFT (chrec),
854 tree right = reset_evolution_in_loop (loop_num, CHREC_RIGHT (chrec),
856 return build3 (POLYNOMIAL_CHREC, TREE_TYPE (left),
857 CHREC_VAR (chrec), left, right);
860 while (TREE_CODE (chrec) == POLYNOMIAL_CHREC
861 && CHREC_VARIABLE (chrec) == loop_num)
862 chrec = CHREC_LEFT (chrec);
864 return build_polynomial_chrec (loop_num, chrec, new_evol);
867 /* Merges two evolution functions that were found by following two
868 alternate paths of a conditional expression. */
871 chrec_merge (tree chrec1,
874 if (chrec1 == chrec_dont_know
875 || chrec2 == chrec_dont_know)
876 return chrec_dont_know;
878 if (chrec1 == chrec_known
879 || chrec2 == chrec_known)
882 if (chrec1 == chrec_not_analyzed_yet)
884 if (chrec2 == chrec_not_analyzed_yet)
887 if (eq_evolutions_p (chrec1, chrec2))
890 return chrec_dont_know;
897 /* Helper function for is_multivariate_chrec. */
900 is_multivariate_chrec_rec (const_tree chrec, unsigned int rec_var)
902 if (chrec == NULL_TREE)
905 if (TREE_CODE (chrec) == POLYNOMIAL_CHREC)
907 if (CHREC_VARIABLE (chrec) != rec_var)
910 return (is_multivariate_chrec_rec (CHREC_LEFT (chrec), rec_var)
911 || is_multivariate_chrec_rec (CHREC_RIGHT (chrec), rec_var));
917 /* Determine whether the given chrec is multivariate or not. */
920 is_multivariate_chrec (const_tree chrec)
922 if (chrec == NULL_TREE)
925 if (TREE_CODE (chrec) == POLYNOMIAL_CHREC)
926 return (is_multivariate_chrec_rec (CHREC_LEFT (chrec),
927 CHREC_VARIABLE (chrec))
928 || is_multivariate_chrec_rec (CHREC_RIGHT (chrec),
929 CHREC_VARIABLE (chrec)));
934 /* Determines whether the chrec contains symbolic names or not. */
937 chrec_contains_symbols (const_tree chrec)
941 if (chrec == NULL_TREE)
944 if (TREE_CODE (chrec) == SSA_NAME
945 || TREE_CODE (chrec) == VAR_DECL
946 || TREE_CODE (chrec) == PARM_DECL
947 || TREE_CODE (chrec) == FUNCTION_DECL
948 || TREE_CODE (chrec) == LABEL_DECL
949 || TREE_CODE (chrec) == RESULT_DECL
950 || TREE_CODE (chrec) == FIELD_DECL)
953 n = TREE_OPERAND_LENGTH (chrec);
954 for (i = 0; i < n; i++)
955 if (chrec_contains_symbols (TREE_OPERAND (chrec, i)))
960 /* Determines whether the chrec contains undetermined coefficients. */
963 chrec_contains_undetermined (const_tree chrec)
967 if (chrec == chrec_dont_know)
970 if (chrec == NULL_TREE)
973 n = TREE_OPERAND_LENGTH (chrec);
974 for (i = 0; i < n; i++)
975 if (chrec_contains_undetermined (TREE_OPERAND (chrec, i)))
980 /* Determines whether the tree EXPR contains chrecs, and increment
981 SIZE if it is not a NULL pointer by an estimation of the depth of
985 tree_contains_chrecs (const_tree expr, int *size)
989 if (expr == NULL_TREE)
995 if (tree_is_chrec (expr))
998 n = TREE_OPERAND_LENGTH (expr);
999 for (i = 0; i < n; i++)
1000 if (tree_contains_chrecs (TREE_OPERAND (expr, i), size))
1005 /* Recursive helper function. */
1008 evolution_function_is_invariant_rec_p (tree chrec, int loopnum)
1010 if (evolution_function_is_constant_p (chrec))
1013 if (TREE_CODE (chrec) == SSA_NAME
1015 || expr_invariant_in_loop_p (get_loop (cfun, loopnum), chrec)))
1018 if (TREE_CODE (chrec) == POLYNOMIAL_CHREC)
1020 if (CHREC_VARIABLE (chrec) == (unsigned) loopnum
1021 || flow_loop_nested_p (get_loop (cfun, loopnum),
1022 get_chrec_loop (chrec))
1023 || !evolution_function_is_invariant_rec_p (CHREC_RIGHT (chrec),
1025 || !evolution_function_is_invariant_rec_p (CHREC_LEFT (chrec),
1031 switch (TREE_OPERAND_LENGTH (chrec))
1034 if (!evolution_function_is_invariant_rec_p (TREE_OPERAND (chrec, 1),
1040 if (!evolution_function_is_invariant_rec_p (TREE_OPERAND (chrec, 0),
1052 /* Return true if CHREC is invariant in loop LOOPNUM, false otherwise. */
1055 evolution_function_is_invariant_p (tree chrec, int loopnum)
1057 return evolution_function_is_invariant_rec_p (chrec, loopnum);
1060 /* Determine whether the given tree is an affine multivariate
1064 evolution_function_is_affine_multivariate_p (const_tree chrec, int loopnum)
1066 if (chrec == NULL_TREE)
1069 switch (TREE_CODE (chrec))
1071 case POLYNOMIAL_CHREC:
1072 if (evolution_function_is_invariant_rec_p (CHREC_LEFT (chrec), loopnum))
1074 if (evolution_function_is_invariant_rec_p (CHREC_RIGHT (chrec), loopnum))
1078 if (TREE_CODE (CHREC_RIGHT (chrec)) == POLYNOMIAL_CHREC
1079 && CHREC_VARIABLE (CHREC_RIGHT (chrec))
1080 != CHREC_VARIABLE (chrec)
1081 && evolution_function_is_affine_multivariate_p
1082 (CHREC_RIGHT (chrec), loopnum))
1090 if (evolution_function_is_invariant_rec_p (CHREC_RIGHT (chrec), loopnum)
1091 && TREE_CODE (CHREC_LEFT (chrec)) == POLYNOMIAL_CHREC
1092 && CHREC_VARIABLE (CHREC_LEFT (chrec)) != CHREC_VARIABLE (chrec)
1093 && evolution_function_is_affine_multivariate_p
1094 (CHREC_LEFT (chrec), loopnum))
1105 /* Determine whether the given tree is a function in zero or one
1109 evolution_function_is_univariate_p (const_tree chrec)
1111 if (chrec == NULL_TREE)
1114 switch (TREE_CODE (chrec))
1116 case POLYNOMIAL_CHREC:
1117 switch (TREE_CODE (CHREC_LEFT (chrec)))
1119 case POLYNOMIAL_CHREC:
1120 if (CHREC_VARIABLE (chrec) != CHREC_VARIABLE (CHREC_LEFT (chrec)))
1122 if (!evolution_function_is_univariate_p (CHREC_LEFT (chrec)))
1127 if (tree_contains_chrecs (CHREC_LEFT (chrec), NULL))
1132 switch (TREE_CODE (CHREC_RIGHT (chrec)))
1134 case POLYNOMIAL_CHREC:
1135 if (CHREC_VARIABLE (chrec) != CHREC_VARIABLE (CHREC_RIGHT (chrec)))
1137 if (!evolution_function_is_univariate_p (CHREC_RIGHT (chrec)))
1142 if (tree_contains_chrecs (CHREC_RIGHT (chrec), NULL))
1152 /* Returns the number of variables of CHREC. Example: the call
1153 nb_vars_in_chrec ({{0, +, 1}_5, +, 2}_6) returns 2. */
1156 nb_vars_in_chrec (tree chrec)
1158 if (chrec == NULL_TREE)
1161 switch (TREE_CODE (chrec))
1163 case POLYNOMIAL_CHREC:
1164 return 1 + nb_vars_in_chrec
1165 (initial_condition_in_loop_num (chrec, CHREC_VARIABLE (chrec)));
1172 /* Converts BASE and STEP of affine scev to TYPE. LOOP is the loop whose iv
1173 the scev corresponds to. AT_STMT is the statement at that the scev is
1174 evaluated. USE_OVERFLOW_SEMANTICS is true if this function should assume that
1175 the rules for overflow of the given language apply (e.g., that signed
1176 arithmetics in C does not overflow) -- i.e., to use them to avoid unnecessary
1177 tests, but also to enforce that the result follows them. Returns true if the
1178 conversion succeeded, false otherwise. */
1181 convert_affine_scev (struct loop *loop, tree type,
1182 tree *base, tree *step, gimple *at_stmt,
1183 bool use_overflow_semantics)
1185 tree ct = TREE_TYPE (*step);
1186 bool enforce_overflow_semantics;
1187 bool must_check_src_overflow, must_check_rslt_overflow;
1188 tree new_base, new_step;
1189 tree step_type = POINTER_TYPE_P (type) ? sizetype : type;
1192 (TYPE) (BASE + STEP * i) = (TYPE) BASE + (TYPE -- sign extend) STEP * i,
1193 but we must check some assumptions.
1195 1) If [BASE, +, STEP] wraps, the equation is not valid when precision
1196 of CT is smaller than the precision of TYPE. For example, when we
1197 cast unsigned char [254, +, 1] to unsigned, the values on left side
1198 are 254, 255, 0, 1, ..., but those on the right side are
1199 254, 255, 256, 257, ...
1200 2) In case that we must also preserve the fact that signed ivs do not
1201 overflow, we must additionally check that the new iv does not wrap.
1202 For example, unsigned char [125, +, 1] casted to signed char could
1203 become a wrapping variable with values 125, 126, 127, -128, -127, ...,
1204 which would confuse optimizers that assume that this does not
1206 must_check_src_overflow = TYPE_PRECISION (ct) < TYPE_PRECISION (type);
1208 enforce_overflow_semantics = (use_overflow_semantics
1209 && nowrap_type_p (type));
1210 if (enforce_overflow_semantics)
1212 /* We can avoid checking whether the result overflows in the following
1215 -- must_check_src_overflow is true, and the range of TYPE is superset
1216 of the range of CT -- i.e., in all cases except if CT signed and
1218 -- both CT and TYPE have the same precision and signedness, and we
1219 verify instead that the source does not overflow (this may be
1220 easier than verifying it for the result, as we may use the
1221 information about the semantics of overflow in CT). */
1222 if (must_check_src_overflow)
1224 if (TYPE_UNSIGNED (type) && !TYPE_UNSIGNED (ct))
1225 must_check_rslt_overflow = true;
1227 must_check_rslt_overflow = false;
1229 else if (TYPE_UNSIGNED (ct) == TYPE_UNSIGNED (type)
1230 && TYPE_PRECISION (ct) == TYPE_PRECISION (type))
1232 must_check_rslt_overflow = false;
1233 must_check_src_overflow = true;
1236 must_check_rslt_overflow = true;
1239 must_check_rslt_overflow = false;
1241 if (must_check_src_overflow
1242 && scev_probably_wraps_p (*base, *step, at_stmt, loop,
1243 use_overflow_semantics))
1246 new_base = chrec_convert (type, *base, at_stmt, use_overflow_semantics);
1247 /* The step must be sign extended, regardless of the signedness
1248 of CT and TYPE. This only needs to be handled specially when
1249 CT is unsigned -- to avoid e.g. unsigned char [100, +, 255]
1250 (with values 100, 99, 98, ...) from becoming signed or unsigned
1251 [100, +, 255] with values 100, 355, ...; the sign-extension is
1252 performed by default when CT is signed. */
1254 if (TYPE_PRECISION (step_type) > TYPE_PRECISION (ct) && TYPE_UNSIGNED (ct))
1256 tree signed_ct = build_nonstandard_integer_type (TYPE_PRECISION (ct), 0);
1257 new_step = chrec_convert (signed_ct, new_step, at_stmt,
1258 use_overflow_semantics);
1260 new_step = chrec_convert (step_type, new_step, at_stmt,
1261 use_overflow_semantics);
1263 if (automatically_generated_chrec_p (new_base)
1264 || automatically_generated_chrec_p (new_step))
1267 if (must_check_rslt_overflow
1268 /* Note that in this case we cannot use the fact that signed variables
1269 do not overflow, as this is what we are verifying for the new iv. */
1270 && scev_probably_wraps_p (new_base, new_step, at_stmt, loop, false))
1279 /* Convert CHREC for the right hand side of a CHREC.
1280 The increment for a pointer type is always sizetype. */
1283 chrec_convert_rhs (tree type, tree chrec, gimple *at_stmt)
1285 if (POINTER_TYPE_P (type))
1288 return chrec_convert (type, chrec, at_stmt);
1291 /* Convert CHREC to TYPE. When the analyzer knows the context in
1292 which the CHREC is built, it sets AT_STMT to the statement that
1293 contains the definition of the analyzed variable, otherwise the
1294 conversion is less accurate: the information is used for
1295 determining a more accurate estimation of the number of iterations.
1296 By default AT_STMT could be safely set to NULL_TREE.
1298 USE_OVERFLOW_SEMANTICS is true if this function should assume that
1299 the rules for overflow of the given language apply (e.g., that signed
1300 arithmetics in C does not overflow) -- i.e., to use them to avoid unnecessary
1301 tests, but also to enforce that the result follows them. */
1304 chrec_convert_1 (tree type, tree chrec, gimple *at_stmt,
1305 bool use_overflow_semantics)
1311 if (automatically_generated_chrec_p (chrec))
1314 ct = chrec_type (chrec);
1315 if (useless_type_conversion_p (type, ct))
1318 if (!evolution_function_is_affine_p (chrec))
1321 loop = get_chrec_loop (chrec);
1322 base = CHREC_LEFT (chrec);
1323 step = CHREC_RIGHT (chrec);
1325 if (convert_affine_scev (loop, type, &base, &step, at_stmt,
1326 use_overflow_semantics))
1327 return build_polynomial_chrec (loop->num, base, step);
1329 /* If we cannot propagate the cast inside the chrec, just keep the cast. */
1331 /* Fold will not canonicalize (long)(i - 1) to (long)i - 1 because that
1332 may be more expensive. We do want to perform this optimization here
1333 though for canonicalization reasons. */
1334 if (use_overflow_semantics
1335 && (TREE_CODE (chrec) == PLUS_EXPR
1336 || TREE_CODE (chrec) == MINUS_EXPR)
1337 && TREE_CODE (type) == INTEGER_TYPE
1338 && TREE_CODE (ct) == INTEGER_TYPE
1339 && TYPE_PRECISION (type) > TYPE_PRECISION (ct)
1340 && TYPE_OVERFLOW_UNDEFINED (ct))
1341 res = fold_build2 (TREE_CODE (chrec), type,
1342 fold_convert (type, TREE_OPERAND (chrec, 0)),
1343 fold_convert (type, TREE_OPERAND (chrec, 1)));
1344 /* Similar perform the trick that (signed char)((int)x + 2) can be
1345 narrowed to (signed char)((unsigned char)x + 2). */
1346 else if (use_overflow_semantics
1347 && TREE_CODE (chrec) == POLYNOMIAL_CHREC
1348 && TREE_CODE (ct) == INTEGER_TYPE
1349 && TREE_CODE (type) == INTEGER_TYPE
1350 && TYPE_OVERFLOW_UNDEFINED (type)
1351 && TYPE_PRECISION (type) < TYPE_PRECISION (ct))
1353 tree utype = unsigned_type_for (type);
1354 res = build_polynomial_chrec (CHREC_VARIABLE (chrec),
1355 fold_convert (utype,
1356 CHREC_LEFT (chrec)),
1357 fold_convert (utype,
1358 CHREC_RIGHT (chrec)));
1359 res = chrec_convert_1 (type, res, at_stmt, use_overflow_semantics);
1362 res = fold_convert (type, chrec);
1364 /* Don't propagate overflows. */
1365 if (CONSTANT_CLASS_P (res))
1366 TREE_OVERFLOW (res) = 0;
1368 /* But reject constants that don't fit in their type after conversion.
1369 This can happen if TYPE_MIN_VALUE or TYPE_MAX_VALUE are not the
1370 natural values associated with TYPE_PRECISION and TYPE_UNSIGNED,
1371 and can cause problems later when computing niters of loops. Note
1372 that we don't do the check before converting because we don't want
1373 to reject conversions of negative chrecs to unsigned types. */
1374 if (TREE_CODE (res) == INTEGER_CST
1375 && TREE_CODE (type) == INTEGER_TYPE
1376 && !int_fits_type_p (res, type))
1377 res = chrec_dont_know;
1382 /* Convert CHREC to TYPE. When the analyzer knows the context in
1383 which the CHREC is built, it sets AT_STMT to the statement that
1384 contains the definition of the analyzed variable, otherwise the
1385 conversion is less accurate: the information is used for
1386 determining a more accurate estimation of the number of iterations.
1387 By default AT_STMT could be safely set to NULL_TREE.
1389 The following rule is always true: TREE_TYPE (chrec) ==
1390 TREE_TYPE (CHREC_LEFT (chrec)) == TREE_TYPE (CHREC_RIGHT (chrec)).
1391 An example of what could happen when adding two chrecs and the type
1392 of the CHREC_RIGHT is different than CHREC_LEFT is:
1394 {(uint) 0, +, (uchar) 10} +
1395 {(uint) 0, +, (uchar) 250}
1397 that would produce a wrong result if CHREC_RIGHT is not (uint):
1399 {(uint) 0, +, (uchar) 4}
1403 {(uint) 0, +, (uint) 260}
1405 USE_OVERFLOW_SEMANTICS is true if this function should assume that
1406 the rules for overflow of the given language apply (e.g., that signed
1407 arithmetics in C does not overflow) -- i.e., to use them to avoid unnecessary
1408 tests, but also to enforce that the result follows them. */
1411 chrec_convert (tree type, tree chrec, gimple *at_stmt,
1412 bool use_overflow_semantics)
1414 return chrec_convert_1 (type, chrec, at_stmt, use_overflow_semantics);
1417 /* Convert CHREC to TYPE, without regard to signed overflows. Returns the new
1418 chrec if something else than what chrec_convert would do happens, NULL_TREE
1419 otherwise. This function set TRUE to variable pointed by FOLD_CONVERSIONS
1420 if the result chrec may overflow. */
1423 chrec_convert_aggressive (tree type, tree chrec, bool *fold_conversions)
1425 tree inner_type, left, right, lc, rc, rtype;
1427 gcc_assert (fold_conversions != NULL);
1429 if (automatically_generated_chrec_p (chrec)
1430 || TREE_CODE (chrec) != POLYNOMIAL_CHREC)
1433 inner_type = TREE_TYPE (chrec);
1434 if (TYPE_PRECISION (type) > TYPE_PRECISION (inner_type))
1437 if (useless_type_conversion_p (type, inner_type))
1440 if (!*fold_conversions && evolution_function_is_affine_p (chrec))
1445 loop = get_chrec_loop (chrec);
1446 base = CHREC_LEFT (chrec);
1447 step = CHREC_RIGHT (chrec);
1448 if (convert_affine_scev (loop, type, &base, &step, NULL, true))
1449 return build_polynomial_chrec (loop->num, base, step);
1451 rtype = POINTER_TYPE_P (type) ? sizetype : type;
1453 left = CHREC_LEFT (chrec);
1454 right = CHREC_RIGHT (chrec);
1455 lc = chrec_convert_aggressive (type, left, fold_conversions);
1457 lc = chrec_convert (type, left, NULL);
1458 rc = chrec_convert_aggressive (rtype, right, fold_conversions);
1460 rc = chrec_convert (rtype, right, NULL);
1462 *fold_conversions = true;
1464 return build_polynomial_chrec (CHREC_VARIABLE (chrec), lc, rc);
1467 /* Returns true when CHREC0 == CHREC1. */
1470 eq_evolutions_p (const_tree chrec0, const_tree chrec1)
1472 if (chrec0 == NULL_TREE
1473 || chrec1 == NULL_TREE
1474 || TREE_CODE (chrec0) != TREE_CODE (chrec1))
1477 if (chrec0 == chrec1)
1480 if (! types_compatible_p (TREE_TYPE (chrec0), TREE_TYPE (chrec1)))
1483 switch (TREE_CODE (chrec0))
1485 case POLYNOMIAL_CHREC:
1486 return (CHREC_VARIABLE (chrec0) == CHREC_VARIABLE (chrec1)
1487 && eq_evolutions_p (CHREC_LEFT (chrec0), CHREC_LEFT (chrec1))
1488 && eq_evolutions_p (CHREC_RIGHT (chrec0), CHREC_RIGHT (chrec1)));
1493 case POINTER_PLUS_EXPR:
1494 return eq_evolutions_p (TREE_OPERAND (chrec0, 0),
1495 TREE_OPERAND (chrec1, 0))
1496 && eq_evolutions_p (TREE_OPERAND (chrec0, 1),
1497 TREE_OPERAND (chrec1, 1));
1500 return eq_evolutions_p (TREE_OPERAND (chrec0, 0),
1501 TREE_OPERAND (chrec1, 0));
1504 return operand_equal_p (chrec0, chrec1, 0);
1508 /* Returns EV_GROWS if CHREC grows (assuming that it does not overflow),
1509 EV_DECREASES if it decreases, and EV_UNKNOWN if we cannot determine
1510 which of these cases happens. */
1513 scev_direction (const_tree chrec)
1517 if (!evolution_function_is_affine_p (chrec))
1518 return EV_DIR_UNKNOWN;
1520 step = CHREC_RIGHT (chrec);
1521 if (TREE_CODE (step) != INTEGER_CST)
1522 return EV_DIR_UNKNOWN;
1524 if (tree_int_cst_sign_bit (step))
1525 return EV_DIR_DECREASES;
1527 return EV_DIR_GROWS;
1530 /* Iterates over all the components of SCEV, and calls CBCK. */
1533 for_each_scev_op (tree *scev, bool (*cbck) (tree *, void *), void *data)
1535 switch (TREE_CODE_LENGTH (TREE_CODE (*scev)))
1538 for_each_scev_op (&TREE_OPERAND (*scev, 2), cbck, data);
1542 for_each_scev_op (&TREE_OPERAND (*scev, 1), cbck, data);
1546 for_each_scev_op (&TREE_OPERAND (*scev, 0), cbck, data);
1555 /* Returns true when the operation can be part of a linear
1559 operator_is_linear (tree scev)
1561 switch (TREE_CODE (scev))
1564 case POLYNOMIAL_CHREC:
1566 case POINTER_PLUS_EXPR:
1571 case NON_LVALUE_EXPR:
1581 /* Return true when SCEV is a linear expression. Linear expressions
1582 can contain additions, substractions and multiplications.
1583 Multiplications are restricted to constant scaling: "cst * x". */
1586 scev_is_linear_expression (tree scev)
1589 || !operator_is_linear (scev))
1592 if (TREE_CODE (scev) == MULT_EXPR)
1593 return !(tree_contains_chrecs (TREE_OPERAND (scev, 0), NULL)
1594 && tree_contains_chrecs (TREE_OPERAND (scev, 1), NULL));
1596 if (TREE_CODE (scev) == POLYNOMIAL_CHREC
1597 && !evolution_function_is_affine_multivariate_p (scev, CHREC_VARIABLE (scev)))
1600 switch (TREE_CODE_LENGTH (TREE_CODE (scev)))
1603 return scev_is_linear_expression (TREE_OPERAND (scev, 0))
1604 && scev_is_linear_expression (TREE_OPERAND (scev, 1))
1605 && scev_is_linear_expression (TREE_OPERAND (scev, 2));
1608 return scev_is_linear_expression (TREE_OPERAND (scev, 0))
1609 && scev_is_linear_expression (TREE_OPERAND (scev, 1));
1612 return scev_is_linear_expression (TREE_OPERAND (scev, 0));
1622 /* Determines whether the expression CHREC contains only interger consts
1623 in the right parts. */
1626 evolution_function_right_is_integer_cst (const_tree chrec)
1628 if (chrec == NULL_TREE)
1631 switch (TREE_CODE (chrec))
1636 case POLYNOMIAL_CHREC:
1637 return TREE_CODE (CHREC_RIGHT (chrec)) == INTEGER_CST
1638 && (TREE_CODE (CHREC_LEFT (chrec)) != POLYNOMIAL_CHREC
1639 || evolution_function_right_is_integer_cst (CHREC_LEFT (chrec)));
1642 return evolution_function_right_is_integer_cst (TREE_OPERAND (chrec, 0));