1 /* Chains of recurrences.
2 Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
3 Free Software Foundation, Inc.
4 Contributed by Sebastian Pop <pop@cri.ensmp.fr>
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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/>. */
22 /* This file implements operations on chains of recurrences. Chains
23 of recurrences are used for modeling evolution functions of scalar
29 #include "coretypes.h"
33 #include "tree-pretty-print.h"
35 #include "tree-flow.h"
36 #include "tree-chrec.h"
37 #include "tree-pass.h"
40 #include "tree-scalar-evolution.h"
44 /* Extended folder for chrecs. */
46 /* Determines whether CST is not a constant evolution. */
49 is_not_constant_evolution (const_tree cst)
51 return (TREE_CODE (cst) == POLYNOMIAL_CHREC);
54 /* Fold CODE for a polynomial function and a constant. */
57 chrec_fold_poly_cst (enum tree_code code,
64 gcc_assert (TREE_CODE (poly) == POLYNOMIAL_CHREC);
65 gcc_assert (!is_not_constant_evolution (cst));
66 gcc_assert (type == chrec_type (poly));
71 return build_polynomial_chrec
72 (CHREC_VARIABLE (poly),
73 chrec_fold_plus (type, CHREC_LEFT (poly), cst),
77 return build_polynomial_chrec
78 (CHREC_VARIABLE (poly),
79 chrec_fold_minus (type, CHREC_LEFT (poly), cst),
83 return build_polynomial_chrec
84 (CHREC_VARIABLE (poly),
85 chrec_fold_multiply (type, CHREC_LEFT (poly), cst),
86 chrec_fold_multiply (type, CHREC_RIGHT (poly), cst));
89 return chrec_dont_know;
93 /* Fold the addition of two polynomial functions. */
96 chrec_fold_plus_poly_poly (enum tree_code code,
102 struct loop *loop0 = get_chrec_loop (poly0);
103 struct loop *loop1 = get_chrec_loop (poly1);
104 tree rtype = code == POINTER_PLUS_EXPR ? sizetype : type;
108 gcc_assert (TREE_CODE (poly0) == POLYNOMIAL_CHREC);
109 gcc_assert (TREE_CODE (poly1) == POLYNOMIAL_CHREC);
110 if (POINTER_TYPE_P (chrec_type (poly0)))
111 gcc_assert (chrec_type (poly1) == sizetype);
113 gcc_assert (chrec_type (poly0) == chrec_type (poly1));
114 gcc_assert (type == chrec_type (poly0));
117 {a, +, b}_1 + {c, +, d}_2 -> {{a, +, b}_1 + c, +, d}_2,
118 {a, +, b}_2 + {c, +, d}_1 -> {{c, +, d}_1 + a, +, b}_2,
119 {a, +, b}_x + {c, +, d}_x -> {a+c, +, b+d}_x. */
120 if (flow_loop_nested_p (loop0, loop1))
122 if (code == PLUS_EXPR || code == POINTER_PLUS_EXPR)
123 return build_polynomial_chrec
124 (CHREC_VARIABLE (poly1),
125 chrec_fold_plus (type, poly0, CHREC_LEFT (poly1)),
126 CHREC_RIGHT (poly1));
128 return build_polynomial_chrec
129 (CHREC_VARIABLE (poly1),
130 chrec_fold_minus (type, poly0, CHREC_LEFT (poly1)),
131 chrec_fold_multiply (type, CHREC_RIGHT (poly1),
132 SCALAR_FLOAT_TYPE_P (type)
133 ? build_real (type, dconstm1)
134 : build_int_cst_type (type, -1)));
137 if (flow_loop_nested_p (loop1, loop0))
139 if (code == PLUS_EXPR || code == POINTER_PLUS_EXPR)
140 return build_polynomial_chrec
141 (CHREC_VARIABLE (poly0),
142 chrec_fold_plus (type, CHREC_LEFT (poly0), poly1),
143 CHREC_RIGHT (poly0));
145 return build_polynomial_chrec
146 (CHREC_VARIABLE (poly0),
147 chrec_fold_minus (type, CHREC_LEFT (poly0), poly1),
148 CHREC_RIGHT (poly0));
151 /* This function should never be called for chrecs of loops that
152 do not belong to the same loop nest. */
153 gcc_assert (loop0 == loop1);
155 if (code == PLUS_EXPR || code == POINTER_PLUS_EXPR)
157 left = chrec_fold_plus
158 (type, CHREC_LEFT (poly0), CHREC_LEFT (poly1));
159 right = chrec_fold_plus
160 (rtype, CHREC_RIGHT (poly0), CHREC_RIGHT (poly1));
164 left = chrec_fold_minus
165 (type, CHREC_LEFT (poly0), CHREC_LEFT (poly1));
166 right = chrec_fold_minus
167 (type, CHREC_RIGHT (poly0), CHREC_RIGHT (poly1));
170 if (chrec_zerop (right))
173 return build_polynomial_chrec
174 (CHREC_VARIABLE (poly0), left, right);
179 /* Fold the multiplication of two polynomial functions. */
182 chrec_fold_multiply_poly_poly (tree type,
188 struct loop *loop0 = get_chrec_loop (poly0);
189 struct loop *loop1 = get_chrec_loop (poly1);
193 gcc_assert (TREE_CODE (poly0) == POLYNOMIAL_CHREC);
194 gcc_assert (TREE_CODE (poly1) == POLYNOMIAL_CHREC);
195 gcc_assert (chrec_type (poly0) == chrec_type (poly1));
196 gcc_assert (type == chrec_type (poly0));
198 /* {a, +, b}_1 * {c, +, d}_2 -> {c*{a, +, b}_1, +, d}_2,
199 {a, +, b}_2 * {c, +, d}_1 -> {a*{c, +, d}_1, +, b}_2,
200 {a, +, b}_x * {c, +, d}_x -> {a*c, +, a*d + b*c + b*d, +, 2*b*d}_x. */
201 if (flow_loop_nested_p (loop0, loop1))
202 /* poly0 is a constant wrt. poly1. */
203 return build_polynomial_chrec
204 (CHREC_VARIABLE (poly1),
205 chrec_fold_multiply (type, CHREC_LEFT (poly1), poly0),
206 CHREC_RIGHT (poly1));
208 if (flow_loop_nested_p (loop1, loop0))
209 /* poly1 is a constant wrt. poly0. */
210 return build_polynomial_chrec
211 (CHREC_VARIABLE (poly0),
212 chrec_fold_multiply (type, CHREC_LEFT (poly0), poly1),
213 CHREC_RIGHT (poly0));
215 gcc_assert (loop0 == loop1);
217 /* poly0 and poly1 are two polynomials in the same variable,
218 {a, +, b}_x * {c, +, d}_x -> {a*c, +, a*d + b*c + b*d, +, 2*b*d}_x. */
221 t0 = chrec_fold_multiply (type, CHREC_LEFT (poly0), CHREC_LEFT (poly1));
224 t1 = chrec_fold_multiply (type, CHREC_LEFT (poly0), CHREC_RIGHT (poly1));
225 t1 = chrec_fold_plus (type, t1, chrec_fold_multiply (type,
227 CHREC_LEFT (poly1)));
229 t2 = chrec_fold_multiply (type, CHREC_RIGHT (poly0), CHREC_RIGHT (poly1));
230 /* "a*d + b*c + b*d". */
231 t1 = chrec_fold_plus (type, t1, t2);
233 t2 = chrec_fold_multiply (type, SCALAR_FLOAT_TYPE_P (type)
234 ? build_real (type, dconst2)
235 : build_int_cst (type, 2), t2);
237 var = CHREC_VARIABLE (poly0);
238 return build_polynomial_chrec (var, t0,
239 build_polynomial_chrec (var, t1, t2));
242 /* When the operands are automatically_generated_chrec_p, the fold has
243 to respect the semantics of the operands. */
246 chrec_fold_automatically_generated_operands (tree op0,
249 if (op0 == chrec_dont_know
250 || op1 == chrec_dont_know)
251 return chrec_dont_know;
253 if (op0 == chrec_known
254 || op1 == chrec_known)
257 if (op0 == chrec_not_analyzed_yet
258 || op1 == chrec_not_analyzed_yet)
259 return chrec_not_analyzed_yet;
261 /* The default case produces a safe result. */
262 return chrec_dont_know;
265 /* Fold the addition of two chrecs. */
268 chrec_fold_plus_1 (enum tree_code code, tree type,
271 tree op1_type = code == POINTER_PLUS_EXPR ? sizetype : type;
273 if (automatically_generated_chrec_p (op0)
274 || automatically_generated_chrec_p (op1))
275 return chrec_fold_automatically_generated_operands (op0, op1);
277 switch (TREE_CODE (op0))
279 case POLYNOMIAL_CHREC:
280 switch (TREE_CODE (op1))
282 case POLYNOMIAL_CHREC:
283 return chrec_fold_plus_poly_poly (code, type, op0, op1);
286 if (tree_contains_chrecs (op1, NULL))
287 return chrec_dont_know;
290 if (code == PLUS_EXPR || code == POINTER_PLUS_EXPR)
291 return build_polynomial_chrec
292 (CHREC_VARIABLE (op0),
293 chrec_fold_plus (type, CHREC_LEFT (op0), op1),
296 return build_polynomial_chrec
297 (CHREC_VARIABLE (op0),
298 chrec_fold_minus (type, CHREC_LEFT (op0), op1),
303 if (tree_contains_chrecs (op0, NULL))
304 return chrec_dont_know;
307 switch (TREE_CODE (op1))
309 case POLYNOMIAL_CHREC:
310 if (code == PLUS_EXPR || code == POINTER_PLUS_EXPR)
311 return build_polynomial_chrec
312 (CHREC_VARIABLE (op1),
313 chrec_fold_plus (type, op0, CHREC_LEFT (op1)),
316 return build_polynomial_chrec
317 (CHREC_VARIABLE (op1),
318 chrec_fold_minus (type, op0, CHREC_LEFT (op1)),
319 chrec_fold_multiply (type, CHREC_RIGHT (op1),
320 SCALAR_FLOAT_TYPE_P (type)
321 ? build_real (type, dconstm1)
322 : build_int_cst_type (type, -1)));
325 if (tree_contains_chrecs (op1, NULL))
326 return chrec_dont_know;
331 if ((tree_contains_chrecs (op0, &size)
332 || tree_contains_chrecs (op1, &size))
333 && size < PARAM_VALUE (PARAM_SCEV_MAX_EXPR_SIZE))
334 return build2 (code, type, op0, op1);
335 else if (size < PARAM_VALUE (PARAM_SCEV_MAX_EXPR_SIZE))
336 return fold_build2 (code, type,
337 fold_convert (type, op0),
338 fold_convert (op1_type, op1));
340 return chrec_dont_know;
346 /* Fold the addition of two chrecs. */
349 chrec_fold_plus (tree type,
354 if (automatically_generated_chrec_p (op0)
355 || automatically_generated_chrec_p (op1))
356 return chrec_fold_automatically_generated_operands (op0, op1);
358 if (integer_zerop (op0))
359 return chrec_convert (type, op1, NULL);
360 if (integer_zerop (op1))
361 return chrec_convert (type, op0, NULL);
363 if (POINTER_TYPE_P (type))
364 code = POINTER_PLUS_EXPR;
368 return chrec_fold_plus_1 (code, type, op0, op1);
371 /* Fold the subtraction of two chrecs. */
374 chrec_fold_minus (tree type,
378 if (automatically_generated_chrec_p (op0)
379 || automatically_generated_chrec_p (op1))
380 return chrec_fold_automatically_generated_operands (op0, op1);
382 if (integer_zerop (op1))
385 return chrec_fold_plus_1 (MINUS_EXPR, type, op0, op1);
388 /* Fold the multiplication of two chrecs. */
391 chrec_fold_multiply (tree type,
395 if (automatically_generated_chrec_p (op0)
396 || automatically_generated_chrec_p (op1))
397 return chrec_fold_automatically_generated_operands (op0, op1);
399 switch (TREE_CODE (op0))
401 case POLYNOMIAL_CHREC:
402 switch (TREE_CODE (op1))
404 case POLYNOMIAL_CHREC:
405 return chrec_fold_multiply_poly_poly (type, op0, op1);
408 if (tree_contains_chrecs (op1, NULL))
409 return chrec_dont_know;
412 if (integer_onep (op1))
414 if (integer_zerop (op1))
415 return build_int_cst (type, 0);
417 return build_polynomial_chrec
418 (CHREC_VARIABLE (op0),
419 chrec_fold_multiply (type, CHREC_LEFT (op0), op1),
420 chrec_fold_multiply (type, CHREC_RIGHT (op0), op1));
424 if (tree_contains_chrecs (op0, NULL))
425 return chrec_dont_know;
428 if (integer_onep (op0))
431 if (integer_zerop (op0))
432 return build_int_cst (type, 0);
434 switch (TREE_CODE (op1))
436 case POLYNOMIAL_CHREC:
437 return build_polynomial_chrec
438 (CHREC_VARIABLE (op1),
439 chrec_fold_multiply (type, CHREC_LEFT (op1), op0),
440 chrec_fold_multiply (type, CHREC_RIGHT (op1), op0));
443 if (tree_contains_chrecs (op1, NULL))
444 return chrec_dont_know;
447 if (integer_onep (op1))
449 if (integer_zerop (op1))
450 return build_int_cst (type, 0);
451 return fold_build2 (MULT_EXPR, type, op0, op1);
460 /* Evaluate the binomial coefficient. Return NULL_TREE if the intermediate
461 calculation overflows, otherwise return C(n,k) with type TYPE. */
464 tree_fold_binomial (tree type, tree n, unsigned int k)
466 unsigned HOST_WIDE_INT lidx, lnum, ldenom, lres, ldum;
467 HOST_WIDE_INT hidx, hnum, hdenom, hres, hdum;
471 /* Handle the most frequent cases. */
473 return build_int_cst (type, 1);
475 return fold_convert (type, n);
477 /* Check that k <= n. */
478 if (TREE_INT_CST_HIGH (n) == 0
479 && TREE_INT_CST_LOW (n) < k)
483 lnum = TREE_INT_CST_LOW (n);
484 hnum = TREE_INT_CST_HIGH (n);
486 /* Denominator = 2. */
490 /* Index = Numerator-1. */
494 lidx = ~ (unsigned HOST_WIDE_INT) 0;
502 /* Numerator = Numerator*Index = n*(n-1). */
503 if (mul_double (lnum, hnum, lidx, hidx, &lnum, &hnum))
506 for (i = 3; i <= k; i++)
512 lidx = ~ (unsigned HOST_WIDE_INT) 0;
517 /* Numerator *= Index. */
518 if (mul_double (lnum, hnum, lidx, hidx, &lnum, &hnum))
521 /* Denominator *= i. */
522 mul_double (ldenom, hdenom, i, 0, &ldenom, &hdenom);
525 /* Result = Numerator / Denominator. */
526 div_and_round_double (EXACT_DIV_EXPR, 1, lnum, hnum, ldenom, hdenom,
527 &lres, &hres, &ldum, &hdum);
529 res = build_int_cst_wide (type, lres, hres);
530 return int_fits_type_p (res, type) ? res : NULL_TREE;
533 /* Helper function. Use the Newton's interpolating formula for
534 evaluating the value of the evolution function. */
537 chrec_evaluate (unsigned var, tree chrec, tree n, unsigned int k)
539 tree arg0, arg1, binomial_n_k;
540 tree type = TREE_TYPE (chrec);
541 struct loop *var_loop = get_loop (var);
543 while (TREE_CODE (chrec) == POLYNOMIAL_CHREC
544 && flow_loop_nested_p (var_loop, get_chrec_loop (chrec)))
545 chrec = CHREC_LEFT (chrec);
547 if (TREE_CODE (chrec) == POLYNOMIAL_CHREC
548 && CHREC_VARIABLE (chrec) == var)
550 arg1 = chrec_evaluate (var, CHREC_RIGHT (chrec), n, k + 1);
551 if (arg1 == chrec_dont_know)
552 return chrec_dont_know;
553 binomial_n_k = tree_fold_binomial (type, n, k);
555 return chrec_dont_know;
556 arg0 = fold_build2 (MULT_EXPR, type,
557 CHREC_LEFT (chrec), binomial_n_k);
558 return chrec_fold_plus (type, arg0, arg1);
561 binomial_n_k = tree_fold_binomial (type, n, k);
563 return chrec_dont_know;
565 return fold_build2 (MULT_EXPR, type, chrec, binomial_n_k);
568 /* Evaluates "CHREC (X)" when the varying variable is VAR.
569 Example: Given the following parameters,
575 The result is given by the Newton's interpolating formula:
576 3 * \binom{10}{0} + 4 * \binom{10}{1}.
580 chrec_apply (unsigned var,
584 tree type = chrec_type (chrec);
585 tree res = chrec_dont_know;
587 if (automatically_generated_chrec_p (chrec)
588 || automatically_generated_chrec_p (x)
590 /* When the symbols are defined in an outer loop, it is possible
591 to symbolically compute the apply, since the symbols are
592 constants with respect to the varying loop. */
593 || chrec_contains_symbols_defined_in_loop (chrec, var))
594 return chrec_dont_know;
596 if (dump_file && (dump_flags & TDF_DETAILS))
597 fprintf (dump_file, "(chrec_apply \n");
599 if (TREE_CODE (x) == INTEGER_CST && SCALAR_FLOAT_TYPE_P (type))
600 x = build_real_from_int_cst (type, x);
602 if (evolution_function_is_affine_p (chrec))
604 /* "{a, +, b} (x)" -> "a + b*x". */
605 x = chrec_convert_rhs (type, x, NULL);
606 res = chrec_fold_multiply (TREE_TYPE (x), CHREC_RIGHT (chrec), x);
607 res = chrec_fold_plus (type, CHREC_LEFT (chrec), res);
610 else if (TREE_CODE (chrec) != POLYNOMIAL_CHREC)
613 else if (TREE_CODE (x) == INTEGER_CST
614 && tree_int_cst_sgn (x) == 1)
615 /* testsuite/.../ssa-chrec-38.c. */
616 res = chrec_evaluate (var, chrec, x, 0);
618 res = chrec_dont_know;
620 if (dump_file && (dump_flags & TDF_DETAILS))
622 fprintf (dump_file, " (varying_loop = %d\n", var);
623 fprintf (dump_file, ")\n (chrec = ");
624 print_generic_expr (dump_file, chrec, 0);
625 fprintf (dump_file, ")\n (x = ");
626 print_generic_expr (dump_file, x, 0);
627 fprintf (dump_file, ")\n (res = ");
628 print_generic_expr (dump_file, res, 0);
629 fprintf (dump_file, "))\n");
635 /* For a given CHREC and an induction variable map IV_MAP that maps
636 (loop->num, expr) for every loop number of the current_loops an
637 expression, calls chrec_apply when the expression is not NULL. */
640 chrec_apply_map (tree chrec, VEC (tree, heap) *iv_map)
645 for (i = 0; VEC_iterate (tree, iv_map, i, expr); i++)
647 chrec = chrec_apply (i, chrec, expr);
652 /* Replaces the initial condition in CHREC with INIT_COND. */
655 chrec_replace_initial_condition (tree chrec,
658 if (automatically_generated_chrec_p (chrec))
661 gcc_assert (chrec_type (chrec) == chrec_type (init_cond));
663 switch (TREE_CODE (chrec))
665 case POLYNOMIAL_CHREC:
666 return build_polynomial_chrec
667 (CHREC_VARIABLE (chrec),
668 chrec_replace_initial_condition (CHREC_LEFT (chrec), init_cond),
669 CHREC_RIGHT (chrec));
676 /* Returns the initial condition of a given CHREC. */
679 initial_condition (tree chrec)
681 if (automatically_generated_chrec_p (chrec))
684 if (TREE_CODE (chrec) == POLYNOMIAL_CHREC)
685 return initial_condition (CHREC_LEFT (chrec));
690 /* Returns a univariate function that represents the evolution in
691 LOOP_NUM. Mask the evolution of any other loop. */
694 hide_evolution_in_other_loops_than_loop (tree chrec,
697 struct loop *loop = get_loop (loop_num), *chloop;
698 if (automatically_generated_chrec_p (chrec))
701 switch (TREE_CODE (chrec))
703 case POLYNOMIAL_CHREC:
704 chloop = get_chrec_loop (chrec);
707 return build_polynomial_chrec
709 hide_evolution_in_other_loops_than_loop (CHREC_LEFT (chrec),
711 CHREC_RIGHT (chrec));
713 else if (flow_loop_nested_p (chloop, loop))
714 /* There is no evolution in this loop. */
715 return initial_condition (chrec);
719 gcc_assert (flow_loop_nested_p (loop, chloop));
720 return hide_evolution_in_other_loops_than_loop (CHREC_LEFT (chrec),
729 /* Returns the evolution part of CHREC in LOOP_NUM when RIGHT is
730 true, otherwise returns the initial condition in LOOP_NUM. */
733 chrec_component_in_loop_num (tree chrec,
738 struct loop *loop = get_loop (loop_num), *chloop;
740 if (automatically_generated_chrec_p (chrec))
743 switch (TREE_CODE (chrec))
745 case POLYNOMIAL_CHREC:
746 chloop = get_chrec_loop (chrec);
751 component = CHREC_RIGHT (chrec);
753 component = CHREC_LEFT (chrec);
755 if (TREE_CODE (CHREC_LEFT (chrec)) != POLYNOMIAL_CHREC
756 || CHREC_VARIABLE (CHREC_LEFT (chrec)) != CHREC_VARIABLE (chrec))
760 return build_polynomial_chrec
762 chrec_component_in_loop_num (CHREC_LEFT (chrec),
768 else if (flow_loop_nested_p (chloop, loop))
769 /* There is no evolution part in this loop. */
774 gcc_assert (flow_loop_nested_p (loop, chloop));
775 return chrec_component_in_loop_num (CHREC_LEFT (chrec),
788 /* Returns the evolution part in LOOP_NUM. Example: the call
789 evolution_part_in_loop_num ({{0, +, 1}_1, +, 2}_1, 1) returns
793 evolution_part_in_loop_num (tree chrec,
796 return chrec_component_in_loop_num (chrec, loop_num, true);
799 /* Returns the initial condition in LOOP_NUM. Example: the call
800 initial_condition_in_loop_num ({{0, +, 1}_1, +, 2}_2, 2) returns
804 initial_condition_in_loop_num (tree chrec,
807 return chrec_component_in_loop_num (chrec, loop_num, false);
810 /* Set or reset the evolution of CHREC to NEW_EVOL in loop LOOP_NUM.
811 This function is essentially used for setting the evolution to
812 chrec_dont_know, for example after having determined that it is
813 impossible to say how many times a loop will execute. */
816 reset_evolution_in_loop (unsigned loop_num,
820 struct loop *loop = get_loop (loop_num);
822 if (POINTER_TYPE_P (chrec_type (chrec)))
823 gcc_assert (sizetype == chrec_type (new_evol));
825 gcc_assert (chrec_type (chrec) == chrec_type (new_evol));
827 if (TREE_CODE (chrec) == POLYNOMIAL_CHREC
828 && flow_loop_nested_p (loop, get_chrec_loop (chrec)))
830 tree left = reset_evolution_in_loop (loop_num, CHREC_LEFT (chrec),
832 tree right = reset_evolution_in_loop (loop_num, CHREC_RIGHT (chrec),
834 return build3 (POLYNOMIAL_CHREC, TREE_TYPE (left),
835 build_int_cst (NULL_TREE, CHREC_VARIABLE (chrec)),
839 while (TREE_CODE (chrec) == POLYNOMIAL_CHREC
840 && CHREC_VARIABLE (chrec) == loop_num)
841 chrec = CHREC_LEFT (chrec);
843 return build_polynomial_chrec (loop_num, chrec, new_evol);
846 /* Merges two evolution functions that were found by following two
847 alternate paths of a conditional expression. */
850 chrec_merge (tree chrec1,
853 if (chrec1 == chrec_dont_know
854 || chrec2 == chrec_dont_know)
855 return chrec_dont_know;
857 if (chrec1 == chrec_known
858 || chrec2 == chrec_known)
861 if (chrec1 == chrec_not_analyzed_yet)
863 if (chrec2 == chrec_not_analyzed_yet)
866 if (eq_evolutions_p (chrec1, chrec2))
869 return chrec_dont_know;
876 /* Helper function for is_multivariate_chrec. */
879 is_multivariate_chrec_rec (const_tree chrec, unsigned int rec_var)
881 if (chrec == NULL_TREE)
884 if (TREE_CODE (chrec) == POLYNOMIAL_CHREC)
886 if (CHREC_VARIABLE (chrec) != rec_var)
889 return (is_multivariate_chrec_rec (CHREC_LEFT (chrec), rec_var)
890 || is_multivariate_chrec_rec (CHREC_RIGHT (chrec), rec_var));
896 /* Determine whether the given chrec is multivariate or not. */
899 is_multivariate_chrec (const_tree chrec)
901 if (chrec == NULL_TREE)
904 if (TREE_CODE (chrec) == POLYNOMIAL_CHREC)
905 return (is_multivariate_chrec_rec (CHREC_LEFT (chrec),
906 CHREC_VARIABLE (chrec))
907 || is_multivariate_chrec_rec (CHREC_RIGHT (chrec),
908 CHREC_VARIABLE (chrec)));
913 /* Determines whether the chrec contains symbolic names or not. */
916 chrec_contains_symbols (const_tree chrec)
920 if (chrec == NULL_TREE)
923 if (TREE_CODE (chrec) == SSA_NAME
924 || TREE_CODE (chrec) == VAR_DECL
925 || TREE_CODE (chrec) == PARM_DECL
926 || TREE_CODE (chrec) == FUNCTION_DECL
927 || TREE_CODE (chrec) == LABEL_DECL
928 || TREE_CODE (chrec) == RESULT_DECL
929 || TREE_CODE (chrec) == FIELD_DECL)
932 n = TREE_OPERAND_LENGTH (chrec);
933 for (i = 0; i < n; i++)
934 if (chrec_contains_symbols (TREE_OPERAND (chrec, i)))
939 /* Determines whether the chrec contains undetermined coefficients. */
942 chrec_contains_undetermined (const_tree chrec)
946 if (chrec == chrec_dont_know)
949 if (chrec == NULL_TREE)
952 n = TREE_OPERAND_LENGTH (chrec);
953 for (i = 0; i < n; i++)
954 if (chrec_contains_undetermined (TREE_OPERAND (chrec, i)))
959 /* Determines whether the tree EXPR contains chrecs, and increment
960 SIZE if it is not a NULL pointer by an estimation of the depth of
964 tree_contains_chrecs (const_tree expr, int *size)
968 if (expr == NULL_TREE)
974 if (tree_is_chrec (expr))
977 n = TREE_OPERAND_LENGTH (expr);
978 for (i = 0; i < n; i++)
979 if (tree_contains_chrecs (TREE_OPERAND (expr, i), size))
984 /* Recursive helper function. */
987 evolution_function_is_invariant_rec_p (tree chrec, int loopnum)
989 if (evolution_function_is_constant_p (chrec))
992 if (TREE_CODE (chrec) == SSA_NAME
994 || expr_invariant_in_loop_p (get_loop (loopnum), chrec)))
997 if (TREE_CODE (chrec) == POLYNOMIAL_CHREC)
999 if (CHREC_VARIABLE (chrec) == (unsigned) loopnum
1000 || !evolution_function_is_invariant_rec_p (CHREC_RIGHT (chrec),
1002 || !evolution_function_is_invariant_rec_p (CHREC_LEFT (chrec),
1008 switch (TREE_OPERAND_LENGTH (chrec))
1011 if (!evolution_function_is_invariant_rec_p (TREE_OPERAND (chrec, 1),
1016 if (!evolution_function_is_invariant_rec_p (TREE_OPERAND (chrec, 0),
1028 /* Return true if CHREC is invariant in loop LOOPNUM, false otherwise. */
1031 evolution_function_is_invariant_p (tree chrec, int loopnum)
1033 return evolution_function_is_invariant_rec_p (chrec, loopnum);
1036 /* Determine whether the given tree is an affine multivariate
1040 evolution_function_is_affine_multivariate_p (const_tree chrec, int loopnum)
1042 if (chrec == NULL_TREE)
1045 switch (TREE_CODE (chrec))
1047 case POLYNOMIAL_CHREC:
1048 if (evolution_function_is_invariant_rec_p (CHREC_LEFT (chrec), loopnum))
1050 if (evolution_function_is_invariant_rec_p (CHREC_RIGHT (chrec), loopnum))
1054 if (TREE_CODE (CHREC_RIGHT (chrec)) == POLYNOMIAL_CHREC
1055 && CHREC_VARIABLE (CHREC_RIGHT (chrec))
1056 != CHREC_VARIABLE (chrec)
1057 && evolution_function_is_affine_multivariate_p
1058 (CHREC_RIGHT (chrec), loopnum))
1066 if (evolution_function_is_invariant_rec_p (CHREC_RIGHT (chrec), loopnum)
1067 && TREE_CODE (CHREC_LEFT (chrec)) == POLYNOMIAL_CHREC
1068 && CHREC_VARIABLE (CHREC_LEFT (chrec)) != CHREC_VARIABLE (chrec)
1069 && evolution_function_is_affine_multivariate_p
1070 (CHREC_LEFT (chrec), loopnum))
1081 /* Determine whether the given tree is a function in zero or one
1085 evolution_function_is_univariate_p (const_tree chrec)
1087 if (chrec == NULL_TREE)
1090 switch (TREE_CODE (chrec))
1092 case POLYNOMIAL_CHREC:
1093 switch (TREE_CODE (CHREC_LEFT (chrec)))
1095 case POLYNOMIAL_CHREC:
1096 if (CHREC_VARIABLE (chrec) != CHREC_VARIABLE (CHREC_LEFT (chrec)))
1098 if (!evolution_function_is_univariate_p (CHREC_LEFT (chrec)))
1106 switch (TREE_CODE (CHREC_RIGHT (chrec)))
1108 case POLYNOMIAL_CHREC:
1109 if (CHREC_VARIABLE (chrec) != CHREC_VARIABLE (CHREC_RIGHT (chrec)))
1111 if (!evolution_function_is_univariate_p (CHREC_RIGHT (chrec)))
1124 /* Returns the number of variables of CHREC. Example: the call
1125 nb_vars_in_chrec ({{0, +, 1}_5, +, 2}_6) returns 2. */
1128 nb_vars_in_chrec (tree chrec)
1130 if (chrec == NULL_TREE)
1133 switch (TREE_CODE (chrec))
1135 case POLYNOMIAL_CHREC:
1136 return 1 + nb_vars_in_chrec
1137 (initial_condition_in_loop_num (chrec, CHREC_VARIABLE (chrec)));
1144 static tree chrec_convert_1 (tree, tree, gimple, bool);
1146 /* Converts BASE and STEP of affine scev to TYPE. LOOP is the loop whose iv
1147 the scev corresponds to. AT_STMT is the statement at that the scev is
1148 evaluated. USE_OVERFLOW_SEMANTICS is true if this function should assume that
1149 the rules for overflow of the given language apply (e.g., that signed
1150 arithmetics in C does not overflow) -- i.e., to use them to avoid unnecessary
1151 tests, but also to enforce that the result follows them. Returns true if the
1152 conversion succeeded, false otherwise. */
1155 convert_affine_scev (struct loop *loop, tree type,
1156 tree *base, tree *step, gimple at_stmt,
1157 bool use_overflow_semantics)
1159 tree ct = TREE_TYPE (*step);
1160 bool enforce_overflow_semantics;
1161 bool must_check_src_overflow, must_check_rslt_overflow;
1162 tree new_base, new_step;
1163 tree step_type = POINTER_TYPE_P (type) ? sizetype : type;
1166 (TYPE) (BASE + STEP * i) = (TYPE) BASE + (TYPE -- sign extend) STEP * i,
1167 but we must check some assumptions.
1169 1) If [BASE, +, STEP] wraps, the equation is not valid when precision
1170 of CT is smaller than the precision of TYPE. For example, when we
1171 cast unsigned char [254, +, 1] to unsigned, the values on left side
1172 are 254, 255, 0, 1, ..., but those on the right side are
1173 254, 255, 256, 257, ...
1174 2) In case that we must also preserve the fact that signed ivs do not
1175 overflow, we must additionally check that the new iv does not wrap.
1176 For example, unsigned char [125, +, 1] casted to signed char could
1177 become a wrapping variable with values 125, 126, 127, -128, -127, ...,
1178 which would confuse optimizers that assume that this does not
1180 must_check_src_overflow = TYPE_PRECISION (ct) < TYPE_PRECISION (type);
1182 enforce_overflow_semantics = (use_overflow_semantics
1183 && nowrap_type_p (type));
1184 if (enforce_overflow_semantics)
1186 /* We can avoid checking whether the result overflows in the following
1189 -- must_check_src_overflow is true, and the range of TYPE is superset
1190 of the range of CT -- i.e., in all cases except if CT signed and
1192 -- both CT and TYPE have the same precision and signedness, and we
1193 verify instead that the source does not overflow (this may be
1194 easier than verifying it for the result, as we may use the
1195 information about the semantics of overflow in CT). */
1196 if (must_check_src_overflow)
1198 if (TYPE_UNSIGNED (type) && !TYPE_UNSIGNED (ct))
1199 must_check_rslt_overflow = true;
1201 must_check_rslt_overflow = false;
1203 else if (TYPE_UNSIGNED (ct) == TYPE_UNSIGNED (type)
1204 && TYPE_PRECISION (ct) == TYPE_PRECISION (type))
1206 must_check_rslt_overflow = false;
1207 must_check_src_overflow = true;
1210 must_check_rslt_overflow = true;
1213 must_check_rslt_overflow = false;
1215 if (must_check_src_overflow
1216 && scev_probably_wraps_p (*base, *step, at_stmt, loop,
1217 use_overflow_semantics))
1220 new_base = chrec_convert_1 (type, *base, at_stmt,
1221 use_overflow_semantics);
1222 /* The step must be sign extended, regardless of the signedness
1223 of CT and TYPE. This only needs to be handled specially when
1224 CT is unsigned -- to avoid e.g. unsigned char [100, +, 255]
1225 (with values 100, 99, 98, ...) from becoming signed or unsigned
1226 [100, +, 255] with values 100, 355, ...; the sign-extension is
1227 performed by default when CT is signed. */
1229 if (TYPE_PRECISION (step_type) > TYPE_PRECISION (ct) && TYPE_UNSIGNED (ct))
1230 new_step = chrec_convert_1 (signed_type_for (ct), new_step, at_stmt,
1231 use_overflow_semantics);
1232 new_step = chrec_convert_1 (step_type, new_step, at_stmt, use_overflow_semantics);
1234 if (automatically_generated_chrec_p (new_base)
1235 || automatically_generated_chrec_p (new_step))
1238 if (must_check_rslt_overflow
1239 /* Note that in this case we cannot use the fact that signed variables
1240 do not overflow, as this is what we are verifying for the new iv. */
1241 && scev_probably_wraps_p (new_base, new_step, at_stmt, loop, false))
1250 /* Convert CHREC for the right hand side of a CHREC.
1251 The increment for a pointer type is always sizetype. */
1254 chrec_convert_rhs (tree type, tree chrec, gimple at_stmt)
1256 if (POINTER_TYPE_P (type))
1259 return chrec_convert (type, chrec, at_stmt);
1262 /* Convert CHREC to TYPE. When the analyzer knows the context in
1263 which the CHREC is built, it sets AT_STMT to the statement that
1264 contains the definition of the analyzed variable, otherwise the
1265 conversion is less accurate: the information is used for
1266 determining a more accurate estimation of the number of iterations.
1267 By default AT_STMT could be safely set to NULL_TREE.
1269 The following rule is always true: TREE_TYPE (chrec) ==
1270 TREE_TYPE (CHREC_LEFT (chrec)) == TREE_TYPE (CHREC_RIGHT (chrec)).
1271 An example of what could happen when adding two chrecs and the type
1272 of the CHREC_RIGHT is different than CHREC_LEFT is:
1274 {(uint) 0, +, (uchar) 10} +
1275 {(uint) 0, +, (uchar) 250}
1277 that would produce a wrong result if CHREC_RIGHT is not (uint):
1279 {(uint) 0, +, (uchar) 4}
1283 {(uint) 0, +, (uint) 260}
1287 chrec_convert (tree type, tree chrec, gimple at_stmt)
1289 return chrec_convert_1 (type, chrec, at_stmt, true);
1292 /* Convert CHREC to TYPE. When the analyzer knows the context in
1293 which the CHREC is built, it sets AT_STMT to the statement that
1294 contains the definition of the analyzed variable, otherwise the
1295 conversion is less accurate: the information is used for
1296 determining a more accurate estimation of the number of iterations.
1297 By default AT_STMT could be safely set to NULL_TREE.
1299 USE_OVERFLOW_SEMANTICS is true if this function should assume that
1300 the rules for overflow of the given language apply (e.g., that signed
1301 arithmetics in C does not overflow) -- i.e., to use them to avoid unnecessary
1302 tests, but also to enforce that the result follows them. */
1305 chrec_convert_1 (tree type, tree chrec, gimple at_stmt,
1306 bool use_overflow_semantics)
1312 if (automatically_generated_chrec_p (chrec))
1315 ct = chrec_type (chrec);
1319 if (!evolution_function_is_affine_p (chrec))
1322 loop = get_chrec_loop (chrec);
1323 base = CHREC_LEFT (chrec);
1324 step = CHREC_RIGHT (chrec);
1326 if (convert_affine_scev (loop, type, &base, &step, at_stmt,
1327 use_overflow_semantics))
1328 return build_polynomial_chrec (loop->num, base, step);
1330 /* If we cannot propagate the cast inside the chrec, just keep the cast. */
1332 /* Fold will not canonicalize (long)(i - 1) to (long)i - 1 because that
1333 may be more expensive. We do want to perform this optimization here
1334 though for canonicalization reasons. */
1335 if (use_overflow_semantics
1336 && (TREE_CODE (chrec) == PLUS_EXPR
1337 || TREE_CODE (chrec) == MINUS_EXPR)
1338 && TREE_CODE (type) == INTEGER_TYPE
1339 && TREE_CODE (ct) == INTEGER_TYPE
1340 && TYPE_PRECISION (type) > TYPE_PRECISION (ct)
1341 && TYPE_OVERFLOW_UNDEFINED (ct))
1342 res = fold_build2 (TREE_CODE (chrec), type,
1343 fold_convert (type, TREE_OPERAND (chrec, 0)),
1344 fold_convert (type, TREE_OPERAND (chrec, 1)));
1346 res = fold_convert (type, chrec);
1348 /* Don't propagate overflows. */
1349 if (CONSTANT_CLASS_P (res))
1350 TREE_OVERFLOW (res) = 0;
1352 /* But reject constants that don't fit in their type after conversion.
1353 This can happen if TYPE_MIN_VALUE or TYPE_MAX_VALUE are not the
1354 natural values associated with TYPE_PRECISION and TYPE_UNSIGNED,
1355 and can cause problems later when computing niters of loops. Note
1356 that we don't do the check before converting because we don't want
1357 to reject conversions of negative chrecs to unsigned types. */
1358 if (TREE_CODE (res) == INTEGER_CST
1359 && TREE_CODE (type) == INTEGER_TYPE
1360 && !int_fits_type_p (res, type))
1361 res = chrec_dont_know;
1366 /* Convert CHREC to TYPE, without regard to signed overflows. Returns the new
1367 chrec if something else than what chrec_convert would do happens, NULL_TREE
1371 chrec_convert_aggressive (tree type, tree chrec)
1373 tree inner_type, left, right, lc, rc, rtype;
1375 if (automatically_generated_chrec_p (chrec)
1376 || TREE_CODE (chrec) != POLYNOMIAL_CHREC)
1379 inner_type = TREE_TYPE (chrec);
1380 if (TYPE_PRECISION (type) > TYPE_PRECISION (inner_type))
1383 rtype = POINTER_TYPE_P (type) ? sizetype : type;
1385 left = CHREC_LEFT (chrec);
1386 right = CHREC_RIGHT (chrec);
1387 lc = chrec_convert_aggressive (type, left);
1389 lc = chrec_convert (type, left, NULL);
1390 rc = chrec_convert_aggressive (rtype, right);
1392 rc = chrec_convert (rtype, right, NULL);
1394 return build_polynomial_chrec (CHREC_VARIABLE (chrec), lc, rc);
1397 /* Returns true when CHREC0 == CHREC1. */
1400 eq_evolutions_p (const_tree chrec0, const_tree chrec1)
1402 if (chrec0 == NULL_TREE
1403 || chrec1 == NULL_TREE
1404 || TREE_CODE (chrec0) != TREE_CODE (chrec1))
1407 if (chrec0 == chrec1)
1410 switch (TREE_CODE (chrec0))
1413 return operand_equal_p (chrec0, chrec1, 0);
1415 case POLYNOMIAL_CHREC:
1416 return (CHREC_VARIABLE (chrec0) == CHREC_VARIABLE (chrec1)
1417 && eq_evolutions_p (CHREC_LEFT (chrec0), CHREC_LEFT (chrec1))
1418 && eq_evolutions_p (CHREC_RIGHT (chrec0), CHREC_RIGHT (chrec1)));
1424 /* Returns EV_GROWS if CHREC grows (assuming that it does not overflow),
1425 EV_DECREASES if it decreases, and EV_UNKNOWN if we cannot determine
1426 which of these cases happens. */
1429 scev_direction (const_tree chrec)
1433 if (!evolution_function_is_affine_p (chrec))
1434 return EV_DIR_UNKNOWN;
1436 step = CHREC_RIGHT (chrec);
1437 if (TREE_CODE (step) != INTEGER_CST)
1438 return EV_DIR_UNKNOWN;
1440 if (tree_int_cst_sign_bit (step))
1441 return EV_DIR_DECREASES;
1443 return EV_DIR_GROWS;
1446 /* Iterates over all the components of SCEV, and calls CBCK. */
1449 for_each_scev_op (tree *scev, bool (*cbck) (tree *, void *), void *data)
1451 switch (TREE_CODE_LENGTH (TREE_CODE (*scev)))
1454 for_each_scev_op (&TREE_OPERAND (*scev, 2), cbck, data);
1457 for_each_scev_op (&TREE_OPERAND (*scev, 1), cbck, data);
1460 for_each_scev_op (&TREE_OPERAND (*scev, 0), cbck, data);
1468 /* Returns true when the operation can be part of a linear
1472 operator_is_linear (tree scev)
1474 switch (TREE_CODE (scev))
1477 case POLYNOMIAL_CHREC:
1479 case POINTER_PLUS_EXPR:
1484 case NON_LVALUE_EXPR:
1494 /* Return true when SCEV is a linear expression. Linear expressions
1495 can contain additions, substractions and multiplications.
1496 Multiplications are restricted to constant scaling: "cst * x". */
1499 scev_is_linear_expression (tree scev)
1502 || !operator_is_linear (scev))
1505 if (TREE_CODE (scev) == MULT_EXPR)
1506 return !(tree_contains_chrecs (TREE_OPERAND (scev, 0), NULL)
1507 && tree_contains_chrecs (TREE_OPERAND (scev, 1), NULL));
1509 if (TREE_CODE (scev) == POLYNOMIAL_CHREC
1510 && !evolution_function_is_affine_multivariate_p (scev, CHREC_VARIABLE (scev)))
1513 switch (TREE_CODE_LENGTH (TREE_CODE (scev)))
1516 return scev_is_linear_expression (TREE_OPERAND (scev, 0))
1517 && scev_is_linear_expression (TREE_OPERAND (scev, 1))
1518 && scev_is_linear_expression (TREE_OPERAND (scev, 2));
1521 return scev_is_linear_expression (TREE_OPERAND (scev, 0))
1522 && scev_is_linear_expression (TREE_OPERAND (scev, 1));
1525 return scev_is_linear_expression (TREE_OPERAND (scev, 0));
1535 /* Determines whether the expression CHREC contains only interger consts
1536 in the right parts. */
1539 evolution_function_right_is_integer_cst (const_tree chrec)
1541 if (chrec == NULL_TREE)
1544 switch (TREE_CODE (chrec))
1549 case POLYNOMIAL_CHREC:
1550 return TREE_CODE (CHREC_RIGHT (chrec)) == INTEGER_CST
1551 && (TREE_CODE (CHREC_LEFT (chrec)) != POLYNOMIAL_CHREC
1552 || evolution_function_right_is_integer_cst (CHREC_LEFT (chrec)));
1555 return evolution_function_right_is_integer_cst (TREE_OPERAND (chrec, 0));