1 /* Scalar evolution detector.
2 Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
3 Free Software Foundation, Inc.
4 Contributed by Sebastian Pop <s.pop@laposte.net>
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/>. */
25 This pass analyzes the evolution of scalar variables in loop
26 structures. The algorithm is based on the SSA representation,
27 and on the loop hierarchy tree. This algorithm is not based on
28 the notion of versions of a variable, as it was the case for the
29 previous implementations of the scalar evolution algorithm, but
30 it assumes that each defined name is unique.
32 The notation used in this file is called "chains of recurrences",
33 and has been proposed by Eugene Zima, Robert Van Engelen, and
34 others for describing induction variables in programs. For example
35 "b -> {0, +, 2}_1" means that the scalar variable "b" is equal to 0
36 when entering in the loop_1 and has a step 2 in this loop, in other
37 words "for (b = 0; b < N; b+=2);". Note that the coefficients of
38 this chain of recurrence (or chrec [shrek]) can contain the name of
39 other variables, in which case they are called parametric chrecs.
40 For example, "b -> {a, +, 2}_1" means that the initial value of "b"
41 is the value of "a". In most of the cases these parametric chrecs
42 are fully instantiated before their use because symbolic names can
43 hide some difficult cases such as self-references described later
44 (see the Fibonacci example).
46 A short sketch of the algorithm is:
48 Given a scalar variable to be analyzed, follow the SSA edge to
51 - When the definition is a GIMPLE_ASSIGN: if the right hand side
52 (RHS) of the definition cannot be statically analyzed, the answer
53 of the analyzer is: "don't know".
54 Otherwise, for all the variables that are not yet analyzed in the
55 RHS, try to determine their evolution, and finally try to
56 evaluate the operation of the RHS that gives the evolution
57 function of the analyzed variable.
59 - When the definition is a condition-phi-node: determine the
60 evolution function for all the branches of the phi node, and
61 finally merge these evolutions (see chrec_merge).
63 - When the definition is a loop-phi-node: determine its initial
64 condition, that is the SSA edge defined in an outer loop, and
65 keep it symbolic. Then determine the SSA edges that are defined
66 in the body of the loop. Follow the inner edges until ending on
67 another loop-phi-node of the same analyzed loop. If the reached
68 loop-phi-node is not the starting loop-phi-node, then we keep
69 this definition under a symbolic form. If the reached
70 loop-phi-node is the same as the starting one, then we compute a
71 symbolic stride on the return path. The result is then the
72 symbolic chrec {initial_condition, +, symbolic_stride}_loop.
76 Example 1: Illustration of the basic algorithm.
82 | if (c > 10) exit_loop
85 Suppose that we want to know the number of iterations of the
86 loop_1. The exit_loop is controlled by a COND_EXPR (c > 10). We
87 ask the scalar evolution analyzer two questions: what's the
88 scalar evolution (scev) of "c", and what's the scev of "10". For
89 "10" the answer is "10" since it is a scalar constant. For the
90 scalar variable "c", it follows the SSA edge to its definition,
91 "c = b + 1", and then asks again what's the scev of "b".
92 Following the SSA edge, we end on a loop-phi-node "b = phi (a,
93 c)", where the initial condition is "a", and the inner loop edge
94 is "c". The initial condition is kept under a symbolic form (it
95 may be the case that the copy constant propagation has done its
96 work and we end with the constant "3" as one of the edges of the
97 loop-phi-node). The update edge is followed to the end of the
98 loop, and until reaching again the starting loop-phi-node: b -> c
99 -> b. At this point we have drawn a path from "b" to "b" from
100 which we compute the stride in the loop: in this example it is
101 "+1". The resulting scev for "b" is "b -> {a, +, 1}_1". Now
102 that the scev for "b" is known, it is possible to compute the
103 scev for "c", that is "c -> {a + 1, +, 1}_1". In order to
104 determine the number of iterations in the loop_1, we have to
105 instantiate_parameters (loop_1, {a + 1, +, 1}_1), that gives after some
106 more analysis the scev {4, +, 1}_1, or in other words, this is
107 the function "f (x) = x + 4", where x is the iteration count of
108 the loop_1. Now we have to solve the inequality "x + 4 > 10",
109 and take the smallest iteration number for which the loop is
110 exited: x = 7. This loop runs from x = 0 to x = 7, and in total
111 there are 8 iterations. In terms of loop normalization, we have
112 created a variable that is implicitly defined, "x" or just "_1",
113 and all the other analyzed scalars of the loop are defined in
114 function of this variable:
120 or in terms of a C program:
123 | for (x = 0; x <= 7; x++)
129 Example 2a: Illustration of the algorithm on nested loops.
140 For analyzing the scalar evolution of "a", the algorithm follows
141 the SSA edge into the loop's body: "a -> b". "b" is an inner
142 loop-phi-node, and its analysis as in Example 1, gives:
147 Following the SSA edge for the initial condition, we end on "c = a
148 + 2", and then on the starting loop-phi-node "a". From this point,
149 the loop stride is computed: back on "c = a + 2" we get a "+2" in
150 the loop_1, then on the loop-phi-node "b" we compute the overall
151 effect of the inner loop that is "b = c + 30", and we get a "+30"
152 in the loop_1. That means that the overall stride in loop_1 is
153 equal to "+32", and the result is:
158 Example 2b: Multivariate chains of recurrences.
171 Analyzing the access function of array A with
172 instantiate_parameters (loop_1, "j + k"), we obtain the
173 instantiation and the analysis of the scalar variables "j" and "k"
174 in loop_1. This leads to the scalar evolution {4, +, 1}_1: the end
175 value of loop_2 for "j" is 4, and the evolution of "k" in loop_1 is
176 {0, +, 1}_1. To obtain the evolution function in loop_3 and
177 instantiate the scalar variables up to loop_1, one has to use:
178 instantiate_scev (block_before_loop (loop_1), loop_3, "j + k").
179 The result of this call is {{0, +, 1}_1, +, 1}_2.
181 Example 3: Higher degree polynomials.
195 instantiate_parameters (loop_1, {5, +, a}_1) -> {5, +, 2, +, 1}_1
196 instantiate_parameters (loop_1, {5 + a, +, a}_1) -> {7, +, 3, +, 1}_1
198 Example 4: Lucas, Fibonacci, or mixers in general.
210 The syntax "(1, c)_1" stands for a PEELED_CHREC that has the
211 following semantics: during the first iteration of the loop_1, the
212 variable contains the value 1, and then it contains the value "c".
213 Note that this syntax is close to the syntax of the loop-phi-node:
214 "a -> (1, c)_1" vs. "a = phi (1, c)".
216 The symbolic chrec representation contains all the semantics of the
217 original code. What is more difficult is to use this information.
219 Example 5: Flip-flops, or exchangers.
231 Based on these symbolic chrecs, it is possible to refine this
232 information into the more precise PERIODIC_CHRECs:
237 This transformation is not yet implemented.
241 You can find a more detailed description of the algorithm in:
242 http://icps.u-strasbg.fr/~pop/DEA_03_Pop.pdf
243 http://icps.u-strasbg.fr/~pop/DEA_03_Pop.ps.gz. But note that
244 this is a preliminary report and some of the details of the
245 algorithm have changed. I'm working on a research report that
246 updates the description of the algorithms to reflect the design
247 choices used in this implementation.
249 A set of slides show a high level overview of the algorithm and run
250 an example through the scalar evolution analyzer:
251 http://cri.ensmp.fr/~pop/gcc/mar04/slides.pdf
253 The slides that I have presented at the GCC Summit'04 are available
254 at: http://cri.ensmp.fr/~pop/gcc/20040604/gccsummit-lno-spop.pdf
259 #include "coretypes.h"
263 #include "basic-block.h"
264 #include "tree-pretty-print.h"
265 #include "gimple-pretty-print.h"
266 #include "tree-flow.h"
267 #include "tree-dump.h"
270 #include "tree-chrec.h"
271 #include "tree-scalar-evolution.h"
272 #include "tree-pass.h"
276 static tree analyze_scalar_evolution_1 (struct loop *, tree, tree);
278 /* The cached information about an SSA name VAR, claiming that below
279 basic block INSTANTIATED_BELOW, the value of VAR can be expressed
282 struct GTY(()) scev_info_str {
283 basic_block instantiated_below;
288 /* Counters for the scev database. */
289 static unsigned nb_set_scev = 0;
290 static unsigned nb_get_scev = 0;
292 /* The following trees are unique elements. Thus the comparison of
293 another element to these elements should be done on the pointer to
294 these trees, and not on their value. */
296 /* The SSA_NAMEs that are not yet analyzed are qualified with NULL_TREE. */
297 tree chrec_not_analyzed_yet;
299 /* Reserved to the cases where the analyzer has detected an
300 undecidable property at compile time. */
301 tree chrec_dont_know;
303 /* When the analyzer has detected that a property will never
304 happen, then it qualifies it with chrec_known. */
307 static GTY ((param_is (struct scev_info_str))) htab_t scalar_evolution_info;
310 /* Constructs a new SCEV_INFO_STR structure for VAR and INSTANTIATED_BELOW. */
312 static inline struct scev_info_str *
313 new_scev_info_str (basic_block instantiated_below, tree var)
315 struct scev_info_str *res;
317 res = ggc_alloc_scev_info_str ();
319 res->chrec = chrec_not_analyzed_yet;
320 res->instantiated_below = instantiated_below;
325 /* Computes a hash function for database element ELT. */
328 hash_scev_info (const void *elt)
330 return SSA_NAME_VERSION (((const struct scev_info_str *) elt)->var);
333 /* Compares database elements E1 and E2. */
336 eq_scev_info (const void *e1, const void *e2)
338 const struct scev_info_str *elt1 = (const struct scev_info_str *) e1;
339 const struct scev_info_str *elt2 = (const struct scev_info_str *) e2;
341 return (elt1->var == elt2->var
342 && elt1->instantiated_below == elt2->instantiated_below);
345 /* Deletes database element E. */
348 del_scev_info (void *e)
353 /* Get the scalar evolution of VAR for INSTANTIATED_BELOW basic block.
354 A first query on VAR returns chrec_not_analyzed_yet. */
357 find_var_scev_info (basic_block instantiated_below, tree var)
359 struct scev_info_str *res;
360 struct scev_info_str tmp;
364 tmp.instantiated_below = instantiated_below;
365 slot = htab_find_slot (scalar_evolution_info, &tmp, INSERT);
368 *slot = new_scev_info_str (instantiated_below, var);
369 res = (struct scev_info_str *) *slot;
374 /* Return true when CHREC contains symbolic names defined in
378 chrec_contains_symbols_defined_in_loop (const_tree chrec, unsigned loop_nb)
382 if (chrec == NULL_TREE)
385 if (is_gimple_min_invariant (chrec))
388 if (TREE_CODE (chrec) == SSA_NAME)
391 loop_p def_loop, loop;
393 if (SSA_NAME_IS_DEFAULT_DEF (chrec))
396 def = SSA_NAME_DEF_STMT (chrec);
397 def_loop = loop_containing_stmt (def);
398 loop = get_loop (loop_nb);
400 if (def_loop == NULL)
403 if (loop == def_loop || flow_loop_nested_p (loop, def_loop))
409 n = TREE_OPERAND_LENGTH (chrec);
410 for (i = 0; i < n; i++)
411 if (chrec_contains_symbols_defined_in_loop (TREE_OPERAND (chrec, i),
417 /* Return true when PHI is a loop-phi-node. */
420 loop_phi_node_p (gimple phi)
422 /* The implementation of this function is based on the following
423 property: "all the loop-phi-nodes of a loop are contained in the
424 loop's header basic block". */
426 return loop_containing_stmt (phi)->header == gimple_bb (phi);
429 /* Compute the scalar evolution for EVOLUTION_FN after crossing LOOP.
430 In general, in the case of multivariate evolutions we want to get
431 the evolution in different loops. LOOP specifies the level for
432 which to get the evolution.
436 | for (j = 0; j < 100; j++)
438 | for (k = 0; k < 100; k++)
440 | i = k + j; - Here the value of i is a function of j, k.
442 | ... = i - Here the value of i is a function of j.
444 | ... = i - Here the value of i is a scalar.
450 | i_1 = phi (i_0, i_2)
454 This loop has the same effect as:
455 LOOP_1 has the same effect as:
459 The overall effect of the loop, "i_0 + 20" in the previous example,
460 is obtained by passing in the parameters: LOOP = 1,
461 EVOLUTION_FN = {i_0, +, 2}_1.
465 compute_overall_effect_of_inner_loop (struct loop *loop, tree evolution_fn)
469 if (evolution_fn == chrec_dont_know)
470 return chrec_dont_know;
472 else if (TREE_CODE (evolution_fn) == POLYNOMIAL_CHREC)
474 struct loop *inner_loop = get_chrec_loop (evolution_fn);
476 if (inner_loop == loop
477 || flow_loop_nested_p (loop, inner_loop))
479 tree nb_iter = number_of_latch_executions (inner_loop);
481 if (nb_iter == chrec_dont_know)
482 return chrec_dont_know;
487 /* evolution_fn is the evolution function in LOOP. Get
488 its value in the nb_iter-th iteration. */
489 res = chrec_apply (inner_loop->num, evolution_fn, nb_iter);
491 if (chrec_contains_symbols_defined_in_loop (res, loop->num))
492 res = instantiate_parameters (loop, res);
494 /* Continue the computation until ending on a parent of LOOP. */
495 return compute_overall_effect_of_inner_loop (loop, res);
502 /* If the evolution function is an invariant, there is nothing to do. */
503 else if (no_evolution_in_loop_p (evolution_fn, loop->num, &val) && val)
507 return chrec_dont_know;
510 /* Determine whether the CHREC is always positive/negative. If the expression
511 cannot be statically analyzed, return false, otherwise set the answer into
515 chrec_is_positive (tree chrec, bool *value)
517 bool value0, value1, value2;
518 tree end_value, nb_iter;
520 switch (TREE_CODE (chrec))
522 case POLYNOMIAL_CHREC:
523 if (!chrec_is_positive (CHREC_LEFT (chrec), &value0)
524 || !chrec_is_positive (CHREC_RIGHT (chrec), &value1))
527 /* FIXME -- overflows. */
528 if (value0 == value1)
534 /* Otherwise the chrec is under the form: "{-197, +, 2}_1",
535 and the proof consists in showing that the sign never
536 changes during the execution of the loop, from 0 to
537 loop->nb_iterations. */
538 if (!evolution_function_is_affine_p (chrec))
541 nb_iter = number_of_latch_executions (get_chrec_loop (chrec));
542 if (chrec_contains_undetermined (nb_iter))
546 /* TODO -- If the test is after the exit, we may decrease the number of
547 iterations by one. */
549 nb_iter = chrec_fold_minus (type, nb_iter, build_int_cst (type, 1));
552 end_value = chrec_apply (CHREC_VARIABLE (chrec), chrec, nb_iter);
554 if (!chrec_is_positive (end_value, &value2))
558 return value0 == value1;
561 *value = (tree_int_cst_sgn (chrec) == 1);
569 /* Associate CHREC to SCALAR. */
572 set_scalar_evolution (basic_block instantiated_below, tree scalar, tree chrec)
576 if (TREE_CODE (scalar) != SSA_NAME)
579 scalar_info = find_var_scev_info (instantiated_below, scalar);
583 if (dump_flags & TDF_DETAILS)
585 fprintf (dump_file, "(set_scalar_evolution \n");
586 fprintf (dump_file, " instantiated_below = %d \n",
587 instantiated_below->index);
588 fprintf (dump_file, " (scalar = ");
589 print_generic_expr (dump_file, scalar, 0);
590 fprintf (dump_file, ")\n (scalar_evolution = ");
591 print_generic_expr (dump_file, chrec, 0);
592 fprintf (dump_file, "))\n");
594 if (dump_flags & TDF_STATS)
598 *scalar_info = chrec;
601 /* Retrieve the chrec associated to SCALAR instantiated below
602 INSTANTIATED_BELOW block. */
605 get_scalar_evolution (basic_block instantiated_below, tree scalar)
611 if (dump_flags & TDF_DETAILS)
613 fprintf (dump_file, "(get_scalar_evolution \n");
614 fprintf (dump_file, " (scalar = ");
615 print_generic_expr (dump_file, scalar, 0);
616 fprintf (dump_file, ")\n");
618 if (dump_flags & TDF_STATS)
622 switch (TREE_CODE (scalar))
625 res = *find_var_scev_info (instantiated_below, scalar);
635 res = chrec_not_analyzed_yet;
639 if (dump_file && (dump_flags & TDF_DETAILS))
641 fprintf (dump_file, " (scalar_evolution = ");
642 print_generic_expr (dump_file, res, 0);
643 fprintf (dump_file, "))\n");
649 /* Helper function for add_to_evolution. Returns the evolution
650 function for an assignment of the form "a = b + c", where "a" and
651 "b" are on the strongly connected component. CHREC_BEFORE is the
652 information that we already have collected up to this point.
653 TO_ADD is the evolution of "c".
655 When CHREC_BEFORE has an evolution part in LOOP_NB, add to this
656 evolution the expression TO_ADD, otherwise construct an evolution
657 part for this loop. */
660 add_to_evolution_1 (unsigned loop_nb, tree chrec_before, tree to_add,
663 tree type, left, right;
664 struct loop *loop = get_loop (loop_nb), *chloop;
666 switch (TREE_CODE (chrec_before))
668 case POLYNOMIAL_CHREC:
669 chloop = get_chrec_loop (chrec_before);
671 || flow_loop_nested_p (chloop, loop))
675 type = chrec_type (chrec_before);
677 /* When there is no evolution part in this loop, build it. */
682 right = SCALAR_FLOAT_TYPE_P (type)
683 ? build_real (type, dconst0)
684 : build_int_cst (type, 0);
688 var = CHREC_VARIABLE (chrec_before);
689 left = CHREC_LEFT (chrec_before);
690 right = CHREC_RIGHT (chrec_before);
693 to_add = chrec_convert (type, to_add, at_stmt);
694 right = chrec_convert_rhs (type, right, at_stmt);
695 right = chrec_fold_plus (chrec_type (right), right, to_add);
696 return build_polynomial_chrec (var, left, right);
700 gcc_assert (flow_loop_nested_p (loop, chloop));
702 /* Search the evolution in LOOP_NB. */
703 left = add_to_evolution_1 (loop_nb, CHREC_LEFT (chrec_before),
705 right = CHREC_RIGHT (chrec_before);
706 right = chrec_convert_rhs (chrec_type (left), right, at_stmt);
707 return build_polynomial_chrec (CHREC_VARIABLE (chrec_before),
712 /* These nodes do not depend on a loop. */
713 if (chrec_before == chrec_dont_know)
714 return chrec_dont_know;
717 right = chrec_convert_rhs (chrec_type (left), to_add, at_stmt);
718 return build_polynomial_chrec (loop_nb, left, right);
722 /* Add TO_ADD to the evolution part of CHREC_BEFORE in the dimension
725 Description (provided for completeness, for those who read code in
726 a plane, and for my poor 62 bytes brain that would have forgotten
727 all this in the next two or three months):
729 The algorithm of translation of programs from the SSA representation
730 into the chrecs syntax is based on a pattern matching. After having
731 reconstructed the overall tree expression for a loop, there are only
732 two cases that can arise:
734 1. a = loop-phi (init, a + expr)
735 2. a = loop-phi (init, expr)
737 where EXPR is either a scalar constant with respect to the analyzed
738 loop (this is a degree 0 polynomial), or an expression containing
739 other loop-phi definitions (these are higher degree polynomials).
746 | a = phi (init, a + 5)
753 | a = phi (inita, 2 * b + 3)
754 | b = phi (initb, b + 1)
757 For the first case, the semantics of the SSA representation is:
759 | a (x) = init + \sum_{j = 0}^{x - 1} expr (j)
761 that is, there is a loop index "x" that determines the scalar value
762 of the variable during the loop execution. During the first
763 iteration, the value is that of the initial condition INIT, while
764 during the subsequent iterations, it is the sum of the initial
765 condition with the sum of all the values of EXPR from the initial
766 iteration to the before last considered iteration.
768 For the second case, the semantics of the SSA program is:
770 | a (x) = init, if x = 0;
771 | expr (x - 1), otherwise.
773 The second case corresponds to the PEELED_CHREC, whose syntax is
774 close to the syntax of a loop-phi-node:
776 | phi (init, expr) vs. (init, expr)_x
778 The proof of the translation algorithm for the first case is a
779 proof by structural induction based on the degree of EXPR.
782 When EXPR is a constant with respect to the analyzed loop, or in
783 other words when EXPR is a polynomial of degree 0, the evolution of
784 the variable A in the loop is an affine function with an initial
785 condition INIT, and a step EXPR. In order to show this, we start
786 from the semantics of the SSA representation:
788 f (x) = init + \sum_{j = 0}^{x - 1} expr (j)
790 and since "expr (j)" is a constant with respect to "j",
792 f (x) = init + x * expr
794 Finally, based on the semantics of the pure sum chrecs, by
795 identification we get the corresponding chrecs syntax:
797 f (x) = init * \binom{x}{0} + expr * \binom{x}{1}
798 f (x) -> {init, +, expr}_x
801 Suppose that EXPR is a polynomial of degree N with respect to the
802 analyzed loop_x for which we have already determined that it is
803 written under the chrecs syntax:
805 | expr (x) -> {b_0, +, b_1, +, ..., +, b_{n-1}} (x)
807 We start from the semantics of the SSA program:
809 | f (x) = init + \sum_{j = 0}^{x - 1} expr (j)
811 | f (x) = init + \sum_{j = 0}^{x - 1}
812 | (b_0 * \binom{j}{0} + ... + b_{n-1} * \binom{j}{n-1})
814 | f (x) = init + \sum_{j = 0}^{x - 1}
815 | \sum_{k = 0}^{n - 1} (b_k * \binom{j}{k})
817 | f (x) = init + \sum_{k = 0}^{n - 1}
818 | (b_k * \sum_{j = 0}^{x - 1} \binom{j}{k})
820 | f (x) = init + \sum_{k = 0}^{n - 1}
821 | (b_k * \binom{x}{k + 1})
823 | f (x) = init + b_0 * \binom{x}{1} + ...
824 | + b_{n-1} * \binom{x}{n}
826 | f (x) = init * \binom{x}{0} + b_0 * \binom{x}{1} + ...
827 | + b_{n-1} * \binom{x}{n}
830 And finally from the definition of the chrecs syntax, we identify:
831 | f (x) -> {init, +, b_0, +, ..., +, b_{n-1}}_x
833 This shows the mechanism that stands behind the add_to_evolution
834 function. An important point is that the use of symbolic
835 parameters avoids the need of an analysis schedule.
842 | a = phi (inita, a + 2 + b)
843 | b = phi (initb, b + 1)
846 When analyzing "a", the algorithm keeps "b" symbolically:
848 | a -> {inita, +, 2 + b}_1
850 Then, after instantiation, the analyzer ends on the evolution:
852 | a -> {inita, +, 2 + initb, +, 1}_1
857 add_to_evolution (unsigned loop_nb, tree chrec_before, enum tree_code code,
858 tree to_add, gimple at_stmt)
860 tree type = chrec_type (to_add);
861 tree res = NULL_TREE;
863 if (to_add == NULL_TREE)
866 /* TO_ADD is either a scalar, or a parameter. TO_ADD is not
867 instantiated at this point. */
868 if (TREE_CODE (to_add) == POLYNOMIAL_CHREC)
869 /* This should not happen. */
870 return chrec_dont_know;
872 if (dump_file && (dump_flags & TDF_DETAILS))
874 fprintf (dump_file, "(add_to_evolution \n");
875 fprintf (dump_file, " (loop_nb = %d)\n", loop_nb);
876 fprintf (dump_file, " (chrec_before = ");
877 print_generic_expr (dump_file, chrec_before, 0);
878 fprintf (dump_file, ")\n (to_add = ");
879 print_generic_expr (dump_file, to_add, 0);
880 fprintf (dump_file, ")\n");
883 if (code == MINUS_EXPR)
884 to_add = chrec_fold_multiply (type, to_add, SCALAR_FLOAT_TYPE_P (type)
885 ? build_real (type, dconstm1)
886 : build_int_cst_type (type, -1));
888 res = add_to_evolution_1 (loop_nb, chrec_before, to_add, at_stmt);
890 if (dump_file && (dump_flags & TDF_DETAILS))
892 fprintf (dump_file, " (res = ");
893 print_generic_expr (dump_file, res, 0);
894 fprintf (dump_file, "))\n");
902 /* This section selects the loops that will be good candidates for the
903 scalar evolution analysis. For the moment, greedily select all the
904 loop nests we could analyze. */
906 /* For a loop with a single exit edge, return the COND_EXPR that
907 guards the exit edge. If the expression is too difficult to
908 analyze, then give up. */
911 get_loop_exit_condition (const struct loop *loop)
914 edge exit_edge = single_exit (loop);
916 if (dump_file && (dump_flags & TDF_DETAILS))
917 fprintf (dump_file, "(get_loop_exit_condition \n ");
923 stmt = last_stmt (exit_edge->src);
924 if (gimple_code (stmt) == GIMPLE_COND)
928 if (dump_file && (dump_flags & TDF_DETAILS))
930 print_gimple_stmt (dump_file, res, 0, 0);
931 fprintf (dump_file, ")\n");
937 /* Recursively determine and enqueue the exit conditions for a loop. */
940 get_exit_conditions_rec (struct loop *loop,
941 VEC(gimple,heap) **exit_conditions)
946 /* Recurse on the inner loops, then on the next (sibling) loops. */
947 get_exit_conditions_rec (loop->inner, exit_conditions);
948 get_exit_conditions_rec (loop->next, exit_conditions);
950 if (single_exit (loop))
952 gimple loop_condition = get_loop_exit_condition (loop);
955 VEC_safe_push (gimple, heap, *exit_conditions, loop_condition);
959 /* Select the candidate loop nests for the analysis. This function
960 initializes the EXIT_CONDITIONS array. */
963 select_loops_exit_conditions (VEC(gimple,heap) **exit_conditions)
965 struct loop *function_body = current_loops->tree_root;
967 get_exit_conditions_rec (function_body->inner, exit_conditions);
971 /* Depth first search algorithm. */
973 typedef enum t_bool {
980 static t_bool follow_ssa_edge (struct loop *loop, gimple, gimple, tree *, int);
982 /* Follow the ssa edge into the binary expression RHS0 CODE RHS1.
983 Return true if the strongly connected component has been found. */
986 follow_ssa_edge_binary (struct loop *loop, gimple at_stmt,
987 tree type, tree rhs0, enum tree_code code, tree rhs1,
988 gimple halting_phi, tree *evolution_of_loop, int limit)
990 t_bool res = t_false;
995 case POINTER_PLUS_EXPR:
997 if (TREE_CODE (rhs0) == SSA_NAME)
999 if (TREE_CODE (rhs1) == SSA_NAME)
1001 /* Match an assignment under the form:
1004 /* We want only assignments of form "name + name" contribute to
1005 LIMIT, as the other cases do not necessarily contribute to
1006 the complexity of the expression. */
1009 evol = *evolution_of_loop;
1010 res = follow_ssa_edge
1011 (loop, SSA_NAME_DEF_STMT (rhs0), halting_phi, &evol, limit);
1014 *evolution_of_loop = add_to_evolution
1016 chrec_convert (type, evol, at_stmt),
1017 code, rhs1, at_stmt);
1019 else if (res == t_false)
1021 res = follow_ssa_edge
1022 (loop, SSA_NAME_DEF_STMT (rhs1), halting_phi,
1023 evolution_of_loop, limit);
1026 *evolution_of_loop = add_to_evolution
1028 chrec_convert (type, *evolution_of_loop, at_stmt),
1029 code, rhs0, at_stmt);
1031 else if (res == t_dont_know)
1032 *evolution_of_loop = chrec_dont_know;
1035 else if (res == t_dont_know)
1036 *evolution_of_loop = chrec_dont_know;
1041 /* Match an assignment under the form:
1043 res = follow_ssa_edge
1044 (loop, SSA_NAME_DEF_STMT (rhs0), halting_phi,
1045 evolution_of_loop, limit);
1047 *evolution_of_loop = add_to_evolution
1048 (loop->num, chrec_convert (type, *evolution_of_loop,
1050 code, rhs1, at_stmt);
1052 else if (res == t_dont_know)
1053 *evolution_of_loop = chrec_dont_know;
1057 else if (TREE_CODE (rhs1) == SSA_NAME)
1059 /* Match an assignment under the form:
1061 res = follow_ssa_edge
1062 (loop, SSA_NAME_DEF_STMT (rhs1), halting_phi,
1063 evolution_of_loop, limit);
1065 *evolution_of_loop = add_to_evolution
1066 (loop->num, chrec_convert (type, *evolution_of_loop,
1068 code, rhs0, at_stmt);
1070 else if (res == t_dont_know)
1071 *evolution_of_loop = chrec_dont_know;
1075 /* Otherwise, match an assignment under the form:
1077 /* And there is nothing to do. */
1082 /* This case is under the form "opnd0 = rhs0 - rhs1". */
1083 if (TREE_CODE (rhs0) == SSA_NAME)
1085 /* Match an assignment under the form:
1088 /* We want only assignments of form "name - name" contribute to
1089 LIMIT, as the other cases do not necessarily contribute to
1090 the complexity of the expression. */
1091 if (TREE_CODE (rhs1) == SSA_NAME)
1094 res = follow_ssa_edge (loop, SSA_NAME_DEF_STMT (rhs0), halting_phi,
1095 evolution_of_loop, limit);
1097 *evolution_of_loop = add_to_evolution
1098 (loop->num, chrec_convert (type, *evolution_of_loop, at_stmt),
1099 MINUS_EXPR, rhs1, at_stmt);
1101 else if (res == t_dont_know)
1102 *evolution_of_loop = chrec_dont_know;
1105 /* Otherwise, match an assignment under the form:
1107 /* And there is nothing to do. */
1118 /* Follow the ssa edge into the expression EXPR.
1119 Return true if the strongly connected component has been found. */
1122 follow_ssa_edge_expr (struct loop *loop, gimple at_stmt, tree expr,
1123 gimple halting_phi, tree *evolution_of_loop, int limit)
1125 enum tree_code code = TREE_CODE (expr);
1126 tree type = TREE_TYPE (expr), rhs0, rhs1;
1129 /* The EXPR is one of the following cases:
1133 - a POINTER_PLUS_EXPR,
1136 - other cases are not yet handled. */
1141 /* This assignment is under the form "a_1 = (cast) rhs. */
1142 res = follow_ssa_edge_expr (loop, at_stmt, TREE_OPERAND (expr, 0),
1143 halting_phi, evolution_of_loop, limit);
1144 *evolution_of_loop = chrec_convert (type, *evolution_of_loop, at_stmt);
1148 /* This assignment is under the form "a_1 = 7". */
1153 /* This assignment is under the form: "a_1 = b_2". */
1154 res = follow_ssa_edge
1155 (loop, SSA_NAME_DEF_STMT (expr), halting_phi, evolution_of_loop, limit);
1158 case POINTER_PLUS_EXPR:
1161 /* This case is under the form "rhs0 +- rhs1". */
1162 rhs0 = TREE_OPERAND (expr, 0);
1163 rhs1 = TREE_OPERAND (expr, 1);
1164 type = TREE_TYPE (rhs0);
1165 STRIP_USELESS_TYPE_CONVERSION (rhs0);
1166 STRIP_USELESS_TYPE_CONVERSION (rhs1);
1167 res = follow_ssa_edge_binary (loop, at_stmt, type, rhs0, code, rhs1,
1168 halting_phi, evolution_of_loop, limit);
1172 /* Handle &MEM[ptr + CST] which is equivalent to POINTER_PLUS_EXPR. */
1173 if (TREE_CODE (TREE_OPERAND (expr, 0)) == MEM_REF)
1175 expr = TREE_OPERAND (expr, 0);
1176 rhs0 = TREE_OPERAND (expr, 0);
1177 rhs1 = TREE_OPERAND (expr, 1);
1178 type = TREE_TYPE (rhs0);
1179 STRIP_USELESS_TYPE_CONVERSION (rhs0);
1180 STRIP_USELESS_TYPE_CONVERSION (rhs1);
1181 res = follow_ssa_edge_binary (loop, at_stmt, type,
1182 rhs0, POINTER_PLUS_EXPR, rhs1,
1183 halting_phi, evolution_of_loop, limit);
1190 /* This assignment is of the form: "a_1 = ASSERT_EXPR <a_2, ...>"
1191 It must be handled as a copy assignment of the form a_1 = a_2. */
1192 rhs0 = ASSERT_EXPR_VAR (expr);
1193 if (TREE_CODE (rhs0) == SSA_NAME)
1194 res = follow_ssa_edge (loop, SSA_NAME_DEF_STMT (rhs0),
1195 halting_phi, evolution_of_loop, limit);
1208 /* Follow the ssa edge into the right hand side of an assignment STMT.
1209 Return true if the strongly connected component has been found. */
1212 follow_ssa_edge_in_rhs (struct loop *loop, gimple stmt,
1213 gimple halting_phi, tree *evolution_of_loop, int limit)
1215 enum tree_code code = gimple_assign_rhs_code (stmt);
1216 tree type = gimple_expr_type (stmt), rhs1, rhs2;
1222 /* This assignment is under the form "a_1 = (cast) rhs. */
1223 res = follow_ssa_edge_expr (loop, stmt, gimple_assign_rhs1 (stmt),
1224 halting_phi, evolution_of_loop, limit);
1225 *evolution_of_loop = chrec_convert (type, *evolution_of_loop, stmt);
1228 case POINTER_PLUS_EXPR:
1231 rhs1 = gimple_assign_rhs1 (stmt);
1232 rhs2 = gimple_assign_rhs2 (stmt);
1233 type = TREE_TYPE (rhs1);
1234 res = follow_ssa_edge_binary (loop, stmt, type, rhs1, code, rhs2,
1235 halting_phi, evolution_of_loop, limit);
1239 if (get_gimple_rhs_class (code) == GIMPLE_SINGLE_RHS)
1240 res = follow_ssa_edge_expr (loop, stmt, gimple_assign_rhs1 (stmt),
1241 halting_phi, evolution_of_loop, limit);
1250 /* Checks whether the I-th argument of a PHI comes from a backedge. */
1253 backedge_phi_arg_p (gimple phi, int i)
1255 const_edge e = gimple_phi_arg_edge (phi, i);
1257 /* We would in fact like to test EDGE_DFS_BACK here, but we do not care
1258 about updating it anywhere, and this should work as well most of the
1260 if (e->flags & EDGE_IRREDUCIBLE_LOOP)
1266 /* Helper function for one branch of the condition-phi-node. Return
1267 true if the strongly connected component has been found following
1270 static inline t_bool
1271 follow_ssa_edge_in_condition_phi_branch (int i,
1273 gimple condition_phi,
1275 tree *evolution_of_branch,
1276 tree init_cond, int limit)
1278 tree branch = PHI_ARG_DEF (condition_phi, i);
1279 *evolution_of_branch = chrec_dont_know;
1281 /* Do not follow back edges (they must belong to an irreducible loop, which
1282 we really do not want to worry about). */
1283 if (backedge_phi_arg_p (condition_phi, i))
1286 if (TREE_CODE (branch) == SSA_NAME)
1288 *evolution_of_branch = init_cond;
1289 return follow_ssa_edge (loop, SSA_NAME_DEF_STMT (branch), halting_phi,
1290 evolution_of_branch, limit);
1293 /* This case occurs when one of the condition branches sets
1294 the variable to a constant: i.e. a phi-node like
1295 "a_2 = PHI <a_7(5), 2(6)>;".
1297 FIXME: This case have to be refined correctly:
1298 in some cases it is possible to say something better than
1299 chrec_dont_know, for example using a wrap-around notation. */
1303 /* This function merges the branches of a condition-phi-node in a
1307 follow_ssa_edge_in_condition_phi (struct loop *loop,
1308 gimple condition_phi,
1310 tree *evolution_of_loop, int limit)
1313 tree init = *evolution_of_loop;
1314 tree evolution_of_branch;
1315 t_bool res = follow_ssa_edge_in_condition_phi_branch (0, loop, condition_phi,
1317 &evolution_of_branch,
1319 if (res == t_false || res == t_dont_know)
1322 *evolution_of_loop = evolution_of_branch;
1324 n = gimple_phi_num_args (condition_phi);
1325 for (i = 1; i < n; i++)
1327 /* Quickly give up when the evolution of one of the branches is
1329 if (*evolution_of_loop == chrec_dont_know)
1332 /* Increase the limit by the PHI argument number to avoid exponential
1333 time and memory complexity. */
1334 res = follow_ssa_edge_in_condition_phi_branch (i, loop, condition_phi,
1336 &evolution_of_branch,
1338 if (res == t_false || res == t_dont_know)
1341 *evolution_of_loop = chrec_merge (*evolution_of_loop,
1342 evolution_of_branch);
1348 /* Follow an SSA edge in an inner loop. It computes the overall
1349 effect of the loop, and following the symbolic initial conditions,
1350 it follows the edges in the parent loop. The inner loop is
1351 considered as a single statement. */
1354 follow_ssa_edge_inner_loop_phi (struct loop *outer_loop,
1355 gimple loop_phi_node,
1357 tree *evolution_of_loop, int limit)
1359 struct loop *loop = loop_containing_stmt (loop_phi_node);
1360 tree ev = analyze_scalar_evolution (loop, PHI_RESULT (loop_phi_node));
1362 /* Sometimes, the inner loop is too difficult to analyze, and the
1363 result of the analysis is a symbolic parameter. */
1364 if (ev == PHI_RESULT (loop_phi_node))
1366 t_bool res = t_false;
1367 int i, n = gimple_phi_num_args (loop_phi_node);
1369 for (i = 0; i < n; i++)
1371 tree arg = PHI_ARG_DEF (loop_phi_node, i);
1374 /* Follow the edges that exit the inner loop. */
1375 bb = gimple_phi_arg_edge (loop_phi_node, i)->src;
1376 if (!flow_bb_inside_loop_p (loop, bb))
1377 res = follow_ssa_edge_expr (outer_loop, loop_phi_node,
1379 evolution_of_loop, limit);
1384 /* If the path crosses this loop-phi, give up. */
1386 *evolution_of_loop = chrec_dont_know;
1391 /* Otherwise, compute the overall effect of the inner loop. */
1392 ev = compute_overall_effect_of_inner_loop (loop, ev);
1393 return follow_ssa_edge_expr (outer_loop, loop_phi_node, ev, halting_phi,
1394 evolution_of_loop, limit);
1397 /* Follow an SSA edge from a loop-phi-node to itself, constructing a
1398 path that is analyzed on the return walk. */
1401 follow_ssa_edge (struct loop *loop, gimple def, gimple halting_phi,
1402 tree *evolution_of_loop, int limit)
1404 struct loop *def_loop;
1406 if (gimple_nop_p (def))
1409 /* Give up if the path is longer than the MAX that we allow. */
1410 if (limit > PARAM_VALUE (PARAM_SCEV_MAX_EXPR_SIZE))
1413 def_loop = loop_containing_stmt (def);
1415 switch (gimple_code (def))
1418 if (!loop_phi_node_p (def))
1419 /* DEF is a condition-phi-node. Follow the branches, and
1420 record their evolutions. Finally, merge the collected
1421 information and set the approximation to the main
1423 return follow_ssa_edge_in_condition_phi
1424 (loop, def, halting_phi, evolution_of_loop, limit);
1426 /* When the analyzed phi is the halting_phi, the
1427 depth-first search is over: we have found a path from
1428 the halting_phi to itself in the loop. */
1429 if (def == halting_phi)
1432 /* Otherwise, the evolution of the HALTING_PHI depends
1433 on the evolution of another loop-phi-node, i.e. the
1434 evolution function is a higher degree polynomial. */
1435 if (def_loop == loop)
1439 if (flow_loop_nested_p (loop, def_loop))
1440 return follow_ssa_edge_inner_loop_phi
1441 (loop, def, halting_phi, evolution_of_loop, limit + 1);
1447 return follow_ssa_edge_in_rhs (loop, def, halting_phi,
1448 evolution_of_loop, limit);
1451 /* At this level of abstraction, the program is just a set
1452 of GIMPLE_ASSIGNs and PHI_NODEs. In principle there is no
1453 other node to be handled. */
1460 /* Given a LOOP_PHI_NODE, this function determines the evolution
1461 function from LOOP_PHI_NODE to LOOP_PHI_NODE in the loop. */
1464 analyze_evolution_in_loop (gimple loop_phi_node,
1467 int i, n = gimple_phi_num_args (loop_phi_node);
1468 tree evolution_function = chrec_not_analyzed_yet;
1469 struct loop *loop = loop_containing_stmt (loop_phi_node);
1472 if (dump_file && (dump_flags & TDF_DETAILS))
1474 fprintf (dump_file, "(analyze_evolution_in_loop \n");
1475 fprintf (dump_file, " (loop_phi_node = ");
1476 print_gimple_stmt (dump_file, loop_phi_node, 0, 0);
1477 fprintf (dump_file, ")\n");
1480 for (i = 0; i < n; i++)
1482 tree arg = PHI_ARG_DEF (loop_phi_node, i);
1487 /* Select the edges that enter the loop body. */
1488 bb = gimple_phi_arg_edge (loop_phi_node, i)->src;
1489 if (!flow_bb_inside_loop_p (loop, bb))
1492 if (TREE_CODE (arg) == SSA_NAME)
1496 ssa_chain = SSA_NAME_DEF_STMT (arg);
1498 /* Pass in the initial condition to the follow edge function. */
1500 res = follow_ssa_edge (loop, ssa_chain, loop_phi_node, &ev_fn, 0);
1502 /* If ev_fn has no evolution in the inner loop, and the
1503 init_cond is not equal to ev_fn, then we have an
1504 ambiguity between two possible values, as we cannot know
1505 the number of iterations at this point. */
1506 if (TREE_CODE (ev_fn) != POLYNOMIAL_CHREC
1507 && no_evolution_in_loop_p (ev_fn, loop->num, &val) && val
1508 && !operand_equal_p (init_cond, ev_fn, 0))
1509 ev_fn = chrec_dont_know;
1514 /* When it is impossible to go back on the same
1515 loop_phi_node by following the ssa edges, the
1516 evolution is represented by a peeled chrec, i.e. the
1517 first iteration, EV_FN has the value INIT_COND, then
1518 all the other iterations it has the value of ARG.
1519 For the moment, PEELED_CHREC nodes are not built. */
1521 ev_fn = chrec_dont_know;
1523 /* When there are multiple back edges of the loop (which in fact never
1524 happens currently, but nevertheless), merge their evolutions. */
1525 evolution_function = chrec_merge (evolution_function, ev_fn);
1528 if (dump_file && (dump_flags & TDF_DETAILS))
1530 fprintf (dump_file, " (evolution_function = ");
1531 print_generic_expr (dump_file, evolution_function, 0);
1532 fprintf (dump_file, "))\n");
1535 return evolution_function;
1538 /* Given a loop-phi-node, return the initial conditions of the
1539 variable on entry of the loop. When the CCP has propagated
1540 constants into the loop-phi-node, the initial condition is
1541 instantiated, otherwise the initial condition is kept symbolic.
1542 This analyzer does not analyze the evolution outside the current
1543 loop, and leaves this task to the on-demand tree reconstructor. */
1546 analyze_initial_condition (gimple loop_phi_node)
1549 tree init_cond = chrec_not_analyzed_yet;
1550 struct loop *loop = loop_containing_stmt (loop_phi_node);
1552 if (dump_file && (dump_flags & TDF_DETAILS))
1554 fprintf (dump_file, "(analyze_initial_condition \n");
1555 fprintf (dump_file, " (loop_phi_node = \n");
1556 print_gimple_stmt (dump_file, loop_phi_node, 0, 0);
1557 fprintf (dump_file, ")\n");
1560 n = gimple_phi_num_args (loop_phi_node);
1561 for (i = 0; i < n; i++)
1563 tree branch = PHI_ARG_DEF (loop_phi_node, i);
1564 basic_block bb = gimple_phi_arg_edge (loop_phi_node, i)->src;
1566 /* When the branch is oriented to the loop's body, it does
1567 not contribute to the initial condition. */
1568 if (flow_bb_inside_loop_p (loop, bb))
1571 if (init_cond == chrec_not_analyzed_yet)
1577 if (TREE_CODE (branch) == SSA_NAME)
1579 init_cond = chrec_dont_know;
1583 init_cond = chrec_merge (init_cond, branch);
1586 /* Ooops -- a loop without an entry??? */
1587 if (init_cond == chrec_not_analyzed_yet)
1588 init_cond = chrec_dont_know;
1590 /* During early loop unrolling we do not have fully constant propagated IL.
1591 Handle degenerate PHIs here to not miss important unrollings. */
1592 if (TREE_CODE (init_cond) == SSA_NAME)
1594 gimple def = SSA_NAME_DEF_STMT (init_cond);
1596 if (gimple_code (def) == GIMPLE_PHI
1597 && (res = degenerate_phi_result (def)) != NULL_TREE
1598 /* Only allow invariants here, otherwise we may break
1599 loop-closed SSA form. */
1600 && is_gimple_min_invariant (res))
1604 if (dump_file && (dump_flags & TDF_DETAILS))
1606 fprintf (dump_file, " (init_cond = ");
1607 print_generic_expr (dump_file, init_cond, 0);
1608 fprintf (dump_file, "))\n");
1614 /* Analyze the scalar evolution for LOOP_PHI_NODE. */
1617 interpret_loop_phi (struct loop *loop, gimple loop_phi_node)
1620 struct loop *phi_loop = loop_containing_stmt (loop_phi_node);
1623 if (phi_loop != loop)
1625 struct loop *subloop;
1626 tree evolution_fn = analyze_scalar_evolution
1627 (phi_loop, PHI_RESULT (loop_phi_node));
1629 /* Dive one level deeper. */
1630 subloop = superloop_at_depth (phi_loop, loop_depth (loop) + 1);
1632 /* Interpret the subloop. */
1633 res = compute_overall_effect_of_inner_loop (subloop, evolution_fn);
1637 /* Otherwise really interpret the loop phi. */
1638 init_cond = analyze_initial_condition (loop_phi_node);
1639 res = analyze_evolution_in_loop (loop_phi_node, init_cond);
1641 /* Verify we maintained the correct initial condition throughout
1642 possible conversions in the SSA chain. */
1643 if (res != chrec_dont_know)
1645 tree new_init = res;
1646 if (CONVERT_EXPR_P (res)
1647 && TREE_CODE (TREE_OPERAND (res, 0)) == POLYNOMIAL_CHREC)
1648 new_init = fold_convert (TREE_TYPE (res),
1649 CHREC_LEFT (TREE_OPERAND (res, 0)));
1650 else if (TREE_CODE (res) == POLYNOMIAL_CHREC)
1651 new_init = CHREC_LEFT (res);
1652 STRIP_USELESS_TYPE_CONVERSION (new_init);
1653 gcc_assert (TREE_CODE (new_init) != POLYNOMIAL_CHREC);
1654 if (!operand_equal_p (init_cond, new_init, 0))
1655 return chrec_dont_know;
1661 /* This function merges the branches of a condition-phi-node,
1662 contained in the outermost loop, and whose arguments are already
1666 interpret_condition_phi (struct loop *loop, gimple condition_phi)
1668 int i, n = gimple_phi_num_args (condition_phi);
1669 tree res = chrec_not_analyzed_yet;
1671 for (i = 0; i < n; i++)
1675 if (backedge_phi_arg_p (condition_phi, i))
1677 res = chrec_dont_know;
1681 branch_chrec = analyze_scalar_evolution
1682 (loop, PHI_ARG_DEF (condition_phi, i));
1684 res = chrec_merge (res, branch_chrec);
1690 /* Interpret the operation RHS1 OP RHS2. If we didn't
1691 analyze this node before, follow the definitions until ending
1692 either on an analyzed GIMPLE_ASSIGN, or on a loop-phi-node. On the
1693 return path, this function propagates evolutions (ala constant copy
1694 propagation). OPND1 is not a GIMPLE expression because we could
1695 analyze the effect of an inner loop: see interpret_loop_phi. */
1698 interpret_rhs_expr (struct loop *loop, gimple at_stmt,
1699 tree type, tree rhs1, enum tree_code code, tree rhs2)
1701 tree res, chrec1, chrec2;
1703 if (get_gimple_rhs_class (code) == GIMPLE_SINGLE_RHS)
1705 if (is_gimple_min_invariant (rhs1))
1706 return chrec_convert (type, rhs1, at_stmt);
1708 if (code == SSA_NAME)
1709 return chrec_convert (type, analyze_scalar_evolution (loop, rhs1),
1712 if (code == ASSERT_EXPR)
1714 rhs1 = ASSERT_EXPR_VAR (rhs1);
1715 return chrec_convert (type, analyze_scalar_evolution (loop, rhs1),
1719 return chrec_dont_know;
1724 case POINTER_PLUS_EXPR:
1725 chrec1 = analyze_scalar_evolution (loop, rhs1);
1726 chrec2 = analyze_scalar_evolution (loop, rhs2);
1727 chrec1 = chrec_convert (type, chrec1, at_stmt);
1728 chrec2 = chrec_convert (sizetype, chrec2, at_stmt);
1729 res = chrec_fold_plus (type, chrec1, chrec2);
1733 chrec1 = analyze_scalar_evolution (loop, rhs1);
1734 chrec2 = analyze_scalar_evolution (loop, rhs2);
1735 chrec1 = chrec_convert (type, chrec1, at_stmt);
1736 chrec2 = chrec_convert (type, chrec2, at_stmt);
1737 res = chrec_fold_plus (type, chrec1, chrec2);
1741 chrec1 = analyze_scalar_evolution (loop, rhs1);
1742 chrec2 = analyze_scalar_evolution (loop, rhs2);
1743 chrec1 = chrec_convert (type, chrec1, at_stmt);
1744 chrec2 = chrec_convert (type, chrec2, at_stmt);
1745 res = chrec_fold_minus (type, chrec1, chrec2);
1749 chrec1 = analyze_scalar_evolution (loop, rhs1);
1750 chrec1 = chrec_convert (type, chrec1, at_stmt);
1751 /* TYPE may be integer, real or complex, so use fold_convert. */
1752 res = chrec_fold_multiply (type, chrec1,
1753 fold_convert (type, integer_minus_one_node));
1757 /* Handle ~X as -1 - X. */
1758 chrec1 = analyze_scalar_evolution (loop, rhs1);
1759 chrec1 = chrec_convert (type, chrec1, at_stmt);
1760 res = chrec_fold_minus (type,
1761 fold_convert (type, integer_minus_one_node),
1766 chrec1 = analyze_scalar_evolution (loop, rhs1);
1767 chrec2 = analyze_scalar_evolution (loop, rhs2);
1768 chrec1 = chrec_convert (type, chrec1, at_stmt);
1769 chrec2 = chrec_convert (type, chrec2, at_stmt);
1770 res = chrec_fold_multiply (type, chrec1, chrec2);
1774 chrec1 = analyze_scalar_evolution (loop, rhs1);
1775 res = chrec_convert (type, chrec1, at_stmt);
1779 res = chrec_dont_know;
1786 /* Interpret the expression EXPR. */
1789 interpret_expr (struct loop *loop, gimple at_stmt, tree expr)
1791 enum tree_code code;
1792 tree type = TREE_TYPE (expr), op0, op1;
1794 if (automatically_generated_chrec_p (expr))
1797 if (TREE_CODE (expr) == POLYNOMIAL_CHREC)
1798 return chrec_dont_know;
1800 extract_ops_from_tree (expr, &code, &op0, &op1);
1802 return interpret_rhs_expr (loop, at_stmt, type,
1806 /* Interpret the rhs of the assignment STMT. */
1809 interpret_gimple_assign (struct loop *loop, gimple stmt)
1811 tree type = TREE_TYPE (gimple_assign_lhs (stmt));
1812 enum tree_code code = gimple_assign_rhs_code (stmt);
1814 return interpret_rhs_expr (loop, stmt, type,
1815 gimple_assign_rhs1 (stmt), code,
1816 gimple_assign_rhs2 (stmt));
1821 /* This section contains all the entry points:
1822 - number_of_iterations_in_loop,
1823 - analyze_scalar_evolution,
1824 - instantiate_parameters.
1827 /* Compute and return the evolution function in WRTO_LOOP, the nearest
1828 common ancestor of DEF_LOOP and USE_LOOP. */
1831 compute_scalar_evolution_in_loop (struct loop *wrto_loop,
1832 struct loop *def_loop,
1838 if (def_loop == wrto_loop)
1841 def_loop = superloop_at_depth (def_loop, loop_depth (wrto_loop) + 1);
1842 res = compute_overall_effect_of_inner_loop (def_loop, ev);
1844 if (no_evolution_in_loop_p (res, wrto_loop->num, &val) && val)
1847 return analyze_scalar_evolution_1 (wrto_loop, res, chrec_not_analyzed_yet);
1850 /* Helper recursive function. */
1853 analyze_scalar_evolution_1 (struct loop *loop, tree var, tree res)
1855 tree type = TREE_TYPE (var);
1858 struct loop *def_loop;
1860 if (loop == NULL || TREE_CODE (type) == VECTOR_TYPE)
1861 return chrec_dont_know;
1863 if (TREE_CODE (var) != SSA_NAME)
1864 return interpret_expr (loop, NULL, var);
1866 def = SSA_NAME_DEF_STMT (var);
1867 bb = gimple_bb (def);
1868 def_loop = bb ? bb->loop_father : NULL;
1871 || !flow_bb_inside_loop_p (loop, bb))
1873 /* Keep the symbolic form. */
1878 if (res != chrec_not_analyzed_yet)
1880 if (loop != bb->loop_father)
1881 res = compute_scalar_evolution_in_loop
1882 (find_common_loop (loop, bb->loop_father), bb->loop_father, res);
1887 if (loop != def_loop)
1889 res = analyze_scalar_evolution_1 (def_loop, var, chrec_not_analyzed_yet);
1890 res = compute_scalar_evolution_in_loop (loop, def_loop, res);
1895 switch (gimple_code (def))
1898 res = interpret_gimple_assign (loop, def);
1902 if (loop_phi_node_p (def))
1903 res = interpret_loop_phi (loop, def);
1905 res = interpret_condition_phi (loop, def);
1909 res = chrec_dont_know;
1915 /* Keep the symbolic form. */
1916 if (res == chrec_dont_know)
1919 if (loop == def_loop)
1920 set_scalar_evolution (block_before_loop (loop), var, res);
1925 /* Analyzes and returns the scalar evolution of the ssa_name VAR in
1926 LOOP. LOOP is the loop in which the variable is used.
1928 Example of use: having a pointer VAR to a SSA_NAME node, STMT a
1929 pointer to the statement that uses this variable, in order to
1930 determine the evolution function of the variable, use the following
1933 loop_p loop = loop_containing_stmt (stmt);
1934 tree chrec_with_symbols = analyze_scalar_evolution (loop, var);
1935 tree chrec_instantiated = instantiate_parameters (loop, chrec_with_symbols);
1939 analyze_scalar_evolution (struct loop *loop, tree var)
1943 if (dump_file && (dump_flags & TDF_DETAILS))
1945 fprintf (dump_file, "(analyze_scalar_evolution \n");
1946 fprintf (dump_file, " (loop_nb = %d)\n", loop->num);
1947 fprintf (dump_file, " (scalar = ");
1948 print_generic_expr (dump_file, var, 0);
1949 fprintf (dump_file, ")\n");
1952 res = get_scalar_evolution (block_before_loop (loop), var);
1953 res = analyze_scalar_evolution_1 (loop, var, res);
1955 if (dump_file && (dump_flags & TDF_DETAILS))
1956 fprintf (dump_file, ")\n");
1961 /* Analyze scalar evolution of use of VERSION in USE_LOOP with respect to
1962 WRTO_LOOP (which should be a superloop of USE_LOOP)
1964 FOLDED_CASTS is set to true if resolve_mixers used
1965 chrec_convert_aggressive (TODO -- not really, we are way too conservative
1966 at the moment in order to keep things simple).
1968 To illustrate the meaning of USE_LOOP and WRTO_LOOP, consider the following
1971 for (i = 0; i < 100; i++) -- loop 1
1973 for (j = 0; j < 100; j++) -- loop 2
1980 for (t = 0; t < 100; t++) -- loop 3
1987 Both k1 and k2 are invariants in loop3, thus
1988 analyze_scalar_evolution_in_loop (loop3, loop3, k1) = k1
1989 analyze_scalar_evolution_in_loop (loop3, loop3, k2) = k2
1991 As they are invariant, it does not matter whether we consider their
1992 usage in loop 3 or loop 2, hence
1993 analyze_scalar_evolution_in_loop (loop2, loop3, k1) =
1994 analyze_scalar_evolution_in_loop (loop2, loop2, k1) = i
1995 analyze_scalar_evolution_in_loop (loop2, loop3, k2) =
1996 analyze_scalar_evolution_in_loop (loop2, loop2, k2) = [0,+,1]_2
1998 Similarly for their evolutions with respect to loop 1. The values of K2
1999 in the use in loop 2 vary independently on loop 1, thus we cannot express
2000 the evolution with respect to loop 1:
2001 analyze_scalar_evolution_in_loop (loop1, loop3, k1) =
2002 analyze_scalar_evolution_in_loop (loop1, loop2, k1) = [0,+,1]_1
2003 analyze_scalar_evolution_in_loop (loop1, loop3, k2) =
2004 analyze_scalar_evolution_in_loop (loop1, loop2, k2) = dont_know
2006 The value of k2 in the use in loop 1 is known, though:
2007 analyze_scalar_evolution_in_loop (loop1, loop1, k1) = [0,+,1]_1
2008 analyze_scalar_evolution_in_loop (loop1, loop1, k2) = 100
2012 analyze_scalar_evolution_in_loop (struct loop *wrto_loop, struct loop *use_loop,
2013 tree version, bool *folded_casts)
2016 tree ev = version, tmp;
2018 /* We cannot just do
2020 tmp = analyze_scalar_evolution (use_loop, version);
2021 ev = resolve_mixers (wrto_loop, tmp);
2023 as resolve_mixers would query the scalar evolution with respect to
2024 wrto_loop. For example, in the situation described in the function
2025 comment, suppose that wrto_loop = loop1, use_loop = loop3 and
2028 analyze_scalar_evolution (use_loop, version) = k2
2030 and resolve_mixers (loop1, k2) finds that the value of k2 in loop 1
2031 is 100, which is a wrong result, since we are interested in the
2034 Instead, we need to proceed from use_loop to wrto_loop loop by loop,
2035 each time checking that there is no evolution in the inner loop. */
2038 *folded_casts = false;
2041 tmp = analyze_scalar_evolution (use_loop, ev);
2042 ev = resolve_mixers (use_loop, tmp);
2044 if (folded_casts && tmp != ev)
2045 *folded_casts = true;
2047 if (use_loop == wrto_loop)
2050 /* If the value of the use changes in the inner loop, we cannot express
2051 its value in the outer loop (we might try to return interval chrec,
2052 but we do not have a user for it anyway) */
2053 if (!no_evolution_in_loop_p (ev, use_loop->num, &val)
2055 return chrec_dont_know;
2057 use_loop = loop_outer (use_loop);
2061 /* Returns from CACHE the value for VERSION instantiated below
2062 INSTANTIATED_BELOW block. */
2065 get_instantiated_value (htab_t cache, basic_block instantiated_below,
2068 struct scev_info_str *info, pattern;
2070 pattern.var = version;
2071 pattern.instantiated_below = instantiated_below;
2072 info = (struct scev_info_str *) htab_find (cache, &pattern);
2080 /* Sets in CACHE the value of VERSION instantiated below basic block
2081 INSTANTIATED_BELOW to VAL. */
2084 set_instantiated_value (htab_t cache, basic_block instantiated_below,
2085 tree version, tree val)
2087 struct scev_info_str *info, pattern;
2090 pattern.var = version;
2091 pattern.instantiated_below = instantiated_below;
2092 slot = htab_find_slot (cache, &pattern, INSERT);
2095 *slot = new_scev_info_str (instantiated_below, version);
2096 info = (struct scev_info_str *) *slot;
2100 /* Return the closed_loop_phi node for VAR. If there is none, return
2104 loop_closed_phi_def (tree var)
2109 gimple_stmt_iterator psi;
2111 if (var == NULL_TREE
2112 || TREE_CODE (var) != SSA_NAME)
2115 loop = loop_containing_stmt (SSA_NAME_DEF_STMT (var));
2116 exit = single_exit (loop);
2120 for (psi = gsi_start_phis (exit->dest); !gsi_end_p (psi); gsi_next (&psi))
2122 phi = gsi_stmt (psi);
2123 if (PHI_ARG_DEF_FROM_EDGE (phi, exit) == var)
2124 return PHI_RESULT (phi);
2130 static tree instantiate_scev_r (basic_block, struct loop *, tree, bool,
2133 /* Analyze all the parameters of the chrec, between INSTANTIATE_BELOW
2134 and EVOLUTION_LOOP, that were left under a symbolic form.
2136 CHREC is an SSA_NAME to be instantiated.
2138 CACHE is the cache of already instantiated values.
2140 FOLD_CONVERSIONS should be set to true when the conversions that
2141 may wrap in signed/pointer type are folded, as long as the value of
2142 the chrec is preserved.
2144 SIZE_EXPR is used for computing the size of the expression to be
2145 instantiated, and to stop if it exceeds some limit. */
2148 instantiate_scev_name (basic_block instantiate_below,
2149 struct loop *evolution_loop, tree chrec,
2150 bool fold_conversions, htab_t cache, int size_expr)
2153 struct loop *def_loop;
2154 basic_block def_bb = gimple_bb (SSA_NAME_DEF_STMT (chrec));
2156 /* A parameter (or loop invariant and we do not want to include
2157 evolutions in outer loops), nothing to do. */
2159 || loop_depth (def_bb->loop_father) == 0
2160 || dominated_by_p (CDI_DOMINATORS, instantiate_below, def_bb))
2163 /* We cache the value of instantiated variable to avoid exponential
2164 time complexity due to reevaluations. We also store the convenient
2165 value in the cache in order to prevent infinite recursion -- we do
2166 not want to instantiate the SSA_NAME if it is in a mixer
2167 structure. This is used for avoiding the instantiation of
2168 recursively defined functions, such as:
2170 | a_2 -> {0, +, 1, +, a_2}_1 */
2172 res = get_instantiated_value (cache, instantiate_below, chrec);
2176 res = chrec_dont_know;
2177 set_instantiated_value (cache, instantiate_below, chrec, res);
2179 def_loop = find_common_loop (evolution_loop, def_bb->loop_father);
2181 /* If the analysis yields a parametric chrec, instantiate the
2183 res = analyze_scalar_evolution (def_loop, chrec);
2185 /* Don't instantiate default definitions. */
2186 if (TREE_CODE (res) == SSA_NAME
2187 && SSA_NAME_IS_DEFAULT_DEF (res))
2190 /* Don't instantiate loop-closed-ssa phi nodes. */
2191 else if (TREE_CODE (res) == SSA_NAME
2192 && loop_depth (loop_containing_stmt (SSA_NAME_DEF_STMT (res)))
2193 > loop_depth (def_loop))
2196 res = loop_closed_phi_def (chrec);
2200 /* When there is no loop_closed_phi_def, it means that the
2201 variable is not used after the loop: try to still compute the
2202 value of the variable when exiting the loop. */
2203 if (res == NULL_TREE)
2205 loop_p loop = loop_containing_stmt (SSA_NAME_DEF_STMT (chrec));
2206 res = analyze_scalar_evolution (loop, chrec);
2207 res = compute_overall_effect_of_inner_loop (loop, res);
2208 res = instantiate_scev_r (instantiate_below, evolution_loop, res,
2209 fold_conversions, cache, size_expr);
2211 else if (!dominated_by_p (CDI_DOMINATORS, instantiate_below,
2212 gimple_bb (SSA_NAME_DEF_STMT (res))))
2213 res = chrec_dont_know;
2216 else if (res != chrec_dont_know)
2217 res = instantiate_scev_r (instantiate_below, evolution_loop, res,
2218 fold_conversions, cache, size_expr);
2220 /* Store the correct value to the cache. */
2221 set_instantiated_value (cache, instantiate_below, chrec, res);
2225 /* Analyze all the parameters of the chrec, between INSTANTIATE_BELOW
2226 and EVOLUTION_LOOP, that were left under a symbolic form.
2228 CHREC is a polynomial chain of recurrence to be instantiated.
2230 CACHE is the cache of already instantiated values.
2232 FOLD_CONVERSIONS should be set to true when the conversions that
2233 may wrap in signed/pointer type are folded, as long as the value of
2234 the chrec is preserved.
2236 SIZE_EXPR is used for computing the size of the expression to be
2237 instantiated, and to stop if it exceeds some limit. */
2240 instantiate_scev_poly (basic_block instantiate_below,
2241 struct loop *evolution_loop, tree chrec,
2242 bool fold_conversions, htab_t cache, int size_expr)
2245 tree op0 = instantiate_scev_r (instantiate_below, evolution_loop,
2246 CHREC_LEFT (chrec), fold_conversions, cache,
2248 if (op0 == chrec_dont_know)
2249 return chrec_dont_know;
2251 op1 = instantiate_scev_r (instantiate_below, evolution_loop,
2252 CHREC_RIGHT (chrec), fold_conversions, cache,
2254 if (op1 == chrec_dont_know)
2255 return chrec_dont_know;
2257 if (CHREC_LEFT (chrec) != op0
2258 || CHREC_RIGHT (chrec) != op1)
2260 unsigned var = CHREC_VARIABLE (chrec);
2262 /* When the instantiated stride or base has an evolution in an
2263 innermost loop, return chrec_dont_know, as this is not a
2264 valid SCEV representation. In the reduced testcase for
2265 PR40281 we would have {0, +, {1, +, 1}_2}_1 that has no
2267 if ((tree_is_chrec (op0) && CHREC_VARIABLE (op0) > var)
2268 || (tree_is_chrec (op1) && CHREC_VARIABLE (op1) > var))
2269 return chrec_dont_know;
2271 op1 = chrec_convert_rhs (chrec_type (op0), op1, NULL);
2272 chrec = build_polynomial_chrec (var, op0, op1);
2278 /* Analyze all the parameters of the chrec, between INSTANTIATE_BELOW
2279 and EVOLUTION_LOOP, that were left under a symbolic form.
2281 "C0 CODE C1" is a binary expression of type TYPE to be instantiated.
2283 CACHE is the cache of already instantiated values.
2285 FOLD_CONVERSIONS should be set to true when the conversions that
2286 may wrap in signed/pointer type are folded, as long as the value of
2287 the chrec is preserved.
2289 SIZE_EXPR is used for computing the size of the expression to be
2290 instantiated, and to stop if it exceeds some limit. */
2293 instantiate_scev_binary (basic_block instantiate_below,
2294 struct loop *evolution_loop, tree chrec, enum tree_code code,
2295 tree type, tree c0, tree c1,
2296 bool fold_conversions, htab_t cache, int size_expr)
2299 tree op0 = instantiate_scev_r (instantiate_below, evolution_loop,
2300 c0, fold_conversions, cache,
2302 if (op0 == chrec_dont_know)
2303 return chrec_dont_know;
2305 op1 = instantiate_scev_r (instantiate_below, evolution_loop,
2306 c1, fold_conversions, cache,
2308 if (op1 == chrec_dont_know)
2309 return chrec_dont_know;
2314 op0 = chrec_convert (type, op0, NULL);
2315 op1 = chrec_convert_rhs (type, op1, NULL);
2319 case POINTER_PLUS_EXPR:
2321 return chrec_fold_plus (type, op0, op1);
2324 return chrec_fold_minus (type, op0, op1);
2327 return chrec_fold_multiply (type, op0, op1);
2334 return chrec ? chrec : fold_build2 (code, type, c0, c1);
2337 /* Analyze all the parameters of the chrec, between INSTANTIATE_BELOW
2338 and EVOLUTION_LOOP, that were left under a symbolic form.
2340 "CHREC" that stands for a convert expression "(TYPE) OP" is to be
2343 CACHE is the cache of already instantiated values.
2345 FOLD_CONVERSIONS should be set to true when the conversions that
2346 may wrap in signed/pointer type are folded, as long as the value of
2347 the chrec is preserved.
2349 SIZE_EXPR is used for computing the size of the expression to be
2350 instantiated, and to stop if it exceeds some limit. */
2353 instantiate_scev_convert (basic_block instantiate_below,
2354 struct loop *evolution_loop, tree chrec,
2356 bool fold_conversions, htab_t cache, int size_expr)
2358 tree op0 = instantiate_scev_r (instantiate_below, evolution_loop, op,
2359 fold_conversions, cache, size_expr);
2361 if (op0 == chrec_dont_know)
2362 return chrec_dont_know;
2364 if (fold_conversions)
2366 tree tmp = chrec_convert_aggressive (type, op0);
2371 if (chrec && op0 == op)
2374 /* If we used chrec_convert_aggressive, we can no longer assume that
2375 signed chrecs do not overflow, as chrec_convert does, so avoid
2376 calling it in that case. */
2377 if (fold_conversions)
2378 return fold_convert (type, op0);
2380 return chrec_convert (type, op0, NULL);
2383 /* Analyze all the parameters of the chrec, between INSTANTIATE_BELOW
2384 and EVOLUTION_LOOP, that were left under a symbolic form.
2386 CHREC is a BIT_NOT_EXPR or a NEGATE_EXPR expression to be instantiated.
2387 Handle ~X as -1 - X.
2388 Handle -X as -1 * X.
2390 CACHE is the cache of already instantiated values.
2392 FOLD_CONVERSIONS should be set to true when the conversions that
2393 may wrap in signed/pointer type are folded, as long as the value of
2394 the chrec is preserved.
2396 SIZE_EXPR is used for computing the size of the expression to be
2397 instantiated, and to stop if it exceeds some limit. */
2400 instantiate_scev_not (basic_block instantiate_below,
2401 struct loop *evolution_loop, tree chrec,
2402 enum tree_code code, tree type, tree op,
2403 bool fold_conversions, htab_t cache, int size_expr)
2405 tree op0 = instantiate_scev_r (instantiate_below, evolution_loop, op,
2406 fold_conversions, cache, size_expr);
2408 if (op0 == chrec_dont_know)
2409 return chrec_dont_know;
2413 op0 = chrec_convert (type, op0, NULL);
2418 return chrec_fold_minus
2419 (type, fold_convert (type, integer_minus_one_node), op0);
2422 return chrec_fold_multiply
2423 (type, fold_convert (type, integer_minus_one_node), op0);
2430 return chrec ? chrec : fold_build1 (code, type, op0);
2433 /* Analyze all the parameters of the chrec, between INSTANTIATE_BELOW
2434 and EVOLUTION_LOOP, that were left under a symbolic form.
2436 CHREC is an expression with 3 operands to be instantiated.
2438 CACHE is the cache of already instantiated values.
2440 FOLD_CONVERSIONS should be set to true when the conversions that
2441 may wrap in signed/pointer type are folded, as long as the value of
2442 the chrec is preserved.
2444 SIZE_EXPR is used for computing the size of the expression to be
2445 instantiated, and to stop if it exceeds some limit. */
2448 instantiate_scev_3 (basic_block instantiate_below,
2449 struct loop *evolution_loop, tree chrec,
2450 bool fold_conversions, htab_t cache, int size_expr)
2453 tree op0 = instantiate_scev_r (instantiate_below, evolution_loop,
2454 TREE_OPERAND (chrec, 0),
2455 fold_conversions, cache, size_expr);
2456 if (op0 == chrec_dont_know)
2457 return chrec_dont_know;
2459 op1 = instantiate_scev_r (instantiate_below, evolution_loop,
2460 TREE_OPERAND (chrec, 1),
2461 fold_conversions, cache, size_expr);
2462 if (op1 == chrec_dont_know)
2463 return chrec_dont_know;
2465 op2 = instantiate_scev_r (instantiate_below, evolution_loop,
2466 TREE_OPERAND (chrec, 2),
2467 fold_conversions, cache, size_expr);
2468 if (op2 == chrec_dont_know)
2469 return chrec_dont_know;
2471 if (op0 == TREE_OPERAND (chrec, 0)
2472 && op1 == TREE_OPERAND (chrec, 1)
2473 && op2 == TREE_OPERAND (chrec, 2))
2476 return fold_build3 (TREE_CODE (chrec),
2477 TREE_TYPE (chrec), op0, op1, op2);
2480 /* Analyze all the parameters of the chrec, between INSTANTIATE_BELOW
2481 and EVOLUTION_LOOP, that were left under a symbolic form.
2483 CHREC is an expression with 2 operands to be instantiated.
2485 CACHE is the cache of already instantiated values.
2487 FOLD_CONVERSIONS should be set to true when the conversions that
2488 may wrap in signed/pointer type are folded, as long as the value of
2489 the chrec is preserved.
2491 SIZE_EXPR is used for computing the size of the expression to be
2492 instantiated, and to stop if it exceeds some limit. */
2495 instantiate_scev_2 (basic_block instantiate_below,
2496 struct loop *evolution_loop, tree chrec,
2497 bool fold_conversions, htab_t cache, int size_expr)
2500 tree op0 = instantiate_scev_r (instantiate_below, evolution_loop,
2501 TREE_OPERAND (chrec, 0),
2502 fold_conversions, cache, size_expr);
2503 if (op0 == chrec_dont_know)
2504 return chrec_dont_know;
2506 op1 = instantiate_scev_r (instantiate_below, evolution_loop,
2507 TREE_OPERAND (chrec, 1),
2508 fold_conversions, cache, size_expr);
2509 if (op1 == chrec_dont_know)
2510 return chrec_dont_know;
2512 if (op0 == TREE_OPERAND (chrec, 0)
2513 && op1 == TREE_OPERAND (chrec, 1))
2516 return fold_build2 (TREE_CODE (chrec), TREE_TYPE (chrec), op0, op1);
2519 /* Analyze all the parameters of the chrec, between INSTANTIATE_BELOW
2520 and EVOLUTION_LOOP, that were left under a symbolic form.
2522 CHREC is an expression with 2 operands to be instantiated.
2524 CACHE is the cache of already instantiated values.
2526 FOLD_CONVERSIONS should be set to true when the conversions that
2527 may wrap in signed/pointer type are folded, as long as the value of
2528 the chrec is preserved.
2530 SIZE_EXPR is used for computing the size of the expression to be
2531 instantiated, and to stop if it exceeds some limit. */
2534 instantiate_scev_1 (basic_block instantiate_below,
2535 struct loop *evolution_loop, tree chrec,
2536 bool fold_conversions, htab_t cache, int size_expr)
2538 tree op0 = instantiate_scev_r (instantiate_below, evolution_loop,
2539 TREE_OPERAND (chrec, 0),
2540 fold_conversions, cache, size_expr);
2542 if (op0 == chrec_dont_know)
2543 return chrec_dont_know;
2545 if (op0 == TREE_OPERAND (chrec, 0))
2548 return fold_build1 (TREE_CODE (chrec), TREE_TYPE (chrec), op0);
2551 /* Analyze all the parameters of the chrec, between INSTANTIATE_BELOW
2552 and EVOLUTION_LOOP, that were left under a symbolic form.
2554 CHREC is the scalar evolution to instantiate.
2556 CACHE is the cache of already instantiated values.
2558 FOLD_CONVERSIONS should be set to true when the conversions that
2559 may wrap in signed/pointer type are folded, as long as the value of
2560 the chrec is preserved.
2562 SIZE_EXPR is used for computing the size of the expression to be
2563 instantiated, and to stop if it exceeds some limit. */
2566 instantiate_scev_r (basic_block instantiate_below,
2567 struct loop *evolution_loop, tree chrec,
2568 bool fold_conversions, htab_t cache, int size_expr)
2570 /* Give up if the expression is larger than the MAX that we allow. */
2571 if (size_expr++ > PARAM_VALUE (PARAM_SCEV_MAX_EXPR_SIZE))
2572 return chrec_dont_know;
2574 if (automatically_generated_chrec_p (chrec)
2575 || is_gimple_min_invariant (chrec))
2578 switch (TREE_CODE (chrec))
2581 return instantiate_scev_name (instantiate_below, evolution_loop, chrec,
2582 fold_conversions, cache, size_expr);
2584 case POLYNOMIAL_CHREC:
2585 return instantiate_scev_poly (instantiate_below, evolution_loop, chrec,
2586 fold_conversions, cache, size_expr);
2588 case POINTER_PLUS_EXPR:
2592 return instantiate_scev_binary (instantiate_below, evolution_loop, chrec,
2593 TREE_CODE (chrec), chrec_type (chrec),
2594 TREE_OPERAND (chrec, 0),
2595 TREE_OPERAND (chrec, 1),
2596 fold_conversions, cache, size_expr);
2599 return instantiate_scev_convert (instantiate_below, evolution_loop, chrec,
2600 TREE_TYPE (chrec), TREE_OPERAND (chrec, 0),
2601 fold_conversions, cache, size_expr);
2605 return instantiate_scev_not (instantiate_below, evolution_loop, chrec,
2606 TREE_CODE (chrec), TREE_TYPE (chrec),
2607 TREE_OPERAND (chrec, 0),
2608 fold_conversions, cache, size_expr);
2610 case SCEV_NOT_KNOWN:
2611 return chrec_dont_know;
2620 if (VL_EXP_CLASS_P (chrec))
2621 return chrec_dont_know;
2623 switch (TREE_CODE_LENGTH (TREE_CODE (chrec)))
2626 return instantiate_scev_3 (instantiate_below, evolution_loop, chrec,
2627 fold_conversions, cache, size_expr);
2630 return instantiate_scev_2 (instantiate_below, evolution_loop, chrec,
2631 fold_conversions, cache, size_expr);
2634 return instantiate_scev_1 (instantiate_below, evolution_loop, chrec,
2635 fold_conversions, cache, size_expr);
2644 /* Too complicated to handle. */
2645 return chrec_dont_know;
2648 /* Analyze all the parameters of the chrec that were left under a
2649 symbolic form. INSTANTIATE_BELOW is the basic block that stops the
2650 recursive instantiation of parameters: a parameter is a variable
2651 that is defined in a basic block that dominates INSTANTIATE_BELOW or
2652 a function parameter. */
2655 instantiate_scev (basic_block instantiate_below, struct loop *evolution_loop,
2659 htab_t cache = htab_create (10, hash_scev_info, eq_scev_info, del_scev_info);
2661 if (dump_file && (dump_flags & TDF_DETAILS))
2663 fprintf (dump_file, "(instantiate_scev \n");
2664 fprintf (dump_file, " (instantiate_below = %d)\n", instantiate_below->index);
2665 fprintf (dump_file, " (evolution_loop = %d)\n", evolution_loop->num);
2666 fprintf (dump_file, " (chrec = ");
2667 print_generic_expr (dump_file, chrec, 0);
2668 fprintf (dump_file, ")\n");
2671 res = instantiate_scev_r (instantiate_below, evolution_loop, chrec, false,
2674 if (dump_file && (dump_flags & TDF_DETAILS))
2676 fprintf (dump_file, " (res = ");
2677 print_generic_expr (dump_file, res, 0);
2678 fprintf (dump_file, "))\n");
2681 htab_delete (cache);
2686 /* Similar to instantiate_parameters, but does not introduce the
2687 evolutions in outer loops for LOOP invariants in CHREC, and does not
2688 care about causing overflows, as long as they do not affect value
2689 of an expression. */
2692 resolve_mixers (struct loop *loop, tree chrec)
2694 htab_t cache = htab_create (10, hash_scev_info, eq_scev_info, del_scev_info);
2695 tree ret = instantiate_scev_r (block_before_loop (loop), loop, chrec, true,
2697 htab_delete (cache);
2701 /* Entry point for the analysis of the number of iterations pass.
2702 This function tries to safely approximate the number of iterations
2703 the loop will run. When this property is not decidable at compile
2704 time, the result is chrec_dont_know. Otherwise the result is a
2705 scalar or a symbolic parameter. When the number of iterations may
2706 be equal to zero and the property cannot be determined at compile
2707 time, the result is a COND_EXPR that represents in a symbolic form
2708 the conditions under which the number of iterations is not zero.
2710 Example of analysis: suppose that the loop has an exit condition:
2712 "if (b > 49) goto end_loop;"
2714 and that in a previous analysis we have determined that the
2715 variable 'b' has an evolution function:
2717 "EF = {23, +, 5}_2".
2719 When we evaluate the function at the point 5, i.e. the value of the
2720 variable 'b' after 5 iterations in the loop, we have EF (5) = 48,
2721 and EF (6) = 53. In this case the value of 'b' on exit is '53' and
2722 the loop body has been executed 6 times. */
2725 number_of_latch_executions (struct loop *loop)
2728 struct tree_niter_desc niter_desc;
2732 /* Determine whether the number of iterations in loop has already
2734 res = loop->nb_iterations;
2738 may_be_zero = NULL_TREE;
2740 if (dump_file && (dump_flags & TDF_DETAILS))
2741 fprintf (dump_file, "(number_of_iterations_in_loop = \n");
2743 res = chrec_dont_know;
2744 exit = single_exit (loop);
2746 if (exit && number_of_iterations_exit (loop, exit, &niter_desc, false))
2748 may_be_zero = niter_desc.may_be_zero;
2749 res = niter_desc.niter;
2752 if (res == chrec_dont_know
2754 || integer_zerop (may_be_zero))
2756 else if (integer_nonzerop (may_be_zero))
2757 res = build_int_cst (TREE_TYPE (res), 0);
2759 else if (COMPARISON_CLASS_P (may_be_zero))
2760 res = fold_build3 (COND_EXPR, TREE_TYPE (res), may_be_zero,
2761 build_int_cst (TREE_TYPE (res), 0), res);
2763 res = chrec_dont_know;
2765 if (dump_file && (dump_flags & TDF_DETAILS))
2767 fprintf (dump_file, " (set_nb_iterations_in_loop = ");
2768 print_generic_expr (dump_file, res, 0);
2769 fprintf (dump_file, "))\n");
2772 loop->nb_iterations = res;
2776 /* Returns the number of executions of the exit condition of LOOP,
2777 i.e., the number by one higher than number_of_latch_executions.
2778 Note that unlike number_of_latch_executions, this number does
2779 not necessarily fit in the unsigned variant of the type of
2780 the control variable -- if the number of iterations is a constant,
2781 we return chrec_dont_know if adding one to number_of_latch_executions
2782 overflows; however, in case the number of iterations is symbolic
2783 expression, the caller is responsible for dealing with this
2784 the possible overflow. */
2787 number_of_exit_cond_executions (struct loop *loop)
2789 tree ret = number_of_latch_executions (loop);
2790 tree type = chrec_type (ret);
2792 if (chrec_contains_undetermined (ret))
2795 ret = chrec_fold_plus (type, ret, build_int_cst (type, 1));
2796 if (TREE_CODE (ret) == INTEGER_CST
2797 && TREE_OVERFLOW (ret))
2798 return chrec_dont_know;
2803 /* One of the drivers for testing the scalar evolutions analysis.
2804 This function computes the number of iterations for all the loops
2805 from the EXIT_CONDITIONS array. */
2808 number_of_iterations_for_all_loops (VEC(gimple,heap) **exit_conditions)
2811 unsigned nb_chrec_dont_know_loops = 0;
2812 unsigned nb_static_loops = 0;
2815 FOR_EACH_VEC_ELT (gimple, *exit_conditions, i, cond)
2817 tree res = number_of_latch_executions (loop_containing_stmt (cond));
2818 if (chrec_contains_undetermined (res))
2819 nb_chrec_dont_know_loops++;
2826 fprintf (dump_file, "\n(\n");
2827 fprintf (dump_file, "-----------------------------------------\n");
2828 fprintf (dump_file, "%d\tnb_chrec_dont_know_loops\n", nb_chrec_dont_know_loops);
2829 fprintf (dump_file, "%d\tnb_static_loops\n", nb_static_loops);
2830 fprintf (dump_file, "%d\tnb_total_loops\n", number_of_loops ());
2831 fprintf (dump_file, "-----------------------------------------\n");
2832 fprintf (dump_file, ")\n\n");
2834 print_loops (dump_file, 3);
2840 /* Counters for the stats. */
2846 unsigned nb_affine_multivar;
2847 unsigned nb_higher_poly;
2848 unsigned nb_chrec_dont_know;
2849 unsigned nb_undetermined;
2852 /* Reset the counters. */
2855 reset_chrecs_counters (struct chrec_stats *stats)
2857 stats->nb_chrecs = 0;
2858 stats->nb_affine = 0;
2859 stats->nb_affine_multivar = 0;
2860 stats->nb_higher_poly = 0;
2861 stats->nb_chrec_dont_know = 0;
2862 stats->nb_undetermined = 0;
2865 /* Dump the contents of a CHREC_STATS structure. */
2868 dump_chrecs_stats (FILE *file, struct chrec_stats *stats)
2870 fprintf (file, "\n(\n");
2871 fprintf (file, "-----------------------------------------\n");
2872 fprintf (file, "%d\taffine univariate chrecs\n", stats->nb_affine);
2873 fprintf (file, "%d\taffine multivariate chrecs\n", stats->nb_affine_multivar);
2874 fprintf (file, "%d\tdegree greater than 2 polynomials\n",
2875 stats->nb_higher_poly);
2876 fprintf (file, "%d\tchrec_dont_know chrecs\n", stats->nb_chrec_dont_know);
2877 fprintf (file, "-----------------------------------------\n");
2878 fprintf (file, "%d\ttotal chrecs\n", stats->nb_chrecs);
2879 fprintf (file, "%d\twith undetermined coefficients\n",
2880 stats->nb_undetermined);
2881 fprintf (file, "-----------------------------------------\n");
2882 fprintf (file, "%d\tchrecs in the scev database\n",
2883 (int) htab_elements (scalar_evolution_info));
2884 fprintf (file, "%d\tsets in the scev database\n", nb_set_scev);
2885 fprintf (file, "%d\tgets in the scev database\n", nb_get_scev);
2886 fprintf (file, "-----------------------------------------\n");
2887 fprintf (file, ")\n\n");
2890 /* Gather statistics about CHREC. */
2893 gather_chrec_stats (tree chrec, struct chrec_stats *stats)
2895 if (dump_file && (dump_flags & TDF_STATS))
2897 fprintf (dump_file, "(classify_chrec ");
2898 print_generic_expr (dump_file, chrec, 0);
2899 fprintf (dump_file, "\n");
2904 if (chrec == NULL_TREE)
2906 stats->nb_undetermined++;
2910 switch (TREE_CODE (chrec))
2912 case POLYNOMIAL_CHREC:
2913 if (evolution_function_is_affine_p (chrec))
2915 if (dump_file && (dump_flags & TDF_STATS))
2916 fprintf (dump_file, " affine_univariate\n");
2919 else if (evolution_function_is_affine_multivariate_p (chrec, 0))
2921 if (dump_file && (dump_flags & TDF_STATS))
2922 fprintf (dump_file, " affine_multivariate\n");
2923 stats->nb_affine_multivar++;
2927 if (dump_file && (dump_flags & TDF_STATS))
2928 fprintf (dump_file, " higher_degree_polynomial\n");
2929 stats->nb_higher_poly++;
2938 if (chrec_contains_undetermined (chrec))
2940 if (dump_file && (dump_flags & TDF_STATS))
2941 fprintf (dump_file, " undetermined\n");
2942 stats->nb_undetermined++;
2945 if (dump_file && (dump_flags & TDF_STATS))
2946 fprintf (dump_file, ")\n");
2949 /* One of the drivers for testing the scalar evolutions analysis.
2950 This function analyzes the scalar evolution of all the scalars
2951 defined as loop phi nodes in one of the loops from the
2952 EXIT_CONDITIONS array.
2954 TODO Optimization: A loop is in canonical form if it contains only
2955 a single scalar loop phi node. All the other scalars that have an
2956 evolution in the loop are rewritten in function of this single
2957 index. This allows the parallelization of the loop. */
2960 analyze_scalar_evolution_for_all_loop_phi_nodes (VEC(gimple,heap) **exit_conditions)
2963 struct chrec_stats stats;
2965 gimple_stmt_iterator psi;
2967 reset_chrecs_counters (&stats);
2969 FOR_EACH_VEC_ELT (gimple, *exit_conditions, i, cond)
2975 loop = loop_containing_stmt (cond);
2978 for (psi = gsi_start_phis (bb); !gsi_end_p (psi); gsi_next (&psi))
2980 phi = gsi_stmt (psi);
2981 if (is_gimple_reg (PHI_RESULT (phi)))
2983 chrec = instantiate_parameters
2985 analyze_scalar_evolution (loop, PHI_RESULT (phi)));
2987 if (dump_file && (dump_flags & TDF_STATS))
2988 gather_chrec_stats (chrec, &stats);
2993 if (dump_file && (dump_flags & TDF_STATS))
2994 dump_chrecs_stats (dump_file, &stats);
2997 /* Callback for htab_traverse, gathers information on chrecs in the
3001 gather_stats_on_scev_database_1 (void **slot, void *stats)
3003 struct scev_info_str *entry = (struct scev_info_str *) *slot;
3005 gather_chrec_stats (entry->chrec, (struct chrec_stats *) stats);
3010 /* Classify the chrecs of the whole database. */
3013 gather_stats_on_scev_database (void)
3015 struct chrec_stats stats;
3020 reset_chrecs_counters (&stats);
3022 htab_traverse (scalar_evolution_info, gather_stats_on_scev_database_1,
3025 dump_chrecs_stats (dump_file, &stats);
3033 initialize_scalar_evolutions_analyzer (void)
3035 /* The elements below are unique. */
3036 if (chrec_dont_know == NULL_TREE)
3038 chrec_not_analyzed_yet = NULL_TREE;
3039 chrec_dont_know = make_node (SCEV_NOT_KNOWN);
3040 chrec_known = make_node (SCEV_KNOWN);
3041 TREE_TYPE (chrec_dont_know) = void_type_node;
3042 TREE_TYPE (chrec_known) = void_type_node;
3046 /* Initialize the analysis of scalar evolutions for LOOPS. */
3049 scev_initialize (void)
3055 scalar_evolution_info = htab_create_ggc (100, hash_scev_info, eq_scev_info,
3058 initialize_scalar_evolutions_analyzer ();
3060 FOR_EACH_LOOP (li, loop, 0)
3062 loop->nb_iterations = NULL_TREE;
3066 /* Cleans up the information cached by the scalar evolutions analysis
3067 in the hash table. */
3070 scev_reset_htab (void)
3072 if (!scalar_evolution_info)
3075 htab_empty (scalar_evolution_info);
3078 /* Cleans up the information cached by the scalar evolutions analysis
3079 in the hash table and in the loop->nb_iterations. */
3092 FOR_EACH_LOOP (li, loop, 0)
3094 loop->nb_iterations = NULL_TREE;
3098 /* Checks whether use of OP in USE_LOOP behaves as a simple affine iv with
3099 respect to WRTO_LOOP and returns its base and step in IV if possible
3100 (see analyze_scalar_evolution_in_loop for more details on USE_LOOP
3101 and WRTO_LOOP). If ALLOW_NONCONSTANT_STEP is true, we want step to be
3102 invariant in LOOP. Otherwise we require it to be an integer constant.
3104 IV->no_overflow is set to true if we are sure the iv cannot overflow (e.g.
3105 because it is computed in signed arithmetics). Consequently, adding an
3108 for (i = IV->base; ; i += IV->step)
3110 is only safe if IV->no_overflow is false, or TYPE_OVERFLOW_UNDEFINED is
3111 false for the type of the induction variable, or you can prove that i does
3112 not wrap by some other argument. Otherwise, this might introduce undefined
3115 for (i = iv->base; ; i = (type) ((unsigned type) i + (unsigned type) iv->step))
3117 must be used instead. */
3120 simple_iv (struct loop *wrto_loop, struct loop *use_loop, tree op,
3121 affine_iv *iv, bool allow_nonconstant_step)
3126 iv->base = NULL_TREE;
3127 iv->step = NULL_TREE;
3128 iv->no_overflow = false;
3130 type = TREE_TYPE (op);
3131 if (TREE_CODE (type) != INTEGER_TYPE
3132 && TREE_CODE (type) != POINTER_TYPE)
3135 ev = analyze_scalar_evolution_in_loop (wrto_loop, use_loop, op,
3137 if (chrec_contains_undetermined (ev)
3138 || chrec_contains_symbols_defined_in_loop (ev, wrto_loop->num))
3141 if (tree_does_not_contain_chrecs (ev))
3144 iv->step = build_int_cst (TREE_TYPE (ev), 0);
3145 iv->no_overflow = true;
3149 if (TREE_CODE (ev) != POLYNOMIAL_CHREC
3150 || CHREC_VARIABLE (ev) != (unsigned) wrto_loop->num)
3153 iv->step = CHREC_RIGHT (ev);
3154 if ((!allow_nonconstant_step && TREE_CODE (iv->step) != INTEGER_CST)
3155 || tree_contains_chrecs (iv->step, NULL))
3158 iv->base = CHREC_LEFT (ev);
3159 if (tree_contains_chrecs (iv->base, NULL))
3162 iv->no_overflow = !folded_casts && TYPE_OVERFLOW_UNDEFINED (type);
3167 /* Runs the analysis of scalar evolutions. */
3170 scev_analysis (void)
3172 VEC(gimple,heap) *exit_conditions;
3174 exit_conditions = VEC_alloc (gimple, heap, 37);
3175 select_loops_exit_conditions (&exit_conditions);
3177 if (dump_file && (dump_flags & TDF_STATS))
3178 analyze_scalar_evolution_for_all_loop_phi_nodes (&exit_conditions);
3180 number_of_iterations_for_all_loops (&exit_conditions);
3181 VEC_free (gimple, heap, exit_conditions);
3184 /* Finalize the scalar evolution analysis. */
3187 scev_finalize (void)
3189 if (!scalar_evolution_info)
3191 htab_delete (scalar_evolution_info);
3192 scalar_evolution_info = NULL;
3195 /* Returns true if the expression EXPR is considered to be too expensive
3196 for scev_const_prop. */
3199 expression_expensive_p (tree expr)
3201 enum tree_code code;
3203 if (is_gimple_val (expr))
3206 code = TREE_CODE (expr);
3207 if (code == TRUNC_DIV_EXPR
3208 || code == CEIL_DIV_EXPR
3209 || code == FLOOR_DIV_EXPR
3210 || code == ROUND_DIV_EXPR
3211 || code == TRUNC_MOD_EXPR
3212 || code == CEIL_MOD_EXPR
3213 || code == FLOOR_MOD_EXPR
3214 || code == ROUND_MOD_EXPR
3215 || code == EXACT_DIV_EXPR)
3217 /* Division by power of two is usually cheap, so we allow it.
3218 Forbid anything else. */
3219 if (!integer_pow2p (TREE_OPERAND (expr, 1)))
3223 switch (TREE_CODE_CLASS (code))
3226 case tcc_comparison:
3227 if (expression_expensive_p (TREE_OPERAND (expr, 1)))
3232 return expression_expensive_p (TREE_OPERAND (expr, 0));
3239 /* Replace ssa names for that scev can prove they are constant by the
3240 appropriate constants. Also perform final value replacement in loops,
3241 in case the replacement expressions are cheap.
3243 We only consider SSA names defined by phi nodes; rest is left to the
3244 ordinary constant propagation pass. */
3247 scev_const_prop (void)
3250 tree name, type, ev;
3252 struct loop *loop, *ex_loop;
3253 bitmap ssa_names_to_remove = NULL;
3256 gimple_stmt_iterator psi;
3258 if (number_of_loops () <= 1)
3263 loop = bb->loop_father;
3265 for (psi = gsi_start_phis (bb); !gsi_end_p (psi); gsi_next (&psi))
3267 phi = gsi_stmt (psi);
3268 name = PHI_RESULT (phi);
3270 if (!is_gimple_reg (name))
3273 type = TREE_TYPE (name);
3275 if (!POINTER_TYPE_P (type)
3276 && !INTEGRAL_TYPE_P (type))
3279 ev = resolve_mixers (loop, analyze_scalar_evolution (loop, name));
3280 if (!is_gimple_min_invariant (ev)
3281 || !may_propagate_copy (name, ev))
3284 /* Replace the uses of the name. */
3286 replace_uses_by (name, ev);
3288 if (!ssa_names_to_remove)
3289 ssa_names_to_remove = BITMAP_ALLOC (NULL);
3290 bitmap_set_bit (ssa_names_to_remove, SSA_NAME_VERSION (name));
3294 /* Remove the ssa names that were replaced by constants. We do not
3295 remove them directly in the previous cycle, since this
3296 invalidates scev cache. */
3297 if (ssa_names_to_remove)
3301 EXECUTE_IF_SET_IN_BITMAP (ssa_names_to_remove, 0, i, bi)
3303 gimple_stmt_iterator psi;
3304 name = ssa_name (i);
3305 phi = SSA_NAME_DEF_STMT (name);
3307 gcc_assert (gimple_code (phi) == GIMPLE_PHI);
3308 psi = gsi_for_stmt (phi);
3309 remove_phi_node (&psi, true);
3312 BITMAP_FREE (ssa_names_to_remove);
3316 /* Now the regular final value replacement. */
3317 FOR_EACH_LOOP (li, loop, LI_FROM_INNERMOST)
3320 tree def, rslt, niter;
3321 gimple_stmt_iterator bsi;
3323 /* If we do not know exact number of iterations of the loop, we cannot
3324 replace the final value. */
3325 exit = single_exit (loop);
3329 niter = number_of_latch_executions (loop);
3330 if (niter == chrec_dont_know)
3333 /* Ensure that it is possible to insert new statements somewhere. */
3334 if (!single_pred_p (exit->dest))
3335 split_loop_exit_edge (exit);
3336 bsi = gsi_after_labels (exit->dest);
3338 ex_loop = superloop_at_depth (loop,
3339 loop_depth (exit->dest->loop_father) + 1);
3341 for (psi = gsi_start_phis (exit->dest); !gsi_end_p (psi); )
3343 phi = gsi_stmt (psi);
3344 rslt = PHI_RESULT (phi);
3345 def = PHI_ARG_DEF_FROM_EDGE (phi, exit);
3346 if (!is_gimple_reg (def))
3352 if (!POINTER_TYPE_P (TREE_TYPE (def))
3353 && !INTEGRAL_TYPE_P (TREE_TYPE (def)))
3359 def = analyze_scalar_evolution_in_loop (ex_loop, loop, def, NULL);
3360 def = compute_overall_effect_of_inner_loop (ex_loop, def);
3361 if (!tree_does_not_contain_chrecs (def)
3362 || chrec_contains_symbols_defined_in_loop (def, ex_loop->num)
3363 /* Moving the computation from the loop may prolong life range
3364 of some ssa names, which may cause problems if they appear
3365 on abnormal edges. */
3366 || contains_abnormal_ssa_name_p (def)
3367 /* Do not emit expensive expressions. The rationale is that
3368 when someone writes a code like
3370 while (n > 45) n -= 45;
3372 he probably knows that n is not large, and does not want it
3373 to be turned into n %= 45. */
3374 || expression_expensive_p (def))
3380 /* Eliminate the PHI node and replace it by a computation outside
3382 def = unshare_expr (def);
3383 remove_phi_node (&psi, false);
3385 def = force_gimple_operand_gsi (&bsi, def, false, NULL_TREE,
3386 true, GSI_SAME_STMT);
3387 ass = gimple_build_assign (rslt, def);
3388 gsi_insert_before (&bsi, ass, GSI_SAME_STMT);
3394 #include "gt-tree-scalar-evolution.h"