2 Copyright (C) 2000, 2001, 2002, 2005, 2006, 2007, 2008
3 Free Software Foundation, Inc.
4 Contributed by Paul Brook <paul@nowt.org>
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 /* dependency.c -- Expression dependency analysis code. */
23 /* There's probably quite a bit of duplication in this file. We currently
24 have different dependency checking functions for different types
25 if dependencies. Ideally these would probably be merged. */
29 #include "dependency.h"
31 /* static declarations */
33 enum range {LHS, RHS, MID};
35 /* Dependency types. These must be in reverse order of priority. */
39 GFC_DEP_EQUAL, /* Identical Ranges. */
40 GFC_DEP_FORWARD, /* e.g., a(1:3), a(2:4). */
41 GFC_DEP_OVERLAP, /* May overlap in some other way. */
42 GFC_DEP_NODEP /* Distinct ranges. */
47 #define IS_ARRAY_EXPLICIT(as) ((as->type == AS_EXPLICIT ? 1 : 0))
50 /* Returns 1 if the expr is an integer constant value 1, 0 if it is not or
51 def if the value could not be determined. */
54 gfc_expr_is_one (gfc_expr *expr, int def)
56 gcc_assert (expr != NULL);
58 if (expr->expr_type != EXPR_CONSTANT)
61 if (expr->ts.type != BT_INTEGER)
64 return mpz_cmp_si (expr->value.integer, 1) == 0;
68 /* Compare two values. Returns 0 if e1 == e2, -1 if e1 < e2, +1 if e1 > e2,
69 and -2 if the relationship could not be determined. */
72 gfc_dep_compare_expr (gfc_expr *e1, gfc_expr *e2)
74 gfc_actual_arglist *args1;
75 gfc_actual_arglist *args2;
78 if (e1->expr_type == EXPR_OP
79 && (e1->value.op.op == INTRINSIC_UPLUS
80 || e1->value.op.op == INTRINSIC_PARENTHESES))
81 return gfc_dep_compare_expr (e1->value.op.op1, e2);
82 if (e2->expr_type == EXPR_OP
83 && (e2->value.op.op == INTRINSIC_UPLUS
84 || e2->value.op.op == INTRINSIC_PARENTHESES))
85 return gfc_dep_compare_expr (e1, e2->value.op.op1);
87 if (e1->expr_type == EXPR_OP && e1->value.op.op == INTRINSIC_PLUS)
89 /* Compare X+C vs. X. */
90 if (e1->value.op.op2->expr_type == EXPR_CONSTANT
91 && e1->value.op.op2->ts.type == BT_INTEGER
92 && gfc_dep_compare_expr (e1->value.op.op1, e2) == 0)
93 return mpz_sgn (e1->value.op.op2->value.integer);
95 /* Compare P+Q vs. R+S. */
96 if (e2->expr_type == EXPR_OP && e2->value.op.op == INTRINSIC_PLUS)
100 l = gfc_dep_compare_expr (e1->value.op.op1, e2->value.op.op1);
101 r = gfc_dep_compare_expr (e1->value.op.op2, e2->value.op.op2);
102 if (l == 0 && r == 0)
104 if (l == 0 && r != -2)
106 if (l != -2 && r == 0)
108 if (l == 1 && r == 1)
110 if (l == -1 && r == -1)
113 l = gfc_dep_compare_expr (e1->value.op.op1, e2->value.op.op2);
114 r = gfc_dep_compare_expr (e1->value.op.op2, e2->value.op.op1);
115 if (l == 0 && r == 0)
117 if (l == 0 && r != -2)
119 if (l != -2 && r == 0)
121 if (l == 1 && r == 1)
123 if (l == -1 && r == -1)
128 /* Compare X vs. X+C. */
129 if (e2->expr_type == EXPR_OP && e2->value.op.op == INTRINSIC_PLUS)
131 if (e2->value.op.op2->expr_type == EXPR_CONSTANT
132 && e2->value.op.op2->ts.type == BT_INTEGER
133 && gfc_dep_compare_expr (e1, e2->value.op.op1) == 0)
134 return -mpz_sgn (e2->value.op.op2->value.integer);
137 /* Compare X-C vs. X. */
138 if (e1->expr_type == EXPR_OP && e1->value.op.op == INTRINSIC_MINUS)
140 if (e1->value.op.op2->expr_type == EXPR_CONSTANT
141 && e1->value.op.op2->ts.type == BT_INTEGER
142 && gfc_dep_compare_expr (e1->value.op.op1, e2) == 0)
143 return -mpz_sgn (e1->value.op.op2->value.integer);
145 /* Compare P-Q vs. R-S. */
146 if (e2->expr_type == EXPR_OP && e2->value.op.op == INTRINSIC_MINUS)
150 l = gfc_dep_compare_expr (e1->value.op.op1, e2->value.op.op1);
151 r = gfc_dep_compare_expr (e1->value.op.op2, e2->value.op.op2);
152 if (l == 0 && r == 0)
154 if (l != -2 && r == 0)
156 if (l == 0 && r != -2)
158 if (l == 1 && r == -1)
160 if (l == -1 && r == 1)
165 /* Compare X vs. X-C. */
166 if (e2->expr_type == EXPR_OP && e2->value.op.op == INTRINSIC_MINUS)
168 if (e2->value.op.op2->expr_type == EXPR_CONSTANT
169 && e2->value.op.op2->ts.type == BT_INTEGER
170 && gfc_dep_compare_expr (e1, e2->value.op.op1) == 0)
171 return mpz_sgn (e2->value.op.op2->value.integer);
174 if (e1->expr_type != e2->expr_type)
177 switch (e1->expr_type)
180 if (e1->ts.type != BT_INTEGER || e2->ts.type != BT_INTEGER)
183 i = mpz_cmp (e1->value.integer, e2->value.integer);
191 if (e1->ref || e2->ref)
193 if (e1->symtree->n.sym == e2->symtree->n.sym)
198 /* Intrinsic operators are the same if their operands are the same. */
199 if (e1->value.op.op != e2->value.op.op)
201 if (e1->value.op.op2 == 0)
203 i = gfc_dep_compare_expr (e1->value.op.op1, e2->value.op.op1);
204 return i == 0 ? 0 : -2;
206 if (gfc_dep_compare_expr (e1->value.op.op1, e2->value.op.op1) == 0
207 && gfc_dep_compare_expr (e1->value.op.op2, e2->value.op.op2) == 0)
209 /* TODO Handle commutative binary operators here? */
213 /* We can only compare calls to the same intrinsic function. */
214 if (e1->value.function.isym == 0 || e2->value.function.isym == 0
215 || e1->value.function.isym != e2->value.function.isym)
218 args1 = e1->value.function.actual;
219 args2 = e2->value.function.actual;
221 /* We should list the "constant" intrinsic functions. Those
222 without side-effects that provide equal results given equal
224 switch (e1->value.function.isym->id)
226 case GFC_ISYM_CONVERSION:
227 /* Handle integer extensions specially, as __convert_i4_i8
228 is not only "constant" but also "unary" and "increasing". */
229 if (args1 && !args1->next
230 && args2 && !args2->next
231 && e1->ts.type == BT_INTEGER
232 && args1->expr->ts.type == BT_INTEGER
233 && e1->ts.kind > args1->expr->ts.kind
234 && e2->ts.type == e1->ts.type
235 && e2->ts.kind == e1->ts.kind
236 && args2->expr->ts.type == args1->expr->ts.type
237 && args2->expr->ts.kind == args2->expr->ts.kind)
238 return gfc_dep_compare_expr (args1->expr, args2->expr);
242 case GFC_ISYM_LOGICAL:
250 /* Compare the argument lists for equality. */
251 while (args1 && args2)
253 if (gfc_dep_compare_expr (args1->expr, args2->expr) != 0)
258 return (args1 || args2) ? -2 : 0;
266 /* Returns 1 if the two ranges are the same, 0 if they are not, and def
267 if the results are indeterminate. N is the dimension to compare. */
270 gfc_is_same_range (gfc_array_ref *ar1, gfc_array_ref *ar2, int n, int def)
276 /* TODO: More sophisticated range comparison. */
277 gcc_assert (ar1 && ar2);
279 gcc_assert (ar1->dimen_type[n] == ar2->dimen_type[n]);
283 /* Check for mismatching strides. A NULL stride means a stride of 1. */
286 i = gfc_expr_is_one (e1, -1);
294 i = gfc_expr_is_one (e2, -1);
302 i = gfc_dep_compare_expr (e1, e2);
308 /* The strides match. */
310 /* Check the range start. */
315 /* Use the bound of the array if no bound is specified. */
317 e1 = ar1->as->lower[n];
320 e2 = ar2->as->lower[n];
322 /* Check we have values for both. */
326 i = gfc_dep_compare_expr (e1, e2);
333 /* Check the range end. */
338 /* Use the bound of the array if no bound is specified. */
340 e1 = ar1->as->upper[n];
343 e2 = ar2->as->upper[n];
345 /* Check we have values for both. */
349 i = gfc_dep_compare_expr (e1, e2);
360 /* Some array-returning intrinsics can be implemented by reusing the
361 data from one of the array arguments. For example, TRANSPOSE does
362 not necessarily need to allocate new data: it can be implemented
363 by copying the original array's descriptor and simply swapping the
364 two dimension specifications.
366 If EXPR is a call to such an intrinsic, return the argument
367 whose data can be reused, otherwise return NULL. */
370 gfc_get_noncopying_intrinsic_argument (gfc_expr *expr)
372 if (expr->expr_type != EXPR_FUNCTION || !expr->value.function.isym)
375 switch (expr->value.function.isym->id)
377 case GFC_ISYM_TRANSPOSE:
378 return expr->value.function.actual->expr;
386 /* Return true if the result of reference REF can only be constructed
387 using a temporary array. */
390 gfc_ref_needs_temporary_p (gfc_ref *ref)
396 for (; ref; ref = ref->next)
400 /* Vector dimensions are generally not monotonic and must be
401 handled using a temporary. */
402 if (ref->u.ar.type == AR_SECTION)
403 for (n = 0; n < ref->u.ar.dimen; n++)
404 if (ref->u.ar.dimen_type[n] == DIMEN_VECTOR)
411 /* Within an array reference, character substrings generally
412 need a temporary. Character array strides are expressed as
413 multiples of the element size (consistent with other array
414 types), not in characters. */
425 /* Return true if array variable VAR could be passed to the same function
426 as argument EXPR without interfering with EXPR. INTENT is the intent
429 This is considerably less conservative than other dependencies
430 because many function arguments will already be copied into a
434 gfc_check_argument_var_dependency (gfc_expr *var, sym_intent intent,
437 gcc_assert (var->expr_type == EXPR_VARIABLE);
438 gcc_assert (var->rank > 0);
440 switch (expr->expr_type)
443 return (gfc_ref_needs_temporary_p (expr->ref)
444 || gfc_check_dependency (var, expr, 1));
447 return gfc_check_dependency (var, expr, 1);
450 if (intent != INTENT_IN && expr->inline_noncopying_intrinsic)
452 expr = gfc_get_noncopying_intrinsic_argument (expr);
453 return gfc_check_argument_var_dependency (var, intent, expr);
463 /* Like gfc_check_argument_var_dependency, but extended to any
464 array expression OTHER, not just variables. */
467 gfc_check_argument_dependency (gfc_expr *other, sym_intent intent,
470 switch (other->expr_type)
473 return gfc_check_argument_var_dependency (other, intent, expr);
476 if (other->inline_noncopying_intrinsic)
478 other = gfc_get_noncopying_intrinsic_argument (other);
479 return gfc_check_argument_dependency (other, INTENT_IN, expr);
489 /* Like gfc_check_argument_dependency, but check all the arguments in ACTUAL.
490 FNSYM is the function being called, or NULL if not known. */
493 gfc_check_fncall_dependency (gfc_expr *other, sym_intent intent,
494 gfc_symbol *fnsym, gfc_actual_arglist *actual)
496 gfc_formal_arglist *formal;
499 formal = fnsym ? fnsym->formal : NULL;
500 for (; actual; actual = actual->next, formal = formal ? formal->next : NULL)
504 /* Skip args which are not present. */
508 /* Skip other itself. */
512 /* Skip intent(in) arguments if OTHER itself is intent(in). */
513 if (formal && intent == INTENT_IN
514 && formal->sym->attr.intent == INTENT_IN)
517 if (gfc_check_argument_dependency (other, intent, expr))
525 /* Return 1 if e1 and e2 are equivalenced arrays, either
526 directly or indirectly; i.e., equivalence (a,b) for a and b
527 or equivalence (a,c),(b,c). This function uses the equiv_
528 lists, generated in trans-common(add_equivalences), that are
529 guaranteed to pick up indirect equivalences. We explicitly
530 check for overlap using the offset and length of the equivalence.
531 This function is symmetric.
532 TODO: This function only checks whether the full top-level
533 symbols overlap. An improved implementation could inspect
534 e1->ref and e2->ref to determine whether the actually accessed
535 portions of these variables/arrays potentially overlap. */
538 gfc_are_equivalenced_arrays (gfc_expr *e1, gfc_expr *e2)
541 gfc_equiv_info *s, *fl1, *fl2;
543 gcc_assert (e1->expr_type == EXPR_VARIABLE
544 && e2->expr_type == EXPR_VARIABLE);
546 if (!e1->symtree->n.sym->attr.in_equivalence
547 || !e2->symtree->n.sym->attr.in_equivalence|| !e1->rank || !e2->rank)
550 if (e1->symtree->n.sym->ns
551 && e1->symtree->n.sym->ns != gfc_current_ns)
552 l = e1->symtree->n.sym->ns->equiv_lists;
554 l = gfc_current_ns->equiv_lists;
556 /* Go through the equiv_lists and return 1 if the variables
557 e1 and e2 are members of the same group and satisfy the
558 requirement on their relative offsets. */
559 for (; l; l = l->next)
563 for (s = l->equiv; s; s = s->next)
565 if (s->sym == e1->symtree->n.sym)
571 if (s->sym == e2->symtree->n.sym)
581 /* Can these lengths be zero? */
582 if (fl1->length <= 0 || fl2->length <= 0)
584 /* These can't overlap if [f11,fl1+length] is before
585 [fl2,fl2+length], or [fl2,fl2+length] is before
586 [fl1,fl1+length], otherwise they do overlap. */
587 if (fl1->offset + fl1->length > fl2->offset
588 && fl2->offset + fl2->length > fl1->offset)
596 /* Return true if the statement body redefines the condition. Returns
597 true if expr2 depends on expr1. expr1 should be a single term
598 suitable for the lhs of an assignment. The IDENTICAL flag indicates
599 whether array references to the same symbol with identical range
600 references count as a dependency or not. Used for forall and where
601 statements. Also used with functions returning arrays without a
605 gfc_check_dependency (gfc_expr *expr1, gfc_expr *expr2, bool identical)
607 gfc_actual_arglist *actual;
612 gcc_assert (expr1->expr_type == EXPR_VARIABLE);
614 switch (expr2->expr_type)
617 n = gfc_check_dependency (expr1, expr2->value.op.op1, identical);
620 if (expr2->value.op.op2)
621 return gfc_check_dependency (expr1, expr2->value.op.op2, identical);
625 /* The interesting cases are when the symbols don't match. */
626 if (expr1->symtree->n.sym != expr2->symtree->n.sym)
628 gfc_typespec *ts1 = &expr1->symtree->n.sym->ts;
629 gfc_typespec *ts2 = &expr2->symtree->n.sym->ts;
631 /* Return 1 if expr1 and expr2 are equivalenced arrays. */
632 if (gfc_are_equivalenced_arrays (expr1, expr2))
635 /* Symbols can only alias if they have the same type. */
636 if (ts1->type != BT_UNKNOWN && ts2->type != BT_UNKNOWN
637 && ts1->type != BT_DERIVED && ts2->type != BT_DERIVED)
639 if (ts1->type != ts2->type || ts1->kind != ts2->kind)
643 /* If either variable is a pointer, assume the worst. */
644 /* TODO: -fassume-no-pointer-aliasing */
645 if (expr1->symtree->n.sym->attr.pointer)
647 for (ref = expr1->ref; ref; ref = ref->next)
648 if (ref->type == REF_COMPONENT && ref->u.c.component->attr.pointer)
651 if (expr2->symtree->n.sym->attr.pointer)
653 for (ref = expr2->ref; ref; ref = ref->next)
654 if (ref->type == REF_COMPONENT && ref->u.c.component->attr.pointer)
657 /* Otherwise distinct symbols have no dependencies. */
664 /* Identical and disjoint ranges return 0,
665 overlapping ranges return 1. */
666 if (expr1->ref && expr2->ref)
667 return gfc_dep_resolver (expr1->ref, expr2->ref);
672 if (expr2->inline_noncopying_intrinsic)
674 /* Remember possible differences between elemental and
675 transformational functions. All functions inside a FORALL
677 for (actual = expr2->value.function.actual;
678 actual; actual = actual->next)
682 n = gfc_check_dependency (expr1, actual->expr, identical);
693 /* Loop through the array constructor's elements. */
694 for (c = expr2->value.constructor; c; c = c->next)
696 /* If this is an iterator, assume the worst. */
699 /* Avoid recursion in the common case. */
700 if (c->expr->expr_type == EXPR_CONSTANT)
702 if (gfc_check_dependency (expr1, c->expr, 1))
713 /* Determines overlapping for two array sections. */
715 static gfc_dependency
716 gfc_check_section_vs_section (gfc_ref *lref, gfc_ref *rref, int n)
737 /* If they are the same range, return without more ado. */
738 if (gfc_is_same_range (&l_ar, &r_ar, n, 0))
739 return GFC_DEP_EQUAL;
741 l_start = l_ar.start[n];
743 l_stride = l_ar.stride[n];
745 r_start = r_ar.start[n];
747 r_stride = r_ar.stride[n];
749 /* If l_start is NULL take it from array specifier. */
750 if (NULL == l_start && IS_ARRAY_EXPLICIT (l_ar.as))
751 l_start = l_ar.as->lower[n];
752 /* If l_end is NULL take it from array specifier. */
753 if (NULL == l_end && IS_ARRAY_EXPLICIT (l_ar.as))
754 l_end = l_ar.as->upper[n];
756 /* If r_start is NULL take it from array specifier. */
757 if (NULL == r_start && IS_ARRAY_EXPLICIT (r_ar.as))
758 r_start = r_ar.as->lower[n];
759 /* If r_end is NULL take it from array specifier. */
760 if (NULL == r_end && IS_ARRAY_EXPLICIT (r_ar.as))
761 r_end = r_ar.as->upper[n];
763 /* Determine whether the l_stride is positive or negative. */
766 else if (l_stride->expr_type == EXPR_CONSTANT
767 && l_stride->ts.type == BT_INTEGER)
768 l_dir = mpz_sgn (l_stride->value.integer);
769 else if (l_start && l_end)
770 l_dir = gfc_dep_compare_expr (l_end, l_start);
774 /* Determine whether the r_stride is positive or negative. */
777 else if (r_stride->expr_type == EXPR_CONSTANT
778 && r_stride->ts.type == BT_INTEGER)
779 r_dir = mpz_sgn (r_stride->value.integer);
780 else if (r_start && r_end)
781 r_dir = gfc_dep_compare_expr (r_end, r_start);
785 /* The strides should never be zero. */
786 if (l_dir == 0 || r_dir == 0)
787 return GFC_DEP_OVERLAP;
789 /* Determine LHS upper and lower bounds. */
795 else if (l_dir == -1)
806 /* Determine RHS upper and lower bounds. */
812 else if (r_dir == -1)
823 /* Check whether the ranges are disjoint. */
824 if (l_upper && r_lower && gfc_dep_compare_expr (l_upper, r_lower) == -1)
825 return GFC_DEP_NODEP;
826 if (r_upper && l_lower && gfc_dep_compare_expr (r_upper, l_lower) == -1)
827 return GFC_DEP_NODEP;
829 /* Handle cases like x:y:1 vs. x:z:-1 as GFC_DEP_EQUAL. */
830 if (l_start && r_start && gfc_dep_compare_expr (l_start, r_start) == 0)
832 if (l_dir == 1 && r_dir == -1)
833 return GFC_DEP_EQUAL;
834 if (l_dir == -1 && r_dir == 1)
835 return GFC_DEP_EQUAL;
838 /* Handle cases like x:y:1 vs. z:y:-1 as GFC_DEP_EQUAL. */
839 if (l_end && r_end && gfc_dep_compare_expr (l_end, r_end) == 0)
841 if (l_dir == 1 && r_dir == -1)
842 return GFC_DEP_EQUAL;
843 if (l_dir == -1 && r_dir == 1)
844 return GFC_DEP_EQUAL;
847 /* Check for forward dependencies x:y vs. x+1:z. */
848 if (l_dir == 1 && r_dir == 1
849 && l_start && r_start && gfc_dep_compare_expr (l_start, r_start) == -1
850 && l_end && r_end && gfc_dep_compare_expr (l_end, r_end) == -1)
852 /* Check that the strides are the same. */
853 if (!l_stride && !r_stride)
854 return GFC_DEP_FORWARD;
855 if (l_stride && r_stride
856 && gfc_dep_compare_expr (l_stride, r_stride) == 0)
857 return GFC_DEP_FORWARD;
860 /* Check for forward dependencies x:y:-1 vs. x-1:z:-1. */
861 if (l_dir == -1 && r_dir == -1
862 && l_start && r_start && gfc_dep_compare_expr (l_start, r_start) == 1
863 && l_end && r_end && gfc_dep_compare_expr (l_end, r_end) == 1)
865 /* Check that the strides are the same. */
866 if (!l_stride && !r_stride)
867 return GFC_DEP_FORWARD;
868 if (l_stride && r_stride
869 && gfc_dep_compare_expr (l_stride, r_stride) == 0)
870 return GFC_DEP_FORWARD;
873 return GFC_DEP_OVERLAP;
877 /* Determines overlapping for a single element and a section. */
879 static gfc_dependency
880 gfc_check_element_vs_section( gfc_ref *lref, gfc_ref *rref, int n)
889 elem = lref->u.ar.start[n];
891 return GFC_DEP_OVERLAP;
894 start = ref->start[n] ;
896 stride = ref->stride[n];
898 if (!start && IS_ARRAY_EXPLICIT (ref->as))
899 start = ref->as->lower[n];
900 if (!end && IS_ARRAY_EXPLICIT (ref->as))
901 end = ref->as->upper[n];
903 /* Determine whether the stride is positive or negative. */
906 else if (stride->expr_type == EXPR_CONSTANT
907 && stride->ts.type == BT_INTEGER)
908 s = mpz_sgn (stride->value.integer);
912 /* Stride should never be zero. */
914 return GFC_DEP_OVERLAP;
916 /* Positive strides. */
919 /* Check for elem < lower. */
920 if (start && gfc_dep_compare_expr (elem, start) == -1)
921 return GFC_DEP_NODEP;
922 /* Check for elem > upper. */
923 if (end && gfc_dep_compare_expr (elem, end) == 1)
924 return GFC_DEP_NODEP;
928 s = gfc_dep_compare_expr (start, end);
929 /* Check for an empty range. */
931 return GFC_DEP_NODEP;
932 if (s == 0 && gfc_dep_compare_expr (elem, start) == 0)
933 return GFC_DEP_EQUAL;
936 /* Negative strides. */
939 /* Check for elem > upper. */
940 if (end && gfc_dep_compare_expr (elem, start) == 1)
941 return GFC_DEP_NODEP;
942 /* Check for elem < lower. */
943 if (start && gfc_dep_compare_expr (elem, end) == -1)
944 return GFC_DEP_NODEP;
948 s = gfc_dep_compare_expr (start, end);
949 /* Check for an empty range. */
951 return GFC_DEP_NODEP;
952 if (s == 0 && gfc_dep_compare_expr (elem, start) == 0)
953 return GFC_DEP_EQUAL;
956 /* Unknown strides. */
960 return GFC_DEP_OVERLAP;
961 s = gfc_dep_compare_expr (start, end);
963 return GFC_DEP_OVERLAP;
964 /* Assume positive stride. */
967 /* Check for elem < lower. */
968 if (gfc_dep_compare_expr (elem, start) == -1)
969 return GFC_DEP_NODEP;
970 /* Check for elem > upper. */
971 if (gfc_dep_compare_expr (elem, end) == 1)
972 return GFC_DEP_NODEP;
974 /* Assume negative stride. */
977 /* Check for elem > upper. */
978 if (gfc_dep_compare_expr (elem, start) == 1)
979 return GFC_DEP_NODEP;
980 /* Check for elem < lower. */
981 if (gfc_dep_compare_expr (elem, end) == -1)
982 return GFC_DEP_NODEP;
987 s = gfc_dep_compare_expr (elem, start);
989 return GFC_DEP_EQUAL;
990 if (s == 1 || s == -1)
991 return GFC_DEP_NODEP;
995 return GFC_DEP_OVERLAP;
999 /* Traverse expr, checking all EXPR_VARIABLE symbols for their
1000 forall_index attribute. Return true if any variable may be
1001 being used as a FORALL index. Its safe to pessimistically
1002 return true, and assume a dependency. */
1005 contains_forall_index_p (gfc_expr *expr)
1007 gfc_actual_arglist *arg;
1015 switch (expr->expr_type)
1018 if (expr->symtree->n.sym->forall_index)
1023 if (contains_forall_index_p (expr->value.op.op1)
1024 || contains_forall_index_p (expr->value.op.op2))
1029 for (arg = expr->value.function.actual; arg; arg = arg->next)
1030 if (contains_forall_index_p (arg->expr))
1036 case EXPR_SUBSTRING:
1039 case EXPR_STRUCTURE:
1041 for (c = expr->value.constructor; c; c = c->next)
1042 if (contains_forall_index_p (c->expr))
1050 for (ref = expr->ref; ref; ref = ref->next)
1054 for (i = 0; i < ref->u.ar.dimen; i++)
1055 if (contains_forall_index_p (ref->u.ar.start[i])
1056 || contains_forall_index_p (ref->u.ar.end[i])
1057 || contains_forall_index_p (ref->u.ar.stride[i]))
1065 if (contains_forall_index_p (ref->u.ss.start)
1066 || contains_forall_index_p (ref->u.ss.end))
1077 /* Determines overlapping for two single element array references. */
1079 static gfc_dependency
1080 gfc_check_element_vs_element (gfc_ref *lref, gfc_ref *rref, int n)
1090 l_start = l_ar.start[n] ;
1091 r_start = r_ar.start[n] ;
1092 i = gfc_dep_compare_expr (r_start, l_start);
1094 return GFC_DEP_EQUAL;
1096 /* Treat two scalar variables as potentially equal. This allows
1097 us to prove that a(i,:) and a(j,:) have no dependency. See
1098 Gerald Roth, "Evaluation of Array Syntax Dependence Analysis",
1099 Proceedings of the International Conference on Parallel and
1100 Distributed Processing Techniques and Applications (PDPTA2001),
1101 Las Vegas, Nevada, June 2001. */
1102 /* However, we need to be careful when either scalar expression
1103 contains a FORALL index, as these can potentially change value
1104 during the scalarization/traversal of this array reference. */
1105 if (contains_forall_index_p (r_start) || contains_forall_index_p (l_start))
1106 return GFC_DEP_OVERLAP;
1109 return GFC_DEP_NODEP;
1110 return GFC_DEP_EQUAL;
1114 /* Determine if an array ref, usually an array section specifies the
1118 gfc_full_array_ref_p (gfc_ref *ref)
1122 if (ref->type != REF_ARRAY)
1124 if (ref->u.ar.type == AR_FULL)
1126 if (ref->u.ar.type != AR_SECTION)
1131 for (i = 0; i < ref->u.ar.dimen; i++)
1133 /* If we have a single element in the reference, we need to check
1134 that the array has a single element and that we actually reference
1135 the correct element. */
1136 if (ref->u.ar.dimen_type[i] == DIMEN_ELEMENT)
1139 || !ref->u.ar.as->lower[i]
1140 || !ref->u.ar.as->upper[i]
1141 || gfc_dep_compare_expr (ref->u.ar.as->lower[i],
1142 ref->u.ar.as->upper[i])
1143 || !ref->u.ar.start[i]
1144 || gfc_dep_compare_expr (ref->u.ar.start[i],
1145 ref->u.ar.as->lower[i]))
1151 /* Check the lower bound. */
1152 if (ref->u.ar.start[i]
1154 || !ref->u.ar.as->lower[i]
1155 || gfc_dep_compare_expr (ref->u.ar.start[i],
1156 ref->u.ar.as->lower[i])))
1158 /* Check the upper bound. */
1159 if (ref->u.ar.end[i]
1161 || !ref->u.ar.as->upper[i]
1162 || gfc_dep_compare_expr (ref->u.ar.end[i],
1163 ref->u.ar.as->upper[i])))
1165 /* Check the stride. */
1166 if (ref->u.ar.stride[i] && !gfc_expr_is_one (ref->u.ar.stride[i], 0))
1173 /* Finds if two array references are overlapping or not.
1175 1 : array references are overlapping.
1176 0 : array references are identical or not overlapping. */
1179 gfc_dep_resolver (gfc_ref *lref, gfc_ref *rref)
1182 gfc_dependency fin_dep;
1183 gfc_dependency this_dep;
1185 fin_dep = GFC_DEP_ERROR;
1186 /* Dependencies due to pointers should already have been identified.
1187 We only need to check for overlapping array references. */
1189 while (lref && rref)
1191 /* We're resolving from the same base symbol, so both refs should be
1192 the same type. We traverse the reference chain until we find ranges
1193 that are not equal. */
1194 gcc_assert (lref->type == rref->type);
1198 /* The two ranges can't overlap if they are from different
1200 if (lref->u.c.component != rref->u.c.component)
1205 /* Substring overlaps are handled by the string assignment code
1206 if there is not an underlying dependency. */
1207 return (fin_dep == GFC_DEP_OVERLAP) ? 1 : 0;
1210 if (lref->u.ar.dimen != rref->u.ar.dimen)
1212 if (lref->u.ar.type == AR_FULL)
1213 fin_dep = gfc_full_array_ref_p (rref) ? GFC_DEP_EQUAL
1215 else if (rref->u.ar.type == AR_FULL)
1216 fin_dep = gfc_full_array_ref_p (lref) ? GFC_DEP_EQUAL
1223 for (n=0; n < lref->u.ar.dimen; n++)
1225 /* Assume dependency when either of array reference is vector
1227 if (lref->u.ar.dimen_type[n] == DIMEN_VECTOR
1228 || rref->u.ar.dimen_type[n] == DIMEN_VECTOR)
1230 if (lref->u.ar.dimen_type[n] == DIMEN_RANGE
1231 && rref->u.ar.dimen_type[n] == DIMEN_RANGE)
1232 this_dep = gfc_check_section_vs_section (lref, rref, n);
1233 else if (lref->u.ar.dimen_type[n] == DIMEN_ELEMENT
1234 && rref->u.ar.dimen_type[n] == DIMEN_RANGE)
1235 this_dep = gfc_check_element_vs_section (lref, rref, n);
1236 else if (rref->u.ar.dimen_type[n] == DIMEN_ELEMENT
1237 && lref->u.ar.dimen_type[n] == DIMEN_RANGE)
1238 this_dep = gfc_check_element_vs_section (rref, lref, n);
1241 gcc_assert (rref->u.ar.dimen_type[n] == DIMEN_ELEMENT
1242 && lref->u.ar.dimen_type[n] == DIMEN_ELEMENT);
1243 this_dep = gfc_check_element_vs_element (rref, lref, n);
1246 /* If any dimension doesn't overlap, we have no dependency. */
1247 if (this_dep == GFC_DEP_NODEP)
1250 /* Overlap codes are in order of priority. We only need to
1251 know the worst one.*/
1252 if (this_dep > fin_dep)
1256 /* If this is an equal element, we have to keep going until we find
1257 the "real" array reference. */
1258 if (lref->u.ar.type == AR_ELEMENT
1259 && rref->u.ar.type == AR_ELEMENT
1260 && fin_dep == GFC_DEP_EQUAL)
1263 /* Exactly matching and forward overlapping ranges don't cause a
1265 if (fin_dep < GFC_DEP_OVERLAP)
1268 /* Keep checking. We only have a dependency if
1269 subsequent references also overlap. */
1279 /* If we haven't seen any array refs then something went wrong. */
1280 gcc_assert (fin_dep != GFC_DEP_ERROR);
1282 /* Assume the worst if we nest to different depths. */
1286 return fin_dep == GFC_DEP_OVERLAP;