From 554fd8c5195424bdbcabf5de30fdc183aba391bd Mon Sep 17 00:00:00 2001 From: upstream source tree Date: Sun, 15 Mar 2015 20:14:05 -0400 Subject: obtained gcc-4.6.4.tar.bz2 from upstream website; verified gcc-4.6.4.tar.bz2.sig; imported gcc-4.6.4 source tree from verified upstream tarball. downloading a git-generated archive based on the 'upstream' tag should provide you with a source tree that is binary identical to the one extracted from the above tarball. if you have obtained the source via the command 'git clone', however, do note that line-endings of files in your working directory might differ from line-endings of the respective files in the upstream repository. --- gcc/fortran/dependency.c | 1882 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 1882 insertions(+) create mode 100644 gcc/fortran/dependency.c (limited to 'gcc/fortran/dependency.c') diff --git a/gcc/fortran/dependency.c b/gcc/fortran/dependency.c new file mode 100644 index 000000000..49e47fb48 --- /dev/null +++ b/gcc/fortran/dependency.c @@ -0,0 +1,1882 @@ +/* Dependency analysis + Copyright (C) 2000, 2001, 2002, 2005, 2006, 2007, 2008, 2009, 2010 + Free Software Foundation, Inc. + Contributed by Paul Brook + +This file is part of GCC. + +GCC is free software; you can redistribute it and/or modify it under +the terms of the GNU General Public License as published by the Free +Software Foundation; either version 3, or (at your option) any later +version. + +GCC is distributed in the hope that it will be useful, but WITHOUT ANY +WARRANTY; without even the implied warranty of MERCHANTABILITY or +FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +for more details. + +You should have received a copy of the GNU General Public License +along with GCC; see the file COPYING3. If not see +. */ + +/* dependency.c -- Expression dependency analysis code. */ +/* There's probably quite a bit of duplication in this file. We currently + have different dependency checking functions for different types + if dependencies. Ideally these would probably be merged. */ + +#include "config.h" +#include "system.h" +#include "gfortran.h" +#include "dependency.h" +#include "constructor.h" +#include "arith.h" + +/* static declarations */ +/* Enums */ +enum range {LHS, RHS, MID}; + +/* Dependency types. These must be in reverse order of priority. */ +typedef enum +{ + GFC_DEP_ERROR, + GFC_DEP_EQUAL, /* Identical Ranges. */ + GFC_DEP_FORWARD, /* e.g., a(1:3) = a(2:4). */ + GFC_DEP_BACKWARD, /* e.g. a(2:4) = a(1:3). */ + GFC_DEP_OVERLAP, /* May overlap in some other way. */ + GFC_DEP_NODEP /* Distinct ranges. */ +} +gfc_dependency; + +/* Macros */ +#define IS_ARRAY_EXPLICIT(as) ((as->type == AS_EXPLICIT ? 1 : 0)) + +/* Forward declarations */ + +static gfc_dependency check_section_vs_section (gfc_array_ref *, + gfc_array_ref *, int); + +/* Returns 1 if the expr is an integer constant value 1, 0 if it is not or + def if the value could not be determined. */ + +int +gfc_expr_is_one (gfc_expr *expr, int def) +{ + gcc_assert (expr != NULL); + + if (expr->expr_type != EXPR_CONSTANT) + return def; + + if (expr->ts.type != BT_INTEGER) + return def; + + return mpz_cmp_si (expr->value.integer, 1) == 0; +} + +/* Check if two array references are known to be identical. Calls + gfc_dep_compare_expr if necessary for comparing array indices. */ + +static bool +identical_array_ref (gfc_array_ref *a1, gfc_array_ref *a2) +{ + int i; + + if (a1->type == AR_FULL && a2->type == AR_FULL) + return true; + + if (a1->type == AR_SECTION && a2->type == AR_SECTION) + { + gcc_assert (a1->dimen == a2->dimen); + + for ( i = 0; i < a1->dimen; i++) + { + /* TODO: Currently, we punt on an integer array as an index. */ + if (a1->dimen_type[i] != DIMEN_RANGE + || a2->dimen_type[i] != DIMEN_RANGE) + return false; + + if (check_section_vs_section (a1, a2, i) != GFC_DEP_EQUAL) + return false; + } + return true; + } + + if (a1->type == AR_ELEMENT && a2->type == AR_ELEMENT) + { + gcc_assert (a1->dimen == a2->dimen); + for (i = 0; i < a1->dimen; i++) + { + if (gfc_dep_compare_expr (a1->start[i], a2->start[i]) != 0) + return false; + } + return true; + } + return false; +} + + + +/* Return true for identical variables, checking for references if + necessary. Calls identical_array_ref for checking array sections. */ + +bool +gfc_are_identical_variables (gfc_expr *e1, gfc_expr *e2) +{ + gfc_ref *r1, *r2; + + if (e1->symtree->n.sym != e2->symtree->n.sym) + return false; + + /* Volatile variables should never compare equal to themselves. */ + + if (e1->symtree->n.sym->attr.volatile_) + return false; + + r1 = e1->ref; + r2 = e2->ref; + + while (r1 != NULL || r2 != NULL) + { + + /* Assume the variables are not equal if one has a reference and the + other doesn't. + TODO: Handle full references like comparing a(:) to a. + */ + + if (r1 == NULL || r2 == NULL) + return false; + + if (r1->type != r2->type) + return false; + + switch (r1->type) + { + + case REF_ARRAY: + if (!identical_array_ref (&r1->u.ar, &r2->u.ar)) + return false; + + break; + + case REF_COMPONENT: + if (r1->u.c.component != r2->u.c.component) + return false; + break; + + case REF_SUBSTRING: + if (gfc_dep_compare_expr (r1->u.ss.start, r2->u.ss.start) != 0) + return false; + + /* If both are NULL, the end length compares equal, because we + are looking at the same variable. This can only happen for + assumed- or deferred-length character arguments. */ + + if (r1->u.ss.end == NULL && r2->u.ss.end == NULL) + break; + + if (gfc_dep_compare_expr (r1->u.ss.end, r2->u.ss.end) != 0) + return false; + + break; + + default: + gfc_internal_error ("gfc_are_identical_variables: Bad type"); + } + r1 = r1->next; + r2 = r2->next; + } + return true; +} + +/* Compare two values. Returns 0 if e1 == e2, -1 if e1 < e2, +1 if e1 > e2, + and -2 if the relationship could not be determined. */ + +int +gfc_dep_compare_expr (gfc_expr *e1, gfc_expr *e2) +{ + gfc_actual_arglist *args1; + gfc_actual_arglist *args2; + int i; + gfc_expr *n1, *n2; + + n1 = NULL; + n2 = NULL; + + /* Remove any integer conversion functions to larger types. */ + if (e1->expr_type == EXPR_FUNCTION && e1->value.function.isym + && e1->value.function.isym->id == GFC_ISYM_CONVERSION + && e1->ts.type == BT_INTEGER) + { + args1 = e1->value.function.actual; + if (args1->expr->ts.type == BT_INTEGER + && e1->ts.kind > args1->expr->ts.kind) + n1 = args1->expr; + } + + if (e2->expr_type == EXPR_FUNCTION && e2->value.function.isym + && e2->value.function.isym->id == GFC_ISYM_CONVERSION + && e2->ts.type == BT_INTEGER) + { + args2 = e2->value.function.actual; + if (args2->expr->ts.type == BT_INTEGER + && e2->ts.kind > args2->expr->ts.kind) + n2 = args2->expr; + } + + if (n1 != NULL) + { + if (n2 != NULL) + return gfc_dep_compare_expr (n1, n2); + else + return gfc_dep_compare_expr (n1, e2); + } + else + { + if (n2 != NULL) + return gfc_dep_compare_expr (e1, n2); + } + + if (e1->expr_type == EXPR_OP + && (e1->value.op.op == INTRINSIC_UPLUS + || e1->value.op.op == INTRINSIC_PARENTHESES)) + return gfc_dep_compare_expr (e1->value.op.op1, e2); + if (e2->expr_type == EXPR_OP + && (e2->value.op.op == INTRINSIC_UPLUS + || e2->value.op.op == INTRINSIC_PARENTHESES)) + return gfc_dep_compare_expr (e1, e2->value.op.op1); + + if (e1->expr_type == EXPR_OP && e1->value.op.op == INTRINSIC_PLUS) + { + /* Compare X+C vs. X. */ + if (e1->value.op.op2->expr_type == EXPR_CONSTANT + && e1->value.op.op2->ts.type == BT_INTEGER + && gfc_dep_compare_expr (e1->value.op.op1, e2) == 0) + return mpz_sgn (e1->value.op.op2->value.integer); + + /* Compare P+Q vs. R+S. */ + if (e2->expr_type == EXPR_OP && e2->value.op.op == INTRINSIC_PLUS) + { + int l, r; + + l = gfc_dep_compare_expr (e1->value.op.op1, e2->value.op.op1); + r = gfc_dep_compare_expr (e1->value.op.op2, e2->value.op.op2); + if (l == 0 && r == 0) + return 0; + if (l == 0 && r != -2) + return r; + if (l != -2 && r == 0) + return l; + if (l == 1 && r == 1) + return 1; + if (l == -1 && r == -1) + return -1; + + l = gfc_dep_compare_expr (e1->value.op.op1, e2->value.op.op2); + r = gfc_dep_compare_expr (e1->value.op.op2, e2->value.op.op1); + if (l == 0 && r == 0) + return 0; + if (l == 0 && r != -2) + return r; + if (l != -2 && r == 0) + return l; + if (l == 1 && r == 1) + return 1; + if (l == -1 && r == -1) + return -1; + } + } + + /* Compare X vs. X+C. */ + if (e2->expr_type == EXPR_OP && e2->value.op.op == INTRINSIC_PLUS) + { + if (e2->value.op.op2->expr_type == EXPR_CONSTANT + && e2->value.op.op2->ts.type == BT_INTEGER + && gfc_dep_compare_expr (e1, e2->value.op.op1) == 0) + return -mpz_sgn (e2->value.op.op2->value.integer); + } + + /* Compare X-C vs. X. */ + if (e1->expr_type == EXPR_OP && e1->value.op.op == INTRINSIC_MINUS) + { + if (e1->value.op.op2->expr_type == EXPR_CONSTANT + && e1->value.op.op2->ts.type == BT_INTEGER + && gfc_dep_compare_expr (e1->value.op.op1, e2) == 0) + return -mpz_sgn (e1->value.op.op2->value.integer); + + /* Compare P-Q vs. R-S. */ + if (e2->expr_type == EXPR_OP && e2->value.op.op == INTRINSIC_MINUS) + { + int l, r; + + l = gfc_dep_compare_expr (e1->value.op.op1, e2->value.op.op1); + r = gfc_dep_compare_expr (e1->value.op.op2, e2->value.op.op2); + if (l == 0 && r == 0) + return 0; + if (l != -2 && r == 0) + return l; + if (l == 0 && r != -2) + return -r; + if (l == 1 && r == -1) + return 1; + if (l == -1 && r == 1) + return -1; + } + } + + /* Compare A // B vs. C // D. */ + + if (e1->expr_type == EXPR_OP && e1->value.op.op == INTRINSIC_CONCAT + && e2->expr_type == EXPR_OP && e2->value.op.op == INTRINSIC_CONCAT) + { + int l, r; + + l = gfc_dep_compare_expr (e1->value.op.op1, e2->value.op.op1); + r = gfc_dep_compare_expr (e1->value.op.op2, e2->value.op.op2); + + if (l == -2) + return -2; + + if (l == 0) + { + /* Watch out for 'A ' // x vs. 'A' // x. */ + gfc_expr *e1_left = e1->value.op.op1; + gfc_expr *e2_left = e2->value.op.op1; + + if (e1_left->expr_type == EXPR_CONSTANT + && e2_left->expr_type == EXPR_CONSTANT + && e1_left->value.character.length + != e2_left->value.character.length) + return -2; + else + return r; + } + else + { + if (l != 0) + return l; + else + return r; + } + } + + /* Compare X vs. X-C. */ + if (e2->expr_type == EXPR_OP && e2->value.op.op == INTRINSIC_MINUS) + { + if (e2->value.op.op2->expr_type == EXPR_CONSTANT + && e2->value.op.op2->ts.type == BT_INTEGER + && gfc_dep_compare_expr (e1, e2->value.op.op1) == 0) + return mpz_sgn (e2->value.op.op2->value.integer); + } + + if (e1->expr_type != e2->expr_type) + return -2; + + switch (e1->expr_type) + { + case EXPR_CONSTANT: + /* Compare strings for equality. */ + if (e1->ts.type == BT_CHARACTER && e2->ts.type == BT_CHARACTER) + return gfc_compare_string (e1, e2); + + if (e1->ts.type != BT_INTEGER || e2->ts.type != BT_INTEGER) + return -2; + + i = mpz_cmp (e1->value.integer, e2->value.integer); + if (i == 0) + return 0; + else if (i < 0) + return -1; + return 1; + + case EXPR_VARIABLE: + if (gfc_are_identical_variables (e1, e2)) + return 0; + else + return -2; + + case EXPR_OP: + /* Intrinsic operators are the same if their operands are the same. */ + if (e1->value.op.op != e2->value.op.op) + return -2; + if (e1->value.op.op2 == 0) + { + i = gfc_dep_compare_expr (e1->value.op.op1, e2->value.op.op1); + return i == 0 ? 0 : -2; + } + if (gfc_dep_compare_expr (e1->value.op.op1, e2->value.op.op1) == 0 + && gfc_dep_compare_expr (e1->value.op.op2, e2->value.op.op2) == 0) + return 0; + /* TODO Handle commutative binary operators here? */ + return -2; + + case EXPR_FUNCTION: + + /* PURE functions can be compared for argument equality. */ + if ((e1->value.function.esym && e2->value.function.esym + && e1->value.function.esym == e2->value.function.esym + && e1->value.function.esym->result->attr.pure) + || (e1->value.function.isym && e2->value.function.isym + && e1->value.function.isym == e2->value.function.isym + && e1->value.function.isym->pure)) + { + args1 = e1->value.function.actual; + args2 = e2->value.function.actual; + + /* Compare the argument lists for equality. */ + while (args1 && args2) + { + /* Bitwise xor, since C has no non-bitwise xor operator. */ + if ((args1->expr == NULL) ^ (args2->expr == NULL)) + return -2; + + if (args1->expr != NULL && args2->expr != NULL + && gfc_dep_compare_expr (args1->expr, args2->expr) != 0) + return -2; + + args1 = args1->next; + args2 = args2->next; + } + return (args1 || args2) ? -2 : 0; + } + else + return -2; + break; + + default: + return -2; + } +} + + +/* Returns 1 if the two ranges are the same, 0 if they are not, and def + if the results are indeterminate. N is the dimension to compare. */ + +int +gfc_is_same_range (gfc_array_ref *ar1, gfc_array_ref *ar2, int n, int def) +{ + gfc_expr *e1; + gfc_expr *e2; + int i; + + /* TODO: More sophisticated range comparison. */ + gcc_assert (ar1 && ar2); + + gcc_assert (ar1->dimen_type[n] == ar2->dimen_type[n]); + + e1 = ar1->stride[n]; + e2 = ar2->stride[n]; + /* Check for mismatching strides. A NULL stride means a stride of 1. */ + if (e1 && !e2) + { + i = gfc_expr_is_one (e1, -1); + if (i == -1) + return def; + else if (i == 0) + return 0; + } + else if (e2 && !e1) + { + i = gfc_expr_is_one (e2, -1); + if (i == -1) + return def; + else if (i == 0) + return 0; + } + else if (e1 && e2) + { + i = gfc_dep_compare_expr (e1, e2); + if (i == -2) + return def; + else if (i != 0) + return 0; + } + /* The strides match. */ + + /* Check the range start. */ + e1 = ar1->start[n]; + e2 = ar2->start[n]; + if (e1 || e2) + { + /* Use the bound of the array if no bound is specified. */ + if (ar1->as && !e1) + e1 = ar1->as->lower[n]; + + if (ar2->as && !e2) + e2 = ar2->as->lower[n]; + + /* Check we have values for both. */ + if (!(e1 && e2)) + return def; + + i = gfc_dep_compare_expr (e1, e2); + if (i == -2) + return def; + else if (i != 0) + return 0; + } + + /* Check the range end. */ + e1 = ar1->end[n]; + e2 = ar2->end[n]; + if (e1 || e2) + { + /* Use the bound of the array if no bound is specified. */ + if (ar1->as && !e1) + e1 = ar1->as->upper[n]; + + if (ar2->as && !e2) + e2 = ar2->as->upper[n]; + + /* Check we have values for both. */ + if (!(e1 && e2)) + return def; + + i = gfc_dep_compare_expr (e1, e2); + if (i == -2) + return def; + else if (i != 0) + return 0; + } + + return 1; +} + + +/* Some array-returning intrinsics can be implemented by reusing the + data from one of the array arguments. For example, TRANSPOSE does + not necessarily need to allocate new data: it can be implemented + by copying the original array's descriptor and simply swapping the + two dimension specifications. + + If EXPR is a call to such an intrinsic, return the argument + whose data can be reused, otherwise return NULL. */ + +gfc_expr * +gfc_get_noncopying_intrinsic_argument (gfc_expr *expr) +{ + if (expr->expr_type != EXPR_FUNCTION || !expr->value.function.isym) + return NULL; + + switch (expr->value.function.isym->id) + { + case GFC_ISYM_TRANSPOSE: + return expr->value.function.actual->expr; + + default: + return NULL; + } +} + + +/* Return true if the result of reference REF can only be constructed + using a temporary array. */ + +bool +gfc_ref_needs_temporary_p (gfc_ref *ref) +{ + int n; + bool subarray_p; + + subarray_p = false; + for (; ref; ref = ref->next) + switch (ref->type) + { + case REF_ARRAY: + /* Vector dimensions are generally not monotonic and must be + handled using a temporary. */ + if (ref->u.ar.type == AR_SECTION) + for (n = 0; n < ref->u.ar.dimen; n++) + if (ref->u.ar.dimen_type[n] == DIMEN_VECTOR) + return true; + + subarray_p = true; + break; + + case REF_SUBSTRING: + /* Within an array reference, character substrings generally + need a temporary. Character array strides are expressed as + multiples of the element size (consistent with other array + types), not in characters. */ + return subarray_p; + + case REF_COMPONENT: + break; + } + + return false; +} + + +static int +gfc_is_data_pointer (gfc_expr *e) +{ + gfc_ref *ref; + + if (e->expr_type != EXPR_VARIABLE && e->expr_type != EXPR_FUNCTION) + return 0; + + /* No subreference if it is a function */ + gcc_assert (e->expr_type == EXPR_VARIABLE || !e->ref); + + if (e->symtree->n.sym->attr.pointer) + return 1; + + for (ref = e->ref; ref; ref = ref->next) + if (ref->type == REF_COMPONENT && ref->u.c.component->attr.pointer) + return 1; + + return 0; +} + + +/* Return true if array variable VAR could be passed to the same function + as argument EXPR without interfering with EXPR. INTENT is the intent + of VAR. + + This is considerably less conservative than other dependencies + because many function arguments will already be copied into a + temporary. */ + +static int +gfc_check_argument_var_dependency (gfc_expr *var, sym_intent intent, + gfc_expr *expr, gfc_dep_check elemental) +{ + gfc_expr *arg; + + gcc_assert (var->expr_type == EXPR_VARIABLE); + gcc_assert (var->rank > 0); + + switch (expr->expr_type) + { + case EXPR_VARIABLE: + /* In case of elemental subroutines, there is no dependency + between two same-range array references. */ + if (gfc_ref_needs_temporary_p (expr->ref) + || gfc_check_dependency (var, expr, elemental == NOT_ELEMENTAL)) + { + if (elemental == ELEM_DONT_CHECK_VARIABLE) + { + /* Too many false positive with pointers. */ + if (!gfc_is_data_pointer (var) && !gfc_is_data_pointer (expr)) + { + /* Elemental procedures forbid unspecified intents, + and we don't check dependencies for INTENT_IN args. */ + gcc_assert (intent == INTENT_OUT || intent == INTENT_INOUT); + + /* We are told not to check dependencies. + We do it, however, and issue a warning in case we find one. + If a dependency is found in the case + elemental == ELEM_CHECK_VARIABLE, we will generate + a temporary, so we don't need to bother the user. */ + gfc_warning ("INTENT(%s) actual argument at %L might " + "interfere with actual argument at %L.", + intent == INTENT_OUT ? "OUT" : "INOUT", + &var->where, &expr->where); + } + return 0; + } + else + return 1; + } + return 0; + + case EXPR_ARRAY: + return gfc_check_dependency (var, expr, 1); + + case EXPR_FUNCTION: + if (intent != INTENT_IN) + { + arg = gfc_get_noncopying_intrinsic_argument (expr); + if (arg != NULL) + return gfc_check_argument_var_dependency (var, intent, arg, + NOT_ELEMENTAL); + } + + if (elemental != NOT_ELEMENTAL) + { + if ((expr->value.function.esym + && expr->value.function.esym->attr.elemental) + || (expr->value.function.isym + && expr->value.function.isym->elemental)) + return gfc_check_fncall_dependency (var, intent, NULL, + expr->value.function.actual, + ELEM_CHECK_VARIABLE); + } + return 0; + + case EXPR_OP: + /* In case of non-elemental procedures, there is no need to catch + dependencies, as we will make a temporary anyway. */ + if (elemental) + { + /* If the actual arg EXPR is an expression, we need to catch + a dependency between variables in EXPR and VAR, + an intent((IN)OUT) variable. */ + if (expr->value.op.op1 + && gfc_check_argument_var_dependency (var, intent, + expr->value.op.op1, + ELEM_CHECK_VARIABLE)) + return 1; + else if (expr->value.op.op2 + && gfc_check_argument_var_dependency (var, intent, + expr->value.op.op2, + ELEM_CHECK_VARIABLE)) + return 1; + } + return 0; + + default: + return 0; + } +} + + +/* Like gfc_check_argument_var_dependency, but extended to any + array expression OTHER, not just variables. */ + +static int +gfc_check_argument_dependency (gfc_expr *other, sym_intent intent, + gfc_expr *expr, gfc_dep_check elemental) +{ + switch (other->expr_type) + { + case EXPR_VARIABLE: + return gfc_check_argument_var_dependency (other, intent, expr, elemental); + + case EXPR_FUNCTION: + other = gfc_get_noncopying_intrinsic_argument (other); + if (other != NULL) + return gfc_check_argument_dependency (other, INTENT_IN, expr, + NOT_ELEMENTAL); + + return 0; + + default: + return 0; + } +} + + +/* Like gfc_check_argument_dependency, but check all the arguments in ACTUAL. + FNSYM is the function being called, or NULL if not known. */ + +int +gfc_check_fncall_dependency (gfc_expr *other, sym_intent intent, + gfc_symbol *fnsym, gfc_actual_arglist *actual, + gfc_dep_check elemental) +{ + gfc_formal_arglist *formal; + gfc_expr *expr; + + formal = fnsym ? fnsym->formal : NULL; + for (; actual; actual = actual->next, formal = formal ? formal->next : NULL) + { + expr = actual->expr; + + /* Skip args which are not present. */ + if (!expr) + continue; + + /* Skip other itself. */ + if (expr == other) + continue; + + /* Skip intent(in) arguments if OTHER itself is intent(in). */ + if (formal && intent == INTENT_IN + && formal->sym->attr.intent == INTENT_IN) + continue; + + if (gfc_check_argument_dependency (other, intent, expr, elemental)) + return 1; + } + + return 0; +} + + +/* Return 1 if e1 and e2 are equivalenced arrays, either + directly or indirectly; i.e., equivalence (a,b) for a and b + or equivalence (a,c),(b,c). This function uses the equiv_ + lists, generated in trans-common(add_equivalences), that are + guaranteed to pick up indirect equivalences. We explicitly + check for overlap using the offset and length of the equivalence. + This function is symmetric. + TODO: This function only checks whether the full top-level + symbols overlap. An improved implementation could inspect + e1->ref and e2->ref to determine whether the actually accessed + portions of these variables/arrays potentially overlap. */ + +int +gfc_are_equivalenced_arrays (gfc_expr *e1, gfc_expr *e2) +{ + gfc_equiv_list *l; + gfc_equiv_info *s, *fl1, *fl2; + + gcc_assert (e1->expr_type == EXPR_VARIABLE + && e2->expr_type == EXPR_VARIABLE); + + if (!e1->symtree->n.sym->attr.in_equivalence + || !e2->symtree->n.sym->attr.in_equivalence|| !e1->rank || !e2->rank) + return 0; + + if (e1->symtree->n.sym->ns + && e1->symtree->n.sym->ns != gfc_current_ns) + l = e1->symtree->n.sym->ns->equiv_lists; + else + l = gfc_current_ns->equiv_lists; + + /* Go through the equiv_lists and return 1 if the variables + e1 and e2 are members of the same group and satisfy the + requirement on their relative offsets. */ + for (; l; l = l->next) + { + fl1 = NULL; + fl2 = NULL; + for (s = l->equiv; s; s = s->next) + { + if (s->sym == e1->symtree->n.sym) + { + fl1 = s; + if (fl2) + break; + } + if (s->sym == e2->symtree->n.sym) + { + fl2 = s; + if (fl1) + break; + } + } + + if (s) + { + /* Can these lengths be zero? */ + if (fl1->length <= 0 || fl2->length <= 0) + return 1; + /* These can't overlap if [f11,fl1+length] is before + [fl2,fl2+length], or [fl2,fl2+length] is before + [fl1,fl1+length], otherwise they do overlap. */ + if (fl1->offset + fl1->length > fl2->offset + && fl2->offset + fl2->length > fl1->offset) + return 1; + } + } + return 0; +} + + +/* Return true if there is no possibility of aliasing because of a type + mismatch between all the possible pointer references and the + potential target. Note that this function is asymmetric in the + arguments and so must be called twice with the arguments exchanged. */ + +static bool +check_data_pointer_types (gfc_expr *expr1, gfc_expr *expr2) +{ + gfc_component *cm1; + gfc_symbol *sym1; + gfc_symbol *sym2; + gfc_ref *ref1; + bool seen_component_ref; + + if (expr1->expr_type != EXPR_VARIABLE + || expr1->expr_type != EXPR_VARIABLE) + return false; + + sym1 = expr1->symtree->n.sym; + sym2 = expr2->symtree->n.sym; + + /* Keep it simple for now. */ + if (sym1->ts.type == BT_DERIVED && sym2->ts.type == BT_DERIVED) + return false; + + if (sym1->attr.pointer) + { + if (gfc_compare_types (&sym1->ts, &sym2->ts)) + return false; + } + + /* This is a conservative check on the components of the derived type + if no component references have been seen. Since we will not dig + into the components of derived type components, we play it safe by + returning false. First we check the reference chain and then, if + no component references have been seen, the components. */ + seen_component_ref = false; + if (sym1->ts.type == BT_DERIVED) + { + for (ref1 = expr1->ref; ref1; ref1 = ref1->next) + { + if (ref1->type != REF_COMPONENT) + continue; + + if (ref1->u.c.component->ts.type == BT_DERIVED) + return false; + + if ((sym2->attr.pointer || ref1->u.c.component->attr.pointer) + && gfc_compare_types (&ref1->u.c.component->ts, &sym2->ts)) + return false; + + seen_component_ref = true; + } + } + + if (sym1->ts.type == BT_DERIVED && !seen_component_ref) + { + for (cm1 = sym1->ts.u.derived->components; cm1; cm1 = cm1->next) + { + if (cm1->ts.type == BT_DERIVED) + return false; + + if ((sym2->attr.pointer || cm1->attr.pointer) + && gfc_compare_types (&cm1->ts, &sym2->ts)) + return false; + } + } + + return true; +} + + +/* Return true if the statement body redefines the condition. Returns + true if expr2 depends on expr1. expr1 should be a single term + suitable for the lhs of an assignment. The IDENTICAL flag indicates + whether array references to the same symbol with identical range + references count as a dependency or not. Used for forall and where + statements. Also used with functions returning arrays without a + temporary. */ + +int +gfc_check_dependency (gfc_expr *expr1, gfc_expr *expr2, bool identical) +{ + gfc_actual_arglist *actual; + gfc_constructor *c; + int n; + + gcc_assert (expr1->expr_type == EXPR_VARIABLE); + + switch (expr2->expr_type) + { + case EXPR_OP: + n = gfc_check_dependency (expr1, expr2->value.op.op1, identical); + if (n) + return n; + if (expr2->value.op.op2) + return gfc_check_dependency (expr1, expr2->value.op.op2, identical); + return 0; + + case EXPR_VARIABLE: + /* The interesting cases are when the symbols don't match. */ + if (expr1->symtree->n.sym != expr2->symtree->n.sym) + { + gfc_typespec *ts1 = &expr1->symtree->n.sym->ts; + gfc_typespec *ts2 = &expr2->symtree->n.sym->ts; + + /* Return 1 if expr1 and expr2 are equivalenced arrays. */ + if (gfc_are_equivalenced_arrays (expr1, expr2)) + return 1; + + /* Symbols can only alias if they have the same type. */ + if (ts1->type != BT_UNKNOWN && ts2->type != BT_UNKNOWN + && ts1->type != BT_DERIVED && ts2->type != BT_DERIVED) + { + if (ts1->type != ts2->type || ts1->kind != ts2->kind) + return 0; + } + + /* If either variable is a pointer, assume the worst. */ + /* TODO: -fassume-no-pointer-aliasing */ + if (gfc_is_data_pointer (expr1) || gfc_is_data_pointer (expr2)) + { + if (check_data_pointer_types (expr1, expr2) + && check_data_pointer_types (expr2, expr1)) + return 0; + + return 1; + } + else + { + gfc_symbol *sym1 = expr1->symtree->n.sym; + gfc_symbol *sym2 = expr2->symtree->n.sym; + if (sym1->attr.target && sym2->attr.target + && ((sym1->attr.dummy && !sym1->attr.contiguous + && (!sym1->attr.dimension + || sym2->as->type == AS_ASSUMED_SHAPE)) + || (sym2->attr.dummy && !sym2->attr.contiguous + && (!sym2->attr.dimension + || sym2->as->type == AS_ASSUMED_SHAPE)))) + return 1; + } + + /* Otherwise distinct symbols have no dependencies. */ + return 0; + } + + if (identical) + return 1; + + /* Identical and disjoint ranges return 0, + overlapping ranges return 1. */ + if (expr1->ref && expr2->ref) + return gfc_dep_resolver (expr1->ref, expr2->ref, NULL); + + return 1; + + case EXPR_FUNCTION: + if (gfc_get_noncopying_intrinsic_argument (expr2) != NULL) + identical = 1; + + /* Remember possible differences between elemental and + transformational functions. All functions inside a FORALL + will be pure. */ + for (actual = expr2->value.function.actual; + actual; actual = actual->next) + { + if (!actual->expr) + continue; + n = gfc_check_dependency (expr1, actual->expr, identical); + if (n) + return n; + } + return 0; + + case EXPR_CONSTANT: + case EXPR_NULL: + return 0; + + case EXPR_ARRAY: + /* Loop through the array constructor's elements. */ + for (c = gfc_constructor_first (expr2->value.constructor); + c; c = gfc_constructor_next (c)) + { + /* If this is an iterator, assume the worst. */ + if (c->iterator) + return 1; + /* Avoid recursion in the common case. */ + if (c->expr->expr_type == EXPR_CONSTANT) + continue; + if (gfc_check_dependency (expr1, c->expr, 1)) + return 1; + } + return 0; + + default: + return 1; + } +} + + +/* Determines overlapping for two array sections. */ + +static gfc_dependency +check_section_vs_section (gfc_array_ref *l_ar, gfc_array_ref *r_ar, int n) +{ + gfc_expr *l_start; + gfc_expr *l_end; + gfc_expr *l_stride; + gfc_expr *l_lower; + gfc_expr *l_upper; + int l_dir; + + gfc_expr *r_start; + gfc_expr *r_end; + gfc_expr *r_stride; + gfc_expr *r_lower; + gfc_expr *r_upper; + gfc_expr *one_expr; + int r_dir; + int stride_comparison; + int start_comparison; + + /* If they are the same range, return without more ado. */ + if (gfc_is_same_range (l_ar, r_ar, n, 0)) + return GFC_DEP_EQUAL; + + l_start = l_ar->start[n]; + l_end = l_ar->end[n]; + l_stride = l_ar->stride[n]; + + r_start = r_ar->start[n]; + r_end = r_ar->end[n]; + r_stride = r_ar->stride[n]; + + /* If l_start is NULL take it from array specifier. */ + if (NULL == l_start && IS_ARRAY_EXPLICIT (l_ar->as)) + l_start = l_ar->as->lower[n]; + /* If l_end is NULL take it from array specifier. */ + if (NULL == l_end && IS_ARRAY_EXPLICIT (l_ar->as)) + l_end = l_ar->as->upper[n]; + + /* If r_start is NULL take it from array specifier. */ + if (NULL == r_start && IS_ARRAY_EXPLICIT (r_ar->as)) + r_start = r_ar->as->lower[n]; + /* If r_end is NULL take it from array specifier. */ + if (NULL == r_end && IS_ARRAY_EXPLICIT (r_ar->as)) + r_end = r_ar->as->upper[n]; + + /* Determine whether the l_stride is positive or negative. */ + if (!l_stride) + l_dir = 1; + else if (l_stride->expr_type == EXPR_CONSTANT + && l_stride->ts.type == BT_INTEGER) + l_dir = mpz_sgn (l_stride->value.integer); + else if (l_start && l_end) + l_dir = gfc_dep_compare_expr (l_end, l_start); + else + l_dir = -2; + + /* Determine whether the r_stride is positive or negative. */ + if (!r_stride) + r_dir = 1; + else if (r_stride->expr_type == EXPR_CONSTANT + && r_stride->ts.type == BT_INTEGER) + r_dir = mpz_sgn (r_stride->value.integer); + else if (r_start && r_end) + r_dir = gfc_dep_compare_expr (r_end, r_start); + else + r_dir = -2; + + /* The strides should never be zero. */ + if (l_dir == 0 || r_dir == 0) + return GFC_DEP_OVERLAP; + + /* Determine the relationship between the strides. Set stride_comparison to + -2 if the dependency cannot be determined + -1 if l_stride < r_stride + 0 if l_stride == r_stride + 1 if l_stride > r_stride + as determined by gfc_dep_compare_expr. */ + + one_expr = gfc_get_int_expr (gfc_index_integer_kind, NULL, 1); + + stride_comparison = gfc_dep_compare_expr (l_stride ? l_stride : one_expr, + r_stride ? r_stride : one_expr); + + if (l_start && r_start) + start_comparison = gfc_dep_compare_expr (l_start, r_start); + else + start_comparison = -2; + + gfc_free (one_expr); + + /* Determine LHS upper and lower bounds. */ + if (l_dir == 1) + { + l_lower = l_start; + l_upper = l_end; + } + else if (l_dir == -1) + { + l_lower = l_end; + l_upper = l_start; + } + else + { + l_lower = NULL; + l_upper = NULL; + } + + /* Determine RHS upper and lower bounds. */ + if (r_dir == 1) + { + r_lower = r_start; + r_upper = r_end; + } + else if (r_dir == -1) + { + r_lower = r_end; + r_upper = r_start; + } + else + { + r_lower = NULL; + r_upper = NULL; + } + + /* Check whether the ranges are disjoint. */ + if (l_upper && r_lower && gfc_dep_compare_expr (l_upper, r_lower) == -1) + return GFC_DEP_NODEP; + if (r_upper && l_lower && gfc_dep_compare_expr (r_upper, l_lower) == -1) + return GFC_DEP_NODEP; + + /* Handle cases like x:y:1 vs. x:z:-1 as GFC_DEP_EQUAL. */ + if (l_start && r_start && gfc_dep_compare_expr (l_start, r_start) == 0) + { + if (l_dir == 1 && r_dir == -1) + return GFC_DEP_EQUAL; + if (l_dir == -1 && r_dir == 1) + return GFC_DEP_EQUAL; + } + + /* Handle cases like x:y:1 vs. z:y:-1 as GFC_DEP_EQUAL. */ + if (l_end && r_end && gfc_dep_compare_expr (l_end, r_end) == 0) + { + if (l_dir == 1 && r_dir == -1) + return GFC_DEP_EQUAL; + if (l_dir == -1 && r_dir == 1) + return GFC_DEP_EQUAL; + } + + /* Handle cases like x:y:2 vs. x+1:z:4 as GFC_DEP_NODEP. + There is no dependency if the remainder of + (l_start - r_start) / gcd(l_stride, r_stride) is + nonzero. + TODO: + - Handle cases where x is an expression. + - Cases like a(1:4:2) = a(2:3) are still not handled. + */ + +#define IS_CONSTANT_INTEGER(a) ((a) && ((a)->expr_type == EXPR_CONSTANT) \ + && (a)->ts.type == BT_INTEGER) + + if (IS_CONSTANT_INTEGER(l_start) && IS_CONSTANT_INTEGER(r_start) + && IS_CONSTANT_INTEGER(l_stride) && IS_CONSTANT_INTEGER(r_stride)) + { + mpz_t gcd, tmp; + int result; + + mpz_init (gcd); + mpz_init (tmp); + + mpz_gcd (gcd, l_stride->value.integer, r_stride->value.integer); + mpz_sub (tmp, l_start->value.integer, r_start->value.integer); + + mpz_fdiv_r (tmp, tmp, gcd); + result = mpz_cmp_si (tmp, 0L); + + mpz_clear (gcd); + mpz_clear (tmp); + + if (result != 0) + return GFC_DEP_NODEP; + } + +#undef IS_CONSTANT_INTEGER + + /* Check for forward dependencies x:y vs. x+1:z and x:y:z vs. x:y:z+1. */ + + if (l_dir == 1 && r_dir == 1 && + (start_comparison == 0 || start_comparison == -1) + && (stride_comparison == 0 || stride_comparison == -1)) + return GFC_DEP_FORWARD; + + /* Check for forward dependencies x:y:-1 vs. x-1:z:-1 and + x:y:-1 vs. x:y:-2. */ + if (l_dir == -1 && r_dir == -1 && + (start_comparison == 0 || start_comparison == 1) + && (stride_comparison == 0 || stride_comparison == 1)) + return GFC_DEP_FORWARD; + + if (stride_comparison == 0 || stride_comparison == -1) + { + if (l_start && IS_ARRAY_EXPLICIT (l_ar->as)) + { + + /* Check for a(low:y:s) vs. a(z:x:s) or + a(low:y:s) vs. a(z:x:s+1) where a has a lower bound + of low, which is always at least a forward dependence. */ + + if (r_dir == 1 + && gfc_dep_compare_expr (l_start, l_ar->as->lower[n]) == 0) + return GFC_DEP_FORWARD; + } + } + + if (stride_comparison == 0 || stride_comparison == 1) + { + if (l_start && IS_ARRAY_EXPLICIT (l_ar->as)) + { + + /* Check for a(high:y:-s) vs. a(z:x:-s) or + a(high:y:-s vs. a(z:x:-s-1) where a has a higher bound + of high, which is always at least a forward dependence. */ + + if (r_dir == -1 + && gfc_dep_compare_expr (l_start, l_ar->as->upper[n]) == 0) + return GFC_DEP_FORWARD; + } + } + + + if (stride_comparison == 0) + { + /* From here, check for backwards dependencies. */ + /* x+1:y vs. x:z. */ + if (l_dir == 1 && r_dir == 1 && start_comparison == 1) + return GFC_DEP_BACKWARD; + + /* x-1:y:-1 vs. x:z:-1. */ + if (l_dir == -1 && r_dir == -1 && start_comparison == -1) + return GFC_DEP_BACKWARD; + } + + return GFC_DEP_OVERLAP; +} + + +/* Determines overlapping for a single element and a section. */ + +static gfc_dependency +gfc_check_element_vs_section( gfc_ref *lref, gfc_ref *rref, int n) +{ + gfc_array_ref *ref; + gfc_expr *elem; + gfc_expr *start; + gfc_expr *end; + gfc_expr *stride; + int s; + + elem = lref->u.ar.start[n]; + if (!elem) + return GFC_DEP_OVERLAP; + + ref = &rref->u.ar; + start = ref->start[n] ; + end = ref->end[n] ; + stride = ref->stride[n]; + + if (!start && IS_ARRAY_EXPLICIT (ref->as)) + start = ref->as->lower[n]; + if (!end && IS_ARRAY_EXPLICIT (ref->as)) + end = ref->as->upper[n]; + + /* Determine whether the stride is positive or negative. */ + if (!stride) + s = 1; + else if (stride->expr_type == EXPR_CONSTANT + && stride->ts.type == BT_INTEGER) + s = mpz_sgn (stride->value.integer); + else + s = -2; + + /* Stride should never be zero. */ + if (s == 0) + return GFC_DEP_OVERLAP; + + /* Positive strides. */ + if (s == 1) + { + /* Check for elem < lower. */ + if (start && gfc_dep_compare_expr (elem, start) == -1) + return GFC_DEP_NODEP; + /* Check for elem > upper. */ + if (end && gfc_dep_compare_expr (elem, end) == 1) + return GFC_DEP_NODEP; + + if (start && end) + { + s = gfc_dep_compare_expr (start, end); + /* Check for an empty range. */ + if (s == 1) + return GFC_DEP_NODEP; + if (s == 0 && gfc_dep_compare_expr (elem, start) == 0) + return GFC_DEP_EQUAL; + } + } + /* Negative strides. */ + else if (s == -1) + { + /* Check for elem > upper. */ + if (end && gfc_dep_compare_expr (elem, start) == 1) + return GFC_DEP_NODEP; + /* Check for elem < lower. */ + if (start && gfc_dep_compare_expr (elem, end) == -1) + return GFC_DEP_NODEP; + + if (start && end) + { + s = gfc_dep_compare_expr (start, end); + /* Check for an empty range. */ + if (s == -1) + return GFC_DEP_NODEP; + if (s == 0 && gfc_dep_compare_expr (elem, start) == 0) + return GFC_DEP_EQUAL; + } + } + /* Unknown strides. */ + else + { + if (!start || !end) + return GFC_DEP_OVERLAP; + s = gfc_dep_compare_expr (start, end); + if (s == -2) + return GFC_DEP_OVERLAP; + /* Assume positive stride. */ + if (s == -1) + { + /* Check for elem < lower. */ + if (gfc_dep_compare_expr (elem, start) == -1) + return GFC_DEP_NODEP; + /* Check for elem > upper. */ + if (gfc_dep_compare_expr (elem, end) == 1) + return GFC_DEP_NODEP; + } + /* Assume negative stride. */ + else if (s == 1) + { + /* Check for elem > upper. */ + if (gfc_dep_compare_expr (elem, start) == 1) + return GFC_DEP_NODEP; + /* Check for elem < lower. */ + if (gfc_dep_compare_expr (elem, end) == -1) + return GFC_DEP_NODEP; + } + /* Equal bounds. */ + else if (s == 0) + { + s = gfc_dep_compare_expr (elem, start); + if (s == 0) + return GFC_DEP_EQUAL; + if (s == 1 || s == -1) + return GFC_DEP_NODEP; + } + } + + return GFC_DEP_OVERLAP; +} + + +/* Traverse expr, checking all EXPR_VARIABLE symbols for their + forall_index attribute. Return true if any variable may be + being used as a FORALL index. Its safe to pessimistically + return true, and assume a dependency. */ + +static bool +contains_forall_index_p (gfc_expr *expr) +{ + gfc_actual_arglist *arg; + gfc_constructor *c; + gfc_ref *ref; + int i; + + if (!expr) + return false; + + switch (expr->expr_type) + { + case EXPR_VARIABLE: + if (expr->symtree->n.sym->forall_index) + return true; + break; + + case EXPR_OP: + if (contains_forall_index_p (expr->value.op.op1) + || contains_forall_index_p (expr->value.op.op2)) + return true; + break; + + case EXPR_FUNCTION: + for (arg = expr->value.function.actual; arg; arg = arg->next) + if (contains_forall_index_p (arg->expr)) + return true; + break; + + case EXPR_CONSTANT: + case EXPR_NULL: + case EXPR_SUBSTRING: + break; + + case EXPR_STRUCTURE: + case EXPR_ARRAY: + for (c = gfc_constructor_first (expr->value.constructor); + c; gfc_constructor_next (c)) + if (contains_forall_index_p (c->expr)) + return true; + break; + + default: + gcc_unreachable (); + } + + for (ref = expr->ref; ref; ref = ref->next) + switch (ref->type) + { + case REF_ARRAY: + for (i = 0; i < ref->u.ar.dimen; i++) + if (contains_forall_index_p (ref->u.ar.start[i]) + || contains_forall_index_p (ref->u.ar.end[i]) + || contains_forall_index_p (ref->u.ar.stride[i])) + return true; + break; + + case REF_COMPONENT: + break; + + case REF_SUBSTRING: + if (contains_forall_index_p (ref->u.ss.start) + || contains_forall_index_p (ref->u.ss.end)) + return true; + break; + + default: + gcc_unreachable (); + } + + return false; +} + +/* Determines overlapping for two single element array references. */ + +static gfc_dependency +gfc_check_element_vs_element (gfc_ref *lref, gfc_ref *rref, int n) +{ + gfc_array_ref l_ar; + gfc_array_ref r_ar; + gfc_expr *l_start; + gfc_expr *r_start; + int i; + + l_ar = lref->u.ar; + r_ar = rref->u.ar; + l_start = l_ar.start[n] ; + r_start = r_ar.start[n] ; + i = gfc_dep_compare_expr (r_start, l_start); + if (i == 0) + return GFC_DEP_EQUAL; + + /* Treat two scalar variables as potentially equal. This allows + us to prove that a(i,:) and a(j,:) have no dependency. See + Gerald Roth, "Evaluation of Array Syntax Dependence Analysis", + Proceedings of the International Conference on Parallel and + Distributed Processing Techniques and Applications (PDPTA2001), + Las Vegas, Nevada, June 2001. */ + /* However, we need to be careful when either scalar expression + contains a FORALL index, as these can potentially change value + during the scalarization/traversal of this array reference. */ + if (contains_forall_index_p (r_start) || contains_forall_index_p (l_start)) + return GFC_DEP_OVERLAP; + + if (i != -2) + return GFC_DEP_NODEP; + return GFC_DEP_EQUAL; +} + + +/* Determine if an array ref, usually an array section specifies the + entire array. In addition, if the second, pointer argument is + provided, the function will return true if the reference is + contiguous; eg. (:, 1) gives true but (1,:) gives false. */ + +bool +gfc_full_array_ref_p (gfc_ref *ref, bool *contiguous) +{ + int i; + int n; + bool lbound_OK = true; + bool ubound_OK = true; + + if (contiguous) + *contiguous = false; + + if (ref->type != REF_ARRAY) + return false; + + if (ref->u.ar.type == AR_FULL) + { + if (contiguous) + *contiguous = true; + return true; + } + + if (ref->u.ar.type != AR_SECTION) + return false; + if (ref->next) + return false; + + for (i = 0; i < ref->u.ar.dimen; i++) + { + /* If we have a single element in the reference, for the reference + to be full, we need to ascertain that the array has a single + element in this dimension and that we actually reference the + correct element. */ + if (ref->u.ar.dimen_type[i] == DIMEN_ELEMENT) + { + /* This is unconditionally a contiguous reference if all the + remaining dimensions are elements. */ + if (contiguous) + { + *contiguous = true; + for (n = i + 1; n < ref->u.ar.dimen; n++) + if (ref->u.ar.dimen_type[n] != DIMEN_ELEMENT) + *contiguous = false; + } + + if (!ref->u.ar.as + || !ref->u.ar.as->lower[i] + || !ref->u.ar.as->upper[i] + || gfc_dep_compare_expr (ref->u.ar.as->lower[i], + ref->u.ar.as->upper[i]) + || !ref->u.ar.start[i] + || gfc_dep_compare_expr (ref->u.ar.start[i], + ref->u.ar.as->lower[i])) + return false; + else + continue; + } + + /* Check the lower bound. */ + if (ref->u.ar.start[i] + && (!ref->u.ar.as + || !ref->u.ar.as->lower[i] + || gfc_dep_compare_expr (ref->u.ar.start[i], + ref->u.ar.as->lower[i]))) + lbound_OK = false; + /* Check the upper bound. */ + if (ref->u.ar.end[i] + && (!ref->u.ar.as + || !ref->u.ar.as->upper[i] + || gfc_dep_compare_expr (ref->u.ar.end[i], + ref->u.ar.as->upper[i]))) + ubound_OK = false; + /* Check the stride. */ + if (ref->u.ar.stride[i] + && !gfc_expr_is_one (ref->u.ar.stride[i], 0)) + return false; + + /* This is unconditionally a contiguous reference as long as all + the subsequent dimensions are elements. */ + if (contiguous) + { + *contiguous = true; + for (n = i + 1; n < ref->u.ar.dimen; n++) + if (ref->u.ar.dimen_type[n] != DIMEN_ELEMENT) + *contiguous = false; + } + + if (!lbound_OK || !ubound_OK) + return false; + } + return true; +} + + +/* Determine if a full array is the same as an array section with one + variable limit. For this to be so, the strides must both be unity + and one of either start == lower or end == upper must be true. */ + +static bool +ref_same_as_full_array (gfc_ref *full_ref, gfc_ref *ref) +{ + int i; + bool upper_or_lower; + + if (full_ref->type != REF_ARRAY) + return false; + if (full_ref->u.ar.type != AR_FULL) + return false; + if (ref->type != REF_ARRAY) + return false; + if (ref->u.ar.type != AR_SECTION) + return false; + + for (i = 0; i < ref->u.ar.dimen; i++) + { + /* If we have a single element in the reference, we need to check + that the array has a single element and that we actually reference + the correct element. */ + if (ref->u.ar.dimen_type[i] == DIMEN_ELEMENT) + { + if (!full_ref->u.ar.as + || !full_ref->u.ar.as->lower[i] + || !full_ref->u.ar.as->upper[i] + || gfc_dep_compare_expr (full_ref->u.ar.as->lower[i], + full_ref->u.ar.as->upper[i]) + || !ref->u.ar.start[i] + || gfc_dep_compare_expr (ref->u.ar.start[i], + full_ref->u.ar.as->lower[i])) + return false; + } + + /* Check the strides. */ + if (full_ref->u.ar.stride[i] && !gfc_expr_is_one (full_ref->u.ar.stride[i], 0)) + return false; + if (ref->u.ar.stride[i] && !gfc_expr_is_one (ref->u.ar.stride[i], 0)) + return false; + + upper_or_lower = false; + /* Check the lower bound. */ + if (ref->u.ar.start[i] + && (ref->u.ar.as + && full_ref->u.ar.as->lower[i] + && gfc_dep_compare_expr (ref->u.ar.start[i], + full_ref->u.ar.as->lower[i]) == 0)) + upper_or_lower = true; + /* Check the upper bound. */ + if (ref->u.ar.end[i] + && (ref->u.ar.as + && full_ref->u.ar.as->upper[i] + && gfc_dep_compare_expr (ref->u.ar.end[i], + full_ref->u.ar.as->upper[i]) == 0)) + upper_or_lower = true; + if (!upper_or_lower) + return false; + } + return true; +} + + +/* Finds if two array references are overlapping or not. + Return value + 2 : array references are overlapping but reversal of one or + more dimensions will clear the dependency. + 1 : array references are overlapping. + 0 : array references are identical or not overlapping. */ + +int +gfc_dep_resolver (gfc_ref *lref, gfc_ref *rref, gfc_reverse *reverse) +{ + int n; + gfc_dependency fin_dep; + gfc_dependency this_dep; + + this_dep = GFC_DEP_ERROR; + fin_dep = GFC_DEP_ERROR; + /* Dependencies due to pointers should already have been identified. + We only need to check for overlapping array references. */ + + while (lref && rref) + { + /* We're resolving from the same base symbol, so both refs should be + the same type. We traverse the reference chain until we find ranges + that are not equal. */ + gcc_assert (lref->type == rref->type); + switch (lref->type) + { + case REF_COMPONENT: + /* The two ranges can't overlap if they are from different + components. */ + if (lref->u.c.component != rref->u.c.component) + return 0; + break; + + case REF_SUBSTRING: + /* Substring overlaps are handled by the string assignment code + if there is not an underlying dependency. */ + return (fin_dep == GFC_DEP_OVERLAP) ? 1 : 0; + + case REF_ARRAY: + + if (ref_same_as_full_array (lref, rref)) + return 0; + + if (ref_same_as_full_array (rref, lref)) + return 0; + + if (lref->u.ar.dimen != rref->u.ar.dimen) + { + if (lref->u.ar.type == AR_FULL) + fin_dep = gfc_full_array_ref_p (rref, NULL) ? GFC_DEP_EQUAL + : GFC_DEP_OVERLAP; + else if (rref->u.ar.type == AR_FULL) + fin_dep = gfc_full_array_ref_p (lref, NULL) ? GFC_DEP_EQUAL + : GFC_DEP_OVERLAP; + else + return 1; + break; + } + + for (n=0; n < lref->u.ar.dimen; n++) + { + /* Assume dependency when either of array reference is vector + subscript. */ + if (lref->u.ar.dimen_type[n] == DIMEN_VECTOR + || rref->u.ar.dimen_type[n] == DIMEN_VECTOR) + return 1; + + if (lref->u.ar.dimen_type[n] == DIMEN_RANGE + && rref->u.ar.dimen_type[n] == DIMEN_RANGE) + this_dep = check_section_vs_section (&lref->u.ar, &rref->u.ar, n); + else if (lref->u.ar.dimen_type[n] == DIMEN_ELEMENT + && rref->u.ar.dimen_type[n] == DIMEN_RANGE) + this_dep = gfc_check_element_vs_section (lref, rref, n); + else if (rref->u.ar.dimen_type[n] == DIMEN_ELEMENT + && lref->u.ar.dimen_type[n] == DIMEN_RANGE) + this_dep = gfc_check_element_vs_section (rref, lref, n); + else + { + gcc_assert (rref->u.ar.dimen_type[n] == DIMEN_ELEMENT + && lref->u.ar.dimen_type[n] == DIMEN_ELEMENT); + this_dep = gfc_check_element_vs_element (rref, lref, n); + } + + /* If any dimension doesn't overlap, we have no dependency. */ + if (this_dep == GFC_DEP_NODEP) + return 0; + + /* Now deal with the loop reversal logic: This only works on + ranges and is activated by setting + reverse[n] == GFC_ENABLE_REVERSE + The ability to reverse or not is set by previous conditions + in this dimension. If reversal is not activated, the + value GFC_DEP_BACKWARD is reset to GFC_DEP_OVERLAP. */ + if (rref->u.ar.dimen_type[n] == DIMEN_RANGE + && lref->u.ar.dimen_type[n] == DIMEN_RANGE) + { + /* Set reverse if backward dependence and not inhibited. */ + if (reverse && reverse[n] == GFC_ENABLE_REVERSE) + reverse[n] = (this_dep == GFC_DEP_BACKWARD) ? + GFC_REVERSE_SET : reverse[n]; + + /* Set forward if forward dependence and not inhibited. */ + if (reverse && reverse[n] == GFC_ENABLE_REVERSE) + reverse[n] = (this_dep == GFC_DEP_FORWARD) ? + GFC_FORWARD_SET : reverse[n]; + + /* Flag up overlap if dependence not compatible with + the overall state of the expression. */ + if (reverse && reverse[n] == GFC_REVERSE_SET + && this_dep == GFC_DEP_FORWARD) + { + reverse[n] = GFC_INHIBIT_REVERSE; + this_dep = GFC_DEP_OVERLAP; + } + else if (reverse && reverse[n] == GFC_FORWARD_SET + && this_dep == GFC_DEP_BACKWARD) + { + reverse[n] = GFC_INHIBIT_REVERSE; + this_dep = GFC_DEP_OVERLAP; + } + + /* If no intention of reversing or reversing is explicitly + inhibited, convert backward dependence to overlap. */ + if ((reverse == NULL && this_dep == GFC_DEP_BACKWARD) + || (reverse != NULL && reverse[n] == GFC_INHIBIT_REVERSE)) + this_dep = GFC_DEP_OVERLAP; + } + + /* Overlap codes are in order of priority. We only need to + know the worst one.*/ + if (this_dep > fin_dep) + fin_dep = this_dep; + } + + /* If this is an equal element, we have to keep going until we find + the "real" array reference. */ + if (lref->u.ar.type == AR_ELEMENT + && rref->u.ar.type == AR_ELEMENT + && fin_dep == GFC_DEP_EQUAL) + break; + + /* Exactly matching and forward overlapping ranges don't cause a + dependency. */ + if (fin_dep < GFC_DEP_BACKWARD) + return 0; + + /* Keep checking. We only have a dependency if + subsequent references also overlap. */ + break; + + default: + gcc_unreachable (); + } + lref = lref->next; + rref = rref->next; + } + + /* If we haven't seen any array refs then something went wrong. */ + gcc_assert (fin_dep != GFC_DEP_ERROR); + + /* Assume the worst if we nest to different depths. */ + if (lref || rref) + return 1; + + return fin_dep == GFC_DEP_OVERLAP; +} -- cgit v1.2.3