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/* Dependency analysis Copyright (C) 2000, 2001, 2002, 2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc. Contributed by Paul Brook <paul@nowt.org> 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 <http://www.gnu.org/licenses/>. */ /* 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. */ static bool are_identical_variables (gfc_expr *e1, gfc_expr *e2) { gfc_ref *r1, *r2; if (e1->symtree->n.sym->attr.dummy && e2->symtree->n.sym->attr.dummy) { /* Dummy arguments: Only check for equal names. */ if (e1->symtree->n.sym->name != e2->symtree->n.sym->name) return false; } else { /* Check for equal symbols. */ 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 ("are_identical_variables: Bad type"); } r1 = r1->next; r2 = r2->next; } return true; } /* Compare two functions for equality. Returns 0 if e1==e2, -2 otherwise. If impure_ok is false, only return 0 for pure functions. */ int gfc_dep_compare_functions (gfc_expr *e1, gfc_expr *e2, bool impure_ok) { gfc_actual_arglist *args1; gfc_actual_arglist *args2; if (e1->expr_type != EXPR_FUNCTION || e2->expr_type != EXPR_FUNCTION) return -2; if ((e1->value.function.esym && e2->value.function.esym && e1->value.function.esym == e2->value.function.esym && (e1->value.function.esym->result->attr.pure || impure_ok)) || (e1->value.function.isym && e2->value.function.isym && e1->value.function.isym == e2->value.function.isym && (e1->value.function.isym->pure || impure_ok))) { 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; } /* Compare two expressions. Return values: * +1 if e1 > e2 * 0 if e1 == e2 * -1 if e1 < e2 * -2 if the relationship could not be determined * -3 if e1 /= e2, but we cannot tell which one is larger. REAL and COMPLEX constants are only compared for equality or inequality; if they are unequal, -2 is returned in all cases. */ 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, for INTEGER only. */ 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, for INTEGER only. */ 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, for INTEGER only. */ 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 l; 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, for INTEGER only. */ 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 -3; 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); /* Compare REAL and COMPLEX constants. Because of the traps and pitfalls associated with comparing a + 1.0 with a + 0.5, check for equality only. */ if (e2->expr_type == EXPR_CONSTANT) { if (e1->ts.type == BT_REAL && e2->ts.type == BT_REAL) { if (mpfr_cmp (e1->value.real, e2->value.real) == 0) return 0; else return -2; } else if (e1->ts.type == BT_COMPLEX && e2->ts.type == BT_COMPLEX) { if (mpc_cmp (e1->value.complex, e2->value.complex) == 0) return 0; else return -2; } } if (e1->ts.type != BT_INTEGER || e2->ts.type != BT_INTEGER) return -2; /* For INTEGER, all cases where e2 is not constant should have been filtered out above. */ gcc_assert (e2->expr_type == EXPR_CONSTANT); 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 (are_identical_variables (e1, e2)) return 0; else return -3; 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; else if (e1->value.op.op == INTRINSIC_TIMES && gfc_dep_compare_expr (e1->value.op.op1, e2->value.op.op2) == 0 && gfc_dep_compare_expr (e1->value.op.op2, e2->value.op.op1) == 0) /* Commutativity of multiplication; addition is handled above. */ return 0; return -2; case EXPR_FUNCTION: return gfc_dep_compare_functions (e1, e2, false); break; default: return -2; } } /* Returns 1 if the two ranges are the same and 0 if they are not (or if the results are indeterminate). 'n' is the dimension to compare. */ static int is_same_range (gfc_array_ref *ar1, gfc_array_ref *ar2, int n) { 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 || i == 0) return 0; } else if (e2 && !e1) { i = gfc_expr_is_one (e2, -1); if (i == -1 || i == 0) return 0; } else if (e1 && e2) { i = gfc_dep_compare_expr (e1, e2); 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 0; i = gfc_dep_compare_expr (e1, e2); 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 0; i = gfc_dep_compare_expr (e1, e2); 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); if (gfc_inline_intrinsic_function_p (expr)) { /* The TRANSPOSE case should have been caught in the noncopying intrinsic case above. */ gcc_assert (expr->value.function.isym->id != GFC_ISYM_TRANSPOSE); 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 (is_same_range (l_ar, r_ar, n)) 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; 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; }
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