===================================================================
@@ -1060,6 +1060,256 @@ convert_elseif (gfc_code **c, int *walk_subtrees A
return 0;
}
+struct do_stack
+{
+ struct do_stack *prev;
+ gfc_iterator *iter;
+ gfc_code *code;
+} *stack_top;
+
+/* Recursivly traverse the block of a WRITE or READ statement, and, can it be
+ optimized, do so. It optimizes it by replacing do loops with their analog
+ array slices. For example:
+
+ write (*,*) (a(i), i=1,4)
+
+ is replaced with
+
+ write (*,*) a(1:4:1) . */
+
+static bool
+traverse_io_block(gfc_code *code, bool *has_reached, gfc_code *prev)
+{
+ gfc_code *curr;
+ gfc_expr *new_e, *expr, *start;
+ gfc_ref *ref;
+ struct do_stack ds_push;
+ int i, future_rank = 0;
+ gfc_iterator *iters[GFC_MAX_DIMENSIONS];
+
+ /* Find the first transfer/do statement. */
+ for (curr = code; curr; curr = curr->next)
+ {
+ if (curr->op == EXEC_DO || curr->op == EXEC_TRANSFER)
+ break;
+ }
+
+ /* Ensure it is the only transfer/do statement because cases like
+
+ write (*,*) (a(i), b(i), i=1,4)
+
+ cannot be optimized. */
+
+ if (!curr || curr->next)
+ return false;
+
+ if (curr->op == EXEC_DO)
+ {
+ if (curr->ext.iterator->var->ref)
+ return false;
+ ds_push.prev = stack_top;
+ ds_push.iter = curr->ext.iterator;
+ ds_push.code = curr;
+ stack_top = &ds_push;
+ if (traverse_io_block(curr->block->next, has_reached, prev))
+ {
+ if (curr != stack_top->code && !*has_reached)
+ {
+ curr->block->next = NULL;
+ gfc_free_statements(curr);
+ }
+ else
+ *has_reached = true;
+ return true;
+ }
+ return false;
+ }
+
+ gcc_assert(curr->op == EXEC_TRANSFER);
+
+ if (curr->expr1->symtree->n.sym->attr.allocatable)
+ return false;
+
+ ref = curr->expr1->ref;
+ if (!ref || ref->type != REF_ARRAY || ref->u.ar.codimen != 0)
+ return false;
+
+ /* Find the iterators belonging to each variable and check conditions. */
+ for (i = 0; i < ref->u.ar.dimen; i++)
+ {
+ if (!ref->u.ar.start[i] || ref->u.ar.start[i]->ref
+ || ref->u.ar.dimen_type[i] != DIMEN_ELEMENT)
+ return false;
+
+ start = ref->u.ar.start[i];
+ gfc_simplify_expr(start, 0);
+ switch (start->expr_type)
+ {
+ case EXPR_VARIABLE:
+
+ /* write (*,*) (a(i), i=a%b,1) not handled yet. */
+ if (start->ref)
+ return false;
+
+ /* Check for (a(k), i=1,4) or ((a(j, i), i=1,4), j=1,4). */
+ if (!stack_top || !stack_top->iter
+ || stack_top->iter->var->symtree != start->symtree)
+ iters[i] = NULL;
+ else
+ {
+ iters[i] = stack_top->iter;
+ stack_top = stack_top->prev;
+ future_rank++;
+ }
+ break;
+ case EXPR_CONSTANT:
+ iters[i] = NULL;
+ break;
+ case EXPR_OP:
+ switch (start->value.op.op)
+ {
+ case INTRINSIC_PLUS:
+ case INTRINSIC_TIMES:
+ if (start->value.op.op1->expr_type != EXPR_VARIABLE)
+ std::swap(start->value.op.op1, start->value.op.op2);
+ __attribute__((fallthrough));
+ case INTRINSIC_MINUS:
+ if ((start->value.op.op1->expr_type!= EXPR_VARIABLE
+ && start->value.op.op2->expr_type != EXPR_CONSTANT)
+ || start->value.op.op1->ref)
+ return false;
+ if (!stack_top || !stack_top->iter
+ || stack_top->iter->var->symtree
+ != start->value.op.op1->symtree)
+ return false;
+ iters[i] = stack_top->iter;
+ stack_top = stack_top->prev;
+ break;
+ default:
+ return false;
+ }
+ future_rank++;
+ break;
+ default:
+ return false;
+ }
+ }
+
+ /* Create new expr. */
+ new_e = gfc_copy_expr(curr->expr1);
+ new_e->expr_type = EXPR_VARIABLE;
+ new_e->rank = future_rank;
+ if (curr->expr1->shape)
+ {
+ new_e->shape = gfc_get_shape(new_e->rank);
+ }
+
+ /* Assign new starts, ends and strides if necessary. */
+ for (i = 0; i < ref->u.ar.dimen; i++)
+ {
+ if (!iters[i])
+ continue;
+ start = ref->u.ar.start[i];
+ switch (start->expr_type)
+ {
+ case EXPR_CONSTANT:
+ gfc_internal_error("bad expression");
+ break;
+ case EXPR_VARIABLE:
+ new_e->ref->u.ar.dimen_type[i] = DIMEN_RANGE;
+ new_e->ref->u.ar.type = AR_SECTION;
+ gfc_free_expr(new_e->ref->u.ar.start[i]);
+ new_e->ref->u.ar.start[i] = gfc_copy_expr(iters[i]->start);
+ new_e->ref->u.ar.end[i] = gfc_copy_expr(iters[i]->end);
+ new_e->ref->u.ar.stride[i] = gfc_copy_expr(iters[i]->step);
+ break;
+ case EXPR_OP:
+ new_e->ref->u.ar.dimen_type[i] = DIMEN_RANGE;
+ new_e->ref->u.ar.type = AR_SECTION;
+ gfc_free_expr(new_e->ref->u.ar.start[i]);
+ expr = gfc_copy_expr(start);
+ expr->value.op.op1 = gfc_copy_expr(iters[i]->start);
+ new_e->ref->u.ar.start[i] = expr;
+ expr = gfc_copy_expr(start);
+ expr->value.op.op1 = gfc_copy_expr(iters[i]->end);
+ new_e->ref->u.ar.end[i] = expr;
+ switch(start->value.op.op)
+ {
+ case INTRINSIC_MINUS:
+ case INTRINSIC_PLUS:
+ new_e->ref->u.ar.stride[i] = gfc_copy_expr(iters[i]->step);
+ break;
+ case INTRINSIC_TIMES:
+ expr = gfc_copy_expr(start);
+ expr->value.op.op1 = gfc_copy_expr(iters[i]->step);
+ new_e->ref->u.ar.stride[i] = expr;
+ break;
+ default:
+ gfc_internal_error("bad op");
+ }
+ break;
+ default:
+ gfc_internal_error("bad expression");
+ }
+ }
+ curr->expr1 = new_e;
+
+ /* Insert modified statement. Check whether the statement needs to be
+ inserted at the lowest level. */
+ if (!stack_top->iter)
+ {
+ if (prev)
+ {
+ curr->next = prev->next->next;
+ prev->next = curr;
+ }
+ else
+ {
+ curr->next = stack_top->code->block->next->next->next;
+ stack_top->code->block->next = curr;
+ }
+ }
+ else
+ stack_top->code->block->next = curr;
+ return true;
+}
+
+/* Function for the gfc_code_walker. If code is a READ or WRITE statement, it
+ tries to optimize its block. */
+
+static int
+simplify_io_impl_do (gfc_code **code, int *walk_subtrees,
+ void *data ATTRIBUTE_UNUSED)
+{
+ gfc_code **curr, *prev = NULL;
+ struct do_stack write, first;
+ bool b = false;
+ *walk_subtrees = 1;
+ if (!(*code)->block || ((*code)->block->op != EXEC_WRITE
+ && (*code)->block->op != EXEC_READ))
+ return 0;
+
+ *walk_subtrees = 0;
+ write.prev = NULL;
+ write.iter = NULL;
+ write.code = *code;
+
+ for (curr = &(*code)->block; *curr; curr = &(*curr)->next)
+ {
+ if ((*curr)->op == EXEC_DO)
+ {
+ first.prev = &write;
+ first.iter = (*curr)->ext.iterator;
+ first.code = *curr;
+ stack_top = &first;
+ traverse_io_block((*curr)->block->next, &b, prev);
+ stack_top = NULL;
+ }
+ prev = *curr;
+ }
+ return 0;
+}
+
/* Optimize a namespace, including all contained namespaces. */
static void
@@ -1073,6 +1323,7 @@ optimize_namespace (gfc_namespace *ns)
in_assoc_list = false;
in_omp_workshare = false;
+ gfc_code_walker (&ns->code, simplify_io_impl_do, dummy_expr_callback, NULL);
gfc_code_walker (&ns->code, convert_do_while, dummy_expr_callback, NULL);
gfc_code_walker (&ns->code, convert_elseif, dummy_expr_callback, NULL);
gfc_code_walker (&ns->code, cfe_code, cfe_expr_0, NULL);