fortran: Factor data references for scalar class argument wrapping [PR92178]

In the case of a scalar actual arg passed to a polymorphic assumed-rank
dummy with INTENT(OUT) attribute, avoid repeatedly evaluating the actual
argument reference by saving a pointer to it.  This is non-optimal, but
may also be invalid, because the data reference may depend on its own
content.  In that case the expression can't be evaluated after the data
has been deallocated.

There are two ways redundant expressions are generated:
 - parmse.expr, which contains the actual argument expression, is
   reused to get or set subfields in gfc_conv_class_to_class.
 - gfc_conv_class_to_class, to get the virtual table pointer associated
   with the argument, generates a new expression from scratch starting
   with the frontend expression.

The first part is fixed by saving parmse.expr to a pointer and using
the pointer instead of the original expression.

The second part is fixed by adding a separate field to gfc_se that
is set to the class container expression  when the expression to
evaluate is polymorphic.  This needs the same field in gfc_ss_info
so that its value can be propagated to gfc_conv_class_to_class which
is modified to use that value.  Finally gfc_conv_procedure saves the
expression in that field to a pointer in between to avoid the same
problem as for the first part.

	PR fortran/92178

gcc/fortran/ChangeLog:

	* trans.h (struct gfc_se): New field class_container.
	(struct gfc_ss_info): Ditto.
	(gfc_evaluate_data_ref_now): New prototype.
	* trans.cc (gfc_evaluate_data_ref_now):  Implement it.
	* trans-array.cc (gfc_conv_ss_descriptor): Copy class_container
	field from gfc_se struct to gfc_ss_info struct.
	(gfc_conv_expr_descriptor): Copy class_container field from
	gfc_ss_info struct to gfc_se struct.
	* trans-expr.cc (gfc_conv_class_to_class): Use class container
	set in class_container field if available.
	(gfc_conv_variable): Set class_container field on encountering
	class variables or components, clear it on encountering
	non-class components.
	(gfc_conv_procedure_call): Evaluate data ref to a pointer now,
	and replace later references by usage of the pointer.

gcc/testsuite/ChangeLog:

	* gfortran.dg/intent_out_20.f90: New test.

0 files changed, 0 insertions, 0 deletions