[PR49366] emit loc exprs for C++ non-virtual pmf template value parms

[PR49366] emit loc exprs for C++ non-virtual pmf template value parms

We used to emit, in debug information, the values bound to pointer to
member function template parameters only when they were NULL or
virtual member functions, because those can be represented with
DW_AT_const_value.

In order to represent the symbolic pointer to member function
constants for non-virtual member functions, we'd need to be able to
emit relocations for part of DW_AT_const_value, which we don't.  The
more viable alternative is to use DW_AT_location to represent such
values, as slated for inclusion in DWARFv5, according to
<URL:http://www.dwarfstd.org/ShowIssue.php?issue=130412.1>.

With this patch, when we can't emit a DW_AT_const_value, we emit each
"member" of the pointer to member function "record" as a
DW_OP_stack_value DW_OP_piece, as long as the referenced member
function is output in the same translation unit, otherwise we'd get
relocations to external symbols, something to avoid in debug sections.

for  gcc/ChangeLog

	PR debug/49366
	* dwarf2out.c (loc_list_from_tree_1): Expand some CONSTRUCTORs
	in DW_OP_pieces, just enough to handle pointers to member
	functions.
	(gen_remaining_tmpl_value_param_die_attribute): Use a location
	expression on DWARFv5 if a constant value doesn't work.

for  gcc/testsuite/ChangeLog

	PR debug/49366
	* g++.dg/debug/dwarf2/template-params-12.H: New.
	* g++.dg/debug/dwarf2/template-params-12f.C: New.
	* g++.dg/debug/dwarf2/template-params-12g.C: New.
	* g++.dg/debug/dwarf2/template-params-12n.C: New.
	* g++.dg/debug/dwarf2/template-params-12s.C: New.
	* g++.dg/debug/dwarf2/template-params-12u.C: New.
	* g++.dg/debug/dwarf2/template-params-12v.C: New.
	* g++.dg/debug/dwarf2/template-params-12w.C: New.

From-SVN: r239401