This moves read_rtx and friends into rtx_reader, and splits
rtx_reader into two classes:

class md_reader: has responsibility for reading chars, managing
include files, top-level directives etc.  It is the read-md.o part.

class rtx_reader, a subclass, has the code for reading hierarchical
rtx expressions using the format codes.   It is the read-rtl.o part.

This split is needed by a followup patch, which converts
read_rtx_operand to a virtual function of rtx_reader.  To do this,
instances of rtx_reader (or its subclasses) need a vtable, which
needs to include a ptr to the code in read-rtl.o.  Splitting it up
allows the gen* tools that currently purely use read-md.o to continue
to do so.

gcc/ChangeLog:
	* genpreds.c (write_tm_constrs_h): Update for renaming of
	rtx_reader_ptr to md_reader_ptr.
	(write_tm_preds_h): Likewise.
	(write_insn_preds_c): Likewise.
	* read-md.c (rtx_reader_ptr): Rename to...
	(md_reader_ptr): ...this, and convert from an
	rtx_reader * to a md_reader *.
	(rtx_reader::set_md_ptr_loc): Rename to...
	(md_reader::set_md_ptr_loc): ...this.
	(rtx_reader::get_md_ptr_loc): Rename to...
	(md_reader::get_md_ptr_loc): ...this.
	(rtx_reader::copy_md_ptr_loc): Rename to...
	(md_reader::copy_md_ptr_loc): ...this.
	(rtx_reader::fprint_md_ptr_loc): Rename to...
	(md_reader::fprint_md_ptr_loc): ...this.
	(rtx_reader::print_md_ptr_loc): Rename to...
	(md_reader::print_md_ptr_loc): ...this.
	(rtx_reader::join_c_conditions): Rename to...
	(md_reader::join_c_conditions): ...this.
	(rtx_reader::fprint_c_condition): ...this.
	(rtx_reader::print_c_condition): Rename to...
	(md_reader::print_c_condition): ...this.
	(fatal_with_file_and_line):  Update for renaming of
	rtx_reader_ptr to md_reader_ptr.
	(rtx_reader::require_char): Rename to...
	(md_reader::require_char): ...this.
	(rtx_reader::require_char_ws): Rename to...
	(md_reader::require_char_ws): ...this.
	(rtx_reader::require_word_ws): Rename to...
	(md_reader::require_word_ws): ...this.
	(rtx_reader::read_char): Rename to...
	(md_reader::read_char): ...this.
	(rtx_reader::unread_char): Rename to...
	(md_reader::unread_char): ...this.
	(rtx_reader::peek_char): Rename to...
	(md_reader::peek_char): ...this.
	(rtx_reader::read_name): Rename to...
	(md_reader::read_name): ...this.
	(rtx_reader::read_escape): Rename to...
	(md_reader::read_escape): ...this.
	(rtx_reader::read_quoted_string): Rename to...
	(md_reader::read_quoted_string): ...this.
	(rtx_reader::read_braced_string): Rename to...
	(md_reader::read_braced_string): ...this.
	(rtx_reader::read_string): Rename to...
	(md_reader::read_string): ...this.
	(rtx_reader::read_skip_construct): Rename to...
	(md_reader::read_skip_construct): ...this.
	(rtx_reader::handle_constants): Rename to...
	(md_reader::handle_constants): ...this.
	(rtx_reader::traverse_md_constants): Rename to...
	(md_reader::traverse_md_constants): ...this.
	(rtx_reader::handle_enum): Rename to...
	(md_reader::handle_enum): ...this.
	(rtx_reader::lookup_enum_type): Rename to...
	(md_reader::lookup_enum_type): ...this.
	(rtx_reader::traverse_enum_types): Rename to...
	(md_reader::traverse_enum_types): ...this.
	(rtx_reader::rtx_reader): Rename to...
	(md_reader::md_reader): ...this, and update for renaming of
	rtx_reader_ptr to md_reader_ptr.
	(rtx_reader::~rtx_reader): Rename to...
	(md_reader::~md_reader): ...this, and update for renaming of
	rtx_reader_ptr to md_reader_ptr.
	(rtx_reader::handle_include): Rename to...
	(md_reader::handle_include): ...this.
	(rtx_reader::handle_file): Rename to...
	(md_reader::handle_file): ...this.
	(rtx_reader::handle_toplevel_file): Rename to...
	(md_reader::handle_toplevel_file): ...this.
	(rtx_reader::get_current_location): Rename to...
	(md_reader::get_current_location): ...this.
	(rtx_reader::add_include_path): Rename to...
	(md_reader::add_include_path): ...this.
	(rtx_reader::read_md_files): Rename to...
	(md_reader::read_md_files): ...this.
	* read-md.h (class rtx_reader): Split into...
	(class md_reader): ...new class.
	(rtx_reader_ptr): Rename to...
	(md_reader_ptr): ...this, and convert to a md_reader *.
	(class noop_reader): Update base class to be md_reader.
	(class rtx_reader): Reintroduce as a subclass of md_reader.
	(rtx_reader_ptr): Reintroduce as a rtx_reader *.
	(read_char): Update for renaming of rtx_reader_ptr to
	md_reader_ptr.
	(unread_char): Likewise.
	* read-rtl.c (rtx_reader_ptr): New global.
	(rtx_reader::apply_iterator_to_string): Rename to...
	(md_reader::apply_iterator_to_string): ...this.
	(rtx_reader::copy_rtx_for_iterators): Rename to...
	(md_reader::copy_rtx_for_iterators): ...this.
	(rtx_reader::read_conditions): Rename to...
	(md_reader::read_conditions): ...this.
	(rtx_reader::record_potential_iterator_use): Rename to...
	(md_reader::record_potential_iterator_use): ...this.
	(rtx_reader::read_mapping): Rename to...
	(md_reader::read_mapping): ...this.
	(rtx_reader::read_rtx): Use rtx_reader_ptr when calling
	read_rtx_code.
	(rtx_reader::read_rtx_operand): Use get_string_obstack rather
	than directly accessing m_string_obstack.
	(rtx_reader::rtx_reader): New ctor.
	(rtx_reader::~rtx_reader): New dtor.

From-SVN: r243426