gcc/ChangeLog:
* read-md.c (md_reader::read_char): Support filtering
the input to a subset of line numbers.
(md_reader::md_reader): Initialize fields
m_first_line and m_last_line.
(md_reader::read_file_fragment): New function.
* read-md.h (md_reader::read_file_fragment): New decl.
(md_reader::m_first_line): New field.
(md_reader::m_last_line): New field.
* read-rtl-function.c (function_reader::create_function): Only
create cfun if it doesn't already exist. Set PROP_rtl on cfun's
curr_properties. Set DECL_INITIAL to a dummy block.
(read_rtl_function_body_from_file_range): New function.
* read-rtl-function.h (read_rtl_function_body_from_file_range):
New decl.