[Bug lto/88147] [9 Regression] ICE in linemap_line_start, at libcpp/line-map.c:781 starting from r265875

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88147

--- Comment #13 from Martin Liška <marxin at gcc dot gnu.org> ---
I hope I understand the failure. So what happens:

- first a new map is created with to_line: 2578 (with m_column_and_range_bits
== 13)
- then a new request comes with to_line: 404198, m_column_and_range_bits is
extended to 15 and we decide to reuse the existing map.
- as seen the line difference is huge, ORDINARY_MAP_STARTING_LINE_NUMBER (map)
- to_line == 401620
- that would require 18 bits to represent

I'm going to append a patch candidate.