[RFC] Modify -g1 to produce line tables

[Cary Coutant <ccoutant at google dot com>]

A long time ago, I proposed a -gmlt option to generate "minimal line
tables" (basically -g1 + line tables):

http://gcc.gnu.org/ml/gcc-patches/2011-04/msg02075.html

The consensus from that thread was that instead of a new option, we
should just modify -g1 to produce line tables (the documented purpose
of -g1 is to enable stack traces, and stack traces are much more
useful with line numbers). I also proposed, and got no objection, that
-g by itself should set the debugging level to 2 (i.e., -g1 -g should
behave the same as -g1 -g2).

Here, finally, is that patch again, reworked to generate line tables
at -g1. I plan to commit this when Stage 1 reopens, but I'd like to
verify that earlier consensus. I also plan to commit this to the
google/main branch, and future merges will go more smoothly if what I
put in google/main matches what eventually goes into trunk.

-cary

2013-02-06   Cary Coutant  <ccoutant@google.com>

gcc/
        * dwarf2out.c (want_pubnames): Don't do pubnames for -g1.
        (add_linkage_name): Don't add linkage name for -g1.
        (decls_for_scope): Process subblocks for -g1.
        (dwarf2out_source_line): Output line tables for -g1.
        (dwarf2out_finish): Likewise.
        * tree-ssa-live.c (remove_unused_scope_block_p): Don't prune
        unused scopes for -g1.
        * opts.c (common_handle_option): Handle -g same as -g2.
        * doc/invoke.texi: Update description for -g1.

gcc/testsuite/
        * gcc.dg/debug/dwarf2/mlt1.c: New test.
        * gcc.dg/debug/dwarf2/mlt2.c: New test.

Attachment: gcc-mlt-patch-3.txt
Description: Text document