On Fri, Oct 16, 2020 at 10:58:34AM -0700, H.J. Lu wrote:
> Don't set HAVE_AS_GDWARF_5_DEBUG_FLAG nor HAVE_AS_WORKING_DWARF_4_FLAG
> if there is an extra assembly input file in debug info generated by
> --gdwarf-5/--gdwarf-4:
>
> https://sourceware.org/bugzilla/show_bug.cgi?id=25878
> https://sourceware.org/bugzilla/show_bug.cgi?id=26740
>
> Also replace success with dwarf4_success in the 32-bit --gdwarf-4 check.
>
> OK for master?
>
> PR bootstrap/97451
> * configure.ac (HAVE_AS_GDWARF_5_DEBUG_FLAG): Don't define if
> there is an extra assembly input file in debug info.
> (HAVE_AS_WORKING_DWARF_4_FLAG): Likewise. Replace success with
> dwarf4_success in the 32-bit --gdwarf-4 check.
> * configure: Regenerated.
The HAVE_AS_GDWARF_5_DEBUG_FLAG macro should be solely about whether
-gdwarf-5 can be passed to as, nothing else. That is because it is not only
used to decide if we can pass -gdwarf-5 to as for assembly of e.g. *.c
compilation, but also if we can pass it to as when gcc driver is invoked on
*.s and *.S. And in that case the problems with -gdwarf-N having unwanted
effects on assembly with compiler generated .debug_info etc. sections.
don't really matter.
The HAVE_AS_WORKING_DWARF_4_FLAG perhaps could be renamed to
...DWARF_N_FLAG, it is meant to check for whether we can safely pass the
option also for *.c etc. compilation when we emit debug info sections by the
compiler.
For that, the question is, are all the issues already fixed on the binutils
trunk? As in, do I get identical object files e.g. for -gdwarf-2
compilation no matter whether the compiler passes -gdwarf-2 to gas or not
(assuming dwarf 2 is the default in gas) when compiling various *.c/*.C
files? Ditto for modified gas that would default to other .debug_line
versions and corresponding gcc -gdwarf-N flag and passing vs. not passing
that -gdwarf-N to gas?
The hope is that -gdwarf-N to gas would have two functions:
1) if the assembly doesn't contain .debug* sections/.file/.loc directives,
emit debug info (mainly .debug_line) for the assembler file in order to
be able to debug those
2) if the assembly does contain .debug* sections/.file/.loc directives,
only change the version of the .debug_line generated for the .file/.loc
directives, but nothing else; keep all .debug* sections but .debug_line
as is
Jakub
