On Mon, Oct 17, 2016 at 11:44 PM, Mike Stump <mikest...@comcast.net> wrote: > On Oct 17, 2016, at 2:38 PM, Ximin Luo <infini...@pwned.gg> wrote: >> >> Mike Stump: >>> On Oct 17, 2016, at 11:00 AM, Ximin Luo <infini...@pwned.gg> wrote: >>>> Therefore, it is better to emit it in all circumstances, in case the >>>> reader needs to know what the working >>>> directory was at compile-time. >>> >>> I can't help but wonder if this would break ccache some? >>> >> >> Could you explain this in some more detail? At the moment, GCC will already >> emit DW_AT_name with an absolute path (in the scenario that this patch is >> relevant to). How does ccache work around this at the moment? (Does it use >> debug-prefix-map? In which case, this also affects DW_AT_comp_dir, so my >> patch should be fine.) > > If you compile the same file, but in a different directory, I wonder if cwd > will cause the cache entry to not be reused. > > I expect one of the ccache people that are around would just know if it will > care at all.
I believe ccache compares preprocessed source, definitely _not_ DWARF output, so this shouldn't break anything there. It might result in different object file output but as the reporter figured due to a bug in dwarf2out.c we end up generating DW_AT_comp_dir in almost all cases already. I think the patch is ok but it misses a ChangeLog entry. How did you test the patch? (bootstrapped and tested on ...?) Thanks, Richard.
