[PATCH] PR77895: DWARF: Emit DW_AT_comp_dir in all cases, even if source is an absolute path

[Mike Stump]

On Oct 17, 2016, at 2:38 PM, Ximin Luo <infinity0@pwned.gg> wrote:
> 
> Mike Stump:
>> On Oct 17, 2016, at 11:00 AM, Ximin Luo <infinity0@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.