Re: debug flags (-feliminate-dwarf2-dups)

[Daniel Berlin <dberlin at redhat dot com>]

scott snyder <snyder@fnal.gov> writes:

> Benjamin Kosnik <bkoz@redhat.com> writes:
> > hey scott. I noticed that you put these flags in your last email:
> > 
> > -g -gdwarf-2 -feliminate-dwarf2-dups 
> > 
> > Seems interesting. I'm wondering if these should be just on by
> > default, by changing DEBUG_FLAGS in the Makefiles.
> 
<snip>
> 
> (Actually, it was amusing to see that -feliminate-dwarf2-dups significantly
> _increased_ the object file sizes --- there's more overhead since each
> object gets put in its own section. 
Why is it amusing? The point of -feliminate-dwarf2-dups was to reduce
the size of debugging executables, not debugging *objects*. 

Nothing will reduce that other than using .debug_str or
.debug_loc. Even doing the elimination in the linker obviously won't
reduce the object file size.
>  The sizes of the images after linking
> were somewhat smaller, but overall, i think it was pretty much a
> wash.
Then you don't have a lot of common debug info.
It's really helpful if you use a lot of common headers or the STL.
Try compiling 5 files that include, say, map, string, and vector with dwarf2. link
them. Note the executable size. Try it again with
-feliminate-dwarf2-dups.
)
)

> 
> sss

-- 
I used to be a narrator for bad mimes.