Compressed debug information

[Tom Kacvinsky]

Hi again,

On Sun, Mar 26, 2023 at 10:21 AM Tom Kacvinsky <tkacvins@gmail.com> wrote:

> HI,
>
> I have a question about compressed debug sections.  I think I am
> getting compressed debug sections because a build of our product
> with -gz=none (using GCC 12.1) results in larger artifacts than a
> build without -gz=none.  Moreover, if I use ld.lld for the linker, where
> I built LLVM without zlib support, it complains that the object files were
> ELF_COMPRESSED and ld.lld could not handle them because LLVM
> was built with zlib support.
>
> Because of that I am under  the impression that the compressed debug
> section object files fed into the linker result in compressed debug
> sections
> in the final shared library or executable, provided the linker can handle
> compressed debug sections.
>
> But I don't know how to verify that the final debug section(s) in the
> executables/shared libraries have debug information.  Google was not my
> friend with respect to determining that.  I looked at readelf and
> objdump options (from binutils 2.39) and didn't see an option for that. I
> also looked at dwarfdump output but didn't see anything.
>
> Any hints?
>
>
I'd like to retract this idiotic question of mine.  Turns out that no,
there was
no compressed debug data.  I compared -gz=none and against a build w/o
-gz=none and the sizes were the same.  Then I built with -gz=zlib and the
file sizes then changed.

So I found my answer by experimentation.  Now I am going to see what I
can do to get this information using tools like readelf or dwarfdump.

Tom