Re: [musl] [PATCH] crt: Add .file directive

[Fangrui Song <i@maskray.me>]

On Fri, Oct 30, 2020 at 1:54 PM Fangrui Song <i@maskray.me> wrote:
>
> On 2020-10-30, Rich Felker wrote:
> >On Fri, Oct 30, 2020 at 11:44:02AM -0700, Khem Raj wrote:
> >> Musl linked binaries come out to be not reproducible because
> >> absolute build path is seen in debug info of crti.o and crtn.o
> >> This is due to the fact that these objects are built from assembly
> >> source files and they are missing .file directive
> >> if we add .file <filename>.s in them then debug info encodes this
> >> value instead of absolute path in debug_line section
>
> .debug_line is unrelated because there is no .loc directive in these
> crti.s and crtn.s files.
>
> Many architectures do not leave non-STT_SECTION STB_LOCAL symbols in
> crti.o and crtn.o, so they don't need to be patched (even if the
> maintainer agrees to add the workaround in musl, instead of fixing the
> toolchain).
>
> >Surely there should be some better way to achieve this with CFLAGS
> >instead of duplication across every source file..?
> >
> >Rich
>
> https://bugs.llvm.org/show_bug.cgi?id=48023 captures the nature of the
> problem. You may send a message to binutils@sourceware.org how GCC/gas
> should handle this situation.
>
> LLD and gold do not synthesize STT_FILE, hence no such problem.

The binutils action is: GNU ld 2.36 will use the base name
(https://sourceware.org/bugzilla/show_bug.cgi?id=26822)