[Bug libdw/30948] New: src/stack doesn't show source inforamtion if the target is compiled with clang

[yamato at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=30948

            Bug ID: 30948
           Summary: src/stack doesn't show source inforamtion if the
                    target is compiled with clang
           Product: elfutils
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libdw
          Assignee: unassigned at sourceware dot org
          Reporter: yamato at redhat dot com
                CC: elfutils-devel at sourceware dot org
  Target Milestone: ---

dwfl_module_getsrc() doesn't work unexpectedly if the target
executable is compiled with clang though it works well with an
executable compiled with gcc.

For testing I used executables built from the following source code (target.c):

    static int
    f1(void)
    {
      while (1);
      return 0;
    }

    static int
    f0(void)
    {
      return f1();
    }

    int main(void)
    {
      return f0();
    }

I made two executables with two compilers.
  $ gcc -O0 -g target.c -o target-gcc
  $ clang -O0 -g target.c -o target-clang

I run the two executables in background:

    $ ./target-gcc &  
    [2] 2118229

    $ ./target-clang &         
    [3] 2118253

I run src/stack with -s -p options:


For the executable built with gcc, backtrace reported source lines.

    $ ./src/stack -s -p 2118229
    PID 2118229 - process
    TID 2118229:
    #0  0x000000000040110a f1
        /home/yamato/var/elfutils/tests/target.c:4:9
    #1  0x0000000000401115 f0
        /home/yamato/var/elfutils/tests/target.c:11:10
    #2  0x0000000000401120 main
        /home/yamato/var/elfutils/tests/target.c:16:10
    #3  0x00007f7d6c823b8a __libc_start_call_main
        ../sysdeps/nptl/libc_start_call_main.h:58:16
    #4  0x00007f7d6c823c4b __libc_start_main@@GLIBC_2.34
        ../csu/libc-start.c:360:3
    #5  0x0000000000401045 _start


For the executable built with clang, backtrace didn't report source lines.

    $ ./src/stack -s -p 2118253
    PID 2118253 - process
    TID 2118253:
    #0  0x0000000000401149 f1
    #1  0x0000000000401139 f0
    #2  0x0000000000401124 main
    #3  0x00007f4a84ab5b8a __libc_start_call_main
        ../sysdeps/nptl/libc_start_call_main.h:58:16
    #4  0x00007f4a84ab5c4b __libc_start_main@@GLIBC_2.34
        ../csu/libc-start.c:360:3
    #5  0x0000000000401045 _start

The bt command of Gdb can report them:

    $ ./target-clang &
    [1] 2116805
    [yamato@dev64]~/var/elfutils/tests% pstack 2116805
    #0  0x0000000000401149 in f1 () at target.c:4
    #1  0x0000000000401139 in f0 () at target.c:11
    #2  0x0000000000401124 in main () at target.c:16

Gdb can report the source lines. So I guess clang injected enough information
to the executable.

The versions of the compilers:
    $ gcc -v
    Using built-in specs.
    COLLECT_GCC=gcc
    COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/13/lto-wrapper
    OFFLOAD_TARGET_NAMES=nvptx-none
    OFFLOAD_TARGET_DEFAULT=1
    Target: x86_64-redhat-linux
    Configured with: ../configure --enable-bootstrap
--enable-languages=c,c++,fortran,objc,obj-c++,ada,go,d,m2,lto --prefix=/usr
--mandir=/usr/share/man --infodir=/usr/share/info
--with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared
--enable-threads=posix --enable-checking=release --enable-multilib
--with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions
--enable-gnu-unique-object --enable-linker-build-id
--with-gcc-major-version-only --enable-libstdcxx-backtrace
--with-libstdcxx-zoneinfo=/usr/share/zoneinfo --with-linker-hash-style=gnu
--enable-plugin --enable-initfini-array
--with-isl=/builddir/build/BUILD/gcc-13.2.1-20230728/obj-x86_64-redhat-linux/isl-install
--enable-offload-targets=nvptx-none --without-cuda-driver
--enable-offload-defaulted --enable-gnu-indirect-function --enable-cet
--with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux
--with-build-config=bootstrap-lto --enable-link-serialization=1
    Thread model: posix
    Supported LTO compression algorithms: zlib zstd
    gcc version 13.2.1 20230728 (Red Hat 13.2.1-1) (GCC)

    $ clang -v
    clang version 16.0.6 (Fedora 16.0.6-3.fc38)
    Target: x86_64-redhat-linux-gnu
    Thread model: posix
    InstalledDir: /usr/bin
    Found candidate GCC installation:
/usr/bin/../lib/gcc/x86_64-redhat-linux/13
    Selected GCC installation: /usr/bin/../lib/gcc/x86_64-redhat-linux/13
    Candidate multilib: .;@m64
    Candidate multilib: 32;@m32
    Selected multilib: .;@m64

The revision of elfutils: 557aa6a4b7b1d678b7c2c3b9aae1dafcc2160c64 (git
commit).

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