[Bug breakpoints/27889] jit.c:1178: internal-error: void jit_event_handler(gdbarch*, objfile*): Assertion `jiter->jiter_data != nullptr' failed.

["cvs-commit at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=27889

--- Comment #7 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Tom de Vries <vries@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=6d1a09b77a9ab52d9fc627b8f5eb952892c81f90

commit 6d1a09b77a9ab52d9fc627b8f5eb952892c81f90
Author: Tom de Vries <tdevries@suse.de>
Date:   Fri May 21 15:09:14 2021 +0200

    [gdb/breakpoint] Fix assert in jit_event_handler

    Consider a minimal test-case test.c:
    ...
    int main (void) { return 0; }
    ...
    which we can compile into llvm byte code using clang:
    ...
    $ clang -g -S -emit-llvm --target=x86_64-unknown-unknown-elf test.c
    ...
    and then run using lli, which uses the llvm jit:
    ...
    $ lli test.ll
    ...

    If we run this under gdb, we run into an assert:
    ...
    $ gdb -q -batch -ex run --args /usr/bin/lli test.ll
    Dwarf Error: Cannot not find DIE at 0x18a936e7 \
      [from module libLLVM.so.10-10.0.1-lp152.30.4.x86_64.debug]

    [Thread debugging using libthread_db enabled]
    Using host libthread_db library "/lib64/libthread_db.so.1".
    src/gdb/jit.c:1178: internal-error: \
      void jit_event_handler(gdbarch*, objfile*): \
      Assertion `jiter->jiter_data != nullptr' failed.
    ...

    This is caused by the following.

    When running jit_breakpoint_re_set_internal, we first handle
    libLLVM.so.10.debug, and set a jit breakpoint.

    Next we handle libLLVM.so.10:
    ...
    (gdb) p the_objfile.original_name
    $42 = 0x2494170 "libLLVM.so.10"
    ...
    but the minimal symbols we find are from libLLVM.so.10.debug:
    ...
    (gdb) p reg_symbol.objfile.original_name
    $43 = 0x38e7c50 "libLLVM.so.10-10.0.1-lp152.30.4.x86_64.debug"
    (gdb) p desc_symbol.objfile.original_name
    $44 = 0x38e7c50 "libLLVM.so.10-10.0.1-lp152.30.4.x86_64.debug"
    ...
    and consequently, the objf_data is the one from libLLVM.so.10.debug:
    ...
          jiter_objfile_data *objf_data
            = get_jiter_objfile_data (reg_symbol.objfile);
    ...
    and so we hit this:
    ...
          if (objf_data->cached_code_address == addr)
            continue;
    ...
    and no second jit breakpoint is inserted.

    Subsequently, the jit breakpoint is triggered and handled, but when finding
    the symbol for the breakpoint address we get:
    ...
    (gdb) p jit_bp_sym.objfile.original_name
    $52 = 0x2494170 "libLLVM.so.10"
    ...

    The assert 'jiter->jiter_data != nullptr' triggers because it checks
    libLLVM.so.10 while the one with jiter_data setup is libLLVM.so.10.debug.

    This fixes the assert:
    ...
           jiter_objfile_data *objf_data
    -        = get_jiter_objfile_data (reg_symbol.objfile);
    -        = get_jiter_objfile_data (the_objfile);
    ...
    but consequently we'll have two jit breakpoints, so we also make sure we
don't
    set a jit breakpoint on separate debug objects like libLLVM.so.10.debug.

    Tested on x86_64-linux.

    gdb/ChangeLog:

    2021-05-21  Tom de Vries  <tdevries@suse.de>

            PR breakpoint/27889
            * jit.c (jit_breakpoint_re_set_internal): Skip separate debug
            objects.  Call get_jiter_objfile_data with the_objfile.

-- 
You are receiving this mail because:
You are on the CC list for the bug.