[Bug gdb/27891] maintenance selftest fail when an executable is loaded

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

https://sourceware.org/bugzilla/show_bug.cgi?id=27891

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |alahay01 at gcc dot gnu.org,
                   |                            |luis.machado at linaro dot org,
                   |                            |vries at gcc dot gnu.org

--- Comment #1 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Andrew Burgess from comment #0)
>  Self test failed: arch armv8.1-m.main: self-test failed at
> ../../src/gdb/disasm-selftests.c:165

The first error I run into is this one, and I've debugged it.

1. With exec.

In gdb_print_insn_arm, we run into this and set info->flags |=
USER_SPECIFIED_MACHINE_TYPE:
...
  /* GDB is able to get bfd_mach from the exe_bfd, info->mach is                
     accurate, so mark USER_SPECIFIED_MACHINE_TYPE bit.  Otherwise,             
     opcodes/arm-dis.c:print_insn reset info->mach, and it will trigger         
     the assert on the mismatch of info->mach and                               
     bfd_get_mach (current_program_space->exec_bfd ()) in                       
     default_print_insn.  */
  if (current_program_space->exec_bfd () != NULL)
    info->flags |= USER_SPECIFIED_MACHINE_TYPE;
...
and consequently we don't do this in print_insn:
...
      if ((info->flags & USER_SPECIFIED_MACHINE_TYPE) == 0)
          info->mach = bfd_mach_arm_unknown;
...
so we end up doing this in select_arm_features:
...
    case bfd_mach_arm_8_1M_MAIN:
      ARM_SET_FEATURES (ARM_ARCH_V8_1M_MAIN);
      arm_feature_set mve_all
        = ARM_FEATURE_CORE_HIGH (ARM_EXT2_MVE | ARM_EXT2_MVE_FP);
      ARM_MERGE_FEATURE_SETS (arch_fset, arch_fset, mve_all);
      force_thumb = 1;
      break;
...

With force_thumb set, we disassemble only two bytes, and the selftest fails.

2. Without exec.

- in gdb_print_insn_arm, we don't set
  info->flags |= USER_SPECIFIED_MACHINE_TYPE.
- in print_insn, we do bfd_mach_arm_unknown
- in select_arm_features, we don't set force_thumb

Without force_thumb set, we disassemble four bytes, and the selftest passes.

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