[Bug python/31437] [gdb/python] Unavailable register breaks python unwinding

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

https://sourceware.org/bugzilla/show_bug.cgi?id=31437

--- Comment #6 from Sourceware Commits <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=2236c5e384de20b0dd6b2fbc964a7269027cb2d9

commit 2236c5e384de20b0dd6b2fbc964a7269027cb2d9
Author: Tom de Vries <tdevries@suse.de>
Date:   Wed May 8 14:13:11 2024 +0200

    [gdb/python] Make gdb.UnwindInfo.add_saved_register more robust

    On arm-linux, until commit bbb12eb9c84 ("gdb/arm: Remove tpidruro register
    from non-FreeBSD target descriptions") I ran into:
    ...
    FAIL: gdb.base/inline-frame-cycle-unwind.exp: cycle at level 5: \
      backtrace when the unwind is broken at frame 5
    ...

    What happens is the following:
    - the TestUnwinder from inline-frame-cycle-unwind.py calls
      gdb.UnwindInfo.add_saved_register with reg == tpidruro and value
      "<unavailable>",
    - pyuw_sniffer calls value->contents ().data () to access the value of the
      register, which throws an UNAVAILABLE_ERROR,
    - this causes the TestUnwinder unwinder to fail, after which another
unwinder
      succeeds and returns the correct frame, and
    - the test-case fails because it's counting on the TestUnwinder to succeed
and
      return an incorrect frame.

    Fix this by checking for !value::entirely_available as well as
    valued::optimized_out in unwind_infopy_add_saved_register.

    Tested on x86_64-linux and arm-linux.

    Approved-By: Andrew Burgess <aburgess@redhat.com>

    PR python/31437
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31437

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