Re: [PATCH v4 2/2] gdb/reverse: Fix stepping over recursive functions

[Simon Marchi <simark@simark.ca>]

On 10/5/22 06:38, Bruno Larsen via Gdb-patches wrote:
> Currently, when using GDB to do reverse debugging, if we try to use the
> command "reverse next" to skip a recursive function, instead of skipping
> all of the recursive calls and stopping in the previous line, we stop at
> the second to last recursive call, and need to manually step backwards
> until we leave the first call.  This is well documented in PR gdb/16678.
> 
> This bug happens because when GDB notices that a reverse step has
> entered into a function, GDB will add a step_resume_breakpoint at the
> start of the function, then single step out of the prologue once that
> breakpoint is hit.  The problem was happening because GDB wouldn't give
> that step_resume_breakpoint a frame-id, so the first time the breakpoint
> was hit, the inferior would be stopped.  This is fixed by giving the
> current frame-id to the breakpoint.
> 
> This commit also changes gdb.reverse/step-reverse.c to contain a
> recursive function and attempt to both, skip it altogether, and to skip
> the second call from inside the first call, as this setup broke a
> previous version of the patch.
> ---
>  gdb/infrun.c                                |  2 +-
>  gdb/testsuite/gdb.reverse/step-precsave.exp |  6 ++-
>  gdb/testsuite/gdb.reverse/step-reverse.c    | 19 ++++++-
>  gdb/testsuite/gdb.reverse/step-reverse.exp  | 55 +++++++++++++++++++--
>  4 files changed, 74 insertions(+), 8 deletions(-)

Hi Bruno,

I see these failures since this commit:

    $ make check TESTS="gdb.reverse/step-reverse.exp" RUNTESTFLAGS="--target_board=native-gdbserver"
    FAIL: gdb.reverse/step-reverse.exp: reverse next over recursion again
    FAIL: gdb.reverse/step-reverse.exp: enter recursive function
    FAIL: gdb.reverse/step-reverse.exp: step over recursion inside the recursion

Simon