From: Doug Evans <dje@google.com>
To: Martin Galvan <martin.galvan@tallertechnologies.com>
Cc: gdb-patches@sourceware.org
Subject: Re: [PATCH] Python API: Add gdb.is_in_prologue and gdb.is_in_epilogue.
Date: Wed, 22 Oct 2014 19:23:00 -0000 [thread overview]
Message-ID: <21576.1088.684481.249056@ruffy.mtv.corp.google.com> (raw)
In-Reply-To: <1413986485-4673-1-git-send-email-martin.galvan@tallertechnologies.com>
Martin Galvan writes:
> Added two new functions to the Python API: gdb.is_in_prologue and gdb.is_in_epilogue.
> These expose the in_prologue and gdbarch_in_function_epilogue_p functions
> respectively, which are useful for checking if the values of local variables are
> valid when single-stepping through machine instructions.
>
> Also added tests for gdb.is_in_prologue only. The reason of this is that
> the tests work by checking the first instruction of a given function, as that's
> conventionally part of the prologue. Testing gdb.is_in_epilogue seems to be
> architecture-dependant (for instance, the last instruction of a function is
> reported as part of an epilogue by gdbarch_in_function_epilogue_p for ARM,
> but not always for x86_64), so I didn't include a test for it.
Hi.
We should have a test for is_in_epilogue anyway.
The canonical choice is to just make it amd64-linux specific.
API functions like these are problematic.
Users don't expect API functions to be heuristic-based,
and that is all these can ever be in the general case.
The patch does try to provide the user some guarantees
("however if the result is @code{False} you can be sure
@value{GDBN} is right."),
but it's not clear to me this will be true in the general case.
I may have missed something so I'm certainly willing to be
persuaded otherwise.
I might be ok with this patch if the functions were named something like
"maybe_is_in_prologue" and "maybe_is_in_epilogue".
That way they scream to the user (and future code readers) "Heads Up!"
next prev parent reply other threads:[~2014-10-22 19:23 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-22 14:02 Martin Galvan
2014-10-22 15:10 ` Eli Zaretskii
2014-10-22 15:14 ` Martin Galvan
2014-10-22 17:33 ` Martin Galvan
2014-10-22 17:47 ` Eli Zaretskii
2014-10-22 18:06 ` Martin Galvan
2014-10-22 18:07 ` Eli Zaretskii
2014-10-22 18:32 ` Martin Galvan
2014-10-22 18:37 ` Eli Zaretskii
2014-10-22 19:23 ` Doug Evans [this message]
2014-10-22 21:34 ` Pedro Alves
2014-10-22 21:59 ` Pedro Alves
2014-10-23 17:36 ` Martin Galvan
2014-10-23 17:57 ` Ulrich Weigand
2014-10-23 18:09 ` Martin Galvan
2014-10-23 18:14 ` Daniel Gutson
2014-10-24 2:42 ` Doug Evans
2014-10-24 14:58 ` Pedro Alves
2014-10-24 4:57 ` Doug Evans
2014-10-24 15:02 ` Pedro Alves
2014-10-24 15:34 ` Ulrich Weigand
2014-10-24 15:47 ` Doug Evans
2014-10-24 14:57 ` Pedro Alves
2014-10-24 15:13 ` Ulrich Weigand
2014-11-07 14:45 ` [push] Revert old nexti prologue check and eliminate in_prologue Pedro Alves
2014-10-24 19:49 ` [PATCH] Python API: Add gdb.is_in_prologue and gdb.is_in_epilogue Martin Galvan
2014-10-24 20:09 ` Pedro Alves
2014-10-24 21:11 ` Martin Galvan
2014-10-24 22:34 ` Pedro Alves
2014-10-27 16:40 ` Martin Galvan
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