From: Tom Tromey <tom@tromey.com>
To: Simon Marchi <simark@simark.ca>
Cc: John Darrington <john@darrington.wattle.id.au>,
gdb-patches@sourceware.org
Subject: Re: [PATCH 3/3] GDB: New target s12z
Date: Tue, 28 Aug 2018 15:35:00 -0000 [thread overview]
Message-ID: <87pny27bcn.fsf@tromey.com> (raw)
In-Reply-To: <510acbee-2338-0c20-8e32-8d6ef83be3e1@simark.ca> (Simon Marchi's message of "Sun, 26 Aug 2018 14:15:03 -0400")
>>>>> "Simon" == Simon Marchi <simark@simark.ca> writes:
Simon> The usual thing to do (I looked at a few other arches) is to use the same value as the
Simon> canonical frame address as defined by DWARF (Section 6.4 in DWARF5.pdf), which is the
Simon> value of the stack pointer just before that frame was created.
Simon> This is of course not mandatory, but I suppose that adhering to this de facto rule could
Simon> make things clearer.
ISTR there was one obscure case where it was necessary -- I think some
architectures have a special epilogue unwinder, and it was important
that this unwinder agree with the DWARF unwinder about the CFA in some
case. This was many years ago so as you can tell I don't really recall
the details.
Anyway, I think using the current frame's SP will fail if the function
uses alloca -- the frame id will change across a step. The CFA is
usually used in order to make the frame id invariant. There may be a
comment in one of the frame*.h files explaining this.
Tom
next prev parent reply other threads:[~2018-08-28 15:35 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-23 17:35 [PATCH 1/3] gdb: Added builtin types for 24 bit integers John Darrington
2018-08-23 17:35 ` [PATCH 3/3] GDB: New target s12z John Darrington
2018-08-23 17:56 ` Eli Zaretskii
2018-08-26 17:19 ` Simon Marchi
2018-08-26 17:41 ` John Darrington
2018-08-26 18:16 ` Simon Marchi
2018-08-26 22:55 ` Simon Marchi
2018-08-27 6:30 ` John Darrington
2018-08-27 12:54 ` Simon Marchi
2018-08-28 15:35 ` Tom Tromey [this message]
2018-08-23 17:35 ` [PATCH 2/3] GDB: Add support for 24 bit addresses John Darrington
2018-08-24 20:34 ` Simon Marchi
2018-08-25 4:56 ` John Darrington
2018-08-23 17:55 ` [PATCH 1/3] gdb: Added builtin types for 24 bit integers Eli Zaretskii
2018-08-23 19:41 ` Simon Marchi
2018-08-23 20:04 ` John Darrington
2018-08-23 20:35 ` Simon Marchi
2018-08-24 6:11 ` John Darrington
2018-08-24 15:09 ` Simon Marchi
2018-08-24 15:29 ` John Darrington
2018-08-24 20:37 ` Simon Marchi
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