From: Andrew Cagney <ac131313@redhat.com>
To: Daniel Jacobowitz <drow@mvista.com>
Cc: gdb@sources.redhat.com
Subject: Re: frame->unwind->this_base()
Date: Tue, 18 Mar 2003 04:29:00 -0000 [thread overview]
Message-ID: <3E7670F6.9060906@redhat.com> (raw)
In-Reply-To: <20030317193537.GA11288@nevyn.them.org>
> On Mon, Mar 17, 2003 at 01:20:28PM -0500, Andrew Cagney wrote:
>
>>
>
>> >>>GDB's frame code also makes available the get_frame_base() method. While
>> >>>the default implementation returns get_frame_id().base, I think there is
>> >>>going to need to be a per-frame frame->unwind->this_base method.
>
>> >
>
>> >>
>> >>get_frame_base() returns ->frame and NOT ->id.base.
>
>> >
>> >
>> >OK, I'm definitely going around in confused little circles. Don't the
>> >two statements above disagree?
>
>>
>> No. See get_prev_frame() where it is defaulting ->frame to ->id.base.
>>
>
>> > The current get_frame_base does return
>> >->frame but you also say above that get_frame_base should return
>> >get_frame_id().base.
>
>>
>> No. Default to get_frame_id().base.
>
>
> So is that supposed to be a statement about the future in the first
> paragraph? It's sure not worded as one, no wonder I'm confused.
The present. GDB historically has had FRAME_FP and frame->frame and
their intended purposes were overloaded: per frame unique identifier,
frame base pointer, ...
Frame ID provides a per-frame unique identifier.
>> >Conceptually, are frame->frame and frame->id.base supposed to be the
>> >same?
>
>>
>> No?
>
>
> Then could you enlighten me as to what the difference is supposed to
> be?
For dwarf2, check the spec where it discuss CFA (see CFI) and frame-base
(see 3.3.5).
CFA + &function == frame_id
A per frame unique identifier that must be constant through out the
lifetime of the frame. CFI recommends the top-of-stack from the
previous frame.
frame-base == get_frame_base()
What ever the debug info would like it to be. The ISAs ABI will
provide a strong set of guidelines though (if, for a framed function it
doesn't match what the user expects, the'll likely complain :-). It
will often point into the middle of the stack frame.
Andrew
next prev parent reply other threads:[~2003-03-18 4:29 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-03-16 22:04 frame->unwind->this_base() Andrew Cagney
2003-03-16 22:10 ` frame->unwind->this_base() Daniel Jacobowitz
2003-03-17 0:09 ` frame->unwind->this_base() Andrew Cagney
2003-03-17 0:14 ` frame->unwind->this_base() Daniel Jacobowitz
2003-03-17 16:22 ` frame->unwind->this_base() Andrew Cagney
2003-03-17 16:38 ` frame->unwind->this_base() Daniel Jacobowitz
2003-03-17 16:56 ` frame->unwind->this_base() Andrew Cagney
2003-03-17 17:11 ` frame->unwind->this_base() Daniel Jacobowitz
2003-03-17 18:20 ` frame->unwind->this_base() Andrew Cagney
2003-03-17 19:35 ` frame->unwind->this_base() Daniel Jacobowitz
2003-03-18 4:29 ` Andrew Cagney [this message]
2003-03-18 5:13 ` frame->unwind->this_base() Daniel Jacobowitz
2003-03-18 15:22 ` frame->unwind->this_base() Andrew Cagney
2003-03-18 16:38 ` frame->unwind->this_base() Daniel Jacobowitz
2003-03-18 17:02 ` frame->unwind->this_base() Andrew Cagney
2003-03-18 17:11 ` frame->unwind->this_base() Daniel Jacobowitz
2003-03-18 17:28 ` frame->unwind->this_base() Andrew Cagney
2003-03-18 17:38 ` frame->unwind->this_base() Daniel Jacobowitz
2003-03-18 20:22 ` frame->unwind->this_base() Andrew Cagney
2003-03-19 14:11 ` frame->unwind->this_base() Daniel Jacobowitz
2003-03-19 15:24 ` frame->unwind->this_base() Andrew Cagney
2003-03-19 15:32 ` frame->unwind->this_base() Daniel Jacobowitz
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