Re: Xtensa port

[Daniel Jacobowitz <drow@false.org>]

On Fri, Sep 22, 2006 at 05:28:04PM -0700, Maxim Grigoriev wrote:
> I need an FP number. And, the most reliable source for this information 
> is DWARF data.

You're relying on the presence of DWARF symbolic debug information, and
yet you can't use DWARF-2 unwinding (.debug_frame, dwarf2-frame.c) and
avoid the issue entirely?  And you have no way to determine this
reliably from instruction scanning, like other ports do (see
prologue-value.c)?  I'd recommend either in preference to this.
I can't tell you how much work either would be, because I don't
know much about Xtensa.

The problem with using DW_AT_frame_base is that there's no guarantee
it is related to what you want it to be in this context.  The compiler
has a lot of freedom in what it places there; it's only meaningful
in context of local variable locations in the same frame.  For
instance, you're completely ignoring any bias.

> If there is no such "utility" request ( which I thought is the case ), 
> I'd need to introduce it. That would be an update to the generic part of 
> GDB. And, I was given specific instructions to avoid any updates to the 
> generic code, when I submit an architecture port.

I don't know why.  They should generally be done separately, with
individual explanations, but hacking around the GDB core instead of
fixing it is generally frowned upon.

-- 
Daniel Jacobowitz
CodeSourcery