Re: [RFA] Generic solution for store_struct_address

[Andrew Cagney <ac131313 at ges dot redhat dot com>]

> Andrew Cagney wrote:
>
> >
> > > On Aug 21,  7:22pm, Michael Snyder wrote:
> > >
> > >
> > >> Kevin, would you by any chance be in a position to test it on ia64
> > >> and/or
> > >> rs6000?
> > >
> > >
> > > Sure, I'll give it a spin...
> > Just FYI, given the thread:
> > http://sources.redhat.com/ml/gdb-patches/2002-08/msg00674.html
> > I'm assuming that this patch is dropped.
>
> Why?  I didn't drop it.  You commented that using generic dummy
> frames was a better solution, but it remains true that some
> targets do not use generic dummy frames, and I'm not sure that
> all targets can use them.
You mean:

> > Adding such a field to the generic dummy frame is a good idea --
> > but some architectures don't use the generic dummy frames.
> That can be fixed by converting the architecture to generic dummy frames :-)
That is a side issue --- anyone fixing a problem need only get it 
working with targets using generic dummy frames.  Any other target 
should first be converted to generic dummy frames anyway.

Anyway, summarizing posts such as:

http://sources.redhat.com/ml/gdb-patches/2002-08/msg00688.html
http://sources.redhat.com/ml/gdb-patches/2002-08/msg00705.html


> As far as I know, there are two cases:
>
> 1. a normal function forced to return:
> (gdb) break foo
> (gdb) finish
Your patch does not, and cannot fix this case.

> 2. an inferior function call:
> (gdb) print foo()
Your patch fixes this case.  However, it is far easier to replace the 
infrun.c code block:

> * Figure out the value returned by the function. */
> /* elz: I defined this new macro for the hppa architecture only.
> this gives us a way to get the value returned by the function from the stack,
> at the same address we told the function to put it.
> We cannot assume on the pa that r28 still contains the address of the returned
> structure. Usually this will be overwritten by the callee.
> I don't know about other architectures, so I defined this macro
> */
>
> #ifdef VALUE_RETURNED_FROM_STACK
> if (struct_return)
> {
> do_cleanups (retbuf_cleanup);
> return VALUE_RETURNED_FROM_STACK (value_type, struct_addr);
> }
> #endif
With the corresponding code lifted from HP/UX.

enjoy,
Andrew