Re: [RFA] Generic solution for store_struct_address

[Andrew Cagney <ac131313@ges.redhat.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