Re: [PATCH 1/2 ver 3] PowerPC, function ppc64_sysv_abi_return_value add missing return value convention

[Carl Love <cel@us.ibm.com>]

On Mon, 2022-11-14 at 16:45 +0000, Ulrich Weigand wrote:
> Carl Love <cel@us.ibm.com> wrote:
> 
> > -------------------------------
> > PowerPC, function ppc64_sysv_abi_return_value add missing return
> > value convention
> > 
> > This patch address five testcase failures in gdb.cp/non-trivial-
> > retval.exp.
> > The following commit resulted in the five testcases failures on
> > PowerPC.  The
> > value returned by the function is being reported incorrectly.
> > 
> >  commit b1718fcdd1d2a5c514f8ee504ba07fb3f42b8608
> >  Author: Andrew Burgess <aburgess@redhat.com>
> >  Date:   Mon Dec 13 16:56:16 2021 +0000
> > 
> >      gdb: on x86-64 non-trivial C++ objects are returned in memory
> > 
> >      Fixes PR gdb/28681.  It was observed that after using the
> > `finish`
> >      command an incorrect value was displayed in some
> > cases.  Specifically,
> >      this behaviour was observed on an x86-64 target.
> > 
> > The function:
> > 
> >  enum return_value_convention
> >  ppc64_sysv_abi_return_value (struct gdbarch *gdbarch, struct value
> > *function,
> >                               struct type *valtype, struct regcache
> > *regcache,
> >                               gdb_byte *readbuf, const gdb_byte
> > *writebuf)
> > 
> > should return RETURN_VALUE_STRUCT_CONVENTION if the valtype->code() 
> > is
> > TYPE_CODE_STRUCT and if the language_pass_by_reference is not
> > trivially_copyable.
> > 
> > This patch adds the need code to return the value
> > RETURN_VALUE_STRUCT_CONVENTION in the case of this case.
> 
> This still has the typos Kevin pointed out.
> 
> > With this patch, the five test cases still fail but with the
> > message "Value
> > returned has type: A. Cannot determine contents".  The PowerPC ABI
> > stores the
> > address of the buffer containing the function return value in
> > register r3 on
> > entry to the function.  However, the PowerPC ABI does not guarentee
> > that r3
> > will not be modified in the function.  So when the function
> > returns, the return
> > buffer address cannot be reliably obtained from register r3.  Thus
> > the message
> > "Cannot determine contents" is appropriate in this case.
> 
> OK with the above typos fixed.
> 

Yes, I had fixed the typos once.  But it seems I didn't get the patch
updated on all of the systems where I was testing/developing the patch
and inadvertently lost the updates to this patch. 

I have fixed the typos again and updated the patch on the various
test/development systems.

Sorry about that.

                                  Carl