Re: [PATCH] [AArch64] Fix PR gdb/28681

[Simon Marchi via Gdb-patches <gdb-patches@sourceware.org>]

On 2022-01-04 13:44, Luis Machado wrote:
> On 1/4/22 3:09 PM, Simon Marchi wrote:
>>
>>
>> On 2022-01-04 12:22, Luis Machado via Gdb-patches wrote:
>>> This is the same as commit b1718fcdd1d2a5c514f8ee504ba07fb3f42b8608, but
>>> fixing things for AArch64.
>>>
>>> With the patch, gdb.cp/non-trivial-retval.exp has full passes on
>>> AArch64-Linux Ubuntu 20.04/18.04.
>>> ---
>>>   gdb/aarch64-tdep.c | 9 +++++++++
>>>   1 file changed, 9 insertions(+)
>>>
>>> diff --git a/gdb/aarch64-tdep.c b/gdb/aarch64-tdep.c
>>> index 70fb66954a4..802762f303c 100644
>>> --- a/gdb/aarch64-tdep.c
>>> +++ b/gdb/aarch64-tdep.c
>>> @@ -2323,6 +2323,15 @@ aarch64_extract_return_value (struct type *type, struct regcache *regs,
>>>         valbuf += X_REGISTER_SIZE;
>>>       }
>>>       }
>>> +  else if (!language_pass_by_reference (type).trivially_copyable)
>>> +    {
>>> +      /* If the object is a non-trivial C++ object, the result is passed as a
>>> +     pointer stored in X0.  */
>>> +      CORE_ADDR addr;
>>> +
>>> +      regs->cooked_read (AARCH64_X0_REGNUM, &addr);
>>> +      read_memory (addr, valbuf, TYPE_LENGTH (type));
>>> +    }
>>>     else
>>>       {
>>>         /* For a structure or union the behaviour is as if the value had
>>
>> I'll let somebody else review this (probably Andrew), but please change the
>> patch subject to something descriptive, not just the bug number.
> 
> Did you want the entire bugzilla PR subject or something else? I can't really tell from your reply, sorry.

No, not the bugzilla title (which is `Wrong pretty-printed unique_ptr
value when using "finish"`), since that is a distant symptom of the
problem you fix.  The subject should state what you are fixing, so
something about the handling of trivially copyable return values on
AArch64 (something like that, I didn't follow the resolution of the bug
close enough).

Simon