Re: [PATCH] gdb: mips: Fix the handling of complex type of function return value

[Andrew Burgess <aburgess@redhat.com>]

Youling Tang <tangyouling@loongson.cn> writes:

> Hi, Lancelo
>
> On 03/16/2022 04:42 PM, Lancelot SIX wrote:
>> On Wed, Mar 16, 2022 at 12:48:26PM +0800, Youling Tang wrote:
>>> $ objdump -d outputs/gdb.base/varargs/varargs
>>> 00000001200012e8 <find_max_float_real>:
>>> ...
>>>     1200013b8:   c7c10000        lwc1    $f1,0(s8)
>>>     1200013bc:   c7c00004        lwc1    $f0,4(s8)
>>>     1200013c0:   46000886        mov.s   $f2,$f1
>>>     1200013c4:   46000046        mov.s   $f1,$f0
>>>     1200013c8:   46001006        mov.s   $f0,$f2
>>>     1200013cc:   46000886        mov.s   $f2,$f1
>>>     1200013d0:   03c0e825        move    sp,s8
>>>     1200013d4:   dfbe0038        ld      s8,56(sp)
>>>     1200013d8:   67bd0080        daddiu  sp,sp,128
>>>     1200013dc:   03e00008        jr      ra
>>>     1200013e0:   00000000        nop
>>>
>>>  From the above disassembly, we can see that when the return value of the
>>> function is a complex type and len <= 2 * MIPS64_REGSIZE, the return value
>>> will be passed through $f0 and $f2, so fix the corresponding processing
>>> in mips_n32n64_return_value().
>>>
>>> $ make check RUNTESTFLAGS='GDB=../gdb gdb.base/varargs.exp --outdir=test'
>>>
>>> Before applying the patch:
>>>   FAIL: gdb.base/varargs.exp: print find_max_float_real(4, fc1, fc2, fc3, fc4)
>>>   FAIL: gdb.base/varargs.exp: print find_max_double_real(4, dc1, dc2, dc3, dc4)
>>>
>>>   # of expected passes		9
>>>   # of unexpected failures	2
>>>
>>> After applying the patch:
>>>   # of expected passes            11
>>>
>>> Signed-off-by: Youling Tang <tangyouling@loongson.cn>
>>> ---
>>>   gdb/mips-tdep.c | 3 ++-
>>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/gdb/mips-tdep.c b/gdb/mips-tdep.c
>>> index 7e37578..cddb8f8 100644
>>> --- a/gdb/mips-tdep.c
>>> +++ b/gdb/mips-tdep.c
>>> @@ -5224,9 +5224,10 @@ mips_n32n64_return_value (struct gdbarch *gdbarch, struct value *function,
>>>   
>>>     if (TYPE_LENGTH (type) > 2 * MIPS64_REGSIZE)
>>>       return RETURN_VALUE_STRUCT_CONVENTION;
>>> -  else if (type->code () == TYPE_CODE_FLT
>>> +  else if ((type->code () == TYPE_CODE_FLT
>>>   	   && TYPE_LENGTH (type) == 16
>>>   	   && tdep->mips_fpu_type != MIPS_FPU_NONE)
>> Hi,
>>
>> Just minor note, those 2 lines above should be indented 2 more space I
>> think (so the && operator continues to vertically align with "type->code
>> ()").
>>
>>> +	   || (type->code () == TYPE_CODE_COMPLEX))
>> I do not think the extra set of parens are requires (but they do no harm
>> either).
> Ok, I will modify this code style in the next version.

This change looks good to me with the style adjusments that Lancelot
pointed out.

Thanks,
Andrew