Re: [PATCH] aarch64: Fix test_dfp_17.c for big-endian [PR 107604]

[Richard Earnshaw <Richard.Earnshaw@foss.arm.com>]

On 22/11/2022 13:09, Christophe Lyon wrote:
> 
> 
> On 11/22/22 12:33, Richard Earnshaw wrote:
>>
>>
>> On 22/11/2022 11:21, Richard Sandiford wrote:
>>> Richard Earnshaw via Gcc-patches <gcc-patches@gcc.gnu.org> writes:
>>>> On 22/11/2022 09:01, Christophe Lyon via Gcc-patches wrote:
>>>>> gcc.target/aarch64/aapcs64/test_dfp_17.c has been failing on 
>>>>> big-endian, because the _Decimal32 on-stack argument is not
>>>>> padded in the same direction depending on endianness.
>>>>>
>>>>> This patch fixes the testcase so that it expects the argument
>>>>> in the right stack location, similarly to what other tests do
>>>>> in the same directory.
>>>>>
>>>>> gcc/testsuite/ChangeLog:
>>>>>
>>>>> PR target/107604 * gcc.target/aarch64/aapcs64/test_dfp_17.c:
>>>>> Fix for big-endian. --- 
>>>>> gcc/testsuite/gcc.target/aarch64/aapcs64/test_dfp_17.c | 4
>>>>> ++++ 1 file changed, 4 insertions(+)
>>>>>
>>>>> diff --git
>>>>> a/gcc/testsuite/gcc.target/aarch64/aapcs64/test_dfp_17.c 
>>>>> b/gcc/testsuite/gcc.target/aarch64/aapcs64/test_dfp_17.c index
>>>>> 22dc462bf7c..3c45f715cf7 100644 ---
>>>>> a/gcc/testsuite/gcc.target/aarch64/aapcs64/test_dfp_17.c +++
>>>>> b/gcc/testsuite/gcc.target/aarch64/aapcs64/test_dfp_17.c @@
>>>>> -32,6 +32,10 @@ struct z b = { 9.0dd, 10.0dd, 11.0dd, 12.0dd
>>>>> }; ANON(struct z, a, D1) ANON(struct z, b, STACK) ANON(int , 5,
>>>>> W0) +#ifndef __AAPCS64_BIG_ENDIAN__ ANON(_Decimal32, f1,
>>>>> STACK+32) /* Note: no promotion to _Decimal64.  */ +#else +
>>>>> ANON(_Decimal32, f1, STACK+36) /* Note: no promotion to 
>>>>> _Decimal64.  */ +#endif LAST_ANON(_Decimal64, 0.5dd, STACK+40) #endif
>>>>
>>>> Why would a Decimal32 change stack placement based on the
>>>> endianness? Isn't it a 4-byte object?
>>>
>>> Yes, but PARM_BOUNDARY (64) sets a minimum alignment for all stack
>>>  arguments.
>>>
>>> Richard
>>
>> Ah, OK.
> Indeed, it was not immediately obvious to me either, when looking at 
> aarch64_layout_arg. aarch64_function_arg_padding comes into play, too.
> 
>>
>> I wonder if we should have a new macro in the tests, something like 
>> ANON_PADDED to describe this case and that works things out more 
>> automagically for big-endian.
> Maybe. There are many other tests under aapcs64/ which have a similar
> #ifndef __AAPCS64_BIG_ENDIAN__
> 

Yes, it could be used to clean all those up as well.

> 
>> I notice the new ANON definition is not correctly indented.
> It looks OK on my side (2 spaces).

Never mind then, it must be a quirk of how the diff is displayed.
> 
> Thanks,
> 
> Christophe
> 
>>
>> R.