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

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

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.

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.

I notice the new ANON definition is not correctly indented.

R.