Re: [PATCH PR85190]Adjust pointer for aligned access

[Bin.Cheng]

On Tue, Apr 10, 2018 at 2:26 PM, Jakub Jelinek <ja...@redhat.com> wrote:
> On Tue, Apr 10, 2018 at 09:55:35AM +0000, Bin Cheng wrote:
>> Hi Rainer, could you please help me double check that this solves the issue?
>>
>> Thanks,
>> bin
>>
>> gcc/testsuite
>> 2018-04-10  Bin Cheng  <bin.ch...@arm.com>
>>
>>       PR testsuite/85190
>>       * gcc.dg/vect/pr81196.c: Adjust pointer for aligned access.
>
>> diff --git a/gcc/testsuite/gcc.dg/vect/pr81196.c 
>> b/gcc/testsuite/gcc.dg/vect/pr81196.c
>> index 46d7a9e..15320ae 100644
>> --- a/gcc/testsuite/gcc.dg/vect/pr81196.c
>> +++ b/gcc/testsuite/gcc.dg/vect/pr81196.c
>> @@ -4,14 +4,14 @@
>>
>>  void f(short*p){
>>    p=(short*)__builtin_assume_aligned(p,64);
>> -  short*q=p+256;
>> +  short*q=p+255;
>>    for(;p!=q;++p,--q){
>>      short t=*p;*p=*q;*q=t;
>
> This is UB then though, because p will never be equal to q.
Sorry I already checked in, will try to correct it in another patch.

Thanks,
bin
>
>>    }
>>  }
>>  void b(short*p){
>>    p=(short*)__builtin_assume_aligned(p,64);
>> -  short*q=p+256;
>> +  short*q=p+255;
>>    for(;p<q;++p,--q){
>>      short t=*p;*p=*q;*q=t;
>
> This one is fine, sure.
>
>         Jakub