2013/6/13 Chung-Ju Wu <jasonwucj@xxxxxxxxx>:
> 2013/6/13 Terry Guo <flameroc@xxxxxxxxx>:
>> Hi there,
>>
>> For the below simple case, I think poly1[i] should be hoisted to
>> outermost loop to avoid loading from innermost loop at each iteration.
>> But for arm-none-eabi target like cortex-m4, gcc fails to do so. Is
>> this a normal case or a missing optimization? Please advise.
>>
>> void
>> PolyMul (float *poly1, unsigned int n1,
>> float *poly2, unsigned int n2,
>> float *polymul, unsigned int *nmul)
>> {
>> unsigned int i, j;
>>
>> for (i = 0; i <= n1; i++)
>> for (j = 0; j <= n2; j++)
>> polymul[i+j] += poly1[i] * poly2[j];
>> }
>>
>> Thanks.
>>
>> BR,
>> Terry
>
> Unless you use 'restrict' qualifier to the pointer type,
> I don't think compiler can do such optimization due to aliasing issue.
>
Also I don't think -fstrict-aliasing could help for your case.
Becase poly1, poly2, and polymul are all 'float *' pointer type.
Best regards,
jasonwucj
