On Tue, Apr 10, 2018 at 3:58 PM, Bin.Cheng <[email protected]> wrote:
> On Tue, Apr 10, 2018 at 2:26 PM, Jakub Jelinek <[email protected]> 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 <[email protected]>
>>>
>>> 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.
Hmm, though it's UB in this case, is it OK for niter analysis gives
below results?
Analyzing # of iterations of loop 1
exit condition [126, + , 18446744073709551615] != 0
bounds on difference of bases: -126 ... -126
result:
# of iterations 126, bounded by 126
I don't really follow last piece of code in number_of_iterations_ne:
/* Let nsd (step, size of mode) = d. If d does not divide c, the loop
is infinite. Otherwise, the number of iterations is
(inverse(s/d) * (c/d)) mod (size of mode/d). */
bits = num_ending_zeros (s);
bound = build_low_bits_mask (niter_type,
(TYPE_PRECISION (niter_type)
- tree_to_uhwi (bits)));
d = fold_binary_to_constant (LSHIFT_EXPR, niter_type,
build_int_cst (niter_type, 1), bits);
s = fold_binary_to_constant (RSHIFT_EXPR, niter_type, s, bits);
if (!exit_must_be_taken)
{
/* If we cannot assume that the exit is taken eventually, record the
assumptions for divisibility of c. */
assumption = fold_build2 (FLOOR_MOD_EXPR, niter_type, c, d);
assumption = fold_build2 (EQ_EXPR, boolean_type_node,
assumption, build_int_cst (niter_type, 0));
if (!integer_nonzerop (assumption))
niter->assumptions = fold_build2 (TRUTH_AND_EXPR, boolean_type_node,
niter->assumptions, assumption);
}
c = fold_build2 (EXACT_DIV_EXPR, niter_type, c, d);
tmp = fold_build2 (MULT_EXPR, niter_type, c, inverse (s, bound));
niter->niter = fold_build2 (BIT_AND_EXPR, niter_type, tmp, bound);
return true;
Though infinite niters is mentioned, I don't see it's handled?
Thanks,
bin
> 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
