On 23.05.19 14:27, Richard Henderson wrote:
> On 5/23/19 3:50 AM, David Hildenbrand wrote:
>> /*
>> * Returns the number of bits composing one element.
>> */
>> static uint8_t get_element_bits(uint8_t es)
>> {
>> return (1 << es) * BITS_PER_BYTE;
>> }
>>
>> /*
>> * Returns the bitmask for a single element.
>> */
>> static uint64_t get_single_element_mask(uint8_t es)
>> {
>> return -1ull >> (64 - get_element_bits(es));
>> }
>>
>> /*
>> * Returns the bitmask for a single element (excluding the MSB).
>> */
>> static uint64_t get_single_element_lsbs_mask(uint8_t es)
>> {
>> return -1ull >> (65 - get_element_bits(es));
>> }
>>
>> /*
>> * Returns the bitmasks for multiple elements (excluding the MSBs).
>> */
>> static uint64_t get_element_lsbs_mask(uint8_t es)
>> {
>> return dup_const(es, get_single_element_lsbs_mask(es));
>> }
>>
>> static int vfae(void *v1, const void *v2, const void *v3, bool in,
>> bool rt, bool zs, uint8_t es)
>> {
>> const uint64_t mask = get_element_lsbs_mask(es);
>> const int bits = get_element_bits(es);
>> uint64_t a0, a1, b0, b1, e0, e1, t0, t1, z0, z1;
>> uint64_t first_zero = 16;
>> uint64_t first_equal;
>> int i;
>>
>> a0 = s390_vec_read_element64(v2, 0);
>> a1 = s390_vec_read_element64(v2, 1);
>> b0 = s390_vec_read_element64(v3, 0);
>> b1 = s390_vec_read_element64(v3, 1);
>> e0 = 0;
>> e1 = 0;
>> /* compare against equality with every other element */
>> for (i = 0; i < 64; i += bits) {
>> t0 = i ? rol64(b0, i) : b0;
>> t1 = i ? rol64(b1, i) : b1;
>> e0 |= zero_search(a0 ^ t0, mask);
>> e0 |= zero_search(a0 ^ t1, mask);
>> e1 |= zero_search(a1 ^ t0, mask);
>> e1 |= zero_search(a1 ^ t1, mask);
>> }
>
> I don't see that this is doing what you want. You're shifting one element of
> B
> down, but not broadcasting it so that it is compared against every element of
> A.
>
> I'd expect something like
>
> t0 = dup_const(es, b0 >> i);
> t1 = dup_const(es, b1 >> i);
>
> (I also don't see what rol is getting you that shift doesn't.)
Let's assume
a0 = [0, 1, 2, 3]
a1 = [4, 5, 6, 7]
b0 = [8, 8, 8, 4]
b1 = [8, 8, 8, 8]
What I would check is
First iteration
a0 == [8, 8, 8, 4] -> no match
a0 == [8, 8, 8, 8] -> no match
a1 == [8, 8, 8, 4] -> no match
a1 == [8, 8, 8, 8] -> no match
Second iteration
a0 == [8, 8, 4, 8] -> no match
a0 == [8, 8, 8, 8] -> no match
a1 == [8, 8, 4, 8]
a1 == [8, 8, 8, 8] -> no match
...
Last iteration
a0 == [4, 8, 8, 8] -> no match
a0 == [8, 8, 8, 8] -> no match
a1 == [4, 8, 8, 8] -> match in first element
a1 == [8, 8, 8, 8] -> no match
What am i missing?
--
Thanks,
David / dhildenb
