Re: [qemu-s390x] [Qemu-devel] [PATCH v2 13/32] s390x/tcg: Implement VECTOR LOAD MULTIPLE

[Richard Henderson]

On 3/1/19 3:53 AM, David Hildenbrand wrote:
> +    /*
> +     * Check for possible access exceptions by trying to load the last
> +     * element. The first element will be checked first next.
> +     */
> +    t = tcg_temp_new_i64();
> +    gen_addi_and_wrap_i64(s, t, o->addr1, (v3 - v1) * 16 + 8);
> +    tcg_gen_qemu_ld_i64(t, t, get_mem_index(s), MO_TEQ);

qemu_ld expands to enough code that it is a shame to discard this value and
reload it during this loop.  Perhaps load this to t2...

> +
> +    for (;; v1++) {
> +        tcg_gen_qemu_ld_i64(t, o->addr1, get_mem_index(s), MO_TEQ);
> +        write_vec_element_i64(t, v1, 0, ES_64);

Move v1 == v3 break here...

> +        gen_addi_and_wrap_i64(s, o->addr1, o->addr1, 8);
> +        tcg_gen_qemu_ld_i64(t, o->addr1, get_mem_index(s), MO_TEQ);
> +        write_vec_element_i64(t, v1, 1, ES_64);
> +        if (v1 == v3) {
> +            break;
> +        }
> +        gen_addi_and_wrap_i64(s, o->addr1, o->addr1, 8);
> +    }

... and store t2 into v3 element 1 after the loop.


r~