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References: <20190411100836.646-1-david@redhat.com>
	<20190411100836.646-42-david@redhat.com>
From: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <0871b6f8-6073-4311-78a5-4772817a009e@linaro.org>
Date: Fri, 12 Apr 2019 20:28:53 -1000
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Subject: Re: [Qemu-devel] [PATCH v1 41/41] s390x/tcg: Implement VECTOR TEST
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To: David Hildenbrand <david@redhat.com>, qemu-devel@nongnu.org
Cc: qemu-s390x@nongnu.org, Cornelia Huck <cohuck@redhat.com>, Thomas Huth <thuth@redhat.com>, Richard Henderson <rth@twiddle.net>

On 4/11/19 12:08 AM, David Hildenbrand wrote:
> +void HELPER(gvec_vtm)(void *v1, const void *v2, CPUS390XState *env,
> +                      uint32_t desc)
> +{
> +    S390Vector tmp;
> +
> +    s390_vec_and(&tmp, v1, v2);
> +    if (s390_vec_is_zero(&tmp)) {
> +        /* Selected bits all zeros; or all mask bits zero */
> +        env->cc_op = 0;
> +    } else if (s390_vec_equal(&tmp, v2)) {
> +        /* Selected bits all ones */
> +        env->cc_op = 3;
> +    } else {
> +        /* Selected bits a mix of zeros and ones */
> +        env->cc_op = 1;
> +    }
> +}

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

However, if you return this value, then you can do

DEF_HELPER_FLAGS_4(gvec_vtm, TCG_CALL_NO_RWG_SE, i32, cptr, cptr)

static DisasJumpType op_vtm(DisasContext *s, DisasOps *o)
{
    TCGv_ptr p1 = tcg_temp_new_ptr();
    TCGv_ptr p2 = tcg_temp_new_ptr();

    tcg_gen_addi_ptr(p1, cpu_env,
        vec_full_reg_offset(get_field(s->fields, v1)));
    tcg_gen_addi_ptr(p2, cpu_env,
        vec_full_reg_offset(get_field(s->fields, v2)));
    gen_helper_gvec_vtm(cc_op, p1, p2);
    tcg_temp_free_ptr(p1);
    tcg_temp_free_ptr(p2);
    set_cc_static(s);
    return DISAS_NEXT;
}

Perhaps it doesn't matter though, since use of vtm probably implies a jump,
which implies end of TB, which means that registers are going to get saved to
backing store anyway.


r~