Re: [PATCH 3/3] target/ppc: Implement Vector Mask Move insns

[Richard Henderson]

On 11/10/21 7:56 PM, matheus.ferst@eldorado.org.br wrote:
> +static bool do_mtvsrm(DisasContext *ctx, arg_VX_tb *a, unsigned vece)
> +{
> +    const uint64_t elem_length = 8 << vece, highest_bit = 15 >> vece;
> +    int i;
> +    TCGv_i64 t0, t1, zero, ones;
> +
> +    REQUIRE_INSNS_FLAGS2(ctx, ISA310);
> +    REQUIRE_VECTOR(ctx);
> +
> +    t0 = tcg_const_i64(0);
> +    t1 = tcg_temp_new_i64();
> +    zero = tcg_constant_i64(0);
> +    ones = tcg_constant_i64(MAKE_64BIT_MASK(0, elem_length));
> +
> +    for (i = 1 << highest_bit; i > 1 << (highest_bit / 2); i >>= 1) {
> +        tcg_gen_shli_i64(t0, t0, elem_length);
> +        tcg_gen_ext_tl_i64(t1, cpu_gpr[a->vrb]);
> +        tcg_gen_andi_i64(t1, t1, i);
> +        tcg_gen_movcond_i64(TCG_COND_NE, t1, t1, zero, ones, zero);
> +        tcg_gen_or_i64(t0, t0, t1);
> +    }

We can do better than that.

    tcg_gen_extu_tl_i64(t0, gpr);
    tcg_gen_extract_i64(t1, t0, elem_count_half, elem_count_half);
    tcg_gen_extract_i64(t0, t0, 0, elem_count_half);

    /*
     * Spread the bits into their respective elements.
     * E.g. for bytes:
     * 00000000000000000000000000000000000000000000000000000000abcdefgh
     *   << 32-4
     * 0000000000000000000000000000abcdefgh0000000000000000000000000000
     *   |
     * 0000000000000000000000000000abcdefgh00000000000000000000abcdefgh
     *   << 16-2
     * 00000000000000abcdefgh00000000000000000000abcdefgh00000000000000
     *   |
     * 00000000000000abcdefgh000000abcdefgh000000abcdefgh000000abcdefgh
     *   << 8-1
     * 0000000abcdefgh000000abcdefgh000000abcdefgh000000abcdefgh0000000
     *   |
     * 0000000abcdefgXbcdefgXbcdefgXbcdefgXbcdefgXbcdefgXbcdefgXbcdefgh
     *   & dup(1)
     * 0000000a0000000b0000000c0000000d0000000e0000000f0000000g0000000h
     *   * 0xff
     * aaaaaaaabbbbbbbbccccccccddddddddeeeeeeeeffffffffgggggggghhhhhhhh
     */

    for (i = elem_count_half, j = 32; i > 0; i >>= 1, j >>= 1) {
        tcg_gen_shli_i64(s0, t0, j - i);
        tcg_gen_shli_i64(s1, t1, j - i);
        tcg_gen_or_i64(t0, t0, s0);
        tcg_gen_or_i64(t1, t1, s1);
    }

    c = dup_const(vece, 1);
    tcg_gen_andi_i64(t0, t0, c);
    tcg_gen_andi_i64(t1, t1, c);

    c = MAKE_64BIT_MASK(0, elem_length);
    tcg_gen_muli_i64(t0, t0, c);
    tcg_gen_muli_i64(t1, t1, c);

    set_avr64(a->vrt, t0, false);
    set_avr64(a->vrt, t1, true);



r~