On 17 February 2018 at 18:22, Richard Henderson
<richard.hender...@linaro.org> wrote:
> Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
> ---
> target/arm/helper-sve.h | 2 +
> target/arm/sve_helper.c | 31 ++++++++++++++++
> target/arm/translate-sve.c | 92
> ++++++++++++++++++++++++++++++++++++++++++++++
> target/arm/sve.decode | 8 ++++
> 4 files changed, 133 insertions(+)
>
> diff --git a/target/arm/helper-sve.h b/target/arm/helper-sve.h
> index dd4f8f754d..1863106d0f 100644
> --- a/target/arm/helper-sve.h
> +++ b/target/arm/helper-sve.h
> @@ -678,3 +678,5 @@ DEF_HELPER_FLAGS_4(sve_brkn, TCG_CALL_NO_RWG, void, ptr,
> ptr, ptr, i32)
> DEF_HELPER_FLAGS_4(sve_brkns, TCG_CALL_NO_RWG, i32, ptr, ptr, ptr, i32)
>
> DEF_HELPER_FLAGS_3(sve_cntp, TCG_CALL_NO_RWG, i64, ptr, ptr, i32)
> +
> +DEF_HELPER_FLAGS_3(sve_while, TCG_CALL_NO_RWG, i32, ptr, i32, i32)
> diff --git a/target/arm/sve_helper.c b/target/arm/sve_helper.c
> index dd884bdd1c..80b78da834 100644
> --- a/target/arm/sve_helper.c
> +++ b/target/arm/sve_helper.c
> @@ -2716,3 +2716,34 @@ uint64_t HELPER(sve_cntp)(void *vn, void *vg, uint32_t
> pred_desc)
> }
> return sum;
> }
> +
> +uint32_t HELPER(sve_while)(void *vd, uint32_t count, uint32_t pred_desc)
This could really use a comment about what part of the overall
instruction it's doing.
> +{
> + uintptr_t oprsz = extract32(pred_desc, 0, SIMD_OPRSZ_BITS) + 2;
> + intptr_t esz = extract32(pred_desc, SIMD_DATA_SHIFT, 2);
> + uint64_t esz_mask = pred_esz_masks[esz];
> + ARMPredicateReg *d = vd;
> + uint32_t flags;
> + intptr_t i;
> +
> + /* Begin with a zero predicate register. */
> + flags = do_zero(d, oprsz);
> + if (count == 0) {
> + return flags;
> + }
> +
> + /* Scale from predicate element count to bits. */
> + count <<= esz;
> + /* Bound to the bits in the predicate. */
> + count = MIN(count, oprsz * 8);
> +
> + /* Set all of the requested bits. */
> + for (i = 0; i < count / 64; ++i) {
> + d->p[i] = esz_mask;
> + }
> + if (count & 63) {
> + d->p[i] = ~(-1ull << (count & 63)) & esz_mask;
> + }
> +
> + return predtest_ones(d, oprsz, esz_mask);
> +}
> diff --git a/target/arm/translate-sve.c b/target/arm/translate-sve.c
> index 038800cc86..4b92a55c21 100644
> --- a/target/arm/translate-sve.c
> +++ b/target/arm/translate-sve.c
> @@ -2847,6 +2847,98 @@ static void trans_SINCDECP_z(DisasContext *s,
> arg_incdec2_pred *a,
> do_sat_addsub_vec(s, a->esz, a->rd, a->rn, val, a->u, a->d);
> }
>
> +static void trans_WHILE(DisasContext *s, arg_WHILE *a, uint32_t insn)
> +{
> + TCGv_i64 op0 = read_cpu_reg(s, a->rn, 1);
> + TCGv_i64 op1 = read_cpu_reg(s, a->rm, 1);
> + TCGv_i64 t0 = tcg_temp_new_i64();
> + TCGv_i64 t1 = tcg_temp_new_i64();
> + TCGv_i32 t2, t3;
> + TCGv_ptr ptr;
> + unsigned desc, vsz = vec_full_reg_size(s);
> + TCGCond cond;
> +
> + if (!a->sf) {
> + if (a->u) {
> + tcg_gen_ext32u_i64(op0, op0);
> + tcg_gen_ext32u_i64(op1, op1);
> + } else {
> + tcg_gen_ext32s_i64(op0, op0);
> + tcg_gen_ext32s_i64(op1, op1);
> + }
> + }
> +
> + /* For the helper, compress the different conditions into a computation
> + * of how many iterations for which the condition is true.
> + *
> + * This is slightly complicated by 0 <= UINT64_MAX, which is nominally
> + * 2**64 iterations, overflowing to 0. Of course, predicate registers
> + * aren't that large, so any value >= predicate size is sufficient.
> + */
> + tcg_gen_sub_i64(t0, op1, op0);
> +
> + /* t0 = MIN(op1 - op0, vsz). */
> + if (a->eq) {
> + /* Equality means one more iteration. */
> + tcg_gen_movi_i64(t1, vsz - 1);
> + tcg_gen_movcond_i64(TCG_COND_LTU, t0, t0, t1, t0, t1);
> + tcg_gen_addi_i64(t0, t0, 1);
> + } else {
> + tcg_gen_movi_i64(t1, vsz);
> + tcg_gen_movcond_i64(TCG_COND_LTU, t0, t0, t1, t0, t1);
> + }
> +
> + /* t0 = (condition true ? t0 : 0). */
> + cond = (a->u
> + ? (a->eq ? TCG_COND_LEU : TCG_COND_LTU)
> + : (a->eq ? TCG_COND_LE : TCG_COND_LT));
> + tcg_gen_movi_i64(t1, 0);
> + tcg_gen_movcond_i64(cond, t0, op0, op1, t0, t1);
> +
> + t2 = tcg_temp_new_i32();
> + tcg_gen_extrl_i64_i32(t2, t0);
> + tcg_temp_free_i64(t0);
> + tcg_temp_free_i64(t1);
> +
> + desc = (vsz / 8) - 2;
> + desc = deposit32(desc, SIMD_DATA_SHIFT, 2, a->esz);
> + t3 = tcg_const_i32(desc);
> +
> + ptr = tcg_temp_new_ptr();
> + tcg_gen_addi_ptr(ptr, cpu_env, pred_full_reg_offset(s, a->rd));
> +
> + gen_helper_sve_while(t2, ptr, t2, t3);
> + do_pred_flags(t2);
> +
> + tcg_temp_free_ptr(ptr);
> + tcg_temp_free_i32(t2);
> + tcg_temp_free_i32(t3);
> +}
I got confused by this -- it is too far different from what the
pseudocode is doing. Could we have more explanatory comments, please?
thanks
-- PMM
