On 9/11/19 2:25 AM, liuzhiwei wrote:
> +/* vredsum.vs vd, vs2, vs1, vm # vd[0] = sum(vs1[0] , vs2[*]) */
> +void VECTOR_HELPER(vredsum_vs)(CPURISCVState *env, uint32_t vm, uint32_t rs1,
> + uint32_t rs2, uint32_t rd)
> +{
>
> + int width, lmul, vl, vlmax;
> + int i, j, src2;
> + uint64_t sum = 0;
> +
> + lmul = vector_get_lmul(env);
> + vector_lmul_check_reg(env, lmul, rs2, false);
> +
> + if (vector_vtype_ill(env) || vector_overlap_vm_common(lmul, vm, rd)) {
> + riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
> + return;
> + }
> + if (env->vfp.vstart != 0) {
> + riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
> + return;
> + }
> +
> + vl = env->vfp.vl;
> + if (vl == 0) {
> + return;
> + }
> +
> + width = vector_get_width(env);
> + vlmax = vector_get_vlmax(env);
> +
> + for (i = 0; i < VLEN / 64; i++) {
> + env->vfp.vreg[rd].u64[i] = 0;
> + }
> +
There is no requirement that I see for vd != vs1 && vd != vs2. Thus clearing
vd before the operation may clobber the inputs.
> + if (i < vl) {
> + switch (width) {
> + case 8:
> + if (vector_elem_mask(env, vm, width, lmul, i)) {
> + sum += env->vfp.vreg[src2].u8[j];
> + }
> + if (i == 0) {
> + sum += env->vfp.vreg[rs1].u8[0];
> + }
Hoist the rs1 case outside the loop.
r~
