在 2022/3/7 下午5:43, ~eopxd 写道:
> From: eopXD <eop.chen@sifive.com>
>
> Signed-off-by: eop Chen <eop.chen@sifive.com>
> Reviewed-by: Frank Chang <frank.chang@sifive.com>
> ---
> target/riscv/vector_helper.c | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/target/riscv/vector_helper.c b/target/riscv/vector_helper.c
> index 6d79908ffe..9a08d14689 100644
> --- a/target/riscv/vector_helper.c
> +++ b/target/riscv/vector_helper.c
> @@ -1317,6 +1317,9 @@ void HELPER(NAME)(void *vd, void *v0, void *vs1, void *vs2, \
> { \
> uint32_t vm = vext_vm(desc); \
> uint32_t vl = env->vl; \
> + uint32_t vlmax = \
> + vext_get_vlmax(env_archcpu(env), env->vtype); \
> + uint32_t vta = vext_vta(desc); \
> uint32_t i; \
> \
> for (i = env->vstart; i < vl; i++) { \
> @@ -1328,6 +1331,12 @@ void HELPER(NAME)(void *vd, void *v0, void *vs1, void *vs2, \
> vext_set_elem_mask(vd, i, DO_OP(s2, s1)); \
> } \
> env->vstart = 0; \
> + /* clear tail element */ \
> + if (vta) { \
> + for (; i < vlmax; i++) { \
> + vext_set_elem_mask(vd, i, 1); \
> + } \
> + } \
> }
>
Why comment 'clear tail element' here?
"In addition, except for mask load instructions, any element in the tail
of a mask result can also be written with the value the
mask-producing operation would have calculated with vl=VLMAX.
Furthermore, for mask-logical instructions and vmsbf.m,
vmsif.m, vmsof.m mask-manipulation instructions, any element in the tail
of the result can be written with the value the
mask-producing operation would have calculated with vl=VLEN, SEW=8, and
LMUL=8 (i.e., all bits of the mask register can
be overwritten)."
Regards,
Weiwei Li
> GEN_VEXT_CMP_VV(vmseq_vv_b, uint8_t, H1, DO_MSEQ)
> @@ -1366,6 +1375,9 @@ void HELPER(NAME)(void *vd, void *v0, target_ulong s1, void *vs2, \
> { \
> uint32_t vm = vext_vm(desc); \
> uint32_t vl = env->vl; \
> + uint32_t vlmax = \
> + vext_get_vlmax(env_archcpu(env), env->vtype); \
> + uint32_t vta = vext_vta(desc); \
> uint32_t i; \
> \
> for (i = env->vstart; i < vl; i++) { \
> @@ -1377,6 +1389,12 @@ void HELPER(NAME)(void *vd, void *v0, target_ulong s1, void *vs2, \
> DO_OP(s2, (ETYPE)(target_long)s1)); \
> } \
> env->vstart = 0; \
> + /* clear tail element */ \
> + if (vta) { \
> + for (; i < vlmax; i++) { \
> + vext_set_elem_mask(vd, i, 1); \
> + } \
> + } \
> }
>
> GEN_VEXT_CMP_VX(vmseq_vx_b, uint8_t, H1, DO_MSEQ)