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target/riscv: fix handling of nop for vstart >= vl in some vector instruction

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Recently, when I was writing a RISCV test, I found that when VL is set to 0, the
instruction should be nop, but when I tested it, I found that QEMU will treat
all elements as tail elements, and in the case of VTA=1, write all elements
to 1.

After troubleshooting, it was found that the vext_vx_rm_1 function was called in
the vext_vx_rm_2, and then the vext_set_elems_1s function was called to process
the tail element, but only VSTART >= vl was checked in the vext_vx_rm_1
function, which caused the tail element to still be processed even if it was
returned in advance.

So I've made the following change:

Put VSTART_CHECK_EARLY_EXIT(env) at the beginning of the vext_vx_rm_2 function,
so that the VSTART register is checked correctly.

Fixes: df4252b2ec ("target/riscv/vector_helpers: do early exit when
vstart >= vl")
Signed-off-by: Chao Liu <lc00631@tecorigin.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Message-ID: <b2649f14915150be4c602d63cd3ea4adf47e9d75.1741573286.git.lc00631@tecorigin.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
This commit is contained in:
Chao Liu 2025-03-10 10:35:25 +08:00 • committed by Alistair Francis
parent e83845316a
commit 4e9e2478df
1 changed files with 14 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

18
target/riscv/vector_helper.c
View file

@ -2175,8 +2175,6 @@ vext_vv_rm_1(void *vd, void *v0, void *vs1, void *vs2,
uint32_t vl, uint32_t vm, int vxrm,
opivv2_rm_fn *fn, uint32_t vma, uint32_t esz)
{
VSTART_CHECK_EARLY_EXIT(env, vl);
for (uint32_t i = env->vstart; i < vl; i++) {
if (!vm && !vext_elem_mask(v0, i)) {
/* set masked-off elements to 1s */
@ -2200,6 +2198,8 @@ vext_vv_rm_2(void *vd, void *v0, void *vs1, void *vs2,
uint32_t vta = vext_vta(desc);
uint32_t vma = vext_vma(desc);
VSTART_CHECK_EARLY_EXIT(env, vl);
switch (env->vxrm) {
case 0: /* rnu */
vext_vv_rm_1(vd, v0, vs1, vs2,
@ -2302,8 +2302,6 @@ vext_vx_rm_1(void *vd, void *v0, target_long s1, void *vs2,
uint32_t vl, uint32_t vm, int vxrm,
opivx2_rm_fn *fn, uint32_t vma, uint32_t esz)
{
VSTART_CHECK_EARLY_EXIT(env, vl);
for (uint32_t i = env->vstart; i < vl; i++) {
if (!vm && !vext_elem_mask(v0, i)) {
/* set masked-off elements to 1s */
@ -2327,6 +2325,8 @@ vext_vx_rm_2(void *vd, void *v0, target_long s1, void *vs2,
uint32_t vta = vext_vta(desc);
uint32_t vma = vext_vma(desc);
VSTART_CHECK_EARLY_EXIT(env, vl);
switch (env->vxrm) {
case 0: /* rnu */
vext_vx_rm_1(vd, v0, s1, vs2,
@ -4662,6 +4662,8 @@ void HELPER(NAME)(void *vd, void *v0, void *vs1, \
uint32_t i; \
TD s1 = *((TD *)vs1 + HD(0)); \
\
VSTART_CHECK_EARLY_EXIT(env, vl); \
\
for (i = env->vstart; i < vl; i++) { \
TS2 s2 = *((TS2 *)vs2 + HS2(i)); \
if (!vm && !vext_elem_mask(v0, i)) { \
@ -4750,6 +4752,8 @@ void HELPER(NAME)(void *vd, void *v0, void *vs1, \
uint32_t i; \
TD s1 = *((TD *)vs1 + HD(0)); \
\
VSTART_CHECK_EARLY_EXIT(env, vl); \
\
for (i = env->vstart; i < vl; i++) { \
TS2 s2 = *((TS2 *)vs2 + HS2(i)); \
if (!vm && !vext_elem_mask(v0, i)) { \
@ -4914,6 +4918,8 @@ static void vmsetm(void *vd, void *v0, void *vs2, CPURISCVState *env,
int i;
bool first_mask_bit = false;
VSTART_CHECK_EARLY_EXIT(env, vl);
for (i = env->vstart; i < vl; i++) {
if (!vm && !vext_elem_mask(v0, i)) {
/* set masked-off elements to 1s */
@ -4986,6 +4992,8 @@ void HELPER(NAME)(void *vd, void *v0, void *vs2, CPURISCVState *env, \
uint32_t sum = 0; \
int i; \
\
VSTART_CHECK_EARLY_EXIT(env, vl); \
\
for (i = env->vstart; i < vl; i++) { \
if (!vm && !vext_elem_mask(v0, i)) { \
/* set masked-off elements to 1s */ \
@ -5344,6 +5352,8 @@ void HELPER(NAME)(void *vd, void *v0, void *vs1, void *vs2, \
uint32_t vta = vext_vta(desc); \
uint32_t num = 0, i; \
\
VSTART_CHECK_EARLY_EXIT(env, vl); \
\
for (i = env->vstart; i < vl; i++) { \
if (!vext_elem_mask(vs1, i)) { \
continue; \