[PATCH v2] target/loongarch: Fix [X]VLDI raising exception incorrectly

[PATCH v2] target/loongarch: Fix [X]VLDI raising exception incorrectly

[WANG Rui]

According to the specification, [X]VLDI should trigger an invalid instruction
exception only when Bit[12] is 1 and Bit[11:8] > 12. This patch fixes an issue
where an exception was incorrectly raised even when Bit[12] was 0.

Test case:

```
    .global main
main:
    vldi    $vr0, 3328
    ret
```

Reported-by: Zhou Qiankang <wszqkzqk@qq.com>
Signed-off-by: WANG Rui <wangrui@loongson.cn>
---
v1 -> v2:
- Keep the INE exception prioritized over the [A]SXD.
---
 target/loongarch/tcg/insn_trans/trans_vec.c.inc | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/target/loongarch/tcg/insn_trans/trans_vec.c.inc b/target/loongarch/tcg/insn_trans/trans_vec.c.inc
index 78730029cb..38bccf2838 100644
--- a/target/loongarch/tcg/insn_trans/trans_vec.c.inc
+++ b/target/loongarch/tcg/insn_trans/trans_vec.c.inc
@@ -3585,7 +3585,9 @@ static bool gen_vldi(DisasContext *ctx, arg_vldi *a, uint32_t oprsz)
     int sel, vece;
     uint64_t value;
 
-    if (!check_valid_vldi_mode(a)) {
+    sel = (a->imm >> 12) & 0x1;
+
+    if (sel && !check_valid_vldi_mode(a)) {
         generate_exception(ctx, EXCCODE_INE);
         return true;
     }
@@ -3594,8 +3596,6 @@ static bool gen_vldi(DisasContext *ctx, arg_vldi *a, uint32_t oprsz)
         return true;
     }
 
-    sel = (a->imm >> 12) & 0x1;
-
     if (sel) {
         value = vldi_get_value(ctx, a->imm);
         vece = MO_64;
-- 
2.50.1

Re: [PATCH v2] target/loongarch: Fix [X]VLDI raising exception incorrectly

[gaosong]

在 2025/8/4 下午9:22, WANG Rui 写道:
> According to the specification, [X]VLDI should trigger an invalid instruction
> exception only when Bit[12] is 1 and Bit[11:8] > 12. This patch fixes an issue
> where an exception was incorrectly raised even when Bit[12] was 0.
>
> Test case:
>
> ```
>      .global main
> main:
>      vldi    $vr0, 3328
>      ret
> ```
>
> Reported-by: Zhou Qiankang <wszqkzqk@qq.com>
> Signed-off-by: WANG Rui <wangrui@loongson.cn>
> ---
> v1 -> v2:
> - Keep the INE exception prioritized over the [A]SXD.
> ---
>   target/loongarch/tcg/insn_trans/trans_vec.c.inc | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
Reviewed-by: Song Gao <gaosong@loongson.cn>

Thanks
Song Gao
> diff --git a/target/loongarch/tcg/insn_trans/trans_vec.c.inc b/target/loongarch/tcg/insn_trans/trans_vec.c.inc
> index 78730029cb..38bccf2838 100644
> --- a/target/loongarch/tcg/insn_trans/trans_vec.c.inc
> +++ b/target/loongarch/tcg/insn_trans/trans_vec.c.inc
> @@ -3585,7 +3585,9 @@ static bool gen_vldi(DisasContext *ctx, arg_vldi *a, uint32_t oprsz)
>       int sel, vece;
>       uint64_t value;
>   
> -    if (!check_valid_vldi_mode(a)) {
> +    sel = (a->imm >> 12) & 0x1;
> +
> +    if (sel && !check_valid_vldi_mode(a)) {
>           generate_exception(ctx, EXCCODE_INE);
>           return true;
>       }
> @@ -3594,8 +3596,6 @@ static bool gen_vldi(DisasContext *ctx, arg_vldi *a, uint32_t oprsz)
>           return true;
>       }
>   
> -    sel = (a->imm >> 12) & 0x1;
> -
>       if (sel) {
>           value = vldi_get_value(ctx, a->imm);
>           vece = MO_64;