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

[gaosong]

在 2025/8/4 上午11:17, WANG Rui 写道:
Hi folks,
On Mon, Aug 4, 2025 at 10:31 AM WANG Rui <wang...@loongson.cn> wrote:
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 <wszqk...@qq.com>
Signed-off-by: WANG Rui <wang...@loongson.cn>
---
  target/loongarch/tcg/insn_trans/trans_vec.c.inc | 10 +++++-----
  1 file changed, 5 insertions(+), 5 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..ee10a9ebe1 100644
--- a/target/loongarch/tcg/insn_trans/trans_vec.c.inc
+++ b/target/loongarch/tcg/insn_trans/trans_vec.c.inc
@@ -3585,11 +3585,6 @@ static bool gen_vldi(DisasContext *ctx, arg_vldi *a, 
uint32_t oprsz)
      int sel, vece;
      uint64_t value;

-    if (!check_valid_vldi_mode(a)) {
-        generate_exception(ctx, EXCCODE_INE);
-        return true;
-    }
Should the INE exception be prioritized over the [A]SXD exception in this case?
yes, I think we should. this is like ARM.
As Richiard said 'For Arm, at least, decode errors take precedence over 
disabled functional units.'

Thanks.
Song Gao
- Rui

-
      if (!check_vec(ctx, oprsz)) {
          return true;
      }
@@ -3597,6 +3592,11 @@ static bool gen_vldi(DisasContext *ctx, arg_vldi *a, 
uint32_t oprsz)
      sel = (a->imm >> 12) & 0x1;

      if (sel) {
+        if (!check_valid_vldi_mode(a)) {
+            generate_exception(ctx, EXCCODE_INE);
+            return true;
+        }
+
          value = vldi_get_value(ctx, a->imm);
          vece = MO_64;
      } else {
--
2.50.1