Re: [PATCH v2] target/riscv: Fix the element agnostic function problem

[LIU Zhiwei]

On 2024/3/21 11:58, Huang Tao wrote:

In RVV and vcrypto instructions, the masked and tail elements are set to 1s
using vext_set_elems_1s function if the vma/vta bit is set. It is the element
agnostic policy.

However, this function can't deal the big endian situation. This patch fixes
the problem by adding handling of such case.

Signed-off-by: Huang Tao <eric.hu...@linux.alibaba.com>
Suggested-by: Richard Henderson <richard.hender...@linaro.org>
---
Changes in v2:
- Keep the api of vext_set_elems_1s
- Reduce the number of patches.
---
  target/riscv/vector_internals.c | 22 ++++++++++++++++++++++
  1 file changed, 22 insertions(+)

diff --git a/target/riscv/vector_internals.c b/target/riscv/vector_internals.c
index 12f5964fbb..3e45b9b4a7 100644
--- a/target/riscv/vector_internals.c
+++ b/target/riscv/vector_internals.c
@@ -30,6 +30,28 @@ void vext_set_elems_1s(void *base, uint32_t is_agnostic, 
uint32_t cnt,
      if (tot - cnt == 0) {
          return ;
      }
+
+#if HOST_BIG_ENDIAN
+    /*
+     * Deal the situation when the elements are insdie
+     * only one uint64 block including setting the
+     * masked-off element.
+     */
+    if ((tot - 1) ^ cnt < 8) {
+        memset(base + H1(tot - 1), -1, tot - cnt);
+        return;
+    }
+    /*
+     * Otherwise, at least cross two uint64_t blocks.
+     * Set first unaligned block.
+     */
+    if (cnt % 8 != 0) {
+        uint32_t j = ROUND_UP(cnt, 8);
+        memset(base + H1(j - 1), -1, j - cnt);
+        cnt = j;
+    }
+    /* Set other 64bit aligend blocks */
+#endif

Reviewed-by: LIU Zhiwei <zhiwei_...@linux.alibaba.com>

Zhiwei

      memset(base + cnt, -1, tot - cnt);
  }