target/riscv/vector_helper.c: use vlenb in HELPER(vsetvl)

Use the new 'vlenb' CPU config to validate fractional LMUL. The original
comparison is done with 'vlen' and 'sew', both in bits. Adjust the shift
to use vlenb.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20240122161107.26737-9-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

diff --git a/target/riscv/vector_helper.c b/target/riscv/vector_helper.c
index 908e69d0731a82096d788eb19c82e493a149f8e5..8ee771716250a427e631f15a45df8cc875b47ce4 100644 (file)
--- a/target/riscv/vector_helper.c
+++ b/target/riscv/vector_helper.c
@@ -45,9 +45,16 @@ target_ulong HELPER(vsetvl)(CPURISCVState *env, target_ulong s1,
                                             xlen - 1 - R_VTYPE_RESERVED_SHIFT);
 
     if (lmul & 4) {
-        /* Fractional LMUL - check LMUL * VLEN >= SEW */
+        /*
+         * Fractional LMUL, check:
+         *
+         * VLEN * LMUL >= SEW
+         * VLEN >> (8 - lmul) >= sew
+         * (vlenb << 3) >> (8 - lmul) >= sew
+         * vlenb >> (8 - 3 - lmul) >= sew
+         */
         if (lmul == 4 ||
-            cpu->cfg.vlen >> (8 - lmul) < sew) {
+            cpu->cfg.vlenb >> (8 - 3 - lmul) < sew) {
             vill = true;
         }
     }