target/riscv: Fix a uninitialized variable warning

riscv_cpu_validate_v() left its variable, min_vlen, uninitialized if
no vector extension is available, causing a compiler warning.

Re-define riscv_cpu_validate_v() as no-op when no vector extension is
available to prevent the scenario that will read the unintialized
variable by construction. It also simplifies its caller as a bonus.

Signed-off-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Message-ID: <20251021-vlen-v2-1-1fb581d4c6bf@rsg.ci.i.u-tokyo.ac.jp>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

diff --git a/target/riscv/tcg/tcg-cpu.c b/target/riscv/tcg/tcg-cpu.c
index 1150bd14697cc63ca4f4f3e3459421b1ed5387d1..d3968251fad5aa085040d733875c92d16e90880c 100644 (file)
--- a/target/riscv/tcg/tcg-cpu.c
+++ b/target/riscv/tcg/tcg-cpu.c
@@ -426,6 +426,8 @@ static void riscv_cpu_validate_v(CPURISCVState *env, RISCVCPUConfig *cfg,
         min_vlen = 64;
     } else if (cfg->ext_zve32x) {
         min_vlen = 32;
+    } else {
+        return;
     }
 
     if (vlen > RV_VLEN_MAX || vlen < min_vlen) {
@@ -676,12 +678,10 @@ void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, Error **errp)
         return;
     }
 
-    if (cpu->cfg.ext_zve32x) {
-        riscv_cpu_validate_v(env, &cpu->cfg, &local_err);
-        if (local_err != NULL) {
-            error_propagate(errp, local_err);
-            return;
-        }
+    riscv_cpu_validate_v(env, &cpu->cfg, &local_err);
+    if (local_err != NULL) {
+        error_propagate(errp, local_err);
+        return;
     }
 
     /* The Zve64d extension depends on the Zve64f extension */