target/riscv: Use env_archcpu() in [check_]nanbox()

When CPUArchState* is available (here CPURISCVState*), we
can use the fast env_archcpu() macro to get ArchCPU* (here
RISCVCPU*). The QOM cast RISCV_CPU() macro will be slower
when building with --enable-qom-cast-debug.

Inspired-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20231009110239.66778-3-philmd@linaro.org>

target/riscv/internals.h

@@ -87,7 +87,7 @@ enum {
 static inline uint64_t nanbox_s(CPURISCVState *env, float32 f)
 {
     /* the value is sign-extended instead of NaN-boxing for zfinx */
-    if (RISCV_CPU(env_cpu(env))->cfg.ext_zfinx) {
+    if (env_archcpu(env)->cfg.ext_zfinx) {
         return (int32_t)f;
     } else {
         return f | MAKE_64BIT_MASK(32, 32);
@@ -97,7 +97,7 @@ static inline uint64_t nanbox_s(CPURISCVState *env, float32 f)
 static inline float32 check_nanbox_s(CPURISCVState *env, uint64_t f)
 {
     /* Disable NaN-boxing check when enable zfinx */
-    if (RISCV_CPU(env_cpu(env))->cfg.ext_zfinx) {
+    if (env_archcpu(env)->cfg.ext_zfinx) {
         return (uint32_t)f;
     }
 
@@ -113,7 +113,7 @@ static inline float32 check_nanbox_s(CPURISCVState *env, uint64_t f)
 static inline uint64_t nanbox_h(CPURISCVState *env, float16 f)
 {
     /* the value is sign-extended instead of NaN-boxing for zfinx */
-    if (RISCV_CPU(env_cpu(env))->cfg.ext_zfinx) {
+    if (env_archcpu(env)->cfg.ext_zfinx) {
         return (int16_t)f;
     } else {
         return f | MAKE_64BIT_MASK(16, 48);
@@ -123,7 +123,7 @@ static inline uint64_t nanbox_h(CPURISCVState *env, float16 f)
 static inline float16 check_nanbox_h(CPURISCVState *env, uint64_t f)
 {
     /* Disable nanbox check when enable zfinx */
-    if (RISCV_CPU(env_cpu(env))->cfg.ext_zfinx) {
+    if (env_archcpu(env)->cfg.ext_zfinx) {
         return (uint16_t)f;
     }