[PATCH] target/hppa: Speed up hppa_is_pa20()

[Helge Deller]

Although the hppa_is_pa20() helper is costly due to string comparisms in
object_dynamic_cast(), it is called quite often during memory lookups
and at each start of a block of instruction translations.
Speed hppa_is_pa20() up by calling object_dynamic_cast() only once at
CPU creation and store the result in the is_pa20 of struct CPUArchState.

Signed-off-by: Helge Deller <deller@gmx.de>

diff --git a/hw/hppa/machine.c b/hw/hppa/machine.c
index a31dc32a9f..08ac1ec068 100644
--- a/hw/hppa/machine.c
+++ b/hw/hppa/machine.c
@@ -281,6 +281,7 @@ static TranslateFn 
*machine_HP_common_init_cpus(MachineState *machine)
     /* Create CPUs.  */
     for (unsigned int i = 0; i < smp_cpus; i++) {
         cpu[i] = HPPA_CPU(cpu_create(machine->cpu_type));
+        cpu[i]->env.is_pa20 = object_dynamic_cast(OBJECT(cpu[i]), 
TYPE_HPPA64_CPU);
     }
 
     /*
diff --git a/target/hppa/cpu.h b/target/hppa/cpu.h
index e45ba50a59..c37a701f44 100644
--- a/target/hppa/cpu.h
+++ b/target/hppa/cpu.h
@@ -208,6 +208,7 @@ typedef struct CPUArchState {
     uint64_t fr[32];
     uint64_t sr[8];          /* stored shifted into place for gva */
 
+    bool is_pa20;
     uint32_t psw;            /* All psw bits except the following:  */
     uint32_t psw_xb;         /* X and B, in their normal positions */
     target_ulong psw_n;      /* boolean */
@@ -294,7 +295,7 @@ struct HPPACPUClass {
 
 static inline bool hppa_is_pa20(CPUHPPAState *env)
 {
-    return object_dynamic_cast(OBJECT(env_cpu(env)), TYPE_HPPA64_CPU) != NULL;
+    return env->is_pa20;
 }
 
 static inline int HPPA_BTLB_ENTRIES(CPUHPPAState *env)