[PATCH v2] 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>

v2:
- moved init to hppa_cpu_initfn() and is_pa20 to end of CPUArchState struct
  (feedback by Richard)

diff --git a/target/hppa/cpu.c b/target/hppa/cpu.c
index b908cf65c6..05de952a87 100644
--- a/target/hppa/cpu.c
+++ b/target/hppa/cpu.c
@@ -199,6 +199,7 @@ static void hppa_cpu_initfn(Object *obj)
     CPUHPPAState *env = &cpu->env;
 
     cs->exception_index = -1;
+    env->is_pa20 = object_dynamic_cast(obj, TYPE_HPPA64_CPU);
     cpu_hppa_loaded_fr0(env);
     cpu_hppa_put_psw(env, PSW_W);
 }
diff --git a/target/hppa/cpu.h b/target/hppa/cpu.h
index 32a674a8b8..288ce6d98a 100644
--- a/target/hppa/cpu.h
+++ b/target/hppa/cpu.h
@@ -266,6 +266,8 @@ typedef struct CPUArchState {
 
     /* Fields up to this point are cleared by a CPU reset */
     struct {} end_reset_fields;
+
+    bool is_pa20;
 } CPUHPPAState;
 
 /**
@@ -299,7 +301,7 @@ 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)