arch: Extract PCStateCommon from PCStateBase.

This class has a lot of common functionality which all PCState classes
use, but in order to make it a true base class which provides the
complete interface for PCState-s throughout gem5, all its methods would
need to become virtual. That doesn't have to be the case today because
we use the literal full ISA specific PC class directly, but we need to
move away from that.

This change leaves PCStateBase empty, since we don't know what will need
to be accessible in base classes through a common/virtual interface.

Also, move methods which do not depend on the InstWidth template
parameter out of SimplePCState and into PCStateCommon. This avoids
having duplicate methods with the same contents which don't depend on
InstWidth.

Change-Id: I31309c4f35e897db1bc8318439fae1567a82b35e
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/52031
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: Earl Ou <shunhsingou@google.com>
Maintainer: Daniel Carvalho <odanrc@yahoo.com.br>
Tested-by: kokoro <noreply+kokoro@google.com>

src/arch/generic/pcstate.hh

@@ -50,11 +50,17 @@
 namespace gem5
 {
 
+class PCStateBase : public Serializable
+{
+  public:
+    virtual ~PCStateBase() = default;
+};
+
 namespace GenericISA
 {
 
 // The guaranteed interface.
-class PCStateBase : public Serializable
+class PCStateCommon : public PCStateBase
 {
   protected:
     Addr _pc = 0;
@@ -63,8 +69,7 @@ class PCStateBase : public Serializable
     MicroPC _upc = 0;
     MicroPC _nupc = 1;
 
-    PCStateBase() {}
-    PCStateBase(Addr val) { set(val); }
+    PCStateCommon() {}
 
   public:
     /**
@@ -100,6 +105,12 @@ class PCStateBase : public Serializable
         return _upc;
     }
 
+    Addr pc() const { return _pc; }
+    void pc(Addr val) { _pc = val; }
+
+    Addr npc() const { return _npc; }
+    void npc(Addr val) { _npc = val; }
+
     // Reset the macroop's upc without advancing the regular pc.
     void
     uReset()
@@ -108,22 +119,20 @@ class PCStateBase : public Serializable
         _nupc = 1;
     }
 
-    /**
-     * Force this PC to reflect a particular value, resetting all its other
-     * fields around it. This is useful for in place (re)initialization.
-     *
-     * @param val The value to set the PC to.
-     */
-    void set(Addr val);
+    void
+    setNPC(Addr val)
+    {
+        npc(val);
+    }
 
     bool
-    operator == (const PCStateBase &opc) const
+    operator == (const PCStateCommon &opc) const
     {
         return _pc == opc._pc && _npc == opc._npc;
     }
 
     bool
-    operator != (const PCStateBase &opc) const
+    operator != (const PCStateCommon &opc) const
     {
         return !(*this == opc);
     }
@@ -156,19 +165,21 @@ class PCStateBase : public Serializable
 
 // The most basic type of PC.
 template <int InstWidth>
-class SimplePCState : public PCStateBase
+class SimplePCState : public PCStateCommon
 {
   protected:
-    typedef PCStateBase Base;
+    typedef PCStateCommon Base;
 
   public:
+    SimplePCState() {}
+    SimplePCState(Addr val) { set(val); }
 
-    Addr pc() const { return _pc; }
-    void pc(Addr val) { _pc = val; }
-
-    Addr npc() const { return _npc; }
-    void npc(Addr val) { _npc = val; }
-
+    /**
+     * Force this PC to reflect a particular value, resetting all its other
+     * fields around it. This is useful for in place (re)initialization.
+     *
+     * @param val The value to set the PC to.
+     */
     void
     set(Addr val)
     {
@@ -176,15 +187,6 @@ class SimplePCState : public PCStateBase
         npc(val + InstWidth);
     };
 
-    void
-    setNPC(Addr val)
-    {
-        npc(val);
-    }
-
-    SimplePCState() {}
-    SimplePCState(Addr val) { set(val); }
-
     bool
     branching() const
     {