arch: Make the ISA::clear() method virtual.

This method is not at all on the critical path, and the adding virtual
method overhead to it will have essentially no effect on over all
performance.

Change-Id: I583bbe30f5ed923a0c771f36c3f07e5979c28476
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/51236
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/arch/arm/isa.hh

@@ -164,7 +164,7 @@ namespace ArmISA
         const RegId &mapIntRegId(RegIndex idx) const { return intRegMap[idx]; }
 
       public:
-        void clear();
+        void clear() override;
 
       protected:
         void clear32(const ArmISAParams &p, const SCTLR &sctlr_rst);

src/arch/generic/isa.hh

@@ -68,6 +68,8 @@ class BaseISA : public SimObject
 
   public:
     virtual PCStateBase *newPCState(Addr new_inst_addr=0) const = 0;
+    virtual void clear() {}
+
     virtual void takeOverFrom(ThreadContext *new_tc, ThreadContext *old_tc) {}
     virtual void setThreadContext(ThreadContext *_tc) { tc = _tc; }
 

src/arch/mips/isa.hh

@@ -77,7 +77,7 @@ namespace MipsISA
         std::vector<BankType> bankType;
 
       public:
-        void clear();
+        void clear() override;
 
         PCStateBase *
         newPCState(Addr new_inst_addr=0) const override

src/arch/power/isa.hh

@@ -57,15 +57,12 @@ class ISA : public BaseISA
     RegVal miscRegs[NUM_MISCREGS];
 
   public:
-    void clear() {}
-
     PCStateBase *
     newPCState(Addr new_inst_addr=0) const override
     {
         return new PCState(new_inst_addr);
     }
 
-  public:
     RegVal
     readMiscRegNoEffect(int misc_reg) const
     {

src/arch/riscv/isa.hh

@@ -75,7 +75,7 @@ class ISA : public BaseISA
   public:
     using Params = RiscvISAParams;
 
-    void clear();
+    void clear() override;
 
     PCStateBase *
     newPCState(Addr new_inst_addr=0) const override

src/arch/sparc/isa.hh

@@ -170,7 +170,7 @@ class ISA : public BaseISA
   public:
     const RegIndex &mapIntRegId(RegIndex idx) const { return intRegMap[idx]; }
 
-    void clear();
+    void clear() override;
 
     PCStateBase *
     newPCState(Addr new_inst_addr=0) const override

src/arch/x86/isa.hh

@@ -60,7 +60,7 @@ class ISA : public BaseISA
     std::string vendorString;
 
   public:
-    void clear();
+    void clear() override;
 
     PCStateBase *
     newPCState(Addr new_inst_addr=0) const override