arch: Make the advance() method virtual and in PCStateBase.

It's occasionally necessary to advance the PC to the next instruction
without having an instruction to do it with. This makes it available
without having to cast to a PCState subclass.

Change-Id: I3b7d94afdfb27b34279e58158782e87ab5066a37
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/52065
Tested-by: kokoro <noreply+kokoro@google.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>

src/arch/arm/pcstate.hh

@@ -288,7 +288,7 @@ class PCState : public GenericISA::UPCState<4>
     }
 
     void
-    advance()
+    advance() override
     {
         Base::advance();
         flags = nextFlags;

src/arch/generic/pcstate.hh

@@ -126,6 +126,8 @@ class PCStateBase : public Serializable
         _upc = 0;
     }
 
+    virtual void advance() = 0;
+
     void
     serialize(CheckpointOut &cp) const override
     {
@@ -370,7 +372,7 @@ class SimplePCState : public PCStateCommon
 
     // Advance the PC.
     void
-    advance()
+    advance() override
     {
         this->_pc = this->_npc;
         this->_npc += InstWidth;
@@ -493,7 +495,7 @@ class DelaySlotPCState : public SimplePCState<InstWidth>
 
     // Advance the PC.
     void
-    advance()
+    advance() override
     {
         this->_pc = this->_npc;
         this->_npc = this->_nnpc;

src/arch/x86/pcstate.hh

@@ -95,7 +95,7 @@ class PCState : public GenericISA::UPCState<8>
     }
 
     void
-    advance()
+    advance() override
     {
         Base::advance();
         _size = 0;

src/cpu/nop_static_inst.cc

@@ -50,9 +50,9 @@ class NopStaticInst : public StaticInst
     }
 
     void
-    advancePC(PCStateBase &pcState) const override
+    advancePC(PCStateBase &pc) const override
     {
-        pcState.as<TheISA::PCState>().advance();
+        pc.advance();
     }
 
     std::string

src/sim/syscall_emul.hh

@@ -1662,7 +1662,7 @@ cloneFunc(SyscallDesc *desc, ThreadContext *tc, RegVal flags, RegVal newStack,
     desc->returnInto(ctc, 0);
 
     std::unique_ptr<PCStateBase> cpc(tc->pcState().clone());
-    cpc->as<TheISA::PCState>().advance();
+    cpc->advance();
     ctc->pcState(*cpc);
     ctc->activate();
 
@@ -2226,7 +2226,7 @@ execveFunc(SyscallDesc *desc, ThreadContext *tc,
     new_p->initState();
     tc->activate();
     std::unique_ptr<PCStateBase> pc_state(tc->pcState().clone());
-    pc_state->as<TheISA::PCState>().advance();
+    pc_state->advance();
     tc->pcState(*pc_state);
 
     return SyscallReturn();