cpu: Delete the unnecessary BaseO3CPU class.

This class has no content, and is not used for anything except as an
extra layer between FullO3CPU and BaseCPU.

Change-Id: Idb6258a655b0fb614e94b0fc0e281696d5081ab0
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/42116
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Nathanael Premillieu <nathanael.premillieu@huawei.com>
Maintainer: Gabe Black <gabe.black@gmail.com>

src/cpu/o3/cpu.cc

@@ -64,14 +64,9 @@
 
 struct BaseCPUParams;
 
-BaseO3CPU::BaseO3CPU(const BaseCPUParams &params)
-    : BaseCPU(params)
-{
-}
-
 template <class Impl>
 FullO3CPU<Impl>::FullO3CPU(const DerivO3CPUParams &params)
-    : BaseO3CPU(params),
+    : BaseCPU(params),
       mmu(params.mmu),
       tickEvent([this]{ tick(); }, "FullO3CPU tick",
                 false, Event::CPU_Tick_Pri),

src/cpu/o3/cpu.hh

@@ -81,22 +81,13 @@ class O3ThreadContext;
 class Checkpoint;
 class Process;
 
-struct BaseCPUParams;
-
-class BaseO3CPU : public BaseCPU
-{
-    //Stuff that's pretty ISA independent will go here.
-  public:
-    BaseO3CPU(const BaseCPUParams &params);
-};
-
 /**
  * FullO3CPU class, has each of the stages (fetch through commit)
  * within it, as well as all of the time buffers between stages.  The
  * tick() function for the CPU is defined here.
  */
 template <class Impl>
-class FullO3CPU : public BaseO3CPU
+class FullO3CPU : public BaseCPU
 {
   public:
     // Typedefs from the Impl here.