cpu: Make getIsaPtr const.

This accessor shouldn't modify the ThreadContext.

Change-Id: I6f2629f950b0379573e51e337626ef6b1429a14d
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/50250
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/fastmodel/iris/thread_context.hh

@@ -220,7 +220,7 @@ class ThreadContext : public gem5::ThreadContext
     System *getSystemPtr() override { return _cpu->system; }
 
     BaseISA *
-    getIsaPtr() override
+    getIsaPtr() const override
     {
         return _isa;
     }

src/cpu/checker/thread_context.hh

@@ -153,7 +153,7 @@ class CheckerThreadContext : public ThreadContext
         return checkerCPU;
     }
 
-    BaseISA *getIsaPtr() override { return actualTC->getIsaPtr(); }
+    BaseISA *getIsaPtr() const override { return actualTC->getIsaPtr(); }
 
     InstDecoder *
     getDecoderPtr() override

src/cpu/o3/thread_context.hh

@@ -107,7 +107,7 @@ class ThreadContext : public gem5::ThreadContext
     CheckerCPU *getCheckerCpuPtr() override { return NULL; }
 
     BaseISA *
-    getIsaPtr() override
+    getIsaPtr() const override
     {
         return cpu->isa[thread->threadId()];
     }

src/cpu/simple_thread.hh

@@ -208,7 +208,7 @@ class SimpleThread : public ThreadState, public ThreadContext
 
     CheckerCPU *getCheckerCpuPtr() override { return NULL; }
 
-    BaseISA *getIsaPtr() override { return isa; }
+    BaseISA *getIsaPtr() const override { return isa; }
 
     InstDecoder *getDecoderPtr() override { return decoder; }
 

src/cpu/thread_context.hh

@@ -142,7 +142,7 @@ class ThreadContext : public PCEventScope
 
     virtual CheckerCPU *getCheckerCpuPtr() = 0;
 
-    virtual BaseISA *getIsaPtr() = 0;
+    virtual BaseISA *getIsaPtr() const = 0;
 
     virtual InstDecoder *getDecoderPtr() = 0;