gpu-compute: mark functions with override if replacing virtual

The clang compiler is more stringent than the recent versions of
GCC when dealing with overrides. This changeset adds the specifier
to the methods which need it to silence the compiler.

src/arch/hsail/insts/gpu_static_inst.hh

@@ -54,7 +54,7 @@ namespace HsailISA
     {
       public:
         HsailGPUStaticInst(const BrigObject *obj, const std::string &opcode);
-        void generateDisassembly();
+        void generateDisassembly() override;
         int instSize() const override { return sizeof(RawMachInst); }
         bool isValid() const override { return true; }
 

src/gpu-compute/gpu_static_inst.hh

@@ -271,24 +271,24 @@ class KernelLaunchStaticInst : public GPUStaticInst
     }
 
     void
-    execute(GPUDynInstPtr gpuDynInst)
+    execute(GPUDynInstPtr gpuDynInst) override
     {
         fatal("kernel launch instruction should not be executed\n");
     }
 
     void
-    generateDisassembly()
+    generateDisassembly() override
     {
         disassembly = opcode;
     }
 
-    int getNumOperands() { return 0; }
-    bool isCondRegister(int operandIndex) { return false; }
-    bool isScalarRegister(int operandIndex) { return false; }
-    bool isVectorRegister(int operandIndex) { return false; }
-    bool isSrcOperand(int operandIndex) { return false; }
-    bool isDstOperand(int operandIndex) { return false; }
-    int getOperandSize(int operandIndex) { return 0; }
+    int getNumOperands() override { return 0; }
+    bool isCondRegister(int operandIndex) override { return false; }
+    bool isScalarRegister(int operandIndex) override { return false; }
+    bool isVectorRegister(int operandIndex) override { return false; }
+    bool isSrcOperand(int operandIndex) override { return false; }
+    bool isDstOperand(int operandIndex) override { return false; }
+    int getOperandSize(int operandIndex) override { return 0; }
 
     int
     getRegisterIndex(int operandIndex, GPUDynInstPtr gpuDynInst) override
@@ -296,9 +296,9 @@ class KernelLaunchStaticInst : public GPUStaticInst
         return 0;
     }
 
-    int numDstRegOperands() { return 0; }
-    int numSrcRegOperands() { return 0; }
-    bool isValid() const { return true; }
+    int numDstRegOperands() override { return 0; }
+    int numSrcRegOperands() override { return 0; }
+    bool isValid() const override { return true; }
     int instSize() const override { return 0; }
 };