Fix -Werror=non-virtual-dtor -Werror=suggest-override errors (#1016)

Fixed the following warnings:
- "has virtual functions and accessible non-virtual destructor"
- runOnModule "can be marked override"

Author: wenju-he

lib/SPIRV/OCLToSPIRV.cpp

@@ -73,6 +73,7 @@ static size_t getOCLCpp11AtomicMaxNumOps(StringRef Name) {
 class OCLToSPIRVBase : public InstVisitor<OCLToSPIRVBase> {
 public:
   OCLToSPIRVBase() : M(nullptr), Ctx(nullptr), CLVer(0) {}
+  virtual ~OCLToSPIRVBase() {}
   bool runOCLToSPIRV(Module &M);
 
   virtual void visitCallInst(CallInst &CI);

lib/SPIRV/SPIRVLowerBool.cpp

@@ -54,6 +54,7 @@ namespace SPIRV {
 class SPIRVLowerBoolBase : public InstVisitor<SPIRVLowerBoolBase> {
 public:
   SPIRVLowerBoolBase() : Context(nullptr) {}
+  virtual ~SPIRVLowerBoolBase() {}
   void replace(Instruction *I, Instruction *NewI) {
     NewI->takeName(I);
     I->replaceAllUsesWith(NewI);

lib/SPIRV/SPIRVLowerMemmove.cpp

@@ -55,6 +55,7 @@ namespace SPIRV {
 class SPIRVLowerMemmoveBase : public InstVisitor<SPIRVLowerMemmoveBase> {
 public:
   SPIRVLowerMemmoveBase() : Context(nullptr) {}
+  virtual ~SPIRVLowerMemmoveBase() {}
   virtual void visitMemMoveInst(MemMoveInst &I) {
     IRBuilder<> Builder(I.getParent());
     Builder.SetInsertPoint(&I);
@@ -137,7 +138,7 @@ class SPIRVLowerMemmoveLegacy : public ModulePass,
   SPIRVLowerMemmoveLegacy() : ModulePass(ID) {
     initializeSPIRVLowerMemmoveLegacyPass(*PassRegistry::getPassRegistry());
   }
-  bool runOnModule(Module &M) { return runLowerMemmove(M); }
+  bool runOnModule(Module &M) override { return runLowerMemmove(M); }
 
   static char ID;
 };

lib/SPIRV/SPIRVLowerSPIRBlocks.cpp

@@ -91,6 +91,7 @@ namespace SPIRV {
 class SPIRVLowerSPIRBlocksBase {
 public:
   SPIRVLowerSPIRBlocksBase() : M(nullptr) {}
+  virtual ~SPIRVLowerSPIRBlocksBase() {}
 
   bool runLowerSPIRBlocks(Module &Module) {
     M = &Module;

lib/SPIRV/SPIRVLowerSaddWithOverflow.cpp

@@ -63,6 +63,7 @@ class SPIRVLowerSaddWithOverflowBase
     : public InstVisitor<SPIRVLowerSaddWithOverflowBase> {
 public:
   SPIRVLowerSaddWithOverflowBase() : Context(nullptr) {}
+  virtual ~SPIRVLowerSaddWithOverflowBase() {}
   virtual void visitIntrinsicInst(CallInst &I) {
     IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I);
     if (!II || II->getIntrinsicID() != Intrinsic::sadd_with_overflow)

lib/SPIRV/SPIRVToOCL.h

@@ -50,6 +50,7 @@ namespace SPIRV {
 class SPIRVToOCLBase : public InstVisitor<SPIRVToOCLBase> {
 public:
   SPIRVToOCLBase() : M(nullptr), Ctx(nullptr) {}
+  virtual ~SPIRVToOCLBase() {}
 
   virtual bool runSPIRVToOCL(Module &M) = 0;
 
@@ -181,7 +182,7 @@ class SPIRVToOCLLegacy : public ModulePass {
   SPIRVToOCLLegacy(char &ID) : ModulePass(ID) {}
 
 public:
-  virtual bool runOnModule(Module &M) = 0;
+  bool runOnModule(Module &M) override = 0;
 };
 
 } // namespace SPIRV