AMDGPU: Silence unused warnings in waitcnt insertion pass in release build

[kzhuravl]

lib/Target/AMDGPU/SIInsertWaitcnts.cpp

144

This got here by accident, I will remove.

[msearles]

LGTM; thx, I've been meaning to address this.

lib/Target/AMDGPU/SIInsertWaitcnts.cpp

 // "s_waitcnt 0" before use.
 class BlockWaitcntBrackets {
 public:
   BlockWaitcntBrackets(const SISubtarget *SubTarget) : ST(SubTarget) {
     for (enum InstCounterType T = VM_CNT; T < NUM_INST_CNTS;
          T = (enum InstCounterType)(T + 1)) {
       memset(VgprScores[T], 0, sizeof(VgprScores[T]));
     }
+
   }
 
   ~BlockWaitcntBrackets() = default;
 
   static int32_t getWaitCountMax(InstCounterType T) {
     switch (T) {
     case VM_CNT:
       return HardwareLimits.VmcntMax;
private:
   // ForceEmitZeroWaitcnts: force all waitcnts insts to be s_waitcnt 0
   // because of amdgpu-waitcnt-forcezero flag
   bool ForceEmitZeroWaitcnts;
   bool ForceEmitWaitcnt[NUM_INST_CNTS];
 
 public:
   static char ID;
 
-  SIInsertWaitcnts() : MachineFunctionPass(ID) {}
+  SIInsertWaitcnts() : MachineFunctionPass(ID) {
+    (void)ForceExpCounter;
+    (void)ForceLgkmCounter;
+    (void)ForceVMCounter;
+  }
 
   bool runOnMachineFunction(MachineFunction &MF) override;
 
   StringRef getPassName() const override {
     return "SI insert wait instructions";
   }
 
   void getAnalysisUsage(AnalysisUsage &AU) const override {