_registerHash(hash){
    hash = this._normalizeHash(hash);

    if(this.instrumentationData[hash]){
      // abi.encode (used to circumvent viaIR) sometimes puts the hash on the stack twice
      // We should only skip duplicate hashes *within* a transaction (see issue #863)
      if (this.lastHash !== hash || this.lastPcZeroCount !== this.pcZeroCounter) {
        this.lastHash = hash;
        this.lastPcZeroCount = this.pcZeroCounter;
        this.instrumentationData[hash].hits++
      }
      return;
    }
  }
Normalizes has string and marks hit.
@param  {String} hash bytes32 hash