编译原理的局部优化中函数bool isManageable(string ioperater)的含义是什么

#include "main.h"

struct DAGNode {
    int number;//节点的唯一标识，与lastNum有关
    string content;//操作
    std::set<DAGNode*> parents;//父节点塞入
    DAGNode* leftChild;
    DAGNode* rightChild;
};
int lastNum = 0;//记录节点数
std::vector<DAGNode*> allNodes;
map<string, int> varNodeTable; // Node table
map<string, int> varsWithInitial; // Vars serving as initial nodes
std::set<string> crossingVars;
string currentFunc2;
std::vector<infixNotation> newInfixTable;
fstream betterInfixFile;
string newOutputBuff;

//Only codes with operand of ADD, SUB, MUL, DIV, NEG, ASSIGN, GETARR are manageable
inline bool isManageable(string ioperater) {
    if (ioperater == "ADD" || ioperater == "SUB" || ioperater == "MUL" ||
        ioperater == "DIV" || ioperater == "NEG" || ioperater == "ASSIGN" ||
        ioperater == "GETARR") {
        return true;
    }
    return false;
}



// Split basic blocks & get crossing variables
//分割基本块
void splitBlocks() {
    map<string, int> varExistenceCount;
    std::set<string> varsInBlock;
    bool isInBlock = false;
    // Check all infix notations, get existence count
    for (int i = 0; i < infixTable.size(); ++i) {
        if (isManageable(infixTable[i].ioperator)) { // Infix code is manageable
            if (!isInBlock) { // This line of code is following an other kind of basic block
                isInBlock = true;
                checkVarExistenceCount(varExistenceCount, varsInBlock);
                // Empty vars in block
                varsInBlock.clear();
            }
        }
        else { // Infix code is not manageable
            if (isInBlock) { // This line of code is following an other kind of basic block
                isInBlock = false;
                checkVarExistenceCount(varExistenceCount, varsInBlock);
                // Empty vars in block
                varsInBlock.clear();
            }
        }
        //insert infixtable node i into varsInBlock
        if (infixTable[i].ioperator != "CONST" && infixTable[i].ioperator != "VAR" &&
            infixTable[i].ioperator != "FUNC" && infixTable[i].ioperator != "PARAM") {
            // Declarations don't take in count
            insertOperands(varsInBlock, infixTable[i]);
        }
    }

    // Manage the rest codes   最后一个块没有判断
    checkVarExistenceCount(varExistenceCount, varsInBlock);

    // Store element with existence count over 1 to crossingVars
    for (map<string, int>::iterator it = varExistenceCount.begin(); it != varExistenceCount.end();
        ++it) {
        if (it->second > 1) { // Var cross basic blocks
            crossingVars.insert(it->first);
        }
    }
}