Instruction.extended_previous_instructions()

Returns the set of all instructions preceding the current node in the control flow graph.

extended_previous_instructions() → APISet[Instruction]

The function returns all instructions that are previous to the instruction in the CFG (control flow graph).

The difference between the extended_previous_instructions() function and previous_instructions() is that the former works in an inter-procedural manner.

The function is inter-procedural, and follows function calls; for the intra-procedural variant of this function, use previous_instructions().

For example, in the function:

function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }
        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");
        return c;
    }

for the instruction:

require(c / a == b, "SafeMath: multiplication overflow")

having that the mul() is being called inside the function:

function _transfer(address from, address to, uint256 amount) private {
        uint256 taxAmount=0;
        if (!_isExcludedFromFee[from] && !_isExcludedFromFee[to]) {
            require(tradeOpen, "Trading not open");
            taxAmount = amount.mul((_buyCount>_reduceBuyTaxAt)?_finalBuyTax:_initialBuyTax).div(100);

            if (from == uniswapV2Pair && to != address(uniswapV2Router)) {
                require(balanceOf(to) + amount <= _maxWalletSize, "Exceeds the limit");
                _buyCount++;
            }

            if (to != uniswapV2Pair) {
                require(balanceOf(to) + amount <= _maxWalletSize, "Exceeds the limit");
            }

            if(to == uniswapV2Pair && from!= address(this) ){
                taxAmount = amount.mul((_buyCount>_reduceSellTaxAt)?_finalSellTax:_initialSellTax).div(100);
            }

        //....
    }

the function will return previous instructions from mul():

       if (a == 0) {
            return 0;
        }
        uint256 c = a * b;

as well as from _transfer():

        uint256 taxAmount=0;
        if (!_isExcludedFromFee[from] && !_isExcludedFromFee[to]) {
            require(tradeOpen, "Trading not open");
            taxAmount = amount.mul((_buyCount>_reduceBuyTaxAt)?_finalBuyTax:_initialBuyTax).div(100);

            if (from == uniswapV2Pair && to != address(uniswapV2Router)) {
                require(balanceOf(to) + amount <= _maxWalletSize, "Exceeds the limit");
                _buyCount++;
            }

            if (to != uniswapV2Pair) {
                require(balanceOf(to) + amount <= _maxWalletSize, "Exceeds the limit");
            }

            if(to == uniswapV2Pair && from!= address(this) ){
                taxAmount = amount.mul((_buyCount>_reduceSellTaxAt)?_finalSellTax:_initialSellTax).div(100);
            }

Furthermore, it will also return instructions from transferFrom() function as the _transfer() is being called from there as well:

function transferFrom(address sender, address recipient, uint256 amount) public override returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }

Query Example

from glider import *
def query():
  instructions = Functions().with_all_properties([MethodProp.INTERNAL]).instructions().with_callee_function_name('require').exec(1,2)

  return instructions + list(instructions[0].extended_previous_instructions())

Example Output

The function returns APISet, instead of APIList, in case the result of the function is used as the return value of the query it must be casted to list()