Instruction.extended_previous_instructions()

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

extended_previous_instructions() → Set[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())

Output

"root":{4 items
"contract":string"0xd705c24267ed3c55458160104994c55c6492dfcf"
"contract_name":string"SafeMath"
"sol_function":solidity
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;
    }
"sol_instruction":solidity
require(c / a == b, "SafeMath: multiplication overflow")
},

...

"root":{4 items
"contract":string"0xd705c24267ed3c55458160104994c55c6492dfcf"
"contract_name":string"Token"
"sol_function":solidity
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);
            }

            uint256 contractTokenBalance = balanceOf(address(this));
            if (!inSwap && to == uniswapV2Pair && swapEnabled && contractTokenBalance>_taxSwapThreshold) {
                swapTokensForEth(min(amount,min(contractTokenBalance,_maxTaxSwap)));
                uint256 contractETHBalance = address(this).balance;
                if(contractETHBalance > 0) {
                    sendETHToFee(address(this).balance);
                }
            }
        }

        if(taxAmount>0){
          _balances[address(this)]=_balances[address(this)].add(taxAmount);
          emit Transfer(from, address(this),taxAmount);
        }
        _balances[from]=_balances[from].sub(amount);
        _balances[to]=_balances[to].add(amount.sub(taxAmount));
        emit Transfer(from, to, amount.sub(taxAmount));
    }
"sol_instruction":solidity
taxAmount = amount.mul((_buyCount>_reduceSellTaxAt)?_finalSellTax:_initialSellTax).div(100)
}

...

"root":{4 items
"contract":string"0xd705c24267ed3c55458160104994c55c6492dfcf"
"contract_name":string"Token"
"sol_function":solidity
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;
    }
"sol_instruction":solidity
_transfer(sender, recipient, amount)
}