Instruction.forward_df()

Returns a list of all instructions following the current point in the current data flow graph.

forward_df() → List[Instruction]

The forward_df() function is an intra-procedural analysis function. This means that the function does not operate recursively and instead returns instructions within the current function instruction set.

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 uint256 c = a * b; the forward data flow will return instructions:

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

The easy way to put this is that it will follow the nodes where the variable c is being used directly or indirectly.

Query Example

from glider import *
def query():
  #fetch an instruction
  instructions = Instructions().exec(1,16)
  # return the list of instructions following the current instruction
  
  return instructions + instructions[0].forward_df()

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
uint256 c = a * b
}
...
"sol_instruction":solidity
require(c / a == b, "SafeMath: multiplication overflow")
}
...
"sol_instruction":solidity
return c
}