When exploiting binary vulnerabilities on hardened systems, ROP-Chains are common alternatives to shellcodes and still considered to be the best way to execute arbitrary code under an ASLR + DEP environment. However, building ROP-Chains is onerous and time-consuming, and even though several attempts have already been made to automate the process, none of them produced a practical solution. To solve the problem, we developed a new approach for semantic code analysis that is specifically designed to scale to gadgets. We also created a gadget-chaining engine which, given a semantic query and a list of available gadgets, is able to build ROP-Chains matching the queries. We implemented this approach in a free tool named ROPGenerator.