Methods and apparatus for implementing a programmable integrated circuit using circuit design tools are provided. The circuit design tools may receive a high-level synthesis source code, parse the high-level synthesis source code to generate a compiler intermediate representation, process the compiler intermediate representation to generate a register transfer level (RTL) description, and then synthesize and compile the RTL description to generate an output netlist. Timing analysis may be performed on the output netlist to identify a critical path. Components in the critical path may be mapped back to specific portions in the RTL descriptions, to specification portions of the compiler intermediate representation, and to specific lines in the high-level synthesis source code. The designer can then optimize the high-level synthesis source code to shorten the critical path. This process may be iterated as many times as desired.