Intel® Quartus® Prime Pro Edition User Guide: Design Optimization

ID 683641
Date 1/07/2022

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Document Table of Contents Optimize Source Code

In many cases, optimizing the design’s source code can have a very significant effect on your design performance. In fact, optimizing your source code is typically the most effective technique for improving the quality of your results and is often a better choice than using Logic Lock or location assignments.

You can use the Design Assistant to help identify areas in the design for timing optimization. Be aware of the number of logic levels needed to implement your logic while you are coding. Too many levels of logic between registers might result in critical paths failing timing. Try restructuring the design to use pipelining or more efficient coding techniques. Also, try limiting high fan-out signals in the source code. When possible, duplicate and pipeline control signals. Make sure the duplicate registers are protected by a preserve attribute, to avoid merging during synthesis.

If the critical path in your design involves memory or DSP functions, check whether you have code blocks in your design that describe memory or functions that are not being inferred and placed in dedicated logic. You might be able to modify your source code to cause these functions to be placed into high-performance dedicated memory or resources in the target device. When using RAM/DSP blocks, enable the optional input and output registers.

Ensure that your state machines are recognized as state machine logic and optimized appropriately in your synthesis tool. State machines that are recognized are generally optimized better than if the synthesis tool treats them as generic logic. In the Intel® Quartus® Prime software, you can check the State Machine report under Analysis & Synthesis in the Compilation Report. This report provides details, including state encoding for each state machine that was recognized during compilation. If your state machine is not recognized, you might have to change your source code to enable it to be recognized.