Intel® Quartus® Prime Standard Edition User Guide: Third-party Synthesis

ID 683796
Date 9/24/2018
Document Table of Contents

1.11.2. Creating a Design with Separate Netlist Files for Incremental Compilation

The first stage of a hierarchical or incremental design flow is to ensure that different parts of your design do not affect each other. Ensure that you have separate netlists for each partition in your design so you can take advantage of incremental compilation in the Intel® Quartus® Prime software. If the entire design is in one netlist file, changes in one partition might affect other partitions because of possible node name changes when you resynthesize the design.

To ensure proper functionality of the synthesis flow, create separate netlist files only for modules and entities. In addition, each module or entity requires its own design file. If two different modules are in the same design file, but are defined as being part of different partitions, incremental compilation cannot be maintained since both partitions must be recompiled when one module is changed.

Intel recommends that you register all inputs and outputs of each partition. This makes logic synchronous, and avoids any delay penalty on signals that cross partition boundaries.

If you use boundary tri-states in a lower-level block, the Synplify software pushes, or bubbles, the tri‑states through the hierarchy to the top-level to use the tri‑state drivers on output pins of Intel devices. Because bubbling tri-states requires optimizing through hierarchies, lower-level tri-states are not supported with a block‑based compilation methodology. Use tri-state drivers only at the external output pins of the device and in the top-level block in the hierarchy.

You can generate multiple .vqm netlist files with the MultiPoint synthesis flow in the Synplify Pro and Premier software, or by manually creating separate Synplify projects and creating a black box for each block that you want to designate as a separate design partition.

In the MultiPoint synthesis flow in the Synplify Pro and Premier software, you create multiple .vqm netlist files from one easy-to-manage, top-level synthesis project. By using the manual black box method, you have multiple synthesis projects, which might be required for certain team‑based or bottom-up designs where a single top-level project is not desired.

After you have created multiple .vqm files using one of these two methods, you must create the appropriate Intel® Quartus® Prime projects to place‑and-route the design.