Intel® Quartus® Prime Standard Edition User Guide: Design Compilation

ID 683283
Date 9/24/2018
Document Table of Contents Resynthesis Due to Source Code Changes

The Intel® Quartus® Prime software uses an internal checksum algorithm to determine whether the contents of a source file have changed. Source files are the design description files used to create the design, and include Memory Initialization Files (.mif) as well as .qxp from exported partitions. When design files in a partition have dependencies on other files, changing one file may initiate an automatic recompilation of another file. The Partition Dependent Files table in the Analysis and Synthesis report lists the design files that contribute to each design partition. You can use this table to determine which partitions are recompiled when a specific file is changed.

For example, if a design has file A.v that contains entity A, B.v that contains entity B, and C.v that contains entity C, then the Partition Dependent Files table for the partition containing entity A lists file A.v, the table for the partition containing entity B lists file B.v, and the table for the partition containing entity C lists file C.v. Any dependencies are transitive, so if file A.v depends on B.v, and B.v depends on C.v, the entities in file A.v depend on files B.v and C.v. In this case, files B.v and C.v are listed in the report table as dependent files for the partition containing entity A.

Note: If you use Rapid Recompile, the Intel® Quartus® Prime software might not recompile the entire partition from the source code as described in this section; it will reuse compatible results if there have been only small changes to the logic in the partition.

If you define module parameters in a higher‑level module, the Intel® Quartus® Prime software checks the parameter values when determining which partitions require resynthesis. If you change a parameter in a higher‑level module that affects a lower‑level module, the lower‑level module is resynthesized. Parameter dependencies are tracked separately from source file dependencies; therefore, parameter definitions are not listed in the Partition Dependent Files list.

If a design contains common files, such as an includes.v file that is referenced in each entity by the command include includes.v, all partitions are dependent on this file. A change to includes.v causes the entire design to be recompiled. The VHDL statement use work.all also typically results in unnecessary recompilations, because it makes all entities in the work library visible in the current entity, which results in the current entity being dependent on all other entities in the design.

To avoid this type of problem, ensure that files common to all entities, such as a common include file, contain only the set of information that is truly common to all entities. Remove use work.all statements in your VHDL file or replace them by including only the specific design units needed for each entity.