Quartus® Prime Standard Edition User Guide: Design Compilation

ID 683283
Date 10/22/2021
Public
Document Table of Contents

1.6.1. Netlist Type for Design Partitions

Before starting a new compilation, ensure that the appropriate netlist type is set for each partition to preserve the desired level of compilation results. The table below describes the settings for the netlist type, explains the behavior of the Quartus® Prime software for each setting, and provides guidance on when to use each setting.
Table 2.  Partition Netlist Type Settings

Netlist Type

Quartus® Prime Software Behavior for Partition During Compilation

Source File

Always compiles the partition using the associated design source file(s). 2

Use this netlist type to recompile a partition from the source code using new synthesis or Fitter settings.

Post-Synthesis

Preserves post-synthesis results for the partition and reuses the post-synthesis netlist when the following conditions are true:

  • A post-synthesis netlist is available from a previous synthesis.
  • No change that initiates an automatic resynthesis has been made to the partition since the previous synthesis. 3

Compiles the partition from the source files if resynthesis is initiated or if a post-synthesis netlist is not available. 2

Use this netlist type to preserve the synthesis results unless you make design changes, but allow the Fitter to refit the partition using any new Fitter settings.

Post-Fit

Preserves post-fit results for the partition and reuses the post-fit netlist when the following conditions are true:

  • A post-fit netlist is available from a previous fitting.
  • No change that initiates an automatic resynthesis has been made to the partition since the previous fitting. 3

When a post-fit netlist is not available, the software reuses the post-synthesis netlist if it is available, or otherwise compiles from the source files. Compiles the partition from the source files if resynthesis is initiated. 2

The Fitter Preservation Level specifies what level of information is preserved from the post‑fit netlist.

Assignment changes, such as Fitter optimization settings, do not cause a partition set to Post-Fit to recompile.

Empty

Uses an empty placeholder netlist for the partition. The partition's port interface information is required during Analysis and Synthesis to connect the partition correctly to other logic and partitions in the design, and peripheral nodes in the source file including pins and PLLs are preserved to help connect the empty partition to the rest of the design and preserve timing of any lower-level non-empty partitions within empty partitions. If the source file is not available, you can create a wrapper file that defines the design block and specifies the input, output, and bidirectional ports. In Verilog HDL: a module declaration, and in VHDL: an entity and architecture declaration.

You can use this netlist type to skip the compilation of a partition that is incomplete or missing from the top-level design. You can also set an empty partition if you want to compile only some partitions in the design, such as to optimize the placement of a timing-critical block such as an IP core before incorporating other design logic, or if the compilation time is large for one partition and you want to exclude it.

If the project database includes a previously generated post-synthesis or post-fit netlist for an unchanged Empty partition, you can set the netlist type from Empty directly to Post-Synthesis or Post-Fit and the software reuses the previous netlist information without recompiling from the source files.

2 If you use Rapid Recompile, the Quartus® Prime software might not recompile the entire partition from the source code as described in this table; it will reuse compatible results if there have been only small changes to the logic in the partition.
3 You can turn on the Ignore changes in source files and strictly use the specified netlist, if available option on the Advanced tab in the Design Partitions Properties dialog box to specify whether the Compiler should ignore source file changes when deciding whether to recompile the partition.