Specifications

CHAPTER 4: SYNTHESIS
PERFORMING INCREMENTAL SYNTHESIS
86 ■ INTRODUCTION TO QUARTUS II ALTERA CORPORATION
Performing Incremental Synthesis
Incremental synthesis is part of the top-down incremental compilation flow.
It allows you to specify entities in your design as design partitions on which
you can perform Analysis & Synthesis incrementally, without affecting the
rest of the project. For more information in the incremental compilation
design flow, refer to “Top-Down Incremental Compilation Flow” on page 30
in Chapter 1, “Design Flow.”
You can perform an incremental synthesis only, or you can perform a full
incremental compilation. For more information about performing a full
incremental compilation, refer to “Performing a Full Incremental
Compilation” on page 92 in Chapter 5, “Place & Route.”
Incremental synthesis ensures that only updated sections of a design are
resynthesized when the design is compiled, which reduces synthesis time
and run-time memory usage. You can change and resynthesize a section of
a design without affecting other sections of a design, which means that node
names are maintained for all registered and combinational nodes in
unchanged sections. After you have performed Analysis & Synthesis
successfully on the project and all of its partitions, the individual partitions
must be merged together so that it can be compiled again as a complete
project.
Incremental Synthesis may be useful if you want to work on partitions of
your design in stages. Incremental Synthesis may not be useful in projects
that need to have optimizations across hierarchical boundaries.
The following steps describe the basic flow for setting up a design for
incremental synthesis:
1. Perform Analysis & Elaboration.
2. Specify one or more entities of the project as partitions. Refer to
“Assigning Design Partitions” on page 62 in Chapter 3, “Constraint
Entry.”
3. Make sure Incremental Synthesis only is selected for Incremental
compilation in the Design Partitions Window (Assignments menu) or
in the Compiler Process Settings page of the Settings dialog box
(Assignments menu).