Intel Quartus Prime Pro Edition User Guide: Design Compilation
Version Information
Updated for: |
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Intel® Quartus® Prime Design Suite 21.1 |
1. Design Compilation
The Intel® Quartus® Prime Pro Edition version of the Compiler supports these advanced features:
- Supports Intel® Arria® 10, Intel® Cyclone® 10 GX, Intel® Stratix® 10, and Intel® Agilex™ devices.
- Incremental Fitter optimization—analyze and optimize after each Fitter stage to maximize performance and shorten total compilation time.
- Hyper-Aware Design Flow—use Hyper-Retiming and Fast Forward compilation for the highest performance in Intel® Stratix® 10 and Intel® Agilex™ devices.
- Partial Reconfiguration—dynamic reconfiguration of a portion of the FPGA, while the remaining FPGA continues to function.
- Block-Based Design Flows—preservation and reuse of design blocks.
1.1. Compilation Overview
Compilation Process | Description |
---|---|
IP Generation | Identifies the status and version of IP components in the project. Reports outdated IP that require upgrade. |
Analysis & Synthesis |
Synthesizes, optimizes, minimizes, and maps design logic to device resources. The "synthesized" snapshot preserves the results of this stage. Analysis & Elaboration is a stage of Analysis & Synthesis. This stage checks for design file and project errors. |
Fitter (Place & Route) |
Assigns the placement and routing of the design to specific device resources, while honoring timing and placement constraints. The Fitter includes the following stages:
|
Fast Forward Timing Closure Recommendations | Generates detailed reports that estimate performance gains achievable by making specific RTL modifications. |
Timing Analysis | Analyzes and validates the timing performance of all design logic with the Timing Analyzer. |
Power Analysis | Optional module that estimates device power consumption. Specify the electrical standard on each I/O cell and the board trace model on each I/O standard in your design. |
Assembler | Converts the Fitter's placement and routing assignments into a programming image for the FPGA device. |
EDA Netlist Writer | Generates output files for use in other EDA tools, as Integrating Other EDA Tools describes. |
- Added support for new features in supported FPGA devices.
- Added support for new devices.
- Efficiency and performance improvements.
- Improvements to compilation time and resource use of the design software.
1.1.1. Compilation Flows
As you develop and optimize your design, run only the Compiler stages that you need, rather than waiting for full compilation. Run full compilation only when your design is complete and you are ready to run all Compiler modules and generate a device programming image.
Compiler Flow | Function |
---|---|
ECO Compilation Flow | The Intel® Quartus® Prime Pro Edition software supports last-minute, targeted design changes (also known as engineering change orders (ECOs)), even after you fully compile the design. ECOs typically occur during the design verification stage. Refer to the Intel® Quartus® Prime Pro Edition User Guide: Design Optimization. |
Incremental Optimization Flow | Incremental optimization allows you to stop processing after each Fitter stage, analyze the results, and adjust settings or RTL before proceeding to the next compilation stage. This iterative flow optimizes at each stage, without waiting for full compilation results. |
Hyper-Aware Design Flow | Combines automated register retiming (Hyper-Retiming), with implementation of targeted timing closure recommendations (Fast Forward Compilation), to maximize use of Hyper-Registers and drive the highest performance in Intel® Stratix® 10 and Intel® Agilex™ devices. |
Full Compilation Flow | Launches all Compiler modules in sequence to synthesize, fit, analyze final timing, and generate a device programming file. By default, the Compiler generates and preserves only the synthesized and final snapshots during a full compilation. You can optionally Enable Intermediate Fitter Snapshots to preserve the planned, placed, routed, and retimed snapshots. |
Partial Reconfiguration | Reconfigures a portion of the FPGA dynamically, while the remaining FPGA design continues to function. |
Block-Based Design Flows | Supports preservation and reuse of design blocks in one or more projects. You can reuse synthesized or final design blocks in other projects. Reusable design blocks can include device core or periphery resources. |
1.1.2. Compilation Hierarchy
If you use design partitions, such as in block-based design, the Compiler also isolates the results for each design partition. The Compiler fully preserves routing and placement within a partition. Changes to other portions of the design hierarchy do not impact the partition. This hierarchical structure allows you to optimize specific design elements without impacting placement and routing in other partitions. The hierarchical project structure also supports distributed work groups and compilation processing across multiple machines.
1.2. Design Synthesis
Synthesis examines the logical completeness and consistency of the design, and checks for boundary connectivity and syntax errors. Synthesis also minimizes and optimizes design logic. For example, synthesis infers D flip flops, latches, and state machines from "behavioral" languages, such as Verilog HDL, VHDL, and SystemVerilog. Synthesis may replace operators, such as + or –, with modules from the Intel® Quartus® Prime IP library, when advantageous. During synthesis, the Compiler may change or remove user logic and design nodes. Intel® Quartus® Prime synthesis minimizes gate count, removes redundant logic, and ensures efficient use of device resources.
At the end of synthesis, the Compiler generates an atom netlist. Atom refers to the most basic hardware resource in the FPGA device. Atoms include logic cells organized into look-up tables, D flip flops, I/O pins, block memory resources, DSP blocks, and the connections between the atoms. The atom netlist is a database of the atom elements that design synthesis requires to implement the design in silicon.
1.2.1. Running Synthesis
- Create or open an Intel® Quartus® Prime project with valid design files for compilation.
-
Before running synthesis, specify any of the following settings
and constraints that impact synthesis:
- To specify options for the synthesis of Verilog HDL input files, click Assignments > Settings > Verilog HDL Input.
- To specify options for the synthesis of VHDL input files, click Assignments > Settings > VHDL Input.
- To specify options that affect compilation processing time, click Assignments > Settings > Compilation Process Settings.
- To specify the Compiler's high-level optimization strategy and other options, click Assignments > Settings > Compiler Settings. Specify the optimization goal, according to Optimization Modes.
- On the Compiler Settings page enable or disable the Enable Intermediate Fitter Snapshots option to preserve snapshots for the Plan, Place, Route, and Retime stages any time you run full compilation. The Compiler does not generate intermediate snapshots by default.
- To specify advanced synthesis settings, click Assignments > Settings > Compiler Settings, and then click Advanced Settings (Synthesis).
- Consider enabling fractal synthesis for arithmetic-intensive designs that exhaust all DSP resources, according to the guidelines in Fractal Synthesis Optimization.
- To run synthesis, click Synthesis on the Compilation Dashboard.
1.2.1.1. Preserving Registers During Synthesis
Assign the Preserve Registers in Synthesis or Preserve Fan-Out Free Register Node options to allow Fitter optimization of the preserved registers. Preserve Registers restricts Fitter optimization of the preserved registers. Specify synthesis preservation assignments by clicking Assignments > Assignment Editor, by modifying the .qsf file, or by specifying synthesis attributes in your RTL.
Assignment | Description | Allows Fitter Optimization? | Assignment Syntax |
---|---|---|---|
Preserve Registers in Synthesis | Prevents removal of registers during synthesis. This settings does not affect retiming or other optimizations in the Fitter. | Yes |
|
Preserve Fan-Out Free Register Node | Prevents removal of assigned
registers without fan-out during synthesis. The PRESERVE_FANOUT_FREE_NODE assignment cannot preserve a fanout-free register that has no fanout inside the Verilog HDL or VHDL module in which you define it. To preserve these fanout-free registers, implement the noprune pragma in the source file: (*noprune*)reg r; If there are multiple instances of this module, with only some instances requiring preservation of the fanout-free register, set a dummy pragma on the register in the HDL and also set the PRESERVE_FANOUT_FREE_NODE assignment. This dummy pragma allows the register synthesis to implement the assignment. For example, set the following dummy pragma for a register r in Verilog HDL: (*dummy*)reg r; |
Yes |
|
Preserve Registers | Prevents removal and sequential optimization of assigned registers during synthesis. Sequential netlist optimizations can eliminate redundant registers and registers with constant drivers. | No |
|
1.2.2. Synthesis Reports
1.3. Design Place and Route
By default, the Fitter selects appropriate resources, interconnection paths, and pin locations. If you assign logic to specific device resources, the Fitter attempts to match those requirements, and then fits and optimizes any remaining unconstrained design logic. If the Fitter cannot fit the design in the current target device, the Fitter terminates compilation and issues an error message.
The Intel® Quartus® Prime Pro Edition Fitter introduces a hybrid placement technique that combines analytical and annealing placement techniques. Analytical placement determines an initial mathematical starting placement. The annealing technique then fine-tunes logic block placement in high resource utilization scenarios.
1.3.1. Using the Compilation Dashboard
The Compilation Dashboard appears by default when you open a project, or you can click Compilation Dashboard in the Tasks window to re-open it.
- Click the Pencil icon to edit settings for that stage of the compilation flow.
- Click any Compiler stage to run one or more Compiler stage.
You can click a Compiler stage to resume an interrupted compilation flow provided no compilation settings have changed from the initial start of the compilation flow.
- Click the Report, RTL Viewer, Technology Map Viewer, Timing Analyzer, or Snapshot Viewer icons for analysis of stage results.
As the Compiler progresses through the flow, the dashboard updates the status of each module, and enables icons that you can click for reports and analysis. The dashboard is also updated if you run your compilation flow from a command line with the quartus_sh --flow command.
1.3.2. Running the Fitter
The Intel® Quartus® Prime Pro Edition Compiler allows control and optimization of each individual Fitter stage, including the Plan, Early Place, Place, and Route stages. Run all stages of the Fitter as part of a full design compilation, or run any Fitter stage independently after design synthesis. Before running the Fitter, you specify settings that impact Fitter processing.
After running a Fitter stage, view detailed report data and analyze the timing of that stage. The Compiler preserves Fitter results of the final snapshot by default.
-
Specify initial Fitter constraints:
- To assign device I/O pins, click Assignments > Pin Planner.
- To assign device periphery, clocks, and I/O interfaces, click Tools > Interface Planner .
- To constrain logic placement regions, click Tools > Chip Planner.
- To specify Fitter optimization goals, click Assignments > Settings > Compiler Settings. Optimization Modes describes these options in detail
- To fine-tune place and route with advanced Fitter options, click Assignments > Settings > Compiler Settings > Advanced Settings (Fitter)
-
To run one or more stages of the Fitter, click any of the following
commands on the Compilation Dashboard:
- To run all Fitter stages in sequence, click Fitter.
- To run only device periphery placement and routing, click Plan.
- To run only early placement, click Early Place.
- To run only logic placement, click Place.
- To run only logic routing, click Route.
- To run only retiming of ALM registers into Hyper-Registers, click Retime.2
- To run the Implement flow (runs Plan, Place, Route, and Retime stages), click Fitter (Implement).
- To run the Finalize flow (runs Plan, Early Place, Place, Route, Retime, and Finalize stages), click Fitter (Finalize).
1.3.2.1. Fitter Commands
Command | Description |
---|---|
Start Fitter (Plan) |
Loads synthesized periphery placement data and constraints, and assigns periphery elements to device I/O resources. This command creates the planned snapshot. |
Start Fitter (Place) |
Places all core elements in a legal location. This command creates the placed snapshot. |
Start Fitter (Route) |
Creates all routing between the elements in the design. This command creates the routed snapshot. |
Start Fitter (Retime) |
Performs register retiming and moves existing registers into Hyper-Registers to increase performance by removing retiming restrictions and eliminating critical paths. The Compiler may report hold violations for short paths following the Retime stage. This command creates the retimed snapshot. |
Start Fitter (Finalize) |
Performs post-routing optimization on the design. The Fitter identifies and corrects the short paths with hold violations during the Fitter (Finalize) stage by adding routing wire along the paths. This stage converts unneeded tiles from High Speed to Low Power. This command creates the final snapshot. For Intel® Stratix® 10 and Intel® Agilex™ designs, the Fitter also runs post-route fix-up to correct any short path hold violations remaining from retiming. |
1.3.2.2. Enabling Physical Synthesis Optimization
To enable physical synthesis options:
- Click Assignments > Settings > Compiler Settings.
- To enable retiming, combinational optimization, and register duplication, click Advanced Settings (Fitter). Next, enable Physical Synthesis.
- View physical synthesis results in the Netlist Optimizations report.
1.3.3. Viewing Fitter Reports
1.3.3.1. Plan Stage Reports
For Intel® Arria® 10 and Intel® Cyclone® 10 GX designs, the Plan stage includes the Global & Other Fast Signals Summary report that allows you to verify which clocks the Compiler promotes to global clocks. Clock planning occurs after the Early Place stage for Intel® Stratix® 10 and Intel® Agilex™ designs.
1.3.3.2. Place Stage Reports
1.3.3.2.1. Global Signal Visualization Report
View global clock tree implementation details and assess capacity to add more global signals to the design. In cases of clock tree synthesis errors, the report can also show targeted regions for failing signals, and competing signals that are contributing to routing congestion.
The interactive heatmap color gradients show clock sector congestion of the clock signals terminating inside the sector. Hover the cursor over a clock signal in the table to highlight the clocks sectors and routing elements. Select a clock signal in the table to dim all irrelevant sectors and routing elements, while highlighting only the clock's sectors and routing elements. The global clock signal routing on different layers displays in the report's stacked layer view.
Filter the display to Show Routing Utilization and Show Sector Utilization. The content of the table changes based on the selections you make in the heatmap. You can search for Signal Names, and then select the signal names to display its properties in the lower pane. Select any signal to Locate in other tools.
1.3.3.3. Route Stage Reports
1.3.3.3.1. Global Router Wire Utilization Map Report
Filter the Global Router Wire table to show short or long Wirelengths in all Directions. The content of the table changes based on the selections you make in the heatmap. You can search for Signal Names, and then single- or multi-select the signal names to display properties in the lower pane. Select one or more node in the table to Locate in various editors.
1.3.3.4. Retime Stage Reports
1.3.3.5. Finalize Stage Reports
- HSLP Summary. For Intel® Arria® 10 and Intel® Cyclone® 10 GX designs, the Compiler converts unnecessary tiles to High-Speed or Low-Power (HSLP) tiles.
- Post-route hold fix-up data. For Intel® Stratix® 10 and Intel® Agilex™ designs, the Compiler reports hold violations for short paths following the Retime stage. The Fitter identifies and corrects the short paths with hold violations during the Fitter (Finalize) stage by adding routing wire along the paths.
1.4. Incremental Optimization Flow
Fitter Stage | Incremental Optimization |
---|---|
Plan | After this stage, you can run post-Plan timing analysis to verify timing constraints, and validate cross-clock timing windows. View the placement and properties of periphery (I/O). |
Place | After this stage, validate resource and logic utilization in the Compilation Reports, and review placement of design elements in the Chip Planner. |
Route | After this stage, perform detailed setup and hold timing closure in the Timing Analyzer, and view routing congestion via the Chip Planner. |
Retime | After this stage, review the Retiming results in the Fitter report and correct any restrictions limiting further retiming optimization. |
1.4.1. Concurrent Analysis During Synthesis or Fitting
During Analysis & Synthesis, you can click the Concurrent Analysis icons on the Dashboard to view reports, the RTL Viewer, or the Technology Map Viewer. While the Fitter is processing, you can analyze timing during the stages displaying the Timing Analyzer icon, and view Technology Map Viewer snapshots during Fitter stages. You should not modify timing constraints during concurrent analysis, because it affects the results of the underlying compile. However, you can halt a compile at any time, modify the .sdc constraints in your source file, and then click the Timing Analyzer icon to restart analysis with the modified constraints.
1.4.2. Analyzing Compiler Snapshots
1.4.2.1. Running Snapshot Viewer
Design Task | Available at Snapshot | Snapshot Viewer Commands |
---|---|---|
Timing Closure—Analyze Failing Paths | Planned, Placed, Routed, Finalized |
|
Placed, Routed, Finalized |
|
|
Timing Closure—Analyze
Clocking
This task is available only for Intel® Stratix® 10 devices. |
Placed, Finalized | Show Global Clock Visualization—loads the Global Signal Visualization report for the snapshot that allows you to visualize clock sector utilization. |
Timing Closure—Analyze High Fanout Nets | Placed, Routed, Finalized |
|
Timing Closure—Validate Constraints | Planned | Timing Exceptions—displays the Timing Exceptions Results report, that identifies timing paths with hold or removal slack exceeding threshold. |
Planned, Placed, Finalized | Check Unregistered Ports—displays the Check Unregistered Ports Results report, that identifies unregistered partition inputs and paths. | |
Timing Closure—Analyze Congestion | Placed, Routed, Finalized | Show Logic Lock Regions with Congestion Heat Map—the Chip Planner displays the Logic Lock regions in a congestion heat map for further analysis. |
The following sections describe each analysis task in detail.
1.4.2.1.1. Analyzing Failing Paths with Snapshot Viewer
- To run the Plan, Place, or Route stage of the Fitter, double-click the stage in the Compilation Dashboard.
-
After the stage completes, click the Snapshot Viewer icon for that stage in the Compilation
Dashboard. The Snapshot Viewer opens.
Figure 17. Snapshot Viewer Icon
-
Under Analyze Failing
Paths, click List Top Failing
Paths.
Figure 18. List Top Failing Paths
-
In Snapshot Selections,
select the failing path for analysis.
Figure 19. Snapshot Selections
- Under Select Failing Path to Analyze, click Show Full Timing Path in the Chip View. The path displays and highlights in the Chip Planner for further analysis.
-
Under Select Failing Path to
Analyze, click Show Full Timing Path
in Schematic. The path displays and highlights in RTL Viewer for
further analysis.
Figure 20. Show Full Timing Path in Schematic
-
Under Select Failing Path to
Analyze, click View Path
Characteristics. The path loads in the Timing Analyzer for
further analysis.
Figure 21. View Path Characteristics in Timing Analyzer
1.4.2.1.2. Analyzing Clocking with Snapshot Viewer
This task is available only for Intel® Stratix® 10 devices.
- Run the Place stage, and then click the Snapshot Viewer icon for the stage in the Compilation Dashboard. The Snapshot Viewer opens.
-
Under Analyze Clocking,
double-click Show Global Clock
Visualization. The Global Signal Visualization report displays
in Snapshot Viewer for analysis of clock sector and routing utilization.
Figure 22. Global Clock Visualization Report
1.4.2.1.3. Analyzing High Fan-out Nets with Snapshot Viewer
- To run the Place or Route stage of the Fitter, double-click the stage in the Compilation Dashboard.
- After the stage completes, click the Snapshot Viewer icon for that stage in the Compilation Dashboard. The Snapshot Viewer opens.
- Under Analyze High Fanout Nets, click Show High Fanout Nets in the Schematic. The path displays and highlights in Tech Map Viewer for further analysis.
-
Under Analyze High Fanout
Nets, click Show High Fanout Nets in
the Chip View. The path displays and highlights in the Chip
Planner for further analysis.
Figure 23. Non-Global High Fan-Out Signal in Chip Planner
1.4.2.1.4. Validating Timing Constraints with Snapshot Viewer
- To run the Plan or Place stage of the Fitter, double-click the stage in the Compilation Dashboard.
- After the stage completes, click the Snapshot Viewer icon for that stage in the Compilation Dashboard. The Snapshot Viewer opens.
-
Under Validate
Constraints, double-click Timing
Exceptions. The Timing Exception Results report open, allowing
additional analysis and locating to other tools.
Figure 24. Validate Constraints—Timing Exceptions Report
-
Under Validate Constraints, double-click
Check Unregistered Ports
Figure 25. Validate Constraints—Check Unregistered Ports Report
1.4.2.1.5. Analyzing Congestion with Snapshot Viewer
- To run the Place or Route stage of the Fitter, double-click the stage in the Compilation Dashboard.
- After the stage completes, click the Snapshot Viewer icon for that stage in the Compilation Dashboard. The Snapshot Viewer opens.
-
Under Analyze Congestion,
double-click Show Logic Lock Regions with Congestion
Heat Map. The Chip Planner displays the Logic Lock regions in a
congestion heat map for further analysis.
Figure 26. Show Logic Lock Regions with Congestion Heat Map
1.4.3. Validating Periphery (I/O) after the Plan Stage
- In the Compilation Dashboard, click the Plan stage.
-
In the Compilation Report, under the Plan Stage folder,
click the Input Pins, Output Pins,
I/O Bank Usage, PLL Usage
Summary, or other reports. Verify attributes of the I/O pins,
such as the physical pin location, I/O standards, and PLL placement.
Figure 28. Input Pins Report
-
For
Intel®
Arria® 10 and
Intel®
Cyclone® 10 GX designs, click Global & Other Fast Signals Summary report
to verify which clocks the Compiler promotes to global clocks. Clock planning
occurs after the Early Place stage for
Intel®
Stratix® 10
and
Intel®
Agilex™
designs.
Figure 29. Global & Other Fast Signals Report Shows Clock Promotion ( Intel® Arria® 10 and Intel® Cyclone® 10 GX FPGAs)
1.5. Fast Forward Compilation Flow
The Fast Forward compilation reports show precisely where to make the most impact with RTL changes, and the performance benefits you can expect from each change after removing retiming restrictions. The Fast Forward compilation flow includes the following high-level steps:
1.5.1. Step 1: Run Register Retiming
The Fitter runs the Retime stage automatically following place and route when you target an Intel® Stratix® 10 or Intel® Agilex™ device. Alternatively, start or stop the individual Retime stage in the Compilation Dashboard. After running register retiming, view the Fitter reports to optimize remaining critical paths.
To run register retiming:
-
Click Retime on the
Compilation Dashboard. The Compiler runs prerequisite stages automatically
before running Retime stage.
Figure 32. Retiming Stage in Compilation Dashboard
- Review the results of the register retiming stage, as Step 2: Review Retiming Results describes.
1.5.2. Step 2: Review Retiming Results
-
To open the Retiming Limit
Details report, click the Report icon for the Retime stage in the Compilation Dashboard. The Retiming Limit Details lists the number of
registers moved, their paths, and the limiting reason preventing further
retiming.
Figure 33. Retiming Limit Details
-
To further optimize, resolve any Limiting Reason in your design, and then rerun the Retime stage, as necessary.
Table 7. Retiming Limit Details Report Data Report Data Description Clock Transfer Lists each clock domain in your design. Click the domain to display data about each entry. Limiting Reason Specifies any design condition that prevent further register retiming improvement, such as any of the following conditions: - Insufficient Registers—indicates insufficient quantity of registers at either end of the chain for retiming. Adding more registers can improve performance.
- Short Path/Long Path—indicates that the critical chain has dependent paths with conflicting characteristics. For example, one path improves performance with more registers, and another path has no place for additional hyper-registers.
- Path Limit—indicates that there are no further Hyper-Register locations available on the critical path, or the design reached a performance limit of the current place and route.
- Loops—indicates a feedback path in a circuit. When the critical chain includes a feedback loop, retiming cannot change the number of registers in the loop without changing functionality. The Compiler can retime around the loop without changing functionality. However, the Compiler cannot place additional registers in the loop.
Critical Chain Details Lists register timing path associated with the retiming limitations. Right-click any path to Locate Critical Chain in Technology Map Viewer. - If register retiming achieves all performance goals for your design, proceed to Fitter (Finalize) and Timing Analysis stages of compilation.
- If your design requires further optimization, run Fast Forward Timing Closure Recommendations as Step 3: Run Fast Forward Compile describes.
1.5.2.1. Locate Critical Chains
- To open the Retiming Limit Details report, click the Report icon next to the Retime stage in the Compilation Dashboard.
-
Right-click any path in the Retiming Limit
Details report and click Locate Critical Chain in
Technology Map Viewer. The netlist displays as a schematic in the Technology
Map Viewer.
Figure 34. Technology Map ViewerFigure 35. Post-Fit Viewer After RetimingIn the post-fit viewer, bypassed ALM registers are gray. Hyper-Registers are pink with the word "HYPER" below them. Used ALMs are pink without the word "HYPER" below them
1.5.3. Step 3: Run Fast Forward Compile
You can review the Fast Forward recommendations and implement the changes in your RTL that remove timing restrictions and enable mobility within the netlist for register Hyper-Retiming.
You can run Fast Forward compilation for the entire design hierarchy, or for only specific instances in the hierarchy, as Fast Forward Compile By Hierarchy describes.
To generate Fast Forward timing closure recommendations, follow these steps:
-
Optionally, specify any of the following any of the following options
if you want to automate or refine Fast Forward analysis:
- If you want to run Fast Forward compilation during each full compilation, click Assignments > Settings > Compiler Settings > HyperFlex and enable Run Fast Forward Timing Closure Recommendations during compilation.
- If you want to modify how Fast Forward compilation interprets specific I/O and block types, click Assignments > Settings > Compiler Settings > HyperFlex > Advanced Settings.
-
On the Compilation Dashboard, click Fast
Forward Timing Closure Recommendations. The Compiler runs prerequisite
synthesis or Fitter stages automatically, as needed, and generates timing closure
recommendations in the Compilation Report.
Figure 36. Running Fast Forward Compilation
- View timing closure recommendations in the Compilation Report to evaluate design performance and implement key RTL performance improvements, as Step 4: Review Fast Forward Results describes.
1.5.3.1. Fast Forward Compile By Hierarchy
Follow these steps to include or exclude specific design subhierarchies and instances during Fast Forward compilation:
-
To enable the optional Fast Forward Compilation stage during
full compilation, turn on Fast Forward Timing Closure
Recommendations on the Compilation Dashboard, or add the
following assignment to the project .qsf:
set_global_assignment -name FLOW_ENABLE_HYPER_RETIMER_FAST_FORWARD ON
Figure 37. Enable Fast Forward Timing Closure Recommendations -
To exclude a specific hierarchy or entity from Fast Forward
Compilation, set the Enable Hyper-Retimer Fast
Forward Hierarchy analysis during compilation assignment to
Off in the Assignment Editor, or add
the following assignment to the project .qsf
for each hierarchy or entity that you want to exclude:
set_global_assignment -name HYPER_RETIMER_FAST_FORWARD_ON_HIERARCHY OFF \ <INSTANCE MODULE NAME>
-
To include a specific hierarchy or entity from Fast Forward
Compilation, set the Enable Hyper-Retimer Fast
Forward Hierarchy analysis during compilation assignment to
On in the Assignment Editor, or add
the following assignment to the project .qsf
for each hierarchy or entity that you want to include:
set_global_assignment -name HYPER_RETIMER_FAST_FORWARD_ON_HIERARCHY ON \ <INSTANCE MODULE NAME>
- Click the Fast Forward Timing Closure Recommendations stage on the Compilation Dashboard, or click Processing > Start Compilation to run a full compilation that includes Fast Forward Compile.
You can mix ON and OFF assignments for the same instance within a single .qsf. If you assign mixed ON and OFF assignments to the same instance, the last assignment that appears in the .qsf takes precedence.
If you want to perform Fast Forward analysis for a subset of the hierarchies in your design, turn off Fast Forward analysis for all hierarchies that you want to omit from analysis. Otherwise, turn off Fast Forward analysis at the root hierarchy, and turn on Fast Forward analysis for the hierarchies that you want to analyze. The following examples show some of these assignment combinations, with respect to the Example Design Hierarchy.
# This runs Fast Forward Compile on the entire hierarchy: A,B,C,D,E,F # This produces the same result as if FAST_FORWARD_HIERARCHY was not set in the QSF set_global_assignment -name FLOW_ENABLE_HYPER_RETIMER_FAST_FORWARD ON set_instance_assignment -name HYPER_RETIMER_FAST_FORWARD_ON_HIERARCHY ON -to |
# Runs Fast Forward Compile on B and E only, ignores A,C,D,F set_global_assignment -name FLOW_ENABLE_HYPER_RETIMER_FAST_FORWARD ON set_instance_assignment -name HYPER_RETIMER_FAST_FORWARD_ON_HIERARCHY OFF -to | set_instance_assignment -name HYPER_RETIMER_FAST_FORWARD_ON_HIERARCHY ON -to B
# Runs Fast Forward Compile on C only, ignores A,B,D,E,F set_global_assignment -name FLOW_ENABLE_HYPER_RETIMER_FAST_FORWARD ON set_instance_assignment -name HYPER_RETIMER_FAST_FORWARD_ON_HIERARCHY OFF -to | set_instance_assignment -name HYPER_RETIMER_FAST_FORWARD_ON_HIERARCHY ON -to C set_instance_assignment -name HYPER_RETIMER_FAST_FORWARD_ON_HIERARCHY OFF -to F
# ON instance HYPER_RETIMER_FAST_FORWARD_ON_HIERARCHY takes precedence # Fast Forward Compile runs on only C and F # If the assignments were reversed then FFC would not run set_global_assignment -name FLOW_ENABLE_HYPER_RETIMER_FAST_FORWARD ON set_instance_assignment -name HYPER_RETIMER_FAST_FORWARD_ON_HIERARCHY OFF -to | set_instance_assignment -name HYPER_RETIMER_FAST_FORWARD_ON_HIERARCHY OFF -to C set_instance_assignment -name HYPER_RETIMER_FAST_FORWARD_ON_HIERARCHY ON -to C
# This runs on A,B,C,F set_global_assignment -name FLOW_ENABLE_HYPER_RETIMER_FAST_FORWARD ON set_instance_assignment -name HYPER_RETIMER_FAST_FORWARD_ON_HIERARCHY OFF -to D set_instance_assignment -name HYPER_RETIMER_FAST_FORWARD_ON_HIERARCHY OFF -to E
1.5.3.2. HyperFlex Settings
Option | Description |
---|---|
Fast Forward Compile Asynchronous Clears | Specifies
how Fast Forward analysis accounts for registers with asynchronous
clear signals. The options are:
|
Fast Forward Compile Cut All Clock Transfers | Cuts all clock transfers in Fast Forward Compilation analysis. |
Fast Forward Compile Fully Registered DSP Blocks | Specifies how Fast Forward analysis accounts for DSP blocks that limit performance. Enable this option to generate results as if all DSP blocks are fully registered. |
Fast Forward Compile Fully Registered RAM Blocks | Specifies how Fast Forward analysis accounts for RAM blocks that limit performance. Enable this option to analyze the blocks as fully registered. |
Fast Forward Compile Maximum Additional Pipeline Stages | Specifies the maximum number of pipeline stages that Fast Forward compilation explores. |
Fast Forward Compile User Preserve Directives | Specifies how Fast Forward compilation accounts for restrictions from user-preserve directives. |
1.5.4. Step 4: Review Fast Forward Results
1.5.4.1. Clock Fmax Summary Report
1.5.4.2. Fast Forward Details Report
Click any optimization Step in the report to view the implementation details and performance calculations for that step.
Right-click any path to locate to the critical chain in the Fast Forward Viewer. The Fast Forward Viewer displays a predictive representation of the complete design, after implementation of all Fast Forward recommendations.
Report Field | Description |
---|---|
Step | Displays the pre-optimized Base Performance fMAX, the recommended Fast Forward optimization steps, and the Fast Forward Limit critical path that prevents further optimization. |
Fast Forward Optimizations Analyzed | Summarizes the optimizations necessary to implement each optimization step. |
Estimated Fmax | Specifies the potential fMAX performance if you implement all Fast Forward optimization steps. |
Optimizations Analyzed For Fast Forward Step | Lists design recommendations hierarchically for the selected Step. Click the text to expand the report and view the clock domain, the affected module, and the bus and bits that require modification. |
Optimizations Analyzed (Cumulative) | Accumulated list of all design changes necessary to reach the selected Step. |
Critical Chain at Fast Forward Limit | Displays information about any path that continues to limit Hyper-Retiming even after application of all Fast Forward steps. The critical chain is any path that limits further Hyper-Retiming. Click the Fast Forward Limit step to display this field. |
Recommendations for Critical Chain | Lists register timing path associated with the retiming limitations. Right-click any path to Locate Critical Chain in Fast Forward Viewer. |
1.5.5. Step 5: Implement Fast Forward Recommendations
- Implement one or more Fast Forward recommendations in your design RTL, such as any of the
following techniques:
- Remove limitations of control logic, such as long feedback loops and state machines.
- Restructure logic to use functionally equivalent feed-forward or pre-compute paths, rather than long combinatorial feedback path.
- Reduce the delay of ‘Long Paths’ in the chain. Use standard timing closure techniques to reduce delay. Excessive combinational logic, sub-optimal placement, and routing congestion cause delay on paths.
- Insert more pipeline stages in ‘Long Paths’ in the chain. Long paths have the most delay between registers in the critical chain.
- Increase the delay (or add pipeline stages to ‘Short Paths’ in the chain).
- Explore performance and implement the RTL changes to your code until you reach the desired performance target.
- Implement your RTL changes and perform Hyper-Retiming by re-running the Retime stage on the Compilation Dashboard (which also reruns prerequisite synthesis and fitting stages).
1.5.6. Retiming Restrictions and Workarounds
In Figure 44, the red line represents the same critical chain. Timing restrictions prevent register A from retiming forward. Timing restrictions also prevent register B from retiming backwards. A loop occurs when register A and register B are the same register.
Fast Forward recommendations for the critical chain include:
- Reduce the delay of ‘Long Paths’ in the chain. Use standard timing closure techniques to reduce delay. Combinational logic, sub-optimal placement, and routing congestion, are among the reasons for path delay.
- Insert more pipeline stages in ‘Long Paths’ in the chain. Long paths are the parts of the critical chain that have the most delay between registers.
- Increase the delay (or add pipeline stages to ‘Short Paths’ in the chain).
Particular registers in critical chains can limit performance for many other reasons. The Compiler classifies the following types of reasons that limit further optimization by retiming:
- Insufficient Registers
- Loop
- Short path/long path
- Path limit
After understanding why a particular critical chain limits your design’s performance, you can then make RTL changes to eliminate that bottleneck and increase performance.
Design Condition | Hyper-Register Support |
---|---|
Initial conditions that cannot be preserved | Hyper-Registers do have initial condition support. However, you cannot perform some retiming operations while preserving the initial condition stage of all registers (that is, the merging and duplicating of Hyper-Registers). If this condition occurs in the design, the Fitter does not retime those registers. This retiming limit ensures that the register retiming does not affect design functionality. |
Register has an asynchronous clear | Hyper-Registers support only data and clock inputs. Hyper-Registers do not have control signals such as asynchronous clears, presets, or enables. The Fitter cannot retime any register that has an asynchronous clear. Use asynchronous clears only when necessary, such as state machines or control logic. Often, you can avoid or remove asynchronous clears from large parts of a datapath. |
Register drives an asynchronous signal | This design condition is inherent to any design that uses asynchronous resets. Focus on reducing the number of registers that are reset with an asynchronous clear. |
Register has don’t touch or preserve attributes | The Compiler does not retime registers with these attributes. If you use the preserve attribute to manage register duplication for high fan-out signals, try removing the preserve attribute. The Compiler may be able to retime the high fan-out register along each of the routing paths to its destinations. Alternatively, use the dont_merge attribute. The Compiler retimes registers in ALMs, DDIOs, single port RAMs, and DSP blocks. |
Register is a clock source | This design condition is uncommon, especially for performance-critical parts of a design. If this retiming restriction prevents you from achieving the required performance, consider whether a PLL can generate the clock, rather than a register. |
Register is a partition boundary | This condition is inherent to any design that uses design partitions. If this retiming restriction prevents you from achieving the required performance, add additional registers inside the partition boundary for Hyper-Retiming. |
Register is a block type modified by an ECO operation | This restriction is uncommon. Avoid the restriction by making the functional change in the design source and recompiling, rather than performing an ECO. |
Register location is an unknown block | This restriction is uncommon. You can often work around this condition by adding extra registers adjacent to the specified block type. |
Register is described in the RTL as a latch | Hyper-Registers cannot implement latches. The Compiler infers latches because of RTL coding issues, such as incomplete assignments. If you do not intend to implement a latch, change the RTL. |
Register location is at an I/O boundary | All designs contain I/O, but you can add additional pipeline stages next to the I/O boundary for Hyper-Retiming. |
Combinational node is fed by a special source | This condition is uncommon, especially for performance-critical parts of a design. |
Register is driven by a locally routed clock | Only the dedicated clock network clocks Hyper-Registers. Using the routing fabric to distribute clock signals is uncommon, especially for performance-critical parts of a design. Consider implementing a small clock region instead. |
Register is a timing exception end-point | The Compiler does not retime registers that are sources or destinations of .sdc constraints. |
Register with inverted input or output | This condition is uncommon. |
Register is part of a synchronizer chain | The Fitter optimizes synchronizer chains to increase the mean time between failure (MTBF), and the Compiler does not retime registers that are detected or marked as part of a synchronizer chain. Add more pipeline stages at the clock domain boundary adjacent to the synchronizer chain to provide flexibility for the retiming. Alternatively, you can reduce the detection number for that particular synchronizer chain Synchronization Register Chain Length (default is 3). In some cases a synchronizer chain isn't necessary, and shouldn't be inferred. |
Register with multiple period requirements for paths that start or end at the register (cross-clock boundary) | This situation occurs at any cross-clock boundary, where a register latches data on a clock at one frequency, and fans out to registers running at another frequency. The Compiler does not retime registers at cross-clock boundaries. Consider adding additional pipeline stages at one side of the clock domain boundary, or the other, to provide flexibility for retiming. |
1.6. Full Compilation Flow
-
Before running a full compilation, specify any of the following
project settings:
- To specify the target FPGA device or development kit, click Assignments > Device.
- To specify device and pin options for the target FPGA device, click Assignments > Device > Device and Pin Options.
- To specify options that affect compilation processing time and netlist preservation, click Assignments > Settings > Compilation Process Settings.
- To specify the Compiler's high-level optimization strategy, click Assignments > Settings > Compiler Settings. Specify a Balanced strategy, or optimize for Performance, Area, Routability, Power, or Compile Time. The Compiler targets the optimization goal you specify. Optimization Modes describes these options in detail.
- To specify synthesis algorithm and other Advanced Settings for synthesis and fitting, click Assignments > Settings > Compiler Settings. Turn on Enable Intermediate Fitter Snapshots to preserve the planned, placed, routed, and retimed snapshots by default during full compilation.
- To specify required timing conditions for proper operation of your design, click Tools > Timing Analyzer.
-
To run full compilation, click Processing > Start Compilation.
Note:
- To save processing time, the Compiler only preserves the planned, placed, routed, and retimed snapshots by default during full compilation if you turn on Enable Intermediate Fitter Snapshots (Assignments > Settings > Compiler Settings).
- Early Place does not run during full compilation by default. To enable Early Place during full compilation, click Assignments > Settings > Compiler Settings > Advanced Settings (Fitter) to modify the Run Early Place during compilation option.
1.7. Exporting Compilation Results
You can export the .qdb for your entire project or for a design partition that you define in your project. When migrating the database for an entire project, you can export the compilation database in a version-compatible format to ensure compatibility for import to a later software version. Although you cannot directly read the contents of the .qdb file after export, you can view attributes of the database file in the Quartus Database File Viewer.
To Export Compilation Results For | Method | Description |
---|---|---|
Complete Design | Click Project > Export Design | Saves compilation results for the entire project in a version-compatible Quartus database file (.qdb) that you can import to another project or migrate to a later version of the Intel® Quartus® Prime software. You can export the results for the synthesized or final compilation snapshot. |
Design Partition | Click Project > Export Design Partition | Saves compilation results for a design partition as a Partition Database File (.qdb) that you can import to another project using the same version of the Intel® Quartus® Prime software. You can export the results for the synthesized or final compilation snapshot. |
1.7.1. Exporting a Version-Compatible Compilation Database
- In the Intel® Quartus® Prime software, open the project that you want to export.
-
Generate synthesis or final compilation results by running
one of the following commands:
- Click Processing > Start > Start Analysis & Synthesis to generate synthesized compilation results.
- Click Processing > Start Compilation to generate final compilation results.
-
Click Project > Export Design. Select the synthesized
or final
Snapshot.
Figure 45. Export Design Dialog Box
- Specify a name for the Quartus Database File to contain the exported results, and click OK.
- To include the exported design's settings and constraint files, copy the .qsf and .sdc files to the import project directory.
1.7.2. Importing a Version-Compatible Compilation Database
- Export a version-compatible compilation database for a complete design, as Exporting a Version-Compatible Compilation Database describes.
- In a newer version of the Intel® Quartus® Prime software, open the original project. Click Yes if prompted to open a project created with a different software version.
-
Click Project > Import Design and specify the Quartus Database
File. To remove previous results, turn on Overwrite existing project's databases
Figure 46. Import Design Dialog Box
- Click OK.
- When you compile the imported design, run only Compiler stages that occur after the stage the .qdb preserves, rather than running a full compilation. For example, if you import a version-compatible database that contains the synthesis snapshot, start compilation with the Fitter (Processing > Start > Start Fitter). If you import a version-compatible database the contains the final snapshot, start compilation with Timing Analysis (Signoff) (Processing > Start > Start Timing Analysis (Signoff)).
1.7.3. Creating a Design Partition
- In the Intel® Quartus® Prime software, open the project that you want to partition.
-
Generate synthesis or final compilation results by running one
of the following commands:
- Click Processing > Start > Start Analysis & Synthesis to generate synthesized compilation results.
- Click Processing > Start Compilation to generate final compilation results.
-
In the Project Navigator, right-click an instance in the
Hierarchy tab, click Design Partition > Set as Design Partition.
Figure 48. Creating a Design Partition from the Project Hierarchy
-
To view and edit all design partitions in the project, click
Assignments > Design Partitions Window.
Figure 49. Design Partitions Window
-
Specify the properties of the design partition in the Design
Partitions Window. The following settings are available:
Table 12. Design Partition Settings Option Description Partition Name Specifies the partition name. Each partition name must be unique and consist of only alphanumeric characters. The Intel® Quartus® Prime software automatically creates a top-level (|) "root_partition" for each project revision. Hierarchy Path Specifies the hierarchy path of the entity instance that you assign to the partition. You specify this value in the Create New Partition dialog box. The root partition hierarchy path is |. Type Double-click to specify one of the following partition types that control how the Compiler processes and implements the partition: - Default—Identifies a standard partition. The Compiler processes the partition using the associated design source files.
- Reconfigurable—Identifies a reconfigurable partition in a partial reconfiguration flow. Specify the Reconfigurable type to preserve synthesis results, while allowing refit of the partition in the PR flow.
- Reserved Core—Identifies a partition in a block-based design flow that is reserved for core development by a Consumer reusing the device periphery.
Preservation Level Specifies one of the following preservation levels for the partition: - Not Set—specifies no preservation level. The partition compiles from source files.
- synthesized—the partition compiles using the synthesized snapshot.
- final—the partition compiles using the final snapshot.
With Preservation Level of synthesized or final, changes to the source code do not appear in the synthesis.
Empty Specifies an empty partition that the Compiler skips. This setting is incompatible with the Reserved Core and Partition Database File settings for the same partition. The Preservation Level must be Not Set. An empty partition cannot have any child partitions. Partition Database File Specifies a Partition Database File (.qdb) that the Compiler uses during compilation of the partition. You export the .qdb for the stage of compilation that you want to reuse (synthesized or final). Assign the .qdb to a partition to reuse those results in another context. Entity Re-binding - PR Flow—specifies the entity that replaces the default persona in each implementation revision.
- Root Partition Reuse Flow —specifies the entity that replaces the reserved core logic in the consumer project.
Color Specifies the color-coding of the partition in the Chip Planner and Design Partition Planner displays. Post Synthesis Export File Automatically exports post-synthesis compilation results for the partition to the .qdb that you specify, each time Analysis & Synthesis runs. You can automatically export any design partition that does not have a preserved parent partition, including the root_partition. Post Final Export File Automatically exports post-final compilation results for the partition to the .qdb that you specify, each time the final stage of the Fitter runs. You can automatically export any design partition that does not have a preserved parent partition, including the root_partition.
1.7.4. Exporting a Design Partition
When you compile a design containing design partitions, the Compiler can preserve a synthesis or final snapshot of results for each partition. You can export the synthesized or final compilation results for individual design partitions with the Export Design Partition dialog box.
If the partition includes any entity-bound .sdc files, you can include those constraints in the .qdb. In addition, you can automate export of one or more partitions in the Design Partitions Window.
Manual Design Partition Export
Follow these steps to manually export a design partition with the Export Design Partition dialog box:
- Open a project and create one or more design partitions. Creating a Design Partition describes this process.
- Run synthesis (Processing > Start > Start Analysis & Synthesis) or full compilation (Processing > Start Compilation), depending on which compilation results that you want to export.
- Click Project > Export Design Partition, and specify one or more options in the Export Design Partition dialog box:
Figure 50. Export Design Partition Dialog Box
- Select the Partition name and the compilation Snapshot for export.
- To include any entity-bound .sdc files in the exported .qdb, turn on Include entity-bound SDC files for the selected partition.
- Click OK. The compilation results for the design partition exports to the file that you specify.
Automated Design Partition Export
Follow these steps to automatically export one or more design partitions following each compilation:
- Open a project containing one or more design partitions. Creating a Design Partition describes this process.
- To open the Design Partitions Window, click Assignments > Design Partitions Window.
- To automatically export a partition with synthesis results after each time you run synthesis, specify the a .qdb export path and file name for the Post Synthesis Export File option for that partition. If you specify only a file name without path, the file exports to the output_files directory after compilation.
- To automatically export a partition with final snapshot results each time you run the Fitter, specify a .qdb file name for the Post Final Export File option for that partition. If you specify only a file name without path, the file exports to the output_files directory after compilation.
.qsf Equivalent Assignment:
set_instance_assignment -name EXPORT_PARTITION_SNAPSHOT_<FINAL|SYNTHESIZED> \ <hpath> -to <file_name>.qdb
1.7.5. Reusing a Design Partition
To reuse an exported design partition in another project, you assign the exported partition .qdb to an appropriately configured design partition in the target project via the Design Partition Window:
- Export a design partition with the appropriate snapshot, as Exporting a Design Partition describes.
- Open the target Intel® Quartus® Prime project that you want to reuse the exported partition.
- Click Processing > Start > Start Analysis & Elaboration.
- Click Assignments > Design Partitions Window, and then create an appropriately sized design partition to contain the logic and compilation results of the exported .qdb.
-
Click the Partition Database File
option for the new partition and select the exported .qdb file.
Figure 52. Partition Database File Setting in Design Partitions Window
- Specify any other properties of the design partition in the Design Partitions Window. The Compiler uses the partition's assigned .qdb as the source.
1.7.6. Viewing Quartus Database File Information
The Intel® Quartus® Prime software automatically stores metadata about the project of origin when you export a Quartus Database File (.qdb). The Intel® Quartus® Prime software automatically stores metadata about the project of origin and resource utilization when you export a Partition Database File (.qdb) from your project. You can then use the Quartus Database File Viewer to display the attributes any of these .qdb files.
- In the Intel® Quartus® Prime software, click File > Open, select Design Files for Files of Type, and select a .qdb file.
-
Click Open. The Quartus
Database File Viewer displays project and resource utilization attributes of the .qdb.
Alternatively, run the following command-line equivalent:
quartus_cdb --extract_metadata --file <archive_name.qdb> \ --type quartus --dir <extraction_directory> \ [--overwrite]
1.7.6.1. QDB File Attribute Types
The Quartus Database Viewer can display the following attributes of a .qdb file:
QDB Attribute Types | Attribute | Example |
Project Information |
Contents | Partition |
Date | Thu Jan 23 10:56:23 2018 | |
Device | 10AX016C3U19E2LG | |
Entity (if Partition) | Counter | |
Family | Arria 10 | |
Partition Name | root_partition | |
Revision Name | Top | |
Revision Type | PR_BASE | |
Snapshot | synthesized | |
Version | 18.1.0 Pro Edition | |
Version-Compatible | Yes | |
Resource Utilization (exported for partition QDB only) |
For synthesized snapshot partition lists data from the Synthesis Resource Usage Summary report. |
Average fan-out.16 Dedicated logic registers:14 Estimate of Logic utilization:1 I/O pins:35 Maximum fan-out:2 Maximum fan-out node:counter[23] Total DSP Blocks:0 Total fan-out:6 ... |
For the final snapshot partition, lists data from the Fitter Partition Statistics report. |
Average fan-out:.16 Combinational ALUTs: 16 I/O Registers M20Ks ... |
1.7.7. Clearing Compilation Results
- Click Project > Clean Project.
- Select All revisions to clear the databases for all revisions of the current project, or specify a Revision name to clear only the revision’s database you specify.
- Click OK. A message indicates when the database is clean.
1.8. Integrating Other EDA Tools
The Intel® Quartus® Prime software supports input netlist files from supported EDA synthesis tools. The Compiler's EDA Netlist Writer module (quartus_eda) can automatically generate output files for processing in other EDA tools. The EDA Netlist Writer runs optionally as part of a full compilation, or you can run EDA Netlist Writer separately from the GUI or at the command line. The following functions are available to simplify EDA tool integration:
EDA Integration Task | EDA Integration Function |
---|---|
Specify settings for generation of output files for processing in other EDA tools. | Click Assignments > Settings > EDA Tool Settings to specify options for supported tools. |
Generate output files for processing in other EDA tools. | Click Processing > Start > Start EDA Netlist Writer (or run quartus_eda) to generate files. |
Compile RTL and gate-level simulation model libraries for your device, supported EDA simulators, and design language. |
Click Tools > Launch Simulation Library Compiler to compile simulation libraries easily. |
Generate EDA tool-specific setup scripts to compile, elaborate, and simulate Intel® FPGA IP models and simulation model library files. | Specify options for Simulation file output when generating Intel® FPGA IP with IP parameter editor. |
Generate files that allow supported EDA tools to perform netlist modifications, such as adding new modules, partitioning the netlist, and changing module connectivity. | Use the quartus_eda –resynthesis command to generate a Verilog Quartus Mapping File (.vqm) that contains a node-level (or atom) representation of the netlist in standard structural Verilog RTL. |
Include files generated by other EDA design entry or synthesis tools in your project as synthesized design files. |
Click Project > Add/Remove Files In Project to add supported Design File files from other EDA tools. |
1.8.1. Generating a VQM Netlist for other EDA Tools
The .vqm format is standard structural Verilog RTL. The modules can be any Intel FPGA family-specific WYSIWYG type for core logic (such as, flip-flop, LUT, DSP, M20K). EDA Netlist Writer does not support .vqm for periphery modules (such as transceivers, memory interfaces, I/O, or IP including these). The RTL is a fully flattened representation of the entire design hierarchy or partition. The module names capture the original hierarchy, although some renaming can occur to legalize names. There is no truncation of the netlist module names.
To perform .vqm netlist partitioning in other EDA tools, define a design partition that includes only core logic elements. Generate the partition netlist as step 3 describes. After processing the .vqm in third-party tools, resynthesize the .vqm files either independently or as a design partition. If including a black box module instantiation in the .vqm, make connections between existing logic in the .vqm and the black box. Prior to resynthesis, specify the source file (.ip, .v, or .vqm) for the black box in the project .qsf.
Requirement or Limitation | Description |
---|---|
Design partitions must only include core logic. | Design partitions must include only flip-flops, LUTs, DSPs, and on-chip memory. The EDA Netlist Writer does not support .vqm output for periphery modules (such as transceivers, memory interfaces, I/O, or IP that includes these). |
Analysis & Synthesis does not support some special characters in instance names that are legal in SystemVerilog. | Analysis & Synthesis resolves these characters by placing the standard escape character ‘\’ to escape the special character present in the RTL. If any of the hierarchical constraints (for example, SDC timing constraints) explicitly reference such a special character, modify these characters manually. |
Generate .vqm only for a synthesized netlist. | The post-fit netlist includes atoms, such as wire-luts, that are not appropriate for resynthesis. |
Avoid module or entity name collisions | If you add a .vqm, generated from an RTL design file, to the same Intel® Quartus® Prime project that generated the .vqm, beware of potential entity or module name collisions. Name collisions can occur if the original RTL file from which the .vqm derives, and the .vqm file itself, both specify the same entity or module name. When the RTL and .vqm files are both present in the project Files list, the Compiler uses the last entry in the list. |
Partition assignments might not align with the original design. | .vqm generation flattens all logic within a partition unless you specify the –exclude_sub_partitions argument. Compiling a design that has assignments pertaining to a flattened partition causes an error. |
To generate a .vqm for processing in other EDA tools, follow these steps:
- In the Intel® Quartus® Prime software, click Processing > Start > Start Analysis & Synthesis (or run quartus_syn) to synthesize the design netlist.
- Create a design partition containing only core logic elements for the .vqm, as Creating a Design Partition describes.
-
To generate the .vqm in the
resynthesis directory, run any of the following
commands at the command prompt:
- To write out the entire design netlist to .vqm:
quartus_eda –resynthesis=on <project_name>
- To write out only a specific design partition netlist to .vqm:
quartus_eda –resynthesis=on -partition=<name> <project_name>
- To write out any sub partition as a black-box netlist to .vqm:
quartus_eda –resynthesis=on –exclude_sub_partitions <project_name>
You can also combine –exclude_sub_partitions with -partition.
- To write out the entire design netlist to .vqm:
- View the resulting .vqm in the resynthesis directory, and specify the .vqm as input to your EDA tool.
- After processing the .vqm in another EDA tool, add the .vqm as an Intel® Quartus® Prime project design file by clicking Project > Add/Remove Files In Project). Avoid module or entity name collisions, as describes.
- Run Analysis & Synthesis on the project, followed by the remaining Compiler stages.
1.9. Synthesis Language Support
1.9.1. Verilog and SystemVerilog Synthesis Support
- Verilog-1995 (IEEE Standard 1364-1995)
- Verilog-2001 (IEEE Standard 1364-2001)
- SystemVerilog-2005 (IEEE Standard 1800-2005)
- SystemVerilog-2009 (IEEE Standard 1800-2009)
- SystemVerilog-2012 (IEEE Standard 1800-2012)
The following important guidelines apply to Intel® Quartus® Prime synthesis of Verilog HDL and SystemVerilog:
- The Compiler uses the Verilog-2001 standard by default for files with an extension of .v, and the SystemVerilog standard for files with the extension of .sv.
- If you use scripts to add design files, you can use the -HDL_VERSION command to specify the HDL version for each design file.
- Compiler support for Verilog HDL is case sensitive in accordance with the Verilog HDL standard.
- The Compiler supports the compiler directive `define, in accordance with the Verilog HDL standard.
- The Compiler supports the include compiler directive to include files with absolute paths (with either “/” or “\” as the separator), or relative paths.
- When searching for a relative path, the Compiler initially searches relative to the project directory. If the Compiler cannot find the file, the Compiler next searches relative to all user libraries. Finally, the Compiler searches relative to the current file's directory location.
- Intel® Quartus® Prime Pro Edition synthesis searches for all modules or entities earlier in the synthesis process than other Quartus software tools. This earlier search produces earlier syntax errors for undefined entities than other Quartus software tools.
1.9.1.1. Verilog HDL Input Settings (Settings Dialog Box)
Setting |
Description |
---|---|
Verilog Version |
Directs synthesis to process Verilog HDL input design files using the specified standard. You can select any of the supported language standards to match your Verilog HDL files or SystemVerilog design files. |
Library Mapping File |
Allows you to optionally specify a provided Library Mapping File (.lmf) for use in synthesizing Verilog HDL files that contain non-Intel FPGA functions mapped to IP cores. You can specify the full path name of the LMF in the File name box. |
Verilog HDL Macro | Verilog HDL macros are pre-compiler directives which can be added to Verilog HDL files to define constants, flags, or other features by Name and Setting. Macros that you add appear in the Existing Verilog HDL macro settings list. |
1.9.1.2. Design Libraries
- When compiling a design instance, the Compiler initially searches for the entity in the library associated with the instance (which is the work library if you do not specify any library).
- If the Compiler cannot locate the entity definition, the Compiler searches for a unique entity definition in all design libraries.
- If the Compiler finds more than one entity with the same name, the Compiler generates an error. If your design uses multiple entities with the same name, you must compile the entities into separate libraries.
1.9.1.3. Verilog HDL Configuration
- Specify a library search order for resolving cell instances (as does a library mapping file).
- Specify overrides to the logical library search order for specified instances.
- Specify overrides to the logical library search order for all instances of specified cells.
1.9.1.3.1. Hierarchical Design Configurations
For example, suppose a subhierarchy of a design is an eight-bit adder, and the RTL Verilog code describes the adder in a logical library named rtllib. The gate-level code describes the adder in the gatelib logical library. If you want to use the gate-level code for the 0 (zero) bit of the adder and the RTL level code for the other seven bits, the configuration might appear as follows:
Gate-level code for the 0 (zero) bit of the adder
config cfg1; design aLib.eight_adder; default liblist rtllib; instance adder.fulladd0 liblist gatelib; endconfig
If you are instantiating this eight-bit adder eight times to create a 64-bit adder, use configuration cfg1 for the first instance of the eight-bit adder, but not in any other instance. A configuration that performs this function is shown below:
Use configuration cfg1 for first instance of eight-bit adder
config cfg2; design bLib.64_adder; default liblist bLib; instance top.64add0 use work.cfg1:config; endconfig
1.9.1.4. Initial Constructs and Memory System Tasks
To avoid such errors, enclose non-synthesizable constructs (such as those intended only for simulation) in translate_off and translate_on synthesis directives. Synthesis of initial constructs enables the power-up state of the synthesized design to match the power-up state of the original HDL code in simulation.
Intel® Quartus® Prime synthesis supports the $readmemb and $readmemh system tasks to initialize memories.
Verilog HDL Code: Initializing RAM with the readmemb Command
reg [7:0] ram[0:15]; initial begin $readmemb("ram.txt", ram); end
When creating a text file to use for memory initialization, specify the address using the format @<location > on a new line, and then specify the memory word such as 110101 or abcde on the next line.
The following example shows a portion of a Memory Initialization File (.mif) for the RAM.
Text File Format: Initializing RAM with the readmemb Command
@0 00000000 @1 00000001 @2 00000010 … @e 00001110 @f 00001111
1.9.1.5. Verilog HDL Macros
To set Verilog HDL macros at the command line for the Intel® Quartus® Prime Pro Edition synthesis (quartus_syn) executable, use the following format:
quartus_syn <PROJECT_NAME> --set=VERILOG_MACRO=a=2
This command adds the following new line to the project .qsf file:
set_global_assignment -name VERILOG_MACRO "a=2"
To avoid adding this line to the project .qsf, add this option to the quartus_syn command:
--write_settings_files=off
1.9.2. VHDL Synthesis Support
- VHDL 1987 (IEEE Standard 1076-1987)
- VHDL 1993 (IEEE Standard 1076-1993)
- VHDL 2008 (IEEE Standard 1076-2008)
The Intel® Quartus® Prime Compiler uses the VHDL 1993 standard by default for files that have the extension .vhdl or .vhd.
1.9.2.1. VHDL Input Settings (Settings Dialog Box)
Setting |
Description |
---|---|
VHDL Version |
Specifies the VHDL standard for use during synthesis of VHDL input design files. Select the language standards that corresponds with the VHDL files. |
Library Mapping File |
Specifies a Library Mapping File (.lmf) for use in synthesizing VHDL files that contain IP cores. Specify the full path name of the LMF in the File name box. |
1.9.2.2. VHDL Standard Libraries and Packages
The STD library is part of the VHDL language standard and includes the packages standard (included in every project by default) and textio. For compatibility with older designs, the Intel® Quartus® Prime software also supports the following vendor-specific packages and libraries:
- Synopsys* packages such as std_logic_arith and std_logic_unsigned in the IEEE library.
- Mentor Graphics* packages such as std_logic_arith in the ARITHMETIC library.
- Primitive packages altera_primitives_components (for primitives such as GLOBAL and DFFE) and maxplus2 in the ALTERA library.
- IP core packages altera_mf_components in the ALTERA_MF library for specific IP cores including LCELL. In addition, lpm_components in the LPM library for library of parameterized modules (LPM) functions.
1.9.2.3. VHDL wait Constructs
VHDL wait until construct example
architecture dff_arch of ls_dff is begin output: process begin wait until (CLK'event and CLK='1'); Q <= D; Qbar <= not D; end process output; end dff_arch;
1.10. Compiler Optimization Techniques
1.10.1. Optimization Modes
Optimization Mode |
Description |
---|---|
Balanced (normal flow) |
The Compiler optimizes synthesis for balanced implementation that respects timing constraints. |
High Performance Effort |
The Compiler increases the timing optimization effort during placement and routing, and enables timing-related Physical Synthesis optimizations (per register optimization settings). Each additional optimization can increase compilation time. |
High Performance with Maximum Placement Effort | Enables the same Compiler optimizations as High Performance Effort, with additional placement optimization effort. |
Superior Performance | Enables the same Compiler optimizations as High Performance Effort, and adds more optimizations during Analysis & Synthesis to maximize design performance with a potential increase to logic area. If design utilization is already very high, this option may lead to difficulty in fitting, which can also negatively affect overall optimization quality. |
Superior Performance with Maximum Placement Effort | Enables the same Compiler optimizations as Superior Performance, with additional placement optimization effort. |
Aggressive Area |
The Compiler makes aggressive effort to reduce the device area required to implement the design at the potential expense of design performance. |
High Placement Routability Effort | The Compiler makes high effort to route the design at the potential expense of design area, performance, and compilation time. The Compiler spends additional time reducing routing utilization, which can improve routability and also saves dynamic power. |
High Packing Routability Effort | The Compiler makes high effort to route the design at the potential expense of design area, performance, and compilation time. The Compiler spends additional time packing registers, which can improve routability and also saves dynamic power. |
Optimize Netlist for Routability | The Compiler implements netlist modifications to increase routability at the possible expense of performance. |
High Power Effort |
The Compiler makes high effort to optimize synthesis for low power. High Power Effort increases synthesis run time. |
Aggressive Power |
Makes aggressive effort to optimize synthesis for low power. The Compiler further reduces the routing usage of signals with the highest specified or estimated toggle rates, saving additional dynamic power but potentially affecting performance. |
Aggressive Compile Time |
Reduces the compile time required to implement the design with reduced effort and fewer performance optimizations. This option also disables some detailed reporting functions. Note: Turning on Aggressive Compile Time enables
Intel®
Quartus® Prime Settings File (.qsf) settings which cannot be
overridden by other .qsf
settings.
|
1.10.2. Allow Register Retiming
Disable register retiming for entity abc
set_global_assignment –name ALLOW_REGISTER_RETIMING ON set_instance_assignment –name ALLOW_REGISTER_RETIMING OFF –to “abc|” set_instance_assignment –name ALLOW_REGISTER_RETIMING ON –to “abc|def|”
Disable register retiming for the whole design, except for registers in entity abc
set_global_assignment –name ALLOW_REGISTER_RETIMING OFF set_instance_assignment –name ALLOW_REGISTER_RETIMING ON –to “abc|” set_instance_assignment –name ALLOW_REGISTER_RETIMING OFF –to “abc|def|”
1.10.3. Automatic Gated Clock Conversion
ASIC Gated Clock Example | FPGA Clock Enable Example |
---|---|
module infer_enable (clk, reset, d, en, q); input d, en, clk, reset; output q; wire gated_clk; reg q; assign gated_clk = clk & en; always@(posedge gated_clk or reset) begin if (!reset) q <= 1’b0; else q <= d ; end endmodule |
module infer_enable (clk, reset, d, en, q); input d, en, clk, reset; output q; reg q; always@(posedge clk or reset) begin if (!reset) q <= 1’b0; else if (en) q <= d; else q <= q ; end endmodule |
Rather than manually converting gated clocks in your RTL, you can specify the Auto Gated Clock Conversion setting to automatically convert gated base clocks in the design to clock enables. You can apply this setting globally to all gated base clocks in the design, or to one or more specific clock signals.
Setting Scope |
Description |
---|---|
Global | Enable the Auto Gated Clock
Conversion option at Assignments > Settings > Compiler Settings > Advanced Settings (Synthesis). Alternatively, add the global assignment to the
project
.qsf:set_global_assignment –name SYNTH_GATED_CLOCK_CONVERSION on |
Instance-specific | Specify the Auto Gated Clock
Conversion for one or more instances in the
Assignment Editor (Assignments > Assignment Editor). Alternatively, add the instance assignment to the
project
.qsf:set_instance_assignment –name SYNTH_GATED_CLOCK_CONVERSION on –to clk_in |
1.10.4. Enable Intermediate Fitter Snapshots
However, you can turn on Enable Intermediate Fitter Snapshots (Assignments > Settings > Compiler Settings) to generate and preserve snapshots for the Plan, Place, Route, and Retime stages any time you run full compilation. You can also run any intermediate Fitter stage independently to generate the snapshot for that stage.
1.10.5. Fast Preserve Option
Interface logic is logic at the partition boundary that interfaces with the rest of the design.
1.10.6. Fractal Synthesis Optimization
Fractal synthesis is a set of synthesis optimizations that use FPGA resources in an optimal way for arithmetic-intensive designs. These synthesis optimizations consist of multiplier regularization and retiming, as well as continuous arithmetic packing. The optimizations target designs with large numbers of low-precision arithmetic operations (such as additions and multiplications). You can enable fractal synthesis globally or for specific multipliers, as Enabling or Disabling Fractal Synthesis describes.
Project-Wide Fractal Synthesis Considerations
- Intel FPGA devices contain thousands of hard DSP blocks that are perfectly suited for arithmetic operations. If the total amount of arithmetic functions in your design is small, then there is no need to enable Fractal Synthesis. In such cases, all the arithmetic functions map directly into DSPs by default. Enable global Fractal Synthesis only if there are not enough DSP blocks available to implement all arithmetic components. Enable Fractal Synthesis only for modules that you do not want the Compiler to map into DSPs.
- In the current version of the Intel® Quartus® Prime Pro Edition software, fractal synthesis optimizations target low-precision multiplication. Implement high-precision multipliers (where width of every operand exceeds 11 bits) using DSP blocks.
- If you enable project-wide Fractal Synthesis, the following information
message number 20193 may generate during
compilation:
Applied dense packing to "<entity>". Area: 2 LABs. Logic density: 0.775.
This information indicates the effort the Compiler is packing computational logic into a smaller number of LABs. If the design is already highly utilized, the Compiler can skip this stage.
- Verify that the Area the message reports does not exceed 100 LABs. If the Area exceeds 100 LABs, divide fractal synthesis blocks to sub-blocks, and then assign the fractal synthesis optimizations to the sub-blocks independently.
- Verify that the Logic density the message reports is greater than 0.75. If the logic density is less than 0.75, disable Fractal Synthesis for this entity because standard synthesis typically achieves better density.
Area (LABs) | |||
---|---|---|---|
Device | Dot-product | Fractal Synthesis ON | Fractal Synthesis OFF |
Intel® Arria® 10 and Intel® Cyclone® 10 GX | Sum of 16 4x4sm | 12 | 19 |
Sum of 16 5x5sm | 19 | 32 | |
Sum of 16 6x6sm | 25 | 36 | |
Sum of 16 7x7sm | 34 | 44 | |
Sum of 16 8x8sm | 45 | 60 | |
Intel® Stratix® 10 and Intel® Agilex™ Devices | Sum of 16 4x4sm | 15 | 22 |
Sum of 16 5x5sm | 21 | 39 | |
Sum of 16 6x6sm | 29 | 47 | |
Sum of 16 7x7sm | 39 | 55 | |
Sum of 16 8x8sm | 55 | 71 |
Multiplier Regularization and Retiming
Multiplier regularization and retiming performs inference of highly optimized soft multiplier implementations. The Compiler may apply backward retiming to two or more pipeline stages if required. When you enable fractal synthesis, the Compiler applies multiplier regularization and retiming to signed and unsigned multipliers.
- Multiplier regularization uses only logic resources, and does not use DSP blocks.
- Multiplier regularization and retiming is applied to both signed and unsigned multipliers in modules where the FRACTAL_SYNTHESIS QSF assignment is set.
Multiplier Regularization Example
The following simple, unsigned dot-product design example contains multiplication operators with 5-bit operands. These short multipliers are perfect candidates for multiplier regularization.
(* altera_attribute = "-name FRACTAL_SYNTHESIS ON" *) module dot_product( input clk, input [4:0] a, b, c, d, e, f, g, h, output reg [11:0] out ); reg [9:0] ab, cd, ef, gh; reg [10:0] ab_cd, ef_gh; always @(posedge clk) begin ab <= a * b; cd <= c * d; ef <= e * f; gh <= g * h; ab_cd <= ab + cd; ef_gh <= ef + gh; out <= ab_cd + ef_gh; end endmodule module top( input clk, input [4:0] a1, b1, c1, d1, e1, f1, g1, h1, input [4:0] a2, b2, c2, d2, e2, f2, g2, h2, output [11:0] out1, out2 ); dot_product core1(.clk(clk), .a(a1), .b(b1), .c(c1), .d(d1), .e(e1), .f(f1), .g(g1), .h(h1), .out(out1)); dot_product core2(.clk(clk), .a(a2), .b(b2), .c(c2), .d(d2), .e(e2), .f(f2), .g(g2), .h(h2), .out(out2)); endmodule
Intel® Quartus® Prime synthesis prints the following messages to the console:

In the Chip Planner, you can observe this design having two unsigned dot-product cores. These cores are independently optimized and placed. The LAB resources are nearly 100% optimized, as the following image shows:

Signed dot-products are common for deep-learning applications. The following demonstrates an example of a signed dot-product:
(* altera_attribute = "-name FRACTAL_SYNTHESIS ON" *) module dot_product( input signed clk, input signed [4:0] a, b, c, d, e, f, g, h, output reg signed [11:0] out ); reg signed [9:0] ab, cd, ef, gh; reg signed [10:0] ab_cd, ef_gh; always @(posedge clk) begin ab <= a * b; cd <= c * d; ef <= e * f; gh <= g * h; ab_cd <= ab + cd; ef_gh <= ef + gh; out <= ab_cd + ef_gh; end endmodule module top( input clk, input signed [4:0] a1, b1, c1, d1, e1, f1, g1, h1, input signed [4:0] a2, b2, c2, d2, e2, f2, g2, h2, output signed [11:0] out1, out2 ); dot_product core1(.clk(clk), .a(a1), .b(b1), .c(c1), .d(d1), .e(e1), .f(f1), .g(g1), .h(h1), .out(out1)); dot_product core2(.clk(clk), .a(a2), .b(b2), .c(c2), .d(d2), .e(e2), .f(f2), .g(g2), .h(h2), .out(out2)); endmodule
Intel® Quartus® Prime synthesis displays the following messages in the console:

In the Chip Planner, you can observe this design having two signed dot-product cores independently optimized and placed:

Continuous Arithmetic Packing
Continuous arithmetic packing re-synthesizes arithmetic gates into logic blocks optimally sized to fit into Intel® FPGA LABs. This optimization allows up to 100% utilization of LAB resources for the arithmetic blocks.
When you enable fractal synthesis, the Compiler applies this optimization to all carry chains and two-input logic gates. This optimization can pack adder trees, multipliers, and any other arithmetic-related logic.
Note that continuous arithmetic packing works independently of multiplier regularization. So, if you are using a multiplier that is not regularized (such as writing your own multiplier) then continuous arithmetic packing can still operate.
1.10.6.1. Enabling or Disabling Fractal Synthesis
For Intel® Stratix® 10 and Intel® Agilex™ devices, fractal synthesis optimization runs automatically for small multipliers (any A*B statement in Verilog HDL or VHDL where bit-width of the operands is 7 or less). You can also disable automatic fractal synthesis for small multipliers for these devices using either of the following methods:
- In RTL, set the DSP multstyle, as "Multstyle Verilog HDL
Synthesis Attribute" describes. For
example:
(* multstyle = "dsp" *) module foo(...); module foo(..) /* synthesis multstyle = "dsp" */;
- In the .qsf file, add as
an assignment as
follows:
set_instance_assignment -name DSP_BLOCK_BALANCING_IMPLEMENTATION \ DSP_BLOCKS -to r
In addition, for Intel® Stratix® 10, Intel® Agilex™ , Intel® Arria® 10, and Intel® Cyclone® 10 GX devices, you can enable fractal synthesis globally or for specific multipliers with the Fractal Synthesis GUI option or the corresponding FRACTAL_SYNTHESIS .qsf assignment:
- In RTL, use altera_attribute
as
follows:
(* altera_attribute = "-name FRACTAL_SYNTHESIS ON" *)
- In the .qsf file, add as
an assignment as
follows:
set_global_assignment -name FRACTAL_SYNTHESIS ON -entity <module name>
In the user interface, follow these steps:
- Click Assignments > Assignment Editor.
- Select Fractal
Synthesis for Assignment
Name, On for the
Value, the arithmetic-intensive
entity name for Entity, and an instance
name in the To column. You can enter a
wildcard (*) for To to assign all
instances of the entity.Figure 64. Fractal Synthesis Assignment in Assignment Editor
1.11. Synthesis Settings Reference
1.11.1. Advanced Synthesis Settings
Option |
Description |
---|---|
Allow Any RAM Size for Recognition |
Allows the Compiler to infer RAMs of any size, even if the RAMs do not meet the current minimum requirements. |
Allow Any ROM Size for Recognition |
Allows the Compiler to infer ROMs of any size even if the ROMs do not meet the design's current minimum size requirements. |
Allow Any Shift Register Size for Recognition |
Allows the Compiler to infer shift registers of any size even if they do not meet the design's current minimum size requirements. |
Allow Register Duplication |
Controls whether the Compiler duplicates registers to improve design performance. When enabled, the Compiler performs optimization that creates a second copy of a register and move a portion of its fan-out to this new node. This technique improves routability and reduces the total routing wire required to route a net with many fan-outs. If you disable this option, retiming of registers is also disabled. Note: Only available for
Intel®
Arria® 10 and
Intel®
Cyclone® 10 GX devices.
|
Allow Register Merging |
Controls whether the Compiler removes (merges) identical registers. When enabled, in cases where two registers generate the same logic, the Compiler may delete one register and fan-out the remaining register to the deleted register's destinations. This option is useful if you want to prevent the Compiler from removing duplicate registers that you have used deliberately. When disabled, retiming optimizations are also disabled. Note: Only available for
Intel®
Arria® 10 and
Intel®
Cyclone® 10 GX devices.
|
Allow Shift Register Merging Across Hierarchies |
Allows the Compiler to take shift registers from different hierarchies of the design and put the registers in the same RAM. |
Allow Synchronous Control Signals |
Allows the Compiler to utilize synchronous clear and synchronous load signals in normal mode logic cells. Turning on this option helps to reduce the total number of logic cells used in the design, but can negatively impact the fitting. This negative impact occurs because all the logic cells in a LAB share synchronous control signals. |
Option |
Description |
---|---|
Analysis & Synthesis Message Level |
Specifies the type of Analysis & Synthesis messages the Compiler display. Low displays only the most important Analysis & Synthesis messages. Medium displays most messages, but hides the detailed messages. High displays all messages. |
Auto Clock Enable Replacement |
Allows the Compiler to locate logic that feeds a register and move the logic to the register's clock enable input port. |
Auto DSP Block Replacement |
Allows the Compiler to find a multiply-accumulate function or a multiply-add function that can be replaced with a DSP block. |
Auto Gated Clock Conversion |
Automatically converts gated clocks to use clock enable pins. Clock gating logic can contain AND, OR, MUX, and NOT gates. Turning on this option may increase memory use and overall run time. You must use the Timing Analyzer for timing analysis, and you must define all base clocks in Synopsys Design Constraints (.sdc) format. |
Option |
Description |
---|---|
Auto Open-Drain Pins |
Allows the Compiler to automatically convert a tri-state buffer with a strong low data input into the equivalent open-drain buffer. |
Auto RAM Replacement |
Allows the Compiler to identify sets of registers and logic that it can replace with the altsyncram or the lpm_ram_dp IP core. Turning on this option may change the functionality of the design. |
Auto ROM Replacement |
Allows the Compiler to identify logic that it can replace with the altsyncram or the lpm_rom IP core. Turning on this option may change the power-up state of the design. |
Auto Resource Sharing |
Allows the Compiler to share hardware resources among many similar, but mutually exclusive, operations in your HDL source code. If you enable this option, the Compiler merges compatible addition, subtraction, and multiplication operations. Merging operations may reduce the area your design requires. Because resource sharing introduces extra muxing and control logic on each shared resource, it may negatively impact the final fMAX of your design. |
Auto Shift Register Placement |
Allows the Compiler to find a group of shift registers of the same length that are replaceable with the altshift_taps IP core. The shift registers must all use the same clock and clock enable signals. The registers must not have any other secondary signals. The registers must have equally spaced taps that are at least three registers apart. |
Automatic Parallel Synthesis |
Option to enable/disable automatic parallel synthesis. Use this option to speed up synthesis compile time by using multiple processors when available. |
Option |
Description |
---|---|
Block Design Naming |
Specifies the naming scheme for the block design. The Compiler ignores the option if you assign the option to anything other than a design entity. |
Clock MUX Protection |
Causes the multiplexers in the clock network to decompose to 2-to-1 multiplexer trees. The Compiler protects these trees from merging with, or transferring to, other logic. This option helps the Timing Analyzer to analyze clock behavior. |
DSP Block Balancing |
Allows you to control the conversion of certain DSP block slices during DSP block balancing. |
Option |
Description |
---|---|
Disable DSP Negate Inferencing |
Allows you to specify whether to use the negate port on an inferred DSP block. |
Disable Register Merging Across Hierarchies |
Specifies whether the Compiler allows merging of registers that are in different hierarchies if their inputs are the same. |
Enable Formal Verification Support | Enables the Compiler to write scripts for use with the OneSpin* formal verification tool. |
Enable State Machines Inference | Allows the Compiler to infer state machines from VHDL or Verilog HDL design files. The Compiler optimizes state machines to reduce area and improve performance. If set to Off, the Compiler extracts and optimizes state machines in VHDL or Verilog HDL design files as regular logic. |
Enable SystemVerilog static assertion support | Enables immediate assertions in the Compiler for information, warning, and error messages for SystemVerilog designs. |
Enable VHDL static assertion support | Enables immediate assertions in the Compiler for information, warning, and error messages for VHDL designs. |
Force Use of Synchronous Clear Signals |
Forces the Compiler to utilize synchronous clear signals in normal mode logic cells. Enabling this option helps to reduce the total number of logic cells in the design, but can negatively impact the fitting. All the logic cells in a LAB share synchronous control signals. |
Fractal Synthesis | Turning this option On directs the Compiler to apply dense packing to arithmetic blocks, minimizing the area of the design for arithmetic-intensive designs. |
HDL Message Level |
Specifies the type of HDL messages you want to view, including messages that display processing errors in the HDL source code. Level1 displays only the most important HDL messages. Level2 displays most HDL messages, including warning and information based messages. Level3 displays all HDL messages, including warning and information based messages and alerts about potential design problems or lint errors. |
Option |
Description |
---|---|
Ignore GLOBAL Buffers |
Ignores GLOBAL buffers in the design. The Compiler ignores this option if you apply the option to anything other than an individual GLOBAL buffer, or a design entity containing GLOBAL buffers. |
Ignore LCELL Buffers |
Ignores LCELL buffers in the design. The Compiler ignores this option if you apply the option to anything other than an individual LCELL buffer, or a design entity containing LCELL buffers. |
Ignore Maximum Fan-Out Assignments |
Directs the Compiler to ignore the Maximum Fan-Out Assignments on a node, an entity, or the whole design. |
Ignore SOFT Buffers |
Ignores SOFT buffers in the design. The Compiler ignores this option if you apply the option to anything other than an individual SOFT buffer or a design entity containing SOFT buffers. |
Option |
Description |
---|---|
Ignore translate_off and synthesis_off Directives |
Ignores all translate_off/synthesis_off synthesis directives in Verilog HDL and VHDL design files. Use this option to disable these synthesis directives and include previously ignored code during elaboration. |
Infer RAMs from Raw Logic |
Infers RAM from registers and multiplexers. The Compiler initially converts some HDL patterns differing from RAM templates into logic. However, these structures function as RAM. As a result, when you enable this option, the Compiler may substitute the altsyncram IP core instance for them at a later stage. When you enable this assignment, the Compiler may use more device RAM resources and fewer LABs. |
Iteration Limit for Constant Verilog Loops |
Defines the iteration limit for Verilog loops with loop conditions that evaluate to compile-time constants on each loop iteration. This limit exists primarily to identify potential infinite loops before they exhaust memory or trap the software in an actual infinite loop. |
Iteration Limit for non-Constant Verilog Loops |
Defines the iteration limit for Verilog HDL loops with loop conditions that do not evaluate to compile-time constants on each loop iteration. This limit exists primarily to identify potential infinite loops before they exhaust memory or trap the software in an actual infinite loop. |
Option |
Description |
---|---|
Maximum DSP Block Usage |
Specifies the maximum number of DSP blocks that the DSP block balancer assumes exist in the current device for each partition. This option overrides the usual method of using the maximum number of DSP blocks the current device supports. |
Maximum Number of LABs |
Specifies the maximum number of LABs that Analysis & Synthesis should try to utilize for a device. This option overrides the usual method of using the maximum number of LABs the current device supports, when the value is non-negative and is less than the maximum number of LABs available on the current device. |
Maximum Number of M4K/M9K/M20K/M10K Memory Blocks |
Specifies the maximum number of M4K, M9K, M20K, or M10K memory blocks that the Compiler may use for a device. This option overrides the usual method of using the maximum number of M4K, M9K, M20K, or M10K memory blocks the current device supports, when the value is non-negative and is less than the maximum number of M4K, M9K, M20K, or M10K memory blocks available on the current device. |
Option |
Description |
---|---|
Maximum Number of Registers Created from Uninferred RAMs |
Specifies the maximum number of registers that Analysis & Synthesis uses for conversion of uninferred RAMs. Use this option as a project-wide option or on a specific partition by setting the assignment on the instance name of the partition root. The assignment on a partition overrides the global assignment (if any) for that particular partition. This option prevents synthesis from causing long compilations and running out of memory when many registers are used for uninferred RAMs. Instead of continuing the compilation, the Intel® Quartus® Prime software issues an error and exits. |
NOT Gate Push-Back |
Allows the Compiler to push an inversion (that is, a NOT gate) back through a register and implement it on that register's data input if it is necessary to implement the design. When this option is on, a register may power-up to an active-high state, and may need explicit clear during initial operation of the device. The Compiler ignores this option if you apply it to anything other than an individual register or a design entity containing registers. When you apply this option to an output pin that is directly fed by a register, the assignment automatically transfers to that register. |
Number of Inverted Registers Reported in Synthesis Report |
Specifies the maximum number of inverted registers that the Synthesis report displays. |
Number of Protected Registers Reported in Synthesis Report | Specifies the maximum number of protected registers that the Synthesis Report displays. |
Number of Removed Registers Reported in Synthesis Migration Checks |
Specifies the maximum number of rows that the Synthesis Migration Check report displays. |
Number of Swept Nodes Reported in Synthesis Report | Specifies the maximum number of swept nodes that the Synthesis Report displays. A swept node is any node which was eliminated from your design because the Compiler found the node to be unnecessary. |
Number of Rows Reported in Synthesis Report |
Specifies the maximum number of rows that the Synthesis report displays. Note: Only available for
Intel®
Arria® 10 and
Intel®
Cyclone® 10 GX devices.
|
Optimization Technique |
Specifies an overall optimization goal for Analysis & Synthesis. Specify a Balanced strategy, or optimize for Performance, Area, Routability, Power, or Compile Time. The Compiler targets the optimization goal you specify. |
Option |
Description |
---|---|
Perform WYSIWYG Primitive Resynthesis |
Specifies whether to perform WYSIWYG primitive resynthesis during synthesis. This option uses the setting specified in the Optimization Technique logic option. |
Power-Up Don't Care |
Causes registers that do not have a Power-Up Level logic option setting to power-up with a do not care logic level (X). When the Power-Up Don't Care option is on, the Compiler determines when it is beneficial to change the power-up level of a register to minimize the area of the design. The Compiler maintains a power-up state of zero, unless there is an immediate area advantage. |
Power Optimization During Synthesis |
Controls the power-driven compilation setting of Analysis & Synthesis. This option determines how aggressively Analysis & Synthesis optimizes the design for power. When this option is Off, the Compiler does not perform any power optimizations. Normal compilation performs power optimizations provided that they are not expected to reduce design performance. Extra effort performs additional power optimizations which may reduce design performance. |
Option |
Description |
---|---|
Remove Duplicate Registers |
Removes a register if it is identical to another register. If two registers generate the same logic, the Compiler deletes the duplicate. The first instance fans-out to the duplicates destinations. Also, if the deleted register contains different logic option assignments, the Compiler ignores the options. This option is useful if you want to prevent the Compiler from removing intentionally duplicate registers. The Compiler ignores this option if you apply it to anything other than an individual register or a design entity containing registers. |
Remove Redundant Logic Cells |
Removes redundant LCELL primitives or WYSIWYG primitives. Turning this option on optimizes a circuit for area and speed. The Compiler ignores this option if you apply it to anything other than a design entity. |
Report Parameter Settings |
Specifies whether the Synthesis report includes the reports in the Parameter Settings by Entity Instance folder. |
Report PR Initial Values as Errors | Allows you to flag explicitly defined initial values found in PR partitions as Errors instead of Warnings. |
Report Source Assignments |
Specifies whether the Synthesis report includes reports in the Source Assignments folder. |
Option |
Description |
---|---|
Resource Aware Inference for Block RAM |
Specifies whether RAM, ROM, and shift-register inference should take the design and device resources into account. |
Restructure Multiplexers |
Reduces the number of logic elements synthesis
requires to implement multiplexers in a design. This option is useful if
your design contains buses of fragmented multiplexers. This option
repacks multiplexers more efficiently for area, allowing the design to
implement multiplexers with a reduced number of logic elements:
|
SDC Constraint Protection |
Verifies.sdc constraints in register merging. This option helps to maintain the validity of .sdc constraints through compilation. |
Safe State Machine |
The Safe State Machine option implements state machines that can recover from an illegal state. The following settings are available:
|
Shift Register Replacement – Allow Asynchronous Clear Signal |
Allows the Compiler to find a group of shift registers of the same length that can be replaced with the altshift_taps IP core. The shift registers must all use the same aclr signals, must not have any other secondary signals, and must have equally spaced taps that are at least three registers apart. To use this option, you must turn on the Auto Shift Register Replacement logic option. |
Size of the Latch Report | Allows you to specify the maximum number of latches that the Synthesis Report should display. |
Size of the PR Initial Conditions Report | Allows you to specify the maximum number of registers that the PR Initial Conditions Report should display. |
Option |
Description |
---|---|
State Machine Processing |
Specifies the processing style the Compiler uses to process a state machine. You can use your own User-Encoded style, or select One-Hot, Minimal Bits, Gray, Johnson, Sequential, or Auto (Compiler-selected) encoding. |
Strict RAM Replacement |
When this option is On, the Compiler replace RAM only if the hardware matches the design exactly. |
Synchronization Register Chain Length |
Specifies the maximum number of registers in a row that the Compiler considers as a synchronization chain. Synchronization chains are sequences of registers with the same clock and no fan-out in between, such that the first register is fed by a pin, or by logic in another clock domain. The Compiler considers these registers for metastability analysis. The Compiler prevents optimizations of these registers, such as retiming. When gate-level retiming is enabled, the Compiler does not remove these registers. The default length is set to two. |
Synthesis Effort |
Controls the synthesis trade-off between compilation speed, performance, and area. The default is Auto. You can select Fast for faster compilation speed at the cost of performance and area. |
Synthesis Migration Check for Stratix 10 | Enables synthesis checks on Intel® Arria® 10 to Intel® Stratix® 10 design migration. |
Timing-Driven Synthesis |
For Intel® Arria® 10 and Intel® Cyclone® 10 GX designs, allows synthesis to use timing information to better optimize the design. The Timing-Driven Synthesis logic option impacts the following Optimization Technique options:
|
1.12. Fitter Settings Reference
Option |
Description |
---|---|
ALM Register Packing Effort |
Guides aggressiveness of the Fitter in packing ALMs during register placement. Use this option to increase secondary register locations. Increasing ALM packing density may lower the number of ALMs needed to fit the design, but it may also reduce routing flexibility and timing performance.
|
Advanced Physical Synthesis |
Enables the Physical Synthesis engine that includes combinational and sequential optimization during fitting to improve circuit performance. |
Allow Delay Chains |
Allows the Fitter to choose the optimal delay chain to meet tSU and tCO timing requirements for all I/O elements. Enabling this option may reduce the number of tSU violations, while introducing a minimal number of tH violations. Enabling this option does not override delay chain settings on individual nodes. |
Allow DSP Retiming |
Allow retiming through DSP blocks. |
Allow Early Global Retiming in the Fitter |
Allows the Compiler to run global retiming early in the Fitter. |
Allow Hyper-Aware Register Chain Area Optimizations in the Fitter |
Reduces ALM usage by automatically forcing some back-to-back registers into Hyper Registers. Turning on this area reduction technique may reduce performance and increase compile time. |
Allow RAM Retiming |
Allow retiming through RAM blocks. |
Allow Register Duplication |
Allows the Compiler to duplicate registers to improve design performance. When you enable this option, the Compiler copies registers and moves some fan-out to this new node. This optimization improves routability and can reduce the total routing wire in nets with many fan-outs. If you disable this option, this disables optimizations that retime registers. Note: Only available for
Intel®
Arria® 10 and
Intel®
Cyclone® 10 GX devices.
|
Allow Register Merging |
Allows the Compiler to remove registers that are identical to other registers in the design. When you enable this option, in cases where two registers generate the same logic, the Compiler deletes one register, and the remaining registers fan-out to the deleted register's destinations. This option is useful if you want to prevent the Compiler from removing intentional use of duplicate registers. If you disable register merging, the Compiler disables optimizations that retime registers. Note: Only available for
Intel®
Arria® 10 and
Intel®
Cyclone® 10 GX devices.
|
Auto Delay Chains for High Fanout Input Pins |
Allows the Fitter to choose how to optimize the delay chains for high fan-out input pins. You must enable Auto Delay Chains to enable this option. Enabling this option may reduce the number of tSU violations, but the compile time increases significantly, as the Fitter tries to optimize the settings for all fan-outs. |
Auto Fit Effort Desired Slack Margin |
Specifies the default worst-case slack margin the Fitter maintains for. If the design is likely to have at least this much slack on every path, the Fitter reduces optimization effort to reduce compilation time. Note: Only available for
Intel®
Arria® 10 and
Intel®
Cyclone® 10 GX devices.
|
Option |
Description |
---|---|
Auto Global Clock |
Allows the Compiler to choose the global clock signal. The Compiler chooses the signal that feeds the most clock inputs to flip-flops. This signal is available throughout the device on the global routing paths. To prevent the Compiler from automatically selecting a particular signal as global clock, set the Global Signal option to Off on that signal. |
Auto Global Register Control Signals |
Allows the Compiler to choose global register control signals. The Compiler chooses signals that feed the most control signal inputs to flip-flops (excluding clock signals) as the global signals. These global signals are available throughout the device on the global routing paths. Depending on the target device family, these control signals can include asynchronous clear and load, synchronous clear and load, clock enable, and preset signals. If you want to prevent the Compiler from automatically selecting a particular signal as a global register control signal, set the Global Signal option to Off on that signal. |
Auto Packed Registers |
Allows the Compiler to combine a register and a combinational function, or to implement registers using I/O cells, RAM blocks, or DSP blocks instead of logic cells. This option controls how aggressively the Fitter combines registers with other function blocks to reduce the area of the design. Generally, the Auto or Sparse Auto settings are appropriate. The other settings limit the flexibility of the Fitter to combine registers with other function blocks and can result in no fits.
If this option is set to any value but Off, registers combine with I/O cells to improve I/O timing. This remains true provided that the Optimize IOC Register Placement For Timing option is enabled. |
Auto RAM to MLAB Conversion |
Specifies whether the Fitter converts RAMs of Auto block type to use LAB locations. If this option is set to Off, only MLAB cells or RAM cells with a block type setting of MLAB use LAB locations to implement memory. |
Auto Register Duplication |
Allows the Fitter to automatically duplicate registers within a LAB that contains empty logic cells. This option does not alter the functionality of the design. The Compiler ignores the Auto Register Duplication option if you select OFF as the setting for the Logic Cell Insertion -- Logic Duplication logic option. Turning on this option allows the Logic Cell Insertion -- Logic Duplication logic option to improve a design's routability, but can make formal verification of a design more difficult. Note: Only available for
Intel®
Arria® 10 and
Intel®
Cyclone® 10 GX devices.
|
Option |
Description |
---|---|
Enable Auto-Pipelining | Turns on the auto-pipelining and latency-insensitive
false path feature. Use this setting in conjunction with the Maximum Additional Pipelining and
optional Additional Pipelining
Group assignments in the Assignment Editor to
automatically add pipeline registers at the locations you specify.
Note: Only available for
Intel®
Stratix® 10 and
Intel®
Agilex™
devices.
|
Enable Bus-Hold Circuitry |
Enables bus-hold circuitry during device operation. When this option is On, a pin retains its last logic level when it is not driven, and does not go to a high impedance logic level. Do not use this option at the same time as the Weak Pull-Up Resistor designs, enables location to the Critical Chain Viewer from the Fast option. The Compiler ignores this option if you apply it to anything other than a pin. |
Enable Critical Chain Viewer |
Enables critical chain visualization in the Fast Forward Timing Closure Recommendations report for Intel® Stratix® 10 and Intel® Agilex™ devices. |
Equivalent RAM and MLAB Paused Read Capabilities |
Specifies whether RAMs implemented in MLAB cells must have equivalent paused read capabilities as RAMs implemented in block RAM. Pausing a read is the ability to keep around the last read value when reading is disabled. Allowing differences in paused read capabilities provides the Fitter more flexibility in implementing RAMs using MLAB cells. To allow the Fitter the most flexibility in deciding which RAMs are implemented using MLAB cells, set this option to Don't Care. The following options are available:
|
Equivalent RAM and MLAB Power Up |
Specifies whether RAMs implemented in MLAB cells must have equivalent power-up conditions as RAMs implemented in block RAM. Power-up conditions occur when the device powers-up or globally resets. Allowing non-equivalent power-up conditions provides the Fitter more flexibility in implementing RAMs using MLAB cells. To allow the Fitter the most flexibility in deciding which RAMs are implemented using MLAB cells, set this option to Auto or Don't Care. The following options are available:
|
Final Placement Optimizations |
Specifies whether the Fitter performs final placement optimizations. Performing final placement optimizations may improve timing and routability, but may also require longer compilation time. |
Fitter Aggressive Routability Optimizations |
Specifies whether the Fitter aggressively optimizes for routability. Performing aggressive routability optimizations may decrease design speed, but may also reduce routing wire usage and routing time. The Automatically setting allows the Fitter to decide whether aggressive routability is beneficial. |
Option |
Description |
---|---|
Fitter Effort |
Specifies the level of physical synthesis optimization during fitting:
Note: Only available for
Intel®
Arria® 10 and
Intel®
Cyclone® 10 GX devices.
|
Fitter Initial Placement Seed |
Specifies the seed for the current design. The value can be any non-negative integer value. By default, the Fitter uses a seed of 1. The Fitter uses the seed as the initial placement configuration when optimizing design placement to meet timing requirements fMAX. Because each different seed value results in a somewhat different fit, you can try several different seeds to attempt to obtain superior fitting results. The seeds that lead to the best fits for a design may change if the design changes. Also, changing the seed may or may not result in a better fit. Therefore, specify a seed only if the Fitter is not meeting timing requirements by a small amount. Note: You can also use the Design Space Explorer II
(DSEII) to sweep complex flow parameters, including the seed, in the
Intel®
Quartus® Prime software to
optimize design performance.
|
Logic Cell Insertion |
Allows the Fitter to automatically insert buffer
logic cells between two nodes without altering the functionality of
the design. The Compiler creates buffer logic cells from unused
logic cells in the device. This option also allows the Fitter to
duplicate a logic cell within a LAB when there are unused logic
cells available in a LAB. Using this option can increase compilation
time. The default setting of Auto allows these operations to run when the design
requires them to fit the
design.
Note: Only available for
Intel®
Arria® 10 and
Intel®
Cyclone® 10 GX devices.
|
MLAB Add Timing Constraints for Mixed-Port Feed-Through Mode Setting Don't Care |
Specifies whether the Timing Analyzer evaluates timing constraints between the write and the read operations of the MLAB memory block. Performing a write and read operation simultaneously at the same address might result in metastability issues because no timing constraints between those operations exist by default. Turning on this option introduces timing constraints between the write and read operations on the MLAB memory block and thereby avoids metastability issues. However, turning on this option degrades the performance of the MLAB memory blocks. If your design does not perform write and read operations simultaneously at the same address, you do not need to set this option. |
Number of Example Nodes Reported in Fitter Messages |
Allows you to specify the maximum number of example nodes Fitter messages should display. |
Option |
Description |
---|---|
Optimize Design for Metastability |
This setting improves the reliability of the design by increasing its Mean Time Between Failures (MTBF). When you enable this setting, the Fitter increases the output setup slacks of synchronizer registers in the design. This slack can exponentially increase the design MTBF. This option only applies when using the Timing Analyzer for timing-driven compilation. Use the Timing Analyzer report_metastability command to review the synchronizers detected in your design and to produce MTBF estimates. |
Optimize Hold Timing |
Directs the Fitter to optimize hold time within a device to meet timing requirements and assignments. The following settings are available:
When you disable the Optimize Timing logic option, the Optimize Hold Timing option is not available. |
Optimize IOC Register Placement for Timing |
Specifies whether the Fitter optimizes I/O pin timing by automatically packing registers into I/Os to minimize delays.
|
Optimize Multi-Corner Timing |
Directs the Fitter to consider all timing corners during optimization to meet timing requirements. These timing delay corners include both fast-corner timing and slow-corner timing. By default, this option is On, and the Fitter optimizes designs considering multi-corner delays in addition to slow-corner delays. When this option is Off, the Fitter optimizes designs considering only slow-corner delays from the slow-corner timing model (slowest manufactured device for a given speed grade, operating in low-voltage conditions). Turning this option On typically creates a more robust design implementation across process, temperature, and voltage variations. When you turn Off the Optimize Timing option, the Optimize Multi-Corner Timing option is not available. |
Optimize Timing |
Specifies whether the Fitter optimizes to meet the maximum delay timing requirements (for example, clock cycle time). By default, this option is set to Normal compilation. Turning this option Off helps fit designs that with extremely high interconnect requirements. Turning this option Off can also reduce compilation time at the expense of timing performance (because the Fitter ignores the design's timing requirements). If this option is Off, other Fitter timing optimization options have no effect (such as Optimize Hold Timing). |
Option |
Description |
---|---|
Periphery to Core Placement and Routing Optimization |
Specifies whether the Fitter should perform targeted placement and routing optimization on direct connections between periphery logic and registers in the FPGA core. The following options are available:
Note: Only available for
Intel®
Arria® 10 and
Intel®
Cyclone® 10 GX devices.
|
Physical Placement Effort |
Controls how much effort the Fitter spends during advanced physical placement optimization. High and Maximum effort settings result in additional compile time to further optimization the placement solution. |
Placement Effort Multiplier |
Specifies the relative time the Fitter spends in placement. The default value is 1.0, and legal values must be greater than 0. Specifying a floating-point number allows you to control the placement effort. A higher value increases CPU time but may improve placement quality. For example, a value of '4' increases fitting time by approximately 2 to 4 times but may increase quality. |
Power Optimization During Fitting |
Directs the Fitter to perform optimizations targeted at reducing the total power devices consume. The available settings for power-optimized fitting are:
|
Option |
Description |
---|---|
Programmable Power Maximum High-Speed Fraction of Used LAB Tiles |
Sets the upper limit on the fraction of the high-speed LAB tiles. Legal values must be between 0.0 and 1.0. The default value is 1.0. A value of 1.0 means that there is no restriction on the number of high-speed tiles, and the Fitter uses the minimum number needed to meet the timing requirements of your design. Specifying a value lower than 1.0 might degrade timing quality, because some timing critical resources might be forced into low-power mode. |
Programmable Power Technology Optimization |
Controls how the Fitter configures tiles to operate in high-speed mode or low-power mode. The following options are available:
For designs that fail timing, all paths with negative slack are put in high-speed mode. This mode likely does not increase the speed of the design, and it may increase static power consumption. This mode may assist in determining which logic paths need to be re-designed to close timing. Note: Only available for
Intel®
Arria® 10 and
Intel®
Cyclone® 10 GX devices.
|
Router Timing Optimization Level |
Controls how aggressively the router tries to meet timing requirements. Setting this option to Maximum can increase design speed slightly, at the cost of increased compile time. Setting this option to Minimum can reduce compile time, at the cost of slightly reduced design speed. The default value is Normal. |
Run Early Place during compilation |
Enables the Early Place Fitter stage during full compilation. Turning on this setting may increase Fitter processing time. |
Option |
Description |
---|---|
Synchronizer Identification |
Specifies how the Compiler identifies synchronization register chain registers for metastability analysis. A synchronization register chain is a sequence of registers with the same clock with no fan-out in between, which is driven by a pin or logic from another clock domain. The following options are available:
The Fitter optimizes the registers that it identifies as synchronizers for improved Mean Time Between Failure (MTBF), provided that you enable Optimize Design for Metastability. If a synchronization register chain is identified with the Forced or Forced if Asynchronous option, then the Timing Analyzer reports the metastability MTBF for the chain when it meets the design timing requirements. |
Treat Bidirectional Pin as Output Pin |
Specifies that the Fitter treats the bidirectional pin as an output pin, meaning that the input path feeds back from the output path. |
Use Checkered Pattern as uninitialized RAM Content |
Loads a checkered pattern as initial RAM content into all RAM blocks without specified RAM content that supports content initialization. Turning on this option does not affect simulation, which may cause on-chip behavior to differ from simulation results. |
Weak Pull-Up Resistor |
Enables the weak pull-up resistor when the device is operating in user mode. This option pulls a high-impedance bus signal to VCC. Do not enable this option simultaneously with the Enable Bus-Hold Circuitry option. The Fitter ignores this option if you apply to anything other than a pin. |
Other Assignments
set_global_assignment –name ERROR_ON_INVALID_ENTITY_NAME:The software ignores .qsf and .qip assignments where the entity field is not a name that exists in the design and generates a warning. If you set ERROR_ON_INVALID_ENTITY_NAME to ON, the software generates these warnings as errors.
1.13. Design Compilation Revision History
Document Version | Intel® Quartus® Prime Version | Changes |
---|---|---|
2021.03.29 | 21.1 |
|
2020.12.14 | 20.3 |
|
2020.11.09 | 20.3 |
|
2020.09.28 | 20.3 |
|
2020.05.08 | 20.1 |
|
2020.04.13 | 20.1 |
|
2019.10.20 | 19.3 |
|
2019.09.30 | 19.3 |
|
2019.07.02 | 19.1 |
|
2019.04.01 | 19.1 |
|
2019.01.03 | 18.1.0 |
|
2018.10.19 | 18.1 |
|
2018.09.24 | 18.1 |
|
2018.05.07 | 18.0 |
|
Date |
Version |
Changes |
---|---|---|
2017.11.06 | 17.1.0 |
|
2017.05.08 | 17.0.0 |
|
2016.10.31 | 16.1.0 |
|
2016.05.03 | 16.0.0 |
|
2015.11.02 | 15.1.0 |
|
2. Reducing Compilation Time
2.1. Factors Affecting Compilation Results
- Project Files—changes to project settings (.qsf, quartus2.ini), design files, and timing constraints (.sdc) can change the results.
- Any setting that changes the number of processors during compilation can impact compilation results.
- Hardware—CPU architecture, not including hard disk or memory size differences. Windows XP x32 results are not identical to Windows XP x64 results. Linux x86 results is not identical to Linux x86_64.
- Intel® Quartus® Prime Software Version—including build number and installed interim updates. Click Help > About to obtain this information.
- Operating System—Windows or Linux operating system, excluding version updates. For example, Windows XP, Windows Vista, and Windows 7 results are identical. Similarly, Linux RHEL, CentOS 4, and CentOS 5 results are identical.
2.2. Compilation Time Advisor
2.3. Strategies to Reduce the Overall Compilation Time
2.3.1. Running the ECO Compilation Flow
The Intel® Quartus® Prime Pro Edition software supports last-minute, targeted design changes (also known as engineering change orders (ECOs)), even after you fully compile the design. ECOs typically occur during the design verification stage. Refer to the Intel® Quartus® Prime Pro Edition User Guide: Design Optimization for details.
2.3.2. Enabling Multi-Processor Compilation
This technique reduces the compilation time by up to 10% on systems with two processing cores, and by up to 20% on systems with four cores. When running timing analysis independently, two processors reduce the timing analysis time by an average of 10%. This reduction reaches an average of 15% when using four processors.
The Intel® Quartus® Prime software does not necessarily use all the processors that you specify during a given compilation. Additionally, the software never uses more than the specified number of processors. This fact enables you to work on other tasks without slowing down your computer. The use of multiple processors does not affect the quality of the fit. For a given Fitter seed, and given Maximum processors allowed setting on a specific design, the fit is exactly the same and deterministic. This remains true, regardless of the target machine, and the number of available processors. Different Maximum processors allowed specifications produce different results of the same quality. The impact is similar to changing the Fitter seed setting.
To enable multiprocessor compilation, follow these steps:
- Open or create an Intel® Quartus® Prime project.
- Click Assignments > Settings > Compilation Process Settings.
- Under Parallel compilation, specify options for the number of processors the Compiler uses.
-
View detailed information about processor use in the Parallel
Compilation report following compilation.
To specify the number of processors for compilation at the command line, use the following Tcl command in your script:
set_global_assignment -name NUM_PARALLEL_PROCESSORS <value>
In this case, <value> is an integer from 1 to 16.
If you want the Intel® Quartus® Prime software to detect the number of processors and use all the processors for the compilation, include the following Tcl command in your script:
set_global_assignment -name NUM_PARALLEL_PROCESSORS ALL
Note: The Compiler detects Intel® Hyper-Threading® Technology (Intel® HT Technology) as a single processor. If your system includes a single processor with Intel HT Technology, set the number of processors to one. Do not use the Intel® HT Technology for Intel® Quartus® Prime compilations.
2.3.3. Using Block-Based Compilation
When using block-based compilation, you can enable the Fast Preserve option to reduce the logic of preserved partitions to only interface logic during compilation, thereby reducing the time the Compiler requires to synthesize, place, and route the partition. Interface logic is logic at the partition boundary that interfaces with the rest of the design.
-
In the Design Partition Planner, identify blocks of a size
suitable for partitioning.
In general, a partition represents roughly 15 to 20 percent of the total design size. Use the information area below the bar at the top of each entity.Figure 65. Entity representation in the Design Partition Planner
- Extract and collapse entities as necessary to achieve stand-alone blocks
-
For each entity of the desired size containing related blocks
of logic, right-click the entity and click Create
Design Partition to place that entity in its own
partition.
The goal is to achieve partitions containing related blocks of logic.
- To enable the Fast Preserve option that simplifies the logic of the preserved partition to only interface logic during compilation, click Assignments > Settings > Compiler Settings > Incremental Compile > Fast Preserve.
2.3.4. Disabling the Register Power-up Initialization
- This option is available only for Intel® Stratix® 10 and Intel® Agilex™ devices.
- Optimizations that rely on power-up states are disabled.
- Bitstream assembler creates bitstreams without the register power-up initialization.
To disable the initialization, enable the Disable Register Power-up Initialization option through the Device and Pin Options dialog.

When you enable the Disable Register Power-up Initialization option, Synthesis prints a warning for registers with power-up care, as shown in the following image:

To view registers with defined power-up states that the Compiler cannot preserve, refer to the Registers with Explicit Power-up Settings report,

For more information about the reset strategy required when you no longer can rely on registers' power-up states to reset the designs, refer to Partial Reconfiguration Design Flow in Intel® Quartus® Prime Pro Edition User Guide: Partial Reconfiguration.
2.4. Reducing Synthesis Time and Synthesis Netlist Optimization Time
2.4.1. Settings to Reduce Synthesis Time and Synthesis Netlist Optimization Time
If your design already meets performance requirements without synthesis netlist or physical synthesis optimizations, turn off these options to reduce compilation time. If you require synthesis netlist optimizations to meet performance, optimize partitions of your design hierarchy separately to reduce the overall time spent in Analysis and Synthesis.
2.4.2. Use Appropriate Coding Style to Reduce Synthesis Time
If you are trying to infer a large memory block, the software consumes more resources in the FPGA. This can cause routing congestion and increasing compilation time significantly. If you see high routing utilizations in certain blocks, it is a good idea to review the code for such blocks.
2.5. Reducing Placement Time
You can reduce the placement time by changing the settings for the placement algorithm.
Sometimes there is a trade-off between placement time and routing time. Routing time can increase if the placer does not run long enough to find a good placement. When you reduce placement time, ensure that it does not increase routing time and negate the overall time reduction.
2.5.1. Placement Effort Multiplier Settings
Click Assignments > Settings > Compiler Settings > Advanced Settings (Fitter) and specify a value for Placement Effort Multiplier. The default is 1.0. Legal values must be greater than 0 and can be non-integer values. Numbers between 0 and 1 can reduce fitting time, but also can reduce placement quality and design performance.
2.6. Reducing Routing Time
If your design requires a long time to route, perform one or more of the following actions:
- Check for routing congestion.
- Turn off Fitter Aggressive Routability Optimization.
2.6.1. Identifying Routing Congestion with the Chip Planner
- Click Tools > Chip Planner.
- To view the routing congestion in the Chip Planner, double-click the Report Routing Utilization command in the Tasks list.
- Click Preview in the Report Routing Utilization dialog box to preview the default congestion display.
- Change the Routing utilization type to display congestion for specific resources. The default display uses dark blue for 0% congestion and red for 100%.
- Adjust the slider for Threshold percentage to change the congestion threshold level.
2.6.1.1. Areas with Routing Congestion
- You can change the connections in your design to reduce routing congestion
- If the area with routing congestion is in a Logic Lock (Standard) region or between Logic Lock (Standard) regions, change or remove the Logic Lock (Standard) regions and recompile your design.
- If the routing time remains the same, the time is a characteristic of your design and the placement
- If the routing time decreases, consider changing the size, location, or contents of Logic Lock (Standard) regions to reduce congestion and decrease routing time.
2.6.1.2. Congestion due to HDL Coding style
2.7. Reducing Static Timing Analysis Time
The Intel® Quartus® Prime Fitter also runs the Timing Analyzer during placement and routing. If there are incorrect constraints in the Synopsys* Design Constraints File (.sdc), the Intel® Quartus® Prime software may spend unnecessary time processing constraints several times.
- If you do not specify false paths and multicycle paths in your design, the Timing Analyzer may analyze paths that are not relevant to your design.
- If you redefine constraints in the .sdc files, the Timing Analyzer may spend additional time processing them. To avoid this situation, look for indications that Synopsis design constraints are being redefined in the compilation messages, and update the .sdc file.
- Ensure that you provide the correct timing constraints to your design, because the software cannot assume design intent, such as which paths to consider as false paths or multicycle paths. When you specify these assignments correctly, the Timing Analyzer skips analysis for those paths, and the Fitter does not spend additional time optimizing those paths.
2.8. Setting Process Priority
2.9. Reducing Compilation Time Revision History
Document Version | Intel® Quartus® Prime Version | Changes |
---|---|---|
2021.03.29 | 21.1 |
|
2020.09.28 | 20.3 |
|
2019.11.11 | 19.3 |
|
2019.09.30 | 19.3 |
|
2019.07.02 | 19.1 | Added the Using the No-Register Initialization Flow topic. |
2018.10.19 | 18.1 |
|
2017.11.06 | 17.1 |
|
Date | Version | Changes |
---|---|---|
2017.05.08 | 17.0.0 |
|
2016.10.31 | 16.1.0 |
|
2016.05.02 | 16.0.0 |
|
2015.11.02 | 15.1.0 | Changed instances of Quartus II to Intel® Quartus® Prime . |
2014.12.15 | 14.1.0 |
|
2014.08.18 |
14.0a10.0 |
Added restriction about smart compilation in Arria 10 devices. |
June 2014 | 14.0.0 | Updated format. |
May 2013 | 13.0.0 | Removed the “Limit to
One Fitting Attempt”, “Using Early Timing Estimation”, “Final Placement
Optimizations”, and “Using Rapid Recompile” sections.
Updated “Placement Effort Multiplier Settings” section. Updated “Identifying Routing Congestion in the Chip Planner” section. General editorial changes throughout the chapter. |
June 2012 | 12.0.0 | Removed survey link. |
November 2011 | 11.0.1 | Template update. |
May 2011 | 11.0.0 |
|
December 2010 | 10.1.0 |
|
July 2010 | 10.0.0 | Initial release. |
3. Intel Quartus Prime Pro Edition User Guide Design Compilation Archives
Intel® Quartus® Prime Version | User Guide |
---|---|
20.3 | Intel® Quartus® Prime Pro Edition User Guide Design Compilation |
20.1 | Intel® Quartus® Prime Pro Edition User Guide Design Compilation |
19.4 | Intel® Quartus® Prime Pro Edition User Guide Design Compilation |
19.3 | Intel® Quartus® Prime Pro Edition User Guide Design Compilation |
19.1 | Intel® Quartus® Prime Pro Edition User Guide Design Compilation |
18.1 | Intel® Quartus® Prime Pro Edition User Guide Design Compilation |
18.0 | Compiler User Guide Intel® Quartus® Prime Pro Edition |
A. Intel Quartus Prime Pro Edition User Guides
Refer to the following user guides for comprehensive information on all phases of the Intel® Quartus® Prime Pro Edition FPGA design flow.