Quartus® Prime Pro Edition User Guide: Design Optimization

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Date 4/01/2024
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Document Table of Contents
Document Table of Contents x
Answers to Top FAQs 1. Design Optimization Overview 2. Optimizing the Design Netlist 3. Netlist Optimizations and Physical Synthesis 4. Area Optimization 5. Timing Closure and Optimization 6. Analyzing and Optimizing the Design Floorplan 7. Using the ECO Compilation Flow 8. Quartus® Prime Pro Edition Design Optimization User Guide Archives A. Quartus® Prime Pro Edition User Guides
1. Design Optimization Overview x
1.1. Initial FPGA Device Considerations 1.2. Initial Compiler Settings 1.3. Optimization Trade-Offs and Limitations 1.4. Design Visualization and Optimization Tools 1.5. Design Optimization Overview Revision History
1.1. Initial FPGA Device Considerations x
1.1.1. Device Migration Considerations
1.2. Initial Compiler Settings x
1.2.1. Initial I/O Assignment Guidelines 1.2.2. Initial Timing Constraint Guidelines
1.3. Optimization Trade-Offs and Limitations x
1.3.1. Area Reduction Trade-Offs 1.3.2. Critical Path Delay Reduction Trade-Offs 1.3.3. Power Consumption Reduction Trade-Offs 1.3.4. Compilation Time Trade-Offs
1.4. Design Visualization and Optimization Tools x
1.4.1. Design Visualization Tools 1.4.2. Design Optimization Tools
2. Optimizing the Design Netlist x
2.1. When to Use the Netlist Viewers: Analyzing Design Problems 2.2. Quartus® Prime Design Flow with the Netlist Viewers 2.3. RTL Viewer Overview 2.4. Technology Map Viewer Overview 2.5. Netlist Viewer User Interface 2.6. Schematic View 2.7. Cross-Probing to a Source Design File and Other Quartus® Prime Windows 2.8. Cross-Probing to the Netlist Viewers from Other Quartus® Prime Windows 2.9. Viewing a Timing Path 2.10. Optimizing the Design Netlist Revision History
2.3. RTL Viewer Overview x
2.3.1. Maximizing Readability in RTL Viewer 2.3.2. Running the RTL Viewer
2.5. Netlist Viewer User Interface x
2.5.1. Netlist Navigator Pane 2.5.2. Properties Pane 2.5.3. Netlist Viewers Find Pane
2.6. Schematic View x
2.6.1. Display Schematics in Multiple Tabbed View 2.6.2. Schematic Symbols 2.6.3. Select Items in the Schematic View 2.6.4. Shortcut Menu Commands in the Schematic View 2.6.5. Filtering in the Schematic View 2.6.6. View Contents of Nodes in the Schematic View 2.6.7. Moving Nodes in the Schematic View 2.6.8. View LUT Representations in the Technology Map Viewer 2.6.9. Zoom Controls 2.6.10. Navigating with the Bird's Eye View 2.6.11. Partition the Schematic into Pages 2.6.12. Follow Nets Across Schematic Pages
3. Netlist Optimizations and Physical Synthesis x
3.1. Physical Synthesis Optimizations 3.2. Applying Netlist Optimizations 3.3. Scripting Support 3.4. Netlist Optimizations and Physical Synthesis Revision History
3.1. Physical Synthesis Optimizations x
3.1.1. Disabling or Enabling Physical Synthesis Optimization 3.1.2. Physical Synthesis Options
3.2. Applying Netlist Optimizations x
3.2.1. WYSIWYG Primitive Resynthesis
3.3. Scripting Support x
3.3.1. Synthesis Netlist Optimizations 3.3.2. Physical Synthesis Optimizations
4. Area Optimization x
4.1. Resource Utilization Information 4.2. Optimizing Resource Utilization 4.3. Scripting Support 4.4. Area Optimization Revision History
4.1. Resource Utilization Information x
4.1.1. Flow Summary Report 4.1.2. Fitter Reports 4.1.3. Design Assistant Recommendations 4.1.4. Analysis and Synthesis Reports 4.1.5. Compilation Messages 4.1.6. Chip Planner Visualization
4.1.2. Fitter Reports x
4.1.2.1. Route Stage Reports
4.1.2.1. Route Stage Reports x
4.1.2.1.1. Nets with Highest Wire Count Report 4.1.2.1.2. Delay Chain Summary Report 4.1.2.1.3. Top Congested Hierarchies and Nets Reports 4.1.2.1.4. Global Route Reports
4.2. Optimizing Resource Utilization x
4.2.1. Resource Utilization Issues Overview 4.2.2. I/O Pin Utilization or Placement 4.2.3. Logic Utilization or Placement 4.2.4. Routing
4.2.2. I/O Pin Utilization or Placement x
4.2.2.1. Guideline: Modify Pin Assignments or Choose a Larger Package
4.2.3. Logic Utilization or Placement x
4.2.3.1. Guideline: Optimize Source Code 4.2.3.2. Guideline: Optimize Synthesis for Area, Not Speed 4.2.3.3. Guideline: Restructure Multiplexers 4.2.3.4. Guideline: Perform WYSIWYG Primitive Resynthesis with Balanced or Area Setting 4.2.3.5. Guideline: Use Register Packing 4.2.3.6. Guideline: Remove Fitter Constraints 4.2.3.7. Guideline: Flatten the Hierarchy During Synthesis 4.2.3.8. Guideline: Re-target Memory Blocks 4.2.3.9. Guideline: Use Physical Synthesis Options to Reduce Area 4.2.3.10. Guideline: Retarget or Balance DSP Blocks 4.2.3.11. Guideline: Use a Larger Device 4.2.3.12. Guideline: Reduce Global Signal Congestion 4.2.3.13. Guideline: Report Pipelining Information
4.2.4. Routing x
4.2.4.1. Guideline: Set Auto Packed Registers to Sparse or Sparse Auto 4.2.4.2. Guideline: Set Fitter Aggressive Routability Optimizations to Always 4.2.4.3. Guideline: Increase Router Effort Multiplier 4.2.4.4. Guideline: Remove Fitter Constraints 4.2.4.5. Guideline: Optimize Synthesis for Routability 4.2.4.6. Guideline: Optimize Source Code 4.2.4.7. Guideline: Use a Larger Device
4.3. Scripting Support x
4.3.1. Initial Compilation Settings 4.3.2. Resource Utilization Optimization Techniques
5. Timing Closure and Optimization x
5.1. Optimize Multi Corner Timing 5.2. Optimize Critical Paths 5.3. Optimize Critical Chains 5.4. Design Evaluation for Timing Closure 5.5. Timing Optimization 5.6. Periphery to Core Register Placement and Routing Optimization 5.7. Scripting Support 5.8. Timing Closure and Optimization Revision History
5.2. Optimize Critical Paths x
5.2.1. Viewing Critical Paths
5.3. Optimize Critical Chains x
5.3.1. Viewing Critical Chains
5.4. Design Evaluation for Timing Closure x
5.4.1. Review Messages 5.4.2. Evaluate Fitter Netlist Optimizations 5.4.3. Evaluate Optimization Results 5.4.4. Evaluate Resource Usage 5.4.5. Evaluate Other Reports and Adjust Settings Accordingly 5.4.6. Evaluate Clustering Difficulty 5.4.7. Revise and Recompile
5.4.4. Evaluate Resource Usage x
5.4.4.1. Evaluate Global and Non-Global Usage 5.4.4.2. Evaluate Routing Usage 5.4.4.3. Evaluate Wires Added for Hold
5.5. Timing Optimization x
5.5.1. Correct Design Assistant Rule Violations 5.5.2. Implement Fast Forward Timing Closure Recommendations 5.5.3. Review Timing Path Details 5.5.4. Try Optional Fitter Settings 5.5.5. Back-Annotating Optimized Assignments 5.5.6. Optimize Settings with Design Space Explorer II 5.5.7. Aggregating and Comparing Compilation Results with Exploration Dashboard 5.5.8. I/O Timing Optimization Techniques 5.5.9. Register-to-Register Timing Optimization Techniques 5.5.10. Metastability Analysis and Optimization Techniques
5.5.2. Implement Fast Forward Timing Closure Recommendations x
5.5.2.1. Retiming Limit Details Report 5.5.2.2. Fast Forward Timing Closure Recommendations
5.5.2.1. Retiming Limit Details Report x
5.5.2.1.1. Using the Retiming Limit Details Report
5.5.2.2. Fast Forward Timing Closure Recommendations x
5.5.2.2.1. Generating Fast Forward Timing Closure Recommendations 5.5.2.2.2. Implementing Fast Forward Recommendations
5.5.3. Review Timing Path Details x
5.5.3.1. Report Timing 5.5.3.2. Report Logic Depth 5.5.3.3. Report Neighbor Paths 5.5.3.4. Report Register Spread 5.5.3.5. Report Route Net of Interest 5.5.3.6. Report Retiming Restrictions 5.5.3.7. Report Pipelining Information 5.5.3.8. Report CDC Viewer 5.5.3.9. Timing Closure Recommendations 5.5.3.10. Global Network Buffers 5.5.3.11. Resets and Global Networks 5.5.3.12. Suspicious Setup 5.5.3.13. Auto Shift Register Replacement 5.5.3.14. Clocking Architecture
5.5.3.10. Global Network Buffers x
5.5.3.10.1. Source Location 5.5.3.10.2. Insertion Delay 5.5.3.10.3. Fan-Out 5.5.3.10.4. Global Signal Assignment
5.5.4. Try Optional Fitter Settings x
5.5.4.1. Optimize Hold Timing 5.5.4.2. Fitter Aggressive Routability Optimization
5.5.6. Optimize Settings with Design Space Explorer II x
5.5.6.1. DSE II Computing Resources 5.5.6.2. DSE II Optimization Parameters 5.5.6.3. DSE II Result Management 5.5.6.4. Running DSE II
5.5.7. Aggregating and Comparing Compilation Results with Exploration Dashboard x
5.5.7.1. Aggregation Use Case 5.5.7.2. Comparison Use Case 5.5.7.3. Exploration Dashboard Object-Property Model 5.5.7.4. Starting the Exploration Dashboard
5.5.7.3. Exploration Dashboard Object-Property Model x
5.5.7.3.1. Base Exploration Dashboard Properties 5.5.7.3.2. Project Handle Properties 5.5.7.3.3. Project Group Objects and Properties 5.5.7.3.4. Workspace Objects and Properties
5.5.8. I/O Timing Optimization Techniques x
5.5.8.1. I/O Timing Constraints 5.5.8.2. Optimize IOC Register Placement for Timing Logic Option 5.5.8.3. Fast Input, Output, and Output Enable Registers 5.5.8.4. Programmable Delays 5.5.8.5. Use PLLs to Shift Clock Edges 5.5.8.6. Use Fast Regional Clock Networks and Regional Clocks Networks 5.5.8.7. Spine Clock Limitations
5.5.9. Register-to-Register Timing Optimization Techniques x
5.5.9.1. Optimize Source Code 5.5.9.2. Improving Register-to-Register Timing 5.5.9.3. Physical Synthesis Optimizations 5.5.9.4. Set Power Optimization During Synthesis to Normal Compilation 5.5.9.5. Optimize Synthesis for Performance, Not Area 5.5.9.6. Flatten the Hierarchy During Synthesis 5.5.9.7. Set the Synthesis Effort to High 5.5.9.8. Change Adder Tree Styles 5.5.9.9. Duplicate Registers for Fan-Out Control 5.5.9.10. Prevent Shift Register Inference 5.5.9.11. Use Other Synthesis Options Available in Your Synthesis Tool 5.5.9.12. Fitter Seed 5.5.9.13. Set Maximum Router Timing Optimization Level 5.5.9.14. Register-to-Register Timing Analysis
5.5.9.9. Duplicate Registers for Fan-Out Control x
5.5.9.9.1. Manual Register Duplication 5.5.9.9.2. Automatic Register Duplication: Estimated Physical Proximity 5.5.9.9.3. Automatic Register Duplication: Hierarchical Proximity
5.5.9.14. Register-to-Register Timing Analysis x
5.5.9.14.1. Tips for Analyzing Failing Paths 5.5.9.14.2. Tips for Analyzing Failing Clock Paths that Cross Clock Domains 5.5.9.14.3. Tips for Critical Path Analysis 5.5.9.14.4. Tips for Creating a .tcl Script to Monitor Critical Paths Across Compiles 5.5.9.14.5. Global Routing Resources 5.5.9.14.6. Register RAMS and DSPs
5.6. Periphery to Core Register Placement and Routing Optimization x
5.6.1. Setting Periphery to Core Optimizations in the Advanced Fitter Setting Dialog Box 5.6.2. Setting Periphery to Core Optimizations in the Assignment Editor 5.6.3. Viewing Periphery to Core Optimizations in the Fitter Report
5.7. Scripting Support x
5.7.1. Initial Compilation Settings 5.7.2. I/O Timing Optimization Techniques 5.7.3. Register-to-Register Timing Optimization Techniques
6. Analyzing and Optimizing the Design Floorplan x
6.1. Location Assignment Optimization Guidelines 6.2. Design Floorplan Analysis in Chip Planner 6.3. Defining Logic Lock Placement Constraints 6.4. Defining Virtual Pins 6.5. Using Logic Lock Regions in Combination with Design Partitions 6.6. Creating Clock Region Assignments in Chip Planner 6.7. Scripting Support 6.8. Analyzing and Optimizing the Design Floorplan Revision History
6.2. Design Floorplan Analysis in Chip Planner x
6.2.1. Starting the Chip Planner 6.2.2. Chip Planner GUI 6.2.3. Viewing Design Elements in Chip Planner 6.2.4. Finding Design Elements in the Chip Planner 6.2.5. Exploring Paths in the Chip Planner 6.2.6. Viewing Assignments in the Chip Planner 6.2.7. Viewing High-Speed and Low-Power Tiles in the Chip Planner 6.2.8. Viewing Design Partition Placement
6.2.3. Viewing Design Elements in Chip Planner x
6.2.3.1. Viewing Architecture-Specific Design Information in Chip Planner 6.2.3.2. Viewing Available Clock Networks in Chip Planner 6.2.3.3. Viewing Clock Sector Utilization in Chip Planner 6.2.3.4. Viewing Routing Congestion in Chip Planner 6.2.3.5. Viewing I/O Banks in Chip Planner 6.2.3.6. Viewing High-Speed Serial Interfaces (HSSI) in Chip Planner 6.2.3.7. Viewing Source and Destination Nodes in Chip Planner 6.2.3.8. Viewing Fan-In and Fan-Out in Chip Planner 6.2.3.9. Viewing Immediate Fan-In and Fan-Out in Chip Planner 6.2.3.10. Viewing the Selected Contents in Chip Planner 6.2.3.11. Viewing the Location and Utilization of Device Resources in Chip Planner 6.2.3.12. Viewing Module Placement by Cross-Probing to Chip Planner
6.2.4. Finding Design Elements in the Chip Planner x
6.2.4.1. Find Options (Chip Planner Search)
6.2.5. Exploring Paths in the Chip Planner x
6.2.5.1. Analyzing Connections for a Path 6.2.5.2. Locate Path from the Timing Analysis Report to the Chip Planner 6.2.5.3. Show Delays 6.2.5.4. Viewing Routing Resources
6.3. Defining Logic Lock Placement Constraints x
6.3.1. The Logic Lock Regions Window 6.3.2. Defining Logic Lock Regions 6.3.3. Customizing the Shape of Logic Lock Regions 6.3.4. Assigning Device Pins to Logic Lock Regions 6.3.5. Viewing Connections Between Logic Lock Regions in Chip Planner 6.3.6. Example: Placement Best Practices for Arria® 10 FPGAs 6.3.7. Migrating Assignments between Quartus® Prime Standard Edition and Quartus® Prime Pro Edition
6.3.2. Defining Logic Lock Regions x
6.3.2.1. Defining a Logic Lock Region in Chip Planner 6.3.2.2. Defining a Logic Lock Region from the Project Navigator 6.3.2.3. Defining Routing Regions 6.3.2.4. Defining Empty Logic Lock Regions 6.3.2.5. Defining Hierarchical Logic Lock Regions
6.3.2.1. Defining a Logic Lock Region in Chip Planner x
6.3.2.1.1. Logic Lock Region Properties 6.3.2.1.2. Snapping to a Region 6.3.2.1.3. Considerations for Auto Sized Regions
6.3.3. Customizing the Shape of Logic Lock Regions x
6.3.3.1. Adding a New Shape to a Logic Lock Region 6.3.3.2. Subtracting Shape from Logic Lock Region 6.3.3.3. Merging Logic Lock Regions 6.3.3.4. Defining Noncontiguous Logic Lock Regions
6.5. Using Logic Lock Regions in Combination with Design Partitions x
6.5.1. Viewing Design Connectivity and Hierarchy
6.6. Creating Clock Region Assignments in Chip Planner x
6.6.1. Creating Clock Assignments in Chip Planner 6.6.2. Resizing a Clock Assignment in Chip Planner 6.6.3. Moving a Clock Assignment in Chip Planner 6.6.4. Deleting a Clock Region Assignment in Chip Planner 6.6.5. Assigning a Clock Signal to a Clock Region in Chip Planner
6.6.1. Creating Clock Assignments in Chip Planner x
6.6.1.1. Clock Assignment Properties
6.7. Scripting Support x
6.7.1. Creating Logic Lock Assignments with Tcl commands 6.7.2. Assigning Virtual Pins with a Tcl command 6.7.3. Logic Lock Region Assignment Examples
7. Using the ECO Compilation Flow x
7.1. ECO Compilation Flow 7.2. ECO Tcl Script Example 7.3. Viewing ECO Compilation Reports 7.4. ECO Commands 7.5. ECO Command Limitations 7.6. Interactive ECO Fitting 7.7. Using the ECO Compilation Flow Revision History
7.4. ECO Commands x
7.4.1. ECO Command Quick Reference 7.4.2. make_connection 7.4.3. remove_connection 7.4.4. modify_lutmask 7.4.5. adjust_pll_refclk 7.4.6. modify_io_slew_rate 7.4.7. modify_io_current_strength 7.4.8. modify_io_delay_chain 7.4.9. create_new_node 7.4.10. remove_node 7.4.11. place_node 7.4.12. unplace_node 7.4.13. create_wirelut
7.6. Interactive ECO Fitting x
7.6.1. eco_load_design and eco_commit_design Commands
Answers to Top FAQs
1. Design Optimization Overview
2. Optimizing the Design Netlist
3. Netlist Optimizations and Physical Synthesis
4. Area Optimization
5. Timing Closure and Optimization
6. Analyzing and Optimizing the Design Floorplan
7. Using the ECO Compilation Flow
8. Quartus® Prime Pro Edition Design Optimization User Guide Archives
A. Quartus® Prime Pro Edition User Guides

6.4. Defining Virtual Pins

A virtual pin is an I/O element that the Compiler temporarily maps to a logic element, rather than to a pin. The Compiler implements these virtual pins as LUTs.

By making assignments to virtual pins, you can ensure that the Fitter places those pins in the same device region as the corresponding internal nodes in the top-level module. You can apply the Virtual Pin option to successfully compile a Logic Lock module that has more pins than the target device. The Virtual Pin option can enable timing analysis of a design module that more closely matches the performance of the module after you integrate it into the top-level design.

You can create and assign virtual pins to an I/O element using the Virtual Pin logic option in the Assignment Editor (Assignments > Assignment Editor).

Figure 127.  Virtual Pin Logic Option in the Assignment Editor


When you apply the Virtual Pin assignment to an input pin, the pin no longer appears as an FPGA pin. Rather, the Compiler fixes the virtual pin to GND in the design. The virtual pin is not a floating node.

Use virtual pins only for I/O elements in lower-level design entities that become nodes after you import the entity to the top-level design; for example, when compiling a partial design. In the top-level design, you connect these virtual pins to an internal node of another module

Note: You must assign the Virtual Pin logic option to an input or output pin. If you assign this option to a bidirectional pin, tri-state pin, or registered I/O element, synthesis ignores the assignment. If you assign this option to a tri-state pin, the Fitter inserts an I/O buffer to account for the tri-state logic; therefore, the pin cannot be a virtual pin. You can use multiplexer logic instead of a tri-state pin if you want to continue to use the assigned pin as a virtual pin. Do not use tri-state logic except for signals that connect directly to device I/O pins.

To display all assigned virtual pins in the design with the Node Finder, you can set Filter Type to Pins: Virtual. To access the Node Finder from the Assignment Editor, double-click the To field; when the arrow appears on the right side of the field, click and select Node Finder.

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