Verification Academy

Search form

My Account Menu

  • Register
  • Log In
  • Topics
  • Courses
  • Forums
  • Patterns Library
  • Cookbooks
  • Events
  • More
  • All Topics
    The Verification Academy offers users multiple entry points to find the information they need. One of these entry points is through Topic collections. These topics are industry standards that all design and verification engineers should recognize. While we continue to add new topics, users are encourage to further refine collection information to meet their specific interests.

    • Languages & Standards

      • Portable Test and Stimulus
      • Functional Safety
      • Design & Verification Languages

    • Methodologies

      • UVM - Universal Verification Methodology
      • UVM Framework
      • UVM Connect
      • FPGA Verification
      • Coverage

    • Techniques & Tools

      • Verification IQ
      • Verification IP
      • Static-Based Techniques
      • Simulation-Based Techniques
      • Planning, Measurement, and Analysis
      • Formal-Based Techniques
      • Debug
      • Acceleration
  • All Courses
    The Verification Academy is organized into a collection of free online courses, focusing on various key aspects of advanced functional verification. Each course consists of multiple sessions—allowing the participant to pick and choose specific topics of interest, as well as revisit any specific topics for future reference. After completing a specific course, the participant should be armed with enough knowledge to then understand the necessary steps required for maturing their own organization’s skills and infrastructure on the specific topic of interest. The Verification Academy will provide you with a unique opportunity to develop an understanding of how to mature your organization’s processes so that you can then reap the benefits that advanced functional verification offers.

    • Universal Verification Methodology (UVM)

      • Introduction to UVM
      • UVM Basics
      • Advanced UVM
      • UVM Connect
      • UVM Debug
      • UVMF - One Bite at a Time

    • Featured Courses

      • Introduction to ISO 26262
      • Introduction to DO-254
      • Clock-Domain Crossing Verification
      • Portable Stimulus Basics
      • Power Aware CDC Verification
      • Power Aware Verification
      • SystemVerilog OOP for UVM Verification

    • Additional Courses

      • Assertion-Based Verification
      • An Introduction to Unit Testing with SVUnit
      • Evolving FPGA Verification Capabilities
      • Metrics in SoC Verification
      • SystemVerilog Testbench Acceleration
      • Testbench Co-Emulation: SystemC & TLM-2.0
      • Verification Planning and Management
      • VHDL-2008 Why It Matters

    • Formal-Based Techniques

      • Formal Assertion-Based Verification
      • Formal-Based Technology: Automatic Formal Solutions
      • Formal Coverage
      • Getting Started with Formal-Based Technology
      • Handling Inconclusive Assertions in Formal Verification
      • Sequential Logic Equivalence Checking

    • Analog/Mixed Signal

      • AMS Design Configuration Schemes
      • Improve AMS Verification Performance
      • Improve AMS Verification Quality
  • All Forum Topics
    The Verification Community is eager to answer your UVM, SystemVerilog and Coverage related questions. We encourage you to take an active role in the Forums by answering and commenting to any questions that you are able to.

    • UVM Forum

      • Active Questions
      • Solutions
      • Replies
      • No Replies
      • Search
      • UVM Forum

    • SystemVerilog Forum

      • Active Questions
      • Solutions
      • Replies
      • No Replies
      • Search
      • SystemVerilog Forum

    • Coverage Forum

      • Active Questions
      • Solutions
      • Replies
      • No Replies
      • Search
      • Coverage Forum

    • Additional Forums

      • Announcements
      • Downloads
      • OVM Forum
  • Patterns Library
    The Verification Academy Patterns Library contains a collection of solutions to many of today's verification problems. The patterns contained in the library span across the entire domain of verification (i.e., from specification to methodology to implementation—and across multiple verification engines such as formal, simulation, and emulation).

    • Implementation Patterns

      • Environment Patterns
      • Stimulus Patterns
      • Analysis Patterns
      • All Implementation Patterns

    • Specification Patterns

      • Occurrence Property Patterns
      • Order Property Patterns
      • All Specification Patterns

    • Pattern Resources

      • Start Here - Patterns Library Overview
      • Whitepaper - Taking Reuse to the Next Level
      • Verification Horizons - The Verification Academy Patterns Library
      • Contribute a Pattern to the Library
  • All Cookbooks
    Find all the methodology you need in this comprehensive and vast collection. The UVM and Coverage Cookbooks contain dozens of informative, executable articles covering all aspects of UVM and Coverage.

    • UVM Cookbook

      • UVM Basics
      • Testbench Architecture
      • DUT-Testbench Connections
      • Configuring a Test Environment
      • Analysis Components & Techniques
      • End Of Test Mechanisms
      • Sequences
      • The UVM Messaging System
      • Other Stimulus Techniques
      • Register Abstraction Layer
      • Testbench Acceleration through Co-Emulation
      • Debug of SV and UVM
      • UVM Connect - SV-SystemC interoperability
      • UVM Versions and Compatibility
      • UVM Cookbook

    • Coding Guidelines & Deployment

      • Code Examples
      • UVM Verification Component
      • Package/Organization
      • Questa/Compiling UVM
      • SystemVerilog Guidelines
      • SystemVerilog Performance Guidelines
      • UVM Guidelines
      • UVM Performance Guidelines

    • Coverage Cookbook

      • Introduction
      • What is Coverage?
      • Kinds of Coverage
      • Specification to Testplan
      • Testplan to Functional Coverage
      • Bus Protocol Coverage
      • Block Level Coverage
      • Datapath Coverage
      • SoC Coverage Example
      • Requirements Writing Guidelines
      • Coverage Cookbook
  • All Events
    No one argues that the challenges of verification are growing exponentially. What is needed to meet these challenges are tools, methodologies and processes that can help you transform your verification environment. These recorded seminars from Verification Academy trainers and users provide examples for adoption of new technologies and how to evolve your verification process.

    • Featured & On-Demand

      • UCIe VIP - 12/7
      • RTL Profiling
      • RISC-V Design
      • Exploring Formal Coverage
      • Processor Customization
      • Interconnect Formal
      • Formal and the Next Normal
      • Formal Verification Made Easy
      • Data Independence and Non-Determinism
      • Exhaustive Scoreboarding
      • Visualizer Debug Environment
      • Webinar Calendar

    • On-Demand Library

      • SystemVerilog Assertions
      • Practical Flows for Continuous Integration
      • Continuous Integration
      • Questa Verification IQ
      • Avery & Siemens VIP
      • Protocol and Memory Interface Verification
      • HPC Protocols & Memories
      • Preparing for PCIe 6.0: Parts I & II
      • High Defect Coverage
      • SoC Design & Functional Safety Flow
      • Complex Safety Architectures
      • All On-Demand Recordings

    • Recording Archive

      • Lint vs Formal AutoCheck
      • FPGA Design Challenges
      • Design Solutions as a Sleep Aid
      • Fix FPGA Failures Faster
      • CDC and RDC Assist
      • The Dog ate my RTL
      • Questa Lint & CDC
      • Hierarchical CDC+RDC
      • Improving Initial RTL Quality
      • CDC Philosophy
      • Hardware Emulation Productivity
      • The Three Pillars of Intent-Focused Insight
      • All Webinar Topics

    • Conferences & WRG

      • 2022 Functional Verification Study
      • Improving Your SystemVerilog & UVM Skills
      • Automotive Functional Safety Forum
      • Aerospace & Defense Tech Day
      • Siemens EDA Functional Verification
      • Industry Data & Surveys
      • DVCon 2023
      • DVCon 2022
      • DVCon 2021
      • Osmosis 2022
      • All Conferences

    • Siemens EDA Learning Center

      • EDA Xcelerator Academy(Learning Services) Verification Training, Badging and Certification
      • View all Xcelerator Academy classes
  • About Verification Academy
    The Verification Academy will provide you with a unique opportunity to develop an understanding of how to mature your organization's processes so that you can then reap the benefits that advanced functional verification offers.

    • Blog & News

      • Verification IQ
      • Verification Horizons Blog
      • Technical Resources

    • Verification Horizons Publication

      • Verification Horizons - July 2023
      • Verification Horizons - March 2023
      • Verification Horizons - December 2022
      • Issue Archive

    • About Us

      • Verification Academy Overview
      • Subject Matter Experts
      • Academy News
      • Contact Us

    • Training

      • Learning @OneGlance (PDF)
      • SystemVerilog & UVM Classes
      • Siemens EDA Classes
Ask a Question
SystemVerilog
  • Home
  • Forums
  • SystemVerilog
  • Covergroup Inheritance

Covergroup Inheritance

SystemVerilog 6883
Covergroup Inheritance 1
Have_A_Doubt
Have_A_Doubt
Forum Access
259 posts
January 11, 2023 at 10:12 am

Hi All ,

I remember reading that covergroup(s) have a limitation that's part of SystemVerilog Open item list . I believed it was about inheritance .

So I was tried an example with covergroup inheritance :: edalink

However I observe that 8 automatic bins are inherited for coverpoint a_auto .

There are total of 12 bins generated , 4 bins for b_auto and 8 bins for a_auto .

If covergroup are inherited then what is the limitation ?

Replies

Log In to Reply

Solution

Solution

dave_59
dave_59
Forum Moderator
11444 posts
January 11, 2023 at 3:00 pm

In reply to Have_A_Doubt:

Your example extends a class type with a second covergroup type; both must be constructed and sampled independently. The original covergroup gc1 was never extended.

The new feature coming in the next revision of the sv LRM allows you to extend the covergroup type as part of the extended class type. Construction and sampling behave virtually similar to the randomize methods so you only have to construct and sample a single covergroup object. 

class  Base ;
    bit [2:0]  a ;
    covergroup  gc1 ;
      auto_a: coverpoint a;
    endgroup
    function  new();
        gc1 = new();
    endfunction
 
 endclass
 
 class  Ext  extends  Base ;
   bit [1:0] b ; 
   covergroup extends gc1 ;       
     auto_b: coverpoint b ;
     cross auto_a, auto_b;
   endgroup
   function  new();
       super.new();
   endfunction
 endclass
 
 module  Covergroup_Inheritance_L3 ;
 
   Ext  ext1 ;
   initial  begin
     ext1 = new() ;
     #2; ext1.b = 1 ;  ext1.gc1.sample();
     #2; ext1.a = 3 ;  ext1.gc1.sample();
   end
 endmodule

This means you can now create a cross between a coverpoint in the base covergroup with a coverpoint in the extended covergroup. You are also allowed to override an existing coverpoint with a new expression or bin structure.

— Dave Rich, Verification Architect, Siemens EDA

MICRO_91
MICRO_91
Full Access
278 posts
January 15, 2023 at 3:19 am

In reply to dave_59:
Hi Dave ,

What if user wants to implement the following as per existing LRM ::

Quote:
create a cross between a coverpoint in the base covergroup with a coverpoint in the extended covergroup

I tried the following code :

class  Ext  extends  Base ;
   bit [1:0] b ; 
   covergroup ext_cg ;       
     auto_a: coverpoint a;
     auto_b: coverpoint b ;
     cross auto_a, auto_b;
   endgroup
   function  new();
       super.new();
       gc1 = null ;    //  Although Legal syntax, coverage  report  not  as  per intention 
       ext_cg = new();
   endfunction
endclass

bins of covergroup gc1 are still inherited although I call null on it explicitly .

Does the LRM have a provision to revert an initialized covergroup to uninitialized / default state ( similar to class objects ) ?

dave_59
dave_59
Forum Moderator
11444 posts
January 15, 2023 at 5:20 pm

In reply to MICRO_91:

Once you construct a covergroup instance, there is no way to remove or modify the bins associated with that instances.

— Dave Rich, Verification Architect, Siemens EDA

MICRO_91
MICRO_91
Full Access
278 posts
January 16, 2023 at 10:03 am

In reply to dave_59:

Thanks Dave .

So the workaround would be to conditionally ignore the bins within base class , right ? ( edalink )

Following warning message is observed at runtime , which I believe is as per intent :=
The number of coverpoint bins is zero for the coverpoint 'a_auto' of covergroup instance ' Base::gc1 '.All the user defined bins in the coverpoint are empty bins and hence it would not contribute towards the overall coverage result.

Any suggestions if there exists a better alternative ?

Siemens Digital Industries Software

Siemens Digital Industries Software

#TodayMeetsTomorrow

Portfolio

  • Cloud
  • Mendix
  • Electronic Design Automation
  • MindSphere
  • Design, Manufacturing and PLM Software
  • View all Portfolio

Explore

  • Community
  • Blog
  • Online Store

Siemens

  • About Us
  • Careers
  • Events
  • News and Press
  • Customer Stories
  • Partners
  • Trust Center

Contact

  • VA - Contact Us
  • PLM - Contact Us
  • EDA - Contact Us
  • Worldwide Offices
  • Support Center
  • Give us Feedback
© Siemens 2023
Terms of Use Privacy Statement Cookie Statement DMCA