Formal Verification of Synchronization Issues of SpecC Description with Automatic Abstraction - PowerPoint PPT Presentation

Loading...

PPT – Formal Verification of Synchronization Issues of SpecC Description with Automatic Abstraction PowerPoint presentation | free to download - id: 7a3d50-YWVmY



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Formal Verification of Synchronization Issues of SpecC Description with Automatic Abstraction

Description:

Formal Verification of Synchronization Issues of SpecC Description with Automatic Abstraction Thanyapat Sakunkonchak Masahiro Fujita Department of Electronics Engineering – PowerPoint PPT presentation

Number of Views:58
Avg rating:3.0/5.0
Slides: 19
Provided by: Thanya2
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Formal Verification of Synchronization Issues of SpecC Description with Automatic Abstraction


1
Formal Verification of Synchronization Issues of
SpecC Description with Automatic Abstraction
  • Thanyapat Sakunkonchak
  • Masahiro Fujita
  • Department of Electronics Engineering
  • University of Tokyo

2
Overview
  • Introduction
  • Verification Flows
  • Example
  • Summary Outlooks

3
Synchronization in SpecC
Ambiguous results on y causing from x 10
/st1/ x 20 /st3/
y 20 (always)
4
Synchronization in SpecC (cont.)
  • TasTbs, TaeTbe
  • TasltT1sltT1eltT2sltT2eltTas
  • TbsltT3sltT3eltTbe
  • T2eltT3s

5
Difference Decision Diagrams (DDD)
  • Introduce by MFller, et al.
  • Symbolic representation of non-boolean, such as
    inequality less efficient if using BDD
  • DDD represents difference constraints (x-yc),
    x,y are integers, c is constant

Represents graph for (x-zlt1)?(x-y0)?(y-z2)
6
Overview
  • Introduction
  • Verification Flows
  • Example
  • Summary Outlooks

7
Verification Flows
  • Goals
  • Check whether given SpecC codes (with par,
    notify/wait) are properly synchronized
  • If checking fails, counter-examples should be
    generated (trace to source of errors)
  • Based on
  • Boolean SpecC, DDD, SVC, Program Slicing, ...

8
(No Transcript)
9
Overview
  • Introduction
  • Verification Flows
  • Example
  • Summary Outlooks

10
Example
  • Sleeping barber problem

barber
  • barber finished cutting-gtcall customer
  • barber no customer-gtwait
  • customer barber wait-gthas hair cut
  • customer chairs occupied-gtcome again
  • customer a chair empty-gtwait

customer
empty chair
barber chair
11
Example
behavior barber (inout event call,
inout bool chairOccupied,
inout int numCustomer) void main()
while(1) if (numCustomer 0)
DayDreaming() else if
(chairOccupied true)
KeepCutting() chairOccupied false
else notify call
chairOccupied true

behavior customer (inout event call,
inout bool chairOccupied,
inout int numCustomer) void main()
while(1) if (numCustomer 3)
GoBack() else numCustomer
if (chairOccupied false) wait
call numCustomer--

12
Example (verify)
  • SpecC gt boolean SpecC build
  • Control Flow Graph (CFG)
  • Verify with DDDs if result is satisfied,
    terminate, else go to next step
  • Use CFG to find related path and use SVC to
    verify boolean variables and find the conditions
    imply infeasibility
  • Use those conditions and modify boolean SpecC
  • Go to 2

13
Example
behavior barber (inout event call,
inout bool chairOccupied,
inout int numCustomer) void main()
while(1) if (numCustomer 0)
DayDreaming() else if
(chairOccupied true)
KeepCutting() chairOccupied false
else notify call
chairOccupied true

behavior customer (inout event call,
inout bool chairOccupied,
inout int numCustomer) void main()
while(1) if (numCustomer 3)
GoBack() else numCustomer
if (chairOccupied false) wait
call numCustomer--

Build boolean SpecC CFG
14
Example (abstract)
behavior barber () void main()
while(a0) if (a1) ... else
if (a2) ...
... else
notify call ...

behavior customer () void main()
while(b0) if (b1) ... else
... if (b2)
wait call ...

Verify with DDDs
15
CFG Construction
Entry barber
while
numCustomer
chairOccupied
call
if numCustomer 0
if numCustomer ! 0
DayDreaming
if chairOccupied T
if chairOccupied F
KeepCutting
chairOccupied F
notify call
chairOccupied T
Control flow (CF)
Date flow (DF)
16
CFG Construction
Entry customer
while
newCustomer
numCustomer
call
chairOccupied
numCustomer newCustomer
newCustomer rand() 1
if numCustomer 5
if numCustomer ! 5
numCustomer
if chairOccupied T
GoBack
wait call
Control flow (CF)
numCustomer--
Date flow (DF)
17
Example (refine)
behavior barber () void main()
while(a0) if (a1) //numCustomer
0 ... else if (a2)
//chairOccupied true ...
!a2 //chairOccupied false
else notify call a2
//chairOccupied true

behavior customer () void main()
while(b0) if (b1) //numCustomer
3 ... else ...
//numCustomer if (b2)
//chairOccupied false wait call
... //numCustomer--

Check predicates for validity (SVC)
Verify with DDDs
18
Example (verification)
  • The synchronization of even call is satisfied
  • User-defined assertions can be used to verify for
    some properties, e.g. to see whether numCustomer
    is more than 3
  • The refinement process is not automatically done.
    Some efforts from users are needed to browse over
    CFG and find the locations

numCustomer if (numCustomer gt 3)
assert(F) if (chairOccupied false)
19
Overview
  • Introduction
  • Verification Flows
  • Example
  • Summary Outlooks

20
Summary Outlook
  • The verification of synchronization issues of
    SpecC is described
  • The automatic abstraction is proposed
  • Up to the current implementation
  • The refinement process is not fully automatic
    (CFG cooperation needs to be manually done)
  • Cannot handle complex SpecC construct

21
Summary Outlook (2)
  • Future plans
  • Make the abstraction refinement to be
    automatically operated
  • Expand capability to support more complex SpecC
    structure, e.g. loop, functions, recursive
About PowerShow.com