wildcard expansion

Mayank Gupta and Rajpal Singh

Wildcard Match

0in FE Noida

March, 2012

2© 2011 Mentor Graphics Corp. Company Confidentialwww.mentor.com

Agenda

Introduction Motivation New Flow Class Hierarchy

Mayank, Wildcard Match, March 2012


Motivation

Efficiently matching a regular expression in a RTL design.

Use NELT to do matching.— Previous flow creates a separate data structure

altogether to do matching. — Using NELT hierarchy would reduce memory usage.

Enhance Functionality.



New Flow


Tokenize •Tokenizing Pattern•Store it in appropriate Data structure

Match on NELT •Start matching on NELT.

Match on UTG •Do matching on UTG.•For Record/Arrays.


New Flow

STEP 1 : Tokenize wildcard

Eg : Wildcard is “a*.b*.*.*c*”


a*

b* *

*c*


New Flow

STEP 2 : Start matching nodes in NELT

- Match current token with top’s children


top

a1

a aa b2

b c1

C

b1

b c1

c

a*

b* *

*c*


New Flow

- Match “b*” with children of a1


top

a1

a aa b2

b c1

C

b1

b c1

ca*

b* *

*c*


New Flow

- Match “*” with children of b2


top

a1

a aa b2

b c1

c

b1

b c1

ca*

b* *

*c*


New Flow

- Match “*c*” and “*” with children of c1


top

a1

a aa b2

b c1

c

b1

b c1

ca*

b* *

*c*

a*

b* *

*c*

Final Match


New Flow


Step 3 : Match on UTG hierarchy

— If we hit a record/Array/Subtype we match using UTG Hierarchy.


Why match using UTG?


Because we do not create NELT for record symbols.

Hence we use UTG for matching inside records.

top

a1

a b2

b

b1

b

Record1

Record2

f21 f22

f1 f2

No NELT for this portion


Tokenizing a wildcard


TokenBase

StarTokenStringToken

Class Hierarchy

A token can be of two types :— String Token — Star Token

Star token is simply a ‘*’ String token is anything other

than ‘*’ Eg : “a*.b*.*.*c*”

— String Tokens are a*,b*,*c*

— Star token is only 1 here - *


How to do Hierarchical Match?


Star Token

Hierarchical Match Star

Local Match Star

Two types of ‘*’ in regex

How we ensure that we match hierarchy in case of ‘*’

There are two types of ‘*’— Local Match Star— Hierarchical Match Star

Local Star matches only the nodes at current level

Hierarchical Star matches all the nodes at current and lower level.


How to do Hierarchical Match?


Star Token

Hierarchical Match Star

Local Match Star

Two types of ‘*’ in regex

Example. If pattern is “a*.b*.*.*c*”

It will be converted to

a*

H*

b*

H*

L*

H*

*c*

H*


Organizing Tokens


Class NeltTokenArray contains — vector<TokenBase*>

Class NeltTokenIndex contains — NeltTokenArray*— Index (current token)

Class NeltRegexExpr contains— Vector<NeltTokenIndex*>

a*

b* *

*c*

a*

b* *

*c*

Index

a*

b* *

*c*

Index

a*

b* *

*c*

a*

b* *

*c*

IndexIndex


Manager Classes


Class NeltRegexMgr is used to match on NELT. Class NeltUtgRegexMgr is used to match on UTG . It is the responsibility of NeltRegexMgr to invoke

NeltUtgRegexMgr.


C++ classes

NeltRegexMgr — NeltTraverse

NeltUtgRegexMgr— NeltTypeTraverse

NeltRegexExpr NeltTokenIndex

— NeltUtgTokenIndex

NeltTokenArray TokenBase

— StringToken— StarToken


NeltTokenIndex

NeltRegexMgr

NeltTraverse

NeltUtgTokenIndex

NeltUtgRegexMgr

NeltUtgTypeTraverse

TokenBase

StarTokenStringToken


Source Code

Source files— src/commonpp/nelt

– neltRegexMgr.cxx– neltRegexMgr.hxx– neltUtgRegexMgr.cxx– neltUtgRegexMgr.hxx– neltRegexUtils.cxx– neltRegexUtils.hxx



Performance data


S.No Test Case Old Flow Time(s)

New Flow Time(s)

1 Parme 161 484

2 Oracle 1814 1658


Future Work

Add a new class SliceToken deriving from TokenBase to store tokens of the form tok[slice]

Avoid duplicate matching— Eg : “a*.a*b” is expanded into two patterns : 1) a*.H*.a*b 2) a*.H*.a*.H*.*b Both the patterns have “a*.H*” in the beginning and

hence it gets matched twice.



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