1. Wildcard Match
Mayank Gupta and Rajpal Singh
0in FE Noida
March, 2012

2. Agenda
 Introduction
 Motivation
 New Flow
 Class Hierarchy
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3. 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.
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4. New Flow
• Tokenizing Pattern
Tokenize
• Store it in appropriate Data structure
• Start matching on NELT.
Match on
NELT
• Do matching on UTG.
• For Record/Arrays.
Match on
UTG
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5. New Flow
STEP 1 : Tokenize wildcard
Eg : Wildcard is ―a*.b*.*.*c*‖
a* b* * *c*
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6. New Flow
STEP 2 : Start matching nodes in NELT
- Match current token with top‘s children top
a1 b1
a* b* * *c*
a aa b2 b c1
b c1
c
C
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7. New Flow
- Match ―b*‖ with children of a1
top
a1 b1
a aa b2
a* b* * *c* b c1
b c1
c
C
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8. New Flow
- Match ―*‖ with children of b2
top
a1 b1
a aa b2 b c1
a* b* * *c* b c1
c
c
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9. New Flow
- Match ―*c*‖ and ―*‖ with children of c1
top
a1 b1
a aa b2 b c1
a* b* * *c* b c1
c
c
a* b* * *c*
Final Match
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10. New Flow
 Step 3 : Match on UTG hierarchy
— If we hit a record/Array/Subtype we match using UTG
Hierarchy.
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11. Why match using UTG?
 Because we do not create NELT for record symbols.
top
a1 b1 Record1
a b2 b Record2 f1 f2
b f21 f22
No NELT for this portion
 Hence we use UTG for matching inside records.
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12. Tokenizing a wildcard
 A token can be of two types :
— String Token
— Star Token TokenBase
 Star token is simply a ‗*‘
 String token is anything other StringToken StarToken
than ‗*‘
 Eg : ―a*.b*.*.*c*‖
— String Tokens are a*,b*,*c* Class Hierarchy
— Star token is only 1 here - *
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13. How to do Hierarchical Match?
 How we ensure that we match
hierarchy in case of ‗*‘
Star Token
 There are two types of ‗*‘
— Local Match Star
— Hierarchical Match Star Local Match Star
Hierarchical
Match Star
 Local Star matches only the
nodes at current level Two types of ‗*‘ in regex
 Hierarchical Star matches all the
nodes at current and lower level.
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14. How to do Hierarchical Match?
Example.
 If pattern is ―a*.b*.*.*c*‖
Star Token
 It will be converted to Hierarchical
Local Match Star
Match Star
a* H* b* H* L* H* *c* H*
Two types of ‗*‘ in regex
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15. Organizing Tokens
 Class NeltTokenArray contains
— vector<TokenBase*> a* b* * *c*
 Class NeltTokenIndex contains
— NeltTokenArray* a* b* * *c*
— Index (current token)
Index
 Class NeltRegexExpr contains
— Vector<NeltTokenIndex*>
a* b* * *c* a* b* * *c* a* b* * *c*
Index Index Index
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16. 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.
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17. C++ classes
 NeltRegexMgr NeltTraverse NeltUtgTypeTraverse
— NeltTraverse
 NeltUtgRegexMgr
NeltRegexMgr NeltUtgRegexMgr
— NeltTypeTraverse
 NeltRegexExpr
 NeltTokenIndex NeltTokenIndex TokenBase
— NeltUtgTokenIndex
 NeltTokenArray NeltUtgTokenIndex StringToken StarToken
 TokenBase
— StringToken
— StarToken
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18. Source Code
 Source files
— src/commonpp/nelt
– neltRegexMgr.cxx
– neltRegexMgr.hxx
– neltUtgRegexMgr.cxx
– neltUtgRegexMgr.hxx
– neltRegexUtils.cxx
– neltRegexUtils.hxx
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19. Performance data
S.No Test Case Old Flow Time(s) New Flow Time(s)
1 Parme 161 484
2 Oracle 1814 1658
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20. 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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21. www.mentor.com
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