On the Object Orientedness of C programs in SPEC CPU 2006

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On the Object Orientedness of C programs in
SPEC CPU 2006

• Ciji Isen Lizy K. John
• University of Texas - Austin

1/27/2008
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Introduction

• Object Oriented programming encourages
• Code modularity, ease of design maintenance
• Inheritance hierarchies
• polymorphism
• Dynamic Dispatch
• Should imply
• Multiple function invocation
• More functions
• More indirect branching
• Increased control flow
• particularly function calls and indirect branches

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Objective

• Object oriented nature of SPEC CPU2006 C
  programs
• Measure using quantifiable metrics
• Compare with other OO(SPEC java) benchmarks
• Has OO nature affected control flow?
• branch compositions
• Branch misprediction

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C programs in SPEC cpu06
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Methodology

• Performance counters
• Woodcrest(Intel), Power5(IBM)
• Benchmarks
• SPEC CPU 2006
• SPEC jbb2000
• SPECjvm98
• Principle Component Analysis for Visualization

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Object Oriented metrics

• CK (Chidamber and Kemerrer) metrics
• WMC (Weighted Methods per Class)
• DIT (Depth of Inheritance Tree)
• NOC (Number of Children)
• CBO (Coupling Between Objects)
• RFC (Response for a Class)

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WMC (Weighted Methods per Class)

• if complexity is unity
• WMC n
• Intuition More methods implies
• more time effort to develop and maintain class
• More methods inherited by children gt more impact
  on children
• Likely to be more application specific gt less
  reuse

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DIT (Depth of Inheritance Tree)

• A measure of impact of ancestor classes
• Intuition deeper class hierarchy implies
• More methods inherited gt more complexity
• Greater design complexity
• Greater potential to reuse inherited methods

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NOC (Number of Children)

• Definition Number of immediate subclasses
• Intuition more children implies
• Greater reuse
• more influence on the design

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CBO (Coupling Between Objects)

• Definition The number of other classes to which
  a class is coupled
• Via methods
• Instance variables
• Intuition more coupling implies
• Bad for modularity. Less independence for class
  gt difficult to reuse
• Less independence gt sensitive to change in other
  parts
• More interaction gt complexity in testing
  correctness

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RFC (Response for a Class)

• Intuition more methods executed per message
  implies
• More complexity for the class
• Complexity in testing and debugging

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Object Orientedness of C benchmarks in cpu06
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Object Orientedness of C benchmarks in cpu06
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Object Orientedness of C vs. java benchmarks
DaCapo paper
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Object Orientedness of C vs. java benchmarks
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Control flow Characteristics

• Has OO nature affected control flow?
• branch compositions
• Branch misprediction

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Branch types - INT
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Branch types - FP
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Branch types - INT
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Branch types - FP
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Branch misprediction - INT
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Branch misprediction - FP
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Summary

• Increased presence of C in SPEC CPU encouraging
• Measured object orientedness of C programs
• Xalanckbmk,dealII omnetpp strong OO
• OO nature of C programs not any worse than SPEC
  Java benchmarks
• Analyzed impact of OO nature on control flow
• Control flow increase pronounced for FP
• Xalanckbmk, dealII omnetpp higher of
  function calls and indirect branches

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Questions
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Laboratory for Computer Architecture
8/28/2007