Automatic derivation of Semantic Properties in 'NET

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Automatic derivation of Semantic Properties in
.NET

• Analyze the behaviour of an assembly using Phoenix

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Problems/issues

• Weaving is currently only possible on the
  syntactic level
• Set also matches Setup
• Not certain of actual implementation
• Possible conflicts while using aspects
• SECRET uses custom attributes
• There is no knowledge about
• the method body itself

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Goals

• Semantic weaving points
• Fine grained weaving
• Inside the method body
• Based on conditions, loops, exception handling,
  method calling, branching
• Detection of possible conflicts
• Read/write actions on same fields
• Resource conflicts (files, ports etc)
• Providing information for SECRET

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How to

• Must support multiple .NET languages
• Parser for each language is inefficient
• Use of the Common Intermediate Language
• Extract semantics from an assembly using a tool
  (IL reader)
• Store the semantics in a model
• Allow tools to query this model using API

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Read IL using Phoenix

• Microsoft research project named Phoenix
• An unified framework for building compilers and
  software development tools.
• Used internal by MS for compiling Windows,
  PowerPoint, games and for building test tools.
• Contains readers, analysis tools (control/data
  flow etc), inserters and writers.
• Targets different architectures and languages

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Phoenix

• Multiple phases executed in sequential order
• Add own phases between others
• A common Intermediate Representation (IR)
• Accessible in each phase
• Represents a function at multiple levels of
  abstraction
• Flows, AST on top of IR
• IL instructions are converted to IR objects

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Phoenix Architecture
High Level Analysis and Optimization
Machine Independent Optimization
Front End
Reader
Code Generation
Phoenix API
Machine Dependent Optimization
Code Emission
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Instructions in Phoenix

• Pseudo instructions
• Not directly mapped to machine code
• E.g. labels, data
• Real instructions
• ValueInstr assignment, add, mul, neg
• CallInstr call, jmp
• CmpInstr gt, lt, eq, neq
• BranchInstr br, brfalse, bgt, bne
• SwitchInstr switch
• OutlineInstr inline assembly code

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New model needed

• Why another model?
• Phoenix model very general and large
• Structure not directly mapped to .NET assembly
  structure
• We only use HIR to analyse
• Need own API to reason about semantics
• Semantic tools independent of Phoenix

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Meta Model
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Meta Model
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Creating an API

• Find certain instruction in method
• Is instruction in loop, for, conditional?
• Has instruction exception handling?
• Is parameter X assigned a value?
• Is field Y assigned a value in this
  method/property?
• Each method where value of Z gt 10
• Which operations are used on the ReifiedMessage
  parameter?

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Remarks

• Static analysis
• Some minor code changes between the real source
  and IL
• However JIT does most of optimalization
• Local variable names are missing in IL
• Phoenix and Whidbey needed
• Phoenix very powerful

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JIT Optimalization

• Constant folding
• Constant and copy propagation
• Common subexpression elimination
• Code motion of loop invariants
• Dead store and dead code elimination
• Register allocation
• Method inlining
• Loop unrolling (small loops with small bodies)