Proof-Transforming Compilation of Programs with Abrupt Termination

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Proof-Transforming Compilation of Programs with
Abrupt Termination

• Peter Müller and Martin Nordio

Microsoft Research (USA)
ETH Zurich
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Proof-Carrying Code
Source Prog
VC Generator
Certifying compiler
code
Annotations
VC Generator
VC
VC
Proof
Proof Generator
Proof Checker
CPU
Code Producer
Code Consumer
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Develop the proof for the Bytecode

• Logics for intermediate languages such asJava
  Bytecode and CIL were developed
• (Müller and Bannwart)
• Pro It can produce the certificate needed
• Con It is difficult and expensive

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Proof-Transforming Compilers (PTC)
Source prog. contracts
Prover
Source prog. proof
Bytecode proof
PTC
Proof Checker
CPU
Code Producer
Code Consumer
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PTC Elements
Source Language Java
Bytecode Language Java Bytecode
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The bytecode Language
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The bytecode Logic

• We use the bytecode logic developed by F.
  Bannwart and P. Müller
• Instruction specification

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The Source Language

• Similar to a Java subset

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Logic for Java subset

• The logic is based on the programming logic
  developed by A. Poetzsch-Heffter and N. Rauch.
• Properties of method bodies are expressed by
  Hoare triples of the form

normal
break
exception
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Example try-finally statements
b ? Normal or Exception?
b 4 Normal
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Compilation try-finally statements
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Example try-finally statements
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Logic for try-finally statements
finally try N B E2
N N B E2
B B B E2
E1 E1 B E2
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Example 2 Exception Table
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Example 2 Exception Table (cont.)
Exception
any
Exception
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Example 2 Exception Table (cont.)
Exception
any
Exception
any
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Translation Function
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PTC

• Compositional statement
• While
• try-finally
• Break
• Translate the finally blocks dividing the
  exception table
• Add a goto end-while

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Summary

• Source Language
• Subset of Java
• while, break,
• try-catch, try-finally, throw
• Soundness proof