1. Proof-Transforming Compilation of Programs with Abrupt Termination
Peter Müller and Martin Nordio
Microsoft Research
(USA)
ETH Zurich

2. Proof-Carrying Code VC Generator Certifying compiler VC Generator
Source Prog
VC Generator
Certifying compiler
code
Annotations
VC Generator VC VC
Proof
Proof Generator
Proof Checker
CPU
Code Producer
Code Consumer 2

3. Develop the proof for the Bytecode
Logics for intermediate languages such as Java Bytecode and CIL were developed
(Müller and Bannwart)
Pro: It can produce the certificate needed
Con: It is difficult and expensive 3

4. Proof-Transforming Compilers (PTC)
Source prog.
+ contracts
Prover
Source prog.
+ proof
Bytecode
+ proof
PTC
Proof Checker
CPU
Code Producer
Code Consumer 4

5. PTC Elements Source Language: Java Logic: Hoare-Style
structured control flow
variables
Logic:
Hoare-Style
translation functions
Bytecode Language:
Java Bytecode
unstructured control flow
operand stack
Bytecode
Logic 5

6. The bytecode Language 6

7. The bytecode Logic
We use the bytecode logic developed by F. Bannwart and P. Müller
Instruction specification 7

8. The Source Language
Similar to a Java subset 8

9. 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 9

10. Example: try-finally statements
b= Normal
b= ? Normal or Exception? 10

11. Compilation: try-finally statements11

12. Example: try-finally statements12

13. Logic for try-finally statementsB E2 E1 13

14. Example 2: Exception Table14

15. Example 2: Exception Table (cont.)
any
Exception 15

16. Example 2: Exception Table (cont.)
any
Exception
any 16

17. Translation Function 17

18. PTC Compositional statement While try-finally Break
Translate the finally blocks dividing the exception table
Add a goto end-while 18

19. Summary Source Language: Soundness proof Subset of Java while, break,
try-catch, try-finally, throw
Soundness proof 19