1 Languages and Compilers (SProg og Oversættere) Bent Thomsen Department of Computer Science Aalborg University With acknowledgement to Hanne Riis Nielson.

1

Languages and Compilers(SProg og Oversættere)

Bent Thomsen

Department of Computer Science

Aalborg University

With acknowledgement to Hanne Riis Nielson and Flemming Nielson whose book this lecture is based on.

2

The missing link

The connectionBetween

Syntax and SemanticsAnd

Languages and Compilers

3

The Language While

The Language While can be considered mini version of Mini-TriangleWhile is almost the same as the BIMS language

4

Single step operational semantics for While

5

A stack based virtual machine - AM

States:

Transitions:

6

Operational semantics for AM

7

Translation of While to AM

Note similarity with code generation templates for Mini-Triangle

8

Example

9

Correctness Proof

10

Soundness and completeness

11

Getting closer to TAM

12

And closer

13

Conclusion

• With a bit of hard work it is possible to connect – The high level operational semantics for a language

– With the low level implementation

– And prove correctness of the translation

• This is called:

Provably correct implementations

• For more information read– Semantics with applications,

– Hanne Riis Nielson and Flemming Nielson

– Wiley 1992, ISBN 0 471 92980 8