1. Interpreted languages Jakub Yaghob
Compiler principles
Interpreted languages
Jakub Yaghob

2. What are we talking about?
The source language is not translated to a CPU code. Instead, it is translated to an abstract machine code
Native compiled interpreter simulates the abstract machine

3. Why? No space for a compiler Portability Security
8-bit computers and BASIC
Portability
The same abstract machine can run od different Oss and different CPU architectures
AS/400, Java
Security
Better control of executed instructions

4. Problems Speed Portability How to design the abstract machine/code
It can be partially solved by JIT (Just-In-Time compilation)
Whenever the interpreter should execute abstract machine code, it is immediately compiled to native CPU instructions and stored in a cache
AoT (Ahead-of-Time)
Compile during installation
Portability
Changing abstract machine behavior causes problems with portability
Java
How to design the abstract machine/code
It should cover all source languages
.NET

5. Dynamic memory When supported, always with garbage collector
Pointers under control
Easy programming
Faster dynamic memory
Program usually does not need too much memory, therefore GC is not invoked at all and all memory is just quickly allocated
The abstract machine simulator usually takes more memory then would have