Risorse bibliografiche
Risorsa bibliografica obbligatoria
Risorsa bibliografica facoltativa
Scheda Riassuntiva
Anno Accademico 2019/2020
Scuola Scuola di Ingegneria Industriale e dell'Informazione
Docente Agosta Giovanni
Cfu 5.00 Tipo insegnamento Monodisciplinare

Corso di Studi Codice Piano di Studio preventivamente approvato Da (compreso) A (escluso) Insegnamento

Obiettivi dell'insegnamento

Code Transformation and Optimization

In modern computer science and engineering, code transformation techniques are critical to achieve the combined goals of combining programmer productivity and program execution efficiency in terms of time and energy. Yet, it is a skill mastered by few – there are less than 1.5 compiler construction expert for every 1000 software engineers, but almost 2 jobs in compilers for every 100 in software engineering!

The course is designed to provide an overview of code transformation, analysis and optimization techniques needed to effectively produce optimized code.

To compiler and EDA tool engineers, the course provides the basic tools to design and implement compilers and other code transformation and analysis tools, as well as an introduction to the most popular modern compiler framework, LLVM.

To software engineers, the course provides a grounding in system software design and development, as well as insights on the benefits and limitations of automation in software engineering. Moreover, as a compiler is a paramount of complex software systems, it provides a hands-on introduction to the design and implementation process for such systems. Finally, many advanced software engineering techniques such as program slicing are implemented on top of algorithms used in compiler construction.

To computer architects and embedded software engineers, the course provides crucial insights on the power and limits of compiler optimization, as well as to the need any processor architecture has of appropriate compilers.

To all computer science students, the course provides a “behind the scenes” view of the operation of software, and its automated manipulation – understanding compilers means being able to write better, more efficient code.

Risultati di apprendimento attesi

Dublin Descriptors

Expected Learning Outcomes

Knowledge and understanding

Understand the internal structure of a real-world compiler as a pipeline of passes, including its main components (front-end: parser, lexer; mid-end: optimizers; back-end: code generator, register allocator, instruction scheduler).

Understand the effectiveness and limitations of code analysis and optimization techniques (focusing in particular on loop transformation and data flow analysis)

Understand the main issues related to the linking phase

Applying knowledge and understanding

Be able to construct a full compiler for a toy language, generating assembly code for a RISC architecture.

Get familiarity with the LLVM compiler framework (an industry-grade, open source compiler).

Making judgements

Analyse and understand the effectiveness of specific code analysis and transformation techniques.

Define the architecture of a compiler framework and/or of specific compiler passes within a give infrastructure.

Understand the pitfalls and tradeoffs of compiler development (e.g., ease of debugging vs global performance optimization).



Develop the ability to communicate complex algorithmic concepts within a short timeframe.

Lifelong learning skills

Learn how to develop in practice a large scale project, understanding the importance of early assessing pitfalls and tradeoffs in development.

Argomenti trattati

Introduction to Compiler Construction

  • Why compiling? Compilers vs interpreters

  • When to compile? JIT, AOT and static compilers

  • What to compile? Compilation units

  • Where to compile? Cross-compilation and split compilation

  • Overview of a compiler framework

    • Lexical analysis & parsing (review)

    • Statement and Data Structure Lowering

    • Optimization: machine independent and machine-dependent

    • Code Generation

Reading: Compiler Construction

Intermediate Representations

  • The Abstract Syntax Tree

  • Basic Blocks and branches

  • The Control Flow Graph

  • The Static Single Assignment Form

Reading: Program Dependence Graph

Reading: The SUIF Compiler Framework

Semantic Analysis & Type Checking

  • Symbol Tables

  • Type Checking

Runtime Organization

  • Data Memory layout

  • Activation Records

  • Dynamic Memory allocation

Reading: Garbage Collection

Code Generation

  • Code generation techniques: CISC and RISC processors

  • Low-level optimization techniques

Reading: Low-level Optimization

Dataflow Optimization

  • Principles and Fixed Point Computation

  • Applications

    • Reaching Definitions

    • Liveness Analysis

    • Constant Propagation

Reading: Dataflow Optimizations

Register Allocation

  • When to allocate registers

  • Graph Coloring

  • Linear scanning

Reading: Linear Scan Register Allocation

Parallelization and other optimization techniques

  • Instruction Scheduling

  • Loop Optimization (Software Pipelining, Loop Unrolling)

  • Limits to optimization: the aliasing problem

Reading: Program Optimization  

Reading: Alias Analysis

Reading: Cache Optimization

Advanced Topics

Advanced Optimization Techniques: Polyhedral Transformations

The LLVM Compiler Framework


  • The sessions will be organized as follows:

    • Recursive descent language parsing

    • Transforming the Abstract Syntax Tree into a Control Flow Graph

    • Design and implementation of the symbol table

    • Function call translation

    • Liveness analysis

    • Register allocation (linear scan)

    • ARM code generation (table-based)




The papers presented in this bibliography are mostly for those who wish to get deeper insight on a specific topic.

Compiler Construction

LLVM: A Compilation Framework for Lifelong Program Analysis & Transformation, by C. Lattner and V. Adve.

Intermediate Representations

The Program Dependence Graph and Its Use in Optimization, by J. Ferrante et al.

The Basic SUIF Programming Guide, by G. Aigner et al.

Alias Analyis

Interprocedural pointer alias analysis, by M. Hind et. al.

Register Allocation

Linear Scan Register Allocation, by M. Poletto and V. Sarkar.


Compiler Transformations for High-Performance Computing, by D. Bacon et al.

Cache Optimization

A Retrospective: A Data Locality Optimizing Algorithm, by M. S. Lam.

Garbage Collection

Uniprocessor Garbage Collection Techniques: a complete survey of Garbage Collection by P. Wilson.



The course is mostly self-contained. Knowledge of imperative and object-oriented programming (as provided in the Laurea in Ingegneria Informatica) is necessary, and an understanding of parsing techniques is useful (however, the necessary concepts of recursive descent parsing are introduced in the first lecture and observed in practice in the first laboratory). Also, a basic understanding of computational complexity (once more, as provided in Laurea in Ingegneria Informatica) is useful.

The project/laboratory work can be conducted in Python or C++.

Modalità di valutazione


Evaluation is performed through a combination of oral exam and project work.

Type of Assessment


Dublin descriptors

Oral Exam

The oral exam consists of a discussion of the topics covered in the course, including theoretical questions and questions aimed at assessing the ability of the student to connect different topics within the course syllabus.


Assessment of laboratorial artefacts

The project work can be taken in groups of one to three students, and in the following two modes:

An independent project activity, consisting in the implementation of an optimization or analysis pass in the LLVM compiler framework (suggested only for students with previous experience in C/C++ programming);

A supervised project activity, consisting in the implementation of a compiler for a toy language targeting the ARM assembly language.




Risorsa bibliografica obbligatoriaAndrew Appel with Jens Palsberg, Modern compiler implementation in Java, Editore: Cambridge University Press, Anno edizione: 2002

The similar, but earlier, book "Modern compiler implementation in C" by Appel is available online for free download.

Risorsa bibliografica facoltativaAho, Lam, Sethi, and Ullman, Compilers: principles, techniques and tools, Editore: Prentice-Hall, Anno edizione: 2006

We use only Chapter 11

Software utilizzato
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Forme didattiche
Tipo Forma Didattica Ore di attività svolte in aula
Ore di studio autonome
Laboratorio Informatico
Laboratorio Sperimentale
Laboratorio Di Progetto
Totale 50:00 75:00

Informazioni in lingua inglese a supporto dell'internazionalizzazione
Insegnamento erogato in lingua Inglese
Disponibilità di materiale didattico/slides in lingua inglese
Disponibilità di libri di testo/bibliografia in lingua inglese
Possibilità di sostenere l'esame in lingua inglese
Disponibilità di supporto didattico in lingua inglese
schedaincarico v. 1.8.3 / 1.8.3
Area Servizi ICT