This document provides an overview of compilers and translation processes. It defines a compiler as a program that transforms source code into a target language like assembly or machine code. Compilers perform analysis on the source code and synthesis to translate it. Compilers can be one-pass or multi-pass. Other translators include preprocessors, interpreters, assemblers, linkers, loaders, cross-compilers, language converters, rewriters, and decompilers. The history and need for compilers and programming languages is also discussed.

1. Compiler Design
(CSE-405-F)
Akhil Kaushik
Asstt. Prof., CE Deptt.,
TIT Bhiwani

2. Programming….Why?

3. What is a Compiler?
• A compiler is a computer program (or set of
programs) that transforms source code written in a
high level language (the source language) into low
level language (the target language may be assembly
language or machine language (0,1)).

4. What is a Compiler?

5. What is a Compiler?
Source Language Target Language

6. Introduction
Compiler basically does two things:
• Analysis: Compiling source code & detecting
errors in it.
• Synthesis: Translating the source code into
object code depending upon the type of
machine.

7. Introduction
• Program errors are difficult to track, if the
compiler is wrongly designed.
• Hence, compiler construction is a very
tedious and long process.

8. One-pass Compiler
• It compiles the that passes through the source
code of each compilation unit only once.
• They are faster than multi-pass compiler.
• Their efficiency is limited because they don’t
produce intermediate codes which can be
refined easily.
• Also known as ‘Narrow Compiler’.

9. Multi-pass Compiler
• It processes the source code or abstract syntax
tree of a program several times.
• It may create one or more intermediate codes
(easy to refine).
• Each pass takes output of previous phase as
input; hence requires less memory.
• Also known as ‘Wide Compiler’.

10. Type of Languages
1. Binary Level
Language
2. Assembly Level
Language
3. High Level
Language

11. Need for programming languages?
• Closer to human thinking behavior.
• Program’s size is shorter.
• Error detection is easy.
• Same program can be compiled in accordance
to different machine architectures.

12. History
• Software for early computers were
written in assembly language.
• The need of reusability of code gave
birth to programming languages.
• This need grow huge to overcome the
cost restriction of compiler.

13. History
• The concept of machine independent
programming gave birth to the need of
compilers in 1950s.
• The 1st compiler was written by
Grace Hopper in 1952 for A-0
programming language.

14. History
• The 1st complete compiler was developed by
FORTRAN team lead by John Backus @ IBM in
1957.
• COBOL was the 1st language to be compiled on
multiple platforms in 1960.

15. History
• Earlier compilers were written in
assembly languages.
• The 1st compiler in HLL was
created for LISP by Tim Hart &
Mike Levin @ MIT, USA in 1962,
which was a self-hosting
Compiler.

16. History
• Most compilers are made in C or Pascal
languages.
• However the trend is changing to self-hosting
compilers, which can compile the source code of
the same language in which they are created.

17. Why Study Compiler?
• Its essential to understand the
heart of programming by
computer science engineering
students.
• There may be need of
designing a compiler for any
software language in the
profession.

18. Why Study Compiler?
• Increases understanding of
language semantics.
• Helps to handle language
performance issues.
• Opportunity for non-trivial
programming project

19. Translators
• It is important to understand that compiler is a
kind of translator, which translates high level
language (human understandable) to low-level
language(machine understandable).

20. Translators

21. Translators - Preprocessor
• It is a program that processes its input data to
produce output that is used as input to another
program.
• The output is said to be a preprocessed form of the
input data, which is often used by some subsequent
programs like compilers.

22. Translators - Preprocessor
• The amount and kind of processing done depends on
the nature of the preprocessor.
• some preprocessors are only capable of performing
simple textual substitutions and macro expansions,
while others have the power of full-
fledged programming languages.
• It can also include macro processing, file inclusion and
language extensions.

23. Translators - Interpreter
• It is another common kind of language processor.
• Instead of producing a target program as a
translation, it directly execute the operations
specified in the source program on inputs supplied
by the user.

24. Translators - Interpreter
• This software converts the high-level language
into low-level language line by line.
• It takes less memory than compiler.
• It takes more time than compiler.
• It is more efficient in error detection than
compiler.
• It takes more time to build.

25. Translators - Interpreter
• Java language processors combine compilation
and interpretation.
• A Java source program may first be compiled into
an intermediate form called bytecodes.
• The bytecodes are then interpreted by a virtual
machine.
• A benefit of this arrangement is that bytecodes
compiled on one machine can be interpreted on
another machine, perhaps across a network.

26. Translators - Interpreter

27. Translators - Assembler
• This software converts the assembly language
(assembly instruction mnemonics) into machine
level language (opcodes i.e. 0,1).
• It offers reusability of assembly codes on different
machine platforms.

28. Translators - Assembler
• It generates instructions by evaluating the
mnemonics (symbols) in operation field and find
the value of symbol and literals to produce
machine code.
• Now, if assembler do all this work in one scan then
it is called single pass assembler, otherwise if it
does in multiple scans then called multiple pass
assembler.

29. Translators - Assembler
• Pass-1:
– Define symbols and literals and remember them in
symbol table and literal table respectively.
– Keep track of location counter
– Process pseudo-operations
• Pass-2:
– Generate object code by converting symbolic op-code
into respective numeric op-code
– Generate data for literals and look for values of
symbols

30. Translators - Assembler

31. Translators - Linker
• A linker is a program that allows a user
to link library programs or separate
modules of code into their own
programs.
• It is used to combine different modules
of object code into one single
executable code program.

32. Translators - Linker
• This may involve combining a program with library
programs, or involve recombining blocks of object
code from the same program, or a mixture of both.
• The linker program is used to recombine the
blocks of object code in RAM to get a working full
program.
• Linker is helpful if there is a shortage of RAM.

33. Translators - Loader
• A loader is a piece of software that chooses
exactly where to put object code in RAM, ready for
it to be run.
• It also adjusts the memory references in programs.

34. Translators - Loader
• Programs can be written by programmers using
either ‘absolute addressing’ or ‘relative addressing’.
• Relative addressing is more common because then
the loader can put the program anywhere in RAM -
absolute addressing isn't flexible.
• Linker & Loader may overlap.

35. Translators - Loader

36. Translators - Cross-Compiler
• If the compiled program can run on a computer
whose C.P.U or O.S is different from the one on
which the compiler runs, the compiler is known
as a cross-complier.

37. Translators - Cross-Compiler

38. Translator – Language Converter
• Also called Language Translator / Source to
source translator.
• It converts programs in one high-level language to
another high-level language.
• Ex: Cfront converts C++ into C language.

39. Translator – Language Rewriter
• It is a program that changes
form of expression of the same
language.
• It does not changes the
language of source code.

40. Translator - Decompiler
• It is a piece of software that converts the low-level
language to high-level language .
• It is not as famous, but may prove a useful tool
sometimes.
• Ex: JD Compiler, .JAD decompiler, NET Reflector

41. Translator – Compiler-Compiler
• It is a tool that creates a compiler, interpreter or
parser from the information provided on formal
description of any language.
• The earliest & most common type is parser-
generator.
• It is also called compiler-generator.
• Ex: Yacc, JavaCC, etc.

42. CONTACT ME AT:
Akhil Kaushik
akhilkaushik05@gmail.com
9416910303
CONTACT ME AT:
Akhil Kaushik
akhilkaushik05@gmail.com
9416910303
Thank You !!!