The document discusses parse trees and syntax trees, which represent the grammatical and syntactic structures of sentences and code, respectively. It also covers the concept of three address code (TAC), an intermediate representation in compiler design that simplifies analysis and optimization, outlining its advantages, structure, and types of instructions. In conclusion, both parse and syntax trees, along with TAC, play crucial roles in natural language processing, compiler design, and optimization techniques.

1. NADAR SARASWATHI COLLEGE OF ARTS AND SCIENCE
By
M.PrathiYat
hi
I M.Sc(CS)
PARSE TREE AND SYNTAX TREE
Compiler design

2. What is a Parse Tree?
Definition
A parse tree is a tree-like structure
that represents the grammatical
structure of a sentence or a code
snippet according to a formal
grammar.
Purpose
Parse trees are used in parsing, a
process of analyzing a string of
symbols to determine its grammatical
structure.
Key Features
Nodes represent grammatical units,
and edges represent the hierarchical
relationships between them.

3. What is a Syntax Tree?
Definition
A syntax tree is a tree-like
structure that represents the
syntactic structure of a code
snippet according to a
programming language's
grammar.
Purpose
Syntax trees are used in
compilers and interpreters to
analyze and understand the
structure of programs.
Key Features
Nodes represent the syntactic elements of the program, and edges
represent the hierarchical relationships between them.

4. Introduction to
Parse Trees and
Syntax Trees
Parse trees and syntax trees are fundamental data structures used in
computer science for analyzing and representing the grammatical
structure of sentences and code. They provide a visual and hierarchical
representation of how language is structured.

5. Constructing a Parse Tree
Step 1
Start with the sentence as
the root node.
Step 2
Break down the sentence
into its constituent parts,
such as noun phrases and
verb phrases.
Step 3
Continue breaking down
each part until you reach
the individual words.
Step 4
Label each node with its
grammatical category.

6. Constructing a Syntax
Tree
1 Step 1
Begin with the individual
lexical tokens, such as
variables, operators, and
constants.
2 Step 2
Combine the tokens
according to the grammar
rules, forming larger
syntactic units.
3 Step 3
Continue combining units
until you reach the root
node, representing the
entire code snippet.
4 Step 4
Label each node with its
type, such as variable,
operator, or expression.

7. Applications of Parse Trees and
Syntax Trees
Natural Language Processing
Parse trees are essential for understanding the grammatical structure of sentences, enabling
tasks like machine translation and sentiment analysis.
Compilers and Interpreters
Syntax trees are crucial for analyzing and understanding the structure of code, enabling tasks
like code optimization and error detection.
Search Engines
Parse trees are used to understand the meaning of queries and retrieve relevant results from
a database.

8. Conclusion and Key
Takeaways
1 Parse Trees
Analyze the grammatical structure of sentences, essential for
natural language processing tasks.
2 Syntax Trees
Represent the syntactic structure of code, crucial for compilers
and interpreters.
3 Applications
Parse trees and syntax trees are widely used in computer
science, enabling tasks like machine translation, code
optimization, and search engines.

9. Three Address
Code: An Overview
Three address code (TAC) is a fundamental concept in compiler design.
It's a low-level intermediate representation (IR) of code, used to simplify
program analysis and optimization before machine code generation.

10. Advantages of Three Address
Code
1 Simplified Analysis
TAC's linear structure simplifies
data flow and control flow
analysis, aiding in optimization
and code generation.
2 Enhanced Readability
TAC's clear and concise
representation makes it easier
for humans to understand the
program logic and identify
potential issues.
3 Machine-Independent
TAC is independent of the target
machine's architecture, making it
versatile and portable across
different platforms.
4 Optimization
Foundation
TAC provides a solid base for
various code optimization
techniques, including constant
propagation and dead code
elimination.

11. Representation of Three Address Code
General Form
TAC generally represents instructions
as triplets of the form:
1. result = operand1 operator
operand2
Where result, operand1, and
operand2 are variables or constants.
Example
The expression x + y * z would be
represented in TAC as:
1. t1 = y * z
2. t2 = x + t1
Where t1 and t2 are temporary
variables.
Types of Instructions
TAC can handle various instruction
types, including assignment,
arithmetic, logical, and control flow
operations.

12. Quadrupled Three Address
Code
Operator Operand 1 Operand 2 Result
+= x 5 x
* y z t1
= t1 None result

13. Benefits of Quadrupled
Three Address Code
Structured
Representation
Quadruples offer a structured
representation of TAC, making it
easier to analyze and manipulate
the code during optimization.
Efficient Optimization
The clear separation of operands
and results in quadruples allows
for efficient application of
various optimization techniques.
Code Generation Simplification
The organized structure of quadruples simplifies the process of
generating machine code from the intermediate representation.

14. Triples Three Address Code
Compact Representation
Triples use a compact representation, storing only the essential
information for each instruction, minimizing storage
requirements.
Implicit Information
Some information, like the operator, might be implicitly
understood from the context, reducing redundancy and
simplifying the representation.
Efficient Storage
The compact structure of triples can lead to efficient storage
utilization and faster access to individual instructions.

15. Advantages of Triples Three
Address Code
Compactness
Triples provide a space-efficient representation, reducing memory overhead and improving
performance.
Efficiency
The compact structure allows for faster processing and manipulation during code
optimization and generation.
Simplification
Triples can simplify certain optimization techniques by providing a clear and concise
representation of the code.

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