The document discusses compiler passes, detailing three types of compilers: single pass, two pass, and multi pass. It explains that single pass compilers run the source code once, while two pass and multi pass compilers process the code multiple times for better optimization and generation. Comparisons highlight that single pass compilers are faster but less efficient compared to multi pass compilers, which provide better code optimization at the cost of speed.

1. Compiler Passes
PRESENTATION BY • SANJAY SINGH

2. Agenda
 Pass
 Single Pass Compiler
 Two Pass Compiler
 Multi Pass Compiler
 Comparisons
 Conclusion

3. Pass
• A pass refers to the traversal of a compiler through the entire program.
• Pass is a group of phases implemented together.
• Majorly, there are three types of compilers:
1. Single Pass Compilers
2. Two Pass Compilers
3. Multi Pass Compilers

4. Single Pass Compiler
• When we merge all the phases of compiler
design in a single module, then it is called a single
pass compiler.
• A single pass compiler runs the source code only
one time.
• In single pass Compiler source code directly
transforms into machine code.
• It is also called a "Narrow compiler. It has limited
scope

5. Two Pass Compiler
• A processor that runs through the program to be translated twice is
considered a two-pass compiler.
• First Pass : is refers as
 Front End
 Analytic Part
 Platform Independent
• Second Pass : is refers as
 Back End
 Synthesis Part
 Platform Dependent
Lexical Analysis
Syntax Analysis
Semantic Analysis
Intermediate Code
Generation
Code Optimization
Target Code Generation

6. Multi Pass Compiler
• The multi-pass compiler processes the source code
several times.
• It divided a large program into multiple small programs
and process them. It develops multiple intermediate
codes.
• All of these multi-pass take the output of the previous
phase as an input.
• It is also known as ‘Wide Compiler’. As it can scan every
portion of the program.

7. Comparisons
SINGLE PASS COMPILER
1. Uses more space than multi pass
compilers.
2. Faster than multi pass as there is no
reading and writing of intermediate
files.
3. Less efficient code optimization and
code generation.
4. Example – Pascal & Tiny C
MULTI PASS COMPILER
1. Uses less space than single pass
compilers.
2. Slower than single pass compiler,
due to reading and writing of
intermediate files.
3. Better code optimization and code
generation.
4. Example – Java, GCC

8. Conclusion
 If we want to design a compiler for different programming language for same
machine, there is requirement of making Front end/first pass for each of
them and only one Back end/second pass.
 If we want to design a compiler for same programming language for different
machine/system, we make different Back end for different Machine/system
and make only one Front end for same programming language.

9. Thank You