Unit-1compiler design and its lecture note .pptx
- 1. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 1 Compiler Design Unit – 4 Pushdown Automata Chapter One Introduction to Compiler
- 2. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 2 Topics to be covered Translator Analysis synthesis model of compilation Phases of compiler Difference between compiler & interpreter Types of compiler Context of compiler (Cousins of compiler) Pass structure
- 3. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 3 Translator A translator is a program that takes one form of program as input and converts it into another form. Types of translators are: 1. Compiler 2. Interpreter 3. Assembler Error Messages Translator Source Program Target Program (If any)
- 4. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 4 Compiler A compiler is a program that reads a program written in source language and translates it into an equivalent program in target language. Error Messages Compiler void main() { int a=1,b=2,c; c=a+b; printf(“%d”,c); } Source Program 0000 1100 0010 0100 0111 1000 0001 1111 0101 1110 1100 0000 1000 1011 Target Program (If any)
- 5. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 5 Interpreter Interpreter is also program that reads a program written in source language and translates it into an equivalent program in target language Interpreter Source Program Target Program line by line. Void main() { int a=1,b=2,c; c=a+b; printf(“%d”,c); } 0000 1100 0010 0000 1111 1010 1100 0010 0011 1100 0010 1111 1100 0010 Error Messages (If any)
- 6. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 6 Assembler • Assembler is a translator which takes the assembly code as an input and generates the machine code as an output. Assembler MOV id3, R1 MUL #2.0, R1 MOV id2, R2 MUL R2, R1 MOV id1, R2 ADD R2, R1 MOV R1, id1 Assembly Code 0000 1100 0010 0100 0111 1000 0001 1111 0101 1110 1100 0000 1000 1011 1100 0000 1000 Machine Code Error Messages (If any)
- 7. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 7 Analysis synthesis model of compilation
- 8. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 8 Analysis synthesis model of compilation There are two part of compilation. 1. Analysis Phase 2. Synthesis Phase Analysis Phase Synthesis Phase Intermediate Representation void main() { int a=1,b=2,c; c=a+b; printf(“%d”,c); } Source Code 0000 1100 0111 1000 0001 1111 0101 1000 1011 Target Code
- 9. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 9 Analysis phase & Synthesis phase Analysis Phase Analysis part breaks up the source program into constituent pieces and creates an intermediate representation of the source program. Analysis phase consist of three sub phases: 1. Lexical analysis 2. Syntax analysis 3. Semantic analysis Synthesis Phase The synthesis part constructs the desired target program from the intermediate representation. Synthesis phase consist of the following sub phases: 1. Code optimization 2. Code generation
- 10. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 10 Phases of compiler
- 11. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 11 Phases of compiler Compiler Analysis phase Synthesis phase Lexical analysis Syntax analysis Semantic analysis Intermediate code generation Code optimization Code generation
- 12. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 12 Lexical analysis Position = initial + rate*60 Lexical analysis id1 Lexical Analysis is also called linear analysis or scanning. Lexical Analyzer divides the given source statement into the tokens. Ex: Position = initial + rate * 60 would be grouped into the following tokens: Position (identifier) = (Assignment symbol) initial (identifier) + (Plus symbol) rate (identifier) * (Multiplication symbol) 60 (Number) = id2 + id3 * 60
- 13. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 13 Phases of compiler Compiler Analysis phase Synthesis phase Lexical analysis Syntax analysis Semantic analysis Intermediate code generation Code optimization Code generation
- 14. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 14 Syntax analysis Position = initial + rate*60 Syntax analysis id1 = id2 + id3 * 60 Syntax Analysis is also called Parsing or Hierarchical Analysis. The syntax analyzer checks each line of the code and spots every tiny mistake. If code is error free then syntax analyzer generates the tree. Lexical analysis = id1 + id2 * id3 60
- 15. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 15 Phases of compiler Compiler Analysis phase Synthesis phase Lexical analysis Syntax analysis Semantic analysis Intermediate code generation Code optimization Code generation
- 16. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 16 Semantic analysis Semantic analyzer determines the meaning of a source string. It performs following operations: 1. matching of parenthesis in the expression. 2. Matching of if..else statement. 3. Performing arithmetic operation that are type compatible. 4. Checking the scope of operation. = id1 + id2 * id3 60 Semantic analysis = id1 + id2 * id3 inttoreal 60 int to real *Note: Consider id1, id2 and id3 are real
- 17. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 17 Phases of compiler Compiler Analysis phase Synthesis phase Lexical analysis Syntax analysis Semantic analysis Intermediate code generation Code optimization Code generation
- 18. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 18 Intermediate code generator Two important properties of intermediate code : 1. It should be easy to produce. 2. Easy to translate into target program. Intermediate form can be represented using “three address code”. Three address code consist of a sequence of instruction, each of which has at most three operands. = id1 + id2 * id3 inttoreal 60 Intermediate code t1= int to real(60) t2= id3 * t1 t3= t2 + id2 id1= t3 t1 t2 t3
- 19. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 19 Phases of compiler Compiler Analysis phase Synthesis phase Lexical analysis Syntax analysis Semantic analysis Intermediate code generation Code optimization Code generation
- 20. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 20 Code optimization It improves the intermediate code. This is necessary to have a faster execution of code or less consumption of memory. Intermediate code t1= int to real(60) t2= id3 * t1 t3= t2 + id2 id1= t3 Code optimization t1= id3 * 60.0 id1 = id2 + t1
- 21. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 21 Phases of compiler Compiler Analysis phase Synthesis phase Lexical analysis Syntax analysis Semantic analysis Intermediate code generation Code optimization Code generation
- 22. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 22 Code generation The intermediate code instructions are translated into sequence of machine instruction. Code generation MOVF id3, R2 MULF #60.0, R2 MOVF id2, R1 ADDF R2,R1 MOVF R1, id1 Code optimization t1= id3 * 60.0 id1 = id2 + t1
- 23. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 23 Phases of compiler Symbol table Error detection and recovery Lexical analysis Code optimization Syntax analysis Semantic analysis Intermediate code Code generation Target Program Source program Analysis Phase Synthesis Phase Sr. Variable Name Type Address 1 Position Float 0001 2 Initial Float 0005 3 Rate Float 0009
- 24. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 24 Exercise Write output of all the phases of compiler for following statements: 1. x = b-c*2 2. I=p*n*r/100
- 25. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 25 Difference between compiler & interpreter Compiler Interpreter Scans the entire program and translates it as a whole into machine code. It translates program’s one statement at a time. It generates intermediate code. It does not generate intermediate code. Memory requirement is more. Memory requirement is less. An error is displayed after entire program is checked. An error is displayed for every instruction interpreted if any. Example: C compiler Example: Basic, Python, Ruby
- 26. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 26 Context of Compiler (Cousins of compiler)/Language Processing
- 27. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 27 Context of compiler (Cousins of compiler) Preprocessor Skeletal Source Program It performs the following functions: 1. Macro processing 2. File inclusion 3. Rational preprocessor 4. Language extensions Preprocessor
- 28. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 28 Context of compiler (Cousins of compiler) Preprocessor Skeletal Source Program 1. Macro processing: Allows user to define macros. Macro is shorthand for longer constructs. Ex: #define PI 3.14159265358979323846 2. File inclusion: A preprocessor may include the header file into the program. Ex: #include<stdio.h> 3. Rational preprocessor: It provides built in macro for construct like while statement or if statement. Preprocessor
- 29. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 29 Context of compiler (Cousins of compiler) Preprocessor Skeletal Source Program 4. Language extensions: Add capabilities to the language by using built-in macros. • Ex: the language equal is a database query language embedded in C. • Statement beginning with ## are taken by preprocessor to be database access statement unrelated to C and translated into procedure call on routines that perform the database access. Preprocessor
- 30. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 30 Context of compiler (Cousins of compiler) Preprocessor Compiler Skeletal Source Program Source Program • A compiler is a program that reads a program written in source language and translates it into an equivalent program in target language. Compiler
- 31. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 31 Context of compiler (Cousins of compiler) Preprocessor Compiler Assembler Skeletal Source Program Source Program Target Assembly Program • Assembler is a translator which takes the assembly program (mnemonic) as an input and generates the machine code as an output. Assembler
- 32. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 32 Context of compiler (Cousins of compiler) Preprocessor Compiler Assembler Skeletal Source Program Source Program Target Assembly Program Relocatable Object Code Libraries & Object Files • Linker makes a single program from a several files of relocatable machine code. • These files may have been the result of several different compilation, and one or more library files. Linker Linker / Loader
- 33. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 33 Context of compiler (Cousins of compiler) Preprocessor Compiler Assembler Skeletal Source Program Source Program Target Assembly Program Relocatable Object Code Absolute Machine Code Libraries & Object Files • The process of loading consists of: 1. Taking relocatable machine code. 2. Altering the relocatable address. 3. Placing the altered instructions and data in memory at the proper location. Loader Linker / Loader
- 34. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 34 Front end & back end (Grouping of phases) Front end: Depends primarily on source language and largely independent of the target machine. It includes following phases: 1. Lexical analysis 2. Syntax analysis 3. Semantic analysis 4. Intermediate code generation 5. Creation of symbol table Back end: Depends on target machine and do not depend on source program. It includes following phases: 6. Code optimization 7. Code generation phase 8. Error handling and symbol table operation
- 35. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 35 Pass structure
- 36. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 36 Pass structure One complete scan of a source program is called pass. Pass includes reading an input file and writing to the output file. In a single pass compiler analysis of source statement is immediately followed by synthesis of equivalent target statement. While in a two pass compiler intermediate code is generated between analysis and synthesis phase. It is difficult to compile the source program into single pass due to: forward reference
- 37. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 37 Pass structure Forward reference: A forward reference of a program entity is a reference to the entity which precedes its definition in the program. This problem can be solved by postponing the generation of target code until more information concerning the entity becomes available. It leads to multi pass model of compilation. In Pass I: Perform analysis of the source program and note relevant information. In Pass II: Generate target code using information noted in pass I.
- 38. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 38 Effect of reducing the number of passes It is desirable to have a few passes, because it takes time to read and write intermediate file. If we group several phases into one pass then memory requirement may be large.
- 39. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 39 Types of compiler
- 40. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 40 Types of compiler 1. One pass compiler • It is a type of compiler that compiles whole process in one-pass. 2. Two pass compiler • It is a type of compiler that compiles whole process in two-pass. • It generates intermediate code. 3. Incremental compiler • The compiler which compiles only the changed line from the source code and update the object code. 4. Native code compiler • The compiler used to compile a source code for a same type of platform only. 5. Cross compiler • The compiler used to compile a source code for a different kinds platform.
- 41. Unit – 1 : Introduction to Compiler Darshan Institute of Engineering & Technology 41 End of Unit-1