1. Lecture-1 Compilation process

2. C Compilation process Components of Compiler Preprocessor Compiler
Source code( .c file)
Preprocessor
Compiler
Assembly code
Components of Compiler
Assember
Libraries
Object code
Linker
Executable file

3. Preprocessor /* this is demo */ #include<stdio.h> void main() {
printf (“hello”); }
Preprocessor
code of stdio.h file
void main() {
printf (“hello”); }
Preprocessor remove comments and include header files in source code, replace macro name with code.

4. Compiler code of stdio.h file void main() { printf (“hello”); }
push ebp
mov ebp, esp
and esp, -16
sub esp, 16
mov eax, OFFSET FLAT:.LC0
mov DWORD PTR [esp], eax
call printf
leave
ret
Compiler generate assebmly code.

5. Assembler
push ebp
mov ebp, esp
and esp, -16
sub esp, 16
mov eax, OFFSET FLAT:.LC0
mov DWORD PTR [esp], eax
call printf
leave
ret
Assembler
Assebler convert assemble code into object code.

6. Linker
Libraries
Linker

7. Linker: Static linking
one()
#include<stdio.h>
void main()
{ one(); }
Libraries
Call function one()
Linker
Code of function one included in final executable file.

8. Linker: Static Linking
Code of file 1 calling 200 funtions.
Code of file 2 calling 100 functions.
Libraries
Object file1
Object file2
Linker
Size ?

9. Linker:Static Linking1
exe file generated. 4
Again compilation needed so that exe file include updated one function. 2
User take exe file. 3
Some changes made in one function.
Libraries
010100

10. Linker: Dynamic linking
one()
#include<stdio.h>
void main()
{ one(); }
Libraries
Call function one()
0x2EA126
One function
Library
Linker
Address of one function in memory
Memory address, where one function is loaded , included in final executable file.
Memory

11. Linker: Dynamic Linking
Benefits over static linking
Size
No need to compile

12. Library Static Library Dynamic Library Windows .lib (Library)
Linux .a (Archive)
Dynamic Library
Windows .dll (Dynamic link library)
Linux .so (Shared object)

13. Commands Linux (gcc) Preprocessor step ( gcc -E <filename>)
Compiler step( gcc -S <filename>)
Generate Object code(gcc -O <filename>)
Generate executable (gcc <object code>)