C Program Compilation

Abstract

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• Convert from C program to Instruction, then execute it as a Process (进程)

Important

We usually use gcc which stands for GNU Compiler Collection, a program that handles the 5 steps program compilation for us.

gcc -Wall program.c tells the C compilers to give all possible warnings.

Stage 1

gcc -E hello_world.c

• Preprocessor generates expanded .I file
• Process Pre-processor Directives
• Replace all the Macro Expansion in the Header File & program files
• Would’t complain about missing Header File
• Is done by a program called cpp
• Remove spaces, new lines & comments

Stage 2

gcc -S hello_world.c

• Compiler generates codes in Assembly language in .s format
• Returns error & warnings if the Header File isn’t defined
• Is done by a program called cc1

Stage 3

gcc -c hello_world.c

• Assembler generate Instruction in .o format
• Essential for code sharing and dynamic linking in software development
• Is done by a program called as

Stage 4

• Linker Link up with other Instruction which are dependencies of the program we wrote
• Sometimes we will break the program into many different c files, then run compiler on each, and link up all. This is for easier management & debugging
• Output executable format or library file
• We can use ldd to show the dependencies
• Will return error if unable to link up some of the required .o files
• Is done by a program called ld

Stage 5

• Loader loads the executable from Disk to Main Memory to create a Process (进程). This part is handled by the OS

References

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• C Language Source Code to EXE
• [Modern OS - 1.8.3 Large Programming Projects](https://csc-knu.github.io/sys-prog/books/Andrew%20S.%20Tanenbaum%20-%20Modern%20Operating%20Systems.pdf#Large Programming Projects)