What are the stages of C compilation?

C compilation goes through several stages. For clang, the C compiler on my machine, these are:

+----+        +----+           +-----+       +---------+       +----+       +----+       +-----------+
| .c |--cpp-->| .i |--parser-->| AST |--??-->| LLVM IR |--??-->| .s |--as-->| .o |--ld-->| a.out/.so |
+----+        +----+           +-----+       +---------+       +----+       +----+       +-----------+

Take main.c, preprocess to produce tokens (a .i file). This is done by the C preprocessor, cpp.
Take tokens, parse into AST.
Take AST, produce LLVM IR (“Intermediate Representation”).
Take LLVM IR, produce assembly (a .s file).
Take assembly, produce object file (a .o file). This is done by the assembler, as.
Take object file, produce executable (a.out) or dynamic library (.so).

I’ll cover these stages in future posts.

What can computers do? What are the limits of mathematics? And just how busy can a busy beaver be? This year, I’m writing Busy Beavers, a unique interactive book on computability theory. You and I will take a practical and modern approach to answering these questions — or at least learning why some questions are unanswerable!

It’s only $19, and you can get 50% off if you find the discount code ... Not quite. Hackers use the console!

After months of secret toil, I and Andrew Carr released Everyday Data Science, a unique interactive online course! You’ll make the perfect glass of lemonade using Thompson sampling. You’ll lose weight with differential equations. And you might just qualify for the Olympics with a bit of statistics!

It’s $29, but you can get 50% off if you find the discount code ... Not quite. Hackers use the console!

More by Jim

Tagged . All content copyright James Fisher 2017. This post is not associated with my employer. Found an error? Edit this page.