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

I’ll cover these stages in future posts.

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