c4

c4 - C in four functions: https://github.com/rswier/c4/ c4x86 - JIT compiler for x86 in 86 lines: https://github.com/EarlGray/c4

This is not terribly hard, though,—Forth implementations have long explored[1] the road from emiting a list of VM instructions (“token threading”) to emitting a list of VM instruction implementation entry points (“direct threading”, although “indirect threading” arguably fits this as well) to emitting a stream of call instructions targeting said entry points (“subroutine threading”) to copying the implementation bodies into the stream (“inline threading”). With sufficient dedication, you can even cut out the bodies from the binary the compiler of your high-level implementation language produced, to piggyback on its target support. Gforth[2] among others does this in the land of Forth, but the more well-known implementation is perhaps the dyngen code generator[3] used in Qemu before the switch to TCG in version 0.10. Generating machine cod

Not so much "obfuscated C" as it is "embedding a binary into a C program". You can still do something similar with modern compilers: char code[] = { /* put your bytes here */ }; ((void(*)())code)(); I believe it is technically UB, but it does exactly what you'd think it does, and if compilers started doing funny things with it, you wouldn't be able to write things like JITs at all. A tiny demonstration of this can be found at the bottom of C4x86: https://github.com/EarlGray/c4/blob/master/c4x86.c

I think the beauty of it is the that's it!? feeling you get once you've looked through all ~500 lines --- based on the amount of functionality one would expect it to be much longer; but it is unexpectedly short, yet complete. For a just-as-interesting "sequel", look at C4x86: https://github.com/EarlGray/c4

c4 with tiny x86 JIT: https://github.com/EarlGray/c4 https://github.com/EarlGray/c4/blob/master/c4x86.c