Hacktical C: practical hacker's guide to the C programming language

> The reason I believe C is and always will be important is that it stands in a class of its own as a mostly portable assembler language, offering similar levels of freedom.

When your computer is a PDP-11, otherwise it is a high level systems language like any other.

Less controversially, when you write C, you write for a virtual machine described by the C spec, not your actual hardware.

Your C optimizer is emulating that VM when performing symbolic execution, and the compiler backend is cross-compiling from it. It's an abstract hardware that doesn't have signed overflow, has a hidden extra bit for every byte of memory that says whether it's initialized or not, etc.

Assembly-level languages let you write your own calling conventions, arrange the stack how you want, and don't make padding bytes in structs cursed.

These are all such nonsensical misinterpretations of what people mean when they say C is "low level". You absolutely don't write C for the C abstract machine, because the C spec says nothing about performance, whereas performance is one of the primary reasons people write C.

The existence of undefined behaviour isn't proof that there is a C "virtual machine" that code is being run on. Undefined behaviour is a relaxation of requirements on the compiler. The C abstract machine doesn't not have signed overflow, rather it allows the compiler to do what it likes when signed overflow is encountered. This is originally a concession to portability, since the common saying is not that C is close to assembly, but rather that it is "portable" assembler. It is kept around because it benefits performance, which is again one of the primary reasons people write C.

C performance exists thanks to UB, and the value optimising compilers extract out of it, during the 8 and 16 bit home computers days any average Assembly developer could write better code than C compiler were able to spit out.

And also because it doesn't get in your way of doing exactly what you want to do.

If that was true then the optimizers wouldn't need to exist in the first place.

Compared to the alternatives.

It gets very frustrating to communicate at this level.

I don't think compilers allowing trash through is a good thing.

Have you ever seen the error steamroller? https://github.com/mattdiamond/fuckitjs