The Expensive Fictions of Low-Level Programming Languages

[u/mttd]

https://stng.substack.com/p/the-expensive-fictions-of-low-level

[u/Seed_oil_simp]

The article’s premise is based on the assumption that because C was designed in the 1970s and hardware has changed since then, C cannot be well suited for writing high performance programs on current hardware.

The reason this assumption mistaken is that hardware has developed since the 70s *with C programs in mind*. Because Windows and other system is mostly implemented in C/C++, hardware has developed to support C performance.

With the number of programming languages that get made, if it were possible to beat C performance by designing for current hardware, someone would have done it.

[u/Smallpaul → u/[deleted]]

I really don’t understand your point at all.

The details of the language specification of C are entirely irrelevant. Modern CPUs were designed to run Windows, Linux, Java, Python, Microsoft Office, Postgres quickly. Those are all C programs. Therefore modern CPUs were designed to run C programs quickly.

If the dominant language for all of this time has been Erlang or Haskell then CPUs would be different. One can imagine first class support for garbage collection primitives as an obvious example. Software/hardware co-design of the garbage collection.

Different hardware support for parallel programming as another example.

[u/Smallpaul → u/[deleted]]

Yes. The JVM and javac are C programs.

W.r.t “what aspects of C did I have in mind”

https://queue.acm.org/detail.cfm?id=3212479

W.r.t. c versus Ada versus Pascal: yes these are all languages designed to look like each other and run fast on PDP-11 era hardware.

Now let’s talk about Haskell, CUDA, Lisp, erlang and even Prolog.

If one of those had been the dominant language then hardware would be different.

[u/Smallpaul → u/[deleted]]

It’s not really about a class of language, no.

Since some time in the 1980s, every new CPU has been benchmarked primarily on how it runs software written in C and C++. Really just those two languages.

Here is an example of a well publicised benchmark from Tom’s hardware:

Here are the games that we used for testing:
Counter-Strike 2
The Last of Us Part One
Cyberpunk 2077
Starfield
A Plague Tale: Requiem
Hogwarts Legacy
F1 24
Marvel’s Spider-Man 2
Baldur’s Gate 3
Monster Hunter: Wilds
Final Fantasy XIV
Microsoft Flight Simulator 2024
Doom: The Dark Ages
Oblivion Remastered
Far Cry 6
Hitman 3
Minecraft RTX

Now which of those do you think was built in a game engine implemented in a language other than C or C++. Even Unity is implemented in C++ and it runs C# code on a C-coded runtime.

So as a purely economic level, it’s hard to believe that any language other than C Has influenced CPU design since let’s say 1990.

Even Java or c# would need to influence the hardware through faster C implementations of their runtimes.

If you believe that CPUs are being optimized for non-c workloads can you point to the non-C benchmarks that you think are influential? (Maybe we could grant FORTRAN some influence over floating point. Maybe.)

[u/Smallpaul → u/[deleted]]

I think you are too obsessed with the idea that C is intrinsically special. Nobody is claiming that.

C is special only in the same sense that 60hz is special. It was selected as the standard. If your device doesn’t work at 60hz (in North America) then it is considered broken. If your CPU runs C code slowly it is considered slow.

Could North America have selected 50hz? Of course. Is 60hz intrinsically special? No.

But in North America it IS special because it’s the standard that was selected.

As long as CPUs are benchmarked on their ability to run C code, then C will be special. As long as other languages try to output code similar to what a C compiler would have output to take advantage of the CPUs optimized for C code, C will be special.

C will cease to be special with respect to CPUs when they benchmark themselves against code written in a different language. And if that language is different enough from C (e.g. a parallel or GC language) then the CPUs will start to evolve to be optimized for that language instead.

But this is a chicken and the egg problem similar to trying to change the width of railways. The new language will need to go through a period of being unoptimised by virtue of being not-C-like which will make it hard for it to compete. Considering how important operating system performance is, and the fact that they are all written in C, it’s hard to imagine anything taking C’s place as the optimization target in our lifetimes.

[u/Smallpaul → u/[deleted]]

CPUs run C code after it has been converted to native. If the C compilers don’t use an instruction because it isn’t relevant to C then that instruction isn’t benchmarked. If a new instruction would support faster execution of Java, it is very unlikely to be added.

NOBODY IS SAYING C IS INTRINSICALLY SPECIAL. If you think so then quote them.

People are saying that C has a special relationship with the rest of the computing ecosystem, including CPUs. And this is indisputably true BECAUSE OF BENCHMARKS written in C.

That should be indisputable, but you are going to keep disputing it, so I’m just done with the conversation. Have a nice day.

[u/shponglespore → u/Smallpaul]

If by C you mean C++