Why aren't programs written in Assembly more often? [closed]

Question

Hellо, I am a compiler.

I just scanned thousands of lines of code while you were reading this sentence. I browsed through millions of possibilities of optimizing a single line of yours using hundreds of different optimization techniques based on a vast amount of academic research that you would spend years getting at. I won't feel any embarrassment, not even a slight ick, when I convert a three-line loop to thousands of instructions just to make it faster. I have no shame to go to great lengths of optimization or to do the dirtiest tricks. And if you don't want me to, maybe for a day or two, I'll behave and do it the way you like. I can transform the methods I'm using whenever you want, without even changing a single line of your code. I can even show you how your code would look in assembly, on different processor architectures and different operating systems and in different assembly conventions if you'd like. Yes, all in seconds. Because, you know, I can; and you know, you can't.

P.S. Oh, by the way you weren't using half of the code you wrote. I did you a favor and threw it away.

ASM has poor legibility and isn't really maintainable compared to higher-level languages.

Also, there are many fewer ASM developers than for other more popular languages, such as C.

Furthermore, if you use a higher-level language and new ASM instructions become available (SSE for example), you just need to update your compiler and your old code can easily make use of the new instructions.

What if the next CPU has twice as many registers?

The converse of this question would be: What functionality do compilers provide?

I doubt you can/want to/should optimize your ASM better than gcc -O3 can.

I've written shedloads of assembler for the 6502, Z80, 6809 and 8086 chips. I stopped doing so as soon as C compilers became available for the platforms I was addressing, and immediately became at least 10x more productive. Most good programmers use the tools they use for rational reasons.

I love programming in assembly language, but it takes more code to do the same thing as in a high-level languge, and there is a direct correlation between lines of code and bugs. (This was explained decades ago in The Mythical Man-Month.)

It's possible to think of C as 'high level assembly', but get a few steps above that and you're in a different world. In C# you don't think twice about writing this:

foreach (string s in listOfStrings) { /* do stuff */ }

This would be dozens, maybe hundreds of lines of code in assembly, each programmer implementing it would take a different approach, and the next person coming along would have to figure it out. So if you believe (as many do) that programs are written primarily for other people to read, assembly is less readable than the typical HLL.

Edit: I accumulated a personal library of code used for common tasks, and macros for implementing C-like control structures. But I hit the wall in the 90s, when GUIs became the norm. Too much time was being spent on things that were routine.

The last task I had where ASM was essential was a few years ago, writing code to combat malware. No user interface, so it was all the fun parts without the bloat.

In addition to other people's answers of readability, maintainability, shorter code and therefore fewer bugs, and being much easier, I'll add an additional reason:

program speed.

Yes, in assembly you can hand tune your code to make use of every last cycle and make it as fast as is physically possible. However who has the time? If you write a not-completely-stupid C program, the compiler will do a really good job of optimizing for you. Probably making at least 95% of the optimizations you'd do by hand, without you having to worry about keeping track of any of it. There's definitely a 90/10 kind of rule here, where that last 5% of optimizations will end up taking up 95% of your time. So why bother?