Other than assembly language, all languages embody abstractions.
I find understanding certain abstractions hard going because they don't mesh well with my view of the problem domain and my design for solution's implementation.
I find understanding certain abstractions hard going because they don't mesh well with my view of the problem domain and my design for solution's implementation.
Essentially the processor reads a while bunch of instructions at once, splits each in the raw microinstructions, arranges them in a graph of dependencies, and then solves an optimization problem to find the best way to schedule nodes from that graph onto its internal execution pipelines. In real-world execution, you can't even tell what assembly instruction(s ) are the ones being executed at a partocular time - disparate parts of various instructions. Some instructions, like "mov ax, 0", don't even execute: they just serve to mark which the tens of real registers is now free to use for another symbolic register like bx.
No matter what the cpu does internally to arrive at producing the requested output from the supplied instructions, it DOES produce exactly the reqested and expected output from the given instructions.
What it does not do is for example maybe a + operator doesn't mean the same thing after some unknowable prior step changed the definition of +, or flatly not provide a means to manipulate some data in a way that a language author thought was crazy and no one could ever have a valid reason to do $thing like idk execute a string or something. Sure there are now optional settings and features you could consciously use, for example to enforce that data/exec seperation, but it doesn't just do it by it's own magic according to someone else's rules instead of your own code.
Even assembly itself has symbols and labels, which are themselves abstractions.
Of course assembly is an abstraction, but it is the lowest level programming language that ordinary mortals can still write code in, which was the point the GP was making.
Exactly nobody writes applications in microcode. Register aliasing and speculative execution have under normal circumstances no effect other than some performance which if the CPU just did as it was told by the assembly code (or actually, the machine code, the binary representation of the possibly optimized assembly) would still work exactly as advertised. You can also switch those off if they're features of the assembler, and if the CPU does them then you're going to have to live with it.
If you really wanted to make the point that Assembly is an abstraction then macros would have probably been a better thing to mention.
Besides the issue of security, performance is also a thing. If you’re trying to squeeze every last cycle out of your program then you need to understand CPU cache hierarchies at the very least. That’s at a level far below assembly language, digging down into the physical layout of the machine.
You could make the same, useless, argument about the raw binary. If you looked at an executable you are still actually only looking at a transcoded representation in ascii in an editor. The cpu doesn't actually know what 0A is, those are glyphs for numbers and letters in a human language.
Assembler mnemonics are not materially different, and even macros don't change this because the macros are macros, built out of other visible assembler not hidden magic.
You are not conducting useful argument or communication with this silliness.
They do hide things. There are often multiple ways to encode a line of assembly into machine code. For example on x86, JMP can take an 8-, 16-, or 32-bit displacement, and the assembler will usually select the shortest encodable variant. Some instructions have a shorter variant for certain registers, like ADD $1, %eax. You add useless REX prefixes.
The cpu magic doesn't do things you didn't ask for, or can't figure out how to ask for through a bunch of indirection.
All the cpu magic means is that you don't know how it did exactly what you expected. It still produced exactly and only the expected output from the given input.
High level language magic means it does things you didn't expect, and that you can have a hard time figuring out how to get it to do something you want if that doesn't happen to be one of the things the language designers predicted and decided for you that you should ever need to do.
You think C is "low level", but it was once considered "high level", and the compiler does many things you don't want, and the standard's ambiguously-worded, and implementers have their own interpretations about the ambiguity, and also bugs in their compilers, and you eventually arrive at:
"If you really want those instructions to happen in this function, without fear of magic, write them in assembly."
I just move atoms until the program I desire is on the computer.
C's position in the "low- vs high-level" hierarchy arguable hasn't changed much since it was created. There were already higher level languages in the 60's (e.g. languages which abstracted the underlying hardware much more than C, but those weren't useful for writing an operating system in).
I prefer the latter definition, as the former is, while objective, quite useless. The second definition could be expanded by a partial order between languages by “feature X can be emulated in it” with some caveats[1], and then we might even get Rust/C++ beat C for low-levelness, since C don’t have any way to force vectorization (compiler-specific intrinsics don’t count!).
[1] since most languages employ FFI/linking, not even this definition is too specific — would probably have to write it as the “idiomatic language can emulate feature”