I will tell you how it can be - if the JavaScript engine JITs the JS in a more optimized way than the C compiler compiled the C.
Well how does that make JS faster than C when JS will always carry more overhead? It cannot and does not - all it means is that the compiler was far better.
A poor C compiler may be outperformed by the best JS one, but that is about the only scenario where JS will outperform C.
If you want to keep arguing that every other language merely asymptotically approaches the performance of x86_64 assembly, that is a fine (if dumb) position. But the argument that C has a monopoly on assembly code generation is silly, as is the argument that C compilers are inherently better at code generation than all other compilers. Look at the LuaJIT2 direct-threading post upthread for an infamous example of a performant dispatching structure that isn't easily expressible in ANSI C.
Sure, but the point of that post is that hand-written assembly can beat C-compiler-generated assembly. It's not arguing that any other language's runtime (even LuaJIT's own code generator) is going to generate assembly that's any better than gcc's in this case.
I do know that one of Mike Pall's stated goals with LuaJIT is to minimize the performance difference between Lua and C as much as possible. Though one of his methods of doing so (the foreign function interface: http://luajit.org/ext_ffi_tutorial.html) gives up the memory-safety of Lua to accomplish this. Even without FFI, LuaJIT is incredibly fast for functional/numerical calculations.
> If you want to keep arguing that every other language merely asymptotically approaches the performance of x86_64 assembly, that is a fine (if dumb) position.
I think what rubs some people (including me) the wrong way about these "faster than C" claims is the implied argument that C (and other non-GC'd languages) are obsolete. These claims often come from people who, as this article's author explicit states, want higher-level languages to win because they don't want to ever have to write in C or deal with anything written in C.
If people can get stuff in higher-level languages to run faster, then great, but those of us working in system-space in non-memory-safe languages are still going to beat their pants off if we combine all the tricks of their VM with domain-specific knowledge and optimizations (specifically parsing, in this case). "Faster than C" claims can sometimes feel like a big "F U" to those of us trying to innovate in system-space, like "our VM is the only system software we'll ever need." It's the Java attitude where people only want "100% pure Java" and shun JNI and anything that won't run on their VM.
The standard C library is full of functions that are slower than equivalent functionality in higher level languages. Or do you think ticking through arrays of hopefully-ASCII bytes, byte by byte, waiting for the 0 byte, is the fastest way to compare two strings?
Yes, you could do the same thing in C code, but the resulting executable would be unreasonably large because you would have to unroll every loop and inline every function.
Pypy has show itself faster than C in some cases as well[1].
1. http://morepypy.blogspot.com/2011/08/pypy-is-faster-than-c-a...
Yes. Exactly. Let's say there are two languages A and B, and A is compiled (be it JIT or AOT) by a smarter compiler, resulting in faster code than the same program written in language B, how does that not make language A faster?
I do know that comparing interpreted/JITed code and AOT-compiled code is somewhat nonsensical, but then again, so is talking about "faster" and "slower" languages.
Well I am talking about the performance limitations imposed by the laws of physics. Not which compiler is better. I can always find a better or worse C or JS compiler/JITter so that proves nothing.
Doing more (Which a more highly abstracted languages must do) in less time with all else being the same is not possible as we understand quantum physics today.
Can you explain why you think this assumption is true? I don't think it is.
A higher level of abstraction may allow your to convey more information in less code, but that does not mean it necessarily translates to more machine code.
In fact, when you operate on a higher level of abstraction with more information available, the compiler may even have more freedom to produce highly efficient output without breaking expected semantics.
In theory, any optimization available to a compiler is also available to an assembly programmer. In practice humans do not match automation. This has been demonstrated both in theory and practice for decades.
There is no limit to the level of language that this argument could theoretically apply to. In practice the run-time guarantees and programmatic indirection that we demand in high level languages make the task insurmountable for current programs. But never underestimate what can happen with a good compiler and the right program.
Instead the trend mostly seems to be that we do it by hand until automation becomes good enough to do it better than we were doing it, and then we move on to harder kinds of problems and let automation do its thing.
I say "mostly seems to be" because there are plenty of counter-examples. But that's the general trend. As is seen by the explosion of programmers working in what used to be considered unbearably slow scripting languages, and the relative lack of people doing traditional assembly programming.
JS and Lua also have disadvantages, such as their inferior (but memory safe) representation of data, so I would not be surprised if JS were faster for some problems and slower for others.
However, in general JITs do not outperform GCC. The JIT overhead only pays off in a limited set of cases.
Most people publishing performance benchmarks on the Internet barely know how to compile a C program for production, let alone write or benchmark one. Google did a thorough benchmark of several languages and C++ was the clear winner: https://days2011.scala-lang.org/sites/days2011/files/ws3-1-H...
No. One person employed at Google did a comparison and lots of other people (including some others employed at Google) explained what they thought was wrong with that comparison.
