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Cheerp – A C/C++ compiler for web applications

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Re: Cheerp – A C/C++ compiler for web applications

#11

Post by Kip9000 »

Touche wrote: post #6
Kip9000 wrote: post #2

I wonder what advantages choosing C++ to write web apps would bring. At the end of the day it's all JavaScript so performance is rather moot point.

That's actually not true. Emscripten compiles to code that is much faster than hand-written JavaScript. In this case they are not using Emscripten or a similar technique but are compiling to regular old JavaScript, so performance probably is the same, rather this might be for people who just like C++, like what GWT is for Java devs.

You misunderstood. People mostly write with C++ when performance is critical. Why? C++ offers deterministic memory management, Specialize to CPU instruction set and better use of CPU caches etc. Those performance benefits would not translate when you cross compile to something like JavaScript. I get the point about converting the legacy desktop apps to web apps, but how would it handle the architectural differences ( Desktop apps don't scale)

Re: Cheerp – A C/C++ compiler for web applications

#12

Post by humanrebar »

Kip9000 wrote: post #11
Touche wrote: post #6

Earlier quoted context omitted.

That's actually not true. Emscripten compiles to code that is much faster than hand-written JavaScript. In this case they are not using Emscripten or a similar technique but are compiling to regular old JavaScript, so performance probably is the same, rather this might be for people who just like C++, like what GWT is for Java devs.

You misunderstood. People mostly write with C++ when performance is critical. Why? C++ offers deterministic memory management, Specialize to CPU instruction set and better use of CPU caches etc. Those performance benefits would not translate when you cross compile to something like JavaScript. I get the point about converting the legacy desktop apps to web apps, but how would it handle the architectural differences (…

> People mostly write with C++ when performance is critical.

Performance is a big reason people use C++, but there are many others. For example, people also write C++ when correctness is critical (bank software, safety-critical systems, etc.).

Re: Cheerp – A C/C++ compiler for web applications

#13

Post by pkolaczk »

humanrebar wrote: post #9
Kip9000 wrote: post #2

I wonder what advantages choosing C++ to write web apps would bring. At the end of the day it's all JavaScript so performance is rather moot point.

> At the end of the day it's all JavaScript so performance is rather moot point That's probably true, but C++ does provide very powerful compile-time evaluation mechanisms like templates, constexpr (compile-time evaluated constants and functions), and template metaprogramming. That being said, compile-time C++ can look very gross since most of the features are accidental. However, there are a lot of huge performance…

Metaprogramming and type-safety facilities of C++ are very limited compared to other languages like Haskell or Scala. And for the latter there is a JS compiler as well.

Re: Cheerp – A C/C++ compiler for web applications

#14

Post by Touche »

Kip9000 wrote: post #11
Touche wrote: post #6

Earlier quoted context omitted.

That's actually not true. Emscripten compiles to code that is much faster than hand-written JavaScript. In this case they are not using Emscripten or a similar technique but are compiling to regular old JavaScript, so performance probably is the same, rather this might be for people who just like C++, like what GWT is for Java devs.

You misunderstood. People mostly write with C++ when performance is critical. Why? C++ offers deterministic memory management, Specialize to CPU instruction set and better use of CPU caches etc. Those performance benefits would not translate when you cross compile to something like JavaScript. I get the point about converting the legacy desktop apps to web apps, but how would it handle the architectural differences (…

You do get some of those performance benefits when you cross-compile. JS VMs have different paths for different types of code and the type of code that Emscripten produces goes through a faster path because more is known about the code ahead of time.

Re: Cheerp – A C/C++ compiler for web applications

#15

Post by pkolaczk »

humanrebar wrote: post #12
Kip9000 wrote: post #11

Earlier quoted context omitted.

You misunderstood. People mostly write with C++ when performance is critical. Why? C++ offers deterministic memory management, Specialize to CPU instruction set and better use of CPU caches etc. Those performance benefits would not translate when you cross compile to something like JavaScript. I get the point about converting the legacy desktop apps to web apps, but how would it handle the architectural differences (…

> People mostly write with C++ when performance is critical. Performance is a big reason people use C++, but there are many others. For example, people also write C++ when correctness is critical (bank software, safety-critical systems, etc.).

Writing for correctness in a language with no memory-safety, weak type system and, till not very long ago, no standardized memory-model, and UB in every other paragraph of the specs? Good joke. If they are really doing this, they have no idea what they are doing. There are plenty of languages better for safety-critical systems than C++; even widely hated, boring Java is much better.

Re: Cheerp – A C/C++ compiler for web applications

#17

Post by Kip9000 »

pkolaczk wrote: post #15
humanrebar wrote: post #12

Earlier quoted context omitted.

> People mostly write with C++ when performance is critical. Performance is a big reason people use C++, but there are many others. For example, people also write C++ when correctness is critical (bank software, safety-critical systems, etc.).

Writing for correctness in a language with no memory-safety, weak type system and, till not very long ago, no standardized memory-model, and UB in every other paragraph of the specs? Good joke. If they are really doing this, they have no idea what they are doing. There are plenty of languages better for safety-critical systems than C++; even widely hated, boring Java is much better.

That was going to be my response..

Re: Cheerp – A C/C++ compiler for web applications

#18

Post by pkolaczk »

Kip9000 wrote: post #17
pkolaczk wrote: post #15

Earlier quoted context omitted.

Writing for correctness in a language with no memory-safety, weak type system and, till not very long ago, no standardized memory-model, and UB in every other paragraph of the specs? Good joke. If they are really doing this, they have no idea what they are doing. There are plenty of languages better for safety-critical systems than C++; even widely hated, boring Java is much better.

That was going to be my response..

I was replying to the statement: "For example, people also write C++ when correctness is critical". And I say if someone writes C++ in a correctness critical system, he must not know what he is doing. Even if you're using only STL, RAII and following all the good coding practices, there are still so many ways to screw things up, that C++ is among the worst choices in this regard.

Re: Cheerp – A C/C++ compiler for web applications

#19

Post by swah »

Kip9000 wrote: post #2

I wonder what advantages choosing C++ to write web apps would bring. At the end of the day it's all JavaScript so performance is rather moot point.

> it's all JavaScript so performance is rather moot point

If that was the case, http://asmjs.org/ wouldn't be a thing.

Re: Cheerp – A C/C++ compiler for web applications

#20

Post by illumen »

Touche wrote: post #14
Kip9000 wrote: post #11

Earlier quoted context omitted.

You misunderstood. People mostly write with C++ when performance is critical. Why? C++ offers deterministic memory management, Specialize to CPU instruction set and better use of CPU caches etc. Those performance benefits would not translate when you cross compile to something like JavaScript. I get the point about converting the legacy desktop apps to web apps, but how would it handle the architectural differences (…

You do get some of those performance benefits when you cross-compile. JS VMs have different paths for different types of code and the type of code that Emscripten produces goes through a faster path because more is known about the code ahead of time.

You also get 1.4MB of code, which takes 1 hour to load on a mobile connection, and reimplements functionality that host JS/Browser provides which goes much quicker ;) Most C++ code does not care about compiled size(especially with templates!!!), but JS code often does, so is written in a smaller way.
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