llvm-project VS Graal

See

https://github.com/llvm/llvm-project/issues/88344

https://fortran-lang.discourse.group/t/flang-new-how-to-forc...

You can never mistake type_declaration with an identifier, otherwise the program will not work. Aside from that constraint, you are free to name them whatever you like, there is no one standard, and each parser has it own naming conventions, unless you are planning to use something like LLVM. If you are interested, you can see examples of naming in different language parsers in the AST Explorer.

> There is one way to make the LLVM JIT compiler more usable, but I fear it’s going to take years to be implemented: being able to cache and reuse compiled queries.

Actually, it's implemented in LLVM for years :) https://github.com/llvm/llvm-project/commit/a98546ebcd2a692e...

> It's true, this was a CVE in Rust and not a CVE in C++, but only because C++ doesn't regard the issue as a problem at all. The problem definitely exists in C++, but it's not acknowledged as a problem, let alone fixed.

Can you find a link that substantiates your claim? You're throwing out some heavy accusations here that don't seem to match reality at all.

Case in point, this was fixed in both major C++ libraries:

https://github.com/gcc-mirror/gcc/commit/ebf6175464768983a2d...

https://github.com/llvm/llvm-project/commit/4f67a909902d8ab9...

So what C++ community refused to regard this as an issue and refused to fix it? Where is your supporting evidence for your claims?

For everyone else looking for the magic in this almost 7k lines monster, look at line 6610 [1].

[1] https://github.com/llvm/llvm-project/blob/8ec28af8eaff5acd0d...

Through value tracking. It's actually LLVM that does this, GCC probably does it as well, so in theory explicit bounds checks in regular C code would also be removed by the compiler.

How it works exactly I don't know, and apparently it's so complex that it requires over 9000 lines of C++ to express:

https://github.com/llvm/llvm-project/blob/main/llvm/lib/Anal...

https://github.com/llvm/llvm-project/blob/main/flang/docs/F2...

• Go • Rust • Lua • pure C (sans C++) • 6502 assembly • WebAssembly • compiler backends, like LLVM or Cranelift

Compilers also may even spill data to stack from memory, even when the original location is still available, as can be seen in this issue: https://github.com/llvm/llvm-project/issues/53348

I vaguely remember that spilling like this could allow high-end CPUs to use something similar to register renaming, i.e. stack locations like [rsp + 96] could be stay in a physical registers during function execution (high-end CPUs often have more physical registers, than logical ones), but could find good references whether such optimization exists in practice or not.

Unfortunately, I think more often than note it causes performance regressions and in some cases it may even cause unnecessary stack spilling of sensitive data: https://github.com/rust-lang/rust/issues/88930#issuecomment-...

Contrary to what vocal Kotlin advocates might believe, Kotlin only matters on Android, and that is thanks to Google pushing it no matter what.

https://spectrum.ieee.org/the-top-programming-languages-2023

https://snyk.io/reports/jvm-ecosystem-report-2021/

And even so, they had to conceed Android and Kotlin on their own, without the Java ecosystem aren't really much useful, thus ART is now updatable via Play Store, and currently supports OpenJDK 17 LTS on Android 12 and later devices.

As for your question regarding numbers, mostly Java 74.6%, C++ 13.7%, on the OpenJDK, other JVM implementations differ, e.g. GraalVM is mostly Java 91.8%, C 3.6%.

https://github.com/openjdk/jdk

https://github.com/oracle/graal

Two examples from many others, https://en.wikipedia.org/wiki/List_of_Java_virtual_machines

Pkl was built using the GraalVM Truffle framework. So it supports runtime compilation using Futurama Projections. We have been working with Apple on this for a while, and I am quite happy that we can finally read the sources!

https://github.com/oracle/graal/tree/master/truffle

Disclaimer: graalvm dev here.

That's pretty interesting. It's not as aggressive as Bee sounds, but the Espresso JVM is somewhat similar in concept. It's a full blown JVM written in Java with all the mod cons, which can either be compiled ahead of time down to memory-efficient native code giving something similar to a JVM written in C++, or run itself as a Java application on top of another JVM. In the latter mode it obviously doesn't achieve top-tier performance, but the advantage is you can easily hack on it using all the regular Java tools, including hotswapping using the debugger.

When run like this, the bytecode interpreter, runtime system and JIT compiler are all regular Java that can be debugged, edited, explored in the IDE, recompiled quickly and so on. Only the GC is provided by the host system. If you compile it to native code, the GC is also written in Java (with some special conventions to allow for convenient direct memory access).

What's most interesting is that Espresso isn't a direct translation of what a classical C++ VM would look like. It's built on the Truffle framework, so the code is extremely high level compared to traditional VM code. Details like how exactly transitions between the interpreter/compiled code happen, how you communicate pointer maps to the GC and so on are all abstracted away. You don't even have to invoke the JIT compiler manually, that's done for you too. The only code Espresso really needs is that which defines the semantics of the Java bytecode language and associated tools like the JDWP debugger protocol.

https://github.com/oracle/graal/tree/master/espresso

This design makes it easy to experiment with new VM features that would be too difficult or expensive to implement otherwise. For example it implements full hotswap capability that lets you arbitrarily redefine code and data on the fly. Espresso can also fully self-host recursively without limit, meaning you can achieve something like what's described in the paper by running Espresso on top of Espresso.

I'm also using GraalVM if that's of any help.

Quarkus is one of Java frameworks for microservices development and cloud-native deployment. It is developed as container-first stack and working with GraalVM and HotSpot virtual machines (VM).

Apologies, I didn't mean to imply DCEVM went poof, just that I was sad it didn't make it into OpenJDK so one need not do JDK silliness between the production one and the "debugging one" since my experience is that's an absolutely stellar way to produce Heisenbugs

And I'll be straight: Graal scares me 'cause Oracle but I just checked and it looks to the casual observer that it's straight-up GPLv2 now so maybe my fears need revisiting: https://github.com/oracle/graal/blob/vm-23.1.0/LICENSE

> to be compiled to a single executable is a strength that Java does not have

I think this is very outdated claim: https://www.graalvm.org/

https://github.com/oracle/graal/issues/7182