qbe-rs VS well

> I think it uses a different backend than LLVM

harec uses https://c9x.me/compile/

Have you considered QBE?

I really hope other new projects (like QBE) can really grow and become widely used

I really liked targetting QBE (https://c9x.me/compile/) as an IR, as it gave me lots of back-end optimisations for free 😊.

There is: QBE.

You might be underestimating the accuracy of the CPU models LLVM uses.

For x86, the same data the code generator uses drives llvm-mca[1], which given a loop body can tell you the throughput, latency, and microarchitectural bottlenecks (decoding, ports, dependencies, store forwarding, etc.)—if not always precisely, then still not worse then IACA, the tool written at Intel by people who presumably knew how the CPUs work, unlike LLVM contributors and the rest of us who can only guess and measure. This separately for Haswell, Sandy Bridge, Skylake, etc.; not “x86”.

Now, is this the best model you can get? Not exactly[2], but it’s close enough to not matter. Do we often need machine code to be optimized to that level of detail? Perhaps not[3], and with that in mind you can shave at least a factor of ten off LLVM’s considerable bulk at the cost of 20—30% of performance[4,5]. But if you do want those as well, it seems that the complexity of LLVM is a fair price, or has the right order of magnitude at least.

(Frontend not included, C++ frontend required to bootstrap sold separately, at a similar markup compared to a C-only frontend with somewhat worse ergonomics.)

[1] https://llvm.org/docs/CommandGuide/llvm-mca.html

[2] https://www.uops.info/

[3] https://briancallahan.net/blog/20211010.html

[4] https://c9x.me/compile/

[5] https://drewdevault.com/talks/qbe.html

You can try buildling you own backend like llvm. A good example or starting point is probably QBE since it is extremely small but very functional.

How big is the whole backend? I've heard that it is small but I wanted to compare it to QBE which is around 8 KLoC and it is quite interesting too.

I want to make a mention of tristan wellman's project called well: 'https://github.com/wellang/well', which aims to be a high level modern assembler, in case anyone knows about the assembly and wants to give support, we are trying to make an 'elf' so that it has linking support for gcc and/or any tool that handles elf compatibility with the '.o'

link: https://github.com/wellang/well

Where's the new one then? https://github.com/wellang/well/blob/main/src/interp.cpp Looks like it's just converting to C++ still.

It appears that the language uses "return" as a synonym for the SYSCALL x86_64 instruction: https://github.com/wellang/well/blob/main/src/syscall_interp...

The example code is equivalent to:

    write(1, "hello world!", 12);