LLVM

“The autovectorizer works quite well in llvm with all the aliasing guarantees rust gives it.”

“good tool users could save a lot of time instead of hand implementing everything, as I would. So thumbs up to LLVM.”

“getting working code was as simple as telling the compiler to use LLVM's MIPS III target”

“LLVM has a hardware agnostic intermediate representation (IR) that one could use though.”

“-Os is much much more aggressive in GCC than it is in LLVM, with LLVM you need to use -Oz to get the same result”

“They actually shipped LLVM bytecode, and you had to compile the executable locally with the whole toolchain”

“llvm definitely does a great job optimising tightly-written vector code to be even faster”

“Even with that there's still plenty of overhead from all the horrible C++ OOP-brained abstractions LLVM uses.”

“This infrastructure is also slow and leads to poor compilation times for any language that uses llvm as a backend.”

“I was surprised at how quickly a self-hosting compiler could be brought up using the LLVM ecosystem.”

“It could have been designed a lot better and could be managed very differently and we'd see better results.”

“i think LLVM also provides frameworks to do basically the same things (which does support a lot of platforms) and they also have good docs.”

“LLVM is a lot more verbose, but allows you to actually pick the semantics you want.”

“llvm makes a lot of assumptions about the structure of your code and the way its manipulated”

“I’m always surprised to learn LLVM is so slow given that was one of the original motivations for developing it.”

“the sentiment that Swift and Mojo and LLVM are these awful abominations is beyond the pale for me from an engineering standpoint”

“for all its warts, nobody is writing a seriously optimized language in any of the options you listed besides LLVM”

“It feels that, if LLVM had completely nailed its mission, these kinds of projects would be less common.”

“Pretty much everyone who has created a programming language with it has complained about its design.”

“llvm/gcc won the compiler world because they blew the codegen of proprietary compilers out of the water”

“Its IR is intended be be C-like, except that everything is well-defined and substantially more expressive than C.”

“they have significantly moved the needle on the average experience for quite a large number of end users”

“Getting all of LLVM mesa linux cmake ninja glibc gcc binutils xorg KDE to work is more work than in 2005 or 2010.”

“My main concern with LLVM is that it adds 30+ million lines of code dependency to any language that relies on it.”

“I remember part of the selling point of LLVM during its early stage was compilation time being so much faster than GCC.”

“LLVM IR is actually remarkably stable these days. I was able to rebase Fil-C from llvm 17 to 20 in a single day of work.”

“The brew LLVM situation is crazy and even more noticeable when you're on older macOS for which they no longer ship precompiled stuff.”

“LLVM isn't well suited for various things you might like to do when compiling functional programming languages”

“This “optimization” is not a win unless you willfully ignore the program and everything but instruction count.”

“I would argue that LLVM was/is the most well thought out and well-architected piece of software that exists today”

“Compiler know-how and resources available during compilations made very signicant progress between gcc and LLVM/clang era.”

“It's an excellent compiler backend. It produces really good code. But it is incredibly slow, and for no good technical reason.”

“LLVM codegen has been almost always sufficient, but for a routine that essentially amounts to adding two fixed-size bigints”

“GCC and LLVM can find some amazing optimizations, but they also consistently miss very obvious optimization opportunities”

“you can view what the LLVM optimizer pipeline does, and which pass is actually responsible for doing which instruction”

“LLVM is also very modular which makes it easy to maintain forks for a specific backend”

“Relatively standard CMake build with mostly self contained c++ codebase and few third party dependencies.”

“Anything else, you're better off starting off with LLVM. Especially if you want a compiler job.”

“the API is surprisingly benign and well documented for how difficult a task it accomplishes”

“The only downside was that you couldn't generate very high dimensional irreps because LLVM would begin to struggle with the sheer volume of code it needed to compile”