8 ms·

It seems to be fast enough for SQL JIT-compiler in PostgreSQL 11+ and shader compilation in the *nix OpenGL stack (mesa), both of which are sort-of-realtime sys

by kspp 7y ago

It seems to be fast enough for SQL JIT-compiler in PostgreSQL 11+ and shader compilation in the *nix OpenGL stack (mesa), both of which are sort-of-realtime systems.

sanxiyn 7y ago
There is an ongoing work to move Mesa away from LLVM because LLVM is slow.
vkazanov 7y ago
Can't say anything about shaders but I do know a thing or two about database queries: 1. Queries are often repeated, i.e. most of backend DBs get the same requests over and over again. Even a slow jit compiler is fine here as things just get cached. 2. Queries usually take some time to complete, and this offsets the jit-related latency. Also, Postgres has a very limited kind of jit compilation, i.e. for expressions only. Notice that javascript jit compilers usually have a multi-tiered compilation. That's because proper compilation takes time, and sometimes it is more efficient to just do some basic template jiting (or no additional compilation) instead of firing the heavy guns. None of them use LLVM, btw.
- simias 7y ago
  I'm not sure I follow your reasoning, Go isn't JITed, is it?
  - pjmlp 7y ago
    Language != Implementation. And yes, there are Go interpreters as well. https://github.com/go-interpreter https://github.com/go-interpreter
saturn_vk 7y ago
Valve doesn't think so: https://steamcommunity.com/games/221410/announcements/detail/1602634609636894200 https://steamcommunity.com/games/221410/announcements/detail...
deleted 7y ago
[deleted]
eatonphil 7y ago
Another HN thread on projects that found LLVM to be slow. https://news.ycombinator.com/item?id=16956589 https://news.ycombinator.com/item?id=16956589
- kspp 7y ago
  That's the best way to learn — post a stupid thing on the internet and let the internet prove you wrong. Thanks to everyone who replied!
azakai 7y ago
SQL queries and GL shaders tend to be much shorter than a typical program. There are exceptions of course, but it's rare to find shaders with thousands of lines of code or more.
nicoburns 7y ago
Rust compilation is slow, and a large part of that is due to the use of LLVM.
- jashmatthews 7y ago
  LLVM is slow but swapping for CraneLift only improves compile times 33%. Other work is needed for a dramatic reduction in compile times: https://github.com/bjorn3/rustc_codegen_cranelift/issues/133#issuecomment-439475172 https://github.com/bjorn3/rustc_codegen_cranelift/issues/133...

by kspp 7y ago

It seems to be fast enough for SQL JIT-compiler in PostgreSQL 11+ and shader compilation in the *nix OpenGL stack (mesa), both of which are sort-of-realtime systems.

sanxiyn 7y ago

There is an ongoing work to move Mesa away from LLVM because LLVM is slow.

vkazanov 7y ago

Can't say anything about shaders but I do know a thing or two about database queries: 1. Queries are often repeated, i.e. most of backend DBs get the same requests over and over again. Even a slow jit compiler is fine here as things just get cached. 2. Queries usually take some time to complete, and this offsets the jit-related latency. Also, Postgres has a very limited kind of jit compilation, i.e. for expressions only. Notice that javascript jit compilers usually have a multi-tiered compilation. That's because proper compilation takes time, and sometimes it is more efficient to just do some basic template jiting (or no additional compilation) instead of firing the heavy guns. None of them use LLVM, btw.

simias 7y ago
I'm not sure I follow your reasoning, Go isn't JITed, is it?
- pjmlp 7y ago
  Language != Implementation. And yes, there are Go interpreters as well. https://github.com/go-interpreter https://github.com/go-interpreter

saturn_vk 7y ago

Valve doesn't think so: https://steamcommunity.com/games/221410/announcements/detail/1602634609636894200 https://steamcommunity.com/games/221410/announcements/detail...

deleted 7y ago

[deleted]

eatonphil 7y ago

Another HN thread on projects that found LLVM to be slow. https://news.ycombinator.com/item?id=16956589 https://news.ycombinator.com/item?id=16956589

kspp 7y ago
That's the best way to learn — post a stupid thing on the internet and let the internet prove you wrong. Thanks to everyone who replied!

azakai 7y ago

SQL queries and GL shaders tend to be much shorter than a typical program. There are exceptions of course, but it's rare to find shaders with thousands of lines of code or more.

nicoburns 7y ago

Rust compilation is slow, and a large part of that is due to the use of LLVM.

jashmatthews 7y ago
LLVM is slow but swapping for CraneLift only improves compile times 33%. Other work is needed for a dramatic reduction in compile times: https://github.com/bjorn3/rustc_codegen_cranelift/issues/133#issuecomment-439475172 https://github.com/bjorn3/rustc_codegen_cranelift/issues/133...