3 ms·
That's not what's going on though. Clang's not slow because LLVM is using additional optimizatons, it's slow because Clang is spending a ton of time in the fro
by ndesaulniers 6y ago
That's not what's going on though. Clang's not slow because LLVM is using additional optimizatons, it's slow because Clang is spending a ton of time in the frontend mostly lexing and keeping track of source locations for macro tokens.
(I literally just looked at a perf record of a whole build of the linux kernel with Clang; and know more about the subject than...anyone).
ToT LLVM, linux-next x86_64 defconfig: https://photos.app.goo.gl/hNwwy2K1Gh7Uc2D67 https://photos.app.goo.gl/hNwwy2K1Gh7Uc2D67 (yes, I know about disabling kptr_restrict)
Our next big project is to look into lazy parsing.
- gsnedders 6y agoWho's "our" here?
- gfxgirl 6y agothe linked image has a name associated with it. Googling that name should answer your question
- ralfd 6y agoTo save people the click and search: Someone from Google who works on compiling Linux.
- ndesaulniers 6y ago"People who care about improving compile times of the Linux kernel with Clang." "There are literally dozens of us!" /s