A Detailed Look At The Speed Advantages To LLVM's LLD Linker

[pal666]

I'm not a mac user.

windows?

[cl333r]

so you didn't believe any llvm devs claims?
hard to imagine llvm devs jumping in with "yes, we suck"

because you are macos user stuck with 10+ year old gcc?

You're clueless and I'm not a mac user.

[pal666]

-fvisibility=hidden

this usually requires changes to source code. like adding export macros to public symbols

-Wl,-Bsymbolic-functions

if you want to break elf symbol interposition, there is -fno-semantic-interposition

[pal666]

I'm not sure I believe it because the author seems to be a GCC dev

so you didn't believe any llvm devs claims?

would be great if a LLVM dev commented on that.

hard to imagine llvm devs jumping in with "yes, we suck"

Though being a C++ dev I totally like LLVM a lot better than g++.

because you are macos user stuck with 10+ year old gcc?

[moltonel]

Can Gentoo be configured to use it? Sounds like it would complement that OS perfectly.

Yes. The user can set the default CC, LD, CFLAGS, and LDFLAGS for your system, or specific setting for specific packages. Also, some packages (like firefox) have a USE flag to build with a different compiler and/or linker, with even less effort.

[moltonel]

Is there any improvement in runtime performance? No. Spending little extra time during linking process is non issue, majority of endusers don't compile their software. GNU/Linux desktop users would benefit from faster EFL binary startup and quicker shared .so library resolution. GCC still offers better compatibility, produces faster and much smaller binaries e.g in firefox case.

There's pretty much no runtime performance difference to using Gnu's LD vs LLD vs Gold. Linking is orthogonal to compiling: you can compile with GCC and link with LLD, or any other combination. Compiling can be highly parallelized (using more cores and even more machines), but linking remains a singular step.

So go ahead and use the compiler that produces faster code for a particular codebase (that's sometimes GCC, sometimes LLVM, usually negligible) and use the faster linker to speed up your development process and therefore make the software better faster.

Linking Firefox takes around 15min with LLD on my machine, I don't even want to try linking with LD. Waiting for a build is a huge developer productivity killer.

[cybertraveler]

Can Gentoo be configured to use it? Sounds like it would complement that OS perfectly.

[brad0]

Is there any improvement in runtime performance? No. Spending little extra time during linking process is non issue, majority of endusers don't compile their software. GNU/Linux desktop users would benefit from faster EFL binary startup and quicker shared .so library resolution. GCC still offers better compatibility, produces faster and much smaller binaries e.g in firefox case.

Still wouldn't use GCC. Not worth it for the marginal "better compatibility". Operating Systems and packages don't magically build themselves.

[flower]

Is there any improvement in runtime performance? No. Spending little extra time during linking process is non issue, majority of endusers don't compile their software. GNU/Linux desktop users would benefit from faster EFL binary startup and quicker shared .so library resolution. GCC still offers better compatibility, produces faster and much smaller binaries e.g in firefox case.

imho binary size is a non issue. most of my ram and disk is not used by code segments.

faster startup times are nice to have.
faster binaries are more important though

[cl333r]

GCC still offers better compatibility, produces faster and much smaller binaries e.g in firefox case.

Thanks for the link, insightful but I'm not sure I believe it because the author seems to be a GCC dev and heavily biased. I'm not into compilers so I can't judge, would be great if a LLVM dev commented on that.
Though being a C++ dev I totally like LLVM a lot better than g++.