lld linker 是 ld 和 gold 的替代品吗？

Question

The linker from the LLVM project lld is currently developed with new features added week by week. Its developers promise that lld is faster than ld . How does it compete compared to gold ?

Is lld a drop-in replacement for ld ? With gold there are some hoops to jump through .

Answer 1

One of the LLD developers, Rui Ueyama, looks back at the progress LLD did in 2016, see http://lists.llvm.org/pipermail/llvm-dev/2016-December/107981.html .

• "Now I'm pretty sure that that [LLD] is going to be a serious (and better, in my opinion) alternative to the existing GNU linkers [..]."
• "LLD is now able to link most x86-64 userland programs."
• "The FreeBSD project and we are trying to make LLD the system default linker of the operating system, and except a few tricky programs such as the kernel or a bootloader, the linker works mostly fine." Already achieved!
• "LLD supports x86, x86-64, x32, AArch64, AMDGPU, ARM, PPC64 and MIPS32/64, though completeness varies."
• "[T]here are already a few systems that are using LLD as system linkers, such as CloudABI or Fuchsia. Chromium and Clang/LLVM itself has build options to use LLD to build them."

And, as a bonus:

• "LLD got faster [..] At the beginning of this year, LLD took about 16 seconds to produce a 1.5 GB clang (debug build) executable. Now, it takes about 14.5 seconds on single core and 8.5 seconds on 20 cores. ld.gold takes about 25 seconds and 20 seconds, respectively. [..] If you have a problem of too long link time, I'd recommend to try LLD."

Update spring 2017 According to one of the developers "LLD/ELF is now ready for production use at least for x86-64 (and probably for AArch64 and MIPS).", seehttp://lists.llvm.org/pipermail/llvm-dev/2017-March/111083.html It also contains a brief description on how to make use of LLD.

Answer 2

The program itself claims compatibility goal, and seems to work fine on simple tests

Eg on Ubuntu 20.04 I install :

sudo apt install lld
lld --version

says:

LLD 10.0.0 (compatible with GNU linkers)

and I'm able to compile a C hello world with -fuse-ld=lld :

gcc -fuse-ld=lld -ggdb3 -O0 -std=c11 -Wall -Wextra -pedantic -o hello.out hello.c

Performance benchmark vs gold

I'll document results soon at: Replacing ld with gold - any experience?

Answer 3

FreeBSD / OpenBSD use lld as the system linker. FreeBSD does across all supported archs, for OpenBSD we do for all minus mips64 at the moment (amd64 arm i386 powerpc -- aarch64 powerpc64 riscv64 ports were from scratch and never used the BFD linker, but do use lld). We're building the whole OS and 99.9999% of the ports tree. I can count on one hand how many are left that do not.

It's definitely much faster for larger projects especially larger C++ projects like Chrome, Firefox, Thunderbird, KDE, etc. Also lower memory utilization which can be problematic on 32-bit archs.