Create .cargo/config.toml in your project directory with the following:
[target.x86_64-unknown-linux-gnu]
linker = “clang”
rustflags = [“-C”, “link-arg=-fuse-ld=/path/to/mold”]
where /path/to/mold is an absolute path to the mold executable. In the example above, we use clang as a linker driver since it always accepts the -fuse-ld option. If your GCC is recent enough to recognize the option, you may be able to remove the linker = “clang” line.
[target.x86_64-unknown-linux-gnu]
rustflags = [“-C”, “link-arg=-fuse-ld=/path/to/mold”]
If you want to use mold for all projects, add the above snippet to ~/.cargo/config.toml
I remember reading about Mold years ago and being impressed, even though most of my programs that I compile don’t really benefit in any way. I appreciate that it kept going.
The performance gains are impressive in relative terms, but I don’t think I would ever switch the default linker if the potential gains are like shaving off 5 seconds when linking a 3GB bundle of binaries.
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Cool. Any idea how would i use this with rustc?
From their repo (https://github.com/rui314/mold#how-to-use)
Create .cargo/config.toml in your project directory with the following:
[target.x86_64-unknown-linux-gnu] linker = “clang” rustflags = [“-C”, “link-arg=-fuse-ld=/path/to/mold”] where /path/to/mold is an absolute path to the mold executable. In the example above, we use clang as a linker driver since it always accepts the -fuse-ld option. If your GCC is recent enough to recognize the option, you may be able to remove the linker = “clang” line.
[target.x86_64-unknown-linux-gnu] rustflags = [“-C”, “link-arg=-fuse-ld=/path/to/mold”] If you want to use mold for all projects, add the above snippet to ~/.cargo/config.toml
I read the design notes and found them pretty interesting even though I haven’t really been pining for a faster linker: https://github.com/rui314/mold/blob/main/docs/design.md
I remember reading about Mold years ago and being impressed, even though most of my programs that I compile don’t really benefit in any way. I appreciate that it kept going.
Parallelize all the things! 🧹
The performance gains are impressive in relative terms, but I don’t think I would ever switch the default linker if the potential gains are like shaving off 5 seconds when linking a 3GB bundle of binaries.
At work we use lld as opposed ld. With ld, the project I work on links in 60-something seconds, with lld it links in less than 6.
Mold is faster than lld. It is absolutely worth it