LLVM Profile Error: Runtime and instrumentation version mismatch : expected 10, but get 8

[ivanrg99]

Hi! Love the project.

I updated my system recently, using the latest llvm package from homebrew and latest rust version. When I now run cargo pgo optimize, I keep getting a LLVM Profile Error: Runtime and instrumentation version mismatch : expected 10, but get 8 error.

My llvm installation is version 19, and running rustc --version --verbose reveals that my rust installation is also using llvm 19:

rustc 1.84.0 (9fc6b4312 2025-01-07)
binary: rustc
commit-hash: 9fc6b43126469e3858e2fe86cafb4f0fd5068869
commit-date: 2025-01-07
host: aarch64-apple-darwin
release: 1.84.0
LLVM version: 19.1.5

Is anyone else facing this issue?

[Kobzol]

Hi, could you please post the output of cargo pgo info? Thanks!

[ivanrg99]

[rustc version]: 1.84.0 is recent enough
[llvm-profdata]: found at /Users/ivan/.rustup/toolchains/stable-aarch64-apple-darwin/lib/rustlib/aarch64-apple-darwin/bin/llvm-profdata
[llvm-bolt]: found at /Users/ivan/Downloads/LLVM/build/bin/llvm-bolt
[merge-fdata]: found at /Users/ivan/Downloads/LLVM/build/bin/merge-fdata

I was missing bolt from my llvm install, so I have built it myself from version 19.1.17 of llvm (which is the latest one packaged by brew), but the same error still persists.

[Kobzol]

BOLT shouldn't be at fault here.

I see that you're on macOS. Sadly, PGO doesn't work well for Rust on macOS. I remember seeing similar errors when we tried to PGO the compiler (rustc) itself on macOS, and these issues haven't been resolved yet. So it's probably this long-standing, yet unresolved issue. Someone has been looking at it recently (https://rust-lang.zulipchat.com/#narrow/stream/122651-general/topic/How.20to.20distribute.20builds.20across.20multiple.20macbooks.3F).

I think that you're going to get the same result, but you could try doing PGO without cargo-pgo (https://doc.rust-lang.org/rustc/profile-guided-optimization.html) to see if that works. If the same error happens without cargo-pgo, then sadly I can't do much here. You could report the issue in the Rust issue tracker though.

[maxall41]

Also having this issue. Doing PGO without cargo pgo did not help. I tried a bunch of other things, but nothing worked. Would love to have a solution to this issue.

For some reason cargo pgo works perfectly on my MacBook, but does not work in Github actions. I have no idea why this is the case.

[Kobzol]

Maybe it is a clang/LLVM version mismatch on macOS? https://stackoverflow.com/a/78391400/1107768 Maybe try installing a Clang version that corresponds to the LLVM version used by rustc. It can be found by running rustc -Vv.

[maxall41]

Just tried this. Ensuring matching clang and rust LLVM versions does not fix the issue:

Github Actions Clang & Rust LLVM versions:

bash-3.2$ rustc -vV
rustc 1.86.0 (05f9846f8 2025-03-31)
binary: rustc
commit-hash: 05f9846f893b09a1be1fc8560e33fc3c815cfecb
commit-date: 2025-03-31
host: aarch64-apple-darwin
release: 1.86.0
LLVM version: 19.1.7

bash-3.2$ clang --version
clang version 19.1.7 (/Users/runner/work/llvm-project/llvm-project/clang cd708029e0b2869e80abe31ddb175f7c35361f90)
Target: arm64-apple-darwin24.5.0
Thread model: posix
InstalledDir: /Users/runner/work/RustSASA/RustSASA/llvm/bin
bash-3.2$

Error:

LLVM Profile Error: Runtime and instrumentation version mismatch : expected 10, but get 8

Oddly on my mac the clang and rust LLVM versions are quite different and yet it works:

❯ rustc -Vv
rustc 1.88.0 (6b00bc388 2025-06-23)
binary: rustc
commit-hash: 6b00bc3880198600130e1cf62b8f8a93494488cc
commit-date: 2025-06-23
host: aarch64-apple-darwin
release: 1.88.0
LLVM version: 20.1.5

❯ clang --version
Apple clang version 17.0.0 (clang-1700.0.13.5)
Target: arm64-apple-darwin24.5.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
(base)