dlopen offload by sgasho · Pull Request #160335 · rust-lang/rust

sgasho · 2026-08-01T13:12:37Z

dlopen offload to dist it in dist-x86_64-linux without enabling llvm.offload=true in CI (#159064 (comment))

I tested that this works by following steps at https://rustc-dev-guide.rust-lang.org/offload/usage.html for both LLVM22 and 23(by switch base branch to #158734 temporarily), though It might be better to land this after LLVM 23.

r? @ZuseZ4

rustbot · 2026-08-01T13:12:40Z

This PR changes how LLVM is built. Consider updating src/bootstrap/download-ci-llvm-stamp.

sgasho · 2026-08-01T13:48:36Z

 impl KernelArgsTy {
    const OFFLOAD_VERSION: u64 = 3;
-    const FLAGS: u64 = 0;
+    const FLAGS: u64 = 1 << 6; // Enable StrictBlocksAndThreads


I got this error while testing on LLVM23

Related to this I guess.
llvm/llvm-project#199483

View changes since the review

cc @kevinsala
@Sa4dUs I vaguely remember you ran into this when trying LLVM 23 patches, right? Was this the right solution?

I'll double-check with Kevin later today and test it myself, otherwise lgtm

ZuseZ4 · 2026-08-02T00:31:06Z

The LLVM 23 update unfortunately takes a little longer than expected, but glad to hear you got it to work with both 22 and 23. In that case I'd just merge it once it's ready and not wait, since it seems unlikely that we'll break the LLVM 23 update PR with this work here. Worst case, std::offload is broken on main for a couple of days if we missed something, but that shouldn't affect too many users yet.

It's a bit unfortunate that we need a new cmake file for the offload wrapper. Hopefully I'll find time to upstream our wrappers into LLVM, so we won't need that in the future. But it would probably be part of llvm 24, so we shouldn't wait for that.

sgasho · 2026-08-05T12:32:11Z

Update to LLVM23 PR has been merged. I pull-rebased onto the latest main and will recheck the offload build on UofT server

sgasho · 2026-08-05T14:21:22Z

I tested that it works against LLVM23 again

ZuseZ4 · 2026-08-06T19:26:49Z

+
+    fn get_rust_offload_path(
+        sysroot: &rustc_session::config::Sysroot,
+    ) -> Result<String, RustOffloadLibraryError> {


That should probably be a PathBuf or an OSString or something like that, or?
https://docs.rs/libloading/latest/libloading/struct.Library.html
I don't think we need to force a normal String here

View changes since the review

ZuseZ4 · 2026-08-06T19:39:48Z

and

Looks good; it worked out of the box and showed both errors when I broke it.

Two things I noticed (btw also wrong in the Enzyme path):

The code uses String instead of OsString or PathBuf
The sysroot path it gives is wrong/confusing. It's not really looking at that location. I had to place a dummy libOffload here, for the code to try and load it: /tmp/drehwald1/prog/rust/build/x86_64-unknown-linux-gnu/stage1/lib/rustlib/x86_64-unknown-linux-gnu/lib/libRustOffload-23.so

Compare that to the sysroot path above, which is quite a bit shorter. But since Enzyme has the same mistakes and it seems to work those can also be follow-up PRs. Can you squash it, since later commits mostly seem to fix the first one?

r=me after squashing

ZuseZ4 · 2026-08-06T19:51:05Z

@bors delegate

rust-bors · 2026-08-06T19:51:09Z

✌️ @sgasho, you can now approve this pull request!

If @ZuseZ4 told you to "r=me" after making some further change, then please make that change and post @bors r=ZuseZ4.

View changes since this delegation.

ZuseZ4 · 2026-08-06T23:16:56Z

@bors squash msg="dlopen Offload"

rust-bors · 2026-08-06T23:17:18Z

🔨 3 commits were squashed into 162cba5.

ZuseZ4 · 2026-08-06T23:17:50Z

@bors r+ rollup

rust-bors · 2026-08-06T23:17:53Z

📌 Commit 162cba5 has been approved by ZuseZ4

It is now in the queue for this repository.

🌲 The tree is currently closed for pull requests below priority 6. This pull request will be tested once the tree is reopened.

Reason for tree closure: Github problems

@ZuseZ4

dlopen offload dlopen offload to dist it in dist-x86_64-linux without enabling llvm.offload=true in CI (rust-lang#159064 (comment)) I tested that this works by following steps at https://rustc-dev-guide.rust-lang.org/offload/usage.html for both LLVM22 and 23(by switch base branch to rust-lang#158734 temporarily), though It might be better to land this after LLVM 23. r? @ZuseZ4

@ZuseZ4

dlopen offload dlopen offload to dist it in dist-x86_64-linux without enabling llvm.offload=true in CI (rust-lang#159064 (comment)) I tested that this works by following steps at https://rustc-dev-guide.rust-lang.org/offload/usage.html for both LLVM22 and 23(by switch base branch to rust-lang#158734 temporarily), though It might be better to land this after LLVM 23. r? @ZuseZ4

Rollup of 14 pull requests Successful merges: - #150885 (Revive L4Re target) - #159643 (Add support for splatted function pointers) - #160433 (delegation: add support for wrapping of the return value with `From::from`) - #160530 (refactor handling of target features in Session) - #160606 (bootstrap: Store and use an explicit CheckKind in `check::Rustc`) - #160628 (fix ICE in `suggest_add_reference_to_arg` for non-callable items) - #160634 (miri subtree update) - #158904 (Fix FutureDropPoll shim for by-move async closures) - #160335 (dlopen offload) - #160445 (codegen: classify localized MSVC linker progress as linker_info) - #160504 (cleanup borrowck, improve c-variadic handling) - #160587 (Add regression test for associated type outlives bound at call site) - #160625 (platform-support/netbsd.md: No longer mention 8.x, due to EoL.) - #160636 (derive(Diagnostic): link to proper docs)

@ZuseZ4

dlopen offload dlopen offload to dist it in dist-x86_64-linux without enabling llvm.offload=true in CI (rust-lang#159064 (comment)) I tested that this works by following steps at https://rustc-dev-guide.rust-lang.org/offload/usage.html for both LLVM22 and 23(by switch base branch to rust-lang#158734 temporarily), though It might be better to land this after LLVM 23. r? @ZuseZ4

…uwer Rollup of 21 pull requests Successful merges: - #159784 (Hint that memchr returns an in-bounds index) - #150885 (Revive L4Re target) - #159643 (Add support for splatted function pointers) - #160433 (delegation: add support for wrapping of the return value with `From::from`) - #160530 (refactor handling of target features in Session) - #160606 (bootstrap: Store and use an explicit CheckKind in `check::Rustc`) - #160628 (fix ICE in `suggest_add_reference_to_arg` for non-callable items) - #160634 (miri subtree update) - #157641 (Do not promote extern statics) - #158904 (Fix FutureDropPoll shim for by-move async closures) - #160103 (Add regression test for GAT bound mismatched type error) - #160335 (dlopen offload) - #160445 (codegen: classify localized MSVC linker progress as linker_info) - #160499 (rustc_resolve: move diagnostic attribute linting to attr parsing) - #160504 (cleanup borrowck, improve c-variadic handling) - #160577 (expand: Feature gate AST-based attribute macros on expressions and statements) - #160587 (Add regression test for associated type outlives bound at call site) - #160625 (platform-support/netbsd.md: No longer mention 8.x, due to EoL.) - #160636 (derive(Diagnostic): link to proper docs) - #160644 (Clean up some manual debug impls) - #160649 (move naked function ui tests)

@ZuseZ4

dlopen offload dlopen offload to dist it in dist-x86_64-linux without enabling llvm.offload=true in CI (rust-lang#159064 (comment)) I tested that this works by following steps at https://rustc-dev-guide.rust-lang.org/offload/usage.html for both LLVM22 and 23(by switch base branch to rust-lang#158734 temporarily), though It might be better to land this after LLVM 23. r? @ZuseZ4

…uwer Rollup of 20 pull requests Successful merges: - #159784 (Hint that memchr returns an in-bounds index) - #150885 (Revive L4Re target) - #159643 (Add support for splatted function pointers) - #160433 (delegation: add support for wrapping of the return value with `From::from`) - #160530 (refactor handling of target features in Session) - #160606 (bootstrap: Store and use an explicit CheckKind in `check::Rustc`) - #160628 (fix ICE in `suggest_add_reference_to_arg` for non-callable items) - #160634 (miri subtree update) - #157641 (Do not promote extern statics) - #158904 (Fix FutureDropPoll shim for by-move async closures) - #160103 (Add regression test for GAT bound mismatched type error) - #160335 (dlopen offload) - #160445 (codegen: classify localized MSVC linker progress as linker_info) - #160499 (rustc_resolve: move diagnostic attribute linting to attr parsing) - #160504 (cleanup borrowck, improve c-variadic handling) - #160577 (expand: Feature gate AST-based attribute macros on expressions and statements) - #160587 (Add regression test for associated type outlives bound at call site) - #160625 (platform-support/netbsd.md: No longer mention 8.x, due to EoL.) - #160636 (derive(Diagnostic): link to proper docs) - #160644 (Clean up some manual debug impls)

@ZuseZ4

dlopen offload dlopen offload to dist it in dist-x86_64-linux without enabling llvm.offload=true in CI (rust-lang#159064 (comment)) I tested that this works by following steps at https://rustc-dev-guide.rust-lang.org/offload/usage.html for both LLVM22 and 23(by switch base branch to rust-lang#158734 temporarily), though It might be better to land this after LLVM 23. r? @ZuseZ4

@ZuseZ4

dlopen offload dlopen offload to dist it in dist-x86_64-linux without enabling llvm.offload=true in CI (rust-lang#159064 (comment)) I tested that this works by following steps at https://rustc-dev-guide.rust-lang.org/offload/usage.html for both LLVM22 and 23(by switch base branch to rust-lang#158734 temporarily), though It might be better to land this after LLVM 23. r? @ZuseZ4

…uwer Rollup of 28 pull requests Successful merges: - #159784 (Hint that memchr returns an in-bounds index) - #160673 (Improve `canonical_param_env_cache`) - #150885 (Revive L4Re target) - #159643 (Add support for splatted function pointers) - #160433 (delegation: add support for wrapping of the return value with `From::from`) - #160530 (refactor handling of target features in Session) - #160606 (bootstrap: Store and use an explicit CheckKind in `check::Rustc`) - #160628 (fix ICE in `suggest_add_reference_to_arg` for non-callable items) - #160683 (Add regression test for unknown feaeture name reported with other errors) - #157641 (Do not promote extern statics) - #158904 (Fix FutureDropPoll shim for by-move async closures) - #159816 (added note/help about iterator invalidation when mutating a collection inside a for loop) - #160103 (Add regression test for GAT bound mismatched type error) - #160335 (dlopen offload) - #160445 (codegen: classify localized MSVC linker progress as linker_info) - #160499 (rustc_resolve: move diagnostic attribute linting to attr parsing) - #160504 (cleanup borrowck, improve c-variadic handling) - #160577 (expand: Feature gate AST-based attribute macros on expressions and statements) - #160587 (Add regression test for associated type outlives bound at call site) - #160625 (platform-support/netbsd.md: No longer mention 8.x, due to EoL.) - #160633 (delegation: fix determining wrong `FnKind` when delegation is inside const arg) - #160636 (derive(Diagnostic): link to proper docs) - #160644 (Clean up some manual debug impls) - #160649 (move naked function ui tests) - #160672 (Improve `MaybeLiveLocals`) - #160693 (Add branch config for perf. unrolling in bors) - #160696 (rustc_codegen_llvm: handle sm_101* features being an alias) - #160706 (renovate: clarify that vulnerability PRs are opened automatically)

rustbot added A-LLVM Area: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues. S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Aug 1, 2026

rustbot assigned ZuseZ4 Aug 1, 2026

rustbot added T-bootstrap Relevant to the bootstrap subteam: Rust's build system (x.py and src/bootstrap) T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Aug 1, 2026

rust-cloud-vms Bot force-pushed the dlopen_offload branch from 1bb876b to 3eee4fe Compare August 1, 2026 13:19