Offload: Build offload as a single Step #150108

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Open

ZuseZ4 wants to merge 5 commits into rust-lang:main from ZuseZ4:offload-build-rework

+237 −14

Member

ZuseZ4 commented Dec 17, 2025 •

edited

Loading

Since it looks like we'll postpone enabling offload in CI for a bit, I factored out these improvements which we want independently. I locally tested both build options successfully, the in-tree-clang build, as well as the build where we provide a path to an external clang.

Collaborator

rustbot commented Dec 17, 2025

This PR modifies src/bootstrap/src/core/config.

If appropriate, please update CONFIG_CHANGE_HISTORY in src/bootstrap/src/utils/change_tracker.rs.

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

This PR modifies bootstrap.example.toml.

If appropriate, please update CONFIG_CHANGE_HISTORY in src/bootstrap/src/utils/change_tracker.rs.

rustbot added S-waiting-on-review T-bootstrap labels

rustbot assigned Kobzol

Collaborator

rustbot commented Dec 17, 2025

Kobzol is not on the review rotation at the moment.
They may take a while to respond.

ZuseZ4 force-pushed the offload-build-rework branch from 93bc6ea to 4b2d2b9 Compare

December 17, 2025 18:32

Collaborator

rustbot commented Dec 17, 2025

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

This comment has been minimized.

Sign in to view


          Change how we build offload as a single Step

dbe2964

ZuseZ4 force-pushed the offload-build-rework branch from 4b2d2b9 to dbe2964 Compare

December 17, 2025 21:08

Kobzol reviewed

View reviewed changes

Member

Kobzol left a comment •

edited by rustbot

Loading

Left some comments, otherwise it looks reasonable.

View changes since this review

bootstrap.example.toml Outdated Show resolved Hide resolved

src/bootstrap/src/core/config/config.rs Outdated Show resolved Hide resolved

src/bootstrap/src/core/config/toml/llvm.rs Outdated Show resolved Hide resolved

src/bootstrap/src/core/build_steps/llvm.rs Outdated Show resolved Hide resolved

src/bootstrap/src/core/build_steps/llvm.rs

    
              }

              impl Step for OmpOffload {

                  type Output = PathBuf;

Member

Kobzol Dec 19, 2025

Could you please modify this to be more similar to #150071? So that it returns some named struct that contains the final path to the libXXX dylibs. So that code that then uses the output (e.g. in the Assemble step) does not need to guess how are the files named, and the corresponding logic to find the files is localized within this step.

src/bootstrap/src/core/build_steps/llvm.rs Outdated Show resolved Hide resolved

src/bootstrap/src/core/build_steps/llvm.rs

    
                      // binaries. We therefore write our offload artifacts into it's own subfolder. We use a

                      // subfolder, so that all the logic that processes our build artifacts (hopefully) also

                      // automatically manages our artifacts in the subfolder.

                      let out_dir = builder.llvm_out(target).join("offload-outdir");

Member

Kobzol Dec 19, 2025

Actually, I think that we should use a different build directory, and handle the copying manually in the Assemble step. We should not rely on other code copying the offload stuff for us. Partly also because we will want to have it as a separate component, and not put the offload things into e.g. the rustc or llvm-tools component by accident.

src/bootstrap/src/core/build_steps/llvm.rs Outdated Show resolved Hide resolved

src/bootstrap/src/core/build_steps/compile.rs Outdated

    
                                  builder.sysroot_target_libdir(target_compiler, target_compiler.host);

                              let lib_ext = std::env::consts::DLL_EXTENSION;

                              let libenzyme = "libLLVMOffload";

Member

Kobzol Dec 19, 2025

As noted in another comment, the logic for locating these components should ideally be localized within the offload step itself. It should then contain the paths to the dylibs (either just as a Vec<PathBuf>, or as three fields, depending on whether it is useful to distinguish them), and the code here in Assembly should just copy them to the correct directories.

src/bootstrap/src/core/build_steps/compile.rs Outdated Show resolved Hide resolved

Kobzol mentioned this pull request

Enable Offload in CI #148671

Draft

Member

Kobzol commented Dec 19, 2025

@rustbot author

rustbot added S-waiting-on-author and removed S-waiting-on-review labels

ZuseZ4 mentioned this pull request

Tracking Issue for GPU-offload #131513

Open

5 tasks

ZuseZ4 added 3 commits

December 20, 2025 10:01


          addressing feedback 1

49cb23c


          addressing feedback 2

235fe6f


          change c/cxx flags

4a3acaa

This comment has been minimized.

Sign in to view


          addressing feedback

d7e7e81

Collaborator

rust-log-analyzer commented Dec 21, 2025

The job aarch64-gnu-llvm-20-2 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

    = note: `-D unused-mut` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(unused_mut)]`

error: could not compile `bootstrap` (lib) due to 1 previous error
failed to run: /checkout/obj/build/aarch64-unknown-linux-gnu/stage0/bin/cargo build --jobs=default --manifest-path /checkout/src/bootstrap/Cargo.toml -Zroot-dir=/checkout --locked --features build-metrics
Build completed unsuccessfully in 0:00:19
make: *** [Makefile:99: prepare] Error 1
Command failed. Attempt 2/5:
##[group]Building bootstrap
   Compiling bootstrap v0.0.0 (/checkout/src/bootstrap)
---
    = note: `-D unused-mut` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(unused_mut)]`

error: could not compile `bootstrap` (lib) due to 1 previous error
failed to run: /checkout/obj/build/aarch64-unknown-linux-gnu/stage0/bin/cargo build --jobs=default --manifest-path /checkout/src/bootstrap/Cargo.toml -Zroot-dir=/checkout --locked --features build-metrics
Build completed unsuccessfully in 0:00:03
make: *** [Makefile:99: prepare] Error 1
Command failed. Attempt 3/5:
##[group]Building bootstrap
   Compiling bootstrap v0.0.0 (/checkout/src/bootstrap)
---
    = note: `-D unused-mut` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(unused_mut)]`

error: could not compile `bootstrap` (lib) due to 1 previous error
failed to run: /checkout/obj/build/aarch64-unknown-linux-gnu/stage0/bin/cargo build --jobs=default --manifest-path /checkout/src/bootstrap/Cargo.toml -Zroot-dir=/checkout --locked --features build-metrics
Build completed unsuccessfully in 0:00:03
make: *** [Makefile:99: prepare] Error 1
Command failed. Attempt 4/5:
##[group]Building bootstrap
   Compiling bootstrap v0.0.0 (/checkout/src/bootstrap)
---
    = note: `-D unused-mut` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(unused_mut)]`

error: could not compile `bootstrap` (lib) due to 1 previous error
failed to run: /checkout/obj/build/aarch64-unknown-linux-gnu/stage0/bin/cargo build --jobs=default --manifest-path /checkout/src/bootstrap/Cargo.toml -Zroot-dir=/checkout --locked --features build-metrics
Build completed unsuccessfully in 0:00:03
make: *** [Makefile:99: prepare] Error 1
Command failed. Attempt 5/5:
##[group]Building bootstrap
   Compiling bootstrap v0.0.0 (/checkout/src/bootstrap)
---
    = note: `-D unused-mut` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(unused_mut)]`

error: could not compile `bootstrap` (lib) due to 1 previous error
failed to run: /checkout/obj/build/aarch64-unknown-linux-gnu/stage0/bin/cargo build --jobs=default --manifest-path /checkout/src/bootstrap/Cargo.toml -Zroot-dir=/checkout --locked --features build-metrics
Build completed unsuccessfully in 0:00:03
make: *** [Makefile:99: prepare] Error 1
The command has failed after 5 attempts.
  local time: Sun Dec 21 10:37:12 UTC 2025
  network time: Sun, 21 Dec 2025 10:37:12 GMT

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

S-waiting-on-author T-bootstrap