[SYCL][Driver] Fix spurious OpenMP error with --save-temps and -fsycl-targets

[srividya-sundaram]

Problem

clang++ --save-temps -fsycl -fsycl-targets=intel_gpu_pvc -o t t.cpp fails with:

error: OpenMP target is invalid: 'intel_gpu_pvc'

The same command without --save-temps works fine.

Root Cause

Without --save-temps, the driver collapses preprocess + compile + backend + assemble into a single cc1 invocation (-emit-obj). The outermost action in constructJob is an AssembleJobAction, so the block that injects -fsycl-targets= into cc1 args (guarded by isa<CompileJobAction>(JA)) never fires.

With --save-temps, collapsing is disabled and the host compile becomes a separate cc1 invocation emitting LLVM BC (-emit-llvm-bc, output type TY_LLVM_BC). The guard fires and -fsycl-targets=intel_gpu_pvc is added to that cc1's arguments.

Since -fsycl-targets= is an alias for --offload-targets=, CompilerInvocation.cpp unconditionally validates the value as an OpenMP target triple. intel_gpu_pvc is a SYCL-specific shorthand, not a valid triple, so it fails with the misleading OpenMP error.

Fix

Skip the -fsycl-targets= injection when the output type is TY_LLVM_BC. That step does not need it — all target-specific decisions are already baked into the preprocessed .ii via the integration header. The fix applies to both the old and new offload drivers.

Testing

Added tests to sycl-offload-save-temps.cpp and sycl-offload-save-temps-old-model.cpp verifying that the host -emit-llvm-bc step does not receive -fsycl-targets= for both spir64_gen-unknown-unknown and intel_gpu_pvc targets.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Fixes a SYCL driver issue where --save-temps causes the host -emit-llvm-bc cc1 invocation to receive -fsycl-targets=…, which is an alias for --offload-targets=… and triggers OpenMP target-triple validation (failing on SYCL shorthands like intel_gpu_pvc). The change prevents that argument injection specifically for the host bitcode-emission step and adds regression tests for both the new and old offload driver models.

Changes:

• Skip -fsycl-targets= injection for host SYCL CompileJobActions producing TY_LLVM_BC (the -emit-llvm-bc step exposed by --save-temps).
• Add driver tests ensuring the host -emit-llvm-bc command line does not contain -fsycl-targets= for both a real triple and a SYCL shorthand target.
• Cover both the new offload driver and the old model.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
clang/lib/Driver/ToolChains/Clang.cpp	Avoids injecting -fsycl-targets= into the host SYCL bitcode-emission cc1 invocation (prevents spurious OpenMP target validation).
clang/test/Driver/sycl-offload-save-temps.cpp	Adds new-driver regression checks that the host -emit-llvm-bc line does not include -fsycl-targets= (including intel_gpu_pvc).
clang/test/Driver/sycl-offload-save-temps-old-model.cpp	Adds old-driver regression checks for the same condition as above.

[srividya-sundaram]

The CI failures on both Linux and Windows are unrelated to this PR.

Linux failure (SYCL Pre Commit on Linux):

• Failing test: SYCL :: SpecConstants/2020/nested-non-packed-struct.cpp
• This is an E2E runtime test for SYCL specialization constants on the CUDA GPU backend. It fails with Assertion 'new_data == data' failed — a pre-existing bug in the CUDA adapter's handling of specialization constants for structs with large alignas alignment.
• This PR only touches clang/lib/Driver/ToolChains/Clang.cpp and two driver test files; no specialization constant or CUDA adapter code was modified.

Windows failure (SYCL Pre Commit on Windows):

• sycl/test-e2e/ESIMD/api/replicate_smoke.cpp - an end-to-end ESIMD GPU kernel test that hung on the Windows GPU runner.

This PR's change is a one-line guard in Clang::ConstructJob that skips injecting -fsycl-targets= when the output type is TY_LLVM_BC, fixing a spurious OpenMP error with --save-temps. It has no impact on runtime behavior, specialization constants, or any Windows-specific compilation paths beyond what is covered by the added driver tests.