[SYCL][Fusion] Interface with kernel fusion JIT

[sommerlukas]

This is the fifth patch in a series of patches to add an implementation of the kernel fusion extension. We have split the implementation into multiple patches to make them more easy to review.

This patch connects the JIT compiler for kernel fusion (sycl-fusion) with the SYCL runtime.

• Enable the feature by default and add an option to configure.py to disable it.
• Link the runtime against the JIT compiler library as a shared library.
• Add logic to retrieve binaries (SPIR-V) and other information (e.g., accessors) from the SYCL RT and invoke the JIT compiler.
• Representation to store binaries (SPIR-V) returned by JIT compiler in memory for use as PI device binaries.

The integration of the JIT compiler into the SYCL RT is described in this design document.

Signed-off-by: Lukas Sommer [email protected]

[sommerlukas]

The corresponding additions of tests to the LLVM test-suite are currently still a draft PR: sommerlukas/llvm-test-suite#1, because they are blocked by intel/llvm-test-suite#1416, which still requires reviews.

[sommerlukas]

I also tried adding a unit test for the complete_fusion route of the scheduler integration, as discussed with @sergey-semenov here.

Unfortunately, it was not possible to test this as an unit test. To completely test the route using complete_fusion, we would need the JIT compiler to successfully generate a fused kernel. However, the unit tests are generally not compiled with a SYCL-enabled compiler, so no SPIR-V for the kernels might be available to use as input to the JIT compiler.

However, various test cases using the complete_fusion route and the integration into the SYCL runtime scheduler are added as SYCL application tests in sommerlukas/llvm-test-suite#1, so this scenario is sufficiently covered by tests.

[sommerlukas]

/verify with intel/llvm-test-suite#1416

[Naghasan]

LGTM

[dm-vodopyanov]

/summary:run

[sommerlukas]

I rebased this PR and explicitly disabled kernel fusion on Windows, to avoid breaking the post-commit Windows CI while we work on finalizing Windows support.

The updated PR also addresses an issue around symbol visibility that was causing problems with the Intel GPU driver.

[bader]

/testwin

[sommerlukas]

Thanks for the feedback @dm-vodopyanov and @bader!

I addressed your comments in the latest version.

[sommerlukas]

Thanks for the approval!

I'm not authorized to merge this, can someone of @bader or @intel/llvm-gatekeepers merge this please?

[bader]

@sommerlukas, unfortunately, compilation of jit-compiler with clang (XCode compiler to be precise) fails.

See https://github.com/intel/llvm/actions/runs/3910984924/jobs/6683827601.

/Users/runner/work/llvm/llvm/src/llvm/include/llvm/Support/Casting.h:280:45: error: unused parameter 'f' [-Werror,-Wunused-parameter]
  static inline bool isPossible(const From &f) { return true; }
                                            ^
/Users/runner/work/llvm/llvm/src/llvm/include/llvm/Support/Casting.h:604:41: error: unused parameter 't' [-Werror,-Wunused-parameter]
  static inline bool isPresent(const T &t) { return true; }
                                        ^
2 errors generated.

It's a bit surprising, but it looks like LLVM is less strict on enforcing "no warnings" policy.
I think we should avoid mis-compilations due to errors in external code like this.
To be honest, I'm sure how did we end-up with enabling -Werror for jit-compiler project. I know that we enabled it for sycl project by setting SYCL_ENABLE_WERROR CMake variable, but it should not impact jit-compiler. Could you investigate, please?

[sommerlukas]

Hi @bader,

thanks for reporting this.

The file which causes this error is jit_compiler.cpp, which is not part of sycl-fusion (i.e., the JIT compiler), but sycl itself (lives in sycl/source/detail) and connects the SYCL runtime to the JIT compiler. As it is compiled as part of the SYCL runtime, I think it is expected that it is compiled with -Werror if SYCL_ENABLE_WERROR is set.

The warnings (which then become errors with -Werror) are caused by including LLVMContext.h in JITContext.h, which in turn is included by jit_compiler.cpp. I'll look into how we can avoid including LLVMContext.h here by using an opaque pointer or similar.

[sommerlukas]

@bader: I've opened #8017 to address this issue.

With the fix from this PR, I'm able to compile with SYCL_ENABLE_WERROR=ON in my local build (Linux, Clang 10).

[bader]

I'm able to compile with SYCL_ENABLE_WERROR=ON in my local build (Linux, Clang 10).

Were you able to reproduce the problem before the fix with your local build (i.e. Linux, Clang 10)?

[sommerlukas]

Yes, with SYCL_ENABLE_WERROR=ON, my local build failed with the same error message before implementing this fix.