[SYCL] Remove fusion implemention and refactor sycl-jit library (#17929)

Removes the remaining fusion implementation and refactors the `sycl-jit`
library to better capture the current use-cases: SYCL runtime
compilation (RTC), and specialization constant materialization (SCM).

High-level notes:
- Split the entrypoints for RTC, SCM and option handling, formerly in
`KernelFusion[.h|.cpp]`, into separate files
- A significant amount of infrastructure became unused after removing
the fusion implementation. The remaining facilities are:
  - CMake setup to link LLVM libraries and produce a pass plugin library
- Translation from LLVM module to SPIRV and PTX/AMDGCN (loading and
linking multiple SPIRV or LLVM modules was unused and removed)
- `JITContext` class owning "binaries" (could be SPIRV blob or
PTX/AMDGCN text). At the interface, we use `JITBinaryInfo` (fka
`SYCLKernelBinaryInfo`), which is a non-owning descriptor type
  - Option handling
- Dropped "fusion" terminology, and mostly dropped "kernel" terminology,
because RTC and SCM deal with device images (runtime-side) respectively
LLVM modules (jit-side). One exception is the translation helper, which
optionally takes a kernel name, which is in turned used by the
PTX/AMDGCN translation to obtain target attributes from the
corresponding kernel function.
- The `sycl-jit-common` library (in `sycl-jit/common` directory) was
removed because it became header-only and the headers were no longer
used by the pass library (so could be moved to
`sycl-jit/jit-compiler/include`)

---------

Signed-off-by: Julian Oppermann <[email protected]>
Co-authored-by: Steffen Larsen <[email protected]>

Author: jopperm

sycl-jit/CMakeLists.txt

@@ -13,14 +13,13 @@ if (NOT WIN32 AND NOT CYGWIN)
   # Set library-wide warning options.
   set(SYCL_JIT_WARNING_FLAGS -Wall -Wextra)
 
-  option(SYCL_JIT_ENABLE_WERROR "Treat all warnings as errors in SYCL kernel JIT library" ON)
+  option(SYCL_JIT_ENABLE_WERROR "Treat all warnings as errors in SYCL JIT library" ON)
   if(SYCL_JIT_ENABLE_WERROR)
     list(APPEND SYCL_JIT_WARNING_FLAGS -Werror)
   endif(SYCL_JIT_ENABLE_WERROR)
 endif()
 
 
-add_subdirectory(common)
 add_subdirectory(jit-compiler)
 add_subdirectory(passes)
 

sycl-jit/README.md

@@ -1,9 +1,19 @@
-# SYCL Kernel Fusion Compiler
+# SYCL-JIT library
 
-Basic JIT compiler infrastructure to perform online kernel fusion of SYCL kernels at runtime.
+A library to make LLVM-based tooling available to the SYCL runtime.
 
-The experimental SYCL extension for kernel fusion is described in 
-[this proposal](../sycl/doc/extensions/experimental/sycl_ext_codeplay_kernel_fusion.asciidoc).
+## Current use-cases
 
-The design of the JIT compiler is described in this 
-[design document](../sycl/doc/design/KernelFusionJIT.md).
+- Materialization of specialization constants for third-party GPUs
+  - Entrypoint declared in `jit-compiler/include/Materializer.h`
+- Runtime-compilation of SYCL code (via `kernel_compiler` extension)
+  - Entrypoints declared in `jit-compiler/include/RTC.h`
+
+## Provided infrastructure
+
+- CMake setup to link LLVM and Clang libraries and produce a pass plugin library
+  - NB: Clang can be invoked programmatically via the LibTooling API
+- Translation from LLVM module to SPIR-V and PTX/AMDGCN; the resulting
+  "binaries" (i.e. SPIR-V blob or PTX/AMDGCN text) are managed by the
+  `JITContext` singleton class
+- Option handling