eb17a2e19c
Summary: This can be unset because CMake does not expose this as a raw variable when you use the find_package interface. If it is not set as in the case of standalone builds the clang resource directory won't be found
libclc
libclc is an open source implementation of the library requirements of the OpenCL C programming language, as specified by the OpenCL 1.1 Specification. The following sections of the specification impose library requirements:
- 6.1: Supported Data Types
- 6.2.3: Explicit Conversions
- 6.2.4.2: Reinterpreting Types Using as_type() and as_typen()
- 6.9: Preprocessor Directives and Macros
- 6.11: Built-in Functions
- 9.3: Double Precision Floating-Point
- 9.4: 64-bit Atomics
- 9.5: Writing to 3D image memory objects
- 9.6: Half Precision Floating-Point
libclc is intended to be used with the Clang compiler's OpenCL frontend.
libclc is designed to be portable and extensible. To this end, it provides generic implementations of most library requirements, allowing the target to override the generic implementation at the granularity of individual functions.
libclc currently supports PTX, AMDGPU, SPIRV and CLSPV targets, but support for more targets is welcome.
Configure, build, and install
libclc is built as part of an LLVM runtimes build.
Select the targets to build with LLVM_RUNTIME_TARGETS, and enable libclc for
each selected target with the matching
RUNTIMES_<target-triple>_LLVM_ENABLE_RUNTIMES cache entry.
Configure for the AMDGPU target
cd llvm-project
mkdir build
cd build
cmake ../llvm -G Ninja -DLLVM_ENABLE_PROJECTS="clang" -DCMAKE_BUILD_TYPE=Release \
-DRUNTIMES_amdgcn-amd-amdhsa-llvm_LLVM_ENABLE_RUNTIMES=libclc \
-DLLVM_RUNTIME_TARGETS="amdgcn-amd-amdhsa-llvm"
Configure for the NVPTX64 target
cmake ../llvm -G Ninja -DLLVM_ENABLE_PROJECTS="clang" -DCMAKE_BUILD_TYPE=Release \
-DRUNTIMES_nvptx64-nvidia-cuda_LLVM_ENABLE_RUNTIMES=libclc \
-DLLVM_RUNTIME_TARGETS="nvptx64-nvidia-cuda"
Configure for CLSPV targets
cmake ../llvm -G Ninja -DLLVM_ENABLE_PROJECTS="clang" -DCMAKE_BUILD_TYPE=Release \
-DRUNTIMES_clspv--_LLVM_ENABLE_RUNTIMES=libclc \
-DRUNTIMES_clspv64--_LLVM_ENABLE_RUNTIMES=libclc \
-DLLVM_RUNTIME_TARGETS="clspv--;clspv64--"
Configure for SPIR-V targets
cmake ../llvm -G Ninja -DLLVM_ENABLE_PROJECTS="clang" -DCMAKE_BUILD_TYPE=Release \
-DRUNTIMES_spirv-mesa3d-_LLVM_ENABLE_RUNTIMES=libclc \
-DRUNTIMES_spirv64-mesa3d-_LLVM_ENABLE_RUNTIMES=libclc \
-DLLVM_RUNTIME_TARGETS="spirv-mesa3d-;spirv64-mesa3d-"
To build multiple targets, pass them as a semicolon-separated list in
LLVM_RUNTIME_TARGETS and provide a matching
RUNTIMES_<target-triple>_LLVM_ENABLE_RUNTIMES=libclc entry for each target.
Build
ninja
Install
ninja install
Note you can use the DESTDIR Makefile variable to do staged installs.
DESTDIR=/path/for/staged/install ninja install
Testing
libclc utilizes the LLVM testing infrastructure.
Run all tests
To execute all per-target tests for libclc.
ninja check-libclc
check-libclc is a top-level target that aggregates all per-target tests.
Run target-specific tests
If you are working on a specific target, you can run tests for just that target triple:
ninja check-libclc-<target-triple>
Alternatively, you can run target-specific tests via the runtimes build by pointing to the target-specific build directory:
ninja -C runtimes/runtimes-<target-triple>-bins check-libclc
Out-of-tree build
To build out of tree, or in other words, against an existing LLVM build or install:
CC=$(<path-to>/llvm-config --bindir)/clang cmake \
<path-to>/llvm-project/libclc/CMakeLists.txt -DCMAKE_BUILD_TYPE=Release \
-G Ninja -DLLVM_DIR=$(<path-to>/llvm-config --cmakedir) \
-DLLVM_RUNTIMES_TARGET=<target-triple>
$ ninja
Then install as before.
In both cases, the LLVM used must include the targets you want libclc support for
(AMDGPU and NVPTX are enabled in LLVM by default). Apart from SPIRV where you do
not need an LLVM target but you do need the
llvm-spirv tool available.
Either build this in-tree, or place it in the directory pointed to by
LLVM_TOOLS_BINARY_DIR.