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llvm/llvm-project/libclc/8edf6dd9ceec3d053d5f4032991e307254605a4a
commit
8edf6dd9ceec3d053d5f4032991e307254605a4a
[log]
author
Matt Arsenault <Matthew.Arsenault@amd.com>
Fri Mar 20 08:33:31 2026 +0100
committer
Copybara-Service <copybara-worker@google.com>
Fri Mar 20 00:36:53 2026 -0700
tree
68d8fc4c636dbe3b5ceeb00b19213538b1d00e68
parent
d8f9df7b4a1eef5bd2d0480f0f2eed40f9924ab9 [diff]
libclc: Use log intrinsic for half and float cases for amdgpu (#187538)

This is pretty verbose and ugly. We're pulling the base implementation
in for the double cases, and scalarizing it. Also fully defining the
half and float cases to directly use the intrinsic, for all vector
types. It would be much more convenient if we had linker based overrides
for the generic implementations, rather than per source file.

GitOrigin-RevId: edbe8277c10433ded3b8b28375dd8b0e85d108f1
5 files changed
tree: 68d8fc4c636dbe3b5ceeb00b19213538b1d00e68
  1. clc/
  2. cmake/
  3. opencl/
  4. test/
  5. www/
  6. CMakeLists.txt
  7. compile-test.sh
  8. CREDITS.TXT
  9. LICENSE.TXT
  10. Maintainers.md
  11. README.md
README.md

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.

Compiling and installing

(in the following instructions you can use make or ninja)

For an in-tree build, Clang must also be built at the same time:

$ cmake <path-to>/llvm-project/llvm/CMakeLists.txt -DLLVM_ENABLE_PROJECTS="clang" \
    -DLLVM_ENABLE_RUNTIMES="libclc" -DCMAKE_BUILD_TYPE=Release -G Ninja
$ ninja

Then install:

$ ninja install

Note you can use the DESTDIR Makefile variable to do staged installs.

$ DESTDIR=/path/for/staged/install ninja install

To build out of tree, or in other words, against an existing LLVM build or install:

$ cmake <path-to>/llvm-project/libclc/CMakeLists.txt -DCMAKE_BUILD_TYPE=Release \
  -G Ninja -DLLVM_DIR=$(<path-to>/llvm-config --cmakedir)
$ ninja

Then install as before.

In both cases this will include all supported targets. You can choose which targets are enabled by passing -DLIBCLC_TARGETS_TO_BUILD to CMake. The default is all.

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.

Website

https://libclc.llvm.org/