https://github.com/llvmbot created https://github.com/llvm/llvm-project/pull/179496
Backport e07a1182fd58a5b48a2c78bc3ae03872186d4ae0 Requested by: @jhuber6 >From cc29f0021a904666f5bba9716ea6b0535b425370 Mon Sep 17 00:00:00 2001 From: Joseph Huber <[email protected]> Date: Tue, 3 Feb 2026 10:35:17 -0600 Subject: [PATCH] [libc] Tweak the runtimes cross-build for GPU (#178548) Summary: We should likely use `-DLLVM_DEFAULT_TARGET_TRIPLE` as the general source of truth, make the handling work with that since we use it for the output directories. Fix the creation of startup files in this mode and make sure it can detect the GPU properly. Fixes: https://github.com/llvm/llvm-project/issues/179375 (cherry picked from commit e07a1182fd58a5b48a2c78bc3ae03872186d4ae0) --- .../modules/prepare_libc_gpu_build.cmake | 4 +- libc/docs/gpu/building.rst | 40 +++---------------- libc/startup/gpu/CMakeLists.txt | 1 + 3 files changed, 9 insertions(+), 36 deletions(-) diff --git a/libc/cmake/modules/prepare_libc_gpu_build.cmake b/libc/cmake/modules/prepare_libc_gpu_build.cmake index 4d12a5917a56f..55cd0242eedeb 100644 --- a/libc/cmake/modules/prepare_libc_gpu_build.cmake +++ b/libc/cmake/modules/prepare_libc_gpu_build.cmake @@ -17,8 +17,8 @@ if(NOT LLVM_LIBC_FULL_BUILD) endif() # Set the required flags globally so standard CMake utilities can compile. -if(LIBC_TARGET_TRIPLE) - set(CMAKE_REQUIRED_FLAGS "--target=${LIBC_TARGET_TRIPLE}") +if(NOT CMAKE_CXX_COMPILER_TARGET) + set(CMAKE_REQUIRED_FLAGS "${LIBC_COMPILE_OPTIONS_DEFAULT}") endif() # Optionally set up a job pool to limit the number of GPU tests run in parallel. diff --git a/libc/docs/gpu/building.rst b/libc/docs/gpu/building.rst index 9f9528b30d9bf..a7791331423dc 100644 --- a/libc/docs/gpu/building.rst +++ b/libc/docs/gpu/building.rst @@ -100,12 +100,12 @@ targeting a GPU architecture. $> TARGET_C_COMPILER=</path/to/clang> $> TARGET_CXX_COMPILER=</path/to/clang++> $> cmake ../runtimes \ # Point to the runtimes build - -G Ninja \ - -DLLVM_ENABLE_RUNTIMES=libc \ - -DCMAKE_C_COMPILER=$TARGET_C_COMPILER \ - -DCMAKE_CXX_COMPILER=$TARGET_CXX_COMPILER \ - -DLLVM_LIBC_FULL_BUILD=ON \ - -DLLVM_RUNTIMES_TARGET=$TARGET_TRIPLE \ + -G Ninja \ + -DLLVM_ENABLE_RUNTIMES=libc \ + -DCMAKE_C_COMPILER=$TARGET_C_COMPILER \ + -DCMAKE_CXX_COMPILER=$TARGET_CXX_COMPILER \ + -DLLVM_LIBC_FULL_BUILD=ON \ + -DLLVM_DEFAULT_TARGET_TRIPLE=$TARGET_TRIPLE \ -DCMAKE_BUILD_TYPE=Release $> ninja install @@ -113,34 +113,6 @@ The above steps will result in a build targeting one of the supported GPU architectures. Building for multiple targets requires separate CMake invocations. -Standalone cross build ----------------------- - -The GPU build can also be targeted directly as long as the compiler used is a -supported ``clang`` compiler. This method is generally not recommended as it can -only target a single GPU architecture. - -.. code-block:: sh - - $> cd llvm-project # The llvm-project checkout - $> mkdir build # A different build directory for the build tools - $> cd build - $> CLANG_C_COMPILER=</path/to/clang> # Must be a trunk build - $> CLANG_CXX_COMPILER=</path/to/clang++> # Must be a trunk build - $> TARGET_TRIPLE=<amdgcn-amd-amdhsa or nvptx64-nvidia-cuda> - $> cmake ../llvm \ # Point to the llvm directory - -G Ninja \ - -DLLVM_ENABLE_PROJECTS=libc \ - -DCMAKE_C_COMPILER=$CLANG_C_COMPILER \ - -DCMAKE_CXX_COMPILER=$CLANG_CXX_COMPILER \ - -DLLVM_LIBC_FULL_BUILD=ON \ - -DLIBC_TARGET_TRIPLE=$TARGET_TRIPLE \ - -DCMAKE_BUILD_TYPE=Release - $> ninja install - -This will build and install the GPU C library along with all the other LLVM -libraries. - Build overview ============== diff --git a/libc/startup/gpu/CMakeLists.txt b/libc/startup/gpu/CMakeLists.txt index fa326ef46a9d1..63e2a6c5dee1a 100644 --- a/libc/startup/gpu/CMakeLists.txt +++ b/libc/startup/gpu/CMakeLists.txt @@ -34,6 +34,7 @@ function(add_startup_object name) RUNTIME_OUTPUT_DIRECTORY ${LIBC_LIBRARY_DIR} RUNTIME_OUTPUT_NAME ${name}.o) target_link_options(${fq_target_name}.exe PRIVATE + ${LIBC_COMPILE_OPTIONS_DEFAULT} "-r" "-nostdlib" "-flto" "-Wl,--lto-emit-llvm") endif() endfunction() _______________________________________________ llvm-branch-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
