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Revert "[libc] Remove 'packaged' GPU build support (#100208)"
Summary: I forgot that the OpenMP tests still look for this, reverting for now until I can make a fix. This reverts commit c1c6ed8.
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‎libc/cmake/modules/LLVMLibCLibraryRules.cmake‎

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@@ -83,6 +83,97 @@ function(get_all_object_file_deps result fq_deps_list)
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set(${result} ${all_deps} PARENT_SCOPE)
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endfunction()
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# A rule to build a library from a collection of entrypoint objects and bundle
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# it into a GPU fatbinary. Usage is the same as 'add_entrypoint_library'.
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# Usage:
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# add_gpu_entrypoint_library(
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# DEPENDS <list of add_entrypoint_object targets>
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# )
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function(add_gpu_entrypoint_library target_name base_target_name)
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cmake_parse_arguments(
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"ENTRYPOINT_LIBRARY"
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"" # No optional arguments
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"" # No single value arguments
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"DEPENDS" # Multi-value arguments
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${ARGN}
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)
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if(NOT ENTRYPOINT_LIBRARY_DEPENDS)
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message(FATAL_ERROR "'add_entrypoint_library' target requires a DEPENDS list "
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"of 'add_entrypoint_object' targets.")
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endif()
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get_fq_deps_list(fq_deps_list ${ENTRYPOINT_LIBRARY_DEPENDS})
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get_all_object_file_deps(all_deps "${fq_deps_list}")
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# The GPU 'libc' needs to be exported in a format that can be linked with
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# offloading langauges like OpenMP or CUDA. This wraps every GPU object into a
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# fat binary and adds them to a static library.
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set(objects "")
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foreach(dep IN LISTS all_deps)
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set(object $<$<STREQUAL:$<TARGET_NAME_IF_EXISTS:${dep}>,${dep}>:$<TARGET_OBJECTS:${dep}>>)
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string(FIND ${dep} "." last_dot_loc REVERSE)
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math(EXPR name_loc "${last_dot_loc} + 1")
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string(SUBSTRING ${dep} ${name_loc} -1 name)
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if(LIBC_TARGET_ARCHITECTURE_IS_NVPTX)
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set(prefix --image=arch=generic,triple=nvptx64-nvidia-cuda,feature=+ptx63)
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elseif(LIBC_TARGET_ARCHITECTURE_IS_AMDGPU)
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set(prefix --image=arch=generic,triple=amdgcn-amd-amdhsa)
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endif()
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# Use the 'clang-offload-packager' to merge these files into a binary blob.
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add_custom_command(
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OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/binary/${name}.gpubin"
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COMMAND ${CMAKE_COMMAND} -E make_directory ${CMAKE_CURRENT_BINARY_DIR}/binary
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COMMAND ${LIBC_CLANG_OFFLOAD_PACKAGER}
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"${prefix},file=$<JOIN:${object},,file=>" -o
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${CMAKE_CURRENT_BINARY_DIR}/binary/${name}.gpubin
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DEPENDS ${dep} ${base_target_name}
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COMMENT "Packaging LLVM offloading binary for '${object}'"
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)
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add_custom_target(${dep}.__gpubin__ DEPENDS ${dep}
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"${CMAKE_CURRENT_BINARY_DIR}/binary/${name}.gpubin")
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if(TARGET clang-offload-packager)
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add_dependencies(${dep}.__gpubin__ clang-offload-packager)
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endif()
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# CMake does not permit setting the name on object files. In order to have
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# human readable names we create an empty stub file with the entrypoint
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# name. This empty file will then have the created binary blob embedded.
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add_custom_command(
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OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/stubs/${name}.cpp"
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COMMAND ${CMAKE_COMMAND} -E make_directory ${CMAKE_CURRENT_BINARY_DIR}/stubs
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COMMAND ${CMAKE_COMMAND} -E touch ${CMAKE_CURRENT_BINARY_DIR}/stubs/${name}.cpp
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DEPENDS ${dep} ${dep}.__gpubin__ ${base_target_name}
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)
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add_custom_target(${dep}.__stub__
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DEPENDS ${dep}.__gpubin__ "${CMAKE_CURRENT_BINARY_DIR}/stubs/${name}.cpp")
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add_library(${dep}.__fatbin__
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EXCLUDE_FROM_ALL OBJECT
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"${CMAKE_CURRENT_BINARY_DIR}/stubs/${name}.cpp"
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)
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# This is always compiled for the LLVM host triple instead of the native GPU
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# triple that is used by default in the build.
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target_compile_options(${dep}.__fatbin__ BEFORE PRIVATE -nostdlib)
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target_compile_options(${dep}.__fatbin__ PRIVATE
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--target=${LLVM_HOST_TRIPLE}
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"SHELL:-Xclang -fembed-offload-object=${CMAKE_CURRENT_BINARY_DIR}/binary/${name}.gpubin")
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add_dependencies(${dep}.__fatbin__
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${dep} ${dep}.__stub__ ${dep}.__gpubin__ ${base_target_name})
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# Set the list of newly create fat binaries containing embedded device code.
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list(APPEND objects $<TARGET_OBJECTS:${dep}.__fatbin__>)
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endforeach()
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add_library(
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${target_name}
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STATIC
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${objects}
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)
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set_target_properties(${target_name} PROPERTIES LIBRARY_OUTPUT_DIRECTORY ${LIBC_LIBRARY_DIR})
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endfunction(add_gpu_entrypoint_library)
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# A rule to build a library from a collection of entrypoint objects and bundle
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# it in a single LLVM-IR bitcode file.
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# Usage:

‎libc/docs/gpu/building.rst‎

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@@ -151,6 +151,25 @@ Build overview
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Once installed, the GPU build will create several files used for different
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targets. This section will briefly describe their purpose.
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**lib/<host-triple>/libcgpu-amdgpu.a or lib/libcgpu-amdgpu.a**
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A static library containing fat binaries supporting AMD GPUs. These are built
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using the support described in the `clang documentation
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<https://clang.llvm.org/docs/OffloadingDesign.html>`_. These are intended to
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be static libraries included natively for offloading languages like CUDA, HIP,
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or OpenMP. This implements the standard C library.
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**lib/<host-triple>/libmgpu-amdgpu.a or lib/libmgpu-amdgpu.a**
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A static library containing fat binaries that implements the standard math
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library for AMD GPUs.
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**lib/<host-triple>/libcgpu-nvptx.a or lib/libcgpu-nvptx.a**
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A static library containing fat binaries that implement the standard C library
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for NVIDIA GPUs.
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**lib/<host-triple>/libmgpu-nvptx.a or lib/libmgpu-nvptx.a**
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A static library containing fat binaries that implement the standard math
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library for NVIDIA GPUs.
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**include/<target-triple>**
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The include directory where all of the generated headers for the target will
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go. These definitions are strictly for the GPU when being targeted directly.

‎libc/docs/gpu/using.rst‎

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@@ -34,17 +34,16 @@ described in the `clang documentation
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by the OpenMP toolchain, but is currently opt-in for the CUDA and HIP toolchains
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through the ``--offload-new-driver``` and ``-fgpu-rdc`` flags.
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In order or link the GPU runtime, we simply pass this library to the embedded
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device linker job. This can be done using the ``-Xoffload-linker`` option, which
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forwards an argument to a ``clang`` job used to create the final GPU executable.
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The toolchain should pick up the C libraries automatically in most cases, so
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this shouldn't be necessary.
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The installation should contain a static library called ``libcgpu-amdgpu.a`` or
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``libcgpu-nvptx.a`` depending on which GPU architectures your build targeted.
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These contain fat binaries compatible with the offloading toolchain such that
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they can be used directly.
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.. code-block:: sh
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$> clang openmp.c -fopenmp --offload-arch=gfx90a -Xoffload-linker -lc
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$> clang cuda.cu --offload-arch=sm_80 --offload-new-driver -fgpu-rdc -Xoffload-linker -lc
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$> clang hip.hip --offload-arch=gfx940 --offload-new-driver -fgpu-rdc -Xoffload-linker -lc
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$> clang openmp.c -fopenmp --offload-arch=gfx90a -lcgpu-amdgpu
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$> clang cuda.cu --offload-arch=sm_80 --offload-new-driver -fgpu-rdc -lcgpu-nvptx
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$> clang hip.hip --offload-arch=gfx940 --offload-new-driver -fgpu-rdc -lcgpu-amdgpu
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This will automatically link in the needed function definitions if they were
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required by the user's application. Normally using the ``-fgpu-rdc`` option

‎libc/lib/CMakeLists.txt‎

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@@ -40,6 +40,20 @@ foreach(archive IN ZIP_LISTS
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# Add the offloading version of the library for offloading languages. These
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# are installed in the standard search path separate from the other libraries.
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if(LIBC_TARGET_OS_IS_GPU)
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add_gpu_entrypoint_library(
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${archive_1}gpu
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${archive_1}
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DEPENDS
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${${archive_2}}
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)
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set_target_properties(
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${archive_1}gpu
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PROPERTIES
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ARCHIVE_OUTPUT_NAME ${archive_0}gpu-${LIBC_TARGET_ARCHITECTURE}
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ARCHIVE_OUTPUT_DIRECTORY ${LLVM_LIBRARY_OUTPUT_INTDIR}
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)
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list(APPEND added_gpu_archive_targets ${archive_1}gpu)
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add_bitcode_entrypoint_library(
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${archive_1}bitcode
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${archive_1}
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PROPERTIES
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OUTPUT_NAME ${archive_1}.bc
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)
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add_dependencies(${archive_1}gpu ${archive_1}bitcode)
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list(APPEND added_gpu_bitcode_targets ${archive_1}bitcode)
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endif()
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endforeach()

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