[libclc] Enable LLVM_RUNTIME_TARGETS in build system (#189892)

libclc target is now passed in from LLVM_RUNTIME_TARGETS. The old configure flow based on `-DLLVM_ENABLE_RUNTIMES=libclc` is deprecated because libclc no longer has a default target. `-DLLVM_ENABLE_RUNTIMES=libclc -DLLVM_RUNTIME_TARGETS="<target-triple>"` still works but it is considered legacy. The new standard build requires: Each target must now be selected explicitly on the CMake command line through the runtimes target-specific cache entry and LLVM_RUNTIME_TARGETS. For example: -DRUNTIMES_amdgcn-amd-amdhsa-llvm_LLVM_ENABLE_RUNTIMES=libclc -DLLVM_RUNTIME_TARGETS="amdgcn-amd-amdhsa-llvm" -DRUNTIMES_nvptx64-nvidia-cuda_LLVM_ENABLE_RUNTIMES=libclc -DLLVM_RUNTIME_TARGETS="nvptx64-nvidia-cuda" -DRUNTIMES_clspv--_LLVM_ENABLE_RUNTIMES=libclc -DLLVM_RUNTIME_TARGETS="clspv--" -DRUNTIMES_clspv64--_LLVM_ENABLE_RUNTIMES=libclc -DLLVM_RUNTIME_TARGETS="clspv64--" -DRUNTIMES_spirv-mesa3d-_LLVM_ENABLE_RUNTIMES=libclc -DLLVM_RUNTIME_TARGETS="spirv-mesa3d-" -DRUNTIMES_spirv64-mesa3d-_LLVM_ENABLE_RUNTIMES=libclc -DLLVM_RUNTIME_TARGETS="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. Updated README.md to document the new build flow. --------- Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
2026-04-13 08:19:08 +08:00
parent 507d823392
commit 121f5a96ff
8 changed files with 287 additions and 209 deletions
--- a/.ci/compute_projects.py
+++ b/.ci/compute_projects.py
@@ -98,6 +98,12 @@ EXCLUDE_LINUX = {
    "openmp",  # https://github.com/google/llvm-premerge-checks/issues/410
 }

+# Runtimes configured for cross-compilation using LLVM_RUNTIME_TARGETS.
+# The same build may also use LLVM_ENABLE_RUNTIMES for other runtimes.
+CROSS_COMPILATION_RUNTIMES = {
+    "libclc",
+}
+
 EXCLUDE_WINDOWS = {
    "cross-project-tests",  # TODO(issues/132797): Tests are failing.
    "openmp",  # TODO(issues/132799): Does not detect perl installation.
@@ -147,7 +153,7 @@ PROJECT_CHECK_TARGETS = {
    "flang": "check-flang",
    "flang-rt": "check-flang-rt",
    "libc": "check-libc",
-    "libclc": "check-libclc",
+    "libclc": "check-libclc-amdgcn-amd-amdhsa-llvm",
    "lld": "check-lld",
    "lldb": "check-lldb",
    "mlir": "check-mlir",
@@ -276,7 +282,9 @@ def _compute_runtimes_to_build(
    for modified_project in modified_projects:
        if modified_project in DEPENDENT_RUNTIMES_TO_BUILD:
            runtimes_to_build.update(DEPENDENT_RUNTIMES_TO_BUILD[modified_project])
-    return _exclude_projects(runtimes_to_build, platform)
+    runtimes_to_build = _exclude_projects(runtimes_to_build, platform)
+    runtimes_to_build -= CROSS_COMPILATION_RUNTIMES
+    return runtimes_to_build


 def _path_matches(matcher: tuple[str], file_path: tuple[str]) -> bool:
@@ -320,7 +328,10 @@ def get_env_variables(modified_files: list[str], platform: str) -> Set[str]:
    runtimes_to_build = _compute_runtimes_to_build(
        runtimes_to_test | runtimes_to_test_needs_reconfig, modified_projects, platform
    )
-    projects_to_build = _compute_projects_to_build(projects_to_test, runtimes_to_build)
+    cross_runtimes_to_test = runtimes_to_test & CROSS_COMPILATION_RUNTIMES
+    projects_to_build = _compute_projects_to_build(
+        projects_to_test, runtimes_to_build | cross_runtimes_to_test
+    )
    projects_check_targets = _compute_project_check_targets(projects_to_test)
    runtimes_check_targets = _compute_project_check_targets(runtimes_to_test)
    runtimes_check_targets_needs_reconfig = _compute_project_check_targets(
--- a/.ci/compute_projects_test.py
+++ b/.ci/compute_projects_test.py
@@ -265,8 +265,11 @@ class TestComputeProjects(unittest.TestCase):
        )
        self.assertEqual(env_variables["projects_to_build"], "clang;llvm")
        self.assertEqual(env_variables["project_check_targets"], "")
-        self.assertEqual(env_variables["runtimes_to_build"], "libclc")
-        self.assertEqual(env_variables["runtimes_check_targets"], "check-libclc")
+        self.assertEqual(env_variables["runtimes_to_build"], "")
+        self.assertEqual(
+            env_variables["runtimes_check_targets"],
+            "check-libclc-amdgcn-amd-amdhsa-llvm",
+        )
        self.assertEqual(env_variables["runtimes_check_targets_needs_reconfig"], "")

    def test_exclude_docs(self):
@@ -303,11 +306,11 @@ class TestComputeProjects(unittest.TestCase):
        )
        self.assertEqual(
            env_variables["runtimes_to_build"],
-            "compiler-rt;flang-rt;libc;libclc;libcxx;libcxxabi;libunwind",
+            "compiler-rt;flang-rt;libc;libcxx;libcxxabi;libunwind",
        )
        self.assertEqual(
            env_variables["runtimes_check_targets"],
-            "check-compiler-rt check-flang-rt check-libc check-libclc",
+            "check-compiler-rt check-flang-rt check-libc check-libclc-amdgcn-amd-amdhsa-llvm",
        )
        self.assertEqual(
            env_variables["runtimes_check_targets_needs_reconfig"],
@@ -328,11 +331,11 @@ class TestComputeProjects(unittest.TestCase):
        )
        self.assertEqual(
            env_variables["runtimes_to_build"],
-            "compiler-rt;libclc",
+            "compiler-rt",
        )
        self.assertEqual(
            env_variables["runtimes_check_targets"],
-            "check-compiler-rt check-libclc",
+            "check-compiler-rt check-libclc-amdgcn-amd-amdhsa-llvm",
        )
        self.assertEqual(
            env_variables["runtimes_check_targets_needs_reconfig"],
@@ -377,11 +380,11 @@ class TestComputeProjects(unittest.TestCase):
        )
        self.assertEqual(
            env_variables["runtimes_to_build"],
-            "compiler-rt;flang-rt;libc;libclc;libcxx;libcxxabi;libunwind",
+            "compiler-rt;flang-rt;libc;libcxx;libcxxabi;libunwind",
        )
        self.assertEqual(
            env_variables["runtimes_check_targets"],
-            "check-compiler-rt check-flang-rt check-libc check-libclc",
+            "check-compiler-rt check-flang-rt check-libc check-libclc-amdgcn-amd-amdhsa-llvm",
        )
        self.assertEqual(
            env_variables["runtimes_check_targets_needs_reconfig"],
@@ -412,11 +415,11 @@ class TestComputeProjects(unittest.TestCase):
        )
        self.assertEqual(
            env_variables["runtimes_to_build"],
-            "compiler-rt;flang-rt;libc;libclc;libcxx;libcxxabi;libunwind",
+            "compiler-rt;flang-rt;libc;libcxx;libcxxabi;libunwind",
        )
        self.assertEqual(
            env_variables["runtimes_check_targets"],
-            "check-compiler-rt check-flang-rt check-libc check-libclc",
+            "check-compiler-rt check-flang-rt check-libc check-libclc-amdgcn-amd-amdhsa-llvm",
        )
        self.assertEqual(
            env_variables["runtimes_check_targets_needs_reconfig"],
--- a/.ci/monolithic-linux.sh
+++ b/.ci/monolithic-linux.sh
@@ -31,6 +31,14 @@ enable_cir="${6}"

 lit_args="-v --xunit-xml-output ${BUILD_DIR}/test-results.xml --use-unique-output-file-name --timeout=1200 --time-tests --succinct"

+runtime_cmake_args=()
+if [[ " ${runtime_targets} " == *" check-libclc-amdgcn-amd-amdhsa-llvm "* ]]; then
+  runtime_cmake_args+=(
+    -D RUNTIMES_amdgcn-amd-amdhsa-llvm_LLVM_ENABLE_RUNTIMES=libclc
+    -D LLVM_RUNTIME_TARGETS="default;amdgcn-amd-amdhsa-llvm"
+  )
+fi
+
 start-group "CMake"

 # Set the system llvm-symbolizer as preferred.
@@ -56,14 +64,14 @@ cmake -S "${MONOREPO_ROOT}"/llvm -B "${BUILD_DIR}" \
      -D CMAKE_CXX_COMPILER_LAUNCHER=sccache \
      -D CMAKE_DISABLE_PRECOMPILE_HEADERS=ON \
      -D LIBCXX_CXX_ABI=libcxxabi \
-      -D LIBCLC_TARGETS_TO_BUILD="amdgcn-amd-amdhsa-llvm" \
      -D MLIR_ENABLE_BINDINGS_PYTHON=ON \
      -D LLDB_ENABLE_PYTHON=ON \
      -D LLDB_ENFORCE_STRICT_TEST_REQUIREMENTS=ON \
      -D CMAKE_INSTALL_PREFIX="${INSTALL_DIR}" \
      -D CMAKE_EXE_LINKER_FLAGS="-no-pie" \
      -D LLVM_ENABLE_WERROR=ON \
-      -D LLVM_BINUTILS_INCDIR=/usr
+      -D LLVM_BINUTILS_INCDIR=/usr \
+      "${runtime_cmake_args[@]}"

 start-group "ninja"

--- a/.ci/monolithic-windows.sh
+++ b/.ci/monolithic-windows.sh
@@ -20,6 +20,14 @@ targets="${2}"
 runtimes="${3}"
 runtimes_targets="${4}"

+runtime_cmake_args=()
+if [[ " ${runtimes_targets} " == *" check-libclc-amdgcn-amd-amdhsa-llvm "* ]]; then
+  runtime_cmake_args+=(
+    -D RUNTIMES_amdgcn-amd-amdhsa-llvm_LLVM_ENABLE_RUNTIMES=libclc
+    -D LLVM_RUNTIME_TARGETS="default;amdgcn-amd-amdhsa-llvm"
+  )
+fi
+
 start-group "CMake"
 pip install -q -r "${MONOREPO_ROOT}"/.ci/all_requirements.txt

@@ -45,11 +53,11 @@ cmake -S "${MONOREPO_ROOT}"/llvm -B "${BUILD_DIR}" \
      -D CMAKE_CXX_COMPILER_LAUNCHER=sccache \
      -D CMAKE_DISABLE_PRECOMPILE_HEADERS=ON \
      -D MLIR_ENABLE_BINDINGS_PYTHON=ON \
-      -D LIBCLC_TARGETS_TO_BUILD="amdgcn-amd-amdhsa-llvm" \
      -D CMAKE_EXE_LINKER_FLAGS="/MANIFEST:NO" \
      -D CMAKE_MODULE_LINKER_FLAGS="/MANIFEST:NO" \
      -D CMAKE_SHARED_LINKER_FLAGS="/MANIFEST:NO" \
-      -D LLVM_ENABLE_RUNTIMES="${runtimes}"
+      -D LLVM_ENABLE_RUNTIMES="${runtimes}" \
+      "${runtime_cmake_args[@]}"

 start-group "ninja"

--- a/libclc/CMakeLists.txt
+++ b/libclc/CMakeLists.txt
@@ -18,14 +18,6 @@ include( GNUInstallDirs )

 set( LIBCLC_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR} )

-# A runtimes cross-build should only use the requested target.
-set( LIBCLC_DEFAULT_TARGET "all" )
-if( LLVM_RUNTIMES_BUILD AND LLVM_DEFAULT_TARGET_TRIPLE MATCHES "^nvptx|^amdgcn" )
-  set( LIBCLC_DEFAULT_TARGET ${LLVM_DEFAULT_TARGET_TRIPLE} )
-endif()
-set( LIBCLC_TARGETS_TO_BUILD ${LIBCLC_DEFAULT_TARGET}
-    CACHE STRING "Semicolon-separated list of libclc targets to build, or 'all'." )
-
 option(
  LIBCLC_USE_SPIRV_BACKEND "Build SPIR-V targets with the SPIR-V backend." OFF
 )
@@ -38,8 +30,20 @@ set( LIBCLC_TARGETS_ALL
  nvptx64--
  nvptx64--nvidiacl
  nvptx64-nvidia-cuda
+  spirv-mesa3d-
+  spirv64-mesa3d-
 )

+set(LIBCLC_TARGET ${LLVM_RUNTIMES_TARGET})
+
+if(NOT LIBCLC_TARGET)
+  message(FATAL_ERROR "libclc target is empty\n")
+endif()
+if(NOT "${LIBCLC_TARGET}" IN_LIST LIBCLC_TARGETS_ALL)
+  message(FATAL_ERROR "Unknown libclc target: ${LIBCLC_TARGET}\n"
+    "Valid targets are: ${LIBCLC_TARGETS_ALL}\n")
+endif()
+
 if( LIBCLC_STANDALONE_BUILD OR CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR )
  set( LIBCLC_STANDALONE_BUILD TRUE )

@@ -97,23 +101,17 @@ if( NOT LIBCLC_USE_SPIRV_BACKEND )
  endif()
 endif()

-if( LIBCLC_USE_SPIRV_BACKEND OR llvm-spirv_exe )
-  list( APPEND LIBCLC_TARGETS_ALL spirv-mesa3d- spirv64-mesa3d- )
-endif()
+message(STATUS "libclc target '${LIBCLC_TARGET}' is enabled")

-if( LIBCLC_TARGETS_TO_BUILD STREQUAL "all" )
-  set( LIBCLC_TARGETS_TO_BUILD ${LIBCLC_TARGETS_ALL} )
-else()
-  foreach(TARGET_TO_BUILD ${LIBCLC_TARGETS_TO_BUILD})
-    if (NOT ${TARGET_TO_BUILD} IN_LIST LIBCLC_TARGETS_ALL)
-      message( FATAL_ERROR
-        "Unknown target in LIBCLC_TARGETS_TO_BUILD: \"${TARGET_TO_BUILD}\"\n"
-        "Valid targets are: ${LIBCLC_TARGETS_ALL}\n")
-    endif()
-  endforeach()
-endif()
+string( REPLACE "-" ";" TRIPLE  ${LIBCLC_TARGET} )
+list(GET TRIPLE 0 ARCH)
+list(GET TRIPLE 2 OS)

-list( SORT LIBCLC_TARGETS_TO_BUILD )
+if(ARCH STREQUAL spirv OR ARCH STREQUAL spirv64)
+  if(NOT LIBCLC_USE_SPIRV_BACKEND AND NOT llvm-spirv_exe)
+    message(FATAL_ERROR "SPIR-V backend or llvm-spirv is required for libclc ${LIBCLC_TARGET}")
+  endif()
+endif()

 foreach( tool IN ITEMS opt llvm-link )
  if( NOT EXISTS "${${tool}_exe}" AND "${${tool}_target}" STREQUAL "" )
@@ -122,160 +120,156 @@ foreach( tool IN ITEMS opt llvm-link )
 endforeach()

 add_subdirectory(clc/lib/generic)
-add_subdirectory(clc/lib/amdgpu)
-add_subdirectory(clc/lib/ptx-nvidiacl)
-add_subdirectory(clc/lib/spirv)
-add_subdirectory(clc/lib/clspv)
-
 add_subdirectory(opencl/lib/generic)
-add_subdirectory(opencl/lib/amdgpu)
-add_subdirectory(opencl/lib/clspv)
-add_subdirectory(opencl/lib/spirv)
+
+if(ARCH STREQUAL amdgcn)
+  add_subdirectory(clc/lib/amdgpu)
+  add_subdirectory(opencl/lib/amdgpu)
+elseif(ARCH STREQUAL nvptx64)
+  add_subdirectory(clc/lib/ptx-nvidiacl)
+elseif(ARCH STREQUAL spirv OR ARCH STREQUAL spirv64)
+  add_subdirectory(clc/lib/spirv)
+  add_subdirectory(opencl/lib/spirv)
+elseif(ARCH STREQUAL clspv OR ARCH STREQUAL clspv64)
+  add_subdirectory(clc/lib/clspv)
+  add_subdirectory(opencl/lib/clspv)
+endif()

 add_custom_target( libclc ALL )

 add_custom_target( libclc-opencl-builtins COMMENT "Build libclc OpenCL builtins" )
 add_dependencies( libclc libclc-opencl-builtins )

-foreach( t ${LIBCLC_TARGETS_TO_BUILD} )
-  message( STATUS "libclc target '${t}' is enabled" )
-  string( REPLACE "-" ";" TRIPLE  ${t} )
-  list( GET TRIPLE 0 ARCH )
-  list( GET TRIPLE 1 VENDOR )
-  list( GET TRIPLE 2 OS )
+# Determine the clang target triple.
+set(clang_triple ${LIBCLC_TARGET})
+if(ARCH STREQUAL spirv AND LIBCLC_USE_SPIRV_BACKEND)
+  set(clang_triple spirv32--)
+elseif(ARCH STREQUAL spirv64 AND LIBCLC_USE_SPIRV_BACKEND)
+  set(clang_triple spirv64--)
+elseif(ARCH STREQUAL spirv OR ARCH STREQUAL clspv)
+  set(clang_triple spir--)
+elseif(ARCH STREQUAL spirv64 OR ARCH STREQUAL clspv64)
+  set(clang_triple spir64--)
+endif()

-  # Determine the clang target triple.
-  set(clang_triple ${t})
-  if(ARCH STREQUAL spirv AND LIBCLC_USE_SPIRV_BACKEND)
-    set(clang_triple spirv32--)
-  elseif(ARCH STREQUAL spirv64 AND LIBCLC_USE_SPIRV_BACKEND)
-    set(clang_triple spirv64--)
-  elseif(ARCH STREQUAL spirv OR ARCH STREQUAL clspv)
-    set(clang_triple spir--)
-  elseif(ARCH STREQUAL spirv64 OR ARCH STREQUAL clspv64)
-    set(clang_triple spir64--)
-  endif()
+# Determine the preprocessor identifier for this target.
+set(MACRO_ARCH ${ARCH})
+if(ARCH STREQUAL spirv)
+  set(MACRO_ARCH SPIRV32)
+elseif(ARCH STREQUAL spirv64)
+  set(MACRO_ARCH SPIRV64)
+elseif(ARCH STREQUAL clspv)
+  set(MACRO_ARCH CLSPV32)
+elseif(ARCH STREQUAL clspv64)
+  set(MACRO_ARCH CLSPV64)
+endif()
+string(TOUPPER "CLC_${MACRO_ARCH}" target_define)

-  # Determine the preprocessor identifier for this target.
-  set(MACRO_ARCH ${ARCH})
-  if(ARCH STREQUAL spirv)
-    set(MACRO_ARCH SPIRV32)
-  elseif(ARCH STREQUAL spirv64)
-    set(MACRO_ARCH SPIRV64)
-  elseif(ARCH STREQUAL clspv)
-    set(MACRO_ARCH CLSPV32)
-  elseif(ARCH STREQUAL clspv64)
-    set(MACRO_ARCH CLSPV64)
-  endif()
-  string(TOUPPER "CLC_${MACRO_ARCH}" target_define)
+# Address space values.
+set(private_addrspace_val 0)
+set(generic_addrspace_val 0)
+if(ARCH STREQUAL amdgcn)
+  set(private_addrspace_val 5)
+endif()
+if(ARCH STREQUAL spirv OR ARCH STREQUAL spirv64)
+  set(generic_addrspace_val 4)
+endif()

-  # Address space values.
-  set(private_addrspace_val 0)
-  set(generic_addrspace_val 0)
+# Target-specific compile flags and defines.
+set(target_compile_flags)
+set(target_extra_defines)
+set(opt_flags -O3)
+
+if(ARCH STREQUAL spirv OR ARCH STREQUAL spirv64)
+  list(APPEND target_compile_flags -O0 -finline-hint-functions)
+  list(APPEND target_extra_defines CLC_SPIRV)
+  set(opt_flags)
+elseif(ARCH STREQUAL clspv OR ARCH STREQUAL clspv64)
+  list(APPEND target_compile_flags -Wno-unknown-assumption -U__opencl_c_int64)
+  list(APPEND target_extra_defines CLC_CLSPV)
+elseif(ARCH STREQUAL amdgcn)
+  list(APPEND target_compile_flags "SHELL:-Xclang -mcode-object-version=none")
+endif()
+
+# Collect CLC sources; target-specific sources override generic ones by basename.
+set(_clc_overrides)
+if(ARCH STREQUAL amdgcn)
+  list(APPEND _clc_overrides ${CLC_AMDGPU_SOURCES})
+elseif(ARCH STREQUAL nvptx64 AND (OS STREQUAL nvidiacl OR OS STREQUAL cuda))
+  list(APPEND _clc_overrides ${CLC_PTX_NVIDIACL_SOURCES})
+elseif(ARCH STREQUAL spirv OR ARCH STREQUAL spirv64)
+  list(APPEND _clc_overrides ${CLC_SPIRV_SOURCES})
+elseif(ARCH STREQUAL clspv OR ARCH STREQUAL clspv64)
+  list(APPEND _clc_overrides ${CLC_CLSPV_SOURCES})
+endif()
+libclc_merge_sources(clc_sources ${CLC_GENERIC_SOURCES} ${_clc_overrides})
+
+# Collect OpenCL sources. SPIR-V and Clspv targets use self-contained
+# subsets while others merge with target-specific overrides.
+if(ARCH STREQUAL spirv OR ARCH STREQUAL spirv64)
+  set(opencl_sources ${OPENCL_SPIRV_SOURCES})
+elseif(ARCH STREQUAL clspv OR ARCH STREQUAL clspv64)
+  set(opencl_sources ${OPENCL_CLSPV_SOURCES})
+else()
+  set(_opencl_overrides)
  if(ARCH STREQUAL amdgcn)
-    set(private_addrspace_val 5)
-  endif()
-  if(ARCH STREQUAL spirv OR ARCH STREQUAL spirv64)
-    set(generic_addrspace_val 4)
+    list(APPEND _opencl_overrides ${OPENCL_AMDGCN_SOURCES})
  endif()
+  libclc_merge_sources(opencl_sources
+    ${OPENCL_GENERIC_SOURCES} ${_opencl_overrides})
+endif()

-  # Target-specific compile flags and defines.
-  set(target_compile_flags)
-  set(target_extra_defines)
-  set(opt_flags -O3)
+# Common compile options shared by CLC and OpenCL libraries.
+set(compile_flags
+  -flto
+  --target=${clang_triple}
+  -nostdlib
+  -nostdlibinc
+  -cl-no-stdinc
+  -cl-std=CL3.0
+  -include opencl-c-base.h
+  -Werror=undef
+  -Wall
+  -Wextra
+  -fdiscard-value-names
+  -ffp-contract=fast-honor-pragmas
+  -fdenormal-fp-math=dynamic
+  ${target_compile_flags}
+)

-  if(ARCH STREQUAL spirv OR ARCH STREQUAL spirv64)
-    list(APPEND target_compile_flags -O0 -finline-hint-functions)
-    list(APPEND target_extra_defines CLC_SPIRV)
-    set(opt_flags)
-  elseif(ARCH STREQUAL clspv OR ARCH STREQUAL clspv64)
-    list(APPEND target_compile_flags -Wno-unknown-assumption
-                                     -U__opencl_c_int64)
-    list(APPEND target_extra_defines CLC_CLSPV)
-  elseif(ARCH STREQUAL amdgcn)
-    list(APPEND target_compile_flags "SHELL:-Xclang -mcode-object-version=none")
-  endif()
+set(_common_defs
+  ${target_define}
+  ${target_extra_defines}
+  __CLC_PRIVATE_ADDRSPACE_VAL=${private_addrspace_val}
+  __CLC_GENERIC_ADDRSPACE_VAL=${generic_addrspace_val}
+)

-  # Collect CLC sources; target-specific sources override generic ones by basename.
-  set(_clc_overrides)
-  if(ARCH STREQUAL amdgcn)
-    list(APPEND _clc_overrides ${CLC_AMDGPU_SOURCES})
-  elseif(ARCH STREQUAL nvptx64 AND (OS STREQUAL nvidiacl OR OS STREQUAL cuda))
-    list(APPEND _clc_overrides ${CLC_PTX_NVIDIACL_SOURCES})
-  elseif(ARCH STREQUAL spirv OR ARCH STREQUAL spirv64)
-    list(APPEND _clc_overrides ${CLC_SPIRV_SOURCES})
-  elseif(ARCH STREQUAL clspv OR ARCH STREQUAL clspv64)
-    list(APPEND _clc_overrides ${CLC_CLSPV_SOURCES})
-  endif()
-  libclc_merge_sources(clc_sources ${CLC_GENERIC_SOURCES} ${_clc_overrides})
+# Build the CLC internal builtins library.
+string(REPLACE "-" "_" lib_suffix ${LIBCLC_TARGET})
+set(clc_lib clc_builtins_${lib_suffix})
+add_libclc_builtin_library(${clc_lib}
+  SOURCES ${clc_sources}
+  COMPILE_OPTIONS ${compile_flags}
+  INCLUDE_DIRS ${CMAKE_CURRENT_SOURCE_DIR}/clc/include
+  COMPILE_DEFINITIONS ${_common_defs}
+  FOLDER "libclc/Device IR/CLC"
+)

-  # Collect OpenCL sources. SPIR-V and Clspv targets use self-contained
-  # subsets while others merge with target-specific overrides.
-  if(ARCH STREQUAL spirv OR ARCH STREQUAL spirv64)
-    set(opencl_sources ${OPENCL_SPIRV_SOURCES})
-  elseif(ARCH STREQUAL clspv OR ARCH STREQUAL clspv64)
-    set(opencl_sources ${OPENCL_CLSPV_SOURCES})
-  else()
-    set(_opencl_overrides)
-    if(ARCH STREQUAL amdgcn)
-      list(APPEND _opencl_overrides ${OPENCL_AMDGCN_SOURCES})
-    endif()
-    libclc_merge_sources(opencl_sources
-      ${OPENCL_GENERIC_SOURCES} ${_opencl_overrides})
-  endif()
-
-  # Common compile options shared by CLC and OpenCL libraries.
-  set(compile_flags
-    -flto
-    --target=${clang_triple}
-    -nostdlib
-    -nostdlibinc
-    -cl-no-stdinc
-    -cl-std=CL3.0
-    -include opencl-c-base.h
-    -Werror=undef
-    -Wall
-    -Wextra
-    -fdiscard-value-names
-    -ffp-contract=fast-honor-pragmas
-    -fdenormal-fp-math=dynamic
-    ${target_compile_flags}
-  )
-
-  set(_common_defs
-    ${target_define}
-    ${target_extra_defines}
-    __CLC_PRIVATE_ADDRSPACE_VAL=${private_addrspace_val}
-    __CLC_GENERIC_ADDRSPACE_VAL=${generic_addrspace_val}
-  )
-
-  # Build the CLC internal builtins library.
-  string(REPLACE "-" "_" lib_suffix ${t})
-  set(clc_lib clc_builtins_${lib_suffix})
-  add_libclc_builtin_library(${clc_lib}
-    SOURCES ${clc_sources}
-    COMPILE_OPTIONS ${compile_flags}
-    INCLUDE_DIRS ${CMAKE_CURRENT_SOURCE_DIR}/clc/include
-    COMPILE_DEFINITIONS ${_common_defs}
-    FOLDER "libclc/Device IR/CLC"
-  )
-
-  # Build, link, and install the final OpenCL builtins library.
-  add_libclc_library(libclc-${t}
-    ARCH ${ARCH}
-    TRIPLE ${clang_triple}
-    TARGET_TRIPLE ${t}
-    SOURCES ${opencl_sources}
-    COMPILE_OPTIONS ${compile_flags} "SHELL:-Xclang -fdeclare-opencl-builtins"
-    INCLUDE_DIRS
-      ${CMAKE_CURRENT_SOURCE_DIR}/clc/include
-      ${CMAKE_CURRENT_SOURCE_DIR}/opencl/include
-    COMPILE_DEFINITIONS ${_common_defs}
-    INTERNALIZE_LIBRARIES ${clc_lib}
-    OPT_FLAGS ${opt_flags}
-    OUTPUT_FILENAME libclc
-    PARENT_TARGET libclc-opencl-builtins
-  )
-endforeach()
+# Build, link, and install the final OpenCL builtins library.
+add_libclc_library(libclc-${LIBCLC_TARGET}
+  ARCH ${ARCH}
+  TRIPLE ${clang_triple}
+  TARGET_TRIPLE ${LIBCLC_TARGET}
+  SOURCES ${opencl_sources}
+  COMPILE_OPTIONS ${compile_flags} "SHELL:-Xclang -fdeclare-opencl-builtins"
+  INCLUDE_DIRS
+    ${CMAKE_CURRENT_SOURCE_DIR}/clc/include
+    ${CMAKE_CURRENT_SOURCE_DIR}/opencl/include
+  COMPILE_DEFINITIONS ${_common_defs}
+  INTERNALIZE_LIBRARIES ${clc_lib}
+  OPT_FLAGS ${opt_flags}
+  OUTPUT_FILENAME libclc
+  PARENT_TARGET libclc-opencl-builtins
+)

 add_subdirectory(test)
--- a/libclc/README.md
+++ b/libclc/README.md
@@ -25,36 +25,87 @@ functions.
 libclc currently supports PTX, AMDGPU, SPIRV and CLSPV targets, but support for
 more targets is welcome.

-## Compiling and installing
+## Configure, build, and install

-(in the following instructions you can use `make` or `ninja`)
+libclc is built as part of an LLVM runtimes build.

-For an in-tree build, Clang must also be built at the same time:
+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
 ```
-$ cmake <path-to>/llvm-project/llvm/CMakeLists.txt -DLLVM_ENABLE_PROJECTS="clang" \
-    -DLLVM_ENABLE_RUNTIMES="libclc" -DCMAKE_BUILD_TYPE=Release -G Ninja
-$ ninja
+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"
 ```
-Then install:
+
+#### Configure for the NVPTX64 target
 ```
-$ ninja install
+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
+DESTDIR=/path/for/staged/install ninja install
 ```
+
+## Run tests
+```
+ninja check-libclc-<target-triple>
+```
+or
+```
+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:
 ```
-$ cmake <path-to>/llvm-project/libclc/CMakeLists.txt -DCMAKE_BUILD_TYPE=Release \
-  -G Ninja -DLLVM_DIR=$(<path-to>/llvm-config --cmakedir)
+CC=$(<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 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
--- a/libclc/test/CMakeLists.txt
+++ b/libclc/test/CMakeLists.txt
@@ -7,19 +7,12 @@ set(LIBCLC_TEST_DEPS
 umbrella_lit_testsuite_begin(check-libclc)

 # Testing unresolved symbols.
-foreach(t ${LIBCLC_TARGETS_TO_BUILD})
-  string(REPLACE "-" ";" TRIPLE ${t})
-  list(GET TRIPLE 0 ARCH)
-
-  # Skip nvptx, clspv, spirv targets
-  if(ARCH MATCHES "^(nvptx|clspv)(64)?$" OR ARCH MATCHES "^spirv(64)?$")
-    continue()
-  endif()
-
+# Skip nvptx, clspv, spirv targets
+if(ARCH MATCHES amdgcn)
  # Get the output file from the target property
-  set(target_file "$<TARGET_PROPERTY:libclc-${t},TARGET_FILE>")
+  set(target_file "$<TARGET_PROPERTY:libclc-${LIBCLC_TARGET},TARGET_FILE>")

-  set(LIBCLC_TARGET_TEST_DIR ${CMAKE_CURRENT_BINARY_DIR}/${t})
+  set(LIBCLC_TARGET_TEST_DIR ${CMAKE_CURRENT_BINARY_DIR}/${LIBCLC_TARGET})
  file(MAKE_DIRECTORY ${LIBCLC_TARGET_TEST_DIR})
  file(GENERATE OUTPUT ${LIBCLC_TARGET_TEST_DIR}/check-external-funcs.test
    CONTENT "; RUN: llvm-nm -u \"${target_file}\" | FileCheck %s --allow-empty\n\n; CHECK-NOT: {{.+}}\n"
@@ -32,11 +25,11 @@ foreach(t ${LIBCLC_TARGETS_TO_BUILD})
      ${CMAKE_CURRENT_SOURCE_DIR}/lit.cfg.py
  )

-  add_lit_testsuite(check-libclc-external-funcs-${t} "Running ${t} tests"
+  add_lit_testsuite(check-libclc-external-funcs-${LIBCLC_TARGET} "Running ${LIBCLC_TARGET} tests"
    ${LIBCLC_TARGET_TEST_DIR}
    DEPENDS ${LIBCLC_TEST_DEPS}
  )
-  set_target_properties(check-libclc-external-funcs-${t} PROPERTIES FOLDER "libclc tests")
-endforeach()
+  set_target_properties(check-libclc-external-funcs-${LIBCLC_TARGET} PROPERTIES FOLDER "libclc tests")
+endif()

 umbrella_lit_testsuite_end(check-libclc)
--- a/llvm/runtimes/CMakeLists.txt
+++ b/llvm/runtimes/CMakeLists.txt
@@ -552,8 +552,18 @@ if(build_runtimes)
    list(APPEND extra_cmake_args "-DCMAKE_PROGRAM_PATH=${CMAKE_PROGRAM_PATH}")
  endif()

-  # TODO: We need to consider passing it as '-DRUNTIMES_x86_64_LLVM_ENABLE_RUNTIMES'.
+  set(libclc_enabled FALSE)
  if("libclc" IN_LIST LLVM_ENABLE_RUNTIMES)
+    set(libclc_enabled TRUE)
+  else()
+    foreach(target ${LLVM_RUNTIME_TARGETS})
+      if("libclc" IN_LIST RUNTIMES_${target}_LLVM_ENABLE_RUNTIMES)
+        set(libclc_enabled TRUE)
+        break()
+      endif()
+    endforeach()
+  endif()
+  if(libclc_enabled)
    foreach(dep clang llvm-link opt llvm-ar llvm-ranlib llvm-spirv)
      if(TARGET ${dep})
        list(APPEND extra_deps ${dep})