llvm · frasercrmck · Jun 30, 2025 · Jul 1, 2025 · Jul 1, 2025 · Jul 1, 2025
diff --git a/clang/include/clang/Basic/DiagnosticDriverKinds.td b/clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -392,6 +392,9 @@ def warn_drv_fraw_string_literals_in_cxx11 : Warning<
   "ignoring '-f%select{no-|}0raw-string-literals', which is only valid for C and C++ standards before C++11">,
   InGroup<UnusedCommandLineArgument>;
 
+def err_drv_libclc_not_found : Error<
+  "no libclc library '%0' found in the clang resource directory or in LIBRARY_PATH">;
+
 def err_drv_invalid_malign_branch_EQ : Error<
   "invalid argument '%0' to -malign-branch=; each element must be one of: %1">;
 

diff --git a/clang/include/clang/Driver/CommonArgs.h b/clang/include/clang/Driver/CommonArgs.h
@@ -215,6 +215,9 @@ void addOpenMPDeviceRTL(const Driver &D, const llvm::opt::ArgList &DriverArgs,
                         StringRef BitcodeSuffix, const llvm::Triple &Triple,
                         const ToolChain &HostTC);
 
+void addOpenCLBuiltinsLib(const Driver &D, const llvm::opt::ArgList &DriverArgs,
+                          llvm::opt::ArgStringList &CC1Args);
+
 void addOutlineAtomicsArgs(const Driver &D, const ToolChain &TC,
                            const llvm::opt::ArgList &Args,
                            llvm::opt::ArgStringList &CmdArgs,

diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
@@ -1421,6 +1421,8 @@ def openacc_macro_override_EQ
 
 // End Clang specific/exclusive options for OpenACC.
 
+def libclc_lib_EQ : Joined<["--"], "libclc-lib=">, Group<opencl_Group>,
+  HelpText<"Namespec of libclc OpenCL bitcode library to link">;
 def libomptarget_amdgpu_bc_path_EQ : Joined<["--"], "libomptarget-amdgpu-bc-path=">, Group<i_Group>,
   HelpText<"Path to libomptarget-amdgcn bitcode library">;
 def libomptarget_amdgcn_bc_path_EQ : Joined<["--"], "libomptarget-amdgcn-bc-path=">, Group<i_Group>,

diff --git a/clang/lib/Driver/ToolChains/AMDGPU.cpp b/clang/lib/Driver/ToolChains/AMDGPU.cpp
@@ -795,6 +795,8 @@ void AMDGPUToolChain::addClangTargetOptions(
     CC1Args.push_back("-fvisibility=hidden");
     CC1Args.push_back("-fapply-global-visibility-to-externs");
   }
+
+  addOpenCLBuiltinsLib(getDriver(), DriverArgs, CC1Args);
 }
 
 void AMDGPUToolChain::addClangWarningOptions(ArgStringList &CC1Args) const {

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -2942,6 +2942,65 @@ void tools::addHIPRuntimeLibArgs(const ToolChain &TC, Compilation &C,
   }
 }
 
+void tools::addOpenCLBuiltinsLib(const Driver &D,
+                                 const llvm::opt::ArgList &DriverArgs,
+                                 llvm::opt::ArgStringList &CC1Args) {
+  // Check whether user specifies a libclc bytecode library
+  if (const Arg *A = DriverArgs.getLastArg(options::OPT_libclc_lib_EQ)) {
+    SmallVector<StringRef, 8> LibraryPaths;
+
+    // Add user defined library paths from LIBRARY_PATH.
+    std::optional<std::string> LibPath =
+        llvm::sys::Process::GetEnv("LIBRARY_PATH");
+    if (LibPath) {
+      SmallVector<StringRef, 8> Frags;
+      const char EnvPathSeparatorStr[] = {llvm::sys::EnvPathSeparator, '\0'};
+      llvm::SplitString(*LibPath, Frags, EnvPathSeparatorStr);
+      for (StringRef Path : Frags)
+        LibraryPaths.emplace_back(Path.trim());
+    }
+
+    // Find device libraries in <LLVM_DIR>/lib/clang/<ver>/lib/libclc/
+    SmallString<128> LibclcPath(D.ResourceDir);
+    llvm::sys::path::append(LibclcPath, "lib", "libclc");
+    LibraryPaths.emplace_back(LibclcPath);
+
+    bool FoundBCLibrary = false;
+    StringRef LibclcNamespec(A->getValue());
+
+    // If the namespec is of the form :filename, search for that file.
+    bool FilenameSearch = LibclcNamespec.starts_with(":");
+    SmallString<128> LibclcTargetFile(
+        LibclcNamespec.drop_front(FilenameSearch ? 1 : 0));
+
+    if (FilenameSearch && llvm::sys::fs::exists(LibclcTargetFile)) {
+      FoundBCLibrary = true;
+      CC1Args.push_back("-mlink-builtin-bitcode");
+      CC1Args.push_back(DriverArgs.MakeArgString(LibclcTargetFile));
+    } else {
+      // Search the library paths for the file
+      if (!FilenameSearch)
+        LibclcTargetFile += ".bc";
+
+      for (StringRef LibraryPath : LibraryPaths) {
+        SmallString<128> LibclcPath(LibraryPath);
+        llvm::sys::path::append(LibclcPath, LibclcTargetFile);
+        if (llvm::sys::fs::exists(LibclcPath)) {
+          FoundBCLibrary = true;
+          CC1Args.push_back("-mlink-builtin-bitcode");
+          CC1Args.push_back(DriverArgs.MakeArgString(LibclcPath));
+          break;
+        }
+      }
+    }
+
+    // Since the user requested a library, if we haven't one then report an
+    // error.
+    if (!FoundBCLibrary)
+      D.Diag(diag::err_drv_libclc_not_found) << LibclcTargetFile;
+  }
+}
+
 void tools::addOutlineAtomicsArgs(const Driver &D, const ToolChain &TC,
                                   const llvm::opt::ArgList &Args,
                                   llvm::opt::ArgStringList &CmdArgs,

diff --git a/clang/test/Driver/Inputs/libclc/libclc.bc b/clang/test/Driver/Inputs/libclc/libclc.bc
diff --git a/clang/test/Driver/Inputs/libclc/subdir/libclc.bc b/clang/test/Driver/Inputs/libclc/subdir/libclc.bc
diff --git a/clang/test/Driver/opencl-libclc.cl b/clang/test/Driver/opencl-libclc.cl
@@ -0,0 +1,10 @@
+// RUN: %clang -### -target amdgcn-amd-amdhsa --no-offloadlib --libclc-lib=:%S/Inputs/libclc/libclc.bc %s 2>&1 | FileCheck %s
+// RUN: env LIBRARY_PATH=%S/Inputs/libclc %clang -### -target amdgcn-amd-amdhsa --no-offloadlib --libclc-lib=libclc %s 2>&1 | FileCheck %s
+// RUN: env LIBRARY_PATH=%S/Inputs/libclc %clang -### -target amdgcn-amd-amdhsa --no-offloadlib --libclc-lib=:libclc.bc %s 2>&1 | FileCheck %s
+
+// RUN: env LIBRARY_PATH=%S/Inputs/libclc/subdir %clang -### -target amdgcn-amd-amdhsa --no-offloadlib --libclc-lib=libclc %s 2>&1 | FileCheck %s --check-prefix CHECK-SUBDIR
+// RUN: env LIBRARY_PATH=%S/Inputs/libclc/subdir %clang -### -target amdgcn-amd-amdhsa --no-offloadlib --libclc-lib=:libclc.bc %s 2>&1 | FileCheck %s --check-prefix CHECK-SUBDIR
+// RUN: env LIBRARY_PATH=%S/Inputs/libclc %clang -### -target amdgcn-amd-amdhsa --no-offloadlib --libclc-lib=:subdir/libclc.bc %s 2>&1 | FileCheck %s --check-prefix CHECK-SUBDIR
+
+// CHECK: -mlink-builtin-bitcode{{.*}}Inputs{{/|\\\\}}libclc{{/|\\\\}}libclc.bc
+// CHECK-SUBDIR: -mlink-builtin-bitcode{{.*}}Inputs{{/|\\\\}}libclc{{/|\\\\}}subdir{{/|\\\\}}libclc.bc
diff --git a/libclc/CMakeLists.txt b/libclc/CMakeLists.txt
@@ -63,6 +63,10 @@ if( LIBCLC_STANDALONE_BUILD OR CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DI
       set( ${tool}_target )
     endforeach()
   endif()
+
+  # Setup the paths where libclc runtimes should be stored.
+  set( LIBCLC_OUTPUT_DIR ${CMAKE_CURRENT_BINARY_DIR} )
+  set( LIBCLC_OUTPUT_LIBRARY_DIR ${LIBCLC_OUTPUT_DIR} )
 else()
   # In-tree configuration
   set( LIBCLC_STANDALONE_BUILD FALSE )
@@ -82,6 +86,13 @@ else()
     get_host_tool_path( llvm-link LLVM_LINK llvm-link_exe llvm-link_target )
     get_host_tool_path( opt OPT opt_exe opt_target )
   endif()
+
+  # Setup the paths where libclc runtimes should be stored. By default, in an
+  # in-tree build we place the libraries in clang's resource driectory.
+  get_clang_resource_dir( LIBCLC_OUTPUT_DIR PREFIX ${LLVM_LIBRARY_OUTPUT_INTDIR}/.. )
+
+  # Note we do not adhere to LLVM_ENABLE_PER_TARGET_RUNTIME_DIR.
+  set( LIBCLC_OUTPUT_LIBRARY_DIR ${LIBCLC_OUTPUT_DIR}/lib/libclc )
 endif()
 
 if( EXISTS ${LIBCLC_CUSTOM_LLVM_TOOLS_BINARY_DIR} )

diff --git a/libclc/cmake/modules/AddLibclc.cmake b/libclc/cmake/modules/AddLibclc.cmake
@@ -120,14 +120,14 @@ function(link_bc)
   endif()
 
   add_custom_command(
-    OUTPUT ${ARG_TARGET}.bc
-    COMMAND ${llvm-link_exe} ${link_flags} -o ${ARG_TARGET}.bc ${LINK_INPUT_ARG}
+    OUTPUT ${LIBCLC_ARCH_OBJFILE_DIR}/${ARG_TARGET}.bc
+    COMMAND ${llvm-link_exe} ${link_flags} -o ${LIBCLC_ARCH_OBJFILE_DIR}/${ARG_TARGET}.bc ${LINK_INPUT_ARG}
     DEPENDS ${llvm-link_target} ${ARG_DEPENDENCIES} ${ARG_INPUTS} ${RSP_FILE}
   )
 
-  add_custom_target( ${ARG_TARGET} ALL DEPENDS ${ARG_TARGET}.bc )
+  add_custom_target( ${ARG_TARGET} ALL DEPENDS ${LIBCLC_ARCH_OBJFILE_DIR}/${ARG_TARGET}.bc )
   set_target_properties( ${ARG_TARGET} PROPERTIES
-    TARGET_FILE ${CMAKE_CURRENT_BINARY_DIR}/${ARG_TARGET}.bc
+    TARGET_FILE ${LIBCLC_ARCH_OBJFILE_DIR}/${ARG_TARGET}.bc
     FOLDER "libclc/Device IR/Linking"
   )
 endfunction()
@@ -358,58 +358,65 @@ function(add_libclc_builtin_set)
 
   if( ARG_ARCH STREQUAL spirv OR ARG_ARCH STREQUAL spirv64 )
     set( spv_suffix ${ARG_ARCH_SUFFIX}.spv )
-    add_custom_command( OUTPUT ${spv_suffix}
-      COMMAND ${llvm-spirv_exe} ${spvflags} -o ${spv_suffix} ${builtins_link_lib}
+    add_custom_command( OUTPUT ${LIBCLC_OUTPUT_LIBRARY_DIR}/${spv_suffix}
+      COMMAND ${llvm-spirv_exe} ${spvflags} -o ${LIBCLC_OUTPUT_LIBRARY_DIR}/${spv_suffix} ${builtins_link_lib}
       DEPENDS ${llvm-spirv_target} ${builtins_link_lib} ${builtins_link_lib_tgt}
     )
-    add_custom_target( "prepare-${spv_suffix}" ALL DEPENDS "${spv_suffix}" )
+    add_custom_target( "prepare-${spv_suffix}" ALL DEPENDS "${LIBCLC_OUTPUT_LIBRARY_DIR}/${spv_suffix}" )
     set_target_properties( "prepare-${spv_suffix}" PROPERTIES FOLDER "libclc/Device IR/Prepare" )
-    install( FILES ${CMAKE_CURRENT_BINARY_DIR}/${spv_suffix}
-       DESTINATION "${CMAKE_INSTALL_DATADIR}/clc" )
+    install( FILES ${LIBCLC_OUTPUT_LIBRARY_DIR}/${spv_suffix}
+       DESTINATION "${CMAKE_INSTALL_DATADIR}/clc"
+     )
 
     return()
   endif()
 
   set( builtins_opt_lib_tgt builtins.opt.${ARG_ARCH_SUFFIX} )
 
   # Add opt target
-  add_custom_command( OUTPUT ${builtins_opt_lib_tgt}.bc
-    COMMAND ${opt_exe} ${ARG_OPT_FLAGS} -o ${builtins_opt_lib_tgt}.bc
+  add_custom_command( OUTPUT ${LIBCLC_ARCH_OBJFILE_DIR}/${builtins_opt_lib_tgt}.bc
+    COMMAND ${opt_exe} ${ARG_OPT_FLAGS} -o ${LIBCLC_ARCH_OBJFILE_DIR}/${builtins_opt_lib_tgt}.bc
       ${builtins_link_lib}
     DEPENDS ${opt_target} ${builtins_link_lib} ${builtins_link_lib_tgt}
   )
   add_custom_target( ${builtins_opt_lib_tgt}
-    ALL DEPENDS ${builtins_opt_lib_tgt}.bc
+    ALL DEPENDS ${LIBCLC_ARCH_OBJFILE_DIR}/${builtins_opt_lib_tgt}.bc
   )
   set_target_properties( ${builtins_opt_lib_tgt} PROPERTIES
-    TARGET_FILE ${CMAKE_CURRENT_BINARY_DIR}/${builtins_opt_lib_tgt}.bc
+    TARGET_FILE ${LIBCLC_ARCH_OBJFILE_DIR}/${builtins_opt_lib_tgt}.bc
     FOLDER "libclc/Device IR/Opt"
   )
 
   set( builtins_opt_lib $<TARGET_PROPERTY:${builtins_opt_lib_tgt},TARGET_FILE> )
 
   # Add prepare target
   set( obj_suffix ${ARG_ARCH_SUFFIX}.bc )
-  add_custom_command( OUTPUT ${obj_suffix}
-    COMMAND ${prepare_builtins_exe} -o ${obj_suffix} ${builtins_opt_lib}
-    DEPENDS ${builtins_opt_lib} ${builtins_opt_lib_tgt} ${prepare_builtins_target} )
-  add_custom_target( prepare-${obj_suffix} ALL DEPENDS ${obj_suffix} )
-  set_target_properties( "prepare-${obj_suffix}" PROPERTIES FOLDER "libclc/Device IR/Prepare" )
+  set( libclc_bc_lib ${LIBCLC_OUTPUT_LIBRARY_DIR}/${obj_suffix} )
+  add_custom_command( OUTPUT ${libclc_bc_lib}
+    COMMAND ${prepare_builtins_exe} -o ${libclc_bc_lib} ${builtins_opt_lib}
+    DEPENDS ${builtins_opt_lib} ${builtins_opt_lib_tgt} ${prepare_builtins_target}
+    WORKING_DIRECTORY ${LIBCLC_OUTPUT_LIBRARY_DIR}
+  )
+  add_custom_target( prepare-${obj_suffix} ALL DEPENDS ${libclc_bc_lib} )
+  set_target_properties( "prepare-${obj_suffix}" PROPERTIES
+    TARGET_FILE ${libclc_bc_lib}
+    FOLDER "libclc/Device IR/Prepare"
+  )
 
   # nvptx-- targets don't include workitem builtins, and clspv targets don't
   # include all OpenCL builtins
   if( NOT ARG_ARCH MATCHES "^(nvptx|clspv)(64)?$" )
     add_test( NAME external-calls-${obj_suffix}
-      COMMAND ./check_external_calls.sh ${CMAKE_CURRENT_BINARY_DIR}/${obj_suffix} ${LLVM_TOOLS_BINARY_DIR}
+      COMMAND ./check_external_calls.sh ${libclc_bc_lib} ${LLVM_TOOLS_BINARY_DIR}
       WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR} )
   endif()
 
-  install( FILES ${CMAKE_CURRENT_BINARY_DIR}/${obj_suffix} DESTINATION "${CMAKE_INSTALL_DATADIR}/clc" )
+  install( FILES ${libclc_bc_lib} DESTINATION "${CMAKE_INSTALL_DATADIR}/clc" )
   foreach( a ${ARG_ALIASES} )
     set( alias_suffix "${a}-${ARG_TRIPLE}.bc" )
     add_custom_command(
       OUTPUT ${alias_suffix}
-      COMMAND ${CMAKE_COMMAND} -E create_symlink ${obj_suffix} ${alias_suffix}
+      COMMAND ${CMAKE_COMMAND} -E create_symlink ${libclc_bc_lib} ${alias_suffix}
       DEPENDS prepare-${obj_suffix} )
     add_custom_target( alias-${alias_suffix} ALL DEPENDS ${alias_suffix} )
     set_target_properties( alias-${alias_suffix} PROPERTIES FOLDER "libclc/Device IR/Aliases" )