[clang] Add the ability to link libclc OpenCL libraries

clang/include/clang/Basic/DiagnosticDriverKinds.td

@@ -392,6 +392,8 @@ 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">;
+
 def err_drv_invalid_malign_branch_EQ : Error<
   "invalid argument '%0' to -malign-branch=; each element must be one of: %1">;
 

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,

clang/include/clang/Driver/Options.td

@@ -1425,6 +1425,8 @@ 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>,

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 {

clang/lib/Driver/ToolChains/CommonArgs.cpp

@@ -2942,6 +2942,43 @@ 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
+  const Arg *A = DriverArgs.getLastArg(options::OPT_libclc_lib_EQ);
+  if (!A)
+    return;
+
+  // Find device libraries in <LLVM_DIR>/lib/clang/<ver>/lib/libclc/
+  SmallString<128> LibclcPath(D.ResourceDir);
+  llvm::sys::path::append(LibclcPath, "lib", "libclc");
+
+  // If the namespec is of the form :filename, search for that file.
+  StringRef LibclcNamespec(A->getValue());
+  bool FilenameSearch = LibclcNamespec.consume_front(":");
+  SmallString<128> LibclcTargetFile(LibclcNamespec);
+
+  if (FilenameSearch && llvm::sys::fs::exists(LibclcTargetFile)) {
+    CC1Args.push_back("-mlink-builtin-bitcode");
+    CC1Args.push_back(DriverArgs.MakeArgString(LibclcTargetFile));
+  } else {
+    // Search the library paths for the file
+    if (!FilenameSearch)
+      LibclcTargetFile += ".bc";
+
+    llvm::sys::path::append(LibclcPath, LibclcTargetFile);
+    if (llvm::sys::fs::exists(LibclcPath)) {
+      CC1Args.push_back("-mlink-builtin-bitcode");
+      CC1Args.push_back(DriverArgs.MakeArgString(LibclcPath));
+    } else {
+      // Since the user requested a library, if we haven't one then report an
+      // error.
+      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,

clang/test/Driver/opencl-libclc.cl

@@ -0,0 +1,9 @@
+// RUN: %clang -### -target amdgcn-amd-amdhsa --no-offloadlib --libclc-lib=:%S/Inputs/libclc/libclc.bc %s 2>&1 | FileCheck %s
+// RUN: %clang -### -target amdgcn-amd-amdhsa --no-offloadlib --libclc-lib=:%S/Inputs/libclc/subdir/libclc.bc %s 2>&1 | FileCheck %s --check-prefix CHECK-SUBDIR
+
+// RUN: not %clang -### -target amdgcn-amd-amdhsa --no-offloadlib --libclc-lib=:%S/Inputs/libclc/subdir/not-here.bc %s 2>&1 | FileCheck %s --check-prefix CHECK-ERROR
+
+// CHECK: -mlink-builtin-bitcode{{.*}}Inputs{{/|\\\\}}libclc{{/|\\\\}}libclc.bc
+// CHECK-SUBDIR: -mlink-builtin-bitcode{{.*}}Inputs{{/|\\\\}}libclc{{/|\\\\}}subdir{{/|\\\\}}libclc.bc
+
+// CHECK-ERROR: no libclc library{{.*}}not-here.bc' found in the clang resource directory

libclc/CMakeLists.txt

@@ -63,6 +63,9 @@ 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_LIBRARY_DIR ${CMAKE_CURRENT_BINARY_DIR} )
 else()
   # In-tree configuration
   set( LIBCLC_STANDALONE_BUILD FALSE )
@@ -82,10 +85,14 @@ 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()
-endif()
 
-# Setup the paths where libclc runtimes should be stored.
-set( LIBCLC_OUTPUT_LIBRARY_DIR ${CMAKE_CURRENT_BINARY_DIR} )
+  # 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} )
   message( WARNING "Using custom LLVM tools to build libclc: "