LLVM Driver Multicall tool

This patch adds an llvm-driver multicall tool that can combine multiple
LLVM-based tools. The build infrastructure is enabled for a tool by
adding the GENERATE_DRIVER option to the add_llvm_executable CMake
call, and changing the tool's main function to a canonicalized
tool_name_main format (i.e. llvm_ar_main, clang_main, etc...).

As currently implemented llvm-driver contains dsymutil, llvm-ar,
llvm-cxxfilt, llvm-objcopy, and clang (if clang is included in the
build).

llvm-driver can be enabled from builds by setting
LLVM_TOOL_LLVM_DRIVER_BUILD=On.

There are several limitations in the current implementation, which can
be addressed in subsequent patches:

(1) the multicall binary cannot currently properly handle
multi-dispatch tools. This means symlinking llvm-ranlib to llvm-driver
will not properly result in llvm-ar's main being called.
(2) the multicall binary cannot be comprised of tools containing
conflicting cl::opt options as the global cl::opt option list cannot
contain duplicates.

These limitations can be addressed in subsequent patches.

Differential revision: https://reviews.llvm.org/D109977

Author: llvm-beanz

clang/cmake/modules/AddClang.cmake

@@ -184,5 +184,8 @@ function(clang_target_link_libraries target type)
   else()
     target_link_libraries(${target} ${type} ${ARGN})
   endif()
+  if (TARGET obj.${target})
+    target_link_libraries(obj.${target} ${ARGN})
+  endif()
 
 endfunction()

clang/tools/driver/CMakeLists.txt

@@ -31,6 +31,7 @@ add_clang_tool(clang
   DEPENDS
   intrinsics_gen
   ${support_plugins}
+  GENERATE_DRIVER
   )
 
 clang_target_link_libraries(clang

clang/tools/driver/driver.cpp

@@ -327,7 +327,7 @@ static int ExecuteCC1Tool(SmallVectorImpl<const char *> &ArgV) {
   return 1;
 }
 
-int main(int Argc, const char **Argv) {
+int clang_main(int Argc, char **Argv) {
   noteBottomOfStack();
   llvm::InitLLVM X(Argc, Argv);
   llvm::setBugReportMsg("PLEASE submit a bug report to " BUG_REPORT_URL

llvm/CMakeLists.txt

@@ -269,6 +269,8 @@ include(VersionFromVCS)
 option(LLVM_APPEND_VC_REV
   "Embed the version control system revision in LLVM" ON)
 
+option(LLVM_TOOL_LLVM_DRIVER_BUILD "Enables building the llvm multicall tool" OFF)
+
 set(PACKAGE_NAME LLVM)
 set(PACKAGE_STRING "${PACKAGE_NAME} ${PACKAGE_VERSION}")
 set(PACKAGE_BUGREPORT "https://github.com/llvm/llvm-project/issues/")

llvm/cmake/driver-template.cpp.in

@@ -0,0 +1,11 @@
+//===-- driver-template.cpp -----------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+int @TOOL_NAME@_main(int argc, char **argv);
+
+int main(int argc, char **argv) { return @TOOL_NAME@_main(argc, argv); }

llvm/cmake/modules/AddLLVM.cmake

@@ -859,7 +859,7 @@ endmacro(add_llvm_library name)
 
 macro(add_llvm_executable name)
   cmake_parse_arguments(ARG
-    "DISABLE_LLVM_LINK_LLVM_DYLIB;IGNORE_EXTERNALIZE_DEBUGINFO;NO_INSTALL_RPATH;SUPPORT_PLUGINS"
+    "DISABLE_LLVM_LINK_LLVM_DYLIB;IGNORE_EXTERNALIZE_DEBUGINFO;NO_INSTALL_RPATH;SUPPORT_PLUGINS;GENERATE_DRIVER"
     "ENTITLEMENTS;BUNDLE_PATH"
     "DEPENDS"
     ${ARGN})
@@ -869,7 +869,7 @@ macro(add_llvm_executable name)
   list(APPEND LLVM_COMMON_DEPENDS ${ARG_DEPENDS})
 
   # Generate objlib
-  if(LLVM_ENABLE_OBJLIB)
+  if(LLVM_ENABLE_OBJLIB OR ARG_GENERATE_DRIVER)
     # Generate an obj library for both targets.
     set(obj_name "obj.${name}")
     add_library(${obj_name} OBJECT EXCLUDE_FROM_ALL
@@ -884,6 +884,23 @@ macro(add_llvm_executable name)
     set_target_properties(${obj_name} PROPERTIES FOLDER "Object Libraries")
   endif()
 
+  if (ARG_GENERATE_DRIVER)
+    string(REPLACE "-" "_" TOOL_NAME ${name})
+    configure_file(
+      ${LLVM_MAIN_SRC_DIR}/cmake/driver-template.cpp.in
+      ${CMAKE_CURRENT_BINARY_DIR}/${name}-driver.cpp)
+
+    list(APPEND ALL_FILES ${CMAKE_CURRENT_BINARY_DIR}/${name}-driver.cpp)
+
+    set_property(GLOBAL APPEND PROPERTY LLVM_DRIVER_COMPONENTS ${LLVM_LINK_COMPONENTS})
+    set_property(GLOBAL APPEND PROPERTY LLVM_DRIVER_DEPS ${ARG_DEPENDS} ${LLVM_COMMON_DEPENDS})
+    set_property(GLOBAL APPEND PROPERTY LLVM_DRIVER_OBJLIBS "${obj_name}")
+    
+    set_property(GLOBAL APPEND PROPERTY LLVM_DRIVER_TOOLS ${name})
+    target_link_libraries(${obj_name} ${LLVM_PTHREAD_LIB})
+    llvm_config(${obj_name} ${USE_SHARED} ${LLVM_LINK_COMPONENTS} )
+  endif()
+
   add_windows_version_resource_file(ALL_FILES ${ALL_FILES})
 
   if(XCODE)
@@ -1449,6 +1466,12 @@ function(llvm_add_implicit_projects project)
   foreach(dir ${sub-dirs})
     if(IS_DIRECTORY "${dir}" AND EXISTS "${dir}/CMakeLists.txt")
       canonicalize_tool_name(${dir} name)
+      # I don't like special casing things by order, but the llvm-driver ends up
+      # linking the object libraries from all the tools that opt-in, so adding
+      # it separately at the end is probably the simplest case.
+      if("${name}" STREQUAL "LLVM_DRIVER")
+        continue()
+      endif()
       if (${project}_TOOL_${name}_BUILD)
         get_filename_component(fn "${dir}" NAME)
         list(APPEND list_of_implicit_subdirs "${fn}")
@@ -1998,6 +2021,16 @@ endfunction()
 
 function(add_llvm_tool_symlink link_name target)
   cmake_parse_arguments(ARG "ALWAYS_GENERATE" "OUTPUT_DIR" "" ${ARGN})
+
+  get_property(LLVM_DRIVER_TOOLS GLOBAL PROPERTY LLVM_DRIVER_TOOLS)
+
+  if (${target} IN_LIST LLVM_DRIVER_TOOLS)
+    string(REPLACE "-" "_" tool_entry ${target})
+    string(REPLACE "-" "_" key ${link_name})
+    string(REPLACE "llvm-" "" tool_name ${link_name})
+    set_property(GLOBAL APPEND_STRING PROPERTY
+                 LLVM_EXTRA_DRIVER_ENTRIES "LLVM_DRIVER_TOOL(\"${tool_name}\", ${tool_entry})\n")
+  endif()
   set(dest_binary "$<TARGET_FILE:${target}>")
 
   # This got a bit gross... For multi-configuration generators the target

llvm/lib/Support/Path.cpp

@@ -1202,9 +1202,18 @@ Error readNativeFileToEOF(file_t FileHandle, SmallVectorImpl<char> &Buffer,
 #include "Windows/Path.inc"
 #endif
 
+bool IsLLVMDriver = false;
+
 namespace llvm {
 namespace sys {
 namespace fs {
+
+std::string getMainExecutable(const char *Argv0, void *MainAddr) {
+  if (IsLLVMDriver)
+    return sys::path::stem(Argv0).str();
+  return getMainExecutableImpl(Argv0, MainAddr);
+}
+
 TempFile::TempFile(StringRef Name, int FD)
     : TmpName(std::string(Name)), FD(FD) {}
 TempFile::TempFile(TempFile &&Other) { *this = std::move(Other); }

llvm/lib/Support/Unix/Path.inc

@@ -194,7 +194,7 @@ getprogpath(char ret[PATH_MAX], const char *bin)
 
 /// GetMainExecutable - Return the path to the main executable, given the
 /// value of argv[0] from program startup.
-std::string getMainExecutable(const char *argv0, void *MainAddr) {
+std::string getMainExecutableImpl(const char *argv0, void *MainAddr) {
 #if defined(__APPLE__)
   // On OS X the executable path is saved to the stack by dyld. Reading it
   // from there is much faster than calling dladdr, especially for large

llvm/lib/Support/Windows/Path.inc

@@ -130,7 +130,7 @@ namespace fs {
 
 const file_t kInvalidFile = INVALID_HANDLE_VALUE;
 
-std::string getMainExecutable(const char *argv0, void *MainExecAddr) {
+std::string getMainExecutableImpl(const char *argv0, void *MainExecAddr) {
   SmallVector<wchar_t, MAX_PATH> PathName;
   PathName.resize_for_overwrite(PathName.capacity());
   DWORD Size = ::GetModuleFileNameW(NULL, PathName.data(), PathName.size());

llvm/test/CMakeLists.txt

@@ -21,6 +21,7 @@ llvm_canonicalize_cmake_booleans(
   LLVM_RAEVICT_MODEL_AUTOGENERATED
   LLVM_ENABLE_EXPENSIVE_CHECKS
   LLVM_INCLUDE_DXIL_TESTS
+  LLVM_TOOL_LLVM_DRIVER_BUILD
   )
 
 configure_lit_site_cfg(
@@ -144,6 +145,10 @@ if(TARGET llvm-lto)
   set(LLVM_TEST_DEPENDS ${LLVM_TEST_DEPENDS} llvm-lto)
 endif()
 
+if(TARGET llvm-driver)
+  set(LLVM_TEST_DEPENDS ${LLVM_TEST_DEPENDS} llvm-driver)
+endif()
+
 # If Intel JIT events are supported, depend on a tool that tests the listener.
 if( LLVM_USE_INTEL_JITEVENTS )
   set(LLVM_TEST_DEPENDS ${LLVM_TEST_DEPENDS} llvm-jitlistener)