[Refactor]Move llvm runtime build for archs to cmake from C++. (#2524)

Co-authored-by: Ailing Zhang <[email protected]>

CMakeLists.txt

@@ -76,6 +76,31 @@ add_custom_target(
 )
 add_dependencies(${CORE_LIBRARY_NAME} generate_commit_hash)
 
+if (TI_WITH_CUDA)
+    set(CUDA_ARCH "cuda")
+endif()
+
+find_program(CLANG_EXECUTABLE NAMES clang-7 clang-8 clang-9 clang-10 clang)
+if (NOT CLANG_EXECUTABLE)
+    message(FATAL_ERROR "Cannot find any clang executable.")
+endif()
+
+find_program(LLVM_AS_EXECUTABLE NAMES llvm-as)
+if (NOT LLVM_AS_EXECUTABLE)
+    message(FATAL_ERROR "Cannot find llvm-as executable.")
+endif()
+
+# Build llvm-runtime for host arch and cuda (if available)
+foreach(arch IN LISTS HOST_ARCH CUDA_ARCH)
+  add_custom_target(
+      "generate_llvm_runtime_${arch}"
+      COMMAND ${CLANG_EXECUTABLE} -S runtime.cpp -o runtime.ll -fno-exceptions -emit-llvm -std=c++17 -D "ARCH_${arch}" -I ${PROJECT_SOURCE_DIR};
+      COMMAND ${LLVM_AS_EXECUTABLE} runtime.ll -o "runtime_${arch}.bc"
+      WORKING_DIRECTORY "${PROJECT_SOURCE_DIR}/taichi/runtime/llvm"
+  )
+  add_dependencies(${CORE_LIBRARY_NAME} "generate_llvm_runtime_${arch}")
+endforeach()
+
 FILE(WRITE ${CMAKE_CURRENT_LIST_DIR}/taichi/common/version.h
         "#pragma once\n"
         "#define TI_VERSION_MAJOR \"${TI_VERSION_MAJOR}\"\n"

cmake/TaichiCXXFlags.cmake

@@ -44,11 +44,14 @@ if ("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "x86_64" OR "${CMAKE_SYSTEM_PROCESSOR}"
         message("Setting -march=nehalem for x86_64 processors")
         set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -march=nehalem -DTI_ARCH_x64")
     endif()
+    set(ARCH "x64")
 elseif ("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "aarch64" OR "${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "arm64")
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DTI_ARCH_ARM")
+    set(ARCH "arm64")
 else()
     message(FATAL_ERROR "Unknown processor type ${CMAKE_SYSTEM_PROCESSOR}")
 endif()
+set(HOST_ARCH ${ARCH} CACHE INTERNAL "Host arch")
 
 if (USE_STDCPP)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -stdlib=libc++")

python/build.py

@@ -88,7 +88,6 @@ def build(project_name):
         assert os.path.exists(libdevice_path)
         shutil.copy(libdevice_path, 'taichi/lib/slim_libdevice.10.bc')
 
-    ti.core.compile_runtimes()
     runtime_dir = ti.core.get_runtime_dir()
     for f in os.listdir(runtime_dir):
         if f.startswith('runtime_') and f.endswith('.bc'):

taichi/llvm/llvm_context.cpp

@@ -230,13 +230,6 @@ void compile_runtime_bitcode(Arch arch) {
   }
 }
 
-void compile_runtimes() {
-  compile_runtime_bitcode(host_arch());
-#if defined(TI_WITH_CUDA)
-  compile_runtime_bitcode(Arch::cuda);
-#endif
-}
-
 std::string libdevice_path() {
   std::string folder;
   if (is_release()) {

taichi/python/export_lang.cpp

@@ -55,7 +55,6 @@ void expr_assign(const Expr &lhs_, const Expr &rhs, std::string tb) {
 
 std::vector<std::unique_ptr<ASTBuilder::ScopeGuard>> scope_stack;
 
-void compile_runtimes();
 std::string libdevice_path();
 std::string get_runtime_dir();
 
@@ -743,7 +742,6 @@ void export_lang(py::module &m) {
   m.def("test_throw", [] { throw IRModified(); });
   m.def("needs_grad", needs_grad);
 
-  m.def("compile_runtimes", compile_runtimes);
   m.def("libdevice_path", libdevice_path);
 
   m.def("host_arch", host_arch);