depot/third_party/nixpkgs/pkgs/development/compilers/llvm/8/crtbegin-and-end.patch

Get crtbegin and crtend without compiler GCC! PR is at https://reviews.llvm.org/D28791

Index: compiler-rt/CMakeLists.txt
===================================================================
--- compiler-rt/CMakeLists.txt
+++ compiler-rt/CMakeLists.txt
@@ -29,6 +29,8 @@
 
 option(COMPILER_RT_BUILD_BUILTINS "Build builtins" ON)
 mark_as_advanced(COMPILER_RT_BUILD_BUILTINS)
+option(COMPILER_RT_BUILD_CRT "Build crtbegin.o/crtend.o" ON)
+mark_as_advanced(COMPILER_RT_BUILD_CRT)
 option(COMPILER_RT_BUILD_SANITIZERS "Build sanitizers" ON)
 mark_as_advanced(COMPILER_RT_BUILD_SANITIZERS)
 option(COMPILER_RT_BUILD_XRAY "Build xray" ON)
Index: compiler-rt/cmake/Modules/AddCompilerRT.cmake
===================================================================
--- compiler-rt/cmake/Modules/AddCompilerRT.cmake
+++ compiler-rt/cmake/Modules/AddCompilerRT.cmake
@@ -132,7 +132,7 @@
 # Adds static or shared runtime for a list of architectures and operating
 # systems and puts it in the proper directory in the build and install trees.
 # add_compiler_rt_runtime(<name>
-#                         {STATIC|SHARED}
+#                         {OBJECT|STATIC|SHARED}
 #                         ARCHS <architectures>
 #                         OS <os list>
 #                         SOURCES <source files>
@@ -144,8 +144,8 @@
 #                         PARENT_TARGET <convenience parent target>
 #                         ADDITIONAL_HEADERS <header files>)
 function(add_compiler_rt_runtime name type)
-  if(NOT type MATCHES "^(STATIC|SHARED)$")
-    message(FATAL_ERROR "type argument must be STATIC or SHARED")
+  if(NOT type MATCHES "^(OBJECT|STATIC|SHARED)$")
+    message(FATAL_ERROR "type argument must be OBJECT, STATIC or SHARED")
     return()
   endif()
   cmake_parse_arguments(LIB
@@ -204,7 +204,10 @@
         message(FATAL_ERROR "Architecture ${arch} can't be targeted")
         return()
       endif()
-      if(type STREQUAL "STATIC")
+      if(type STREQUAL "OBJECT")
+        set(libname "${name}-${arch}")
+        set(output_name_${libname} ${libname}${COMPILER_RT_OS_SUFFIX})
+      elseif(type STREQUAL "STATIC")
         set(libname "${name}-${arch}")
         set_output_name(output_name_${libname} ${name} ${arch})
       else()
@@ -270,12 +273,34 @@
       set(COMPONENT_OPTION COMPONENT ${libname})
     endif()
 
-    add_library(${libname} ${type} ${sources_${libname}})
-    set_target_compile_flags(${libname} ${extra_cflags_${libname}})
-    set_target_link_flags(${libname} ${extra_link_flags_${libname}})
-    set_property(TARGET ${libname} APPEND PROPERTY
-                COMPILE_DEFINITIONS ${LIB_DEFS})
-    set_target_output_directories(${libname} ${output_dir_${libname}})
+    if(type STREQUAL "OBJECT")
+      string(TOUPPER ${CMAKE_BUILD_TYPE} config)
+      get_property(cflags SOURCE ${sources_${libname}} PROPERTY COMPILE_FLAGS)
+      separate_arguments(cflags)
+      add_custom_command(
+          OUTPUT ${output_dir_${libname}}/${libname}.o
+          COMMAND ${CMAKE_C_COMPILER} ${sources_${libname}} ${cflags} ${extra_cflags_${libname}} -c -o ${output_dir_${libname}}/${libname}.o
+          DEPENDS ${sources_${libname}}
+          COMMENT "Building C object ${libname}.o")
+      add_custom_target(${libname} DEPENDS ${output_dir_${libname}}/${libname}.o)
+      install(FILES ${output_dir_${libname}}/${libname}.o
+        DESTINATION ${install_dir_${libname}}
+        ${COMPONENT_OPTION})
+    else()
+      add_library(${libname} ${type} ${sources_${libname}})
+      set_target_compile_flags(${libname} ${extra_cflags_${libname}})
+      set_target_link_flags(${libname} ${extra_link_flags_${libname}})
+      set_property(TARGET ${libname} APPEND PROPERTY
+                   COMPILE_DEFINITIONS ${LIB_DEFS})
+      set_target_output_directories(${libname} ${output_dir_${libname}})
+      install(TARGETS ${libname}
+        ARCHIVE DESTINATION ${install_dir_${libname}}
+                ${COMPONENT_OPTION}
+        LIBRARY DESTINATION ${install_dir_${libname}}
+                ${COMPONENT_OPTION}
+        RUNTIME DESTINATION ${install_dir_${libname}}
+                ${COMPONENT_OPTION})
+    endif()
     set_target_properties(${libname} PROPERTIES
         OUTPUT_NAME ${output_name_${libname}})
     set_target_properties(${libname} PROPERTIES FOLDER "Compiler-RT Runtime")
@@ -299,13 +324,6 @@
         )
       endif()
     endif()
-    install(TARGETS ${libname}
-      ARCHIVE DESTINATION ${install_dir_${libname}}
-              ${COMPONENT_OPTION}
-      LIBRARY DESTINATION ${install_dir_${libname}}
-              ${COMPONENT_OPTION}
-      RUNTIME DESTINATION ${install_dir_${libname}}
-              ${COMPONENT_OPTION})
 
     # We only want to generate per-library install targets if you aren't using
     # an IDE because the extra targets get cluttered in IDEs.
Index: compiler-rt/cmake/config-ix.cmake
===================================================================
--- compiler-rt/cmake/config-ix.cmake
+++ compiler-rt/cmake/config-ix.cmake
@@ -227,6 +227,7 @@
     ${ARM32} ${ARM64} ${MIPS32} ${MIPS64} ${S390X})
 set(ALL_ASAN_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM32} ${ARM64}
     ${MIPS32} ${MIPS64} ${PPC64} ${S390X})
+set(ALL_CRT_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM32} ${ARM64})
 set(ALL_DFSAN_SUPPORTED_ARCH ${X86_64} ${MIPS64} ${ARM64})
 set(ALL_FUZZER_SUPPORTED_ARCH ${X86_64} ${ARM64})
 
@@ -474,6 +475,7 @@
     SANITIZER_COMMON_SUPPORTED_ARCH)
 
 else()
+  filter_available_targets(CRT_SUPPORTED_ARCH ${ALL_CRT_SUPPORTED_ARCH})
   # Architectures supported by compiler-rt libraries.
   filter_available_targets(SANITIZER_COMMON_SUPPORTED_ARCH
     ${ALL_SANITIZER_COMMON_SUPPORTED_ARCH})
@@ -563,6 +565,12 @@
 
 # TODO: Add builtins support.
 
+if (CRT_SUPPORTED_ARCH AND OS_NAME MATCHES "Linux")
+  set(COMPILER_RT_HAS_CRT TRUE)
+else()
+  set(COMPILER_RT_HAS_CRT FALSE)
+endif()
+
 if (COMPILER_RT_HAS_SANITIZER_COMMON AND DFSAN_SUPPORTED_ARCH AND
     OS_NAME MATCHES "Linux")
   set(COMPILER_RT_HAS_DFSAN TRUE)
Index: compiler-rt/lib/CMakeLists.txt
===================================================================
--- compiler-rt/lib/CMakeLists.txt
+++ compiler-rt/lib/CMakeLists.txt
@@ -17,6 +17,10 @@
   add_subdirectory(builtins)
 endif()
 
+if(COMPILER_RT_BUILD_CRT)
+  add_subdirectory(crt)
+endif()
+
 function(compiler_rt_build_runtime runtime)
   string(TOUPPER ${runtime} runtime_uppercase)
   if(COMPILER_RT_HAS_${runtime_uppercase})
Index: compiler-rt/lib/crt/CMakeLists.txt
===================================================================
--- /dev/null
+++ compiler-rt/lib/crt/CMakeLists.txt
@@ -0,0 +1,102 @@
+add_compiler_rt_component(crt)
+
+function(check_cxx_section_exists section output)
+  cmake_parse_arguments(ARG "" "" "SOURCE;FLAGS" ${ARGN})
+  if(NOT ARG_SOURCE)
+    set(ARG_SOURCE "int main() { return 0; }\n")
+  endif()
+
+  string(RANDOM TARGET_NAME)
+  set(TARGET_NAME "${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/cmTC_${TARGET_NAME}.dir")
+  file(MAKE_DIRECTORY ${TARGET_NAME})
+
+  file(WRITE "${TARGET_NAME}/CheckSectionExists.c" "${ARG_SOURCE}\n")
+
+  string(REGEX MATCHALL "<[A-Za-z0-9_]*>" substitutions
+         ${CMAKE_C_COMPILE_OBJECT})
+
+  set(try_compile_flags "${ARG_FLAGS}")
+  if(CMAKE_C_COMPILER_ID MATCHES Clang AND CMAKE_C_COMPILER_TARGET)
+    list(APPEND try_compile_flags "-target ${CMAKE_C_COMPILER_TARGET}")
+  endif()
+
+  string(REPLACE ";" " " extra_flags "${try_compile_flags}")
+
+  set(test_compile_command "${CMAKE_C_COMPILE_OBJECT}")
+  foreach(substitution ${substitutions})
+    if(substitution STREQUAL "<CMAKE_C_COMPILER>")
+      string(REPLACE "<CMAKE_C_COMPILER>"
+             "${CMAKE_C_COMPILER}" test_compile_command ${test_compile_command})
+    elseif(substitution STREQUAL "<OBJECT>")
+      string(REPLACE "<OBJECT>" "${TARGET_NAME}/CheckSectionExists.o"
+             test_compile_command ${test_compile_command})
+    elseif(substitution STREQUAL "<SOURCE>")
+      string(REPLACE "<SOURCE>" "${TARGET_NAME}/CheckSectionExists.c"
+             test_compile_command ${test_compile_command})
+    elseif(substitution STREQUAL "<FLAGS>")
+      string(REPLACE "<FLAGS>" "${CMAKE_C_FLAGS} ${extra_flags}"
+             test_compile_command ${test_compile_command})
+    else()
+      string(REPLACE "${substitution}" "" test_compile_command
+             ${test_compile_command})
+    endif()
+  endforeach()
+
+  string(REPLACE " " ";" test_compile_command "${test_compile_command}")
+
+  execute_process(
+    COMMAND ${test_compile_command}
+    RESULT_VARIABLE TEST_RESULT
+    OUTPUT_VARIABLE TEST_OUTPUT
+    ERROR_VARIABLE TEST_ERROR
+  )
+
+  execute_process(
+    COMMAND ${CMAKE_OBJDUMP} -h "${TARGET_NAME}/CheckSectionExists.o"
+    RESULT_VARIABLE CHECK_RESULT
+    OUTPUT_VARIABLE CHECK_OUTPUT
+    ERROR_VARIABLE CHECK_ERROR
+  )
+  string(FIND "${CHECK_OUTPUT}" "${section}" SECTION_FOUND)
+
+  if(NOT SECTION_FOUND EQUAL -1)
+    set(${output} TRUE PARENT_SCOPE)
+  else()
+    set(${output} FALSE PARENT_SCOPE)
+  endif()
+
+  file(REMOVE_RECURSE ${TARGET_NAME})
+endfunction()
+
+check_cxx_section_exists(".init_array" COMPILER_RT_HAS_INITFINI_ARRAY
+  SOURCE "__attribute__((constructor)) void f() {}\nint main() { return 0; }\n")
+
+append_list_if(COMPILER_RT_HAS_INITFINI_ARRAY -DCRT_HAS_INITFINI_ARRAY CRT_CFLAGS)
+append_list_if(COMPILER_RT_HAS_FPIC_FLAG -fPIC CRT_CFLAGS)
+
+foreach(arch ${CRT_SUPPORTED_ARCH})
+  add_compiler_rt_runtime(clang_rt.crtbegin
+    OBJECT
+    ARCHS ${arch}
+    SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/crtbegin.c
+    CFLAGS ${CRT_CFLAGS}
+    PARENT_TARGET crt)
+  add_compiler_rt_runtime(clang_rt.crtbegin_shared
+    OBJECT
+    ARCHS ${arch}
+    SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/crtbegin.c
+    CFLAGS ${CRT_CFLAGS} -DCRT_SHARED
+    PARENT_TARGET crt)
+  add_compiler_rt_runtime(clang_rt.crtend
+    OBJECT
+    ARCHS ${arch}
+    SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/crtend.c
+    CFLAGS ${CRT_CFLAGS}
+    PARENT_TARGET crt)
+  add_compiler_rt_runtime(clang_rt.crtend_shared
+    OBJECT
+    ARCHS ${arch}
+    SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/crtend.c
+    CFLAGS ${CRT_CFLAGS} -DCRT_SHARED
+    PARENT_TARGET crt)
+endforeach()
Index: compiler-rt/lib/crt/crtbegin.c
===================================================================
--- /dev/null
+++ compiler-rt/lib/crt/crtbegin.c
@@ -0,0 +1,108 @@
+/* ===-- crtbegin.c - Start of constructors and destructors ----------------===
+ *
+ *      	       The LLVM Compiler Infrastructure
+ *
+ * This file is dual licensed under the MIT and the University of Illinois Open
+ * Source Licenses. See LICENSE.TXT for details.
+ *
+ * ===----------------------------------------------------------------------===
+ */
+
+#include <stddef.h>
+
+__attribute__((visibility("hidden")))
+#ifdef CRT_SHARED
+void *__dso_handle = &__dso_handle;
+#else
+void *__dso_handle = (void *)0;
+#endif
+
+static long __EH_FRAME_LIST__[]
+    __attribute__((section(".eh_frame"), aligned(sizeof(void *)))) = {};
+
+extern void __register_frame_info(const void *, void *) __attribute__((weak));
+extern void *__deregister_frame_info(const void *) __attribute__((weak));
+
+#ifndef CRT_HAS_INITFINI_ARRAY
+typedef void (*fp)(void);
+
+static fp __CTOR_LIST__[]
+    __attribute__((section(".ctors"), aligned(sizeof(fp)), used)) = {(fp)-1};
+extern fp __CTOR_LIST_END__[];
+#endif
+
+#ifdef CRT_SHARED
+extern void __cxa_finalize(void *) __attribute__((weak));
+#endif
+
+static void __attribute__((used)) __do_init() {
+  static _Bool __initialized;
+  if (__builtin_expect(__initialized, 0))
+    return;
+  __initialized = 1;
+
+  static struct { void *p[8]; } __object;
+  if (__register_frame_info)
+    __register_frame_info(__EH_FRAME_LIST__, &__object);
+
+#ifndef CRT_HAS_INITFINI_ARRAY
+  const size_t n = __CTOR_LIST_END__ - __CTOR_LIST__ - 1;
+  for (size_t i = n; i >= 1; i--) __CTOR_LIST__[i]();
+#endif
+}
+
+#ifdef CRT_HAS_INITFINI_ARRAY
+__attribute__((section(".init_array"),
+               used)) static void (*__init)(void) = __do_init;
+#else  // CRT_HAS_INITFINI_ARRAY
+#if defined(__i386__) || defined(__x86_64__)
+asm(".pushsection .init,\"ax\",@progbits\n\t"
+    "call " __USER_LABEL_PREFIX__ "__do_init\n\t"
+    ".popsection");
+#elif defined(__arm__)
+asm(".pushsection .init,\"ax\",%progbits\n\t"
+    "bl " __USER_LABEL_PREFIX__ "__do_init\n\t"
+    ".popsection");
+#endif  // CRT_HAS_INITFINI_ARRAY
+#endif
+
+#ifndef CRT_HAS_INITFINI_ARRAY
+static fp __DTOR_LIST__[]
+    __attribute__((section(".dtors"), aligned(sizeof(fp)), used)) = {(fp)-1};
+extern fp __DTOR_LIST_END__[];
+#endif
+
+static void __attribute__((used)) __do_fini() {
+  static _Bool __finalized;
+  if (__builtin_expect(__finalized, 0))
+    return;
+  __finalized = 1;
+
+#ifdef CRT_SHARED
+  if (__cxa_finalize)
+    __cxa_finalize(__dso_handle);
+#endif
+
+#ifndef CRT_HAS_INITFINI_ARRAY
+  if (__deregister_frame_info)
+    __deregister_frame_info(__EH_FRAME_LIST__);
+
+  const size_t n = __DTOR_LIST_END__ - __DTOR_LIST__ - 1;
+  for (size_t i = 1; i < n; i++) __DTOR_LIST__[i]();
+#endif
+}
+
+#ifdef CRT_HAS_INITFINI_ARRAY
+__attribute__((section(".fini_array"),
+               used)) static void (*__fini)(void) = __do_fini;
+#else  // CRT_HAS_INITFINI_ARRAY
+#if defined(__i386__) || defined(__x86_64__)
+asm(".pushsection .fini,\"ax\",@progbits\n\t"
+    "call " __USER_LABEL_PREFIX__ "__do_fini\n\t"
+    ".popsection");
+#elif defined(__arm__)
+asm(".pushsection .fini,\"ax\",%progbits\n\t"
+    "bl " __USER_LABEL_PREFIX__ "__do_fini\n\t"
+    ".popsection");
+#endif
+#endif  // CRT_HAS_INIT_FINI_ARRAY
Index: compiler-rt/lib/crt/crtend.c
===================================================================
--- /dev/null
+++ compiler-rt/lib/crt/crtend.c
@@ -0,0 +1,24 @@
+/* ===-- crtend.c - End of constructors and destructors --------------------===
+ *
+ *      	       The LLVM Compiler Infrastructure
+ *
+ * This file is dual licensed under the MIT and the University of Illinois Open
+ * Source Licenses. See LICENSE.TXT for details.
+ *
+ * ===----------------------------------------------------------------------===
+ */
+
+#include <stdint.h>
+
+// Put 4-byte zero which is the length field in FDE at the end as a terminator.
+const int32_t __EH_FRAME_LIST_END__[]
+    __attribute__((section(".eh_frame"), aligned(sizeof(int32_t)),
+                   visibility("hidden"), used)) = {0};
+
+#ifndef CRT_HAS_INITFINI_ARRAY
+typedef void (*fp)(void);
+fp __CTOR_LIST_END__[]
+    __attribute__((section(".ctors"), visibility("hidden"), used)) = {0};
+fp __DTOR_LIST_END__[]
+    __attribute__((section(".dtors"), visibility("hidden"), used)) = {0};
+#endif
Index: compiler-rt/test/CMakeLists.txt
===================================================================
--- compiler-rt/test/CMakeLists.txt
+++ compiler-rt/test/CMakeLists.txt
@@ -73,6 +73,9 @@
   if(COMPILER_RT_BUILD_XRAY)
     compiler_rt_test_runtime(xray)
   endif()
+  if(COMPILER_RT_HAS_CRT)
+    add_subdirectory(crt)
+  endif()
   # ShadowCallStack does not yet provide a runtime with compiler-rt, the tests
   # include their own minimal runtime
   add_subdirectory(shadowcallstack)
Index: compiler-rt/test/crt/CMakeLists.txt
===================================================================
--- /dev/null
+++ compiler-rt/test/crt/CMakeLists.txt
@@ -0,0 +1,31 @@
+set(CRT_LIT_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
+
+set(CRT_TESTSUITES)
+
+set(CRT_TEST_DEPS "")
+
+if(NOT COMPILER_RT_STANDALONE_BUILD AND COMPILER_RT_BUILD_CRT AND
+   COMPILER_RT_HAS_CRT)
+  list(APPEND CRT_TEST_DEPS crt)
+endif()
+
+set(CRT_TEST_ARCH ${CRT_SUPPORTED_ARCH})
+if (COMPILER_RT_BUILD_CRT AND COMPILER_RT_HAS_CRT)
+  foreach(arch ${CRT_TEST_ARCH})
+    set(CRT_TEST_TARGET_ARCH ${arch})
+    string(TOLOWER "-${arch}-${OS_NAME}" CRT_TEST_CONFIG_SUFFIX)
+    get_test_cc_for_arch(${arch} CRT_TEST_TARGET_CC CRT_TEST_TARGET_CFLAGS)
+    string(TOUPPER ${arch} ARCH_UPPER_CASE)
+    set(CONFIG_NAME ${ARCH_UPPER_CASE}${OS_NAME}Config)
+
+    configure_lit_site_cfg(
+      ${CMAKE_CURRENT_SOURCE_DIR}/lit.site.cfg.in
+      ${CMAKE_CURRENT_BINARY_DIR}/${CONFIG_NAME}/lit.site.cfg)
+    list(APPEND CRT_TESTSUITES ${CMAKE_CURRENT_BINARY_DIR}/${CONFIG_NAME})
+  endforeach()
+endif()
+
+add_lit_testsuite(check-crt "Running the CRT tests"
+  ${CRT_TESTSUITES}
+  DEPENDS ${CRT_TEST_DEPS})
+set_target_properties(check-crt PROPERTIES FOLDER "Compiler-RT Misc")
Index: compiler-rt/test/crt/dso_handle.cpp
===================================================================
--- /dev/null
+++ compiler-rt/test/crt/dso_handle.cpp
@@ -0,0 +1,33 @@
+// RUN: %clangxx -g -DCRT_SHARED -c %s -fPIC -o %tshared.o
+// RUN: %clangxx -g -c %s -fPIC -o %t.o
+// RUN: %clangxx -g -shared -o %t.so -nostdlib %crti %shared_crtbegin %tshared.o %libstdcxx -lc -lm -lgcc_s %shared_crtend %crtn
+// RUN: %clangxx -g -o %t -nostdlib %crt1 %crti %crtbegin %t.o %libstdcxx -lc -lm %libgcc %t.so %crtend %crtn
+// RUN: %run %t 2>&1 | FileCheck %s
+
+#include <stdio.h>
+
+// CHECK: 1
+// CHECK-NEXT: ~A()
+
+#ifdef CRT_SHARED
+bool G;
+void C() {
+  printf("%d\n", G);
+}
+
+struct A {
+  A() { G = true; }
+  ~A() {
+    printf("~A()\n");
+  }
+};
+
+A a;
+#else
+void C();
+
+int main() {
+  C();
+  return 0;
+}
+#endif
Index: compiler-rt/test/crt/lit.cfg
===================================================================
--- /dev/null
+++ compiler-rt/test/crt/lit.cfg
@@ -0,0 +1,80 @@
+# -*- Python -*-
+
+import os
+import subprocess
+
+# Setup config name.
+config.name = 'CRT' + config.name_suffix
+
+# Setup source root.
+config.test_source_root = os.path.dirname(__file__)
+
+
+def get_library_path(file):
+    cmd = subprocess.Popen([config.clang.strip(),
+                            config.target_cflags.strip(),
+                            '-print-file-name=%s' % file],
+                           stdout=subprocess.PIPE,
+                           env=config.environment)
+    if not cmd.stdout:
+      lit_config.fatal("Couldn't find the library path for '%s'" % file)
+    dir = cmd.stdout.read().strip()
+    if sys.platform in ['win32'] and execute_external:
+        # Don't pass dosish path separator to msys bash.exe.
+        dir = dir.replace('\\', '/')
+    # Ensure the result is an ascii string, across Python2.5+ - Python3.
+    return str(dir.decode('ascii'))
+
+
+def get_libgcc_file_name():
+    cmd = subprocess.Popen([config.clang.strip(),
+                            config.target_cflags.strip(),
+                            '-print-libgcc-file-name'],
+                           stdout=subprocess.PIPE,
+                           env=config.environment)
+    if not cmd.stdout:
+      lit_config.fatal("Couldn't find the library path for '%s'" % file)
+    dir = cmd.stdout.read().strip()
+    if sys.platform in ['win32'] and execute_external:
+        # Don't pass dosish path separator to msys bash.exe.
+        dir = dir.replace('\\', '/')
+    # Ensure the result is an ascii string, across Python2.5+ - Python3.
+    return str(dir.decode('ascii'))
+
+
+def build_invocation(compile_flags):
+    return ' ' + ' '.join([config.clang] + compile_flags) + ' '
+
+
+# Setup substitutions.
+config.substitutions.append(
+    ('%clang ', build_invocation([config.target_cflags])))
+config.substitutions.append(
+    ('%clangxx ',
+     build_invocation(config.cxx_mode_flags + [config.target_cflags])))
+
+base_lib = os.path.join(
+    config.compiler_rt_libdir, "clang_rt.%%s-%s.o" % config.target_arch)
+config.substitutions.append(('%crtbegin', base_lib % "crtbegin"))
+config.substitutions.append(('%shared_crtbegin', base_lib % "crtbegin_shared"))
+config.substitutions.append(('%crtend', base_lib % "crtend"))
+config.substitutions.append(('%shared_crtend', base_lib % "crtend_shared"))
+
+config.substitutions.append(
+    ('%crt1', get_library_path('crt1.o')))
+config.substitutions.append(
+    ('%crti', get_library_path('crti.o')))
+config.substitutions.append(
+    ('%crtn', get_library_path('crtn.o')))
+
+config.substitutions.append(
+    ('%libgcc', get_libgcc_file_name()))
+
+config.substitutions.append(
+    ('%libstdcxx', '-l' + config.sanitizer_cxx_lib.lstrip('lib')))
+
+# Default test suffixes.
+config.suffixes = ['.c', '.cc', '.cpp']
+
+if config.host_os not in ['Linux']:
+    config.unsupported = True
Index: compiler-rt/test/crt/lit.site.cfg.in
===================================================================
--- /dev/null
+++ compiler-rt/test/crt/lit.site.cfg.in
@@ -0,0 +1,14 @@
+@LIT_SITE_CFG_IN_HEADER@
+
+# Tool-specific config options.
+config.name_suffix = "@CRT_TEST_CONFIG_SUFFIX@"
+config.crt_lit_source_dir = "@CRT_LIT_SOURCE_DIR@"
+config.target_cflags = "@CRT_TEST_TARGET_CFLAGS@"
+config.target_arch = "@CRT_TEST_TARGET_ARCH@"
+config.sanitizer_cxx_lib = "@SANITIZER_TEST_CXX_LIBNAME@"
+
+# Load common config for all compiler-rt lit tests
+lit_config.load_config(config, "@COMPILER_RT_BINARY_DIR@/test/lit.common.configured")
+
+# Load tool-specific config that would do the real work.
+lit_config.load_config(config, "@CRT_LIT_SOURCE_DIR@/lit.cfg")