Merge pull request #55750 from matthewbauer/llvm-cross

Allow using LLVM for cross compilation toolchain
2019-02-26 21:53:19 -05:00 · 2019-02-26 21:53:19 -05:00 · 3a4d497a6f
commit 3a4d497a6f
parent 2e23d727d6 8e25da0beb
16 changed files with 746 additions and 46 deletions
--- a/lib/systems/default.nix
+++ b/lib/systems/default.nix
@ -101,7 +101,7 @@ rec {
      in
        if final.parsed.kernel.name == pkgs.stdenv.hostPlatform.parsed.kernel.name &&
           pkgs.stdenv.hostPlatform.isCompatible final
-        then pkgs.runtimeShell
+        then "${pkgs.runtimeShell} -c"
        else if final.isWindows
        then "${wine}/bin/${wine-name}"
        else if final.isLinux && pkgs.stdenv.hostPlatform.isLinux
--- a/pkgs/development/compilers/llvm/3.8/llvm.nix
+++ b/pkgs/development/compilers/llvm/3.8/llvm.nix
@ -79,8 +79,8 @@ in stdenv.mkDerivation rec {
    "-DLLVM_ENABLE_RTTI=ON"

    "-DLLVM_HOST_TRIPLE=${stdenv.hostPlatform.config}"
-    "-DLLVM_DEFAULT_TARGET_TRIPLE=${stdenv.targetPlatform.config}"
-    "-DTARGET_TRIPLE=${stdenv.targetPlatform.config}"
+    "-DLLVM_DEFAULT_TARGET_TRIPLE=${stdenv.hostPlatform.config}"
+    "-DTARGET_TRIPLE=${stdenv.hostPlatform.config}"
  ] ++ stdenv.lib.optional enableSharedLibraries [
    "-DLLVM_LINK_LLVM_DYLIB=ON"
  ] ++ stdenv.lib.optional (!isDarwin)
--- a/pkgs/development/compilers/llvm/3.9/llvm.nix
+++ b/pkgs/development/compilers/llvm/3.9/llvm.nix
@ -120,8 +120,8 @@ in stdenv.mkDerivation rec {
    "-DCOMPILER_RT_INCLUDE_TESTS=OFF" # FIXME: requires clang source code

    "-DLLVM_HOST_TRIPLE=${stdenv.hostPlatform.config}"
-    "-DLLVM_DEFAULT_TARGET_TRIPLE=${stdenv.targetPlatform.config}"
-    "-DTARGET_TRIPLE=${stdenv.targetPlatform.config}"
+    "-DLLVM_DEFAULT_TARGET_TRIPLE=${stdenv.hostPlatform.config}"
+    "-DTARGET_TRIPLE=${stdenv.hostPlatform.config}"
  ] ++ stdenv.lib.optional enableSharedLibraries [
    "-DLLVM_LINK_LLVM_DYLIB=ON"
  ] ++ stdenv.lib.optional (!isDarwin)
--- a/pkgs/development/compilers/llvm/4/llvm.nix
+++ b/pkgs/development/compilers/llvm/4/llvm.nix
@ -100,8 +100,8 @@ in stdenv.mkDerivation (rec {
    "-DCOMPILER_RT_INCLUDE_TESTS=OFF" # FIXME: requires clang source code

    "-DLLVM_HOST_TRIPLE=${stdenv.hostPlatform.config}"
-    "-DLLVM_DEFAULT_TARGET_TRIPLE=${stdenv.targetPlatform.config}"
-    "-DTARGET_TRIPLE=${stdenv.targetPlatform.config}"
+    "-DLLVM_DEFAULT_TARGET_TRIPLE=${stdenv.hostPlatform.config}"
+    "-DTARGET_TRIPLE=${stdenv.hostPlatform.config}"
  ]
  ++ stdenv.lib.optional enableSharedLibraries
    "-DLLVM_LINK_LLVM_DYLIB=ON"
--- a/pkgs/development/compilers/llvm/6/llvm.nix
+++ b/pkgs/development/compilers/llvm/6/llvm.nix
@ -94,7 +94,7 @@ in stdenv.mkDerivation (rec {
    "-DLLVM_ENABLE_FFI=ON"
    "-DLLVM_ENABLE_RTTI=ON"
    "-DLLVM_HOST_TRIPLE=${stdenv.hostPlatform.config}"
-    "-DLLVM_DEFAULT_TARGET_TRIPLE=${stdenv.targetPlatform.config}"
+    "-DLLVM_DEFAULT_TARGET_TRIPLE=${stdenv.hostPlatform.config}"
    "-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=WebAssembly"
    "-DLLVM_ENABLE_DUMP=ON"
  ] ++ optionals enableSharedLibraries [
--- a/pkgs/development/compilers/llvm/7/bintools.nix
+++ b/pkgs/development/compilers/llvm/7/bintools.nix
@ -0,0 +1,19 @@
+{ runCommand, stdenv, llvm, lld, version }:
+
+let
+  prefix =
+    if stdenv.hostPlatform != stdenv.targetPlatform
+    then "${stdenv.targetPlatform.config}-"
+    else "";
+in runCommand "llvm-binutils-${version}" { preferLocalBuild = true; } ''
+   mkdir -p $out/bin
+   for prog in ${lld}/bin/*; do
+     ln -s $prog $out/bin/${prefix}$(basename $prog)
+   done
+   for prog in ${llvm}/bin/*; do
+     ln -s $prog $out/bin/${prefix}$(echo $(basename $prog) | sed -e "s|llvm-||")
+     ln -sf $prog $out/bin/${prefix}$(basename $prog)
+   done
+   rm -f $out/bin/${prefix}cat
+   ln -s ${lld}/bin/lld $out/bin/${prefix}ld
+''
--- a/pkgs/development/compilers/llvm/7/clang/default.nix
+++ b/pkgs/development/compilers/llvm/7/clang/default.nix
@ -5,7 +5,6 @@
 }:

 let
-  gcc = if stdenv.cc.isGNU then stdenv.cc.cc else stdenv.cc.cc.gcc;
  self = stdenv.mkDerivation ({
    name = "clang-${version}";

@ -81,8 +80,8 @@ let
    passthru = {
      isClang = true;
      inherit llvm;
-    } // stdenv.lib.optionalAttrs stdenv.targetPlatform.isLinux {
-      inherit gcc;
+    } // stdenv.lib.optionalAttrs (stdenv.targetPlatform.isLinux || (stdenv.cc.isGNU && stdenv.cc.cc ? gcc)) {
+      gcc = if stdenv.cc.isGNU then stdenv.cc.cc else stdenv.cc.cc.gcc;
    };

    meta = {
--- a/pkgs/development/compilers/llvm/7/compiler-rt.nix
+++ b/pkgs/development/compilers/llvm/7/compiler-rt.nix
@ -7,8 +7,19 @@ stdenv.mkDerivation rec {
  nativeBuildInputs = [ cmake python llvm ];
  buildInputs = stdenv.lib.optional stdenv.hostPlatform.isDarwin libcxxabi;

-  configureFlags = [
+  cmakeFlags = [
    "-DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON"
+  ] ++ stdenv.lib.optional (stdenv.hostPlatform != stdenv.buildPlatform) [
+    "-DCMAKE_C_FLAGS=-nodefaultlibs"
+    "-DCMAKE_CXX_COMPILER_WORKS=ON"
+    "-DCOMPILER_RT_BUILD_BUILTINS=ON"
+    "-DCOMPILER_RT_BUILD_SANITIZERS=OFF"
+    "-DCOMPILER_RT_BUILD_XRAY=OFF"
+    "-DCOMPILER_RT_BUILD_LIBFUZZER=OFF"
+    "-DCOMPILER_RT_BUILD_PROFILE=OFF"
+    "-DCMAKE_C_COMPILER_TARGET=${stdenv.hostPlatform.config}"
+    "-DCMAKE_ASM_COMPILER_TARGET=${stdenv.hostPlatform.config}"
+    "-DCOMPILER_RT_BAREMETAL_BUILD=ON"
  ];

  outputs = [ "out" "dev" ];
@ -16,7 +27,8 @@ stdenv.mkDerivation rec {
  patches = [
    ./compiler-rt-codesign.patch # Revert compiler-rt commit that makes codesign mandatory
  ] ++ stdenv.lib.optional stdenv.hostPlatform.isMusl ./sanitizers-nongnu.patch
-  ++ stdenv.lib.optional stdenv.hostPlatform.isDarwin ./compiler-rt-clock_gettime.patch;
+    ++ stdenv.lib.optional (stdenv.hostPlatform != stdenv.buildPlatform) ./crtbegin-and-end.patch
+    ++ stdenv.lib.optional stdenv.hostPlatform.isDarwin ./compiler-rt-clock_gettime.patch;

  # TSAN requires XPC on Darwin, which we have no public/free source files for. We can depend on the Apple frameworks
  # to get it, but they're unfree. Since LLVM is rather central to the stdenv, we patch out TSAN support so that Hydra
@ -26,11 +38,23 @@ stdenv.mkDerivation rec {
  postPatch = stdenv.lib.optionalString stdenv.isDarwin ''
    substituteInPlace cmake/config-ix.cmake \
      --replace 'set(COMPILER_RT_HAS_TSAN TRUE)' 'set(COMPILER_RT_HAS_TSAN FALSE)'
+  '' + stdenv.lib.optionalString (stdenv.hostPlatform != stdenv.buildPlatform) ''
+    substituteInPlace lib/builtins/int_util.c \
+      --replace "#include <stdlib.h>" ""
+    substituteInPlace lib/builtins/clear_cache.c \
+      --replace "#include <assert.h>" ""
+    substituteInPlace lib/builtins/cpu_model.c \
+      --replace "#include <assert.h>" ""
  '';

  # Hack around weird upsream RPATH bug
  postInstall = stdenv.lib.optionalString stdenv.isDarwin ''
    ln -s "$out/lib"/*/* "$out/lib"
+  '' + stdenv.lib.optionalString (stdenv.hostPlatform != stdenv.buildPlatform) ''
+    ln -s $out/lib/*/clang_rt.crtbegin-*.o $out/lib/linux/crtbegin.o
+    ln -s $out/lib/*/cclang_rt.crtend-*.o $out/lib/linux/crtend.o
+    ln -s $out/lib/*/clang_rt.crtbegin_shared-*.o $out/lib/linux/crtbeginS.o
+    ln -s $out/lib/*/clang_rt.crtend_shared-*.o $out/lib/linux/crtendS.o
  '';

  enableParallelBuilding = true;
--- a/pkgs/development/compilers/llvm/7/crtbegin-and-end.patch
+++ b/pkgs/development/compilers/llvm/7/crtbegin-and-end.patch
@ -0,0 +1,595 @@
+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 +1,101 @@
+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)
+
+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 -fPIC
+    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 -fPIC
+    PARENT_TARGET crt)
+endforeach()
+Index: compiler-rt/lib/crt/crtbegin.c
+===================================================================
+--- /dev/null
+++ compiler-rt/lib/crt/crtbegin.c
+@@ -0,0 +1,110 @@
+/* ===-- 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 *)), visibility("hidden"))) = {};
+
+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)), visibility("hidden"),
+                   used)) = {(fp)-1};
+extern fp __CTOR_LIST_END__[] __attribute__((visibility("hidden")));
+#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)), visibility("hidden"),
+                   used)) = {(fp)-1};
+extern fp __DTOR_LIST_END__[] __attribute__((visibility("hidden")));
+#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 +1,23 @@
+/* ===-- 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)), 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")
--- a/pkgs/development/compilers/llvm/7/default.nix
+++ b/pkgs/development/compilers/llvm/7/default.nix
@ -1,5 +1,5 @@
 { lowPrio, newScope, pkgs, stdenv, cmake, libstdcxxHook
-, libxml2, python, isl, fetchurl, overrideCC, wrapCCWith
+, libxml2, python, isl, fetchurl, overrideCC, wrapCCWith, wrapBintoolsWith
 , buildLlvmTools # tools, but from the previous stage, for cross
 , targetLlvmLibraries # libraries, but from the next stage, for cross
 }:
@ -23,7 +23,7 @@ let
      ln -s "${cc}/lib/clang/${release_version}/include" "$rsrc"
      ln -s "${targetLlvmLibraries.compiler-rt.out}/lib" "$rsrc/lib"
      echo "-resource-dir=$rsrc" >> $out/nix-support/cc-cflags
-    '' + stdenv.lib.optionalString stdenv.targetPlatform.isLinux ''
+    '' + stdenv.lib.optionalString (stdenv.targetPlatform.isLinux && tools.clang-unwrapped ? gcc) ''
      echo "--gcc-toolchain=${tools.clang-unwrapped.gcc}" >> $out/nix-support/cc-cflags
    '';
  in {
@ -77,13 +77,63 @@ let
    lld = callPackage ./lld.nix {};

    lldb = callPackage ./lldb.nix {};
+
+    bintools = callPackage ./bintools.nix {};
+
+    lldClang = wrapCCWith rec {
+      cc = tools.clang-unwrapped;
+      bintools = wrapBintoolsWith {
+        inherit (tools) bintools;
+      };
+      extraPackages = [
+        # targetLlvmLibraries.libcxx
+        # targetLlvmLibraries.libcxxabi
+        targetLlvmLibraries.compiler-rt
+      ];
+      extraBuildCommands = ''
+        echo "-target ${stdenv.targetPlatform.config} -rtlib=compiler-rt" >> $out/nix-support/cc-cflags
+      '' + mkExtraBuildCommands cc;
+    };
+
+    lldClangNoLibc = wrapCCWith rec {
+      cc = tools.clang-unwrapped;
+      bintools = wrapBintoolsWith {
+        inherit (tools) bintools;
+        libc = null;
+      };
+      extraPackages = [
+        # targetLlvmLibraries.libcxx
+        # targetLlvmLibraries.libcxxabi
+        targetLlvmLibraries.compiler-rt
+      ];
+      extraBuildCommands = ''
+        echo "-target ${stdenv.targetPlatform.config} -rtlib=compiler-rt" >> $out/nix-support/cc-cflags
+      '' + mkExtraBuildCommands cc;
+    };
+
+    lldClangNoCompilerRt = wrapCCWith rec {
+      cc = tools.clang-unwrapped;
+      bintools = wrapBintoolsWith {
+        inherit (tools) bintools;
+        libc = null;
+      };
+      extraPackages = [ ];
+      extraBuildCommands = ''
+        echo "-nostartfiles -target ${stdenv.targetPlatform.config}" >> $out/nix-support/cc-cflags
+      '';
+    };
+
  });

  libraries = stdenv.lib.makeExtensible (libraries: let
    callPackage = newScope (libraries // buildLlvmTools // { inherit stdenv cmake libxml2 python isl release_version version fetch; });
  in {

-    compiler-rt = callPackage ./compiler-rt.nix {};
+    compiler-rt = callPackage ./compiler-rt.nix {
+      stdenv = if stdenv.hostPlatform.useLLVM or false
+               then overrideCC stdenv buildLlvmTools.lldClangNoCompilerRt
+               else stdenv;
+    };

    stdenv = overrideCC stdenv buildLlvmTools.clang;

--- a/pkgs/development/compilers/llvm/7/llvm.nix
+++ b/pkgs/development/compilers/llvm/7/llvm.nix
@ -106,7 +106,7 @@ in stdenv.mkDerivation (rec {
    "-DLLVM_ENABLE_FFI=ON"
    "-DLLVM_ENABLE_RTTI=ON"
    "-DLLVM_HOST_TRIPLE=${stdenv.hostPlatform.config}"
-    "-DLLVM_DEFAULT_TARGET_TRIPLE=${stdenv.targetPlatform.config}"
+    "-DLLVM_DEFAULT_TARGET_TRIPLE=${stdenv.hostPlatform.config}"
    "-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=WebAssembly"
    "-DLLVM_ENABLE_DUMP=ON"
  ] ++ optionals enableSharedLibraries [
--- a/pkgs/development/libraries/libpfm/default.nix
+++ b/pkgs/development/libraries/libpfm/default.nix
@ -12,8 +12,8 @@ stdenv.mkDerivation rec {
  makeFlags = [
    "PREFIX=${placeholder "out"}"
    "LDCONFIG=true"
-    "ARCH=${stdenv.targetPlatform.uname.processor}"
-    "SYS=${stdenv.targetPlatform.uname.system}"
+    "ARCH=${stdenv.hostPlatform.uname.processor}"
+    "SYS=${stdenv.hostPlatform.uname.system}"
  ];

  NIX_CFLAGS_COMPILE = [ "-Wno-error" ];
--- a/pkgs/stdenv/cross/default.nix
+++ b/pkgs/stdenv/cross/default.nix
@ -54,6 +54,8 @@ in lib.init bootStages ++ [
             then buildPackages.darwin.iosSdkPkgs.clang
           else if crossSystem.useAndroidPrebuilt or false
             then buildPackages."androidndkPkgs_${crossSystem.ndkVer}".gcc
+           else if crossSystem.useLLVM or false
+             then buildPackages.llvmPackages_7.lldClang
           else buildPackages.gcc;

      extraNativeBuildInputs = old.extraNativeBuildInputs
--- a/pkgs/stdenv/generic/make-derivation.nix
+++ b/pkgs/stdenv/generic/make-derivation.nix
@ -86,7 +86,7 @@ rec {
      doCheck' = doCheck && stdenv.hostPlatform == stdenv.buildPlatform;
      doInstallCheck' = doInstallCheck && stdenv.hostPlatform == stdenv.buildPlatform;

-      separateDebugInfo' = separateDebugInfo && stdenv.hostPlatform.isLinux;
+      separateDebugInfo' = separateDebugInfo && stdenv.hostPlatform.isLinux && !(stdenv.hostPlatform.useLLVM or false);
      outputs' = outputs ++ lib.optional separateDebugInfo' "debug";

      fixedOutputDrv = attrs ? outputHash;
--- a/pkgs/test/cross/default.nix
+++ b/pkgs/test/cross/default.nix
@ -26,14 +26,20 @@ let
    # We need to remove whitespace, unfortunately
    # Windows programs use \r but Unix programs use \n

+    echo Running native-built program natively
+
    # find expected value natively
    ${getExecutable hostPkgs pkgFun exec} ${args'} \
      | dos2unix > $out/expected

+    echo Running cross-built program in emulator
+
    # run emulator to get actual value
    ${emulator} ${getExecutable crossPkgs pkgFun exec} ${args'} \
      | dos2unix > $out/actual

+    echo Comparing results...
+
    if [ "$(cat $out/actual)" != "$(cat $out/expected)" ]; then
      echo "${pkgName} did not output expected value:"
      cat $out/expected
@ -47,10 +53,10 @@ let
    fi
  '';

-  mapMultiPlatformTest = test: lib.mapAttrs (name: system: test rec {
+  mapMultiPlatformTest = crossSystemFun: test: lib.mapAttrs (name: system: test rec {
    crossPkgs = import pkgs.path {
      localSystem = { inherit (pkgs.hostPlatform) config; };
-      crossSystem = system;
+      crossSystem = crossSystemFun system;
    };

    emulator = crossPkgs.hostPlatform.emulator pkgs;
@ -65,26 +71,30 @@ let
      } else pkg;
  }) testedSystems;

-in
+  tests = {

-lib.mapAttrs (_: mapMultiPlatformTest) {
+    file = {platformFun, crossPkgs, emulator}: compareTest {
+      inherit emulator crossPkgs;
+      hostPkgs = pkgs;
+      exec = "/bin/file";
+      args = [
+        "${pkgs.file}/share/man/man1/file.1.gz"
+        "${pkgs.dejavu_fonts}/share/fonts/truetype/DejaVuMathTeXGyre.ttf"
+      ];
+      pkgFun = pkgs: platformFun pkgs.file;
+    };
+
+    hello = {platformFun, crossPkgs, emulator}: compareTest {
+      inherit emulator crossPkgs;
+      hostPkgs = pkgs;
+      exec = "/bin/hello";
+      pkgFun = pkgs: pkgs.hello;
+    };

-  file = {platformFun, crossPkgs, emulator}: compareTest {
-    inherit emulator crossPkgs;
-    hostPkgs = pkgs;
-    exec = "/bin/file";
-    args = [
-      "${pkgs.file}/share/man/man1/file.1.gz"
-      "${pkgs.dejavu_fonts}/share/fonts/truetype/DejaVuMathTeXGyre.ttf"
-    ];
-    pkgFun = pkgs: platformFun pkgs.file;
  };

-  hello = {platformFun, crossPkgs, emulator}: compareTest {
-    inherit emulator crossPkgs;
-    hostPkgs = pkgs;
-    exec = "/bin/hello";
-    pkgFun = pkgs: pkgs.hello;
-  };
-
-}
+in (lib.mapAttrs (_: mapMultiPlatformTest builtins.id) tests)
+// (lib.mapAttrs' (name: test: {
+    name = "${name}-llvm";
+    value = mapMultiPlatformTest (system: system // {useLLVM = true;}) test;
+  }) tests)
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@ -6842,7 +6842,10 @@ in
    { substitutions = { gcc = gcc-unwrapped; }; }
    ../development/compilers/gcc/libstdc++-hook.sh;

-  crossLibcStdenv = overrideCC stdenv buildPackages.gccCrossStageStatic;
+  crossLibcStdenv = overrideCC stdenv
+    (if stdenv.targetPlatform.useLLVM or false
+     then buildPackages.llvmPackages_7.lldClangNoLibc
+     else buildPackages.gccCrossStageStatic);

  # The GCC used to build libc for the target platform. Normal gccs will be
  # built with, and use, that cross-compiled libc.
@ -7384,13 +7387,11 @@ in
    stdenv = overrideCC stdenv buildPackages.gcc6; # with gcc-7: undefined reference to `__divmoddi4'
  });

-  llvmPackages_7 = callPackage ../development/compilers/llvm/7 ({
+  llvmPackages_7 = callPackage ../development/compilers/llvm/7 {
    inherit (stdenvAdapters) overrideCC;
    buildLlvmTools = buildPackages.llvmPackages_7.tools;
    targetLlvmLibraries = targetPackages.llvmPackages_7.libraries;
-  } // stdenv.lib.optionalAttrs (stdenv.cc.isGNU && stdenv.hostPlatform.isi686) {
-    stdenv = overrideCC stdenv buildPackages.gcc6; # with gcc-7: undefined reference to `__divmoddi4'
-  });
+  };

  llvmPackages_latest = llvmPackages_7;