Add initial support for cross compile Windows runtimes under Linux when building Fuchsia clang toolchain

[haowei]

Summary

Initial work on building Windows compiler runtimes under Linux.

[haowei]

Correct C, CXX flag issue.

[phosek]

clang/cmake/caches/Fuchsia-stage2.cmake

73

I'd drop this part altogether, let's build these anytime when WINDOWS_SDK_DIR is set.

96–99

I think we should introduce a new LLVM CMake option for setting this akin to LLVM_WINSYSROOT (for example LLVM_VFSOVERLAY).

100–101

Can we instead set BUILTINS_${target}_LLVM_WINSYSROOT to ${WINDOWS_SDK_DIR}?

105–108

These should be set automatically if you set /winsysroot (through LLVM_WINSYSROOT), see https://github.com/llvm/llvm-project/blob/a64846bee0bb4b4912c8cf6bf018ba5d892065d1/clang/lib/Driver/ToolChains/MSVC.cpp#L107.

142–143

Can we instead set RUNTIMES_${target}_LLVM_WINSYSROOT to ${WINDOWS_SDK_DIR}?

llvm/cmake/modules/LLVMExternalProjectUtils.cmake

172

This should be in a separate block just like other tools below guarded by a llvm-rc IN_LIST TOOLCHAIN_TOOLS condition.

173

This should be in a separate block just like other tools below guarded by a llvm-mt IN_LIST TOOLCHAIN_TOOLS condition.

llvm/runtimes/CMakeLists.txt

359

We should fix the build so that this isn't needed, it should be possible to use LLVM_USE_LINKER=lld when targeting Windows.

[haowei]

clang/cmake/caches/Fuchsia-stage2.cmake

73

We need to do a soft transition if we drop the "WIN32" since the bots are not passing the WINSYSROOT flag yet. Let's keep the WIN32 here.

105–108

There is an issue that "CLANG_CL" variable is not correctly set when clang kicks runtime build. When CLANG_CL is not set, the /winsysroot will not be added by the LLVM_WINSYSROOT flag. I have some thoughts about it and prefer to address this issue in a follow up patch instead of put everything here.

142–143

As stated in an earlier comment, this will require fixing the setting the "CLANG_CL" variable in compiler version detection.

llvm/runtimes/CMakeLists.txt

359

I made some other changes and now the /fuse-ld=lld will be passed to lld-link.exe if we leave this line unchanged.
It will through a warning but won't stop the build.
Once I fix the CLANG_CL issue, I can prevent it from inserting /fuse-ld=lld when using CLANG_CL

[haowei]

Correct an issue llvm-rc and llvm-mt are not part of TOOLCHAIN_TOOLS

[phosek]

clang/cmake/caches/Fuchsia-stage2.cmake

79

I think we'll want to use these flags even when not cross-compiling so I'd change the name to reflect that.

81–115

You can set these unconditionally (unset variables in CMake evaluate to empty string).

90

I think we'll want to use these flags even when not cross-compiling so I'd change the name to reflect that.

123–132

You can set these unconditionally.

[phosek]

LGTM

[haowei]

Thanks for the review. I will land the change once Fuchsia clang builders are green.

[thakis]

clang/cmake/caches/Fuchsia-stage2.cmake

95

You can tell cmake to invoke lld-link, which has a /winsysroot: flag.

[haowei]

clang/cmake/caches/Fuchsia-stage2.cmake

95

What would be a good way to make CMake invoke lld-link (or through clang-cl) instead of using cmake vs_link in this situation?
We thought about using

set(CMAKE_${LANG}_SIMULATE_ID "MSVC")
set(CMAKE_${LANG}_COMPILER_FRONTEND_VARIANT "GNU")

but I don't feel great about changing variables that are not suppose to change.

[phosek]

clang/cmake/caches/Fuchsia-stage2.cmake

95

Wouldn't CMake use lld-link if you set CMAKE_LINKER=lld-link. We already do this in https://github.com/llvm/llvm-project/blob/0e09bb8b143c80426c497a924ee4fa57a26af6b5/llvm/cmake/modules/LLVMExternalProjectUtils.cmake#L179 which is used by the bootstrapping build so you should be able to use /winsysroot: here.

[haowei]

Correct dependency issues on llvm-mt

[phosek]

clang/cmake/caches/Fuchsia-stage2.cmake

95

@haowei have tried this suggestion?

[haowei]

clang/cmake/caches/Fuchsia-stage2.cmake

95

I tried:

FAILED: runtimes/runtimes-x86_64-pc-windows-msvc-stamps/runtimes-x86_64-pc-windows-msvc-configure /mnt/nvme_sec/SRC/llvm-project/build-lldlink/runtimes/runtimes-x86_64-pc-windows-msvc-stamps/runtimes-x86_64-pc-windows-msvc-configure 
cd /mnt/nvme_sec/SRC/llvm-project/build-lldlink/runtimes/runtimes-x86_64-pc-windows-msvc-bins && /mnt/nvme_sec/SRC/llvm-prebuilts/cmake/linux-amd64/bin/cmake \
-DCMAKE_C_COMPILER=/mnt/nvme_sec/SRC/llvm-project/build-lldlink/./bin/clang-cl \
-DCMAKE_CXX_COMPILER=/mnt/nvme_sec/SRC/llvm-project/build-lldlink/./bin/clang-cl \
-DCMAKE_ASM_COMPILER=/mnt/nvme_sec/SRC/llvm-project/build-lldlink/./bin/clang-cl \
-DCMAKE_LINKER=/mnt/nvme_sec/SRC/llvm-project/build-lldlink/./bin/lld-link \
....

But cmake is still using vs_link, see:

FAILED: cmTC_a05d1.exe 
        : && /mnt/nvme_sec/SRC/llvm-prebuilts/cmake/linux-amd64/bin/cmake -E vs_link_exe --intdir=CMakeFiles/cmTC_a05d1.dir --rc=/mnt/nvme_sec/SRC/llvm-project/build-lldlink/./bin/llvm-rc --mt=/mnt/nvme_sec/SRC/llvm-project/build-lldlink/bin/llvm-mt --manifests  -- /mnt/nvme_sec/SRC/llvm-project/build-lldlink/bin/lld-link /nologo CMakeFiles/cmTC_a05d1.dir/CMakeCCompilerABI.c.obj  /out:cmTC_a05d1.exe /implib:cmTC_a05d1.lib /pdb:cmTC_a05d1.pdb /version:0.0 /vfsoverlay:/mnt/nvme_sec/SRC/WinSDK/winsdk-cipd/llvm-vfsoverlay.yaml  /debug /INCREMENTAL /subsystem:console

[phosek]

LGTM

clang/cmake/caches/Fuchsia-stage2.cmake

95

Thanks for checking, we should investigate this further and perhaps reach out to CMake maintainers but that can be done separately.

clang/cmake/caches/Fuchsia-stage2.cmake

if(APPLE)
   set(LIBCXXABI_USE_LLVM_UNWINDER ON CACHE BOOL "")
   set(LIBCXX_ABI_VERSION 2 CACHE STRING "")
   set(LIBCXX_ENABLE_SHARED OFF CACHE BOOL "")
   set(LIBCXX_ENABLE_STATIC_ABI_LIBRARY ON CACHE BOOL "")
   set(LIBCXX_USE_COMPILER_RT ON CACHE BOOL "")
   set(RUNTIMES_CMAKE_ARGS "-DCMAKE_OSX_DEPLOYMENT_TARGET=10.13;-DCMAKE_OSX_ARCHITECTURES=arm64|x86_64" CACHE STRING "")
 endif()
 
-if(WIN32)
+
+if(WIN32 OR (LINUX AND WINDOWS_SDK_DIR))
+#if(WINDOWS_SDK_DIR)
+  #message(FATAL_ERROR "${WINDOWS_SDK_DIR} is set")
   set(target "x86_64-pc-windows-msvc")
 
   list(APPEND BUILTIN_TARGETS "${target}")
   set(BUILTINS_${target}_CMAKE_SYSTEM_NAME Windows CACHE STRING "")
   set(BUILTINS_${target}_CMAKE_BUILD_TYPE RelWithDebInfo CACHE STRING "")
 
+  if(LINUX AND WINDOWS_SDK_DIR)
+    if(NOT FUCHSIA_TOOLCHAIN_DIR)
+      message(FATAL_ERROR "FUCHSIA_TOOLCHAIN_DIR should be defined")
+    endif()
+    set(BUILTINS_${target}_WINDOWS_SDK_DIR ${WINDOWS_SDK_DIR})
+    # set(BUILTINS_${target}_CMAKE_C_COMPILER "${FUCHSIA_TOOLCHAIN_DIR}/bin/clang-cl")
+    # set(BUILTINS_${target}_CMAKE_CXX_COMPILER "${FUCHSIA_TOOLCHAIN_DIR}/bin/clang-cl")
+    # set(BUILTINS_${target}_CMAKE_ASM_COMPILER "${FUCHSIA_TOOLCHAIN_DIR}/bin/clang-cl")
+    # set(BUILTINS_${target}_CMAKE_LINKER_COMPILER "${FUCHSIA_TOOLCHAIN_DIR}/bin/llvm-link")
+    # set(BUILTINS_${target}_CMAKE_AR "${FUCHSIA_TOOLCHAIN_DIR}/bin/llvm-lib")
+    # set(BUILTINS_${target}_CMAKE_NM "${FUCHSIA_TOOLCHAIN_DIR}/bin/llvm-nm")
+    # set(BUILTINS_${target}_CMAKE_RC "${FUCHSIA_TOOLCHAIN_DIR}/bin/llvm-rc")
+    # set(BUILTINS_${target}_CMAKE_MT "${FUCHSIA_TOOLCHAIN_DIR}/bin/llvm-mt")
+    set(CLANG_WINDOWS_CROSS_FLAGS
+        -Xclang
+        -ivfsoverlay
+        -Xclang
+        "${WINDOWS_SDK_DIR}/llvm-vfsoverlay.yaml"
+        /winsysroot
+        ${WINDOWS_SDK_DIR})
+    set(LINK_WINDOWS_OVERLAY_FLAGS
+        /vfsoverlay:"${WINDOWS_SDK_DIR}/llvm-vfsoverlay.yaml"
+        -libpath:"${WINDOWS_SDK_DIR}/VC/Tools/MSVC/14.34.31933/lib/x64"
+        -libpath:"${WINDOWS_SDK_DIR}/VC/Tools/MSVC/14.34.31933/atlmfc/lib/x64"
+        -libpath:"${WINDOWS_SDK_DIR}/Windows Kits/10/Lib/10.0.19041.0/ucrt/x64"
+        -libpath:"${WINDOWS_SDK_DIR}/Windows Kits/10/Lib/10.0.19041.0/um/x64")
+    set(BUILTINS_${target}_CMAKE_C_FLAGS ${CLANG_WINDOWS_CROSS_FLAGS} CACHE STRING "")
+    set(BUILTINS_${target}_CMAKE_CXX_FLAGS ${CLANG_WINDOWS_CROSS_FLAGS} CACHE STRING "")
+    set(BUILTINS_${target}_CMAKE_EXE_LINKER_FLAGS ${LINK_WINDOWS_OVERLAY_FLAGS} CACHE STRING "")
+    set(BUILTINS_${target}_CMAKE_SHARED_LINKER_FLAGS ${LINK_WINDOWS_OVERLAY_FLAGS} CACHE STRING "")
+    set(BUILTINS_${target}_CMAKE_MODULE_LINKER_FLAGS ${LINK_WINDOWS_OVERLAY_FLAGS} CACHE STRING "")
+  endif()
+
   list(APPEND RUNTIME_TARGETS "${target}")
   set(RUNTIMES_${target}_CMAKE_SYSTEM_NAME Windows CACHE STRING "")
   set(RUNTIMES_${target}_CMAKE_BUILD_TYPE RelWithDebInfo CACHE STRING "")
   set(RUNTIMES_${target}_LIBCXX_ABI_VERSION 2 CACHE STRING "")
   set(RUNTIMES_${target}_LIBCXX_ENABLE_FILESYSTEM OFF CACHE BOOL "")
   set(RUNTIMES_${target}_LIBCXX_ENABLE_ABI_LINKER_SCRIPT OFF CACHE BOOL "")
   set(RUNTIMES_${target}_LIBCXX_ENABLE_SHARED OFF CACHE BOOL "")
   set(RUNTIMES_${target}_LLVM_ENABLE_RUNTIMES "compiler-rt;libcxx" CACHE STRING "")
+
+  if(LINUX AND WINDOWS_SDK_DIR)
+    if(NOT FUCHSIA_TOOLCHAIN_DIR)
+      message(FATAL_ERROR "FUCHSIA_TOOLCHAIN_DIR should be defined")
+    endif()
+    # set(RUNTIMES_${target}_WINDOWS_SDK_DIR ${WINDOWS_SDK_DIR})
+    # set(RUNTIMES_${target}_CMAKE_C_COMPILER "${FUCHSIA_TOOLCHAIN_DIR}/bin/clang-cl")
+    # set(RUNTIMES_${target}_CMAKE_CXX_COMPILER "${FUCHSIA_TOOLCHAIN_DIR}/bin/clang-cl")
+    # set(RUNTIMES_${target}_CMAKE_ASM_COMPILER "${FUCHSIA_TOOLCHAIN_DIR}/bin/clang-cl")
+    # set(RUNTIMES_${target}_CMAKE_LINKER_COMPILER "${FUCHSIA_TOOLCHAIN_DIR}/bin/llvm-link")
+    # set(RUNTIMES_${target}_CMAKE_AR "${FUCHSIA_TOOLCHAIN_DIR}/bin/llvm-lib")
+    # set(RUNTIMES_${target}_CMAKE_NM "${FUCHSIA_TOOLCHAIN_DIR}/bin/llvm-nm")
+    # set(RUNTIMES_${target}_CMAKE_RC "${FUCHSIA_TOOLCHAIN_DIR}/bin/llvm-rc")
+    # set(RUNTIMES_${target}_CMAKE_MT "${FUCHSIA_TOOLCHAIN_DIR}/bin/llvm-mt")
+    set(CLANG_WINDOWS_CROSS_FLAGS
+        -Xclang
+        -ivfsoverlay
+        -Xclang
+        "${WINDOWS_SDK_DIR}/llvm-vfsoverlay.yaml"
+        /winsysroot
+        ${WINDOWS_SDK_DIR})
+    set(LINK_WINDOWS_OVERLAY_FLAGS
+        /vfsoverlay:"${WINDOWS_SDK_DIR}/llvm-vfsoverlay.yaml"
+        -libpath:"${WINDOWS_SDK_DIR}/VC/Tools/MSVC/14.34.31933/lib/x64"
+        -libpath:"${WINDOWS_SDK_DIR}/VC/Tools/MSVC/14.34.31933/atlmfc/lib/x64"
+        -libpath:"${WINDOWS_SDK_DIR}/Windows Kits/10/Lib/10.0.19041.0/ucrt/x64"
+        -libpath:"${WINDOWS_SDK_DIR}/Windows Kits/10/Lib/10.0.19041.0/um/x64")
+    set(RUNTIMES_${target}_CMAKE_C_FLAGS "-Xclang -ivfsoverlay -Xclang ${WINDOWS_SDK_DIR}/llvm-vfsoverlay.yaml /winsysroot ${WINDOWS_SDK_DIR}" CACHE STRING "")
+    set(RUNTIMES_${target}_CMAKE_CXX_FLAGS "-Xclang -ivfsoverlay -Xclang ${WINDOWS_SDK_DIR}/llvm-vfsoverlay.yaml /winsysroot ${WINDOWS_SDK_DIR}" CACHE STRING "")
+    set(RUNTIMES_${target}_CMAKE_EXE_LINKER_FLAGS "/vfsoverlay:${WINDOWS_SDK_DIR}/llvm-vfsoverlay.yaml" CACHE STRING "")
+    set(RUNTIMES_${target}_CMAKE_SHARED_LINKER_FLAGS "/vfsoverlay:${WINDOWS_SDK_DIR}/llvm-vfsoverlay.yaml" CACHE STRING "")
+    set(RUNTIMES_${target}_CMAKE_MODULE_LINKER_FLAGS "/vfsoverlay:${WINDOWS_SDK_DIR}/llvm-vfsoverlay.yaml" CACHE STRING "")
+  endif()
 endif()
 
 foreach(target aarch64-unknown-linux-gnu;armv7-unknown-linux-gnueabihf;i386-unknown-linux-gnu;x86_64-unknown-linux-gnu)
   if(LINUX_${target}_SYSROOT)
     # Set the per-target builtins options.
     list(APPEND BUILTIN_TARGETS "${target}")
     set(BUILTINS_${target}_CMAKE_SYSTEM_NAME Linux CACHE STRING "")
     set(BUILTINS_${target}_CMAKE_BUILD_TYPE RelWithDebInfo CACHE STRING "")
if(FUCHSIA_SDK)
   set(LLVM_RUNTIME_MULTILIB_asan_TARGETS "x86_64-unknown-fuchsia;aarch64-unknown-fuchsia" CACHE STRING "")
   set(LLVM_RUNTIME_MULTILIB_noexcept_TARGETS "x86_64-unknown-fuchsia;aarch64-unknown-fuchsia" CACHE STRING "")
   set(LLVM_RUNTIME_MULTILIB_compat_TARGETS "x86_64-unknown-fuchsia;aarch64-unknown-fuchsia" CACHE STRING "")
   set(LLVM_RUNTIME_MULTILIB_asan+noexcept_TARGETS "x86_64-unknown-fuchsia;aarch64-unknown-fuchsia" CACHE STRING "")
   set(LLVM_RUNTIME_MULTILIB_hwasan_TARGETS "aarch64-unknown-fuchsia" CACHE STRING "")
   set(LLVM_RUNTIME_MULTILIB_hwasan+noexcept_TARGETS "aarch64-unknown-fuchsia" CACHE STRING "")
 endif()
 
+
+# if(LINUX)
+#   if (WINDOWS_SDK_DIR)
+#   endif()
+# endif()
+
 set(LLVM_BUILTIN_TARGETS "${BUILTIN_TARGETS}" CACHE STRING "")
 set(LLVM_RUNTIME_TARGETS "${RUNTIME_TARGETS}" CACHE STRING "")
 
+message(NOTICE "Fuchisa Clang builtins: ${LLVM_BUILTIN_TARGETS}")
+message(NOTICE "Fuchisa Clang runtimes: ${LLVM_RUNTIME_TARGETS}")
+
 # Setup toolchain.
 set(LLVM_INSTALL_TOOLCHAIN_ONLY ON CACHE BOOL "")
 set(LLVM_TOOLCHAIN_TOOLS
   dsymutil
   llvm-ar
   llvm-bolt
   llvm-cov
   llvm-cxxfilt

llvm/cmake/modules/LLVMExternalProjectUtils.cmake

foreach(prefix ${ARG_PASSTHROUGH_PREFIXES})
     endforeach()
   endforeach()
 
   if(ARG_USE_TOOLCHAIN AND NOT CMAKE_CROSSCOMPILING)
     if(CLANG_IN_TOOLCHAIN)
       if(is_msvc_target)
         set(compiler_args -DCMAKE_C_COMPILER=${LLVM_RUNTIME_OUTPUT_INTDIR}/clang-cl${CMAKE_EXECUTABLE_SUFFIX}
                           -DCMAKE_CXX_COMPILER=${LLVM_RUNTIME_OUTPUT_INTDIR}/clang-cl${CMAKE_EXECUTABLE_SUFFIX}
-                          -DCMAKE_ASM_COMPILER=${LLVM_RUNTIME_OUTPUT_INTDIR}/clang-cl${CMAKE_EXECUTABLE_SUFFIX})
+                          -DCMAKE_ASM_COMPILER=${LLVM_RUNTIME_OUTPUT_INTDIR}/clang-cl${CMAKE_EXECUTABLE_SUFFIX}
+                          -DCMAKE_RC_COMPILER=${LLVM_RUNTIME_OUTPUT_INTDIR}/llvm-rc
+                          -DCMAKE_MT=${LLVM_RUNTIME_OUTPUT_INTDIR}/llvm-mt
+                          )
       else()
         set(compiler_args -DCMAKE_C_COMPILER=${LLVM_RUNTIME_OUTPUT_INTDIR}/clang${CMAKE_EXECUTABLE_SUFFIX}
                           -DCMAKE_CXX_COMPILER=${LLVM_RUNTIME_OUTPUT_INTDIR}/clang++${CMAKE_EXECUTABLE_SUFFIX}
                           -DCMAKE_ASM_COMPILER=${LLVM_RUNTIME_OUTPUT_INTDIR}/clang${CMAKE_EXECUTABLE_SUFFIX})
       endif()
     endif()
     if(lld IN_LIST TOOLCHAIN_TOOLS)
       if(is_msvc_target)

llvm/runtimes/CMakeLists.txt

 # TODO: This file assumes the Clang toolchain so it'd be better if it lived in
 # Clang, except there already is clang/runtime directory which contains
 # similar although simpler functionality. We should figure out how to merge
 # the two files.
 
+message(NOTICE "Fuchisa Clang compiler-rt hello world")
+message(NOTICE "CMAKE_CURRENT_SOURCE_DIR is ${CMAKE_CURRENT_SOURCE_DIR}")
 set(COMMON_CMAKE_ARGS "-DHAVE_LLVM_LIT=ON")
 foreach(proj ${LLVM_ENABLE_RUNTIMES})
   set(proj_dir "${CMAKE_CURRENT_SOURCE_DIR}/../../${proj}")
+  message(NOTICE "${proj}'s proj_dir is ${proj_dir}")
   if(IS_DIRECTORY ${proj_dir} AND EXISTS ${proj_dir}/CMakeLists.txt)
     list(APPEND runtimes ${proj_dir})
   else()
     message(FATAL_ERROR "LLVM_ENABLE_RUNTIMES requests ${proj} but directory not found: ${proj_dir}")
   endif()
   string(TOUPPER "${proj}" canon_name)
   STRING(REGEX REPLACE "-" "_" canon_name ${canon_name})
   set(LLVM_EXTERNAL_${canon_name}_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../../${proj}")

 endfunction()
 
 function(builtin_register_target compiler_rt_path target)
   cmake_parse_arguments(ARG "" "" "DEPENDS" ${ARGN})
 
   check_apple_target(${target} builtin)
 
   get_cmake_property(variableNames VARIABLES)
+  #message(NOTICE "builtin variableNames ${variableNames}")
   foreach(variableName ${variableNames})
+    #message(NOTICE "builtin variableName ${variableName}")
     string(FIND "${variableName}" "BUILTINS_${target}" out)
     if("${out}" EQUAL 0)
       string(REPLACE "BUILTINS_${target}_" "" new_name ${variableName})
       string(REPLACE ";" "|" new_value "${${variableName}}")
       list(APPEND ${target}_extra_args "-D${new_name}=${new_value}")
     endif()
   endforeach()
 
+  message(NOTICE "builtin target for ${target}")
+  #message(NOTICE "cmake args ${CMAKE_ARGS}")
+  message(NOTICE "cmake common args ${COMMON_CMAKE_ARGS}")
+  message(NOTICE "extra args:")
+  message(NOTICE ${${target}_extra_args})
+
   llvm_ExternalProject_Add(builtins-${target}
                            ${compiler_rt_path}/lib/builtins
                            DEPENDS ${ARG_DEPENDS}
                            CMAKE_ARGS -DLLVM_LIBRARY_OUTPUT_INTDIR=${LLVM_LIBRARY_DIR}
                                       -DLLVM_RUNTIME_OUTPUT_INTDIR=${LLVM_TOOLS_BINARY_DIR}
                                       -DLLVM_DEFAULT_TARGET_TRIPLE=${target}
                                       -DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=ON
                                       -DCMAKE_C_COMPILER_WORKS=ON
if("default" IN_LIST LLVM_BUILTIN_TARGETS)
         DEPENDS clang-resource-headers)
       list(REMOVE_ITEM LLVM_BUILTIN_TARGETS "default")
     else()
       add_custom_target(builtins)
       add_custom_target(install-builtins)
       add_custom_target(install-builtins-stripped)
     endif()
 
+    message(NOTICE "Fuchisa Clang builtins: ${LLVM_BUILTIN_TARGETS}")
     foreach(target ${LLVM_BUILTIN_TARGETS})
       builtin_register_target(${compiler_rt_path} ${target}
         DEPENDS clang-resource-headers)
 
       add_dependencies(builtins builtins-${target})
       add_dependencies(install-builtins install-builtins-${target})
       add_dependencies(install-builtins-stripped install-builtins-${target}-stripped)
     endforeach()
if(NOT "${name}" STREQUAL "${target}")
     endforeach()
   endif()
 
   if(NOT RUNTIMES_${name}_LLVM_ENABLE_RUNTIMES AND NOT RUNTIMES_${target}_LLVM_ENABLE_RUNTIMES)
     string(REPLACE ";" "|" LLVM_ENABLE_RUNTIMES_PASSTHROUGH "${LLVM_ENABLE_RUNTIMES}")
     list(APPEND ${name}_extra_args -DLLVM_ENABLE_RUNTIMES=${LLVM_ENABLE_RUNTIMES_PASSTHROUGH})
   endif()
 
-  if(NOT RUNTIMES_${name}_LLVM_USE_LINKER AND NOT RUNTIMES_${target}_LLVM_USE_LINKER)
+  if(NOT RUNTIMES_${name}_LLVM_USE_LINKER AND NOT RUNTIMES_${target}_LLVM_USE_LINKER AND NOT ${target} STREQUAL "x86_64-pc-windows-msvc")
     list(APPEND ${name}_extra_args -DLLVM_USE_LINKER=${LLVM_USE_LINKER})
   endif()
 
+  message(NOTICE "runtime target for ${target}")
+  #message(NOTICE "cmake args ${CMAKE_ARGS}")
+  message(NOTICE "cmake common args ${COMMON_CMAKE_ARGS}")
+  message(NOTICE "extra args:")
+  message(NOTICE ${${name}_extra_args})
+
   llvm_ExternalProject_Add(runtimes-${name}
                            ${CMAKE_CURRENT_SOURCE_DIR}/../../runtimes
                            DEPENDS ${${name}_deps}
                            # Builtins were built separately above
                            CMAKE_ARGS -DCOMPILER_RT_BUILD_BUILTINS=Off
                                       -DLLVM_INCLUDE_TESTS=${LLVM_INCLUDE_TESTS}
                                       -DLLVM_DEFAULT_TARGET_TRIPLE=${target}
                                       -DLLVM_ENABLE_PROJECTS_USED=${LLVM_ENABLE_PROJECTS_USED}
else()
         foreach(component ${LLVM_RUNTIME_DISTRIBUTION_COMPONENTS})
           add_custom_target(${component})
           add_custom_target(install-${component})
           add_custom_target(install-${component}-stripped)
         endforeach()
       endif()
     endif()
 
+    message(NOTICE "Fuchisa Clang runtimes: ${LLVM_RUNTIME_TARGETS}")
     foreach(name ${LLVM_RUNTIME_TARGETS})
       if(builtins_dep)
         if (LLVM_BUILTIN_TARGETS)
           set(builtins_dep_name "${builtins_dep}-${name}")
         else()
           set(builtins_dep_name ${builtins_dep})
         endif()
       endif()