[runtimes] Allow overriding where CMake installs RUNTIME type libraries (DLLs)

[mstorsjo]

Summary

Currently this is hardcoded to the directory 'bin' under the
install prefix, but when doing per-target runtime builds, all
of these would end up in the same bin directory (where that bin
directory is for the native compiler itself, not for cross target
executables).

Default to bin/${LLVM_DEFAULT_TARGET_TRIPLE}, and let the user
override it.

For existing per-target runtime configurations on Windows, this
does change where the output binaries are placed (but before,
one couldn't use it for more than one target at a time anyway
as the build products would clobber each other).

[compnerd]

Why not just use CMAKE_RUNTIME_OUTPUT_DIRECTORY to initialize the value?

[mstorsjo]

In D107892#2950876, @compnerd wrote:

Why not just use CMAKE_RUNTIME_OUTPUT_DIRECTORY to initialize the value?

You mean instead of the e.g. set(LIBUNWIND_INSTALL_RUNTIME_DIR bin ... and set(LIBUNWIND_INSTALL_RUNTIME_DIR bin/${LLVM_DEFAULT_TARGET_TRIPLE} ... statements - making them e.g. set(LIBUNWIND_INSTALL_RUNTIME_DIR ${CMAKE_RUNTIME_OUTPUT_DIRECTORY} ...? By default CMAKE_RUNTIME_OUTPUT_DIRECTORY is unset it seems; such a setup makes the DLLs not be installed at all unless the user sets CMAKE_RUNTIME_OUTPUT_DIRECTORY.

Our own cmake code initializes CMAKE_RUNTIME_OUTPUT_DIRECTORY right below - so in libunwind/libcxxabi/libcxx, CMAKE_RUNTIME_OUTPUT_DIRECTORY, CMAKE_ARCHIVE_OUTPUT_DIRECTORY and CMAKE_LIBRARY_OUTPUT_DIRECTORY aren't anything you can set as an end-user to influence where things are installed (as they're overwritten unconditionally), but the end user should set e.g. LIBUNWIND_INSTALL_LIBRARY_DIR instead.

[mstorsjo]

@ldionne - This one is a bit simpler as it's not about any specific less-supported way of building the library, but just adding similar configurability for this part of the installed RUNTIME files as already exists for files in the LIBRARY category.

[mstorsjo]

@ldionne Ping

[compnerd]

I really would prefer to avoid adding bin/<TRIPLE> to the default installation path. This doesn't match the defaults for most platforms (e.g. exherbo uses /usr/<triple>/bin - which would be a default value of ${LLVM_DEFAULT_TARGET_TRIPLE}/bin. On Windows, it seems that bin, bin64, bin64a is the style that Microsoft uses. Having to have different defaults seems unfortunate. Defaulting to bin and letting the user override it seems reasonable to me.

[mstorsjo]

Defaulting to bin and letting the user override it seems reasonable to me.

Fair enough, we can leave that default at bin, as long as it’s settable.

[phosek]

If we still need this, then I'd prefer ${LLVM_DEFAULT_TARGET_TRIPLE}/bin following https://wiki.debian.org/Multiarch/LibraryPathOverview.

[mstorsjo]

Keep the default target dir as 'bin' for per-target runtimes build too.

[phosek]

LGTM

[mstorsjo]

In D107892#2989709, @phosek wrote:

If we still need this, then I'd prefer ${LLVM_DEFAULT_TARGET_TRIPLE}/bin following https://wiki.debian.org/Multiarch/LibraryPathOverview.

Well, this path is only ever used for windows builds - but yeah, that pattern, <triple>/bin is what I use for mingw things in general too.

But isn’t that a bit inconsistent when the other per-target files are installed into lib/<triple> and include/<triple>?

[compnerd]

As to the comment on the consistency - there are a number of different layouts that are inconsistent with each other :-(. This is messy, and therefore forcing the user to specify the paths seems like a good compromise.

[phosek]

In D107892#2989781, @mstorsjo wrote:

In D107892#2989709, @phosek wrote:

If we still need this, then I'd prefer ${LLVM_DEFAULT_TARGET_TRIPLE}/bin following https://wiki.debian.org/Multiarch/LibraryPathOverview.

Well, this path is only ever used for windows builds - but yeah, that pattern, <triple>/bin is what I use for mingw things in general too.

But isn’t that a bit inconsistent when the other per-target files are installed into lib/<triple> and include/<triple>?

AFAIK the reason why these are different is that if your binary foo uses dynamic linking, then the shared libraries for <triple>/bin/foo would be in <triple>/lib which is different from lib/<triple> which contains libraries used when targeting <triple>.

[phosek]

In D107892#2989982, @phosek wrote:

In D107892#2989781, @mstorsjo wrote:

In D107892#2989709, @phosek wrote:

If we still need this, then I'd prefer ${LLVM_DEFAULT_TARGET_TRIPLE}/bin following https://wiki.debian.org/Multiarch/LibraryPathOverview.

Well, this path is only ever used for windows builds - but yeah, that pattern, <triple>/bin is what I use for mingw things in general too.

But isn’t that a bit inconsistent when the other per-target files are installed into lib/<triple> and include/<triple>?

AFAIK the reason why these are different is that if your binary foo uses dynamic linking, then the shared libraries for <triple>/bin/foo would be in <triple>/lib which is different from lib/<triple> which contains libraries used when targeting <triple>.

To give a more practical albeit contrived example, you could end up with this:

x86_64-linux-gnu/
  bin/
    clang
  lib/
    libz.so
aarch86_64-linux-gnu/
  bin/
    clang
  lib/
    libz.so
include/
  ...
  riscv64-linux-gnu/
    ...
lib/
  riscv64-linux-gnu/
    libc++.a

libcxx/CMakeLists.txt

 # TODO: Projects that depend on libc++ should use LIBCXX_GENERATED_INCLUDE_DIR
 # instead of hard-coding include/c++/v1.
 if(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT APPLE)
   set(LIBCXX_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR}/${LLVM_DEFAULT_TARGET_TRIPLE})
   set(LIBCXX_GENERATED_INCLUDE_DIR "${LLVM_BINARY_DIR}/include/c++/v1")
   set(LIBCXX_GENERATED_INCLUDE_TARGET_DIR "${LLVM_BINARY_DIR}/include/${LLVM_DEFAULT_TARGET_TRIPLE}/c++/v1")
   set(LIBCXX_INSTALL_LIBRARY_DIR lib${LLVM_LIBDIR_SUFFIX}/${LLVM_DEFAULT_TARGET_TRIPLE} CACHE PATH
       "Path where built libc++ libraries should be installed.")
+  set(LIBCXX_INSTALL_RUNTIME_DIR bin CACHE PATH
+      "Path where built libc++ runtime libraries should be installed.")
   set(LIBCXX_INSTALL_INCLUDE_DIR "include/c++/v1" CACHE PATH
       "Path where target-agnostic libc++ headers should be installed.")
   set(LIBCXX_INSTALL_INCLUDE_TARGET_DIR "include/${LLVM_DEFAULT_TARGET_TRIPLE}/c++/v1" CACHE PATH
       "Path where target-specific libc++ headers should be installed.")
   if(LIBCXX_LIBDIR_SUBDIR)
     string(APPEND LIBCXX_LIBRARY_DIR /${LIBCXX_LIBDIR_SUBDIR})
     string(APPEND LIBCXX_INSTALL_LIBRARY_DIR /${LIBCXX_LIBDIR_SUBDIR})
   endif()
 elseif(LLVM_LIBRARY_OUTPUT_INTDIR)
   set(LIBCXX_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR})
   set(LIBCXX_GENERATED_INCLUDE_DIR "${LLVM_BINARY_DIR}/include/c++/v1")
   set(LIBCXX_GENERATED_INCLUDE_TARGET_DIR "${LIBCXX_GENERATED_INCLUDE_DIR}")
   set(LIBCXX_INSTALL_LIBRARY_DIR lib${LIBCXX_LIBDIR_SUFFIX} CACHE PATH
       "Path where built libc++ libraries should be installed.")
+  set(LIBCXX_INSTALL_RUNTIME_DIR bin CACHE PATH
+      "Path where built libc++ runtime libraries should be installed.")
   set(LIBCXX_INSTALL_INCLUDE_DIR "include/c++/v1" CACHE PATH
       "Path where target-agnostic libc++ headers should be installed.")
   set(LIBCXX_INSTALL_INCLUDE_TARGET_DIR "${LIBCXX_INSTALL_INCLUDE_DIR}" CACHE PATH
       "Path where target-specific libc++ headers should be installed.")
 else()
   set(LIBCXX_LIBRARY_DIR ${CMAKE_BINARY_DIR}/lib${LIBCXX_LIBDIR_SUFFIX})
   set(LIBCXX_GENERATED_INCLUDE_DIR "${CMAKE_BINARY_DIR}/include/c++/v1")
   set(LIBCXX_GENERATED_INCLUDE_TARGET_DIR "${LIBCXX_GENERATED_INCLUDE_DIR}")
   set(LIBCXX_INSTALL_LIBRARY_DIR lib${LIBCXX_LIBDIR_SUFFIX} CACHE PATH
       "Path where built libc++ libraries should be installed.")
+  set(LIBCXX_INSTALL_RUNTIME_DIR bin CACHE PATH
+      "Path where built libc++ runtime libraries should be installed.")
   set(LIBCXX_INSTALL_INCLUDE_DIR "include/c++/v1" CACHE PATH
       "Path where target-agnostic libc++ headers should be installed.")
   set(LIBCXX_INSTALL_INCLUDE_TARGET_DIR "${LIBCXX_INSTALL_INCLUDE_DIR}" CACHE PATH
       "Path where target-specific libc++ headers should be installed.")
 endif()
 
 file(MAKE_DIRECTORY "${LIBCXX_BINARY_INCLUDE_DIR}")
 

libcxx/src/CMakeLists.txt

if (LIBCXX_BUILD_EXTERNAL_THREAD_LIBRARY)
 
   target_link_libraries(cxx_external_threads PRIVATE cxx-headers)
 endif()
 
 if (LIBCXX_INSTALL_SHARED_LIBRARY)
   install(TARGETS cxx_shared
     ARCHIVE DESTINATION ${LIBCXX_INSTALL_LIBRARY_DIR} COMPONENT cxx
     LIBRARY DESTINATION ${LIBCXX_INSTALL_LIBRARY_DIR} COMPONENT cxx
-    RUNTIME DESTINATION bin COMPONENT cxx)
+    RUNTIME DESTINATION ${LIBCXX_INSTALL_RUNTIME_DIR} COMPONENT cxx)
 endif()
 
 if (LIBCXX_INSTALL_STATIC_LIBRARY)
   install(TARGETS cxx_static
     ARCHIVE DESTINATION ${LIBCXX_INSTALL_LIBRARY_DIR} COMPONENT cxx
     LIBRARY DESTINATION ${LIBCXX_INSTALL_LIBRARY_DIR} COMPONENT cxx
-    RUNTIME DESTINATION bin COMPONENT cxx)
+    RUNTIME DESTINATION ${LIBCXX_INSTALL_RUNTIME_DIR} COMPONENT cxx)
 endif()
 
 if(LIBCXX_INSTALL_EXPERIMENTAL_LIBRARY)
   install(TARGETS cxx_experimental
     LIBRARY DESTINATION ${LIBCXX_INSTALL_LIBRARY_DIR} COMPONENT cxx
     ARCHIVE DESTINATION ${LIBCXX_INSTALL_LIBRARY_DIR} COMPONENT cxx
-    RUNTIME DESTINATION bin COMPONENT cxx)
+    RUNTIME DESTINATION ${LIBCXX_INSTALL_RUNTIME_DIR} COMPONENT cxx)
 endif()
 
 # NOTE: This install command must go after the cxx install command otherwise
 # it will not be executed after the library symlinks are installed.
 if (LIBCXX_ENABLE_SHARED AND LIBCXX_ENABLE_ABI_LINKER_SCRIPT)
   install(FILES "$<TARGET_LINKER_FILE:cxx_shared>"
     DESTINATION ${LIBCXX_INSTALL_LIBRARY_DIR}
     COMPONENT libcxx)

libcxxabi/CMakeLists.txt

set(CMAKE_MODULE_PATH
   ${CMAKE_MODULE_PATH}
   )
 
 if(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT APPLE)
   set(LIBCXXABI_HEADER_DIR ${LLVM_BINARY_DIR})
   set(LIBCXXABI_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR}/${LLVM_DEFAULT_TARGET_TRIPLE})
   set(LIBCXXABI_INSTALL_LIBRARY_DIR lib${LLVM_LIBDIR_SUFFIX}/${LLVM_DEFAULT_TARGET_TRIPLE} CACHE PATH
       "Path where built libc++abi libraries should be installed.")
+  set(LIBCXXABI_INSTALL_RUNTIME_DIR bin CACHE PATH
+      "Path where built libc++abi runtime libraries should be installed.")
   if(LIBCXX_LIBDIR_SUBDIR)
     string(APPEND LIBCXXABI_LIBRARY_DIR /${LIBCXXABI_LIBDIR_SUBDIR})
     string(APPEND LIBCXXABI_INSTALL_LIBRARY_DIR /${LIBCXXABI_LIBDIR_SUBDIR})
   endif()
 elseif(LLVM_LIBRARY_OUTPUT_INTDIR)
   set(LIBCXXABI_HEADER_DIR ${LLVM_BINARY_DIR})
   set(LIBCXXABI_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR})
   set(LIBCXXABI_INSTALL_LIBRARY_DIR lib${LIBCXXABI_LIBDIR_SUFFIX} CACHE PATH
       "Path where built libc++abi libraries should be installed.")
+  set(LIBCXXABI_INSTALL_RUNTIME_DIR bin CACHE PATH
+      "Path where built libc++abi runtime libraries should be installed.")
 else()
   set(LIBCXXABI_HEADER_DIR ${CMAKE_BINARY_DIR})
   set(LIBCXXABI_LIBRARY_DIR ${CMAKE_BINARY_DIR}/lib${LIBCXXABI_LIBDIR_SUFFIX})
   set(LIBCXXABI_INSTALL_LIBRARY_DIR lib${LIBCXXABI_LIBDIR_SUFFIX} CACHE PATH
       "Path where built libc++abi libraries should be installed.")
+  set(LIBCXXABI_INSTALL_RUNTIME_DIR bin CACHE PATH
+      "Path where built libc++abi runtime libraries should be installed.")
 endif()
 
 set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${LIBCXXABI_LIBRARY_DIR})
 set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${LIBCXXABI_LIBRARY_DIR})
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${LIBCXXABI_LIBRARY_DIR})
 
 # By default, for non-standalone builds, libcxx and libcxxabi share a library
 # directory.

libcxxabi/src/CMakeLists.txt

 
 # Add a meta-target for both libraries.
 add_custom_target(cxxabi DEPENDS ${LIBCXXABI_BUILD_TARGETS})
 
 if (LIBCXXABI_INSTALL_LIBRARY)
   install(TARGETS ${LIBCXXABI_INSTALL_TARGETS}
     LIBRARY DESTINATION ${LIBCXXABI_INSTALL_LIBRARY_DIR} COMPONENT cxxabi
     ARCHIVE DESTINATION ${LIBCXXABI_INSTALL_LIBRARY_DIR} COMPONENT cxxabi
+    RUNTIME DESTINATION ${LIBCXXABI_INSTALL_RUNTIME_DIR} COMPONENT cxxabi
     )
 endif()
 
 if (NOT CMAKE_CONFIGURATION_TYPES AND LIBCXXABI_INSTALL_LIBRARY)
   add_custom_target(install-cxxabi
     DEPENDS cxxabi
     COMMAND "${CMAKE_COMMAND}"
             -DCMAKE_INSTALL_COMPONENT=cxxabi
             -P "${LIBCXXABI_BINARY_DIR}/cmake_install.cmake")
   add_custom_target(install-cxxabi-stripped
     DEPENDS cxxabi
     COMMAND "${CMAKE_COMMAND}"
             -DCMAKE_INSTALL_COMPONENT=cxxabi
             -DCMAKE_INSTALL_DO_STRIP=1
             -P "${LIBCXXABI_BINARY_DIR}/cmake_install.cmake")
 endif()

libunwind/CMakeLists.txt

 set(CMAKE_MODULE_PATH
     "${CMAKE_CURRENT_SOURCE_DIR}/cmake"
     ${CMAKE_MODULE_PATH})
 
 if(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT APPLE)
   set(LIBUNWIND_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR}/${LLVM_DEFAULT_TARGET_TRIPLE})
   set(LIBUNWIND_INSTALL_LIBRARY_DIR lib${LLVM_LIBDIR_SUFFIX}/${LLVM_DEFAULT_TARGET_TRIPLE} CACHE PATH
       "Path where built libunwind libraries should be installed.")
+  set(LIBUNWIND_INSTALL_RUNTIME_DIR bin CACHE PATH
+      "Path where built libunwind runtime libraries should be installed.")
   if(LIBCXX_LIBDIR_SUBDIR)
     string(APPEND LIBUNWIND_LIBRARY_DIR /${LIBUNWIND_LIBDIR_SUBDIR})
     string(APPEND LIBUNWIND_INSTALL_LIBRARY_DIR /${LIBUNWIND_LIBDIR_SUBDIR})
   endif()
 elseif(LLVM_LIBRARY_OUTPUT_INTDIR)
   set(LIBUNWIND_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR})
   set(LIBUNWIND_INSTALL_LIBRARY_DIR lib${LIBUNWIND_LIBDIR_SUFFIX} CACHE PATH
       "Path where built libunwind libraries should be installed.")
+  set(LIBUNWIND_INSTALL_RUNTIME_DIR bin CACHE PATH
+      "Path where built libunwind runtime libraries should be installed.")
 else()
   set(LIBUNWIND_LIBRARY_DIR ${CMAKE_BINARY_DIR}/lib${LIBUNWIND_LIBDIR_SUFFIX})
   set(LIBUNWIND_INSTALL_LIBRARY_DIR lib${LIBUNWIND_LIBDIR_SUFFIX} CACHE PATH
       "Path where built libunwind libraries should be installed.")
+  set(LIBUNWIND_INSTALL_RUNTIME_DIR bin CACHE PATH
+      "Path where built libunwind runtime libraries should be installed.")
 endif()
 
 set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${LIBUNWIND_LIBRARY_DIR})
 set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${LIBUNWIND_LIBRARY_DIR})
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${LIBUNWIND_LIBRARY_DIR})
 
 set(LIBUNWIND_C_FLAGS "")
 set(LIBUNWIND_CXX_FLAGS "")

libunwind/src/CMakeLists.txt

 
 # Add a meta-target for both libraries.
 add_custom_target(unwind DEPENDS ${LIBUNWIND_BUILD_TARGETS})
 
 if (LIBUNWIND_INSTALL_LIBRARY)
   install(TARGETS ${LIBUNWIND_INSTALL_TARGETS}
     LIBRARY DESTINATION ${LIBUNWIND_INSTALL_LIBRARY_DIR} COMPONENT unwind
     ARCHIVE DESTINATION ${LIBUNWIND_INSTALL_LIBRARY_DIR} COMPONENT unwind
-    RUNTIME DESTINATION bin COMPONENT unwind)
+    RUNTIME DESTINATION ${LIBUNWIND_INSTALL_RUNTIME_DIR} COMPONENT unwind)
 endif()
 
 if (NOT CMAKE_CONFIGURATION_TYPES AND LIBUNWIND_INSTALL_LIBRARY)
   add_custom_target(install-unwind
     DEPENDS unwind
     COMMAND "${CMAKE_COMMAND}"
             -DCMAKE_INSTALL_COMPONENT=unwind
             -P "${LIBUNWIND_BINARY_DIR}/cmake_install.cmake")
   add_custom_target(install-unwind-stripped
     DEPENDS unwind
     COMMAND "${CMAKE_COMMAND}"
             -DCMAKE_INSTALL_COMPONENT=unwind
             -DCMAKE_INSTALL_DO_STRIP=1
             -P "${LIBUNWIND_BINARY_DIR}/cmake_install.cmake")
 endif()