[llvm] CYGWIN: Fix build of some plugins/library/unittests

[carlo-bramini]

Summary

CYGWIN uses the same format of WIN32 for shared libraries.
As the comment says: "a shared library can't have undefined references", in this case CYGWIN must be handled like WIN32 by CMakeLists.txt, otherwise you will get several errors when linking because some symbols are undefined.
Attached patch fixes this issue and allows to complete the build process for those targets.

[mstorsjo]

LGTM

What's the preferred git author for the commit, Real Name <email@address>?

[carlo-bramini]

In D154794#4483616, @mstorsjo wrote:

LGTM

What's the preferred git author for the commit, Real Name <email@address>?

Real name: Carlo Bramini
email: [e-mail]

llvm/examples/Bye/CMakeLists.txt

 if(LLVM_BYE_LINK_INTO_TOOLS)
   message(WARNING "Setting LLVM_BYE_LINK_INTO_TOOLS=ON only makes sense for testing purpose")
 endif()
 
 # The plugin expects to not link against the Support and Core libraries,
 # but expects them to exist in the process loading the plugin. This doesn't
 # work with DLLs on Windows (where a shared library can't have undefined
 # references), so just skip this example on Windows.
-if (NOT WIN32)
+if (NOT WIN32 AND NOT CYGWIN)
   add_llvm_pass_plugin(Bye
     Bye.cpp
     DEPENDS
     intrinsics_gen
     BUILDTREE_ONLY
    )
 
   install(TARGETS ${name} RUNTIME DESTINATION "${LLVM_EXAMPLES_INSTALL_DIR}")
   set_target_properties(${name} PROPERTIES FOLDER "Examples")
 endif()

llvm/examples/IRTransforms/CMakeLists.txt

 if(LLVM_EXAMPLEIRTRANSFORMS_LINK_INTO_TOOLS)
     message(WARNING "Setting LLVM_EXAMPLEIRTRANSFORMS_LINK_INTO_TOOLS=ON only makes sense for testing purpose")
 endif()
 
 # The plugin expects to not link against the Support and Core libraries,
 # but expects them to exist in the process loading the plugin. This doesn't
 # work with DLLs on Windows (where a shared library can't have undefined
 # references), so just skip this example on Windows.
-if (NOT WIN32)
+if (NOT WIN32 AND NOT CYGWIN)
   add_llvm_pass_plugin(ExampleIRTransforms
     SimplifyCFG.cpp
     DEPENDS
     intrinsics_gen
     BUILDTREE_ONLY
     )
 
   install(TARGETS ${name} RUNTIME DESTINATION "${LLVM_EXAMPLES_INSTALL_DIR}")
   set_target_properties(${name} PROPERTIES FOLDER "Examples")
 endif()

llvm/unittests/Analysis/InlineAdvisorPlugin/CMakeLists.txt

 # The advisor plugin expects to not link against the Analysis, Support and Core 
 # libraries, but expects them to exist in the process loading the plugin. This 
 # doesn't work with DLLs on Windows (where a shared library can't have undefined
 # references), so just skip this testcase on Windows.
-if (NOT WIN32)
+if (NOT WIN32 AND NOT CYGWIN)
   unset(LLVM_LINK_COMPONENTS)
   add_llvm_library(InlineAdvisorPlugin MODULE BUILDTREE_ONLY
     InlineAdvisorPlugin.cpp
     )
   # Put PLUGIN next to the unit test executable.
   set_output_directory(InlineAdvisorPlugin
       BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_CFG_INTDIR}/../
       LIBRARY_DIR ${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_CFG_INTDIR}/../

llvm/unittests/Analysis/InlineOrderPlugin/CMakeLists.txt

 # The order plugin expects to not link against the Analysis, Support and Core 
 # libraries, but expects them to exist in the process loading the plugin. This 
 # doesn't work with DLLs on Windows (where a shared library can't have undefined
 # references), so just skip this testcase on Windows.
-if (NOT WIN32)
+if (NOT WIN32 AND NOT CYGWIN)
   unset(LLVM_LINK_COMPONENTS)
   add_llvm_library(InlineOrderPlugin MODULE BUILDTREE_ONLY
     InlineOrderPlugin.cpp
     )
   # Put PLUGIN next to the unit test executable.
   set_output_directory(InlineOrderPlugin
       BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_CFG_INTDIR}/../
       LIBRARY_DIR ${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_CFG_INTDIR}/../

llvm/unittests/Passes/Plugins/CMakeLists.txt

 # The plugin expects to not link against the Support and Core libraries,
 # but expects them to exist in the process loading the plugin. This doesn't
 # work with DLLs on Windows (where a shared library can't have undefined
 # references), so just skip this testcase on Windows.
-if (NOT WIN32)
+if (NOT WIN32 AND NOT CYGWIN)
   set(LLVM_LINK_COMPONENTS Support Passes Core AsmParser)
   add_llvm_unittest(PluginsTests
     PluginsTest.cpp
     )
   export_executable_symbols_for_plugins(PluginsTests)
   target_link_libraries(PluginsTests PRIVATE LLVMTestingSupport)
 
   unset(LLVM_LINK_COMPONENTS)
   add_subdirectory(TestPlugin)
   add_subdirectory(DoublerPlugin)
 endif()