[Polly][CMake] Allow Polly to transitively pull in its dependencies into host programs.

[Meinersbur]

Summary

Polly comes in two library flavors: One loadable module to use the LLVM framework -load mechanism, and another one that host applications can link to. These have very different requirements for Polly's own dependencies.

The loadable module assumes that all its LLVM dependencies are already available in the address space of the host application, and is not allowed to bring in its own copy of any LLVM library (including the NVPTX backend in case of Polly-ACC).

The non-module library is intended to be linked to using target_link_libraries. CMake would then resolve all of its dependencies, including NVPTX and ensure that only a single instance of each library will be used.

The patch for LLVM will be:

diff --git a/tools/bugpoint/CMakeLists.txt b/tools/bugpoint/CMakeLists.txt
index 7598657427e..0e00db4f5c4 100644
--- a/tools/bugpoint/CMakeLists.txt
+++ b/tools/bugpoint/CMakeLists.txt
@@ -16,6 +16,10 @@ set(LLVM_LINK_COMPONENTS
   Vectorize
   )

+if(WITH_POLLY AND LINK_POLLY_INTO_TOOLS)
+  list(APPEND LLVM_LINK_COMPONENTS Polly)
+endif()
+
 # Support plugins.
 set(LLVM_NO_DEAD_STRIP 1)

@@ -34,9 +38,3 @@ add_llvm_tool(bugpoint
   intrinsics_gen
   )
 export_executable_symbols(bugpoint)
-
-if(WITH_POLLY AND LINK_POLLY_INTO_TOOLS)
-  target_link_libraries(bugpoint Polly)
-  # Ensure LLVMTarget can resolve dependences in Polly.
-  target_link_libraries(bugpoint LLVMTarget)
-endif(WITH_POLLY AND LINK_POLLY_INTO_TOOLS)
diff --git a/tools/opt/CMakeLists.txt b/tools/opt/CMakeLists.txt
index 518396e3602..8fb95ef7483 100644
--- a/tools/opt/CMakeLists.txt
+++ b/tools/opt/CMakeLists.txt
@@ -19,6 +19,10 @@ set(LLVM_LINK_COMPONENTS
   Passes
   )

+if(WITH_POLLY AND LINK_POLLY_INTO_TOOLS)
+  list(APPEND LLVM_LINK_COMPONENTS Polly)
+endif()
+
 # Support plugins.
 set(LLVM_NO_DEAD_STRIP 1)

@@ -35,7 +39,3 @@ add_llvm_tool(opt
   intrinsics_gen
   )
 export_executable_symbols(opt)
-
-if(WITH_POLLY AND LINK_POLLY_INTO_TOOLS)
-  target_link_libraries(opt Polly)
-endif(WITH_POLLY AND LINK_POLLY_INTO_TOOLS)

The patch for clang will be:

diff --git a/tools/driver/CMakeLists.txt b/tools/driver/CMakeLists.txt
index 901b6d62e4..38bb34df79 100644
--- a/tools/driver/CMakeLists.txt
+++ b/tools/driver/CMakeLists.txt
@@ -16,6 +16,10 @@ set( LLVM_LINK_COMPONENTS
   Vectorize
   )

+if(WITH_POLLY AND LINK_POLLY_INTO_TOOLS)
+  list(APPEND LLVM_LINK_COMPONENTS Polly)
+endif()
+
 option(CLANG_PLUGIN_SUPPORT "Build clang with plugin support" ON)

 # Support plugins. This must be before add_clang_executable as it reads
@@ -125,7 +129,3 @@ if(CLANG_ORDER_FILE AND (LD64_EXECUTABLE OR GOLD_EXECUTABLE))
     set_target_properties(clang PROPERTIES LINK_DEPENDS ${CLANG_ORDER_FILE})
   endif()
 endif()
-
-if(WITH_POLLY AND LINK_POLLY_INTO_TOOLS)
-  target_link_libraries(clang Polly)
-endif(WITH_POLLY AND LINK_POLLY_INTO_TOOLS)

This patch uses LLVM's add_llvm_library, which is convenient because it handles all requirements and ensures consistency with LLVM, but also has other effects:

• Polly becomes part of libLLVM.so in case of LLVM_BUILD_LLVM_DYLIB=ON, even without LLVM_POLLY_LINK_INTO_TOOLS. This behavior could be avoided if we implement another option in add_llvm_library.
  • The LLVM component system expects its component's names to begin with "LLVM". For this reason the targets "LLVMPolly" and "Polly" swap their meanings. This could be confusing to downstream users.

• The non-module Polly library is not available in out-of-LLVM-tree builds. This is no loss for Polly itself since it uses it only for LLVM_POLLY_LINK_INTO_TOOLS=ON, but maybe there are downstream users. llvm-config doesn't deliver enough information to get its dependency relations right anyway. Maybe importing the LLVMConfig.cmake would.

[grosser]

Hi Michael,

this seems to be a nice cmake cleanup now finally adding Polly with the right native cmake tools. I think it is OK to have Polly as part of libLLVM.so, as this is only the case if Polly is actually checked out. I also think it is OK to expose the core library not to external users. It is hard to guess which build artifacts they might need, if we neither know about their existence nor about their use cases. I personally would guess there are none, but if there are I am sure they will let us know when we break them. In this case we can always try to address their use case.

Best,
Tobias

[Meinersbur]

With having invested some extra effort, D32392 seems to work better. Other opinions?

[Meinersbur]

Abandoned in favor of D32442

cmake/CMakeLists.txt

 # Keep this in sync with llvm/cmake/CMakeLists.txt!
 if (LLVM_INSTALL_ROOT)
   # this simplifies things down the road, by not requiring to distinguish
   # between in-tree and out of tree builds
   set(LLVM_BINARY_DIR ${LLVM_INSTALL_ROOT})
 endif()
 
 set(LLVM_INSTALL_PACKAGE_DIR "lib${LLVM_LIBDIR_SUFFIX}/cmake/llvm")
 set(POLLY_INSTALL_PACKAGE_DIR "lib${LLVM_LIBDIR_SUFFIX}/cmake/polly")
 if (CMAKE_CONFIGURATION_TYPES)
   set(POLLY_EXPORTS_FILE_NAME "PollyExports-$<LOWER_CASE:$<CONFIG>>.cmake")
 else()
   # avoid conflicts in the build-tree when changing configuration
   set(POLLY_EXPORTS_FILE_NAME "PollyExports-all.cmake")
 endif()
 
-set(POLLY_CONFIG_EXPORTED_TARGETS Polly ${ISL_TARGET})
-if (NOT MSVC)
-  # LLVMPolly is a dummy target on Win
+set(POLLY_CONFIG_EXPORTED_TARGETS ${ISL_TARGET})
+if (DEFINED LLVM_MAIN_SRC_DIR)
   list(APPEND POLLY_CONFIG_EXPORTED_TARGETS LLVMPolly)
-endif()
+endif ()
+if (NOT MSVC)
+  # Polly is a dummy target on Win
+  list(APPEND POLLY_CONFIG_EXPORTED_TARGETS Polly)
+endif()
 if (POLLY_ENABLE_GPGPU_CODEGEN)
   list(APPEND POLLY_CONFIG_EXPORTED_TARGETS PollyPPCG)
 endif()
 
 # Get the target type for every exported target
 foreach(tgt IN LISTS POLLY_CONFIG_EXPORTED_TARGETS)
   get_target_property(tgt_type ${tgt} TYPE)
   string(REPLACE "_LIBRARY" "" tgt_type ${tgt_type})

lib/CMakeLists.txt

 # Compile ISL into a separate library.
 add_subdirectory(External)
 
 set(POLLY_HEADER_FILES)
 if (MSVC_IDE OR XCODE)
   file(GLOB_RECURSE POLLY_HEADER_FILES "${POLLY_SOURCE_DIR}/include/polly/*.h")
 endif ()
 
-add_polly_library(Polly
+add_library(PollyCore OBJECT
   Analysis/DependenceInfo.cpp
   Analysis/PolyhedralInfo.cpp
   Analysis/ScopDetection.cpp
   Analysis/ScopDetectionDiagnostic.cpp
   Analysis/ScopInfo.cpp
   Analysis/ScopBuilder.cpp
   Analysis/ScopGraphPrinter.cpp
   Analysis/ScopPass.cpp
add_library(PollyCore OBJECT
   Transform/CodePreparation.cpp
   Transform/DeadCodeElimination.cpp
   Transform/ScheduleOptimizer.cpp
   Transform/FlattenSchedule.cpp
   Transform/FlattenAlgo.cpp
   Transform/DeLICM.cpp
   Transform/Simplify.cpp
   ${POLLY_HEADER_FILES}
-  )
 
-if (GPU_CODEGEN)
-  target_link_libraries(Polly PollyPPCG)
-endif (GPU_CODEGEN)
-
-target_link_libraries(Polly ${ISL_TARGET})
-
-if (BUILD_SHARED_LIBS)
-  target_link_libraries(Polly
-    LLVMSupport
-    LLVMCore
-    LLVMScalarOpts
-    LLVMInstCombine
-    LLVMTransformUtils
-    LLVMAnalysis
-    LLVMipo
-    LLVMMC
+# Create the library that can be linked into LLVM's tools and Polly's unittests.
+# It depends on all library it needs, such that with
+# LLVM_POLLY_LINK_INTO_TOOLS=ON, its dependencies like PollyISL are linked as
+# well.
+# The library name must be prefixed with "LLVM" to be allowed to be used in
+# LLVM_LINK_COMPONENTS.
+# It is only useful when building inside the LLVM source tree and
+# LLVM_POLLY_LINK_INTO_TOOLS=ON, in all other cases the loadable module has to
+# be used. We still create it in case of LLVM_POLLY_LINK_INTO_TOOLS=OFF such
+# that unittests can still link against it.
+if (DEFINED LLVM_MAIN_SRC_DIR)
+  set(required_components
+    Support
+    Core
+    ScalarOpts
+    InstCombine
+    TransformUtils
+    Analysis
+    ipo
+    MC
   # The libraries below are required for darwin: http://PR26392
-    LLVMBitReader
-    LLVMMCParser
-    LLVMObject
-    LLVMProfileData
-    LLVMTarget
-    LLVMVectorize
-  )
-  link_directories(
-    ${LLVM_LIBRARY_DIR}
-  )
-elseif (LLVM_LINK_LLVM_DYLIB)
-  target_link_libraries(Polly
-    LLVM
+    BitReader
+    MCParser
+    Object
+    ProfileData
+    Target
+    Vectorize
   )
-  link_directories(
-    ${LLVM_LIBRARY_DIR}
+  set(required_libs ${ISL_TARGET})
+  if (GPU_CODEGEN)
+    list(APPEND required_components NVPTX)
+    list(APPEND required_libs PollyPPCG)
+  endif ()
+  
+  # Using add_llvm_library also has the effect of Polly becoming part of
+  # libLLVM.so if LLVM_BUILD_LLVM_DYLIB=ON. The LLVM_LINK_COMPONENTS mechanism
+  # will take care for Polly not being linked in multiple times, since there
+  # might already be a copy of Polly in libLLVM.so.
+  add_llvm_library(LLVMPolly
+    OBJLIBS $<TARGET_OBJECTS:PollyCore>
+    LINK_COMPONENTS ${required_components} 
+    DEPENDS intrinsics_gen
   )
-endif()
+
+  # We cannot use the LINK_LIBS parameter of add_llvm_library for these because
+  # it calls target_link_libraries with the PRIVATE option.
+  target_link_libraries(LLVMPolly PUBLIC ${required_libs})
+endif ()
 
-# Build a monolithic Polly.a and a thin module LLVMPolly.moduleext that links to
-# that static library.
+# Create a loadable module Polly.so that can be loaded using
+# LLVM's/clang's "-load" option.
 if (MSVC)
   # Add dummy target, because loadable modules are not supported on Windows
-  add_custom_target(LLVMPolly)
-  set_target_properties(LLVMPolly PROPERTIES FOLDER "Polly")
+  add_custom_target(Polly)
+  set_target_properties(Polly PROPERTIES FOLDER "Polly")
 else ()
-  add_polly_loadable_module(LLVMPolly
+  add_polly_loadable_module(Polly
     Polly.cpp
+    $<TARGET_OBJECTS:PollyCore>
   )
 
-  target_link_libraries(LLVMPolly Polly)
+  # Only add the dependencies that are not part of LLVM. The latter are assumed
+  # to be already available in the address space the module is loaded into.
+  # Adding them once more would have the effect that both copies try to register
+  # the same command line options, to which LLVM reacts with an error. 
+  # If Polly-ACC is enabled, the NVPTX target is also expected to reside in the
+  # hosts. This is not the case for bugpoint. Use LLVM_POLLY_LINK_INTO_TOOLS=ON
+  # instead which will automatically resolve the additional dependencies by
+  # Polly.
+  target_link_libraries(Polly ${ISL_TARGET})
+  if (GPU_CODEGEN)
+    target_link_libraries(Polly PollyPPCG)
+  endif ()
 
-  set_target_properties(LLVMPolly
+  set_target_properties(Polly
     PROPERTIES
     LINKER_LANGUAGE CXX
     PREFIX "")
 endif ()
-
-if (TARGET intrinsics_gen)
-  # Check if we are building as part of an LLVM build
-  add_dependencies(Polly intrinsics_gen)
-endif()
-

test/CMakeLists.txt

 set_target_properties(check-polly PROPERTIES FOLDER "Polly")
 
 if (NOT DEFINED LLVM_MAIN_SRC_DIR)
 
   # We are building polly out of tree, adjust the settings.
   # FIXME: FileCheck is not available in llvm install directory at the moment.
   set(LLVM_LIT ${LLVM_INSTALL_ROOT}/bin/llvm-lit)
   if (POLLY_BUNDLED_ISL)
-    set(POLLY_TEST_DEPS LLVMPolly polly-isl-test)
+    set(POLLY_TEST_DEPS Polly polly-isl-test)
   endif (POLLY_BUNDLED_ISL)
   if (POLLY_GTEST_AVAIL)
     list(APPEND POLLY_TEST_DEPS PollyUnitTests)
   endif ()
 
   set(LLVM_BINARY_DIR "${LLVM_INSTALL_ROOT}")
   set(LLVM_TOOLS_DIR "${LLVM_INSTALL_ROOT}/bin")
   set(LLVM_LIBS_DIR "${LLVM_INSTALL_ROOT}/lib")
if (POLLY_BUNDLED_ISL)
                   COMMENT "Running isl unit tests")
       set_target_properties(check-polly-isl PROPERTIES FOLDER "Polly")
     endif (POLLY_BUNDLED_ISL)
   endif()
 
 else (NOT DEFINED LLVM_MAIN_SRC_DIR)
 
   set(LLVM_LIT ${LLVM_TOOLS_BINARY_DIR}/llvm-lit)
-  set(POLLY_TEST_DEPS llvm-config opt LLVMPolly FileCheck not)
+  set(POLLY_TEST_DEPS llvm-config opt Polly FileCheck not)
   if (POLLY_BUNDLED_ISL)
     list(APPEND POLLY_TEST_DEPS polly-isl-test)
   endif()
   if (POLLY_GTEST_AVAIL)
     list(APPEND POLLY_TEST_DEPS PollyUnitTests)
   endif ()
 
   set(LLVM_BINARY_DIR "${LLVM_BINARY_DIR}")

test/lit.site.cfg.in

if config.link_polly_into_tools == '' or \
    config.link_polly_into_tools.lower() == '0' or \
    config.link_polly_into_tools.lower() == 'n' or \
    config.link_polly_into_tools.lower() == 'no' or \
    config.link_polly_into_tools.lower() == 'off' or \
    config.link_polly_into_tools.lower() == 'false' or \
    config.link_polly_into_tools.lower() == 'notfound' or \
    config.link_polly_into_tools.lower() == 'link_polly_into_tools-notfound':
     config.substitutions.append(('%loadPolly', '-load '
-                                 + config.polly_lib_dir + '/LLVMPolly@LLVM_SHLIBEXT@'
+                                 + config.polly_lib_dir + '/Polly@LLVM_SHLIBEXT@'
                                  + ' -polly-process-unprofitable '
                                  + ' -polly-remarks-minimal '
                                  ))
 else:
     config.substitutions.append(('%loadPolly', ''
                                  + ' -polly-process-unprofitable '
                                  + ' -polly-remarks-minimal '
                                  ))
 
 if config.enable_gpgpu_codegen == 'TRUE' :
     config.available_features.add('pollyacc')
 
 # Let the main config do the real work.
 lit_config.load_config(config, "@POLLY_SOURCE_DIR@/test/lit.cfg")

unittests/CMakeLists.txt

 add_custom_target(PollyUnitTests)
 set_target_properties(PollyUnitTests PROPERTIES FOLDER "Polly")
 
 # add_polly_unittest(test_dirname file1.cpp file2.cpp)
 #
 # Will compile the list of files together and link against Polly and its dependences.
 function(add_polly_unittest test_name)
   if(COMMAND add_unittest)
+    set(LLVM_LINK_COMPONENTS Polly)
     add_unittest(PollyUnitTests ${test_name} ${ARGN})
-    target_link_libraries(${test_name} Polly)
-
-    # The Polly target does not depend on its required libraries, except:
-    # - BUILD_SHARED_LIBS=ON
-    #     in which case calling target_link_libraries again is redundant.
-    # - LLVM_LINK_LLVM_DYLIB=ON
-    #     in which case it depends on libLLVM.so, so no additional libs needed.
-    #     We are also not allowed to link against the plain LLVM* libraries,
-    #     which would result in multiple instances of these to be loaded.
-    if (NOT LLVM_LINK_LLVM_DYLIB)
-      target_link_libraries(${test_name} LLVMCore LLVMSupport LLVMDemangle LLVMipo)
-    endif ()
   else()
-    add_executable(${test_name} EXCLUDE_FROM_ALL ${ARGN})
+    add_executable(${test_name} EXCLUDE_FROM_ALL $<TARGET_OBJECTS:PollyCore> ${ARGN})
     set_target_properties(${test_name} PROPERTIES RUNTIME_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
 
-    target_link_libraries(${test_name} gtest_main gtest Polly ${LLVM_LIBS})
+    target_link_libraries(${test_name} gtest_main gtest ${LLVM_LIBS} ${ISL_TARGET})
+    if (GPU_CODEGEN)
+      target_link_libraries(${test_name} PollyPPCG)
+    endif ()
     add_dependencies(PollyUnitTests ${test_name})
 
     set_property(TARGET ${test_name} PROPERTY FOLDER "Polly")
   endif()
 endfunction()
 
 add_subdirectory(Isl)
 add_subdirectory(Flatten)
 add_subdirectory(DeLICM)