Enable linking tools, shared libraries against libLLVM

[axw]

Summary

Three closely related changes, to have a mode in which we link all
executables and shared libraries against libLLVM.

1. Add a new LLVM_LINK_LLVM_DYLIB cmake option, which, when ON, will link executables and shared libraries against libLLVM. For this to work, it is necessary to also set LLVM_BUILD_LLVM_DYLIB and LLVM_DYLIB_EXPORT_ALL.
   
   It is not strictly necessary to set LLVM_DISABLE_LLVM_DYLIB_ATEXIT, but we also default to OFF in this mode, or tools tend to misbehave (e.g. stdout may not flush on exit when output is buffered.)
   
   llvm-config and Tablegen do not use libLLVM, as they are dependencies of libLLVM.

2. Modify llvm-go to take a new flag, "linkmode=component-libs|dylib". Depending on which one is passed (default is component-libs), we link with the individual libraries or libLLVM respectively. We pass in dylib when LLVM_LINK_LLVM_DYLIB is ON.

3. Fix LLVM_DYLIB_EXPORT_ALL on Linux, and expand the symbols exported to actually export all. Don't strip leading underscore from symbols on Linux, and make sure we get all exported symbols and weak-with-default symbols ("W" in nm output). Without these changes, passes won't load because the "Annotate..." symbols defined in lib/Support/Valigrind.cpp are not found.

Testing:

• Ran default build ("ninja") with LLVM, clang, compiler-rt, llgo, lldb.
• Ran "check", "check-clang", "check-tsan", "check-libgo" targets. I've never had much success with LLDB tests, and llgoi is currently broken so check-llgo fails for an unrelated reason.
• Ran "lldb" to ensure it loads.

[axw]

Merge trunk

[pcc]

Without these changes, passes won't load because the "Annotate..." symbols defined in lib/Support/Valigrind.cpp are not found.

I haven't looked at this in detail yet, but are these changes necessary after r245374?

[axw]

In D12488#236244, @pcc wrote:

Without these changes, passes won't load because the "Annotate..." symbols defined in lib/Support/Valigrind.cpp are not found.

I haven't looked at this in detail yet, but are these changes necessary after r245374?

Argh! :)

Probably not. Is there any strong reason *not* to change it now? This way, if later on someone adds weak symbols or others that don't begin with/include LLVM/llvm, then they'll get picked up.

[rnk]

Thanks, this is a lot less painful than I thought it'd be.

tools/llvm-config/CMakeLists.txt

2 ↗

(On Diff #33558)

Maybe throw a comment in here? I'm assuming this is because we want llvm-config to be a tiny statically linked binary for portability.

tools/llvm-shlib/CMakeLists.txt

79

@beanz Why is this code even generating export lists if it wants to export everything? The default Unix behavior is to export all default visibility symbols from shared objects. Here's how I'd structure it:

set(LLVM_EXPORTED_SYMBOL_FILE)
if (DEFINED LLVM_LLVM_DYLIB_EXPORTED_SYMBOL_FILE)
  set(LLVM_EXPORTED_SYMBOL_FILE ${LLVM_DYLIB_EXPORTED_SYMBOL_FILE})
  add_custom_target(libLLVMExports DEPENDS ${LLVM_EXPORTED_SYMBOL_FILE})
elseif (NOT LLVM_DYLIB_EXPORT_ALL)
  # ... C API generation code here
endif()

If LLVM_EXPORTED_SYMBOL_FILE is empty, add_llvm_library won't pass it in.

140

With the suggested structure, this would have to be conditional on if (LLVM_EXPORTED_SYMBOL_FILE).

[beanz]

cmake/modules/AddLLVM.cmake

451

If we're going to implement this, we should generalize the code from llvm-c-test/CMakeLists.txt to ensure that the dylib contains all the libraries that the library or tool we're linking requires. That will avoid difficult to debug linker errors.

616

See comment above.

cmake/modules/TableGen.cmake

74

I'd prefer to see this reworked as an option to add_llvm_utility, add_llvm_tool, etc. That makes it less magic.

tools/llvm-config/CMakeLists.txt

2 ↗

(On Diff #33558)

Same as my comment on tablegen. I'd rather see this as an overridden option on add_llvm_tool than turning the setting off for the sub directory.

tools/llvm-shlib/CMakeLists.txt

79

In my mind 'all' was to export everything LLVM, and we have some random things that aren't in the llvm namespace that I wanted to exclude.

If that doesn't make sense to other people, feel free to change it.

[rnk]

tools/llvm-shlib/CMakeLists.txt

79

I'd rather go with the tool defaults over custom shell commands. :)

[axw]

Address review comments

cmake/modules/AddLLVM.cmake

451

I think it's unlikely that anyone will use LLVM_LINK_LLVM_DYLIB, want to specify the components, and build only a subset of tools/shared libraries that matches them. So instead I've modified llvm-shlib so that if LLVM_LINK_LLVM_DYLIB is set:

• LLVM_DYLIB_COMPONENTS must not be set, and doing so will cause an error
• LLVM_DYLIB_EXPORT_ALL must be set, and not doing so will cause an error (it's defaulted to ON in the top-level CMakeLists.txt when LLVM_LINK_LLVM_DYLIB is enabled)
• Force linking in all components (except TableGen, as noted in summary and code comments)

Let me know if you think this isn't reasonable.

cmake/modules/TableGen.cmake

74

Done: added DISABLE_LLVM_LINK_LLVM_DYLIB option to add_llvm_library and add_llvm_executable (add_llvm_{utility, tool} etc. all devolve into the latter). Suggestions for less wordy option name are welcome.

tools/llvm-config/CMakeLists.txt

2 ↗

(On Diff #33558)

@rnk actually this change is unnecessary, I've reverted it. I must have made a mistake earlier on which caused a cyclic dependency, but it's not there anymore.

tools/llvm-shlib/CMakeLists.txt

79

@pcc pointed out these changes are no longer necessary, so I have reverted them.

[rnk]

lgtm :)

[chapuni]

cmake/modules/AddLLVM.cmake

44

Is it relevant to your changes?
FYI, it triggers recompilation of whole files (on ninja).

cmake/modules/TableGen.cmake

74

I thought it'd be just a variable, not an option, IMO.

The name "DISABLE_LLVM_LINK_LLVM_DYLIB" may be shorten.

[axw]

cmake/modules/AddLLVM.cmake

44

Is it relevant to your changes?

This was to fix a bug I found while making my changes. In some cases, COMPILE_FLAGS did not end with whitespace, so argument lists were being concatenated badly.

FYI, it triggers recompilation of whole files (on ninja).

Once only, right? Is that a problem?

cmake/modules/TableGen.cmake

74

I'm happy to change the name, given suggestions. It's likely only ever going to be used in two places, so I don't think worth spending much energy on.

[chapuni]

cmake/modules/AddLLVM.cmake

44

Once only, right? Is that a problem?

Once. Let it not reverted if it fixed your issue.

[beanz]

I still disagree with how this patch works, and there are some problems with it functionally too. For example, if you try to build clang, lld, or lldb with this it doesn't work at all, and even if it did, it would screw up the target dependencies, because llvm-shlib isn't processed by CMake until after clang, lld, and lldb.

I've also been thinking more about how this patch works, and I think it is implemented wrong. We should push all of this down into the llvm_config CMake functionality, and we should probably find a way to bake this behavior into the llvm-config executable and installed CMake files so that people using distributions of LLVM get the right behavior too.

[axw]

In D12488#237400, @beanz wrote:

I still disagree with how this patch works, and there are some problems with it functionally too. For example, if you try to build clang, lld, or lldb with this it doesn't work at all, and even if it did, it would screw up the target dependencies, because llvm-shlib isn't processed by CMake until after clang, lld, and lldb.

I don't understand, can you please elaborate on that? I built clang and lldb (not lld though; I should have), and they do work with the new option. Did you try them and find an issue? Please revert if it's actively breaking things, and let me know what needs fixing.

I've also been thinking more about how this patch works, and I think it is implemented wrong. We should push all of this down into the llvm_config CMake functionality, and we should probably find a way to bake this behavior into the llvm-config executable and installed CMake files so that people using distributions of LLVM get the right behavior too.

I did think about that, and the problem there is that the way the existing build scripts work is: call into LLVM-Config.cmake to translate a list of component names to library names, and pass them through target_link_libraries. Making this change would have been *much* more invasive, requiring touching all the CMakeLists.txts.

[axw]

In D12488#237856, @axw wrote:

In D12488#237400, @beanz wrote:

I've also been thinking more about how this patch works, and I think it is implemented wrong. We should push all of this down into the llvm_config CMake functionality, and we should probably find a way to bake this behavior into the llvm-config executable and installed CMake files so that people using distributions of LLVM get the right behavior too.

I did think about that, and the problem there is that the way the existing build scripts work is: call into LLVM-Config.cmake to translate a list of component names to library names, and pass them through target_link_libraries. Making this change would have been *much* more invasive, requiring touching all the CMakeLists.txts.

Please disregard this reply, I was in a pre-caffeine state. This is just what I did in AddLLVM.cmake. The alternative I was thinking of was to modify llvm_map_components_to_libnames to return libLLVM only in this mode, but that seemed like it would be wrong/surprising.

If you could describe how you'd like this to look instead, I'm very happy to do the work.

[beanz]

Clang builds, but it doesn’t link libLLVM. See:

> grep "build bin/clang-3.8" ./build.ninja
build bin/clang-3.8: CXX_EXECUTABLE_LINKER__clang tools/clang/tools/driver/CMakeFiles/clang.dir/driver.cpp.o tools/clang/tools/driver/CMakeFiles/clang.dir/cc1_main.cpp.o tools/clang/tools/driver/CMakeFiles/clang.dir/cc1as_main.cpp.o | lib/libLLVM.3.8.0svn.dylib lib/libclangBasic.a lib/libclangCodeGen.a lib/libclangDriver.a lib/libclangFrontend.a lib/libclangFrontendTool.a lib/libclangCodeGen.a lib/libLLVMBitWriter.a lib/libLLVMipo.a lib/libLLVMVectorize.a lib/libLLVMIRReader.a lib/libLLVMAsmParser.a lib/libLLVMInstrumentation.a lib/libLLVMLinker.a lib/libLLVMObjCARCOpts.a lib/libLLVMProfileData.a lib/libLLVMObject.a lib/libLLVMScalarOpts.a lib/libLLVMInstCombine.a lib/libLLVMTarget.a lib/libLLVMTransformUtils.a lib/libLLVMAnalysis.a lib/libclangRewriteFrontend.a lib/libclangARCMigrate.a lib/libclangStaticAnalyzerFrontend.a lib/libclangFrontend.a lib/libclangDriver.a lib/libLLVMOption.a lib/libclangParse.a lib/libLLVMMCParser.a lib/libclangSerialization.a lib/libLLVMBitReader.a lib/libclangSema.a lib/libclangEdit.a lib/libclangStaticAnalyzerCheckers.a lib/libclangStaticAnalyzerCore.a lib/libclangAnalysis.a lib/libclangAST.a lib/libclangRewrite.a lib/libclangLex.a lib/libclangBasic.a lib/libLLVMCore.a lib/libLLVMMC.a lib/libLLVMSupport.a || lib/libLLVMInstCombine.a lib/libLLVMAsmParser.a lib/libLLVMProfileData.a lib/libLLVMScalarOpts.a lib/libLLVMipo.a lib/libLLVMVectorize.a lib/libLLVMObjCARCOpts.a lib/libLLVMLinker.a lib/libLLVMAnalysis.a lib/libLLVMMC.a lib/libLLVMMCParser.a lib/libLLVMObject.a lib/libLLVMOption.a lib/libLLVMTarget.a tools/clang/include/clang/AST/ClangCommentCommandList tools/clang/include/clang/AST/ClangCommentCommandInfo tools/clang/include/clang/AST/ClangCommentHTMLNamedCharacterReferences tools/clang/include/clang/AST/ClangCommentHTMLTagsProperties tools/clang/include/clang/AST/ClangCommentNodes tools/clang/include/clang/AST/ClangAttrImpl tools/clang/include/clang/AST/ClangStmtNodes tools/clang/include/clang/AST/ClangAttrClasses tools/clang/include/clang/AST/ClangAttrDump tools/clang/include/clang/AST/ClangCommentHTMLTags tools/clang/include/clang/AST/ClangDeclNodes tools/clang/include/clang/AST/ClangAttrVisitor tools/clang/include/clang/Basic/ClangARMNeon tools/clang/include/clang/Basic/ClangDiagnosticIndexName tools/clang/include/clang/Basic/ClangDiagnosticParse tools/clang/include/clang/Basic/ClangDiagnosticFrontend tools/clang/include/clang/Basic/ClangDiagnosticSerialization tools/clang/include/clang/Basic/ClangDiagnosticLex tools/clang/include/clang/Basic/ClangDiagnosticCommon tools/clang/include/clang/Basic/ClangDiagnosticSema tools/clang/include/clang/Basic/ClangAttrList tools/clang/include/clang/Basic/ClangDiagnosticComment tools/clang/include/clang/Basic/ClangAttrHasAttributeImpl tools/clang/include/clang/Basic/ClangDiagnosticAST tools/clang/include/clang/Basic/ClangDiagnosticDriver tools/clang/include/clang/Basic/ClangDiagnosticGroups tools/clang/include/clang/Basic/ClangDiagnosticAnalysis tools/clang/include/clang/Parse/ClangAttrParserStringSwitches tools/clang/include/clang/Sema/ClangAttrParsedAttrList tools/clang/include/clang/Sema/ClangAttrTemplateInstantiate tools/clang/include/clang/Sema/ClangAttrSpellingListIndex tools/clang/include/clang/Sema/ClangAttrParsedAttrImpl tools/clang/include/clang/Sema/ClangAttrParsedAttrKinds tools/clang/include/clang/Serialization/ClangAttrPCHWrite tools/clang/include/clang/Serialization/ClangAttrPCHRead tools/clang/lib/Headers/clang-headers lib/libclangBasic.a lib/libclangLex.a lib/libclangParse.a lib/libclangAST.a lib/libclangSema.a lib/libclangCodeGen.a lib/libclangAnalysis.a lib/libclangEdit.a lib/libclangRewrite.a lib/libclangARCMigrate.a lib/libclangDriver.a lib/libclangSerialization.a lib/libclangFrontend.a lib/libclangRewriteFrontend.a lib/libclangFrontendTool.a lib/libclangStaticAnalyzerCore.a lib/libclangStaticAnalyzerCheckers.a lib/libclangStaticAnalyzerFrontend.a lib/libLLVM.dylib lib/libLLVMSupport.a lib/libLLVMCore.a lib/libLLVMIRReader.a lib/libLLVMBitReader.a lib/libLLVMBitWriter.a lib/libLLVMTransformUtils.a lib/libLLVMInstrumentation.a

It is actually impossible for your change to work as implemented because the libLLVM targets don’t exist until after clang, lld, and lldb targets are generated.

See the comment at the top of tools/CMakeLists.txt WRT ordering issues.

One of the other problems that you should account for is that not all tools and subprojects use AddLLVM. The AddLLVM macros shouldn't be calling target_link_libraries for LLVM libraries (I know the code did that in some places already and I'm not asking you to clean it up, just don't make it worse). Instead we should be relying on llvm_config. We should add an option "USE_SHARED" to llvm_config, and we should have code that filters the list of components passed into explicit_llvm_config based on the components included in the dylib and calls target_link_libraries as appropriate.

For this to work there are two changes required further out in CMake. (1) LLVM_DYLIB_COMPONENTS needs to be defined in the root CMakeLists (it can default to 'all'), and (2) tools/CMakeLists.txt needs to explicitly add llvm-shlib before any other tools.

It is probably reasonable to have add_llvm_utility default to not using the shared library, as I can't think of a single utility that is shipped as part of a distribution (and if there is one we should probably make it a tool).

[axw]

In D12488#238489, @beanz wrote:

Clang builds, but it doesn’t link libLLVM. See:

> grep "build bin/clang-3.8" ./build.ninja
build bin/clang-3.8: CXX_EXECUTABLE_LINKER__clang tools/clang/tools/driver/CMakeFiles/clang.dir/driver.cpp.o tools/clang/tools/driver/CMakeFiles/clang.dir/cc1_main.cpp.o tools/clang/tools/driver/CMakeFiles/clang.dir/cc1as_main.cpp.o | lib/libLLVM.3.8.0svn.dylib lib/libclangBasic.a lib/libclangCodeGen.a lib/libclangDriver.a lib/libclangFrontend.a lib/libclangFrontendTool.a lib/libclangCodeGen.a lib/libLLVMBitWriter.a lib/libLLVMipo.a lib/libLLVMVectorize.a lib/libLLVMIRReader.a lib/libLLVMAsmParser.a lib/libLLVMInstrumentation.a lib/libLLVMLinker.a lib/libLLVMObjCARCOpts.a lib/libLLVMProfileData.a lib/libLLVMObject.a lib/libLLVMScalarOpts.a lib/libLLVMInstCombine.a lib/libLLVMTarget.a lib/libLLVMTransformUtils.a lib/libLLVMAnalysis.a lib/libclangRewriteFrontend.a lib/libclangARCMigrate.a lib/libclangStaticAnalyzerFrontend.a lib/libclangFrontend.a lib/libclangDriver.a lib/libLLVMOption.a lib/libclangParse.a lib/libLLVMMCParser.a lib/libclangSerialization.a lib/libLLVMBitReader.a lib/libclangSema.a lib/libclangEdit.a lib/libclangStaticAnalyzerCheckers.a lib/libclangStaticAnalyzerCore.a lib/libclangAnalysis.a lib/libclangAST.a lib/libclangRewrite.a lib/libclangLex.a lib/libclangBasic.a lib/libLLVMCore.a lib/libLLVMMC.a lib/libLLVMSupport.a || lib/libLLVMInstCombine.a lib/libLLVMAsmParser.a lib/libLLVMProfileData.a lib/libLLVMScalarOpts.a lib/libLLVMipo.a lib/libLLVMVectorize.a lib/libLLVMObjCARCOpts.a lib/libLLVMLinker.a lib/libLLVMAnalysis.a lib/libLLVMMC.a lib/libLLVMMCParser.a lib/libLLVMObject.a lib/libLLVMOption.a lib/libLLVMTarget.a tools/clang/include/clang/AST/ClangCommentCommandList tools/clang/include/clang/AST/ClangCommentCommandInfo tools/clang/include/clang/AST/ClangCommentHTMLNamedCharacterReferences tools/clang/include/clang/AST/ClangCommentHTMLTagsProperties tools/clang/include/clang/AST/ClangCommentNodes tools/clang/include/clang/AST/ClangAttrImpl tools/clang/include/clang/AST/ClangStmtNodes tools/clang/include/clang/AST/ClangAttrClasses tools/clang/include/clang/AST/ClangAttrDump tools/clang/include/clang/AST/ClangCommentHTMLTags tools/clang/include/clang/AST/ClangDeclNodes tools/clang/include/clang/AST/ClangAttrVisitor tools/clang/include/clang/Basic/ClangARMNeon tools/clang/include/clang/Basic/ClangDiagnosticIndexName tools/clang/include/clang/Basic/ClangDiagnosticParse tools/clang/include/clang/Basic/ClangDiagnosticFrontend tools/clang/include/clang/Basic/ClangDiagnosticSerialization tools/clang/include/clang/Basic/ClangDiagnosticLex tools/clang/include/clang/Basic/ClangDiagnosticCommon tools/clang/include/clang/Basic/ClangDiagnosticSema tools/clang/include/clang/Basic/ClangAttrList tools/clang/include/clang/Basic/ClangDiagnosticComment tools/clang/include/clang/Basic/ClangAttrHasAttributeImpl tools/clang/include/clang/Basic/ClangDiagnosticAST tools/clang/include/clang/Basic/ClangDiagnosticDriver tools/clang/include/clang/Basic/ClangDiagnosticGroups tools/clang/include/clang/Basic/ClangDiagnosticAnalysis tools/clang/include/clang/Parse/ClangAttrParserStringSwitches tools/clang/include/clang/Sema/ClangAttrParsedAttrList tools/clang/include/clang/Sema/ClangAttrTemplateInstantiate tools/clang/include/clang/Sema/ClangAttrSpellingListIndex tools/clang/include/clang/Sema/ClangAttrParsedAttrImpl tools/clang/include/clang/Sema/ClangAttrParsedAttrKinds tools/clang/include/clang/Serialization/ClangAttrPCHWrite tools/clang/include/clang/Serialization/ClangAttrPCHRead tools/clang/lib/Headers/clang-headers lib/libclangBasic.a lib/libclangLex.a lib/libclangParse.a lib/libclangAST.a lib/libclangSema.a lib/libclangCodeGen.a lib/libclangAnalysis.a lib/libclangEdit.a lib/libclangRewrite.a lib/libclangARCMigrate.a lib/libclangDriver.a lib/libclangSerialization.a lib/libclangFrontend.a lib/libclangRewriteFrontend.a lib/libclangFrontendTool.a lib/libclangStaticAnalyzerCore.a lib/libclangStaticAnalyzerCheckers.a lib/libclangStaticAnalyzerFrontend.a lib/libLLVM.dylib lib/libLLVMSupport.a lib/libLLVMCore.a lib/libLLVMIRReader.a lib/libLLVMBitReader.a lib/libLLVMBitWriter.a lib/libLLVMTransformUtils.a lib/libLLVMInstrumentation.a

libLLVM.dylib *is* in that list (after clang static archives, before LLVM static archives). What am I missing?
(Sorry, I'd try on OS X myself but I don't have it. I also don't really know it well, so my bafflement could be related.)

It is actually impossible for your change to work as implemented because the libLLVM targets don’t exist until after clang, lld, and lldb targets are generated.

Again, this *is* working for me on Linux. Not theoretical - I'm looking at the resulting binaries right now, and all them are linked against libLLVM.so.

I am under the impression that CMake builds up fake nodes for libraries referred to ahead of time, and replaces them in the DAG when
the target is defined for real, so that ordering wouldn't matter. I don't know how this would work for me at all otherwise. I just wrote a
small CMake test that does:

• add_executable(X ...)
• target_link_libraries(X Y)
• add_library(Y ...)

and it worked just fine.

See the comment at the top of tools/CMakeLists.txt WRT ordering issues.

One of the other problems that you should account for is that not all tools and subprojects use AddLLVM. The AddLLVM macros shouldn't be calling target_link_libraries for LLVM libraries (I know the code did that in some places already and I'm not asking you to clean it up, just don't make it worse). Instead we should be relying on llvm_config. We should add an option "USE_SHARED" to llvm_config, and we should have code that filters the list of components passed into explicit_llvm_config based on the components included in the dylib and calls target_link_libraries as appropriate.

Sounds sensible. I don't quite understand why you'd need to filter the components, since they'll just be ignored if USE_SHARED is set?

For this to work there are two changes required further out in CMake. (1) LLVM_DYLIB_COMPONENTS needs to be defined in the root CMakeLists (it can default to 'all'), and (2) tools/CMakeLists.txt needs to explicitly add llvm-shlib before any other tools.

It is probably reasonable to have add_llvm_utility default to not using the shared library, as I can't think of a single utility that is shipped as part of a distribution (and if there is one we should probably make it a tool).

Thanks for explaining, that sounds neater if nothing else. I'll put something together soon that addresses these points, and send it to you for review. Sorry for causing you grief.

CMakeLists.txt

 option (LLVM_BUILD_DOCS "Build the llvm documentation." OFF)
 option (LLVM_INCLUDE_DOCS "Generate build targets for llvm documentation." ON)
 option (LLVM_ENABLE_DOXYGEN "Use doxygen to generate llvm API documentation." OFF)
 option (LLVM_ENABLE_SPHINX "Use Sphinx to generate llvm documentation." OFF)
 
 option (LLVM_BUILD_EXTERNAL_COMPILER_RT
   "Build compiler-rt as an external project." OFF)
 
-option(LLVM_BUILD_LLVM_DYLIB "Build libllvm dynamic library" OFF)
-option(LLVM_DYLIB_EXPORT_ALL "Export all symbols from libLLVM.dylib (default is C API only" OFF)
-option(LLVM_DISABLE_LLVM_DYLIB_ATEXIT "Disable llvm-shlib's atexit destructors." ON)
+option(LLVM_LINK_LLVM_DYLIB "Link tools against the libllvm dynamic library" OFF)
+option(LLVM_BUILD_LLVM_DYLIB "Build libllvm dynamic library" ${LLVM_LINK_LLVM_DYLIB})
+option(LLVM_DYLIB_EXPORT_ALL "Export all symbols from libLLVM.dylib (default is C API only" ${LLVM_LINK_LLVM_DYLIB})
+set(LLVM_DISABLE_LLVM_DYLIB_ATEXIT_DEFAULT ON)
+if (LLVM_LINK_LLVM_DYLIB)
+  set(LLVM_DISABLE_LLVM_DYLIB_ATEXIT_DEFAULT OFF)
+endif()
+option(LLVM_DISABLE_LLVM_DYLIB_ATEXIT "Disable llvm-shlib's atexit destructors." ${LLVM_DISABLE_LLVM_DYLIB_ATEXIT_DEFAULT})
 if(LLVM_DISABLE_LLVM_DYLIB_ATEXIT)
   set(DISABLE_LLVM_DYLIB_ATEXIT 1)
 endif()
 
 option(LLVM_OPTIMIZED_TABLEGEN "Force TableGen to be built with optimization" OFF)
 if(CMAKE_CROSSCOMPILING OR (LLVM_OPTIMIZED_TABLEGEN AND LLVM_ENABLE_ASSERTIONS))
   set(LLVM_USE_HOST_TOOLS ON)
 endif()

cmake/modules/AddLLVM.cmake

if(NOT (LLVM_REQUIRES_RTTI OR LLVM_ENABLE_RTTI))
     elseif (MSVC)
       list(APPEND LLVM_COMPILE_FLAGS "/GR-")
     endif ()
   endif()
 
   # Assume that;
   #   - LLVM_COMPILE_FLAGS is list.
   #   - PROPERTY COMPILE_FLAGS is string.
-  string(REPLACE ";" " " target_compile_flags "${LLVM_COMPILE_FLAGS}")
+  string(REPLACE ";" " " target_compile_flags " ${LLVM_COMPILE_FLAGS}")
 
   if(update_src_props)
     foreach(fn ${sources})
       get_filename_component(suf ${fn} EXT)
       if("${suf}" STREQUAL ".cpp")
         set_property(SOURCE ${fn} APPEND_STRING PROPERTY
           COMPILE_FLAGS "${target_compile_flags}")
       endif()

 
 # llvm_add_library(name sources...
 #   SHARED;STATIC
 #     STATIC by default w/o BUILD_SHARED_LIBS.
 #     SHARED by default w/  BUILD_SHARED_LIBS.
 #   MODULE
 #     Target ${name} might not be created on unsupported platforms.
 #     Check with "if(TARGET ${name})".
+#   DISABLE_LLVM_LINK_LLVM_DYLIB
+#     Do not link this library to libLLVM, even if
+#     LLVM_LINK_LLVM_DYLIB is enabled.
 #   OUTPUT_NAME name
 #     Corresponds to OUTPUT_NAME in target properties.
 #   DEPENDS targets...
 #     Same semantics as add_dependencies().
 #   LINK_COMPONENTS components...
 #     Same as the variable LLVM_LINK_COMPONENTS.
 #   LINK_LIBS lib_targets...
 #     Same semantics as target_link_libraries().
 #   ADDITIONAL_HEADERS
 #     May specify header files for IDE generators.
 #   )
 function(llvm_add_library name)
   cmake_parse_arguments(ARG
-    "MODULE;SHARED;STATIC"
+    "MODULE;SHARED;STATIC;DISABLE_LLVM_LINK_LLVM_DYLIB"
     "OUTPUT_NAME"
     "ADDITIONAL_HEADERS;DEPENDS;LINK_COMPONENTS;LINK_LIBS;OBJLIBS"
     ${ARGN})
   list(APPEND LLVM_COMMON_DEPENDS ${ARG_DEPENDS})
   if(ARG_ADDITIONAL_HEADERS)
     # Pass through ADDITIONAL_HEADERS.
     set(ARG_ADDITIONAL_HEADERS ADDITIONAL_HEADERS ${ARG_ADDITIONAL_HEADERS})
   endif()
function(llvm_add_library name)
 
   # Add the explicit dependency information for this library.
   #
   # It would be nice to verify that we have the dependencies for this library
   # name, but using get_property(... SET) doesn't suffice to determine if a
   # property has been set to an empty value.
   get_property(lib_deps GLOBAL PROPERTY LLVMBUILD_LIB_DEPS_${name})
 
+  if (LLVM_LINK_LLVM_DYLIB AND NOT ARG_STATIC AND NOT ARG_DISABLE_LLVM_LINK_LLVM_DYLIB)
+    set(llvm_libs LLVM)
+  else()
     llvm_map_components_to_libnames(llvm_libs
       ${ARG_LINK_COMPONENTS}
       ${LLVM_LINK_COMPONENTS}
       )
+  endif()
 
   if(CMAKE_VERSION VERSION_LESS 2.8.12)
     # Link libs w/o keywords, assuming PUBLIC.
     target_link_libraries(${name}
       ${ARG_LINK_LIBS}
       ${lib_deps}
       ${llvm_libs}
       )
else()
     endif()
   endif()
 
   set_target_properties(${name} PROPERTIES FOLDER "Loadable modules")
 endmacro(add_llvm_loadable_module name)
 
 
 macro(add_llvm_executable name)
-  llvm_process_sources( ALL_FILES ${ARGN} )
+  cmake_parse_arguments(ARG "DISABLE_LLVM_LINK_LLVM_DYLIB" "" "" ${ARGN})
+  llvm_process_sources( ALL_FILES ${ARG_UNPARSED_ARGUMENTS} )
 
   # Generate objlib
   if(LLVM_ENABLE_OBJLIB)
     # Generate an obj library for both targets.
     set(obj_name "obj.${name}")
     add_library(${obj_name} OBJECT EXCLUDE_FROM_ALL
       ${ALL_FILES}
       )
macro(add_llvm_executable name)
   set_target_properties( ${name} PROPERTIES DEFINE_SYMBOL "" )
 
   if (LLVM_EXPORTED_SYMBOL_FILE)
     add_llvm_symbol_exports( ${name} ${LLVM_EXPORTED_SYMBOL_FILE} )
   endif(LLVM_EXPORTED_SYMBOL_FILE)
 
   set(EXCLUDE_FROM_ALL OFF)
   set_output_directory(${name} ${LLVM_RUNTIME_OUTPUT_INTDIR} ${LLVM_LIBRARY_OUTPUT_INTDIR})
+  if (LLVM_LINK_LLVM_DYLIB AND NOT ARG_DISABLE_LLVM_LINK_LLVM_DYLIB)
+    target_link_libraries(${name} LLVM)
+  else()
     llvm_config( ${name} ${LLVM_LINK_COMPONENTS} )
+  endif()
   if( LLVM_COMMON_DEPENDS )
     add_dependencies( ${name} ${LLVM_COMMON_DEPENDS} )
   endif( LLVM_COMMON_DEPENDS )
 endmacro(add_llvm_executable name)
 
 function(export_executable_symbols target)
   if (NOT MSVC) # MSVC's linker doesn't support exporting all symbols.
     set_target_properties(${target} PROPERTIES ENABLE_EXPORTS 1)
if(LLVM_BINDINGS MATCHES "go")
     set(cc "${CMAKE_C_COMPILER} ${CMAKE_C_COMPILER_ARG1}")
     set(cxx "${CMAKE_CXX_COMPILER} ${CMAKE_CXX_COMPILER_ARG1}")
     set(cppflags "")
     get_property(include_dirs DIRECTORY PROPERTY INCLUDE_DIRECTORIES)
     foreach(d ${include_dirs})
       set(cppflags "${cppflags} -I${d}")
     endforeach(d)
     set(ldflags "${CMAKE_EXE_LINKER_FLAGS}")
+    if (LLVM_LINK_LLVM_DYLIB)
+      set(linkmode "dylib")
+    else()
+      set(linkmode "component-libs")
+    endif()
     add_custom_command(OUTPUT ${binpath}
-      COMMAND ${CMAKE_BINARY_DIR}/bin/llvm-go "go=${GO_EXECUTABLE}" "cc=${cc}" "cxx=${cxx}" "cppflags=${cppflags}" "ldflags=${ldflags}"
+      COMMAND ${CMAKE_BINARY_DIR}/bin/llvm-go "go=${GO_EXECUTABLE}" "cc=${cc}" "cxx=${cxx}" "cppflags=${cppflags}" "ldflags=${ldflags}" "linkmode=${linkmode}"
               ${ARG_GOFLAGS} build -o ${binpath} ${pkgpath}
       DEPENDS llvm-config ${CMAKE_BINARY_DIR}/bin/llvm-go${CMAKE_EXECUTABLE_SUFFIX}
               ${llvmlibs} ${ARG_DEPENDS}
       COMMENT "Building Go executable ${binary}"
       VERBATIM)
     if (ARG_ALL)
       add_custom_target(${binary} ALL DEPENDS ${binpath})
     else()

cmake/modules/TableGen.cmake

function(add_public_tablegen_target target)
   if(LLVM_COMMON_DEPENDS)
     add_dependencies(${target} ${LLVM_COMMON_DEPENDS})
   endif()
   set_target_properties(${target} PROPERTIES FOLDER "Tablegenning")
   set(LLVM_COMMON_DEPENDS ${LLVM_COMMON_DEPENDS} ${target} PARENT_SCOPE)
 endfunction()
 
 macro(add_tablegen target project)
   set(${target}_OLD_LLVM_LINK_COMPONENTS ${LLVM_LINK_COMPONENTS})
   set(LLVM_LINK_COMPONENTS ${LLVM_LINK_COMPONENTS} TableGen)
 
   # FIXME: It leaks to user, callee of add_tablegen.
   set(LLVM_ENABLE_OBJLIB ON)
 
-  add_llvm_utility(${target} ${ARGN})
+  add_llvm_utility(
+    ${target} ${ARGN}
+    # libLLVM does not include the TableGen
+    # components, so we cannot link any tblgen
+    # utilities against it.
+    DISABLE_LLVM_LINK_LLVM_DYLIB)
+
   set(LLVM_LINK_COMPONENTS ${${target}_OLD_LLVM_LINK_COMPONENTS})
 
   set(${project}_TABLEGEN "${target}" CACHE
       STRING "Native TableGen executable. Saves building one when cross-compiling.")
 
   # Upgrade existing LLVM_TABLEGEN setting.
   if(${project} STREQUAL LLVM)
     if(${LLVM_TABLEGEN} STREQUAL tblgen)

tools/llvm-go/llvm-go.go

import (
   "io/ioutil"
   "os"
   "os/exec"
   "path/filepath"
   "runtime"
   "strings"
 )
 
+const (
+  linkmodeComponentLibs = "component-libs"
+  linkmodeDylib         = "dylib"
+)
+
 type pkg struct {
   llvmpath, pkgpath string
 }
 
 var packages = []pkg{
   {"bindings/go/llvm", "llvm.org/llvm/bindings/go/llvm"},
   {"tools/llgo", "llvm.org/llgo"},
 }
var components = []string{
   "scalaropts",
   "support",
   "target",
 }
 
 func llvmConfig(args ...string) string {
   configpath := os.Getenv("LLVM_CONFIG")
   if configpath == "" {
-    // strip llvm-go, add llvm-config
-    configpath = os.Args[0][:len(os.Args[0])-7] + "llvm-config"
+    bin, _ := filepath.Split(os.Args[0])
+    configpath = filepath.Join(bin, "llvm-config")
   }
 
   cmd := exec.Command(configpath, args...)
+  cmd.Stderr = os.Stderr
   out, err := cmd.Output()
   if err != nil {
     panic(err.Error())
   }
 
   outstr := string(out)
   outstr = strings.TrimSuffix(outstr, "\n")
-  return strings.Replace(outstr, "\n", " ", -1)
+  outstr = strings.Replace(outstr, "\n", " ", -1)
+  return outstr
 }
 
-func llvmFlags() compilerFlags {
-  ldflags := llvmConfig(append([]string{"--ldflags", "--libs", "--system-libs"}, components...)...)
+func llvmFlags(linkmode string) compilerFlags {
+  ldflags := llvmConfig("--ldflags")
+  switch linkmode {
+  case linkmodeComponentLibs:
+    ldflags += " " + llvmConfig(append([]string{"--libs"}, components...)...)
+  case linkmodeDylib:
+    ldflags += " -lLLVM"
+  default:
+    panic("invalid linkmode: " + linkmode)
+  }
+  ldflags += " " + llvmConfig("--system-libs")
   if runtime.GOOS != "darwin" {
     // OS X doesn't like -rpath with cgo. See:
     // https://code.google.com/p/go/issues/detail?id=7293
     ldflags = "-Wl,-rpath," + llvmConfig("--libdir") + " " + ldflags
   }
   return compilerFlags{
     cpp: llvmConfig("--cppflags"),
     cxx: "-std=c++11",
func addTag(args []string, tag string) []string {
   }
   return args
 }
 
 func printComponents() {
   fmt.Println(strings.Join(components, " "))
 }
 
-func printConfig() {
-  flags := llvmFlags()
+func printConfig(linkmode string) {
+  flags := llvmFlags(linkmode)
 
   fmt.Printf(`// +build !byollvm
 
 // This file is generated by llvm-go, do not edit.
 
 package llvm
 
 /*
 #cgo CPPFLAGS: %s
 #cgo CXXFLAGS: %s
 #cgo LDFLAGS: %s
 */
 import "C"
 
 type (run_build_sh int)
 `, flags.cpp, flags.cxx, flags.ld)
 }
 
-func runGoWithLLVMEnv(args []string, cc, cxx, gocmd, llgo, cppflags, cxxflags, ldflags string) {
+func runGoWithLLVMEnv(args []string, cc, cxx, gocmd, llgo, cppflags, cxxflags, ldflags, linkmode string) {
   args = addTag(args, "byollvm")
 
   srcdir := llvmConfig("--src-root")
 
   tmpgopath, err := ioutil.TempDir("", "gopath")
   if err != nil {
     panic(err.Error())
   }
func runGoWithLLVMEnv(args []string, cc, cxx, gocmd, llgo, cppflags, cxxflags, ldflags, linkmode string) {
   }
 
   newpath := os.Getenv("PATH")
 
   newgopathlist := []string{tmpgopath}
   newgopathlist = append(newgopathlist, filepath.SplitList(os.Getenv("GOPATH"))...)
   newgopath := strings.Join(newgopathlist, string(filepath.ListSeparator))
 
-  flags := llvmFlags()
+  flags := llvmFlags(linkmode)
 
   newenv := []string{
     "CC=" + cc,
     "CXX=" + cxx,
     "CGO_CPPFLAGS=" + flags.cpp + " " + cppflags,
     "CGO_CXXFLAGS=" + flags.cxx + " " + cxxflags,
     "CGO_LDFLAGS=" + flags.ld + " " + ldflags,
     "GOPATH=" + newgopath,
     "PATH=" + newpath,
   }
   if llgo != "" {
-    newenv = append(newenv, "GCCGO=" + llgo)
+    newenv = append(newenv, "GCCGO="+llgo)
   }
 
   for _, v := range os.Environ() {
     if !strings.HasPrefix(v, "CC=") &&
       !strings.HasPrefix(v, "CXX=") &&
       !strings.HasPrefix(v, "CGO_CPPFLAGS=") &&
       !strings.HasPrefix(v, "CGO_CXXFLAGS=") &&
       !strings.HasPrefix(v, "CGO_LDFLAGS=") &&

 func main() {
   cc := os.Getenv("CC")
   cxx := os.Getenv("CXX")
   cppflags := os.Getenv("CGO_CPPFLAGS")
   cxxflags := os.Getenv("CGO_CXXFLAGS")
   ldflags := os.Getenv("CGO_LDFLAGS")
   gocmd := "go"
   llgo := ""
+  linkmode := linkmodeComponentLibs
+
+  flags := []struct {
+    name string
+    dest *string
+  }{
+    {"cc", &cc},
+    {"cxx", &cxx},
+    {"go", &gocmd},
+    {"llgo", &llgo},
+    {"cppflags", &cppflags},
+    {"ldflags", &ldflags},
+    {"linkmode", &linkmode},
+  }
 
   args := os.Args[1:]
-  DONE: for {
-    switch {
-    case len(args) == 0:
+LOOP:
+  for {
+    if len(args) == 0 {
       usage()
-    case strings.HasPrefix(args[0], "cc="):
-      cc = args[0][3:]
-      args = args[1:]
-    case strings.HasPrefix(args[0], "cxx="):
-      cxx = args[0][4:]
-      args = args[1:]
-    case strings.HasPrefix(args[0], "go="):
-      gocmd = args[0][3:]
-      args = args[1:]
-    case strings.HasPrefix(args[0], "llgo="):
-      llgo = args[0][5:]
-      args = args[1:]
-    case strings.HasPrefix(args[0], "cppflags="):
-      cppflags = args[0][9:]
-      args = args[1:]
-    case strings.HasPrefix(args[0], "cxxflags="):
-      cxxflags = args[0][9:]
-      args = args[1:]
-    case strings.HasPrefix(args[0], "ldflags="):
-      ldflags = args[0][8:]
+    }
+    for _, flag := range flags {
+      if strings.HasPrefix(args[0], flag.name+"=") {
+        *flag.dest = args[0][len(flag.name)+1:]
         args = args[1:]
-    default:
-      break DONE
+        continue LOOP
+      }
     }
+    break
   }
 
   switch args[0] {
   case "build", "get", "install", "run", "test":
-    runGoWithLLVMEnv(args, cc, cxx, gocmd, llgo, cppflags, cxxflags, ldflags)
+    runGoWithLLVMEnv(args, cc, cxx, gocmd, llgo, cppflags, cxxflags, ldflags, linkmode)
   case "print-components":
     printComponents()
   case "print-config":
-    printConfig()
+    printConfig(linkmode)
   default:
     usage()
   }
 }

tools/llvm-shlib/CMakeLists.txt

 # This tool creates a shared library from the LLVM libraries. Generating this
 # library is enabled by setting LLVM_BUILD_LLVM_DYLIB=yes on the CMake
 # commandline. By default the shared library only exports the LLVM C API.
 
+if(LLVM_LINK_LLVM_DYLIB)
+  if(DEFINED LLVM_DYLIB_COMPONENTS)
+    # To avoid inscrutable link errors, just disallow setting
+    # LLVM_DYLIB_COMPONENTS when we're intending to link tools
+    # and shared libraries with the dylib.
+    message(FATAL_ERROR "LLVM_DYLIB_COMPONENTS must not be set when LLVM_LINK_LLVM_DYLIB is ON")
+  endif()
+  if(NOT LLVM_DYLIB_EXPORT_ALL)
+    message(FATAL_ERROR "LLVM_DYLIB_EXPORT_ALL must be ON when LLVM_LINK_LLVM_DYLIB is ON")
+  endif()
+  set(LLVM_DYLIB_COMPONENTS all)
+endif()
 
-# You can configure which libraries from LLVM you want to include in the shared
-# library by setting LLVM_DYLIB_COMPONENTS to a semi-colon delimited list of
-# LLVM components. All compoenent names handled by llvm-config are valid.
-
+# If LLVM_LINK_LLVM_DYLIB is not OFF, you can configure which libraries from
+# LLVM you want to include in the shared library by setting
+# LLVM_DYLIB_COMPONENTS to a semi-colon delimited list of LLVM components.
+# All component names handled by llvm-config are valid.
 if(NOT DEFINED LLVM_DYLIB_COMPONENTS)
   set(LLVM_DYLIB_COMPONENTS
     ${LLVM_TARGETS_TO_BUILD}
     Analysis
     BitReader
     BitWriter
     CodeGen
     Core

 add_definitions( -DLLVM_VERSION_INFO=\"${PACKAGE_VERSION}\" )
 
 set(SOURCES
   libllvm.cpp
   )
 
 llvm_map_components_to_libnames(LIB_NAMES ${LLVM_DYLIB_COMPONENTS})
 
+if(LLVM_LINK_LLVM_DYLIB)
+  # libLLVM.so should not have any dependencies on any other LLVM
+  # shared libraries. When using the "all" pseudo-component,
+  # LLVM_AVAILABLE_LIBS is added to the dependencies, which may
+  # contain shared libraries (e.g. libLTO).
+  #
+  # Also exclude libLLVMTableGen for the following reasons:
+  #  - it is only used by internal *-tblgen utilities;
+  #  - it pollutes the global options space.
+  foreach(lib ${LIB_NAMES})
+    get_target_property(t ${lib} TYPE)
+    if("${lib}" STREQUAL "LLVMTableGen")
+    elseif("x${t}" STREQUAL "xSTATIC_LIBRARY")
+      list(APPEND FILTERED_LIB_NAMES ${lib})
+    endif()
+  endforeach()
+  set(LIB_NAMES ${FILTERED_LIB_NAMES})
+endif()
+
 if(NOT DEFINED LLVM_DYLIB_EXPORTED_SYMBOL_FILE)
 
   if( WIN32 AND NOT CYGWIN )
     message(FATAL_ERROR "Auto-generation not implemented for Win32 without GNU utils. Please specify LLVM_EXPORTED_SYMBOL_FILE.")
   endif()
 
   # To get the export list for a single llvm library:
   # nm ${LIB_PATH} | awk "/T _LLVM/ { print $3 }" | sort -u | sed -e "s/^_//g" > ${LIB_PATH}.exports
 
if(NOT DEFINED LLVM_DYLIB_EXPORTED_SYMBOL_FILE)
   endif()
 
   add_custom_target(libLLVMExports DEPENDS ${LLVM_EXPORTED_SYMBOL_FILE})
 else()
   set(LLVM_EXPORTED_SYMBOL_FILE ${LLVM_DYLIB_EXPORTED_SYMBOL_FILE})
   add_custom_target(libLLVMExports DEPENDS ${LLVM_EXPORTED_SYMBOL_FILE})
 endif()
 
-add_llvm_library(LLVM SHARED ${SOURCES})
+add_llvm_library(LLVM SHARED DISABLE_LLVM_LINK_LLVM_DYLIB ${SOURCES})
 
 list(REMOVE_DUPLICATES LIB_NAMES)
 if("${CMAKE_SYSTEM_NAME}" STREQUAL "Linux") # FIXME: It should be "GNU ld for elf"
   # GNU ld doesn't resolve symbols in the version script.
   set(LIB_NAMES -Wl,--whole-archive ${LIB_NAMES} -Wl,--no-whole-archive)
 elseif("${CMAKE_SYSTEM_NAME}" STREQUAL "Darwin")
   set(LIB_NAMES -Wl,-all_load ${LIB_NAMES})
 endif()
 
 target_link_libraries(LLVM PRIVATE ${LIB_NAMES})
 
 add_dependencies(LLVM libLLVMExports)
 
 if (APPLE)
   set_property(TARGET LLVM APPEND_STRING PROPERTY
               LINK_FLAGS
               " -compatibility_version ${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR} -current_version ${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}")
 endif()