[cmake] rework LLVM_LINK_LLVM_DYLIB option handling

Summary:
This diff attempts to address the concerns raised in
http://reviews.llvm.org/D12488.

We introduce a new USE_SHARED option to llvm_config,
which, if set, causes the target to be linked against
libLLVM.

add_llvm_utility now uniformly disables linking against
libLLVM. These utilities are not intended for distribution,
and this keeps the option handling more centralised.

llvm-shlib is now processes before any other "tools"
subdirectories, ensuring the libLLVM target is defined
before its dependents.

One main difference from what was requested: llvm_config
does not prune LLVM_DYLIB_COMPONENTS from the components
passed into explicit_llvm_config. This is because the "all"
component does something special, adding additional
libraries (namely libLTO). Adding the component libraries
after libLLVM should not be a problem, as symbols will be
resolved in libLLVM first.

Finally, I'm not really happy with the
DISABLE_LLVM_LINK_LLVM option, but I'm not sure of a
better way to get the following:
 - link all tools and shared libraries to libLLVM if
   LLVM_LINK_LLVM_DYLIB is set
 - some way of explicitly *not* doing so for utilities
   and libLLVM itself
Suggestions for improvement here are particularly welcome.

Reviewers: beanz

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D12590

llvm-svn: 246918

1 files changed, 4 insertions, 47 deletions

diff --git a/llvm/tools/llvm-shlib/CMakeLists.txt b/llvm/tools/llvm-shlib/CMakeLists.txt
index 7415722d3f6..d9bd15f7624 100644
--- a/llvm/tools/llvm-shlib/CMakeLists.txt
+++ b/llvm/tools/llvm-shlib/CMakeLists.txt
@@ -2,53 +2,6 @@
 # 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()
-
-# 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
-    ${LLVM_TARGETS_TO_BUILD}
-    Analysis
-    BitReader
-    BitWriter
-    CodeGen
-    Core
-    DebugInfoDWARF
-    DebugInfoPDB
-    ExecutionEngine
-    IPO
-    IRReader
-    InstCombine
-    Instrumentation
-    Interpreter
-    Linker
-    MCDisassembler
-    MCJIT
-    ObjCARCOpts
-    Object
-    ScalarOpts
-    Support
-    Target
-    TransformUtils
-    Vectorize
-    native
-    )
-endif()
-
 add_definitions( -DLLVM_VERSION_INFO=\"${PACKAGE_VERSION}\" )
 
 set(SOURCES
@@ -58,6 +11,10 @@ set(SOURCES
 llvm_map_components_to_libnames(LIB_NAMES ${LLVM_DYLIB_COMPONENTS})
 
 if(LLVM_LINK_LLVM_DYLIB)
+  if(NOT LLVM_DYLIB_EXPORT_ALL)
+    message(FATAL_ERROR "LLVM_DYLIB_EXPORT_ALL must be ON when LLVM_LINK_LLVM_DYLIB is ON")
+  endif()
+
   # 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