Reapply r276856 "Adjust Registry interface to not require plugins to export a registry"

This version has two fixes compared to the original:
 * In Registry.h the template static members are instantiated before they are
   used, as clang gives an error if you do it the other way around.
 * The use of the Registry template in clang-tidy is updated in the same way as
   has been done everywhere else.

Original commit message:

Currently the Registry class contains the vestiges of a previous attempt to
allow plugins to be used on Windows without using BUILD_SHARED_LIBS, where a
plugin would have its own copy of a registry and export it to be imported by
the tool that's loading the plugin. This only works if the plugin is entirely
self-contained with the only interface between the plugin and tool being the
registry, and in particular this conflicts with how IR pass plugins work.

This patch changes things so that instead the add_node function of the registry
is exported by the tool and then imported by the plugin, which solves this
problem and also means that instead of every plugin having to export every
registry they use instead LLVM only has to export the add_node functions. This
allows plugins that use a registry to work on Windows if
LLVM_EXPORT_SYMBOLS_FOR_PLUGINS is used.

llvm-svn: 276973

7 files changed, 6 insertions, 9 deletions

diff --git a/clang/examples/AnnotateFunctions/CMakeLists.txt b/clang/examples/AnnotateFunctions/CMakeLists.txt
index cf564d527d6..5684abf2380 100644
--- a/clang/examples/AnnotateFunctions/CMakeLists.txt
+++ b/clang/examples/AnnotateFunctions/CMakeLists.txt
@@ -1,4 +1,4 @@
-add_llvm_loadable_module(AnnotateFunctions AnnotateFunctions.cpp)
+add_llvm_loadable_module(AnnotateFunctions AnnotateFunctions.cpp PLUGIN_TOOL clang)
 
 if(LLVM_ENABLE_PLUGINS AND (WIN32 OR CYGWIN))
   target_link_libraries(AnnotateFunctions PRIVATE
diff --git a/clang/examples/PrintFunctionNames/CMakeLists.txt b/clang/examples/PrintFunctionNames/CMakeLists.txt
index 5a00d5036fb..f5f818866ca 100644
--- a/clang/examples/PrintFunctionNames/CMakeLists.txt
+++ b/clang/examples/PrintFunctionNames/CMakeLists.txt
@@ -9,7 +9,7 @@ if( NOT MSVC ) # MSVC mangles symbols differently, and
   endif()
 endif()
 
-add_llvm_loadable_module(PrintFunctionNames PrintFunctionNames.cpp)
+add_llvm_loadable_module(PrintFunctionNames PrintFunctionNames.cpp PLUGIN_TOOL clang)
 
 if(LLVM_ENABLE_PLUGINS AND (WIN32 OR CYGWIN))
   target_link_libraries(PrintFunctionNames PRIVATE
diff --git a/clang/include/clang/Frontend/FrontendPluginRegistry.h b/clang/include/clang/Frontend/FrontendPluginRegistry.h
index ecab630c122..9d7ee08d95d 100644
--- a/clang/include/clang/Frontend/FrontendPluginRegistry.h
+++ b/clang/include/clang/Frontend/FrontendPluginRegistry.h
@@ -13,9 +13,6 @@
 #include "clang/Frontend/FrontendAction.h"
 #include "llvm/Support/Registry.h"
 
-// Instantiated in FrontendAction.cpp.
-extern template class llvm::Registry<clang::PluginASTAction>;
-
 namespace clang {
 
 /// The frontend plugin registry.
diff --git a/clang/include/clang/Lex/Preprocessor.h b/clang/include/clang/Lex/Preprocessor.h
index c9b712504e1..000df6647fe 100644
--- a/clang/include/clang/Lex/Preprocessor.h
+++ b/clang/include/clang/Lex/Preprocessor.h
@@ -1972,6 +1972,4 @@ typedef llvm::Registry<PragmaHandler> PragmaHandlerRegistry;
 
 }  // end namespace clang
 
-extern template class llvm::Registry<clang::PragmaHandler>;
-
 #endif
diff --git a/clang/lib/Frontend/FrontendAction.cpp b/clang/lib/Frontend/FrontendAction.cpp
index d2c2a80394d..2945b8925f9 100644
--- a/clang/lib/Frontend/FrontendAction.cpp
+++ b/clang/lib/Frontend/FrontendAction.cpp
@@ -33,7 +33,7 @@
 #include <system_error>
 using namespace clang;
 
-template class llvm::Registry<clang::PluginASTAction>;
+LLVM_INSTANTIATE_REGISTRY(FrontendPluginRegistry)
 
 namespace {
 
diff --git a/clang/lib/Lex/Preprocessor.cpp b/clang/lib/Lex/Preprocessor.cpp
index 8832c7f80c4..f0d68725462 100644
--- a/clang/lib/Lex/Preprocessor.cpp
+++ b/clang/lib/Lex/Preprocessor.cpp
@@ -54,7 +54,7 @@
 #include <utility>
 using namespace clang;
 
-template class llvm::Registry<clang::PragmaHandler>;
+LLVM_INSTANTIATE_REGISTRY(PragmaHandlerRegistry)
 
 //===----------------------------------------------------------------------===//
 ExternalPreprocessorSource::~ExternalPreprocessorSource() { }
diff --git a/clang/lib/Tooling/CompilationDatabase.cpp b/clang/lib/Tooling/CompilationDatabase.cpp
index 8fc4a1fe5be..6f95bf01f69 100644
--- a/clang/lib/Tooling/CompilationDatabase.cpp
+++ b/clang/lib/Tooling/CompilationDatabase.cpp
@@ -32,6 +32,8 @@
 using namespace clang;
 using namespace tooling;
 
+LLVM_INSTANTIATE_REGISTRY(CompilationDatabasePluginRegistry)
+
 CompilationDatabase::~CompilationDatabase() {}
 
 std::unique_ptr<CompilationDatabase>