Move manifest utils into separate lib, to reduce libxml2 deps.

[ecbeckmann]

Summary

Previously were in support. Since many many things depend on support,
were all forced to also depend on libxml2, which we only want in a few cases.
This puts all the libxml2 deps in a separate lib to be used only in a few
places.

[rnk]

Can you remind me if we had any expected clients for manifest merging? Does LLD need to call this logic? If lld doesn't need to call this logic, I'd suggest we move this to tools/llvm-mt.

[ecbeckmann]

In D35819#820736, @rnk wrote:

Can you remind me if we had any expected clients for manifest merging? Does LLD need to call this logic? If lld doesn't need to call this logic, I'd suggest we move this to tools/llvm-mt.

LLD will need to call this logic. This will replace the external shell-out to "mt.exe" in DriverUtils, by merging manifests directly in the memory of the same process.

[rnk]

lgtm

[ecbeckmann]

rebase

llvm/include/llvm/WindowsManifest/WindowsManifestMerger.h

 //===-- WindowsManifestMerger.h ---------------------------------*- C++-*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===---------------------------------------------------------------------===//
 //
 // This file provides a utility for merging Microsoft .manifest files.  These
 // files are xml documents which contain meta-information about applications,
 // such as whether or not admin access is required, system compatibility,
 // versions, etc.  Part of the linking process of an executable may require
 // merging several of these .manifest files using a tree-merge following
 // specific rules.  Unfortunately, these rules are not documented well
 // anywhere.  However, a careful investigation of the behavior of the original
 // Microsoft Manifest Tool (mt.exe) revealed the rules of this merge.  As the
 // saying goes, code is the best documentation, so please look below if you are
 // interested in the exact merging requirements.
 //
 // Ref:
 // https://msdn.microsoft.com/en-us/library/windows/desktop/aa374191(v=vs.85).aspx
 //
 //===---------------------------------------------------------------------===//
 
 #ifndef LLVM_INCLUDE_LLVM_SUPPORT_WINDOWS_MANIFEST_MERGER_H
 #define LLVM_INCLUDE_LLVM_SUPPORT_WINDOWS_MANIFEST_MERGER_H
 
 #include "llvm/Config/config.h"
 #include "llvm/Support/Error.h"
 
 #if LLVM_LIBXML2_ENABLED
 #include <libxml/xmlreader.h>
 #endif
 
 namespace llvm {
 
 class MemoryBuffer;
 
 #if LLVM_LIBXML2_ENABLED
 typedef xmlDocPtr XMLDocumentImpl;
 typedef xmlNodePtr XMLNodeImpl;
 #else
 typedef void *XMLDocumentImpl;
 typedef void *XMLNodeImpl;
 #endif
 
 class WindowsManifestError : public ErrorInfo<WindowsManifestError, ECError> {
 public:
   static char ID;
   WindowsManifestError(const Twine &Msg);
   void log(raw_ostream &OS) const override;
 
 private:
   std::string Msg;
 };
 
 class WindowsManifestMerger {
 public:
   Error merge(const MemoryBuffer &Manifest);
 
   // Returns vector containing merged xml manifest, or uninitialized vector for
   // empty manifest.
   std::unique_ptr<MemoryBuffer> getMergedManifest();
 
 private:
   static void errorCallback(void *Ctx, const char *Format, ...);
   Error getParseError();
 
 #if LLVM_LIBXML2_ENABLED
   XMLNodeImpl CombinedRoot = nullptr;
 #endif
   bool ParseErrorOccurred = false;
 };
 
 } // namespace llvm
 #endif

llvm/include/llvm/module.modulemap

 
 // This is used for a $src == $build compilation. Otherwise we use
 // LLVM_Support_DataTypes_Build, defined in a module map that is
 // copied into the build area.
 module LLVM_Support_DataTypes_Src {
   header "llvm/Support/DataTypes.h"
   export *
 }
+
+module LLVM_WindowsManifest {
+  requires cplusplus
+  umbrella "WindowsManifest"
+  module * { export * }
+}

llvm/lib/CMakeLists.txt

 add_subdirectory(AsmParser)
 add_subdirectory(LineEditor)
 add_subdirectory(ProfileData)
 add_subdirectory(Fuzzer)
 add_subdirectory(Passes)
 add_subdirectory(ToolDrivers)
 add_subdirectory(XRay)
 add_subdirectory(Testing)
+add_subdirectory(WindowsManifest)

llvm/lib/LLVMBuild.txt

  Passes
  ProfileData
  Support
  TableGen
  Target
  Testing
  ToolDrivers
  Transforms
+ WindowsManifest
 
 [component_0]
 type = Group
 name = Libraries
 parent = $ROOT

llvm/lib/Support/CMakeLists.txt

elseif( CMAKE_HOST_UNIX )
   endif()
   set(system_libs ${system_libs} ${LLVM_PTHREAD_LIB})
   if ( LLVM_ENABLE_ZLIB AND HAVE_LIBZ )
     set(system_libs ${system_libs} z)
   endif()
   if( UNIX AND NOT (BEOS OR HAIKU) )
     set(system_libs ${system_libs} m)
   endif()
-  if( LLVM_LIBXML2_ENABLED )
-    set(system_libs ${system_libs} ${LIBXML2_LIBS})
-  endif()
 endif( MSVC OR MINGW )
 
 add_llvm_library(LLVMSupport
   AMDGPUCodeObjectMetadata.cpp
   APFloat.cpp
   APInt.cpp
   APSInt.cpp
   ARMBuildAttrs.cpp
add_llvm_library(LLVMSupport
   TargetParser.cpp
   ThreadPool.cpp
   Timer.cpp
   ToolOutputFile.cpp
   TrigramIndex.cpp
   Triple.cpp
   Twine.cpp
   Unicode.cpp
-  WindowsManifestMerger.cpp
   YAMLParser.cpp
   YAMLTraits.cpp
   raw_os_ostream.cpp
   raw_ostream.cpp
   regcomp.c
   regerror.c
   regexec.c
   regfree.c

llvm/lib/WindowsManifest/CMakeLists.txt

+set(system_libs)
+if( CMAKE_HOST_UNIX )
+  if( LLVM_LIBXML2_ENABLED )
+    set(system_libs ${system_libs} ${LIBXML2_LIBS})
+  endif()
+endif()
+
+add_llvm_library(LLVMWindowsManifest
+  WindowsManifestMerger.cpp
+
+  ADDITIONAL_HEADER_DIRS
+  ${LLVM_MAIN_INCLUDE_DIR}/llvm/WindowsManifest
+  ${Backtrace_INCLUDE_DIRS}
+
+  LINK_LIBS ${system_libs}
+  )
+
+set_property(TARGET LLVMWindowsManifest PROPERTY LLVM_SYSTEM_LIBS "${system_libs}")

llvm/lib/WindowsManifest/LLVMBuild.txt

-;===- ./tools/llvm-mt/LLVMBuild.txt ---------------------------*- Conf -*--===;
-;
-;                     The LLVM Compiler Infrastructure
-;
-; This file is distributed under the University of Illinois Open Source
-; License. See LICENSE.TXT for details.
-;
-;===------------------------------------------------------------------------===;
-;
-; This is an LLVMBuild description file for the components in this subdirectory.
-;
-; For more information on the LLVMBuild system, please see:
-;
-;   http://llvm.org/docs/LLVMBuild.html
-;
-;===------------------------------------------------------------------------===;
-
-[component_0]
-type = Tool
-name = llvm-mt
-parent = Tools
-required_libraries = Option Support
+;===- ./lib/WindowsManifest/LLVMBuild.txt ----------------------*- Conf -*--===;
+;
+;                     The LLVM Compiler Infrastructure
+;
+; This file is distributed under the University of Illinois Open Source
+; License. See LICENSE.TXT for details.
+;
+;===------------------------------------------------------------------------===;
+;
+; This is an LLVMBuild description file for the components in this subdirectory.
+;
+; For more information on the LLVMBuild system, please see:
+;
+;   http://llvm.org/docs/LLVMBuild.html
+;
+;===------------------------------------------------------------------------===;
+
+[component_0]
+type = Library
+name = WindowsManifest
+parent = Libraries
+required_libraries = Support

llvm/lib/WindowsManifest/WindowsManifestMerger.cpp

 //===-- WindowsManifestMerger.cpp ------------------------------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===---------------------------------------------------------------------===//
 //
 // This file implements the .manifest merger class.
 //
 //===---------------------------------------------------------------------===//
 
-#include "llvm/Support/WindowsManifestMerger.h"
 #include "llvm/Support/MemoryBuffer.h"
+#include "llvm/WindowsManifest/WindowsManifestMerger.h"
 
 #include <stdarg.h>
 
 namespace llvm {
 
 char WindowsManifestError::ID = 0;
 
 WindowsManifestError::WindowsManifestError(const Twine &Msg) : Msg(Msg.str()) {}

llvm/tools/llvm-mt/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
   Option
   Support
+  WindowsManifest
   )
 
 set(LLVM_TARGET_DEFINITIONS Opts.td)
 
 tablegen(LLVM Opts.inc -gen-opt-parser-defs)
 add_public_tablegen_target(MtTableGen)
 
 add_llvm_tool(llvm-mt
   llvm-mt.cpp
   )

llvm/tools/llvm-mt/LLVMBuild.txt

 ;   http://llvm.org/docs/LLVMBuild.html
 ;
 ;===------------------------------------------------------------------------===;
 
 [component_0]
 type = Tool
 name = llvm-mt
 parent = Tools
-required_libraries = Option Support
+required_libraries = Option Support WindowsManifest

llvm/tools/llvm-mt/llvm-mt.cpp

 #include "llvm/Option/Option.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/FileOutputBuffer.h"
 #include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/PrettyStackTrace.h"
 #include "llvm/Support/Process.h"
 #include "llvm/Support/Signals.h"
-#include "llvm/Support/WindowsManifestMerger.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/WindowsManifest/WindowsManifestMerger.h"
 
 #include <system_error>
 
 using namespace llvm;
 
 namespace {
 
 enum ID {