Fix `llvm-config` to adapt to the install environment.

[DiamondLovesYou]

Summary

This patch does a couple of things:

• Adds a new argument --shared-mode which accepts a list of components and prints whether or not the provided components need to be linked statically or shared.
• Fixes --libnames when CMake BUILD_SHARED_LIBS is used.
• Fixes --libnames, --libs, and --libfiles for dylib when static components aren't installed.
• Fixes --libnames, --libs, --libfiles, and --components to use LLVM_DYLIB_COMPONENTS as the component manifest for dylib linking.
• Uses the host platform's usual convention for filename extensions and such, instead of always defaulting to Unix-izms.

Because I don't own a Mac, I am not able to test the Mac platform dependent stuff locally. If someone would be willing to run a build for me on their machine (unless there's a better option), I'd appreciate it.

[DiamondLovesYou]

Bump.

[brad.king]

Sorry for the delay. Overall the changes look good. The configuration of BuildVariables.inc looks right.

I built and tested on OS X and there is a problem. For versioned shared libraries, CMake places the version number before the .dylib suffix, as in libLLVMObject.3.8.0svn.dylib instead of libLLVMObject.dylib.3.8.0svn. The --libfiles output currently constructs the versioned names with the components in the wrong order. On Linux the order is correct and the named files exist.

[DiamondLovesYou]

In D13198#279173, @brad.king wrote:

I built and tested on OS X and there is a problem. For versioned shared libraries, CMake places the version number before the .dylib suffix, as in libLLVMObject.3.8.0svn.dylib instead of libLLVMObject.dylib.3.8.0svn. The --libfiles output currently constructs the versioned names with the components in the wrong order. On Linux the order is correct and the named files exist.

Thanks for running a build! Does Darwin's autoconf do the same? (EDIT: grammars)

[brad.king]

In D13198#279493, @DiamondLovesYou wrote:

Thanks for running a build! Does Darwin's autoconf do the same? (EDIT: grammars)

With autoconf the library name is libLLVM-3.8svn.dylib and there is a symlink called libLLVM-3.8.0svn.dylib that points to it (which seems reversed, BTW). However, since LLVM_ENABLE_SHARED is hard-coded to OFF for autoconf builds (by this patch) the --libfiles output does not list the dylib anyway.

[DiamondLovesYou]

Mac puts the package revision before the extension.

[brad.king]

After a minor fix this now compiles and gives the proper --libfiles paths on OS X with both CMake and autoconf builds.

tools/llvm-config/llvm-config.cpp

367

Minor fix needed to compile:

-  std::string DyLibName = SharedPrefix + "LLVM";
+  std::string DyLibName = SharedPrefix.str() + "LLVM";

[DiamondLovesYou]

Fix compile issue.

[DiamondLovesYou]

tools/llvm-config/llvm-config.cpp

367

Odd that I did not catch that locally.

[beanz]

We've made some changes recently to LLVM's CMake usage to make it match the output of our autoconf build. The changes were reviewed here: D13841

These changes aren't ideal for a number of reasons, but they make your patches not work correctly on trunk. The main changes are:

• The version is only part of the library path on Linux
• The version is always before the shared library extension (meaning libLLVM-3.8.so not the more-typical libLLVM.so.3.8)

[DiamondLovesYou]

Fixes for recent trunk changes.

[brad.king]

I applied the updated changes on top of r252467 and built all combinations of:

• OS: Linux / OS X
• Build tool: autoconf / cmake
• --enable-shared (LLVM_BUILD_LLVM_DYLIB): ON / OFF

I also tried removing the .a files so that llvm-config would switch to reporting the single shared library instead of the components.

All worked as expected.

[beanz]

LGTM! Thank you for doing this.

-Chris

[chapuni]

llvm/trunk/tools/llvm-config/llvm-config.cpp

331 ↗

(On Diff #39758)

The behavior should be controlled not by target, but by host. Fixed in r260343.
Consider if host=linux, target=i686-win32.

[chapuni]

llvm-config is a tool for host's libraries, regardless of the target.

With cross compilation of clang/llvm, Both llvm-config (host's, aka
configure's --build) and llvm-config.exe should be built.
See also, http://bb.pgr.jp/builders/i686-mingw32-RA-on-linux/builds/7293
It is using i686-mingw32-g++ on linux.

bindings/ocaml/Makefile.ocaml

 ifndef SYSTEM_LLVM_CONFIG
 all-local:: build-deplibs
 clean-local:: clean-deplibs
 install-local:: install-deplibs
 uninstall-local:: uninstall-deplibs
 
 build-deplibs: $(OutputLibs)
 
+$(OcamlDir)/%.so: $(LibDir)/%.so
+  $(Verb) ln -sf $< $@
 $(OcamlDir)/%.a: $(LibDir)/%.a
   $(Verb) ln -sf $< $@
 
 $(OcamlDir)/%.o: $(LibDir)/%.o
   $(Verb) ln -sf $< $@
 
 clean-deplibs:
   $(Verb) $(RM) -f $(OutputLibs)

tools/llvm-config/BuildVariables.inc.in

 #define LLVM_CFLAGS "@LLVM_CFLAGS@"
 #define LLVM_LDFLAGS "@LLVM_LDFLAGS@"
 #define LLVM_CXXFLAGS "@LLVM_CXXFLAGS@"
 #define LLVM_BUILDMODE "@LLVM_BUILDMODE@"
 #define LLVM_LIBDIR_SUFFIX "@LLVM_LIBDIR_SUFFIX@"
 #define LLVM_TARGETS_BUILT "@LLVM_TARGETS_BUILT@"
 #define LLVM_SYSTEM_LIBS "@LLVM_SYSTEM_LIBS@"
 #define LLVM_BUILD_SYSTEM "@LLVM_BUILD_SYSTEM@"
+#define LLVM_ENABLE_DYLIB "@LLVM_BUILD_LLVM_DYLIB@"
+#define LLVM_ENABLE_SHARED "@LLVM_ENABLE_SHARED@"
+#define LLVM_DYLIB_COMPONENTS "@LLVM_DYLIB_COMPONENTS@"

tools/llvm-config/CMakeLists.txt

 set(LLVM_CFLAGS "${CMAKE_C_FLAGS} ${CMAKE_C_FLAGS_${uppercase_CMAKE_BUILD_TYPE}} ${LLVM_DEFINITIONS}")
 set(LLVM_CXXFLAGS "${CMAKE_CXX_FLAGS} ${CMAKE_CXX_FLAGS_${uppercase_CMAKE_BUILD_TYPE}} ${COMPILE_FLAGS} ${LLVM_DEFINITIONS}")
 set(LLVM_BUILD_SYSTEM cmake)
 
 # Use the C++ link flags, since they should be a superset of C link flags.
 set(LLVM_LDFLAGS "${CMAKE_CXX_LINK_FLAGS}")
 set(LLVM_BUILDMODE ${CMAKE_BUILD_TYPE})
 set(LLVM_SYSTEM_LIBS ${SYSTEM_LIBS})
+if(BUILD_SHARED_LIBS)
+  set(LLVM_ENABLE_SHARED ON)
+else()
+  set(LLVM_ENABLE_SHARED OFF)
+endif()
 string(REPLACE ";" " " LLVM_TARGETS_BUILT "${LLVM_TARGETS_TO_BUILD}")
 configure_file(${BUILDVARIABLES_SRCPATH} ${BUILDVARIABLES_OBJPATH} @ONLY)
 
 # Set build-time environment(s).
 add_definitions(-DCMAKE_CFG_INTDIR="${CMAKE_CFG_INTDIR}")
 
 # Add the dependency on the generation step.
 add_file_dependencies(${CMAKE_CURRENT_SOURCE_DIR}/llvm-config.cpp ${BUILDVARIABLES_OBJPATH})

tools/llvm-config/Makefile

$(ObjDir)/BuildVariables.inc: $(BUILDVARIABLES_SRCPATH) Makefile $(ObjDir)/.dir
   $(Verb) $(ECHO) 's/@LLVM_BUILDMODE@/$(subst /,\/,$(BuildMode))/' \
     >> temp.sed
   $(Verb) $(ECHO) 's/@LLVM_LIBDIR_SUFFIX@//' \
     >> temp.sed
   $(Verb) $(ECHO) 's/@LLVM_SYSTEM_LIBS@/$(subst /,\/,$(LLVM_SYSTEM_LIBS))/' \
     >> temp.sed
   $(Verb) $(ECHO) 's/@LLVM_TARGETS_BUILT@/$(subst /,\/,$(TARGETS_TO_BUILD))/' \
     >> temp.sed
+  $(if $(filter-out $(ENABLE_SHARED),0),\
+    $(Verb) $(ECHO) 's/@LLVM_BUILD_LLVM_DYLIB@/ON/',\
+    $(Verb) $(ECHO) 's/@LLVM_BUILD_LLVM_DYLIB@/OFF/') \
+    >> temp.sed
+  $(Verb) $(ECHO) 's/@LLVM_ENABLE_SHARED@/OFF/' \
+    >> temp.sed
+  $(Verb) $(ECHO) 's/@LLVM_DYLIB_COMPONENTS@/all/' \
+    >> temp.sed
   $(Verb) $(ECHO) 's/@LLVM_BUILD_SYSTEM@/autoconf/' \
     >> temp.sed
   $(Verb) $(SED) -f temp.sed < $< > $@
   $(Verb) $(RM) temp.sed
 
 # When cross-compiling, install a version of llvm-config that runs on the host.
 ifeq ($(LLVM_CROSS_COMPILING),1)
 install:: $(DESTDIR)$(PROJ_bindir)
   $(Echo) Installing llvm-config-host
   $(Verb) $(ProgInstall) $(BuildLLVMToolDir)/llvm-config \
     $(DESTDIR)$(PROJ_bindir)/$(program_prefix)llvm-config-host
 endif

tools/llvm-config/llvm-config.cpp

 #include "llvm/Config/config.h"
 #include "llvm/Config/llvm-config.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cstdlib>
 #include <set>
 #include <vector>
+#include <unordered_set>
 
 using namespace llvm;
 
 // Include the build time variables we can report to the user. This is generated
 // at build time from the BuildVariables.inc.in file by the build system.
 #include "BuildVariables.inc"
 
 // Include the component table. This creates an array of struct
 // AvailableComponent entries, which record the component name, library name,
 // and required components for all of the available libraries.
 //
 // Not all components define a library, we also use "library groups" as a way to
 // create entries for pseudo groups like x86 or all-targets.
 #include "LibraryDependencies.inc"
 
 /// \brief Traverse a single component adding to the topological ordering in
 /// \arg RequiredLibs.
 ///
 /// \param Name - The component to traverse.
 /// \param ComponentMap - A prebuilt map of component names to descriptors.
 /// \param VisitedComponents [in] [out] - The set of already visited components.
-/// \param RequiredLibs [out] - The ordered list of required libraries.
+/// \param RequiredLibs [out] - The ordered list of required
+/// libraries.
+/// \param GetComponentNames - Get the component names instead of the
+/// library name.
 static void VisitComponent(StringRef Name,
                            const StringMap<AvailableComponent*> &ComponentMap,
                            std::set<AvailableComponent*> &VisitedComponents,
                            std::vector<StringRef> &RequiredLibs,
-                           bool IncludeNonInstalled) {
+                           bool IncludeNonInstalled, bool GetComponentNames,
+                           const std::string *ActiveLibDir, bool *HasMissing) {
   // Lookup the component.
   AvailableComponent *AC = ComponentMap.lookup(Name);
   assert(AC && "Invalid component name!");
 
   // Add to the visited table.
   if (!VisitedComponents.insert(AC).second) {
     // We are done if the component has already been visited.
     return;
   }
 
   // Only include non-installed components if requested.
   if (!AC->IsInstalled && !IncludeNonInstalled)
     return;
 
   // Otherwise, visit all the dependencies.
   for (unsigned i = 0; AC->RequiredLibraries[i]; ++i) {
     VisitComponent(AC->RequiredLibraries[i], ComponentMap, VisitedComponents,
-                   RequiredLibs, IncludeNonInstalled);
+                   RequiredLibs, IncludeNonInstalled, GetComponentNames,
+                   ActiveLibDir, HasMissing);
+  }
+
+  if (GetComponentNames) {
+    RequiredLibs.push_back(Name);
+    return;
   }
 
   // Add to the required library list.
-  if (AC->Library)
+  if (AC->Library) {
+    if (!IncludeNonInstalled && HasMissing && !*HasMissing && ActiveLibDir) {
+      *HasMissing = !sys::fs::exists(*ActiveLibDir + "/" + AC->Library);
+    }
     RequiredLibs.push_back(AC->Library);
   }
+}
 
 /// \brief Compute the list of required libraries for a given list of
 /// components, in an order suitable for passing to a linker (that is, libraries
 /// appear prior to their dependencies).
 ///
 /// \param Components - The names of the components to find libraries for.
 /// \param RequiredLibs [out] - On return, the ordered list of libraries that
 /// are required to link the given components.
 /// \param IncludeNonInstalled - Whether non-installed components should be
 /// reported.
+/// \param GetComponentNames - True if one would prefer the component names.
 static void ComputeLibsForComponents(const std::vector<StringRef> &Components,
                                      std::vector<StringRef> &RequiredLibs,
-                                     bool IncludeNonInstalled) {
+                                     bool IncludeNonInstalled, bool GetComponentNames,
+                                     const std::string *ActiveLibDir,
+                                     bool *HasMissing) {
   std::set<AvailableComponent*> VisitedComponents;
 
   // Build a map of component names to information.
   StringMap<AvailableComponent*> ComponentMap;
   for (unsigned i = 0; i != array_lengthof(AvailableComponents); ++i) {
     AvailableComponent *AC = &AvailableComponents[i];
     ComponentMap[AC->Name] = AC;
   }
 
   // Visit the components.
   for (unsigned i = 0, e = Components.size(); i != e; ++i) {
     // Users are allowed to provide mixed case component names.
     std::string ComponentLower = Components[i].lower();
 
     // Validate that the user supplied a valid component name.
     if (!ComponentMap.count(ComponentLower)) {
       llvm::errs() << "llvm-config: unknown component name: " << Components[i]
                    << "\n";
       exit(1);
     }
 
     VisitComponent(ComponentLower, ComponentMap, VisitedComponents,
-                   RequiredLibs, IncludeNonInstalled);
+                   RequiredLibs, IncludeNonInstalled, GetComponentNames,
+                   ActiveLibDir, HasMissing);
   }
 
   // The list is now ordered with leafs first, we want the libraries to printed
   // in the reverse order of dependency.
   std::reverse(RequiredLibs.begin(), RequiredLibs.end());
 }
 
 /* *** */
Options:\n\
   --libnames        Bare library names for in-tree builds.\n\
   --libfiles        Fully qualified library filenames for makefile depends.\n\
   --components      List of all possible components.\n\
   --targets-built   List of all targets currently built.\n\
   --host-target     Target triple used to configure LLVM.\n\
   --build-mode      Print build mode of LLVM tree (e.g. Debug or Release).\n\
   --assertion-mode  Print assertion mode of LLVM tree (ON or OFF).\n\
   --build-system    Print the build system used to build LLVM (autoconf or cmake).\n\
+  --shared-mode     Print how the provided components can be collectively linked (`shared` or `static`).\n\
 Typical components:\n\
   all               All LLVM libraries (default).\n\
   engine            Either a native JIT or a bitcode interpreter.\n";
   exit(1);
 }
 
 /// \brief Compute the path to the main executable.
 std::string GetExecutablePath(const char *Argv0) {
   // This just needs to be some symbol in the binary; C++ doesn't
   // allow taking the address of ::main however.
   void *P = (void*) (intptr_t) GetExecutablePath;
   return llvm::sys::fs::getMainExecutable(Argv0, P);
 }
 
+/// \brief Expand the semi-colon delimited LLVM_DYLIB_COMPONENTS into
+/// the full list of components.
+std::vector<StringRef> GetAllDyLibComponents(const bool IsInDevelopmentTree,
+                                             const bool GetComponentNames) {
+  std::vector<StringRef> DyLibComponents;
+  {
+    StringRef DyLibComponentsStr(LLVM_DYLIB_COMPONENTS);
+    size_t Offset = 0;
+    while (true) {
+      const size_t NextOffset = DyLibComponentsStr.find(';', Offset);
+      DyLibComponents.push_back(DyLibComponentsStr.substr(Offset, NextOffset));
+      if (NextOffset == std::string::npos) {
+        break;
+      }
+      Offset = NextOffset + 1;
+    }
+
+    assert(DyLibComponents.size() > 0);
+  }
+
+  std::vector<StringRef> Components;
+  ComputeLibsForComponents(DyLibComponents, Components,
+                           /*IncludeNonInstalled=*/IsInDevelopmentTree,
+                           GetComponentNames, nullptr, nullptr);
+
+  return std::move(Components);
+}
+
 int main(int argc, char **argv) {
   std::vector<StringRef> Components;
   bool PrintLibs = false, PrintLibNames = false, PrintLibFiles = false;
-  bool PrintSystemLibs = false;
+  bool PrintSystemLibs = false, PrintSharedMode = false;
   bool HasAnyOption = false;
 
   // llvm-config is designed to support being run both from a development tree
   // and from an installed path. We try and auto-detect which case we are in so
   // that we can report the correct information when run from a development
   // tree.
   bool IsInDevelopmentTree;
   enum { MakefileStyle, CMakeStyle, CMakeBuildModeStyle } DevelopmentTreeLayout;
#endif
   } else {
     ActivePrefix = CurrentExecPrefix;
     ActiveIncludeDir = ActivePrefix + "/include";
     ActiveBinDir = ActivePrefix + "/bin";
     ActiveLibDir = ActivePrefix + "/lib" + LLVM_LIBDIR_SUFFIX;
     ActiveIncludeOption = "-I" + ActiveIncludeDir;
   }
 
+  /// We only use `shared library` mode in cases where the static library form
+  /// of the components provided are not available; note however that this is
+  /// skipped if we're run from within the build dir. However, once installed,
+  /// we still need to provide correct output when the static archives are
+  /// removed or, as in the case of CMake's `BUILD_SHARED_LIBS`, never present
+  /// in the first place. This can't be done at configure/build time.
+
+  StringRef SharedExt, SharedVersionedExt, SharedDir, SharedPrefix, StaticExt,
+      StaticDir = "lib", StaticPrefix = "lib";
+  const Triple HostTriple(Triple::normalize(LLVM_DEFAULT_TARGET_TRIPLE));
+  if (HostTriple.isOSWindows()) {
+    SharedExt = "dll";
+    SharedVersionedExt = PACKAGE_VERSION ".dll";
+    StaticExt = "a";
+    SharedDir = ActiveBinDir;
+    StaticDir = ActiveLibDir;
+    StaticPrefix = SharedPrefix = "";
+  } else if (HostTriple.isOSDarwin()) {
+    SharedExt = "dylib";
+    SharedVersionedExt = PACKAGE_VERSION ".dylib";
+    StaticExt = "a";
+    StaticDir = SharedDir = ActiveLibDir;
+    StaticPrefix = SharedPrefix = "lib";
+  } else {
+    // default to the unix values:
+    SharedExt = "so";
+    SharedVersionedExt = "so." PACKAGE_VERSION;
+    StaticExt = "a";
+    StaticDir = SharedDir = ActiveLibDir;
+    StaticPrefix = SharedPrefix = "lib";
+  }
+
+  const bool BuiltDyLib = (std::strcmp(LLVM_ENABLE_DYLIB, "ON") == 0);
+
+  enum { CMake, AutoConf } ConfigTool;
+  if (std::strcmp(LLVM_BUILD_SYSTEM, "cmake") == 0) {
+    ConfigTool = CMake;
+  } else {
+    ConfigTool = AutoConf;
+  }
+
+  /// CMake style shared libs, ie each component is in a shared library.
+  const bool BuiltSharedLibs =
+      (ConfigTool == CMake && std::strcmp(LLVM_ENABLE_SHARED, "ON") == 0);
+
+  bool DyLibExists = false;
+  std::string DyLibName = SharedPrefix.str() + "LLVM";
+  if (ConfigTool == CMake) {
+    DyLibName += ".";
+  } else {
+    DyLibName += "-";
+  }
+  DyLibName += SharedVersionedExt;
+  if (BuiltDyLib) {
+    DyLibExists = sys::fs::exists(SharedDir + "/" + DyLibName);
+  }
+
+  /// Get the component's library name without the lib prefix and the
+  /// extension. Returns true if Lib is in a recognized format.
+  auto GetComponentLibraryNameSlice = [&](const StringRef &Lib,
+                                          StringRef &Out) {
+    if (Lib.startswith("lib")) {
+      unsigned FromEnd;
+      if (Lib.endswith(".a")) {
+        FromEnd = 2;
+      } else if (Lib.endswith(SharedExt)) {
+        FromEnd = SharedExt.size() + 1;
+      } else if (Lib.endswith(SharedVersionedExt)) {
+        FromEnd = SharedVersionedExt.size() + 1;
+      } else {
+        FromEnd = 0;
+      }
+
+      if (FromEnd != 0) {
+        Out = Lib.slice(3, Lib.size() - FromEnd);
+        return true;
+      }
+    }
+
+    return false;
+  };
+  /// Maps Unixizms to the host platform.
+  auto GetComponentLibraryFileName = [&](const StringRef &Lib,
+                                         const bool ForceShared) {
+    std::string LibFileName = Lib;
+    StringRef LibName;
+    if (GetComponentLibraryNameSlice(Lib, LibName)) {
+      if (BuiltSharedLibs || ForceShared) {
+        if (ConfigTool == CMake) {
+          LibFileName =
+              (SharedPrefix + LibName + "." + SharedVersionedExt).str();
+        } else {
+          LibFileName = (SharedPrefix + LibName + "." + SharedExt).str();
+        }
+      } else {
+        // default to static
+        LibFileName = (StaticPrefix + LibName + "." + StaticExt).str();
+      }
+    }
+
+    return LibFileName;
+  };
+  /// Get the full path for a possibly shared component library.
+  auto GetComponentLibraryPath = [&](const StringRef &Name,
+                                     const bool ForceShared) {
+    auto LibFileName = GetComponentLibraryFileName(Name, ForceShared);
+    if (BuiltSharedLibs || ForceShared) {
+      return (SharedDir + "/" + LibFileName).str();
+    } else {
+      return (StaticDir + "/" + LibFileName).str();
+    }
+  };
+
   raw_ostream &OS = outs();
   for (int i = 1; i != argc; ++i) {
     StringRef Arg = argv[i];
 
     if (Arg.startswith("-")) {
       HasAnyOption = true;
       if (Arg == "--version") {
         OS << PACKAGE_VERSION << '\n';
if (Arg.startswith("-")) {
         PrintSystemLibs = true;
       } else if (Arg == "--libs") {
         PrintLibs = true;
       } else if (Arg == "--libnames") {
         PrintLibNames = true;
       } else if (Arg == "--libfiles") {
         PrintLibFiles = true;
       } else if (Arg == "--components") {
+        /// If there are missing static archives and a dylib was
+        /// built, print LLVM_DYLIB_COMPONENTS instead of everything
+        /// in the manifest.
+        std::vector<StringRef> Components;
         for (unsigned j = 0; j != array_lengthof(AvailableComponents); ++j) {
           // Only include non-installed components when in a development tree.
           if (!AvailableComponents[j].IsInstalled && !IsInDevelopmentTree)
             continue;
 
+          Components.push_back(AvailableComponents[j].Name);
+          if (AvailableComponents[j].Library && !IsInDevelopmentTree) {
+            if (DyLibExists &&
+                !sys::fs::exists(GetComponentLibraryPath(
+                    AvailableComponents[j].Library, false))) {
+              Components = GetAllDyLibComponents(IsInDevelopmentTree, true);
+              std::sort(Components.begin(), Components.end());
+              break;
+            }
+          }
+        }
+
+        for (unsigned I = 0; I < Components.size(); ++I) {
+          if (I) {
             OS << ' ';
-          OS << AvailableComponents[j].Name;
+          }
+
+          OS << Components[I];
         }
         OS << '\n';
       } else if (Arg == "--targets-built") {
         OS << LLVM_TARGETS_BUILT << '\n';
       } else if (Arg == "--host-target") {
         OS << Triple::normalize(LLVM_DEFAULT_TARGET_TRIPLE) << '\n';
       } else if (Arg == "--build-mode") {
         OS << build_mode << '\n';
       } else if (Arg == "--assertion-mode") {
 #if defined(NDEBUG)
         OS << "OFF\n";
 #else
         OS << "ON\n";
 #endif
       } else if (Arg == "--build-system") {
         OS << LLVM_BUILD_SYSTEM << '\n';
+      } else if (Arg == "--shared-mode") {
+        PrintSharedMode = true;
       } else if (Arg == "--obj-root") {
         OS << ActivePrefix << '\n';
       } else if (Arg == "--src-root") {
         OS << LLVM_SRC_ROOT << '\n';
       } else {
         usage();
       }
     } else {
       Components.push_back(Arg);
     }
   }
 
   if (!HasAnyOption)
     usage();
 
-  if (PrintLibs || PrintLibNames || PrintLibFiles || PrintSystemLibs) {
+  if (PrintLibs || PrintLibNames || PrintLibFiles || PrintSystemLibs ||
+      PrintSharedMode) {
+
+    if (PrintSharedMode && BuiltSharedLibs) {
+      OS << "shared\n";
+      return 0;
+    }
+
     // If no components were specified, default to "all".
     if (Components.empty())
       Components.push_back("all");
 
     // Construct the list of all the required libraries.
     std::vector<StringRef> RequiredLibs;
+    bool HasMissing = false;
     ComputeLibsForComponents(Components, RequiredLibs,
-                             /*IncludeNonInstalled=*/IsInDevelopmentTree);
+                             /*IncludeNonInstalled=*/IsInDevelopmentTree, false,
+                             &ActiveLibDir, &HasMissing);
+
+    if (PrintSharedMode) {
+      std::unordered_set<std::string> FullDyLibComponents;
+      std::vector<StringRef> DyLibComponents =
+          GetAllDyLibComponents(IsInDevelopmentTree, false);
+
+      for (auto &Component : DyLibComponents) {
+        FullDyLibComponents.insert(Component);
+      }
+      DyLibComponents.clear();
+
+      for (auto &Lib : RequiredLibs) {
+        if (!FullDyLibComponents.count(Lib)) {
+          OS << "static\n";
+          return 0;
+        }
+      }
+      FullDyLibComponents.clear();
+
+      if (HasMissing && DyLibExists) {
+        OS << "shared\n";
+        return 0;
+      } else {
+        OS << "static\n";
+        return 0;
+      }
+    }
 
     if (PrintLibs || PrintLibNames || PrintLibFiles) {
-      for (unsigned i = 0, e = RequiredLibs.size(); i != e; ++i) {
-        StringRef Lib = RequiredLibs[i];
-        if (i)
-          OS << ' ';
 
+      auto PrintForLib = [&](const StringRef &Lib, const bool ForceShared) {
         if (PrintLibNames) {
-          OS << Lib;
+          OS << GetComponentLibraryFileName(Lib, ForceShared);
         } else if (PrintLibFiles) {
-          OS << ActiveLibDir << '/' << Lib;
+          OS << GetComponentLibraryPath(Lib, ForceShared);
         } else if (PrintLibs) {
           // If this is a typical library name, include it using -l.
-          if (Lib.startswith("lib") && Lib.endswith(".a")) {
-            OS << "-l" << Lib.slice(3, Lib.size()-2);
-            continue;
+          StringRef LibName;
+          if (Lib.startswith("lib")) {
+            if (GetComponentLibraryNameSlice(Lib, LibName)) {
+              OS << "-l" << LibName;
+            } else {
+              OS << "-l:" << GetComponentLibraryFileName(Lib, ForceShared);
             }
-
+          } else {
             // Otherwise, print the full path.
-          OS << ActiveLibDir << '/' << Lib;
+            OS << GetComponentLibraryPath(Lib, ForceShared);
+          }
+        }
+      };
+
+      if (HasMissing && DyLibExists) {
+        PrintForLib(DyLibName, true);
+      } else {
+        for (unsigned i = 0, e = RequiredLibs.size(); i != e; ++i) {
+          StringRef Lib = RequiredLibs[i];
+          if (i)
+            OS << ' ';
+
+          PrintForLib(Lib, false);
         }
       }
       OS << '\n';
     }
 
     // Print SYSTEM_LIBS after --libs.
     // FIXME: Each LLVM component may have its dependent system libs.
     if (PrintSystemLibs)
       OS << LLVM_SYSTEM_LIBS << '\n';
   } else if (!Components.empty()) {
     errs() << "llvm-config: error: components given, but unused\n\n";
     usage();
   }
 
   return 0;
 }