HostInfoMacOSX: Share the clang resource directory with Swift.

[aprantl]

Summary

Inside Xcode and in Xcode toolchains LLDB is always in lockstep
with the Swift compiler, so it can reuse its Clang resource
directory. This allows LLDB and the Swift compiler to share the
same Clang module cache.

rdar://problem/40039633

[friss]

source/Host/macosx/HostInfoMacOSX.mm

288

As both branches above also resize, I think it would be clearer if this resize was in a final else above rather than on its own. Otherwise this LGTM

include/lldb/Host/macosx/HostInfoMacOSX.h

 
 protected:
   static bool ComputeSupportExeDirectory(FileSpec &file_spec);
   static void ComputeHostArchitectureSupport(ArchSpec &arch_32,
                                              ArchSpec &arch_64);
   static bool ComputeHeaderDirectory(FileSpec &file_spec);
   static bool ComputePythonDirectory(FileSpec &file_spec);
   static bool ComputeClangDirectory(FileSpec &file_spec);
+  static bool ComputeClangDirectory(FileSpec &lldb_shlib_spec,
+                                    FileSpec &file_spec, bool verify);
   static bool ComputeSystemPluginsDirectory(FileSpec &file_spec);
   static bool ComputeUserPluginsDirectory(FileSpec &file_spec);
 };
 }
 
 #endif

source/Host/macosx/HostInfoMacOSX.mm

 #include "lldb/Host/HostInfo.h"
 #include "lldb/Host/macosx/HostInfoMacOSX.h"
 #include "lldb/Utility/Args.h"
 #include "lldb/Utility/Log.h"
 #include "lldb/Utility/SafeMachO.h"
 
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/FileSystem.h"
+#include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
 
 // C++ Includes
 #include <string>
 
 // C inclues
 #include <stdlib.h>
 #include <sys/sysctl.h>
#ifndef LLDB_DISABLE_PYTHON
   file_spec.GetDirectory().SetString(
       llvm::StringRef(raw_path.c_str(), raw_path.size()));
   return true;
 #else
   return false;
 #endif
 }
 
+static bool VerifyClangPath(const llvm::Twine &clang_path) {
+  if (llvm::sys::fs::is_directory(clang_path))
+    return true;
+  Log *log = lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_HOST);
+  if (log)
+    log->Printf("HostInfoMacOSX::ComputeClangDirectory(): "
+                "failed to stat clang resource directory at \"%s\"",
+                clang_path.str().c_str());
+  return false;
+}
+
 bool HostInfoMacOSX::ComputeClangDirectory(FileSpec &file_spec) {
   FileSpec lldb_file_spec;
   if (!GetLLDBPath(lldb::ePathTypeLLDBShlibDir, lldb_file_spec))
     return false;
+  return ComputeClangDirectory(lldb_file_spec, file_spec, true);
+}
 
-  std::string raw_path = lldb_file_spec.GetPath();
+bool HostInfoMacOSX::ComputeClangDirectory(FileSpec &lldb_shlib_spec,
+                                           FileSpec &file_spec, bool verify) {
+  std::string raw_path = lldb_shlib_spec.GetPath();
 
-  size_t framework_pos = raw_path.find("LLDB.framework");
-  if (framework_pos == std::string::npos)
+  auto rev_it = llvm::sys::path::rbegin(raw_path);
+  auto r_end = llvm::sys::path::rend(raw_path);
+
+  // Check for a Posix-style build of LLDB.
+  if (rev_it == r_end || *rev_it != "LLDB.framework")
     return HostInfoPosix::ComputeClangDirectory(file_spec);
-  
-  framework_pos += strlen("LLDB.framework");
-  raw_path.resize(framework_pos);
+  // Inside Xcode and in Xcode toolchains LLDB is always in lockstep
+  // with the Swift compiler, so it can reuse its Clang resource
+  // directory. This allows LLDB and the Swift compiler to share the
+  // same Clang module cache.
+  llvm::SmallString<256> clang_path;
+  const char *swift_clang_resource_dir = "usr/lib/swift/clang";
+  ++rev_it;
+  if (rev_it != r_end && *rev_it == "SharedFrameworks") {
+    // This is the top-level LLDB in the Xcode.app bundle.
+    raw_path.resize(rev_it - r_end);
+    llvm::sys::path::append(clang_path, raw_path,
+                            "Developer/Toolchains/XcodeDefault.xctoolchain",
+                            swift_clang_resource_dir);
+    if (!verify || VerifyClangPath(clang_path)) {
+      file_spec.SetFile(clang_path.c_str(), true);
+      return true;
+    }
+  } else if (rev_it != r_end && *rev_it == "PrivateFrameworks" &&
+             ++rev_it != r_end && ++rev_it != r_end) {
+    // This is LLDB inside an Xcode toolchain.
+    raw_path.resize(rev_it - r_end);
+    llvm::sys::path::append(clang_path, raw_path, swift_clang_resource_dir);
+    if (!verify || VerifyClangPath(clang_path)) {
+      file_spec.SetFile(clang_path.c_str(), true);
+      return true;
+    }
+  }
+
+  // Fall back to the Clang resource directory inside the framework.
+  raw_path.resize(rev_it - r_end);
   raw_path.append("/Resources/Clang");
-  
   file_spec.SetFile(raw_path.c_str(), true);
   return true;
 }
 
 bool HostInfoMacOSX::ComputeSystemPluginsDirectory(FileSpec &file_spec) {
   FileSpec lldb_file_spec;
   if (!GetLLDBPath(lldb::ePathTypeLLDBShlibDir, lldb_file_spec))
     return false;

unittests/Host/CMakeLists.txt

if (CMAKE_SYSTEM_NAME MATCHES "Linux|Android")
   )
 endif()
 
 add_lldb_unittest(HostTests
   ${FILES}
   LINK_LIBS
     lldbCore
     lldbHost
+    lldbUtilityHelpers
   )

unittests/Host/HostInfoTest.cpp

 //===-- HostInfoTest.cpp ----------------------------------------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #include "lldb/Host/HostInfo.h"
+#include "lldb/Host/macosx/HostInfoMacOSX.h"
 #include "lldb/lldb-defines.h"
+#include "TestingSupport/TestUtilities.h"
 #include "gtest/gtest.h"
 
 using namespace lldb_private;
 using namespace llvm;
 
 namespace {
 class HostInfoTest: public ::testing::Test {
   public:
TEST_F(HostInfoTest, GetAugmentedArchSpec) {
   EXPECT_EQ(spec.GetTriple().getOS(), triple.getOS());
   EXPECT_EQ(spec.GetTriple().getVendor(), triple.getVendor());
   EXPECT_EQ(spec.GetTriple().getEnvironment(), triple.getEnvironment());
 
   // Test LLDB_ARCH_DEFAULT
   EXPECT_EQ(HostInfo::GetAugmentedArchSpec(LLDB_ARCH_DEFAULT).GetTriple(),
             HostInfo::GetArchitecture(HostInfo::eArchKindDefault).GetTriple());
 }
+
+
+struct HostInfoMacOSXTest : public HostInfoMacOSX {
+  static std::string ComputeClangDir(std::string lldb_shlib_path,
+                                     bool verify = false) {
+    FileSpec clang_dir;
+    FileSpec lldb_shlib_spec(lldb_shlib_path, false);
+    ComputeClangDirectory(lldb_shlib_spec, clang_dir, verify);
+    return clang_dir.GetPath();
+  }
+};
+
+
+TEST_F(HostInfoTest, MacOSX) {
+  // This returns whatever the POSIX fallback returns.
+  std::string posix = "/usr/lib/liblldb.dylib";
+  EXPECT_FALSE(HostInfoMacOSXTest::ComputeClangDir(posix).empty());
+
+  std::string xcode =
+    "/Applications/Xcode.app/Contents/SharedFrameworks/LLDB.framework";
+  std::string xcode_clang =
+    "/Applications/Xcode.app/Contents/Developer/Toolchains/"
+    "XcodeDefault.xctoolchain/usr/lib/swift/clang";
+  EXPECT_EQ(HostInfoMacOSXTest::ComputeClangDir(xcode), xcode_clang);
+
+  std::string toolchain =
+      "/Applications/Xcode.app/Contents/Developer/Toolchains/"
+      "Swift-4.1-development-snapshot.xctoolchain/System/Library/"
+      "PrivateFrameworks/LLDB.framework";
+  std::string toolchain_clang =
+      "/Applications/Xcode.app/Contents/Developer/Toolchains/"
+      "Swift-4.1-development-snapshot.xctoolchain/usr/lib/swift/clang";
+  EXPECT_EQ(HostInfoMacOSXTest::ComputeClangDir(toolchain), toolchain_clang);
+
+  // Test that a bogus path is detected.
+  EXPECT_NE(HostInfoMacOSXTest::ComputeClangDir(GetInputFilePath(xcode), true),
+            HostInfoMacOSXTest::ComputeClangDir(GetInputFilePath(xcode)));
+}