From 2665e747d5866480f2f704d5a72fe016d258f200 Mon Sep 17 00:00:00 2001
From: Michael Buch <michaelbuch12@gmail.com>
Date: Tue, 25 Feb 2025 13:11:33 +0000
Subject: [PATCH 1/8] [lldb]HostInfoMacOSX] Search CommandLineTools directory
 when looking up SDK paths

`GetSDKRoot` uses `xcrun` to find an SDK root path for a given SDK
version string. But if the SDK doesn't exist in the Xcode installations,
but instead lives in the `CommandLineTools`, `xcrun` will fail to find
it. Negative searches for an SDK path cost a lot (a few seconds) each
time `xcrun` is invoked. We do cache negative results in
`find_cached_path` inside LLDB, but we would still pay the price on
every new debug session the first time we evaluate an expression. This
doesn't only cause a noticable delay in running the expression, but also
generates following error:
```
error: Error while searching for Xcode SDK: timed out waiting for shell command to complete
(int) $0 = 42
```

To avoid this `xcrun` penalty, we search `CommandLineTools` for a
matching SDK ourselves, and only if we don't find it, do we fall back to
calling `xcrun`.

rdar://113619904
rdar://113619723
---
 lldb/include/lldb/Host/FileSystem.h           |  5 +-
 .../Host/macosx/objcxx/HostInfoMacOSX.mm      | 60 +++++++++++++++++++
 2 files changed, 63 insertions(+), 2 deletions(-)

diff --git a/lldb/include/lldb/Host/FileSystem.h b/lldb/include/lldb/Host/FileSystem.h
index 640f3846e448c..4128d7b012041 100644
--- a/lldb/include/lldb/Host/FileSystem.h
+++ b/lldb/include/lldb/Host/FileSystem.h
@@ -183,8 +183,9 @@ class FileSystem {
     eEnumerateDirectoryResultQuit
   };
 
-  typedef EnumerateDirectoryResult (*EnumerateDirectoryCallbackType)(
-      void *baton, llvm::sys::fs::file_type file_type, llvm::StringRef);
+  typedef std::function<EnumerateDirectoryResult(
+      void *baton, llvm::sys::fs::file_type file_type, llvm::StringRef)>
+      EnumerateDirectoryCallbackType;
 
   typedef std::function<EnumerateDirectoryResult(
       llvm::sys::fs::file_type file_type, llvm::StringRef)>
diff --git a/lldb/source/Host/macosx/objcxx/HostInfoMacOSX.mm b/lldb/source/Host/macosx/objcxx/HostInfoMacOSX.mm
index 6e924fdc684cf..a94fd3b57f9d6 100644
--- a/lldb/source/Host/macosx/objcxx/HostInfoMacOSX.mm
+++ b/lldb/source/Host/macosx/objcxx/HostInfoMacOSX.mm
@@ -15,11 +15,14 @@
 #include "lldb/Utility/Log.h"
 #include "lldb/Utility/Timer.h"
 
+#include "clang/Basic/DarwinSDKInfo.h"
 #include "llvm/ADT/ScopeExit.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringMap.h"
+#include "llvm/Support/Error.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
+#include "llvm/Support/VersionTuple.h"
 #include "llvm/Support/raw_ostream.h"
 
 // C++ Includes
@@ -569,10 +572,52 @@ static bool ResolveAndVerifyCandidateSupportDir(FileSpec &path) {
     cache.insert({key, {error, true}});
     return llvm::createStringError(llvm::inconvertibleErrorCode(), error);
   }
+
+  if (path_or_err->empty())
+    return llvm::createStringError("Empty path determined for '%s'",
+                                   key.data());
+
   auto it_new = cache.insert({key, {*path_or_err, false}});
   return it_new.first->second.str;
 }
 
+static llvm::Expected<std::string>
+GetCommandLineToolsSDKRoot(llvm::VersionTuple version) {
+  std::string clt_root_dir;
+  FileSystem::Instance().EnumerateDirectory(
+      "/Library/Developer/CommandLineTools/SDKs/", /*find_directories=*/true,
+      /*find_files=*/false, /*find_other=*/false,
+      [&](void *baton, llvm::sys::fs::file_type file_type,
+          llvm::StringRef name) {
+        assert(file_type == llvm::sys::fs::file_type::directory_file);
+
+        if (!name.ends_with(".sdk"))
+          return FileSystem::eEnumerateDirectoryResultNext;
+
+        llvm::Expected<std::optional<clang::DarwinSDKInfo>> sdk_info =
+            clang::parseDarwinSDKInfo(
+                *FileSystem::Instance().GetVirtualFileSystem(), name);
+        if (!sdk_info) {
+          LLDB_LOG_ERROR(GetLog(LLDBLog::Expressions), sdk_info.takeError(),
+                         "Error while parsing {1}: {0}", name);
+          return FileSystem::eEnumerateDirectoryResultNext;
+        }
+
+        if (!*sdk_info)
+          return FileSystem::eEnumerateDirectoryResultNext;
+
+        if (version == (*sdk_info)->getVersion()) {
+          clt_root_dir = name;
+          return FileSystem::eEnumerateDirectoryResultQuit;
+        }
+
+        return FileSystem::eEnumerateDirectoryResultNext;
+      },
+      /*baton=*/nullptr);
+
+  return clt_root_dir;
+}
+
 llvm::Expected<llvm::StringRef> HostInfoMacOSX::GetSDKRoot(SDKOptions options) {
   static llvm::StringMap<ErrorOrPath> g_sdk_path;
   static std::mutex g_sdk_path_mutex;
@@ -581,6 +626,21 @@ static bool ResolveAndVerifyCandidateSupportDir(FileSpec &path) {
                                    "XcodeSDK not specified");
   XcodeSDK sdk = *options.XcodeSDKSelection;
   auto key = sdk.GetString();
+
+  // xcrun doesn't search SDKs in the CommandLineTools (CLT) directory. So if
+  // a program was compiled against a CLT SDK, but that SDK wasn't present in
+  // any of the Xcode installations, then xcrun would fail to find the SDK
+  // (which is expensive). To avoid this we first try to find the specified SDK
+  // in the CLT directory.
+  auto clt_root_dir = find_cached_path(g_sdk_path, g_sdk_path_mutex, key, [&] {
+    return GetCommandLineToolsSDKRoot(sdk.GetVersion());
+  });
+
+  if (clt_root_dir)
+    return clt_root_dir;
+  else
+    llvm::consumeError(clt_root_dir.takeError());
+
   return find_cached_path(g_sdk_path, g_sdk_path_mutex, key, [&](){
     return GetXcodeSDK(sdk);
   });

From 96ae6dbf77692fb063eae65a15730997b3f65303 Mon Sep 17 00:00:00 2001
From: Michael Buch <michaelbuch12@gmail.com>
Date: Fri, 28 Feb 2025 12:55:03 +0000
Subject: [PATCH 2/8] fixup! if path at DW_AT_LLVM_sysroot exists, use it

---
 lldb/include/lldb/Host/FileSystem.h           |  5 +-
 lldb/include/lldb/Symbol/SymbolFile.h         |  6 +-
 lldb/include/lldb/Symbol/SymbolFileOnDemand.h |  2 +-
 lldb/include/lldb/Target/Platform.h           | 24 +-------
 .../Host/macosx/objcxx/HostInfoMacOSX.mm      | 60 -------------------
 .../Clang/ClangExpressionParser.cpp           |  8 +--
 .../Platform/MacOSX/PlatformDarwin.cpp        | 56 ++++-------------
 .../Plugins/Platform/MacOSX/PlatformDarwin.h  |  6 +-
 .../SymbolFile/DWARF/SymbolFileDWARF.cpp      | 32 ++++++----
 .../SymbolFile/DWARF/SymbolFileDWARF.h        |  3 +-
 .../DWARF/SymbolFileDWARFDebugMap.cpp         |  3 +-
 .../DWARF/SymbolFileDWARFDebugMap.h           |  3 +-
 lldb/source/Symbol/SymbolFileOnDemand.cpp     |  7 ++-
 .../SymbolFile/DWARF/XcodeSDKModuleTests.cpp  |  2 +-
 14 files changed, 54 insertions(+), 163 deletions(-)

diff --git a/lldb/include/lldb/Host/FileSystem.h b/lldb/include/lldb/Host/FileSystem.h
index 4128d7b012041..640f3846e448c 100644
--- a/lldb/include/lldb/Host/FileSystem.h
+++ b/lldb/include/lldb/Host/FileSystem.h
@@ -183,9 +183,8 @@ class FileSystem {
     eEnumerateDirectoryResultQuit
   };
 
-  typedef std::function<EnumerateDirectoryResult(
-      void *baton, llvm::sys::fs::file_type file_type, llvm::StringRef)>
-      EnumerateDirectoryCallbackType;
+  typedef EnumerateDirectoryResult (*EnumerateDirectoryCallbackType)(
+      void *baton, llvm::sys::fs::file_type file_type, llvm::StringRef);
 
   typedef std::function<EnumerateDirectoryResult(
       llvm::sys::fs::file_type file_type, llvm::StringRef)>
diff --git a/lldb/include/lldb/Symbol/SymbolFile.h b/lldb/include/lldb/Symbol/SymbolFile.h
index 837b922ae77f7..d417899e97084 100644
--- a/lldb/include/lldb/Symbol/SymbolFile.h
+++ b/lldb/include/lldb/Symbol/SymbolFile.h
@@ -32,6 +32,7 @@
 #include <mutex>
 #include <optional>
 #include <unordered_map>
+#include <utility>
 
 #if defined(LLDB_CONFIGURATION_DEBUG)
 #define ASSERT_MODULE_LOCK(expr) (expr->AssertModuleLock())
@@ -148,7 +149,10 @@ class SymbolFile : public PluginInterface {
 
   virtual lldb::LanguageType ParseLanguage(CompileUnit &comp_unit) = 0;
   /// Return the Xcode SDK comp_unit was compiled against.
-  virtual XcodeSDK ParseXcodeSDK(CompileUnit &comp_unit) { return {}; }
+  virtual std::pair<XcodeSDK, std::string>
+  ParseXcodeSDK(CompileUnit &comp_unit) {
+    return {};
+  }
 
   /// This function exists because SymbolFileDWARFDebugMap may extra compile
   /// units which aren't exposed as "real" compile units. In every other
diff --git a/lldb/include/lldb/Symbol/SymbolFileOnDemand.h b/lldb/include/lldb/Symbol/SymbolFileOnDemand.h
index 7a366bfabec86..77e7b50539043 100644
--- a/lldb/include/lldb/Symbol/SymbolFileOnDemand.h
+++ b/lldb/include/lldb/Symbol/SymbolFileOnDemand.h
@@ -65,7 +65,7 @@ class SymbolFileOnDemand : public lldb_private::SymbolFile {
   lldb::LanguageType
   ParseLanguage(lldb_private::CompileUnit &comp_unit) override;
 
-  lldb_private::XcodeSDK
+  std::pair<lldb_private::XcodeSDK, std::string>
   ParseXcodeSDK(lldb_private::CompileUnit &comp_unit) override;
 
   void InitializeObject() override;
diff --git a/lldb/include/lldb/Target/Platform.h b/lldb/include/lldb/Target/Platform.h
index a702abb540fd9..5f85caeb790ba 100644
--- a/lldb/include/lldb/Target/Platform.h
+++ b/lldb/include/lldb/Target/Platform.h
@@ -438,25 +438,6 @@ class Platform : public PluginInterface {
     return lldb_private::ConstString();
   }
 
-  /// Search each CU associated with the specified 'module' for
-  /// the SDK paths the CUs were compiled against. In the presence
-  /// of different SDKs, we try to pick the most appropriate one
-  /// using \ref XcodeSDK::Merge.
-  ///
-  /// \param[in] module Module whose debug-info CUs to parse for
-  ///                   which SDK they were compiled against.
-  ///
-  /// \returns If successful, returns a pair of a parsed XcodeSDK
-  ///          object and a boolean that is 'true' if we encountered
-  ///          a conflicting combination of SDKs when parsing the CUs
-  ///          (e.g., a public and internal SDK).
-  virtual llvm::Expected<std::pair<XcodeSDK, bool>>
-  GetSDKPathFromDebugInfo(Module &module) {
-    return llvm::createStringError(
-        llvm::formatv("{0} not implemented for '{1}' platform.",
-                      LLVM_PRETTY_FUNCTION, GetName()));
-  }
-
   /// Returns the full path of the most appropriate SDK for the
   /// specified 'module'. This function gets this path by parsing
   /// debug-info (see \ref `GetSDKPathFromDebugInfo`).
@@ -477,8 +458,9 @@ class Platform : public PluginInterface {
   ///
   /// \param[in] unit The CU
   ///
-  /// \returns A parsed XcodeSDK object if successful, an Error otherwise. 
-  virtual llvm::Expected<XcodeSDK> GetSDKPathFromDebugInfo(CompileUnit &unit) {
+  /// \returns A parsed XcodeSDK object if successful, an Error otherwise.
+  virtual llvm::Expected<std::pair<XcodeSDK, std::string>>
+  GetSDKPathFromDebugInfo(CompileUnit &unit) {
     return llvm::createStringError(
         llvm::formatv("{0} not implemented for '{1}' platform.",
                       LLVM_PRETTY_FUNCTION, GetName()));
diff --git a/lldb/source/Host/macosx/objcxx/HostInfoMacOSX.mm b/lldb/source/Host/macosx/objcxx/HostInfoMacOSX.mm
index a94fd3b57f9d6..6e924fdc684cf 100644
--- a/lldb/source/Host/macosx/objcxx/HostInfoMacOSX.mm
+++ b/lldb/source/Host/macosx/objcxx/HostInfoMacOSX.mm
@@ -15,14 +15,11 @@
 #include "lldb/Utility/Log.h"
 #include "lldb/Utility/Timer.h"
 
-#include "clang/Basic/DarwinSDKInfo.h"
 #include "llvm/ADT/ScopeExit.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringMap.h"
-#include "llvm/Support/Error.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
-#include "llvm/Support/VersionTuple.h"
 #include "llvm/Support/raw_ostream.h"
 
 // C++ Includes
@@ -572,52 +569,10 @@ static bool ResolveAndVerifyCandidateSupportDir(FileSpec &path) {
     cache.insert({key, {error, true}});
     return llvm::createStringError(llvm::inconvertibleErrorCode(), error);
   }
-
-  if (path_or_err->empty())
-    return llvm::createStringError("Empty path determined for '%s'",
-                                   key.data());
-
   auto it_new = cache.insert({key, {*path_or_err, false}});
   return it_new.first->second.str;
 }
 
-static llvm::Expected<std::string>
-GetCommandLineToolsSDKRoot(llvm::VersionTuple version) {
-  std::string clt_root_dir;
-  FileSystem::Instance().EnumerateDirectory(
-      "/Library/Developer/CommandLineTools/SDKs/", /*find_directories=*/true,
-      /*find_files=*/false, /*find_other=*/false,
-      [&](void *baton, llvm::sys::fs::file_type file_type,
-          llvm::StringRef name) {
-        assert(file_type == llvm::sys::fs::file_type::directory_file);
-
-        if (!name.ends_with(".sdk"))
-          return FileSystem::eEnumerateDirectoryResultNext;
-
-        llvm::Expected<std::optional<clang::DarwinSDKInfo>> sdk_info =
-            clang::parseDarwinSDKInfo(
-                *FileSystem::Instance().GetVirtualFileSystem(), name);
-        if (!sdk_info) {
-          LLDB_LOG_ERROR(GetLog(LLDBLog::Expressions), sdk_info.takeError(),
-                         "Error while parsing {1}: {0}", name);
-          return FileSystem::eEnumerateDirectoryResultNext;
-        }
-
-        if (!*sdk_info)
-          return FileSystem::eEnumerateDirectoryResultNext;
-
-        if (version == (*sdk_info)->getVersion()) {
-          clt_root_dir = name;
-          return FileSystem::eEnumerateDirectoryResultQuit;
-        }
-
-        return FileSystem::eEnumerateDirectoryResultNext;
-      },
-      /*baton=*/nullptr);
-
-  return clt_root_dir;
-}
-
 llvm::Expected<llvm::StringRef> HostInfoMacOSX::GetSDKRoot(SDKOptions options) {
   static llvm::StringMap<ErrorOrPath> g_sdk_path;
   static std::mutex g_sdk_path_mutex;
@@ -626,21 +581,6 @@ static bool ResolveAndVerifyCandidateSupportDir(FileSpec &path) {
                                    "XcodeSDK not specified");
   XcodeSDK sdk = *options.XcodeSDKSelection;
   auto key = sdk.GetString();
-
-  // xcrun doesn't search SDKs in the CommandLineTools (CLT) directory. So if
-  // a program was compiled against a CLT SDK, but that SDK wasn't present in
-  // any of the Xcode installations, then xcrun would fail to find the SDK
-  // (which is expensive). To avoid this we first try to find the specified SDK
-  // in the CLT directory.
-  auto clt_root_dir = find_cached_path(g_sdk_path, g_sdk_path_mutex, key, [&] {
-    return GetCommandLineToolsSDKRoot(sdk.GetVersion());
-  });
-
-  if (clt_root_dir)
-    return clt_root_dir;
-  else
-    llvm::consumeError(clt_root_dir.takeError());
-
   return find_cached_path(g_sdk_path, g_sdk_path_mutex, key, [&](){
     return GetXcodeSDK(sdk);
   });
diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
index f1573bae2651b..e980c914afd1a 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
+++ b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
@@ -336,13 +336,7 @@ sdkSupportsBuiltinModules(lldb_private::Target &target) {
   if (!platform_sp)
     return llvm::createStringError("No Platform plugin found on target.");
 
-  auto sdk_or_err = platform_sp->GetSDKPathFromDebugInfo(*module_sp);
-  if (!sdk_or_err)
-    return sdk_or_err.takeError();
-
-  // Use the SDK path from debug-info to find a local matching SDK directory.
-  auto sdk_path_or_err =
-      HostInfo::GetSDKRoot(HostInfo::SDKOptions{std::move(sdk_or_err->first)});
+  auto sdk_path_or_err = platform_sp->ResolveSDKPathFromDebugInfo(*module_sp);
   if (!sdk_path_or_err)
     return sdk_path_or_err.takeError();
 
diff --git a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp
index 51e9a6d81b839..ef10481503efe 100644
--- a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp
+++ b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp
@@ -1386,57 +1386,18 @@ llvm::Triple::OSType PlatformDarwin::GetHostOSType() {
 #endif // __APPLE__
 }
 
-llvm::Expected<std::pair<XcodeSDK, bool>>
-PlatformDarwin::GetSDKPathFromDebugInfo(Module &module) {
-  SymbolFile *sym_file = module.GetSymbolFile();
-  if (!sym_file)
-    return llvm::createStringError(
-        llvm::inconvertibleErrorCode(),
-        llvm::formatv("No symbol file available for module '{0}'",
-                      module.GetFileSpec().GetFilename().AsCString("")));
-
-  bool found_public_sdk = false;
-  bool found_internal_sdk = false;
-  XcodeSDK merged_sdk;
-  for (unsigned i = 0; i < sym_file->GetNumCompileUnits(); ++i) {
-    if (auto cu_sp = sym_file->GetCompileUnitAtIndex(i)) {
-      auto cu_sdk = sym_file->ParseXcodeSDK(*cu_sp);
-      bool is_internal_sdk = cu_sdk.IsAppleInternalSDK();
-      found_public_sdk |= !is_internal_sdk;
-      found_internal_sdk |= is_internal_sdk;
-
-      merged_sdk.Merge(cu_sdk);
-    }
-  }
-
-  const bool found_mismatch = found_internal_sdk && found_public_sdk;
-
-  return std::pair{std::move(merged_sdk), found_mismatch};
-}
-
 llvm::Expected<std::string>
 PlatformDarwin::ResolveSDKPathFromDebugInfo(Module &module) {
-  auto sdk_or_err = GetSDKPathFromDebugInfo(module);
-  if (!sdk_or_err)
+  auto cu_sp = module.GetCompileUnitAtIndex(0);
+  if (!cu_sp)
     return llvm::createStringError(
-        llvm::inconvertibleErrorCode(),
-        llvm::formatv("Failed to parse SDK path from debug-info: {0}",
-                      llvm::toString(sdk_or_err.takeError())));
-
-  auto [sdk, _] = std::move(*sdk_or_err);
-
-  auto path_or_err = HostInfo::GetSDKRoot(HostInfo::SDKOptions{sdk});
-  if (!path_or_err)
-    return llvm::createStringError(
-        llvm::inconvertibleErrorCode(),
-        llvm::formatv("Error while searching for SDK (XcodeSDK '{0}'): {1}",
-                      sdk.GetString(),
-                      llvm::toString(path_or_err.takeError())));
+        "Couldn't retrieve compile-unit for module '%s'.",
+        module.GetObjectName().AsCString("<null>"));
 
-  return path_or_err->str();
+  return ResolveSDKPathFromDebugInfo(*cu_sp);
 }
 
-llvm::Expected<XcodeSDK>
+llvm::Expected<std::pair<XcodeSDK, std::string>>
 PlatformDarwin::GetSDKPathFromDebugInfo(CompileUnit &unit) {
   ModuleSP module_sp = unit.CalculateSymbolContextModule();
   if (!module_sp)
@@ -1459,7 +1420,10 @@ PlatformDarwin::ResolveSDKPathFromDebugInfo(CompileUnit &unit) {
         llvm::formatv("Failed to parse SDK path from debug-info: {0}",
                       llvm::toString(sdk_or_err.takeError())));
 
-  auto sdk = std::move(*sdk_or_err);
+  auto [sdk, sysroot] = std::move(*sdk_or_err);
+
+  if (FileSystem::Instance().Exists(sysroot))
+    return sysroot;
 
   auto path_or_err = HostInfo::GetSDKRoot(HostInfo::SDKOptions{sdk});
   if (!path_or_err)
diff --git a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.h b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.h
index e2d4cb6726d58..0a4e6c9938c17 100644
--- a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.h
+++ b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.h
@@ -124,13 +124,11 @@ class PlatformDarwin : public PlatformPOSIX {
   /// located in.
   static FileSpec GetCurrentCommandLineToolsDirectory();
 
-  llvm::Expected<std::pair<XcodeSDK, bool>>
-  GetSDKPathFromDebugInfo(Module &module) override;
-
   llvm::Expected<std::string>
   ResolveSDKPathFromDebugInfo(Module &module) override;
 
-  llvm::Expected<XcodeSDK> GetSDKPathFromDebugInfo(CompileUnit &unit) override;
+  llvm::Expected<std::pair<XcodeSDK, std::string>>
+  GetSDKPathFromDebugInfo(CompileUnit &unit) override;
 
   llvm::Expected<std::string>
   ResolveSDKPathFromDebugInfo(CompileUnit &unit) override;
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
index a96757afabddf..714586a4e2468 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -982,7 +982,8 @@ lldb::LanguageType SymbolFileDWARF::ParseLanguage(CompileUnit &comp_unit) {
     return eLanguageTypeUnknown;
 }
 
-XcodeSDK SymbolFileDWARF::ParseXcodeSDK(CompileUnit &comp_unit) {
+std::pair<XcodeSDK, std::string>
+SymbolFileDWARF::ParseXcodeSDK(CompileUnit &comp_unit) {
   std::lock_guard<std::recursive_mutex> guard(GetModuleMutex());
   DWARFUnit *dwarf_cu = GetDWARFCompileUnit(&comp_unit);
   if (!dwarf_cu)
@@ -993,21 +994,26 @@ XcodeSDK SymbolFileDWARF::ParseXcodeSDK(CompileUnit &comp_unit) {
   const char *sdk = cu_die.GetAttributeValueAsString(DW_AT_APPLE_sdk, nullptr);
   if (!sdk)
     return {};
-  const char *sysroot =
+  std::string sysroot =
       cu_die.GetAttributeValueAsString(DW_AT_LLVM_sysroot, "");
-  // Register the sysroot path remapping with the module belonging to
-  // the CU as well as the one belonging to the symbol file. The two
-  // would be different if this is an OSO object and module is the
-  // corresponding debug map, in which case both should be updated.
-  ModuleSP module_sp = comp_unit.GetModule();
-  if (module_sp)
-    module_sp->RegisterXcodeSDK(sdk, sysroot);
 
-  ModuleSP local_module_sp = m_objfile_sp->GetModule();
-  if (local_module_sp && local_module_sp != module_sp)
-    local_module_sp->RegisterXcodeSDK(sdk, sysroot);
+  // RegisterXcodeSDK calls into xcrun which is not aware of CLT, which is
+  // expensive.
+  if (sysroot.find("/Library/Developer/CommandLineTools/SDKs") != 0) {
+    // Register the sysroot path remapping with the module belonging to
+    // the CU as well as the one belonging to the symbol file. The two
+    // would be different if this is an OSO object and module is the
+    // corresponding debug map, in which case both should be updated.
+    ModuleSP module_sp = comp_unit.GetModule();
+    if (module_sp)
+      module_sp->RegisterXcodeSDK(sdk, sysroot);
+
+    ModuleSP local_module_sp = m_objfile_sp->GetModule();
+    if (local_module_sp && local_module_sp != module_sp)
+      local_module_sp->RegisterXcodeSDK(sdk, sysroot);
+  }
 
-  return {sdk};
+  return std::pair{XcodeSDK{sdk}, std::move(sysroot)};
 }
 
 size_t SymbolFileDWARF::ParseFunctions(CompileUnit &comp_unit) {
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
index 7309f7a86b659..8f7f84aff355d 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
@@ -110,7 +110,8 @@ class SymbolFileDWARF : public SymbolFileCommon {
 
   lldb::LanguageType ParseLanguage(CompileUnit &comp_unit) override;
 
-  XcodeSDK ParseXcodeSDK(CompileUnit &comp_unit) override;
+  std::pair<XcodeSDK, std::string>
+  ParseXcodeSDK(CompileUnit &comp_unit) override;
 
   size_t ParseFunctions(CompileUnit &comp_unit) override;
 
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
index 0ecf47a3c7869..eb2db68dd9435 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
@@ -673,7 +673,8 @@ SymbolFileDWARFDebugMap::ParseLanguage(CompileUnit &comp_unit) {
   return eLanguageTypeUnknown;
 }
 
-XcodeSDK SymbolFileDWARFDebugMap::ParseXcodeSDK(CompileUnit &comp_unit) {
+std::pair<XcodeSDK, std::string>
+SymbolFileDWARFDebugMap::ParseXcodeSDK(CompileUnit &comp_unit) {
   std::lock_guard<std::recursive_mutex> guard(GetModuleMutex());
   SymbolFileDWARF *oso_dwarf = GetSymbolFile(comp_unit);
   if (oso_dwarf)
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h
index df41d6a2a4e42..9f1fe9abe002b 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h
@@ -64,7 +64,8 @@ class SymbolFileDWARFDebugMap : public SymbolFileCommon {
 
   // Compile Unit function calls
   lldb::LanguageType ParseLanguage(CompileUnit &comp_unit) override;
-  XcodeSDK ParseXcodeSDK(CompileUnit &comp_unit) override;
+  std::pair<XcodeSDK, std::string>
+  ParseXcodeSDK(CompileUnit &comp_unit) override;
   llvm::SmallSet<lldb::LanguageType, 4>
   ParseAllLanguages(CompileUnit &comp_unit) override;
   size_t ParseFunctions(CompileUnit &comp_unit) override;
diff --git a/lldb/source/Symbol/SymbolFileOnDemand.cpp b/lldb/source/Symbol/SymbolFileOnDemand.cpp
index 94979b2fb1c22..94c6e01d83d1d 100644
--- a/lldb/source/Symbol/SymbolFileOnDemand.cpp
+++ b/lldb/source/Symbol/SymbolFileOnDemand.cpp
@@ -58,17 +58,18 @@ lldb::LanguageType SymbolFileOnDemand::ParseLanguage(CompileUnit &comp_unit) {
   return m_sym_file_impl->ParseLanguage(comp_unit);
 }
 
-XcodeSDK SymbolFileOnDemand::ParseXcodeSDK(CompileUnit &comp_unit) {
+std::pair<XcodeSDK, std::string>
+SymbolFileOnDemand::ParseXcodeSDK(CompileUnit &comp_unit) {
   if (!m_debug_info_enabled) {
     Log *log = GetLog();
     LLDB_LOG(log, "[{0}] {1} is skipped", GetSymbolFileName(), __FUNCTION__);
     XcodeSDK defaultValue{};
     if (log) {
-      XcodeSDK sdk = m_sym_file_impl->ParseXcodeSDK(comp_unit);
+      auto [sdk, sysroot] = m_sym_file_impl->ParseXcodeSDK(comp_unit);
       if (!(sdk == defaultValue))
         LLDB_LOG(log, "SDK {0} would return if hydrated.", sdk.GetString());
     }
-    return defaultValue;
+    return {defaultValue, {}};
   }
   return m_sym_file_impl->ParseXcodeSDK(comp_unit);
 }
diff --git a/lldb/unittests/SymbolFile/DWARF/XcodeSDKModuleTests.cpp b/lldb/unittests/SymbolFile/DWARF/XcodeSDKModuleTests.cpp
index fc008ca7011e4..bda69815ad388 100644
--- a/lldb/unittests/SymbolFile/DWARF/XcodeSDKModuleTests.cpp
+++ b/lldb/unittests/SymbolFile/DWARF/XcodeSDKModuleTests.cpp
@@ -118,7 +118,7 @@ TEST_F(XcodeSDKModuleTests, TestModuleGetXcodeSDK) {
   ASSERT_TRUE(static_cast<bool>(comp_unit.get()));
   ModuleSP module = t.GetModule();
   ASSERT_EQ(module->GetSourceMappingList().GetSize(), 0u);
-  XcodeSDK sdk = sym_file.ParseXcodeSDK(*comp_unit);
+  auto [sdk, sysroot] = sym_file.ParseXcodeSDK(*comp_unit);
   ASSERT_EQ(sdk.GetType(), XcodeSDK::Type::MacOSX);
   ASSERT_EQ(module->GetSourceMappingList().GetSize(), 1u);
 }

From 4d7c510e79ac33ed3bd72b073f7876b51735b338 Mon Sep 17 00:00:00 2001
From: Michael Buch <michaelbuch12@gmail.com>
Date: Mon, 3 Mar 2025 12:31:47 +0000
Subject: [PATCH 3/8] Revert "fixup! if path at DW_AT_LLVM_sysroot exists, use
 it"

This reverts commit 96ae6dbf77692fb063eae65a15730997b3f65303.
---
 lldb/include/lldb/Host/FileSystem.h           |  5 +-
 lldb/include/lldb/Symbol/SymbolFile.h         |  6 +-
 lldb/include/lldb/Symbol/SymbolFileOnDemand.h |  2 +-
 lldb/include/lldb/Target/Platform.h           | 24 +++++++-
 .../Host/macosx/objcxx/HostInfoMacOSX.mm      | 60 +++++++++++++++++++
 .../Clang/ClangExpressionParser.cpp           |  8 ++-
 .../Platform/MacOSX/PlatformDarwin.cpp        | 56 +++++++++++++----
 .../Plugins/Platform/MacOSX/PlatformDarwin.h  |  6 +-
 .../SymbolFile/DWARF/SymbolFileDWARF.cpp      | 32 ++++------
 .../SymbolFile/DWARF/SymbolFileDWARF.h        |  3 +-
 .../DWARF/SymbolFileDWARFDebugMap.cpp         |  3 +-
 .../DWARF/SymbolFileDWARFDebugMap.h           |  3 +-
 lldb/source/Symbol/SymbolFileOnDemand.cpp     |  7 +--
 .../SymbolFile/DWARF/XcodeSDKModuleTests.cpp  |  2 +-
 14 files changed, 163 insertions(+), 54 deletions(-)

diff --git a/lldb/include/lldb/Host/FileSystem.h b/lldb/include/lldb/Host/FileSystem.h
index 640f3846e448c..4128d7b012041 100644
--- a/lldb/include/lldb/Host/FileSystem.h
+++ b/lldb/include/lldb/Host/FileSystem.h
@@ -183,8 +183,9 @@ class FileSystem {
     eEnumerateDirectoryResultQuit
   };
 
-  typedef EnumerateDirectoryResult (*EnumerateDirectoryCallbackType)(
-      void *baton, llvm::sys::fs::file_type file_type, llvm::StringRef);
+  typedef std::function<EnumerateDirectoryResult(
+      void *baton, llvm::sys::fs::file_type file_type, llvm::StringRef)>
+      EnumerateDirectoryCallbackType;
 
   typedef std::function<EnumerateDirectoryResult(
       llvm::sys::fs::file_type file_type, llvm::StringRef)>
diff --git a/lldb/include/lldb/Symbol/SymbolFile.h b/lldb/include/lldb/Symbol/SymbolFile.h
index d417899e97084..837b922ae77f7 100644
--- a/lldb/include/lldb/Symbol/SymbolFile.h
+++ b/lldb/include/lldb/Symbol/SymbolFile.h
@@ -32,7 +32,6 @@
 #include <mutex>
 #include <optional>
 #include <unordered_map>
-#include <utility>
 
 #if defined(LLDB_CONFIGURATION_DEBUG)
 #define ASSERT_MODULE_LOCK(expr) (expr->AssertModuleLock())
@@ -149,10 +148,7 @@ class SymbolFile : public PluginInterface {
 
   virtual lldb::LanguageType ParseLanguage(CompileUnit &comp_unit) = 0;
   /// Return the Xcode SDK comp_unit was compiled against.
-  virtual std::pair<XcodeSDK, std::string>
-  ParseXcodeSDK(CompileUnit &comp_unit) {
-    return {};
-  }
+  virtual XcodeSDK ParseXcodeSDK(CompileUnit &comp_unit) { return {}; }
 
   /// This function exists because SymbolFileDWARFDebugMap may extra compile
   /// units which aren't exposed as "real" compile units. In every other
diff --git a/lldb/include/lldb/Symbol/SymbolFileOnDemand.h b/lldb/include/lldb/Symbol/SymbolFileOnDemand.h
index 77e7b50539043..7a366bfabec86 100644
--- a/lldb/include/lldb/Symbol/SymbolFileOnDemand.h
+++ b/lldb/include/lldb/Symbol/SymbolFileOnDemand.h
@@ -65,7 +65,7 @@ class SymbolFileOnDemand : public lldb_private::SymbolFile {
   lldb::LanguageType
   ParseLanguage(lldb_private::CompileUnit &comp_unit) override;
 
-  std::pair<lldb_private::XcodeSDK, std::string>
+  lldb_private::XcodeSDK
   ParseXcodeSDK(lldb_private::CompileUnit &comp_unit) override;
 
   void InitializeObject() override;
diff --git a/lldb/include/lldb/Target/Platform.h b/lldb/include/lldb/Target/Platform.h
index 5f85caeb790ba..a702abb540fd9 100644
--- a/lldb/include/lldb/Target/Platform.h
+++ b/lldb/include/lldb/Target/Platform.h
@@ -438,6 +438,25 @@ class Platform : public PluginInterface {
     return lldb_private::ConstString();
   }
 
+  /// Search each CU associated with the specified 'module' for
+  /// the SDK paths the CUs were compiled against. In the presence
+  /// of different SDKs, we try to pick the most appropriate one
+  /// using \ref XcodeSDK::Merge.
+  ///
+  /// \param[in] module Module whose debug-info CUs to parse for
+  ///                   which SDK they were compiled against.
+  ///
+  /// \returns If successful, returns a pair of a parsed XcodeSDK
+  ///          object and a boolean that is 'true' if we encountered
+  ///          a conflicting combination of SDKs when parsing the CUs
+  ///          (e.g., a public and internal SDK).
+  virtual llvm::Expected<std::pair<XcodeSDK, bool>>
+  GetSDKPathFromDebugInfo(Module &module) {
+    return llvm::createStringError(
+        llvm::formatv("{0} not implemented for '{1}' platform.",
+                      LLVM_PRETTY_FUNCTION, GetName()));
+  }
+
   /// Returns the full path of the most appropriate SDK for the
   /// specified 'module'. This function gets this path by parsing
   /// debug-info (see \ref `GetSDKPathFromDebugInfo`).
@@ -458,9 +477,8 @@ class Platform : public PluginInterface {
   ///
   /// \param[in] unit The CU
   ///
-  /// \returns A parsed XcodeSDK object if successful, an Error otherwise.
-  virtual llvm::Expected<std::pair<XcodeSDK, std::string>>
-  GetSDKPathFromDebugInfo(CompileUnit &unit) {
+  /// \returns A parsed XcodeSDK object if successful, an Error otherwise. 
+  virtual llvm::Expected<XcodeSDK> GetSDKPathFromDebugInfo(CompileUnit &unit) {
     return llvm::createStringError(
         llvm::formatv("{0} not implemented for '{1}' platform.",
                       LLVM_PRETTY_FUNCTION, GetName()));
diff --git a/lldb/source/Host/macosx/objcxx/HostInfoMacOSX.mm b/lldb/source/Host/macosx/objcxx/HostInfoMacOSX.mm
index 6e924fdc684cf..a94fd3b57f9d6 100644
--- a/lldb/source/Host/macosx/objcxx/HostInfoMacOSX.mm
+++ b/lldb/source/Host/macosx/objcxx/HostInfoMacOSX.mm
@@ -15,11 +15,14 @@
 #include "lldb/Utility/Log.h"
 #include "lldb/Utility/Timer.h"
 
+#include "clang/Basic/DarwinSDKInfo.h"
 #include "llvm/ADT/ScopeExit.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringMap.h"
+#include "llvm/Support/Error.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
+#include "llvm/Support/VersionTuple.h"
 #include "llvm/Support/raw_ostream.h"
 
 // C++ Includes
@@ -569,10 +572,52 @@ static bool ResolveAndVerifyCandidateSupportDir(FileSpec &path) {
     cache.insert({key, {error, true}});
     return llvm::createStringError(llvm::inconvertibleErrorCode(), error);
   }
+
+  if (path_or_err->empty())
+    return llvm::createStringError("Empty path determined for '%s'",
+                                   key.data());
+
   auto it_new = cache.insert({key, {*path_or_err, false}});
   return it_new.first->second.str;
 }
 
+static llvm::Expected<std::string>
+GetCommandLineToolsSDKRoot(llvm::VersionTuple version) {
+  std::string clt_root_dir;
+  FileSystem::Instance().EnumerateDirectory(
+      "/Library/Developer/CommandLineTools/SDKs/", /*find_directories=*/true,
+      /*find_files=*/false, /*find_other=*/false,
+      [&](void *baton, llvm::sys::fs::file_type file_type,
+          llvm::StringRef name) {
+        assert(file_type == llvm::sys::fs::file_type::directory_file);
+
+        if (!name.ends_with(".sdk"))
+          return FileSystem::eEnumerateDirectoryResultNext;
+
+        llvm::Expected<std::optional<clang::DarwinSDKInfo>> sdk_info =
+            clang::parseDarwinSDKInfo(
+                *FileSystem::Instance().GetVirtualFileSystem(), name);
+        if (!sdk_info) {
+          LLDB_LOG_ERROR(GetLog(LLDBLog::Expressions), sdk_info.takeError(),
+                         "Error while parsing {1}: {0}", name);
+          return FileSystem::eEnumerateDirectoryResultNext;
+        }
+
+        if (!*sdk_info)
+          return FileSystem::eEnumerateDirectoryResultNext;
+
+        if (version == (*sdk_info)->getVersion()) {
+          clt_root_dir = name;
+          return FileSystem::eEnumerateDirectoryResultQuit;
+        }
+
+        return FileSystem::eEnumerateDirectoryResultNext;
+      },
+      /*baton=*/nullptr);
+
+  return clt_root_dir;
+}
+
 llvm::Expected<llvm::StringRef> HostInfoMacOSX::GetSDKRoot(SDKOptions options) {
   static llvm::StringMap<ErrorOrPath> g_sdk_path;
   static std::mutex g_sdk_path_mutex;
@@ -581,6 +626,21 @@ static bool ResolveAndVerifyCandidateSupportDir(FileSpec &path) {
                                    "XcodeSDK not specified");
   XcodeSDK sdk = *options.XcodeSDKSelection;
   auto key = sdk.GetString();
+
+  // xcrun doesn't search SDKs in the CommandLineTools (CLT) directory. So if
+  // a program was compiled against a CLT SDK, but that SDK wasn't present in
+  // any of the Xcode installations, then xcrun would fail to find the SDK
+  // (which is expensive). To avoid this we first try to find the specified SDK
+  // in the CLT directory.
+  auto clt_root_dir = find_cached_path(g_sdk_path, g_sdk_path_mutex, key, [&] {
+    return GetCommandLineToolsSDKRoot(sdk.GetVersion());
+  });
+
+  if (clt_root_dir)
+    return clt_root_dir;
+  else
+    llvm::consumeError(clt_root_dir.takeError());
+
   return find_cached_path(g_sdk_path, g_sdk_path_mutex, key, [&](){
     return GetXcodeSDK(sdk);
   });
diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
index e980c914afd1a..f1573bae2651b 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
+++ b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
@@ -336,7 +336,13 @@ sdkSupportsBuiltinModules(lldb_private::Target &target) {
   if (!platform_sp)
     return llvm::createStringError("No Platform plugin found on target.");
 
-  auto sdk_path_or_err = platform_sp->ResolveSDKPathFromDebugInfo(*module_sp);
+  auto sdk_or_err = platform_sp->GetSDKPathFromDebugInfo(*module_sp);
+  if (!sdk_or_err)
+    return sdk_or_err.takeError();
+
+  // Use the SDK path from debug-info to find a local matching SDK directory.
+  auto sdk_path_or_err =
+      HostInfo::GetSDKRoot(HostInfo::SDKOptions{std::move(sdk_or_err->first)});
   if (!sdk_path_or_err)
     return sdk_path_or_err.takeError();
 
diff --git a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp
index ef10481503efe..51e9a6d81b839 100644
--- a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp
+++ b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp
@@ -1386,18 +1386,57 @@ llvm::Triple::OSType PlatformDarwin::GetHostOSType() {
 #endif // __APPLE__
 }
 
+llvm::Expected<std::pair<XcodeSDK, bool>>
+PlatformDarwin::GetSDKPathFromDebugInfo(Module &module) {
+  SymbolFile *sym_file = module.GetSymbolFile();
+  if (!sym_file)
+    return llvm::createStringError(
+        llvm::inconvertibleErrorCode(),
+        llvm::formatv("No symbol file available for module '{0}'",
+                      module.GetFileSpec().GetFilename().AsCString("")));
+
+  bool found_public_sdk = false;
+  bool found_internal_sdk = false;
+  XcodeSDK merged_sdk;
+  for (unsigned i = 0; i < sym_file->GetNumCompileUnits(); ++i) {
+    if (auto cu_sp = sym_file->GetCompileUnitAtIndex(i)) {
+      auto cu_sdk = sym_file->ParseXcodeSDK(*cu_sp);
+      bool is_internal_sdk = cu_sdk.IsAppleInternalSDK();
+      found_public_sdk |= !is_internal_sdk;
+      found_internal_sdk |= is_internal_sdk;
+
+      merged_sdk.Merge(cu_sdk);
+    }
+  }
+
+  const bool found_mismatch = found_internal_sdk && found_public_sdk;
+
+  return std::pair{std::move(merged_sdk), found_mismatch};
+}
+
 llvm::Expected<std::string>
 PlatformDarwin::ResolveSDKPathFromDebugInfo(Module &module) {
-  auto cu_sp = module.GetCompileUnitAtIndex(0);
-  if (!cu_sp)
+  auto sdk_or_err = GetSDKPathFromDebugInfo(module);
+  if (!sdk_or_err)
     return llvm::createStringError(
-        "Couldn't retrieve compile-unit for module '%s'.",
-        module.GetObjectName().AsCString("<null>"));
+        llvm::inconvertibleErrorCode(),
+        llvm::formatv("Failed to parse SDK path from debug-info: {0}",
+                      llvm::toString(sdk_or_err.takeError())));
+
+  auto [sdk, _] = std::move(*sdk_or_err);
+
+  auto path_or_err = HostInfo::GetSDKRoot(HostInfo::SDKOptions{sdk});
+  if (!path_or_err)
+    return llvm::createStringError(
+        llvm::inconvertibleErrorCode(),
+        llvm::formatv("Error while searching for SDK (XcodeSDK '{0}'): {1}",
+                      sdk.GetString(),
+                      llvm::toString(path_or_err.takeError())));
 
-  return ResolveSDKPathFromDebugInfo(*cu_sp);
+  return path_or_err->str();
 }
 
-llvm::Expected<std::pair<XcodeSDK, std::string>>
+llvm::Expected<XcodeSDK>
 PlatformDarwin::GetSDKPathFromDebugInfo(CompileUnit &unit) {
   ModuleSP module_sp = unit.CalculateSymbolContextModule();
   if (!module_sp)
@@ -1420,10 +1459,7 @@ PlatformDarwin::ResolveSDKPathFromDebugInfo(CompileUnit &unit) {
         llvm::formatv("Failed to parse SDK path from debug-info: {0}",
                       llvm::toString(sdk_or_err.takeError())));
 
-  auto [sdk, sysroot] = std::move(*sdk_or_err);
-
-  if (FileSystem::Instance().Exists(sysroot))
-    return sysroot;
+  auto sdk = std::move(*sdk_or_err);
 
   auto path_or_err = HostInfo::GetSDKRoot(HostInfo::SDKOptions{sdk});
   if (!path_or_err)
diff --git a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.h b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.h
index 0a4e6c9938c17..e2d4cb6726d58 100644
--- a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.h
+++ b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.h
@@ -124,11 +124,13 @@ class PlatformDarwin : public PlatformPOSIX {
   /// located in.
   static FileSpec GetCurrentCommandLineToolsDirectory();
 
+  llvm::Expected<std::pair<XcodeSDK, bool>>
+  GetSDKPathFromDebugInfo(Module &module) override;
+
   llvm::Expected<std::string>
   ResolveSDKPathFromDebugInfo(Module &module) override;
 
-  llvm::Expected<std::pair<XcodeSDK, std::string>>
-  GetSDKPathFromDebugInfo(CompileUnit &unit) override;
+  llvm::Expected<XcodeSDK> GetSDKPathFromDebugInfo(CompileUnit &unit) override;
 
   llvm::Expected<std::string>
   ResolveSDKPathFromDebugInfo(CompileUnit &unit) override;
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
index 714586a4e2468..a96757afabddf 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -982,8 +982,7 @@ lldb::LanguageType SymbolFileDWARF::ParseLanguage(CompileUnit &comp_unit) {
     return eLanguageTypeUnknown;
 }
 
-std::pair<XcodeSDK, std::string>
-SymbolFileDWARF::ParseXcodeSDK(CompileUnit &comp_unit) {
+XcodeSDK SymbolFileDWARF::ParseXcodeSDK(CompileUnit &comp_unit) {
   std::lock_guard<std::recursive_mutex> guard(GetModuleMutex());
   DWARFUnit *dwarf_cu = GetDWARFCompileUnit(&comp_unit);
   if (!dwarf_cu)
@@ -994,26 +993,21 @@ SymbolFileDWARF::ParseXcodeSDK(CompileUnit &comp_unit) {
   const char *sdk = cu_die.GetAttributeValueAsString(DW_AT_APPLE_sdk, nullptr);
   if (!sdk)
     return {};
-  std::string sysroot =
+  const char *sysroot =
       cu_die.GetAttributeValueAsString(DW_AT_LLVM_sysroot, "");
+  // Register the sysroot path remapping with the module belonging to
+  // the CU as well as the one belonging to the symbol file. The two
+  // would be different if this is an OSO object and module is the
+  // corresponding debug map, in which case both should be updated.
+  ModuleSP module_sp = comp_unit.GetModule();
+  if (module_sp)
+    module_sp->RegisterXcodeSDK(sdk, sysroot);
 
-  // RegisterXcodeSDK calls into xcrun which is not aware of CLT, which is
-  // expensive.
-  if (sysroot.find("/Library/Developer/CommandLineTools/SDKs") != 0) {
-    // Register the sysroot path remapping with the module belonging to
-    // the CU as well as the one belonging to the symbol file. The two
-    // would be different if this is an OSO object and module is the
-    // corresponding debug map, in which case both should be updated.
-    ModuleSP module_sp = comp_unit.GetModule();
-    if (module_sp)
-      module_sp->RegisterXcodeSDK(sdk, sysroot);
-
-    ModuleSP local_module_sp = m_objfile_sp->GetModule();
-    if (local_module_sp && local_module_sp != module_sp)
-      local_module_sp->RegisterXcodeSDK(sdk, sysroot);
-  }
+  ModuleSP local_module_sp = m_objfile_sp->GetModule();
+  if (local_module_sp && local_module_sp != module_sp)
+    local_module_sp->RegisterXcodeSDK(sdk, sysroot);
 
-  return std::pair{XcodeSDK{sdk}, std::move(sysroot)};
+  return {sdk};
 }
 
 size_t SymbolFileDWARF::ParseFunctions(CompileUnit &comp_unit) {
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
index 8f7f84aff355d..7309f7a86b659 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
@@ -110,8 +110,7 @@ class SymbolFileDWARF : public SymbolFileCommon {
 
   lldb::LanguageType ParseLanguage(CompileUnit &comp_unit) override;
 
-  std::pair<XcodeSDK, std::string>
-  ParseXcodeSDK(CompileUnit &comp_unit) override;
+  XcodeSDK ParseXcodeSDK(CompileUnit &comp_unit) override;
 
   size_t ParseFunctions(CompileUnit &comp_unit) override;
 
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
index eb2db68dd9435..0ecf47a3c7869 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
@@ -673,8 +673,7 @@ SymbolFileDWARFDebugMap::ParseLanguage(CompileUnit &comp_unit) {
   return eLanguageTypeUnknown;
 }
 
-std::pair<XcodeSDK, std::string>
-SymbolFileDWARFDebugMap::ParseXcodeSDK(CompileUnit &comp_unit) {
+XcodeSDK SymbolFileDWARFDebugMap::ParseXcodeSDK(CompileUnit &comp_unit) {
   std::lock_guard<std::recursive_mutex> guard(GetModuleMutex());
   SymbolFileDWARF *oso_dwarf = GetSymbolFile(comp_unit);
   if (oso_dwarf)
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h
index 9f1fe9abe002b..df41d6a2a4e42 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h
@@ -64,8 +64,7 @@ class SymbolFileDWARFDebugMap : public SymbolFileCommon {
 
   // Compile Unit function calls
   lldb::LanguageType ParseLanguage(CompileUnit &comp_unit) override;
-  std::pair<XcodeSDK, std::string>
-  ParseXcodeSDK(CompileUnit &comp_unit) override;
+  XcodeSDK ParseXcodeSDK(CompileUnit &comp_unit) override;
   llvm::SmallSet<lldb::LanguageType, 4>
   ParseAllLanguages(CompileUnit &comp_unit) override;
   size_t ParseFunctions(CompileUnit &comp_unit) override;
diff --git a/lldb/source/Symbol/SymbolFileOnDemand.cpp b/lldb/source/Symbol/SymbolFileOnDemand.cpp
index 94c6e01d83d1d..94979b2fb1c22 100644
--- a/lldb/source/Symbol/SymbolFileOnDemand.cpp
+++ b/lldb/source/Symbol/SymbolFileOnDemand.cpp
@@ -58,18 +58,17 @@ lldb::LanguageType SymbolFileOnDemand::ParseLanguage(CompileUnit &comp_unit) {
   return m_sym_file_impl->ParseLanguage(comp_unit);
 }
 
-std::pair<XcodeSDK, std::string>
-SymbolFileOnDemand::ParseXcodeSDK(CompileUnit &comp_unit) {
+XcodeSDK SymbolFileOnDemand::ParseXcodeSDK(CompileUnit &comp_unit) {
   if (!m_debug_info_enabled) {
     Log *log = GetLog();
     LLDB_LOG(log, "[{0}] {1} is skipped", GetSymbolFileName(), __FUNCTION__);
     XcodeSDK defaultValue{};
     if (log) {
-      auto [sdk, sysroot] = m_sym_file_impl->ParseXcodeSDK(comp_unit);
+      XcodeSDK sdk = m_sym_file_impl->ParseXcodeSDK(comp_unit);
       if (!(sdk == defaultValue))
         LLDB_LOG(log, "SDK {0} would return if hydrated.", sdk.GetString());
     }
-    return {defaultValue, {}};
+    return defaultValue;
   }
   return m_sym_file_impl->ParseXcodeSDK(comp_unit);
 }
diff --git a/lldb/unittests/SymbolFile/DWARF/XcodeSDKModuleTests.cpp b/lldb/unittests/SymbolFile/DWARF/XcodeSDKModuleTests.cpp
index bda69815ad388..fc008ca7011e4 100644
--- a/lldb/unittests/SymbolFile/DWARF/XcodeSDKModuleTests.cpp
+++ b/lldb/unittests/SymbolFile/DWARF/XcodeSDKModuleTests.cpp
@@ -118,7 +118,7 @@ TEST_F(XcodeSDKModuleTests, TestModuleGetXcodeSDK) {
   ASSERT_TRUE(static_cast<bool>(comp_unit.get()));
   ModuleSP module = t.GetModule();
   ASSERT_EQ(module->GetSourceMappingList().GetSize(), 0u);
-  auto [sdk, sysroot] = sym_file.ParseXcodeSDK(*comp_unit);
+  XcodeSDK sdk = sym_file.ParseXcodeSDK(*comp_unit);
   ASSERT_EQ(sdk.GetType(), XcodeSDK::Type::MacOSX);
   ASSERT_EQ(module->GetSourceMappingList().GetSize(), 1u);
 }

From 2b5628eb2d9515d9beeb767f106e8a39b980e309 Mon Sep 17 00:00:00 2001
From: Michael Buch <michaelbuch12@gmail.com>
Date: Mon, 3 Mar 2025 12:31:48 +0000
Subject: [PATCH 4/8] Revert "[lldb]HostInfoMacOSX] Search CommandLineTools
 directory when looking up SDK paths"

This reverts commit 2665e747d5866480f2f704d5a72fe016d258f200.
---
 lldb/include/lldb/Host/FileSystem.h           |  5 +-
 .../Host/macosx/objcxx/HostInfoMacOSX.mm      | 60 -------------------
 2 files changed, 2 insertions(+), 63 deletions(-)

diff --git a/lldb/include/lldb/Host/FileSystem.h b/lldb/include/lldb/Host/FileSystem.h
index 4128d7b012041..640f3846e448c 100644
--- a/lldb/include/lldb/Host/FileSystem.h
+++ b/lldb/include/lldb/Host/FileSystem.h
@@ -183,9 +183,8 @@ class FileSystem {
     eEnumerateDirectoryResultQuit
   };
 
-  typedef std::function<EnumerateDirectoryResult(
-      void *baton, llvm::sys::fs::file_type file_type, llvm::StringRef)>
-      EnumerateDirectoryCallbackType;
+  typedef EnumerateDirectoryResult (*EnumerateDirectoryCallbackType)(
+      void *baton, llvm::sys::fs::file_type file_type, llvm::StringRef);
 
   typedef std::function<EnumerateDirectoryResult(
       llvm::sys::fs::file_type file_type, llvm::StringRef)>
diff --git a/lldb/source/Host/macosx/objcxx/HostInfoMacOSX.mm b/lldb/source/Host/macosx/objcxx/HostInfoMacOSX.mm
index a94fd3b57f9d6..6e924fdc684cf 100644
--- a/lldb/source/Host/macosx/objcxx/HostInfoMacOSX.mm
+++ b/lldb/source/Host/macosx/objcxx/HostInfoMacOSX.mm
@@ -15,14 +15,11 @@
 #include "lldb/Utility/Log.h"
 #include "lldb/Utility/Timer.h"
 
-#include "clang/Basic/DarwinSDKInfo.h"
 #include "llvm/ADT/ScopeExit.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringMap.h"
-#include "llvm/Support/Error.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
-#include "llvm/Support/VersionTuple.h"
 #include "llvm/Support/raw_ostream.h"
 
 // C++ Includes
@@ -572,52 +569,10 @@ static bool ResolveAndVerifyCandidateSupportDir(FileSpec &path) {
     cache.insert({key, {error, true}});
     return llvm::createStringError(llvm::inconvertibleErrorCode(), error);
   }
-
-  if (path_or_err->empty())
-    return llvm::createStringError("Empty path determined for '%s'",
-                                   key.data());
-
   auto it_new = cache.insert({key, {*path_or_err, false}});
   return it_new.first->second.str;
 }
 
-static llvm::Expected<std::string>
-GetCommandLineToolsSDKRoot(llvm::VersionTuple version) {
-  std::string clt_root_dir;
-  FileSystem::Instance().EnumerateDirectory(
-      "/Library/Developer/CommandLineTools/SDKs/", /*find_directories=*/true,
-      /*find_files=*/false, /*find_other=*/false,
-      [&](void *baton, llvm::sys::fs::file_type file_type,
-          llvm::StringRef name) {
-        assert(file_type == llvm::sys::fs::file_type::directory_file);
-
-        if (!name.ends_with(".sdk"))
-          return FileSystem::eEnumerateDirectoryResultNext;
-
-        llvm::Expected<std::optional<clang::DarwinSDKInfo>> sdk_info =
-            clang::parseDarwinSDKInfo(
-                *FileSystem::Instance().GetVirtualFileSystem(), name);
-        if (!sdk_info) {
-          LLDB_LOG_ERROR(GetLog(LLDBLog::Expressions), sdk_info.takeError(),
-                         "Error while parsing {1}: {0}", name);
-          return FileSystem::eEnumerateDirectoryResultNext;
-        }
-
-        if (!*sdk_info)
-          return FileSystem::eEnumerateDirectoryResultNext;
-
-        if (version == (*sdk_info)->getVersion()) {
-          clt_root_dir = name;
-          return FileSystem::eEnumerateDirectoryResultQuit;
-        }
-
-        return FileSystem::eEnumerateDirectoryResultNext;
-      },
-      /*baton=*/nullptr);
-
-  return clt_root_dir;
-}
-
 llvm::Expected<llvm::StringRef> HostInfoMacOSX::GetSDKRoot(SDKOptions options) {
   static llvm::StringMap<ErrorOrPath> g_sdk_path;
   static std::mutex g_sdk_path_mutex;
@@ -626,21 +581,6 @@ static bool ResolveAndVerifyCandidateSupportDir(FileSpec &path) {
                                    "XcodeSDK not specified");
   XcodeSDK sdk = *options.XcodeSDKSelection;
   auto key = sdk.GetString();
-
-  // xcrun doesn't search SDKs in the CommandLineTools (CLT) directory. So if
-  // a program was compiled against a CLT SDK, but that SDK wasn't present in
-  // any of the Xcode installations, then xcrun would fail to find the SDK
-  // (which is expensive). To avoid this we first try to find the specified SDK
-  // in the CLT directory.
-  auto clt_root_dir = find_cached_path(g_sdk_path, g_sdk_path_mutex, key, [&] {
-    return GetCommandLineToolsSDKRoot(sdk.GetVersion());
-  });
-
-  if (clt_root_dir)
-    return clt_root_dir;
-  else
-    llvm::consumeError(clt_root_dir.takeError());
-
   return find_cached_path(g_sdk_path, g_sdk_path_mutex, key, [&](){
     return GetXcodeSDK(sdk);
   });

From 907b2f4682528ca06856f1a6690607f2ee19c94c Mon Sep 17 00:00:00 2001
From: Michael Buch <michaelbuch12@gmail.com>
Date: Fri, 28 Feb 2025 17:54:36 +0000
Subject: [PATCH 5/8] fixup! store sysroot inside XcodeSDK

---
 .../include/lldb/Host/macosx/HostInfoMacOSX.h |  3 ++
 lldb/include/lldb/Utility/XcodeSDK.h          |  5 ++++
 .../Platform/MacOSX/PlatformDarwin.cpp        | 12 ++++++++
 .../SymbolFile/DWARF/SymbolFileDWARF.cpp      | 29 +++++++++++--------
 lldb/source/Utility/XcodeSDK.cpp              | 19 +++++++++---
 .../SymbolFile/DWARF/XcodeSDKModuleTests.cpp  | 19 ++++++++++--
 lldb/unittests/Utility/XcodeSDKTest.cpp       | 12 ++++++++
 7 files changed, 81 insertions(+), 18 deletions(-)

diff --git a/lldb/include/lldb/Host/macosx/HostInfoMacOSX.h b/lldb/include/lldb/Host/macosx/HostInfoMacOSX.h
index 8eb2ede382c22..9034c80fdefa4 100644
--- a/lldb/include/lldb/Host/macosx/HostInfoMacOSX.h
+++ b/lldb/include/lldb/Host/macosx/HostInfoMacOSX.h
@@ -32,6 +32,9 @@ class HostInfoMacOSX : public HostInfoPosix {
   static FileSpec GetXcodeDeveloperDirectory();
 
   /// Query xcrun to find an Xcode SDK directory.
+  ///
+  /// Note, this is an expensive operation if the SDK we're querying
+  /// does not exist in an Xcode installation path on the host.
   static llvm::Expected<llvm::StringRef> GetSDKRoot(SDKOptions options);
   static llvm::Expected<llvm::StringRef> FindSDKTool(XcodeSDK sdk,
                                                      llvm::StringRef tool);
diff --git a/lldb/include/lldb/Utility/XcodeSDK.h b/lldb/include/lldb/Utility/XcodeSDK.h
index 2720d0d8a44a1..fa893c0ca8d7e 100644
--- a/lldb/include/lldb/Utility/XcodeSDK.h
+++ b/lldb/include/lldb/Utility/XcodeSDK.h
@@ -23,6 +23,8 @@ namespace lldb_private {
 /// An abstraction for Xcode-style SDKs that works like \ref ArchSpec.
 class XcodeSDK {
   std::string m_name;
+  std::optional<std::string>
+      m_sysroot_path; // TODO: should this be std::optional<FileSpec>?
 
 public:
   /// Different types of Xcode SDKs.
@@ -62,6 +64,8 @@ class XcodeSDK {
   /// directory component of a path one would pass to clang's -isysroot
   /// parameter. For example, "MacOSX.10.14.sdk".
   XcodeSDK(std::string &&name) : m_name(std::move(name)) {}
+  XcodeSDK(std::string name, std::string sysroot)
+      : m_name(std::move(name)), m_sysroot_path(std::move(sysroot)) {}
   static XcodeSDK GetAnyMacOS() { return XcodeSDK("MacOSX.sdk"); }
 
   /// The merge function follows a strict order to maintain monotonicity:
@@ -79,6 +83,7 @@ class XcodeSDK {
   llvm::VersionTuple GetVersion() const;
   Type GetType() const;
   llvm::StringRef GetString() const;
+  std::optional<llvm::StringRef> GetSysroot() const;
   /// Whether this Xcode SDK supports Swift.
   bool SupportsSwift() const;
 
diff --git a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp
index 51e9a6d81b839..d74c8651e4abc 100644
--- a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp
+++ b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp
@@ -79,6 +79,14 @@ static Status ExceptionMaskValidator(const char *string, void *unused) {
   return {};
 }
 
+static bool XcodeSysrootExists(XcodeSDK const &sdk) {
+  auto maybe_sysroot = sdk.GetSysroot();
+  if (!maybe_sysroot)
+    return false;
+
+  return FileSystem::Instance().Exists(*maybe_sysroot);
+}
+
 /// Destructor.
 ///
 /// The destructor is virtual since this class is designed to be
@@ -1395,6 +1403,7 @@ PlatformDarwin::GetSDKPathFromDebugInfo(Module &module) {
         llvm::formatv("No symbol file available for module '{0}'",
                       module.GetFileSpec().GetFilename().AsCString("")));
 
+  std::string sysroot;
   bool found_public_sdk = false;
   bool found_internal_sdk = false;
   XcodeSDK merged_sdk;
@@ -1425,6 +1434,9 @@ PlatformDarwin::ResolveSDKPathFromDebugInfo(Module &module) {
 
   auto [sdk, _] = std::move(*sdk_or_err);
 
+  if (XcodeSysrootExists(sdk))
+    return sdk.GetSysroot()->str();
+
   auto path_or_err = HostInfo::GetSDKRoot(HostInfo::SDKOptions{sdk});
   if (!path_or_err)
     return llvm::createStringError(
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
index a96757afabddf..9b5eb68652f58 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -993,21 +993,26 @@ XcodeSDK SymbolFileDWARF::ParseXcodeSDK(CompileUnit &comp_unit) {
   const char *sdk = cu_die.GetAttributeValueAsString(DW_AT_APPLE_sdk, nullptr);
   if (!sdk)
     return {};
-  const char *sysroot =
+  std::string sysroot =
       cu_die.GetAttributeValueAsString(DW_AT_LLVM_sysroot, "");
-  // Register the sysroot path remapping with the module belonging to
-  // the CU as well as the one belonging to the symbol file. The two
-  // would be different if this is an OSO object and module is the
-  // corresponding debug map, in which case both should be updated.
-  ModuleSP module_sp = comp_unit.GetModule();
-  if (module_sp)
-    module_sp->RegisterXcodeSDK(sdk, sysroot);
 
-  ModuleSP local_module_sp = m_objfile_sp->GetModule();
-  if (local_module_sp && local_module_sp != module_sp)
-    local_module_sp->RegisterXcodeSDK(sdk, sysroot);
+  // RegisterXcodeSDK calls into xcrun which is not aware of CLT, which is
+  // expensive.
+  if (sysroot.find("/Library/Developer/CommandLineTools/SDKs") != 0) {
+    // Register the sysroot path remapping with the module belonging to
+    // the CU as well as the one belonging to the symbol file. The two
+    // would be different if this is an OSO object and module is the
+    // corresponding debug map, in which case both should be updated.
+    ModuleSP module_sp = comp_unit.GetModule();
+    if (module_sp)
+      module_sp->RegisterXcodeSDK(sdk, sysroot);
+
+    ModuleSP local_module_sp = m_objfile_sp->GetModule();
+    if (local_module_sp && local_module_sp != module_sp)
+      local_module_sp->RegisterXcodeSDK(sdk, sysroot);
+  }
 
-  return {sdk};
+  return {sdk, std::move(sysroot)};
 }
 
 size_t SymbolFileDWARF::ParseFunctions(CompileUnit &comp_unit) {
diff --git a/lldb/source/Utility/XcodeSDK.cpp b/lldb/source/Utility/XcodeSDK.cpp
index b7d51f7e0827a..9e22720053e91 100644
--- a/lldb/source/Utility/XcodeSDK.cpp
+++ b/lldb/source/Utility/XcodeSDK.cpp
@@ -142,6 +142,10 @@ XcodeSDK::Type XcodeSDK::GetType() const {
 
 llvm::StringRef XcodeSDK::GetString() const { return m_name; }
 
+std::optional<llvm::StringRef> XcodeSDK::GetSysroot() const {
+  return m_sysroot_path;
+}
+
 bool XcodeSDK::Info::operator<(const Info &other) const {
   return std::tie(type, version, internal) <
          std::tie(other.type, other.version, other.internal);
@@ -153,6 +157,10 @@ bool XcodeSDK::Info::operator==(const Info &other) const {
 }
 
 void XcodeSDK::Merge(const XcodeSDK &other) {
+  auto add_internal_sdk_suffix = [](std::string const &sdk) {
+    return sdk.substr(0, sdk.size() - 3) + "Internal.sdk";
+  };
+
   // The "bigger" SDK always wins.
   auto l = Parse();
   auto r = other.Parse();
@@ -160,10 +168,13 @@ void XcodeSDK::Merge(const XcodeSDK &other) {
     *this = other;
   else {
     // The Internal flag always wins.
-    if (llvm::StringRef(m_name).ends_with(".sdk"))
-      if (!l.internal && r.internal)
-        m_name =
-            m_name.substr(0, m_name.size() - 3) + std::string("Internal.sdk");
+    if (!l.internal && r.internal) {
+      if (llvm::StringRef(m_name).ends_with(".sdk"))
+        m_name = add_internal_sdk_suffix(m_name);
+
+      if (m_sysroot_path && llvm::StringRef(*m_sysroot_path).ends_with(".sdk"))
+        m_sysroot_path.emplace(add_internal_sdk_suffix(*m_sysroot_path));
+    }
   }
 }
 
diff --git a/lldb/unittests/SymbolFile/DWARF/XcodeSDKModuleTests.cpp b/lldb/unittests/SymbolFile/DWARF/XcodeSDKModuleTests.cpp
index fc008ca7011e4..c1e471653a279 100644
--- a/lldb/unittests/SymbolFile/DWARF/XcodeSDKModuleTests.cpp
+++ b/lldb/unittests/SymbolFile/DWARF/XcodeSDKModuleTests.cpp
@@ -310,13 +310,28 @@ SDKPathParsingTestData sdkPathParsingTestCases[] = {
      .expect_internal_sdk = true,
      .expect_sdk_path_pattern = "Internal.sdk"},
 
-    /// Two CUs with an internal SDK each
+    /// Two CUs with a public (non-CommandLineTools) SDK each
+    {.input_sdk_paths = {"/Path/To/SDKs/iPhoneOS14.1.sdk",
+                         "/Path/To/SDKs/MacOSX11.3.sdk"},
+     .expect_mismatch = false,
+     .expect_internal_sdk = false,
+     .expect_sdk_path_pattern = "iPhoneOS14.1.sdk"},
+
+    /// One CU with CommandLineTools and the other a public SDK
     {.input_sdk_paths =
          {"/Library/Developer/CommandLineTools/SDKs/iPhoneOS14.1.sdk",
-          "/Library/Developer/CommandLineTools/SDKs/MacOSX11.3.sdk"},
+          "/Path/To/SDKs/MacOSX11.3.sdk"},
      .expect_mismatch = false,
      .expect_internal_sdk = false,
      .expect_sdk_path_pattern = "iPhoneOS14.1.sdk"},
+
+    /// One CU with CommandLineTools and the other an internal SDK
+    {.input_sdk_paths =
+         {"/Library/Developer/CommandLineTools/SDKs/iPhoneOS14.1.sdk",
+          "/Path/To/SDKs/MacOSX11.3.Internal.sdk"},
+     .expect_mismatch = false,
+     .expect_internal_sdk = false,
+     .expect_sdk_path_pattern = "iPhoneOS14.1.Internal.sdk"},
 };
 
 INSTANTIATE_TEST_SUITE_P(SDKPathParsingTests, SDKPathParsingMultiparamTests,
diff --git a/lldb/unittests/Utility/XcodeSDKTest.cpp b/lldb/unittests/Utility/XcodeSDKTest.cpp
index 8bf7ee1be1dba..95307ade4d43a 100644
--- a/lldb/unittests/Utility/XcodeSDKTest.cpp
+++ b/lldb/unittests/Utility/XcodeSDKTest.cpp
@@ -34,12 +34,16 @@ TEST(XcodeSDKTest, ParseTest) {
   EXPECT_EQ(XcodeSDK("MacOSX10.9.sdk").GetVersion(), llvm::VersionTuple(10, 9));
   EXPECT_EQ(XcodeSDK("MacOSX10.15.4.sdk").GetVersion(), llvm::VersionTuple(10, 15));
   EXPECT_EQ(XcodeSDK("MacOSX.sdk").IsAppleInternalSDK(), false);
+  EXPECT_EQ(XcodeSDK("MacOSX.sdk", "/Path/To/MacOSX.sdk").GetSysroot(),
+            "/Path/To/MacOSX.sdk");
   EXPECT_EQ(XcodeSDK("MacOSX10.15.Internal.sdk").GetType(), XcodeSDK::MacOSX);
   EXPECT_EQ(XcodeSDK("MacOSX10.15.Internal.sdk").GetVersion(),
             llvm::VersionTuple(10, 15));
   EXPECT_EQ(XcodeSDK("MacOSX10.15.Internal.sdk").IsAppleInternalSDK(), true);
+  EXPECT_EQ(XcodeSDK("MacOSX10.15.Internal.sdk").GetSysroot(), std::nullopt);
   EXPECT_EQ(XcodeSDK().GetType(), XcodeSDK::unknown);
   EXPECT_EQ(XcodeSDK().GetVersion(), llvm::VersionTuple());
+  EXPECT_EQ(XcodeSDK().GetSysroot(), std::nullopt);
 }
 
 TEST(XcodeSDKTest, MergeTest) {
@@ -60,6 +64,14 @@ TEST(XcodeSDKTest, MergeTest) {
   XcodeSDK empty;
   empty.Merge(XcodeSDK("MacOSX10.14.Internal.sdk"));
   EXPECT_EQ(empty.GetString(), llvm::StringRef("MacOSX10.14.Internal.sdk"));
+  EXPECT_EQ(empty.GetSysroot(), std::nullopt);
+  empty.Merge(XcodeSDK("MacOSX9.5.Internal.sdk", "/Path/To/9.5.sdk"));
+  EXPECT_EQ(empty.GetSysroot(), std::nullopt);
+  empty.Merge(XcodeSDK("MacOSX12.5.sdk", "/Path/To/12.5.sdk"));
+  EXPECT_EQ(empty.GetSysroot(), "/Path/To/12.5.sdk");
+  empty.Merge(
+      XcodeSDK("MacOSX11.5.Internal.sdk", "/Path/To/12.5.Internal.sdk"));
+  EXPECT_EQ(empty.GetSysroot(), "/Path/To/12.5.Internal.sdk");
 }
 
 #ifndef _WIN32

From c172ffe4df0abbb8061423465c02813b205692f5 Mon Sep 17 00:00:00 2001
From: Michael Buch <michaelbuch12@gmail.com>
Date: Mon, 3 Mar 2025 13:13:24 +0000
Subject: [PATCH 6/8] fixup! make sysroot member a FileSpec

---
 lldb/include/lldb/Utility/XcodeSDK.h          | 10 ++++----
 .../Platform/MacOSX/PlatformDarwin.cpp        | 12 ++-------
 .../SymbolFile/DWARF/SymbolFileDWARF.cpp      |  2 +-
 lldb/source/Utility/XcodeSDK.cpp              | 12 ++++-----
 lldb/unittests/Utility/XcodeSDKTest.cpp       | 25 ++++++++++---------
 5 files changed, 26 insertions(+), 35 deletions(-)

diff --git a/lldb/include/lldb/Utility/XcodeSDK.h b/lldb/include/lldb/Utility/XcodeSDK.h
index fa893c0ca8d7e..3a6cbb9c98f6b 100644
--- a/lldb/include/lldb/Utility/XcodeSDK.h
+++ b/lldb/include/lldb/Utility/XcodeSDK.h
@@ -9,6 +9,7 @@
 #ifndef LLDB_UTILITY_SDK_H
 #define LLDB_UTILITY_SDK_H
 
+#include "lldb/Utility/FileSpec.h"
 #include "lldb/lldb-forward.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/VersionTuple.h"
@@ -23,8 +24,7 @@ namespace lldb_private {
 /// An abstraction for Xcode-style SDKs that works like \ref ArchSpec.
 class XcodeSDK {
   std::string m_name;
-  std::optional<std::string>
-      m_sysroot_path; // TODO: should this be std::optional<FileSpec>?
+  FileSpec m_sysroot;
 
 public:
   /// Different types of Xcode SDKs.
@@ -64,8 +64,8 @@ class XcodeSDK {
   /// directory component of a path one would pass to clang's -isysroot
   /// parameter. For example, "MacOSX.10.14.sdk".
   XcodeSDK(std::string &&name) : m_name(std::move(name)) {}
-  XcodeSDK(std::string name, std::string sysroot)
-      : m_name(std::move(name)), m_sysroot_path(std::move(sysroot)) {}
+  XcodeSDK(std::string name, FileSpec sysroot)
+      : m_name(std::move(name)), m_sysroot(std::move(sysroot)) {}
   static XcodeSDK GetAnyMacOS() { return XcodeSDK("MacOSX.sdk"); }
 
   /// The merge function follows a strict order to maintain monotonicity:
@@ -83,7 +83,7 @@ class XcodeSDK {
   llvm::VersionTuple GetVersion() const;
   Type GetType() const;
   llvm::StringRef GetString() const;
-  std::optional<llvm::StringRef> GetSysroot() const;
+  const FileSpec &GetSysroot() const;
   /// Whether this Xcode SDK supports Swift.
   bool SupportsSwift() const;
 
diff --git a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp
index d74c8651e4abc..0bdd1b37d5bd0 100644
--- a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp
+++ b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp
@@ -79,14 +79,6 @@ static Status ExceptionMaskValidator(const char *string, void *unused) {
   return {};
 }
 
-static bool XcodeSysrootExists(XcodeSDK const &sdk) {
-  auto maybe_sysroot = sdk.GetSysroot();
-  if (!maybe_sysroot)
-    return false;
-
-  return FileSystem::Instance().Exists(*maybe_sysroot);
-}
-
 /// Destructor.
 ///
 /// The destructor is virtual since this class is designed to be
@@ -1434,8 +1426,8 @@ PlatformDarwin::ResolveSDKPathFromDebugInfo(Module &module) {
 
   auto [sdk, _] = std::move(*sdk_or_err);
 
-  if (XcodeSysrootExists(sdk))
-    return sdk.GetSysroot()->str();
+  if (FileSystem::Instance().Exists(sdk.GetSysroot()))
+    return sdk.GetSysroot().GetPath();
 
   auto path_or_err = HostInfo::GetSDKRoot(HostInfo::SDKOptions{sdk});
   if (!path_or_err)
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
index 9b5eb68652f58..eecc8269006c2 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -1012,7 +1012,7 @@ XcodeSDK SymbolFileDWARF::ParseXcodeSDK(CompileUnit &comp_unit) {
       local_module_sp->RegisterXcodeSDK(sdk, sysroot);
   }
 
-  return {sdk, std::move(sysroot)};
+  return {sdk, FileSpec{std::move(sysroot)}};
 }
 
 size_t SymbolFileDWARF::ParseFunctions(CompileUnit &comp_unit) {
diff --git a/lldb/source/Utility/XcodeSDK.cpp b/lldb/source/Utility/XcodeSDK.cpp
index 9e22720053e91..02cf7866e22fb 100644
--- a/lldb/source/Utility/XcodeSDK.cpp
+++ b/lldb/source/Utility/XcodeSDK.cpp
@@ -142,9 +142,7 @@ XcodeSDK::Type XcodeSDK::GetType() const {
 
 llvm::StringRef XcodeSDK::GetString() const { return m_name; }
 
-std::optional<llvm::StringRef> XcodeSDK::GetSysroot() const {
-  return m_sysroot_path;
-}
+const FileSpec &XcodeSDK::GetSysroot() const { return m_sysroot; }
 
 bool XcodeSDK::Info::operator<(const Info &other) const {
   return std::tie(type, version, internal) <
@@ -157,8 +155,8 @@ bool XcodeSDK::Info::operator==(const Info &other) const {
 }
 
 void XcodeSDK::Merge(const XcodeSDK &other) {
-  auto add_internal_sdk_suffix = [](std::string const &sdk) {
-    return sdk.substr(0, sdk.size() - 3) + "Internal.sdk";
+  auto add_internal_sdk_suffix = [](llvm::StringRef sdk) {
+    return (sdk.substr(0, sdk.size() - 3) + "Internal.sdk").str();
   };
 
   // The "bigger" SDK always wins.
@@ -172,8 +170,8 @@ void XcodeSDK::Merge(const XcodeSDK &other) {
       if (llvm::StringRef(m_name).ends_with(".sdk"))
         m_name = add_internal_sdk_suffix(m_name);
 
-      if (m_sysroot_path && llvm::StringRef(*m_sysroot_path).ends_with(".sdk"))
-        m_sysroot_path.emplace(add_internal_sdk_suffix(*m_sysroot_path));
+      if (m_sysroot.GetFileNameExtension() == ".sdk")
+        m_sysroot.SetFilename(add_internal_sdk_suffix(m_sysroot.GetFilename()));
     }
   }
 }
diff --git a/lldb/unittests/Utility/XcodeSDKTest.cpp b/lldb/unittests/Utility/XcodeSDKTest.cpp
index 95307ade4d43a..bca7f1291c425 100644
--- a/lldb/unittests/Utility/XcodeSDKTest.cpp
+++ b/lldb/unittests/Utility/XcodeSDKTest.cpp
@@ -34,16 +34,17 @@ TEST(XcodeSDKTest, ParseTest) {
   EXPECT_EQ(XcodeSDK("MacOSX10.9.sdk").GetVersion(), llvm::VersionTuple(10, 9));
   EXPECT_EQ(XcodeSDK("MacOSX10.15.4.sdk").GetVersion(), llvm::VersionTuple(10, 15));
   EXPECT_EQ(XcodeSDK("MacOSX.sdk").IsAppleInternalSDK(), false);
-  EXPECT_EQ(XcodeSDK("MacOSX.sdk", "/Path/To/MacOSX.sdk").GetSysroot(),
-            "/Path/To/MacOSX.sdk");
+  EXPECT_EQ(
+      XcodeSDK("MacOSX.sdk", FileSpec{"/Path/To/MacOSX.sdk"}).GetSysroot(),
+      FileSpec("/Path/To/MacOSX.sdk"));
   EXPECT_EQ(XcodeSDK("MacOSX10.15.Internal.sdk").GetType(), XcodeSDK::MacOSX);
   EXPECT_EQ(XcodeSDK("MacOSX10.15.Internal.sdk").GetVersion(),
             llvm::VersionTuple(10, 15));
   EXPECT_EQ(XcodeSDK("MacOSX10.15.Internal.sdk").IsAppleInternalSDK(), true);
-  EXPECT_EQ(XcodeSDK("MacOSX10.15.Internal.sdk").GetSysroot(), std::nullopt);
+  EXPECT_FALSE(XcodeSDK("MacOSX10.15.Internal.sdk").GetSysroot());
   EXPECT_EQ(XcodeSDK().GetType(), XcodeSDK::unknown);
   EXPECT_EQ(XcodeSDK().GetVersion(), llvm::VersionTuple());
-  EXPECT_EQ(XcodeSDK().GetSysroot(), std::nullopt);
+  EXPECT_FALSE(XcodeSDK().GetSysroot());
 }
 
 TEST(XcodeSDKTest, MergeTest) {
@@ -64,14 +65,14 @@ TEST(XcodeSDKTest, MergeTest) {
   XcodeSDK empty;
   empty.Merge(XcodeSDK("MacOSX10.14.Internal.sdk"));
   EXPECT_EQ(empty.GetString(), llvm::StringRef("MacOSX10.14.Internal.sdk"));
-  EXPECT_EQ(empty.GetSysroot(), std::nullopt);
-  empty.Merge(XcodeSDK("MacOSX9.5.Internal.sdk", "/Path/To/9.5.sdk"));
-  EXPECT_EQ(empty.GetSysroot(), std::nullopt);
-  empty.Merge(XcodeSDK("MacOSX12.5.sdk", "/Path/To/12.5.sdk"));
-  EXPECT_EQ(empty.GetSysroot(), "/Path/To/12.5.sdk");
-  empty.Merge(
-      XcodeSDK("MacOSX11.5.Internal.sdk", "/Path/To/12.5.Internal.sdk"));
-  EXPECT_EQ(empty.GetSysroot(), "/Path/To/12.5.Internal.sdk");
+  EXPECT_FALSE(empty.GetSysroot());
+  empty.Merge(XcodeSDK("MacOSX9.5.Internal.sdk", FileSpec{"/Path/To/9.5.sdk"}));
+  EXPECT_FALSE(empty.GetSysroot());
+  empty.Merge(XcodeSDK("MacOSX12.5.sdk", FileSpec{"/Path/To/12.5.sdk"}));
+  EXPECT_EQ(empty.GetSysroot(), FileSpec{"/Path/To/12.5.sdk"});
+  empty.Merge(XcodeSDK("MacOSX11.5.Internal.sdk",
+                       FileSpec{"/Path/To/12.5.Internal.sdk"}));
+  EXPECT_EQ(empty.GetSysroot(), FileSpec{"/Path/To/12.5.Internal.sdk"});
 }
 
 #ifndef _WIN32

From 18bc94ac7b92801a214cf957ce0abb8f7c2ca76d Mon Sep 17 00:00:00 2001
From: Michael Buch <michaelbuch12@gmail.com>
Date: Mon, 3 Mar 2025 13:29:28 +0000
Subject: [PATCH 7/8] fixup! remove redundant local variable

---
 lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp | 1 -
 1 file changed, 1 deletion(-)

diff --git a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp
index 0bdd1b37d5bd0..b777914407c6c 100644
--- a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp
+++ b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp
@@ -1395,7 +1395,6 @@ PlatformDarwin::GetSDKPathFromDebugInfo(Module &module) {
         llvm::formatv("No symbol file available for module '{0}'",
                       module.GetFileSpec().GetFilename().AsCString("")));
 
-  std::string sysroot;
   bool found_public_sdk = false;
   bool found_internal_sdk = false;
   XcodeSDK merged_sdk;

From b23e6310b5c1fa65f97391915ed39b8a0e6c54dd Mon Sep 17 00:00:00 2001
From: Michael Buch <michaelbuch12@gmail.com>
Date: Mon, 3 Mar 2025 13:32:58 +0000
Subject: [PATCH 8/8] fixup! fix test expectation

---
 lldb/unittests/SymbolFile/DWARF/XcodeSDKModuleTests.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lldb/unittests/SymbolFile/DWARF/XcodeSDKModuleTests.cpp b/lldb/unittests/SymbolFile/DWARF/XcodeSDKModuleTests.cpp
index c1e471653a279..fe6755d80c3aa 100644
--- a/lldb/unittests/SymbolFile/DWARF/XcodeSDKModuleTests.cpp
+++ b/lldb/unittests/SymbolFile/DWARF/XcodeSDKModuleTests.cpp
@@ -330,7 +330,7 @@ SDKPathParsingTestData sdkPathParsingTestCases[] = {
          {"/Library/Developer/CommandLineTools/SDKs/iPhoneOS14.1.sdk",
           "/Path/To/SDKs/MacOSX11.3.Internal.sdk"},
      .expect_mismatch = false,
-     .expect_internal_sdk = false,
+     .expect_internal_sdk = true,
      .expect_sdk_path_pattern = "iPhoneOS14.1.Internal.sdk"},
 };