[darwin] parse the SDK settings from SDKSettings.json if it exists and pass in the -target-sdk-version to the compiler and backend

[arphaman]

Summary

This patch is a follow-up to the LLVM SDK Version metadata support: https://reviews.llvm.org/D55612.

This patch adds support for reading the SDKSettings.json file in the Darwin driver. This file is used by the driver to determine the SDK's version, and it uses that information to pass it down to the compiler using the new -target-sdk-version=. This option is then used to set the appropriate SDK Version module metadata introduced in https://reviews.llvm.org/D55612.

[steven_wu]

See comments inline.

include/clang/Driver/DarwinSDKInfo.h

2

Can this just be in Toolchains/Darwin.h?

37

Isn't parseSDKSettings enough? And it can just return Optional<VersionTuple>?

lib/Driver/ToolChains/Darwin.cpp

2102

We also has this InferredFromSDK when we infer deployment target, which can be used as a fallback method.

The result of parsing JSON should be available to InferredFromSDK in deployment target setting.

Bonus point is to set "-sdk_version" flag passing to ld64.

[arphaman]

include/clang/Driver/DarwinSDKInfo.h

2

No, we need to expose it to clients like Swift.

[arphaman]

include/clang/Driver/DarwinSDKInfo.h

37

We will support other fields besides VersionTuple in the SDKSettings, so that's why we have a structure.

[arphaman]

Updated to infer deployment target version from SDK versions specified in the JSON file and to allow inferring the SDK version from the SDK path.

[arphaman]

lib/Driver/ToolChains/Darwin.cpp

2102

Done.
We're not planning to pass it down to the linker.

[arphaman]

Ensure test will pass on non-darwin.

[steven_wu]

Other than a small design choice commented inline, LGTM.

include/clang/Driver/DarwinSDKInfo.h

37

I feel like for this usage, it is better to return Expected<DarwinSDKInfo> with all the fields being Optional?

[arphaman]

include/clang/Driver/DarwinSDKInfo.h

37

Hmm, we want to assume that version exists for future uses. I feel like the current type captures the intention better.

[steven_wu]

include/clang/Driver/DarwinSDKInfo.h

37

I think it is fine for current use. We can always change in the future.

[tra]

Would that be OK to use target_sdk_version to pass *CUDA* SDK version to the CC1 compilations?
I have upcoming changes that need to know the version to generate correct glue IR for CUDA. The driver currently figures out detected CUDA version in lib/Driver/ToolChains/Cuda.cpp and I could use -target-sdk-version to pass it on to CC1 instances.

On one hand CUDA is a target SDK and the option appears to be accessible exactly where I need it. On the other hand, my use case is not *exactly* the case -target-sdk-version was intended for (i.e. it's not darwin and it has nothing to do with module metadata, though it *may* be eventually useful there even for CUDA).

If using the option for CUDA sounds like too much of a hack, I guess I can add a separate -cuda-sdk-version=, though it would effectively replicate some of this patch.

Opinions?

[arphaman]

In D55673#1377404, @tra wrote:

Would that be OK to use target_sdk_version to pass *CUDA* SDK version to the CC1 compilations?
I have upcoming changes that need to know the version to generate correct glue IR for CUDA. The driver currently figures out detected CUDA version in lib/Driver/ToolChains/Cuda.cpp and I could use -target-sdk-version to pass it on to CC1 instances.

On one hand CUDA is a target SDK and the option appears to be accessible exactly where I need it. On the other hand, my use case is not *exactly* the case -target-sdk-version was intended for (i.e. it's not darwin and it has nothing to do with module metadata, though it *may* be eventually useful there even for CUDA).

If using the option for CUDA sounds like too much of a hack, I guess I can add a separate -cuda-sdk-version=, though it would effectively replicate some of this patch.

Opinions?

I would be ok with reusing that option, as long as it's documented that there is a difference in terms of how it can be used.

[tra]

I would be ok with reusing that option, as long as it's documented that there is a difference in terms of how it can be used.

The patch is in https://reviews.llvm.org/D57487
It does not look like we're formally documenting CC1 options anywhere. I've added some comments next to SDKVersion in TargetOptions.h. PTAL.

include/clang/Basic/DiagnosticDriverKinds.td

 
 def warn_drv_experimental_isel_incomplete_opt : Warning<
   "-fexperimental-isel support is incomplete for this architecture at the current optimization level">,
   InGroup<ExperimentalISel>;
 
 def warn_drv_moutline_unsupported_opt : Warning<
   "The '%0' architecture does not support -moutline; flag ignored">,
   InGroup<OptionIgnored>;
+
+def warn_drv_darwin_sdk_invalid_settings : Warning<
+  "SDK settings were ignored as 'SDKSettings.json' could not be parsed">,
+  InGroup<DiagGroup<"darwin-sdk-settings">>;
 }

include/clang/Basic/TargetInfo.h

   /// corresponding target specific DWARF address space.
   ///
   /// \returns Otherwise return None and no conversion will be emitted in the
   /// DWARF.
   virtual Optional<unsigned> getDWARFAddressSpace(unsigned AddressSpace) const {
     return None;
   }
 
+  /// \returns The version of the SDK which was used during the compilation if
+  /// one was specified, or an empty version otherwise.
+  const llvm::VersionTuple &getSDKVersion() const {
+    return getTargetOpts().SDKVersion;
+  }
+
   /// Check the target is valid after it is fully initialized.
   virtual bool validateTarget(DiagnosticsEngine &Diags) const {
     return true;
   }
 
 protected:
   virtual uint64_t getPointerWidthV(unsigned AddrSpace) const {
     return PointerWidth;

include/clang/Basic/TargetOptions.h

 /// \file
 /// Defines the clang::TargetOptions class.
 ///
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_BASIC_TARGETOPTIONS_H
 #define LLVM_CLANG_BASIC_TARGETOPTIONS_H
 
-#include <string>
-#include <vector>
 #include "clang/Basic/OpenCLOptions.h"
+#include "llvm/Support/VersionTuple.h"
 #include "llvm/Target/TargetOptions.h"
+#include <string>
+#include <vector>
 
 namespace clang {
 
 /// Options for controlling the target.
 class TargetOptions {
 public:
   /// The name of the target triple to compile for.
   std::string Triple;
public:
   /// address space.
   bool NVPTXUseShortPointers = false;
 
   // The code model to be used as specified by the user. Corresponds to
   // CodeModel::Model enum defined in include/llvm/Support/CodeGen.h, plus
   // "default" for the case when the user has not explicitly specified a
   // code model.
   std::string CodeModel;
+
+  /// The version of the SDK which was used during the compilation.
+  VersionTuple SDKVersion;
 };
 
 }  // end namespace clang
 
 #endif

include/clang/Driver/CC1Options.td

 def target_cpu : Separate<["-"], "target-cpu">,
   HelpText<"Target a specific cpu type">;
 def target_feature : Separate<["-"], "target-feature">,
   HelpText<"Target specific attributes">;
 def triple : Separate<["-"], "triple">,
   HelpText<"Specify target triple (e.g. i686-apple-darwin9)">;
 def target_abi : Separate<["-"], "target-abi">,
   HelpText<"Target a particular ABI type">;
+def target_sdk_version_EQ : Joined<["-"], "target-sdk-version=">,
+  HelpText<"The version of target SDK used for compilation">;
 
 }
 
 def target_linker_version : Separate<["-"], "target-linker-version">,
   HelpText<"Target linker version">;
 def triple_EQ : Joined<["-"], "triple=">, Alias<triple>;
 def mfpmath : Separate<["-"], "mfpmath">,
   HelpText<"Which unit to use for fp math">;

include/clang/Driver/DarwinSDKInfo.h

+//===--- DarwinSDKInfo.h - SDK Information parser for darwin ----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_DRIVER_DARWIN_SDK_INFO_H
+#define LLVM_CLANG_DRIVER_DARWIN_SDK_INFO_H
+
+#include "clang/Basic/LLVM.h"
+#include "llvm/Support/Error.h"
+#include "llvm/Support/VersionTuple.h"
+#include "llvm/Support/VirtualFileSystem.h"
+
+namespace clang {
+namespace driver {
+
+/// The information about the darwin SDK that was used during this compilation.
+class DarwinSDKInfo {
+public:
+  DarwinSDKInfo(llvm::VersionTuple Version) : Version(Version) {}
+
+  const llvm::VersionTuple &getVersion() const { return Version; }
+
+private:
+  llvm::VersionTuple Version;
+};
+
+/// Parse the SDK information from the SDKSettings.json file.
+///
+/// \returns an error if the SDKSettings.json file is invalid, None if the
+/// SDK has no SDKSettings.json, or a valid \c DarwinSDKInfo otherwise.
+Expected<Optional<DarwinSDKInfo>> parseDarwinSDKInfo(llvm::vfs::FileSystem &VFS,
+                                                     StringRef SDKRootPath);
+
+} // end namespace driver
+} // end namespace clang
+
+#endif // LLVM_CLANG_DRIVER_DARWIN_SDK_INFO_H

lib/CodeGen/ModuleBuilder.cpp

llvm::Module *StartModule(llvm::StringRef ModuleName,
       return M.get();
     }
 
     void Initialize(ASTContext &Context) override {
       Ctx = &Context;
 
       M->setTargetTriple(Ctx->getTargetInfo().getTriple().getTriple());
       M->setDataLayout(Ctx->getTargetInfo().getDataLayout());
+      const auto &SDKVersion = Ctx->getTargetInfo().getSDKVersion();
+      if (!SDKVersion.empty())
+        M->setSDKVersion(SDKVersion);
       Builder.reset(new CodeGen::CodeGenModule(Context, HeaderSearchOpts,
                                                PreprocessorOpts, CodeGenOpts,
                                                *M, Diags, CoverageInfo));
 
       for (auto &&Lib : CodeGenOpts.DependentLibraries)
         Builder->AddDependentLib(Lib);
       for (auto &&Opt : CodeGenOpts.LinkerOptions)
         Builder->AppendLinkerOptions(Opt);

lib/Driver/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
   BinaryFormat
   Option
   Support
   )
 
 if(WIN32)
   # MSVCToolChain.cpp uses version.dll.
   set(system_libs version)
 endif()
 
 add_clang_library(clangDriver
   Action.cpp
   Compilation.cpp
+  DarwinSDKInfo.cpp
   Distro.cpp
   Driver.cpp
   DriverOptions.cpp
   Job.cpp
   Multilib.cpp
   Phases.cpp
   SanitizerArgs.cpp
   Tool.cpp

lib/Driver/DarwinSDKInfo.cpp

+//===--- DarwinSDKInfo.cpp - SDK Information parser for darwin - ----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Driver/DarwinSDKInfo.h"
+#include "llvm/Support/ErrorOr.h"
+#include "llvm/Support/JSON.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/Path.h"
+
+using namespace clang::driver;
+using namespace clang;
+
+Expected<Optional<DarwinSDKInfo>>
+driver::parseDarwinSDKInfo(llvm::vfs::FileSystem &VFS, StringRef SDKRootPath) {
+  llvm::SmallString<256> Filepath = SDKRootPath;
+  llvm::sys::path::append(Filepath, "SDKSettings.json");
+  llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> File =
+      VFS.getBufferForFile(Filepath);
+  if (!File) {
+    // If the file couldn't be read, assume it just doesn't exist.
+    return None;
+  }
+  Expected<llvm::json::Value> Result =
+      llvm::json::parse(File.get()->getBuffer());
+  if (!Result)
+    return Result.takeError();
+
+  if (const auto *Obj = Result->getAsObject()) {
+    auto VersionString = Obj->getString("Version");
+    if (VersionString) {
+      VersionTuple Version;
+      if (!Version.tryParse(*VersionString))
+        return DarwinSDKInfo(Version);
+    }
+  }
+  return llvm::make_error<llvm::StringError>("invalid SDKSettings.json",
+                                             llvm::inconvertibleErrorCode());
+}

lib/Driver/ToolChains/Darwin.h

 //===--- Darwin.h - Darwin ToolChain Implementations ------------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_LIB_DRIVER_TOOLCHAINS_DARWIN_H
 #define LLVM_CLANG_LIB_DRIVER_TOOLCHAINS_DARWIN_H
 
 #include "Cuda.h"
-#include "clang/Driver/XRayArgs.h"
+#include "clang/Driver/DarwinSDKInfo.h"
 #include "clang/Driver/Tool.h"
 #include "clang/Driver/ToolChain.h"
+#include "clang/Driver/XRayArgs.h"
 
 namespace clang {
 namespace driver {
 
 namespace toolchains {
 class MachO;
 } // end namespace toolchains
 
public:
   };
 
   mutable DarwinPlatformKind TargetPlatform;
   mutable DarwinEnvironmentKind TargetEnvironment;
 
   /// The OS version we are targeting.
   mutable VersionTuple TargetVersion;
 
+  /// The information about the darwin SDK that was used.
+  mutable Optional<DarwinSDKInfo> SDKInfo;
+
   CudaInstallationDetector CudaInstallation;
 
 private:
   void AddDeploymentTarget(llvm::opt::DerivedArgList &Args) const;
 
 public:
   Darwin(const Driver &D, const llvm::Triple &Triple,
          const llvm::opt::ArgList &Args);

lib/Driver/ToolChains/Darwin.cpp

static DarwinPlatform createFromSDK(DarwinPlatformKind Platform,
     Result.InferSimulatorFromArch = false;
     return Result;
   }
   static DarwinPlatform createFromArch(llvm::Triple::OSType OS,
                                        StringRef Value) {
     return DarwinPlatform(InferredFromArch, getPlatformFromOS(OS), Value);
   }
 
+  /// Constructs an inferred SDKInfo value based on the version inferred from
+  /// the SDK path itself. Only works for values that were created by inferring
+  /// the platform from the SDKPath.
+  DarwinSDKInfo inferSDKInfo() {
+    assert(Kind == InferredFromSDK && "can infer SDK info only");
+    llvm::VersionTuple Version;
+    bool IsValid = !Version.tryParse(OSVersion);
+    (void)IsValid;
+    assert(IsValid && "invalid SDK version");
+    return DarwinSDKInfo(Version);
+  }
+
 private:
   DarwinPlatform(SourceKind Kind, DarwinPlatformKind Platform, Arg *Argument)
       : Kind(Kind), Platform(Platform), Argument(Argument) {}
   DarwinPlatform(SourceKind Kind, DarwinPlatformKind Platform, StringRef Value,
                  Arg *Argument = nullptr)
       : Kind(Kind), Platform(Platform), OSVersion(Value), Argument(Argument) {}
 
   static DarwinPlatformKind getPlatformFromOS(llvm::Triple::OSType OS) {
if (!Target.value().empty())
       return DarwinPlatform::createDeploymentTargetEnv(
           (Darwin::DarwinPlatformKind)Target.index(), EnvVars[Target.index()],
           Target.value());
   }
   return None;
 }
 
 /// Tries to infer the deployment target from the SDK specified by -isysroot
-/// (or SDKROOT).
-Optional<DarwinPlatform> inferDeploymentTargetFromSDK(DerivedArgList &Args) {
+/// (or SDKROOT). Uses the version specified in the SDKSettings.json file if
+/// it's available.
+Optional<DarwinPlatform>
+inferDeploymentTargetFromSDK(DerivedArgList &Args,
+                             const Optional<DarwinSDKInfo> &SDKInfo) {
   const Arg *A = Args.getLastArg(options::OPT_isysroot);
   if (!A)
     return None;
   StringRef isysroot = A->getValue();
   StringRef SDK = Darwin::getSDKName(isysroot);
   if (!SDK.size())
     return None;
+
+  std::string Version;
+  if (SDKInfo) {
+    // Get the version from the SDKSettings.json if it's available.
+    Version = SDKInfo->getVersion().getAsString();
+  } else {
     // Slice the version number out.
     // Version number is between the first and the last number.
     size_t StartVer = SDK.find_first_of("0123456789");
     size_t EndVer = SDK.find_last_of("0123456789");
-  if (StartVer != StringRef::npos && EndVer > StartVer) {
-    StringRef Version = SDK.slice(StartVer, EndVer + 1);
-    if (SDK.startswith("iPhoneOS") || SDK.startswith("iPhoneSimulator"))
-      return DarwinPlatform::createFromSDK(
-          Darwin::IPhoneOS, Version,
-          /*IsSimulator=*/SDK.startswith("iPhoneSimulator"));
-    else if (SDK.startswith("MacOSX"))
-      return DarwinPlatform::createFromSDK(Darwin::MacOS,
-                                           getSystemOrSDKMacOSVersion(Version));
-    else if (SDK.startswith("WatchOS") || SDK.startswith("WatchSimulator"))
-      return DarwinPlatform::createFromSDK(
-          Darwin::WatchOS, Version,
-          /*IsSimulator=*/SDK.startswith("WatchSimulator"));
-    else if (SDK.startswith("AppleTVOS") || SDK.startswith("AppleTVSimulator"))
-      return DarwinPlatform::createFromSDK(
-          Darwin::TvOS, Version,
-          /*IsSimulator=*/SDK.startswith("AppleTVSimulator"));
-  }
+    if (StartVer != StringRef::npos && EndVer > StartVer)
+      Version = SDK.slice(StartVer, EndVer + 1);
+  }
+  if (Version.empty())
+    return None;
+
   return None;
 }
 
 std::string getOSVersion(llvm::Triple::OSType OS, const llvm::Triple &Triple,
                          const Driver &TheDriver) {
   unsigned Major, Minor, Micro;
   llvm::Triple SystemTriple(llvm::sys::getProcessTriple());
   switch (OS) {
Optional<DarwinPlatform> getDeploymentTargetFromTargetArg(
   if (Triple.getOS() == llvm::Triple::Darwin ||
       Triple.getOS() == llvm::Triple::UnknownOS)
     return None;
   std::string OSVersion = getOSVersion(Triple.getOS(), Triple, TheDriver);
   return DarwinPlatform::createFromTarget(Triple, OSVersion,
                                           Args.getLastArg(options::OPT_target));
 }
 
+Optional<DarwinSDKInfo> parseSDKSettings(llvm::vfs::FileSystem &VFS,
+                                         const ArgList &Args,
+                                         const Driver &TheDriver) {
+  const Arg *A = Args.getLastArg(options::OPT_isysroot);
+  if (!A)
+    return None;
+  StringRef isysroot = A->getValue();
+  auto SDKInfoOrErr = driver::parseDarwinSDKInfo(VFS, isysroot);
+  if (!SDKInfoOrErr) {
+    llvm::consumeError(SDKInfoOrErr.takeError());
+    TheDriver.Diag(diag::warn_drv_darwin_sdk_invalid_settings);
+    return None;
+  }
+  return *SDKInfoOrErr;
+}
+
 } // namespace
 
 void Darwin::AddDeploymentTarget(DerivedArgList &Args) const {
   const OptTable &Opts = getDriver().getOpts();
 
   // Support allowing the SDKROOT environment variable used by xcrun and other
   // Xcode tools to define the default sysroot, by making it the default for
   // isysroot.
   if (const Arg *A = Args.getLastArg(options::OPT_isysroot)) {
     // Warn if the path does not exist.
     if (!getVFS().exists(A->getValue()))
       getDriver().Diag(clang::diag::warn_missing_sysroot) << A->getValue();
   } else {
     if (char *env = ::getenv("SDKROOT")) {
       // We only use this value as the default if it is an absolute path,
       // exists, and it is not the root path.
       if (llvm::sys::path::is_absolute(env) && getVFS().exists(env) &&
           StringRef(env) != "/") {
         Args.append(Args.MakeSeparateArg(
             nullptr, Opts.getOption(options::OPT_isysroot), env));
       }
     }
   }
 
+  // Read the SDKSettings.json file for more information, like the SDK version
+  // that we can pass down to the compiler.
+  SDKInfo = parseSDKSettings(getVFS(), Args, getDriver());
+
   // The OS and the version can be specified using the -target argument.
   Optional<DarwinPlatform> OSTarget =
       getDeploymentTargetFromTargetArg(Args, getTriple(), getDriver());
   if (OSTarget) {
     Optional<DarwinPlatform> OSVersionArgTarget =
         getDeploymentTargetFromOSVersionArg(Args, getDriver());
     if (OSVersionArgTarget) {
       unsigned TargetMajor, TargetMinor, TargetMicro;
if (OSTarget) {
     OSTarget = getDeploymentTargetFromOSVersionArg(Args, getDriver());
     // If no deployment target was specified on the command line, check for
     // environment defines.
     if (!OSTarget) {
       OSTarget =
           getDeploymentTargetFromEnvironmentVariables(getDriver(), getTriple());
       if (OSTarget) {
         // Don't infer simulator from the arch when the SDK is also specified.
-        Optional<DarwinPlatform> SDKTarget = inferDeploymentTargetFromSDK(Args);
+        Optional<DarwinPlatform> SDKTarget =
+            inferDeploymentTargetFromSDK(Args, SDKInfo);
         if (SDKTarget)
           OSTarget->setEnvironment(SDKTarget->getEnvironment());
       }
     }
     // If there is no command-line argument to specify the Target version and
     // no environment variable defined, see if we can set the default based
-    // on -isysroot.
-    if (!OSTarget)
-      OSTarget = inferDeploymentTargetFromSDK(Args);
+    // on -isysroot using SDKSettings.json if it exists.
+    if (!OSTarget) {
+      OSTarget = inferDeploymentTargetFromSDK(Args, SDKInfo);
+      /// If the target was successfully constructed from the SDK path, try to
+      /// infer the SDK info if the SDK doesn't have it.
+      if (OSTarget && !SDKInfo)
+        SDKInfo = OSTarget->inferSDKInfo();
+    }
     // If no OS targets have been specified, try to guess platform from -target
     // or arch name and compute the version from the triple.
     if (!OSTarget)
       OSTarget =
           inferDeploymentTargetFromArch(Args, *this, getTriple(), getDriver());
   }
 
   assert(OSTarget && "Unable to infer Darwin variant");
void Darwin::addClangTargetOptions(const llvm::opt::ArgList &DriverArgs,
                                    llvm::opt::ArgStringList &CC1Args,
                                    Action::OffloadKind DeviceOffloadKind) const {
   // Pass "-faligned-alloc-unavailable" only when the user hasn't manually
   // enabled or disabled aligned allocations.
   if (!DriverArgs.hasArgNoClaim(options::OPT_faligned_allocation,
                                 options::OPT_fno_aligned_allocation) &&
       isAlignedAllocationUnavailable())
     CC1Args.push_back("-faligned-alloc-unavailable");
+
+  if (SDKInfo) {
+    /// Pass the SDK version to the compiler when the SDK information is
+    /// available.
+    std::string Arg;
+    llvm::raw_string_ostream OS(Arg);
+    OS << "-target-sdk-version=" << SDKInfo->getVersion();
+    CC1Args.push_back(DriverArgs.MakeArgString(OS.str()));
+  }
 }
 
 DerivedArgList *
 Darwin::TranslateArgs(const DerivedArgList &Args, StringRef BoundArch,
                       Action::OffloadKind DeviceOffloadKind) const {
   // First get the generic Apple args, before moving onto Darwin-specific ones.
   DerivedArgList *DAL =
       MachO::TranslateArgs(Args, BoundArch, DeviceOffloadKind);

lib/Frontend/CompilerInvocation.cpp

static void ParseTargetArgs(TargetOptions &Opts, ArgList &Args,
   // Use the default target triple if unspecified.
   if (Opts.Triple.empty())
     Opts.Triple = llvm::sys::getDefaultTargetTriple();
   Opts.Triple = llvm::Triple::normalize(Opts.Triple);
   Opts.OpenCLExtensionsAsWritten = Args.getAllArgValues(OPT_cl_ext_EQ);
   Opts.ForceEnableInt128 = Args.hasArg(OPT_fforce_enable_int128);
   Opts.NVPTXUseShortPointers = Args.hasFlag(
       options::OPT_fcuda_short_ptr, options::OPT_fno_cuda_short_ptr, false);
+  if (Arg *A = Args.getLastArg(options::OPT_target_sdk_version_EQ)) {
+    llvm::VersionTuple Version;
+    if (Version.tryParse(A->getValue()))
+      Diags.Report(diag::err_drv_invalid_value)
+          << A->getAsString(Args) << A->getValue();
+    else
+      Opts.SDKVersion = Version;
+  }
 }
 
 bool CompilerInvocation::CreateFromArgs(CompilerInvocation &Res,
                                         const char *const *ArgBegin,
                                         const char *const *ArgEnd,
                                         DiagnosticsEngine &Diags) {
   bool Success = true;
 

test/CodeGen/darwin-sdk-version.c

+// RUN: %clang_cc1 -triple x86_64-apple-macosx10.14 -target-sdk-version=10.14.1 -emit-llvm -o - %s | FileCheck %s
+
+// CHECK: !llvm.module.flags = !{!0
+// CHECK: !0 = !{i32 2, !"SDK Version", [3 x i32] [i32 10, i32 14, i32 1]}

test/Driver/Inputs/MacOSX10.14.sdk/SDKSettings.json

+{"Version":"10.14"}

test/Driver/darwin-sdk-version.c

+// RUN: %clang -target x86_64-apple-macosx10.13 -isysroot %S/Inputs/MacOSX10.14.sdk -c -### %s 2>&1 \
+// RUN:   | FileCheck %s
+// RUN: env SDKROOT=%S/Inputs/MacOSX10.14.sdk %clang -target x86_64-apple-macosx10.13 -c -### %s 2>&1 \
+// RUN:   | FileCheck %s
+//
+// RUN: rm -rf %t/SDKs/MacOSX10.10.sdk
+// RUN: mkdir -p %t/SDKs/MacOSX10.10.sdk
+// RUN: %clang -isysroot %t/SDKs/MacOSX10.10.sdk -c -### %s 2>&1 \
+// RUN:   | FileCheck --check-prefix=INFER_SDK_VERSION %s
+// RUN: cp %S/Inputs/MacOSX10.14.sdk/SDKSettings.json %t/SDKs/MacOSX10.10.sdk
+// RUN: %clang -isysroot %t/SDKs/MacOSX10.10.sdk -c -### %s 2>&1 \
+// RUN:   | FileCheck --check-prefix=INFER_DEPLOYMENT_TARGET_VERSION %s
+// REQUIRES: system-darwin && native
+//
+// RUN: rm -rf %t/SDKs/MacOSX10.14.sdk
+// RUN: mkdir -p %t/SDKs/MacOSX10.14.sdk
+// RUN: %clang -target x86_64-apple-macosx10.13 -isysroot %t/SDKs/MacOSX10.14.sdk -c -### %s 2>&1 \
+// RUN:   | FileCheck --check-prefix=NO_VERSION %s
+//
+// RUN: rm -rf %t/SDKs/MacOSX10.14.sdk
+// RUN: mkdir -p %t/SDKs/MacOSX10.14.sdk
+// RUN: echo '{broken json' > %t/SDKs/MacOSX10.14.sdk/SDKSettings.json
+// RUN: %clang -target x86_64-apple-macosx10.13 -isysroot %t/SDKs/MacOSX10.14.sdk -c -### %s 2>&1 \
+// RUN:   | FileCheck --check-prefixes=NO_VERSION,ERROR %s
+//
+// RUN: rm -rf %t/SDKs/MacOSX10.14.sdk
+// RUN: mkdir -p %t/SDKs/MacOSX10.14.sdk
+// RUN: echo '{"Version":1}' > %t/SDKs/MacOSX10.14.sdk/SDKSettings.json
+// RUN: %clang -target x86_64-apple-macosx10.13 -isysroot %t/SDKs/MacOSX10.14.sdk -c -### %s 2>&1 \
+// RUN:   | FileCheck --check-prefixes=NO_VERSION,ERROR %s
+
+// CHECK: -target-sdk-version=10.14
+// INFER_SDK_VERSION: "-triple" "x86_64-apple-macosx10.10.0"
+// INFER_SDK_VERSION-SAME: -target-sdk-version=10.10
+// INFER_DEPLOYMENT_TARGET_VERSION: "-triple" "x86_64-apple-macosx10.14.0"
+// NO_VERSION-NOT: target-sdk-version
+// ERROR: warning: SDK settings were ignored as 'SDKSettings.json' could not be parsed

test/Frontend/ast-main.c

-// RUN: %clang -emit-llvm -S -o %t1.ll -x c - < %s
-// RUN: %clang -emit-ast -o %t.ast %s
-// RUN: %clang -emit-llvm -S -o %t2.ll -x ast - < %t.ast
+// RUN: env SDKROOT="/" %clang -emit-llvm -S -o %t1.ll -x c - < %s
+// RUN: env SDKROOT="/" %clang -emit-ast -o %t.ast %s
+// RUN: env SDKROOT="/" %clang -emit-llvm -S -o %t2.ll -x ast - < %t.ast
 // RUN: diff %t1.ll %t2.ll
 
 int main() {
   return 0;
 }

test/Frontend/ast-main.cpp

-// RUN: %clang -emit-llvm -S -o %t1.ll -x c++ - < %s
-// RUN: %clang -fno-delayed-template-parsing -emit-ast -o %t.ast %s
-// RUN: %clang -emit-llvm -S -o %t2.ll -x ast - < %t.ast
+// RUN: env SDKROOT="/" %clang -emit-llvm -S -o %t1.ll -x c++ - < %s
+// RUN: env SDKROOT="/" %clang -fno-delayed-template-parsing -emit-ast -o %t.ast %s
+// RUN: env SDKROOT="/" %clang -emit-llvm -S -o %t2.ll -x ast - < %t.ast
 // RUN: diff %t1.ll %t2.ll
 
 // http://llvm.org/bugs/show_bug.cgi?id=15377
 template<typename T>
 struct S {
     T *mf();
 };
 template<typename T>