[clang][driver] Cleanup UEFI toolchain driver

UEFI toolchain predefines clean up. Introducing new __PECOFF__ predefine
for targets that produce PE COFF binaries. Updating UEFI header includes
to not include system include directories.

Author: Prabhuk

clang/lib/Basic/Targets/OSTargets.cpp

@@ -260,6 +260,7 @@ static void addVisualCDefines(const LangOptions &Opts, MacroBuilder &Builder) {
 void addWindowsDefines(const llvm::Triple &Triple, const LangOptions &Opts,
                        MacroBuilder &Builder) {
   Builder.defineMacro("_WIN32");
+  Builder.defineMacro("__PECOFF__");
   if (Triple.isArch64Bit())
     Builder.defineMacro("_WIN64");
   if (Triple.isWindowsGNUEnvironment())

clang/lib/Basic/Targets/OSTargets.h

@@ -783,7 +783,11 @@ template <typename Target>
 class LLVM_LIBRARY_VISIBILITY UEFITargetInfo : public OSTargetInfo<Target> {
 protected:
   void getOSDefines(const LangOptions &Opts, const llvm::Triple &Triple,
-                    MacroBuilder &Builder) const override {}
+                    MacroBuilder &Builder) const override {
+    Builder.defineMacro("__PECOFF__");
+    Builder.defineMacro("__UEFI__");
+    // Builder.defineMacro("_WIN32");
+  }
 
 public:
   UEFITargetInfo(const llvm::Triple &Triple, const TargetOptions &Opts)

clang/lib/Basic/Targets/X86.h

@@ -826,11 +826,6 @@ class LLVM_LIBRARY_VISIBILITY UEFIX86_64TargetInfo
                           "i64:64-i128:128-f80:128-n8:16:32:64-S128");
   }
 
-  void getTargetDefines(const LangOptions &Opts,
-                        MacroBuilder &Builder) const override {
-    getOSDefines(Opts, X86TargetInfo::getTriple(), Builder);
-  }
-
   BuiltinVaListKind getBuiltinVaListKind() const override {
     return TargetInfo::CharPtrBuiltinVaList;
   }

clang/lib/Driver/ToolChains/UEFI.cpp

@@ -35,6 +35,24 @@ UEFI::UEFI(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
 
 Tool *UEFI::buildLinker() const { return new tools::uefi::Linker(*this); }
 
+void UEFI::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
+                                     ArgStringList &CC1Args) const {
+  if (DriverArgs.hasArg(options::OPT_nostdinc))
+    return;
+
+  if (!DriverArgs.hasArg(options::OPT_nobuiltininc)) {
+    SmallString<128> Dir(getDriver().ResourceDir);
+    llvm::sys::path::append(Dir, "include");
+    addSystemInclude(DriverArgs, CC1Args, Dir.str());
+  }
+
+  if (DriverArgs.hasArg(options::OPT_nostdlibinc))
+    return;
+
+  if (std::optional<std::string> Path = getStdlibIncludePath())
+    addSystemInclude(DriverArgs, CC1Args, *Path);
+}
+
 void tools::uefi::Linker::ConstructJob(Compilation &C, const JobAction &JA,
                                        const InputInfo &Output,
                                        const InputInfoList &Inputs,

clang/lib/Driver/ToolChains/UEFI.h

@@ -51,6 +51,10 @@ class LLVM_LIBRARY_VISIBILITY UEFI : public ToolChain {
     return false;
   }
   bool isPICDefaultForced() const override { return true; }
+
+  void
+  AddClangSystemIncludeArgs(const llvm::opt::ArgList &DriverArgs,
+                            llvm::opt::ArgStringList &CC1Args) const override;
 };
 
 } // namespace toolchains

clang/lib/Lex/InitHeaderSearch.cpp

@@ -305,6 +305,7 @@ bool InitHeaderSearch::ShouldAddDefaultIncludePaths(
   case llvm::Triple::PS5:
   case llvm::Triple::RTEMS:
   case llvm::Triple::Solaris:
+  case llvm::Triple::UEFI:
   case llvm::Triple::WASI:
   case llvm::Triple::ZOS:
     return false;

libcxx/include/__configuration/platform.h

@@ -22,6 +22,8 @@
 #  define _LIBCPP_OBJECT_FORMAT_MACHO 1
 #elif defined(_WIN32)
 #  define _LIBCPP_OBJECT_FORMAT_COFF 1
+#elif defined(__UEFI__)
+#  define _LIBCPP_OBJECT_FORMAT_COFF 1
 #elif defined(__wasm__)
 #  define _LIBCPP_OBJECT_FORMAT_WASM 1
 #elif defined(_AIX)