Parameterize Initialization of 'clang::CodeGenerator' on a TargetInfo instance which may differ from the one in the ASTContext

As per swiftlang/swift#65930, Swift compiler's built-in Clang instance may require to perform type-checking against one OS version and compilation/code-generation against an earlier version. This change allows Swift to configure it's built-in Clang code-generator with a custom 'TargetInfo'.

Part of rdar://113712186

Author: artemcm

clang/include/clang/AST/ASTConsumer.h

@@ -27,6 +27,7 @@ namespace clang {
   class VarDecl;
   class FunctionDecl;
   class ImportDecl;
+  class TargetInfo;
 
 /// ASTConsumer - This is an abstract interface that should be implemented by
 /// clients that read ASTs.  This abstraction layer allows the client to be
@@ -47,6 +48,14 @@ class ASTConsumer {
   /// ASTContext.
   virtual void Initialize(ASTContext &Context) {}
 
+  /// Initialize - This is called to initialize the consumer, providing the
+  /// ASTContext. 'CodeGenTargetInfo' specifies the code-generation configuration
+  /// for this compilation instance, which may differ from the one carried
+  /// by the Context itself only in the OS Version number -
+  /// for example when type-checking must be performed against an epoch OS version
+  /// while code-generation must run according to the user-specified OS version.
+  virtual void Initialize(ASTContext &Context, const TargetInfo &CodeGenTargetInfo) {}
+
   /// HandleTopLevelDecl - Handle the specified top-level declaration.  This is
   /// called by the parser to process every top-level Decl*.
   ///

clang/lib/CodeGen/CodeGenModule.cpp

@@ -337,12 +337,14 @@ CodeGenModule::CodeGenModule(ASTContext &C,
                              IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS,
                              const HeaderSearchOptions &HSO,
                              const PreprocessorOptions &PPO,
-                             const CodeGenOptions &CGO, llvm::Module &M,
+                             const CodeGenOptions &CGO,
+                             const TargetInfo &CGTI,
+                             llvm::Module &M,
                              DiagnosticsEngine &diags,
                              CoverageSourceInfo *CoverageInfo)
     : Context(C), LangOpts(C.getLangOpts()), FS(FS), HeaderSearchOpts(HSO),
       PreprocessorOpts(PPO), CodeGenOpts(CGO), TheModule(M), Diags(diags),
-      Target(C.getTargetInfo()), ABI(createCXXABI(*this)),
+      Target(CGTI), ABI(createCXXABI(*this)),
       VMContext(M.getContext()), VTables(*this),
       SanitizerMD(new SanitizerMetadata(*this)) {
 
@@ -358,19 +360,19 @@ CodeGenModule::CodeGenModule(ASTContext &C,
   BFloatTy = llvm::Type::getBFloatTy(LLVMContext);
   FloatTy = llvm::Type::getFloatTy(LLVMContext);
   DoubleTy = llvm::Type::getDoubleTy(LLVMContext);
-  PointerWidthInBits = C.getTargetInfo().getPointerWidth(LangAS::Default);
+  PointerWidthInBits = Target.getPointerWidth(LangAS::Default);
   PointerAlignInBytes =
-      C.toCharUnitsFromBits(C.getTargetInfo().getPointerAlign(LangAS::Default))
+      C.toCharUnitsFromBits(Target.getPointerAlign(LangAS::Default))
           .getQuantity();
   SizeSizeInBytes =
-    C.toCharUnitsFromBits(C.getTargetInfo().getMaxPointerWidth()).getQuantity();
+    C.toCharUnitsFromBits(Target.getMaxPointerWidth()).getQuantity();
   IntAlignInBytes =
-    C.toCharUnitsFromBits(C.getTargetInfo().getIntAlign()).getQuantity();
+    C.toCharUnitsFromBits(Target.getIntAlign()).getQuantity();
   CharTy =
-    llvm::IntegerType::get(LLVMContext, C.getTargetInfo().getCharWidth());
-  IntTy = llvm::IntegerType::get(LLVMContext, C.getTargetInfo().getIntWidth());
+    llvm::IntegerType::get(LLVMContext, Target.getCharWidth());
+  IntTy = llvm::IntegerType::get(LLVMContext, Target.getIntWidth());
   IntPtrTy = llvm::IntegerType::get(LLVMContext,
-    C.getTargetInfo().getMaxPointerWidth());
+    Target.getMaxPointerWidth());
   Int8PtrTy = llvm::PointerType::get(LLVMContext,
                                      C.getTargetAddressSpace(LangAS::Default));
   const llvm::DataLayout &DL = M.getDataLayout();

clang/lib/CodeGen/CodeGenModule.h

@@ -636,7 +636,9 @@ class CodeGenModule : public CodeGenTypeCache {
   CodeGenModule(ASTContext &C, IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS,
                 const HeaderSearchOptions &headersearchopts,
                 const PreprocessorOptions &ppopts,
-                const CodeGenOptions &CodeGenOpts, llvm::Module &M,
+                const CodeGenOptions &CodeGenOpts,
+                const TargetInfo &CodeGenTargetInfo,
+                llvm::Module &M,
                 DiagnosticsEngine &Diags,
                 CoverageSourceInfo *CoverageInfo = nullptr);
 

clang/lib/CodeGen/ModuleBuilder.cpp

@@ -149,21 +149,26 @@ namespace {
     }
 
     void Initialize(ASTContext &Context) override {
+      Initialize(Context, Context.getTargetInfo());
+    }
+
+    void Initialize(ASTContext &Context, const TargetInfo &CodeGenTargetInfo) override {
       Ctx = &Context;
 
-      M->setTargetTriple(Ctx->getTargetInfo().getTriple().getTriple());
-      M->setDataLayout(Ctx->getTargetInfo().getDataLayoutString());
-      const auto &SDKVersion = Ctx->getTargetInfo().getSDKVersion();
+      M->setTargetTriple(CodeGenTargetInfo.getTriple().getTriple());
+      M->setDataLayout(CodeGenTargetInfo.getDataLayoutString());
+      const auto &SDKVersion = CodeGenTargetInfo.getSDKVersion();
       if (!SDKVersion.empty())
         M->setSDKVersion(SDKVersion);
-      if (const auto *TVT = Ctx->getTargetInfo().getDarwinTargetVariantTriple())
+      if (const auto *TVT = CodeGenTargetInfo.getDarwinTargetVariantTriple())
         M->setDarwinTargetVariantTriple(TVT->getTriple());
       if (auto TVSDKVersion =
-              Ctx->getTargetInfo().getDarwinTargetVariantSDKVersion())
+          CodeGenTargetInfo.getDarwinTargetVariantSDKVersion())
         M->setDarwinTargetVariantSDKVersion(*TVSDKVersion);
       Builder.reset(new CodeGen::CodeGenModule(Context, FS, HeaderSearchOpts,
                                                PreprocessorOpts, CodeGenOpts,
-                                               *M, Diags, CoverageInfo));
+                                               CodeGenTargetInfo, *M,
+                                               Diags, CoverageInfo));
 
       for (auto &&Lib : CodeGenOpts.DependentLibraries)
         Builder->AddDependentLib(Lib);

clang/lib/CodeGen/ObjectFilePCHContainerOperations.cpp

@@ -173,14 +173,19 @@ class PCHContainerGenerator : public ASTConsumer {
   ~PCHContainerGenerator() override = default;
 
   void Initialize(ASTContext &Context) override {
+    Initialize(Context, Context.getTargetInfo());
+  }
+
+  void Initialize(ASTContext &Context, const TargetInfo &CodeGenTargetInfo) override {
     assert(!Ctx && "initialized multiple times");
 
     Ctx = &Context;
     VMContext.reset(new llvm::LLVMContext());
     M.reset(new llvm::Module(MainFileName, *VMContext));
     M->setDataLayout(Ctx->getTargetInfo().getDataLayoutString());
     Builder.reset(new CodeGen::CodeGenModule(
-        *Ctx, FS, HeaderSearchOpts, PreprocessorOpts, CodeGenOpts, *M, Diags));
+        *Ctx, FS, HeaderSearchOpts, PreprocessorOpts, CodeGenOpts,
+        CodeGenTargetInfo, *M, Diags));
 
     // Prepare CGDebugInfo to emit debug info for a clang module.
     auto *DI = Builder->getModuleDebugInfo();