Wrap clang module files in a Mach-O, ELF, or COFF container.

This is a necessary prerequisite for debugging with modules.
The .pcm files become containers that hold the serialized AST which allows
us to store debug information in the module file that can be shared by all
object files that were built importing the module.

rdar://problem/19104245

This reapplies r230044 with a fixed configure+make build and updated
dependencies.

llvm-svn: 230067

2 files changed, 152 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CMakeLists.txt b/clang/lib/CodeGen/CMakeLists.txt
index 18f505d8c59..dae14bd3b1c 100644
--- a/clang/lib/CodeGen/CMakeLists.txt
+++ b/clang/lib/CodeGen/CMakeLists.txt
@@ -1,4 +1,5 @@
 set(LLVM_LINK_COMPONENTS
+  ${LLVM_TARGETS_TO_BUILD}
   Analysis
   BitReader
   BitWriter
@@ -63,6 +64,7 @@ add_clang_library(clangCodeGen
   CodeGenAction.cpp
   CodeGenFunction.cpp
   CodeGenModule.cpp
+  CodeGenModuleContainer.cpp
   CodeGenPGO.cpp
   CodeGenTBAA.cpp
   CodeGenTypes.cpp
diff --git a/clang/lib/CodeGen/CodeGenModuleContainer.cpp b/clang/lib/CodeGen/CodeGenModuleContainer.cpp
new file mode 100644
index 00000000000..b1162ccf191
--- /dev/null
+++ b/clang/lib/CodeGen/CodeGenModuleContainer.cpp
@@ -0,0 +1,150 @@
+//===--- CodeGenModuleContainer.cpp - Emit .pcm files ---------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/CodeGen/CodeGenModuleContainer.h"
+#include "CodeGenModule.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/DeclObjC.h"
+#include "clang/AST/Expr.h"
+#include "clang/AST/RecursiveASTVisitor.h"
+#include "clang/Basic/Diagnostic.h"
+#include "clang/Basic/TargetInfo.h"
+#include "clang/CodeGen/BackendUtil.h"
+#include "clang/Frontend/CodeGenOptions.h"
+#include "clang/Serialization/ASTWriter.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Support/TargetRegistry.h"
+#include <memory>
+using namespace clang;
+
+namespace {
+class ModuleContainerGenerator : public CodeGenerator {
+  DiagnosticsEngine &Diags;
+  std::unique_ptr<const llvm::DataLayout> TD;
+  ASTContext *Ctx;
+  const CodeGenOptions CodeGenOpts;
+  const TargetOptions TargetOpts;
+  const LangOptions LangOpts;
+  llvm::LLVMContext VMContext;
+  std::unique_ptr<llvm::Module> M;
+  std::unique_ptr<CodeGen::CodeGenModule> Builder;
+  raw_ostream *OS;
+  SmallVectorImpl<char> *SerializedASTBuffer;
+
+public:
+  ModuleContainerGenerator(DiagnosticsEngine &diags,
+                           const std::string &ModuleName,
+                           const CodeGenOptions &CGO, const TargetOptions &TO,
+                           const LangOptions &LO, raw_ostream *OS,
+                           PCHGenerator *PCHGen)
+      : Diags(diags), CodeGenOpts(CGO), TargetOpts(TO), LangOpts(LO),
+        M(new llvm::Module(ModuleName, VMContext)), OS(OS) {
+    PCHGen->RegisterSerializationFinishedCallback(
+      [&](SmallVectorImpl<char> *Buf){
+        SerializedASTBuffer = Buf;
+      });
+  }
+
+  virtual ~ModuleContainerGenerator() {}
+  llvm::Module *GetModule() override { return M.get(); }
+  llvm::Module *ReleaseModule() override { return M.release(); }
+
+  /// Lifted from ModuleBuilder.
+  const Decl *GetDeclForMangledName(StringRef MangledName) override {
+    GlobalDecl Result;
+    if (!Builder->lookupRepresentativeDecl(MangledName, Result))
+      return nullptr;
+    const Decl *D = Result.getCanonicalDecl().getDecl();
+    if (auto FD = dyn_cast<FunctionDecl>(D)) {
+      if (FD->hasBody(FD))
+        return FD;
+    } else if (auto TD = dyn_cast<TagDecl>(D)) {
+      if (auto Def = TD->getDefinition())
+        return Def;
+    }
+    return D;
+  }
+
+  void Initialize(ASTContext &Context) override {
+    Ctx = &Context;
+    M->setTargetTriple(Ctx->getTargetInfo().getTriple().getTriple());
+    M->setDataLayout(Ctx->getTargetInfo().getTargetDescription());
+    TD.reset(new llvm::DataLayout(Ctx->getTargetInfo().getTargetDescription()));
+    Builder.reset(
+        new CodeGen::CodeGenModule(Context, CodeGenOpts, *M, *TD, Diags));
+  }
+
+  /// Emit a container holding the serialized AST.
+  void HandleTranslationUnit(ASTContext &Ctx) override {
+    if (Diags.hasErrorOccurred()) {
+      if (Builder)
+        Builder->clear();
+      M.reset();
+      return;
+    }
+
+    // Finalize the Builder.
+    if (Builder)
+      Builder->Release();
+
+    // Initialize the backend if we haven't done so already.
+    LLVMInitializeAllTargetInfos();
+    LLVMInitializeAllTargets();
+    LLVMInitializeAllAsmPrinters();
+    LLVMInitializeAllTargetMCs();
+
+    // Ensure the target exists.
+    std::string Error;
+    auto Triple = Ctx.getTargetInfo().getTriple();
+    if (!llvm::TargetRegistry::lookupTarget(Triple.getTriple(), Error))
+      llvm::report_fatal_error(Error);
+
+    // Emit the serialized Clang AST into its own section.
+    auto Size = SerializedASTBuffer->size();
+    auto Int8Ty = llvm::Type::getInt8Ty(VMContext);
+    auto *Ty = llvm::ArrayType::get(Int8Ty, Size);
+    auto *Data = llvm::ConstantDataArray::getString(VMContext,
+        StringRef(SerializedASTBuffer->data(), Size), /*AddNull=*/false);
+    auto *ASTSym = new llvm::GlobalVariable(*M, Ty, /*constant*/ true,
+        llvm::GlobalVariable::InternalLinkage, Data, "__clang_ast");
+    ASTSym->setAlignment(8);
+    if (Triple.isOSBinFormatMachO())
+      // Include Mach-O segment name.
+      ASTSym->setSection("__CLANG,__clangast");
+    else if (Triple.isOSBinFormatCOFF())
+      // Adhere to COFF eight-character limit.
+      ASTSym->setSection("clangast");
+    else
+      ASTSym->setSection("__clangast");
+
+    // Use the LLVM backend to emit the pcm.
+    EmitBackendOutput(Diags, CodeGenOpts, TargetOpts, LangOpts,
+                      Ctx.getTargetInfo().getTargetDescription(), M.get(),
+                      BackendAction::Backend_EmitObj, OS);
+
+    // Make sure the module container hits disk now.
+    OS->flush();
+
+    // Free up some memory, in case the process is kept alive.
+    SerializedASTBuffer->clear();
+  }
+};
+}
+
+CodeGenerator *clang::CreateModuleContainerGenerator(
+    DiagnosticsEngine &Diags, const std::string &ModuleName,
+    const CodeGenOptions &CGO, const TargetOptions &TO, const LangOptions &LO,
+    llvm::raw_ostream *OS, PCHGenerator *PCHGen) {
+  return
+    new ModuleContainerGenerator(Diags, ModuleName, CGO, TO, LO, OS, PCHGen);
+}