//===------- CGObjCMac.cpp - Interface to Apple Objective-C Runtime -------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This provides Objective-C code generation targetting the Apple runtime.
//
//===----------------------------------------------------------------------===//

#include "CGObjCRuntime.h"

#include "CodeGenModule.h"
#include "clang/AST/Decl.h"
#include "clang/Basic/LangOptions.h"

#include "llvm/Support/IRBuilder.h"

using namespace clang;

namespace {
class CGObjCMac : public CodeGen::CGObjCRuntime {
private:
  CodeGen::CodeGenModule &CGM;

  /// UsedGlobals - list of globals to pack into the llvm.used metadata
  /// to prevent them from being clobbered.
  std::vector<llvm::GlobalValue*> UsedGlobals;

  /// EmitImageInfo - Emit the image info marker used to encode some module
  /// level information.
  void EmitImageInfo();

  /// FinishModule - Write out global data structures at the end of
  /// processing a translation unit.
  void FinishModule();

public:
  CGObjCMac(CodeGen::CodeGenModule &cgm);
  virtual llvm::Constant *GenerateConstantString(const char *String, 
                                                 const size_t length);

  virtual llvm::Value *GenerateMessageSend(llvm::IRBuilder<> &Builder,
                                           const llvm::Type *ReturnTy,
                                           llvm::Value *Sender,
                                           llvm::Value *Receiver,
                                           Selector Sel,
                                           llvm::Value** ArgV,
                                           unsigned ArgC);

  virtual llvm::Value *GenerateMessageSendSuper(llvm::IRBuilder<> &Builder,
                                                const llvm::Type *ReturnTy,
                                                llvm::Value *Sender,
                                                const char *SuperClassName,
                                                llvm::Value *Receiver,
                                                Selector Sel,
                                                llvm::Value** ArgV,
                                                unsigned ArgC);

  virtual llvm::Value *LookupClass(llvm::IRBuilder<> &Builder,
                                   llvm::Value *ClassName);

  virtual llvm::Value *GetSelector(llvm::IRBuilder<> &Builder, Selector Sel);
  
  virtual llvm::Function *MethodPreamble(const std::string &ClassName,
                                         const std::string &CategoryName,
                                         const std::string &MethodName,
                                         const llvm::Type *ReturnTy,
                                         const llvm::Type *SelfTy,
                                         const llvm::Type **ArgTy,
                                         unsigned ArgC,
                                         bool isClassMethod,
                                         bool isVarArg);

  virtual void GenerateCategory(const char *ClassName, const char *CategoryName,
           const llvm::SmallVectorImpl<Selector>  &InstanceMethodSels,
           const llvm::SmallVectorImpl<llvm::Constant *>  &InstanceMethodTypes,
           const llvm::SmallVectorImpl<Selector>  &ClassMethodSels,
           const llvm::SmallVectorImpl<llvm::Constant *>  &ClassMethodTypes,
           const llvm::SmallVectorImpl<std::string> &Protocols);

  virtual void GenerateClass(
           const char *ClassName,
           const char *SuperClassName,
           const int instanceSize,
           const llvm::SmallVectorImpl<llvm::Constant *>  &IvarNames,
           const llvm::SmallVectorImpl<llvm::Constant *>  &IvarTypes,
           const llvm::SmallVectorImpl<llvm::Constant *>  &IvarOffsets,
           const llvm::SmallVectorImpl<Selector>  &InstanceMethodSels,
           const llvm::SmallVectorImpl<llvm::Constant *>  &InstanceMethodTypes,
           const llvm::SmallVectorImpl<Selector>  &ClassMethodSels,
           const llvm::SmallVectorImpl<llvm::Constant *>  &ClassMethodTypes,
           const llvm::SmallVectorImpl<std::string> &Protocols);

  virtual llvm::Value *GenerateProtocolRef(llvm::IRBuilder<> &Builder,
                                           const char *ProtocolName);

  virtual void GenerateProtocol(const char *ProtocolName,
      const llvm::SmallVectorImpl<std::string> &Protocols,
      const llvm::SmallVectorImpl<llvm::Constant *>  &InstanceMethodNames,
      const llvm::SmallVectorImpl<llvm::Constant *>  &InstanceMethodTypes,
      const llvm::SmallVectorImpl<llvm::Constant *>  &ClassMethodNames,
      const llvm::SmallVectorImpl<llvm::Constant *>  &ClassMethodTypes);

  virtual llvm::Function *ModuleInitFunction();
};
} // end anonymous namespace
 
CGObjCMac::CGObjCMac(CodeGen::CodeGenModule &cgm) : CGM(cgm) {
  EmitImageInfo();
}

// This has to perform the lookup every time, since posing and related
// techniques can modify the name -> class mapping.
llvm::Value *CGObjCMac::LookupClass(llvm::IRBuilder<> &Builder,                                    
                                    llvm::Value *ClassName) {
  assert(0 && "Cannot lookup classes on Mac runtime.");
  return 0;
}

/// GetSelector - Return the pointer to the unique'd string for this selector.
llvm::Value *CGObjCMac::GetSelector(llvm::IRBuilder<> &Builder, Selector Sel) {
  assert(0 && "Cannot get selector on Mac runtime.");
  return 0;
}

/// Generate an NSConstantString object.
llvm::Constant *CGObjCMac::GenerateConstantString(const char *String, 
                                                  const size_t length) {
  assert(0 && "Cannot generate constant string for Mac runtime.");
  return 0;
}

/// Generates a message send where the super is the receiver.  This is
/// a message send to self with special delivery semantics indicating
/// which class's method should be called.
llvm::Value *CGObjCMac::GenerateMessageSendSuper(llvm::IRBuilder<> &Builder,
                                                 const llvm::Type *ReturnTy,
                                                 llvm::Value *Sender,
                                                 const char *SuperClassName,
                                                 llvm::Value *Receiver,
                                                 Selector Sel,
                                                 llvm::Value** ArgV,
                                                 unsigned ArgC) {
  assert(0 && "Cannot generate message send to super for Mac runtime.");
  return 0;
}

/// Generate code for a message send expression.  
llvm::Value *CGObjCMac::GenerateMessageSend(llvm::IRBuilder<> &Builder,
                                            const llvm::Type *ReturnTy,
                                            llvm::Value *Sender,
                                            llvm::Value *Receiver,
                                            Selector Sel,
                                            llvm::Value** ArgV,
                                            unsigned ArgC) {
  assert(0 && "Cannot generate message send for Mac runtime.");
  return 0;
}

llvm::Value *CGObjCMac::GenerateProtocolRef(llvm::IRBuilder<> &Builder, 
                                            const char *ProtocolName) {
  assert(0 && "Cannot get protocol reference on Mac runtime.");
  return 0;
}

void CGObjCMac::GenerateProtocol(const char *ProtocolName,
    const llvm::SmallVectorImpl<std::string> &Protocols,
    const llvm::SmallVectorImpl<llvm::Constant *>  &InstanceMethodNames,
    const llvm::SmallVectorImpl<llvm::Constant *>  &InstanceMethodTypes,
    const llvm::SmallVectorImpl<llvm::Constant *>  &ClassMethodNames,
    const llvm::SmallVectorImpl<llvm::Constant *>  &ClassMethodTypes) {
  assert(0 && "Cannot generate protocol for Mac runtime.");
}

void CGObjCMac::GenerateCategory(
           const char *ClassName,
           const char *CategoryName,
           const llvm::SmallVectorImpl<Selector>  &InstanceMethodSels,
           const llvm::SmallVectorImpl<llvm::Constant *>  &InstanceMethodTypes,
           const llvm::SmallVectorImpl<Selector>  &ClassMethodSels,
           const llvm::SmallVectorImpl<llvm::Constant *>  &ClassMethodTypes,
           const llvm::SmallVectorImpl<std::string> &Protocols) {
  assert(0 && "Cannot generate category for Mac runtime.");
}

void CGObjCMac::GenerateClass(
           const char *ClassName,
           const char *SuperClassName,
           const int instanceSize,
           const llvm::SmallVectorImpl<llvm::Constant *>  &IvarNames,
           const llvm::SmallVectorImpl<llvm::Constant *>  &IvarTypes,
           const llvm::SmallVectorImpl<llvm::Constant *>  &IvarOffsets,
           const llvm::SmallVectorImpl<Selector>  &InstanceMethodSels,
           const llvm::SmallVectorImpl<llvm::Constant *>  &InstanceMethodTypes,
           const llvm::SmallVectorImpl<Selector>  &ClassMethodSels,
           const llvm::SmallVectorImpl<llvm::Constant *>  &ClassMethodTypes,
           const llvm::SmallVectorImpl<std::string> &Protocols) {
  assert(0 && "Cannot generate class for Mac runtime.");
}

llvm::Function *CGObjCMac::ModuleInitFunction() { 
  // Abuse this interface function as a place to finalize.
  FinishModule();

  return NULL;
}

llvm::Function *CGObjCMac::MethodPreamble(
                                         const std::string &ClassName,
                                         const std::string &CategoryName,
                                         const std::string &MethodName,
                                         const llvm::Type *ReturnTy,
                                         const llvm::Type *SelfTy,
                                         const llvm::Type **ArgTy,
                                         unsigned ArgC,
                                         bool isClassMethod,
                                         bool isVarArg) {
  assert(0 && "Cannot generate method preamble for Mac runtime.");
  return 0;
}

/* *** Private Interface *** */

/// EmitImageInfo - Emit the image info marker used to encode some module
/// level information.
///
/// See: <rdr://4810609&4810587&4810587>
/// struct IMAGE_INFO {
///   unsigned version;
///   unsigned flags;
/// };
enum ImageInfoFlags {
  eImageInfo_FixAndContinue   = (1 << 0), // FIXME: Not sure what this implies
  eImageInfo_GarbageCollected = (1 << 1), 
  eImageInfo_GCOnly           = (1 << 2)  
};

void CGObjCMac::EmitImageInfo() {
  unsigned version = 0; // Version is unused?
  unsigned flags = 0;

  // FIXME: Fix and continue?
  if (CGM.getLangOptions().getGCMode() != LangOptions::NonGC)
    flags |= eImageInfo_GarbageCollected;
  if (CGM.getLangOptions().getGCMode() == LangOptions::GCOnly)
    flags |= eImageInfo_GCOnly;

  fprintf(stderr, "flags: %d (%d)\n", flags, CGM.getLangOptions().getGCMode());

  // Emitted as int[2];
  llvm::Constant *values[2] = {
    llvm::ConstantInt::get(llvm::Type::Int32Ty, version),
    llvm::ConstantInt::get(llvm::Type::Int32Ty, flags)
  };
  llvm::ArrayType *AT = llvm::ArrayType::get(llvm::Type::Int32Ty, 2);  
  llvm::GlobalValue *GV = 
    new llvm::GlobalVariable(AT, true,
                             llvm::GlobalValue::InternalLinkage,
                             llvm::ConstantArray::get(AT, values, 2),
                             "\01L_OBJC_IMAGE_INFO", 
                             &CGM.getModule());

  GV->setSection("__OBJC, __image_info,regular");

  UsedGlobals.push_back(GV);
}

void CGObjCMac::FinishModule() {
  std::vector<llvm::Constant*> Used;
  
  llvm::Type *I8Ptr = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
  for (std::vector<llvm::GlobalValue*>::iterator i = UsedGlobals.begin(), 
         e = UsedGlobals.end(); i != e; ++i) {
    Used.push_back(llvm::ConstantExpr::getBitCast(*i, I8Ptr));
  }
  
  llvm::ArrayType *AT = llvm::ArrayType::get(I8Ptr, Used.size());
  llvm::GlobalValue *GV = 
    new llvm::GlobalVariable(AT, false,
                             llvm::GlobalValue::AppendingLinkage,
                             llvm::ConstantArray::get(AT, Used),
                             "llvm.used", 
                             &CGM.getModule());

  GV->setSection("llvm.metadata");
}

/* *** */

CodeGen::CGObjCRuntime *CodeGen::CreateMacObjCRuntime(CodeGen::CodeGenModule &CGM){
  return new CGObjCMac(CGM);
}