path: root/lib/CodeGen/CGBlocks.cpp

//===--- CGBlocks.cpp - Emit LLVM Code for declarations -------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This contains code to emit blocks.
//
//===----------------------------------------------------------------------===//

#include "CodeGenFunction.h"
#include "CodeGenModule.h"
#include "clang/AST/DeclObjC.h"
#include "llvm/Module.h"
#include "llvm/Target/TargetData.h"
#include <algorithm>
using namespace clang;
using namespace CodeGen;

llvm::Constant *CodeGenFunction::
BuildDescriptorBlockDecl(bool BlockHasCopyDispose, uint64_t Size,
                         const llvm::StructType* Ty,
                         std::vector<HelperInfo> *NoteForHelper) {
  const llvm::Type *UnsignedLongTy
    = CGM.getTypes().ConvertType(getContext().UnsignedLongTy);
  llvm::Constant *C;
  std::vector<llvm::Constant*> Elts;

  // reserved
  C = llvm::ConstantInt::get(UnsignedLongTy, 0);
  Elts.push_back(C);

  // Size
  // FIXME: What is the right way to say this doesn't fit?  We should give
  // a user diagnostic in that case.  Better fix would be to change the
  // API to size_t.
  C = llvm::ConstantInt::get(UnsignedLongTy, Size);
  Elts.push_back(C);

  if (BlockHasCopyDispose) {
    // copy_func_helper_decl
    Elts.push_back(BuildCopyHelper(Ty, NoteForHelper));

    // destroy_func_decl
    Elts.push_back(BuildDestroyHelper(Ty, NoteForHelper));
  }

  C = llvm::ConstantStruct::get(Elts);

  C = new llvm::GlobalVariable(C->getType(), true,
                               llvm::GlobalValue::InternalLinkage,
                               C, "__block_descriptor_tmp", &CGM.getModule());
  return C;
}

llvm::Constant *BlockModule::getNSConcreteGlobalBlock() {
  if (NSConcreteGlobalBlock == 0)
    NSConcreteGlobalBlock = CGM.CreateRuntimeVariable(PtrToInt8Ty, 
                                                      "_NSConcreteGlobalBlock");
  return NSConcreteGlobalBlock;
}

llvm::Constant *BlockModule::getNSConcreteStackBlock() {
  if (NSConcreteStackBlock == 0)
    NSConcreteStackBlock = CGM.CreateRuntimeVariable(PtrToInt8Ty, 
                                                     "_NSConcreteStackBlock");
  return NSConcreteStackBlock;
}

static void CollectBlockDeclRefInfo(const Stmt *S,
                                    CodeGenFunction::BlockInfo &Info) {
  for (Stmt::const_child_iterator I = S->child_begin(), E = S->child_end();
       I != E; ++I)
    if (*I)
      CollectBlockDeclRefInfo(*I, Info);

  if (const BlockDeclRefExpr *DE = dyn_cast<BlockDeclRefExpr>(S)) {
    // FIXME: Handle enums.
    if (isa<FunctionDecl>(DE->getDecl()))
      return;

    if (DE->isByRef())
      Info.ByRefDeclRefs.push_back(DE);
    else
      Info.ByCopyDeclRefs.push_back(DE);
  }
}

/// CanBlockBeGlobal - Given a BlockInfo struct, determines if a block can be
/// declared as a global variable instead of on the stack.
static bool CanBlockBeGlobal(const CodeGenFunction::BlockInfo &Info) {
  return Info.ByRefDeclRefs.empty() && Info.ByCopyDeclRefs.empty();
}

// FIXME: Push most into CGM, passing down a few bits, like current function
// name.
llvm::Value *CodeGenFunction::BuildBlockLiteralTmp(const BlockExpr *BE) {

  std::string Name = CurFn->getName();
  CodeGenFunction::BlockInfo Info(0, Name.c_str());
  CollectBlockDeclRefInfo(BE->getBody(), Info);

  // Check if the block can be global.
  // FIXME: This test doesn't work for nested blocks yet.  Longer term, I'd like
  // to just have one code path.  We should move this function into CGM and pass
  // CGF, then we can just check to see if CGF is 0.
  if (0 && CanBlockBeGlobal(Info))
    return CGM.GetAddrOfGlobalBlock(BE, Name.c_str());

  std::vector<llvm::Constant*> Elts(5);
  llvm::Constant *C;
  llvm::Value *V;

  {
    // C = BuildBlockStructInitlist();
    unsigned int flags = BLOCK_HAS_DESCRIPTOR;

    // We run this first so that we set BlockHasCopyDispose from the entire
    // block literal.
    // __invoke
    uint64_t subBlockSize, subBlockAlign;
    llvm::SmallVector<const Expr *,