ldc/gen/module.cpp

//===-- module.cpp --------------------------------------------------------===//
//
//                         LDC – the LLVM D compiler
//
// This file is distributed under the BSD-style LDC license. See the LICENSE
// file for details.
//
//===----------------------------------------------------------------------===//

#include "aggregate.h"
#include "attrib.h"
#include "declaration.h"
#include "enum.h"
#include "id.h"
#include "import.h"
#include "init.h"
#include "mars.h"
#include "module.h"
#include "mtype.h"
#include "scope.h"
#include "statement.h"
#include "target.h"
#include "template.h"
#include "gen/abi.h"
#include "gen/arrays.h"
#include "gen/classes.h"
#include "gen/functions.h"
#include "gen/irstate.h"
#include "gen/llvm.h"
#include "gen/llvmhelpers.h"
#include "gen/logger.h"
#include "gen/objcgen.h"
#include "gen/optimizer.h"
#include "gen/programs.h"
#include "gen/rttibuilder.h"
#include "gen/runtime.h"
#include "gen/structs.h"
#include "gen/tollvm.h"
#include "ir/irdsymbol.h"
#include "ir/irfunction.h"
#include "ir/irmodule.h"
#include "ir/irtype.h"
#include "ir/irvar.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/IR/Verifier.h"
#include "llvm/LinkAllPasses.h"
#include "llvm/Transforms/Utils/ModuleUtils.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/DataLayout.h"

#if _AIX || __sun
#include <alloca.h>
#endif

static llvm::cl::opt<bool>
    preservePaths("op", llvm::cl::desc("Do not strip paths from source file"),
                  llvm::cl::ZeroOrMore);

static llvm::cl::opt<bool>
    fqnNames("oq",
             llvm::cl::desc("Write object files with fully qualified names"),
             llvm::cl::ZeroOrMore);

static void check_and_add_output_file(Module *NewMod, const std::string &str) {
  static std::map<std::string, Module *> files;

  auto i = files.find(str);
  if (i != files.end()) {
    Module *ThisMod = i->second;
    error(Loc(), "Output file '%s' for module '%s' collides with previous "
                 "module '%s'. See the -oq option",
          str.c_str(), NewMod->toPrettyChars(), ThisMod->toPrettyChars());
    fatal();
  }
  files.insert(std::make_pair(str, NewMod));
}

void buildTargetFiles(Module *m, bool singleObj, bool library) {
  if (m->objfile && (!m->doDocComment || m->docfile) && (!m->doHdrGen || m->hdrfile)) {
    return;
  }

  if (!m->objfile) {
    const char *objname = library ? nullptr : global.params.objname;
    if (global.params.output_o) {
      m->objfile = m->buildFilePath(objname, global.params.objdir,
                                      global.params.targetTriple->isOSWindows()
                                          ? global.obj_ext_alt
                                          : global.obj_ext, library, fqnNames);
    } else if (global.params.output_bc) {
      m->objfile =
          m->buildFilePath(objname, global.params.objdir, global.bc_ext, library, fqnNames);
    } else if (global.params.output_ll) {
      m->objfile =
          m->buildFilePath(objname, global.params.objdir, global.ll_ext, library, fqnNames);
    } else if (global.params.output_s) {
      m->objfile =
          m->buildFilePath(objname, global.params.objdir, global.s_ext, library, fqnNames);
    }
  }
  if (m->doDocComment && !m->docfile) {
    m->docfile = m->buildFilePath(global.params.docname, global.params.docdir,
                                    global.doc_ext, library, fqnNames);
  }
  if (m->doHdrGen && !m->hdrfile) {
    m->hdrfile = m->buildFilePath(global.params.hdrname, global.params.hdrdir,
                                    global.hdr_ext, library, fqnNames);
  }

  // safety check: never allow obj, doc or hdr file to have the source file's
  // name
  if (Port::stricmp(FileName::name(m->objfile->name->str),
                    FileName::name(m->arg)) == 0) {
    m->error("Output object files with the same name as the source file are "
          "forbidden");
    fatal();
  }
  if (m->docfile &&
      Port::stricmp(FileName::name(m->docfile->name->str),
                    FileName::name(m->arg)) == 0) {
    m->error(
        "Output doc files with the same name as the source file are forbidden");
    fatal();
  }
  if (m->hdrfile &&
      Port::stricmp(FileName::name(m->hdrfile->name->str),
                    FileName::name(m->arg)) == 0) {
    m->error("Output header files with the same name as the source file are "
          "forbidden");
    fatal();
  }

  // LDC
  // another safety check to make sure we don't overwrite previous output files
  if (!singleObj && global.params.obj) {
    check_and_add_output_file(m, m->objfile->name->str);
  }
  if (m->docfile) {
    check_and_add_output_file(m, m->docfile->name->str);
  }
  // FIXME: DMD overwrites header files. This should be done only in a DMD mode.
  // if (hdrfile)
  //    check_and_add_output_file(m, hdrfile->name->str);
}

static llvm::Function *build_module_function(
    const std::string &name, const std::list<FuncDeclaration *> &funcs,
    const std::list<VarDeclaration *> &gates = std::list<VarDeclaration *>()) {
  if (gates.empty()) {
    if (funcs.empty()) {
      return nullptr;
    }

    if (funcs.size() == 1) {
      return getIrFunc(funcs.front())->func;
    }
  }

  // build ctor type
  LLFunctionType *fnTy = LLFunctionType::get(LLType::getVoidTy(gIR->context()),
                                             std::vector<LLType *>(), false);

  std::string const symbolName = gABI->mangleForLLVM(name, LINKd);
  assert(gIR->module.getFunction(symbolName) == NULL);
  llvm::Function *fn = llvm::Function::Create(
      fnTy, llvm::GlobalValue::InternalLinkage, symbolName, &gIR->module);
  fn->setCallingConv(gABI->callingConv(fn->getFunctionType(), LINKd));

  llvm::BasicBlock *bb = llvm::BasicBlock::Create(gIR->context(), "", fn);
  IRBuilder<> builder(bb);

  // debug info
  ldc::DISubprogram dis = gIR->DBuilder.EmitModuleCTor(fn, name.c_str());
  if (global.params.symdebug) {
    // Need _some_ debug info to avoid inliner bug, see GitHub issue #998.
    builder.SetCurrentDebugLocation(llvm::DebugLoc::get(0, 0, dis));
  }

  // Call ctor's
  for (auto func : funcs) {
    llvm::Function *f = getIrFunc(func)->func;
#if LDC_LLVM_VER >= 307
    llvm::CallInst *call = builder.CreateCall(f, {});
#else
    llvm::CallInst *call = builder.CreateCall(f, "");
#endif
    call->setCallingConv(gABI->callingConv(call->
#if LDC_LLVM_VER < 307
                                           getCalledFunction()
                                               ->
#endif
                                           getFunctionType(),
                                           LINKd));
  }

  // Increment vgate's
  for (auto gate : gates) {
    assert(getIrGlobal(gate));
    llvm::Value *val = getIrGlobal(gate)->value;
    llvm::Value *rval = builder.CreateLoad(val, "vgate");
    llvm::Value *res = builder.CreateAdd(rval, DtoConstUint(1), "vgate");
    builder.CreateStore(res, val);
  }

  builder.CreateRetVoid();
  return fn;
}

// build module ctor

static llvm::Function *build_module_ctor(Module *m) {
  std::string name("_D");
  name.append(mangle(m));
  name.append("6__ctorZ");
  IrModule *irm = getIrModule(m);
  return build_module_function(name, irm->ctors, irm->gates);
}

// build module dtor

static llvm::Function *build_module_dtor(Module *m) {
  std::string name("_D");
  name.append(mangle(m));
  name.append("6__dtorZ");
  return build_module_function(name, getIrModule(m)->dtors);
}

// build module unittest

static llvm::Function *build_module_unittest(Module *m) {
  std::string name("_D");
  name.append(mangle(m));
  name.append("10__unittestZ");
  return build_module_function(name, getIrModule(m)->unitTests);
}

// build module shared ctor

static llvm::Function *build_module_shared_ctor(Module *m) {
  std::string name("_D");
  name.append(mangle(m));
  name.append("13__shared_ctorZ");
  IrModule *irm = getIrModule(m);
  return build_module_function(name, irm->sharedCtors, irm->sharedGates);
}

// build module shared dtor

static llvm::Function *build_module_shared_dtor(Module *m) {
  std::string name("_D");
  name.append(mangle(m));
  name.append("13__shared_dtorZ");
  return build_module_function(name, getIrModule(m)->sharedDtors);
}

// build ModuleReference and register function, to register the module info in
// the global linked list
static LLFunction *build_module_reference_and_ctor(const char *moduleMangle,
                                                   LLConstant *moduleinfo) {
  // build ctor type
  LLFunctionType *fty = LLFunctionType::get(LLType::getVoidTy(gIR->context()),
                                            std::vector<LLType *>(), false);

  // build ctor name
  std::string fname = "_D";
  fname += moduleMangle;
  fname += "16__moduleinfoCtorZ";

  // build a function that registers the moduleinfo in the global moduleinfo
  // linked list
  LLFunction *ctor = LLFunction::Create(fty, LLGlobalValue::InternalLinkage,
                                        fname, &gIR->module);

  // provide the default initializer
  LLStructType *modulerefTy = DtoModuleReferenceType();
  LLConstant *mrefvalues[] = {
      LLConstant::getNullValue(modulerefTy->getContainedType(0)),
      llvm::ConstantExpr::getBitCast(moduleinfo,
                                     modulerefTy->getContainedType(1))};
  LLConstant *thismrefinit = LLConstantStruct::get(
      modulerefTy, llvm::ArrayRef<LLConstant *>(mrefvalues));

  // create the ModuleReference node for this module
  std::string thismrefname = "_D";
  thismrefname += moduleMangle;
  thismrefname += "11__moduleRefZ";
  Loc loc;
  LLGlobalVariable *thismref = getOrCreateGlobal(
      loc, gIR->module, modulerefTy, false, LLGlobalValue::InternalLinkage,
      thismrefinit, thismrefname);
  // make sure _Dmodule_ref is declared
  LLConstant *mref = gIR->module.getNamedGlobal("_Dmodule_ref");
  LLType *modulerefPtrTy = getPtrToType(modulerefTy);
  if (!mref) {
    mref = new LLGlobalVariable(gIR->module, modulerefPtrTy, false,
                                LLGlobalValue::ExternalLinkage, nullptr,
                                "_Dmodule_ref");
  }
  mref = DtoBitCast(mref, getPtrToType(modulerefPtrTy));

  // make the function insert this moduleinfo as the beginning of the
  // _Dmodule_ref linked list
  llvm::BasicBlock *bb =
      llvm::BasicBlock::Create(gIR->context(), "moduleinfoCtorEntry", ctor);
  IRBuilder<> builder(bb);

  // debug info
  gIR->DBuilder.EmitModuleCTor(ctor, fname.c_str());

  // get current beginning
  LLValue *curbeg = builder.CreateLoad(mref, "current");

  // put current beginning as the next of this one
  LLValue *gep = builder.CreateStructGEP(
#if LDC_LLVM_VER >= 307
      modulerefTy,
#endif
      thismref, 0, "next");
  builder.CreateStore(curbeg, gep);

  // replace beginning
  builder.CreateStore(thismref, mref);

  // return
  builder.CreateRetVoid();

  return ctor;
}

/// Builds the body for the ldc.dso_ctor and ldc.dso_dtor functions.
///
/// Pseudocode:
/// if (dsoInitialized == executeWhenInitialized) {
///     dsoInitialized = !executeWhenInitialized;
///     auto record = {1, dsoSlot, minfoBeg, minfoEnd, minfoUsedPointer};
///     _d_dso_registry(cast(CompilerDSOData*)&record);
/// }
static void build_dso_ctor_dtor_body(
    llvm::Function *targetFunc, llvm::Value *dsoInitialized,
    llvm::Value *dsoSlot, llvm::Value *minfoBeg, llvm::Value *minfoEnd,
    llvm::Value *minfoUsedPointer, bool executeWhenInitialized) {
  llvm::Function *const dsoRegistry =
      getRuntimeFunction(Loc(), gIR->module, "_d_dso_registry");
  llvm::Type *const recordPtrTy =
      dsoRegistry->getFunctionType()->getContainedType(1);

  llvm::BasicBlock *const entryBB =
      llvm::BasicBlock::Create(gIR->context(), "", targetFunc);
  llvm::BasicBlock *const initBB =
      llvm::BasicBlock::Create(gIR->context(), "init", targetFunc);
  llvm::BasicBlock *const endBB =
      llvm::BasicBlock::Create(gIR->context(), "end", targetFunc);

  {
    IRBuilder<> b(entryBB);
    llvm::Value *condEval =
        b.CreateICmp(executeWhenInitialized ? llvm::ICmpInst::ICMP_NE
                                            : llvm::ICmpInst::ICMP_EQ,
                     b.CreateLoad(dsoInitialized), b.getInt8(0));
    b.CreateCondBr(condEval, initBB, endBB);
  }
  {
    IRBuilder<> b(initBB);
    b.CreateStore(b.getInt8(!executeWhenInitialized), dsoInitialized);

    llvm::Constant *version = DtoConstSize_t(1);
    llvm::Type *memberTypes[] = {version->getType(), dsoSlot->getType(),
                                 minfoBeg->getType(), minfoEnd->getType(),
                                 minfoUsedPointer->getType()};
    llvm::StructType *stype =
        llvm::StructType::get(gIR->context(), memberTypes, false);
    llvm::Value *record = b.CreateAlloca(stype);
#if LDC_LLVM_VER >= 307
    b.CreateStore(version, b.CreateStructGEP(stype, record, 0)); // version
    b.CreateStore(dsoSlot, b.CreateStructGEP(stype, record, 1)); // slot
    b.CreateStore(minfoBeg, b.CreateStructGEP(stype, record, 2));
    b.CreateStore(minfoEnd, b.CreateStructGEP(stype, record, 3));
    b.CreateStore(minfoUsedPointer, b.CreateStructGEP(stype, record, 4));
#else
    b.CreateStore(version, b.CreateStructGEP(record, 0)); // version
    b.CreateStore(dsoSlot, b.CreateStructGEP(record, 1)); // slot
    b.CreateStore(minfoBeg, b.CreateStructGEP(record, 2));
    b.CreateStore(minfoEnd, b.CreateStructGEP(record, 3));
    b.CreateStore(minfoUsedPointer, b.CreateStructGEP(record, 4));
#endif

    b.CreateCall(dsoRegistry, b.CreateBitCast(record, recordPtrTy));
    b.CreateBr(endBB);
  }
  {
    IRBuilder<> b(endBB);
    b.CreateRetVoid();
  }
}

static void build_module_ref(std::string moduleMangle,
                             llvm::Constant *thisModuleInfo) {
  // Build the ModuleInfo reference and bracketing symbols.
  llvm::Type *const moduleInfoPtrTy = DtoPtrToType(Module::moduleinfo->type);

  std::string thismrefname = "_D";
  thismrefname += moduleMangle;
  thismrefname += "11__moduleRefZ";
  auto thismref = new llvm::GlobalVariable(
      gIR->module, moduleInfoPtrTy,
      false, // FIXME: mRelocModel != llvm::Reloc::PIC_
      llvm::GlobalValue::LinkOnceODRLinkage,
      DtoBitCast(thisModuleInfo, moduleInfoPtrTy), thismrefname);
  thismref->setSection(".minfo");
  gIR->usedArray.push_back(thismref);
}

static void build_dso_registry_calls(std::string moduleMangle,
                                     llvm::Constant *thisModuleInfo) {
  // Build the ModuleInfo reference and bracketing symbols.
  llvm::Type *const moduleInfoPtrTy = DtoPtrToType(Module::moduleinfo->type);

  // Order is important here: We must create the symbols in the
  // bracketing sections right before/after the ModuleInfo reference
  // so that they end up in the correct order in the object file.
  auto minfoBeg =
      new llvm::GlobalVariable(gIR->module, moduleInfoPtrTy,
                               false, // FIXME: mRelocModel != llvm::Reloc::PIC_
                               llvm::GlobalValue::LinkOnceODRLinkage,
                               getNullPtr(moduleInfoPtrTy), "_minfo_beg");
  minfoBeg->setSection(".minfo_beg");
  minfoBeg->setVisibility(llvm::GlobalValue::HiddenVisibility);

  std::string thismrefname = "_D";
  thismrefname += moduleMangle;
  thismrefname += "11__moduleRefZ";
  auto thismref = new llvm::GlobalVariable(
      gIR->module, moduleInfoPtrTy,
      false, // FIXME: mRelocModel != llvm::Reloc::PIC_
      llvm::GlobalValue::LinkOnceODRLinkage,
      DtoBitCast(thisModuleInfo, moduleInfoPtrTy), thismrefname);
  thismref->setSection(".minfo");
  gIR->usedArray.push_back(thismref);

  auto minfoEnd =
      new llvm::GlobalVariable(gIR->module, moduleInfoPtrTy,
                               false, // FIXME: mRelocModel != llvm::Reloc::PIC_
                               llvm::GlobalValue::LinkOnceODRLinkage,
                               getNullPtr(moduleInfoPtrTy), "_minfo_end");
  minfoEnd->setSection(".minfo_end");
  minfoEnd->setVisibility(llvm::GlobalValue::HiddenVisibility);

  // Build the ctor to invoke _d_dso_registry.

  // This is the DSO slot for use by the druntime implementation.
  auto dsoSlot =
      new llvm::GlobalVariable(gIR->module, getVoidPtrType(), false,
                               llvm::GlobalValue::LinkOnceODRLinkage,
                               getNullPtr(getVoidPtrType()), "ldc.dso_slot");
  dsoSlot->setVisibility(llvm::GlobalValue::HiddenVisibility);

  // Okay, so the theory is easy: We want to have one global constructor and
  // destructor per object (i.e. executable/shared library) that calls
  // _d_dso_registry with the respective DSO record. However, there are a
  // couple of issues that make this harder than necessary:
  //
  //  1) The natural way to implement the "one-per-image" part would be to
  //     emit a weak reference to a weak function into a .ctors.<somename>
  //     section (llvm.global_ctors doesn't support the necessary
  //     functionality, so we'd use our knowledge of the linker script to work
  //     around that). But as of LLVM 3.4, emitting a symbol both as weak and
  //     into a custom section is not supported by the MC layer. Thus, we have
  //     to use a normal ctor/dtor and manually ensure that we only perform
  //     the call once. This is done by introducing ldc.dso_initialized.
  //
  //  2) To make sure the .minfo section isn't removed by the linker when
  //     using --gc-sections, we need to keep a reference to it around in
  //     _every_ object file (as --gc-sections works per object file). The
  //     natural place for this is the ctor, where we just load a reference
  //     on the stack after the DSO record (to ensure LLVM doesn't optimize
  //     it out). However, this way, we need to have at least one ctor
  //     instance per object file be pulled into the final executable. We
  //     do this here by making the module mangle string part of its name,
  //     even thoguht this is slightly wasteful on -singleobj builds.
  //
  // It might be a better idea to simply use a custom linker script (using
  // INSERT AFTER… so as to still keep the default one) to avoid all these
  // problems. This would mean that it is no longer safe to link D objects
  // directly using e.g. "g++ dcode.o cppcode.o", though.

  auto dsoInitialized = new llvm::GlobalVariable(
      gIR->module, llvm::Type::getInt8Ty(gIR->context()), false,
      llvm::GlobalValue::LinkOnceODRLinkage,
      llvm::ConstantInt::get(llvm::Type::getInt8Ty(gIR->context()), 0),
      "ldc.dso_initialized");
  dsoInitialized->setVisibility(llvm::GlobalValue::HiddenVisibility);

  // There is no reason for this cast to void*, other than that removing it
  // seems to trigger a bug in the llvm::Linker (at least on LLVM 3.4)
  // causing it to not merge the %object.ModuleInfo types properly. This
  // manifests itself in a type mismatch assertion being triggered on the
  // minfoUsedPointer store in the ctor as soon as the optimizer runs.
  llvm::Value *minfoRefPtr = DtoBitCast(thismref, getVoidPtrType());

  std::string ctorName = "ldc.dso_ctor.";
  ctorName += moduleMangle;
  llvm::Function *dsoCtor = llvm::Function::Create(
      llvm::FunctionType::get(llvm::Type::getVoidTy(gIR->context()), false),
      llvm::GlobalValue::LinkOnceODRLinkage, ctorName, &gIR->module);
  dsoCtor->setVisibility(llvm::GlobalValue::HiddenVisibility);
  build_dso_ctor_dtor_body(dsoCtor, dsoInitialized, dsoSlot, minfoBeg, minfoEnd,
                           minfoRefPtr, false);
  llvm::appendToGlobalCtors(gIR->module, dsoCtor, 65535);

  std::string dtorName = "ldc.dso_dtor.";
  dtorName += moduleMangle;
  llvm::Function *dsoDtor = llvm::Function::Create(
      llvm::FunctionType::get(llvm::Type::getVoidTy(gIR->context()), false),
      llvm::GlobalValue::LinkOnceODRLinkage, dtorName, &gIR->module);
  dsoDtor->setVisibility(llvm::GlobalValue::HiddenVisibility);
  build_dso_ctor_dtor_body(dsoDtor, dsoInitialized, dsoSlot, minfoBeg, minfoEnd,
                           minfoRefPtr, true);
  llvm::appendToGlobalDtors(gIR->module, dsoDtor, 65535);
}

static void build_llvm_used_array(IRState *p) {
  if (p->usedArray.empty()) {
    return;
  }

  std::vector<llvm::Constant *> usedVoidPtrs;
  usedVoidPtrs.reserve(p->usedArray.size());

  for (auto constant : p->usedArray) {
    usedVoidPtrs.push_back(DtoBitCast(constant, getVoidPtrType()));
  }

  llvm::ArrayType *arrayType =
      llvm::ArrayType::get(getVoidPtrType(), usedVoidPtrs.size());
  auto llvmUsed = new llvm::GlobalVariable(
      p->module, arrayType, false, llvm::GlobalValue::AppendingLinkage,
      llvm::ConstantArray::get(arrayType, usedVoidPtrs), "llvm.used");
  llvmUsed->setSection("llvm.metadata");
}

// Add module-private variables and functions for coverage analysis.
static void addCoverageAnalysis(Module *m) {
  IF_LOG {
    Logger::println("Adding coverage analysis for module %s (%d lines)",
                    m->srcfile->toChars(), m->numlines);
    Logger::indent();
  }

  // size_t[# source lines / # bits in sizeTy] _d_cover_valid
  LLValue *d_cover_valid_slice = nullptr;
  {
    unsigned Dsizet_bits = gDataLayout->getTypeSizeInBits(DtoSize_t());
    size_t array_size = (m->numlines + (Dsizet_bits - 1)) / Dsizet_bits; // ceil

    // Work around a bug in the interface of druntime's _d_cover_register2
    // https://issues.dlang.org/show_bug.cgi?id=14417
    // For safety, make the array large enough such that the slice passed to
    // _d_cover_register2 is completely valid.
    array_size = m->numlines;

    IF_LOG Logger::println(
        "Build private variable: size_t[%llu] _d_cover_valid",
        static_cast<unsigned long long>(array_size));

    llvm::ArrayType *type = llvm::ArrayType::get(DtoSize_t(), array_size);
    llvm::ConstantAggregateZero *zeroinitializer =
        llvm::ConstantAggregateZero::get(type);
    m->d_cover_valid = new llvm::GlobalVariable(
        gIR->module, type, true, LLGlobalValue::InternalLinkage,
        zeroinitializer, "_d_cover_valid");
    LLConstant *idxs[] = {DtoConstUint(0), DtoConstUint(0)};
    d_cover_valid_slice =
        DtoConstSlice(DtoConstSize_t(type->getArrayNumElements()),
                      llvm::ConstantExpr::getGetElementPtr(
#if LDC_LLVM_VER >= 307
                          type,
#endif
                          m->d_cover_valid, idxs, true));

    // Assert that initializer array elements have enough bits
    assert(sizeof(m->d_cover_valid_init[0]) * 8 >=
           gDataLayout->getTypeSizeInBits(DtoSize_t()));
    m->d_cover_valid_init.setDim(array_size);
    m->d_cover_valid_init.zero();
  }

  // uint[# source lines] _d_cover_data
  LLValue *d_cover_data_slice = nullptr;
  {
    IF_LOG Logger::println("Build private variable: uint[%d] _d_cover_data",
                           m->numlines);

    LLArrayType *type =
        LLArrayType::get(LLType::getInt32Ty(gIR->context()), m->numlines);
    llvm::ConstantAggregateZero *zeroinitializer =
        llvm::ConstantAggregateZero::get(type);
    m->d_cover_data = new llvm::GlobalVariable(
        gIR->module, type, false, LLGlobalValue::InternalLinkage,
        zeroinitializer, "_d_cover_data");
    LLConstant *idxs[] = {DtoConstUint(0), DtoConstUint(0)};
    d_cover_data_slice =
        DtoConstSlice(DtoConstSize_t(type->getArrayNumElements()),
                      llvm::ConstantExpr::getGetElementPtr(
#if LDC_LLVM_VER >= 307
                          type,
#endif
                          m->d_cover_data, idxs, true));
  }

  // Create "static constructor" that calls _d_cover_register2(string filename,
  // size_t[] valid, uint[] data, ubyte minPercent)
  // Build ctor name
  LLFunction *ctor = nullptr;
  std::string ctorname = "_D";
  ctorname += mangle(m);
  ctorname += "12_coverageanalysisCtor1FZv";
  {
    IF_LOG Logger::println("Build Coverage Analysis constructor: %s",
                           ctorname.c_str());

    LLFunctionType *ctorTy = LLFunctionType::get(
        LLType::getVoidTy(gIR->context()), std::vector<LLType *>(), false);
    ctor = LLFunction::Create(ctorTy, LLGlobalValue::InternalLinkage, ctorname,
                              &gIR->module);
    ctor->setCallingConv(gABI->callingConv(ctor->getFunctionType(), LINKd));
    // Set function attributes. See functions.cpp:DtoDefineFunction()
    if (global.params.targetTriple->getArch() == llvm::Triple::x86_64) {
      ctor->addFnAttr(LLAttribute::UWTable);
    }

    llvm::BasicBlock *bb = llvm::BasicBlock::Create(gIR->context(), "", ctor);
    IRBuilder<> builder(bb);

    // Set up call to _d_cover_register2
    llvm::Function *fn =
        getRuntimeFunction(Loc(), gIR->module, "_d_cover_register2");
    LLValue *args[] = {DtoConstString(m->srcfile->name->toChars()),
                       d_cover_valid_slice, d_cover_data_slice,
                       DtoConstUbyte(global.params.covPercent)};
    // Check if argument types are correct
    for (unsigned i = 0; i < 4; ++i) {
      assert(args[i]->getType() == fn->getFunctionType()->getParamType(i));
    }

    builder.CreateCall(fn, args);

    builder.CreateRetVoid();
  }

  // Add the ctor to the module's static ctors list. TODO: This is quite the
  // hack.
  {
    IF_LOG Logger::println("Add %s to module's shared static constructor list",
                           ctorname.c_str());
    FuncDeclaration *fd =
        FuncDeclaration::genCfunc(nullptr, Type::tvoid, ctorname.c_str());
    fd->linkage = LINKd;
    IrFunction *irfunc = getIrFunc(fd, true);
    irfunc->func = ctor;
    getIrModule(m)->sharedCtors.push_back(fd);
  }

  IF_LOG Logger::undent();
}

// Initialize _d_cover_valid for coverage analysis
static void addCoverageAnalysisInitializer(Module *m) {
  IF_LOG Logger::println("Adding coverage analysis _d_cover_valid initializer");

  size_t array_size = m->d_cover_valid_init.size();

  llvm::ArrayType *type = llvm::ArrayType::get(DtoSize_t(), array_size);
  std::vector<LLConstant *> arrayInits(array_size);
  for (size_t i = 0; i < array_size; i++) {
    arrayInits[i] = DtoConstSize_t(m->d_cover_valid_init[i]);
  }
  m->d_cover_valid->setInitializer(llvm::ConstantArray::get(type, arrayInits));
}

static void genModuleInfo(Module *m, bool emitFullModuleInfo);

void codegenModule(IRState *irs, Module *m, bool emitFullModuleInfo) {
  assert(!irs->dmodule &&
         "irs->module not null, codegen already in progress?!");
  irs->dmodule = m;
  assert(!gIR && "gIR not null, codegen already in progress?!");
  gIR = irs;

  initRuntime();

  // Skip pseudo-modules for coverage analysis
  std::string name = m->toChars();
  if (global.params.cov && name != "__entrypoint" && name != "__main") {
    addCoverageAnalysis(m);
  }

  // process module members
  for (unsigned k = 0; k < m->members->dim; k++) {
    Dsymbol *dsym = (*m->members)[k];
    assert(dsym);
    Declaration_codegen(dsym);
  }

  if (global.errors) {
    fatal();
  }

  // Skip emission of all the additional module metadata if requested by the
  // user.
  if (!m->noModuleInfo) {
    // generate ModuleInfo
    genModuleInfo(m, emitFullModuleInfo);

    build_llvm_used_array(irs);
  }

  if (m->d_cover_valid) {
    addCoverageAnalysisInitializer(m);
  }

  gIR = nullptr;
  irs->dmodule = nullptr;
}

// Put out instance of ModuleInfo for this Module
static void genModuleInfo(Module *m, bool emitFullModuleInfo) {
  // resolve ModuleInfo
  if (!Module::moduleinfo) {
    m->error("object.d is missing the ModuleInfo struct");
    fatal();
  }
  // check for patch
  else {
    // The base struct should consist only of _flags/_index.
    if (Module::moduleinfo->structsize != 4 + 4) {
      m->error("Unexpected size of struct object.ModuleInfo; "
               "druntime version does not match compiler (see -v)");
      fatal();
    }
  }

  // use the RTTIBuilder
  RTTIBuilder b(Module::moduleinfo);

  // some types
  llvm::Type *const moduleInfoPtrTy = DtoPtrToType(Module::moduleinfo->type);
  LLType *classinfoTy = Type::typeinfoclass->type->ctype->getLLType();

  // importedModules[]
  std::vector<LLConstant *> importInits;
  LLConstant *importedModules = nullptr;
  llvm::ArrayType *importedModulesTy = nullptr;
  for (size_t i = 0; i < m->aimports.dim; i++) {
    Module *mod = static_cast<Module *>(m->aimports.data[i]);
    if (!mod->needModuleInfo() || mod == m) {
      continue;
    }

    importInits.push_back(
        DtoBitCast(getIrModule(mod)->moduleInfoSymbol(), moduleInfoPtrTy));
  }
  // has import array?
  if (!importInits.empty()) {
    importedModulesTy =
        llvm::ArrayType::get(moduleInfoPtrTy, importInits.size());
    importedModules = LLConstantArray::get(importedModulesTy, importInits);
  }

  // localClasses[]
  LLConstant *localClasses = nullptr;
  llvm::ArrayType *localClassesTy = nullptr;
  ClassDeclarations aclasses;
  // printf("members->dim = %d\n", members->dim);
  for (size_t i = 0; i < m->members->dim; i++) {
    (*m->members)[i]->addLocalClass(&aclasses);
  }
  // fill inits
  std::vector<LLConstant *> classInits;
  for (size_t i = 0; i < aclasses.dim; i++) {
    ClassDeclaration *cd = aclasses[i];
    DtoResolveClass(cd);

    if (cd->isInterfaceDeclaration()) {
      IF_LOG Logger::println("skipping interface '%s' in moduleinfo",
                             cd->toPrettyChars());
      continue;
    } else if (cd->sizeok != SIZEOKdone) {
      IF_LOG Logger::println(
          "skipping opaque class declaration '%s' in moduleinfo",
          cd->toPrettyChars());
      continue;
    }
    IF_LOG Logger::println("class: %s", cd->toPrettyChars());
    LLConstant *c =
        DtoBitCast(getIrAggr(cd)->getClassInfoSymbol(), classinfoTy);
    classInits.push_back(c);
  }
  // has class array?
  if (!classInits.empty()) {
    localClassesTy = llvm::ArrayType::get(classinfoTy, classInits.size());
    localClasses = LLConstantArray::get(localClassesTy, classInits);
  }

// These must match the values in druntime/src/object_.d
#define MIstandalone 4
#define MItlsctor 8
#define MItlsdtor 0x10
#define MIctor 0x20
#define MIdtor 0x40
#define MIxgetMembers 0x80
#define MIictor 0x100
#define MIunitTest 0x200
#define MIimportedModules 0x400
#define MIlocalClasses 0x800
#define MInew 0x80000000 // it's the "new" layout

  llvm::Function *fsharedctor = build_module_shared_ctor(m);
  llvm::Function *fshareddtor = build_module_shared_dtor(m);
  llvm::Function *funittest = build_module_unittest(m);
  llvm::Function *fctor = build_module_ctor(m);
  llvm::Function *fdtor = build_module_dtor(m);

  unsigned flags = MInew;
  if (fctor) {
    flags |= MItlsctor;
  }
  if (fdtor) {
    flags |= MItlsdtor;
  }
  if (fsharedctor) {
    flags |= MIctor;
  }
  if (fshareddtor) {
    flags |= MIdtor;
  }
#if 0
    if (fgetmembers)
        flags |= MIxgetMembers;
    if (fictor)
        flags |= MIictor;
#endif
  if (funittest) {
    flags |= MIunitTest;
  }
  if (importedModules) {
    flags |= MIimportedModules;
  }
  if (localClasses) {
    flags |= MIlocalClasses;
  }

  if (!m->needmoduleinfo) {
    flags |= MIstandalone;
  }

  b.push_uint(flags); // flags
  b.push_uint(0);     // index

  if (fctor) {
    b.push(fctor);
  }
  if (fdtor) {
    b.push(fdtor);
  }
  if (fsharedctor) {
    b.push(fsharedctor);
  }
  if (fshareddtor) {
    b.push(fshareddtor);
  }
#if 0
    if (fgetmembers)
        b.push(fgetmembers);
    if (fictor)
        b.push(fictor);
#endif
  if (funittest) {
    b.push(funittest);
  }
  if (importedModules) {
    b.push_size(importInits.size());
    b.push(importedModules);
  }
  if (localClasses) {
    b.push_size(classInits.size());
    b.push(localClasses);
  }

  // Put out module name as a 0-terminated string.
  const char *name = m->toPrettyChars();
  const size_t len = strlen(name) + 1;
  llvm::IntegerType *it = llvm::IntegerType::getInt8Ty(gIR->context());
  llvm::ArrayType *at = llvm::ArrayType::get(it, len);
  b.push(toConstantArray(it, at, name, len, false));

  objc_Module_genmoduleinfo_classes();

  // create and set initializer
  LLGlobalVariable *moduleInfoSym = getIrModule(m)->moduleInfoSymbol();
  b.finalize(moduleInfoSym->getType()->getPointerElementType(), moduleInfoSym);
  setLinkage({LLGlobalValue::ExternalLinkage, false}, moduleInfoSym);

  if ((global.params.targetTriple.isOSLinux() &&
       global.params.targetTriple.getEnvironment() != llvm::Triple::Android) ||
      global.params.targetTriple.isOSFreeBSD() ||
#if LDC_LLVM_VER > 305
      global.params.targetTriple->isOSNetBSD() || global.params.targetTriple->isOSOpenBSD() ||
      global.params.targetTriple->isOSDragonFly()
#else
      global.params.targetTriple->getOS() == llvm::Triple::NetBSD ||
      global.params.targetTriple->getOS() == llvm::Triple::OpenBSD ||
      global.params.targetTriple->getOS() == llvm::Triple::DragonFly
#endif
          ) {
    if (emitFullModuleInfo) {
      build_dso_registry_calls(mangle(m), moduleInfoSym);
    } else {
      build_module_ref(mangle(m), moduleInfoSym);
    }
  } else {
    // build the modulereference and ctor for registering it
    LLFunction *mictor =
        build_module_reference_and_ctor(mangle(m), moduleInfoSym);
    AppendFunctionToLLVMGlobalCtorsDtors(mictor, 65535, true);
  }
}