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

#include "gen/rttibuilder.h"
#include "aggregate.h"
#include "mtype.h"
#include "gen/arrays.h"
#include "gen/functions.h"
#include "gen/irstate.h"
#include "gen/linkage.h"
#include "gen/llvm.h"
#include "gen/llvmhelpers.h"
#include "gen/tollvm.h"
#include "ir/iraggr.h"
#include "ir/irfunction.h"

RTTIBuilder::RTTIBuilder(AggregateDeclaration *base_class) {
  DtoResolveDsymbol(base_class);

  base = base_class;
  basetype = static_cast<TypeClass *>(base->type);

  baseir = getIrAggr(base);
  assert(baseir && "no IrStruct for TypeInfo base class");

  prevFieldEnd = 0;

  if (base->isClassDeclaration()) {
    // just start with adding the vtbl
    push(baseir->getVtblSymbol());
    // and monitor
    push_null_vp();
  }
}

void RTTIBuilder::push(llvm::Constant *C) {
  // We need to explicitly zero any padding bytes as per TDPL §7.1.1 (and
  // also match the struct type lowering code here).
  const uint64_t fieldStart =
#if LDC_LLVM_VER >= 309
    llvm::alignTo
#else
    llvm::RoundUpToAlignment
#endif
    (prevFieldEnd, gDataLayout->getABITypeAlignment(C->getType()));

  const uint64_t paddingBytes = fieldStart - prevFieldEnd;
  if (paddingBytes) {
    llvm::Type *const padding = llvm::ArrayType::get(
        llvm::Type::getInt8Ty(gIR->context()), paddingBytes);
    inits.push_back(llvm::Constant::getNullValue(padding));
  }
  inits.push_back(C);
  prevFieldEnd = fieldStart + gDataLayout->getTypeAllocSize(C->getType());
}

void RTTIBuilder::push_null(Type *T) { push(getNullValue(DtoType(T))); }

void RTTIBuilder::push_null_vp() { push(getNullValue(getVoidPtrType())); }

void RTTIBuilder::push_typeinfo(Type *t) { push(DtoTypeInfoOf(t, true)); }

void RTTIBuilder::push_classinfo(ClassDeclaration *cd) {
  push(getIrAggr(cd)->getClassInfoSymbol());
}

void RTTIBuilder::push_string(const char *str) { push(DtoConstString(str)); }

void RTTIBuilder::push_null_void_array() {
  LLType *T = DtoType(Type::tvoid->arrayOf());
  push(getNullValue(T));
}

void RTTIBuilder::push_void_array(uint64_t dim, llvm::Constant *ptr) {
  push(DtoConstSlice(DtoConstSize_t(dim), DtoBitCast(ptr, getVoidPtrType())));
}

void RTTIBuilder::push_void_array(llvm::Constant *CI, Type *valtype,
                                  Dsymbol *mangle_sym) {
  OutBuffer initname;
  mangleToBuffer(mangle_sym, &initname);
  initname.writestring(".rtti.voidarr.data");

  const LinkageWithCOMDAT lwc(TYPEINFO_LINKAGE_TYPE, supportsCOMDAT());

  auto G = new LLGlobalVariable(gIR->module, CI->getType(), true,
                                lwc.first, CI, initname.peekString());
  setLinkage(lwc, G);
  G->setAlignment(DtoAlignment(valtype));

  push_void_array(getTypeAllocSize(CI->getType()), G);
}

void RTTIBuilder::push_array(llvm::Constant *CI, uint64_t dim, Type *valtype,
                             Dsymbol *mangle_sym) {
  std::string tmpStr(valtype->arrayOf()->toChars());
  tmpStr.erase(remove(tmpStr.begin(), tmpStr.end(), '['), tmpStr.end());
  tmpStr.erase(remove(tmpStr.begin(), tmpStr.end(), ']'), tmpStr.end());
  tmpStr.append("arr");

  OutBuffer initname;
  if (mangle_sym)
    mangleToBuffer(mangle_sym, &initname);
  else
    initname.writestring(".ldc");
  initname.writestring(".rtti.");
  initname.writestring(tmpStr.c_str());
  initname.writestring(".data");

  const LinkageWithCOMDAT lwc(TYPEINFO_LINKAGE_TYPE, supportsCOMDAT());

  auto G = new LLGlobalVariable(gIR->module, CI->getType(), true,
                                lwc.first, CI, initname.peekString());
  setLinkage(lwc, G);
  G->setAlignment(DtoAlignment(valtype));

  push_array(dim, DtoBitCast(G, DtoType(valtype->pointerTo())));
}

void RTTIBuilder::push_array(uint64_t dim, llvm::Constant *ptr) {
  push(DtoConstSlice(DtoConstSize_t(dim), ptr));
}

void RTTIBuilder::push_uint(unsigned u) { push(DtoConstUint(u)); }

void RTTIBuilder::push_size(uint64_t s) { push(DtoConstSize_t(s)); }

void RTTIBuilder::push_size_as_vp(uint64_t s) {
  push(llvm::ConstantExpr::getIntToPtr(DtoConstSize_t(s), getVoidPtrType()));
}

void RTTIBuilder::push_funcptr(FuncDeclaration *fd, Type *castto) {
  if (fd) {
    DtoResolveFunction(fd);
    LLConstant *F = DtoCallee(fd);
    if (castto) {
      F = DtoBitCast(F, DtoType(castto));
    }
    push(F);
  } else if (castto) {
    push_null(castto);
  } else {
    push_null_vp();
  }
}

void RTTIBuilder::finalize(IrGlobal *tid) { finalize(tid->type, tid->value); }

void RTTIBuilder::finalize(LLType *type, LLValue *value) {
  llvm::ArrayRef<LLConstant *> inits = llvm::makeArrayRef(this->inits);
  LLStructType *st = isaStruct(type);
  assert(st);

  // set struct body
  if (st->isOpaque()) {
    const int n = inits.size();
    std::vector<LLType *> types;
    types.reserve(n);
    for (int i = 0; i < n; ++i) {
      types.push_back(inits[i]->getType());
    }
    st->setBody(types);
  }

  // create the inititalizer
  LLConstant *tiInit = LLConstantStruct::get(st, inits);

  // set the initializer
  llvm::GlobalVariable *gvar = llvm::cast<llvm::GlobalVariable>(value);
  gvar->setInitializer(tiInit);
  setLinkage({TYPEINFO_LINKAGE_TYPE, supportsCOMDAT()}, gvar);
}

LLConstant *RTTIBuilder::get_constant(LLStructType *initType) {
  // just return the inititalizer
  return LLConstantStruct::get(initType, inits);
}
