lib/Target/TargetData.cpp

//===-- TargetData.cpp - Data size & alignment routines --------------------==//
//
// This file defines target properties related to datatype size/offset/alignment
// information.  It uses lazy annotations to cache information about how 
// structure types are laid out and used.
//
// This structure should be created once, filled in if the defaults are not
// correct and then passed around by const&.  None of the members functions
// require modification to the object.
//
//===----------------------------------------------------------------------===//

#include "llvm/Target/TargetData.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Constants.h"

// Handle the Pass registration stuff neccesary to use TargetData's.
namespace {
  // Register the default SparcV9 implementation...
  RegisterPass<TargetData> X("targetdata", "Target Data Layout");
}


static inline void getTypeInfo(const Type *Ty, const TargetData *TD,
			       uint64_t &Size, unsigned char &Alignment);

//===----------------------------------------------------------------------===//
// Support for StructLayout Annotation
//===----------------------------------------------------------------------===//

StructLayout::StructLayout(const StructType *ST, const TargetData &TD) 
  : Annotation(TD.getStructLayoutAID()) {
  StructAlignment = 0;
  StructSize = 0;

  // Loop over each of the elements, placing them in memory...
  for (StructType::ElementTypes::const_iterator
	 TI = ST->getElementTypes().begin(), 
	 TE = ST->getElementTypes().end(); TI != TE; ++TI) {
    const Type *Ty = *TI;
    unsigned char A;
    unsigned TyAlign;
    uint64_t TySize;
    getTypeInfo(Ty, &TD, TySize, A);
    TyAlign = A;

    // Add padding if neccesary to make the data element aligned properly...
    if (StructSize % TyAlign != 0)
      StructSize = (StructSize/TyAlign + 1) * TyAlign;   // Add padding...

    // Keep track of maximum alignment constraint
    StructAlignment = std::max(TyAlign, StructAlignment);

    MemberOffsets.push_back(StructSize);
    StructSize += TySize;                 // Consume space for this data item
  }

  // Add padding to the end of the struct so that it could be put in an array
  // and all array elements would be aligned correctly.
  if (StructSize % StructAlignment != 0)
    StructSize = (StructSize/StructAlignment + 1) * StructAlignment;

  if (StructSize == 0) {
    StructSize = 1;           // Empty struct is 1 byte
    StructAlignment = 1;
  }
}

Annotation *TargetData::TypeAnFactory(AnnotationID AID, const Annotable *T,
				      void *D) {
  const TargetData &TD = *(const TargetData*)D;
  assert(AID == TD.AID && "Target data annotation ID mismatch!");
  const Type *Ty = cast<const Type>((const Value *)T);
  assert(isa<StructType>(Ty) && 
	 "Can only create StructLayout annotation on structs!");
  return new StructLayout((const StructType *)Ty, TD);
}

//===----------------------------------------------------------------------===//
//                       TargetData Class Implementation
//===----------------------------------------------------------------------===//

TargetData::TargetData(const std::string &TargetName,
                       bool isLittleEndian, unsigned char SubWordSize,
                       unsigned char IntRegSize, unsigned char PtrSize,
                       unsigned char PtrAl, unsigned char DoubleAl,
                       unsigned char FloatAl, unsigned char LongAl, 
                       unsigned char IntAl, unsigned char ShortAl,
                       unsigned char ByteAl)
  : AID(AnnotationManager::getID("TargetData::" + TargetName)) {
  AnnotationManager::registerAnnotationFactory(AID, TypeAnFactory, this);

  LittleEndian     = isLittleEndian;
  SubWordDataSize  = SubWordSize;
  IntegerRegSize   = IntRegSize;
  PointerSize      = PtrSize;
  PointerAlignment = PtrAl;
  DoubleAlignment  = DoubleAl;
  FloatAlignment   = FloatAl;
  LongAlignment    = LongAl;
  IntAlignment     = IntAl;
  ShortAlignment   = ShortAl;
  ByteAlignment    = ByteAl;
}

TargetData::~TargetData() {
  AnnotationManager::registerAnnotationFactory(AID, 0);   // Deregister factory
}

static inline void getTypeInfo(const Type *Ty, const TargetData *TD,
			       uint64_t &Size, unsigned char &Alignment) {
  assert(Ty->isSized() && "Cannot getTypeInfo() on a type that is unsized!");
  switch (Ty->getPrimitiveID()) {
  case Type::VoidTyID:
  case Type::BoolTyID:
  case Type::UByteTyID:
  case Type::SByteTyID:  Size = 1; Alignment = TD->getByteAlignment(); return;
  case Type::UShortTyID:
  case Type::ShortTyID:  Size = 2; Alignment = TD->getShortAlignment(); return;
  case Type::UIntTyID:
  case Type::IntTyID:    Size = 4; Alignment = TD->getIntAlignment(); return;
  case Type::ULongTyID:
  case Type::LongTyID:   Size = 8; Alignment = TD->getLongAlignment(); return;
  case Type::FloatTyID:  Size = 4; Alignment = TD->getFloatAlignment(); return;
  case Type::DoubleTyID: Size = 8; Alignment = TD->getDoubleAlignment(); return;
  case Type::LabelTyID:
  case Type::PointerTyID:
    Size = TD->getPointerSize(); Alignment = TD->getPointerAlignment();
    return;
  case Type::ArrayTyID: {
    const ArrayType *ATy = (const ArrayType *)Ty;
    getTypeInfo(ATy->getElementType(), TD, Size, Alignment);
    Size *= ATy->getNumElements();
    return;
  }
  case Type::StructTyID: {
    // Get the layout annotation... which is lazily created on demand.
    const StructLayout *Layout = TD->getStructLayout((const StructType*)Ty);
    Size = Layout->StructSize; Alignment = Layout->StructAlignment;
    return;
  }
    
  case Type::TypeTyID:
  default:
    assert(0 && "Bad type for getTypeInfo!!!");
    return;
  }
}

uint64_t TargetData::getTypeSize(const Type *Ty) const {
  uint64_t Size;
  unsigned char Align;
  getTypeInfo(Ty, this, Size, Align);
  return Size;
}

unsigned char TargetData::getTypeAlignment(const Type *Ty) const {
  uint64_t Size;
  unsigned char Align;
  getTypeInfo(Ty, this, Size, Align);
  return Align;
}

uint64_t TargetData::getIndexedOffset(const Type *ptrTy,
				      const std::vector<Value*> &Idx) const {
  const Type *Ty = ptrTy;
  assert(isa<PointerType>(Ty) && "Illegal argument for getIndexedOffset()");
  uint64_t Result = 0;

  for (unsigned CurIDX = 0; CurIDX != Idx.size(); ++CurIDX) {
    if (Idx[CurIDX]->getType() == Type::LongTy) {
      // Update Ty to refer to current element
      Ty = cast<SequentialType>(Ty)->getElementType();

      // Get the array index and the size of each array element.
      // Both must be known constants, or the index shd be 0; else this fails.
      int64_t arrayIdx = cast<ConstantSInt>(Idx[CurIDX])->getValue();
      Result += arrayIdx == 0? 0
                : (uint64_t) (arrayIdx * (int64_t) getTypeSize(Ty)); 

    } else if (const StructType *STy = dyn_cast<const StructType>(Ty)) {
      assert(Idx[CurIDX]->getType() == Type::UByteTy && "Illegal struct idx");
      unsigned FieldNo = cast<ConstantUInt>(Idx[CurIDX])->getValue();

      // Get structure layout information...
      const StructLayout *Layout = getStructLayout(STy);

      // Add in the offset, as calculated by the structure layout info...
      assert(FieldNo < Layout->MemberOffsets.size() &&"FieldNo out of range!");
      Result += Layout->MemberOffsets[FieldNo];

      // Update Ty to refer to current element
      Ty = STy->getElementTypes()[FieldNo];

    } else if (isa<const ArrayType>(Ty)) {
      assert(0 && "Loading from arrays not implemented yet!");
    } else {
      assert(0 && "Indexing type that is not struct or array?");
      return 0;                         // Load directly through ptr
    }
  }

  return Result;
}