llvm/lib/ABI/IRTypeMapper.cpp

//===---- IRTypeMapper.cpp - Maps LLVM ABI Types to LLVM IR Types -------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include "llvm/ABI/IRTypeMapper.h"
#include "llvm/ABI/Types.h"
#include "llvm/ADT/APFloat.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Type.h"
#include "llvm/Support/MathExtras.h"

using namespace llvm::abi;

llvm::Type *IRTypeMapper::convertType(const abi::Type *ABIType) {
  assert(ABIType && "convertType requires a non-null ABI type");

  auto It = TypeCache.find(ABIType);
  if (It != TypeCache.end())
    return It->second;

  llvm::Type *Result = nullptr;

  switch (ABIType->getKind()) {
  case abi::TypeKind::Void:
    Result = llvm::Type::getVoidTy(Context);
    break;
  case abi::TypeKind::Integer: {
    const auto *IT = cast<abi::IntegerType>(ABIType);
    Result =
        llvm::IntegerType::get(Context, IT->getSizeInBits().getFixedValue());
    break;
  }
  case abi::TypeKind::Float: {
    const llvm::fltSemantics *Semantics =
        cast<abi::FloatType>(ABIType)->getSemantics();
    Result = llvm::Type::getFloatingPointTy(Context, *Semantics);
    break;
  }
  case abi::TypeKind::Pointer:
    Result = llvm::PointerType::get(
        Context, cast<abi::PointerType>(ABIType)->getAddrSpace());
    break;
  case abi::TypeKind::Array:
    Result = convertArrayType(cast<abi::ArrayType>(ABIType));
    break;
  case abi::TypeKind::Vector:
    Result = convertVectorType(cast<abi::VectorType>(ABIType));
    break;
  case abi::TypeKind::Record:
    Result = convertRecordType(cast<abi::RecordType>(ABIType));
    break;
  case abi::TypeKind::Complex:
    Result = convertComplexType(cast<abi::ComplexType>(ABIType));
    break;
  case abi::TypeKind::MemberPointer:
    Result = convertMemberPointerType(cast<abi::MemberPointerType>(ABIType));
    break;
  }

  TypeCache[ABIType] = Result;
  return Result;
}

llvm::Type *IRTypeMapper::convertArrayType(const abi::ArrayType *AT) {
  llvm::Type *ElementType = convertType(AT->getElementType());
  uint64_t NumElements = AT->getNumElements();
  if (AT->isMatrixType())
    return llvm::VectorType::get(ElementType,
                                 ElementCount::getFixed(NumElements));
  return llvm::ArrayType::get(ElementType, NumElements);
}

llvm::Type *IRTypeMapper::convertVectorType(const abi::VectorType *VT) {
  llvm::Type *ElementType = convertType(VT->getElementType());
  return llvm::VectorType::get(ElementType, VT->getNumElements());
}

llvm::Type *IRTypeMapper::convertRecordType(const abi::RecordType *RT) {
  return createStructFromFields(RT->getFields(), RT->getSizeInBits(),
                                RT->getAlignment(), RT->isUnion());
}

llvm::Type *IRTypeMapper::convertComplexType(const abi::ComplexType *CT) {
  llvm::Type *ElementType = convertType(CT->getElementType());
  llvm::Type *Fields[] = {ElementType, ElementType};
  return llvm::StructType::get(Context, Fields, /*isPacked=*/false);
}

llvm::Type *
IRTypeMapper::convertMemberPointerType(const abi::MemberPointerType *MPT) {
  llvm::Type *IntPtrTy = DL.getIntPtrType(Context);
  if (MPT->isFunctionPointer()) {
    llvm::Type *Fields[] = {IntPtrTy, IntPtrTy};
    return llvm::StructType::get(Context, Fields, /*isPacked=*/false);
  }
  return IntPtrTy;
}

llvm::Type *IRTypeMapper::createPaddingType(uint64_t PaddingBits) {
  if (PaddingBits == 0)
    return nullptr;
  assert(PaddingBits % 8 == 0 &&
         "sub-byte padding cannot be expressed as an llvm::Type");
  return llvm::ArrayType::get(llvm::IntegerType::get(Context, 8),
                              PaddingBits / 8);
}

llvm::StructType *
IRTypeMapper::createStructFromFields(ArrayRef<abi::FieldInfo> Fields,
                                     TypeSize Size, Align Alignment,
                                     bool IsUnion) {
  SmallVector<llvm::Type *, 16> FieldTypes;

  if (IsUnion) {
    llvm::Type *LargestFieldType = nullptr;
    uint64_t LargestFieldSize = 0;
    for (const auto &Field : Fields) {
      llvm::Type *FieldType = convertType(Field.FieldType);
      uint64_t FieldSize = Field.FieldType->getSizeInBits().getFixedValue();
      if (FieldSize > LargestFieldSize) {
        LargestFieldSize = FieldSize;
        LargestFieldType = FieldType;
      }
    }
    if (LargestFieldType) {
      FieldTypes.push_back(LargestFieldType);
      uint64_t UnionSizeBits = Size.getFixedValue();
      if (LargestFieldSize < UnionSizeBits) {
        if (llvm::Type *PaddingType =
                createPaddingType(UnionSizeBits - LargestFieldSize))
          FieldTypes.push_back(PaddingType);
      }
    }
  } else {
    uint64_t CurrentOffset = 0;
    for (const auto &Field : Fields) {
      assert(!Field.IsBitField && "bitfields should not reach IR type mapping");
      llvm::Type *FieldType = convertType(Field.FieldType);
      if (Field.OffsetInBits > CurrentOffset) {
        uint64_t AlignBits = DL.getABITypeAlign(FieldType).value() * 8;
        uint64_t NaturalNextOffset =
            AlignBits ? alignTo(CurrentOffset, AlignBits) : CurrentOffset;
        if (NaturalNextOffset != Field.OffsetInBits) {
          if (llvm::Type *PaddingType =
                  createPaddingType(Field.OffsetInBits - CurrentOffset))
            FieldTypes.push_back(PaddingType);
        }
        CurrentOffset = Field.OffsetInBits;
      }
      FieldTypes.push_back(FieldType);
      CurrentOffset += Field.FieldType->getSizeInBits().getFixedValue();
    }
    uint64_t TotalSizeBits = Size.getFixedValue();
    if (CurrentOffset < TotalSizeBits) {
      if (llvm::Type *PaddingType =
              createPaddingType(TotalSizeBits - CurrentOffset))
        FieldTypes.push_back(PaddingType);
    }
  }

  return StructType::get(Context, FieldTypes, /*isPacked=*/false);
}