Pointer.cpp

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//===--- Pointer.cpp - Types for the constexpr VM ---------------*- C++ -*-===//
//
// 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 "Pointer.h"
#include "Boolean.h"
#include "Context.h"
#include "Floating.h"
#include "Function.h"
#include "Integral.h"
#include "InterpBlock.h"
#include "MemberPointer.h"
#include "PrimType.h"
#include "Record.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/RecordLayout.h"
 
using namespace clang;
using namespace clang::interp;
 
Pointer::Pointer(Block *Pointee)
    : Pointer(Pointee, Pointee->getDescriptor()->getMetadataSize(),
              Pointee->getDescriptor()->getMetadataSize()) {}
 
Pointer::Pointer(Block *Pointee, uint64_t BaseAndOffset)
    : Pointer(Pointee, BaseAndOffset, BaseAndOffset) {}
 
Pointer::Pointer(const Pointer &P)
    : Offset(P.Offset), PointeeStorage(P.PointeeStorage),
      StorageKind(P.StorageKind) {
 
  if (isBlockPointer() && PointeeStorage.BS.Pointee)
    PointeeStorage.BS.Pointee->addPointer(this);
}
 
Pointer::Pointer(Block *Pointee, unsigned Base, uint64_t Offset)
    : Offset(Offset), StorageKind(Storage::Block) {
  assert((Base == RootPtrMark || Base % alignof(void *) == 0) && "wrong base");
 
  PointeeStorage.BS = {Pointee, Base};
 
  if (Pointee)
    Pointee->addPointer(this);
}
 
Pointer::Pointer(Pointer &&P)
    : Offset(P.Offset), PointeeStorage(P.PointeeStorage),
      StorageKind(P.StorageKind) {
 
  if (StorageKind == Storage::Block && PointeeStorage.BS.Pointee)
    PointeeStorage.BS.Pointee->replacePointer(&P, this);
}
 
Pointer::~Pointer() {
  if (!isBlockPointer())
    return;
 
  if (Block *Pointee = PointeeStorage.BS.Pointee) {
    Pointee->removePointer(this);
    PointeeStorage.BS.Pointee = nullptr;
    Pointee->cleanup();
  }
}
 
void Pointer::operator=(const Pointer &P) {
  // If the current storage type is Block, we need to remove
  // this pointer from the block.
  if (isBlockPointer()) {
    if (P.isBlockPointer() && this->block() == P.block()) {
      Offset = P.Offset;
      PointeeStorage.BS.Base = P.PointeeStorage.BS.Base;
      return;
    }
 
    if (Block *Pointee = PointeeStorage.BS.Pointee) {
      Pointee->removePointer(this);
      PointeeStorage.BS.Pointee = nullptr;
      Pointee->cleanup();
    }
  }
 
  StorageKind = P.StorageKind;
  Offset = P.Offset;
 
  if (P.isBlockPointer()) {
    PointeeStorage.BS = P.PointeeStorage.BS;
    PointeeStorage.BS.Pointee = P.PointeeStorage.BS.Pointee;
 
    if (PointeeStorage.BS.Pointee)
      PointeeStorage.BS.Pointee->addPointer(this);
  } else if (P.isIntegralPointer()) {
    PointeeStorage.Int = P.PointeeStorage.Int;
  } else if (P.isFunctionPointer()) {
    PointeeStorage.Fn = P.PointeeStorage.Fn;
  } else if (P.isTypeidPointer()) {
    PointeeStorage.Typeid = P.PointeeStorage.Typeid;
  } else {
    assert(false && "Unhandled storage kind");
  }
}
 
void Pointer::operator=(Pointer &&P) {
  // If the current storage type is Block, we need to remove
  // this pointer from the block.
  if (isBlockPointer()) {
    if (P.isBlockPointer() && this->block() == P.block()) {
      Offset = P.Offset;
      PointeeStorage.BS.Base = P.PointeeStorage.BS.Base;
      return;
    }
 
    if (Block *Pointee = PointeeStorage.BS.Pointee) {
      assert(P.block() != this->block());
      Pointee->removePointer(this);
      PointeeStorage.BS.Pointee = nullptr;
      Pointee->cleanup();
    }
  }
 
  StorageKind = P.StorageKind;
  Offset = P.Offset;
 
  if (P.isBlockPointer()) {
    PointeeStorage.BS = P.PointeeStorage.BS;
    PointeeStorage.BS.Pointee = P.PointeeStorage.BS.Pointee;
 
    if (PointeeStorage.BS.Pointee)
      PointeeStorage.BS.Pointee->addPointer(this);
  } else if (P.isIntegralPointer()) {
    PointeeStorage.Int = P.PointeeStorage.Int;
  } else if (P.isFunctionPointer()) {
    PointeeStorage.Fn = P.PointeeStorage.Fn;
  } else if (P.isTypeidPointer()) {
    PointeeStorage.Typeid = P.PointeeStorage.Typeid;
  } else {
    assert(false && "Unhandled storage kind");
  }
}
 
APValue Pointer::toAPValue(const ASTContext &ASTCtx) const {
  llvm::SmallVector<APValue::LValuePathEntry, 5> Path;
 
  if (isZero())
    return APValue(static_cast<const Expr *>(nullptr), CharUnits::Zero(), Path,
                   /*IsOnePastEnd=*/false, /*IsNullPtr=*/true);
  if (isIntegralPointer())
    return APValue(static_cast<const Expr *>(nullptr),
                   CharUnits::fromQuantity(asIntPointer().Value + this->Offset),
                   Path,
                   /*IsOnePastEnd=*/false, /*IsNullPtr=*/false);
  if (isFunctionPointer())
    return asFunctionPointer().toAPValue(ASTCtx);
 
  if (isTypeidPointer()) {
    TypeInfoLValue TypeInfo(PointeeStorage.Typeid.TypePtr);
    return APValue(
        APValue::LValueBase::getTypeInfo(
            TypeInfo, QualType(PointeeStorage.Typeid.TypeInfoType, 0)),
        CharUnits::Zero(), APValue::NoLValuePath{});
  }
 
  // Build the lvalue base from the block.
  const Descriptor *Desc = getDeclDesc();
  APValue::LValueBase Base;
  if (const auto *VD = Desc->asValueDecl())
    Base = VD;
  else if (const auto *E = Desc->asExpr()) {
    // Create a DynamicAlloc base of the right type.
    if (const auto *NewExpr = dyn_cast<CXXNewExpr>(E)) {
      QualType AllocatedType;
      if (NewExpr->isArray()) {
        assert(Desc->isArray());
        APInt ArraySize(64, static_cast<uint64_t>(Desc->getNumElems()),
                        /*IsSigned=*/false);
        AllocatedType =
            ASTCtx.getConstantArrayType(NewExpr->getAllocatedType(), ArraySize,
                                        nullptr, ArraySizeModifier::Normal, 0);
      } else {
        AllocatedType = NewExpr->getAllocatedType();
      }
      // FIXME: Suboptimal counting of dynamic allocations. Move this to Context
      // or InterpState?
      static int ReportedDynamicAllocs = 0;
      DynamicAllocLValue DA(ReportedDynamicAllocs++);
      Base = APValue::LValueBase::getDynamicAlloc(DA, AllocatedType);
    } else {
      Base = E;
    }
  } else
    llvm_unreachable("Invalid allocation type");
 
  if (isUnknownSizeArray())
    return APValue(Base, CharUnits::Zero(), Path,
                   /*IsOnePastEnd=*/isOnePastEnd(), /*IsNullPtr=*/false);
 
  CharUnits Offset = CharUnits::Zero();
 
  auto getFieldOffset = [&](const FieldDecl *FD) -> CharUnits {
    // This shouldn't happen, but if it does, don't crash inside
    // getASTRecordLayout.
    if (FD->getParent()->isInvalidDecl())
      return CharUnits::Zero();
    const ASTRecordLayout &Layout = ASTCtx.getASTRecordLayout(FD->getParent());
    unsigned FieldIndex = FD->getFieldIndex();
    return ASTCtx.toCharUnitsFromBits(Layout.getFieldOffset(FieldIndex));
  };
 
  // Build the path into the object.
  Pointer Ptr = *this;
  while (Ptr.isField() || Ptr.isArrayElement()) {
 
    if (Ptr.isArrayRoot()) {
      // An array root may still be an array element itself.
      if (Ptr.isArrayElement()) {
        Ptr = Ptr.expand();
        unsigned Index = Ptr.getIndex();
        Path.push_back(APValue::LValuePathEntry::ArrayIndex(Index));
        QualType ElemType = Ptr.getFieldDesc()->getElemQualType();
        Offset += (Index * ASTCtx.getTypeSizeInChars(ElemType));
        Ptr = Ptr.getArray();
      } else {
        Path.push_back(APValue::LValuePathEntry(
            {Ptr.getFieldDesc()->asDecl(), /*IsVirtual=*/false}));
 
        if (const auto *FD =
                dyn_cast_if_present<FieldDecl>(Ptr.getFieldDesc()->asDecl()))
          Offset += getFieldOffset(FD);
 
        Ptr = Ptr.getBase();
      }
    } else if (Ptr.isArrayElement()) {
      Ptr = Ptr.expand();
      unsigned Index;
      if (Ptr.isOnePastEnd())
        Index = Ptr.getArray().getNumElems();
      else
        Index = Ptr.getIndex();
 
      QualType ElemType = Ptr.getFieldDesc()->getElemQualType();
      Offset += (Index * ASTCtx.getTypeSizeInChars(ElemType));
      Path.push_back(APValue::LValuePathEntry::ArrayIndex(Index));
      Ptr = Ptr.getArray();
    } else {
      bool IsVirtual = false;
 
      // Create a path entry for the field.
      const Descriptor *Desc = Ptr.getFieldDesc();
      if (const auto *BaseOrMember = Desc->asDecl()) {
        if (const auto *FD = dyn_cast<FieldDecl>(BaseOrMember)) {
          Ptr = Ptr.getBase();
          Offset += getFieldOffset(FD);
        } else if (const auto *RD = dyn_cast<CXXRecordDecl>(BaseOrMember)) {
          IsVirtual = Ptr.isVirtualBaseClass();
          Ptr = Ptr.getBase();
          const Record *BaseRecord = Ptr.getRecord();
 
          const ASTRecordLayout &Layout = ASTCtx.getASTRecordLayout(
              cast<CXXRecordDecl>(BaseRecord->getDecl()));
          if (IsVirtual)
            Offset += Layout.getVBaseClassOffset(RD);
          else
            Offset += Layout.getBaseClassOffset(RD);
 
        } else {
          Ptr = Ptr.getBase();
        }
        Path.push_back(APValue::LValuePathEntry({BaseOrMember, IsVirtual}));
        continue;
      }
      llvm_unreachable("Invalid field type");
    }
  }
 
  // We assemble the LValuePath starting from the innermost pointer to the
  // outermost one. SO in a.b.c, the first element in Path will refer to
  // the field 'c', while later code expects it to refer to 'a'.
  // Just invert the order of the elements.
  std::reverse(Path.begin(), Path.end());
 
  return APValue(Base, Offset, Path, /*IsOnePastEnd=*/isOnePastEnd(),
                 /*IsNullPtr=*/false);
}
 
void Pointer::print(llvm::raw_ostream &OS) const {
  switch (StorageKind) {
  case Storage::Block: {
    const Block *B = PointeeStorage.BS.Pointee;
    OS << "(Block) " << B << " {";
 
    if (isRoot())
      OS << "rootptr(" << PointeeStorage.BS.Base << "), ";
    else
      OS << PointeeStorage.BS.Base << ", ";
 
    if (isElementPastEnd())
      OS << "pastend, ";
    else
      OS << Offset << ", ";
 
    if (B)
      OS << B->getSize();
    else
      OS << "nullptr";
    OS << "}";
  } break;
  case Storage::Int:
    OS << "(Int) {";
    OS << PointeeStorage.Int.Value << " + " << Offset << ", "
       << PointeeStorage.Int.Desc;
    OS << "}";
    break;
  case Storage::Fn:
    OS << "(Fn) { " << asFunctionPointer().getFunction() << " + " << Offset
       << " }";
    break;
  case Storage::Typeid:
    OS << "(Typeid)";
  }
}
 
std::string Pointer::toDiagnosticString(const ASTContext &Ctx) const {
  if (isZero())
    return "nullptr";
 
  if (isIntegralPointer())
    return (Twine("&(") + Twine(asIntPointer().Value + Offset) + ")").str();
 
  return toAPValue(Ctx).getAsString(Ctx, getType());
}
 
bool Pointer::isInitialized() const {
  if (!isBlockPointer())
    return true;
 
  if (isRoot() && PointeeStorage.BS.Base == sizeof(GlobalInlineDescriptor)) {
    const GlobalInlineDescriptor &GD =
        *reinterpret_cast<const GlobalInlineDescriptor *>(block()->rawData());
    return GD.InitState == GlobalInitState::Initialized;
  }
 
  assert(PointeeStorage.BS.Pointee &&
         "Cannot check if null pointer was initialized");
  const Descriptor *Desc = getFieldDesc();
  assert(Desc);
  if (Desc->isPrimitiveArray()) {
    if (isStatic() && PointeeStorage.BS.Base == 0)
      return true;
 
    InitMapPtr &IM = getInitMap();
 
    if (!IM)
      return false;
 
    if (IM->first)
      return true;
 
    return IM->second->isElementInitialized(getIndex());
  }
 
  if (asBlockPointer().Base == 0)
    return true;
 
  // Field has its bit in an inline descriptor.
  return getInlineDesc()->IsInitialized;
}
 
void Pointer::initialize() const {
  if (!isBlockPointer())
    return;
 
  assert(PointeeStorage.BS.Pointee && "Cannot initialize null pointer");
  const Descriptor *Desc = getFieldDesc();
 
  if (isRoot() && PointeeStorage.BS.Base == sizeof(GlobalInlineDescriptor)) {
    GlobalInlineDescriptor &GD = *reinterpret_cast<GlobalInlineDescriptor *>(
        asBlockPointer().Pointee->