path: root/runtime/verifier/register_line.cc

/*
 * Copyright (C) 2012 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "register_line.h"

#include "base/stringprintf.h"
#include "dex_instruction-inl.h"
#include "method_verifier.h"
#include "register_line-inl.h"
#include "reg_type-inl.h"

namespace art {
namespace verifier {

bool RegisterLine::WasUninitializedThisOverwritten(MethodVerifier* verifier,
                                                   size_t this_loc,
                                                   bool was_invoke_direct) const {
  DCHECK(verifier->IsConstructor());

  // Is the UnintializedThis type still there?
  if (GetRegisterType(verifier, this_loc).IsUninitializedThisReference() ||
      GetRegisterType(verifier, this_loc).IsUnresolvedAndUninitializedThisReference()) {
    return false;
  }

  // If there is an initialized reference here now, did we just perform an invoke-direct? Note that
  // this is the correct approach for dex bytecode: results of invoke-direct are stored in the
  // result register. Overwriting "this_loc" can only be done by a constructor call.
  if (GetRegisterType(verifier, this_loc).IsReferenceTypes() && was_invoke_direct) {
    return false;
    // Otherwise we could have just copied a different initialized reference to this location.
  }

  // The UnintializedThis in the register is gone, so check to see if it's somewhere else now.
  for (size_t i = 0; i < num_regs_; i++) {
    if (GetRegisterType(verifier, i).IsUninitializedThisReference() ||
        GetRegisterType(verifier, i).IsUnresolvedAndUninitializedThisReference()) {
      // We found it somewhere else...
      return false;
    }
  }

  // The UninitializedThis is gone from the original register, and now we can't find it.
  return true;
}

bool RegisterLine::GetUninitializedThisLoc(MethodVerifier* verifier, size_t* vreg) const {
  for (size_t i = 0; i < num_regs_; i++) {
    if (GetRegisterType(verifier, i).IsUninitializedThisReference() ||
        GetRegisterType(verifier, i).IsUnresolvedAndUninitializedThisReference()) {
      *vreg = i;
      return true;
    }
  }
  return false;
}

bool RegisterLine::CheckConstructorReturn(MethodVerifier* verifier) const {
  for (size_t i = 0; i < num_regs_; i++) {
    if (GetRegisterType(verifier, i).IsUninitializedThisReference() ||
        GetRegisterType(verifier, i).IsUnresolvedAndUninitializedThisReference()) {
      verifier->Fail(VERIFY_ERROR_BAD_CLASS_SOFT)
          << "Constructor returning without calling superclass constructor";
      return false;
    }
  }
  return true;
}

const RegType& RegisterLine::GetInvocationThis(MethodVerifier* verifier, const Instruction* inst,
                                               bool is_range, bool allow_failure) {
  const size_t args_count = is_range ? inst->VRegA_3rc() : inst->VRegA_35c();
  if (args_count < 1) {
    if (!allow_failure) {
      verifier->Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "invoke lacks 'this'";
    }
    return verifier->GetRegTypeCache()->Conflict();
  }
  /* Get the element type of the array held in vsrc */
  const uint32_t this_reg = (is_range) ? inst->VRegC_3rc() : inst->VRegC_35c();
  const RegType& this_type = GetRegisterType(verifier, this_reg);
  if (!this_type.IsReferenceTypes()) {
    if (!allow_failure) {
      verifier->Fail(VERIFY_ERROR_BAD_CLASS_HARD)
          << "tried to get class from non-reference register v" << this_reg
          << " (type=" << this_type << ")";
    }
    return verifier->GetRegTypeCache()->Conflict();
  }
  return this_type;
}

bool RegisterLine::VerifyRegisterTypeWide(MethodVerifier* verifier, uint32_t vsrc,
                                          const RegType& check_type1,
                                          const RegType& check_type2) {
  DCHECK(check_type1.CheckWidePair(check_type2));
  // Verify the src register type against the check type refining the type of the register
  const RegType& src_type = GetRegisterType(verifier, vsrc);
  if (!check_type1.IsAssignableFrom(src_type)) {
    verifier->Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "register v" << vsrc << " has type " << src_type
                               << " but expected " << check_type1;
    return false;
  }
  const RegType& src_type_h = GetRegisterType(verifier, vsrc + 1);
  if (!src_type.CheckWidePair(src_type_h)) {
    verifier->Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "wide register v" << vsrc << " has type "
        << src_type << "/" << src_type_h;
    return false;
  }
  // The register at vsrc has a defined type, we know the lower-upper-bound, but this is less
  // precise than the subtype in vsrc so leave it for reference types. For primitive types
  // if they are a defined type then they are as precise as we can get, however, for constant
  // types we may wish to refine them. Unfortunately constant propagation has rendered this useless.
  return true;
}

void RegisterLine::MarkRefsAsInitialized(MethodVerifier* verifier, const RegType& uninit_type,
                                         uint32_t this_reg, uint32_t dex_pc) {
  DCHECK(uninit_type.IsUninitializedTypes());
  bool is_string = !uninit_type.IsUnresolvedTypes() && uninit_type.GetClass()->IsStringClass();
  const RegType& init_type = verifier->GetRegTypeCache()->FromUninitialized(uninit_type);
  size_t changed = 0;
  for (uint32_t i = 0; i < num_regs_; i++) {
    if (GetRegisterType(verifier, i).Equals(uninit_type)) {
      line_[i] = init_type.GetId();
      changed++;
      if (is_string && i != this_reg) {
        auto it = verifier->GetStringInitPcRegMap().find(dex_pc);
        if (it != verifier->GetStringInitPcRegMap().end()) {
          it->second.insert(i);
        } else {
          std::set<uint32_t> reg_set = { i };
          verifier->GetStringInitPcRegMap().Put(dex_pc, reg_set);
        }
      }
    }
  }
  DCHECK_GT(changed, 0u);
}

void RegisterLine::MarkAllRegistersAsConflicts(MethodVerifier* verifier) {
  uint16_t conflict_type_id = verifier->GetRegTypeCache()->Conflict().GetId();
  for (uint32_t i = 0; i < num_regs_; i++) {
    line_[i] = conflict_type_id;
  }
}

void RegisterLine::MarkAllRegistersAsConflictsExcept(MethodVerifier* verifier, uint32_t vsrc) {
  uint16_t conflict_type_id = verifier->GetRegTypeCache()->Conflict().GetId();
  for (uint32_t i = 0; i < num_regs_; i++) {
    if (i != vsrc) {
      line_[i] = conflict_type_id;
    }
  }
}

void RegisterLine::MarkAllRegistersAsConflictsExceptWide(MethodVerifier* verifier, uint32_t vsrc) {
  uint16_t conflict_type_id = verifier->GetRegTypeCache()->Conflict().GetId();
  for (uint32_t i = 0; i < num_regs_; i++) {
    if ((i != vsrc) && (i != (vsrc + 1))) {
      line_[i] = conflict_type_id;
    }
  }
}

std::string RegisterLine::Dump(MethodVerifier* verifier) const {
  std::string result;
  for (size_t i = 0; i < num_regs_; i++) {
    result += StringPrintf("%zd:[", i);
    result += GetRegisterType(verifier, i).Dump();
    result += "],";
  }
  for (const auto& monitor : monitors_) {
    result += StringPrintf("{%d},", monitor);
  }
  return result;
}

void RegisterLine::MarkUninitRefsAsInvalid(MethodVerifier* verifier, const RegType& uninit_type) {
  for (size_t i = 0; i < num_regs_; i++) {
    if (GetRegisterType(verifier, i).Equals(uninit_type)) {
      line_[i] = verifier->GetRegTypeCache()->Conflict().GetId();
      ClearAllRegToLockDepths(i);
    }
  }
}

void RegisterLine::CopyResultRegister1(MethodVerifier* verifier, uint32_t vdst, bool is_reference) {
  const RegType& type = verifier->GetRegTypeCache()->GetFromId(result_[0]);
  if ((!is_reference && !type.IsCategory1Types()) ||
      (is_reference && !type.IsReferenceTypes())) {
    verifier->Fail(VERIFY_ERROR_BAD_CLASS_HARD)
        << "copyRes1 v" << vdst << "<- result0"  << " type=" << type;
  } else {
    DCHECK(verifier->GetRegTypeCache()->GetFromId(result_[1]).IsUndefined());
    SetRegisterType(verifier, vdst, type);
    result_[0] = verifier->GetRegTypeCache()->Undefined().GetId();
  }
}

/*
 * Implement "move-result-wide". Copy the category-2 value from the result
 * register to another register, and reset the result register.
 */
void RegisterLine::CopyResultRegister2(MethodVerifier* verifier, uint32_t vdst) {
  const RegType& type_l = verifier->GetRegTypeCache()->GetFromId(result_[0]);
  const RegType& type_h = verifier->GetRegTypeCache()->GetFromId(result_[1]);
  if (!type_l.IsCategory2Types()) {
    verifier->Fail(VERIFY_ERROR_BAD_CLASS_HARD)
        << "copyRes2 v" << vdst << "<- result0"  << " type=" << type_l;
  } else {
    DCHECK(type_l.CheckWidePair(type_h));  // Set should never allow this case
    SetRegisterTypeWide(verifier, vdst, type_l, type_h);  // also sets the high
    result_[0] = verifier->GetRegTypeCache()->Undefined().GetId();
    result_[1] = verifier->GetRegTypeCache()->Undefined().GetId();
  }
}

void RegisterLine::CheckUnaryOp(MethodVerifier* verifier, const Instruction* inst,
                                const RegType& dst_type, const RegType& src_type) {
  if (VerifyRegisterType(verifier, inst->VRegB_12x(), src_type)) {
    SetRegisterType(verifier, inst->VRegA_12x(), dst_type);
  }
}

void RegisterLine::CheckUnaryOpWide(MethodVerifier* verifier, const Instruction* inst,
                                    const RegType& dst_type1, const RegType& dst_type2,
                                    const RegType& src_type1, const RegType& src_type2) {
  if (VerifyRegisterTypeWide(verifier, inst->VRegB_12x(), src_type1, src_type2)) {
    SetRegisterTypeWide(verifier, inst->VRegA_12x(), dst_type1, dst_type2);
  }
}

void RegisterLine::CheckUnaryOpToWide(MethodVerifier* verifier, const Instruction* inst,
                                      const RegType& dst_type1, const RegType& dst_type2,
                                      const RegType& src_type) {
  if (VerifyRegisterType(verifier, inst->VRegB_12x(), src_type)) {
    SetRegisterTypeWide(verifier, inst->VRegA_12x(), dst_type1, dst_type2);
  }
}

void RegisterLine::CheckUnaryOpFromWide(MethodVerifier* verifier, const Instruction* inst,
                                        const RegType& dst_type,
                                        const RegType& src_type1, const RegType& src_type2) {
  if (VerifyRegisterTypeWide(verifier, inst->VRegB_12x(), src_type1, src_type2)) {
    SetRegisterType(verifier, inst->VRegA_12x(), dst_type);
  }
}

void RegisterLine::CheckBinaryOp(MethodVerifier* verifier, const Instruction* inst,
                                 const RegType& dst_type,
                                 const RegType& src_type1, const RegType& src_type2,
                                 bool check_boolean_op) {
  const uint32_t vregB = inst->VRegB_23x();
  const uint32_t vregC = inst->VRegC_23x();
  if (VerifyRegisterType(verifier, vregB, src_type1) &&
      VerifyRegisterType(verifier, vregC, src_type2)) {
    if (check_boolean_op) {
      DCHECK(dst_type.IsInteger());
      if (GetRegisterType(verifier, vregB).IsBooleanTypes() &&
          GetRegisterType(verifier, vregC).IsBooleanTypes()) {
        SetRegisterType(verifier, inst->VRegA_23x(), verifier->GetRegTypeCache()->Boolean());
        return;
      }
    }
    SetRegisterType(verifier, inst->VRegA_23x(), dst_type);
  }
}

void RegisterLine::CheckBinaryOpWide(MethodVerifier* verifier, const Instruction* inst,
                                     const RegType& dst_type1, const RegType& dst_type2,
                                     const RegType& src_type1_1, const RegType& src_type1_2,
                                     const RegType& src_type2_1, const RegType& src_type2_2) {
  if (VerifyRegisterTypeWide(verifier, inst->VRegB_23x(), src_type1_1, src_type1_2) &&
      VerifyRegisterTypeWide(verifier, inst->VRegC_23x(), src_type2_1, src_type2_2)) {
    SetRegisterTypeWide(verifier, inst->VRegA_23x(), dst_type1, dst_type2);
  }
}

void RegisterLine::CheckBinaryOpWideShift(MethodVerifier* verifier, const Instruction* inst,
                                          const RegType& long_lo_type, const RegType& long_hi_type,
                                          const RegType& int_type) {
  if (VerifyRegisterTypeWide(verifier, inst->VRegB_23x(), long_lo_type, long_hi_type) &&
      VerifyRegisterType(verifier, inst->VRegC_23x(), int_type)) {
    SetRegisterTypeWide(verifier, inst->VRegA_23x(), long_lo_type, long_hi_type);
  }
}

void RegisterLine::CheckBinaryOp2addr(MethodVerifier* verifier, const Instruction* inst,
                                      const RegType& dst_type, const RegType& src_type1,
                                      const RegType& src_type2, bool check_boolean_op) {
  const uint32_t vregA = inst->VRegA_12x();
  const uint32_t vregB = inst->VRegB_12x();
  if (VerifyRegisterType(verifier, vregA, src_type1) &&
      VerifyRegisterType(verifier, vregB, src_type2)) {
    if (check_boolean_op) {
      DCHECK(dst_type.IsInteger());
      if (GetRegisterType(verifier, vregA).IsBooleanTypes() &&
          GetRegisterType(verifier, vregB).IsBooleanTypes()) {
        SetRegisterType(verifier, vregA, verifier->GetRegTypeCache()->Boolean());
        return;
      }
    }
    SetRegisterType(verifier, vregA, dst_type);
  }
}

void RegisterLine::CheckBinaryOp2addrWide(MethodVerifier* verifier, const Instruction* inst,
                                          const RegType& dst_type1, const RegType& dst_type2,
                                          const RegType& src_type1_1, const RegType& src_type1_2,
                                          const RegType& src_type2_1, const RegType& src_type2_2) {
  const uint32_t vregA = inst->VRegA_12x();
  const uint32_t vregB = inst->VRegB_12x();
  if (VerifyRegisterTypeWide(verifier, vregA, src_type1_1, src_type1_2) &&
      VerifyRegisterTypeWide(verifier, vregB, src_type2_1, src_type2_2)) {
    SetRegisterTypeWide(verifier, vregA, dst_type1, dst_type2);
  }
}

void RegisterLine::CheckBinaryOp2addrWideShift(MethodVerifier* verifier, const Instruction* inst,
                                               const RegType& long_lo_type, const RegType& long_hi_type,
                                               const RegType& int_type) {
  const uint32_t vregA = inst->VRegA_12x();
  const uint32_t vregB = inst->VRegB_12x();
  if (VerifyRegisterTypeWide(verifier, vregA, long_lo_type, long_hi_type) &&
      VerifyRegisterType(verifier, vregB, int_type)) {
    SetRegisterTypeWide(verifier, vregA, long_lo_type, long_hi_type);
  }
}

void RegisterLine::CheckLiteralOp(MethodVerifier* verifier, const Instruction* inst,
                                  const RegType& dst_type, const RegType& src_type,
                                  bool check_boolean_op, bool is_lit16) {
  const uint32_t vregA = is_lit16 ? inst->VRegA_22s() : inst->VRegA_22b();
  const uint32_t vregB = is_lit16 ? inst->VRegB_22s() : inst->VRegB_22b();
  if (VerifyRegisterType(verifier, vregB, src_type)) {
    if (check_boolean_op) {
      DCHECK(dst_type.IsInteger());
      /* check vB with the call, then check the constant manually */
      const uint32_t val = is_lit16 ? inst->VRegC_22s() : inst->VRegC_22b();
      if (GetRegisterType(verifier, vregB).IsBooleanTypes() && (val == 0 || val == 1)) {
        SetRegisterType(verifier, vregA, verifier->GetRegTypeCache()->Boolean());
        return;
      }
    }
    SetRegisterType(verifier, vregA, dst_type);
  }
}

void RegisterLine::PushMonitor(MethodVerifier* verifier, uint32_t reg_idx, int32_t insn_idx) {
  const RegType& reg_type = GetRegisterType(verifier, reg_idx);
  if (!reg_type.IsReferenceTypes()) {
    verifier->Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "monitor-enter on non-object ("
        << reg_type << ")";
  } else if (monitors_.size() >= 32) {
    verifier->Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "monitor-enter stack overflow: "
        << monitors_.size();
  } else {
    if (SetRegToLockDepth(reg_idx, monitors_.size())) {
      monitors_.push_back(insn_idx);
    } else {
      verifier->Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "unexpected monitor-enter on register v" <<
          reg_idx;
    }
  }
}

void RegisterLine::PopMonitor(MethodVerifier* verifier, uint32_t reg_idx) {
  const RegType& reg_type = GetRegisterType(verifier, reg_idx);
  if (!reg_type.IsReferenceTypes()) {
    verifier->Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "monitor-exit on non-object (" << reg_type << ")";
  } else if (monitors_.empty()) {
    verifier->Fail(VERIFY_ERROR_BAD_CLASS_HARD) << "monitor-exit stack underflow";
  } else {
    monitors_.pop_back();
    if (!IsSetLockDepth(reg_idx, monitors_.size())) {
      // Bug 3215458: Locks and unlocks are on objects, if that object is a literal then before
      // format "036" the constant collector may create unlocks on the same object but referenced
      // via different registers.
      ((verifier->DexFileVersion() >= 36) ? verifier->Fail(VERIFY_ERROR_BAD_CLASS_SOFT)
                                          : verifier->LogVerifyInfo())
            << "monitor-exit not unlocking the top of the monitor stack";
    } else {
      // Record the register was unlocked
      ClearRegToLockDepth(reg_idx, monitors_.size());
    }
  }
}

bool RegisterLine::MergeRegisters(MethodVerifier* verifier, const RegisterLine* incoming_line) {
  bool changed = false;
  DCHECK(incoming_line != nullptr);
  for (size_t idx = 0; idx < num_regs_; idx++) {
    if (line_[idx] != incoming_line->line_[idx]) {
      const RegType& incoming_reg_type = incoming_line->GetRegisterType(verifier, idx);
      const RegType& cur_type = GetRegisterType(verifier, idx);
      const RegType& new_type = cur_type.Merge(incoming_reg_type, verifier->GetRegTypeCache());
      changed = changed || !cur_type.Equals(new_type);
      line_[idx] = new_type.GetId();
    }
  }
  if (monitors_.size() > 0 || incoming_line->monitors_.size() > 0) {
    if (monitors_.size() != incoming_line->monitors_.size()) {
      LOG(WARNING) << "mismatched stack depths (depth=" << MonitorStackDepth()
                     << ", incoming depth=" << incoming_line->MonitorStackDepth() << ")";
    } else if (reg_to_lock_depths_ != incoming_line->reg_to_lock_depths_) {
      for (uint32_t idx = 0; idx < num_regs_; idx++) {
        size_t depths = reg_to_lock_depths_.count(idx);
        size_t incoming_depths = incoming_line->reg_to_lock_depths_.count(idx);
        if (depths != incoming_depths) {
          if (depths == 0 || incoming_depths == 0) {
            reg_to_lock_depths_.erase(idx);
          } else {
            LOG(WARNING) << "mismatched stack depths for register v" << idx
                << ": " << depths  << " != " << incoming_depths;
            break;
          }
        }
      }
    }
  }
  return changed;
}

void RegisterLine::WriteReferenceBitMap(MethodVerifier* verifier,
                                        std::vector<uint8_t>* data, size_t max_bytes) {
  for (size_t i = 0; i < num_regs_; i += 8) {
    uint8_t val = 0;
    for (size_t j = 0; j < 8 && (i + j) < num_regs_; j++) {
      // Note: we write 1 for a Reference but not for Null
      if (GetRegisterType(verifier, i + j).IsNonZeroReferenceTypes()) {
        val |= 1 << j;
      }
    }
    if ((i / 8) >= max_bytes) {
      DCHECK_EQ(0, val);
      continue;
    }
    DCHECK_LT(i / 8, max_bytes) << "val=" << static_cast<uint32_t>(val);
    data->push_back(val);
  }
}

}  // namespace verifier
}  // namespace art