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* 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
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include <deque>
#include <vector>
#include "dex_instruction.h"
#include "reg_type.h"
#include "safe_map.h"
namespace art {
namespace verifier {
class MethodVerifier;
* Register type categories, for type checking.
* The spec says category 1 includes boolean, byte, char, short, int, float, reference, and
* returnAddress. Category 2 includes long and double.
* We treat object references separately, so we have "category1nr". We don't support jsr/ret, so
* there is no "returnAddress" type.
enum TypeCategory {
kTypeCategoryUnknown = 0,
kTypeCategory1nr = 1, // boolean, byte, char, short, int, float
kTypeCategory2 = 2, // long, double
kTypeCategoryRef = 3, // object reference
// During verification, we associate one of these with every "interesting" instruction. We track
// the status of all registers, and (if the method has any monitor-enter instructions) maintain a
// stack of entered monitors (identified by code unit offset).
// If live-precise register maps are enabled, the "liveRegs" vector will be populated. Unlike the
// other lists of registers here, we do not track the liveness of the method result register
// (which is not visible to the GC).
class RegisterLine {
RegisterLine(size_t num_regs, MethodVerifier* verifier) :
line_(new uint16_t[num_regs]), verifier_(verifier), num_regs_(num_regs) {
memset(line_.get(), 0, num_regs_ * sizeof(uint16_t));
result_[0] = RegType::kRegTypeUnknown;
result_[1] = RegType::kRegTypeUnknown;
// Implement category-1 "move" instructions. Copy a 32-bit value from "vsrc" to "vdst".
void CopyRegister1(uint32_t vdst, uint32_t vsrc, TypeCategory cat);
// Implement category-2 "move" instructions. Copy a 64-bit value from "vsrc" to "vdst". This
// copies both halves of the register.
void CopyRegister2(uint32_t vdst, uint32_t vsrc);
// Implement "move-result". Copy the category-1 value from the result register to another
// register, and reset the result register.
void CopyResultRegister1(uint32_t vdst, bool is_reference);
// Implement "move-result-wide". Copy the category-2 value from the result register to another
// register, and reset the result register.
void CopyResultRegister2(uint32_t vdst);
// Set the invisible result register to unknown
void SetResultTypeToUnknown();
// Set the type of register N, verifying that the register is valid. If "newType" is the "Lo"
// part of a 64-bit value, register N+1 will be set to "newType+1".
// The register index was validated during the static pass, so we don't need to check it here.
bool SetRegisterType(uint32_t vdst, const RegType& new_type);
/* Set the type of the "result" register. */
void SetResultRegisterType(const RegType& new_type);
// Get the type of register vsrc.
const RegType& GetRegisterType(uint32_t vsrc) const;
bool VerifyRegisterType(uint32_t vsrc, const RegType& check_type);
void CopyFromLine(const RegisterLine* src) {
DCHECK_EQ(num_regs_, src->num_regs_);
memcpy(line_.get(), src->line_.get(), num_regs_ * sizeof(uint16_t));
monitors_ = src->monitors_;
reg_to_lock_depths_ = src->reg_to_lock_depths_;
std::string Dump() const {
std::string result;
for (size_t i = 0; i < num_regs_; i++) {
result += StringPrintf("%zd:[", i);
result += GetRegisterType(i).Dump();
result += "],";
typedef std::deque<uint32_t>::const_iterator It; // TODO: C++0x auto
for (It it = monitors_.begin(), end = monitors_.end(); it != end ; ++it) {
result += StringPrintf("{%d},", *it);
return result;
void FillWithGarbage() {
memset(line_.get(), 0xf1, num_regs_ * sizeof(uint16_t));
while (!monitors_.empty()) {
* We're creating a new instance of class C at address A. Any registers holding instances
* previously created at address A must be initialized by now. If not, we mark them as "conflict"
* to prevent them from being used (otherwise, MarkRefsAsInitialized would mark the old ones and
* the new ones at the same time).
void MarkUninitRefsAsInvalid(const RegType& uninit_type);
* Update all registers holding "uninit_type" to instead hold the corresponding initialized
* reference type. This is called when an appropriate constructor is invoked -- all copies of
* the reference must be marked as initialized.
void MarkRefsAsInitialized(const RegType& uninit_type);
* Check constraints on constructor return. Specifically, make sure that the "this" argument got
* initialized.
* The "this" argument to <init> uses code offset kUninitThisArgAddr, which puts it at the start
* of the list in slot 0. If we see a register with an uninitialized slot 0 reference, we know it
* somehow didn't get initialized.
bool CheckConstructorReturn() const;
// Compare two register lines. Returns 0 if they match.
// Using this for a sort is unwise, since the value can change based on machine endianness.
int CompareLine(const RegisterLine* line2) const {
DCHECK(monitors_ == line2->monitors_);
// TODO: DCHECK(reg_to_lock_depths_ == line2->reg_to_lock_depths_);
return memcmp(line_.get(), line2->line_.get(), num_regs_ * sizeof(uint16_t));
size_t NumRegs() const {
return num_regs_;
* Get the "this" pointer from a non-static method invocation. This returns the RegType so the
* caller can decide whether it needs the reference to be initialized or not. (Can also return
* kRegTypeZero if the reference can only be zero at this point.)
* The argument count is in vA, and the first argument is in vC, for both "simple" and "range"
* versions. We just need to make sure vA is >= 1 and then return vC.
const RegType& GetInvocationThis(const DecodedInstruction& dec_insn);
* Verify types for a simple two-register instruction (e.g. "neg-int").
* "dst_type" is stored into vA, and "src_type" is verified against vB.
void CheckUnaryOp(const DecodedInstruction& dec_insn,
const RegType& dst_type, const RegType& src_type);
* Verify types for a simple three-register instruction (e.g. "add-int").
* "dst_type" is stored into vA, and "src_type1"/"src_type2" are verified
* against vB/vC.
void CheckBinaryOp(const DecodedInstruction& dec_insn,
const RegType& dst_type, const RegType& src_type1, const RegType& src_type2,
bool check_boolean_op);
* Verify types for a binary "2addr" operation. "src_type1"/"src_type2"
* are verified against vA/vB, then "dst_type" is stored into vA.
void CheckBinaryOp2addr(const DecodedInstruction& dec_insn,
const RegType& dst_type,
const RegType& src_type1, const RegType& src_type2,
bool check_boolean_op);
* Verify types for A two-register instruction with a literal constant (e.g. "add-int/lit8").
* "dst_type" is stored into vA, and "src_type" is verified against vB.
* If "check_boolean_op" is set, we use the constant value in vC.
void CheckLiteralOp(const DecodedInstruction& dec_insn,
const RegType& dst_type, const RegType& src_type, bool check_boolean_op);
// Verify/push monitor onto the monitor stack, locking the value in reg_idx at location insn_idx.
void PushMonitor(uint32_t reg_idx, int32_t insn_idx);
// Verify/pop monitor from monitor stack ensuring that we believe the monitor is locked
void PopMonitor(uint32_t reg_idx);
// Stack of currently held monitors and where they were locked
size_t MonitorStackDepth() const {
return monitors_.size();
// We expect no monitors to be held at certain points, such a method returns. Verify the stack
// is empty, failing and returning false if not.
bool VerifyMonitorStackEmpty();
bool MergeRegisters(const RegisterLine* incoming_line);
size_t GetMaxNonZeroReferenceReg(size_t max_ref_reg) {
size_t i = static_cast<int>(max_ref_reg) < 0 ? 0 : max_ref_reg;
for (; i < num_regs_; i++) {
if (GetRegisterType(i).IsNonZeroReferenceTypes()) {
max_ref_reg = i;
return max_ref_reg;
// Write a bit at each register location that holds a reference
void WriteReferenceBitMap(std::vector<uint8_t>& data, size_t max_bytes);
void CopyRegToLockDepth(size_t dst, size_t src) {
SafeMap<uint32_t, uint32_t>::iterator it = reg_to_lock_depths_.find(src);
if (it != reg_to_lock_depths_.end()) {
reg_to_lock_depths_.Put(dst, it->second);
bool IsSetLockDepth(size_t reg, size_t depth) {
SafeMap<uint32_t, uint32_t>::iterator it = reg_to_lock_depths_.find(reg);
if (it != reg_to_lock_depths_.end()) {
return (it->second & (1 << depth)) != 0;
} else {
return false;
void SetRegToLockDepth(size_t reg, size_t depth) {
CHECK_LT(depth, 32u);
DCHECK(!IsSetLockDepth(reg, depth));
SafeMap<uint32_t, uint32_t>::iterator it = reg_to_lock_depths_.find(reg);
if (it == reg_to_lock_depths_.end()) {
reg_to_lock_depths_.Put(reg, 1 << depth);
} else {
it->second |= (1 << depth);
void ClearRegToLockDepth(size_t reg, size_t depth) {
CHECK_LT(depth, 32u);
DCHECK(IsSetLockDepth(reg, depth));
SafeMap<uint32_t, uint32_t>::iterator it = reg_to_lock_depths_.find(reg);
DCHECK(it != reg_to_lock_depths_.end());
uint32_t depths = it->second ^ (1 << depth);
if (depths != 0) {
it->second = depths;
} else {
void ClearAllRegToLockDepths(size_t reg) {
// Storage for the result register's type, valid after an invocation
uint16_t result_[2];
// An array of RegType Ids associated with each dex register
UniquePtr<uint16_t[]> line_;
// Back link to the verifier
MethodVerifier* verifier_;
// Length of reg_types_
const size_t num_regs_;
// A stack of monitor enter locations
std::deque<uint32_t> monitors_;
// A map from register to a bit vector of indices into the monitors_ stack. As we pop the monitor
// stack we verify that monitor-enter/exit are correctly nested. That is, if there was a
// monitor-enter on v5 and then on v6, we expect the monitor-exit to be on v6 then on v5
SafeMap<uint32_t, uint32_t> reg_to_lock_depths_;
std::ostream& operator<<(std::ostream& os, const RegisterLine& rhs);
} // namespace verifier
} // namespace art