runtime/verifier/register_line.h - platform/art - Gitiles

 /*
  * 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.
  */

 #ifndef ART_RUNTIME_VERIFIER_REGISTER_LINE_H_
 #define ART_RUNTIME_VERIFIER_REGISTER_LINE_H_

 #include <memory>
 #include <vector>

 #include "base/scoped_arena_containers.h"
 #include "safe_map.h"

 namespace art {

 class Instruction;

 namespace verifier {

 class MethodVerifier;
 class RegType;

 /*
  * 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
 };

 // What to do with the lock levels when setting the register type.
 enum class LockOp {
   kClear,                       // Clear the lock levels recorded.
   kKeep                         // Leave the lock levels alone.
 };

 // 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).
 class RegisterLine {
  public:
   // A map from register to a bit vector of indices into the monitors_ stack.
   using RegToLockDepthsMap = ScopedArenaSafeMap<uint32_t, uint32_t>;

   // Create a register line of num_regs registers.
   static RegisterLine* Create(size_t num_regs, MethodVerifier* verifier);

   // Implement category-1 "move" instructions. Copy a 32-bit value from "vsrc" to "vdst".
   void CopyRegister1(MethodVerifier* verifier, uint32_t vdst, uint32_t vsrc, TypeCategory cat)
       SHARED_REQUIRES(Locks::mutator_lock_);

   // Implement category-2 "move" instructions. Copy a 64-bit value from "vsrc" to "vdst". This
   // copies both halves of the register.
   void CopyRegister2(MethodVerifier* verifier, uint32_t vdst, uint32_t vsrc)
       SHARED_REQUIRES(Locks::mutator_lock_);

   // Implement "move-result". Copy the category-1 value from the result register to another
   // register, and reset the result register.
   void CopyResultRegister1(MethodVerifier* verifier, uint32_t vdst, bool is_reference)
       SHARED_REQUIRES(Locks::mutator_lock_);

   // Implement "move-result-wide". Copy the category-2 value from the result register to another
   // register, and reset the result register.
   void CopyResultRegister2(MethodVerifier* verifier, uint32_t vdst)
       SHARED_REQUIRES(Locks::mutator_lock_);

   // Set the invisible result register to unknown
   void SetResultTypeToUnknown(MethodVerifier* verifier) SHARED_REQUIRES(Locks::mutator_lock_);

   // 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.
   //
   // LockOp::kClear should be used by default; it will clear the lock levels associated with the
   // register. An example is setting the register type because an instruction writes to the
   // register.
   // LockOp::kKeep keeps the lock levels of the register and only changes the register type. This
   // is typical when the underlying value did not change, but we have "different" type information
   // available now. An example is sharpening types after a check-cast. Note that when given kKeep,
   // the new_type is dchecked to be a reference type.
   template <LockOp kLockOp>
   ALWAYS_INLINE bool SetRegisterType(MethodVerifier* verifier, uint32_t vdst,
                                      const RegType& new_type)
       SHARED_REQUIRES(Locks::mutator_lock_);

   bool SetRegisterTypeWide(MethodVerifier* verifier, uint32_t vdst, const RegType& new_type1,
                            const RegType& new_type2)
       SHARED_REQUIRES(Locks::mutator_lock_);

   /* Set the type of the "result" register. */
   void SetResultRegisterType(MethodVerifier* verifier, const RegType& new_type)
       SHARED_REQUIRES(Locks::mutator_lock_);

   void SetResultRegisterTypeWide(const RegType& new_type1, const RegType& new_type2)
       SHARED_REQUIRES(Locks::mutator_lock_);

   // Get the type of register vsrc.
   const RegType& GetRegisterType(MethodVerifier* verifier, uint32_t vsrc) const;

   ALWAYS_INLINE bool VerifyRegisterType(MethodVerifier* verifier, uint32_t vsrc,
                                         const RegType& check_type)
       SHARED_REQUIRES(Locks::mutator_lock_);

   bool VerifyRegisterTypeWide(MethodVerifier* verifier, uint32_t vsrc, const RegType& check_type1,
                               const RegType& check_type2)
       SHARED_REQUIRES(Locks::mutator_lock_);

   void CopyFromLine(const RegisterLine* src) {
     DCHECK_EQ(num_regs_, src->num_regs_);
     memcpy(&line_, &src->line_, num_regs_ * sizeof(uint16_t));
     monitors_ = src->monitors_;
     reg_to_lock_depths_ = src->reg_to_lock_depths_;
     this_initialized_ = src->this_initialized_;
   }

   std::string Dump(MethodVerifier* verifier) const SHARED_REQUIRES(Locks::mutator_lock_);

   void FillWithGarbage() {
     memset(&line_, 0xf1, num_regs_ * sizeof(uint16_t));
     monitors_.clear();
     reg_to_lock_depths_.clear();
   }

   /*
    * 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(MethodVerifier* verifier, const RegType& uninit_type)
       SHARED_REQUIRES(Locks::mutator_lock_);

   /*
    * 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(MethodVerifier* verifier, const RegType& uninit_type,
                              uint32_t this_reg, uint32_t dex_pc)
       SHARED_REQUIRES(Locks::mutator_lock_);

   /*
    * Update all registers to be Conflict except vsrc.
    */
   void MarkAllRegistersAsConflicts(MethodVerifier* verifier);
   void MarkAllRegistersAsConflictsExcept(MethodVerifier* verifier, uint32_t vsrc);
   void MarkAllRegistersAsConflictsExceptWide(MethodVerifier* verifier, uint32_t vsrc);

   void SetThisInitialized() {
     this_initialized_ = true;
   }

   void CopyThisInitialized(const RegisterLine& src) {
     this_initialized_ = src.this_initialized_;
   }

   /*
    * 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(MethodVerifier* verifier) 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 {
     if (monitors_ != line2->monitors_) {
       return 1;
     }
     // TODO: DCHECK(reg_to_lock_depths_ == line2->reg_to_lock_depths_);
     return memcmp(&line_, &line2->line_, 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.
    * allow_failure will return Conflict() instead of causing a verification failure if there is an
    * error.
    */
   const RegType& GetInvocationThis(MethodVerifier* verifier, const Instruction* inst,
                                    bool is_range, bool allow_failure = false)
       SHARED_REQUIRES(Locks::mutator_lock_);

   /*
    * 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(MethodVerifier* verifier, const Instruction* inst, const RegType& dst_type,
                     const RegType& src_type)
       SHARED_REQUIRES(Locks::mutator_lock_);

   void CheckUnaryOpWide(MethodVerifier* verifier, const Instruction* inst,
                         const RegType& dst_type1, const RegType& dst_type2,
                         const RegType& src_type1, const RegType& src_type2)
       SHARED_REQUIRES(Locks::mutator_lock_);

   void CheckUnaryOpToWide(MethodVerifier* verifier, const Instruction* inst,
                           const RegType& dst_type1, const RegType& dst_type2,
                           const RegType& src_type)
       SHARED_REQUIRES(Locks::mutator_lock_);

   void CheckUnaryOpFromWide(MethodVerifier* verifier, const Instruction* inst,
                             const RegType& dst_type,
                             const RegType& src_type1, const RegType& src_type2)
       SHARED_REQUIRES(Locks::mutator_lock_);

   /*
    * 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(MethodVerifier* verifier, const Instruction* inst,
                      const RegType& dst_type, const RegType& src_type1, const RegType& src_type2,
                      bool check_boolean_op)
       SHARED_REQUIRES(Locks::mutator_lock_);

   void 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)
       SHARED_REQUIRES(Locks::mutator_lock_);

   void CheckBinaryOpWideShift(MethodVerifier* verifier, const Instruction* inst,
                               const RegType& long_lo_type, const RegType& long_hi_type,
                               const RegType& int_type)
       SHARED_REQUIRES(Locks::mutator_lock_);

   /*
    * 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(MethodVerifier* verifier, const Instruction* inst,
                           const RegType& dst_type,
                           const RegType& src_type1, const RegType& src_type2,
                           bool check_boolean_op)
       SHARED_REQUIRES(Locks::mutator_lock_);

   void 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)
       SHARED_REQUIRES(Locks::mutator_lock_);

   void CheckBinaryOp2addrWideShift(MethodVerifier* verifier, const Instruction* inst,
                                    const RegType& long_lo_type, const RegType& long_hi_type,
                                    const RegType& int_type)
       SHARED_REQUIRES(Locks::mutator_lock_);

   /*
    * 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(MethodVerifier* verifier, const Instruction* inst,
                       const RegType& dst_type, const RegType& src_type,
                       bool check_boolean_op, bool is_lit16)
       SHARED_REQUIRES(Locks::mutator_lock_);

   // Verify/push monitor onto the monitor stack, locking the value in reg_idx at location insn_idx.
   void PushMonitor(MethodVerifier* verifier, uint32_t reg_idx, int32_t insn_idx)
       SHARED_REQUIRES(Locks::mutator_lock_);

   // Verify/pop monitor from monitor stack ensuring that we believe the monitor is locked
   void PopMonitor(MethodVerifier* verifier, uint32_t reg_idx)
       SHARED_REQUIRES(Locks::mutator_lock_);

   // 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, queueing a LOCKING error else.
   void VerifyMonitorStackEmpty(MethodVerifier* verifier) const;

   bool MergeRegisters(MethodVerifier* verifier, const RegisterLine* incoming_line)
       SHARED_REQUIRES(Locks::mutator_lock_);

   size_t GetMaxNonZeroReferenceReg(MethodVerifier* verifier, size_t max_ref_reg) const;

   // Write a bit at each register location that holds a reference.
   void WriteReferenceBitMap(MethodVerifier* verifier, std::vector<uint8_t>* data, size_t max_bytes);

   size_t GetMonitorEnterCount() const {
     return monitors_.size();
   }

   uint32_t GetMonitorEnterDexPc(size_t i) const {
     return monitors_[i];
   }

  private:
   void CopyRegToLockDepth(size_t dst, size_t src) {
     auto 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) {
     auto it = reg_to_lock_depths_.find(reg);
     if (it != reg_to_lock_depths_.end()) {
       return (it->second & (1 << depth)) != 0;
     } else {
       return false;
     }
   }

   bool SetRegToLockDepth(size_t reg, size_t depth) {
     CHECK_LT(depth, 32u);
     if (IsSetLockDepth(reg, depth)) {
       return false;  // Register already holds lock so locking twice is erroneous.
     }
     auto 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);
     }
     return true;
   }

   void ClearRegToLockDepth(size_t reg, size_t depth) {
     CHECK_LT(depth, 32u);
     DCHECK(IsSetLockDepth(reg, depth));
     auto 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 {
       reg_to_lock_depths_.erase(it);
     }
     // Need to unlock every register at the same lock depth. These are aliased locks.
     uint32_t mask = 1 << depth;
     for (auto& pair : reg_to_lock_depths_) {
       if ((pair.second & mask) != 0) {
         VLOG(verifier) << "Also unlocking " << pair.first;
         pair.second ^= mask;
       }
     }
   }

   void ClearAllRegToLockDepths(size_t reg) {
     reg_to_lock_depths_.erase(reg);
   }

   RegisterLine(size_t num_regs, MethodVerifier* verifier);

   // Storage for the result register's type, valid after an invocation.
   uint16_t result_[2];

   // Length of reg_types_
   const uint32_t num_regs_;

   // A stack of monitor enter locations.
   ScopedArenaVector<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.
   RegToLockDepthsMap reg_to_lock_depths_;

   // Whether "this" initialization (a constructor supercall) has happened.
   bool this_initialized_;

   // An array of RegType Ids associated with each dex register.
   uint16_t line_[1];

   DISALLOW_COPY_AND_ASSIGN(RegisterLine);
 };

 }  // namespace verifier
 }  // namespace art

 #endif  // ART_RUNTIME_VERIFIER_REGISTER_LINE_H_
	/*
	* 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.
	*/

	#ifndef ART_RUNTIME_VERIFIER_REGISTER_LINE_H_
	#define ART_RUNTIME_VERIFIER_REGISTER_LINE_H_

	#include <memory>
	#include <vector>

	#include "base/scoped_arena_containers.h"
	#include "safe_map.h"

	namespace art {

	class Instruction;

	namespace verifier {

	class MethodVerifier;
	class RegType;

	/*
	* 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
	};

	// What to do with the lock levels when setting the register type.
	enum class LockOp {
	kClear, // Clear the lock levels recorded.
	kKeep // Leave the lock levels alone.
	};

	// 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).
	class RegisterLine {
	public:
	// A map from register to a bit vector of indices into the monitors_ stack.
	using RegToLockDepthsMap = ScopedArenaSafeMap<uint32_t, uint32_t>;

	// Create a register line of num_regs registers.
	static RegisterLine* Create(size_t num_regs, MethodVerifier* verifier);

	// Implement category-1 "move" instructions. Copy a 32-bit value from "vsrc" to "vdst".
	void CopyRegister1(MethodVerifier* verifier, uint32_t vdst, uint32_t vsrc, TypeCategory cat)
	SHARED_REQUIRES(Locks::mutator_lock_);

	// Implement category-2 "move" instructions. Copy a 64-bit value from "vsrc" to "vdst". This
	// copies both halves of the register.
	void CopyRegister2(MethodVerifier* verifier, uint32_t vdst, uint32_t vsrc)
	SHARED_REQUIRES(Locks::mutator_lock_);

	// Implement "move-result". Copy the category-1 value from the result register to another
	// register, and reset the result register.
	void CopyResultRegister1(MethodVerifier* verifier, uint32_t vdst, bool is_reference)
	SHARED_REQUIRES(Locks::mutator_lock_);

	// Implement "move-result-wide". Copy the category-2 value from the result register to another
	// register, and reset the result register.
	void CopyResultRegister2(MethodVerifier* verifier, uint32_t vdst)
	SHARED_REQUIRES(Locks::mutator_lock_);

	// Set the invisible result register to unknown
	void SetResultTypeToUnknown(MethodVerifier* verifier) SHARED_REQUIRES(Locks::mutator_lock_);

	// 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.
	//
	// LockOp::kClear should be used by default; it will clear the lock levels associated with the
	// register. An example is setting the register type because an instruction writes to the
	// register.
	// LockOp::kKeep keeps the lock levels of the register and only changes the register type. This
	// is typical when the underlying value did not change, but we have "different" type information
	// available now. An example is sharpening types after a check-cast. Note that when given kKeep,
	// the new_type is dchecked to be a reference type.
	template <LockOp kLockOp>
	ALWAYS_INLINE bool SetRegisterType(MethodVerifier* verifier, uint32_t vdst,
	const RegType& new_type)
	SHARED_REQUIRES(Locks::mutator_lock_);

	bool SetRegisterTypeWide(MethodVerifier* verifier, uint32_t vdst, const RegType& new_type1,
	const RegType& new_type2)
	SHARED_REQUIRES(Locks::mutator_lock_);

	/* Set the type of the "result" register. */
	void SetResultRegisterType(MethodVerifier* verifier, const RegType& new_type)
	SHARED_REQUIRES(Locks::mutator_lock_);

	void SetResultRegisterTypeWide(const RegType& new_type1, const RegType& new_type2)
	SHARED_REQUIRES(Locks::mutator_lock_);

	// Get the type of register vsrc.
	const RegType& GetRegisterType(MethodVerifier* verifier, uint32_t vsrc) const;

	ALWAYS_INLINE bool VerifyRegisterType(MethodVerifier* verifier, uint32_t vsrc,
	const RegType& check_type)
	SHARED_REQUIRES(Locks::mutator_lock_);

	bool VerifyRegisterTypeWide(MethodVerifier* verifier, uint32_t vsrc, const RegType& check_type1,
	const RegType& check_type2)
	SHARED_REQUIRES(Locks::mutator_lock_);

	void CopyFromLine(const RegisterLine* src) {
	DCHECK_EQ(num_regs_, src->num_regs_);
	memcpy(&line_, &src->line_, num_regs_ * sizeof(uint16_t));
	monitors_ = src->monitors_;
	reg_to_lock_depths_ = src->reg_to_lock_depths_;
	this_initialized_ = src->this_initialized_;
	}

	std::string Dump(MethodVerifier* verifier) const SHARED_REQUIRES(Locks::mutator_lock_);

	void FillWithGarbage() {
	memset(&line_, 0xf1, num_regs_ * sizeof(uint16_t));
	monitors_.clear();
	reg_to_lock_depths_.clear();
	}

	/*
	* 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(MethodVerifier* verifier, const RegType& uninit_type)
	SHARED_REQUIRES(Locks::mutator_lock_);

	/*
	* 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(MethodVerifier* verifier, const RegType& uninit_type,
	uint32_t this_reg, uint32_t dex_pc)
	SHARED_REQUIRES(Locks::mutator_lock_);

	/*
	* Update all registers to be Conflict except vsrc.
	*/
	void MarkAllRegistersAsConflicts(MethodVerifier* verifier);
	void MarkAllRegistersAsConflictsExcept(MethodVerifier* verifier, uint32_t vsrc);
	void MarkAllRegistersAsConflictsExceptWide(MethodVerifier* verifier, uint32_t vsrc);

	void SetThisInitialized() {
	this_initialized_ = true;
	}

	void CopyThisInitialized(const RegisterLine& src) {
	this_initialized_ = src.this_initialized_;
	}

	/*
	* 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(MethodVerifier* verifier) 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 {
	if (monitors_ != line2->monitors_) {
	return 1;
	}
	// TODO: DCHECK(reg_to_lock_depths_ == line2->reg_to_lock_depths_);
	return memcmp(&line_, &line2->line_, 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.
	* allow_failure will return Conflict() instead of causing a verification failure if there is an
	* error.
	*/
	const RegType& GetInvocationThis(MethodVerifier* verifier, const Instruction* inst,
	bool is_range, bool allow_failure = false)
	SHARED_REQUIRES(Locks::mutator_lock_);

	/*
	* 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(MethodVerifier* verifier, const Instruction* inst, const RegType& dst_type,
	const RegType& src_type)
	SHARED_REQUIRES(Locks::mutator_lock_);

	void CheckUnaryOpWide(MethodVerifier* verifier, const Instruction* inst,
	const RegType& dst_type1, const RegType& dst_type2,
	const RegType& src_type1, const RegType& src_type2)
	SHARED_REQUIRES(Locks::mutator_lock_);

	void CheckUnaryOpToWide(MethodVerifier* verifier, const Instruction* inst,
	const RegType& dst_type1, const RegType& dst_type2,
	const RegType& src_type)
	SHARED_REQUIRES(Locks::mutator_lock_);

	void CheckUnaryOpFromWide(MethodVerifier* verifier, const Instruction* inst,
	const RegType& dst_type,
	const RegType& src_type1, const RegType& src_type2)
	SHARED_REQUIRES(Locks::mutator_lock_);

	/*
	* 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(MethodVerifier* verifier, const Instruction* inst,
	const RegType& dst_type, const RegType& src_type1, const RegType& src_type2,
	bool check_boolean_op)
	SHARED_REQUIRES(Locks::mutator_lock_);

	void 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)
	SHARED_REQUIRES(Locks::mutator_lock_);

	void CheckBinaryOpWideShift(MethodVerifier* verifier, const Instruction* inst,
	const RegType& long_lo_type, const RegType& long_hi_type,
	const RegType& int_type)
	SHARED_REQUIRES(Locks::mutator_lock_);

	/*
	* 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(MethodVerifier* verifier, const Instruction* inst,
	const RegType& dst_type,
	const RegType& src_type1, const RegType& src_type2,
	bool check_boolean_op)
	SHARED_REQUIRES(Locks::mutator_lock_);

	void 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)
	SHARED_REQUIRES(Locks::mutator_lock_);

	void CheckBinaryOp2addrWideShift(MethodVerifier* verifier, const Instruction* inst,
	const RegType& long_lo_type, const RegType& long_hi_type,
	const RegType& int_type)
	SHARED_REQUIRES(Locks::mutator_lock_);

	/*
	* 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(MethodVerifier* verifier, const Instruction* inst,
	const RegType& dst_type, const RegType& src_type,
	bool check_boolean_op, bool is_lit16)
	SHARED_REQUIRES(Locks::mutator_lock_);

	// Verify/push monitor onto the monitor stack, locking the value in reg_idx at location insn_idx.
	void PushMonitor(MethodVerifier* verifier, uint32_t reg_idx, int32_t insn_idx)
	SHARED_REQUIRES(Locks::mutator_lock_);

	// Verify/pop monitor from monitor stack ensuring that we believe the monitor is locked
	void PopMonitor(MethodVerifier* verifier, uint32_t reg_idx)
	SHARED_REQUIRES(Locks::mutator_lock_);

	// 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, queueing a LOCKING error else.
	void VerifyMonitorStackEmpty(MethodVerifier* verifier) const;

	bool MergeRegisters(MethodVerifier* verifier, const RegisterLine* incoming_line)
	SHARED_REQUIRES(Locks::mutator_lock_);

	size_t GetMaxNonZeroReferenceReg(MethodVerifier* verifier, size_t max_ref_reg) const;

	// Write a bit at each register location that holds a reference.
	void WriteReferenceBitMap(MethodVerifier* verifier, std::vector<uint8_t>* data, size_t max_bytes);

	size_t GetMonitorEnterCount() const {
	return monitors_.size();
	}

	uint32_t GetMonitorEnterDexPc(size_t i) const {
	return monitors_[i];
	}

	private:
	void CopyRegToLockDepth(size_t dst, size_t src) {
	auto 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) {
	auto it = reg_to_lock_depths_.find(reg);
	if (it != reg_to_lock_depths_.end()) {
	return (it->second & (1 << depth)) != 0;
	} else {
	return false;
	}
	}

	bool SetRegToLockDepth(size_t reg, size_t depth) {
	CHECK_LT(depth, 32u);
	if (IsSetLockDepth(reg, depth)) {
	return false; // Register already holds lock so locking twice is erroneous.
	}
	auto 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);
	}
	return true;
	}

	void ClearRegToLockDepth(size_t reg, size_t depth) {
	CHECK_LT(depth, 32u);
	DCHECK(IsSetLockDepth(reg, depth));
	auto 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 {
	reg_to_lock_depths_.erase(it);
	}
	// Need to unlock every register at the same lock depth. These are aliased locks.
	uint32_t mask = 1 << depth;
	for (auto& pair : reg_to_lock_depths_) {
	if ((pair.second & mask) != 0) {
	VLOG(verifier) << "Also unlocking " << pair.first;
	pair.second ^= mask;
	}
	}
	}

	void ClearAllRegToLockDepths(size_t reg) {
	reg_to_lock_depths_.erase(reg);
	}

	RegisterLine(size_t num_regs, MethodVerifier* verifier);

	// Storage for the result register's type, valid after an invocation.
	uint16_t result_[2];

	// Length of reg_types_
	const uint32_t num_regs_;

	// A stack of monitor enter locations.
	ScopedArenaVector<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.
	RegToLockDepthsMap reg_to_lock_depths_;

	// Whether "this" initialization (a constructor supercall) has happened.
	bool this_initialized_;

	// An array of RegType Ids associated with each dex register.
	uint16_t line_[1];

	DISALLOW_COPY_AND_ASSIGN(RegisterLine);
	};

	} // namespace verifier
	} // namespace art

	#endif // ART_RUNTIME_VERIFIER_REGISTER_LINE_H_