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// Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
// Declares a Simulator for ARM64 instructions if we are not generating a native
// ARM64 binary. This Simulator allows us to run and debug ARM64 code generation
// on regular desktop machines.
// Dart calls into generated code by "calling" the InvokeDartCode stub,
// which will start execution in the Simulator or forwards to the real entry
// on a ARM64 HW platform.
#error Do not include simulator_arm64.h directly; use simulator.h.
#include "vm/constants_arm64.h"
namespace dart {
class Isolate;
class Mutex;
class RawObject;
class SimulatorSetjmpBuffer;
class Thread;
typedef struct {
union {
int64_t i64[2];
int32_t i32[4];
} bits;
} simd_value_t;
class Simulator {
static const uword kSimulatorStackUnderflowSize = 64;
// The currently executing Simulator instance, which is associated to the
// current isolate
static Simulator* Current();
// Accessors for register state.
// The default value for R31Type has to be R31IsSP because get_register is
// accessed from architecture independent code through SPREG without
// specifying the type. We also can't translate a dummy value for SPREG into
// a real value because the architecture independent code expects SPREG to
// be a real register value.
void set_register(
Instr* instr, Register reg, int64_t value, R31Type r31t = R31IsSP);
int64_t get_register(Register reg, R31Type r31t = R31IsSP) const;
void set_wregister(Register reg, int32_t value, R31Type r31t = R31IsSP);
int32_t get_wregister(Register reg, R31Type r31t = R31IsSP) const;
int32_t get_vregisters(VRegister reg, int idx) const;
void set_vregisters(VRegister reg, int idx, int32_t value);
int64_t get_vregisterd(VRegister reg, int idx) const;
void set_vregisterd(VRegister reg, int idx, int64_t value);
void get_vregister(VRegister reg, simd_value_t* value) const;
void set_vregister(VRegister reg, const simd_value_t& value);
int64_t get_pc() const;
int64_t get_last_pc() const;
void set_pc(int64_t pc);
// Accessors to the internal simulator stack base and top.
uword StackBase() const { return reinterpret_cast<uword>(stack_); }
uword StackTop() const;
// Accessor to the instruction counter.
uint64_t get_icount() const { return icount_; }
// The isolate's top_exit_frame_info refers to a Dart frame in the simulator
// stack. The simulator's top_exit_frame_info refers to a C++ frame in the
// native stack.
uword top_exit_frame_info() const { return top_exit_frame_info_; }
void set_top_exit_frame_info(uword value) { top_exit_frame_info_ = value; }
// Call on program start.
static void InitOnce();
// Dart generally calls into generated code with 4 parameters. This is a
// convenience function, which sets up the simulator state and grabs the
// result on return. The return value is R0. The parameters are placed in
// R0-3.
int64_t Call(int64_t entry,
int64_t parameter0,
int64_t parameter1,
int64_t parameter2,
int64_t parameter3,
bool fp_return = false,
bool fp_args = false);
// Implementation of atomic compare and exchange in the same synchronization
// domain as other synchronization primitive instructions (e.g. ldrex, strex).
static uword CompareExchange(uword* address,
uword compare_value,
uword new_value);
// Runtime and native call support.
enum CallKind {
static uword RedirectExternalReference(uword function,
CallKind call_kind,
int argument_count);
static uword FunctionForRedirect(uword redirect);
void Longjmp(uword pc,
uword sp,
uword fp,
RawObject* raw_exception,
RawObject* raw_stacktrace,
Thread* thread);
// Known bad pc value to ensure that the simulator does not execute
// without being properly setup.
static const uword kBadLR = -1;
// A pc value used to signal the simulator to stop execution. Generally
// the lr is set to this value on transition from native C code to
// simulated execution, so that the simulator can "return" to the native
// C code.
static const uword kEndSimulatingPC = -2;
// CPU state.
int64_t registers_[kNumberOfCpuRegisters];
bool n_flag_;
bool z_flag_;
bool c_flag_;
bool v_flag_;
simd_value_t vregisters_[kNumberOfVRegisters];
// Simulator support.
int64_t last_pc_;
int64_t pc_;
char* stack_;
bool pc_modified_;
uint64_t icount_;
static int64_t flag_stop_sim_at_;
SimulatorSetjmpBuffer* last_setjmp_buffer_;
uword top_exit_frame_info_;
// Registered breakpoints.
Instr* break_pc_;
int64_t break_instr_;
// Illegal memory access support.
static bool IsIllegalAddress(uword addr) {
return addr < 64*1024;
void HandleIllegalAccess(uword addr, Instr* instr);
// Handles an unaligned memory access.
void UnalignedAccess(const char* msg, uword addr, Instr* instr);
// Handles a legal instruction that the simulator does not implement.
void UnimplementedInstruction(Instr* instr);
// Unsupported instructions use Format to print an error and stop execution.
void Format(Instr* instr, const char* format);
inline uint8_t ReadBU(uword addr);
inline int8_t ReadB(uword addr);
inline void WriteB(uword addr, uint8_t value);
inline uint16_t ReadHU(uword addr, Instr* instr);
inline int16_t ReadH(uword addr, Instr* instr);
inline void WriteH(uword addr, uint16_t value, Instr* instr);
inline uint32_t ReadWU(uword addr, Instr* instr);
inline int32_t ReadW(uword addr, Instr* instr);
inline void WriteW(uword addr, uint32_t value, Instr* instr);
inline intptr_t ReadX(uword addr, Instr* instr);
inline void WriteX(uword addr, intptr_t value, Instr* instr);
// We keep track of 16 exclusive access address tags across all threads.
// Since we cannot simulate a native context switch, which clears
// the exclusive access state of the local monitor (using the CLREX
// instruction), we associate the thread requesting exclusive access to the
// address tag. Multiple threads requesting exclusive access (using the LDREX
// instruction) to the same address will result in multiple address tags being
// created for the same address, one per thread.
// At any given time, each thread is associated to at most one address tag.
static Mutex* exclusive_access_lock_;
static const int kNumAddressTags = 16;
static struct AddressTag {
Thread* thread;
uword addr;
} exclusive_access_state_[kNumAddressTags];
static int next_address_tag_;
// Synchronization primitives support.
void ClearExclusive();
intptr_t ReadExclusiveW(uword addr, Instr* instr);
intptr_t WriteExclusiveW(uword addr, intptr_t value, Instr* instr);
// Set access to given address to 'exclusive state' for current thread.
static void SetExclusiveAccess(uword addr);
// Returns true if the current thread has exclusive access to given address,
// returns false otherwise. In either case, set access to given address to
// 'open state' for all threads.
// If given addr is NULL, set access to 'open state' for current
// thread (CLREX).
static bool HasExclusiveAccessAndOpen(uword addr);
// Helper functions to set the conditional flags in the architecture state.
void SetNZFlagsW(int32_t val);
bool CarryFromW(int32_t left, int32_t right, int32_t carry);
bool OverflowFromW(int32_t left, int32_t right, int32_t carry);
void SetNZFlagsX(int64_t val);
bool CarryFromX(int64_t alu_out, int64_t left, int64_t right, bool addition);
bool OverflowFromX(
int64_t alu_out, int64_t left, int64_t right, bool addition);
void SetCFlag(bool val);
void SetVFlag(bool val);
int64_t ShiftOperand(uint8_t reg_size,
int64_t value,
Shift shift_type,
uint8_t amount);
int64_t ExtendOperand(uint8_t reg_size,
int64_t value,
Extend extend_type,
uint8_t amount);
int64_t DecodeShiftExtendOperand(Instr* instr);
bool ConditionallyExecute(Instr* instr);
void DoRedirectedCall(Instr* instr);
// Decode instructions.
void InstructionDecode(Instr* instr);
#define DECODE_OP(op) \
void Decode##op(Instr* instr);
#undef DECODE_OP
// Executes ARM64 instructions until the PC reaches kEndSimulatingPC.
void Execute();
// Returns true if tracing of executed instructions is enabled.
bool IsTracingExecution() const;
// Longjmp support for exceptions.
SimulatorSetjmpBuffer* last_setjmp_buffer() {
return last_setjmp_buffer_;
void set_last_setjmp_buffer(SimulatorSetjmpBuffer* buffer) {
last_setjmp_buffer_ = buffer;
friend class SimulatorDebugger;
friend class SimulatorSetjmpBuffer;
} // namespace dart
#endif // VM_SIMULATOR_ARM64_H_