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sdk/runtime/vm/simulator_arm64.cc
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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.
#include <math.h> // for isnan.
#include <setjmp.h>
#include <stdlib.h>
#include "vm/globals.h"
#if defined(TARGET_ARCH_ARM64)
// Only build the simulator if not compiling for real ARM hardware.
#if !defined(HOST_ARCH_ARM64)
#include "vm/simulator.h"
#include "vm/assembler.h"
#include "vm/constants_arm64.h"
#include "vm/cpu.h"
#include "vm/disassembler.h"
#include "vm/native_arguments.h"
#include "vm/stack_frame.h"
#include "vm/thread.h"
namespace dart {
DEFINE_FLAG(bool, trace_sim, false, "Trace simulator execution.");
DEFINE_FLAG(int, stop_sim_at, 0, "Address to stop simulator at.");
// This macro provides a platform independent use of sscanf. The reason for
// SScanF not being implemented in a platform independent way through
// OS in the same way as SNPrint is that the Windows C Run-Time
// Library does not provide vsscanf.
#define SScanF sscanf // NOLINT
// SimulatorSetjmpBuffer are linked together, and the last created one
// is referenced by the Simulator. When an exception is thrown, the exception
// runtime looks at where to jump and finds the corresponding
// SimulatorSetjmpBuffer based on the stack pointer of the exception handler.
// The runtime then does a Longjmp on that buffer to return to the simulator.
class SimulatorSetjmpBuffer {
public:
int Setjmp() { return setjmp(buffer_); }
void Longjmp() {
// "This" is now the last setjmp buffer.
simulator_->set_last_setjmp_buffer(this);
longjmp(buffer_, 1);
}
explicit SimulatorSetjmpBuffer(Simulator* sim) {
simulator_ = sim;
link_ = sim->last_setjmp_buffer();
sim->set_last_setjmp_buffer(this);
sp_ = static_cast<uword>(sim->get_register(R31, R31IsSP));
native_sp_ = reinterpret_cast<uword>(&sim); // Current C++ stack pointer.
}
~SimulatorSetjmpBuffer() {
ASSERT(simulator_->last_setjmp_buffer() == this);
simulator_->set_last_setjmp_buffer(link_);
}
SimulatorSetjmpBuffer* link() { return link_; }
uword sp() { return sp_; }
uword native_sp() { return native_sp_; }
private:
uword sp_;
uword native_sp_;
Simulator* simulator_;
SimulatorSetjmpBuffer* link_;
jmp_buf buffer_;
friend class Simulator;
};
// The SimulatorDebugger class is used by the simulator while debugging
// simulated ARM64 code.
class SimulatorDebugger {
public:
explicit SimulatorDebugger(Simulator* sim);
~SimulatorDebugger();
void Stop(Instr* instr, const char* message);
void Debug();
char* ReadLine(const char* prompt);
private:
Simulator* sim_;
bool GetValue(char* desc, int64_t* value);
// TODO(zra): GetVValue for doubles.
// TODO(zra): Breakpoints.
};
SimulatorDebugger::SimulatorDebugger(Simulator* sim) {
sim_ = sim;
}
SimulatorDebugger::~SimulatorDebugger() {
}
void SimulatorDebugger::Stop(Instr* instr, const char* message) {
OS::Print("Simulator hit %s\n", message);
Debug();
}
static Register LookupCpuRegisterByName(const char* name) {
static const char* kNames[] = {
"r0", "r1", "r2", "r3",
"r4", "r5", "r6", "r7",
"r8", "r9", "r10", "r11",
"r12", "r13", "r14", "r15",
"r16", "r17", "r18", "r19",
"r20", "r21", "r22", "r23",
"r24", "r25", "r26", "r27",
"r28", "r29", "r30",
"ip0", "ip1", "pp", "ctx", "fp", "lr", "sp", "zr",
};
static const Register kRegisters[] = {
R0, R1, R2, R3, R4, R5, R6, R7,
R8, R9, R10, R11, R12, R13, R14, R15,
R16, R17, R18, R19, R20, R21, R22, R23,
R24, R25, R26, R27, R28, R29, R30,
IP0, IP1, PP, CTX, FP, LR, R31, ZR,
};
ASSERT(ARRAY_SIZE(kNames) == ARRAY_SIZE(kRegisters));
for (unsigned i = 0; i < ARRAY_SIZE(kNames); i++) {
if (strcmp(kNames[i], name) == 0) {
return kRegisters[i];
}
}
return kNoRegister;
}
bool SimulatorDebugger::GetValue(char* desc, int64_t* value) {
Register reg = LookupCpuRegisterByName(desc);
if (reg != kNoRegister) {
if (reg == ZR) {
*value = 0;
return true;
}
*value = sim_->get_register(reg);
return true;
}
if (desc[0] == '*') {
int64_t addr;
if (GetValue(desc + 1, &addr)) {
if (Simulator::IsIllegalAddress(addr)) {
return false;
}
*value = *(reinterpret_cast<int64_t*>(addr));
return true;
}
}
if (strcmp("pc", desc) == 0) {
*value = sim_->get_pc();
return true;
}
bool retval = SScanF(desc, "0x%"Px64, value) == 1;
if (!retval) {
retval = SScanF(desc, "%"Px64, value) == 1;
}
return retval;
}
void SimulatorDebugger::Debug() {
intptr_t last_pc = -1;
bool done = false;
#define COMMAND_SIZE 63
#define ARG_SIZE 255
#define STR(a) #a
#define XSTR(a) STR(a)
char cmd[COMMAND_SIZE + 1];
char arg1[ARG_SIZE + 1];
char arg2[ARG_SIZE + 1];
// make sure to have a proper terminating character if reaching the limit
cmd[COMMAND_SIZE] = 0;
arg1[ARG_SIZE] = 0;
arg2[ARG_SIZE] = 0;
// TODO(zra): Undo all set breakpoints while running in the debugger shell.
// This will make them invisible to all commands.
// UndoBreakpoints();
while (!done) {
if (last_pc != sim_->get_pc()) {
last_pc = sim_->get_pc();
if (Simulator::IsIllegalAddress(last_pc)) {
OS::Print("pc is out of bounds: 0x%" Px "\n", last_pc);
} else {
Disassembler::Disassemble(last_pc, last_pc + Instr::kInstrSize);
}
}
char* line = ReadLine("sim> ");
if (line == NULL) {
FATAL("ReadLine failed");
} else {
// Use sscanf to parse the individual parts of the command line. At the
// moment no command expects more than two parameters.
int args = SScanF(line,
"%" XSTR(COMMAND_SIZE) "s "
"%" XSTR(ARG_SIZE) "s "
"%" XSTR(ARG_SIZE) "s",
cmd, arg1, arg2);
if ((strcmp(cmd, "h") == 0) || (strcmp(cmd, "help") == 0)) {
OS::Print("c/cont -- continue execution\n"
"disasm -- disassemble instrs at current pc location\n"
" other variants are:\n"
" disasm <address>\n"
" disasm <address> <number_of_instructions>\n"
" by default 10 instrs are disassembled\n"
"gdb -- transfer control to gdb\n"
"h/help -- print this help string\n"
"p/print <reg or value or *addr> -- print integer value\n"
"po/printobject <*reg or *addr> -- print object\n"
"si/stepi -- single step an instruction\n"
"q/quit -- Quit the debugger and exit the program\n");
} else if ((strcmp(cmd, "quit") == 0) || (strcmp(cmd, "q") == 0)) {
OS::Print("Quitting\n");
OS::Exit(0);
} else if ((strcmp(cmd, "si") == 0) || (strcmp(cmd, "stepi") == 0)) {
sim_->InstructionDecode(reinterpret_cast<Instr*>(sim_->get_pc()));
} else if ((strcmp(cmd, "c") == 0) || (strcmp(cmd, "cont") == 0)) {
// Execute the one instruction we broke at with breakpoints disabled.
sim_->InstructionDecode(reinterpret_cast<Instr*>(sim_->get_pc()));
// Leave the debugger shell.
done = true;
} else if ((strcmp(cmd, "p") == 0) || (strcmp(cmd, "print") == 0)) {
if (args == 2) {
int64_t value;
if (GetValue(arg1, &value)) {
OS::Print("%s: %"Pu64" 0x%"Px64"\n", arg1, value, value);
} else {
OS::Print("%s unrecognized\n", arg1);
}
} else {
OS::Print("print <reg or value or *addr>\n");
}
} else if ((strcmp(cmd, "po") == 0) ||
(strcmp(cmd, "printobject") == 0)) {
if (args == 2) {
int64_t value;
// Make the dereferencing '*' optional.
if (((arg1[0] == '*') && GetValue(arg1 + 1, &value)) ||
GetValue(arg1, &value)) {
if (Isolate::Current()->heap()->Contains(value)) {
OS::Print("%s: \n", arg1);
#if defined(DEBUG)
const Object& obj = Object::Handle(
reinterpret_cast<RawObject*>(value));
obj.Print();
#endif // defined(DEBUG)
} else {
OS::Print("0x%"Px64" is not an object reference\n", value);
}
} else {
OS::Print("%s unrecognized\n", arg1);
}
} else {
OS::Print("printobject <*reg or *addr>\n");
}
} else if (strcmp(cmd, "disasm") == 0) {
int64_t start = 0;
int64_t end = 0;
if (args == 1) {
start = sim_->get_pc();
end = start + (10 * Instr::kInstrSize);
} else if (args == 2) {
if (GetValue(arg1, &start)) {
// no length parameter passed, assume 10 instructions
if (Simulator::IsIllegalAddress(start)) {
// If start isn't a valid address, warn and use PC instead
OS::Print("First argument yields invalid address: 0x%"Px64"\n",
start);
OS::Print("Using PC instead");
start = sim_->get_pc();
}
end = start + (10 * Instr::kInstrSize);
}
} else {
int64_t length;
if (GetValue(arg1, &start) && GetValue(arg2, &length)) {
if (Simulator::IsIllegalAddress(start)) {
// If start isn't a valid address, warn and use PC instead
OS::Print("First argument yields invalid address: 0x%"Px64"\n",
start);
OS::Print("Using PC instead\n");
start = sim_->get_pc();
}
end = start + (length * Instr::kInstrSize);
}
}
Disassembler::Disassemble(start, end);
} else if (strcmp(cmd, "gdb") == 0) {
OS::Print("relinquishing control to gdb\n");
OS::DebugBreak();
OS::Print("regaining control from gdb\n");
} else {
OS::Print("Unknown command: %s\n", cmd);
}
}
delete[] line;
}
// TODO(zra): Add all the breakpoints back to stop execution and enter the
// debugger shell when hit.
// RedoBreakpoints();
#undef COMMAND_SIZE
#undef ARG_SIZE
#undef STR
#undef XSTR
}
char* SimulatorDebugger::ReadLine(const char* prompt) {
char* result = NULL;
char line_buf[256];
intptr_t offset = 0;
bool keep_going = true;
OS::Print("%s", prompt);
while (keep_going) {
if (fgets(line_buf, sizeof(line_buf), stdin) == NULL) {
// fgets got an error. Just give up.
if (result != NULL) {
delete[] result;
}
return NULL;
}
intptr_t len = strlen(line_buf);
if (len > 1 &&
line_buf[len - 2] == '\\' &&
line_buf[len - 1] == '\n') {
// When we read a line that ends with a "\" we remove the escape and
// append the remainder.
line_buf[len - 2] = '\n';
line_buf[len - 1] = 0;
len -= 1;
} else if ((len > 0) && (line_buf[len - 1] == '\n')) {
// Since we read a new line we are done reading the line. This
// will exit the loop after copying this buffer into the result.
keep_going = false;
}
if (result == NULL) {
// Allocate the initial result and make room for the terminating '\0'
result = new char[len + 1];
if (result == NULL) {
// OOM, so cannot readline anymore.
return NULL;
}
} else {
// Allocate a new result with enough room for the new addition.
intptr_t new_len = offset + len + 1;
char* new_result = new char[new_len];
if (new_result == NULL) {
// OOM, free the buffer allocated so far and return NULL.
delete[] result;
return NULL;
} else {
// Copy the existing input into the new array and set the new
// array as the result.
memmove(new_result, result, offset);
delete[] result;
result = new_result;
}
}
// Copy the newly read line into the result.
memmove(result + offset, line_buf, len);
offset += len;
}
ASSERT(result != NULL);
result[offset] = '\0';
return result;
}
Simulator::Simulator() {
// Setup simulator support first. Some of this information is needed to
// setup the architecture state.
// We allocate the stack here, the size is computed as the sum of
// the size specified by the user and the buffer space needed for
// handling stack overflow exceptions. To be safe in potential
// stack underflows we also add some underflow buffer space.
stack_ = new char[(Isolate::GetSpecifiedStackSize() +
Isolate::kStackSizeBuffer +
kSimulatorStackUnderflowSize)];
pc_modified_ = false;
icount_ = 0;
break_pc_ = NULL;
break_instr_ = 0;
top_exit_frame_info_ = 0;
// Setup architecture state.
// All registers are initialized to zero to start with.
for (int i = 0; i < kNumberOfCpuRegisters; i++) {
registers_[i] = 0;
}
n_flag_ = false;
z_flag_ = false;
c_flag_ = false;
v_flag_ = false;
// The sp is initialized to point to the bottom (high address) of the
// allocated stack area.
registers_[R31] = StackTop();
// The lr and pc are initialized to a known bad value that will cause an
// access violation if the simulator ever tries to execute it.
registers_[LR] = kBadLR;
pc_ = kBadLR;
}
Simulator::~Simulator() {
delete[] stack_;
Isolate* isolate = Isolate::Current();
if (isolate != NULL) {
isolate->set_simulator(NULL);
}
}
// When the generated code calls an external reference we need to catch that in
// the simulator. The external reference will be a function compiled for the
// host architecture. We need to call that function instead of trying to
// execute it with the simulator. We do that by redirecting the external
// reference to a svc (supervisor call) instruction that is handled by
// the simulator. We write the original destination of the jump just at a known
// offset from the svc instruction so the simulator knows what to call.
class Redirection {
public:
uword address_of_hlt_instruction() {
return reinterpret_cast<uword>(&hlt_instruction_);
}
uword external_function() const { return external_function_; }
Simulator::CallKind call_kind() const { return call_kind_; }
int argument_count() const { return argument_count_; }
static Redirection* Get(uword external_function,
Simulator::CallKind call_kind,
int argument_count) {
Redirection* current;
for (current = list_; current != NULL; current = current->next_) {
if (current->external_function_ == external_function) return current;
}
return new Redirection(external_function, call_kind, argument_count);
}
static Redirection* FromHltInstruction(Instr* hlt_instruction) {
char* addr_of_hlt = reinterpret_cast<char*>(hlt_instruction);
char* addr_of_redirection =
addr_of_hlt - OFFSET_OF(Redirection, hlt_instruction_);
return reinterpret_cast<Redirection*>(addr_of_redirection);
}
private:
static const int32_t kRedirectInstruction = Instr::kRedirectInstruction;
Redirection(uword external_function,
Simulator::CallKind call_kind,
int argument_count)
: external_function_(external_function),
call_kind_(call_kind),
argument_count_(argument_count),
hlt_instruction_(kRedirectInstruction),
next_(list_) {
list_ = this;
}
uword external_function_;
Simulator::CallKind call_kind_;
int argument_count_;
uint32_t hlt_instruction_;
Redirection* next_;
static Redirection* list_;
};
Redirection* Redirection::list_ = NULL;
uword Simulator::RedirectExternalReference(uword function,
CallKind call_kind,
int argument_count) {
Redirection* redirection =
Redirection::Get(function, call_kind, argument_count);
return redirection->address_of_hlt_instruction();
}
// Get the active Simulator for the current isolate.
Simulator* Simulator::Current() {
Simulator* simulator = Isolate::Current()->simulator();
if (simulator == NULL) {
simulator = new Simulator();
Isolate::Current()->set_simulator(simulator);
}
return simulator;
}
// Sets the register in the architecture state.
void Simulator::set_register(Register reg, int64_t value, R31Type r31t) {
// register is in range, and if it is R31, a mode is specified.
ASSERT((reg >= 0) && (reg < kNumberOfCpuRegisters));
if ((reg != R31) || (r31t != R31IsZR)) {
registers_[reg] = value;
}
}
// Get the register from the architecture state.
int64_t Simulator::get_register(Register reg, R31Type r31t) const {
ASSERT((reg >= 0) && (reg < kNumberOfCpuRegisters));
if ((reg == R31) && (r31t == R31IsZR)) {
return 0;
} else {
return registers_[reg];
}
}
void Simulator::set_wregister(Register reg, int32_t value, R31Type r31t) {
ASSERT((reg >= 0) && (reg < kNumberOfCpuRegisters));
// When setting in W mode, clear the high bits.
if ((reg != R31) || (r31t != R31IsZR)) {
registers_[reg] = Utils::LowHighTo64Bits(static_cast<uint32_t>(value), 0);
}
}
// Get the register from the architecture state.
int32_t Simulator::get_wregister(Register reg, R31Type r31t) const {
ASSERT((reg >= 0) && (reg < kNumberOfCpuRegisters));
if ((reg == R31) && (r31t == R31IsZR)) {
return 0;
} else {
return registers_[reg];
}
}
// Raw access to the PC register.
void Simulator::set_pc(int64_t value) {
pc_modified_ = true;
last_pc_ = pc_;
pc_ = value;
}
// Raw access to the pc.
int64_t Simulator::get_pc() const {
return pc_;
}
int64_t Simulator::get_last_pc() const {
return last_pc_;
}
void Simulator::HandleIllegalAccess(uword addr, Instr* instr) {
uword fault_pc = get_pc();
uword last_pc = get_last_pc();
// TODO(zra): drop into debugger.
char buffer[128];
snprintf(buffer, sizeof(buffer),
"illegal memory access at 0x%" Px ", pc=0x%" Px ", last_pc=0x%" Px"\n",
addr, fault_pc, last_pc);
SimulatorDebugger dbg(this);
dbg.Stop(instr, buffer);
// The debugger will return control in non-interactive mode.
FATAL("Cannot continue execution after illegal memory access.");
}
// The ARMv8 manual advises that an unaligned access may generate a fault,
// and if not, will likely take a number of additional cycles to execute,
// so let's just not generate any.
void Simulator::UnalignedAccess(const char* msg, uword addr, Instr* instr) {
char buffer[128];
snprintf(buffer, sizeof(buffer),
"unaligned %s at 0x%" Px ", pc=%p\n", msg, addr, instr);
SimulatorDebugger dbg(this);
dbg.Stop(instr, buffer);
// The debugger will not be able to single step past this instruction, but
// it will be possible to disassemble the code and inspect registers.
FATAL("Cannot continue execution after unaligned access.");
}
void Simulator::UnimplementedInstruction(Instr* instr) {
char buffer[128];
snprintf(buffer, sizeof(buffer),
"Unimplemented instruction: at %p, last_pc=0x%" Px64 "\n",
instr, get_last_pc());
SimulatorDebugger dbg(this);
dbg.Stop(instr, buffer);
FATAL("Cannot continue execution after unimplemented instruction.");
}
// Returns the top of the stack area to enable checking for stack pointer
// validity.
uword Simulator::StackTop() const {
// To be safe in potential stack underflows we leave some buffer above and
// set the stack top.
return reinterpret_cast<uword>(stack_) +
(Isolate::GetSpecifiedStackSize() + Isolate::kStackSizeBuffer);
}
intptr_t Simulator::ReadX(uword addr, Instr* instr) {
if ((addr & 7) == 0) {
intptr_t* ptr = reinterpret_cast<intptr_t*>(addr);
return *ptr;
}
UnalignedAccess("read", addr, instr);
return 0;
}
void Simulator::WriteX(uword addr, intptr_t value, Instr* instr) {
if ((addr & 7) == 0) {
intptr_t* ptr = reinterpret_cast<intptr_t*>(addr);
*ptr = value;
return;
}
UnalignedAccess("write", addr, instr);
}
uint32_t Simulator::ReadWU(uword addr, Instr* instr) {
if ((addr & 3) == 0) {
uint32_t* ptr = reinterpret_cast<uint32_t*>(addr);
return *ptr;
}
UnalignedAccess("read unsigned single word", addr, instr);
return 0;
}
int32_t Simulator::ReadW(uword addr, Instr* instr) {
if ((addr & 3) == 0) {
int32_t* ptr = reinterpret_cast<int32_t*>(addr);
return *ptr;
}
UnalignedAccess("read single word", addr, instr);
return 0;
}
void Simulator::WriteW(uword addr, uint32_t value, Instr* instr) {
if ((addr & 3) == 0) {
uint32_t* ptr = reinterpret_cast<uint32_t*>(addr);
*ptr = value;
return;
}
UnalignedAccess("write single word", addr, instr);
}
uint16_t Simulator::ReadHU(uword addr, Instr* instr) {
if ((addr & 1) == 0) {
uint16_t* ptr = reinterpret_cast<uint16_t*>(addr);
return *ptr;
}
UnalignedAccess("unsigned halfword read", addr, instr);
return 0;
}
int16_t Simulator::ReadH(uword addr, Instr* instr) {
if ((addr & 1) == 0) {
int16_t* ptr = reinterpret_cast<int16_t*>(addr);
return *ptr;
}
UnalignedAccess("signed halfword read", addr, instr);
return 0;
}
void Simulator::WriteH(uword addr, uint16_t value, Instr* instr) {
if ((addr & 1) == 0) {
uint16_t* ptr = reinterpret_cast<uint16_t*>(addr);
*ptr = value;
return;
}
UnalignedAccess("halfword write", addr, instr);
}
uint8_t Simulator::ReadBU(uword addr) {
uint8_t* ptr = reinterpret_cast<uint8_t*>(addr);
return *ptr;
}
int8_t Simulator::ReadB(uword addr) {
int8_t* ptr = reinterpret_cast<int8_t*>(addr);
return *ptr;
}
void Simulator::WriteB(uword addr, uint8_t value) {
uint8_t* ptr = reinterpret_cast<uint8_t*>(addr);
*ptr = value;
}
// Unsupported instructions use Format to print an error and stop execution.
void Simulator::Format(Instr* instr, const char* format) {
OS::Print("Simulator found unsupported instruction:\n 0x%p: %s\n",
instr,
format);
UNIMPLEMENTED();
}
// Calculate and set the Negative and Zero flags.
void Simulator::SetNZFlagsW(int32_t val) {
n_flag_ = (val < 0);
z_flag_ = (val == 0);
}
// Calculate C flag value for additions.
bool Simulator::CarryFromW(int32_t left, int32_t right) {
uint32_t uleft = static_cast<uint32_t>(left);
uint32_t uright = static_cast<uint32_t>(right);
uint32_t urest = 0xffffffffU - uleft;
return (uright > urest);
}
// Calculate C flag value for subtractions.
bool Simulator::BorrowFromW(int32_t left, int32_t right) {
uint32_t uleft = static_cast<uint32_t>(left);
uint32_t uright = static_cast<uint32_t>(right);
return (uright > uleft);
}
// Calculate V flag value for additions and subtractions.
bool Simulator::OverflowFromW(int32_t alu_out,
int32_t left, int32_t right, bool addition) {
bool overflow;
if (addition) {
// operands have the same sign
overflow = ((left >= 0 && right >= 0) || (left < 0 && right < 0))
// and operands and result have different sign
&& ((left < 0 && alu_out >= 0) || (left >= 0 && alu_out < 0));
} else {
// operands have different signs
overflow = ((left < 0 && right >= 0) || (left >= 0 && right < 0))
// and first operand and result have different signs
&& ((left < 0 && alu_out >= 0) || (left >= 0 && alu_out < 0));
}
return overflow;
}
// Calculate and set the Negative and Zero flags.
void Simulator::SetNZFlagsX(int64_t val) {
n_flag_ = (val < 0);
z_flag_ = (val == 0);
}
// Calculate C flag value for additions.
bool Simulator::CarryFromX(int64_t left, int64_t right) {
uint64_t uleft = static_cast<uint64_t>(left);
uint64_t uright = static_cast<uint64_t>(right);
uint64_t urest = 0xffffffffffffffffULL - uleft;
return (uright > urest);
}
// Calculate C flag value for subtractions.
bool Simulator::BorrowFromX(int64_t left, int64_t right) {
uint64_t uleft = static_cast<uint64_t>(left);
uint64_t uright = static_cast<uint64_t>(right);
return (uright > uleft);
}
// Calculate V flag value for additions and subtractions.
bool Simulator::OverflowFromX(int64_t alu_out,
int64_t left, int64_t right, bool addition) {
bool overflow;
if (addition) {
// operands have the same sign
overflow = ((left >= 0 && right >= 0) || (left < 0 && right < 0))
// and operands and result have different sign
&& ((left < 0 && alu_out >= 0) || (left >= 0 && alu_out < 0));
} else {
// operands have different signs
overflow = ((left < 0 && right >= 0) || (left >= 0 && right < 0))
// and first operand and result have different signs
&& ((left < 0 && alu_out >= 0) || (left >= 0 && alu_out < 0));
}
return overflow;
}
// Set the Carry flag.
void Simulator::SetCFlag(bool val) {
c_flag_ = val;
}
// Set the oVerflow flag.
void Simulator::SetVFlag(bool val) {
v_flag_ = val;
}
void Simulator::DecodeMoveWide(Instr* instr) {
const Register rd = instr->RdField();
const int hw = instr->HWField();
const int64_t shift = hw << 4;
const int64_t shifted_imm =
static_cast<uint64_t>(instr->Imm16Field()) << shift;
if (instr->SFField()) {
if (instr->Bits(29, 2) == 0) {
// Format(instr, "movn'sf 'rd, 'imm16 'hw");
set_register(rd, ~shifted_imm, instr->RdMode());
} else if (instr->Bits(29, 2) == 2) {
// Format(instr, "movz'sf 'rd, 'imm16 'hw");
set_register(rd, shifted_imm, instr->RdMode());
} else if (instr->Bits(29, 2) == 3) {
// Format(instr, "movk'sf 'rd, 'imm16 'hw");
const int64_t rd_val = get_register(rd, instr->RdMode());
const int64_t result = (rd_val & ~(0xffffL << shift)) | shifted_imm;
set_register(rd, result, instr->RdMode());
} else {
UnimplementedInstruction(instr);
}
} else if ((hw & 0x2) == 0) {
if (instr->Bits(29, 2) == 0) {
// Format(instr, "movn'sf 'rd, 'imm16 'hw");
set_wregister(rd, ~shifted_imm & kWRegMask, instr->RdMode());
} else if (instr->Bits(29, 2) == 2) {
// Format(instr, "movz'sf 'rd, 'imm16 'hw");
set_wregister(rd, shifted_imm & kWRegMask, instr->RdMode());
} else if (instr->Bits(29, 2) == 3) {
// Format(instr, "movk'sf 'rd, 'imm16 'hw");
const int32_t rd_val = get_wregister(rd, instr->RdMode());
const int32_t result = (rd_val & ~(0xffffL << shift)) | shifted_imm;
set_wregister(rd, result, instr->RdMode());
} else {
UnimplementedInstruction(instr);
}
} else {
// Dest is 32 bits, but shift is more than 32.
UnimplementedInstruction(instr);
}
}
void Simulator::DecodeAddSubImm(Instr* instr) {
bool addition = (instr->Bit(30) == 0);
// Format(instr, "addi'sf's 'rd, 'rn, 'imm12s");
// Format(instr, "subi'sf's 'rd, 'rn, 'imm12s");
const Register rd = instr->RdField();
const Register rn = instr->RnField();
const uint32_t imm = (instr->Bit(22) == 1) ? (instr->Imm12Field() << 12)
: (instr->Imm12Field());
if (instr->SFField()) {
// 64-bit add.
const int64_t rn_val = get_register(rn, instr->RnMode());
const int64_t alu_out = addition ? (rn_val + imm) : (rn_val - imm);
set_register(rd, alu_out, instr->RdMode());
if (instr->HasS()) {
SetNZFlagsX(alu_out);
SetCFlag(CarryFromX(rn_val, imm));
SetVFlag(OverflowFromX(alu_out, rn_val, imm, addition));
}
} else {
// 32-bit add.
const int32_t rn_val = get_wregister(rn, instr->RnMode());
const int32_t alu_out = addition ? (rn_val + imm) : (rn_val - imm);
set_wregister(rd, alu_out, instr->RdMode());
if (instr->HasS()) {
SetNZFlagsW(alu_out);
SetCFlag(CarryFromW(rn_val, imm));
SetVFlag(OverflowFromW(alu_out, rn_val, imm, addition));
}
}
}
void Simulator::DecodeLogicalImm(Instr* instr) {
const int op = instr->Bits(29, 2);
const bool set_flags = op == 3;
const int out_size = ((instr->SFField() == 0) && (instr->NField() == 0))
? kWRegSizeInBits : kXRegSizeInBits;
const Register rn = instr->RnField();
const Register rd = instr->RdField();
const int64_t rn_val = get_register(rn, instr->RnMode());
const uint64_t imm = instr->ImmLogical();
if (imm == 0) {
UnimplementedInstruction(instr);
}
int64_t alu_out = 0;
switch (op) {
case 0:
alu_out = rn_val & imm;
break;
case 1:
alu_out = rn_val | imm;
break;
case 2:
alu_out = rn_val ^ imm;
break;
case 3:
alu_out = rn_val & imm;
break;
default:
UNREACHABLE();
break;
}
if (set_flags) {
if (out_size == kXRegSizeInBits) {
SetNZFlagsX(alu_out);
} else {
SetNZFlagsW(alu_out);
}
SetCFlag(false);
SetVFlag(false);
}
if (out_size == kXRegSizeInBits) {
set_register(rd, alu_out, instr->RdMode());
} else {
set_wregister(rd, alu_out, instr->RdMode());
}
}
void Simulator::DecodePCRel(Instr* instr) {
const int op = instr->Bit(31);
if (op == 0) {
// Format(instr, "adr 'rd, 'pcrel")
const Register rd = instr->RdField();
const int64_t immhi = instr->SImm19Field();
const int64_t immlo = instr->Bits(29, 2);
const int64_t off = (immhi << 2) | immlo;
const int64_t dest = get_pc() + off;
set_register(rd, dest, instr->RdMode());
} else {
UnimplementedInstruction(instr);
}
}
void Simulator::DecodeDPImmediate(Instr* instr) {
if (instr->IsMoveWideOp()) {
DecodeMoveWide(instr);
} else if (instr->IsAddSubImmOp()) {
DecodeAddSubImm(instr);
} else if (instr->IsLogicalImmOp()) {
DecodeLogicalImm(instr);
} else if (instr->IsPCRelOp()) {
DecodePCRel(instr);
} else {
UnimplementedInstruction(instr);
}
}
void Simulator::DecodeCompareAndBranch(Instr* instr) {
const int op = instr->Bit(24);
const Register rt = instr->RtField();
const int64_t imm19 = instr->SImm19Field();
const int64_t dest = get_pc() + (imm19 << 2);
const int64_t mask = instr->SFField() == 1 ? kXRegMask : kWRegMask;
const int64_t rt_val = get_register(rt, R31IsZR) & mask;
if (op == 0) {
// Format(instr, "cbz'sf 'rt, 'dest19");
if (rt_val == 0) {
set_pc(dest);
}
} else {
// Format(instr, "cbnz'sf 'rt, 'dest19");
if (rt_val != 0) {
set_pc(dest);
}
}
}
bool Simulator::ConditionallyExecute(Instr* instr) {
Condition cond;
if (instr->IsConditionalSelectOp()) {
cond = instr->SelectConditionField();
} else {
cond = instr->ConditionField();
}
switch (cond) {
case EQ: return z_flag_;
case NE: return !z_flag_;
case CS: return c_flag_;
case CC: return !c_flag_;
case MI: return n_flag_;
case PL: return !n_flag_;
case VS: return v_flag_;
case VC: return !v_flag_;
case HI: return c_flag_ && !z_flag_;
case LS: return !c_flag_ || z_flag_;
case GE: return n_flag_ == v_flag_;
case LT: return n_flag_ != v_flag_;
case GT: return !z_flag_ && (n_flag_ == v_flag_);
case LE: return z_flag_ || (n_flag_ != v_flag_);
case AL: return true;
default: UNREACHABLE();
}
return false;
}
void Simulator::DecodeConditionalBranch(Instr* instr) {
// Format(instr, "b'cond 'dest19");
if ((instr->Bit(24) != 0) || (instr->Bit(4) != 0)) {
UnimplementedInstruction(instr);
}
const int64_t imm19 = instr->SImm19Field();
const int64_t dest = get_pc() + (imm19 << 2);
if (ConditionallyExecute(instr)) {
set_pc(dest);
}
}
// Calls into the Dart runtime are based on this interface.
typedef void (*SimulatorRuntimeCall)(NativeArguments arguments);
// Calls to leaf Dart runtime functions are based on this interface.
typedef int32_t (*SimulatorLeafRuntimeCall)(
int64_t r0, int64_t r1, int64_t r2, int64_t r3,
int64_t r4, int64_t r5, int64_t r6, int64_t r7);
// Calls to leaf float Dart runtime functions are based on this interface.
typedef double (*SimulatorLeafFloatRuntimeCall)(
double d0, double d1, double d2, double d3,
double d4, double d5, double d6, double d7);
// Calls to native Dart functions are based on this interface.
typedef void (*SimulatorBootstrapNativeCall)(NativeArguments* arguments);
typedef void (*SimulatorNativeCall)(NativeArguments* arguments, uword target);
void Simulator::DoRedirectedCall(Instr* instr) {
SimulatorSetjmpBuffer buffer(this);
if (!setjmp(buffer.buffer_)) {
int64_t saved_lr = get_register(LR);
Redirection* redirection = Redirection::FromHltInstruction(instr);
uword external = redirection->external_function();
if (FLAG_trace_sim) {
OS::Print("Call to host function at 0x%" Pd "\n", external);
}
if ((redirection->call_kind() == kRuntimeCall) ||
(redirection->call_kind() == kBootstrapNativeCall) ||
(redirection->call_kind() == kNativeCall)) {
// Set the top_exit_frame_info of this simulator to the native stack.
set_top_exit_frame_info(reinterpret_cast<uword>(&buffer));
}
if (redirection->call_kind() == kRuntimeCall) {
NativeArguments arguments;
ASSERT(sizeof(NativeArguments) == 4*kWordSize);
arguments.isolate_ = reinterpret_cast<Isolate*>(get_register(R0));
arguments.argc_tag_ = get_register(R1);
arguments.argv_ = reinterpret_cast<RawObject*(*)[]>(get_register(R2));
arguments.retval_ = reinterpret_cast<RawObject**>(get_register(R3));
SimulatorRuntimeCall target =
reinterpret_cast<SimulatorRuntimeCall>(external);
target(arguments);
set_register(R0, icount_); // Zap result register from void function.
set_register(R1, icount_);
} else if (redirection->call_kind() == kLeafRuntimeCall) {
ASSERT((0 <= redirection->argument_count()) &&
(redirection->argument_count() <= 8));
int64_t r0 = get_register(R0);
int64_t r1 = get_register(R1);
int64_t r2 = get_register(R2);
int64_t r3 = get_register(R3);
int64_t r4 = get_register(R4);
int64_t r5 = get_register(R5);
int64_t r6 = get_register(R6);
int64_t r7 = get_register(R7);
SimulatorLeafRuntimeCall target =
reinterpret_cast<SimulatorLeafRuntimeCall>(external);
r0 = target(r0, r1, r2, r3, r4, r5, r6, r7);
set_register(R0, r0); // Set returned result from function.
set_register(R1, icount_); // Zap unused result register.
} else if (redirection->call_kind() == kLeafFloatRuntimeCall) {
// TODO(zra): leaf float runtime calls.
UNIMPLEMENTED();
} else if (redirection->call_kind() == kBootstrapNativeCall) {
NativeArguments* arguments;
arguments = reinterpret_cast<NativeArguments*>(get_register(R0));
SimulatorBootstrapNativeCall target =
reinterpret_cast<SimulatorBootstrapNativeCall>(external);
target(arguments);
set_register(R0, icount_); // Zap result register from void function.
} else {
ASSERT(redirection->call_kind() == kNativeCall);
NativeArguments* arguments;
arguments = reinterpret_cast<NativeArguments*>(get_register(R0));
uword target_func = get_register(R1);
SimulatorNativeCall target =
reinterpret_cast<SimulatorNativeCall>(external);
target(arguments, target_func);
set_register(R0, icount_); // Zap result register from void function.
set_register(R1, icount_);
}
set_top_exit_frame_info(0);
// Zap caller-saved registers, since the actual runtime call could have
// used them.
set_register(R2, icount_);
set_register(R3, icount_);
set_register(R4, icount_);
set_register(R5, icount_);
set_register(R6, icount_);
set_register(R7, icount_);
set_register(R8, icount_);
set_register(R9, icount_);
set_register(R10, icount_);
set_register(R11, icount_);
set_register(R12, icount_);
set_register(R13, icount_);
set_register(R14, icount_);
set_register(R15, icount_);
set_register(IP0, icount_);
set_register(IP1, icount_);
set_register(R18, icount_);
set_register(LR, icount_);
// TODO(zra): Zap caller-saved fpu registers.
// Return.
set_pc(saved_lr);
} else {
// Coming via long jump from a throw. Continue to exception handler.
set_top_exit_frame_info(0);
}
}
void Simulator::DecodeExceptionGen(Instr* instr) {
if ((instr->Bits(0, 2) == 1) && (instr->Bits(2, 3) == 0) &&
(instr->Bits(21, 3) == 0)) {
// Format(instr, "svc 'imm16");
UnimplementedInstruction(instr);
} else if ((instr->Bits(0, 2) == 0) && (instr->Bits(2, 3) == 0) &&
(instr->Bits(21, 3) == 1)) {
// Format(instr, "brk 'imm16");
UnimplementedInstruction(instr);
} else if ((instr->Bits(0, 2) == 0) && (instr->Bits(2, 3) == 0) &&
(instr->Bits(21, 3) == 2)) {
// Format(instr, "hlt 'imm16");
uint16_t imm = static_cast<uint16_t>(instr->Imm16Field());
if (imm == kImmExceptionIsDebug) {
SimulatorDebugger dbg(this);
const char* message = *reinterpret_cast<const char**>(
reinterpret_cast<intptr_t>(instr) - 2 * Instr::kInstrSize);
set_pc(get_pc() + Instr::kInstrSize);
dbg.Stop(instr, message);
} else if (imm == kImmExceptionIsPrintf) {
const char* message = *reinterpret_cast<const char**>(
reinterpret_cast<intptr_t>(instr) - 2 * Instr::kInstrSize);
OS::Print("Simulator hit: %s", message);
} else if (imm == kImmExceptionIsRedirectedCall) {
DoRedirectedCall(instr);
} else {
UnimplementedInstruction(instr);
}
}
}
void Simulator::DecodeSystem(Instr* instr) {
if ((instr->Bits(0, 8) == 0x5f) && (instr->Bits(12, 4) == 2) &&
(instr->Bits(16, 3) == 3) && (instr->Bits(19, 2) == 0) &&
(instr->Bit(21) == 0)) {
if (instr->Bits(8, 4) == 0) {
// Format(instr, "nop");
} else {
UnimplementedInstruction(instr);
}
} else {
UnimplementedInstruction(instr);
}
}
void Simulator::DecodeTestAndBranch(Instr* instr) {
const int op = instr->Bit(24);
const int bitpos = instr->Bits(19, 4) | (instr->Bit(31) << 5);
const int64_t imm14 = instr->SImm14Field();
const int64_t dest = get_pc() + (imm14 << 2);
const Register rt = instr->RtField();
const int64_t rt_val = get_register(rt, R31IsZR);
if (op == 0) {
// Format(instr, "tbz'sf 'rt, 'bitpos, 'dest14");
if ((rt_val & (1 << bitpos)) == 0) {
set_pc(dest);
}
} else {
// Format(instr, "tbnz'sf 'rt, 'bitpos, 'dest14");
if ((rt_val & (1 << bitpos)) != 0) {
set_pc(dest);
}
}
}
void Simulator::DecodeUnconditionalBranch(Instr* instr) {
const bool link = instr->Bit(31) == 1;
const int64_t imm26 = instr->SImm26Field();
const int64_t dest = get_pc() + (imm26 << 2);
const int64_t ret = get_pc() + Instr::kInstrSize;
set_pc(dest);
if (link) {
set_register(LR, ret);
}
}
void Simulator::DecodeUnconditionalBranchReg(Instr* instr) {
if ((instr->Bits(0, 5) == 0) && (instr->Bits(10, 6) == 0) &&
(instr->Bits(16, 5) == 0x1f)) {
switch (instr->Bits(21, 4)) {
case 0: {
// Format(instr, "br 'rn");
const Register rn = instr->RnField();
const int64_t dest = get_register(rn, instr->RnMode());
set_pc(dest);
break;
}
case 1: {
// Format(instr, "blr 'rn");
const Register rn = instr->RnField();
const int64_t dest = get_register(rn, instr->RnMode());
const int64_t ret = get_pc() + Instr::kInstrSize;
set_pc(dest);
set_register(LR, ret);
break;
}
case 2: {
// Format(instr, "ret 'rn");
const Register rn = instr->RnField();
const int64_t rn_val = get_register(rn, instr->RnMode());
set_pc(rn_val);
break;
}
default:
UnimplementedInstruction(instr);
break;
}
} else {
UnimplementedInstruction(instr);
}
}
void Simulator::DecodeCompareBranch(Instr* instr) {
if (instr->IsCompareAndBranchOp()) {
DecodeCompareAndBranch(instr);
} else if (instr->IsConditionalBranchOp()) {
DecodeConditionalBranch(instr);
} else if (instr->IsExceptionGenOp()) {
DecodeExceptionGen(instr);
} else if (instr->IsSystemOp()) {
DecodeSystem(instr);
} else if (instr->IsTestAndBranchOp()) {
DecodeTestAndBranch(instr);
} else if (instr->IsUnconditionalBranchOp()) {
DecodeUnconditionalBranch(instr);
} else if (instr->IsUnconditionalBranchRegOp()) {
DecodeUnconditionalBranchReg(instr);
} else {
UnimplementedInstruction(instr);
}
}
void Simulator::DecodeLoadStoreReg(Instr* instr) {
// TODO(zra): SIMD loads and stores have bit 26 (V) set.
// (bit 25 is never set for loads and stores).
if (instr->Bits(25, 2) != 0) {
UnimplementedInstruction(instr);
return;
}
// Calculate the address.
const Register rn = instr->RnField();
const Register rt = instr->RtField();
const int64_t rn_val = get_register(rn, R31IsSP);
const uint32_t size = instr->SzField();
uword address = 0;
uword wb_address = 0;
bool wb = false;
if (instr->Bit(24) == 1) {
// addr = rn + scaled unsigned 12-bit immediate offset.
const uint32_t imm12 = static_cast<uint32_t>(instr->Imm12Field());
const uint32_t offset = imm12 << size;
address = rn_val + offset;
} else if (instr->Bits(10, 2) == 0) {
// addr = rn + signed 9-bit immediate offset.
wb = false;
const int64_t offset = static_cast<int64_t>(instr->SImm9Field());
address = rn_val + offset;
wb_address = rn_val;
} else if (instr->Bit(10) == 1) {
// addr = rn + signed 9-bit immediate offset.
wb = true;
const int64_t offset = static_cast<int64_t>(instr->SImm9Field());
if (instr->Bit(11) == 1) {
// Pre-index.
address = rn_val + offset;
wb_address = address;
} else {
// Post-index.
address = rn_val;
wb_address = rn_val + offset;
}
} else if (instr->Bits(10, 2) == 2) {
// addr = rn + (rm EXT optionally scaled by operand instruction size).
const Register rm = instr->RmField();
const Extend ext = instr->ExtendTypeField();
const uint8_t scale =
(ext == UXTX) && (instr->Bit(12) == 1) ? size : 0;
const int64_t rm_val = get_register(rm, R31IsZR);
const int64_t offset = ExtendOperand(kXRegSizeInBits, rm_val, ext, scale);
address = rn_val + offset;
} else {
UnimplementedInstruction(instr);
}
// Check the address.
if (IsIllegalAddress(address)) {
HandleIllegalAccess(address, instr);
return;
}
// Do access.
if (instr->Bits(22, 2) == 0) {
// Format(instr, "str'sz 'rt, 'memop");
int32_t rt_val32 = get_wregister(rt, R31IsZR);
switch (size) {
case 0: {
uint8_t val = static_cast<uint8_t>(rt_val32);
WriteB(address, val);
break;
}
case 1: {
uint16_t val = static_cast<uint16_t>(rt_val32);
WriteH(address, val, instr);
break;
}
case 2: {
uint32_t val = static_cast<uint32_t>(rt_val32);
WriteW(address, val, instr);
break;
}
case 3: {
int64_t val = get_register(rt, R31IsZR);
WriteX(address, val, instr);
break;
}
default:
UNREACHABLE();
break;
}
} else {
// Format(instr, "ldr'sz 'rt, 'memop");
// Undefined case.
if ((size == 3) && (instr->Bits(22, 0) == 3)) {
UnimplementedInstruction(instr);
return;
}
// Read the value.
const bool signd = instr->Bit(23) == 1;
// Write the W register for signed values when size < 2.
// Write the W register for unsigned values when size == 2.
const bool use_w =
(signd && (instr->Bit(22) == 1)) || (!signd && (size == 2));
int64_t val = 0; // Sign extend into an int64_t.
switch (size) {
case 0: {
if (signd) {
val = static_cast<int64_t>(ReadB(address));
} else {
val = static_cast<int64_t>(ReadBU(address));
}
break;
}
case 1: {
if (signd) {
val = static_cast<int64_t>(ReadH(address, instr));
} else {
val = static_cast<int64_t>(ReadHU(address, instr));
}
break;
}
case 2: {
if (signd) {
val = static_cast<int64_t>(ReadW(address, instr));
} else {
val = static_cast<int64_t>(ReadWU(address, instr));
}
break;
}
case 3:
val = ReadX(address, instr);
break;
default:
UNREACHABLE();
break;
}
// Write to register.
if (use_w) {
set_wregister(rt, static_cast<int32_t>(val), R31IsZR);
} else {
set_register(rt, val, R31IsZR);
}
}
// Do writeback.
if (wb) {
set_register(rn, wb_address, R31IsSP);
}
}
void Simulator::DecodeLoadRegLiteral(Instr* instr) {
if ((instr->Bit(31) != 0) || (instr->Bit(29) != 0) ||
(instr->Bits(24, 3) != 0)) {
UnimplementedInstruction(instr);
}
const Register rt = instr->RtField();
const int64_t off = instr->SImm19Field() << 2;
const int64_t pc = reinterpret_cast<int64_t>(instr);
const int64_t address = pc + off;
const int64_t val = ReadX(address, instr);
if (instr->Bit(30)) {
// Format(instr, "ldrx 'rt, 'pcldr");
set_register(rt, val, R31IsZR);
} else {
// Format(instr, "ldrw 'rt, 'pcldr");
set_wregister(rt, static_cast<int32_t>(val), R31IsZR);
}
}
void Simulator::DecodeLoadStore(Instr* instr) {
if (instr->IsLoadStoreRegOp()) {
DecodeLoadStoreReg(instr);
} else if (instr->IsLoadRegLiteralOp()) {
DecodeLoadRegLiteral(instr);
} else {
UnimplementedInstruction(instr);
}
}
int64_t Simulator::ShiftOperand(uint8_t reg_size,
int64_t value,
Shift shift_type,
uint8_t amount) {
if (amount == 0) {
return value;
}
int64_t mask = reg_size == kXRegSizeInBits ? kXRegMask : kWRegMask;
switch (shift_type) {
case LSL:
return (value << amount) & mask;
case LSR:
return static_cast<uint64_t>(value) >> amount;
case ASR: {
// Shift used to restore the sign.
uint8_t s_shift = kXRegSizeInBits - reg_size;
// Value with its sign restored.
int64_t s_value = (value << s_shift) >> s_shift;
return (s_value >> amount) & mask;
}
case ROR: {
if (reg_size == kWRegSizeInBits) {
value &= kWRegMask;
}
return (static_cast<uint64_t>(value) >> amount) |
((value & ((1L << amount) - 1L)) << (reg_size - amount));
}
default:
UNIMPLEMENTED();
return 0;
}
}
int64_t Simulator::ExtendOperand(uint8_t reg_size,
int64_t value,
Extend extend_type,
uint8_t amount) {
switch (extend_type) {
case UXTB:
value &= 0xff;
break;
case UXTH:
value &= 0xffff;
break;
case UXTW:
value &= 0xffffffff;
break;
case SXTB:
value = (value << 56) >> 56;
break;
case SXTH:
value = (value << 48) >> 48;
break;
case SXTW:
value = (value << 32) >> 32;
break;
case UXTX:
case SXTX:
break;
default:
UNREACHABLE();
break;
}
int64_t mask = (reg_size == kXRegSizeInBits) ? kXRegMask : kWRegMask;
return (value << amount) & mask;
}
int64_t Simulator::DecodeShiftExtendOperand(Instr* instr) {
const Register rm = instr->RmField();
const int64_t rm_val = get_register(rm, R31IsZR);
const uint8_t size = instr->SFField() ? kXRegSizeInBits : kWRegSizeInBits;
if (instr->IsShift()) {
const Shift shift_type = instr->ShiftTypeField();
const uint8_t shift_amount = instr->Imm6Field();
return ShiftOperand(size, rm_val, shift_type, shift_amount);
} else {
ASSERT(instr->IsExtend());
const Extend extend_type = instr->ExtendTypeField();
const uint8_t shift_amount = instr->Imm3Field();
return ExtendOperand(size, rm_val, extend_type, shift_amount);
}
UNREACHABLE();
return -1;
}
void Simulator::DecodeAddSubShiftExt(Instr* instr) {
// Format(instr, "add'sf's 'rd, 'rn, 'shift_op");
// also, sub, cmp, etc.
const bool subtract = instr->Bit(30) == 1;
const Register rd = instr->RdField();
const Register rn = instr->RnField();
const int64_t rm_val = DecodeShiftExtendOperand(instr);
if (instr->SFField()) {
// 64-bit add.
const int64_t rn_val = get_register(rn, instr->RnMode());
int64_t alu_out = 0;
if (subtract) {
alu_out = rn_val - rm_val;
} else {
alu_out = rn_val + rm_val;
}
set_register(rd, alu_out, instr->RdMode());
if (instr->HasS()) {
SetNZFlagsX(alu_out);
SetCFlag(CarryFromX(rn_val, rm_val));
SetVFlag(OverflowFromX(alu_out, rn_val, rm_val, !subtract));
}
} else {
// 32-bit add.
const int32_t rn_val = get_wregister(rn, instr->RnMode());
const int32_t rm_val32 = static_cast<int32_t>(rm_val & kWRegMask);
int32_t alu_out = 0;
if (subtract) {
alu_out = rn_val - rm_val32;
} else {
alu_out = rn_val + rm_val32;
}
set_wregister(rd, alu_out, instr->RdMode());
if (instr->HasS()) {
SetNZFlagsW(alu_out);
SetCFlag(CarryFromW(rn_val, rm_val32));
SetVFlag(OverflowFromW(alu_out, rn_val, rm_val32, !subtract));
}
}
}
void Simulator::DecodeLogicalShift(Instr* instr) {
const int op = (instr->Bits(29, 2) << 1) | instr->Bit(21);
const Register rd = instr->RdField();
const Register rn = instr->RnField();
const int64_t rn_val = get_register(rn, instr->RnMode());
const int64_t rm_val = DecodeShiftExtendOperand(instr);
int64_t alu_out = 0;
switch (op) {
case 0:
// Format(instr, "and'sf 'rd, 'rn, 'shift_op");
alu_out = rn_val & rm_val;
break;
case 1:
// Format(instr, "bic'sf 'rd, 'rn, 'shift_op");
alu_out = rn_val & (~rm_val);
break;
case 2:
// Format(instr, "orr'sf 'rd, 'rn, 'shift_op");
alu_out = rn_val | rm_val;
break;
case 3:
// Format(instr, "orn'sf 'rd, 'rn, 'shift_op");
alu_out = rn_val | (~rm_val);
break;
case 4:
// Format(instr, "eor'sf 'rd, 'rn, 'shift_op");
alu_out = rn_val ^ rm_val;
break;
case 5:
// Format(instr, "eon'sf 'rd, 'rn, 'shift_op");
alu_out = rn_val ^ (~rm_val);
break;
case 6:
// Format(instr, "and'sfs 'rd, 'rn, 'shift_op");
alu_out = rn_val & rm_val;
break;
case 7:
// Format(instr, "bic'sfs 'rd, 'rn, 'shift_op");
alu_out = rn_val & (~rm_val);
break;
default:
UNREACHABLE();
break;
}
// Set flags if ands or bics.
if ((op == 6) || (op == 7)) {
if (instr->SFField() == 1) {
SetNZFlagsX(alu_out);
} else {
SetNZFlagsW(alu_out);
}
SetCFlag(false);
SetVFlag(false);
}
if (instr->SFField() == 1) {
set_register(rd, alu_out, instr->RdMode());
} else {
set_wregister(rd, alu_out & kWRegMask, instr->RdMode());
}
}
static int64_t divide64(int64_t top, int64_t bottom, bool signd) {
// ARM64 does not trap on integer division by zero. The destination register
// is instead set to 0.
if (bottom == 0) {
return 0;
}
if (signd) {
// INT_MIN / -1 = INT_MIN.
if ((top == static_cast<int64_t>(0x8000000000000000LL)) &&
(bottom == static_cast<int64_t>(0xffffffffffffffffLL))) {
return static_cast<int64_t>(0x8000000000000000LL);
} else {
return top / bottom;
}
} else {
const uint64_t utop = static_cast<uint64_t>(top);
const uint64_t ubottom = static_cast<uint64_t>(bottom);
return static_cast<int64_t>(utop / ubottom);
}
}
static int32_t divide32(int32_t top, int32_t bottom, bool signd) {
// ARM64 does not trap on integer division by zero. The destination register
// is instead set to 0.
if (bottom == 0) {
return 0;
}
if (signd) {
// INT_MIN / -1 = INT_MIN.
if ((top == static_cast<int32_t>(0x80000000)) &&
(bottom == static_cast<int32_t>(0xffffffff))) {
return static_cast<int32_t>(0x80000000);
} else {
return top / bottom;
}
} else {
const uint32_t utop = static_cast<uint32_t>(top);
const uint32_t ubottom = static_cast<uint32_t>(bottom);
return static_cast<int32_t>(utop / ubottom);
}
}
void Simulator::DecodeMiscDP2Source(Instr* instr) {
if (instr->Bit(29) != 0) {
UnimplementedInstruction(instr);
}
const Register rd = instr->RdField();
const Register rn = instr->RnField();
const Register rm = instr->RmField();
const int op = instr->Bits(10, 6);
const int64_t rn_val64 = get_register(rn, R31IsZR);
const int64_t rm_val64 = get_register(rm, R31IsZR);
const int32_t rn_val32 = get_wregister(rn, R31IsZR);
const int32_t rm_val32 = get_wregister(rm, R31IsZR);
switch (op) {
case 2:
case 3: {
// Format(instr, "udiv'sf 'rd, 'rn, 'rm");
// Format(instr, "sdiv'sf 'rd, 'rn, 'rm");
const bool signd = instr->Bit(10) == 1;
if (instr->SFField() == 1) {
set_register(rd, divide64(rn_val64, rm_val64, signd), R31IsZR);
} else {
set_wregister(rd, divide32(rn_val32, rm_val32, signd), R31IsZR);
}
break;
}
case 8: {
// Format(instr, "lsl'sf 'rd, 'rn, 'rm");
if (instr->SFField() == 1) {
const int64_t alu_out = rn_val64 << (rm_val64 & (kXRegSizeInBits - 1));
set_register(rd, alu_out, R31IsZR);
} else {
const int32_t alu_out = rn_val32 << (rm_val32 & (kXRegSizeInBits - 1));
set_wregister(rd, alu_out, R31IsZR);
}
break;
}
case 9: {
// Format(instr, "lsr'sf 'rd, 'rn, 'rm");
if (instr->SFField() == 1) {
const uint64_t rn_u64 = static_cast<uint64_t>(rn_val64);
const int64_t alu_out = rn_u64 >> (rm_val64 & (kXRegSizeInBits - 1));
set_register(rd, alu_out, R31IsZR);
} else {
const uint32_t rn_u32 = static_cast<uint32_t>(rn_val32);
const int32_t alu_out = rn_u32 >> (rm_val32 & (kXRegSizeInBits - 1));
set_wregister(rd, alu_out, R31IsZR);
}
break;
}
case 10: {
// Format(instr, "asr'sf 'rd, 'rn, 'rm");
if (instr->SFField() == 1) {
const int64_t alu_out = rn_val64 >> (rm_val64 & (kXRegSizeInBits - 1));
set_register(rd, alu_out, R31IsZR);
} else {
const int32_t alu_out = rn_val32 >> (rm_val32 & (kXRegSizeInBits - 1));
set_wregister(rd, alu_out, R31IsZR);
}
break;
}
default:
UnimplementedInstruction(instr);
break;
}
}
void Simulator::DecodeMiscDP3Source(Instr* instr) {
if ((instr->Bits(29, 2) == 0) && (instr->Bits(21, 3) == 0) &&
(instr->Bit(15) == 0)) {
// Format(instr, "madd'sf 'rd, 'rn, 'rm, 'ra");
const Register rd = instr->RdField();
const Register rn = instr->RnField();
const Register rm = instr->RmField();
const Register ra = instr->RaField();
if (instr->SFField() == 1) {
const int64_t rn_val = get_register(rn, R31IsZR);
const int64_t rm_val = get_register(rm, R31IsZR);
const int64_t ra_val = get_register(ra, R31IsZR);
const int64_t alu_out = ra_val + (rn_val * rm_val);
set_register(rd, alu_out, R31IsZR);
} else {
const int32_t rn_val = get_wregister(rn, R31IsZR);
const int32_t rm_val = get_wregister(rm, R31IsZR);
const int32_t ra_val = get_wregister(ra, R31IsZR);
const int32_t alu_out = ra_val + (rn_val * rm_val);
set_wregister(rd, alu_out, R31IsZR);
}
} else {
UnimplementedInstruction(instr);
}
}
void Simulator::DecodeConditionalSelect(Instr* instr) {
if ((instr->Bits(29, 2) == 0) && (instr->Bits(10, 2) == 0)) {
// Format(instr, "mov'sf'cond 'rd, 'rn, 'rm");
const Register rd = instr->RdField();
const Register rn = instr->RnField();
const Register rm = instr->RmField();
if (instr->SFField() == 1) {
int64_t res = 0;
if (ConditionallyExecute(instr)) {
res = get_register(rn, instr->RnMode());
} else {
res = get_register(rm, R31IsZR);
}
set_register(rd, res, instr->RdMode());
} else {
int32_t res = 0;
if (ConditionallyExecute(instr)) {
res = get_wregister(rn, instr->RnMode());
} else {
res = get_wregister(rm, R31IsZR);
}
set_wregister(rd, res, instr->RdMode());
}
} else {
UnimplementedInstruction(instr);
}
}
void Simulator::DecodeDPRegister(Instr* instr) {
if (instr->IsAddSubShiftExtOp()) {
DecodeAddSubShiftExt(instr);
} else if (instr->IsLogicalShiftOp()) {
DecodeLogicalShift(instr);
} else if (instr->IsMiscDP2SourceOp()) {
DecodeMiscDP2Source(instr);
} else if (instr->IsMiscDP3SourceOp()) {
DecodeMiscDP3Source(instr);
} else if (instr->IsConditionalSelectOp()) {
DecodeConditionalSelect(instr);
} else {
UnimplementedInstruction(instr);
}
}
void Simulator::DecodeDPSimd1(Instr* instr) {
UnimplementedInstruction(instr);
}
void Simulator::DecodeDPSimd2(Instr* instr) {
UnimplementedInstruction(instr);
}
// Executes the current instruction.
void Simulator::InstructionDecode(Instr* instr) {
pc_modified_ = false;
if (FLAG_trace_sim) {
const uword start = reinterpret_cast<uword>(instr);
const uword end = start + Instr::kInstrSize;
Disassembler::Disassemble(start, end);
}
if (instr->IsDPImmediateOp()) {
DecodeDPImmediate(instr);
} else if (instr->IsCompareBranchOp()) {
DecodeCompareBranch(instr);
} else if (instr->IsLoadStoreOp()) {
DecodeLoadStore(instr);
} else if (instr->IsDPRegisterOp()) {
DecodeDPRegister(instr);
} else if (instr->IsDPSimd1Op()) {
DecodeDPSimd1(instr);
} else if (instr->IsDPSimd2Op()) {
DecodeDPSimd2(instr);
} else {
UnimplementedInstruction(instr);
}
if (!pc_modified_) {
set_pc(reinterpret_cast<int64_t>(instr) + Instr::kInstrSize);
}
}
void Simulator::Execute() {
// Get the PC to simulate. Cannot use the accessor here as we need the
// raw PC value and not the one used as input to arithmetic instructions.
uword program_counter = get_pc();
if (FLAG_stop_sim_at == 0) {
// Fast version of the dispatch loop without checking whether the simulator
// should be stopping at a particular executed instruction.
while (program_counter != kEndSimulatingPC) {
Instr* instr = reinterpret_cast<Instr*>(program_counter);
icount_++;
if (IsIllegalAddress(program_counter)) {
HandleIllegalAccess(program_counter, instr);
} else {
InstructionDecode(instr);
}
program_counter = get_pc();
}
} else {
// FLAG_stop_sim_at is at the non-default value. Stop in the debugger when
// we reach the particular instruction count.
while (program_counter != kEndSimulatingPC) {
Instr* instr = reinterpret_cast<Instr*>(program_counter);
icount_++;
if (icount_ == FLAG_stop_sim_at) {
// TODO(zra): Add a debugger.
UNIMPLEMENTED();
} else if (IsIllegalAddress(program_counter)) {
HandleIllegalAccess(program_counter, instr);
} else {
InstructionDecode(instr);
}
program_counter = get_pc();
}
}
}
int64_t Simulator::Call(int64_t entry,
int64_t parameter0,
int64_t parameter1,
int64_t parameter2,
int64_t parameter3) {
// Save the SP register before the call so we can restore it.
intptr_t sp_before_call = get_register(R31, R31IsSP);
// Setup parameters.
set_register(R0, parameter0);
set_register(R1, parameter1);
set_register(R2, parameter2);
set_register(R3, parameter3);
// Make sure the activation frames are properly aligned.
intptr_t stack_pointer = sp_before_call;
if (OS::ActivationFrameAlignment() > 1) {
stack_pointer =
Utils::RoundDown(stack_pointer, OS::ActivationFrameAlignment());
}
set_register(R31, stack_pointer, R31IsSP);
// Prepare to execute the code at entry.
set_pc(entry);
// Put down marker for end of simulation. The simulator will stop simulation
// when the PC reaches this value. By saving the "end simulation" value into
// the LR the simulation stops when returning to this call point.
set_register(LR, kEndSimulatingPC);
// Remember the values of callee-saved registers.
int64_t r19_val = get_register(R19);
int64_t r20_val = get_register(R20);
int64_t r21_val = get_register(R21);
int64_t r22_val = get_register(R22);
int64_t r23_val = get_register(R23);
int64_t r24_val = get_register(R24);
int64_t r25_val = get_register(R25);
int64_t r26_val = get_register(R26);
int64_t r27_val = get_register(R27);
int64_t r28_val = get_register(R28);
int64_t r29_val = get_register(R29);
// Setup the callee-saved registers with a known value. To be able to check
// that they are preserved properly across dart execution.
int64_t callee_saved_value = icount_;
set_register(R19, callee_saved_value);
set_register(R20, callee_saved_value);
set_register(R21, callee_saved_value);
set_register(R22, callee_saved_value);
set_register(R23, callee_saved_value);
set_register(R24, callee_saved_value);
set_register(R25, callee_saved_value);
set_register(R26, callee_saved_value);
set_register(R27, callee_saved_value);
set_register(R28, callee_saved_value);
set_register(R29, callee_saved_value);
// Start the simulation
Execute();
// Check that the callee-saved registers have been preserved.
ASSERT(callee_saved_value == get_register(R19));
ASSERT(callee_saved_value == get_register(R20));
ASSERT(callee_saved_value == get_register(R21));
ASSERT(callee_saved_value == get_register(R22));
ASSERT(callee_saved_value == get_register(R23));
ASSERT(callee_saved_value == get_register(R24));
ASSERT(callee_saved_value == get_register(R25));
ASSERT(callee_saved_value == get_register(R26));
ASSERT(callee_saved_value == get_register(R27));
ASSERT(callee_saved_value == get_register(R28));
ASSERT(callee_saved_value == get_register(R29));
// Restore callee-saved registers with the original value.
set_register(R19, r19_val);
set_register(R20, r20_val);
set_register(R21, r21_val);
set_register(R22, r22_val);
set_register(R23, r23_val);
set_register(R24, r24_val);
set_register(R25, r25_val);
set_register(R26, r26_val);
set_register(R27, r27_val);
set_register(R28, r28_val);
set_register(R29, r29_val);
// Restore the SP register and return R0.
set_register(R31, sp_before_call, R31IsSP);
int64_t return_value;
return_value = get_register(R0);
return return_value;
}
} // namespace dart
#endif // !defined(HOST_ARCH_ARM64)
#endif // defined TARGET_ARCH_ARM64
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