deps/v8/src/arm/simulator-arm.cc
// Copyright 2012 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <stdarg.h>
#include <stdlib.h>
#include <cmath>
#include "src/v8.h"
#if V8_TARGET_ARCH_ARM
#include "src/arm/constants-arm.h"
#include "src/arm/simulator-arm.h"
#include "src/assembler.h"
#include "src/codegen.h"
#include "src/disasm.h"
#if defined(USE_SIMULATOR)
// Only build the simulator if not compiling for real ARM hardware.
namespace v8 {
namespace internal {
// This macro provides a platform independent use of sscanf. The reason for
// SScanF not being implemented in a platform independent way through
// ::v8::internal::OS in the same way as SNPrintF is that the
// Windows C Run-Time Library does not provide vsscanf.
#define SScanF sscanf // NOLINT
// The ArmDebugger class is used by the simulator while debugging simulated ARM
// code.
class ArmDebugger {
public:
explicit ArmDebugger(Simulator* sim) : sim_(sim) { }
~ArmDebugger();
void Stop(Instruction* instr);
void Debug();
private:
static const Instr kBreakpointInstr =
(al | (7*B25) | (1*B24) | kBreakpoint);
static const Instr kNopInstr = (al | (13*B21));
Simulator* sim_;
int32_t GetRegisterValue(int regnum);
double GetRegisterPairDoubleValue(int regnum);
double GetVFPDoubleRegisterValue(int regnum);
bool GetValue(const char* desc, int32_t* value);
bool GetVFPSingleValue(const char* desc, float* value);
bool GetVFPDoubleValue(const char* desc, double* value);
// Set or delete a breakpoint. Returns true if successful.
bool SetBreakpoint(Instruction* breakpc);
bool DeleteBreakpoint(Instruction* breakpc);
// Undo and redo all breakpoints. This is needed to bracket disassembly and
// execution to skip past breakpoints when run from the debugger.
void UndoBreakpoints();
void RedoBreakpoints();
};
ArmDebugger::~ArmDebugger() {
}
#ifdef GENERATED_CODE_COVERAGE
static FILE* coverage_log = NULL;
static void InitializeCoverage() {
char* file_name = getenv("V8_GENERATED_CODE_COVERAGE_LOG");
if (file_name != NULL) {
coverage_log = fopen(file_name, "aw+");
}
}
void ArmDebugger::Stop(Instruction* instr) {
// Get the stop code.
uint32_t code = instr->SvcValue() & kStopCodeMask;
// Retrieve the encoded address, which comes just after this stop.
char** msg_address =
reinterpret_cast<char**>(sim_->get_pc() + Instruction::kInstrSize);
char* msg = *msg_address;
DCHECK(msg != NULL);
// Update this stop description.
if (isWatchedStop(code) && !watched_stops_[code].desc) {
watched_stops_[code].desc = msg;
}
if (strlen(msg) > 0) {
if (coverage_log != NULL) {
fprintf(coverage_log, "%s\n", msg);
fflush(coverage_log);
}
// Overwrite the instruction and address with nops.
instr->SetInstructionBits(kNopInstr);
reinterpret_cast<Instruction*>(msg_address)->SetInstructionBits(kNopInstr);
}
sim_->set_pc(sim_->get_pc() + 2 * Instruction::kInstrSize);
}
#else // ndef GENERATED_CODE_COVERAGE
static void InitializeCoverage() {
}
void ArmDebugger::Stop(Instruction* instr) {
// Get the stop code.
uint32_t code = instr->SvcValue() & kStopCodeMask;
// Retrieve the encoded address, which comes just after this stop.
char* msg = *reinterpret_cast<char**>(sim_->get_pc()
+ Instruction::kInstrSize);
// Update this stop description.
if (sim_->isWatchedStop(code) && !sim_->watched_stops_[code].desc) {
sim_->watched_stops_[code].desc = msg;
}
// Print the stop message and code if it is not the default code.
if (code != kMaxStopCode) {
PrintF("Simulator hit stop %u: %s\n", code, msg);
} else {
PrintF("Simulator hit %s\n", msg);
}
sim_->set_pc(sim_->get_pc() + 2 * Instruction::kInstrSize);
Debug();
}
#endif
int32_t ArmDebugger::GetRegisterValue(int regnum) {
if (regnum == kPCRegister) {
return sim_->get_pc();
} else {
return sim_->get_register(regnum);
}
}
double ArmDebugger::GetRegisterPairDoubleValue(int regnum) {
return sim_->get_double_from_register_pair(regnum);
}
double ArmDebugger::GetVFPDoubleRegisterValue(int regnum) {
return sim_->get_double_from_d_register(regnum);
}
bool ArmDebugger::GetValue(const char* desc, int32_t* value) {
int regnum = Registers::Number(desc);
if (regnum != kNoRegister) {
*value = GetRegisterValue(regnum);
return true;
} else {
if (strncmp(desc, "0x", 2) == 0) {
return SScanF(desc + 2, "%x", reinterpret_cast<uint32_t*>(value)) == 1;
} else {
return SScanF(desc, "%u", reinterpret_cast<uint32_t*>(value)) == 1;
}
}
return false;
}
bool ArmDebugger::GetVFPSingleValue(const char* desc, float* value) {
bool is_double;
int regnum = VFPRegisters::Number(desc, &is_double);
if (regnum != kNoRegister && !is_double) {
*value = sim_->get_float_from_s_register(regnum);
return true;
}
return false;
}
bool ArmDebugger::GetVFPDoubleValue(const char* desc, double* value) {
bool is_double;
int regnum = VFPRegisters::Number(desc, &is_double);
if (regnum != kNoRegister && is_double) {
*value = sim_->get_double_from_d_register(regnum);
return true;
}
return false;
}
bool ArmDebugger::SetBreakpoint(Instruction* breakpc) {
// Check if a breakpoint can be set. If not return without any side-effects.
if (sim_->break_pc_ != NULL) {
return false;
}
// Set the breakpoint.
sim_->break_pc_ = breakpc;
sim_->break_instr_ = breakpc->InstructionBits();
// Not setting the breakpoint instruction in the code itself. It will be set
// when the debugger shell continues.
return true;
}
bool ArmDebugger::DeleteBreakpoint(Instruction* breakpc) {
if (sim_->break_pc_ != NULL) {
sim_->break_pc_->SetInstructionBits(sim_->break_instr_);
}
sim_->break_pc_ = NULL;
sim_->break_instr_ = 0;
return true;
}
void ArmDebugger::UndoBreakpoints() {
if (sim_->break_pc_ != NULL) {
sim_->break_pc_->SetInstructionBits(sim_->break_instr_);
}
}
void ArmDebugger::RedoBreakpoints() {
if (sim_->break_pc_ != NULL) {
sim_->break_pc_->SetInstructionBits(kBreakpointInstr);
}
}
void ArmDebugger::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];
char* argv[3] = { cmd, arg1, arg2 };
// make sure to have a proper terminating character if reaching the limit
cmd[COMMAND_SIZE] = 0;
arg1[ARG_SIZE] = 0;
arg2[ARG_SIZE] = 0;
// Undo all set breakpoints while running in the debugger shell. This will
// make them invisible to all commands.
UndoBreakpoints();
while (!done && !sim_->has_bad_pc()) {
if (last_pc != sim_->get_pc()) {
disasm::NameConverter converter;
disasm::Disassembler dasm(converter);
// use a reasonably large buffer
v8::internal::EmbeddedVector<char, 256> buffer;
dasm.InstructionDecode(buffer,
reinterpret_cast<byte*>(sim_->get_pc()));
PrintF(" 0x%08x %s\n", sim_->get_pc(), buffer.start());
last_pc = sim_->get_pc();
}
char* line = ReadLine("sim> ");
if (line == NULL) {
break;
} else {
char* last_input = sim_->last_debugger_input();
if (strcmp(line, "\n") == 0 && last_input != NULL) {
line = last_input;
} else {
// Ownership is transferred to sim_;
sim_->set_last_debugger_input(line);
}
// Use sscanf to parse the individual parts of the command line. At the
// moment no command expects more than two parameters.
int argc = SScanF(line,
"%" XSTR(COMMAND_SIZE) "s "
"%" XSTR(ARG_SIZE) "s "
"%" XSTR(ARG_SIZE) "s",
cmd, arg1, arg2);
if ((strcmp(cmd, "si") == 0) || (strcmp(cmd, "stepi") == 0)) {
sim_->InstructionDecode(reinterpret_cast<Instruction*>(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<Instruction*>(sim_->get_pc()));
// Leave the debugger shell.
done = true;
} else if ((strcmp(cmd, "p") == 0) || (strcmp(cmd, "print") == 0)) {
if (argc == 2 || (argc == 3 && strcmp(arg2, "fp") == 0)) {
int32_t value;
float svalue;
double dvalue;
if (strcmp(arg1, "all") == 0) {
for (int i = 0; i < kNumRegisters; i++) {
value = GetRegisterValue(i);
PrintF("%3s: 0x%08x %10d", Registers::Name(i), value, value);
if ((argc == 3 && strcmp(arg2, "fp") == 0) &&
i < 8 &&
(i % 2) == 0) {
dvalue = GetRegisterPairDoubleValue(i);
PrintF(" (%f)\n", dvalue);
} else {
PrintF("\n");
}
}
for (int i = 0; i < DwVfpRegister::NumRegisters(); i++) {
dvalue = GetVFPDoubleRegisterValue(i);
uint64_t as_words = BitCast<uint64_t>(dvalue);
PrintF("%3s: %f 0x%08x %08x\n",
VFPRegisters::Name(i, true),
dvalue,
static_cast<uint32_t>(as_words >> 32),
static_cast<uint32_t>(as_words & 0xffffffff));
}
} else {
if (GetValue(arg1, &value)) {
PrintF("%s: 0x%08x %d \n", arg1, value, value);
} else if (GetVFPSingleValue(arg1, &svalue)) {
uint32_t as_word = BitCast<uint32_t>(svalue);
PrintF("%s: %f 0x%08x\n", arg1, svalue, as_word);
} else if (GetVFPDoubleValue(arg1, &dvalue)) {
uint64_t as_words = BitCast<uint64_t>(dvalue);
PrintF("%s: %f 0x%08x %08x\n",
arg1,
dvalue,
static_cast<uint32_t>(as_words >> 32),
static_cast<uint32_t>(as_words & 0xffffffff));
} else {
PrintF("%s unrecognized\n", arg1);
}
}
} else {
PrintF("print <register>\n");
}
} else if ((strcmp(cmd, "po") == 0)
|| (strcmp(cmd, "printobject") == 0)) {
if (argc == 2) {
int32_t value;
OFStream os(stdout);
if (GetValue(arg1, &value)) {
Object* obj = reinterpret_cast<Object*>(value);
os << arg1 << ": \n";
#ifdef DEBUG
obj->Print(os);
os << "\n";
#else
os << Brief(obj) << "\n";
#endif
} else {
os << arg1 << " unrecognized\n";
}
} else {
PrintF("printobject <value>\n");
}
} else if (strcmp(cmd, "stack") == 0 || strcmp(cmd, "mem") == 0) {
int32_t* cur = NULL;
int32_t* end = NULL;
int next_arg = 1;
if (strcmp(cmd, "stack") == 0) {
cur = reinterpret_cast<int32_t*>(sim_->get_register(Simulator::sp));
} else { // "mem"
int32_t value;
if (!GetValue(arg1, &value)) {
PrintF("%s unrecognized\n", arg1);
continue;
}
cur = reinterpret_cast<int32_t*>(value);
next_arg++;
}
int32_t words;
if (argc == next_arg) {
words = 10;
} else {
if (!GetValue(argv[next_arg], &words)) {
words = 10;
}
}
end = cur + words;
while (cur < end) {
PrintF(" 0x%08x: 0x%08x %10d",
reinterpret_cast<intptr_t>(cur), *cur, *cur);
HeapObject* obj = reinterpret_cast<HeapObject*>(*cur);
int value = *cur;
Heap* current_heap = v8::internal::Isolate::Current()->heap();
if (((value & 1) == 0) || current_heap->Contains(obj)) {
PrintF(" (");
if ((value & 1) == 0) {
PrintF("smi %d", value / 2);
} else {
obj->ShortPrint();
}
PrintF(")");
}
PrintF("\n");
cur++;
}
} else if (strcmp(cmd, "disasm") == 0 || strcmp(cmd, "di") == 0) {
disasm::NameConverter converter;
disasm::Disassembler dasm(converter);
// use a reasonably large buffer
v8::internal::EmbeddedVector<char, 256> buffer;
byte* prev = NULL;
byte* cur = NULL;
byte* end = NULL;
if (argc == 1) {
cur = reinterpret_cast<byte*>(sim_->get_pc());
end = cur + (10 * Instruction::kInstrSize);
} else if (argc == 2) {
int regnum = Registers::Number(arg1);
if (regnum != kNoRegister || strncmp(arg1, "0x", 2) == 0) {
// The argument is an address or a register name.
int32_t value;
if (GetValue(arg1, &value)) {
cur = reinterpret_cast<byte*>(value);
// Disassemble 10 instructions at <arg1>.
end = cur + (10 * Instruction::kInstrSize);
}
} else {
// The argument is the number of instructions.
int32_t value;
if (GetValue(arg1, &value)) {
cur = reinterpret_cast<byte*>(sim_->get_pc());
// Disassemble <arg1> instructions.
end = cur + (value * Instruction::kInstrSize);
}
}
} else {
int32_t value1;
int32_t value2;
if (GetValue(arg1, &value1) && GetValue(arg2, &value2)) {
cur = reinterpret_cast<byte*>(value1);
end = cur + (value2 * Instruction::kInstrSize);
}
}
while (cur < end) {
prev = cur;
cur += dasm.InstructionDecode(buffer, cur);
PrintF(" 0x%08x %s\n",
reinterpret_cast<intptr_t>(prev), buffer.start());
}
} else if (strcmp(cmd, "gdb") == 0) {
PrintF("relinquishing control to gdb\n");
v8::base::OS::DebugBreak();
PrintF("regaining control from gdb\n");
} else if (strcmp(cmd, "break") == 0) {
if (argc == 2) {
int32_t value;
if (GetValue(arg1, &value)) {
if (!SetBreakpoint(reinterpret_cast<Instruction*>(value))) {
PrintF("setting breakpoint failed\n");
}
} else {
PrintF("%s unrecognized\n", arg1);
}
} else {
PrintF("break <address>\n");
}
} else if (strcmp(cmd, "del") == 0) {
if (!DeleteBreakpoint(NULL)) {
PrintF("deleting breakpoint failed\n");
}
} else if (strcmp(cmd, "flags") == 0) {
PrintF("N flag: %d; ", sim_->n_flag_);
PrintF("Z flag: %d; ", sim_->z_flag_);
PrintF("C flag: %d; ", sim_->c_flag_);
PrintF("V flag: %d\n", sim_->v_flag_);
PrintF("INVALID OP flag: %d; ", sim_->inv_op_vfp_flag_);
PrintF("DIV BY ZERO flag: %d; ", sim_->div_zero_vfp_flag_);
PrintF("OVERFLOW flag: %d; ", sim_->overflow_vfp_flag_);
PrintF("UNDERFLOW flag: %d; ", sim_->underflow_vfp_flag_);
PrintF("INEXACT flag: %d;\n", sim_->inexact_vfp_flag_);
} else if (strcmp(cmd, "stop") == 0) {
int32_t value;
intptr_t stop_pc = sim_->get_pc() - 2 * Instruction::kInstrSize;
Instruction* stop_instr = reinterpret_cast<Instruction*>(stop_pc);
Instruction* msg_address =
reinterpret_cast<Instruction*>(stop_pc + Instruction::kInstrSize);
if ((argc == 2) && (strcmp(arg1, "unstop") == 0)) {
// Remove the current stop.
if (sim_->isStopInstruction(stop_instr)) {
stop_instr->SetInstructionBits(kNopInstr);
msg_address->SetInstructionBits(kNopInstr);
} else {
PrintF("Not at debugger stop.\n");
}
} else if (argc == 3) {
// Print information about all/the specified breakpoint(s).
if (strcmp(arg1, "info") == 0) {
if (strcmp(arg2, "all") == 0) {
PrintF("Stop information:\n");
for (uint32_t i = 0; i < sim_->kNumOfWatchedStops; i++) {
sim_->PrintStopInfo(i);
}
} else if (GetValue(arg2, &value)) {
sim_->PrintStopInfo(value);
} else {
PrintF("Unrecognized argument.\n");
}
} else if (strcmp(arg1, "enable") == 0) {
// Enable all/the specified breakpoint(s).
if (strcmp(arg2, "all") == 0) {
for (uint32_t i = 0; i < sim_->kNumOfWatchedStops; i++) {
sim_->EnableStop(i);
}
} else if (GetValue(arg2, &value)) {
sim_->EnableStop(value);
} else {
PrintF("Unrecognized argument.\n");
}
} else if (strcmp(arg1, "disable") == 0) {
// Disable all/the specified breakpoint(s).
if (strcmp(arg2, "all") == 0) {
for (uint32_t i = 0; i < sim_->kNumOfWatchedStops; i++) {
sim_->DisableStop(i);
}
} else if (GetValue(arg2, &value)) {
sim_->DisableStop(value);
} else {
PrintF("Unrecognized argument.\n");
}
}
} else {
PrintF("Wrong usage. Use help command for more information.\n");
}
} else if ((strcmp(cmd, "t") == 0) || strcmp(cmd, "trace") == 0) {
::v8::internal::FLAG_trace_sim = !::v8::internal::FLAG_trace_sim;
PrintF("Trace of executed instructions is %s\n",
::v8::internal::FLAG_trace_sim ? "on" : "off");
} else if ((strcmp(cmd, "h") == 0) || (strcmp(cmd, "help") == 0)) {
PrintF("cont\n");
PrintF(" continue execution (alias 'c')\n");
PrintF("stepi\n");
PrintF(" step one instruction (alias 'si')\n");
PrintF("print <register>\n");
PrintF(" print register content (alias 'p')\n");
PrintF(" use register name 'all' to print all registers\n");
PrintF(" add argument 'fp' to print register pair double values\n");
PrintF("printobject <register>\n");
PrintF(" print an object from a register (alias 'po')\n");
PrintF("flags\n");
PrintF(" print flags\n");
PrintF("stack [<words>]\n");
PrintF(" dump stack content, default dump 10 words)\n");
PrintF("mem <address> [<words>]\n");
PrintF(" dump memory content, default dump 10 words)\n");
PrintF("disasm [<instructions>]\n");
PrintF("disasm [<address/register>]\n");
PrintF("disasm [[<address/register>] <instructions>]\n");
PrintF(" disassemble code, default is 10 instructions\n");
PrintF(" from pc (alias 'di')\n");
PrintF("gdb\n");
PrintF(" enter gdb\n");
PrintF("break <address>\n");
PrintF(" set a break point on the address\n");
PrintF("del\n");
PrintF(" delete the breakpoint\n");
PrintF("trace (alias 't')\n");
PrintF(" toogle the tracing of all executed statements\n");
PrintF("stop feature:\n");
PrintF(" Description:\n");
PrintF(" Stops are debug instructions inserted by\n");
PrintF(" the Assembler::stop() function.\n");
PrintF(" When hitting a stop, the Simulator will\n");
PrintF(" stop and and give control to the ArmDebugger.\n");
PrintF(" The first %d stop codes are watched:\n",
Simulator::kNumOfWatchedStops);
PrintF(" - They can be enabled / disabled: the Simulator\n");
PrintF(" will / won't stop when hitting them.\n");
PrintF(" - The Simulator keeps track of how many times they \n");
PrintF(" are met. (See the info command.) Going over a\n");
PrintF(" disabled stop still increases its counter. \n");
PrintF(" Commands:\n");
PrintF(" stop info all/<code> : print infos about number <code>\n");
PrintF(" or all stop(s).\n");
PrintF(" stop enable/disable all/<code> : enables / disables\n");
PrintF(" all or number <code> stop(s)\n");
PrintF(" stop unstop\n");
PrintF(" ignore the stop instruction at the current location\n");
PrintF(" from now on\n");
} else {
PrintF("Unknown command: %s\n", cmd);
}
}
}
// 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
}
static bool ICacheMatch(void* one, void* two) {
DCHECK((reinterpret_cast<intptr_t>(one) & CachePage::kPageMask) == 0);
DCHECK((reinterpret_cast<intptr_t>(two) & CachePage::kPageMask) == 0);
return one == two;
}
static uint32_t ICacheHash(void* key) {
return static_cast<uint32_t>(reinterpret_cast<uintptr_t>(key)) >> 2;
}
static bool AllOnOnePage(uintptr_t start, int size) {
intptr_t start_page = (start & ~CachePage::kPageMask);
intptr_t end_page = ((start + size) & ~CachePage::kPageMask);
return start_page == end_page;
}
void Simulator::set_last_debugger_input(char* input) {
DeleteArray(last_debugger_input_);
last_debugger_input_ = input;
}
void Simulator::FlushICache(v8::internal::HashMap* i_cache,
void* start_addr,
size_t size) {
intptr_t start = reinterpret_cast<intptr_t>(start_addr);
int intra_line = (start & CachePage::kLineMask);
start -= intra_line;
size += intra_line;
size = ((size - 1) | CachePage::kLineMask) + 1;
int offset = (start & CachePage::kPageMask);
while (!AllOnOnePage(start, size - 1)) {
int bytes_to_flush = CachePage::kPageSize - offset;
FlushOnePage(i_cache, start, bytes_to_flush);
start += bytes_to_flush;
size -= bytes_to_flush;
DCHECK_EQ(0, start & CachePage::kPageMask);
offset = 0;
}
if (size != 0) {
FlushOnePage(i_cache, start, size);
}
}
CachePage* Simulator::GetCachePage(v8::internal::HashMap* i_cache, void* page) {
v8::internal::HashMap::Entry* entry = i_cache->Lookup(page,
ICacheHash(page),
true);
if (entry->value == NULL) {
CachePage* new_page = new CachePage();
entry->value = new_page;
}
return reinterpret_cast<CachePage*>(entry->value);
}
// Flush from start up to and not including start + size.
void Simulator::FlushOnePage(v8::internal::HashMap* i_cache,
intptr_t start,
int size) {
DCHECK(size <= CachePage::kPageSize);
DCHECK(AllOnOnePage(start, size - 1));
DCHECK((start & CachePage::kLineMask) == 0);
DCHECK((size & CachePage::kLineMask) == 0);
void* page = reinterpret_cast<void*>(start & (~CachePage::kPageMask));
int offset = (start & CachePage::kPageMask);
CachePage* cache_page = GetCachePage(i_cache, page);
char* valid_bytemap = cache_page->ValidityByte(offset);
memset(valid_bytemap, CachePage::LINE_INVALID, size >> CachePage::kLineShift);
}
void Simulator::CheckICache(v8::internal::HashMap* i_cache,
Instruction* instr) {
intptr_t address = reinterpret_cast<intptr_t>(instr);
void* page = reinterpret_cast<void*>(address & (~CachePage::kPageMask));
void* line = reinterpret_cast<void*>(address & (~CachePage::kLineMask));
int offset = (address & CachePage::kPageMask);
CachePage* cache_page = GetCachePage(i_cache, page);
char* cache_valid_byte = cache_page->ValidityByte(offset);
bool cache_hit = (*cache_valid_byte == CachePage::LINE_VALID);
char* cached_line = cache_page->CachedData(offset & ~CachePage::kLineMask);
if (cache_hit) {
// Check that the data in memory matches the contents of the I-cache.
CHECK_EQ(0,
memcmp(reinterpret_cast<void*>(instr),
cache_page->CachedData(offset), Instruction::kInstrSize));
} else {
// Cache miss. Load memory into the cache.
memcpy(cached_line, line, CachePage::kLineLength);
*cache_valid_byte = CachePage::LINE_VALID;
}
}
void Simulator::Initialize(Isolate* isolate) {
if (isolate->simulator_initialized()) return;
isolate->set_simulator_initialized(true);
::v8::internal::ExternalReference::set_redirector(isolate,
&RedirectExternalReference);
}
Simulator::Simulator(Isolate* isolate) : isolate_(isolate) {
i_cache_ = isolate_->simulator_i_cache();
if (i_cache_ == NULL) {
i_cache_ = new v8::internal::HashMap(&ICacheMatch);
isolate_->set_simulator_i_cache(i_cache_);
}
Initialize(isolate);
// Set up simulator support first. Some of this information is needed to
// setup the architecture state.
size_t stack_size = 1 * 1024*1024; // allocate 1MB for stack
stack_ = reinterpret_cast<char*>(malloc(stack_size));
pc_modified_ = false;
icount_ = 0;
break_pc_ = NULL;
break_instr_ = 0;
// Set up architecture state.
// All registers are initialized to zero to start with.
for (int i = 0; i < num_registers; i++) {
registers_[i] = 0;
}
n_flag_ = false;
z_flag_ = false;
c_flag_ = false;
v_flag_ = false;
// Initializing VFP registers.
// All registers are initialized to zero to start with
// even though s_registers_ & d_registers_ share the same
// physical registers in the target.
for (int i = 0; i < num_d_registers * 2; i++) {
vfp_registers_[i] = 0;
}
n_flag_FPSCR_ = false;
z_flag_FPSCR_ = false;
c_flag_FPSCR_ = false;
v_flag_FPSCR_ = false;
FPSCR_rounding_mode_ = RN;
FPSCR_default_NaN_mode_ = false;
inv_op_vfp_flag_ = false;
div_zero_vfp_flag_ = false;
overflow_vfp_flag_ = false;
underflow_vfp_flag_ = false;
inexact_vfp_flag_ = false;
// The sp is initialized to point to the bottom (high address) of the
// allocated stack area. To be safe in potential stack underflows we leave
// some buffer below.
registers_[sp] = reinterpret_cast<int32_t>(stack_) + stack_size - 64;
// 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_[pc] = bad_lr;
registers_[lr] = bad_lr;
InitializeCoverage();
last_debugger_input_ = NULL;
}
Simulator::~Simulator() {
}
// 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:
Redirection(void* external_function, ExternalReference::Type type)
: external_function_(external_function),
swi_instruction_(al | (0xf*B24) | kCallRtRedirected),
type_(type),
next_(NULL) {
Isolate* isolate = Isolate::Current();
next_ = isolate->simulator_redirection();
Simulator::current(isolate)->
FlushICache(isolate->simulator_i_cache(),
reinterpret_cast<void*>(&swi_instruction_),
Instruction::kInstrSize);
isolate->set_simulator_redirection(this);
}
void* address_of_swi_instruction() {
return reinterpret_cast<void*>(&swi_instruction_);
}
void* external_function() { return external_function_; }
ExternalReference::Type type() { return type_; }
static Redirection* Get(void* external_function,
ExternalReference::Type type) {
Isolate* isolate = Isolate::Current();
Redirection* current = isolate->simulator_redirection();
for (; current != NULL; current = current->next_) {
if (current->external_function_ == external_function) {
DCHECK_EQ(current->type(), type);
return current;
}
}
return new Redirection(external_function, type);
}
static Redirection* FromSwiInstruction(Instruction* swi_instruction) {
char* addr_of_swi = reinterpret_cast<char*>(swi_instruction);
char* addr_of_redirection =
addr_of_swi - OFFSET_OF(Redirection, swi_instruction_);
return reinterpret_cast<Redirection*>(addr_of_redirection);
}
static void* ReverseRedirection(int32_t reg) {
Redirection* redirection = FromSwiInstruction(
reinterpret_cast<Instruction*>(reinterpret_cast<void*>(reg)));
return redirection->external_function();
}
private:
void* external_function_;
uint32_t swi_instruction_;
ExternalReference::Type type_;
Redirection* next_;
};
void* Simulator::RedirectExternalReference(void* external_function,
ExternalReference::Type type) {
Redirection* redirection = Redirection::Get(external_function, type);
return redirection->address_of_swi_instruction();
}
// Get the active Simulator for the current thread.
Simulator* Simulator::current(Isolate* isolate) {
v8::internal::Isolate::PerIsolateThreadData* isolate_data =
isolate->FindOrAllocatePerThreadDataForThisThread();
DCHECK(isolate_data != NULL);
Simulator* sim = isolate_data->simulator();
if (sim == NULL) {
// TODO(146): delete the simulator object when a thread/isolate goes away.
sim = new Simulator(isolate);
isolate_data->set_simulator(sim);
}
return sim;
}
// Sets the register in the architecture state. It will also deal with updating
// Simulator internal state for special registers such as PC.
void Simulator::set_register(int reg, int32_t value) {
DCHECK((reg >= 0) && (reg < num_registers));
if (reg == pc) {
pc_modified_ = true;
}
registers_[reg] = value;
}
// Get the register from the architecture state. This function does handle
// the special case of accessing the PC register.
int32_t Simulator::get_register(int reg) const {
DCHECK((reg >= 0) && (reg < num_registers));
// Stupid code added to avoid bug in GCC.
// See: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43949
if (reg >= num_registers) return 0;
// End stupid code.
return registers_[reg] + ((reg == pc) ? Instruction::kPCReadOffset : 0);
}
double Simulator::get_double_from_register_pair(int reg) {
DCHECK((reg >= 0) && (reg < num_registers) && ((reg % 2) == 0));
double dm_val = 0.0;
// Read the bits from the unsigned integer register_[] array
// into the double precision floating point value and return it.
char buffer[2 * sizeof(vfp_registers_[0])];
memcpy(buffer, ®isters_[reg], 2 * sizeof(registers_[0]));
memcpy(&dm_val, buffer, 2 * sizeof(registers_[0]));
return(dm_val);
}
void Simulator::set_register_pair_from_double(int reg, double* value) {
DCHECK((reg >= 0) && (reg < num_registers) && ((reg % 2) == 0));
memcpy(registers_ + reg, value, sizeof(*value));
}
void Simulator::set_dw_register(int dreg, const int* dbl) {
DCHECK((dreg >= 0) && (dreg < num_d_registers));
registers_[dreg] = dbl[0];
registers_[dreg + 1] = dbl[1];
}
void Simulator::get_d_register(int dreg, uint64_t* value) {
DCHECK((dreg >= 0) && (dreg < DwVfpRegister::NumRegisters()));
memcpy(value, vfp_registers_ + dreg * 2, sizeof(*value));
}
void Simulator::set_d_register(int dreg, const uint64_t* value) {
DCHECK((dreg >= 0) && (dreg < DwVfpRegister::NumRegisters()));
memcpy(vfp_registers_ + dreg * 2, value, sizeof(*value));
}
void Simulator::get_d_register(int dreg, uint32_t* value) {
DCHECK((dreg >= 0) && (dreg < DwVfpRegister::NumRegisters()));
memcpy(value, vfp_registers_ + dreg * 2, sizeof(*value) * 2);
}
void Simulator::set_d_register(int dreg, const uint32_t* value) {
DCHECK((dreg >= 0) && (dreg < DwVfpRegister::NumRegisters()));
memcpy(vfp_registers_ + dreg * 2, value, sizeof(*value) * 2);
}
void Simulator::get_q_register(int qreg, uint64_t* value) {
DCHECK((qreg >= 0) && (qreg < num_q_registers));
memcpy(value, vfp_registers_ + qreg * 4, sizeof(*value) * 2);
}
void Simulator::set_q_register(int qreg, const uint64_t* value) {
DCHECK((qreg >= 0) && (qreg < num_q_registers));
memcpy(vfp_registers_ + qreg * 4, value, sizeof(*value) * 2);
}
void Simulator::get_q_register(int qreg, uint32_t* value) {
DCHECK((qreg >= 0) && (qreg < num_q_registers));
memcpy(value, vfp_registers_ + qreg * 4, sizeof(*value) * 4);
}
void Simulator::set_q_register(int qreg, const uint32_t* value) {
DCHECK((qreg >= 0) && (qreg < num_q_registers));
memcpy(vfp_registers_ + qreg * 4, value, sizeof(*value) * 4);
}
// Raw access to the PC register.
void Simulator::set_pc(int32_t value) {
pc_modified_ = true;
registers_[pc] = value;
}
bool Simulator::has_bad_pc() const {
return ((registers_[pc] == bad_lr) || (registers_[pc] == end_sim_pc));
}
// Raw access to the PC register without the special adjustment when reading.
int32_t Simulator::get_pc() const {
return registers_[pc];
}
// Getting from and setting into VFP registers.
void Simulator::set_s_register(int sreg, unsigned int value) {
DCHECK((sreg >= 0) && (sreg < num_s_registers));
vfp_registers_[sreg] = value;
}
unsigned int Simulator::get_s_register(int sreg) const {
DCHECK((sreg >= 0) && (sreg < num_s_registers));
return vfp_registers_[sreg];
}
template<class InputType, int register_size>
void Simulator::SetVFPRegister(int reg_index, const InputType& value) {
DCHECK(reg_index >= 0);
if (register_size == 1) DCHECK(reg_index < num_s_registers);
if (register_size == 2) DCHECK(reg_index < DwVfpRegister::NumRegisters());
char buffer[register_size * sizeof(vfp_registers_[0])];
memcpy(buffer, &value, register_size * sizeof(vfp_registers_[0]));
memcpy(&vfp_registers_[reg_index * register_size], buffer,
register_size * sizeof(vfp_registers_[0]));
}
template<class ReturnType, int register_size>
ReturnType Simulator::GetFromVFPRegister(int reg_index) {
DCHECK(reg_index >= 0);
if (register_size == 1) DCHECK(reg_index < num_s_registers);
if (register_size == 2) DCHECK(reg_index < DwVfpRegister::NumRegisters());
ReturnType value = 0;
char buffer[register_size * sizeof(vfp_registers_[0])];
memcpy(buffer, &vfp_registers_[register_size * reg_index],
register_size * sizeof(vfp_registers_[0]));
memcpy(&value, buffer, register_size * sizeof(vfp_registers_[0]));
return value;
}
// Runtime FP routines take:
// - two double arguments
// - one double argument and zero or one integer arguments.
// All are consructed here from r0-r3 or d0, d1 and r0.
void Simulator::GetFpArgs(double* x, double* y, int32_t* z) {
if (use_eabi_hardfloat()) {
*x = get_double_from_d_register(0);
*y = get_double_from_d_register(1);
*z = get_register(0);
} else {
// Registers 0 and 1 -> x.
*x = get_double_from_register_pair(0);
// Register 2 and 3 -> y.
*y = get_double_from_register_pair(2);
// Register 2 -> z
*z = get_register(2);
}
}
// The return value is either in r0/r1 or d0.
void Simulator::SetFpResult(const double& result) {
if (use_eabi_hardfloat()) {
char buffer[2 * sizeof(vfp_registers_[0])];
memcpy(buffer, &result, sizeof(buffer));
// Copy result to d0.
memcpy(vfp_registers_, buffer, sizeof(buffer));
} else {
char buffer[2 * sizeof(registers_[0])];
memcpy(buffer, &result, sizeof(buffer));
// Copy result to r0 and r1.
memcpy(registers_, buffer, sizeof(buffer));
}
}
void Simulator::TrashCallerSaveRegisters() {
// We don't trash the registers with the return value.
registers_[2] = 0x50Bad4U;
registers_[3] = 0x50Bad4U;
registers_[12] = 0x50Bad4U;
}
// Some Operating Systems allow unaligned access on ARMv7 targets. We
// assume that unaligned accesses are not allowed unless the v8 build system
// defines the CAN_USE_UNALIGNED_ACCESSES macro to be non-zero.
// The following statements below describes the behavior of the ARM CPUs
// that don't support unaligned access.
// Some ARM platforms raise an interrupt on detecting unaligned access.
// On others it does a funky rotation thing. For now we
// simply disallow unaligned reads. Note that simulator runs have the runtime
// system running directly on the host system and only generated code is
// executed in the simulator. Since the host is typically IA32 we will not
// get the correct ARM-like behaviour on unaligned accesses for those ARM
// targets that don't support unaligned loads and stores.
int Simulator::ReadW(int32_t addr, Instruction* instr) {
if (FLAG_enable_unaligned_accesses || (addr & 3) == 0) {
intptr_t* ptr = reinterpret_cast<intptr_t*>(addr);
return *ptr;
} else {
PrintF("Unaligned read at 0x%08x, pc=0x%08" V8PRIxPTR "\n",
addr,
reinterpret_cast<intptr_t>(instr));
UNIMPLEMENTED();
return 0;
}
}
void Simulator::WriteW(int32_t addr, int value, Instruction* instr) {
if (FLAG_enable_unaligned_accesses || (addr & 3) == 0) {
intptr_t* ptr = reinterpret_cast<intptr_t*>(addr);
*ptr = value;
} else {
PrintF("Unaligned write at 0x%08x, pc=0x%08" V8PRIxPTR "\n",
addr,
reinterpret_cast<intptr_t>(instr));
UNIMPLEMENTED();
}
}
uint16_t Simulator::ReadHU(int32_t addr, Instruction* instr) {
if (FLAG_enable_unaligned_accesses || (addr & 1) == 0) {
uint16_t* ptr = reinterpret_cast<uint16_t*>(addr);
return *ptr;
} else {
PrintF("Unaligned unsigned halfword read at 0x%08x, pc=0x%08"
V8PRIxPTR "\n",
addr,
reinterpret_cast<intptr_t>(instr));
UNIMPLEMENTED();
return 0;
}
}
int16_t Simulator::ReadH(int32_t addr, Instruction* instr) {
if (FLAG_enable_unaligned_accesses || (addr & 1) == 0) {
int16_t* ptr = reinterpret_cast<int16_t*>(addr);
return *ptr;
} else {
PrintF("Unaligned signed halfword read at 0x%08x\n", addr);
UNIMPLEMENTED();
return 0;
}
}
void Simulator::WriteH(int32_t addr, uint16_t value, Instruction* instr) {
if (FLAG_enable_unaligned_accesses || (addr & 1) == 0) {
uint16_t* ptr = reinterpret_cast<uint16_t*>(addr);
*ptr = value;
} else {
PrintF("Unaligned unsigned halfword write at 0x%08x, pc=0x%08"
V8PRIxPTR "\n",
addr,
reinterpret_cast<intptr_t>(instr));
UNIMPLEMENTED();
}
}
void Simulator::WriteH(int32_t addr, int16_t value, Instruction* instr) {
if (FLAG_enable_unaligned_accesses || (addr & 1) == 0) {
int16_t* ptr = reinterpret_cast<int16_t*>(addr);
*ptr = value;
} else {
PrintF("Unaligned halfword write at 0x%08x, pc=0x%08" V8PRIxPTR "\n",
addr,
reinterpret_cast<intptr_t>(instr));
UNIMPLEMENTED();
}
}
uint8_t Simulator::ReadBU(int32_t addr) {
uint8_t* ptr = reinterpret_cast<uint8_t*>(addr);
return *ptr;
}
int8_t Simulator::ReadB(int32_t addr) {
int8_t* ptr = reinterpret_cast<int8_t*>(addr);
return *ptr;
}
void Simulator::WriteB(int32_t addr, uint8_t value) {
uint8_t* ptr = reinterpret_cast<uint8_t*>(addr);
*ptr = value;
}
void Simulator::WriteB(int32_t addr, int8_t value) {
int8_t* ptr = reinterpret_cast<int8_t*>(addr);
*ptr = value;
}
int32_t* Simulator::ReadDW(int32_t addr) {
if (FLAG_enable_unaligned_accesses || (addr & 3) == 0) {
int32_t* ptr = reinterpret_cast<int32_t*>(addr);
return ptr;
} else {
PrintF("Unaligned read at 0x%08x\n", addr);
UNIMPLEMENTED();
return 0;
}
}
void Simulator::WriteDW(int32_t addr, int32_t value1, int32_t value2) {
if (FLAG_enable_unaligned_accesses || (addr & 3) == 0) {
int32_t* ptr = reinterpret_cast<int32_t*>(addr);
*ptr++ = value1;
*ptr = value2;
} else {
PrintF("Unaligned write at 0x%08x\n", addr);
UNIMPLEMENTED();
}
}
// Returns the limit of the stack area to enable checking for stack overflows.
uintptr_t Simulator::StackLimit() const {
// Leave a safety margin of 1024 bytes to prevent overrunning the stack when
// pushing values.
return reinterpret_cast<uintptr_t>(stack_) + 1024;
}
// Unsupported instructions use Format to print an error and stop execution.
void Simulator::Format(Instruction* instr, const char* format) {
PrintF("Simulator found unsupported instruction:\n 0x%08x: %s\n",
reinterpret_cast<intptr_t>(instr), format);
UNIMPLEMENTED();
}
// Checks if the current instruction should be executed based on its
// condition bits.
bool Simulator::ConditionallyExecute(Instruction* instr) {
switch (instr->ConditionField()) {
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;
}
// Calculate and set the Negative and Zero flags.
void Simulator::SetNZFlags(int32_t val) {
n_flag_ = (val < 0);
z_flag_ = (val == 0);
}
// Set the Carry flag.
void Simulator::SetCFlag(bool val) {
c_flag_ = val;
}
// Set the oVerflow flag.
void Simulator::SetVFlag(bool val) {
v_flag_ = val;
}
// Calculate C flag value for additions.
bool Simulator::CarryFrom(int32_t left, int32_t right, int32_t carry) {
uint32_t uleft = static_cast<uint32_t>(left);
uint32_t uright = static_cast<uint32_t>(right);
uint32_t urest = 0xffffffffU - uleft;
return (uright > urest) ||
(carry && (((uright + 1) > urest) || (uright > (urest - 1))));
}
// Calculate C flag value for subtractions.
bool Simulator::BorrowFrom(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::OverflowFrom(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;
}
// Support for VFP comparisons.
void Simulator::Compute_FPSCR_Flags(double val1, double val2) {
if (std::isnan(val1) || std::isnan(val2)) {
n_flag_FPSCR_ = false;
z_flag_FPSCR_ = false;
c_flag_FPSCR_ = true;
v_flag_FPSCR_ = true;
// All non-NaN cases.
} else if (val1 == val2) {
n_flag_FPSCR_ = false;
z_flag_FPSCR_ = true;
c_flag_FPSCR_ = true;
v_flag_FPSCR_ = false;
} else if (val1 < val2) {
n_flag_FPSCR_ = true;
z_flag_FPSCR_ = false;
c_flag_FPSCR_ = false;
v_flag_FPSCR_ = false;
} else {
// Case when (val1 > val2).
n_flag_FPSCR_ = false;
z_flag_FPSCR_ = false;
c_flag_FPSCR_ = true;
v_flag_FPSCR_ = false;
}
}
void Simulator::Copy_FPSCR_to_APSR() {
n_flag_ = n_flag_FPSCR_;
z_flag_ = z_flag_FPSCR_;
c_flag_ = c_flag_FPSCR_;
v_flag_ = v_flag_FPSCR_;
}
// Addressing Mode 1 - Data-processing operands:
// Get the value based on the shifter_operand with register.
int32_t Simulator::GetShiftRm(Instruction* instr, bool* carry_out) {
ShiftOp shift = instr->ShiftField();
int shift_amount = instr->ShiftAmountValue();
int32_t result = get_register(instr->RmValue());
if (instr->Bit(4) == 0) {
// by immediate
if ((shift == ROR) && (shift_amount == 0)) {
UNIMPLEMENTED();
return result;
} else if (((shift == LSR) || (shift == ASR)) && (shift_amount == 0)) {
shift_amount = 32;
}
switch (shift) {
case ASR: {
if (shift_amount == 0) {
if (result < 0) {
result = 0xffffffff;
*carry_out = true;
} else {
result = 0;
*carry_out = false;
}
} else {
result >>= (shift_amount - 1);
*carry_out = (result & 1) == 1;
result >>= 1;
}
break;
}
case LSL: {
if (shift_amount == 0) {
*carry_out = c_flag_;
} else {
result <<= (shift_amount - 1);
*carry_out = (result < 0);
result <<= 1;
}
break;
}
case LSR: {
if (shift_amount == 0) {
result = 0;
*carry_out = c_flag_;
} else {
uint32_t uresult = static_cast<uint32_t>(result);
uresult >>= (shift_amount - 1);
*carry_out = (uresult & 1) == 1;
uresult >>= 1;
result = static_cast<int32_t>(uresult);
}
break;
}
case ROR: {
if (shift_amount == 0) {
*carry_out = c_flag_;
} else {
uint32_t left = static_cast<uint32_t>(result) >> shift_amount;
uint32_t right = static_cast<uint32_t>(result) << (32 - shift_amount);
result = right | left;
*carry_out = (static_cast<uint32_t>(result) >> 31) != 0;
}
break;
}
default: {
UNREACHABLE();
break;
}
}
} else {
// by register
int rs = instr->RsValue();
shift_amount = get_register(rs) &0xff;
switch (shift) {
case ASR: {
if (shift_amount == 0) {
*carry_out = c_flag_;
} else if (shift_amount < 32) {
result >>= (shift_amount - 1);
*carry_out = (result & 1) == 1;
result >>= 1;
} else {
DCHECK(shift_amount >= 32);
if (result < 0) {
*carry_out = true;
result = 0xffffffff;
} else {
*carry_out = false;
result = 0;
}
}
break;
}
case LSL: {
if (shift_amount == 0) {
*carry_out = c_flag_;
} else if (shift_amount < 32) {
result <<= (shift_amount - 1);
*carry_out = (result < 0);
result <<= 1;
} else if (shift_amount == 32) {
*carry_out = (result & 1) == 1;
result = 0;
} else {
DCHECK(shift_amount > 32);
*carry_out = false;
result = 0;
}
break;
}
case LSR: {
if (shift_amount == 0) {
*carry_out = c_flag_;
} else if (shift_amount < 32) {
uint32_t uresult = static_cast<uint32_t>(result);
uresult >>= (shift_amount - 1);
*carry_out = (uresult & 1) == 1;
uresult >>= 1;
result = static_cast<int32_t>(uresult);
} else if (shift_amount == 32) {
*carry_out = (result < 0);
result = 0;
} else {
*carry_out = false;
result = 0;
}
break;
}
case ROR: {
if (shift_amount == 0) {
*carry_out = c_flag_;
} else {
uint32_t left = static_cast<uint32_t>(result) >> shift_amount;
uint32_t right = static_cast<uint32_t>(result) << (32 - shift_amount);
result = right | left;
*carry_out = (static_cast<uint32_t>(result) >> 31) != 0;
}
break;
}
default: {
UNREACHABLE();
break;
}
}
}
return result;
}
// Addressing Mode 1 - Data-processing operands:
// Get the value based on the shifter_operand with immediate.
int32_t Simulator::GetImm(Instruction* instr, bool* carry_out) {
int rotate = instr->RotateValue() * 2;
int immed8 = instr->Immed8Value();
int imm = (immed8 >> rotate) | (immed8 << (32 - rotate));
*carry_out = (rotate == 0) ? c_flag_ : (imm < 0);
return imm;
}
static int count_bits(int bit_vector) {
int count = 0;
while (bit_vector != 0) {
if ((bit_vector & 1) != 0) {
count++;
}
bit_vector >>= 1;
}
return count;
}
int32_t Simulator::ProcessPU(Instruction* instr,
int num_regs,
int reg_size,
intptr_t* start_address,
intptr_t* end_address) {
int rn = instr->RnValue();
int32_t rn_val = get_register(rn);
switch (instr->PUField()) {
case da_x: {
UNIMPLEMENTED();
break;
}
case ia_x: {
*start_address = rn_val;
*end_address = rn_val + (num_regs * reg_size) - reg_size;
rn_val = rn_val + (num_regs * reg_size);
break;
}
case db_x: {
*start_address = rn_val - (num_regs * reg_size);
*end_address = rn_val - reg_size;
rn_val = *start_address;
break;
}
case ib_x: {
*start_address = rn_val + reg_size;
*end_address = rn_val + (num_regs * reg_size);
rn_val = *end_address;
break;
}
default: {
UNREACHABLE();
break;
}
}
return rn_val;
}
// Addressing Mode 4 - Load and Store Multiple
void Simulator::HandleRList(Instruction* instr, bool load) {
int rlist = instr->RlistValue();
int num_regs = count_bits(rlist);
intptr_t start_address = 0;
intptr_t end_address = 0;
int32_t rn_val =
ProcessPU(instr, num_regs, kPointerSize, &start_address, &end_address);
intptr_t* address = reinterpret_cast<intptr_t*>(start_address);
// Catch null pointers a little earlier.
DCHECK(start_address > 8191 || start_address < 0);
int reg = 0;
while (rlist != 0) {
if ((rlist & 1) != 0) {
if (load) {
set_register(reg, *address);
} else {
*address = get_register(reg);
}
address += 1;
}
reg++;
rlist >>= 1;
}
DCHECK(end_address == ((intptr_t)address) - 4);
if (instr->HasW()) {
set_register(instr->RnValue(), rn_val);
}
}
// Addressing Mode 6 - Load and Store Multiple Coprocessor registers.
void Simulator::HandleVList(Instruction* instr) {
VFPRegPrecision precision =
(instr->SzValue() == 0) ? kSinglePrecision : kDoublePrecision;
int operand_size = (precision == kSinglePrecision) ? 4 : 8;
bool load = (instr->VLValue() == 0x1);
int vd;
int num_regs;
vd = instr->VFPDRegValue(precision);
if (precision == kSinglePrecision) {
num_regs = instr->Immed8Value();
} else {
num_regs = instr->Immed8Value() / 2;
}
intptr_t start_address = 0;
intptr_t end_address = 0;
int32_t rn_val =
ProcessPU(instr, num_regs, operand_size, &start_address, &end_address);
intptr_t* address = reinterpret_cast<intptr_t*>(start_address);
for (int reg = vd; reg < vd + num_regs; reg++) {
if (precision == kSinglePrecision) {
if (load) {
set_s_register_from_sinteger(
reg, ReadW(reinterpret_cast<int32_t>(address), instr));
} else {
WriteW(reinterpret_cast<int32_t>(address),
get_sinteger_from_s_register(reg), instr);
}
address += 1;
} else {
if (load) {
int32_t data[] = {
ReadW(reinterpret_cast<int32_t>(address), instr),
ReadW(reinterpret_cast<int32_t>(address + 1), instr)
};
double d;
memcpy(&d, data, 8);
set_d_register_from_double(reg, d);
} else {
int32_t data[2];
double d = get_double_from_d_register(reg);
memcpy(data, &d, 8);
WriteW(reinterpret_cast<int32_t>(address), data[0], instr);
WriteW(reinterpret_cast<int32_t>(address + 1), data[1], instr);
}
address += 2;
}
}
DCHECK(reinterpret_cast<intptr_t>(address) - operand_size == end_address);
if (instr->HasW()) {
set_register(instr->RnValue(), rn_val);
}
}
// Calls into the V8 runtime are based on this very simple interface.
// Note: To be able to return two values from some calls the code in runtime.cc
// uses the ObjectPair which is essentially two 32-bit values stuffed into a
// 64-bit value. With the code below we assume that all runtime calls return
// 64 bits of result. If they don't, the r1 result register contains a bogus
// value, which is fine because it is caller-saved.
typedef int64_t (*SimulatorRuntimeCall)(int32_t arg0,
int32_t arg1,
int32_t arg2,
int32_t arg3,
int32_t arg4,
int32_t arg5);
// These prototypes handle the four types of FP calls.
typedef int64_t (*SimulatorRuntimeCompareCall)(double darg0, double darg1);
typedef double (*SimulatorRuntimeFPFPCall)(double darg0, double darg1);
typedef double (*SimulatorRuntimeFPCall)(double darg0);
typedef double (*SimulatorRuntimeFPIntCall)(double darg0, int32_t arg0);
// This signature supports direct call in to API function native callback
// (refer to InvocationCallback in v8.h).
typedef void (*SimulatorRuntimeDirectApiCall)(int32_t arg0);
typedef void (*SimulatorRuntimeProfilingApiCall)(int32_t arg0, void* arg1);
// This signature supports direct call to accessor getter callback.
typedef void (*SimulatorRuntimeDirectGetterCall)(int32_t arg0, int32_t arg1);
typedef void (*SimulatorRuntimeProfilingGetterCall)(
int32_t arg0, int32_t arg1, void* arg2);
// Software interrupt instructions are used by the simulator to call into the
// C-based V8 runtime.
void Simulator::SoftwareInterrupt(Instruction* instr) {
int svc = instr->SvcValue();
switch (svc) {
case kCallRtRedirected: {
// Check if stack is aligned. Error if not aligned is reported below to
// include information on the function called.
bool stack_aligned =
(get_register(sp)
& (::v8::internal::FLAG_sim_stack_alignment - 1)) == 0;
Redirection* redirection = Redirection::FromSwiInstruction(instr);
int32_t arg0 = get_register(r0);
int32_t arg1 = get_register(r1);
int32_t arg2 = get_register(r2);
int32_t arg3 = get_register(r3);
int32_t* stack_pointer = reinterpret_cast<int32_t*>(get_register(sp));
int32_t arg4 = stack_pointer[0];
int32_t arg5 = stack_pointer[1];
bool fp_call =
(redirection->type() == ExternalReference::BUILTIN_FP_FP_CALL) ||
(redirection->type() == ExternalReference::BUILTIN_COMPARE_CALL) ||
(redirection->type() == ExternalReference::BUILTIN_FP_CALL) ||
(redirection->type() == ExternalReference::BUILTIN_FP_INT_CALL);
// This is dodgy but it works because the C entry stubs are never moved.
// See comment in codegen-arm.cc and bug 1242173.
int32_t saved_lr = get_register(lr);
intptr_t external =
reinterpret_cast<intptr_t>(redirection->external_function());
if (fp_call) {
double dval0, dval1; // one or two double parameters
int32_t ival; // zero or one integer parameters
int64_t iresult = 0; // integer return value
double dresult = 0; // double return value
GetFpArgs(&dval0, &dval1, &ival);
if (::v8::internal::FLAG_trace_sim || !stack_aligned) {
SimulatorRuntimeCall generic_target =
reinterpret_cast<SimulatorRuntimeCall>(external);
switch (redirection->type()) {
case ExternalReference::BUILTIN_FP_FP_CALL:
case ExternalReference::BUILTIN_COMPARE_CALL:
PrintF("Call to host function at %p with args %f, %f",
FUNCTION_ADDR(generic_target), dval0, dval1);
break;
case ExternalReference::BUILTIN_FP_CALL:
PrintF("Call to host function at %p with arg %f",
FUNCTION_ADDR(generic_target), dval0);
break;
case ExternalReference::BUILTIN_FP_INT_CALL:
PrintF("Call to host function at %p with args %f, %d",
FUNCTION_ADDR(generic_target), dval0, ival);
break;
default:
UNREACHABLE();
break;
}
if (!stack_aligned) {
PrintF(" with unaligned stack %08x\n", get_register(sp));
}
PrintF("\n");
}
CHECK(stack_aligned);
switch (redirection->type()) {
case ExternalReference::BUILTIN_COMPARE_CALL: {
SimulatorRuntimeCompareCall target =
reinterpret_cast<SimulatorRuntimeCompareCall>(external);
iresult = target(dval0, dval1);
set_register(r0, static_cast<int32_t>(iresult));
set_register(r1, static_cast<int32_t>(iresult >> 32));
break;
}
case ExternalReference::BUILTIN_FP_FP_CALL: {
SimulatorRuntimeFPFPCall target =
reinterpret_cast<SimulatorRuntimeFPFPCall>(external);
dresult = target(dval0, dval1);
SetFpResult(dresult);
break;
}
case ExternalReference::BUILTIN_FP_CALL: {
SimulatorRuntimeFPCall target =
reinterpret_cast<SimulatorRuntimeFPCall>(external);
dresult = target(dval0);
SetFpResult(dresult);
break;
}
case ExternalReference::BUILTIN_FP_INT_CALL: {
SimulatorRuntimeFPIntCall target =
reinterpret_cast<SimulatorRuntimeFPIntCall>(external);
dresult = target(dval0, ival);
SetFpResult(dresult);
break;
}
default:
UNREACHABLE();
break;
}
if (::v8::internal::FLAG_trace_sim || !stack_aligned) {
switch (redirection->type()) {
case ExternalReference::BUILTIN_COMPARE_CALL:
PrintF("Returned %08x\n", static_cast<int32_t>(iresult));
break;
case ExternalReference::BUILTIN_FP_FP_CALL:
case ExternalReference::BUILTIN_FP_CALL:
case ExternalReference::BUILTIN_FP_INT_CALL:
PrintF("Returned %f\n", dresult);
break;
default:
UNREACHABLE();
break;
}
}
} else if (redirection->type() == ExternalReference::DIRECT_API_CALL) {
if (::v8::internal::FLAG_trace_sim || !stack_aligned) {
PrintF("Call to host function at %p args %08x",
reinterpret_cast<void*>(external), arg0);
if (!stack_aligned) {
PrintF(" with unaligned stack %08x\n", get_register(sp));
}
PrintF("\n");
}
CHECK(stack_aligned);
SimulatorRuntimeDirectApiCall target =
reinterpret_cast<SimulatorRuntimeDirectApiCall>(external);
target(arg0);
} else if (
redirection->type() == ExternalReference::PROFILING_API_CALL) {
if (::v8::internal::FLAG_trace_sim || !stack_aligned) {
PrintF("Call to host function at %p args %08x %08x",
reinterpret_cast<void*>(external), arg0, arg1);
if (!stack_aligned) {
PrintF(" with unaligned stack %08x\n", get_register(sp));
}
PrintF("\n");
}
CHECK(stack_aligned);
SimulatorRuntimeProfilingApiCall target =
reinterpret_cast<SimulatorRuntimeProfilingApiCall>(external);
target(arg0, Redirection::ReverseRedirection(arg1));
} else if (
redirection->type() == ExternalReference::DIRECT_GETTER_CALL) {
if (::v8::internal::FLAG_trace_sim || !stack_aligned) {
PrintF("Call to host function at %p args %08x %08x",
reinterpret_cast<void*>(external), arg0, arg1);
if (!stack_aligned) {
PrintF(" with unaligned stack %08x\n", get_register(sp));
}
PrintF("\n");
}
CHECK(stack_aligned);
SimulatorRuntimeDirectGetterCall target =
reinterpret_cast<SimulatorRuntimeDirectGetterCall>(external);
target(arg0, arg1);
} else if (
redirection->type() == ExternalReference::PROFILING_GETTER_CALL) {
if (::v8::internal::FLAG_trace_sim || !stack_aligned) {
PrintF("Call to host function at %p args %08x %08x %08x",
reinterpret_cast<void*>(external), arg0, arg1, arg2);
if (!stack_aligned) {
PrintF(" with unaligned stack %08x\n", get_register(sp));
}
PrintF("\n");
}
CHECK(stack_aligned);
SimulatorRuntimeProfilingGetterCall target =
reinterpret_cast<SimulatorRuntimeProfilingGetterCall>(
external);
target(arg0, arg1, Redirection::ReverseRedirection(arg2));
} else {
// builtin call.
DCHECK(redirection->type() == ExternalReference::BUILTIN_CALL);
SimulatorRuntimeCall target =
reinterpret_cast<SimulatorRuntimeCall>(external);
if (::v8::internal::FLAG_trace_sim || !stack_aligned) {
PrintF(
"Call to host function at %p "
"args %08x, %08x, %08x, %08x, %08x, %08x",
FUNCTION_ADDR(target),
arg0,
arg1,
arg2,
arg3,
arg4,
arg5);
if (!stack_aligned) {
PrintF(" with unaligned stack %08x\n", get_register(sp));
}
PrintF("\n");
}
CHECK(stack_aligned);
int64_t result = target(arg0, arg1, arg2, arg3, arg4, arg5);
int32_t lo_res = static_cast<int32_t>(result);
int32_t hi_res = static_cast<int32_t>(result >> 32);
if (::v8::internal::FLAG_trace_sim) {
PrintF("Returned %08x\n", lo_res);
}
set_register(r0, lo_res);
set_register(r1, hi_res);
}
set_register(lr, saved_lr);
set_pc(get_register(lr));
break;
}
case kBreakpoint: {
ArmDebugger dbg(this);
dbg.Debug();
break;
}
// stop uses all codes greater than 1 << 23.
default: {
if (svc >= (1 << 23)) {
uint32_t code = svc & kStopCodeMask;
if (isWatchedStop(code)) {
IncreaseStopCounter(code);
}
// Stop if it is enabled, otherwise go on jumping over the stop
// and the message address.
if (isEnabledStop(code)) {
ArmDebugger dbg(this);
dbg.Stop(instr);
} else {
set_pc(get_pc() + 2 * Instruction::kInstrSize);
}
} else {
// This is not a valid svc code.
UNREACHABLE();
break;
}
}
}
}
double Simulator::canonicalizeNaN(double value) {
return (FPSCR_default_NaN_mode_ && std::isnan(value)) ?
FixedDoubleArray::canonical_not_the_hole_nan_as_double() : value;
}
// Stop helper functions.
bool Simulator::isStopInstruction(Instruction* instr) {
return (instr->Bits(27, 24) == 0xF) && (instr->SvcValue() >= kStopCode);
}
bool Simulator::isWatchedStop(uint32_t code) {
DCHECK(code <= kMaxStopCode);
return code < kNumOfWatchedStops;
}
bool Simulator::isEnabledStop(uint32_t code) {
DCHECK(code <= kMaxStopCode);
// Unwatched stops are always enabled.
return !isWatchedStop(code) ||
!(watched_stops_[code].count & kStopDisabledBit);
}
void Simulator::EnableStop(uint32_t code) {
DCHECK(isWatchedStop(code));
if (!isEnabledStop(code)) {
watched_stops_[code].count &= ~kStopDisabledBit;
}
}
void Simulator::DisableStop(uint32_t code) {
DCHECK(isWatchedStop(code));
if (isEnabledStop(code)) {
watched_stops_[code].count |= kStopDisabledBit;
}
}
void Simulator::IncreaseStopCounter(uint32_t code) {
DCHECK(code <= kMaxStopCode);
DCHECK(isWatchedStop(code));
if ((watched_stops_[code].count & ~(1 << 31)) == 0x7fffffff) {
PrintF("Stop counter for code %i has overflowed.\n"
"Enabling this code and reseting the counter to 0.\n", code);
watched_stops_[code].count = 0;
EnableStop(code);
} else {
watched_stops_[code].count++;
}
}
// Print a stop status.
void Simulator::PrintStopInfo(uint32_t code) {
DCHECK(code <= kMaxStopCode);
if (!isWatchedStop(code)) {
PrintF("Stop not watched.");
} else {
const char* state = isEnabledStop(code) ? "Enabled" : "Disabled";
int32_t count = watched_stops_[code].count & ~kStopDisabledBit;
// Don't print the state of unused breakpoints.
if (count != 0) {
if (watched_stops_[code].desc) {
PrintF("stop %i - 0x%x: \t%s, \tcounter = %i, \t%s\n",
code, code, state, count, watched_stops_[code].desc);
} else {
PrintF("stop %i - 0x%x: \t%s, \tcounter = %i\n",
code, code, state, count);
}
}
}
}
// Handle execution based on instruction types.
// Instruction types 0 and 1 are both rolled into one function because they
// only differ in the handling of the shifter_operand.
void Simulator::DecodeType01(Instruction* instr) {
int type = instr->TypeValue();
if ((type == 0) && instr->IsSpecialType0()) {
// multiply instruction or extra loads and stores
if (instr->Bits(7, 4) == 9) {
if (instr->Bit(24) == 0) {
// Raw field decoding here. Multiply instructions have their Rd in
// funny places.
int rn = instr->RnValue();
int rm = instr->RmValue();
int rs = instr->RsValue();
int32_t rs_val = get_register(rs);
int32_t rm_val = get_register(rm);
if (instr->Bit(23) == 0) {
if (instr->Bit(21) == 0) {
// The MUL instruction description (A 4.1.33) refers to Rd as being
// the destination for the operation, but it confusingly uses the
// Rn field to encode it.
// Format(instr, "mul'cond's 'rn, 'rm, 'rs");
int rd = rn; // Remap the rn field to the Rd register.
int32_t alu_out = rm_val * rs_val;
set_register(rd, alu_out);
if (instr->HasS()) {
SetNZFlags(alu_out);
}
} else {
int rd = instr->RdValue();
int32_t acc_value = get_register(rd);
if (instr->Bit(22) == 0) {
// The MLA instruction description (A 4.1.28) refers to the order
// of registers as "Rd, Rm, Rs, Rn". But confusingly it uses the
// Rn field to encode the Rd register and the Rd field to encode
// the Rn register.
// Format(instr, "mla'cond's 'rn, 'rm, 'rs, 'rd");
int32_t mul_out = rm_val * rs_val;
int32_t result = acc_value + mul_out;
set_register(rn, result);
} else {
// Format(instr, "mls'cond's 'rn, 'rm, 'rs, 'rd");
int32_t mul_out = rm_val * rs_val;
int32_t result = acc_value - mul_out;
set_register(rn, result);
}
}
} else {
// The signed/long multiply instructions use the terms RdHi and RdLo
// when referring to the target registers. They are mapped to the Rn
// and Rd fields as follows:
// RdLo == Rd
// RdHi == Rn (This is confusingly stored in variable rd here
// because the mul instruction from above uses the
// Rn field to encode the Rd register. Good luck figuring
// this out without reading the ARM instruction manual
// at a very detailed level.)
// Format(instr, "'um'al'cond's 'rd, 'rn, 'rs, 'rm");
int rd_hi = rn; // Remap the rn field to the RdHi register.
int rd_lo = instr->RdValue();
int32_t hi_res = 0;
int32_t lo_res = 0;
if (instr->Bit(22) == 1) {
int64_t left_op = static_cast<int32_t>(rm_val);
int64_t right_op = static_cast<int32_t>(rs_val);
uint64_t result = left_op * right_op;
hi_res = static_cast<int32_t>(result >> 32);
lo_res = static_cast<int32_t>(result & 0xffffffff);
} else {
// unsigned multiply
uint64_t left_op = static_cast<uint32_t>(rm_val);
uint64_t right_op = static_cast<uint32_t>(rs_val);
uint64_t result = left_op * right_op;
hi_res = static_cast<int32_t>(result >> 32);
lo_res = static_cast<int32_t>(result & 0xffffffff);
}
set_register(rd_lo, lo_res);
set_register(rd_hi, hi_res);
if (instr->HasS()) {
UNIMPLEMENTED();
}
}
} else {
UNIMPLEMENTED(); // Not used by V8.
}
} else {
// extra load/store instructions
int rd = instr->RdValue();
int rn = instr->RnValue();
int32_t rn_val = get_register(rn);
int32_t addr = 0;
if (instr->Bit(22) == 0) {
int rm = instr->RmValue();
int32_t rm_val = get_register(rm);
switch (instr->PUField()) {
case da_x: {
// Format(instr, "'memop'cond'sign'h 'rd, ['rn], -'rm");
DCHECK(!instr->HasW());
addr = rn_val;
rn_val -= rm_val;
set_register(rn, rn_val);
break;
}
case ia_x: {
// Format(instr, "'memop'cond'sign'h 'rd, ['rn], +'rm");
DCHECK(!instr->HasW());
addr = rn_val;
rn_val += rm_val;
set_register(rn, rn_val);
break;
}
case db_x: {
// Format(instr, "'memop'cond'sign'h 'rd, ['rn, -'rm]'w");
rn_val -= rm_val;
addr = rn_val;
if (instr->HasW()) {
set_register(rn, rn_val);
}
break;
}
case ib_x: {
// Format(instr, "'memop'cond'sign'h 'rd, ['rn, +'rm]'w");
rn_val += rm_val;
addr = rn_val;
if (instr->HasW()) {
set_register(rn, rn_val);
}
break;
}
default: {
// The PU field is a 2-bit field.
UNREACHABLE();
break;
}
}
} else {
int32_t imm_val = (instr->ImmedHValue() << 4) | instr->ImmedLValue();
switch (instr->PUField()) {
case da_x: {
// Format(instr, "'memop'cond'sign'h 'rd, ['rn], #-'off8");
DCHECK(!instr->HasW());
addr = rn_val;
rn_val -= imm_val;
set_register(rn, rn_val);
break;
}
case ia_x: {
// Format(instr, "'memop'cond'sign'h 'rd, ['rn], #+'off8");
DCHECK(!instr->HasW());
addr = rn_val;
rn_val += imm_val;
set_register(rn, rn_val);
break;
}
case db_x: {
// Format(instr, "'memop'cond'sign'h 'rd, ['rn, #-'off8]'w");
rn_val -= imm_val;
addr = rn_val;
if (instr->HasW()) {
set_register(rn, rn_val);
}
break;
}
case ib_x: {
// Format(instr, "'memop'cond'sign'h 'rd, ['rn, #+'off8]'w");
rn_val += imm_val;
addr = rn_val;
if (instr->HasW()) {
set_register(rn, rn_val);
}
break;
}
default: {
// The PU field is a 2-bit field.
UNREACHABLE();
break;
}
}
}
if (((instr->Bits(7, 4) & 0xd) == 0xd) && (instr->Bit(20) == 0)) {
DCHECK((rd % 2) == 0);
if (instr->HasH()) {
// The strd instruction.
int32_t value1 = get_register(rd);
int32_t value2 = get_register(rd+1);
WriteDW(addr, value1, value2);
} else {
// The ldrd instruction.
int* rn_data = ReadDW(addr);
set_dw_register(rd, rn_data);
}
} else if (instr->HasH()) {
if (instr->HasSign()) {
if (instr->HasL()) {
int16_t val = ReadH(addr, instr);
set_register(rd, val);
} else {
int16_t val = get_register(rd);
WriteH(addr, val, instr);
}
} else {
if (instr->HasL()) {
uint16_t val = ReadHU(addr, instr);
set_register(rd, val);
} else {
uint16_t val = get_register(rd);
WriteH(addr, val, instr);
}
}
} else {
// signed byte loads
DCHECK(instr->HasSign());
DCHECK(instr->HasL());
int8_t val = ReadB(addr);
set_register(rd, val);
}
return;
}
} else if ((type == 0) && instr->IsMiscType0()) {
if (instr->Bits(22, 21) == 1) {
int rm = instr->RmValue();
switch (instr->BitField(7, 4)) {
case BX:
set_pc(get_register(rm));
break;
case BLX: {
uint32_t old_pc = get_pc();
set_pc(get_register(rm));
set_register(lr, old_pc + Instruction::kInstrSize);
break;
}
case BKPT: {
ArmDebugger dbg(this);
PrintF("Simulator hit BKPT.\n");
dbg.Debug();
break;
}
default:
UNIMPLEMENTED();
}
} else if (instr->Bits(22, 21) == 3) {
int rm = instr->RmValue();
int rd = instr->RdValue();
switch (instr->BitField(7, 4)) {
case CLZ: {
uint32_t bits = get_register(rm);
int leading_zeros = 0;
if (bits == 0) {
leading_zeros = 32;
} else {
while ((bits & 0x80000000u) == 0) {
bits <<= 1;
leading_zeros++;
}
}
set_register(rd, leading_zeros);
break;
}
default:
UNIMPLEMENTED();
}
} else {
PrintF("%08x\n", instr->InstructionBits());
UNIMPLEMENTED();
}
} else if ((type == 1) && instr->IsNopType1()) {
// NOP.
} else {
int rd = instr->RdValue();
int rn = instr->RnValue();
int32_t rn_val = get_register(rn);
int32_t shifter_operand = 0;
bool shifter_carry_out = 0;
if (type == 0) {
shifter_operand = GetShiftRm(instr, &shifter_carry_out);
} else {
DCHECK(instr->TypeValue() == 1);
shifter_operand = GetImm(instr, &shifter_carry_out);
}
int32_t alu_out;
switch (instr->OpcodeField()) {
case AND: {
// Format(instr, "and'cond's 'rd, 'rn, 'shift_rm");
// Format(instr, "and'cond's 'rd, 'rn, 'imm");
alu_out = rn_val & shifter_operand;
set_register(rd, alu_out);
if (instr->HasS()) {
SetNZFlags(alu_out);
SetCFlag(shifter_carry_out);
}
break;
}
case EOR: {
// Format(instr, "eor'cond's 'rd, 'rn, 'shift_rm");
// Format(instr, "eor'cond's 'rd, 'rn, 'imm");
alu_out = rn_val ^ shifter_operand;
set_register(rd, alu_out);
if (instr->HasS()) {
SetNZFlags(alu_out);
SetCFlag(shifter_carry_out);
}
break;
}
case SUB: {
// Format(instr, "sub'cond's 'rd, 'rn, 'shift_rm");
// Format(instr, "sub'cond's 'rd, 'rn, 'imm");
alu_out = rn_val - shifter_operand;
set_register(rd, alu_out);
if (instr->HasS()) {
SetNZFlags(alu_out);
SetCFlag(!BorrowFrom(rn_val, shifter_operand));
SetVFlag(OverflowFrom(alu_out, rn_val, shifter_operand, false));
}
break;
}
case RSB: {
// Format(instr, "rsb'cond's 'rd, 'rn, 'shift_rm");
// Format(instr, "rsb'cond's 'rd, 'rn, 'imm");
alu_out = shifter_operand - rn_val;
set_register(rd, alu_out);
if (instr->HasS()) {
SetNZFlags(alu_out);
SetCFlag(!BorrowFrom(shifter_operand, rn_val));
SetVFlag(OverflowFrom(alu_out, shifter_operand, rn_val, false));
}
break;
}
case ADD: {
// Format(instr, "add'cond's 'rd, 'rn, 'shift_rm");
// Format(instr, "add'cond's 'rd, 'rn, 'imm");
alu_out = rn_val + shifter_operand;
set_register(rd, alu_out);
if (instr->HasS()) {
SetNZFlags(alu_out);
SetCFlag(CarryFrom(rn_val, shifter_operand));
SetVFlag(OverflowFrom(alu_out, rn_val, shifter_operand, true));
}
break;
}
case ADC: {
// Format(instr, "adc'cond's 'rd, 'rn, 'shift_rm");
// Format(instr, "adc'cond's 'rd, 'rn, 'imm");
alu_out = rn_val + shifter_operand + GetCarry();
set_register(rd, alu_out);
if (instr->HasS()) {
SetNZFlags(alu_out);
SetCFlag(CarryFrom(rn_val, shifter_operand, GetCarry()));
SetVFlag(OverflowFrom(alu_out, rn_val, shifter_operand, true));
}
break;
}
case SBC: {
Format(instr, "sbc'cond's 'rd, 'rn, 'shift_rm");
Format(instr, "sbc'cond's 'rd, 'rn, 'imm");
break;
}
case RSC: {
Format(instr, "rsc'cond's 'rd, 'rn, 'shift_rm");
Format(instr, "rsc'cond's 'rd, 'rn, 'imm");
break;
}
case TST: {
if (instr->HasS()) {
// Format(instr, "tst'cond 'rn, 'shift_rm");
// Format(instr, "tst'cond 'rn, 'imm");
alu_out = rn_val & shifter_operand;
SetNZFlags(alu_out);
SetCFlag(shifter_carry_out);
} else {
// Format(instr, "movw'cond 'rd, 'imm").
alu_out = instr->ImmedMovwMovtValue();
set_register(rd, alu_out);
}
break;
}
case TEQ: {
if (instr->HasS()) {
// Format(instr, "teq'cond 'rn, 'shift_rm");
// Format(instr, "teq'cond 'rn, 'imm");
alu_out = rn_val ^ shifter_operand;
SetNZFlags(alu_out);
SetCFlag(shifter_carry_out);
} else {
// Other instructions matching this pattern are handled in the
// miscellaneous instructions part above.
UNREACHABLE();
}
break;
}
case CMP: {
if (instr->HasS()) {
// Format(instr, "cmp'cond 'rn, 'shift_rm");
// Format(instr, "cmp'cond 'rn, 'imm");
alu_out = rn_val - shifter_operand;
SetNZFlags(alu_out);
SetCFlag(!BorrowFrom(rn_val, shifter_operand));
SetVFlag(OverflowFrom(alu_out, rn_val, shifter_operand, false));
} else {
// Format(instr, "movt'cond 'rd, 'imm").
alu_out = (get_register(rd) & 0xffff) |
(instr->ImmedMovwMovtValue() << 16);
set_register(rd, alu_out);
}
break;
}
case CMN: {
if (instr->HasS()) {
// Format(instr, "cmn'cond 'rn, 'shift_rm");
// Format(instr, "cmn'cond 'rn, 'imm");
alu_out = rn_val + shifter_operand;
SetNZFlags(alu_out);
SetCFlag(CarryFrom(rn_val, shifter_operand));
SetVFlag(OverflowFrom(alu_out, rn_val, shifter_operand, true));
} else {
// Other instructions matching this pattern are handled in the
// miscellaneous instructions part above.
UNREACHABLE();
}
break;
}
case ORR: {
// Format(instr, "orr'cond's 'rd, 'rn, 'shift_rm");
// Format(instr, "orr'cond's 'rd, 'rn, 'imm");
alu_out = rn_val | shifter_operand;
set_register(rd, alu_out);
if (instr->HasS()) {
SetNZFlags(alu_out);
SetCFlag(shifter_carry_out);
}
break;
}
case MOV: {
// Format(instr, "mov'cond's 'rd, 'shift_rm");
// Format(instr, "mov'cond's 'rd, 'imm");
alu_out = shifter_operand;
set_register(rd, alu_out);
if (instr->HasS()) {
SetNZFlags(alu_out);
SetCFlag(shifter_carry_out);
}
break;
}
case BIC: {
// Format(instr, "bic'cond's 'rd, 'rn, 'shift_rm");
// Format(instr, "bic'cond's 'rd, 'rn, 'imm");
alu_out = rn_val & ~shifter_operand;
set_register(rd, alu_out);
if (instr->HasS()) {
SetNZFlags(alu_out);
SetCFlag(shifter_carry_out);
}
break;
}
case MVN: {
// Format(instr, "mvn'cond's 'rd, 'shift_rm");
// Format(instr, "mvn'cond's 'rd, 'imm");
alu_out = ~shifter_operand;
set_register(rd, alu_out);
if (instr->HasS()) {
SetNZFlags(alu_out);
SetCFlag(shifter_carry_out);
}
break;
}
default: {
UNREACHABLE();
break;
}
}
}
}
void Simulator::DecodeType2(Instruction* instr) {
int rd = instr->RdValue();
int rn = instr->RnValue();
int32_t rn_val = get_register(rn);
int32_t im_val = instr->Offset12Value();
int32_t addr = 0;
switch (instr->PUField()) {
case da_x: {
// Format(instr, "'memop'cond'b 'rd, ['rn], #-'off12");
DCHECK(!instr->HasW());
addr = rn_val;
rn_val -= im_val;
set_register(rn, rn_val);
break;
}
case ia_x: {
// Format(instr, "'memop'cond'b 'rd, ['rn], #+'off12");
DCHECK(!instr->HasW());
addr = rn_val;
rn_val += im_val;
set_register(rn, rn_val);
break;
}
case db_x: {
// Format(instr, "'memop'cond'b 'rd, ['rn, #-'off12]'w");
rn_val -= im_val;
addr = rn_val;
if (instr->HasW()) {
set_register(rn, rn_val);
}
break;
}
case ib_x: {
// Format(instr, "'memop'cond'b 'rd, ['rn, #+'off12]'w");
rn_val += im_val;
addr = rn_val;
if (instr->HasW()) {
set_register(rn, rn_val);
}
break;
}
default: {
UNREACHABLE();
break;
}
}
if (instr->HasB()) {
if (instr->HasL()) {
byte val = ReadBU(addr);
set_register(rd, val);
} else {
byte val = get_register(rd);
WriteB(addr, val);
}
} else {
if (instr->HasL()) {
set_register(rd, ReadW(addr, instr));
} else {
WriteW(addr, get_register(rd), instr);
}
}
}
void Simulator::DecodeType3(Instruction* instr) {
int rd = instr->RdValue();
int rn = instr->RnValue();
int32_t rn_val = get_register(rn);
bool shifter_carry_out = 0;
int32_t shifter_operand = GetShiftRm(instr, &shifter_carry_out);
int32_t addr = 0;
switch (instr->PUField()) {
case da_x: {
DCHECK(!instr->HasW());
Format(instr, "'memop'cond'b 'rd, ['rn], -'shift_rm");
UNIMPLEMENTED();
break;
}
case ia_x: {
if (instr->Bit(4) == 0) {
// Memop.
} else {
if (instr->Bit(5) == 0) {
switch (instr->Bits(22, 21)) {
case 0:
if (instr->Bit(20) == 0) {
if (instr->Bit(6) == 0) {
// Pkhbt.
uint32_t rn_val = get_register(rn);
uint32_t rm_val = get_register(instr->RmValue());
int32_t shift = instr->Bits(11, 7);
rm_val <<= shift;
set_register(rd, (rn_val & 0xFFFF) | (rm_val & 0xFFFF0000U));
} else {
// Pkhtb.
uint32_t rn_val = get_register(rn);
int32_t rm_val = get_register(instr->RmValue());
int32_t shift = instr->Bits(11, 7);
if (shift == 0) {
shift = 32;
}
rm_val >>= shift;
set_register(rd, (rn_val & 0xFFFF0000U) | (rm_val & 0xFFFF));
}
} else {
UNIMPLEMENTED();
}
break;
case 1:
UNIMPLEMENTED();
break;
case 2:
UNIMPLEMENTED();
break;
case 3: {
// Usat.
int32_t sat_pos = instr->Bits(20, 16);
int32_t sat_val = (1 << sat_pos) - 1;
int32_t shift = instr->Bits(11, 7);
int32_t shift_type = instr->Bit(6);
int32_t rm_val = get_register(instr->RmValue());
if (shift_type == 0) { // LSL
rm_val <<= shift;
} else { // ASR
rm_val >>= shift;
}
// If saturation occurs, the Q flag should be set in the CPSR.
// There is no Q flag yet, and no instruction (MRS) to read the
// CPSR directly.
if (rm_val > sat_val) {
rm_val = sat_val;
} else if (rm_val < 0) {
rm_val = 0;
}
set_register(rd, rm_val);
break;
}
}
} else {
switch (instr->Bits(22, 21)) {
case 0:
UNIMPLEMENTED();
break;
case 1:
UNIMPLEMENTED();
break;
case 2:
if ((instr->Bit(20) == 0) && (instr->Bits(9, 6) == 1)) {
if (instr->Bits(19, 16) == 0xF) {
// Uxtb16.
uint32_t rm_val = get_register(instr->RmValue());
int32_t rotate = instr->Bits(11, 10);
switch (rotate) {
case 0:
break;
case 1:
rm_val = (rm_val >> 8) | (rm_val << 24);
break;
case 2:
rm_val = (rm_val >> 16) | (rm_val << 16);
break;
case 3:
rm_val = (rm_val >> 24) | (rm_val << 8);
break;
}
set_register(rd,
(rm_val & 0xFF) | (rm_val & 0xFF0000));
} else {
UNIMPLEMENTED();
}
} else {
UNIMPLEMENTED();
}
break;
case 3:
if ((instr->Bit(20) == 0) && (instr->Bits(9, 6) == 1)) {
if (instr->Bits(19, 16) == 0xF) {
// Uxtb.
uint32_t rm_val = get_register(instr->RmValue());
int32_t rotate = instr->Bits(11, 10);
switch (rotate) {
case 0:
break;
case 1:
rm_val = (rm_val >> 8) | (rm_val << 24);
break;
case 2:
rm_val = (rm_val >> 16) | (rm_val << 16);
break;
case 3:
rm_val = (rm_val >> 24) | (rm_val << 8);
break;
}
set_register(rd, (rm_val & 0xFF));
} else {
// Uxtab.
uint32_t rn_val = get_register(rn);
uint32_t rm_val = get_register(instr->RmValue());
int32_t rotate = instr->Bits(11, 10);
switch (rotate) {
case 0:
break;
case 1:
rm_val = (rm_val >> 8) | (rm_val << 24);
break;
case 2:
rm_val = (rm_val >> 16) | (rm_val << 16);
break;
case 3:
rm_val = (rm_val >> 24) | (rm_val << 8);
break;
}
set_register(rd, rn_val + (rm_val & 0xFF));
}
} else {
UNIMPLEMENTED();
}
break;
}
}
return;
}
break;
}
case db_x: {
if (FLAG_enable_sudiv) {
if (instr->Bits(5, 4) == 0x1) {
if ((instr->Bit(22) == 0x0) && (instr->Bit(20) == 0x1)) {
// (s/u)div (in V8 notation matching ARM ISA format) rn = rm/rs
// Format(instr, "'(s/u)div'cond'b 'rn, 'rm, 'rs);
int rm = instr->RmValue();
int32_t rm_val = get_register(rm);
int rs = instr->RsValue();
int32_t rs_val = get_register(rs);
int32_t ret_val = 0;
DCHECK(rs_val != 0);
// udiv
if (instr->Bit(21) == 0x1) {
ret_val = static_cast<int32_t>(static_cast<uint32_t>(rm_val) /
static_cast<uint32_t>(rs_val));
} else if ((rm_val == kMinInt) && (rs_val == -1)) {
ret_val = kMinInt;
} else {
ret_val = rm_val / rs_val;
}
set_register(rn, ret_val);
return;
}
}
}
// Format(instr, "'memop'cond'b 'rd, ['rn, -'shift_rm]'w");
addr = rn_val - shifter_operand;
if (instr->HasW()) {
set_register(rn, addr);
}
break;
}
case ib_x: {
if (instr->HasW() && (instr->Bits(6, 4) == 0x5)) {
uint32_t widthminus1 = static_cast<uint32_t>(instr->Bits(20, 16));
uint32_t lsbit = static_cast<uint32_t>(instr->Bits(11, 7));
uint32_t msbit = widthminus1 + lsbit;
if (msbit <= 31) {
if (instr->Bit(22)) {
// ubfx - unsigned bitfield extract.
uint32_t rm_val =
static_cast<uint32_t>(get_register(instr->RmValue()));
uint32_t extr_val = rm_val << (31 - msbit);
extr_val = extr_val >> (31 - widthminus1);
set_register(instr->RdValue(), extr_val);
} else {
// sbfx - signed bitfield extract.
int32_t rm_val = get_register(instr->RmValue());
int32_t extr_val = rm_val << (31 - msbit);
extr_val = extr_val >> (31 - widthminus1);
set_register(instr->RdValue(), extr_val);
}
} else {
UNREACHABLE();
}
return;
} else if (!instr->HasW() && (instr->Bits(6, 4) == 0x1)) {
uint32_t lsbit = static_cast<uint32_t>(instr->Bits(11, 7));
uint32_t msbit = static_cast<uint32_t>(instr->Bits(20, 16));
if (msbit >= lsbit) {
// bfc or bfi - bitfield clear/insert.
uint32_t rd_val =
static_cast<uint32_t>(get_register(instr->RdValue()));
uint32_t bitcount = msbit - lsbit + 1;
uint32_t mask = 0xffffffffu >> (32 - bitcount);
rd_val &= ~(mask << lsbit);
if (instr->RmValue() != 15) {
// bfi - bitfield insert.
uint32_t rm_val =
static_cast<uint32_t>(get_register(instr->RmValue()));
rm_val &= mask;
rd_val |= rm_val << lsbit;
}
set_register(instr->RdValue(), rd_val);
} else {
UNREACHABLE();
}
return;
} else {
// Format(instr, "'memop'cond'b 'rd, ['rn, +'shift_rm]'w");
addr = rn_val + shifter_operand;
if (instr->HasW()) {
set_register(rn, addr);
}
}
break;
}
default: {
UNREACHABLE();
break;
}
}
if (instr->HasB()) {
if (instr->HasL()) {
uint8_t byte = ReadB(addr);
set_register(rd, byte);
} else {
uint8_t byte = get_register(rd);
WriteB(addr, byte);
}
} else {
if (instr->HasL()) {
set_register(rd, ReadW(addr, instr));
} else {
WriteW(addr, get_register(rd), instr);
}
}
}
void Simulator::DecodeType4(Instruction* instr) {
DCHECK(instr->Bit(22) == 0); // only allowed to be set in privileged mode
if (instr->HasL()) {
// Format(instr, "ldm'cond'pu 'rn'w, 'rlist");
HandleRList(instr, true);
} else {
// Format(instr, "stm'cond'pu 'rn'w, 'rlist");
HandleRList(instr, false);
}
}
void Simulator::DecodeType5(Instruction* instr) {
// Format(instr, "b'l'cond 'target");
int off = (instr->SImmed24Value() << 2);
intptr_t pc_address = get_pc();
if (instr->HasLink()) {
set_register(lr, pc_address + Instruction::kInstrSize);
}
int pc_reg = get_register(pc);
set_pc(pc_reg + off);
}
void Simulator::DecodeType6(Instruction* instr) {
DecodeType6CoprocessorIns(instr);
}
void Simulator::DecodeType7(Instruction* instr) {
if (instr->Bit(24) == 1) {
SoftwareInterrupt(instr);
} else {
DecodeTypeVFP(instr);
}
}
// void Simulator::DecodeTypeVFP(Instruction* instr)
// The Following ARMv7 VFPv instructions are currently supported.
// vmov :Sn = Rt
// vmov :Rt = Sn
// vcvt: Dd = Sm
// vcvt: Sd = Dm
// vcvt.f64.s32 Dd, Dd, #<fbits>
// Dd = vabs(Dm)
// Dd = vneg(Dm)
// Dd = vadd(Dn, Dm)
// Dd = vsub(Dn, Dm)
// Dd = vmul(Dn, Dm)
// Dd = vdiv(Dn, Dm)
// vcmp(Dd, Dm)
// vmrs
// Dd = vsqrt(Dm)
void Simulator::DecodeTypeVFP(Instruction* instr) {
DCHECK((instr->TypeValue() == 7) && (instr->Bit(24) == 0x0) );
DCHECK(instr->Bits(11, 9) == 0x5);
// Obtain double precision register codes.
int vm = instr->VFPMRegValue(kDoublePrecision);
int vd = instr->VFPDRegValue(kDoublePrecision);
int vn = instr->VFPNRegValue(kDoublePrecision);
if (instr->Bit(4) == 0) {
if (instr->Opc1Value() == 0x7) {
// Other data processing instructions
if ((instr->Opc2Value() == 0x0) && (instr->Opc3Value() == 0x1)) {
// vmov register to register.
if (instr->SzValue() == 0x1) {
int m = instr->VFPMRegValue(kDoublePrecision);
int d = instr->VFPDRegValue(kDoublePrecision);
set_d_register_from_double(d, get_double_from_d_register(m));
} else {
int m = instr->VFPMRegValue(kSinglePrecision);
int d = instr->VFPDRegValue(kSinglePrecision);
set_s_register_from_float(d, get_float_from_s_register(m));
}
} else if ((instr->Opc2Value() == 0x0) && (instr->Opc3Value() == 0x3)) {
// vabs
double dm_value = get_double_from_d_register(vm);
double dd_value = std::fabs(dm_value);
dd_value = canonicalizeNaN(dd_value);
set_d_register_from_double(vd, dd_value);
} else if ((instr->Opc2Value() == 0x1) && (instr->Opc3Value() == 0x1)) {
// vneg
double dm_value = get_double_from_d_register(vm);
double dd_value = -dm_value;
dd_value = canonicalizeNaN(dd_value);
set_d_register_from_double(vd, dd_value);
} else if ((instr->Opc2Value() == 0x7) && (instr->Opc3Value() == 0x3)) {
DecodeVCVTBetweenDoubleAndSingle(instr);
} else if ((instr->Opc2Value() == 0x8) && (instr->Opc3Value() & 0x1)) {
DecodeVCVTBetweenFloatingPointAndInteger(instr);
} else if ((instr->Opc2Value() == 0xA) && (instr->Opc3Value() == 0x3) &&
(instr->Bit(8) == 1)) {
// vcvt.f64.s32 Dd, Dd, #<fbits>
int fraction_bits = 32 - ((instr->Bits(3, 0) << 1) | instr->Bit(5));
int fixed_value = get_sinteger_from_s_register(vd * 2);
double divide = 1 << fraction_bits;
set_d_register_from_double(vd, fixed_value / divide);
} else if (((instr->Opc2Value() >> 1) == 0x6) &&
(instr->Opc3Value() & 0x1)) {
DecodeVCVTBetweenFloatingPointAndInteger(instr);
} else if (((instr->Opc2Value() == 0x4) || (instr->Opc2Value() == 0x5)) &&
(instr->Opc3Value() & 0x1)) {
DecodeVCMP(instr);
} else if (((instr->Opc2Value() == 0x1)) && (instr->Opc3Value() == 0x3)) {
// vsqrt
double dm_value = get_double_from_d_register(vm);
double dd_value = std::sqrt(dm_value);
dd_value = canonicalizeNaN(dd_value);
set_d_register_from_double(vd, dd_value);
} else if (instr->Opc3Value() == 0x0) {
// vmov immediate.
if (instr->SzValue() == 0x1) {
set_d_register_from_double(vd, instr->DoubleImmedVmov());
} else {
UNREACHABLE(); // Not used by v8.
}
} else {
UNREACHABLE(); // Not used by V8.
}
} else if (instr->Opc1Value() == 0x3) {
if (instr->SzValue() != 0x1) {
UNREACHABLE(); // Not used by V8.
}
if (instr->Opc3Value() & 0x1) {
// vsub
double dn_value = get_double_from_d_register(vn);
double dm_value = get_double_from_d_register(vm);
double dd_value = dn_value - dm_value;
dd_value = canonicalizeNaN(dd_value);
set_d_register_from_double(vd, dd_value);
} else {
// vadd
double dn_value = get_double_from_d_register(vn);
double dm_value = get_double_from_d_register(vm);
double dd_value = dn_value + dm_value;
dd_value = canonicalizeNaN(dd_value);
set_d_register_from_double(vd, dd_value);
}
} else if ((instr->Opc1Value() == 0x2) && !(instr->Opc3Value() & 0x1)) {
// vmul
if (instr->SzValue() != 0x1) {
UNREACHABLE(); // Not used by V8.
}
double dn_value = get_double_from_d_register(vn);
double dm_value = get_double_from_d_register(vm);
double dd_value = dn_value * dm_value;
dd_value = canonicalizeNaN(dd_value);
set_d_register_from_double(vd, dd_value);
} else if ((instr->Opc1Value() == 0x0)) {
// vmla, vmls
const bool is_vmls = (instr->Opc3Value() & 0x1);
if (instr->SzValue() != 0x1) {
UNREACHABLE(); // Not used by V8.
}
const double dd_val = get_double_from_d_register(vd);
const double dn_val = get_double_from_d_register(vn);
const double dm_val = get_double_from_d_register(vm);
// Note: we do the mul and add/sub in separate steps to avoid getting a
// result with too high precision.
set_d_register_from_double(vd, dn_val * dm_val);
if (is_vmls) {
set_d_register_from_double(
vd,
canonicalizeNaN(dd_val - get_double_from_d_register(vd)));
} else {
set_d_register_from_double(
vd,
canonicalizeNaN(dd_val + get_double_from_d_register(vd)));
}
} else if ((instr->Opc1Value() == 0x4) && !(instr->Opc3Value() & 0x1)) {
// vdiv
if (instr->SzValue() != 0x1) {
UNREACHABLE(); // Not used by V8.
}
double dn_value = get_double_from_d_register(vn);
double dm_value = get_double_from_d_register(vm);
double dd_value = dn_value / dm_value;
div_zero_vfp_flag_ = (dm_value == 0);
dd_value = canonicalizeNaN(dd_value);
set_d_register_from_double(vd, dd_value);
} else {
UNIMPLEMENTED(); // Not used by V8.
}
} else {
if ((instr->VCValue() == 0x0) &&
(instr->VAValue() == 0x0)) {
DecodeVMOVBetweenCoreAndSinglePrecisionRegisters(instr);
} else if ((instr->VLValue() == 0x0) &&
(instr->VCValue() == 0x1) &&
(instr->Bit(23) == 0x0)) {
// vmov (ARM core register to scalar)
int vd = instr->Bits(19, 16) | (instr->Bit(7) << 4);
double dd_value = get_double_from_d_register(vd);
int32_t data[2];
memcpy(data, &dd_value, 8);
data[instr->Bit(21)] = get_register(instr->RtValue());
memcpy(&dd_value, data, 8);
set_d_register_from_double(vd, dd_value);
} else if ((instr->VLValue() == 0x1) &&
(instr->VCValue() == 0x1) &&
(instr->Bit(23) == 0x0)) {
// vmov (scalar to ARM core register)
int vn = instr->Bits(19, 16) | (instr->Bit(7) << 4);
double dn_value = get_double_from_d_register(vn);
int32_t data[2];
memcpy(data, &dn_value, 8);
set_register(instr->RtValue(), data[instr->Bit(21)]);
} else if ((instr->VLValue() == 0x1) &&
(instr->VCValue() == 0x0) &&
(instr->VAValue() == 0x7) &&
(instr->Bits(19, 16) == 0x1)) {
// vmrs
uint32_t rt = instr->RtValue();
if (rt == 0xF) {
Copy_FPSCR_to_APSR();
} else {
// Emulate FPSCR from the Simulator flags.
uint32_t fpscr = (n_flag_FPSCR_ << 31) |
(z_flag_FPSCR_ << 30) |
(c_flag_FPSCR_ << 29) |
(v_flag_FPSCR_ << 28) |
(FPSCR_default_NaN_mode_ << 25) |
(inexact_vfp_flag_ << 4) |
(underflow_vfp_flag_ << 3) |
(overflow_vfp_flag_ << 2) |
(div_zero_vfp_flag_ << 1) |
(inv_op_vfp_flag_ << 0) |
(FPSCR_rounding_mode_);
set_register(rt, fpscr);
}
} else if ((instr->VLValue() == 0x0) &&
(instr->VCValue() == 0x0) &&
(instr->VAValue() == 0x7) &&
(instr->Bits(19, 16) == 0x1)) {
// vmsr
uint32_t rt = instr->RtValue();
if (rt == pc) {
UNREACHABLE();
} else {
uint32_t rt_value = get_register(rt);
n_flag_FPSCR_ = (rt_value >> 31) & 1;
z_flag_FPSCR_ = (rt_value >> 30) & 1;
c_flag_FPSCR_ = (rt_value >> 29) & 1;
v_flag_FPSCR_ = (rt_value >> 28) & 1;
FPSCR_default_NaN_mode_ = (rt_value >> 25) & 1;
inexact_vfp_flag_ = (rt_value >> 4) & 1;
underflow_vfp_flag_ = (rt_value >> 3) & 1;
overflow_vfp_flag_ = (rt_value >> 2) & 1;
div_zero_vfp_flag_ = (rt_value >> 1) & 1;
inv_op_vfp_flag_ = (rt_value >> 0) & 1;
FPSCR_rounding_mode_ =
static_cast<VFPRoundingMode>((rt_value) & kVFPRoundingModeMask);
}
} else {
UNIMPLEMENTED(); // Not used by V8.
}
}
}
void Simulator::DecodeVMOVBetweenCoreAndSinglePrecisionRegisters(
Instruction* instr) {
DCHECK((instr->Bit(4) == 1) && (instr->VCValue() == 0x0) &&
(instr->VAValue() == 0x0));
int t = instr->RtValue();
int n = instr->VFPNRegValue(kSinglePrecision);
bool to_arm_register = (instr->VLValue() == 0x1);
if (to_arm_register) {
int32_t int_value = get_sinteger_from_s_register(n);
set_register(t, int_value);
} else {
int32_t rs_val = get_register(t);
set_s_register_from_sinteger(n, rs_val);
}
}
void Simulator::DecodeVCMP(Instruction* instr) {
DCHECK((instr->Bit(4) == 0) && (instr->Opc1Value() == 0x7));
DCHECK(((instr->Opc2Value() == 0x4) || (instr->Opc2Value() == 0x5)) &&
(instr->Opc3Value() & 0x1));
// Comparison.
VFPRegPrecision precision = kSinglePrecision;
if (instr->SzValue() == 1) {
precision = kDoublePrecision;
}
int d = instr->VFPDRegValue(precision);
int m = 0;
if (instr->Opc2Value() == 0x4) {
m = instr->VFPMRegValue(precision);
}
if (precision == kDoublePrecision) {
double dd_value = get_double_from_d_register(d);
double dm_value = 0.0;
if (instr->Opc2Value() == 0x4) {
dm_value = get_double_from_d_register(m);
}
// Raise exceptions for quiet NaNs if necessary.
if (instr->Bit(7) == 1) {
if (std::isnan(dd_value)) {
inv_op_vfp_flag_ = true;
}
}
Compute_FPSCR_Flags(dd_value, dm_value);
} else {
UNIMPLEMENTED(); // Not used by V8.
}
}
void Simulator::DecodeVCVTBetweenDoubleAndSingle(Instruction* instr) {
DCHECK((instr->Bit(4) == 0) && (instr->Opc1Value() == 0x7));
DCHECK((instr->Opc2Value() == 0x7) && (instr->Opc3Value() == 0x3));
VFPRegPrecision dst_precision = kDoublePrecision;
VFPRegPrecision src_precision = kSinglePrecision;
if (instr->SzValue() == 1) {
dst_precision = kSinglePrecision;
src_precision = kDoublePrecision;
}
int dst = instr->VFPDRegValue(dst_precision);
int src = instr->VFPMRegValue(src_precision);
if (dst_precision == kSinglePrecision) {
double val = get_double_from_d_register(src);
set_s_register_from_float(dst, static_cast<float>(val));
} else {
float val = get_float_from_s_register(src);
set_d_register_from_double(dst, static_cast<double>(val));
}
}
bool get_inv_op_vfp_flag(VFPRoundingMode mode,
double val,
bool unsigned_) {
DCHECK((mode == RN) || (mode == RM) || (mode == RZ));
double max_uint = static_cast<double>(0xffffffffu);
double max_int = static_cast<double>(kMaxInt);
double min_int = static_cast<double>(kMinInt);
// Check for NaN.
if (val != val) {
return true;
}
// Check for overflow. This code works because 32bit integers can be
// exactly represented by ieee-754 64bit floating-point values.
switch (mode) {
case RN:
return unsigned_ ? (val >= (max_uint + 0.5)) ||
(val < -0.5)
: (val >= (max_int + 0.5)) ||
(val < (min_int - 0.5));
case RM:
return unsigned_ ? (val >= (max_uint + 1.0)) ||
(val < 0)
: (val >= (max_int + 1.0)) ||
(val < min_int);
case RZ:
return unsigned_ ? (val >= (max_uint + 1.0)) ||
(val <= -1)
: (val >= (max_int + 1.0)) ||
(val <= (min_int - 1.0));
default:
UNREACHABLE();
return true;
}
}
// We call this function only if we had a vfp invalid exception.
// It returns the correct saturated value.
int VFPConversionSaturate(double val, bool unsigned_res) {
if (val != val) {
return 0;
} else {
if (unsigned_res) {
return (val < 0) ? 0 : 0xffffffffu;
} else {
return (val < 0) ? kMinInt : kMaxInt;
}
}
}
void Simulator::DecodeVCVTBetweenFloatingPointAndInteger(Instruction* instr) {
DCHECK((instr->Bit(4) == 0) && (instr->Opc1Value() == 0x7) &&
(instr->Bits(27, 23) == 0x1D));
DCHECK(((instr->Opc2Value() == 0x8) && (instr->Opc3Value() & 0x1)) ||
(((instr->Opc2Value() >> 1) == 0x6) && (instr->Opc3Value() & 0x1)));
// Conversion between floating-point and integer.
bool to_integer = (instr->Bit(18) == 1);
VFPRegPrecision src_precision = (instr->SzValue() == 1) ? kDoublePrecision
: kSinglePrecision;
if (to_integer) {
// We are playing with code close to the C++ standard's limits below,
// hence the very simple code and heavy checks.
//
// Note:
// C++ defines default type casting from floating point to integer as
// (close to) rounding toward zero ("fractional part discarded").
int dst = instr->VFPDRegValue(kSinglePrecision);
int src = instr->VFPMRegValue(src_precision);
// Bit 7 in vcvt instructions indicates if we should use the FPSCR rounding
// mode or the default Round to Zero mode.
VFPRoundingMode mode = (instr->Bit(7) != 1) ? FPSCR_rounding_mode_
: RZ;
DCHECK((mode == RM) || (mode == RZ) || (mode == RN));
bool unsigned_integer = (instr->Bit(16) == 0);
bool double_precision = (src_precision == kDoublePrecision);
double val = double_precision ? get_double_from_d_register(src)
: get_float_from_s_register(src);
int temp = unsigned_integer ? static_cast<uint32_t>(val)
: static_cast<int32_t>(val);
inv_op_vfp_flag_ = get_inv_op_vfp_flag(mode, val, unsigned_integer);
double abs_diff =
unsigned_integer ? std::fabs(val - static_cast<uint32_t>(temp))
: std::fabs(val - temp);
inexact_vfp_flag_ = (abs_diff != 0);
if (inv_op_vfp_flag_) {
temp = VFPConversionSaturate(val, unsigned_integer);
} else {
switch (mode) {
case RN: {
int val_sign = (val > 0) ? 1 : -1;
if (abs_diff > 0.5) {
temp += val_sign;
} else if (abs_diff == 0.5) {
// Round to even if exactly halfway.
temp = ((temp % 2) == 0) ? temp : temp + val_sign;
}
break;
}
case RM:
temp = temp > val ? temp - 1 : temp;
break;
case RZ:
// Nothing to do.
break;
default:
UNREACHABLE();
}
}
// Update the destination register.
set_s_register_from_sinteger(dst, temp);
} else {
bool unsigned_integer = (instr->Bit(7) == 0);
int dst = instr->VFPDRegValue(src_precision);
int src = instr->VFPMRegValue(kSinglePrecision);
int val = get_sinteger_from_s_register(src);
if (src_precision == kDoublePrecision) {
if (unsigned_integer) {
set_d_register_from_double(
dst, static_cast<double>(static_cast<uint32_t>(val)));
} else {
set_d_register_from_double(dst, static_cast<double>(val));
}
} else {
if (unsigned_integer) {
set_s_register_from_float(
dst, static_cast<float>(static_cast<uint32_t>(val)));
} else {
set_s_register_from_float(dst, static_cast<float>(val));
}
}
}
}
// void Simulator::DecodeType6CoprocessorIns(Instruction* instr)
// Decode Type 6 coprocessor instructions.
// Dm = vmov(Rt, Rt2)
// <Rt, Rt2> = vmov(Dm)
// Ddst = MEM(Rbase + 4*offset).
// MEM(Rbase + 4*offset) = Dsrc.
void Simulator::DecodeType6CoprocessorIns(Instruction* instr) {
DCHECK((instr->TypeValue() == 6));
if (instr->CoprocessorValue() == 0xA) {
switch (instr->OpcodeValue()) {
case 0x8:
case 0xA:
case 0xC:
case 0xE: { // Load and store single precision float to memory.
int rn = instr->RnValue();
int vd = instr->VFPDRegValue(kSinglePrecision);
int offset = instr->Immed8Value();
if (!instr->HasU()) {
offset = -offset;
}
int32_t address = get_register(rn) + 4 * offset;
if (instr->HasL()) {
// Load double from memory: vldr.
set_s_register_from_sinteger(vd, ReadW(address, instr));
} else {
// Store double to memory: vstr.
WriteW(address, get_sinteger_from_s_register(vd), instr);
}
break;
}
case 0x4:
case 0x5:
case 0x6:
case 0x7:
case 0x9:
case 0xB:
// Load/store multiple single from memory: vldm/vstm.
HandleVList(instr);
break;
default:
UNIMPLEMENTED(); // Not used by V8.
}
} else if (instr->CoprocessorValue() == 0xB) {
switch (instr->OpcodeValue()) {
case 0x2:
// Load and store double to two GP registers
if (instr->Bits(7, 6) != 0 || instr->Bit(4) != 1) {
UNIMPLEMENTED(); // Not used by V8.
} else {
int rt = instr->RtValue();
int rn = instr->RnValue();
int vm = instr->VFPMRegValue(kDoublePrecision);
if (instr->HasL()) {
int32_t data[2];
double d = get_double_from_d_register(vm);
memcpy(data, &d, 8);
set_register(rt, data[0]);
set_register(rn, data[1]);
} else {
int32_t data[] = { get_register(rt), get_register(rn) };
double d;
memcpy(&d, data, 8);
set_d_register_from_double(vm, d);
}
}
break;
case 0x8:
case 0xA:
case 0xC:
case 0xE: { // Load and store double to memory.
int rn = instr->RnValue();
int vd = instr->VFPDRegValue(kDoublePrecision);
int offset = instr->Immed8Value();
if (!instr->HasU()) {
offset = -offset;
}
int32_t address = get_register(rn) + 4 * offset;
if (instr->HasL()) {
// Load double from memory: vldr.
int32_t data[] = {
ReadW(address, instr),
ReadW(address + 4, instr)
};
double val;
memcpy(&val, data, 8);
set_d_register_from_double(vd, val);
} else {
// Store double to memory: vstr.
int32_t data[2];
double val = get_double_from_d_register(vd);
memcpy(data, &val, 8);
WriteW(address, data[0], instr);
WriteW(address + 4, data[1], instr);
}
break;
}
case 0x4:
case 0x5:
case 0x6:
case 0x7:
case 0x9:
case 0xB:
// Load/store multiple double from memory: vldm/vstm.
HandleVList(instr);
break;
default:
UNIMPLEMENTED(); // Not used by V8.
}
} else {
UNIMPLEMENTED(); // Not used by V8.
}
}
void Simulator::DecodeSpecialCondition(Instruction* instr) {
switch (instr->SpecialValue()) {
case 5:
if ((instr->Bits(18, 16) == 0) && (instr->Bits(11, 6) == 0x28) &&
(instr->Bit(4) == 1)) {
// vmovl signed
if ((instr->VdValue() & 1) != 0) UNIMPLEMENTED();
int Vd = (instr->Bit(22) << 3) | (instr->VdValue() >> 1);
int Vm = (instr->Bit(5) << 4) | instr->VmValue();
int imm3 = instr->Bits(21, 19);
if ((imm3 != 1) && (imm3 != 2) && (imm3 != 4)) UNIMPLEMENTED();
int esize = 8 * imm3;
int elements = 64 / esize;
int8_t from[8];
get_d_register(Vm, reinterpret_cast<uint64_t*>(from));
int16_t to[8];
int e = 0;
while (e < elements) {
to[e] = from[e];
e++;
}
set_q_register(Vd, reinterpret_cast<uint64_t*>(to));
} else {
UNIMPLEMENTED();
}
break;
case 7:
if ((instr->Bits(18, 16) == 0) && (instr->Bits(11, 6) == 0x28) &&
(instr->Bit(4) == 1)) {
// vmovl unsigned
if ((instr->VdValue() & 1) != 0) UNIMPLEMENTED();
int Vd = (instr->Bit(22) << 3) | (instr->VdValue() >> 1);
int Vm = (instr->Bit(5) << 4) | instr->VmValue();
int imm3 = instr->Bits(21, 19);
if ((imm3 != 1) && (imm3 != 2) && (imm3 != 4)) UNIMPLEMENTED();
int esize = 8 * imm3;
int elements = 64 / esize;
uint8_t from[8];
get_d_register(Vm, reinterpret_cast<uint64_t*>(from));
uint16_t to[8];
int e = 0;
while (e < elements) {
to[e] = from[e];
e++;
}
set_q_register(Vd, reinterpret_cast<uint64_t*>(to));
} else {
UNIMPLEMENTED();
}
break;
case 8:
if (instr->Bits(21, 20) == 0) {
// vst1
int Vd = (instr->Bit(22) << 4) | instr->VdValue();
int Rn = instr->VnValue();
int type = instr->Bits(11, 8);
int Rm = instr->VmValue();
int32_t address = get_register(Rn);
int regs = 0;
switch (type) {
case nlt_1:
regs = 1;
break;
case nlt_2:
regs = 2;
break;
case nlt_3:
regs = 3;
break;
case nlt_4:
regs = 4;
break;
default:
UNIMPLEMENTED();
break;
}
int r = 0;
while (r < regs) {
uint32_t data[2];
get_d_register(Vd + r, data);
WriteW(address, data[0], instr);
WriteW(address + 4, data[1], instr);
address += 8;
r++;
}
if (Rm != 15) {
if (Rm == 13) {
set_register(Rn, address);
} else {
set_register(Rn, get_register(Rn) + get_register(Rm));
}
}
} else if (instr->Bits(21, 20) == 2) {
// vld1
int Vd = (instr->Bit(22) << 4) | instr->VdValue();
int Rn = instr->VnValue();
int type = instr->Bits(11, 8);
int Rm = instr->VmValue();
int32_t address = get_register(Rn);
int regs = 0;
switch (type) {
case nlt_1:
regs = 1;
break;
case nlt_2:
regs = 2;
break;
case nlt_3:
regs = 3;
break;
case nlt_4:
regs = 4;
break;
default:
UNIMPLEMENTED();
break;
}
int r = 0;
while (r < regs) {
uint32_t data[2];
data[0] = ReadW(address, instr);
data[1] = ReadW(address + 4, instr);
set_d_register(Vd + r, data);
address += 8;
r++;
}
if (Rm != 15) {
if (Rm == 13) {
set_register(Rn, address);
} else {
set_register(Rn, get_register(Rn) + get_register(Rm));
}
}
} else {
UNIMPLEMENTED();
}
break;
case 0xA:
case 0xB:
if ((instr->Bits(22, 20) == 5) && (instr->Bits(15, 12) == 0xf)) {
// pld: ignore instruction.
} else {
UNIMPLEMENTED();
}
break;
default:
UNIMPLEMENTED();
break;
}
}
// Executes the current instruction.
void Simulator::InstructionDecode(Instruction* instr) {
if (v8::internal::FLAG_check_icache) {
CheckICache(isolate_->simulator_i_cache(), instr);
}
pc_modified_ = false;
if (::v8::internal::FLAG_trace_sim) {
disasm::NameConverter converter;
disasm::Disassembler dasm(converter);
// use a reasonably large buffer
v8::internal::EmbeddedVector<char, 256> buffer;
dasm.InstructionDecode(buffer,
reinterpret_cast<byte*>(instr));
PrintF(" 0x%08x %s\n", reinterpret_cast<intptr_t>(instr), buffer.start());
}
if (instr->ConditionField() == kSpecialCondition) {
DecodeSpecialCondition(instr);
} else if (ConditionallyExecute(instr)) {
switch (instr->TypeValue()) {
case 0:
case 1: {
DecodeType01(instr);
break;
}
case 2: {
DecodeType2(instr);
break;
}
case 3: {
DecodeType3(instr);
break;
}
case 4: {
DecodeType4(instr);
break;
}
case 5: {
DecodeType5(instr);
break;
}
case 6: {
DecodeType6(instr);
break;
}
case 7: {
DecodeType7(instr);
break;
}
default: {
UNIMPLEMENTED();
break;
}
}
// If the instruction is a non taken conditional stop, we need to skip the
// inlined message address.
} else if (instr->IsStop()) {
set_pc(get_pc() + 2 * Instruction::kInstrSize);
}
if (!pc_modified_) {
set_register(pc, reinterpret_cast<int32_t>(instr)
+ Instruction::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.
int program_counter = get_pc();
if (::v8::internal::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 != end_sim_pc) {
Instruction* instr = reinterpret_cast<Instruction*>(program_counter);
icount_++;
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 instuction count.
while (program_counter != end_sim_pc) {
Instruction* instr = reinterpret_cast<Instruction*>(program_counter);
icount_++;
if (icount_ == ::v8::internal::FLAG_stop_sim_at) {
ArmDebugger dbg(this);
dbg.Debug();
} else {
InstructionDecode(instr);
}
program_counter = get_pc();
}
}
}
void Simulator::CallInternal(byte* entry) {
// Prepare to execute the code at entry
set_register(pc, reinterpret_cast<int32_t>(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, end_sim_pc);
// Remember the values of callee-saved registers.
// The code below assumes that r9 is not used as sb (static base) in
// simulator code and therefore is regarded as a callee-saved register.
int32_t r4_val = get_register(r4);
int32_t r5_val = get_register(r5);
int32_t r6_val = get_register(r6);
int32_t r7_val = get_register(r7);
int32_t r8_val = get_register(r8);
int32_t r9_val = get_register(r9);
int32_t r10_val = get_register(r10);
int32_t r11_val = get_register(r11);
// Set up the callee-saved registers with a known value. To be able to check
// that they are preserved properly across JS execution.
int32_t callee_saved_value = icount_;
set_register(r4, callee_saved_value);
set_register(r5, callee_saved_value);
set_register(r6, callee_saved_value);
set_register(r7, callee_saved_value);
set_register(r8, callee_saved_value);
set_register(r9, callee_saved_value);
set_register(r10, callee_saved_value);
set_register(r11, callee_saved_value);
// Start the simulation
Execute();
// Check that the callee-saved registers have been preserved.
CHECK_EQ(callee_saved_value, get_register(r4));
CHECK_EQ(callee_saved_value, get_register(r5));
CHECK_EQ(callee_saved_value, get_register(r6));
CHECK_EQ(callee_saved_value, get_register(r7));
CHECK_EQ(callee_saved_value, get_register(r8));
CHECK_EQ(callee_saved_value, get_register(r9));
CHECK_EQ(callee_saved_value, get_register(r10));
CHECK_EQ(callee_saved_value, get_register(r11));
// Restore callee-saved registers with the original value.
set_register(r4, r4_val);
set_register(r5, r5_val);
set_register(r6, r6_val);
set_register(r7, r7_val);
set_register(r8, r8_val);
set_register(r9, r9_val);
set_register(r10, r10_val);
set_register(r11, r11_val);
}
int32_t Simulator::Call(byte* entry, int argument_count, ...) {
va_list parameters;
va_start(parameters, argument_count);
// Set up arguments
// First four arguments passed in registers.
DCHECK(argument_count >= 4);
set_register(r0, va_arg(parameters, int32_t));
set_register(r1, va_arg(parameters, int32_t));
set_register(r2, va_arg(parameters, int32_t));
set_register(r3, va_arg(parameters, int32_t));
// Remaining arguments passed on stack.
int original_stack = get_register(sp);
// Compute position of stack on entry to generated code.
int entry_stack = (original_stack - (argument_count - 4) * sizeof(int32_t));
if (base::OS::ActivationFrameAlignment() != 0) {
entry_stack &= -base::OS::ActivationFrameAlignment();
}
// Store remaining arguments on stack, from low to high memory.
intptr_t* stack_argument = reinterpret_cast<intptr_t*>(entry_stack);
for (int i = 4; i < argument_count; i++) {
stack_argument[i - 4] = va_arg(parameters, int32_t);
}
va_end(parameters);
set_register(sp, entry_stack);
CallInternal(entry);
// Pop stack passed arguments.
CHECK_EQ(entry_stack, get_register(sp));
set_register(sp, original_stack);
int32_t result = get_register(r0);
return result;
}
void Simulator::CallFP(byte* entry, double d0, double d1) {
if (use_eabi_hardfloat()) {
set_d_register_from_double(0, d0);
set_d_register_from_double(1, d1);
} else {
set_register_pair_from_double(0, &d0);
set_register_pair_from_double(2, &d1);
}
CallInternal(entry);
}
int32_t Simulator::CallFPReturnsInt(byte* entry, double d0, double d1) {
CallFP(entry, d0, d1);
int32_t result = get_register(r0);
return result;
}
double Simulator::CallFPReturnsDouble(byte* entry, double d0, double d1) {
CallFP(entry, d0, d1);
if (use_eabi_hardfloat()) {
return get_double_from_d_register(0);
} else {
return get_double_from_register_pair(0);
}
}
uintptr_t Simulator::PushAddress(uintptr_t address) {
int new_sp = get_register(sp) - sizeof(uintptr_t);
uintptr_t* stack_slot = reinterpret_cast<uintptr_t*>(new_sp);
*stack_slot = address;
set_register(sp, new_sp);
return new_sp;
}
uintptr_t Simulator::PopAddress() {
int current_sp = get_register(sp);
uintptr_t* stack_slot = reinterpret_cast<uintptr_t*>(current_sp);
uintptr_t address = *stack_slot;
set_register(sp, current_sp + sizeof(uintptr_t));
return address;
}
} } // namespace v8::internal
#endif // USE_SIMULATOR
#endif // V8_TARGET_ARCH_ARM