// Copyright 2010 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include <stdlib.h>
#include <cstdarg>
#include "v8.h"
#include "disasm.h"
#include "assembler.h"
#include "arm/constants-arm.h"
#include "arm/simulator-arm.h"
#if !defined(__arm__)
// Only build the simulator if not compiling for real ARM hardware.
namespace assembler {
namespace arm {
using ::v8::internal::Object;
using ::v8::internal::PrintF;
using ::v8::internal::OS;
using ::v8::internal::ReadLine;
using ::v8::internal::DeleteArray;
// 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 Debugger class is used by the simulator while debugging simulated ARM
// code.
class Debugger {
public:
explicit Debugger(Simulator* sim);
~Debugger();
void Stop(Instr* instr);
void Debug();
private:
static const instr_t kBreakpointInstr =
((AL << 28) | (7 << 25) | (1 << 24) | break_point);
static const instr_t kNopInstr =
((AL << 28) | (13 << 21));
Simulator* sim_;
int32_t GetRegisterValue(int regnum);
bool GetValue(const char* desc, int32_t* value);
// Set or delete a breakpoint. Returns true if successful.
bool SetBreakpoint(Instr* breakpc);
bool DeleteBreakpoint(Instr* 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();
};
Debugger::Debugger(Simulator* sim) {
sim_ = sim;
}
Debugger::~Debugger() {
}
#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 Debugger::Stop(Instr* instr) {
char* str = reinterpret_cast<char*>(instr->InstructionBits() & 0x0fffffff);
if (strlen(str) > 0) {
if (coverage_log != NULL) {
fprintf(coverage_log, "%s\n", str);
fflush(coverage_log);
}
instr->SetInstructionBits(0xe1a00000); // Overwrite with nop.
}
sim_->set_pc(sim_->get_pc() + Instr::kInstrSize);
}
#else // ndef GENERATED_CODE_COVERAGE
static void InitializeCoverage() {
}
void Debugger::Stop(Instr* instr) {
const char* str = (const char*)(instr->InstructionBits() & 0x0fffffff);
PrintF("Simulator hit %s\n", str);
sim_->set_pc(sim_->get_pc() + Instr::kInstrSize);
Debug();
}
#endif
int32_t Debugger::GetRegisterValue(int regnum) {
if (regnum == kPCRegister) {
return sim_->get_pc();
} else {
return sim_->get_register(regnum);
}
}
bool Debugger::GetValue(const char* desc, int32_t* value) {
int regnum = Registers::Number(desc);
if (regnum != kNoRegister) {
*value = GetRegisterValue(regnum);
return true;
} else {
return SScanF(desc, "%i", value) == 1;
}
return false;
}
bool Debugger::SetBreakpoint(Instr* 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 Debugger::DeleteBreakpoint(Instr* breakpc) {
if (sim_->break_pc_ != NULL) {
sim_->break_pc_->SetInstructionBits(sim_->break_instr_);
}
sim_->break_pc_ = NULL;
sim_->break_instr_ = 0;
return true;
}
void Debugger::UndoBreakpoints() {
if (sim_->break_pc_ != NULL) {
sim_->break_pc_->SetInstructionBits(sim_->break_instr_);
}
}
void Debugger::RedoBreakpoints() {
if (sim_->break_pc_ != NULL) {
sim_->break_pc_->SetInstructionBits(kBreakpointInstr);
}
}
void Debugger::Debug() {
intptr_t last_pc = -1;
bool done = false;
#define COMMAND_SIZE 63
#define ARG_SIZE 255
#define STR(a) #a
#define XSTR(a) STR(a)
char cmd[COMMAND_SIZE + 1];
char arg1[ARG_SIZE + 1];
char arg2[ARG_SIZE + 1];
// make sure to have a proper terminating character if reaching the limit
cmd[COMMAND_SIZE] = 0;
arg1[ARG_SIZE] = 0;
arg2[ARG_SIZE] = 0;
// Undo all set breakpoints while running in the debugger shell. This will
// make them invisible to all commands.
UndoBreakpoints();
while (!done) {
if (last_pc != sim_->get_pc()) {
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 {
// Use sscanf to parse the individual parts of the command line. At the
// moment no command expects more than two parameters.
int args = SScanF(line,
"%" XSTR(COMMAND_SIZE) "s "
"%" XSTR(ARG_SIZE) "s "
"%" XSTR(ARG_SIZE) "s",
cmd, arg1, arg2);
if ((strcmp(cmd, "si") == 0) || (strcmp(cmd, "stepi") == 0)) {
sim_->InstructionDecode(reinterpret_cast<Instr*>(sim_->get_pc()));
} else if ((strcmp(cmd, "c") == 0) || (strcmp(cmd, "cont") == 0)) {
// Execute the one instruction we broke at with breakpoints disabled.
sim_->InstructionDecode(reinterpret_cast<Instr*>(sim_->get_pc()));
// Leave the debugger shell.
done = true;
} else if ((strcmp(cmd, "p") == 0) || (strcmp(cmd, "print") == 0)) {
if (args == 2) {
int32_t value;
if (strcmp(arg1, "all") == 0) {
for (int i = 0; i < kNumRegisters; i++) {
value = GetRegisterValue(i);
PrintF("%3s: 0x%08x %10d\n", Registers::Name(i), value, value);
}
} else {
if (GetValue(arg1, &value)) {
PrintF("%s: 0x%08x %d \n", arg1, value, value);
} else {
PrintF("%s unrecognized\n", arg1);
}
}
} else {
PrintF("print <register>\n");
}
} else if ((strcmp(cmd, "po") == 0)
|| (strcmp(cmd, "printobject") == 0)) {
if (args == 2) {
int32_t value;
if (GetValue(arg1, &value)) {
Object* obj = reinterpret_cast<Object*>(value);
PrintF("%s: \n", arg1);
#ifdef DEBUG
obj->PrintLn();
#else
obj->ShortPrint();
PrintF("\n");
#endif
} else {
PrintF("%s unrecognized\n", arg1);
}
} else {
PrintF("printobject <value>\n");
}
} else if (strcmp(cmd, "disasm") == 0) {
disasm::NameConverter converter;
disasm::Disassembler dasm(converter);
// use a reasonably large buffer
v8::internal::EmbeddedVector<char, 256> buffer;
byte* cur = NULL;
byte* end = NULL;
if (args == 1) {
cur = reinterpret_cast<byte*>(sim_->get_pc());
end = cur + (10 * Instr::kInstrSize);
} else if (args == 2) {
int32_t value;
if (GetValue(arg1, &value)) {
cur = reinterpret_cast<byte*>(value);
// no length parameter passed, assume 10 instructions
end = cur + (10 * Instr::kInstrSize);
}
} else {
int32_t value1;
int32_t value2;
if (GetValue(arg1, &value1) && GetValue(arg2, &value2)) {
cur = reinterpret_cast<byte*>(value1);
end = cur + (value2 * Instr::kInstrSize);
}
}
while (cur < end) {
dasm.InstructionDecode(buffer, cur);
PrintF(" 0x%08x %s\n", cur, buffer.start());
cur += Instr::kInstrSize;
}
} else if (strcmp(cmd, "gdb") == 0) {
PrintF("relinquishing control to gdb\n");
v8::internal::OS::DebugBreak();
PrintF("regaining control from gdb\n");
} else if (strcmp(cmd, "break") == 0) {
if (args == 2) {
int32_t value;
if (GetValue(arg1, &value)) {
if (!SetBreakpoint(reinterpret_cast<Instr*>(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; ", sim_->inexact_vfp_flag_);
} else if (strcmp(cmd, "unstop") == 0) {
intptr_t stop_pc = sim_->get_pc() - Instr::kInstrSize;
Instr* stop_instr = reinterpret_cast<Instr*>(stop_pc);
if (stop_instr->ConditionField() == special_condition) {
stop_instr->SetInstructionBits(kNopInstr);
} else {
PrintF("Not at debugger stop.");
}
} 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("printobject <register>\n");
PrintF(" print an object from a register (alias 'po')\n");
PrintF("flags\n");
PrintF(" print flags\n");
PrintF("disasm [<instructions>]\n");
PrintF("disasm [[<address>] <instructions>]\n");
PrintF(" disassemble code, default is 10 instructions from pc\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("unstop\n");
PrintF(" ignore the stop instruction at the current location");
PrintF(" from now on\n");
PrintF("trace (alias 't')\n");
PrintF(" toogle the tracing of all executed statements");
} else {
PrintF("Unknown command: %s\n", cmd);
}
}
DeleteArray(line);
}
// 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
}
// Create one simulator per thread and keep it in thread local storage.
static v8::internal::Thread::LocalStorageKey simulator_key;
bool Simulator::initialized_ = false;
void Simulator::Initialize() {
if (initialized_) return;
simulator_key = v8::internal::Thread::CreateThreadLocalKey();
initialized_ = true;
::v8::internal::ExternalReference::set_redirector(&RedirectExternalReference);
}
Simulator::Simulator() {
Initialize();
// Setup 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;
// Setup 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_s_registers; i++) {
vfp_register[i] = 0;
}
n_flag_FPSCR_ = false;
z_flag_FPSCR_ = false;
c_flag_FPSCR_ = false;
v_flag_FPSCR_ = 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();
}
// 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 swi (software-interrupt) instruction that is handled by
// the simulator. We write the original destination of the jump just at a known
// offset from the swi instruction so the simulator knows what to call.
class Redirection {
public:
Redirection(void* external_function, bool fp_return)
: external_function_(external_function),
swi_instruction_((AL << 28) | (0xf << 24) | call_rt_redirected),
fp_return_(fp_return),
next_(list_) {
list_ = this;
}
void* address_of_swi_instruction() {
return reinterpret_cast<void*>(&swi_instruction_);
}
void* external_function() { return external_function_; }
bool fp_return() { return fp_return_; }
static Redirection* Get(void* external_function, bool fp_return) {
Redirection* current;
for (current = list_; current != NULL; current = current->next_) {
if (current->external_function_ == external_function) return current;
}
return new Redirection(external_function, fp_return);
}
static Redirection* FromSwiInstruction(Instr* 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);
}
private:
void* external_function_;
uint32_t swi_instruction_;
bool fp_return_;
Redirection* next_;
static Redirection* list_;
};
Redirection* Redirection::list_ = NULL;
void* Simulator::RedirectExternalReference(void* external_function,
bool fp_return) {
Redirection* redirection = Redirection::Get(external_function, fp_return);
return redirection->address_of_swi_instruction();
}
// Get the active Simulator for the current thread.
Simulator* Simulator::current() {
Initialize();
Simulator* sim = reinterpret_cast<Simulator*>(
v8::internal::Thread::GetThreadLocal(simulator_key));
if (sim == NULL) {
// TODO(146): delete the simulator object when a thread goes away.
sim = new Simulator();
v8::internal::Thread::SetThreadLocal(simulator_key, 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) {
ASSERT((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 {
ASSERT((reg >= 0) && (reg < num_registers));
return registers_[reg] + ((reg == pc) ? Instr::kPCReadOffset : 0);
}
// Raw access to the PC register.
void Simulator::set_pc(int32_t value) {
pc_modified_ = true;
registers_[pc] = value;
}
// 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) {
ASSERT((sreg >= 0) && (sreg < num_s_registers));
vfp_register[sreg] = value;
}
unsigned int Simulator::get_s_register(int sreg) const {
ASSERT((sreg >= 0) && (sreg < num_s_registers));
return vfp_register[sreg];
}
void Simulator::set_s_register_from_float(int sreg, const float flt) {
ASSERT((sreg >= 0) && (sreg < num_s_registers));
// Read the bits from the single precision floating point value
// into the unsigned integer element of vfp_register[] given by index=sreg.
char buffer[sizeof(vfp_register[0])];
memcpy(buffer, &flt, sizeof(vfp_register[0]));
memcpy(&vfp_register[sreg], buffer, sizeof(vfp_register[0]));
}
void Simulator::set_s_register_from_sinteger(int sreg, const int sint) {
ASSERT((sreg >= 0) && (sreg < num_s_registers));
// Read the bits from the integer value into the unsigned integer element of
// vfp_register[] given by index=sreg.
char buffer[sizeof(vfp_register[0])];
memcpy(buffer, &sint, sizeof(vfp_register[0]));
memcpy(&vfp_register[sreg], buffer, sizeof(vfp_register[0]));
}
void Simulator::set_d_register_from_double(int dreg, const double& dbl) {
ASSERT((dreg >= 0) && (dreg < num_d_registers));
// Read the bits from the double precision floating point value into the two
// consecutive unsigned integer elements of vfp_register[] given by index
// 2*sreg and 2*sreg+1.
char buffer[2 * sizeof(vfp_register[0])];
memcpy(buffer, &dbl, 2 * sizeof(vfp_register[0]));
#ifndef BIG_ENDIAN_FLOATING_POINT
memcpy(&vfp_register[dreg * 2], buffer, 2 * sizeof(vfp_register[0]));
#else
memcpy(&vfp_register[dreg * 2], &buffer[4], sizeof(vfp_register[0]));
memcpy(&vfp_register[dreg * 2 + 1], &buffer[0], sizeof(vfp_register[0]));
#endif
}
float Simulator::get_float_from_s_register(int sreg) {
ASSERT((sreg >= 0) && (sreg < num_s_registers));
float sm_val = 0.0;
// Read the bits from the unsigned integer vfp_register[] array
// into the single precision floating point value and return it.
char buffer[sizeof(vfp_register[0])];
memcpy(buffer, &vfp_register[sreg], sizeof(vfp_register[0]));
memcpy(&sm_val, buffer, sizeof(vfp_register[0]));
return(sm_val);
}
int Simulator::get_sinteger_from_s_register(int sreg) {
ASSERT((sreg >= 0) && (sreg < num_s_registers));
int sm_val = 0;
// Read the bits from the unsigned integer vfp_register[] array
// into the single precision floating point value and return it.
char buffer[sizeof(vfp_register[0])];
memcpy(buffer, &vfp_register[sreg], sizeof(vfp_register[0]));
memcpy(&sm_val, buffer, sizeof(vfp_register[0]));
return(sm_val);
}
double Simulator::get_double_from_d_register(int dreg) {
ASSERT((dreg >= 0) && (dreg < num_d_registers));
double dm_val = 0.0;
// Read the bits from the unsigned integer vfp_register[] array
// into the double precision floating point value and return it.
char buffer[2 * sizeof(vfp_register[0])];
#ifdef BIG_ENDIAN_FLOATING_POINT
memcpy(&buffer[0], &vfp_register[2 * dreg + 1], sizeof(vfp_register[0]));
memcpy(&buffer[4], &vfp_register[2 * dreg], sizeof(vfp_register[0]));
#else
memcpy(buffer, &vfp_register[2 * dreg], 2 * sizeof(vfp_register[0]));
#endif
memcpy(&dm_val, buffer, 2 * sizeof(vfp_register[0]));
return(dm_val);
}
// For use in calls that take two double values, constructed from r0, r1, r2
// and r3.
void Simulator::GetFpArgs(double* x, double* y) {
// We use a char buffer to get around the strict-aliasing rules which
// otherwise allow the compiler to optimize away the copy.
char buffer[2 * sizeof(registers_[0])];
// Registers 0 and 1 -> x.
memcpy(buffer, registers_, sizeof(buffer));
memcpy(x, buffer, sizeof(buffer));
// Registers 2 and 3 -> y.
memcpy(buffer, registers_ + 2, sizeof(buffer));
memcpy(y, buffer, sizeof(buffer));
}
void Simulator::SetFpResult(const double& result) {
char buffer[2 * sizeof(registers_[0])];
memcpy(buffer, &result, sizeof(buffer));
// result -> registers 0 and 1.
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;
}
// The ARM cannot do unaligned reads and writes. On some ARM platforms an
// interrupt is caused. On others it does a funky rotation thing. For now we
// simply disallow unaligned reads, but at some point we may want to move to
// emulating the rotate behaviour. 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.
int Simulator::ReadW(int32_t addr, Instr* instr) {
if ((addr & 3) == 0) {
intptr_t* ptr = reinterpret_cast<intptr_t*>(addr);
return *ptr;
}
PrintF("Unaligned read at 0x%08x\n", addr);
UNIMPLEMENTED();
return 0;
}
void Simulator::WriteW(int32_t addr, int value, Instr* instr) {
if ((addr & 3) == 0) {
intptr_t* ptr = reinterpret_cast<intptr_t*>(addr);
*ptr = value;
return;
}
PrintF("Unaligned write at 0x%08x, pc=%p\n", addr, instr);
UNIMPLEMENTED();
}
uint16_t Simulator::ReadHU(int32_t addr, Instr* instr) {
if ((addr & 1) == 0) {
uint16_t* ptr = reinterpret_cast<uint16_t*>(addr);
return *ptr;
}
PrintF("Unaligned unsigned halfword read at 0x%08x, pc=%p\n", addr, instr);
UNIMPLEMENTED();
return 0;
}
int16_t Simulator::ReadH(int32_t addr, Instr* instr) {
if ((addr & 1) == 0) {
int16_t* ptr = reinterpret_cast<int16_t*>(addr);
return *ptr;
}
PrintF("Unaligned signed halfword read at 0x%08x\n", addr);
UNIMPLEMENTED();
return 0;
}
void Simulator::WriteH(int32_t addr, uint16_t value, Instr* instr) {
if ((addr & 1) == 0) {
uint16_t* ptr = reinterpret_cast<uint16_t*>(addr);
*ptr = value;
return;
}
PrintF("Unaligned unsigned halfword write at 0x%08x, pc=%p\n", addr, instr);
UNIMPLEMENTED();
}
void Simulator::WriteH(int32_t addr, int16_t value, Instr* instr) {
if ((addr & 1) == 0) {
int16_t* ptr = reinterpret_cast<int16_t*>(addr);
*ptr = value;
return;
}
PrintF("Unaligned halfword write at 0x%08x, pc=%p\n", addr, 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;
}
// Returns the limit of the stack area to enable checking for stack overflows.
uintptr_t Simulator::StackLimit() const {
// Leave a safety margin of 256 bytes to prevent overrunning the stack when
// pushing values.
return reinterpret_cast<uintptr_t>(stack_) + 256;
}
// Unsupported instructions use Format to print an error and stop execution.
void Simulator::Format(Instr* instr, const char* format) {
PrintF("Simulator found unsupported instruction:\n 0x%08x: %s\n",
instr, format);
UNIMPLEMENTED();
}
// Checks if the current instruction should be executed based on its
// condition bits.
bool Simulator::ConditionallyExecute(Instr* 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) {
uint32_t uleft = static_cast<uint32_t>(left);
uint32_t uright = static_cast<uint32_t>(right);
uint32_t urest = 0xffffffffU - uleft;
return (uright > urest);
}
// Calculate C flag value for subtractions.
bool Simulator::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 (isnan(val1) || 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(Instr* instr, bool* carry_out) {
Shift shift = instr->ShiftField();
int shift_amount = instr->ShiftAmountField();
int32_t result = get_register(instr->RmField());
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: {
UNIMPLEMENTED();
break;
}
default: {
UNREACHABLE();
break;
}
}
} else {
// by register
int rs = instr->RsField();
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 {
ASSERT(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 {
ASSERT(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: {
UNIMPLEMENTED();
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(Instr* instr, bool* carry_out) {
int rotate = instr->RotateField() * 2;
int immed8 = instr->Immed8Field();
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;
}
// Addressing Mode 4 - Load and Store Multiple
void Simulator::HandleRList(Instr* instr, bool load) {
int rn = instr->RnField();
int32_t rn_val = get_register(rn);
int rlist = instr->RlistField();
int num_regs = count_bits(rlist);
intptr_t start_address = 0;
intptr_t end_address = 0;
switch (instr->PUField()) {
case 0: {
// Print("da");
UNIMPLEMENTED();
break;
}
case 1: {
// Print("ia");
start_address = rn_val;
end_address = rn_val + (num_regs * 4) - 4;
rn_val = rn_val + (num_regs * 4);
break;
}
case 2: {
// Print("db");
start_address = rn_val - (num_regs * 4);
end_address = rn_val - 4;
rn_val = start_address;
break;
}
case 3: {
// Print("ib");
UNIMPLEMENTED();
break;
}
default: {
UNREACHABLE();
break;
}
}
if (instr->HasW()) {
set_register(rn, rn_val);
}
intptr_t* address = reinterpret_cast<intptr_t*>(start_address);
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;
}
ASSERT(end_address == ((intptr_t)address) - 4);
}
// 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);
typedef double (*SimulatorRuntimeFPCall)(int32_t arg0,
int32_t arg1,
int32_t arg2,
int32_t arg3);
// Software interrupt instructions are used by the simulator to call into the
// C-based V8 runtime.
void Simulator::SoftwareInterrupt(Instr* instr) {
int swi = instr->SwiField();
switch (swi) {
case call_rt_redirected: {
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);
// 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);
if (redirection->fp_return()) {
intptr_t external =
reinterpret_cast<intptr_t>(redirection->external_function());
SimulatorRuntimeFPCall target =
reinterpret_cast<SimulatorRuntimeFPCall>(external);
if (::v8::internal::FLAG_trace_sim) {
double x, y;
GetFpArgs(&x, &y);
PrintF("Call to host function at %p with args %f, %f\n",
FUNCTION_ADDR(target), x, y);
}
double result = target(arg0, arg1, arg2, arg3);
SetFpResult(result);
} else {
intptr_t external =
reinterpret_cast<int32_t>(redirection->external_function());
SimulatorRuntimeCall target =
reinterpret_cast<SimulatorRuntimeCall>(external);
if (::v8::internal::FLAG_trace_sim) {
PrintF(
"Call to host function at %p with args %08x, %08x, %08x, %08x\n",
FUNCTION_ADDR(target),
arg0,
arg1,
arg2,
arg3);
}
int64_t result = target(arg0, arg1, arg2, arg3);
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 break_point: {
Debugger dbg(this);
dbg.Debug();
break;
}
default: {
UNREACHABLE();
break;
}
}
}
// 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(Instr* instr) {
int type = instr->TypeField();
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->RnField();
int rm = instr->RmField();
int rs = instr->RsField();
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 {
// 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");
}
} 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->RdField();
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->RdField();
int rn = instr->RnField();
int32_t rn_val = get_register(rn);
int32_t addr = 0;
if (instr->Bit(22) == 0) {
int rm = instr->RmField();
int32_t rm_val = get_register(rm);
switch (instr->PUField()) {
case 0: {
// Format(instr, "'memop'cond'sign'h 'rd, ['rn], -'rm");
ASSERT(!instr->HasW());
addr = rn_val;
rn_val -= rm_val;
set_register(rn, rn_val);
break;
}
case 1: {
// Format(instr, "'memop'cond'sign'h 'rd, ['rn], +'rm");
ASSERT(!instr->HasW());
addr = rn_val;
rn_val += rm_val;
set_register(rn, rn_val);
break;
}
case 2: {
// 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 3: {
// 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->ImmedHField() << 4) | instr->ImmedLField();
switch (instr->PUField()) {
case 0: {
// Format(instr, "'memop'cond'sign'h 'rd, ['rn], #-'off8");
ASSERT(!instr->HasW());
addr = rn_val;
rn_val -= imm_val;
set_register(rn, rn_val);
break;
}
case 1: {
// Format(instr, "'memop'cond'sign'h 'rd, ['rn], #+'off8");
ASSERT(!instr->HasW());
addr = rn_val;
rn_val += imm_val;
set_register(rn, rn_val);
break;
}
case 2: {
// 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 3: {
// 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->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
ASSERT(instr->HasSign());
ASSERT(instr->HasL());
int8_t val = ReadB(addr);
set_register(rd, val);
}
return;
}
} else {
int rd = instr->RdField();
int rn = instr->RnField();
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 {
ASSERT(instr->TypeField() == 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");
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 {
UNIMPLEMENTED();
}
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 {
ASSERT(type == 0);
int rm = instr->RmField();
switch (instr->Bits(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 + Instr::kInstrSize);
break;
}
default:
UNIMPLEMENTED();
}
}
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 {
UNIMPLEMENTED();
}
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 {
ASSERT(type == 0);
int rm = instr->RmField();
int rd = instr->RdField();
switch (instr->Bits(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();
}
}
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(Instr* instr) {
int rd = instr->RdField();
int rn = instr->RnField();
int32_t rn_val = get_register(rn);
int32_t im_val = instr->Offset12Field();
int32_t addr = 0;
switch (instr->PUField()) {
case 0: {
// Format(instr, "'memop'cond'b 'rd, ['rn], #-'off12");
ASSERT(!instr->HasW());
addr = rn_val;
rn_val -= im_val;
set_register(rn, rn_val);
break;
}
case 1: {
// Format(instr, "'memop'cond'b 'rd, ['rn], #+'off12");
ASSERT(!instr->HasW());
addr = rn_val;
rn_val += im_val;
set_register(rn, rn_val);
break;
}
case 2: {
// 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 3: {
// 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(Instr* instr) {
ASSERT(instr->Bits(6, 4) == 0x5 || instr->Bit(4) == 0);
int rd = instr->RdField();
int rn = instr->RnField();
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 0: {
ASSERT(!instr->HasW());
Format(instr, "'memop'cond'b 'rd, ['rn], -'shift_rm");
break;
}
case 1: {
ASSERT(!instr->HasW());
Format(instr, "'memop'cond'b 'rd, ['rn], +'shift_rm");
break;
}
case 2: {
// Format(instr, "'memop'cond'b 'rd, ['rn, -'shift_rm]'w");
addr = rn_val - shifter_operand;
if (instr->HasW()) {
set_register(rn, addr);
}
break;
}
case 3: {
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->ShiftAmountField());
uint32_t msbit = widthminus1 + lsbit;
if (msbit <= 31) {
uint32_t rm_val =
static_cast<uint32_t>(get_register(instr->RmField()));
uint32_t extr_val = rm_val << (31 - msbit);
extr_val = extr_val >> (31 - widthminus1);
set_register(instr->RdField(), extr_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(Instr* instr) {
ASSERT(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(Instr* instr) {
// Format(instr, "b'l'cond 'target");
int off = (instr->SImmed24Field() << 2);
intptr_t pc_address = get_pc();
if (instr->HasLink()) {
set_register(lr, pc_address + Instr::kInstrSize);
}
int pc_reg = get_register(pc);
set_pc(pc_reg + off);
}
void Simulator::DecodeType6(Instr* instr) {
DecodeType6CoprocessorIns(instr);
}
void Simulator::DecodeType7(Instr* instr) {
if (instr->Bit(24) == 1) {
SoftwareInterrupt(instr);
} else {
DecodeTypeVFP(instr);
}
}
void Simulator::DecodeUnconditional(Instr* instr) {
if (instr->Bits(7, 4) == 0x0B && instr->Bits(27, 25) == 0 && instr->HasL()) {
// Load halfword instruction, either register or immediate offset.
int rd = instr->RdField();
int rn = instr->RnField();
int32_t rn_val = get_register(rn);
int32_t addr = 0;
int32_t offset;
if (instr->Bit(22) == 0) {
// Register offset.
int rm = instr->RmField();
offset = get_register(rm);
} else {
// Immediate offset
offset = instr->Bits(3, 0) + (instr->Bits(11, 8) << 4);
}
switch (instr->PUField()) {
case 0: {
// Post index, negative.
ASSERT(!instr->HasW());
addr = rn_val;
rn_val -= offset;
set_register(rn, rn_val);
break;
}
case 1: {
// Post index, positive.
ASSERT(!instr->HasW());
addr = rn_val;
rn_val += offset;
set_register(rn, rn_val);
break;
}
case 2: {
// Pre index or offset, negative.
rn_val -= offset;
addr = rn_val;
if (instr->HasW()) {
set_register(rn, rn_val);
}
break;
}
case 3: {
// Pre index or offset, positive.
rn_val += offset;
addr = rn_val;
if (instr->HasW()) {
set_register(rn, rn_val);
}
break;
}
default: {
// The PU field is a 2-bit field.
UNREACHABLE();
break;
}
}
// Not sign extending, so load as unsigned.
uint16_t halfword = ReadH(addr, instr);
set_register(rd, halfword);
} else {
Debugger dbg(this);
dbg.Stop(instr);
}
}
// void Simulator::DecodeTypeVFP(Instr* instr)
// The Following ARMv7 VFPv instructions are currently supported.
// vmov :Sn = Rt
// vmov :Rt = Sn
// vcvt: Dd = Sm
// vcvt: Sd = Dm
// Dd = vadd(Dn, Dm)
// Dd = vsub(Dn, Dm)
// Dd = vmul(Dn, Dm)
// Dd = vdiv(Dn, Dm)
// vcmp(Dd, Dm)
// VMRS
void Simulator::DecodeTypeVFP(Instr* instr) {
ASSERT((instr->TypeField() == 7) && (instr->Bit(24) == 0x0) );
int rt = instr->RtField();
int vm = instr->VmField();
int vn = instr->VnField();
int vd = instr->VdField();
if (instr->Bit(23) == 1) {
if ((instr->Bits(21, 19) == 0x7) &&
(instr->Bits(18, 16) == 0x5) &&
(instr->Bits(11, 9) == 0x5) &&
(instr->Bit(8) == 1) &&
(instr->Bit(6) == 1) &&
(instr->Bit(4) == 0)) {
double dm_val = get_double_from_d_register(vm);
int32_t int_value = static_cast<int32_t>(dm_val);
set_s_register_from_sinteger(((vd<<1) | instr->DField()), int_value);
} else if ((instr->Bits(21, 19) == 0x7) &&
(instr->Bits(18, 16) == 0x0) &&
(instr->Bits(11, 9) == 0x5) &&
(instr->Bit(8) == 1) &&
(instr->Bit(7) == 1) &&
(instr->Bit(6) == 1) &&
(instr->Bit(4) == 0)) {
int32_t int_value = get_sinteger_from_s_register(((vm<<1) |
instr->MField()));
double dbl_value = static_cast<double>(int_value);
set_d_register_from_double(vd, dbl_value);
} else if ((instr->Bit(21) == 0x0) &&
(instr->Bit(20) == 0x0) &&
(instr->Bits(11, 9) == 0x5) &&
(instr->Bit(8) == 1) &&
(instr->Bit(6) == 0) &&
(instr->Bit(4) == 0)) {
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;
set_d_register_from_double(vd, dd_value);
} else if ((instr->Bits(21, 20) == 0x3) &&
(instr->Bits(19, 16) == 0x4) &&
(instr->Bits(11, 9) == 0x5) &&
(instr->Bit(8) == 0x1) &&
(instr->Bit(6) == 0x1) &&
(instr->Bit(4) == 0x0)) {
double dd_value = get_double_from_d_register(vd);
double dm_value = get_double_from_d_register(vm);
Compute_FPSCR_Flags(dd_value, dm_value);
} else if ((instr->Bits(23, 20) == 0xF) &&
(instr->Bits(19, 16) == 0x1) &&
(instr->Bits(11, 8) == 0xA) &&
(instr->Bits(7, 5) == 0x0) &&
(instr->Bit(4) == 0x1) &&
(instr->Bits(3, 0) == 0x0)) {
if (instr->Bits(15, 12) == 0xF)
Copy_FPSCR_to_APSR();
else
UNIMPLEMENTED(); // Not used by V8.
} else {
UNIMPLEMENTED(); // Not used by V8.
}
} else if (instr->Bit(21) == 1) {
if ((instr->Bit(20) == 0x1) &&
(instr->Bits(11, 9) == 0x5) &&
(instr->Bit(8) == 0x1) &&
(instr->Bit(6) == 0) &&
(instr->Bit(4) == 0)) {
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;
set_d_register_from_double(vd, dd_value);
} else if ((instr->Bit(20) == 0x1) &&
(instr->Bits(11, 9) == 0x5) &&
(instr->Bit(8) == 0x1) &&
(instr->Bit(6) == 1) &&
(instr->Bit(4) == 0)) {
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;
set_d_register_from_double(vd, dd_value);
} else if ((instr->Bit(20) == 0x0) &&
(instr->Bits(11, 9) == 0x5) &&
(instr->Bit(8) == 0x1) &&
(instr->Bit(6) == 0) &&
(instr->Bit(4) == 0)) {
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;
set_d_register_from_double(vd, dd_value);
} else {
UNIMPLEMENTED(); // Not used by V8.
}
} else {
if ((instr->Bit(20) == 0x0) &&
(instr->Bits(11, 8) == 0xA) &&
(instr->Bits(6, 5) == 0x0) &&
(instr->Bit(4) == 1) &&
(instr->Bits(3, 0) == 0x0)) {
int32_t rs_val = get_register(rt);
set_s_register_from_sinteger(((vn<<1) | instr->NField()), rs_val);
} else if ((instr->Bit(20) == 0x1) &&
(instr->Bits(11, 8) == 0xA) &&
(instr->Bits(6, 5) == 0x0) &&
(instr->Bit(4) == 1) &&
(instr->Bits(3, 0) == 0x0)) {
int32_t int_value = get_sinteger_from_s_register(((vn<<1) |
instr->NField()));
set_register(rt, int_value);
} else {
UNIMPLEMENTED(); // Not used by V8.
}
}
}
// void Simulator::DecodeType6CoprocessorIns(Instr* 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(Instr* instr) {
ASSERT((instr->TypeField() == 6));
if (instr->CoprocessorField() != 0xB) {
UNIMPLEMENTED(); // Not used by V8.
} else {
switch (instr->OpcodeField()) {
case 0x2:
// Load and store double to two GP registers
if (instr->Bits(7, 4) != 0x1) {
UNIMPLEMENTED(); // Not used by V8.
} else {
int rt = instr->RtField();
int rn = instr->RnField();
int vm = instr->VmField();
if (instr->HasL()) {
int32_t rt_int_value = get_sinteger_from_s_register(2*vm);
int32_t rn_int_value = get_sinteger_from_s_register(2*vm+1);
set_register(rt, rt_int_value);
set_register(rn, rn_int_value);
} else {
int32_t rs_val = get_register(rt);
int32_t rn_val = get_register(rn);
set_s_register_from_sinteger(2*vm, rs_val);
set_s_register_from_sinteger((2*vm+1), rn_val);
}
}
break;
case 0x8:
case 0xC: { // Load and store double to memory.
int rn = instr->RnField();
int vd = instr->VdField();
int offset = instr->Immed8Field();
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(2*vd, ReadW(address, instr));
set_s_register_from_sinteger(2*vd + 1, ReadW(address + 4, instr));
} else {
// Store double to memory: vstr.
WriteW(address, get_sinteger_from_s_register(2*vd), instr);
WriteW(address + 4, get_sinteger_from_s_register(2*vd + 1), instr);
}
break;
}
default:
UNIMPLEMENTED(); // Not used by V8.
break;
}
}
}
// Executes the current instruction.
void Simulator::InstructionDecode(Instr* 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", instr, buffer.start());
}
if (instr->ConditionField() == special_condition) {
DecodeUnconditional(instr);
} else if (ConditionallyExecute(instr)) {
switch (instr->TypeField()) {
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 (!pc_modified_) {
set_register(pc, reinterpret_cast<int32_t>(instr) + Instr::kInstrSize);
}
}
void Simulator::Execute() {
// Get the PC to simulate. Cannot use the accessor here as we need the
// raw PC value and not the one used as input to arithmetic instructions.
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) {
Instr* instr = reinterpret_cast<Instr*>(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) {
Instr* instr = reinterpret_cast<Instr*>(program_counter);
icount_++;
if (icount_ == ::v8::internal::FLAG_stop_sim_at) {
Debugger dbg(this);
dbg.Debug();
} else {
InstructionDecode(instr);
}
program_counter = get_pc();
}
}
}
int32_t Simulator::Call(byte* entry, int argument_count, ...) {
va_list parameters;
va_start(parameters, argument_count);
// Setup arguments
// First four arguments passed in registers.
ASSERT(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 (OS::ActivationFrameAlignment() != 0) {
entry_stack &= -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);
// 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);
// Setup 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);
// Pop stack passed arguments.
CHECK_EQ(entry_stack, get_register(sp));
set_register(sp, original_stack);
int32_t result = get_register(r0);
return result;
}
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 assembler::arm
#endif // !defined(__arm__)