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// Copyright 2013, ARM Limited
// 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 ARM Limited 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 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.
#ifdef USE_SIMULATOR
#include <string.h>
#include <cmath>
#include "a64/simulator-a64.h"
namespace vixl {
const Instruction* Simulator::kEndOfSimAddress = NULL;
void SimSystemRegister::SetBits(int msb, int lsb, uint32_t bits) {
int width = msb - lsb + 1;
VIXL_ASSERT(is_uintn(width, bits) || is_intn(width, bits));
bits <<= lsb;
uint32_t mask = ((1 << width) - 1) << lsb;
VIXL_ASSERT((mask & write_ignore_mask_) == 0);
value_ = (value_ & ~mask) | (bits & mask);
}
SimSystemRegister SimSystemRegister::DefaultValueFor(SystemRegister id) {
switch (id) {
case NZCV:
return SimSystemRegister(0x00000000, NZCVWriteIgnoreMask);
case FPCR:
return SimSystemRegister(0x00000000, FPCRWriteIgnoreMask);
default:
VIXL_UNREACHABLE();
return SimSystemRegister();
}
}
Simulator::Simulator(Decoder* decoder, FILE* stream) {
// Ensure that shift operations act as the simulator expects.
VIXL_ASSERT((static_cast<int32_t>(-1) >> 1) == -1);
VIXL_ASSERT((static_cast<uint32_t>(-1) >> 1) == 0x7FFFFFFF);
// Set up the decoder.
decoder_ = decoder;
decoder_->AppendVisitor(this);
ResetState();
// Allocate and set up the simulator stack.
stack_ = new byte[stack_size_];
stack_limit_ = stack_ + stack_protection_size_;
// Configure the starting stack pointer.
// - Find the top of the stack.
byte * tos = stack_ + stack_size_;
// - There's a protection region at both ends of the stack.
tos -= stack_protection_size_;
// - The stack pointer must be 16-byte aligned.
tos = AlignDown(tos, 16);
set_sp(tos);
stream_ = stream;
print_disasm_ = new PrintDisassembler(stream_);
set_coloured_trace(false);
disasm_trace_ = false;
// Set the sample period to 10, as the VIXL examples and tests are short.
instrumentation_ = new Instrument("vixl_stats.csv", 10);
// Print a warning about exclusive-access instructions, but only the first
// time they are encountered. This warning can be silenced using
// SilenceExclusiveAccessWarning().
print_exclusive_access_warning_ = true;
}
void Simulator::ResetState() {
// Reset the system registers.
nzcv_ = SimSystemRegister::DefaultValueFor(NZCV);
fpcr_ = SimSystemRegister::DefaultValueFor(FPCR);
// Reset registers to 0.
pc_ = NULL;
pc_modified_ = false;
for (unsigned i = 0; i < kNumberOfRegisters; i++) {
set_xreg(i, 0xbadbeef);
}
for (unsigned i = 0; i < kNumberOfFPRegisters; i++) {
// Set FP registers to a value that is NaN in both 32-bit and 64-bit FP.
set_dreg(i, kFP64SignallingNaN);
}
// Returning to address 0 exits the Simulator.
set_lr(kEndOfSimAddress);
}
Simulator::~Simulator() {
delete [] stack_;
// The decoder may outlive the simulator.
decoder_->RemoveVisitor(print_disasm_);
delete print_disasm_;
decoder_->RemoveVisitor(instrumentation_);
delete instrumentation_;
}
void Simulator::Run() {
pc_modified_ = false;
while (pc_ != kEndOfSimAddress) {
ExecuteInstruction();
}
}
void Simulator::RunFrom(const Instruction* first) {
set_pc(first);
Run();
}
const char* Simulator::xreg_names[] = {
"x0", "x1", "x2", "x3", "x4", "x5", "x6", "x7",
"x8", "x9", "x10", "x11", "x12", "x13", "x14", "x15",
"x16", "x17", "x18", "x19", "x20", "x21", "x22", "x23",
"x24", "x25", "x26", "x27", "x28", "x29", "lr", "xzr", "sp"};
const char* Simulator::wreg_names[] = {
"w0", "w1", "w2", "w3", "w4", "w5", "w6", "w7",
"w8", "w9", "w10", "w11", "w12", "w13", "w14", "w15",
"w16", "w17", "w18", "w19", "w20", "w21", "w22", "w23",
"w24", "w25", "w26", "w27", "w28", "w29", "w30", "wzr", "wsp"};
const char* Simulator::sreg_names[] = {
"s0", "s1", "s2", "s3", "s4", "s5", "s6", "s7",
"s8", "s9", "s10", "s11", "s12", "s13", "s14", "s15",
"s16", "s17", "s18", "s19", "s20", "s21", "s22", "s23",
"s24", "s25", "s26", "s27", "s28", "s29", "s30", "s31"};
const char* Simulator::dreg_names[] = {
"d0", "d1", "d2", "d3", "d4", "d5", "d6", "d7",
"d8", "d9", "d10", "d11", "d12", "d13", "d14", "d15",
"d16", "d17", "d18", "d19", "d20", "d21", "d22", "d23",
"d24", "d25", "d26", "d27", "d28", "d29", "d30", "d31"};
const char* Simulator::vreg_names[] = {
"v0", "v1", "v2", "v3", "v4", "v5", "v6", "v7",
"v8", "v9", "v10", "v11", "v12", "v13", "v14", "v15",
"v16", "v17", "v18", "v19", "v20", "v21", "v22", "v23",
"v24", "v25", "v26", "v27", "v28", "v29", "v30", "v31"};
const char* Simulator::WRegNameForCode(unsigned code, Reg31Mode mode) {
VIXL_ASSERT(code < kNumberOfRegisters);
// If the code represents the stack pointer, index the name after zr.
if ((code == kZeroRegCode) && (mode == Reg31IsStackPointer)) {
code = kZeroRegCode + 1;
}
return wreg_names[code];
}
const char* Simulator::XRegNameForCode(unsigned code, Reg31Mode mode) {
VIXL_ASSERT(code < kNumberOfRegisters);
// If the code represents the stack pointer, index the name after zr.
if ((code == kZeroRegCode) && (mode == Reg31IsStackPointer)) {
code = kZeroRegCode + 1;
}
return xreg_names[code];
}
const char* Simulator::SRegNameForCode(unsigned code) {
VIXL_ASSERT(code < kNumberOfFPRegisters);
return sreg_names[code];
}
const char* Simulator::DRegNameForCode(unsigned code) {
VIXL_ASSERT(code < kNumberOfFPRegisters);
return dreg_names[code];
}
const char* Simulator::VRegNameForCode(unsigned code) {
VIXL_ASSERT(code < kNumberOfFPRegisters);
return vreg_names[code];
}
#define COLOUR(colour_code) "\033[0;" colour_code "m"
#define COLOUR_BOLD(colour_code) "\033[1;" colour_code "m"
#define NORMAL ""
#define GREY "30"
#define RED "31"
#define GREEN "32"
#define YELLOW "33"
#define BLUE "34"
#define MAGENTA "35"
#define CYAN "36"
#define WHITE "37"
void Simulator::set_coloured_trace(bool value) {
coloured_trace_ = value;
clr_normal = value ? COLOUR(NORMAL) : "";
clr_flag_name = value ? COLOUR_BOLD(GREY) : "";
clr_flag_value = value ? COLOUR_BOLD(WHITE) : "";
clr_reg_name = value ? COLOUR_BOLD(BLUE) : "";
clr_reg_value = value ? COLOUR_BOLD(CYAN) : "";
clr_fpreg_name = value ? COLOUR_BOLD(YELLOW) : "";
clr_fpreg_value = value ? COLOUR_BOLD(MAGENTA) : "";
clr_memory_value = value ? COLOUR_BOLD(GREEN) : "";
clr_memory_address = value ? COLOUR(GREEN) : "";
clr_debug_number = value ? COLOUR_BOLD(YELLOW) : "";
clr_debug_message = value ? COLOUR(YELLOW) : "";
clr_warning = value ? COLOUR_BOLD(RED) : "";
clr_warning_message = value ? COLOUR(RED) : "";
clr_printf = value ? COLOUR(GREEN) : "";
}
// Helpers ---------------------------------------------------------------------
int64_t Simulator::AddWithCarry(unsigned reg_size,
bool set_flags,
int64_t src1,
int64_t src2,
int64_t carry_in) {
VIXL_ASSERT((carry_in == 0) || (carry_in == 1));
VIXL_ASSERT((reg_size == kXRegSize) || (reg_size == kWRegSize));
uint64_t u1, u2;
int64_t result;
int64_t signed_sum = src1 + src2 + carry_in;
uint32_t N, Z, C, V;
if (reg_size == kWRegSize) {
u1 = static_cast<uint64_t>(src1) & kWRegMask;
u2 = static_cast<uint64_t>(src2) & kWRegMask;
result = signed_sum & kWRegMask;
// Compute the C flag by comparing the sum to the max unsigned integer.
C = ((kWMaxUInt - u1) < (u2 + carry_in)) ||
((kWMaxUInt - u1 - carry_in) < u2);
// Overflow iff the sign bit is the same for the two inputs and different
// for the result.
int64_t s_src1 = src1 << (kXRegSize - kWRegSize);
int64_t s_src2 = src2 << (kXRegSize - kWRegSize);
int64_t s_result = result << (kXRegSize - kWRegSize);
V = ((s_src1 ^ s_src2) >= 0) && ((s_src1 ^ s_result) < 0);
} else {
u1 = static_cast<uint64_t>(src1);
u2 = static_cast<uint64_t>(src2);
result = signed_sum;
// Compute the C flag by comparing the sum to the max unsigned integer.
C = ((kXMaxUInt - u1) < (u2 + carry_in)) ||
((kXMaxUInt - u1 - carry_in) < u2);
// Overflow iff the sign bit is the same for the two inputs and different
// for the result.
V = ((src1 ^ src2) >= 0) && ((src1 ^ result) < 0);
}
N = CalcNFlag(result, reg_size);
Z = CalcZFlag(result);
if (set_flags) {
nzcv().SetN(N);
nzcv().SetZ(Z);
nzcv().SetC(C);
nzcv().SetV(V);
}
return result;
}
int64_t Simulator::ShiftOperand(unsigned reg_size,
int64_t value,
Shift shift_type,
unsigned amount) {
if (amount == 0) {
return value;
}
int64_t mask = reg_size == kXRegSize ? kXRegMask : kWRegMask;
switch (shift_type) {
case LSL:
return (value << amount) & mask;
case LSR:
return static_cast<uint64_t>(value) >> amount;
case ASR: {
// Shift used to restore the sign.
unsigned s_shift = kXRegSize - reg_size;
// Value with its sign restored.
int64_t s_value = (value << s_shift) >> s_shift;
return (s_value >> amount) & mask;
}
case ROR: {
if (reg_size == kWRegSize) {
value &= kWRegMask;
}
return (static_cast<uint64_t>(value) >> amount) |
((value & ((INT64_C(1) << amount) - 1)) <<
(reg_size - amount));
}
default:
VIXL_UNIMPLEMENTED();
return 0;
}
}
int64_t Simulator::ExtendValue(unsigned reg_size,
int64_t value,
Extend extend_type,
unsigned left_shift) {
switch (extend_type) {
case UXTB:
value &= kByteMask;
break;
case UXTH:
value &= kHalfWordMask;
break;
case UXTW:
value &= kWordMask;
break;
case SXTB:
value = (value << 56) >> 56;
break;
case SXTH:
value = (value << 48) >> 48;
break;
case SXTW:
value = (value << 32) >> 32;
break;
case UXTX:
case SXTX:
break;
default:
VIXL_UNREACHABLE();
}
int64_t mask = (reg_size == kXRegSize) ? kXRegMask : kWRegMask;
return (value << left_shift) & mask;
}
template<> double Simulator::FPDefaultNaN<double>() const {
return kFP64DefaultNaN;
}
template<> float Simulator::FPDefaultNaN<float>() const {
return kFP32DefaultNaN;
}
void Simulator::FPCompare(double val0, double val1) {
AssertSupportedFPCR();
// TODO: This assumes that the C++ implementation handles comparisons in the
// way that we expect (as per AssertSupportedFPCR()).
if ((std::isnan(val0) != 0) || (std::isnan(val1) != 0)) {
nzcv().SetRawValue(FPUnorderedFlag);
} else if (val0 < val1) {
nzcv().SetRawValue(FPLessThanFlag);
} else if (val0 > val1) {
nzcv().SetRawValue(FPGreaterThanFlag);
} else if (val0 == val1) {
nzcv().SetRawValue(FPEqualFlag);
} else {
VIXL_UNREACHABLE();
}
}
void Simulator::PrintSystemRegisters(bool print_all) {
static bool first_run = true;
static SimSystemRegister last_nzcv;
if (print_all || first_run || (last_nzcv.RawValue() != nzcv().RawValue())) {
fprintf(stream_, "# %sFLAGS: %sN:%d Z:%d C:%d V:%d%s\n",
clr_flag_name,
clr_flag_value,
N(), Z(), C(), V(),
clr_normal);
}
last_nzcv = nzcv();
static SimSystemRegister last_fpcr;
if (print_all || first_run || (last_fpcr.RawValue() != fpcr().RawValue())) {
static const char * rmode[] = {
"0b00 (Round to Nearest)",
"0b01 (Round towards Plus Infinity)",
"0b10 (Round towards Minus Infinity)",
"0b11 (Round towards Zero)"
};
VIXL_ASSERT(fpcr().RMode() < (sizeof(rmode) / sizeof(rmode[0])));
fprintf(stream_, "# %sFPCR: %sAHP:%d DN:%d FZ:%d RMode:%s%s\n",
clr_flag_name,
clr_flag_value,
fpcr().AHP(), fpcr().DN(), fpcr().FZ(), rmode[fpcr().RMode()],
clr_normal);
}
last_fpcr = fpcr();
first_run = false;
}
void Simulator::PrintRegisters(bool print_all_regs) {
static bool first_run = true;
static int64_t last_regs[kNumberOfRegisters];
for (unsigned i = 0; i < kNumberOfRegisters; i++) {
if (print_all_regs || first_run ||
(last_regs[i] != xreg(i, Reg31IsStackPointer))) {
fprintf(stream_,
"# %s%4s:%s 0x%016" PRIx64 "%s\n",
clr_reg_name,
XRegNameForCode(i, Reg31IsStackPointer),
clr_reg_value,
xreg(i, Reg31IsStackPointer),
clr_normal);
}
// Cache the new register value so the next run can detect any changes.
last_regs[i] = xreg(i, Reg31IsStackPointer);
}
first_run = false;
}
void Simulator::PrintFPRegisters(bool print_all_regs) {
static bool first_run = true;
static uint64_t last_regs[kNumberOfFPRegisters];
// Print as many rows of registers as necessary, keeping each individual
// register in the same column each time (to make it easy to visually scan
// for changes).
for (unsigned i = 0; i < kNumberOfFPRegisters; i++) {
if (print_all_regs || first_run || (last_regs[i] != dreg_bits(i))) {
fprintf(stream_,
"# %s%4s:%s 0x%016" PRIx64 "%s (%s%s:%s %g%s %s:%s %g%s)\n",
clr_fpreg_name,
VRegNameForCode(i),
clr_fpreg_value,
dreg_bits(i),
clr_normal,
clr_fpreg_name,
DRegNameForCode(i),
clr_fpreg_value,
dreg(i),
clr_fpreg_name,
SRegNameForCode(i),
clr_fpreg_value,
sreg(i),
clr_normal);
}
// Cache the new register value so the next run can detect any changes.
last_regs[i] = dreg_bits(i);
}
first_run = false;
}
void Simulator::PrintProcessorState() {
PrintSystemRegisters();
PrintRegisters();
PrintFPRegisters();
}
// Visitors---------------------------------------------------------------------
void Simulator::VisitUnimplemented(const Instruction* instr) {
printf("Unimplemented instruction at %p: 0x%08" PRIx32 "\n",
reinterpret_cast<const void*>(instr), instr->InstructionBits());
VIXL_UNIMPLEMENTED();
}
void Simulator::VisitUnallocated(const Instruction* instr) {
printf("Unallocated instruction at %p: 0x%08" PRIx32 "\n",
reinterpret_cast<const void*>(instr), instr->InstructionBits());
VIXL_UNIMPLEMENTED();
}
void Simulator::VisitPCRelAddressing(const Instruction* instr) {
VIXL_ASSERT((instr->Mask(PCRelAddressingMask) == ADR) ||
(instr->Mask(PCRelAddressingMask) == ADRP));
set_reg(instr->Rd(), instr->ImmPCOffsetTarget());
}
void Simulator::VisitUnconditionalBranch(const Instruction* instr) {
switch (instr->Mask(UnconditionalBranchMask)) {
case BL:
set_lr(instr->NextInstruction());
// Fall through.
case B:
set_pc(instr->ImmPCOffsetTarget());
break;
default: VIXL_UNREACHABLE();
}
}
void Simulator::VisitConditionalBranch(const Instruction* instr) {
VIXL_ASSERT(instr->Mask(ConditionalBranchMask) == B_cond);
if (ConditionPassed(instr->ConditionBranch())) {
set_pc(instr->ImmPCOffsetTarget());
}
}
void Simulator::VisitUnconditionalBranchToRegister(const Instruction* instr) {
const Instruction* target = Instruction::Cast(xreg(instr->Rn()));
switch (instr->Mask(UnconditionalBranchToRegisterMask)) {
case BLR:
set_lr(instr->NextInstruction());
// Fall through.
case BR:
case RET: set_pc(target); break;
default: VIXL_UNREACHABLE();
}
}
void Simulator::VisitTestBranch(const Instruction* instr) {
unsigned bit_pos = (instr->ImmTestBranchBit5() << 5) |
instr->ImmTestBranchBit40();
bool bit_zero = ((xreg(instr->Rt()) >> bit_pos) & 1) == 0;
bool take_branch = false;
switch (instr->Mask(TestBranchMask)) {
case TBZ: take_branch = bit_zero; break;
case TBNZ: take_branch = !bit_zero; break;
default: VIXL_UNIMPLEMENTED();
}
if (take_branch) {
set_pc(instr->ImmPCOffsetTarget());
}
}
void Simulator::VisitCompareBranch(const Instruction* instr) {
unsigned rt = instr->Rt();
bool take_branch = false;
switch (instr->Mask(CompareBranchMask)) {
case CBZ_w: take_branch = (wreg(rt) == 0); break;
case CBZ_x: take_branch = (xreg(rt) == 0); break;
case CBNZ_w: take_branch = (wreg(rt) != 0); break;
case CBNZ_x: take_branch = (xreg(rt) != 0); break;
default: VIXL_UNIMPLEMENTED();
}
if (take_branch) {
set_pc(instr->ImmPCOffsetTarget());
}
}
void Simulator::AddSubHelper(const Instruction* instr, int64_t op2) {
unsigned reg_size = instr->SixtyFourBits() ? kXRegSize : kWRegSize;
bool set_flags = instr->FlagsUpdate();
int64_t new_val = 0;
Instr operation = instr->Mask(AddSubOpMask);
switch (operation) {
case ADD:
case ADDS: {
new_val = AddWithCarry(reg_size,
set_flags,
reg(reg_size, instr->Rn(), instr->RnMode()),
op2);
break;
}
case SUB:
case SUBS: {
new_val = AddWithCarry(reg_size,
set_flags,
reg(reg_size, instr->Rn(), instr->RnMode()),
~op2,
1);
break;
}
default: VIXL_UNREACHABLE();
}
set_reg(reg_size, instr->Rd(), new_val, instr->RdMode());
}
void Simulator::VisitAddSubShifted(const Instruction* instr) {
unsigned reg_size = instr->SixtyFourBits() ? kXRegSize : kWRegSize;
int64_t op2 = ShiftOperand(reg_size,
reg(reg_size, instr->Rm()),
static_cast<Shift>(instr->ShiftDP()),
instr->ImmDPShift());
AddSubHelper(instr, op2);
}
void Simulator::VisitAddSubImmediate(const Instruction* instr) {
int64_t op2 = instr->ImmAddSub() << ((instr->ShiftAddSub() == 1) ? 12 : 0);
AddSubHelper(instr, op2);
}
void Simulator::VisitAddSubExtended(const Instruction* instr) {
unsigned reg_size = instr->SixtyFourBits() ? kXRegSize : kWRegSize;
int64_t op2 = ExtendValue(reg_size,
reg(reg_size, instr->Rm()),
static_cast<Extend>(instr->ExtendMode()),
instr->ImmExtendShift());
AddSubHelper(instr, op2);
}
void Simulator::VisitAddSubWithCarry(const Instruction* instr) {
unsigned reg_size = instr->SixtyFourBits() ? kXRegSize : kWRegSize;
int64_t op2 = reg(reg_size, instr->Rm());
int64_t new_val;
if ((instr->Mask(AddSubOpMask) == SUB) || instr->Mask(AddSubOpMask) == SUBS) {
op2 = ~op2;
}
new_val = AddWithCarry(reg_size,
instr->FlagsUpdate(),
reg(reg_size, instr->Rn()),
op2,
C());
set_reg(reg_size, instr->Rd(), new_val);
}
void Simulator::VisitLogicalShifted(const Instruction* instr) {
unsigned reg_size = instr->SixtyFourBits() ? kXRegSize : kWRegSize;
Shift shift_type = static_cast<Shift>(instr->ShiftDP());
unsigned shift_amount = instr->ImmDPShift();
int64_t op2 = ShiftOperand(reg_size, reg(reg_size, instr->Rm()), shift_type,
shift_amount);
if (instr->Mask(NOT) == NOT) {
op2 = ~op2;
}
LogicalHelper(instr, op2);
}
void Simulator::VisitLogicalImmediate(const Instruction* instr) {
LogicalHelper(instr, instr->ImmLogical());
}
void Simulator::LogicalHelper(const Instruction* instr, int64_t op2) {
unsigned reg_size = instr->SixtyFourBits() ? kXRegSize : kWRegSize;
int64_t op1 = reg(reg_size, instr->Rn());
int64_t result = 0;
bool update_flags = false;
// Switch on the logical operation, stripping out the NOT bit, as it has a
// different meaning for logical immediate instructions.
switch (instr->Mask(LogicalOpMask & ~NOT)) {
case ANDS: update_flags = true; // Fall through.
case AND: result = op1 & op2; break;
case ORR: result = op1 | op2; break;
case EOR: result = op1 ^ op2; break;
default:
VIXL_UNIMPLEMENTED();
}
if (update_flags) {
nzcv().SetN(CalcNFlag(result, reg_size));
nzcv().SetZ(CalcZFlag(result));
nzcv().SetC(0);
nzcv().SetV(0);
}
set_reg(reg_size, instr->Rd(), result, instr->RdMode());
}
void Simulator::VisitConditionalCompareRegister(const Instruction* instr) {
unsigned reg_size = instr->SixtyFourBits() ? kXRegSize : kWRegSize;
ConditionalCompareHelper(instr, reg(reg_size, instr->Rm()));
}
void Simulator::VisitConditionalCompareImmediate(const Instruction* instr) {
ConditionalCompareHelper(instr, instr->ImmCondCmp());
}
void Simulator::ConditionalCompareHelper(const Instruction* instr,
int64_t op2) {
unsigned reg_size = instr->SixtyFourBits() ? kXRegSize : kWRegSize;
int64_t op1 = reg(reg_size, instr->Rn());
if (ConditionPassed(instr->Condition())) {
// If the condition passes, set the status flags to the result of comparing
// the operands.
if (instr->Mask(ConditionalCompareMask) == CCMP) {
AddWithCarry(reg_size, true, op1, ~op2, 1);
} else {
VIXL_ASSERT(instr->Mask(ConditionalCompareMask) == CCMN);
AddWithCarry(reg_size, true, op1, op2, 0);
}
} else {
// If the condition fails, set the status flags to the nzcv immediate.
nzcv().SetFlags(instr->Nzcv());
}
}
void Simulator::VisitLoadStoreUnsignedOffset(const Instruction* instr) {
int offset = instr->ImmLSUnsigned() << instr->SizeLS();
LoadStoreHelper(instr, offset, Offset);
}
void Simulator::VisitLoadStoreUnscaledOffset(const Instruction* instr) {
LoadStoreHelper(instr, instr->ImmLS(), Offset);
}
void Simulator::VisitLoadStorePreIndex(const Instruction* instr) {
LoadStoreHelper(instr, instr->ImmLS(), PreIndex);
}
void Simulator::VisitLoadStorePostIndex(const Instruction* instr) {
LoadStoreHelper(instr, instr->ImmLS(), PostIndex);
}
void Simulator::VisitLoadStoreRegisterOffset(const Instruction* instr) {
Extend ext = static_cast<Extend>(instr->ExtendMode());
VIXL_ASSERT((ext == UXTW) || (ext == UXTX) || (ext == SXTW) || (ext == SXTX));
unsigned shift_amount = instr->ImmShiftLS() * instr->SizeLS();
int64_t offset = ExtendValue(kXRegSize, xreg(instr->Rm()), ext,
shift_amount);
LoadStoreHelper(instr, offset, Offset);
}
void Simulator::LoadStoreHelper(const Instruction* instr,
int64_t offset,
AddrMode addrmode) {
unsigned srcdst = instr->Rt();
uint8_t* address = AddressModeHelper(instr->Rn(), offset, addrmode);
LoadStoreOp op = static_cast<LoadStoreOp>(instr->Mask(LoadStoreOpMask));
switch (op) {
case LDRB_w: set_wreg(srcdst, MemoryRead<uint8_t>(address)); break;
case LDRH_w: set_wreg(srcdst, MemoryRead<uint16_t>(address)); break;
case LDR_w: set_wreg(srcdst, MemoryRead<uint32_t>(address)); break;
case LDR_x: set_xreg(srcdst, MemoryRead<uint64_t>(address)); break;
case LDRSB_w: set_wreg(srcdst, MemoryRead<int8_t>(address)); break;
case LDRSH_w: set_wreg(srcdst, MemoryRead<int16_t>(address)); break;
case LDRSB_x: set_xreg(srcdst, MemoryRead<int8_t>(address)); break;
case LDRSH_x: set_xreg(srcdst, MemoryRead<int16_t>(address)); break;
case LDRSW_x: set_xreg(srcdst, MemoryRead<int32_t>(address)); break;
case LDR_s: set_sreg(srcdst, MemoryRead<float>(address)); break;
case LDR_d: set_dreg(srcdst, MemoryRead<double>(address)); break;
case STRB_w: MemoryWrite<uint8_t>(address, wreg(srcdst)); break;
case STRH_w: MemoryWrite<uint16_t>(address, wreg(srcdst)); break;
case STR_w: MemoryWrite<uint32_t>(address, wreg(srcdst)); break;
case STR_x: MemoryWrite<uint64_t>(address, xreg(srcdst)); break;
case STR_s: MemoryWrite<float>(address, sreg(srcdst)); break;
case STR_d: MemoryWrite<double>(address, dreg(srcdst)); break;
default: VIXL_UNIMPLEMENTED();
}
local_monitor_.MaybeClear();
}
void Simulator::VisitLoadStorePairOffset(const Instruction* instr) {
LoadStorePairHelper(instr, Offset);
}
void Simulator::VisitLoadStorePairPreIndex(const Instruction* instr) {
LoadStorePairHelper(instr, PreIndex);
}
void Simulator::VisitLoadStorePairPostIndex(const Instruction* instr) {
LoadStorePairHelper(instr, PostIndex);
}
void Simulator::VisitLoadStorePairNonTemporal(const Instruction* instr) {
LoadStorePairHelper(instr, Offset);
}
void Simulator::LoadStorePairHelper(const Instruction* instr,
AddrMode addrmode) {
unsigned rt = instr->Rt();
unsigned rt2 = instr->Rt2();
int offset = instr->ImmLSPair() << instr->SizeLSPair();
uint8_t* address = AddressModeHelper(instr->Rn(), offset, addrmode);
LoadStorePairOp op =
static_cast<LoadStorePairOp>(instr->Mask(LoadStorePairMask));
// 'rt' and 'rt2' can only be aliased for stores.
VIXL_ASSERT(((op & LoadStorePairLBit) == 0) || (rt != rt2));
switch (op) {
case LDP_w: {
set_wreg(rt, MemoryRead<uint32_t>(address));
set_wreg(rt2, MemoryRead<uint32_t>(address + kWRegSizeInBytes));
break;
}
case LDP_s: {
set_sreg(rt, MemoryRead<float>(address));
set_sreg(rt2, MemoryRead<float>(address + kSRegSizeInBytes));
break;
}
case LDP_x: {
set_xreg(rt, MemoryRead<uint64_t>(address));
set_xreg(rt2, MemoryRead<uint64_t>(address + kXRegSizeInBytes));
break;
}
case LDP_d: {
set_dreg(rt, MemoryRead<double>(address));
set_dreg(rt2, MemoryRead<double>(address + kDRegSizeInBytes));
break;
}
case LDPSW_x: {
set_xreg(rt, MemoryRead<int32_t>(address));
set_xreg(rt2, MemoryRead<int32_t>(address + kWRegSizeInBytes));
break;
}
case STP_w: {
MemoryWrite<uint32_t>(address, wreg(rt));
MemoryWrite<uint32_t>(address + kWRegSizeInBytes, wreg(rt2));
break;
}
case STP_s: {
MemoryWrite<float>(address, sreg(rt));
MemoryWrite<float>(address + kSRegSizeInBytes, sreg(rt2));
break;
}
case STP_x: {
MemoryWrite<uint64_t>(address, xreg(rt));
MemoryWrite<uint64_t>(address + kXRegSizeInBytes, xreg(rt2));
break;
}
case STP_d: {
MemoryWrite<double>(address, dreg(rt));
MemoryWrite<double>(address + kDRegSizeInBytes, dreg(rt2));
break;
}
default: VIXL_UNREACHABLE();
}
local_monitor_.MaybeClear();
}
void Simulator::PrintExclusiveAccessWarning() {
if (print_exclusive_access_warning_) {
fprintf(
stderr,
"%sWARNING:%s VIXL simulator support for load-/store-/clear-exclusive "
"instructions is limited. Refer to the README for details.%s\n",
clr_warning, clr_warning_message, clr_normal);
print_exclusive_access_warning_ = false;
}
}
void Simulator::VisitLoadStoreExclusive(const Instruction* instr) {
PrintExclusiveAccessWarning();
unsigned rs = instr->Rs();
unsigned rt = instr->Rt();
unsigned rt2 = instr->Rt2();
unsigned rn = instr->Rn();
LoadStoreExclusive op =
static_cast<LoadStoreExclusive>(instr->Mask(LoadStoreExclusiveMask));
bool is_acquire_release = instr->LdStXAcquireRelease();
bool is_exclusive = !instr->LdStXNotExclusive();
bool is_load = instr->LdStXLoad();
bool is_pair = instr->LdStXPair();
uint8_t * address = reg<uint8_t *>(rn, Reg31IsStackPointer);
size_t element_size = 1 << instr->LdStXSizeLog2();
size_t access_size = is_pair ? element_size * 2 : element_size;
// Check the alignment of `address`.
if (AlignDown(address, access_size) != address) {
VIXL_ALIGNMENT_EXCEPTION();
}
// The sp must be aligned to 16 bytes when it is accessed.
if ((rn == 31) && (AlignDown(address, 16) != address)) {
VIXL_ALIGNMENT_EXCEPTION();
}
if (is_load) {
if (is_exclusive) {
local_monitor_.MarkExclusive(address, access_size);
} else {
// Any non-exclusive load can clear the local monitor as a side effect. We
// don't need to do this, but it is useful to stress the simulated code.
local_monitor_.Clear();
}
switch (op) {
case LDXRB_w:
case LDAXRB_w:
case LDARB_w:
set_wreg(rt, MemoryRead<uint8_t>(address));
break;
case LDXRH_w:
case LDAXRH_w:
case LDARH_w:
set_wreg(rt, MemoryRead<uint16_t>(address));
break;
case LDXR_w:
case LDAXR_w:
case LDAR_w:
set_wreg(rt, MemoryRead<uint32_t>(address));
break;
case LDXR_x:
case LDAXR_x:
case LDAR_x:
set_xreg(rt, MemoryRead<uint64_t>(address));
break;
case LDXP_w:
case LDAXP_w:
set_wreg(rt, MemoryRead<uint32_t>(address));
set_wreg(rt2, MemoryRead<uint32_t>(address + element_size));
break;
case LDXP_x:
case LDAXP_x:
set_xreg(rt, MemoryRead<uint64_t>(address));
set_xreg(rt2, MemoryRead<uint64_t>(address + element_size));
break;
default:
VIXL_UNREACHABLE();
}
if (is_acquire_release) {
// Approximate load-acquire by issuing a full barrier after the load.
__sync_synchronize();
}
} else {
if (is_acquire_release) {
// Approximate store-release by issuing a full barrier before the store.
__sync_synchronize();
}
bool do_store = true;
if (is_exclusive) {
do_store = local_monitor_.IsExclusive(address, access_size) &&
global_monitor_.IsExclusive(address, access_size);
set_wreg(rs, do_store ? 0 : 1);
// - All exclusive stores explicitly clear the local monitor.
local_monitor_.Clear();
} else {
// - Any other store can clear the local monitor as a side effect.
local_monitor_.MaybeClear();
}
if (do_store) {
switch (op) {
case STXRB_w:
case STLXRB_w:
case STLRB_w:
MemoryWrite<uint8_t>(address, wreg(rt));
break;
case STXRH_w:
case STLXRH_w:
case STLRH_w:
MemoryWrite<uint16_t>(address, wreg(rt));
break;
case STXR_w:
case STLXR_w:
case STLR_w:
MemoryWrite<uint32_t>(address, wreg(rt));
break;
case STXR_x:
case STLXR_x:
case STLR_x:
MemoryWrite<uint64_t>(address, xreg(rt));
break;
case STXP_w:
case STLXP_w:
MemoryWrite<uint32_t>(address, wreg(rt));
MemoryWrite<uint32_t>(address + element_size, wreg(rt2));
break;
case STXP_x:
case STLXP_x:
MemoryWrite<uint64_t>(address, xreg(rt));
MemoryWrite<uint64_t>(address + element_size, xreg(rt2));
break;
default:
VIXL_UNREACHABLE();
}
}
}
}
void Simulator::VisitLoadLiteral(const Instruction* instr) {
uint8_t* address = instr->LiteralAddress();
unsigned rt = instr->Rt();
switch (instr->Mask(LoadLiteralMask)) {
case LDR_w_lit: set_wreg(rt, MemoryRead<uint32_t>(address)); break;
case LDR_x_lit: set_xreg(rt, MemoryRead<uint64_t>(address)); break;
case LDR_s_lit: set_sreg(rt, MemoryRead<float>(address)); break;
case LDR_d_lit: set_dreg(rt, MemoryRead<double>(address)); break;
case LDRSW_x_lit: set_xreg(rt, MemoryRead<int32_t>(address)); break;
default: VIXL_UNREACHABLE();
}
local_monitor_.MaybeClear();
}
uint8_t* Simulator::AddressModeHelper(unsigned addr_reg,
int64_t offset,
AddrMode addrmode) {
uint64_t address = xreg(addr_reg, Reg31IsStackPointer);
if ((addr_reg == 31) && ((address % 16) != 0)) {
// When the base register is SP the stack pointer is required to be
// quadword aligned prior to the address calculation and write-backs.
// Misalignment will cause a stack alignment fault.
VIXL_ALIGNMENT_EXCEPTION();
}
if ((addrmode == PreIndex) || (addrmode == PostIndex)) {
VIXL_ASSERT(offset != 0);
set_xreg(addr_reg, address + offset, Reg31IsStackPointer);
}
if ((addrmode == Offset) || (addrmode == PreIndex)) {
address += offset;
}
// Verify that the calculated address is available to the host.
VIXL_ASSERT(address == static_cast<uintptr_t>(address));
return reinterpret_cast<uint8_t*>(address);
}
void Simulator::VisitMoveWideImmediate(const Instruction* instr) {
MoveWideImmediateOp mov_op =
static_cast<MoveWideImmediateOp>(instr->Mask(MoveWideImmediateMask));
int64_t new_xn_val = 0;
bool is_64_bits = instr->SixtyFourBits() != 0;
// Shift is limited for W operations.
VIXL_ASSERT(is_64_bits || (instr->ShiftMoveWide() < 2));
// Get the shifted immediate.
int64_t shift = instr->ShiftMoveWide() * 16;
int64_t shifted_imm16 = instr->ImmMoveWide() << shift;
// Compute the new value.
switch (mov_op) {
case MOVN_w:
case MOVN_x: {
new_xn_val = ~shifted_imm16;
if (!is_64_bits) new_xn_val &= kWRegMask;
break;
}
case MOVK_w:
case MOVK_x: {
unsigned reg_code = instr->Rd();
int64_t prev_xn_val = is_64_bits ? xreg(reg_code)
: wreg(reg_code);
new_xn_val =
(prev_xn_val & ~(INT64_C(0xffff) << shift)) | shifted_imm16;
break;
}
case MOVZ_w:
case MOVZ_x: {
new_xn_val = shifted_imm16;
break;
}
default:
VIXL_UNREACHABLE();
}
// Update the destination register.
set_xreg(instr->Rd(), new_xn_val);
}
void Simulator::VisitConditionalSelect(const Instruction* instr) {
uint64_t new_val = xreg(instr->Rn());
if (ConditionFailed(static_cast<Condition>(instr->Condition()))) {
new_val = xreg(instr->Rm());
switch (instr->Mask(ConditionalSelectMask)) {
case CSEL_w:
case CSEL_x: break;
case CSINC_w:
case CSINC_x: new_val++; break;
case CSINV_w:
case CSINV_x: new_val = ~new_val; break;
case CSNEG_w:
case CSNEG_x: new_val = -new_val; break;
default: VIXL_UNIMPLEMENTED();
}
}
unsigned reg_size = instr->SixtyFourBits() ? kXRegSize : kWRegSize;
set_reg(reg_size, instr->Rd(), new_val);
}
void Simulator::VisitDataProcessing1Source(const Instruction* instr) {
unsigned dst = instr->Rd();
unsigned src = instr->Rn();
switch (instr->Mask(DataProcessing1SourceMask)) {
case RBIT_w: set_wreg(dst, ReverseBits(wreg(src), kWRegSize)); break;
case RBIT_x: set_xreg(dst, ReverseBits(xreg(src), kXRegSize)); break;
case REV16_w: set_wreg(dst, ReverseBytes(wreg(src), Reverse16)); break;
case REV16_x: set_xreg(dst, ReverseBytes(xreg(src), Reverse16)); break;
case REV_w: set_wreg(dst, ReverseBytes(wreg(src), Reverse32)); break;
case REV32_x: set_xreg(dst, ReverseBytes(xreg(src), Reverse32)); break;
case REV_x: set_xreg(dst, ReverseBytes(xreg(src), Reverse64)); break;
case CLZ_w: set_wreg(dst, CountLeadingZeros(wreg(src), kWRegSize)); break;
case CLZ_x: set_xreg(dst, CountLeadingZeros(xreg(src), kXRegSize)); break;
case CLS_w: {
set_wreg(dst, CountLeadingSignBits(wreg(src), kWRegSize));
break;
}
case CLS_x: {
set_xreg(dst, CountLeadingSignBits(xreg(src), kXRegSize));
break;
}
default: VIXL_UNIMPLEMENTED();
}
}
uint64_t Simulator::ReverseBits(uint64_t value, unsigned num_bits) {
VIXL_ASSERT((num_bits == kWRegSize) || (num_bits == kXRegSize));
uint64_t result = 0;
for (unsigned i = 0; i < num_bits; i++) {
result = (result << 1) | (value & 1);
value >>= 1;
}
return result;
}
uint64_t Simulator::ReverseBytes(uint64_t value, ReverseByteMode mode) {
// Split the 64-bit value into an 8-bit array, where b[0] is the least
// significant byte, and b[7] is the most significant.
uint8_t bytes[8];
uint64_t mask = UINT64_C(0xff00000000000000);
for (int i = 7; i >= 0; i--) {
bytes[i] = (value & mask) >> (i * 8);
mask >>= 8;
}
// Permutation tables for REV instructions.
// permute_table[Reverse16] is used by REV16_x, REV16_w
// permute_table[Reverse32] is used by REV32_x, REV_w
// permute_table[Reverse64] is used by REV_x
VIXL_STATIC_ASSERT((Reverse16 == 0) && (Reverse32 == 1) && (Reverse64 == 2));
static const uint8_t permute_table[3][8] = { {6, 7, 4, 5, 2, 3, 0, 1},
{4, 5, 6, 7, 0, 1, 2, 3},
{0, 1, 2, 3, 4, 5, 6, 7} };
uint64_t result = 0;
for (int i = 0; i < 8; i++) {
result <<= 8;
result |= bytes[permute_table[mode][i]];
}
return result;
}
void Simulator::VisitDataProcessing2Source(const Instruction* instr) {
Shift shift_op = NO_SHIFT;
int64_t result = 0;
switch (instr->Mask(DataProcessing2SourceMask)) {
case SDIV_w: {
int32_t rn = wreg(instr->Rn());
int32_t rm = wreg(instr->Rm());
if ((rn == kWMinInt) && (rm == -1)) {
result = kWMinInt;
} else if (rm == 0) {
// Division by zero can be trapped, but not on A-class processors.
result = 0;
} else {
result = rn / rm;
}
break;
}
case SDIV_x: {
int64_t rn = xreg(instr->Rn());
int64_t rm = xreg(instr->Rm());
if ((rn == kXMinInt) && (rm == -1)) {
result = kXMinInt;
} else if (rm == 0) {
// Division by zero can be trapped, but not on A-class processors.
result = 0;
} else {
result = rn / rm;
}
break;
}
case UDIV_w: {
uint32_t rn = static_cast<uint32_t>(wreg(instr->Rn()));
uint32_t rm = static_cast<uint32_t>(wreg(instr->Rm()));
if (rm == 0) {
// Division by zero can be trapped, but not on A-class processors.
result = 0;
} else {
result = rn / rm;
}
break;
}
case UDIV_x: {
uint64_t rn = static_cast<uint64_t>(xreg(instr->Rn()));
uint64_t rm = static_cast<uint64_t>(xreg(instr->Rm()));
if (rm == 0) {
// Division by zero can be trapped, but not on A-class processors.
result = 0;
} else {
result = rn / rm;
}
break;
}
case LSLV_w:
case LSLV_x: shift_op = LSL; break;
case LSRV_w:
case LSRV_x: shift_op = LSR; break;
case ASRV_w:
case ASRV_x: shift_op = ASR; break;
case RORV_w:
case RORV_x: shift_op = ROR; break;
default: VIXL_UNIMPLEMENTED();
}
unsigned reg_size = instr->SixtyFourBits() ? kXRegSize : kWRegSize;
if (shift_op != NO_SHIFT) {
// Shift distance encoded in the least-significant five/six bits of the
// register.
int mask = (instr->SixtyFourBits() != 0) ? 0x3f : 0x1f;
unsigned shift = wreg(instr->Rm()) & mask;
result = ShiftOperand(reg_size, reg(reg_size, instr->Rn()), shift_op,
shift);
}
set_reg(reg_size, instr->Rd(), result);
}
// The algorithm used is adapted from the one described in section 8.2 of
// Hacker's Delight, by Henry S. Warren, Jr.
// It assumes that a right shift on a signed integer is an arithmetic shift.
static int64_t MultiplyHighSigned(int64_t u, int64_t v) {
uint64_t u0, v0, w0;
int64_t u1, v1, w1, w2, t;
u0 = u & 0xffffffff;
u1 = u >> 32;
v0 = v & 0xffffffff;
v1 = v >> 32;
w0 = u0 * v0;
t = u1 * v0 + (w0 >> 32);
w1 = t & 0xffffffff;
w2 = t >> 32;
w1 = u0 * v1 + w1;
return u1 * v1 + w2 + (w1 >> 32);
}
void Simulator::VisitDataProcessing3Source(const Instruction* instr) {
unsigned reg_size = instr->SixtyFourBits() ? kXRegSize : kWRegSize;
int64_t result = 0;
// Extract and sign- or zero-extend 32-bit arguments for widening operations.
uint64_t rn_u32 = reg<uint32_t>(instr->Rn());
uint64_t rm_u32 = reg<uint32_t>(instr->Rm());
int64_t rn_s32 = reg<int32_t>(instr->Rn());
int64_t rm_s32 = reg<int32_t>(instr->Rm());
switch (instr->Mask(DataProcessing3SourceMask)) {
case MADD_w:
case MADD_x:
result = xreg(instr->Ra()) + (xreg(instr->Rn()) * xreg(instr->Rm()));
break;
case MSUB_w:
case MSUB_x:
result = xreg(instr->Ra()) - (xreg(instr->Rn()) * xreg(instr->Rm()));
break;
case SMADDL_x: result = xreg(instr->Ra()) + (rn_s32 * rm_s32); break;
case SMSUBL_x: result = xreg(instr->Ra()) - (rn_s32 * rm_s32); break;
case UMADDL_x: result = xreg(instr->Ra()) + (rn_u32 * rm_u32); break;
case UMSUBL_x: result = xreg(instr->Ra()) - (rn_u32 * rm_u32); break;
case SMULH_x:
result = MultiplyHighSigned(xreg(instr->Rn()), xreg(instr->Rm()));
break;
default: VIXL_UNIMPLEMENTED();
}
set_reg(reg_size, instr->Rd(), result);
}
void Simulator::VisitBitfield(const Instruction* instr) {
unsigned reg_size = instr->SixtyFourBits() ? kXRegSize : kWRegSize;
int64_t reg_mask = instr->SixtyFourBits() ? kXRegMask : kWRegMask;
int64_t R = instr->ImmR();
int64_t S = instr->ImmS();
int64_t diff = S - R;
int64_t mask;
if (diff >= 0) {
mask = (diff < (reg_size - 1)) ? (INT64_C(1) << (diff + 1)) - 1
: reg_mask;
} else {
mask = (INT64_C(1) << (S + 1)) - 1;
mask = (static_cast<uint64_t>(mask) >> R) | (mask << (reg_size - R));
diff += reg_size;
}
// inzero indicates if the extracted bitfield is inserted into the
// destination register value or in zero.
// If extend is true, extend the sign of the extracted bitfield.
bool inzero = false;
bool extend = false;
switch (instr->Mask(BitfieldMask)) {
case BFM_x:
case BFM_w:
break;
case SBFM_x:
case SBFM_w:
inzero = true;
extend = true;
break;
case UBFM_x:
case UBFM_w:
inzero = true;
break;
default:
VIXL_UNIMPLEMENTED();
}
int64_t dst = inzero ? 0 : reg(reg_size, instr->Rd());
int64_t src = reg(reg_size, instr->Rn());
// Rotate source bitfield into place.
int64_t result = (static_cast<uint64_t>(src) >> R) | (src << (reg_size - R));
// Determine the sign extension.
int64_t topbits = ((INT64_C(1) << (reg_size - diff - 1)) - 1) << (diff + 1);
int64_t signbits = extend && ((src >> S) & 1) ? topbits : 0;
// Merge sign extension, dest/zero and bitfield.
result = signbits | (result & mask) | (dst & ~mask);
set_reg(reg_size, instr->Rd(), result);
}
void Simulator::VisitExtract(const Instruction* instr) {
unsigned lsb = instr->ImmS();
unsigned reg_size = (instr->SixtyFourBits() != 0) ? kXRegSize
: kWRegSize;
uint64_t low_res = static_cast<uint64_t>(reg(reg_size, instr->Rm())) >> lsb;
uint64_t high_res =
(lsb == 0) ? 0 : reg(reg_size, instr->Rn()) << (reg_size - lsb);
set_reg(reg_size, instr->Rd(), low_res | high_res);
}
void Simulator::VisitFPImmediate(const Instruction* instr) {
AssertSupportedFPCR();
unsigned dest = instr->Rd();
switch (instr->Mask(FPImmediateMask)) {
case FMOV_s_imm: set_sreg(dest, instr->ImmFP32()); break;
case FMOV_d_imm: set_dreg(dest, instr->ImmFP64()); break;
default: VIXL_UNREACHABLE();
}
}
void Simulator::VisitFPIntegerConvert(const Instruction* instr) {
AssertSupportedFPCR();
unsigned dst = instr->Rd();
unsigned src = instr->Rn();
FPRounding round = RMode();
switch (instr->Mask(FPIntegerConvertMask)) {
case FCVTAS_ws: set_wreg(dst, FPToInt32(sreg(src), FPTieAway)); break;
case FCVTAS_xs: set_xreg(dst, FPToInt64(sreg(src), FPTieAway)); break;
case FCVTAS_wd: set_wreg(dst, FPToInt32(dreg(src), FPTieAway)); break;
case FCVTAS_xd: set_xreg(dst, FPToInt64(dreg(src), FPTieAway)); break;
case FCVTAU_ws: set_wreg(dst, FPToUInt32(sreg(src), FPTieAway)); break;
case FCVTAU_xs: set_xreg(dst, FPToUInt64(sreg(src), FPTieAway)); break;
case FCVTAU_wd: set_wreg(dst, FPToUInt32(dreg(src), FPTieAway)); break;
case FCVTAU_xd: set_xreg(dst, FPToUInt64(dreg(src), FPTieAway)); break;
case FCVTMS_ws:
set_wreg(dst, FPToInt32(sreg(src), FPNegativeInfinity));
break;
case FCVTMS_xs:
set_xreg(dst, FPToInt64(sreg(src), FPNegativeInfinity));
break;
case FCVTMS_wd:
set_wreg(dst, FPToInt32(dreg(src), FPNegativeInfinity));
break;
case FCVTMS_xd:
set_xreg(dst, FPToInt64(dreg(src), FPNegativeInfinity));
break;
case FCVTMU_ws:
set_wreg(dst, FPToUInt32(sreg(src), FPNegativeInfinity));
break;
case FCVTMU_xs:
set_xreg(dst, FPToUInt64(sreg(src), FPNegativeInfinity));
break;
case FCVTMU_wd:
set_wreg(dst, FPToUInt32(dreg(src), FPNegativeInfinity));
break;
case FCVTMU_xd:
set_xreg(dst, FPToUInt64(dreg(src), FPNegativeInfinity));
break;
case FCVTNS_ws: set_wreg(dst, FPToInt32(sreg(src), FPTieEven)); break;
case FCVTNS_xs: set_xreg(dst, FPToInt64(sreg(src), FPTieEven)); break;
case FCVTNS_wd: set_wreg(dst, FPToInt32(dreg(src), FPTieEven)); break;
case FCVTNS_xd: set_xreg(dst, FPToInt64(dreg(src), FPTieEven)); break;
case FCVTNU_ws: set_wreg(dst, FPToUInt32(sreg(src), FPTieEven)); break;
case FCVTNU_xs: set_xreg(dst, FPToUInt64(sreg(src), FPTieEven)); break;
case FCVTNU_wd: set_wreg(dst, FPToUInt32(dreg(src), FPTieEven)); break;
case FCVTNU_xd: set_xreg(dst, FPToUInt64(dreg(src), FPTieEven)); break;
case FCVTZS_ws: set_wreg(dst, FPToInt32(sreg(src), FPZero)); break;
case FCVTZS_xs: set_xreg(dst, FPToInt64(sreg(src), FPZero)); break;
case FCVTZS_wd: set_wreg(dst, FPToInt32(dreg(src), FPZero)); break;
case FCVTZS_xd: set_xreg(dst, FPToInt64(dreg(src), FPZero)); break;
case FCVTZU_ws: set_wreg(dst, FPToUInt32(sreg(src), FPZero)); break;
case FCVTZU_xs: set_xreg(dst, FPToUInt64(sreg(src), FPZero)); break;
case FCVTZU_wd: set_wreg(dst, FPToUInt32(dreg(src), FPZero)); break;
case FCVTZU_xd: set_xreg(dst, FPToUInt64(dreg(src), FPZero)); break;
case FMOV_ws: set_wreg(dst, sreg_bits(src)); break;
case FMOV_xd: set_xreg(dst, dreg_bits(src)); break;
case FMOV_sw: set_sreg_bits(dst, wreg(src)); break;
case FMOV_dx: set_dreg_bits(dst, xreg(src)); break;
// A 32-bit input can be handled in the same way as a 64-bit input, since
// the sign- or zero-extension will not affect the conversion.
case SCVTF_dx: set_dreg(dst, FixedToDouble(xreg(src), 0, round)); break;
case SCVTF_dw: set_dreg(dst, FixedToDouble(wreg(src), 0, round)); break;
case UCVTF_dx: set_dreg(dst, UFixedToDouble(xreg(src), 0, round)); break;
case UCVTF_dw: {
set_dreg(dst, UFixedToDouble(static_cast<uint32_t>(wreg(src)), 0, round));
break;
}
case SCVTF_sx: set_sreg(dst, FixedToFloat(xreg(src), 0, round)); break;
case SCVTF_sw: set_sreg(dst, FixedToFloat(wreg(src), 0, round)); break;
case UCVTF_sx: set_sreg(dst, UFixedToFloat(xreg(src), 0, round)); break;
case UCVTF_sw: {
set_sreg(dst, UFixedToFloat(static_cast<uint32_t>(wreg(src)), 0, round));
break;
}
default: VIXL_UNREACHABLE();
}
}
void Simulator::VisitFPFixedPointConvert(const Instruction* instr) {
AssertSupportedFPCR();
unsigned dst = instr->Rd();
unsigned src = instr->Rn();
int fbits = 64 - instr->FPScale();
FPRounding round = RMode();
switch (instr->Mask(FPFixedPointConvertMask)) {
// A 32-bit input can be handled in the same way as a 64-bit input, since
// the sign- or zero-extension will not affect the conversion.
case SCVTF_dx_fixed:
set_dreg(dst, FixedToDouble(xreg(src), fbits, round));
break;
case SCVTF_dw_fixed:
set_dreg(dst, FixedToDouble(wreg(src), fbits, round));
break;
case UCVTF_dx_fixed:
set_dreg(dst, UFixedToDouble(xreg(src), fbits, round));
break;
case UCVTF_dw_fixed: {
set_dreg(dst,
UFixedToDouble(static_cast<uint32_t>(wreg(src)), fbits, round));
break;
}
case SCVTF_sx_fixed:
set_sreg(dst, FixedToFloat(xreg(src), fbits, round));
break;
case SCVTF_sw_fixed:
set_sreg(dst, FixedToFloat(wreg(src), fbits, round));
break;
case UCVTF_sx_fixed:
set_sreg(dst, UFixedToFloat(xreg(src), fbits, round));
break;
case UCVTF_sw_fixed: {
set_sreg(dst,
UFixedToFloat(static_cast<uint32_t>(wreg(src)), fbits, round));
break;
}
default: VIXL_UNREACHABLE();
}
}
int32_t Simulator::FPToInt32(double value, FPRounding rmode) {
value = FPRoundInt(value, rmode);
if (value >= kWMaxInt) {
return kWMaxInt;
} else if (value < kWMinInt) {
return kWMinInt;
}
return std::isnan(value) ? 0 : static_cast<int32_t>(value);
}
int64_t Simulator::FPToInt64(double value, FPRounding rmode) {
value = FPRoundInt(value, rmode);
if (value >= kXMaxInt) {
return kXMaxInt;
} else if (value < kXMinInt) {
return kXMinInt;
}
return std::isnan(value) ? 0 : static_cast<int64_t>(value);
}
uint32_t Simulator::FPToUInt32(double value, FPRounding rmode) {
value = FPRoundInt(value, rmode);
if (value >= kWMaxUInt) {
return kWMaxUInt;
} else if (value < 0.0) {
return 0;
}
return std::isnan(value) ? 0 : static_cast<uint32_t>(value);
}
uint64_t Simulator::FPToUInt64(double value, FPRounding rmode) {
value = FPRoundInt(value, rmode);
if (value >= kXMaxUInt) {
return kXMaxUInt;
} else if (value < 0.0) {
return 0;
}
return std::isnan(value) ? 0 : static_cast<uint64_t>(value);
}
void Simulator::VisitFPCompare(const Instruction* instr) {
AssertSupportedFPCR();
switch (instr->Mask(FPCompareMask)) {
case FCMP_s: FPCompare(sreg(instr->Rn()), sreg(instr->Rm())); break;
case FCMP_d: FPCompare(dreg(instr->Rn()), dreg(instr->Rm())); break;
case FCMP_s_zero: FPCompare(sreg(instr->Rn()), 0.0f); break;
case FCMP_d_zero: FPCompare(dreg(instr->Rn()), 0.0); break;
default: VIXL_UNIMPLEMENTED();
}
}
void Simulator::VisitFPConditionalCompare(const Instruction* instr) {
AssertSupportedFPCR();
switch (instr->Mask(FPConditionalCompareMask)) {
case FCCMP_s:
if (ConditionPassed(instr->Condition())) {
FPCompare(sreg(instr->Rn()), sreg(instr->Rm()));
} else {
nzcv().SetFlags(instr->Nzcv());
}
break;
case FCCMP_d:
if (ConditionPassed(instr->Condition())) {
FPCompare(dreg(instr->Rn()), dreg(instr->Rm()));
} else {
nzcv().SetFlags(instr->Nzcv());
}
break;
default: VIXL_UNIMPLEMENTED();
}
}
void Simulator::VisitFPConditionalSelect(const Instruction* instr) {
AssertSupportedFPCR();
Instr selected;
if (ConditionPassed(instr->Condition())) {
selected = instr->Rn();
} else {
selected = instr->Rm();
}
switch (instr->Mask(FPConditionalSelectMask)) {
case FCSEL_s: set_sreg(instr->Rd(), sreg(selected)); break;
case FCSEL_d: set_dreg(instr->Rd(), dreg(selected)); break;
default: VIXL_UNIMPLEMENTED();
}
}
void Simulator::VisitFPDataProcessing1Source(const Instruction* instr) {
AssertSupportedFPCR();
unsigned fd = instr->Rd();
unsigned fn = instr->Rn();
switch (instr->Mask(FPDataProcessing1SourceMask)) {
case FMOV_s: set_sreg(fd, sreg(fn)); break;
case FMOV_d: set_dreg(fd, dreg(fn)); break;
case FABS_s: set_sreg(fd, fabsf(sreg(fn))); break;
case FABS_d: set_dreg(fd, fabs(dreg(fn))); break;
case FNEG_s: set_sreg(fd, -sreg(fn)); break;
case FNEG_d: set_dreg(fd, -dreg(fn)); break;
case FSQRT_s: set_sreg(fd, FPSqrt(sreg(fn))); break;
case FSQRT_d: set_dreg(fd, FPSqrt(dreg(fn))); break;
case FRINTA_s: set_sreg(fd, FPRoundInt(sreg(fn), FPTieAway)); break;
case FRINTA_d: set_dreg(fd, FPRoundInt(dreg(fn), FPTieAway)); break;
case FRINTM_s:
set_sreg(fd, FPRoundInt(sreg(fn), FPNegativeInfinity)); break;
case FRINTM_d:
set_dreg(fd, FPRoundInt(dreg(fn), FPNegativeInfinity)); break;
case FRINTN_s: set_sreg(fd, FPRoundInt(sreg(fn), FPTieEven)); break;
case FRINTN_d: set_dreg(fd, FPRoundInt(dreg(fn), FPTieEven)); break;
case FRINTZ_s: set_sreg(fd, FPRoundInt(sreg(fn), FPZero)); break;
case FRINTZ_d: set_dreg(fd, FPRoundInt(dreg(fn), FPZero)); break;
case FCVT_ds: set_dreg(fd, FPToDouble(sreg(fn))); break;
case FCVT_sd: set_sreg(fd, FPToFloat(dreg(fn), FPTieEven)); break;
default: VIXL_UNIMPLEMENTED();
}
}
// Assemble the specified IEEE-754 components into the target type and apply
// appropriate rounding.
// sign: 0 = positive, 1 = negative
// exponent: Unbiased IEEE-754 exponent.
// mantissa: The mantissa of the input. The top bit (which is not encoded for
// normal IEEE-754 values) must not be omitted. This bit has the
// value 'pow(2, exponent)'.
//
// The input value is assumed to be a normalized value. That is, the input may
// not be infinity or NaN. If the source value is subnormal, it must be
// normalized before calling this function such that the highest set bit in the
// mantissa has the value 'pow(2, exponent)'.
//
// Callers should use FPRoundToFloat or FPRoundToDouble directly, rather than
// calling a templated FPRound.
template <class T, int ebits, int mbits>
static T FPRound(int64_t sign, int64_t exponent, uint64_t mantissa,
FPRounding round_mode) {
VIXL_ASSERT((sign == 0) || (sign == 1));
// Only the FPTieEven rounding mode is implemented.
VIXL_ASSERT(round_mode == FPTieEven);
USE(round_mode);
// Rounding can promote subnormals to normals, and normals to infinities. For
// example, a double with exponent 127 (FLT_MAX_EXP) would appear to be
// encodable as a float, but rounding based on the low-order mantissa bits
// could make it overflow. With ties-to-even rounding, this value would become
// an infinity.
// ---- Rounding Method ----
//
// The exponent is irrelevant in the rounding operation, so we treat the
// lowest-order bit that will fit into the result ('onebit') as having
// the value '1'. Similarly, the highest-order bit that won't fit into
// the result ('halfbit') has the value '0.5'. The 'point' sits between
// 'onebit' and 'halfbit':
//
// These bits fit into the result.
// |---------------------|
// mantissa = 0bxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
// ||
// / |
// / halfbit
// onebit
//
// For subnormal outputs, the range of representable bits is smaller and
// the position of onebit and halfbit depends on the exponent of the
// input, but the method is otherwise similar.
//
// onebit(frac)
// |
// | halfbit(frac) halfbit(adjusted)
// | / /
// | | |
// 0b00.0 (exact) -> 0b00.0 (exact) -> 0b00
// 0b00.0... -> 0b00.0... -> 0b00
// 0b00.1 (exact) -> 0b00.0111..111 -> 0b00
// 0b00.1... -> 0b00.1... -> 0b01
// 0b01.0 (exact) -> 0b01.0 (exact) -> 0b01
// 0b01.0... -> 0b01.0... -> 0b01
// 0b01.1 (exact) -> 0b01.1 (exact) -> 0b10
// 0b01.1... -> 0b01.1... -> 0b10
// 0b10.0 (exact) -> 0b10.0 (exact) -> 0b10
// 0b10.0... -> 0b10.0... -> 0b10
// 0b10.1 (exact) -> 0b10.0111..111 -> 0b10
// 0b10.1... -> 0b10.1... -> 0b11
// 0b11.0 (exact) -> 0b11.0 (exact) -> 0b11
// ... / | / |
// / | / |
// / |
// adjusted = frac - (halfbit(mantissa) & ~onebit(frac)); / |
//
// mantissa = (mantissa >> shift) + halfbit(adjusted);
static const int mantissa_offset = 0;
static const int exponent_offset = mantissa_offset + mbits;
static const int sign_offset = exponent_offset + ebits;
VIXL_ASSERT(sign_offset == (sizeof(T) * 8 - 1));
// Bail out early for zero inputs.
if (mantissa == 0) {
return sign << sign_offset;
}
// If all bits in the exponent are set, the value is infinite or NaN.
// This is true for all binary IEEE-754 formats.
static const int infinite_exponent = (1 << ebits) - 1;
static const int max_normal_exponent = infinite_exponent - 1;
// Apply the exponent bias to encode it for the result. Doing this early makes
// it easy to detect values that will be infinite or subnormal.
exponent += max_normal_exponent >> 1;
if (exponent > max_normal_exponent) {
// Overflow: The input is too large for the result type to represent. The
// FPTieEven rounding mode handles overflows using infinities.
exponent = infinite_exponent;
mantissa = 0;
return (sign << sign_offset) |
(exponent << exponent_offset) |
(mantissa << mantissa_offset);
}
// Calculate the shift required to move the top mantissa bit to the proper
// place in the destination type.
const int highest_significant_bit = 63 - CountLeadingZeros(mantissa, 64);
int shift = highest_significant_bit - mbits;
if (exponent <= 0) {
// The output will be subnormal (before rounding).
// For subnormal outputs, the shift must be adjusted by the exponent. The +1
// is necessary because the exponent of a subnormal value (encoded as 0) is
// the same as the exponent of the smallest normal value (encoded as 1).
shift += -exponent + 1;
// Handle inputs that would produce a zero output.
//
// Shifts higher than highest_significant_bit+1 will always produce a zero
// result. A shift of exactly highest_significant_bit+1 might produce a
// non-zero result after rounding.
if (shift > (highest_significant_bit + 1)) {
// The result will always be +/-0.0.
return sign << sign_offset;
}
// Properly encode the exponent for a subnormal output.
exponent = 0;
} else {
// Clear the topmost mantissa bit, since this is not encoded in IEEE-754
// normal values.
mantissa &= ~(UINT64_C(1) << highest_significant_bit);
}
if (shift > 0) {
// We have to shift the mantissa to the right. Some precision is lost, so we
// need to apply rounding.
uint64_t onebit_mantissa = (mantissa >> (shift)) & 1;
uint64_t halfbit_mantissa = (mantissa >> (shift-1)) & 1;
uint64_t adjusted = mantissa - (halfbit_mantissa & ~onebit_mantissa);
T halfbit_adjusted = (adjusted >> (shift-1)) & 1;
T result = (sign << sign_offset) |
(exponent << exponent_offset) |
((mantissa >> shift) << mantissa_offset);
// A very large mantissa can overflow during rounding. If this happens, the
// exponent should be incremented and the mantissa set to 1.0 (encoded as
// 0). Applying halfbit_adjusted after assembling the float has the nice
// side-effect that this case is handled for free.
//
// This also handles cases where a very large finite value overflows to
// infinity, or where a very large subnormal value overflows to become
// normal.
return result + halfbit_adjusted;
} else {
// We have to shift the mantissa to the left (or not at all). The input
// mantissa is exactly representable in the output mantissa, so apply no
// rounding correction.
return (sign << sign_offset) |
(exponent << exponent_offset) |
((mantissa << -shift) << mantissa_offset);
}
}
// See FPRound for a description of this function.
static inline double FPRoundToDouble(int64_t sign, int64_t exponent,
uint64_t mantissa, FPRounding round_mode) {
int64_t bits =
FPRound<int64_t, kDoubleExponentBits, kDoubleMantissaBits>(sign,
exponent,
mantissa,
round_mode);
return rawbits_to_double(bits);
}
// See FPRound for a description of this function.
static inline float FPRoundToFloat(int64_t sign, int64_t exponent,
uint64_t mantissa, FPRounding round_mode) {
int32_t bits =
FPRound<int32_t, kFloatExponentBits, kFloatMantissaBits>(sign,
exponent,
mantissa,
round_mode);
return rawbits_to_float(bits);
}
double Simulator::FixedToDouble(int64_t src, int fbits, FPRounding round) {
if (src >= 0) {
return UFixedToDouble(src, fbits, round);
} else {
// This works for all negative values, including INT64_MIN.
return -UFixedToDouble(-src, fbits, round);
}
}
double Simulator::UFixedToDouble(uint64_t src, int fbits, FPRounding round) {
// An input of 0 is a special case because the result is effectively
// subnormal: The exponent is encoded as 0 and there is no implicit 1 bit.
if (src == 0) {
return 0.0;
}
// Calculate the exponent. The highest significant bit will have the value
// 2^exponent.
const int highest_significant_bit = 63 - CountLeadingZeros(src, 64);
const int64_t exponent = highest_significant_bit - fbits;
return FPRoundToDouble(0, exponent, src, round);
}
float Simulator::FixedToFloat(int64_t src, int fbits, FPRounding round) {
if (src >= 0) {
return UFixedToFloat(src, fbits, round);
} else {
// This works for all negative values, including INT64_MIN.
return -UFixedToFloat(-src, fbits, round);
}
}
float Simulator::UFixedToFloat(uint64_t src, int fbits, FPRounding round) {
// An input of 0 is a special case because the result is effectively
// subnormal: The exponent is encoded as 0 and there is no implicit 1 bit.
if (src == 0) {
return 0.0f;
}
// Calculate the exponent. The highest significant bit will have the value
// 2^exponent.
const int highest_significant_bit = 63 - CountLeadingZeros(src, 64);
const int32_t exponent = highest_significant_bit - fbits;
return FPRoundToFloat(0, exponent, src, round);
}
double Simulator::FPRoundInt(double value, FPRounding round_mode) {
if ((value == 0.0) || (value == kFP64PositiveInfinity) ||
(value == kFP64NegativeInfinity)) {
return value;
} else if (std::isnan(value)) {
return FPProcessNaN(value);
}
double int_result = floor(value);
double error = value - int_result;
switch (round_mode) {
case FPTieAway: {
// Take care of correctly handling the range ]-0.5, -0.0], which must
// yield -0.0.
if ((-0.5 < value) && (value < 0.0)) {
int_result = -0.0;
} else if ((error > 0.5) || ((error == 0.5) && (int_result >= 0.0))) {
// If the error is greater than 0.5, or is equal to 0.5 and the integer
// result is positive, round up.
int_result++;
}
break;
}
case FPTieEven: {
// Take care of correctly handling the range [-0.5, -0.0], which must
// yield -0.0.
if ((-0.5 <= value) && (value < 0.0)) {
int_result = -0.0;
// If the error is greater than 0.5, or is equal to 0.5 and the integer
// result is odd, round up.
} else if ((error > 0.5) ||
((error == 0.5) && (fmod(int_result, 2) != 0))) {
int_result++;
}
break;
}
case FPZero: {
// If value>0 then we take floor(value)
// otherwise, ceil(value).
if (value < 0) {
int_result = ceil(value);
}
break;
}
case FPNegativeInfinity: {
// We always use floor(value).
break;
}
default: VIXL_UNIMPLEMENTED();
}
return int_result;
}
double Simulator::FPToDouble(float value) {
switch (std::fpclassify(value)) {
case FP_NAN: {
if (DN()) return kFP64DefaultNaN;
// Convert NaNs as the processor would:
// - The sign is propagated.
// - The payload (mantissa) is transferred entirely, except that the top
// bit is forced to '1', making the result a quiet NaN. The unused
// (low-order) payload bits are set to 0.
uint32_t raw = float_to_rawbits(value);
uint64_t sign = raw >> 31;
uint64_t exponent = (1 << 11) - 1;
uint64_t payload = unsigned_bitextract_64(21, 0, raw);
payload <<= (52 - 23); // The unused low-order bits should be 0.
payload |= (UINT64_C(1) << 51); // Force a quiet NaN.
return rawbits_to_double((sign << 63) | (exponent << 52) | payload);
}
case FP_ZERO:
case FP_NORMAL:
case FP_SUBNORMAL:
case FP_INFINITE: {
// All other inputs are preserved in a standard cast, because every value
// representable using an IEEE-754 float is also representable using an
// IEEE-754 double.
return static_cast<double>(value);
}
}
VIXL_UNREACHABLE();
return static_cast<double>(value);
}
float Simulator::FPToFloat(double value, FPRounding round_mode) {
// Only the FPTieEven rounding mode is implemented.
VIXL_ASSERT(round_mode == FPTieEven);
USE(round_mode);
switch (std::fpclassify(value)) {
case FP_NAN: {
if (DN()) return kFP32DefaultNaN;
// Convert NaNs as the processor would:
// - The sign is propagated.
// - The payload (mantissa) is transferred as much as possible, except
// that the top bit is forced to '1', making the result a quiet NaN.
uint64_t raw = double_to_rawbits(value);
uint32_t sign = raw >> 63;
uint32_t exponent = (1 << 8) - 1;
uint32_t payload = unsigned_bitextract_64(50, 52 - 23, raw);
payload |= (1 << 22); // Force a quiet NaN.
return rawbits_to_float((sign << 31) | (exponent << 23) | payload);
}
case FP_ZERO:
case FP_INFINITE: {
// In a C++ cast, any value representable in the target type will be
// unchanged. This is always the case for +/-0.0 and infinities.
return static_cast<float>(value);
}
case FP_NORMAL:
case FP_SUBNORMAL: {
// Convert double-to-float as the processor would, assuming that FPCR.FZ
// (flush-to-zero) is not set.
uint64_t raw = double_to_rawbits(value);
// Extract the IEEE-754 double components.
uint32_t sign = raw >> 63;
// Extract the exponent and remove the IEEE-754 encoding bias.
int32_t exponent = unsigned_bitextract_64(62, 52, raw) - 1023;
// Extract the mantissa and add the implicit '1' bit.
uint64_t mantissa = unsigned_bitextract_64(51, 0, raw);
if (std::fpclassify(value) == FP_NORMAL) {
mantissa |= (UINT64_C(1) << 52);
}
return FPRoundToFloat(sign, exponent, mantissa, round_mode);
}
}
VIXL_UNREACHABLE();
return value;
}
void Simulator::VisitFPDataProcessing2Source(const Instruction* instr) {
AssertSupportedFPCR();
unsigned fd = instr->Rd();
unsigned fn = instr->Rn();
unsigned fm = instr->Rm();
// Fmaxnm and Fminnm have special NaN handling.
switch (instr->Mask(FPDataProcessing2SourceMask)) {
case FMAXNM_s: set_sreg(fd, FPMaxNM(sreg(fn), sreg(fm))); return;
case FMAXNM_d: set_dreg(fd, FPMaxNM(dreg(fn), dreg(fm))); return;
case FMINNM_s: set_sreg(fd, FPMinNM(sreg(fn), sreg(fm))); return;
case FMINNM_d: set_dreg(fd, FPMinNM(dreg(fn), dreg(fm))); return;
default:
break; // Fall through.
}
if (FPProcessNaNs(instr)) return;
switch (instr->Mask(FPDataProcessing2SourceMask)) {
case FADD_s: set_sreg(fd, FPAdd(sreg(fn), sreg(fm))); break;
case FADD_d: set_dreg(fd, FPAdd(dreg(fn), dreg(fm))); break;
case FSUB_s: set_sreg(fd, FPSub(sreg(fn), sreg(fm))); break;
case FSUB_d: set_dreg(fd, FPSub(dreg(fn), dreg(fm))); break;
case FMUL_s: set_sreg(fd, FPMul(sreg(fn), sreg(fm))); break;
case FMUL_d: set_dreg(fd, FPMul(dreg(fn), dreg(fm))); break;
case FDIV_s: set_sreg(fd, FPDiv(sreg(fn), sreg(fm))); break;
case FDIV_d: set_dreg(fd, FPDiv(dreg(fn), dreg(fm))); break;
case FMAX_s: set_sreg(fd, FPMax(sreg(fn), sreg(fm))); break;
case FMAX_d: set_dreg(fd, FPMax(dreg(fn), dreg(fm))); break;
case FMIN_s: set_sreg(fd, FPMin(sreg(fn), sreg(fm))); break;
case FMIN_d: set_dreg(fd, FPMin(dreg(fn), dreg(fm))); break;
case FMAXNM_s:
case FMAXNM_d:
case FMINNM_s:
case FMINNM_d:
// These were handled before the standard FPProcessNaNs() stage.
VIXL_UNREACHABLE();
default: VIXL_UNIMPLEMENTED();
}
}
void Simulator::VisitFPDataProcessing3Source(const Instruction* instr) {
AssertSupportedFPCR();
unsigned fd = instr->Rd();
unsigned fn = instr->Rn();
unsigned fm = instr->Rm();
unsigned fa = instr->Ra();
switch (instr->Mask(FPDataProcessing3SourceMask)) {
// fd = fa +/- (fn * fm)
case FMADD_s: set_sreg(fd, FPMulAdd(sreg(fa), sreg(fn), sreg(fm))); break;
case FMSUB_s: set_sreg(fd, FPMulAdd(sreg(fa), -sreg(fn), sreg(fm))); break;
case FMADD_d: set_dreg(fd, FPMulAdd(dreg(fa), dreg(fn), dreg(fm))); break;
case FMSUB_d: set_dreg(fd, FPMulAdd(dreg(fa), -dreg(fn), dreg(fm))); break;
// Negated variants of the above.
case FNMADD_s:
set_sreg(fd, FPMulAdd(-sreg(fa), -sreg(fn), sreg(fm)));
break;
case FNMSUB_s:
set_sreg(fd, FPMulAdd(-sreg(fa), sreg(fn), sreg(fm)));
break;
case FNMADD_d:
set_dreg(fd, FPMulAdd(-dreg(fa), -dreg(fn), dreg(fm)));
break;
case FNMSUB_d:
set_dreg(fd, FPMulAdd(-dreg(fa), dreg(fn), dreg(fm)));
break;
default: VIXL_UNIMPLEMENTED();
}
}
template <typename T>
T Simulator::FPAdd(T op1, T op2) {
// NaNs should be handled elsewhere.
VIXL_ASSERT(!std::isnan(op1) && !std::isnan(op2));
if (std::isinf(op1) && std::isinf(op2) && (op1 != op2)) {
// inf + -inf returns the default NaN.
FPProcessException();
return FPDefaultNaN<T>();
} else {
// Other cases should be handled by standard arithmetic.
return op1 + op2;
}
}
template <typename T>
T Simulator::FPDiv(T op1, T op2) {
// NaNs should be handled elsewhere.
VIXL_ASSERT(!std::isnan(op1) && !std::isnan(op2));
if ((std::isinf(op1) && std::isinf(op2)) || ((op1 == 0.0) && (op2 == 0.0))) {
// inf / inf and 0.0 / 0.0 return the default NaN.
FPProcessException();
return FPDefaultNaN<T>();
} else {
if (op2 == 0.0) FPProcessException();
// Other cases should be handled by standard arithmetic.
return op1 / op2;
}
}
template <typename T>
T Simulator::FPMax(T a, T b) {
// NaNs should be handled elsewhere.
VIXL_ASSERT(!std::isnan(a) && !std::isnan(b));
if ((a == 0.0) && (b == 0.0) &&
(copysign(1.0, a) != copysign(1.0, b))) {
// a and b are zero, and the sign differs: return +0.0.
return 0.0;
} else {
return (a > b) ? a : b;
}
}
template <typename T>
T Simulator::FPMaxNM(T a, T b) {
if (IsQuietNaN(a) && !IsQuietNaN(b)) {
a = kFP64NegativeInfinity;
} else if (!IsQuietNaN(a) && IsQuietNaN(b)) {
b = kFP64NegativeInfinity;
}
T result = FPProcessNaNs(a, b);
return std::isnan(result) ? result : FPMax(a, b);
}
template <typename T>
T Simulator::FPMin(T a, T b) {
// NaNs should be handled elsewhere.
VIXL_ASSERT(!std::isnan(a) && !std::isnan(b));
if ((a == 0.0) && (b == 0.0) &&
(copysign(1.0, a) != copysign(1.0, b))) {
// a and b are zero, and the sign differs: return -0.0.
return -0.0;
} else {
return (a < b) ? a : b;
}
}
template <typename T>
T Simulator::FPMinNM(T a, T b) {
if (IsQuietNaN(a) && !IsQuietNaN(b)) {
a = kFP64PositiveInfinity;
} else if (!IsQuietNaN(a) && IsQuietNaN(b)) {
b = kFP64PositiveInfinity;
}
T result = FPProcessNaNs(a, b);
return std::isnan(result) ? result : FPMin(a, b);
}
template <typename T>
T Simulator::FPMul(T op1, T op2) {
// NaNs should be handled elsewhere.
VIXL_ASSERT(!std::isnan(op1) && !std::isnan(op2));
if ((std::isinf(op1) && (op2 == 0.0)) || (std::isinf(op2) && (op1 == 0.0))) {
// inf * 0.0 returns the default NaN.
FPProcessException();
return FPDefaultNaN<T>();
} else {
// Other cases should be handled by standard arithmetic.
return op1 * op2;
}
}
template<typename T>
T Simulator::FPMulAdd(T a, T op1, T op2) {
T result = FPProcessNaNs3(a, op1, op2);
T sign_a = copysign(1.0, a);
T sign_prod = copysign(1.0, op1) * copysign(1.0, op2);
bool isinf_prod = std::isinf(op1) || std::isinf(op2);
bool operation_generates_nan =
(std::isinf(op1) && (op2 == 0.0)) || // inf * 0.0
(std::isinf(op2) && (op1 == 0.0)) || // 0.0 * inf
(std::isinf(a) && isinf_prod && (sign_a != sign_prod)); // inf - inf
if (std::isnan(result)) {
// Generated NaNs override quiet NaNs propagated from a.
if (operation_generates_nan && IsQuietNaN(a)) {
FPProcessException();
return FPDefaultNaN<T>();
} else {
return result;
}
}
// If the operation would produce a NaN, return the default NaN.
if (operation_generates_nan) {
FPProcessException();
return FPDefaultNaN<T>();
}
// Work around broken fma implementations for exact zero results: The sign of
// exact 0.0 results is positive unless both a and op1 * op2 are negative.
if (((op1 == 0.0) || (op2 == 0.0)) && (a == 0.0)) {
return ((sign_a < 0) && (sign_prod < 0)) ? -0.0 : 0.0;
}
result = FusedMultiplyAdd(op1, op2, a);
VIXL_ASSERT(!std::isnan(result));
// Work around broken fma implementations for rounded zero results: If a is
// 0.0, the sign of the result is the sign of op1 * op2 before rounding.
if ((a == 0.0) && (result == 0.0)) {
return copysign(0.0, sign_prod);
}
return result;
}
template <typename T>
T Simulator::FPSub(T op1, T op2) {
// NaNs should be handled elsewhere.
VIXL_ASSERT(!std::isnan(op1) && !std::isnan(op2));
if (std::isinf(op1) && std::isinf(op2) && (op1 == op2)) {
// inf - inf returns the default NaN.
FPProcessException();
return FPDefaultNaN<T>();
} else {
// Other cases should be handled by standard arithmetic.
return op1 - op2;
}
}
template <typename T>
T Simulator::FPSqrt(T op) {
if (std::isnan(op)) {
return FPProcessNaN(op);
} else if (op < 0.0) {
FPProcessException();
return FPDefaultNaN<T>();
} else {
return sqrt(op);
}
}
template <typename T>
T Simulator::FPProcessNaN(T op) {
VIXL_ASSERT(std::isnan(op));
if (IsSignallingNaN(op)) {
FPProcessException();
}
return DN() ? FPDefaultNaN<T>() : ToQuietNaN(op);
}
template <typename T>
T Simulator::FPProcessNaNs(T op1, T op2) {
if (IsSignallingNaN(op1)) {
return FPProcessNaN(op1);
} else if (IsSignallingNaN(op2)) {
return FPProcessNaN(op2);
} else if (std::isnan(op1)) {
VIXL_ASSERT(IsQuietNaN(op1));
return FPProcessNaN(op1);
} else if (std::isnan(op2)) {
VIXL_ASSERT(IsQuietNaN(op2));
return FPProcessNaN(op2);
} else {
return 0.0;
}
}
template <typename T>
T Simulator::FPProcessNaNs3(T op1, T op2, T op3) {
if (IsSignallingNaN(op1)) {
return FPProcessNaN(op1);
} else if (IsSignallingNaN(op2)) {
return FPProcessNaN(op2);
} else if (IsSignallingNaN(op3)) {
return FPProcessNaN(op3);
} else if (std::isnan(op1)) {
VIXL_ASSERT(IsQuietNaN(op1));
return FPProcessNaN(op1);
} else if (std::isnan(op2)) {
VIXL_ASSERT(IsQuietNaN(op2));
return FPProcessNaN(op2);
} else if (std::isnan(op3)) {
VIXL_ASSERT(IsQuietNaN(op3));
return FPProcessNaN(op3);
} else {
return 0.0;
}
}
bool Simulator::FPProcessNaNs(const Instruction* instr) {
unsigned fd = instr->Rd();
unsigned fn = instr->Rn();
unsigned fm = instr->Rm();
bool done = false;
if (instr->Mask(FP64) == FP64) {
double result = FPProcessNaNs(dreg(fn), dreg(fm));
if (std::isnan(result)) {
set_dreg(fd, result);
done = true;
}
} else {
float result = FPProcessNaNs(sreg(fn), sreg(fm));
if (std::isnan(result)) {
set_sreg(fd, result);
done = true;
}
}
return done;
}
void Simulator::VisitSystem(const Instruction* instr) {
// Some system instructions hijack their Op and Cp fields to represent a
// range of immediates instead of indicating a different instruction. This
// makes the decoding tricky.
if (instr->Mask(SystemExclusiveMonitorFMask) == SystemExclusiveMonitorFixed) {
VIXL_ASSERT(instr->Mask(SystemExclusiveMonitorMask) == CLREX);
switch (instr->Mask(SystemExclusiveMonitorMask)) {
case CLREX: {
PrintExclusiveAccessWarning();
ClearLocalMonitor();
break;
}
}
} else if (instr->Mask(SystemSysRegFMask) == SystemSysRegFixed) {
switch (instr->Mask(SystemSysRegMask)) {
case MRS: {
switch (instr->ImmSystemRegister()) {
case NZCV: set_xreg(instr->Rt(), nzcv().RawValue()); break;
case FPCR: set_xreg(instr->Rt(), fpcr().RawValue()); break;
default: VIXL_UNIMPLEMENTED();
}
break;
}
case MSR: {
switch (instr->ImmSystemRegister()) {
case NZCV: nzcv().SetRawValue(xreg(instr->Rt())); break;
case FPCR: fpcr().SetRawValue(xreg(instr->Rt())); break;
default: VIXL_UNIMPLEMENTED();
}
break;
}
}
} else if (instr->Mask(SystemHintFMask) == SystemHintFixed) {
VIXL_ASSERT(instr->Mask(SystemHintMask) == HINT);
switch (instr->ImmHint()) {
case NOP: break;
default: VIXL_UNIMPLEMENTED();
}
} else if (instr->Mask(MemBarrierFMask) == MemBarrierFixed) {
__sync_synchronize();
} else {
VIXL_UNIMPLEMENTED();
}
}
void Simulator::VisitException(const Instruction* instr) {
switch (instr->Mask(ExceptionMask)) {
case BRK: HostBreakpoint(); break;
case HLT:
// The Printf pseudo instruction is so useful, we include it in the
// default simulator.
if (instr->ImmException() == kPrintfOpcode) {
DoPrintf(instr);
} else {
HostBreakpoint();
}
break;
default:
VIXL_UNIMPLEMENTED();
}
}
void Simulator::DoPrintf(const Instruction* instr) {
VIXL_ASSERT((instr->Mask(ExceptionMask) == HLT) &&
(instr->ImmException() == kPrintfOpcode));
// Read the arguments encoded inline in the instruction stream.
uint32_t arg_count;
uint32_t arg_pattern_list;
VIXL_STATIC_ASSERT(sizeof(*instr) == 1);
memcpy(&arg_count,
instr + kPrintfArgCountOffset,
sizeof(arg_count));
memcpy(&arg_pattern_list,
instr + kPrintfArgPatternListOffset,
sizeof(arg_pattern_list));
VIXL_ASSERT(arg_count <= kPrintfMaxArgCount);
VIXL_ASSERT((arg_pattern_list >> (kPrintfArgPatternBits * arg_count)) == 0);
// We need to call the host printf function with a set of arguments defined by
// arg_pattern_list. Because we don't know the types and sizes of the
// arguments, this is very difficult to do in a robust and portable way. To
// work around the problem, we pick apart the format string, and print one
// format placeholder at a time.
// Allocate space for the format string. We take a copy, so we can modify it.
// Leave enough space for one extra character per expected argument (plus the
// '\0' termination).
const char * format_base = reg<const char *>(0);
VIXL_ASSERT(format_base != NULL);
size_t length = strlen(format_base) + 1;
char * const format = new char[length + arg_count];
// A list of chunks, each with exactly one format placeholder.
const char * chunks[kPrintfMaxArgCount];
// Copy the format string and search for format placeholders.
uint32_t placeholder_count = 0;
char * format_scratch = format;
for (size_t i = 0; i < length; i++) {
if (format_base[i] != '%') {
*format_scratch++ = format_base[i];
} else {
if (format_base[i + 1] == '%') {
// Ignore explicit "%%" sequences.
*format_scratch++ = format_base[i];
i++;
// Chunks after the first are passed as format strings to printf, so we
// need to escape '%' characters in those chunks.
if (placeholder_count > 0) *format_scratch++ = format_base[i];
} else {
VIXL_CHECK(placeholder_count < arg_count);
// Insert '\0' before placeholders, and store their locations.
*format_scratch++ = '\0';
chunks[placeholder_count++] = format_scratch;
*format_scratch++ = format_base[i];
}
}
}
VIXL_CHECK(placeholder_count == arg_count);
// Finally, call printf with each chunk, passing the appropriate register
// argument. Normally, printf returns the number of bytes transmitted, so we
// can emulate a single printf call by adding the result from each chunk. If
// any call returns a negative (error) value, though, just return that value.
printf("%s", clr_printf);
// Because '\0' is inserted before each placeholder, the first string in
// 'format' contains no format placeholders and should be printed literally.
int result = printf("%s", format);
int pcs_r = 1; // Start at x1. x0 holds the format string.
int pcs_f = 0; // Start at d0.
if (result >= 0) {
for (uint32_t i = 0; i < placeholder_count; i++) {
int part_result = -1;
uint32_t arg_pattern = arg_pattern_list >> (i * kPrintfArgPatternBits);
arg_pattern &= (1 << kPrintfArgPatternBits) - 1;
switch (arg_pattern) {
case kPrintfArgW: part_result = printf(chunks[i], wreg(pcs_r++)); break;
case kPrintfArgX: part_result = printf(chunks[i], xreg(pcs_r++)); break;
case kPrintfArgD: part_result = printf(chunks[i], dreg(pcs_f++)); break;
default: VIXL_UNREACHABLE();
}
if (part_result < 0) {
// Handle error values.
result = part_result;
break;
}
result += part_result;
}
}
printf("%s", clr_normal);
// Printf returns its result in x0 (just like the C library's printf).
set_xreg(0, result);
// The printf parameters are inlined in the code, so skip them.
set_pc(instr->InstructionAtOffset(kPrintfLength));
// Set LR as if we'd just called a native printf function.
set_lr(pc());
delete[] format;
}
} // namespace vixl
#endif // USE_SIMULATOR