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// Copyright 2018 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/codegen/handler-table.h"
#include <iomanip>
#include "src/codegen/assembler-inl.h"
#include "src/objects/code-inl.h"
#include "src/objects/objects-inl.h"
namespace v8 {
namespace internal {
HandlerTable::HandlerTable(Code code)
: HandlerTable(code.InstructionStart() + code.handler_table_offset(),
code.handler_table_size(), kReturnAddressBasedEncoding) {}
HandlerTable::HandlerTable(BytecodeArray bytecode_array)
: HandlerTable(bytecode_array.handler_table()) {}
HandlerTable::HandlerTable(ByteArray byte_array)
: HandlerTable(reinterpret_cast<Address>(byte_array.GetDataStartAddress()),
byte_array.length(), kRangeBasedEncoding) {}
HandlerTable::HandlerTable(Address handler_table, int handler_table_size,
EncodingMode encoding_mode)
: number_of_entries_(handler_table_size / EntrySizeFromMode(encoding_mode) /
sizeof(int32_t)),
#ifdef DEBUG
mode_(encoding_mode),
#endif
raw_encoded_data_(handler_table) {
// Check padding.
static_assert(4 < kReturnEntrySize * sizeof(int32_t), "allowed padding");
// For return address encoding, maximum padding is 4; otherwise, there should
// be no padding.
DCHECK_GE(kReturnAddressBasedEncoding == encoding_mode ? 4 : 0,
handler_table_size %
(EntrySizeFromMode(encoding_mode) * sizeof(int32_t)));
}
// static
int HandlerTable::EntrySizeFromMode(EncodingMode mode) {
switch (mode) {
case kReturnAddressBasedEncoding:
return kReturnEntrySize;
case kRangeBasedEncoding:
return kRangeEntrySize;
}
UNREACHABLE();
}
int HandlerTable::GetRangeStart(int index) const {
DCHECK_EQ(kRangeBasedEncoding, mode_);
DCHECK_LT(index, NumberOfRangeEntries());
int offset = index * kRangeEntrySize + kRangeStartIndex;
return Memory<int32_t>(raw_encoded_data_ + offset * sizeof(int32_t));
}
int HandlerTable::GetRangeEnd(int index) const {
DCHECK_EQ(kRangeBasedEncoding, mode_);
DCHECK_LT(index, NumberOfRangeEntries());
int offset = index * kRangeEntrySize + kRangeEndIndex;
return Memory<int32_t>(raw_encoded_data_ + offset * sizeof(int32_t));
}
int HandlerTable::GetRangeHandler(int index) const {
DCHECK_EQ(kRangeBasedEncoding, mode_);
DCHECK_LT(index, NumberOfRangeEntries());
int offset = index * kRangeEntrySize + kRangeHandlerIndex;
return HandlerOffsetField::decode(
Memory<int32_t>(raw_encoded_data_ + offset * sizeof(int32_t)));
}
int HandlerTable::GetRangeData(int index) const {
DCHECK_EQ(kRangeBasedEncoding, mode_);
DCHECK_LT(index, NumberOfRangeEntries());
int offset = index * kRangeEntrySize + kRangeDataIndex;
return Memory<int32_t>(raw_encoded_data_ + offset * sizeof(int32_t));
}
HandlerTable::CatchPrediction HandlerTable::GetRangePrediction(
int index) const {
DCHECK_EQ(kRangeBasedEncoding, mode_);
DCHECK_LT(index, NumberOfRangeEntries());
int offset = index * kRangeEntrySize + kRangeHandlerIndex;
return HandlerPredictionField::decode(
Memory<int32_t>(raw_encoded_data_ + offset * sizeof(int32_t)));
}
int HandlerTable::GetReturnOffset(int index) const {
DCHECK_EQ(kReturnAddressBasedEncoding, mode_);
DCHECK_LT(index, NumberOfReturnEntries());
int offset = index * kReturnEntrySize + kReturnOffsetIndex;
return Memory<int32_t>(raw_encoded_data_ + offset * sizeof(int32_t));
}
int HandlerTable::GetReturnHandler(int index) const {
DCHECK_EQ(kReturnAddressBasedEncoding, mode_);
DCHECK_LT(index, NumberOfReturnEntries());
int offset = index * kReturnEntrySize + kReturnHandlerIndex;
return HandlerOffsetField::decode(
Memory<int32_t>(raw_encoded_data_ + offset * sizeof(int32_t)));
}
void HandlerTable::SetRangeStart(int index, int value) {
int offset = index * kRangeEntrySize + kRangeStartIndex;
Memory<int32_t>(raw_encoded_data_ + offset * sizeof(int32_t)) = value;
}
void HandlerTable::SetRangeEnd(int index, int value) {
int offset = index * kRangeEntrySize + kRangeEndIndex;
Memory<int32_t>(raw_encoded_data_ + offset * sizeof(int32_t)) = value;
}
void HandlerTable::SetRangeHandler(int index, int handler_offset,
CatchPrediction prediction) {
int value = HandlerOffsetField::encode(handler_offset) |
HandlerPredictionField::encode(prediction);
int offset = index * kRangeEntrySize + kRangeHandlerIndex;
Memory<int32_t>(raw_encoded_data_ + offset * sizeof(int32_t)) = value;
}
void HandlerTable::SetRangeData(int index, int value) {
int offset = index * kRangeEntrySize + kRangeDataIndex;
Memory<int32_t>(raw_encoded_data_ + offset * sizeof(int32_t)) = value;
}
// static
int HandlerTable::LengthForRange(int entries) {
return entries * kRangeEntrySize * sizeof(int32_t);
}
// static
int HandlerTable::EmitReturnTableStart(Assembler* masm) {
masm->DataAlign(sizeof(int32_t)); // Make sure entries are aligned.
masm->RecordComment(";;; Exception handler table.");
int table_start = masm->pc_offset();
return table_start;
}
// static
void HandlerTable::EmitReturnEntry(Assembler* masm, int offset, int handler) {
masm->dd(offset);
masm->dd(HandlerOffsetField::encode(handler));
}
int HandlerTable::NumberOfRangeEntries() const {
DCHECK_EQ(kRangeBasedEncoding, mode_);
return number_of_entries_;
}
int HandlerTable::NumberOfReturnEntries() const {
DCHECK_EQ(kReturnAddressBasedEncoding, mode_);
return number_of_entries_;
}
int HandlerTable::LookupRange(int pc_offset, int* data_out,
CatchPrediction* prediction_out) {
int innermost_handler = -1;
#ifdef DEBUG
// Assuming that ranges are well nested, we don't need to track the innermost
// offsets. This is just to verify that the table is actually well nested.
int innermost_start = std::numeric_limits<int>::min();
int innermost_end = std::numeric_limits<int>::max();
#endif
for (int i = 0; i < NumberOfRangeEntries(); ++i) {
int start_offset = GetRangeStart(i);
int end_offset = GetRangeEnd(i);
int handler_offset = GetRangeHandler(i);
int handler_data = GetRangeData(i);
CatchPrediction prediction = GetRangePrediction(i);
if (pc_offset >= start_offset && pc_offset < end_offset) {
DCHECK_GE(start_offset, innermost_start);
DCHECK_LT(end_offset, innermost_end);
innermost_handler = handler_offset;
#ifdef DEBUG
innermost_start = start_offset;
innermost_end = end_offset;
#endif
if (data_out) *data_out = handler_data;
if (prediction_out) *prediction_out = prediction;
}
}
return innermost_handler;
}
// TODO(turbofan): Make sure table is sorted and use binary search.
int HandlerTable::LookupReturn(int pc_offset) {
for (int i = 0; i < NumberOfReturnEntries(); ++i) {
int return_offset = GetReturnOffset(i);
if (pc_offset == return_offset) {
return GetReturnHandler(i);
}
}
return -1;
}
#ifdef ENABLE_DISASSEMBLER
void HandlerTable::HandlerTableRangePrint(std::ostream& os) {
os << " from to hdlr (prediction, data)\n";
for (int i = 0; i < NumberOfRangeEntries(); ++i) {
int pc_start = GetRangeStart(i);
int pc_end = GetRangeEnd(i);
int handler_offset = GetRangeHandler(i);
int handler_data = GetRangeData(i);
CatchPrediction prediction = GetRangePrediction(i);
os << " (" << std::setw(4) << pc_start << "," << std::setw(4) << pc_end
<< ") -> " << std::setw(4) << handler_offset
<< " (prediction=" << prediction << ", data=" << handler_data << ")\n";
}
}
void HandlerTable::HandlerTableReturnPrint(std::ostream& os) {
os << " offset handler\n";
for (int i = 0; i < NumberOfReturnEntries(); ++i) {
int pc_offset = GetReturnOffset(i);
int handler_offset = GetReturnHandler(i);
os << std::hex << " " << std::setw(4) << pc_offset << " -> "
<< std::setw(4) << handler_offset << std::dec << "\n";
}
}
#endif // ENABLE_DISASSEMBLER
} // namespace internal
} // namespace v8
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