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handler-table.cc
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277 lines (240 loc) · 9.57 KB
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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 <algorithm>
#include <iomanip>
#include "src/base/iterator.h"
#include "src/codegen/assembler-inl.h"
#include "src/objects/code-inl.h"
#include "src/objects/objects-inl.h"
#if V8_ENABLE_WEBASSEMBLY
#include "src/wasm/wasm-code-manager.h"
#endif // V8_ENABLE_WEBASSEMBLY
namespace v8 {
namespace internal {
HandlerTable::HandlerTable(Tagged<Code> code)
: HandlerTable(code->handler_table_address(), code->handler_table_size(),
kReturnAddressBasedEncoding) {}
#if V8_ENABLE_WEBASSEMBLY
HandlerTable::HandlerTable(const wasm::WasmCode* code)
: HandlerTable(code->handler_table(), code->handler_table_size(),
kReturnAddressBasedEncoding) {}
#endif // V8_ENABLE_WEBASSEMBLY
HandlerTable::HandlerTable(Tagged<BytecodeArray> bytecode_array)
: HandlerTable(bytecode_array->handler_table()) {}
HandlerTable::HandlerTable(Tagged<TrustedByteArray> byte_array)
: HandlerTable(reinterpret_cast<Address>(byte_array->begin()),
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::GetRangeHandlerBitfield(int index) const {
DCHECK_EQ(kRangeBasedEncoding, mode_);
DCHECK_LT(index, NumberOfRangeEntries());
int offset = index * kRangeEntrySize + kRangeHandlerIndex;
return base::Relaxed_Load(
&Memory<int32_t>(raw_encoded_data_ + offset * sizeof(int32_t)));
}
int HandlerTable::GetRangeHandler(int index) const {
return HandlerOffsetField::decode(GetRangeHandlerBitfield(index));
}
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 {
return HandlerPredictionField::decode(GetRangeHandlerBitfield(index));
}
bool HandlerTable::HandlerWasUsed(int index) const {
return HandlerWasUsedField::decode(GetRangeHandlerBitfield(index));
}
void HandlerTable::MarkHandlerUsed(int index) {
DCHECK_EQ(kRangeBasedEncoding, mode_);
DCHECK_LT(index, NumberOfRangeEntries());
int offset = index * kRangeEntrySize + kRangeHandlerIndex;
auto& mem = Memory<int32_t>(raw_encoded_data_ + offset * sizeof(int32_t));
base::Relaxed_Store(&mem, HandlerWasUsedField::update(mem, true));
}
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) |
HandlerWasUsedField::encode(false) |
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(InstructionStream::kMetadataAlignment);
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::LookupHandlerIndexForRange(int pc_offset) const {
int innermost_handler = kNoHandlerFound;
#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);
if (end_offset <= pc_offset) continue;
if (start_offset > pc_offset) break;
DCHECK_GE(start_offset, innermost_start);
DCHECK_LT(end_offset, innermost_end);
innermost_handler = i;
#ifdef DEBUG
innermost_start = start_offset;
innermost_end = end_offset;
#endif
}
return innermost_handler;
}
int HandlerTable::LookupReturn(int pc_offset) {
// We only implement the methods needed by the standard libraries we care
// about. This is not technically a full random access iterator by the spec.
struct Iterator : base::iterator<std::random_access_iterator_tag, int> {
Iterator(HandlerTable* tbl, int idx) : table(tbl), index(idx) {}
value_type operator*() const { return table->GetReturnOffset(index); }
bool operator!=(const Iterator& other) const { return !(*this == other); }
bool operator==(const Iterator& other) const {
return index == other.index;
}
// GLIBCXX_DEBUG checks uses the <= comparator.
bool operator<=(const Iterator& other) { return index <= other.index; }
Iterator& operator++() {
index++;
return *this;
}
Iterator& operator--() {
index--;
return *this;
}
Iterator& operator+=(difference_type offset) {
index += offset;
return *this;
}
difference_type operator-(const Iterator& other) const {
return index - other.index;
}
HandlerTable* table;
int index;
};
Iterator begin{this, 0}, end{this, NumberOfReturnEntries()};
SLOW_DCHECK(std::is_sorted(begin, end)); // Must be sorted.
Iterator result = std::lower_bound(begin, end, pc_offset);
if (result != end && *result == pc_offset) {
return GetReturnHandler(result.index);
}
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