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Unified Diff: src/interpreter/source-position-table.cc

Issue 2095893002: Use source position table for unoptimized code. (Closed) Base URL: https://chromium.googlesource.com/v8/v8.git@master
Patch Set: fix gc mole Created 4 years, 6 months ago
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Index: src/interpreter/source-position-table.cc
diff --git a/src/interpreter/source-position-table.cc b/src/interpreter/source-position-table.cc
deleted file mode 100644
index 579c6c48948237ad7683106891ea56c07885d50a..0000000000000000000000000000000000000000
--- a/src/interpreter/source-position-table.cc
+++ /dev/null
@@ -1,178 +0,0 @@
-// Copyright 2016 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/interpreter/source-position-table.h"
-
-#include "src/objects-inl.h"
-#include "src/objects.h"
-
-namespace v8 {
-namespace internal {
-namespace interpreter {
-
-// We'll use a simple encoding scheme to record the source positions.
-// Conceptually, each position consists of:
-// - bytecode_offset: An integer index into the BytecodeArray
-// - source_position: An integer index into the source string.
-// - position type: Each position is either a statement or an expression.
-//
-// The basic idea for the encoding is to use a variable-length integer coding,
-// where each byte contains 7 bits of payload data, and 1 'more' bit that
-// determines whether additional bytes follow. Additionally:
-// - we record the difference from the previous position,
-// - we just stuff one bit for the type into the bytecode offset,
-// - we write least-significant bits first,
-// - we use zig-zag encoding to encode both positive and negative numbers.
-
-namespace {
-
-// Each byte is encoded as MoreBit | ValueBits.
-class MoreBit : public BitField8<bool, 7, 1> {};
-class ValueBits : public BitField8<unsigned, 0, 7> {};
-
-// Helper: Add the offsets from 'other' to 'value'. Also set is_statement.
-void AddAndSetEntry(PositionTableEntry& value,
- const PositionTableEntry& other) {
- value.bytecode_offset += other.bytecode_offset;
- value.source_position += other.source_position;
- value.is_statement = other.is_statement;
-}
-
-// Helper: Substract the offsets from 'other' from 'value'.
-void SubtractFromEntry(PositionTableEntry& value,
- const PositionTableEntry& other) {
- value.bytecode_offset -= other.bytecode_offset;
- value.source_position -= other.source_position;
-}
-
-// Helper: Encode an integer.
-void EncodeInt(ZoneVector<byte>& bytes, int value) {
- // Zig-zag encoding.
- static const int kShift = kIntSize * kBitsPerByte - 1;
- value = ((value << 1) ^ (value >> kShift));
- DCHECK_GE(value, 0);
- unsigned int encoded = static_cast<unsigned int>(value);
- bool more;
- do {
- more = encoded > ValueBits::kMax;
- bytes.push_back(MoreBit::encode(more) |
- ValueBits::encode(encoded & ValueBits::kMask));
- encoded >>= ValueBits::kSize;
- } while (more);
-}
-
-// Encode a PositionTableEntry.
-void EncodeEntry(ZoneVector<byte>& bytes, const PositionTableEntry& entry) {
- // We only accept ascending bytecode offsets.
- DCHECK(entry.bytecode_offset >= 0);
- // Since bytecode_offset is not negative, we use sign to encode is_statement.
- EncodeInt(bytes, entry.is_statement ? entry.bytecode_offset
- : -entry.bytecode_offset - 1);
- EncodeInt(bytes, entry.source_position);
-}
-
-// Helper: Decode an integer.
-void DecodeInt(ByteArray* bytes, int* index, int* v) {
- byte current;
- int shift = 0;
- int decoded = 0;
- bool more;
- do {
- current = bytes->get((*index)++);
- decoded |= ValueBits::decode(current) << shift;
- more = MoreBit::decode(current);
- shift += ValueBits::kSize;
- } while (more);
- DCHECK_GE(decoded, 0);
- decoded = (decoded >> 1) ^ (-(decoded & 1));
- *v = decoded;
-}
-
-void DecodeEntry(ByteArray* bytes, int* index, PositionTableEntry* entry) {
- int tmp;
- DecodeInt(bytes, index, &tmp);
- if (tmp >= 0) {
- entry->is_statement = true;
- entry->bytecode_offset = tmp;
- } else {
- entry->is_statement = false;
- entry->bytecode_offset = -(tmp + 1);
- }
- DecodeInt(bytes, index, &entry->source_position);
-}
-
-} // namespace
-
-void SourcePositionTableBuilder::AddPosition(size_t bytecode_offset,
- int source_position,
- bool is_statement) {
- int offset = static_cast<int>(bytecode_offset);
- AddEntry({offset, source_position, is_statement});
-}
-
-void SourcePositionTableBuilder::AddEntry(const PositionTableEntry& entry) {
- PositionTableEntry tmp(entry);
- SubtractFromEntry(tmp, previous_);
- EncodeEntry(bytes_, tmp);
- previous_ = entry;
-
- if (entry.is_statement) {
- LOG_CODE_EVENT(isolate_, CodeLinePosInfoAddStatementPositionEvent(
- jit_handler_data_, entry.bytecode_offset,
- entry.source_position));
- }
- LOG_CODE_EVENT(isolate_, CodeLinePosInfoAddPositionEvent(
- jit_handler_data_, entry.bytecode_offset,
- entry.source_position));
-
-#ifdef ENABLE_SLOW_DCHECKS
- raw_entries_.push_back(entry);
-#endif
-}
-
-Handle<ByteArray> SourcePositionTableBuilder::ToSourcePositionTable() {
- if (bytes_.empty()) return isolate_->factory()->empty_byte_array();
-
- Handle<ByteArray> table = isolate_->factory()->NewByteArray(
- static_cast<int>(bytes_.size()), TENURED);
-
- MemCopy(table->GetDataStartAddress(), &*bytes_.begin(), bytes_.size());
-
-#ifdef ENABLE_SLOW_DCHECKS
- // Brute force testing: Record all positions and decode
- // the entire table to verify they are identical.
- auto raw = raw_entries_.begin();
- for (SourcePositionTableIterator encoded(*table); !encoded.done();
- encoded.Advance(), raw++) {
- DCHECK(raw != raw_entries_.end());
- DCHECK_EQ(encoded.bytecode_offset(), raw->bytecode_offset);
- DCHECK_EQ(encoded.source_position(), raw->source_position);
- DCHECK_EQ(encoded.is_statement(), raw->is_statement);
- }
- DCHECK(raw == raw_entries_.end());
-#endif
-
- return table;
-}
-
-SourcePositionTableIterator::SourcePositionTableIterator(ByteArray* byte_array)
- : table_(byte_array), index_(0), current_() {
- Advance();
-}
-
-void SourcePositionTableIterator::Advance() {
- DCHECK(!done());
- DCHECK(index_ >= 0 && index_ <= table_->length());
- if (index_ == table_->length()) {
- index_ = kDone;
- } else {
- PositionTableEntry tmp;
- DecodeEntry(table_, &index_, &tmp);
- AddAndSetEntry(current_, tmp);
- }
-}
-
-} // namespace interpreter
-} // namespace internal
-} // namespace v8
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