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[codegen] Move SourcePositionTableBuilder to Zone

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The SourcePositionTableBuilder unconditionally allocates heap memory for
every Liftoff compilation. This shows up with 1-2% of compilation time
in profiles. Hence move the vector contained in the
SourcePositionTableBuilder into the compilation zone. Such a zone
already exists for both Liftoff and TurboFan, so we can easily save
allocations this way.

R=thibaudm@chromium.org

Bug: v8:10576
Change-Id: Ia83d05cc8c36c775ebff6ec2064e9c3f8cc4d384
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2224221
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68112}
This commit is contained in:
Clemens Backes 2020-06-02 12:50:42 +02:00 committed by Commit Bot
parent f62fc2e1a8
commit 447ad5ccbe
7 changed files with 50 additions and 40 deletions
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18
src/codegen/source-position-table.cc
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@ -49,10 +49,10 @@ void SubtractFromEntry(PositionTableEntry* value,
// Helper: Encode an integer.
template <typename T>
void EncodeInt(std::vector<byte>* bytes, T value) {
void EncodeInt(ZoneVector<byte>* bytes, T value) {
using unsigned_type = typename std::make_unsigned<T>::type;
// Zig-zag encoding.
static const int kShift = sizeof(T) * kBitsPerByte - 1;
static constexpr int kShift = sizeof(T) * kBitsPerByte - 1;
value = ((static_cast<unsigned_type>(value) << 1) ^ (value >> kShift));
DCHECK_GE(value, 0);
unsigned_type encoded = static_cast<unsigned_type>(value);
@ -67,7 +67,7 @@ void EncodeInt(std::vector<byte>* bytes, T value) {
}
// Encode a PositionTableEntry.
void EncodeEntry(std::vector<byte>* bytes, const PositionTableEntry& entry) {
void EncodeEntry(ZoneVector<byte>* bytes, const PositionTableEntry& entry) {
// We only accept ascending code offsets.
DCHECK_GE(entry.code_offset, 0);
// Since code_offset is not negative, we use sign to encode is_statement.
@ -115,7 +115,7 @@ Vector<const byte> VectorFromByteArray(ByteArray byte_array) {
}
#ifdef ENABLE_SLOW_DCHECKS
void CheckTableEquals(const std::vector<PositionTableEntry>& raw_entries,
void CheckTableEquals(const ZoneVector<PositionTableEntry>& raw_entries,
SourcePositionTableIterator* encoded) {
// Brute force testing: Record all positions and decode
// the entire table to verify they are identical.
@ -133,8 +133,14 @@ void CheckTableEquals(const std::vector<PositionTableEntry>& raw_entries,
} // namespace
SourcePositionTableBuilder::SourcePositionTableBuilder(
SourcePositionTableBuilder::RecordingMode mode)
: mode_(mode), previous_() {}
Zone* zone, SourcePositionTableBuilder::RecordingMode mode)
: mode_(mode),
bytes_(zone),
#ifdef ENABLE_SLOW_DCHECKS
raw_entries_(zone),
#endif
previous_() {
}
void SourcePositionTableBuilder::AddPosition(size_t code_offset,
SourcePosition source_position,

6
src/codegen/source-position-table.h
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@ -49,7 +49,7 @@ class V8_EXPORT_PRIVATE SourcePositionTableBuilder {
};
explicit SourcePositionTableBuilder(
RecordingMode mode = RECORD_SOURCE_POSITIONS);
Zone* zone, RecordingMode mode = RECORD_SOURCE_POSITIONS);
void AddPosition(size_t code_offset, SourcePosition source_position,
bool is_statement);
@ -66,9 +66,9 @@ class V8_EXPORT_PRIVATE SourcePositionTableBuilder {
void AddEntry(const PositionTableEntry& entry);
RecordingMode mode_;
std::vector<byte> bytes_;
ZoneVector<byte> bytes_;
#ifdef ENABLE_SLOW_DCHECKS
std::vector<PositionTableEntry> raw_entries_;
ZoneVector<PositionTableEntry> raw_entries_;
#endif
PositionTableEntry previous_; // Previously written entry, to compute delta.
};

23
src/compiler/backend/code-generator.cc
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@ -55,19 +55,20 @@ CodeGenerator::CodeGenerator(
frame_access_state_(nullptr),
linkage_(linkage),
instructions_(instructions),
unwinding_info_writer_(zone()),
unwinding_info_writer_(codegen_zone),
info_(info),
labels_(zone()->NewArray<Label>(instructions->InstructionBlockCount())),
labels_(
codegen_zone->NewArray<Label>(instructions->InstructionBlockCount())),
current_block_(RpoNumber::Invalid()),
start_source_position_(start_source_position),
current_source_position_(SourcePosition::Unknown()),
tasm_(isolate, options, CodeObjectRequired::kNo, std::move(buffer)),
resolver_(this),
safepoints_(zone()),
handlers_(zone()),
deoptimization_exits_(zone()),
deoptimization_literals_(zone()),
translations_(zone()),
safepoints_(codegen_zone),
handlers_(codegen_zone),
deoptimization_exits_(codegen_zone),
deoptimization_literals_(codegen_zone),
translations_(codegen_zone),
max_unoptimized_frame_height_(max_unoptimized_frame_height),
max_pushed_argument_count_(max_pushed_argument_count),
caller_registers_saved_(false),
@ -77,12 +78,12 @@ CodeGenerator::CodeGenerator(
osr_pc_offset_(-1),
optimized_out_literal_id_(-1),
source_position_table_builder_(
SourcePositionTableBuilder::RECORD_SOURCE_POSITIONS),
protected_instructions_(zone()),
codegen_zone, SourcePositionTableBuilder::RECORD_SOURCE_POSITIONS),
protected_instructions_(codegen_zone),
result_(kSuccess),
poisoning_level_(poisoning_level),
block_starts_(zone()),
instr_starts_(zone()) {
block_starts_(codegen_zone),
instr_starts_(codegen_zone) {
for (int i = 0; i < instructions->InstructionBlockCount(); ++i) {
new (&labels_[i]) Label;
}

3
src/debug/liveedit.cc
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@ -1003,7 +1003,8 @@ bool CanRestartFrame(
void TranslateSourcePositionTable(Isolate* isolate, Handle<BytecodeArray> code,
const std::vector<SourceChangeRange>& diffs) {
SourcePositionTableBuilder builder;
Zone zone(isolate->allocator(), ZONE_NAME);
SourcePositionTableBuilder builder(&zone);
Handle<ByteArray> source_position_table(code->SourcePositionTable(), isolate);
for (SourcePositionTableIterator iterator(*source_position_table);

2
src/interpreter/bytecode-array-writer.cc
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@ -27,7 +27,7 @@ BytecodeArrayWriter::BytecodeArrayWriter(
SourcePositionTableBuilder::RecordingMode source_position_mode)
: bytecodes_(zone),
unbound_jumps_(0),
source_position_table_builder_(source_position_mode),
source_position_table_builder_(zone, source_position_mode),
constant_array_builder_(constant_array_builder),
last_bytecode_(Bytecode::kIllegal),
last_bytecode_offset_(0),

1
src/wasm/baseline/liftoff-compiler.cc
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@ -339,6 +339,7 @@ class LiftoffCompiler {
debug_sidetable_builder_(debug_sidetable_builder),
for_debugging_(for_debugging),
out_of_line_code_(compilation_zone),
source_position_table_builder_(compilation_zone),
protected_instructions_(compilation_zone),
compilation_zone_(compilation_zone),
safepoint_table_builder_(compilation_zone_),

37
test/unittests/codegen/source-position-table-unittest.cc
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@ -14,12 +14,18 @@ namespace interpreter {
class SourcePositionTableTest : public TestWithIsolate {
public:
SourcePositionTableTest() = default;
SourcePositionTableTest() : zone_(isolate()->allocator(), ZONE_NAME) {}
~SourcePositionTableTest() override = default;
SourcePosition toPos(int offset) {
return SourcePosition(offset, offset % 10 - 1);
}
SourcePositionTableBuilder* builder() { return &builder_; }
private:
Zone zone_;
SourcePositionTableBuilder builder_{&zone_};
};
// Some random offsets, mostly at 'suspicious' bit boundaries.
@ -28,48 +34,43 @@ static int offsets[] = {0, 1, 2, 3, 4, 30, 31, 32,
129, 250, 1000, 9999, 12000, 31415926};
TEST_F(SourcePositionTableTest, EncodeStatement) {
SourcePositionTableBuilder builder;
for (size_t i = 0; i < arraysize(offsets); i++) {
builder.AddPosition(offsets[i], toPos(offsets[i]), true);
builder()->AddPosition(offsets[i], toPos(offsets[i]), true);
}
// To test correctness, we rely on the assertions in ToSourcePositionTable().
// (Also below.)
CHECK(!builder.ToSourcePositionTable(isolate()).is_null());
CHECK(!builder()->ToSourcePositionTable(isolate()).is_null());
}
TEST_F(SourcePositionTableTest, EncodeStatementDuplicates) {
SourcePositionTableBuilder builder;
for (size_t i = 0; i < arraysize(offsets); i++) {
builder.AddPosition(offsets[i], toPos(offsets[i]), true);
builder.AddPosition(offsets[i], toPos(offsets[i] + 1), true);
builder()->AddPosition(offsets[i], toPos(offsets[i]), true);
builder()->AddPosition(offsets[i], toPos(offsets[i] + 1), true);
}
// To test correctness, we rely on the assertions in ToSourcePositionTable().
// (Also below.)
CHECK(!builder.ToSourcePositionTable(isolate()).is_null());
CHECK(!builder()->ToSourcePositionTable(isolate()).is_null());
}
TEST_F(SourcePositionTableTest, EncodeExpression) {
SourcePositionTableBuilder builder;
for (size_t i = 0; i < arraysize(offsets); i++) {
builder.AddPosition(offsets[i], toPos(offsets[i]), false);
builder()->AddPosition(offsets[i], toPos(offsets[i]), false);
}
CHECK(!builder.ToSourcePositionTable(isolate()).is_null());
CHECK(!builder()->ToSourcePositionTable(isolate()).is_null());
}
TEST_F(SourcePositionTableTest, EncodeAscending) {
SourcePositionTableBuilder builder;
int code_offset = 0;
int source_position = 0;
for (size_t i = 0; i < arraysize(offsets); i++) {
code_offset += offsets[i];
source_position += offsets[i];
if (i % 2) {
builder.AddPosition(code_offset, toPos(source_position), true);
builder()->AddPosition(code_offset, toPos(source_position), true);
} else {
builder.AddPosition(code_offset, toPos(source_position), false);
builder()->AddPosition(code_offset, toPos(source_position), false);
}
}
@ -78,13 +79,13 @@ TEST_F(SourcePositionTableTest, EncodeAscending) {
code_offset += offsets[i];
source_position -= offsets[i];
if (i % 2) {
builder.AddPosition(code_offset, toPos(source_position), true);
builder()->AddPosition(code_offset, toPos(source_position), true);
} else {
builder.AddPosition(code_offset, toPos(source_position), false);
builder()->AddPosition(code_offset, toPos(source_position), false);
}
}
CHECK(!builder.ToSourcePositionTable(isolate()).is_null());
CHECK(!builder()->ToSourcePositionTable(isolate()).is_null());
}
} // namespace interpreter