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[vm] Add more checks when packing nullability during serialization.

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Also only shift as many bits as needed to fit nullability into the
serialized value in case additional type states or flags are added in
the future.

Change-Id: Ic821070971f77040e05d5aeb53a5a0ed85cc8d09
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/158180
Commit-Queue: Tess Strickland <sstrickl@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
This commit is contained in:
Tess Strickland
2020-08-12 14:56:44 +00:00
committed by commit-bot@chromium.org
parent d5def62c9c
commit 41458ba4b1
3 changed files with 56 additions and 51 deletions
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runtime/vm/clustered_snapshot.cc
+45 -40
View File
@@ -3366,6 +3366,10 @@ class LibraryPrefixDeserializationCluster : public DeserializationCluster {
}
};
// Used to pack nullability into other serialized values.
static constexpr intptr_t kNullabilityBitSize = 2;
static constexpr intptr_t kNullabilityBitMask = (1 << kNullabilityBitSize) - 1;
#if !defined(DART_PRECOMPILED_RUNTIME)
class TypeSerializationCluster : public SerializationCluster {
public:
@@ -3412,31 +3416,31 @@ class TypeSerializationCluster : public SerializationCluster {
void WriteFill(Serializer* s) {
intptr_t count = canonical_objects_.length();
for (intptr_t i = 0; i < count; i++) {
TypePtr type = canonical_objects_[i];
AutoTraceObject(type);
WriteFromTo(type);
s->WriteTokenPosition(type->ptr()->token_pos_);
const uint8_t combined =
(type->ptr()->type_state_ << 4) | type->ptr()->nullability_;
ASSERT(type->ptr()->type_state_ == (combined >> 4));
ASSERT(type->ptr()->nullability_ == (combined & 0xf));
s->Write<uint8_t>(combined);
WriteType(s, canonical_objects_[i]);
}
count = objects_.length();
for (intptr_t i = 0; i < count; i++) {
TypePtr type = objects_[i];
AutoTraceObject(type);
WriteFromTo(type);
s->WriteTokenPosition(type->ptr()->token_pos_);
const uint8_t combined =
(type->ptr()->type_state_ << 4) | type->ptr()->nullability_;
ASSERT(type->ptr()->type_state_ == (combined >> 4));
ASSERT(type->ptr()->nullability_ == (combined & 0xf));
s->Write<uint8_t>(combined);
WriteType(s, objects_[i]);
}
}
private:
void WriteType(Serializer* s, TypePtr type) {
AutoTraceObject(type);
WriteFromTo(type);
s->WriteTokenPosition(type->ptr()->token_pos_);
ASSERT(type->ptr()->type_state_ < (1 << TypeLayout::kTypeStateBitSize));
ASSERT(type->ptr()->nullability_ < (1 << kNullabilityBitSize));
static_assert(TypeLayout::kTypeStateBitSize + kNullabilityBitSize <=
kBitsPerByte * sizeof(uint8_t),
"Cannot pack type_state_ and nullability_ into a uint8_t");
const uint8_t combined = (type->ptr()->type_state_ << kNullabilityBitSize) |
type->ptr()->nullability_;
ASSERT_EQUAL(type->ptr()->type_state_, combined >> kNullabilityBitSize);
ASSERT_EQUAL(type->ptr()->nullability_, combined & kNullabilityBitMask);
s->Write<uint8_t>(combined);
}
GrowableArray<TypePtr> canonical_objects_;
GrowableArray<TypePtr> objects_;
};
@@ -3468,26 +3472,12 @@ class TypeDeserializationCluster : public DeserializationCluster {
for (intptr_t id = canonical_start_index_; id < canonical_stop_index_;
id++) {
TypePtr type = static_cast<TypePtr>(d->Ref(id));
bool is_canonical = true;
Deserializer::InitializeHeader(type, kTypeCid, Type::InstanceSize(),
is_canonical);
ReadFromTo(type);
type->ptr()->token_pos_ = d->ReadTokenPosition();
const uint8_t combined = d->Read<uint8_t>();
type->ptr()->type_state_ = combined >> 4;
type->ptr()->nullability_ = combined & 0xf;
ReadType(d, type, /*is_canonical=*/true);
}
for (intptr_t id = start_index_; id < stop_index_; id++) {
TypePtr type = static_cast<TypePtr>(d->Ref(id));
bool is_canonical = false;
Deserializer::InitializeHeader(type, kTypeCid, Type::InstanceSize(),
is_canonical);
ReadFromTo(type);
type->ptr()->token_pos_ = d->ReadTokenPosition();
const uint8_t combined = d->Read<uint8_t>();
type->ptr()->type_state_ = combined >> 4;
type->ptr()->nullability_ = combined & 0xf;
ReadType(d, type, /*is_canonical=*/false);
}
}
@@ -3523,6 +3513,16 @@ class TypeDeserializationCluster : public DeserializationCluster {
}
private:
void ReadType(Deserializer* d, TypePtr type, bool is_canonical) {
Deserializer::InitializeHeader(type, kTypeCid, Type::InstanceSize(),
is_canonical);
ReadFromTo(type);
type->ptr()->token_pos_ = d->ReadTokenPosition();
const uint8_t combined = d->Read<uint8_t>();
type->ptr()->type_state_ = combined >> kNullabilityBitSize;
type->ptr()->nullability_ = combined & kNullabilityBitMask;
}
intptr_t canonical_start_index_;
intptr_t canonical_stop_index_;
};
@@ -3659,10 +3659,15 @@ class TypeParameterSerializationCluster : public SerializationCluster {
s->Write<int32_t>(type->ptr()->parameterized_class_id_);
s->WriteTokenPosition(type->ptr()->token_pos_);
s->Write<int16_t>(type->ptr()->index_);
const uint8_t combined =
(type->ptr()->flags_ << 4) | type->ptr()->nullability_;
ASSERT(type->ptr()->flags_ == (combined >> 4));
ASSERT(type->ptr()->nullability_ == (combined & 0xf));
ASSERT(type->ptr()->flags_ < (1 << TypeParameterLayout::kFlagsBitSize));
ASSERT(type->ptr()->nullability_ < (1 << kNullabilityBitSize));
static_assert(TypeParameterLayout::kFlagsBitSize + kNullabilityBitSize <=
kBitsPerByte * sizeof(uint8_t),
"Cannot pack flags_ and nullability_ into a uint8_t");
const uint8_t combined = (type->ptr()->flags_ << kNullabilityBitSize) |
type->ptr()->nullability_;
ASSERT_EQUAL(type->ptr()->flags_, combined >> kNullabilityBitSize);
ASSERT_EQUAL(type->ptr()->nullability_, combined & kNullabilityBitMask);
s->Write<uint8_t>(combined);
}
@@ -3752,8 +3757,8 @@ class TypeParameterDeserializationCluster : public DeserializationCluster {
type->ptr()->token_pos_ = d->ReadTokenPosition();
type->ptr()->index_ = d->Read<int16_t>();
const uint8_t combined = d->Read<uint8_t>();
type->ptr()->flags_ = combined >> 4;
type->ptr()->nullability_ = combined & 0xf;
type->ptr()->flags_ = combined >> kNullabilityBitSize;
type->ptr()->nullability_ = combined & kNullabilityBitMask;
}
intptr_t canonical_start_index_;
runtime/vm/object.h
+1
View File
@@ -900,6 +900,7 @@ enum class Nullability : int8_t {
kNullable = 0,
kNonNullable = 1,
kLegacy = 2,
// Adjust kNullabilityBitSize in clustered_snapshot.cc if adding new values.
};
// Equality kind between types.
runtime/vm/raw_object.h
+10 -11
View File
@@ -2190,9 +2190,12 @@ class AbstractTypeLayout : public InstanceLayout {
kBeingFinalized, // In the process of being finalized.
kFinalizedInstantiated, // Instantiated type ready for use.
kFinalizedUninstantiated, // Uninstantiated type ready for use.
// Adjust kTypeStateBitSize if more are added.
};
protected:
static constexpr intptr_t kTypeStateBitSize = 2;
uword type_test_stub_entry_point_; // Accessed from generated code.
CodePtr type_test_stub_; // Must be the last field, since subclasses use it
// in their VISIT_FROM.
@@ -2237,17 +2240,6 @@ class TypeRefLayout : public AbstractTypeLayout {
};
class TypeParameterLayout : public AbstractTypeLayout {
public:
enum {
kFinalizedBit = 0,
kGenericCovariantImplBit,
kDeclarationBit,
};
class FinalizedBit : public BitField<uint8_t, bool, kFinalizedBit, 1> {};
class GenericCovariantImplBit
: public BitField<uint8_t, bool, kGenericCovariantImplBit, 1> {};
class DeclarationBit : public BitField<uint8_t, bool, kDeclarationBit, 1> {};
private:
RAW_HEAP_OBJECT_IMPLEMENTATION(TypeParameter);
@@ -2263,6 +2255,13 @@ class TypeParameterLayout : public AbstractTypeLayout {
uint8_t flags_;
int8_t nullability_;
using FinalizedBit = BitField<decltype(flags_), bool, 0, 1>;
using GenericCovariantImplBit =
BitField<decltype(flags_), bool, FinalizedBit::kNextBit, 1>;
using DeclarationBit =
BitField<decltype(flags_), bool, GenericCovariantImplBit::kNextBit, 1>;
static constexpr intptr_t kFlagsBitSize = DeclarationBit::kNextBit;
ObjectPtr* to_snapshot(Snapshot::Kind kind) { return to(); }
friend class CidRewriteVisitor;