Keep original order of fields in Class.
The fields of a class are ordered alphabetically in the dex
file. Keep the same order in the field arrays so that we can
do binary search lookups by name. Those lookups will be
implemented in a subsequent change in libcore/.
Bug: 18211592
(cherry picked from commit bfa3ed0ad988e1da13626ddbaf6dcae0c58ea79e)
Change-Id: I8f979de62ffe37d1c7d5c721717d2f3501e7c9e6
diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index fb90b91..5afba62 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -185,15 +185,13 @@
}
// Shuffle fields forward, making use of gaps whenever possible.
template<int n>
-static void ShuffleForward(const size_t num_fields, size_t* current_field_idx,
+static void ShuffleForward(size_t* current_field_idx,
MemberOffset* field_offset,
- mirror::ObjectArray<mirror::ArtField>* fields,
std::deque<mirror::ArtField*>* grouped_and_sorted_fields,
FieldGaps* gaps)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
DCHECK(current_field_idx != nullptr);
DCHECK(grouped_and_sorted_fields != nullptr);
- DCHECK(fields != nullptr || (num_fields == 0 && grouped_and_sorted_fields->empty()));
DCHECK(gaps != nullptr);
DCHECK(field_offset != nullptr);
@@ -211,7 +209,6 @@
}
CHECK(type != Primitive::kPrimNot) << PrettyField(field); // should be primitive types
grouped_and_sorted_fields->pop_front();
- fields->Set<false>(*current_field_idx, field);
if (!gaps->empty() && gaps->top().size >= n) {
FieldGap gap = gaps->top();
gaps->pop();
@@ -5231,13 +5228,7 @@
// Initialize field_offset
MemberOffset field_offset(0);
if (is_static) {
- uint32_t base = sizeof(mirror::Class); // Static fields come after the class.
- if (klass->ShouldHaveEmbeddedImtAndVTable()) {
- // Static fields come after the embedded tables.
- base = mirror::Class::ComputeClassSize(true, klass->GetVTableDuringLinking()->GetLength(),
- 0, 0, 0, 0, 0);
- }
- field_offset = MemberOffset(base);
+ field_offset = klass->GetFirstReferenceStaticFieldOffsetDuringLinking();
} else {
mirror::Class* super_class = klass->GetSuperClass();
if (super_class != nullptr) {
@@ -5274,28 +5265,25 @@
if (isPrimitive) {
break; // past last reference, move on to the next phase
}
- if (UNLIKELY(!IsAligned<4>(field_offset.Uint32Value()))) {
+ if (UNLIKELY(!IsAligned<sizeof(mirror::HeapReference<mirror::Object>)>(
+ field_offset.Uint32Value()))) {
MemberOffset old_offset = field_offset;
field_offset = MemberOffset(RoundUp(field_offset.Uint32Value(), 4));
AddFieldGap(old_offset.Uint32Value(), field_offset.Uint32Value(), &gaps);
}
- DCHECK(IsAligned<4>(field_offset.Uint32Value()));
+ DCHECK(IsAligned<sizeof(mirror::HeapReference<mirror::Object>)>(field_offset.Uint32Value()));
grouped_and_sorted_fields.pop_front();
num_reference_fields++;
- fields->Set<false>(current_field, field);
field->SetOffset(field_offset);
- field_offset = MemberOffset(field_offset.Uint32Value() + sizeof(uint32_t));
+ field_offset = MemberOffset(field_offset.Uint32Value() +
+ sizeof(mirror::HeapReference<mirror::Object>));
}
// Gaps are stored as a max heap which means that we must shuffle from largest to smallest
// otherwise we could end up with suboptimal gap fills.
- ShuffleForward<8>(num_fields, ¤t_field, &field_offset,
- fields, &grouped_and_sorted_fields, &gaps);
- ShuffleForward<4>(num_fields, ¤t_field, &field_offset,
- fields, &grouped_and_sorted_fields, &gaps);
- ShuffleForward<2>(num_fields, ¤t_field, &field_offset,
- fields, &grouped_and_sorted_fields, &gaps);
- ShuffleForward<1>(num_fields, ¤t_field, &field_offset,
- fields, &grouped_and_sorted_fields, &gaps);
+ ShuffleForward<8>(¤t_field, &field_offset, &grouped_and_sorted_fields, &gaps);
+ ShuffleForward<4>(¤t_field, &field_offset, &grouped_and_sorted_fields, &gaps);
+ ShuffleForward<2>(¤t_field, &field_offset, &grouped_and_sorted_fields, &gaps);
+ ShuffleForward<1>(¤t_field, &field_offset, &grouped_and_sorted_fields, &gaps);
CHECK(grouped_and_sorted_fields.empty()) << "Missed " << grouped_and_sorted_fields.size() <<
" fields.";
self->EndAssertNoThreadSuspension(old_no_suspend_cause);
@@ -5309,39 +5297,6 @@
--num_reference_fields;
}
- if (kIsDebugBuild) {
- // Make sure that all reference fields appear before
- // non-reference fields, and all double-wide fields are aligned.
- bool seen_non_ref = false;
- for (size_t i = 0; i < num_fields; i++) {
- mirror::ArtField* field = fields->Get(i);
- if ((false)) { // enable to debug field layout
- LOG(INFO) << "LinkFields: " << (is_static ? "static" : "instance")
- << " class=" << PrettyClass(klass.Get())
- << " field=" << PrettyField(field)
- << " offset="
- << field->GetField32(mirror::ArtField::OffsetOffset());
- }
- Primitive::Type type = field->GetTypeAsPrimitiveType();
- bool is_primitive = type != Primitive::kPrimNot;
- if (klass->DescriptorEquals("Ljava/lang/ref/Reference;") &&
- strcmp("referent", field->GetName()) == 0) {
- is_primitive = true; // We lied above, so we have to expect a lie here.
- }
- if (is_primitive) {
- if (!seen_non_ref) {
- seen_non_ref = true;
- DCHECK_EQ(num_reference_fields, i) << PrettyField(field);
- }
- } else {
- DCHECK(!seen_non_ref) << PrettyField(field);
- }
- }
- if (!seen_non_ref) {
- DCHECK_EQ(num_fields, num_reference_fields) << PrettyClass(klass.Get());
- }
- }
-
size_t size = field_offset.Uint32Value();
// Update klass
if (is_static) {
@@ -5360,11 +5315,59 @@
klass->SetObjectSize(size);
}
}
+
+ if (kIsDebugBuild) {
+ // Make sure that the fields array is ordered by name but all reference
+ // offsets are at the beginning as far as alignment allows.
+ MemberOffset start_ref_offset = is_static
+ ? klass->GetFirstReferenceStaticFieldOffsetDuringLinking()
+ : klass->GetFirstReferenceInstanceFieldOffset();
+ MemberOffset end_ref_offset(start_ref_offset.Uint32Value() +
+ num_reference_fields *
+ sizeof(mirror::HeapReference<mirror::Object>));
+ MemberOffset current_ref_offset = start_ref_offset;
+ for (size_t i = 0; i < num_fields; i++) {
+ mirror::ArtField* field = fields->Get(i);
+ if ((false)) { // enable to debug field layout
+ LOG(INFO) << "LinkFields: " << (is_static ? "static" : "instance")
+ << " class=" << PrettyClass(klass.Get())
+ << " field=" << PrettyField(field)
+ << " offset="
+ << field->GetField32(mirror::ArtField::OffsetOffset());
+ }
+ if (i != 0) {
+ mirror::ArtField* prev_field = fields->Get(i - 1u);
+ CHECK_LT(strcmp(prev_field->GetName(), field->GetName()), 0);
+ }
+ Primitive::Type type = field->GetTypeAsPrimitiveType();
+ bool is_primitive = type != Primitive::kPrimNot;
+ if (klass->DescriptorEquals("Ljava/lang/ref/Reference;") &&
+ strcmp("referent", field->GetName()) == 0) {
+ is_primitive = true; // We lied above, so we have to expect a lie here.
+ }
+ MemberOffset offset = field->GetOffsetDuringLinking();
+ if (is_primitive) {
+ if (offset.Uint32Value() < end_ref_offset.Uint32Value()) {
+ // Shuffled before references.
+ size_t type_size = Primitive::ComponentSize(type);
+ CHECK_LT(type_size, sizeof(mirror::HeapReference<mirror::Object>));
+ CHECK_LT(offset.Uint32Value(), start_ref_offset.Uint32Value());
+ CHECK_LE(offset.Uint32Value() + type_size, start_ref_offset.Uint32Value());
+ CHECK(!IsAligned<sizeof(mirror::HeapReference<mirror::Object>)>(offset.Uint32Value()));
+ }
+ } else {
+ CHECK_EQ(current_ref_offset.Uint32Value(), offset.Uint32Value());
+ current_ref_offset = MemberOffset(current_ref_offset.Uint32Value() +
+ sizeof(mirror::HeapReference<mirror::Object>));
+ }
+ }
+ CHECK_EQ(current_ref_offset.Uint32Value(), end_ref_offset.Uint32Value());
+ }
+
return true;
}
-// Set the bitmap of reference offsets, refOffsets, from the ifields
-// list.
+// Set the bitmap of reference instance field offsets.
void ClassLinker::CreateReferenceInstanceOffsets(Handle<mirror::Class> klass) {
uint32_t reference_offsets = 0;
mirror::Class* super_class = klass->GetSuperClass();
@@ -5374,23 +5377,18 @@
// Compute reference offsets unless our superclass overflowed.
if (reference_offsets != mirror::Class::kClassWalkSuper) {
size_t num_reference_fields = klass->NumReferenceInstanceFieldsDuringLinking();
- mirror::ObjectArray<mirror::ArtField>* fields = klass->GetIFields();
- // All of the fields that contain object references are guaranteed
- // to be at the beginning of the fields list.
- for (size_t i = 0; i < num_reference_fields; ++i) {
- // Note that byte_offset is the offset from the beginning of
- // object, not the offset into instance data
- mirror::ArtField* field = fields->Get(i);
- MemberOffset byte_offset = field->GetOffsetDuringLinking();
- uint32_t displaced_bitmap_position =
- (byte_offset.Uint32Value() - mirror::kObjectHeaderSize) /
+ if (num_reference_fields != 0u) {
+ // All of the fields that contain object references are guaranteed be grouped in memory
+ // starting at an appropriately aligned address after super class object data.
+ uint32_t start_offset = RoundUp(super_class->GetObjectSize(),
+ sizeof(mirror::HeapReference<mirror::Object>));
+ uint32_t start_bit = (start_offset - mirror::kObjectHeaderSize) /
sizeof(mirror::HeapReference<mirror::Object>);
- if (displaced_bitmap_position >= 32) {
- // Can't encode offset so fall back on slow-path.
+ if (start_bit + num_reference_fields > 32) {
reference_offsets = mirror::Class::kClassWalkSuper;
- break;
} else {
- reference_offsets |= (1 << displaced_bitmap_position);
+ reference_offsets |= (0xffffffffu << start_bit) &
+ (0xffffffffu >> (32 - (start_bit + num_reference_fields)));
}
}
}