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[snapshot] Refactoring: isolate cases where Object* is not a valid Object*.

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BUG=v8:7308

Change-Id: Ib15097beb7c7e4a91df0e6e148f8ce41e5bfd074
Reviewed-on: https://chromium-review.googlesource.com/966521
Commit-Queue: Marja Hölttä <marja@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52011}
This commit is contained in:
Marja Hölttä 2018-03-19 10:27:54 +01:00 committed by Commit Bot
parent 21dad34f93
commit 155e8e9abc
2 changed files with 47 additions and 14 deletions
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52
src/snapshot/deserializer.cc
View File

@ -446,12 +446,6 @@ bool Deserializer<AllocatorT>::ReadData(Object** current, Object** limit,
SINGLE_CASE(kPartialSnapshotCache, kPlain, kStartOfObject, 0)
SINGLE_CASE(kPartialSnapshotCache, kFromCode, kStartOfObject, 0)
SINGLE_CASE(kPartialSnapshotCache, kFromCode, kInnerPointer, 0)
// Find an external reference and write a pointer to it to the current
// object.
SINGLE_CASE(kExternalReference, kPlain, kStartOfObject, 0)
// Find an external reference and write a pointer to it in the current
// code object.
SINGLE_CASE(kExternalReference, kFromCode, kStartOfObject, 0)
// Find an object in the attached references and write a pointer to it to
// the current object.
SINGLE_CASE(kAttachedReference, kPlain, kStartOfObject, 0)
@ -473,6 +467,21 @@ bool Deserializer<AllocatorT>::ReadData(Object** current, Object** limit,
break;
}
// Find an external reference and write a pointer to it to the current
// object.
case kExternalReference + kPlain + kStartOfObject:
current = reinterpret_cast<Object**>(ReadExternalReferenceCase(
kPlain, isolate, reinterpret_cast<void**>(current),
current_object_address));
break;
// Find an external reference and write a pointer to it in the current
// code object.
case kExternalReference + kFromCode + kStartOfObject:
current = reinterpret_cast<Object**>(ReadExternalReferenceCase(
kFromCode, isolate, reinterpret_cast<void**>(current),
current_object_address));
break;
case kInternalReferenceEncoded:
case kInternalReference: {
// Internal reference address is not encoded via skip, but by offset
@ -708,6 +717,30 @@ int FixupJSConstructStub(Isolate* isolate, int builtin_id) {
} // namespace
template <class AllocatorT>
void** Deserializer<AllocatorT>::ReadExternalReferenceCase(
HowToCode how, Isolate* isolate, void** current,
Address current_object_address) {
int skip = source_.GetInt();
current = reinterpret_cast<void**>(reinterpret_cast<Address>(current) + skip);
uint32_t reference_id = static_cast<uint32_t>(source_.GetInt());
Address address = external_reference_table_->address(reference_id);
if (how == kFromCode) {
Address location_of_branch_data = reinterpret_cast<Address>(current);
Assembler::deserialization_set_special_target_at(
location_of_branch_data,
Code::cast(HeapObject::FromAddress(current_object_address)), address);
location_of_branch_data += Assembler::kSpecialTargetSize;
current = reinterpret_cast<void**>(location_of_branch_data);
} else {
void* new_current = reinterpret_cast<void**>(address);
UnalignedCopy(current, &new_current);
++current;
}
return current;
}
template <class AllocatorT>
template <int where, int how, int within, int space_number_if_any>
Object** Deserializer<AllocatorT>::ReadDataCase(Isolate* isolate,
@ -745,13 +778,6 @@ Object** Deserializer<AllocatorT>::ReadDataCase(Isolate* isolate,
int cache_index = source_.GetInt();
new_object = isolate->partial_snapshot_cache()->at(cache_index);
emit_write_barrier = isolate->heap()->InNewSpace(new_object);
} else if (where == kExternalReference) {
int skip = source_.GetInt();
current =
reinterpret_cast<Object**>(reinterpret_cast<Address>(current) + skip);
uint32_t reference_id = static_cast<uint32_t>(source_.GetInt());
Address address = external_reference_table_->address(reference_id);
new_object = reinterpret_cast<Object*>(address);
} else if (where == kAttachedReference) {
int index = source_.GetInt();
new_object = *attached_objects_[index];

9
src/snapshot/deserializer.h
View File

@ -101,7 +101,8 @@ class Deserializer : public SerializerDeserializer {
void Synchronize(VisitorSynchronization::SyncTag tag) override;
void UnalignedCopy(Object** dest, Object** src) {
template <typename T>
void UnalignedCopy(T** dest, T** src) {
memcpy(dest, src, sizeof(*src));
}
@ -120,6 +121,12 @@ class Deserializer : public SerializerDeserializer {
Address current_object_address, byte data,
bool write_barrier_needed);
// A helper function for ReadData for reading external references.
// Returns the new value of {current}.
inline void** ReadExternalReferenceCase(HowToCode how, Isolate* isolate,
void** current,
Address current_object_address);
void ReadObject(int space_number, Object** write_back);
// Special handling for serialized code like hooking up internalized strings.