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1 // Copyright 2016 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 #include "src/snapshot/code-serializer.h"
6 
7 #include <memory>
8 
9 #include "src/code-stubs.h"
10 #include "src/counters.h"
11 #include "src/debug/debug.h"
12 #include "src/log.h"
13 #include "src/macro-assembler.h"
14 #include "src/objects-inl.h"
15 #include "src/snapshot/object-deserializer.h"
16 #include "src/snapshot/snapshot.h"
17 #include "src/version.h"
18 #include "src/visitors.h"
19 
20 namespace v8 {
21 namespace internal {
22 
ScriptData(const byte * data,int length)23 ScriptData::ScriptData(const byte* data, int length)
24     : owns_data_(false), rejected_(false), data_(data), length_(length) {
25   if (!IsAligned(reinterpret_cast<intptr_t>(data), kPointerAlignment)) {
26     byte* copy = NewArray<byte>(length);
27     DCHECK(IsAligned(reinterpret_cast<intptr_t>(copy), kPointerAlignment));
28     CopyBytes(copy, data, length);
29     data_ = copy;
30     AcquireDataOwnership();
31   }
32 }
33 
CodeSerializer(Isolate * isolate,uint32_t source_hash)34 CodeSerializer::CodeSerializer(Isolate* isolate, uint32_t source_hash)
35     : Serializer(isolate), source_hash_(source_hash) {
36   allocator()->UseCustomChunkSize(FLAG_serialization_chunk_size);
37 }
38 
39 // static
Serialize(Handle<SharedFunctionInfo> info)40 ScriptCompiler::CachedData* CodeSerializer::Serialize(
41     Handle<SharedFunctionInfo> info) {
42   Isolate* isolate = info->GetIsolate();
43   TRACE_EVENT_CALL_STATS_SCOPED(isolate, "v8", "V8.Execute");
44   HistogramTimerScope histogram_timer(isolate->counters()->compile_serialize());
45   RuntimeCallTimerScope runtimeTimer(isolate,
46                                      RuntimeCallCounterId::kCompileSerialize);
47   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"), "V8.CompileSerialize");
48 
49   base::ElapsedTimer timer;
50   if (FLAG_profile_deserialization) timer.Start();
51   Handle<Script> script(Script::cast(info->script()), isolate);
52   if (FLAG_trace_serializer) {
53     PrintF("[Serializing from");
54     script->name()->ShortPrint();
55     PrintF("]\n");
56   }
57   // TODO(7110): Enable serialization of Asm modules once the AsmWasmData is
58   // context independent.
59   if (script->ContainsAsmModule()) return nullptr;
60 
61   isolate->heap()->read_only_space()->ClearStringPaddingIfNeeded();
62 
63   // Serialize code object.
64   Handle<String> source(String::cast(script->source()), isolate);
65   CodeSerializer cs(isolate, SerializedCodeData::SourceHash(
66                                  source, script->origin_options()));
67   DisallowHeapAllocation no_gc;
68   cs.reference_map()->AddAttachedReference(*source);
69   ScriptData* script_data = cs.SerializeSharedFunctionInfo(info);
70 
71   if (FLAG_profile_deserialization) {
72     double ms = timer.Elapsed().InMillisecondsF();
73     int length = script_data->length();
74     PrintF("[Serializing to %d bytes took %0.3f ms]\n", length, ms);
75   }
76 
77   ScriptCompiler::CachedData* result =
78       new ScriptCompiler::CachedData(script_data->data(), script_data->length(),
79                                      ScriptCompiler::CachedData::BufferOwned);
80   script_data->ReleaseDataOwnership();
81   delete script_data;
82 
83   return result;
84 }
85 
SerializeSharedFunctionInfo(Handle<SharedFunctionInfo> info)86 ScriptData* CodeSerializer::SerializeSharedFunctionInfo(
87     Handle<SharedFunctionInfo> info) {
88   DisallowHeapAllocation no_gc;
89 
90   VisitRootPointer(Root::kHandleScope, nullptr,
91                    Handle<Object>::cast(info).location());
92   SerializeDeferredObjects();
93   Pad();
94 
95   SerializedCodeData data(sink_.data(), this);
96 
97   return data.GetScriptData();
98 }
99 
SerializeReadOnlyObject(HeapObject * obj,HowToCode how_to_code,WhereToPoint where_to_point,int skip)100 bool CodeSerializer::SerializeReadOnlyObject(HeapObject* obj,
101                                              HowToCode how_to_code,
102                                              WhereToPoint where_to_point,
103                                              int skip) {
104   PagedSpace* read_only_space = isolate()->heap()->read_only_space();
105   if (!read_only_space->Contains(obj)) return false;
106 
107   // For objects in RO_SPACE, never serialize the object, but instead create a
108   // back reference that encodes the page number as the chunk_index and the
109   // offset within the page as the chunk_offset.
110   Address address = obj->address();
111   Page* page = Page::FromAddress(address);
112   uint32_t chunk_index = 0;
113   for (Page* p : *read_only_space) {
114     if (p == page) break;
115     ++chunk_index;
116   }
117   uint32_t chunk_offset = static_cast<uint32_t>(page->Offset(address));
118   SerializerReference back_reference =
119       SerializerReference::BackReference(RO_SPACE, chunk_index, chunk_offset);
120   reference_map()->Add(obj, back_reference);
121   CHECK(SerializeBackReference(obj, how_to_code, where_to_point, skip));
122   return true;
123 }
124 
SerializeObject(HeapObject * obj,HowToCode how_to_code,WhereToPoint where_to_point,int skip)125 void CodeSerializer::SerializeObject(HeapObject* obj, HowToCode how_to_code,
126                                      WhereToPoint where_to_point, int skip) {
127   if (SerializeHotObject(obj, how_to_code, where_to_point, skip)) return;
128 
129   int root_index = root_index_map()->Lookup(obj);
130   if (root_index != RootIndexMap::kInvalidRootIndex) {
131     PutRoot(root_index, obj, how_to_code, where_to_point, skip);
132     return;
133   }
134 
135   if (SerializeBackReference(obj, how_to_code, where_to_point, skip)) return;
136 
137   if (SerializeReadOnlyObject(obj, how_to_code, where_to_point, skip)) return;
138 
139   FlushSkip(skip);
140 
141   if (obj->IsCode()) {
142     Code* code_object = Code::cast(obj);
143     switch (code_object->kind()) {
144       case Code::OPTIMIZED_FUNCTION:  // No optimized code compiled yet.
145       case Code::REGEXP:              // No regexp literals initialized yet.
146       case Code::NUMBER_OF_KINDS:     // Pseudo enum value.
147       case Code::BYTECODE_HANDLER:    // No direct references to handlers.
148         break;                        // hit UNREACHABLE below.
149       case Code::BUILTIN:
150         SerializeBuiltinReference(code_object, how_to_code, where_to_point, 0);
151         return;
152       case Code::STUB:
153         if (code_object->builtin_index() == -1) {
154           SerializeCodeStub(code_object, how_to_code, where_to_point);
155         } else {
156           SerializeBuiltinReference(code_object, how_to_code, where_to_point,
157                                     0);
158         }
159         return;
160       default:
161         return SerializeCodeObject(code_object, how_to_code, where_to_point);
162     }
163     UNREACHABLE();
164   }
165 
166   ReadOnlyRoots roots(isolate());
167   if (ElideObject(obj)) {
168     return SerializeObject(roots.undefined_value(), how_to_code, where_to_point,
169                            skip);
170   }
171 
172   if (obj->IsScript()) {
173     Script* script_obj = Script::cast(obj);
174     DCHECK_NE(script_obj->compilation_type(), Script::COMPILATION_TYPE_EVAL);
175     // We want to differentiate between undefined and uninitialized_symbol for
176     // context_data for now. It is hack to allow debugging for scripts that are
177     // included as a part of custom snapshot. (see debug::Script::IsEmbedded())
178     Object* context_data = script_obj->context_data();
179     if (context_data != roots.undefined_value() &&
180         context_data != roots.uninitialized_symbol()) {
181       script_obj->set_context_data(roots.undefined_value());
182     }
183     // We don't want to serialize host options to avoid serializing unnecessary
184     // object graph.
185     FixedArray* host_options = script_obj->host_defined_options();
186     script_obj->set_host_defined_options(roots.empty_fixed_array());
187     SerializeGeneric(obj, how_to_code, where_to_point);
188     script_obj->set_host_defined_options(host_options);
189     script_obj->set_context_data(context_data);
190     return;
191   }
192 
193   if (obj->IsSharedFunctionInfo()) {
194     SharedFunctionInfo* sfi = SharedFunctionInfo::cast(obj);
195     // TODO(7110): Enable serializing of Asm modules once the AsmWasmData
196     // is context independent.
197     DCHECK(!sfi->IsApiFunction() && !sfi->HasAsmWasmData());
198 
199     DebugInfo* debug_info = nullptr;
200     BytecodeArray* debug_bytecode_array = nullptr;
201     if (sfi->HasDebugInfo()) {
202       // Clear debug info.
203       debug_info = sfi->GetDebugInfo();
204       if (debug_info->HasInstrumentedBytecodeArray()) {
205         debug_bytecode_array = debug_info->DebugBytecodeArray();
206         sfi->SetDebugBytecodeArray(debug_info->OriginalBytecodeArray());
207       }
208       sfi->set_script_or_debug_info(debug_info->script());
209     }
210     DCHECK(!sfi->HasDebugInfo());
211 
212     // Mark SFI to indicate whether the code is cached.
213     bool was_deserialized = sfi->deserialized();
214     sfi->set_deserialized(sfi->is_compiled());
215     SerializeGeneric(obj, how_to_code, where_to_point);
216     sfi->set_deserialized(was_deserialized);
217 
218     // Restore debug info
219     if (debug_info != nullptr) {
220       sfi->set_script_or_debug_info(debug_info);
221       if (debug_bytecode_array != nullptr) {
222         sfi->SetDebugBytecodeArray(debug_bytecode_array);
223       }
224     }
225     return;
226   }
227 
228   if (obj->IsBytecodeArray()) {
229     // Clear the stack frame cache if present
230     BytecodeArray::cast(obj)->ClearFrameCacheFromSourcePositionTable();
231   }
232 
233   // Past this point we should not see any (context-specific) maps anymore.
234   CHECK(!obj->IsMap());
235   // There should be no references to the global object embedded.
236   CHECK(!obj->IsJSGlobalProxy() && !obj->IsJSGlobalObject());
237   // Embedded FixedArrays that need rehashing must support rehashing.
238   CHECK_IMPLIES(obj->NeedsRehashing(), obj->CanBeRehashed());
239   // We expect no instantiated function objects or contexts.
240   CHECK(!obj->IsJSFunction() && !obj->IsContext());
241 
242   SerializeGeneric(obj, how_to_code, where_to_point);
243 }
244 
SerializeGeneric(HeapObject * heap_object,HowToCode how_to_code,WhereToPoint where_to_point)245 void CodeSerializer::SerializeGeneric(HeapObject* heap_object,
246                                       HowToCode how_to_code,
247                                       WhereToPoint where_to_point) {
248   // Object has not yet been serialized.  Serialize it here.
249   ObjectSerializer serializer(this, heap_object, &sink_, how_to_code,
250                               where_to_point);
251   serializer.Serialize();
252 }
253 
SerializeCodeStub(Code * code_stub,HowToCode how_to_code,WhereToPoint where_to_point)254 void CodeSerializer::SerializeCodeStub(Code* code_stub, HowToCode how_to_code,
255                                        WhereToPoint where_to_point) {
256   // We only arrive here if we have not encountered this code stub before.
257   DCHECK(!reference_map()->LookupReference(code_stub).is_valid());
258   uint32_t stub_key = code_stub->stub_key();
259   DCHECK(CodeStub::MajorKeyFromKey(stub_key) != CodeStub::NoCache);
260   DCHECK(!CodeStub::GetCode(isolate(), stub_key).is_null());
261   stub_keys_.push_back(stub_key);
262 
263   SerializerReference reference =
264       reference_map()->AddAttachedReference(code_stub);
265   if (FLAG_trace_serializer) {
266     PrintF(" Encoding code stub %s as attached reference %d\n",
267            CodeStub::MajorName(CodeStub::MajorKeyFromKey(stub_key)),
268            reference.attached_reference_index());
269   }
270   PutAttachedReference(reference, how_to_code, where_to_point);
271 }
272 
Deserialize(Isolate * isolate,ScriptData * cached_data,Handle<String> source,ScriptOriginOptions origin_options)273 MaybeHandle<SharedFunctionInfo> CodeSerializer::Deserialize(
274     Isolate* isolate, ScriptData* cached_data, Handle<String> source,
275     ScriptOriginOptions origin_options) {
276   base::ElapsedTimer timer;
277   if (FLAG_profile_deserialization || FLAG_log_function_events) timer.Start();
278 
279   HandleScope scope(isolate);
280 
281   SerializedCodeData::SanityCheckResult sanity_check_result =
282       SerializedCodeData::CHECK_SUCCESS;
283   const SerializedCodeData scd = SerializedCodeData::FromCachedData(
284       isolate, cached_data,
285       SerializedCodeData::SourceHash(source, origin_options),
286       &sanity_check_result);
287   if (sanity_check_result != SerializedCodeData::CHECK_SUCCESS) {
288     if (FLAG_profile_deserialization) PrintF("[Cached code failed check]\n");
289     DCHECK(cached_data->rejected());
290     isolate->counters()->code_cache_reject_reason()->AddSample(
291         sanity_check_result);
292     return MaybeHandle<SharedFunctionInfo>();
293   }
294 
295   // Deserialize.
296   MaybeHandle<SharedFunctionInfo> maybe_result =
297       ObjectDeserializer::DeserializeSharedFunctionInfo(isolate, &scd, source);
298 
299   Handle<SharedFunctionInfo> result;
300   if (!maybe_result.ToHandle(&result)) {
301     // Deserializing may fail if the reservations cannot be fulfilled.
302     if (FLAG_profile_deserialization) PrintF("[Deserializing failed]\n");
303     return MaybeHandle<SharedFunctionInfo>();
304   }
305 
306   if (FLAG_profile_deserialization) {
307     double ms = timer.Elapsed().InMillisecondsF();
308     int length = cached_data->length();
309     PrintF("[Deserializing from %d bytes took %0.3f ms]\n", length, ms);
310   }
311 
312   bool log_code_creation = isolate->logger()->is_listening_to_code_events() ||
313                            isolate->is_profiling();
314   if (log_code_creation || FLAG_log_function_events) {
315     String* name = ReadOnlyRoots(isolate).empty_string();
316     if (result->script()->IsScript()) {
317       Script* script = Script::cast(result->script());
318       if (script->name()->IsString()) name = String::cast(script->name());
319       if (FLAG_log_function_events) {
320         LOG(isolate, FunctionEvent("deserialize", script->id(),
321                                    timer.Elapsed().InMillisecondsF(),
322                                    result->StartPosition(),
323                                    result->EndPosition(), name));
324       }
325     }
326     if (log_code_creation) {
327       PROFILE(isolate, CodeCreateEvent(CodeEventListener::SCRIPT_TAG,
328                                        result->abstract_code(), *result, name));
329     }
330   }
331 
332   if (isolate->NeedsSourcePositionsForProfiling()) {
333     Handle<Script> script(Script::cast(result->script()), isolate);
334     Script::InitLineEnds(script);
335   }
336   return scope.CloseAndEscape(result);
337 }
338 
339 class Checksum {
340  public:
Checksum(Vector<const byte> payload)341   explicit Checksum(Vector<const byte> payload) {
342 #ifdef MEMORY_SANITIZER
343     // Computing the checksum includes padding bytes for objects like strings.
344     // Mark every object as initialized in the code serializer.
345     MSAN_MEMORY_IS_INITIALIZED(payload.start(), payload.length());
346 #endif  // MEMORY_SANITIZER
347     // Fletcher's checksum. Modified to reduce 64-bit sums to 32-bit.
348     uintptr_t a = 1;
349     uintptr_t b = 0;
350     const uintptr_t* cur = reinterpret_cast<const uintptr_t*>(payload.start());
351     DCHECK(IsAligned(payload.length(), kIntptrSize));
352     const uintptr_t* end = cur + payload.length() / kIntptrSize;
353     while (cur < end) {
354       // Unsigned overflow expected and intended.
355       a += *cur++;
356       b += a;
357     }
358 #if V8_HOST_ARCH_64_BIT
359     a ^= a >> 32;
360     b ^= b >> 32;
361 #endif  // V8_HOST_ARCH_64_BIT
362     a_ = static_cast<uint32_t>(a);
363     b_ = static_cast<uint32_t>(b);
364   }
365 
Check(uint32_t a,uint32_t b) const366   bool Check(uint32_t a, uint32_t b) const { return a == a_ && b == b_; }
367 
a() const368   uint32_t a() const { return a_; }
b() const369   uint32_t b() const { return b_; }
370 
371  private:
372   uint32_t a_;
373   uint32_t b_;
374 
375   DISALLOW_COPY_AND_ASSIGN(Checksum);
376 };
377 
SerializedCodeData(const std::vector<byte> * payload,const CodeSerializer * cs)378 SerializedCodeData::SerializedCodeData(const std::vector<byte>* payload,
379                                        const CodeSerializer* cs) {
380   DisallowHeapAllocation no_gc;
381   const std::vector<uint32_t>* stub_keys = cs->stub_keys();
382   std::vector<Reservation> reservations = cs->EncodeReservations();
383 
384   // Calculate sizes.
385   uint32_t reservation_size =
386       static_cast<uint32_t>(reservations.size()) * kUInt32Size;
387   uint32_t num_stub_keys = static_cast<uint32_t>(stub_keys->size());
388   uint32_t stub_keys_size = num_stub_keys * kUInt32Size;
389   uint32_t payload_offset = kHeaderSize + reservation_size + stub_keys_size;
390   uint32_t padded_payload_offset = POINTER_SIZE_ALIGN(payload_offset);
391   uint32_t size =
392       padded_payload_offset + static_cast<uint32_t>(payload->size());
393 
394   // Allocate backing store and create result data.
395   AllocateData(size);
396 
397   // Set header values.
398   SetMagicNumber(cs->isolate());
399   SetHeaderValue(kVersionHashOffset, Version::Hash());
400   SetHeaderValue(kSourceHashOffset, cs->source_hash());
401   SetHeaderValue(kCpuFeaturesOffset,
402                  static_cast<uint32_t>(CpuFeatures::SupportedFeatures()));
403   SetHeaderValue(kFlagHashOffset, FlagList::Hash());
404   SetHeaderValue(kNumReservationsOffset,
405                  static_cast<uint32_t>(reservations.size()));
406   SetHeaderValue(kNumCodeStubKeysOffset, num_stub_keys);
407   SetHeaderValue(kPayloadLengthOffset, static_cast<uint32_t>(payload->size()));
408 
409   // Zero out any padding in the header.
410   memset(data_ + kUnalignedHeaderSize, 0, kHeaderSize - kUnalignedHeaderSize);
411 
412   // Copy reservation chunk sizes.
413   CopyBytes(data_ + kHeaderSize,
414             reinterpret_cast<const byte*>(reservations.data()),
415             reservation_size);
416 
417   // Copy code stub keys.
418   CopyBytes(data_ + kHeaderSize + reservation_size,
419             reinterpret_cast<const byte*>(stub_keys->data()), stub_keys_size);
420 
421   // Zero out any padding before the payload.
422   memset(data_ + payload_offset, 0, padded_payload_offset - payload_offset);
423 
424   // Copy serialized data.
425   CopyBytes(data_ + padded_payload_offset, payload->data(),
426             static_cast<size_t>(payload->size()));
427 
428   Checksum checksum(DataWithoutHeader());
429   SetHeaderValue(kChecksum1Offset, checksum.a());
430   SetHeaderValue(kChecksum2Offset, checksum.b());
431 }
432 
SanityCheck(Isolate * isolate,uint32_t expected_source_hash) const433 SerializedCodeData::SanityCheckResult SerializedCodeData::SanityCheck(
434     Isolate* isolate, uint32_t expected_source_hash) const {
435   if (this->size_ < kHeaderSize) return INVALID_HEADER;
436   uint32_t magic_number = GetMagicNumber();
437   if (magic_number != ComputeMagicNumber(isolate)) return MAGIC_NUMBER_MISMATCH;
438   uint32_t version_hash = GetHeaderValue(kVersionHashOffset);
439   uint32_t source_hash = GetHeaderValue(kSourceHashOffset);
440   uint32_t cpu_features = GetHeaderValue(kCpuFeaturesOffset);
441   uint32_t flags_hash = GetHeaderValue(kFlagHashOffset);
442   uint32_t payload_length = GetHeaderValue(kPayloadLengthOffset);
443   uint32_t c1 = GetHeaderValue(kChecksum1Offset);
444   uint32_t c2 = GetHeaderValue(kChecksum2Offset);
445   if (version_hash != Version::Hash()) return VERSION_MISMATCH;
446   if (source_hash != expected_source_hash) return SOURCE_MISMATCH;
447   if (cpu_features != static_cast<uint32_t>(CpuFeatures::SupportedFeatures())) {
448     return CPU_FEATURES_MISMATCH;
449   }
450   if (flags_hash != FlagList::Hash()) return FLAGS_MISMATCH;
451   uint32_t max_payload_length =
452       this->size_ -
453       POINTER_SIZE_ALIGN(kHeaderSize +
454                          GetHeaderValue(kNumReservationsOffset) * kInt32Size +
455                          GetHeaderValue(kNumCodeStubKeysOffset) * kInt32Size);
456   if (payload_length > max_payload_length) return LENGTH_MISMATCH;
457   if (!Checksum(DataWithoutHeader()).Check(c1, c2)) return CHECKSUM_MISMATCH;
458   return CHECK_SUCCESS;
459 }
460 
SourceHash(Handle<String> source,ScriptOriginOptions origin_options)461 uint32_t SerializedCodeData::SourceHash(Handle<String> source,
462                                         ScriptOriginOptions origin_options) {
463   const uint32_t source_length = source->length();
464 
465   static constexpr uint32_t kModuleFlagMask = (1 << 31);
466   const uint32_t is_module = origin_options.IsModule() ? kModuleFlagMask : 0;
467   DCHECK_EQ(0, source_length & kModuleFlagMask);
468 
469   return source_length | is_module;
470 }
471 
472 // Return ScriptData object and relinquish ownership over it to the caller.
GetScriptData()473 ScriptData* SerializedCodeData::GetScriptData() {
474   DCHECK(owns_data_);
475   ScriptData* result = new ScriptData(data_, size_);
476   result->AcquireDataOwnership();
477   owns_data_ = false;
478   data_ = nullptr;
479   return result;
480 }
481 
Reservations() const482 std::vector<SerializedData::Reservation> SerializedCodeData::Reservations()
483     const {
484   uint32_t size = GetHeaderValue(kNumReservationsOffset);
485   std::vector<Reservation> reservations(size);
486   memcpy(reservations.data(), data_ + kHeaderSize,
487          size * sizeof(SerializedData::Reservation));
488   return reservations;
489 }
490 
Payload() const491 Vector<const byte> SerializedCodeData::Payload() const {
492   int reservations_size = GetHeaderValue(kNumReservationsOffset) * kInt32Size;
493   int code_stubs_size = GetHeaderValue(kNumCodeStubKeysOffset) * kInt32Size;
494   int payload_offset = kHeaderSize + reservations_size + code_stubs_size;
495   int padded_payload_offset = POINTER_SIZE_ALIGN(payload_offset);
496   const byte* payload = data_ + padded_payload_offset;
497   DCHECK(IsAligned(reinterpret_cast<intptr_t>(payload), kPointerAlignment));
498   int length = GetHeaderValue(kPayloadLengthOffset);
499   DCHECK_EQ(data_ + size_, payload + length);
500   return Vector<const byte>(payload, length);
501 }
502 
CodeStubKeys() const503 Vector<const uint32_t> SerializedCodeData::CodeStubKeys() const {
504   int reservations_size = GetHeaderValue(kNumReservationsOffset) * kInt32Size;
505   const byte* start = data_ + kHeaderSize + reservations_size;
506   return Vector<const uint32_t>(reinterpret_cast<const uint32_t*>(start),
507                                 GetHeaderValue(kNumCodeStubKeysOffset));
508 }
509 
SerializedCodeData(ScriptData * data)510 SerializedCodeData::SerializedCodeData(ScriptData* data)
511     : SerializedData(const_cast<byte*>(data->data()), data->length()) {}
512 
FromCachedData(Isolate * isolate,ScriptData * cached_data,uint32_t expected_source_hash,SanityCheckResult * rejection_result)513 SerializedCodeData SerializedCodeData::FromCachedData(
514     Isolate* isolate, ScriptData* cached_data, uint32_t expected_source_hash,
515     SanityCheckResult* rejection_result) {
516   DisallowHeapAllocation no_gc;
517   SerializedCodeData scd(cached_data);
518   *rejection_result = scd.SanityCheck(isolate, expected_source_hash);
519   if (*rejection_result != CHECK_SUCCESS) {
520     cached_data->Reject();
521     return SerializedCodeData(nullptr, 0);
522   }
523   return scd;
524 }
525 
526 }  // namespace internal
527 }  // namespace v8
528