Track code cache reject reason via histogram buckets.

R=vogelheim@chromium.org
BUG=chromium:441896
LOG=N

Review URL: https://codereview.chromium.org/922573003

Cr-Commit-Position: refs/heads/master@{#26660}

src/counters.h

@@ -362,7 +362,9 @@ class AggregatedHistogramTimerScope {
   /* Generic range histograms */                                              \
   HR(gc_idle_time_allotted_in_ms, V8.GCIdleTimeAllottedInMS, 0, 10000, 101)   \
   HR(gc_idle_time_limit_overshot, V8.GCIdleTimeLimit.Overshot, 0, 10000, 101) \
-  HR(gc_idle_time_limit_undershot, V8.GCIdleTimeLimit.Undershot, 0, 10000, 101)
+  HR(gc_idle_time_limit_undershot, V8.GCIdleTimeLimit.Undershot, 0, 10000,    \
+     101)                                                                     \
+  HR(code_cache_reject_reason, V8.CodeCacheRejectReason, 1, 6, 6)
 
 #define HISTOGRAM_TIMER_LIST(HT)                                              \
   /* Garbage collection timers. */                                            \

src/serialize.cc

@@ -2567,6 +2567,7 @@ SerializedCodeData::SerializedCodeData(const List<byte>& payload,
   AllocateData(size);
 
   // Set header values.
+  SetHeaderValue(kMagicNumberOffset, kMagicNumber);
   SetHeaderValue(kVersionHashOffset, Version::Hash());
   SetHeaderValue(kSourceHashOffset, SourceHash(cs.source()));
   SetHeaderValue(kCpuFeaturesOffset,
@@ -2597,14 +2598,24 @@ SerializedCodeData::SerializedCodeData(const List<byte>& payload,
 }
 
 
-bool SerializedCodeData::IsSane(String* source) const {
-  return GetHeaderValue(kVersionHashOffset) == Version::Hash() &&
-         GetHeaderValue(kSourceHashOffset) == SourceHash(source) &&
-         GetHeaderValue(kCpuFeaturesOffset) ==
-             static_cast<uint32_t>(CpuFeatures::SupportedFeatures()) &&
-         GetHeaderValue(kFlagHashOffset) == FlagList::Hash() &&
-         Checksum(Payload()).Check(GetHeaderValue(kChecksum1Offset),
-                                   GetHeaderValue(kChecksum2Offset));
+SerializedCodeData::SanityCheckResult SerializedCodeData::SanityCheck(
+    String* source) const {
+  uint32_t magic_number = GetHeaderValue(kMagicNumberOffset);
+  uint32_t version_hash = GetHeaderValue(kVersionHashOffset);
+  uint32_t source_hash = GetHeaderValue(kSourceHashOffset);
+  uint32_t cpu_features = GetHeaderValue(kCpuFeaturesOffset);
+  uint32_t flags_hash = GetHeaderValue(kFlagHashOffset);
+  uint32_t c1 = GetHeaderValue(kChecksum1Offset);
+  uint32_t c2 = GetHeaderValue(kChecksum2Offset);
+  if (magic_number != kMagicNumber) return MAGIC_NUMBER_MISMATCH;
+  if (version_hash != Version::Hash()) return VERSION_MISMATCH;
+  if (source_hash != SourceHash(source)) return SOURCE_MISMATCH;
+  if (cpu_features != static_cast<uint32_t>(CpuFeatures::SupportedFeatures())) {
+    return CPU_FEATURES_MISMATCH;
+  }
+  if (flags_hash != FlagList::Hash()) return FLAGS_MISMATCH;
+  if (!Checksum(Payload()).Check(c1, c2)) return CHECKSUM_MISMATCH;
+  return CHECK_SUCCESS;
 }
 
 
@@ -2660,8 +2671,10 @@ SerializedCodeData* SerializedCodeData::FromCachedData(ScriptData* cached_data,
                                                        String* source) {
   DisallowHeapAllocation no_gc;
   SerializedCodeData* scd = new SerializedCodeData(cached_data);
-  if (scd->IsSane(source)) return scd;
+  SanityCheckResult r = scd->SanityCheck(source);
+  if (r == CHECK_SUCCESS) return scd;
   cached_data->Reject();
+  source->GetIsolate()->counters()->code_cache_reject_reason()->AddSample(r);
   delete scd;
   return NULL;
 }

src/serialize.h

@@ -949,25 +949,39 @@ class SerializedCodeData : public SerializedData {
  private:
   explicit SerializedCodeData(ScriptData* data);
 
-  bool IsSane(String* source) const;
+  enum SanityCheckResult {
+    CHECK_SUCCESS = 0,
+    MAGIC_NUMBER_MISMATCH = 1,
+    VERSION_MISMATCH = 2,
+    SOURCE_MISMATCH = 3,
+    CPU_FEATURES_MISMATCH = 4,
+    FLAGS_MISMATCH = 5,
+    CHECKSUM_MISMATCH = 6,
+  };
+
+  SanityCheckResult SanityCheck(String* source) const;
 
   uint32_t SourceHash(String* source) const { return source->length(); }
 
+  static const uint32_t kMagicNumber = 0xC0D1F1ED;
+
   // The data header consists of uint32_t-sized entries:
-  // [0] version hash
-  // [1] source hash
-  // [2] cpu features
-  // [3] flag hash
-  // [4] number of internalized strings
-  // [5] number of code stub keys
-  // [6] number of reservation size entries
-  // [7] payload length
-  // [8] payload checksum part 1
-  // [9] payload checksum part 2
-  // ... reservations
-  // ... code stub keys
-  // ... serialized payload
-  static const int kVersionHashOffset = 0;
+  // [ 0] magic number
+  // [ 1] version hash
+  // [ 2] source hash
+  // [ 3] cpu features
+  // [ 4] flag hash
+  // [ 5] number of internalized strings
+  // [ 6] number of code stub keys
+  // [ 7] number of reservation size entries
+  // [ 8] payload length
+  // [ 9] payload checksum part 1
+  // [10] payload checksum part 2
+  // ...  reservations
+  // ...  code stub keys
+  // ...  serialized payload
+  static const int kMagicNumberOffset = 0;
+  static const int kVersionHashOffset = kMagicNumberOffset + kInt32Size;
   static const int kSourceHashOffset = kVersionHashOffset + kInt32Size;
   static const int kCpuFeaturesOffset = kSourceHashOffset + kInt32Size;
   static const int kFlagHashOffset = kCpuFeaturesOffset + kInt32Size;