Serializer: micro-optimizations for the deserializer.

src/snapshot-source-sink.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_SNAPSHOT_SOURCE_SINK_H_
 #define V8_SNAPSHOT_SOURCE_SINK_H_
 
 #include "src/base/logging.h"
 #include "src/utils.h"
 
@@ skipping 18 matching lines @@
 
   ~SnapshotByteSource() {}
 
   bool HasMore() { return position_ < length_; }
 
   byte Get() {
     DCHECK(position_ < length_);
     return data_[position_++];
   }
 
-  int32_t GetUnalignedInt();
-
   void Advance(int by) { position_ += by; }
 
   void CopyRaw(byte* to, int number_of_bytes);
 
   inline int GetInt() {
-    // This way of variable-length encoding integers does not suffer from branch
-    // mispredictions.
-    uint32_t answer = GetUnalignedInt();
+    // This way of decoding variable-length encoded integers does not
+    // suffer from branch mispredictions.
+    DCHECK(position_ + 3 < length_);
+    uint32_t answer = data_[position_];
+    answer |= data_[position_ + 1] << 8;
+    answer |= data_[position_ + 2] << 16;
+    answer |= data_[position_ + 3] << 24;
     int bytes = (answer & 3) + 1;
     Advance(bytes);
     uint32_t mask = 0xffffffffu;
     mask >>= 32 - (bytes << 3);
     answer &= mask;
     answer >>= 2;
     return answer;
   }
 
   bool GetBlob(const byte** data, int* number_of_bytes);
@@ skipping 37 matching lines @@
   const List<byte>& data() const { return data_; }
 
  private:
   List<byte> data_;
 };
 
 }  // namespace v8::internal
 }  // namespace v8
 
 #endif  // V8_SNAPSHOT_SOURCE_SINK_H_