MIPS: Fix NaN value inconsistency with snapshots (alternate implementation).

src/serialize.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1426 matching lines @@
 
   // Mark this object as already serialized.
   bool start_new_page;
   int offset = serializer_->Allocate(space, size, &start_new_page);
   serializer_->address_mapper()->AddMapping(object_, offset);
   if (start_new_page) {
     sink_->Put(kNewPage, "NewPage");
     sink_->PutSection(space, "NewPageSpace");
   }
 
+#ifdef V8_TARGET_ARCH_MIPS
+#define MIPS_QNAN_HI 0x7ff7ffff
+#define MIPS_QNAN_LO 0xffffffff
+  // Mips has a different encoding of qNaN than ia32, so any heap NaN built
+  // with simulator must be re-encoded for the snapshot. Performance hit not
+  // critical at mksnapshot/build time.
+  if (object_->IsNaN()) {
+    uint64_t mips_qnan_bits =
+        (static_cast<uint64_t>(MIPS_QNAN_HI) << 32) | MIPS_QNAN_LO;
+    Address value_ptr = (reinterpret_cast<byte*>(object_) +
+        HeapNumber::kValueOffset - kHeapObjectTag);
+    memcpy(value_ptr, &mips_qnan_bits, sizeof(mips_qnan_bits));
+  }
+#endif  // V8_TARGET_ARCH_MIPS
+
   // Serialize the map (first word of the object).
   serializer_->SerializeObject(object_->map(), kPlain, kStartOfObject);
 
   // Serialize the rest of the object.
   CHECK_EQ(0, bytes_processed_so_far_);
   bytes_processed_so_far_ = kPointerSize;
   object_->IterateBody(object_->map()->instance_type(), size, this);
   OutputRawData(object_->address() + size);
 }
 
@@ skipping 242 matching lines @@
 int Serializer::SpaceAreaSize(int space) {
   if (space == CODE_SPACE) {
     return isolate_->memory_allocator()->CodePageAreaSize();
   } else {
     return Page::kPageSize - Page::kObjectStartOffset;
   }
 }
 
 
 } }  // namespace v8::internal