Ensure only whitelisted stubs have sse2 versions in the snapshot.

src/mips/assembler-mips.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 393 matching lines @@
 // Supported features must be enabled by a CpuFeatureScope before use.
 class CpuFeatures : public AllStatic {
  public:
   // Detect features of the target CPU. Set safe defaults if the serializer
   // is enabled (snapshots must be portable).
   static void Probe();
 
   // Check whether a feature is supported by the target CPU.
   static bool IsSupported(CpuFeature f) {
     ASSERT(initialized_);
-    return (supported_ & (1u << f)) != 0;
+    return Check(f, supported_);
   }
 
   static bool IsFoundByRuntimeProbingOnly(CpuFeature f) {
     ASSERT(initialized_);
-    return (found_by_runtime_probing_only_ &
-            (static_cast<uint64_t>(1) << f)) != 0;
+    return Check(f, found_by_runtime_probing_only_);
   }
 
   static bool IsSafeForSnapshot(CpuFeature f) {
-    return (IsSupported(f) &&
+    return Check(f, cross_compile_) ||
+           (IsSupported(f) &&
             (!Serializer::enabled() || !IsFoundByRuntimeProbingOnly(f)));
   }
 
+  static bool VerifyCrossCompiling() {
+    return cross_compile_ == 0;
+  }
+
+  static bool VerifyCrossCompiling(CpuFeature f) {
+    unsigned mask = flag2set(f);
+    return cross_compile_ == 0 ||
+           (cross_compile_ & mask) == mask;
+  }
+
  private:
+  static bool Check(CpuFeature f, unsigned set) {
+    return (set & flag2set(f)) != 0;
+  }
+
+  static unsigned flag2set(CpuFeature f) {
+    return 1u << f;
+  }
+
 #ifdef DEBUG
   static bool initialized_;
 #endif
   static unsigned supported_;
   static unsigned found_by_runtime_probing_only_;
 
+  static unsigned cross_compile_;
+
   friend class ExternalReference;
   friend class PlatformFeatureScope;
   DISALLOW_COPY_AND_ASSIGN(CpuFeatures);
 };
 
 
 class Assembler : public AssemblerBase {
  public:
   // Create an assembler. Instructions and relocation information are emitted
   // into a buffer, with the instructions starting from the beginning and the
@@ skipping 773 matching lines @@
 class EnsureSpace BASE_EMBEDDED {
  public:
   explicit EnsureSpace(Assembler* assembler) {
     assembler->CheckBuffer();
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_ARM_ASSEMBLER_MIPS_H_