[strong] Disallow implicit conversions for comparison

src/code-stubs.h

Index: src/code-stubs.h
diff --git a/src/code-stubs.h b/src/code-stubs.h
index 040bf10f774597fed42d95832a349d03631a1899..56d08b0ebcf3e1b2000d1439d41b240d5296c45f 100644
--- a/src/code-stubs.h
+++ b/src/code-stubs.h
@@ -1469,12 +1469,14 @@ class StringAddStub final : public HydrogenCodeStub {
 
 class CompareICStub : public PlatformCodeStub {
  public:
-  CompareICStub(Isolate* isolate, Token::Value op, CompareICState::State left,
-                CompareICState::State right, CompareICState::State state)
+  CompareICStub(Isolate* isolate, Token::Value op, bool strong,
+                CompareICState::State left, CompareICState::State right,
+                CompareICState::State state)
       : PlatformCodeStub(isolate) {
     DCHECK(Token::IsCompareOp(op));
-    minor_key_ = OpBits::encode(op - Token::EQ) | LeftStateBits::encode(left) |
-                 RightStateBits::encode(right) | StateBits::encode(state);
+    minor_key_ = OpBits::encode(op - Token::EQ) | StrongBits::encode(strong) |
+                 LeftStateBits::encode(left) | RightStateBits::encode(right) |
+                 StateBits::encode(state);
   }
 
   void set_known_map(Handle<Map> map) { known_map_ = map; }
@@ -1485,6 +1487,8 @@ class CompareICStub : public PlatformCodeStub {
     return static_cast<Token::Value>(Token::EQ + OpBits::decode(minor_key_));
   }
 
+  bool strong() const { return StrongBits::decode(minor_key_); }
+
   CompareICState::State left() const {
     return LeftStateBits::decode(minor_key_);
   }
@@ -1516,9 +1520,10 @@ class CompareICStub : public PlatformCodeStub {
   }
 
   class OpBits : public BitField<int, 0, 3> {};
-  class LeftStateBits : public BitField<CompareICState::State, 3, 4> {};
-  class RightStateBits : public BitField<CompareICState::State, 7, 4> {};
-  class StateBits : public BitField<CompareICState::State, 11, 4> {};
+  class StrongBits : public BitField<bool, 3, 1> {};
+  class LeftStateBits : public BitField<CompareICState::State, 4, 4> {};
+  class RightStateBits : public BitField<CompareICState::State, 8, 4> {};
+  class StateBits : public BitField<CompareICState::State, 12, 4> {};
 
   Handle<Map> known_map_;