Avoid hydrogen compare-objects-equal assertions in dead code

src/hydrogen.cc

 // Copyright 2013 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 9828 matching lines @@
         HCompareObjectEqAndBranch* result =
             New<HCompareObjectEqAndBranch>(left, right);
         return result;
       }
     } else {
       Bailout(kUnsupportedNonPrimitiveCompare);
       return NULL;
     }
   } else if (combined_type->Is(Type::InternalizedString()) &&
              Token::IsEqualityOp(op)) {
+    // If we have a constant argument, it should be consistent with the type
+    // feedback (otherwise we fail assertions in HCompareObjectEqAndBranch).
+    if ((left->IsConstant() &&
+         !HConstant::cast(left)->HasInternalizedStringValue()) ||
+        (right->IsConstant() &&
+         !HConstant::cast(right)->HasInternalizedStringValue())) {
+      Add<HDeoptimize>("Type mismatch between feedback and constant",
+                       Deoptimizer::SOFT);
+      // The caller expects a branch instruction, so make it happy.
+      return New<HBranch>(graph()->GetConstantTrue());
+    }
     BuildCheckHeapObject(left);
     Add<HCheckInstanceType>(left, HCheckInstanceType::IS_INTERNALIZED_STRING);
     BuildCheckHeapObject(right);
     Add<HCheckInstanceType>(right, HCheckInstanceType::IS_INTERNALIZED_STRING);
     HCompareObjectEqAndBranch* result =
         New<HCompareObjectEqAndBranch>(left, right);
     return result;
   } else if (combined_type->Is(Type::String())) {
+    // If we have a constant argument, it should be consistent with the type
+    // feedback (otherwise we fail assertions in HCompareObjectEqAndBranch).
+    if ((left->IsConstant() &&
+         !HConstant::cast(left)->HasStringValue()) ||
+        (right->IsConstant() &&
+         !HConstant::cast(right)->HasStringValue())) {
+      Add<HDeoptimize>("Type mismatch between feedback and constant",
+                       Deoptimizer::SOFT);
+      // The caller expects a branch instruction, so make it happy.
+      return New<HBranch>(graph()->GetConstantTrue());
+    }
     BuildCheckHeapObject(left);
     Add<HCheckInstanceType>(left, HCheckInstanceType::IS_STRING);
     BuildCheckHeapObject(right);
     Add<HCheckInstanceType>(right, HCheckInstanceType::IS_STRING);
     HStringCompareAndBranch* result =
         New<HStringCompareAndBranch>(left, right, op);
     return result;
   } else {
     if (combined_rep.IsTagged() || combined_rep.IsNone()) {
       HCompareGeneric* result = Add<HCompareGeneric>(left, right, op);
@@ skipping 1635 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal