[crankshaft] There is no guarantee that allocations are folded in Crankshaft.

src/crankshaft/hydrogen-instructions.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_CRANKSHAFT_HYDROGEN_INSTRUCTIONS_H_
 #define V8_CRANKSHAFT_HYDROGEN_INSTRUCTIONS_H_
 
 #include <cstring>
 #include <iosfwd>
 
@@ skipping 5130 matching lines @@
                                             HValue* dominator) {
   // There may be multiple inner allocates dominated by one allocate.
   while (object->IsInnerAllocatedObject()) {
     object = HInnerAllocatedObject::cast(object)->base_object();
   }
 
   if (object->IsAllocate()) {
     HAllocate* allocate = HAllocate::cast(object);
     if (allocate->IsAllocationFolded()) {
       HValue* dominator = allocate->allocation_folding_dominator();
-      DCHECK(HAllocate::cast(dominator)->IsAllocationFoldingDominator());
-      object = dominator;
+      // There is no guarantee that all allocations are folded together because
+      // GVN performs a fixpoint.
+      if (HAllocate::cast(dominator)->IsAllocationFoldingDominator()) {
+        object = dominator;
+      }
     }
   }
 
   if (object->IsConstant() &&
       HConstant::cast(object)->HasExternalReferenceValue()) {
     // Stores to external references require no write barriers
     return false;
   }
   // We definitely need a write barrier unless the object is the allocation
   // dominator.
@@ skipping 2041 matching lines @@
   bool IsDeletable() const override { return true; }
 };
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_CRANKSHAFT_HYDROGEN_INSTRUCTIONS_H_