[Interpreter] Allocates new temporary register outside the reservation for consecutive registers.

src/interpreter/bytecode-generator.cc

 // Copyright 2015 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.
 
 #include "src/interpreter/bytecode-generator.h"
 
 #include "src/ast/scopes.h"
 #include "src/compiler.h"
 #include "src/interpreter/control-flow-builders.h"
 #include "src/objects.h"
@@ skipping 187 matching lines @@
   bool IsEffect() const { return kind_ == Expression::kEffect; }
   bool IsValue() const { return kind_ == Expression::kValue; }
 
   virtual void SetResultInAccumulator() = 0;
   virtual void SetResultInRegister(Register reg) = 0;
 
   BytecodeGenerator* generator() const { return generator_; }
   BytecodeArrayBuilder* builder() const { return generator()->builder(); }
   ExpressionResultScope* outer() const { return outer_; }
 
-  Register NewRegister() { return allocator_.NewRegister(); }
+  Register NewRegister() {
+    ExpressionResultScope* current_scope = generator()->execution_result();
+    if ((current_scope == this) ||
+        (current_scope->outer() == this &&
+         !current_scope->allocator_.hasConsecutiveAllocations())) {
+      // Regular case - Allocating registers in current or outer context.
+      // VisitForRegisterValue, allocates register in outer context.
+      return allocator_.NewRegister();
+    } else {
+      // We need this when allocating registers due to an Assignment hazard.
+      // It might be expensive to walk the full context chain and compute the
+      // list of consecutive reservations in the innerscopes. So allocates a
+      // new unallocated temporary register.
+      return allocator_.AllocateNewRegister();
+    }
+  }
 
   void PrepareForConsecutiveAllocations(size_t count) {
     allocator_.PrepareForConsecutiveAllocations(count);
   }
 
   Register NextConsecutiveRegister() {
     return allocator_.NextConsecutiveRegister();
   }
 
  protected:
@@ skipping 1979 matching lines @@
 }
 
 
 int BytecodeGenerator::feedback_index(FeedbackVectorSlot slot) const {
   return info()->feedback_vector()->GetIndex(slot);
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8