[interpreter] Reduce size of OSR nesting level field.

src/objects-inl.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.
 //
 // Review notes:
 //
 // - The use of macros in these inline functions may seem superfluous
 // but it is absolutely needed to make sure gcc generates optimal
 // code. gcc is not happy when attempting to inline too deep.
 //
@@ skipping 4081 matching lines @@
 int BytecodeArray::interrupt_budget() const {
   return READ_INT_FIELD(this, kInterruptBudgetOffset);
 }
 
 void BytecodeArray::set_interrupt_budget(int interrupt_budget) {
   DCHECK_GE(interrupt_budget, 0);
   WRITE_INT_FIELD(this, kInterruptBudgetOffset, interrupt_budget);
 }
 
 int BytecodeArray::osr_loop_nesting_level() const {
-  return READ_INT_FIELD(this, kOSRNestingLevelOffset);
+  return READ_INT8_FIELD(this, kOSRNestingLevelOffset);
 }
 
 void BytecodeArray::set_osr_loop_nesting_level(int depth) {
   DCHECK(0 <= depth && depth <= AbstractCode::kMaxLoopNestingMarker);
-  WRITE_INT_FIELD(this, kOSRNestingLevelOffset, depth);
+  STATIC_ASSERT(AbstractCode::kMaxLoopNestingMarker < kMaxInt8);
+  WRITE_INT8_FIELD(this, kOSRNestingLevelOffset, depth);
 }
 
 int BytecodeArray::parameter_count() const {
   // Parameter count is stored as the size on stack of the parameters to allow
   // it to be used directly by generated code.
   return READ_INT_FIELD(this, kParameterSizeOffset) >> kPointerSizeLog2;
 }
 
 
 ACCESSORS(BytecodeArray, constant_pool, FixedArray, kConstantPoolOffset)
@@ skipping 4008 matching lines @@
 #undef WRITE_INT64_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 #undef NOBARRIER_READ_BYTE_FIELD
 #undef NOBARRIER_WRITE_BYTE_FIELD
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_OBJECTS_INL_H_