[interpreter] Reduce size of OSR nesting level field.

src/interpreter/interpreter-assembler.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/interpreter-assembler.h"
 
 #include <limits>
 #include <ostream>
 
 #include "src/code-factory.h"
@@ skipping 830 matching lines @@
   Node* sp = LoadStackPointer();
   Node* stack_limit = Load(
       MachineType::Pointer(),
       ExternalConstant(ExternalReference::address_of_stack_limit(isolate())));
   return UintPtrLessThan(sp, stack_limit);
 }
 
 Node* InterpreterAssembler::LoadOSRNestingLevel() {
   Node* offset =
       IntPtrConstant(BytecodeArray::kOSRNestingLevelOffset - kHeapObjectTag);
-  return Load(MachineType::Int32(), BytecodeArrayTaggedPointer(), offset);
+  return Load(MachineType::Int8(), BytecodeArrayTaggedPointer(), offset);
 }
 
 void InterpreterAssembler::Abort(BailoutReason bailout_reason) {
   disable_stack_check_across_call_ = true;
   Node* abort_id = SmiTag(Int32Constant(bailout_reason));
   CallRuntime(Runtime::kAbort, GetContext(), abort_id);
   disable_stack_check_across_call_ = false;
 }
 
 void InterpreterAssembler::AbortIfWordNotEqual(Node* lhs, Node* rhs,
@@ skipping 130 matching lines @@
     Goto(&loop);
   }
   Bind(&done_loop);
 
   return array;
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8