Remove FLAG_opt_safe_uint32_operations.

src/x64/lithium-x64.cc

 // 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.
 
 #include <sstream>
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_X64
 
@@ skipping 704 matching lines @@
         // cannot be truncated to smi.
         does_deopt = !instr->CheckUsesForFlag(HValue::kTruncatingToSmi);
       }
     } else {
       right = UseFixed(right_value, rcx);
     }
 
     // Shift operations can only deoptimize if we do a logical shift by 0 and
     // the result cannot be truncated to int32.
     if (op == Token::SHR && constant_value == 0) {
-      if (FLAG_opt_safe_uint32_operations) {
-        does_deopt = !instr->CheckFlag(HInstruction::kUint32);
-      } else {
-        does_deopt = !instr->CheckUsesForFlag(HValue::kTruncatingToInt32);
-      }
+      does_deopt = !instr->CheckFlag(HInstruction::kUint32);
     }
 
     LInstruction* result =
         DefineSameAsFirst(new(zone()) LShiftI(op, left, right, does_deopt));
     return does_deopt ? AssignEnvironment(result) : result;
   } else {
     return DoArithmeticT(op, instr);
   }
 }
 
@@ skipping 1946 matching lines @@
   LOperand* function = UseRegisterAtStart(instr->function());
   LAllocateBlockContext* result =
       new(zone()) LAllocateBlockContext(context, function);
   return MarkAsCall(DefineFixed(result, rsi), instr);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64