MIPS: Cleanup handling of shifts: SHR can deoptimize only when its a shift by 0, all other shift ne…

src/mips/lithium-mips.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 686 matching lines @@
   LOperand* right = NULL;
   int constant_value = 0;
   if (right_value->IsConstant()) {
     HConstant* constant = HConstant::cast(right_value);
     right = chunk_->DefineConstantOperand(constant);
     constant_value = constant->Integer32Value() & 0x1f;
   } else {
     right = UseRegisterAtStart(right_value);
   }
 
+  // Shift operations can only deoptimize if we do a logical shift
+  // by 0 and the result cannot be truncated to int32.
   bool does_deopt = false;
-
-  if (FLAG_opt_safe_uint32_operations) {
-    does_deopt = !instr->CheckFlag(HInstruction::kUint32);
-  } else {
-    // Shift operations can only deoptimize if we do a logical shift
-    // by 0 and the result cannot be truncated to int32.
-    bool may_deopt = (op == Token::SHR && constant_value == 0);
-    if (may_deopt) {
+  if (op == Token::SHR && constant_value == 0) {
+    if (FLAG_opt_safe_uint32_operations) {
+      does_deopt = !instr->CheckFlag(HInstruction::kUint32);
+    } else {
       for (HUseIterator it(instr->uses()); !it.Done(); it.Advance()) {
         if (!it.value()->CheckFlag(HValue::kTruncatingToInt32)) {
           does_deopt = true;
           break;
         }
       }
     }
   }
 
   LInstruction* result =
@@ skipping 1519 matching lines @@
 
 
 LInstruction* LChunkBuilder::DoLoadFieldByIndex(HLoadFieldByIndex* instr) {
   LOperand* object = UseRegister(instr->object());
   LOperand* index = UseRegister(instr->index());
   return DefineAsRegister(new(zone()) LLoadFieldByIndex(object, index));
 }
 
 
 } }  // namespace v8::internal