Do not transform a/b into a * (1/b) in the parser for integer constants....

src/parser.cc

 // Copyright 2010 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 2305 matching lines @@
             uint32_t shift = DoubleToInt32(y_val) & 0x1f;
             int value = ArithmeticShiftRight(DoubleToInt32(x_val), shift);
             x = NewNumberLiteral(value);
             continue;
           }
           default:
             break;
         }
       }
 
-      // Convert constant divisions to multiplications for speed.
-      if (op == Token::DIV &&
-          y && y->AsLiteral() && y->AsLiteral()->handle()->IsNumber()) {
-        double y_val = y->AsLiteral()->handle()->Number();
-        int64_t y_int = static_cast<int64_t>(y_val);
-        // There are rounding issues with this optimization, but they don't
-        // apply if the number to be divided with has a reciprocal that can be
-        // precisely represented as a floating point number.  This is the case
-        // if the number is an integer power of 2.  Negative integer powers of
-        // 2 work too, but for -2, -1, 1 and 2 we don't do the strength
-        // reduction because the inlined optimistic idiv has a reasonable
-        // chance of succeeding by producing a Smi answer with no remainder.
-        if (static_cast<double>(y_int) == y_val &&
-            (IsPowerOf2(y_int) || IsPowerOf2(-y_int)) &&
-            (y_int > 2 || y_int < -2)) {
-          y = NewNumberLiteral(1 / y_val);
-          op = Token::MUL;
-        }
-      }
-
       // For now we distinguish between comparisons and other binary
       // operations.  (We could combine the two and get rid of this
       // code and AST node eventually.)
       if (Token::IsCompareOp(op)) {
         // We have a comparison.
         Token::Value cmp = op;
         switch (op) {
           case Token::NE: cmp = Token::EQ; break;
           case Token::NE_STRICT: cmp = Token::EQ_STRICT; break;
           default: break;
@@ skipping 2352 matching lines @@
       Handle<String> source = Handle<String>(String::cast(script->source()));
       result = parser.ParseProgram(source, info->is_global());
     }
   }
 
   info->SetFunction(result);
   return (result != NULL);
 }
 
 } }  // namespace v8::internal