Avoid a call to the runtime system when doing binary fp ops on ARM...

src/codegen-ia32.cc

 // Copyright 2006-2009 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 3909 matching lines @@
       frame_->PushElementAt(target.size() - 1);
       Result ignored = frame_->CallRuntime(Runtime::kToSlowProperties, 1);
     }
     if (node->op() == Token::ASSIGN ||
         node->op() == Token::INIT_VAR ||
         node->op() == Token::INIT_CONST) {
       Load(node->value());
 
     } else {
       Literal* literal = node->value()->AsLiteral();
+      bool overwrite_value =
+          (node->value()->AsBinaryOperation() != NULL &&
+           node->value()->AsBinaryOperation()->ResultOverwriteAllowed());
       Variable* right_var = node->value()->AsVariableProxy()->AsVariable();
       // There are two cases where the target is not read in the right hand
       // side, that are easy to test for: the right hand side is a literal,
       // or the right hand side is a different variable.  TakeValue invalidates
       // the target, with an implicit promise that it will be written to again
       // before it is read.
       if (literal != NULL || (right_var != NULL && right_var != var)) {
         target.TakeValue(NOT_INSIDE_TYPEOF);
       } else {
         target.GetValue(NOT_INSIDE_TYPEOF);
       }
       Load(node->value());
-      GenericBinaryOperation(node->binary_op(), node->type());
+      GenericBinaryOperation(node->binary_op(),
+                             node->type(),
+                             overwrite_value ? OVERWRITE_RIGHT : NO_OVERWRITE);
     }
 
     if (var != NULL &&
         var->mode() == Variable::CONST &&
         node->op() != Token::INIT_VAR && node->op() != Token::INIT_CONST) {
       // Assignment ignored - leave the value on the stack.
     } else {
       CodeForSourcePosition(node->position());
       if (node->op() == Token::INIT_CONST) {
         // Dynamic constant initializations must use the function context
@@ skipping 3148 matching lines @@
 
   // Slow-case: Go through the JavaScript implementation.
   __ bind(&slow);
   __ InvokeBuiltin(Builtins::INSTANCE_OF, JUMP_FUNCTION);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal