Request for review: 6896617: Optimize sun.nio.cs.ISO_8859_1$Encode.encodeArrayLoop() on x86

[Vitaly Davidovich]

One could write this as:
boolean overflow = false;
if (len > (dl - dp))
{
  overflow = true;
   len = dl - dp;
}

One would hope jit can do this automatically and also CSE away the dl - dp
bit. :)

Sent from my phone
On Jan 9, 2013 7:39 PM, "Vladimir Kozlov" <vladimir.kozlov at oracle.com>
wrote:

> From JIT compiler view current code is better since it has only one
> compare. Your code has two compares: one to calculate "overflow" and an
> other (depended on first) to calculate "len".
>
> Thanks,
> Vladimir
>
> On 1/9/13 3:57 PM, Ulf Zibis wrote:
>
>> Another little simplification:
>>    179             boolean overflow = sr > dr;
>>    180             sr = overflow ? dr : sr;
>> or in your existing logic:
>>   178             int len = sl - sp;
>>   179             boolean overflow = len > (dl - dp);
>>   180             len = overflow ? dl - dp : len;
>> (len is equivalent to sr)
>>
>> -Ulf
>>
>> Am 09.01.2013 19:03, schrieb Vladimir Kozlov:
>>
>>> Ulf,
>>>
>>> Thank you for this suggestion but I would like to keep surrounding
>>> code intact. I will rename "overflowflag" to "overflow". It is used to
>>> indicate that we should return CoderResult.OVERFLOW result.
>>>
>>> Thanks,
>>> Vladimir
>>>
>>> On 1/9/13 3:58 AM, Ulf Zibis wrote:
>>>
>>>> Am 09.01.2013 01:10, schrieb Vitaly Davidovich:
>>>>
>>>>> On Jan 8, 2013 6:18 PM, "Vladimir Kozlov" <vladimir.kozlov at oracle.com>
>>>>> wrote:
>>>>>
>>>>>  http://cr.openjdk.java.net/~****kvn/6896617_jdk/webrev<http://cr.openjdk.java.net/~**kvn/6896617_jdk/webrev>
>>>>>> <http://**cr.openjdk.java.net/~kvn/**6896617_jdk/webrev<http://cr.openjdk.java.net/~kvn/6896617_jdk/webrev>
>>>>>> >
>>>>>>
>>>>>>
>>>>>>
>>>> Another tweak:
>>>>   168             char[] sa = src.array();
>>>>   169             int sp = src.arrayOffset() + src.position();
>>>>   170             int sr = src.remaining();
>>>>   171             int sl = sp + sr;
>>>>   172             assert (sp <= sl); // superfluous, sr is always >= 0
>>>>   173             sp = (sp <= sl ? sp : sl); // superfluous "
>>>>   174             byte[] da = dst.array();
>>>>   175             int dp = dst.arrayOffset() + dst.position();
>>>>   170             int dr = dst.remaining();
>>>>   176             int dl = dp + dr;
>>>>   177             assert (dp <= dl); // superfluous   "
>>>>   178             dp = (dp <= dl ? dp : dl); // superfluous "
>>>>   179             boolean overflow = false;
>>>>   180             if (sr > dr) {
>>>>   181                 sr = dr;
>>>>   182                 overflow = true;
>>>>   183             }
>>>>
>>>> Why you called it "overflowflag", in that way, you could name each
>>>> variable "myvaluevariable" or "myvaluefield" ;-)
>>>>
>>>>
>>>> -Ulf
>>>>
>>>>
>>>
>>
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