RFR 8248043: Need to eliminate excessive i2l conversions

[Igor Veresov]

I think you forgot to include changes to BoolNode in the webrev.

igor



> On Jun 30, 2020, at 11:04 AM, Boris Ulasevich <boris.ulasevich at bell-sw.com> wrote:
> 
> Hi Claes,
> 
> > Seems like the optimization is mostly effective, but not getting all the way.
> 
> Good point about LHS, thanks! CmpL turned to be not canonized on the moment.
> I moved the optimization to CmpLNode::Ideal and transformations now works as follows:
> 1. CmpINode::Ideal: CmpI(CmpL3)->CmpL
> 2. BoolNode::Ideal: Bool(CmpL(const,val),test)->Bool(CmpL(val,const),test_invert)
> 3. CmpLNode::Ideal: CmpL(ConvI2L(val),ConL)->CmpI(val,ConI)
> 
> I applied your test to the benchmark. The result is:
> Benchmark                            Mode  Cnt   Score   Error Units
> SkipIntToLongCast.skipCastTestLeft   avgt    5  14.288 ± 0.052 ns/op
> SkipIntToLongCast.skipCastTestRight  avgt    5  14.338 ± 0.088 ns/op
> 
> Updated webrev:
> http://cr.openjdk.java.net/~bulasevich/8248043/webrev.02b
> 
> thanks,
> Boris
> 
> On 26.06.2020 21:31, Claes Redestad wrote:
>> Hi Boris,
>> 
>> this looks like a nice improvement! I just have some comments about the
>> micro.
>> 
>> I was curious whether the optimization works when the constant is on
>> the LHS and added a variant of the micro to try that[1]. Results are
>> interesting (Intel Xeon):
>> 
>> Benchmark                            Mode  Cnt   Score   Error Units
>> SkipIntToLongCast.skipCastTest       avgt    5  30.937 ± 0.056 ns/op
>> SkipIntToLongCast.skipCastTestLeft   avgt    5  30.937 ± 0.140 ns/op
>> 
>> With your patch:
>> Benchmark                            Mode  Cnt   Score   Error Units
>> SkipIntToLongCast.skipCastTest       avgt    5  14.123 ± 0.035 ns/op
>> SkipIntToLongCast.skipCastTestLeft   avgt    5  17.420 ± 0.044 ns/op
>> 
>> Seems like the optimization is mostly effective, but not getting all
>> the way. I wouldn't worry about it for this RFE, but perhaps something
>> to investigate in a follow-up. Feel free to include such a variant in
>> your patch though (no attribution necessary).
>> 
>> The micro also stabilizes very quickly, so you might want to provide
>> some default tuning to keep runtime in check, e.g., something like:
>> 
>> @Warmup(iterations = 10, time = 500, timeUnit = TimeUnit.MILLISECONDS)
>> @Measurement(iterations = 5, time = 1000, timeUnit = TimeUnit.MILLISECONDS)
>> @Fork(3)
>> 
>> Thanks!
>> 
>> /Claes
>> 
>> [1]
>>     @Benchmark
>>     public int skipCastTestLeft() {
>>         for (int i = 0; i < ARRAYSIZE_L; i++) {
>>             if (ARRAYSIZE_L == intValues[i]) {
>>                 return i;
>>             }
>>         }
>>         return 0;
>>     }
>> 
>> On 2020-06-26 17:05, Boris Ulasevich wrote:
>>> Hi all,
>>> 
>>> Please review the change to eliminate the unnecessary i2l conversion
>>> for expressions like this: "if (intValue == 1L)".
>>> 
>>> http://bugs.openjdk.java.net/browse/JDK-8248043
>>> http://cr.openjdk.java.net/~bulasevich/8248043/webrev.01
>>> 
>>> The provided benchmark shows performance boost on all platforms:
>>> - Intel Xeon: 32.705 --> 14.234 ns/op
>>> - arm64: 42.060 --> 25.456 ns/op
>>> - arm32: 618.763 --> 314.040 ns/op
>>> - ppc8:  81.218 --> 63.026 ns/op
>>> 
>>> Testing done: jtreg, jck.
>>> 
>>> thanks,
>>> Boris
>