RFR: 8318723: RISC-V: C2 UDivL [v3]

[Fei Yang]

On Thu, 26 Oct 2023 10:13:46 GMT, Hamlin Li <mli at openjdk.org> wrote:

>> Hi,
>> Can you review the change to add intrinsic for UDivI and UDivL?
>> Thanks!
>> 
>> 
>> ## Tests
>> 
>> ### Functionality
>> Run tests successfully found via `grep -nr test/jdk/ -we divideUnsigned` and `grep -nr test/hotspot/ -we divideUnsigned` 
>> 
>> ### Performance
>> ( NOTE: there are another 2 related issues: https://bugs.openjdk.org/browse/JDK-8318225, https://bugs.openjdk.org/browse/JDK-8318226, the pr of which will be subseqently sent out after this one finished. )
>> 
>> #### Long
>> **NOTE: for positive divisor, it's the common case; for negative divisor, it's a rare case**
>> 
>> **Before**
>> 
>> LongDivMod.testDivideUnsigned                    1024          mixed  avgt   10  19684.873 ± 21.882  ns/op
>> LongDivMod.testDivideUnsigned                    1024       positive  avgt   10  28853.041 ±  6.425  ns/op
>> LongDivMod.testDivideUnsigned                    1024       negative  avgt   10   6367.239 ± 16.011  ns/op
>> 
>> 
>> **After**
>> 
>> LongDivMod.testDivideUnsigned                    1024          mixed  avgt   10  22622.133 ±  7.158  ns/op
>> LongDivMod.testDivideUnsigned                    1024       positive  avgt   10  15957.272 ±  3.174  ns/op
>> LongDivMod.testDivideUnsigned                    1024       negative  avgt   10  29499.721 ± 10.404  ns/op
>> 
>> 
>> #### Integer
>> **Before**
>> 
>> IntegerDivMod.testDivideUnsigned                    1024          mixed  avgt   10  23397.267 ± 36.980  ns/op
>> IntegerDivMod.testDivideUnsigned                    1024       positive  avgt   10  16792.414 ±  5.869  ns/op
>> IntegerDivMod.testDivideUnsigned                    1024       negative  avgt   10  30184.357 ± 55.464  ns/op
>> 
>> 
>> **After**
>> 
>> IntegerDivMod.testDivideUnsigned                    1024          mixed  avgt   10  23210.437 ±  4.463  ns/op
>> IntegerDivMod.testDivideUnsigned                    1024       positive  avgt   10  16622.342 ±  4.047  ns/op
>> IntegerDivMod.testDivideUnsigned                    1024       negative  avgt   10  30013.414 ± 48.695  ns/op
>> 
>> 
>> 
>> /************ following is just backup: quick path for negative divisor *************/
>> #### Long
>> **Before**
>> 
>> LongDivMod.testDivideUnsigned                    1024          mixed  avgt   10  19704.317 ± 64.078  ns/op
>> LongDivMod.testDivideUnsigned                    1024       positive  avgt   10  28856.859 ± 14.901  ns/op
>> LongDivMod.testDivideUnsigned                    1024       negative  avgt   10   6364.974 ±  2.465  ns/op
>> 
>> 
>> **After v1**
>> (This is a simp...
>
> Hamlin Li has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix format for UdivL

Updated change LGTM.

-------------

Marked as reviewed by fyang (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/16346#pullrequestreview-1699887036