RFR:8144771: AVX3 patch for MacroAssembler::string_compare

[Civlin, Jan]

Tobias,

Thank you for spotting this. 
These comments were from the design and reflected the original order str1/str2. I'm removing them since the function calls say enough. 
The order should remain str2/str1 since the "result" is modified in the "str1" line.

Vladimir, 
could you please upload the updated patch (I still do not have an access).


Yes, the test has been run:

[jcivlin at SKY71 test]$ date; echo $JAVA_HOME; ls -l $JAVA_HOME/lib/amd64/server/libjvm.so; time /home/jcivlin/Tools/jtreg/bin/jtreg compiler/intrinsics/string/TestStringIntrinsics.java
Mon Dec  7 11:00:07 PST 2015
/home/jcivlin/Java/mberg-100915-11K/build/linux-x86_64-normal-server-release/jdk
-rwxrwxr-x 1 jcivlin jcivlin 17999532 Dec  2 22:13 /home/jcivlin/Java/mberg-100915-11K/build/linux-x86_64-normal-server-release/jdk/lib/amd64/server/libjvm.so
Test results: passed: 1
Report written to /home/jcivlin/Java/mberg-100915-11K/hotspot/test/JTreport/html/report.html
Results written to /home/jcivlin/Java/mberg-100915-11K/hotspot/test/JTwork

Thank you,

Jan

-----Original Message-----
From: Tobias Hartmann [mailto:tobias.hartmann at oracle.com] 
Sent: Monday, December 07, 2015 6:39 AM
To: Civlin, Jan; hotspot compiler
Cc: Vladimir Kozlov
Subject: Re: RFR:8144771: AVX3 patch for MacroAssembler::string_compare

Hi Jan,

the intrinsic looks good to me (not a reviewer). Here are two minor suggestions:
- The following comments are wrong:
  8355     } else { //ae == StrIntrinsicNode::UL
  8356       load_unsigned_short(cnt1, Address(str2, result, scale2));   // L string
  8357       load_unsigned_byte(result, Address(str1, result, scale1)); // U string
  The first line then loads a UTF16 (two-byte) String and the second line loads a Latin1 (one-byte) String. Maybe you should also exchange the lines to first load str1 and then load str2. I would omit the comment after "else" because ae could either be UL or LU (both have the Latin1 string in str1).
- Missing whitespace after comma:
  8143       cmpl(cnt2,stride2x2);

I assume you executed the hotspot JTREG tests (including /compiler/intrinsics/string/TestStringIntrinsics.java).

Best,
Tobias

On 05.12.2015 05:07, Civlin, Jan wrote:
> We would like to contribute AVX3 patch for MacroAssembler::string_compare.
> 
> This utilizes 512 bits registers on AVX3 architecture and delivers performance gain (speed-up) on long strings at about x 1.33 and on random string about x 1.22. This was measured vs AVX2 (256 bits registers).
> 
> 
> Contributors:
> MacroAssembler::string_compare - Jan Civlin.
> Rest of code, including all x86 AVX3 extensions  - Michael Berg
> 
> 
> Bug-id: https://bugs.openjdk.java.net/browse/JDK-8144771
> Webrev:  http://cr.openjdk.java.net/~kvn/8144771/webrev/
> 
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