RFR: 8349361: C2: RShiftL should support all applicable transformations that RShiftI does [v9]

[Roland Westrelin]

On Mon, 24 Feb 2025 15:46:45 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> Roland Westrelin has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 15 additional commits since the last revision:
>> 
>>  - review
>>  - review
>>  - review
>>  - Merge branch 'master' into JDK-8349361
>>  - Update src/hotspot/share/opto/mulnode.cpp
>>    
>>    Co-authored-by: Emanuel Peter <emanuel.peter at oracle.com>
>>  - Update src/hotspot/share/opto/mulnode.cpp
>>    
>>    Co-authored-by: Emanuel Peter <emanuel.peter at oracle.com>
>>  - review
>>  - Update src/hotspot/share/opto/mulnode.hpp
>>    
>>    Co-authored-by: Jasmine Karthikeyan <25208576+jaskarth at users.noreply.github.com>
>>  - Update src/hotspot/share/opto/mulnode.cpp
>>    
>>    Co-authored-by: Jasmine Karthikeyan <25208576+jaskarth at users.noreply.github.com>
>>  - Update src/hotspot/share/opto/mulnode.cpp
>>    
>>    Co-authored-by: Jasmine Karthikeyan <25208576+jaskarth at users.noreply.github.com>
>>  - ... and 5 more: https://git.openjdk.org/jdk/compare/5d94f680...5b05d222
>
> test/hotspot/jtreg/compiler/c2/irTests/RShiftLNodeIdealizationTests.java line 125:
> 
>> 123:     final static int test7Shift = RunInfo.getRandom().nextInt(32) + 32;
>> 124:     final static long test7Min = -1L << (64 - test7Shift -1);
>> 125:     final static long test7Max = ~test7Min;
> 
> Would you mind adding a quick comment about why you chose the values the way you do?

Added in new commit.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23438#discussion_r1973984640