RFR: 8335444: Generalize implementation of AndNode mul_ring
Jasmine Karthikeyan
jkarthikeyan at openjdk.org
Mon Jul 8 03:42:01 UTC 2024
Hi all,
I've written this patch which improves type calculation for bitwise-and functions. Previously, the only cases that were considered were if one of the inputs to the node were a positive constant. I've generalized this behavior, as well as added a case to better estimate the result for arbitrary ranges. Since these are very common patterns to see, this can help propagate more precise types throughout the ideal graph for a large number of methods, making other optimizations and analyses stronger. I was interested in where this patch improves types, so I ran CTW for `java_base` and `java_base_2` and printed out the differences in this gist [here](https://gist.github.com/jaskarth/b45260d81ab621656f4a55cc51cf5292). While I don't think it's particularly complicated I've also added some discussion of the mathematics below, mostly because I thought it was interesting to work through :)
This patch passes tier1-3 testing on my linux x64 machine. Thoughts and reviews would be very appreciated!
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Commit messages:
- Improve result of AndNode mul_ring
Changes: https://git.openjdk.org/jdk/pull/20066/files
Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20066&range=00
Issue: https://bugs.openjdk.org/browse/JDK-8335444
Stats: 212 lines in 3 files changed: 168 ins; 34 del; 10 mod
Patch: https://git.openjdk.org/jdk/pull/20066.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/20066/head:pull/20066
PR: https://git.openjdk.org/jdk/pull/20066
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