RFR: 8315066: Add unsigned bounds and known bits to TypeInt/Long [v17]
Quan Anh Mai
qamai at openjdk.org
Tue Sep 10 12:23:28 UTC 2024
> Hi,
>
> This patch adds unsigned bounds and known bits constraints to TypeInt and TypeLong. This opens more transformation opportunities in an elegant manner as well as helps avoid some ad-hoc rules in Hotspot.
>
> In general, a `TypeInt/Long` represents a set of values `x` that satisfies: `x s>= lo && x s<= hi && x u>= ulo && x u<= uhi && (x & zeros) == 0 && (x & ones) == ones`. These constraints are not independent, e.g. an int that lies in [0, 3] in signed domain must also lie in [0, 3] in unsigned domain and have all bits but the last 2 being unset. As a result, we must canonicalize the constraints (tighten the constraints so that they are optimal) before constructing a `TypeInt/Long` instance.
>
> This is extracted from #15440 , node value transformations are left for later PRs. I have also added unit tests to verify the soundness of constraint normalization.
>
> Please kindly review, thanks a lot.
>
> Testing
>
> - [x] GHA
> - [x] Linux x64, tier 1-4
Quan Anh Mai has updated the pull request incrementally with one additional commit since the last revision:
add doc to TypeInt, rename parameters, remove unused methods
-------------
Changes:
- all: https://git.openjdk.org/jdk/pull/17508/files
- new: https://git.openjdk.org/jdk/pull/17508/files/9b70213e..81f4e15b
Webrevs:
- full: https://webrevs.openjdk.org/?repo=jdk&pr=17508&range=16
- incr: https://webrevs.openjdk.org/?repo=jdk&pr=17508&range=15-16
Stats: 135 lines in 4 files changed: 65 ins; 15 del; 55 mod
Patch: https://git.openjdk.org/jdk/pull/17508.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/17508/head:pull/17508
PR: https://git.openjdk.org/jdk/pull/17508
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