RFR: 8315066: Add unsigned bounds and known bits to TypeInt/Long [v2]
Quan Anh Mai
qamai at openjdk.org
Mon Aug 28 15:37:53 UTC 2023
> 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. The new constraints are applied to identity and value calls of the common nodes (Add, Sub, L/R/URShift, And, Or, Xor, bit counting, Cmp, Bool, ConvI2L/L2I), the detailed ideas for each node will be presented below.
>
> 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) == 0`. 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 normalize the constraints (tighten the constraints so that they are optimal) before constructing a `TypeInt/Long` instance.
>
> Please kindly review, thanks very much.
>
> 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:
typo
-------------
Changes:
- all: https://git.openjdk.org/jdk/pull/15440/files
- new: https://git.openjdk.org/jdk/pull/15440/files/5fc5cf3a..ae7cc260
Webrevs:
- full: https://webrevs.openjdk.org/?repo=jdk&pr=15440&range=01
- incr: https://webrevs.openjdk.org/?repo=jdk&pr=15440&range=00-01
Stats: 4 lines in 1 file changed: 0 ins; 3 del; 1 mod
Patch: https://git.openjdk.org/jdk/pull/15440.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/15440/head:pull/15440
PR: https://git.openjdk.org/jdk/pull/15440
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