RFR: 8302673: [SuperWord] MaxReduction and MinReduction should vectorize for int

[Roberto Castañeda Lozano]

The canonicalization of MinI/MaxI chains into right-spline graphs within `MinINode/MaxINode::Ideal()` inhibits the vectorization of reductions of these nodes. This changeset reworks `MinINode/MaxINode::Ideal()` to perform the same algebraic optimizations without the need for canonicalization, re-enabling auto-vectorization of MinI/MaxI reductions. This is achieved by handling all four permutations of the targeted Ideal subgraph induced by the commutativity of MinI/MaxI directly. The algorithm (for the MaxI case, the MinI case is analogous) tries to apply two Ideal graph rewrites in the following order, where `c0` and `c1` are constants and `MAX` is a compile-time operation:
1. `max(x + c0, max(x + c1, z))` (or a permutation of it) to `max(x + MAX(c0, c1), z)`.
2. `max(x + c0, x + c1)` (or a permutation of it) to `x + MAX(c0, c1)`.

Here is an example of the four permutations handled in step 1 with `x = RShiftI`, `c0 = 100` or `150`, `c1 = 150` or `100`, and `z = ConI (#int:200)`:

![two-level-idealization](https://github.com/openjdk/jdk/assets/8792647/bf60a2c3-39cd-4f0d-965d-c711723e374c)

Here is an example of the two permutations handled in step 2 with `x = RShiftI`, `c0 = 10` or `11`, and `c1 = 11` or `10`:

![one-level-idealization](https://github.com/openjdk/jdk/assets/8792647/0a1fe85b-3f30-46bc-8817-d90b3eff946c)

The changeset implements `MinINode/MaxINode::Ideal()` in a common method `MaxNode::IdealI()`, since the algorithm is symmetric for both node types. The changeset also extends the existing MinI/MaxI Idealization tests with positive tests for all targeted permutations and negative tests, and adds a new test (contributed by @jbhateja) to assert that MinI/MaxI reductions are vectorized.

#### Testing

##### Functionality

- tier1-5, stress test, fuzzing (windows-x64, linux-x64, linux-aarch64, macosx-x64, macosx-aarch64; release and debug mode).

##### Performance

- Tested performance on a set of standard benchmark suites (DaCapo, SPECjbb2015, SPECjvm2008). No significant change was observed.

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Commit messages:
 - Refine comments
 - Update copyright header
 - Uncomment tests
 - Complement idealization tests with negative ones
 - Add some comments
 - Refactor
 - Simplify
 - Re-add comment
 - Flatten nested if
 - Extract MaxINode::Ideal() and MinINode::Ideal() into MaxNode::IdealI()
 - ... and 4 more: https://git.openjdk.org/jdk/compare/8ac71863...9fd482b5

Changes: https://git.openjdk.org/jdk/pull/13924/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13924&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8302673
  Stats: 424 lines in 5 files changed: 266 ins; 103 del; 55 mod
  Patch: https://git.openjdk.org/jdk/pull/13924.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13924/head:pull/13924

PR: https://git.openjdk.org/jdk/pull/13924