RFR: 8334647: C2: CastII added by PhaseIdealLoop::add_template_assertion_predicate() should have control [v2]

[Roland Westrelin]

> `PhaseIdealLoop::add_template_assertion_predicate()` creates a new
> `CastII` but doesn't set its control. I think it's good practice to
> always set the control of a `CastII` when it narrows the type of its
> input (it has to be control dependent on some condition that makes the
> narrowing possible). This is also motivated by
> https://bugs.openjdk.org/browse/JDK-8275202 where a node that becomes
> top is used as an indication that control flow where the node changes
> type can constant fold. This only works if control is set correctly.

Roland Westrelin has updated the pull request incrementally with one additional commit since the last revision:

  review

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/19808/files
  - new: https://git.openjdk.org/jdk/pull/19808/files/b05cf955..b22ba3f7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19808&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19808&range=00-01

  Stats: 11 lines in 3 files changed: 2 ins; 6 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/19808.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19808/head:pull/19808

PR: https://git.openjdk.org/jdk/pull/19808