RFR: 8361702: C2: assert(is_dominator(compute_early_ctrl(limit, limit_ctrl), pre_end)) failed: node pinned on loop exit test? [v4]

[Roland Westrelin]

> A node in a pre loop only has uses out of the loop dominated by the
> loop exit. `PhaseIdealLoop::try_sink_out_of_loop()` sets its control
> to the loop exit projection. A range check in the main loop has this
> node as input (through a chain of some other nodes). Range check
> elimination needs to update the exit condition of the pre loop with an
> expression that depends on the node pinned on its exit: that's
> impossible and the assert fires. This is a variant of 8314024 (this
> one was for a node with uses out of the pre loop on multiple paths). I
> propose the same fix: leave the node with control in the pre loop in
> this case.

Roland Westrelin has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains eight additional commits since the last revision:

 - Merge branch 'master' into JDK-8361702
 - Update src/hotspot/share/opto/loopopts.cpp
   
   Co-authored-by: Christian Hagedorn <christian.hagedorn at oracle.com>
 - Update test/hotspot/jtreg/compiler/rangechecks/TestSunkRangeFromPreLoopRCE3.java
   
   Co-authored-by: Christian Hagedorn <christian.hagedorn at oracle.com>
 - Update test/hotspot/jtreg/compiler/rangechecks/TestSunkRangeFromPreLoopRCE2.java
   
   Co-authored-by: Christian Hagedorn <christian.hagedorn at oracle.com>
 - Update src/hotspot/share/opto/loopopts.cpp
   
   Co-authored-by: Christian Hagedorn <christian.hagedorn at oracle.com>
 - Update test/hotspot/jtreg/compiler/rangechecks/TestSunkRangeFromPreLoopRCE2.java
   
   Co-authored-by: Christian Hagedorn <christian.hagedorn at oracle.com>
 - tests
 - fix

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/26424/files
  - new: https://git.openjdk.org/jdk/pull/26424/files/1b658c4b..cc64aa6f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=26424&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=26424&range=02-03

  Stats: 59316 lines in 1541 files changed: 32800 ins; 20025 del; 6491 mod
  Patch: https://git.openjdk.org/jdk/pull/26424.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26424/head:pull/26424

PR: https://git.openjdk.org/jdk/pull/26424