RFR: 8373508: C2: sinking CreateEx out of loop breaks the graph [v2]

[Roland Westrelin]

> A `CreateEx` gets sunk out of loop by
> `PhaseIdealLoop::try_sink_out_of_loop()` and, as a consequence, the
> following logic:
> 
> 
>   return (in(0)->is_CatchProj() && in(0)->in(0)->is_Catch() &&
>           in(0)->in(0)->in(1) == in(1)) ? this : call->in(TypeFunc::Parms);
> 
> 
> in `CreateExNode::Identity()` triggers which leads to the crash
> because `call->in(TypeFunc::Parms)` is not even an object in this
> particular case.
> 
> It's actually not clear to me what that logic in
> `CreateExNode::Identity()` is expected to do and I wonder if it's
> still needed.
> 
> Anyway, the fix I propose is to skip `CreateEx` in
> `PhaseIdealLoop::try_sink_out_of_loop()`.

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

  Update test/hotspot/jtreg/compiler/loopopts/TestCreateExSunkOutOfLoop.java
  
  Co-authored-by: Christian Hagedorn <christian.hagedorn at oracle.com>

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/28842/files
  - new: https://git.openjdk.org/jdk/pull/28842/files/45097770..e4bdff59

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=28842&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=28842&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/28842.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28842/head:pull/28842

PR: https://git.openjdk.org/jdk/pull/28842