RFR: 8347997: assert(false) failed: EA: missing memory path [v3]

[Vladimir Kozlov]

> C2's Escape Analysis does not recognize pattern where one input of memory `Phi` node is `MergeMem` node and an other is RAW store. This pattern is created by Continuation pinning intrinsic. As result EA complains about strange memory graph.
> 
> I suggest to add second `MergeMem` between Store and Phi nodes by calling `reset_memory()`. EA recognize such patter and removes allocations.
> 
> I checked generated assembler pinning code and it is the same as before. The only difference in the test is eliminated allocations.
> 
> I moved Uncommon code up to avoid resetting memory - it is already done at the beginning of this intrinsic code.
> 
> We should not use `uncommon_trap_exact()` for `Deoptimization::Action_none` - It is used for other actions to prevent changing them to `Action_none`.
> 
> Tested tier1-5, hs-xcomp, hs-comp-stress
> Added new regression test based on reproducer from bug report.

Vladimir Kozlov has updated the pull request incrementally with one additional commit since the last revision:

  Update test/hotspot/jtreg/compiler/intrinsics/TestContinuationPinningAndEA.java
  
  Co-authored-by: Tobias Hartmann <tobias.hartmann at oracle.com>

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Changes:
  - all: https://git.openjdk.org/jdk/pull/23284/files
  - new: https://git.openjdk.org/jdk/pull/23284/files/fad42ecb..fee3b721

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23284&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23284&range=01-02

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/23284.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23284/head:pull/23284

PR: https://git.openjdk.org/jdk/pull/23284