[jdk15u-dev] RFR: 8253353: Crash in C2: guarantee(n != NULL) failed: No Node

[Olga Mikhaltsova]

I'd like to backport JDK-8253353 to jdk15u for parity with jdk11u. The original patch applies cleanly (see 1st commit).
In spite of simplicity and low risk it contains a bug that was fixed under JDK-8260632. 
The backport for `8260632: Build failures after JDK-8253353` was included as a part of this patch due to dependency. It applies also cleanly (see 2nd commit).
Tested with tier1-3 on Linux x64, Windows x64, macOS x64.

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Commit messages:
 - Backport bc41bb10c77860bcd35b66006c063b4ba865df3d
 - Backport 1926765f5e79bfc8db762823c412cf9769ae28eb

Changes: https://git.openjdk.org/jdk15u-dev/pull/263/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk15u-dev&pr=263&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8253353
  Stats: 1988 lines in 5 files changed: 1986 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk15u-dev/pull/263.diff
  Fetch: git fetch https://git.openjdk.org/jdk15u-dev pull/263/head:pull/263

PR: https://git.openjdk.org/jdk15u-dev/pull/263