RFR: 8303627: compiler/loopopts/TestUnreachableInnerLoop.java failed with -XX:LoopMaxUnroll=4

[SUN Guoyun]

This test failed with VM_OPTIONS=-XX:LoopMaxUnroll=4 and CONF=fastdebug on X86_64, AArch64 LoongArch64 architecture.

<pre><code class="shell">
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/home/sunguoyun/jdk-ls/src/hotspot/share/opto/block.cpp:1359), pid=31328, tid=31344
# assert(n->is_Root() || n->is_Region() || n->is_Phi() || n->is_MachMerge() || def_block->dominates(block)) failed: uses must be dominated by definitions
#
</code></pre>
This PR fix the issue, Please help review it.

Thanks.

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

Commit messages:
 - 8303627: compiler/loopopts/TestUnreachableInnerLoop.java failed with -XX:LoopMaxUnroll=4

Changes: https://git.openjdk.org/jdk/pull/12874/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12874&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8303627
  Stats: 17 lines in 2 files changed: 14 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/12874.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12874/head:pull/12874

PR: https://git.openjdk.org/jdk/pull/12874