aarch64: C2 OSR compilation fails with "shouldn't process one node several times" in final graph reshaping

(synopsis is provisional, please change as you see fit)

Found with fuzzing. Reliably reproduces on aarch64, but not on x86_64, although it is probably not architecture-specific.
Test bundle is attached, along with sample hs_errs.

$ ~/jdk-jdk/build/linux-aarch64-server-fastdebug/images/jdk/bin/java Test

# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/home/shade/jdk-jdk/src/hotspot/share/opto/compile.cpp:3489), pid=3503, tid=3514
# assert(!wq.contains(u)) failed: shouldn't process one node several times
#
# JRE version: OpenJDK Runtime Environment (14.0) (fastdebug build 14-internal+0-adhoc.shade.jdk-jdk)
# Java VM: OpenJDK 64-Bit Server VM (fastdebug 14-internal+0-adhoc.shade.jdk-jdk, mixed mode, sharing, tiered, compressed oops, g1 gc, linux-aarch64)
# Problematic frame:
# V [libjvm.so+0x7a0f58] Compile::final_graph_reshaping_main_switch(Node*, Final_Reshape_Counts&, unsigned int)+0x1268
#
# Core dump will be written. Default location: Core dumps may be processed with "/usr/libexec/abrt-hook-ccpp %s %c %p %u %g %t e %P %I %h" (or dumping to /home/shade/tests/05015/core.3503)
#
# If you would like to submit a bug report, please visit:
# http://bugreport.java.com/bugreport/crash.jsp
#

--------------- S U M M A R Y ------------

Command Line: Test

Host: merino.lab2.eng.bos.redhat.com, AArch64, 46 cores, 95G, Red Hat Enterprise Linux Server release 7.6 (Maipo)
Time: Wed Aug 14 06:39:26 2019 EDT elapsed time: 1 seconds (0d 0h 0m 1s)

--------------- T H R E A D ---------------

Current thread (0x0000ffff905ab000): JavaThread "C2 CompilerThread0" daemon [_thread_in_native, id=3514, stack(0x0000ffff2cf90000,0x0000ffff2d190000)]


Current CompileTask:
C2: 1335 88 % ! 4 Test::vMeth @ 72 (368 bytes)

Stack: [0x0000ffff2cf90000,0x0000ffff2d190000], sp=0x0000ffff2d18aae0, free space=2026k
Native frames: (J=compiled Java code, A=aot compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x7a0f58] Compile::final_graph_reshaping_main_switch(Node*, Final_Reshape_Counts&, unsigned int)+0x1268
V [libjvm.so+0x7a1d04] Compile::final_graph_reshaping_impl(Node*, Final_Reshape_Counts&)+0x1a4
V [libjvm.so+0x7a227c] Compile::final_graph_reshaping_walk(Node_Stack&, Node*, Final_Reshape_Counts&)+0xcc
V [libjvm.so+0x7abc40] Compile::final_graph_reshaping()+0x3f8
V [libjvm.so+0x7adee4] Compile::Optimize()+0xdfc
V [libjvm.so+0x7af014] Compile::Compile(ciEnv*, C2Compiler*, ciMethod*, int, bool, bool, bool, DirectiveSet*)+0x10a0
V [libjvm.so+0x61d428] C2Compiler::compile_method(ciEnv*, ciMethod*, int, DirectiveSet*)+0x114