C2: Deoptimization during vector box construction is broken

A lot of jdk/incubator/vector tests either fail with following exception

 java.lang.ClassCastException: class [B cannot be cast to class jdk.incubator.vector.ByteVector ([B is in module java.base of loader 'bootstrap'; jdk.incubator.vector.ByteVector is in module jdk.incubator.vector of loader 'bootstrap')
at jdk.incubator.vector/jdk.incubator.vector.ByteVector.fromArray0Template(ByteVector.java:3165)
at jdk.incubator.vector/jdk.incubator.vector.Byte128Vector.fromArray0(Byte128Vector.java:805)
at jdk.incubator.vector/jdk.incubator.vector.ByteVector.fromArray(ByteVector.java:2699)
at VectorReshapeTests.testVectorCastByteToLong(VectorReshapeTests.java:1863)
at VectorReshapeTests.testCastFromByte(VectorReshapeTests.java:2415)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)



or crash with
# SIGSEGV (0xb) at pc=0x00007f35607ec0df, pid=21765, tid=21786
#
# JRE version: Java(TM) SE Runtime Environment (16.0) (fastdebug build 16-internal+0-2020-10-23-2105515.katya...)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 16-internal+0-2020-10-23-2105515.katya..., mixed mode, sharing, compressed oops, g1 gc, linux-amd64)
# Problematic frame:
# J 2432 c2 jdk.incubator.vector.IntVector.toArray()Ljava/lang/Object; jdk.incubator.vector@16-internal (5 bytes) @ 0x00007f35607ec0df [0x00007f35607ec040+0x000000000000009f]

when running with -XX:+DeoptimizeALot flag.


To reproduce crash run for example:
> jtreg -J-Xms64M -J-Xmx1600M -J-XX:ThreadStackSize=1536 -timeoutFactor:10
 -jdk:TESTED_JDK
 -vmoptions:"-XX:+CreateCoredumpOnCrash -ea -esa -XX:CompileThreshold=100 -XX:+UnlockExperimentalVMOptions -XX:+DeoptimizeALot"
 -dir:open/test/jdk jdk/incubator/vector/VectorMaxConversionTests.java