Shenandoah: Fix register clash in SBSA::resolve_forwarding_pointer() borrowing

$ ~/trunks/jdk-jdk/build/linux-x86_64-server-fastdebug/images/jdk/bin/java -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -Xmx8g -XX:ShenandoahGCHeuristics=compact -jar ~/Downloads/renaissance-gpl-0.10.0.jar finagle-http
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by com.twitter.jvm.Hotspot (file:/home/shade/temp/renaissance/./tmp-jars-2716329772267256121/cp-util-jvm_2.11-19.4.0.jar1132306962165764229.jar) to field sun.management.ManagementFactoryHelper.jvm
WARNING: Please consider reporting this to the maintainers of com.twitter.jvm.Hotspot
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
Sep 27, 2019 4:41:56 PM com.twitter.finagle.Init$$anonfun$6 apply$mcV$sp
INFO: Finagle version 19.4.0 (rev=15ae0aba979a2c11ed4a71774b2e995f5df918b4) built at 20190418-114039
finagle-http on :42797 spawning 16 client and default number of server workers.
====== finagle-http (twitter-finagle), iteration 0 started ======
====== finagle-http (twitter-finagle), iteration 0 completed (12029.205 ms) ======
====== finagle-http (twitter-finagle), iteration 1 started ======
Exception in thread "finagle-http-worker-6" com.twitter.finagle.ChannelClosedException: syscall:read(..) failed: Connection reset by peer at remote address: localhost/127.0.0.1:42797 from service: localhost:42797. Remote Info: Upstream Address: Not Available, Upstream id: Not Available, Downstream Address: localhost/127.0.0.1:42797, Downstream label: localhost:42797, Trace Id: 69d79c1cdc3dfe27.69d79c1cdc3dfe27<:69d79c1cdc3dfe27
at com.twitter.finagle.ChannelException$.apply(Exceptions.scala:272)
at com.twitter.finagle.netty4.transport.ChannelTransport$$anon$2.exceptionCaught(ChannelTransport.scala:179)
at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:285)
at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:264)
at io.netty.channel.AbstractChannelHandlerContext.fireExceptionCaught(AbstractChannelHandlerContext.java:256)
at io.netty.channel.ChannelInboundHandlerAdapter.exceptionCaught(ChannelInboundHandlerAdapter.java:131)
at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:285)
at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:264)
at io.netty.channel.AbstractChannelHandlerContext.fireExceptionCaught(AbstractChannelHandlerContext.java:256)
at com.twitter.finagle.netty4.http.handler.ClientExceptionMapper$.exceptionCaught(ClientExceptionMapper.scala:40)
at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:285)
at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:264)
at io.netty.channel.AbstractChannelHandlerContext.fireExceptionCaught(AbstractChannelHandlerContext.java:256)
at io.netty.channel.ChannelInboundHandlerAdapter.exceptionCaught(ChannelInboundHandlerAdapter.java:131)
at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:285)
at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:264)
at io.netty.channel.AbstractChannelHandlerContext.fireExceptionCaught(AbstractChannelHandlerContext.java:256)
at io.netty.channel.ChannelInboundHandlerAdapter.exceptionCaught(ChannelInboundHandlerAdapter.java:131)
at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:285)
at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:264)
at io.netty.channel.AbstractChannelHandlerContext.fireExceptionCaught(AbstractChannelHandlerContext.java:256)
at io.netty.channel.ChannelInboundHandlerAdapter.exceptionCaught(ChannelInboundHandlerAdapter.java:131)
at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:285)
at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:264)
at io.netty.channel.AbstractChannelHandlerContext.fireExceptionCaught(AbstractChannelHandlerContext.java:256)
at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireExceptionCaught(CombinedChannelDuplexHandler.java:426)
at io.netty.channel.ChannelHandlerAdapter.exceptionCaught(ChannelHandlerAdapter.java:87)
at io.netty.channel.CombinedChannelDuplexHandler$1.fireExceptionCaught(CombinedChannelDuplexHandler.java:147)
at io.netty.channel.ChannelInboundHandlerAdapter.exceptionCaught(ChannelInboundHandlerAdapter.java:131)
at io.netty.channel.CombinedChannelDuplexHandler.exceptionCaught(CombinedChannelDuplexHandler.java:233)
at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:285)
at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:264)
at io.netty.channel.AbstractChannelHandlerContext.fireExceptionCaught(AbstractChannelHandlerContext.java:256)
at io.netty.channel.ChannelInboundHandlerAdapter.exceptionCaught(ChannelInboundHandlerAdapter.java:131)
at com.twitter.finagle.netty4.channel.ChannelExceptionHandler.exceptionCaught(ChannelExceptionHandler.scala:69)
at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:285)
at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:264)
at io.netty.channel.AbstractChannelHandlerContext.fireExceptionCaught(AbstractChannelHandlerContext.java:256)
at io.netty.channel.ChannelInboundHandlerAdapter.exceptionCaught(ChannelInboundHandlerAdapter.java:131)
at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:285)
at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:264)
at io.netty.channel.AbstractChannelHandlerContext.fireExceptionCaught(AbstractChannelHandlerContext.java:256)
at io.netty.channel.ChannelInboundHandlerAdapter.exceptionCaught(ChannelInboundHandlerAdapter.java:131)
at com.twitter.finagle.netty4.channel.ChannelStatsHandler.exceptionCaught(ChannelStatsHandler.scala:210)
at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:285)
at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:264)
at io.netty.channel.AbstractChannelHandlerContext.fireExceptionCaught(AbstractChannelHandlerContext.java:256)
at io.netty.channel.DefaultChannelPipeline$HeadContext.exceptionCaught(DefaultChannelPipeline.java:1401)
at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:285)
at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:264)
at io.netty.channel.DefaultChannelPipeline.fireExceptionCaught(DefaultChannelPipeline.java:953)
at io.netty.channel.epoll.AbstractEpollStreamChannel$EpollStreamUnsafe.handleReadException(AbstractEpollStreamChannel.java:736)
at io.netty.channel.epoll.AbstractEpollStreamChannel$EpollStreamUnsafe.epollInReady(AbstractEpollStreamChannel.java:825)
at io.netty.channel.epoll.EpollEventLoop.processReady(EpollEventLoop.java:433)
at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:330)
at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:897)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at com.twitter.finagle.util.BlockingTimeTrackingThreadFactory$$anon$1.run(BlockingTimeTrackingThreadFactory.scala:23)
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
at java.base/java.lang.Thread.run(Thread.java:830)
Caused by: io.netty.channel.unix.Errors$NativeIoException: syscall:read(..) failed: Connection reset by peer
at io.netty.channel.unix.FileDescriptor.readAddress(..)(Unknown Source)
Exception occurred in org.renaissance.twitter.finagle.FinagleHttp@5de5e95: total request length: expected 5184000 but got 4875525
org.renaissance.ValidationException: total request length: expected 5184000 but got 4875525
at org.renaissance.ValidationException.throwIfNotEqual(ValidationException.java:42)
at org.renaissance.SimpleResult.validate(SimpleResult.java:39)
at org.renaissance.RenaissanceBenchmark.runIterationWithBeforeAndAfter(RenaissanceBenchmark.java:143)
at org.renaissance.FixedIterationsPolicy.execute(FixedIterationsPolicy.java:48)
at org.renaissance.RenaissanceBenchmark.runBenchmark(RenaissanceBenchmark.java:91)
at org.renaissance.RenaissanceSuite$.$anonfun$main$2(renaissance-suite.scala:298)
at org.renaissance.RenaissanceSuite$.$anonfun$main$2$adapted(renaissance-suite.scala:296)
at scala.collection.mutable.ResizableArray.foreach(ResizableArray.scala:62)
at scala.collection.mutable.ResizableArray.foreach$(ResizableArray.scala:55)
at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:49)
at org.renaissance.RenaissanceSuite$.main(renaissance-suite.scala:296)
at org.renaissance.RenaissanceSuite.main(renaissance-suite.scala)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at org.renaissance.Launcher.main(Launcher.java:21)
The following benchmarks failed: finagle-http