SIGSEGV in string_indexof_char and stringL_indexof_char intrinsics

The following test failed in the JDK16 CI:

javax/xml/crypto/dsig/GenerationTests.java

Here's a snippet from the log file:

unknown Transform
-S
no source document
-S#
# A fatal error has been detected by the Java Runtime Environment:
#
# SIGSEGV (0xb) at pc=0x000000011a317e29, pid=67294, tid=23555
#
# JRE version: Java(TM) SE Runtime Environment (16.0+20) (build 16-ea+20-1090)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (16-ea+20-1090, mixed mode, sharing, tiered, compressed oops, g1 gc, bsd-amd64)
# Problematic frame:
# J 7618 c2 sun.net.www.http.HttpClient.parseHTTPHeader(Lsun/net/www/MessageHeader;Lsun/net/ProgressSource;Lsun/net/www/protocol/http/HttpURLConnection;)Z java.base@16-ea (1173 bytes) @ 0x000000011a317e29 [0x000000011a317680+0x00000000000007a9]
#
# Core dump will be written. Default location: core.67294
#
# An error report file with more information is saved as:
# /System/Volumes/Data/mesos/work_dir/slaves/4076d11c-c6ed-4d07-84c1-4ab8d55cd975-S421566/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/79afc7f6-a6d8-4412-bf80-079c818d0f2a/runs/6cb77053-6c69-4c1c-ac33-ab8254ea4714/testoutput/test-support/jtreg_open_test_jdk_tier2_part1/scratch/4/hs_err_pid67294.log
#
# If you would like to submit a bug report, please visit:
# https://bugreport.java.com/bugreport/crash.jsp
#
----------System.err:(0/0)----------


Here's the crashing thread's stack:

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

Current thread (0x00007fbc74009600): JavaThread "MainThread" [_thread_in_Java, id=23555, stack(0x000070000c913000,0x000070000ca13000)]

Stack: [0x000070000c913000,0x000070000ca13000], sp=0x000070000ca11d00, free space=1019k
Native frames: (J=compiled Java code, A=aot compiled Java code, j=interpreted, Vv=VM code, C=native code)
J 7618 c2 sun.net.www.http.HttpClient.parseHTTPHeader(Lsun/net/www/MessageHeader;Lsun/net/ProgressSource;Lsun/net/www/protocol/http/HttpURLConnection;)Z java.base@16-ea (1173 bytes) @ 0x000000011a317e29 [0x000000011a317680+0x00000000000007a9]
J 7440 c2 sun.net.www.http.HttpClient.parseHTTP(Lsun/net/www/MessageHeader;Lsun/net/ProgressSource;Lsun/net/www/protocol/http/HttpURLConnection;)Z java.base@16-ea (183 bytes) @ 0x000000011a28054c [0x000000011a280140+0x000000000000040c]
J 6066 c2 sun.net.www.protocol.http.HttpURLConnection.getInputStream0()Ljava/io/InputStream; java.base@16-ea (2059 bytes) @ 0x0000000119fa7f4c [0x0000000119fa7740+0x000000000000080c]
J 7821 c2 com.sun.org.apache.xml.internal.security.utils.resolver.implementations.ResolverDirectHTTP.engineResolveURI(Lcom/sun/org/apache/xml/internal/security/utils/resolver/ResourceResolverContext;)Lcom/sun/org/apache/xml/internal/security/signature/XMLSignatureInput; java.xml.crypto@16-ea (413 bytes) @ 0x000000011a3ae8b8 [0x000000011a3ae460+0x0000000000000458]
J 7611 c2 org.jcp.xml.dsig.internal.dom.DOMURIDereferencer.dereference(Ljavax/xml/crypto/URIReference;Ljavax/xml/crypto/XMLCryptoContext;)Ljavax/xml/crypto/Data; java.xml.crypto@16-ea (433 bytes) @ 0x000000011a30e264 [0x000000011a30d840+0x0000000000000a24]
J 8243 c2 org.jcp.xml.dsig.internal.dom.DOMXMLSignature.digestReference(Lorg/jcp/xml/dsig/internal/dom/DOMReference;Ljavax/xml/crypto/dsig/XMLSignContext;)V java.xml.crypto@16-ea (231 bytes) @ 0x000000011a52b1a0 [0x000000011a52b0a0+0x0000000000000100]
J 8215 c1 org.jcp.xml.dsig.internal.dom.DOMXMLSignature.sign(Ljavax/xml/crypto/dsig/XMLSignContext;)V java.xml.crypto@16-ea (609 bytes) @ 0x0000000112e797fc [0x0000000112e76e60+0x000000000000299c]
J 8224 c1 GenerationTests.test_create_detached_signature0(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;LGenerationTests$KeyInfoType;LGenerationTests$Content;I)Z (887 bytes) @ 0x00000001132ad8fc [0x00000001132a9c40+0x0000000000003cbc]
j GenerationTests.test_create_detached_signature(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;LGenerationTests$KeyInfoType;LGenerationTests$Content;IZLjava/lang/Class;)V+55
j GenerationTests.main([Ljava/lang/String;)V+421
v ~StubRoutines::call_stub
V [libjvm.dylib+0x4b50a2] JavaCalls::call_helper(JavaValue*, methodHandle const&, JavaCallArguments*, Thread*)+0x2d2
V [libjvm.dylib+0x89fb65] invoke(InstanceKlass*, methodHandle const&, Handle, bool, objArrayHandle, BasicType, objArrayHandle, bool, Thread*)+0xa65
V [libjvm.dylib+0x89f098] Reflection::invoke_method(oopDesc*, Handle, objArrayHandle, Thread*)+0x158
V [libjvm.dylib+0x564337] JVM_InvokeMethod+0x337
j jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Ljava/lang/reflect/Method;Ljava/lang/Object;[Ljava/lang/Object;)Ljava/lang/Object;+0 java.base@16-ea
j jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Ljava/lang/Object;[Ljava/lang/Object;)Ljava/lang/Object;+113 java.base@16-ea
j jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Ljava/lang/Object;[Ljava/lang/Object;)Ljava/lang/Object;+6 java.base@16-ea
j java.lang.reflect.Method.invoke(Ljava/lang/Object;[Ljava/lang/Object;)Ljava/lang/Object;+59 java.base@16-ea
j com.sun.javatest.regtest.agent.MainWrapper$MainThread.run()V+172
j java.lang.Thread.run()V+11 java.base@16-ea
v ~StubRoutines::call_stub
V [libjvm.dylib+0x4b50a2] JavaCalls::call_helper(JavaValue*, methodHandle const&, JavaCallArguments*, Thread*)+0x2d2
V [libjvm.dylib+0x4b40e7] JavaCalls::call_virtual(JavaValue*, Klass*, Symbol*, Symbol*, JavaCallArguments*, Thread*)+0x147
V [libjvm.dylib+0x4b41b3] JavaCalls::call_virtual(JavaValue*, Handle, Klass*, Symbol*, Symbol*, Thread*)+0x63
V [libjvm.dylib+0x5600e4] thread_entry(JavaThread*, Thread*)+0xb4
V [libjvm.dylib+0x99febd] JavaThread::thread_main_inner()+0xcd
V [libjvm.dylib+0x99d461] Thread::call_run()+0x71
V [libjvm.dylib+0x82bd57] thread_native_entry(Thread*)+0x157
C [libsystem_pthread.dylib+0x6109] _pthread_start+0x94
C [libsystem_pthread.dylib+0x1b8b] thread_start+0xf


siginfo: si_signo: 11 (SIGSEGV), si_code: 1 (SEGV_MAPERR), si_addr: 0x00000000e41d2718

Starting this bug as a P2 since it has happened in two Tier2
job sets in a row.