for review: 8236522: "always atomic" modifier for inline classes to enforce atomicity

[Tobias Hartmann]

Hi John,

On 24.12.19 22:36, John Rose wrote:
> This uncovered a missing StoreStore barrier in C2, which I also fixed.

While trying to reproduce this issue, I've hit some issues:

1) #  assert(strchr(class_name, '.') == 0LL) failed: external form of class name

Stack: [0x000000b1eca00000,0x000000b1ecb00000]
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V  [jvm.dll+0xb09e61]  os::platform_print_native_stack+0xf1  (os_windows_x86.cpp:369)
V  [jvm.dll+0xd36c6b]  VMError::report+0xf0b  (vmerror.cpp:725)
V  [jvm.dll+0xd3851e]  VMError::report_and_die+0x8ae  (vmerror.cpp:1533)
V  [jvm.dll+0xd38c14]  VMError::report_and_die+0x64  (vmerror.cpp:1317)
V  [jvm.dll+0x4e5202]  report_vm_error+0x102  (debug.cpp:264)
V  [jvm.dll+0xc08482]  StringUtils::class_list_matches+0x72  (stringutils.cpp:97)
V  [jvm.dll+0x45f4f0]  ClassFileParser::parse_stream+0x660  (classfileparser.cpp:6450)
V  [jvm.dll+0x44e567]  ClassFileParser::ClassFileParser+0x507  (classfileparser.cpp:6264)
V  [jvm.dll+0x921db3]  KlassFactory::create_from_stream+0x1d3  (klassfactory.cpp:204)
V  [jvm.dll+0xc7aa1b]  SystemDictionary::resolve_from_stream+0x21b  (systemdictionary.cpp:1163)
V  [jvm.dll+0x7bb3c2]  jvm_define_class_common+0x252  (jvm.cpp:975)
V  [jvm.dll+0x7c542c]  JVM_DefineClassWithSource+0x20c  (jvm.cpp:999)
C  [java.dll+0x1970]  Java_java_lang_ClassLoader_defineClass1+0x140  (classloader.c:133)

Seems to happen only on Windows.

2) The jdk/jshell/ fail with "No corresponding jdk.jshell.CompletenessAnalyzer.TK for
com.sun.tools.javac.parser.Tokens.TokenKind: __AlwaysAtomic"

3) Some javac tests fail
- tools/javac/valhalla/lworld-values/QTypeTest.java
- tools/javac/diags/CheckResourceKeys.java

I've added the Mach5 result link to the bug comments.

Now I'm not able to reproduce the problem with the missing StoreStore barrier in C2. Neither with
your ValueTearing.java test, nor with a newly written one with flags like -XX:+StressGCM.

How did it reproduce for you? It would be nice to have a regression test.

Thanks,
Tobias