The clhsdb jstack command crashes when the debugged program is run with `-Xcomp
-XX:+StressGCM -XX:StressSeed=2` on AArch64:
sun.jvm.hotspot.utilities.AssertionFailure: sanity check
at jdk.hotspot.agent/sun.jvm.hotspot.utilities.Assert.that(Assert.java:32)
at
jdk.hotspot.agent/sun.jvm.hotspot.runtime.RegisterMap.setLocation(RegisterMap.java:160)
at
jdk.hotspot.agent/sun.jvm.hotspot.compiler.ImmutableOopMapSet.updateRegisterMap(ImmutableOopMapSet.java:303)
at
jdk.hotspot.agent/sun.jvm.hotspot.runtime.aarch64.AARCH64Frame.senderForCompiledFrame(AARCH64Frame.java:407)
The assertion failure here is:
Assert.that(0 <= i && i < regCount, "sanity check");
I.e. there's an invalid register in the oop map.
The problem seems to be caused by the changes in JDK-8231586 which changed
`OopMapValue::oop_types` from a bit mask to normal integer enum. However the
changes in the C++ code weren't mirrored in SA's OopMapStream which still
treats OopTypes as a bit mask.
The particular oop map this is crashing on looks like this:
ImmutableOopMap {[24]=Oop [32]=Oop [40]=Derived_oop_[24] } pc offsets: 324
The code is looking for callee saved values (type=2) by AND-ing with each oop
value type in the set, so it wrongly interprets the derived oop [40] (type=3)
as a callee saved register.
This patch just mirrors the changes to the C++ code into the corresponding SA
classes. The C++ OopMapStream constructor no longer takes a type filter
argument and callers are expected filter themselves, so I've made the same
change to the Java code.
This bug can also be seen using the clhsdb "disassemble" command. For example
the above oop map is currently printed incorrectly as:
OopMap:
NarrowOops:[40]
Callee saved:[40] = [24]
Derived oops:[40] = [24]
With this patch it becomes:
OopMap:
Oops:[24] [32]
Derived oops:[40] = [24]
This bug was reported on AArch64 but it seems to be just luck that we don't see
it on other platforms.
Tested tier1 and hotspot_serviceability on AArch64 and x86.
-------------
Commit messages:
- 8261236: C2: ClhsdbJstackXcompStress test fails when StressGCM is enabled
Changes: https://git.openjdk.java.net/jdk/pull/4807/files
Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4807&range=00
Issue: https://bugs.openjdk.java.net/browse/JDK-8261236
Stats: 58 lines in 3 files changed: 12 ins; 28 del; 18 mod
Patch: https://git.openjdk.java.net/jdk/pull/4807.diff
Fetch: git fetch https://git.openjdk.java.net/jdk pull/4807/head:pull/4807
PR: https://git.openjdk.java.net/jdk/pull/4807
