When testing with the dacapo test suite I've hit the following assert:

# To suppress the following error report, specify this argument
# after -XX: or in .hotspotrc: SuppressErrorAt=/memnode.cpp:4035
#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/java/east/u2/ap31282/hotspot-g1-race-7/src/share/vm/opto/memnode.cpp:4035), pid=2974, tid=63
# Error: assert(alias_idx >= Compile::AliasIdxRaw || alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,"must avoid base_memory and AliasIdxTop")
#
# JRE version: 7.0-b28
# Java VM: OpenJDK 64-Bit Server VM (17.0-b06-internal-fastdebug mixed mode solaris-sparc )
# An error report file with more information is saved as:
# /java/east/u2/ap31282/gc_test_suite_core/dacapo/hs_err_pid2974.log
#
# If you would like to submit a bug report, please visit:
# http://java.sun.com/webapps/bugreport/crash.jsp
#

I hit it every time I run the bloat test, either on its own or when run along with the other dacapo tests. I can reproduce it with a solaris / sparcv9 / fastdebug build on a 16-way UltraIV, as well as a Niagara 1 box. It doesn't seem to happen with a 32-bit sparc JVM. I also tried an amd64 build on my workstation and again I couldn't reproduce the issue.

Here's the incantation that uncovers the failure:

java -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:-ReduceInitialCardMarks -d64 -XX:+PrintGCTimeStamps -XX:+PrintGCDetails -jar dacapo-2006-10.jar -s default bloat