The problem is C1, I reproduced it on solaris-sparc, i586

To reproduce run:
/net/sqenfs-1.sfbay/export1/jdk/re/6u18/promoted/all/b01/binaries/solaris-sparc/fastdebug/bin/java -client -XX:-ShowMessageBoxOnError -Xverify:all -XX:+CompileTheWorld -Xbootclasspath/p:/net/sqenfs-1.sfbay/export1/comp/vm/testbase/ctw/build/../jars/ibiblio/maven2/com/flagstonesoftware/transform-swf/2.1.5/transform-swf-2.1.5.jar


Output:
# To suppress the following error report, specify this argument
# after -XX: or in .hotspotrc: SuppressErrorAt=/c1_Instruction.hpp:409
#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/BUILD_AREA/jdk6_18/hotspot/src/share/vm/c1/c1_Instruction.hpp:409), pid=29751, tid=7
# Error: assert(subst == 0 || type()->base() == subst->type()->base() || subst->type()->base() == illegalType,"type can't change")
#
# JRE version: 6.0_18-b01
# Java VM: Java HotSpot(TM) Client VM (16.0-b08-fastdebug mixed mode solaris-sparc )
# An error report file with more information is saved as:
# /tmp/hs_err_pid29751.log
#
# If you would like to submit a bug report, please visit:
# http://java.sun.com/webapps/bugreport/crash.jsp
#
Current thread is 7
Dumping core ...
Abort
lm153972@vm-t20