After the fix for 6990192 running loopsAndThreads with a debug build on SPARC results in:

$ gamma -XX:+ShowMessageBoxOnError -XX:+UseSerialGC -XX:+UnlockExperimentalVMOptions -XX:+EnableInvokeDynamic -cp classes:. Test
VM option '+ShowMessageBoxOnError'
VM option '+UseSerialGC'
VM option '+UnlockExperimentalVMOptions'
VM option '+EnableInvokeDynamic'
EXECUTION STOPPED: too many pushes: Lesp points into register window

==============================================================================
too many pushes: Lesp points into register window
------------------------------------------------------------------------------
Execution stopped, print registers?
==============================================================================
n
# To suppress the following error report, specify this argument
# after -XX: or in .hotspotrc: SuppressErrorAt=/assembler_sparc.cpp:1969
==============================================================================
Unexpected Error
------------------------------------------------------------------------------
Internal Error at assembler_sparc.cpp:1969, pid=8944, tid=66
assert(false) failed: error

Do you want to debug the problem?

To debug, run 'dbx - 8944'; then switch to thread 66
Enter 'yes' to launch dbx automatically (PATH must include dbx)
Otherwise, press RETURN to abort...
==============================================================================


(dbx) where
current thread: t@66
  [1] _waitid(0x0, 0x22f1, 0xfffffffe69cfe440, 0x3, 0x0, 0xffffffff7f736540), at 0xffffffff7cddb230
  [2] _waitpid(0x22f1, 0xfffffffe69cfe6a8, 0x0, 0xffffffff7e6ba618, 0xffffffff75110a00, 0x0), at 0xffffffff7cd7abfc
  [3] waitpid(0x22f1, 0xfffffffe69cfe6a8, 0x0, 0x0, 0x0, 0xffffffff7cf482a0), at 0xffffffff7cdc9cec
=>[4] os::fork_and_exec(cmd = 0xffffffff7f206798 "dbx - 8944"), line 5978 in "os_solaris.cpp"
  [5] VMError::show_message_box(this = 0xfffffffe69cfea70, buf = 0xffffffff7f206798 "dbx - 8944", buflen = 2000), line 53 in "vmError_solaris.cpp"
  [6] VMError::report_and_die(this = 0xfffffffe69cfea70), line 725 in "vmError.cpp"
  [7] report_vm_error(file = 0xffffffff7ea21b86 "/home/ct232829/hotspot-comp/6990192/src/cpu/sparc/vm/assembler_sparc.cpp", line = 1969, error_msg = 0xffffffff7ea21bcf "assert(false) failed", detail_msg = 0xffffffff7ea21be4 "error"), line 176 in "debug.cpp"
  [8] MacroAssembler::debug(msg = 0xffffffff7ec4f3d0 "too many pushes: Lesp points into register window", regs = 0xfffffffe69cfed68), line 1969 in "assembler_sparc.cpp"
  [9] 0xffffffff780006fc(0xfffffffe69cfed68, 0xffffffff7ec4f3d0, 0x0, 0xffffffff78032994, 0x1003aef98, 0xffffffff78000520), at 0xffffffff780006fc
  [10] 0xffffffff7803876c(0x1c8, 0xa0, 0x8, 0xffffffff78033ed4, 0x0, 0xfffffffe69cfe7f1), at 0xffffffff7803876c
  [11] 0xffffffff78038750(0xfffffffe74cd03c0, 0xb6, 0x0, 0xffffffff7803870c, 0x0, 0xfffffffe69cfe901), at 0xffffffff78038750
  [12] 0xffffffff780067f0(0xfffffffe74cdc770, 0xffffffff700509f0, 0x0, 0xffffffff780370a0, 0x1, 0xfffffffe69cfea11), at 0xffffffff780067f0
  [13] 0xffffffff78007900(0xfffffffe74cd00e0, 0x1003ae000, 0x0, 0xffffffff78037e60, 0xfffffffe69cffa29, 0xfffffffe69cfeb01), at 0xffffffff78007900
  [14] 0xffffffff78000318(0xfffffffe69cff4d8, 0xfffffffe69cffb90, 0xa, 0xffffffff70052810, 0xffffffff78015600, 0xfffffffe69cff9f0), at 0xffffffff78000318
  [15] JavaCalls::call_helper(result = 0xfffffffe69cffb88, m = 0xfffffffe69cff758, args = 0xfffffffe69cff9d8, __the_thread__ = 0x1003ae000), line 379 in "javaCalls.cpp"
  [16] os::os_exception_wrapper(f = 0xffffffff7e31d600 = &JavaCalls::call_helper(JavaValue*,methodHandle*,JavaCallArguments*,Thread*), value = 0xfffffffe69cffb88, method = 0xfffffffe69cff758, args = 0xfffffffe69cff9d8, thread = 0x1003ae000), line 4083 in "os_solaris.cpp"
  [17] JavaCalls::call(result = 0xfffffffe69cffb88, method = CLASS, args = 0xfffffffe69cff9d8, __the_thread__ = 0x1003ae000), line 293 in "javaCalls.cpp"
  [18] JavaCalls::call_virtual(result = 0xfffffffe69cffb88, spec_klass = CLASS, name = CLASS, signature = CLASS, args = 0xfffffffe69cff9d8, __the_thread__ = 0x1003ae000), line 190 in "javaCalls.cpp"
  [19] JavaCalls::call_virtual(result = 0xfffffffe69cffb88, receiver = CLASS, spec_klass = CLASS, name = CLASS, signature = CLASS, __the_thread__ = 0x1003ae000), line 196 in "javaCalls.cpp"
  [20] thread_entry(thread = 0x1003ae000, __the_thread__ = 0x1003ae000), line 2580 in "jvm.cpp"
  [21] JavaThread::thread_main_inner(this = 0x1003ae000), line 1430 in "thread.cpp"
  [22] JavaThread::run(this = 0x1003ae000), line 1414 in "thread.cpp"
  [23] java_start(thread_addr = 0x1003ae000), line 1010 in "os_solaris.cpp"
(dbx) p ps ()

"Executing ps"
 for thread: "Thread-56" prio=3 tid=0x00000001003ae000 nid=0x42 runnable [0x0000000000000000]
   java.lang.Thread.State: RUNNABLE
   JavaThread state: _thread_in_Java
Thread: 0x00000001003ae000 [0x42] State: _running _has_called_back 0 _at_poll_safepoint 0
   JavaThread state: _thread_in_Java

(guessing starting frame id=fffffffe69cfe540 based on current fp)
C frame (sp=0xfffffffe69cfe540 unextended sp=0xfffffffe69cfe540, fp=0xfffffffe69cfe5f0, pc=0xffffffff7cdc9cf4)
C frame (sp=0xfffffffe69cfe5f0 unextended sp=0xfffffffe69cfe5f0, fp=0xfffffffe69cfe6f0, pc=0xffffffff7e6ba620)
C frame (sp=0xfffffffe69cfe6f0 unextended sp=0xfffffffe69cfe6f0, fp=0xfffffffe69cfe7e0, pc=0xffffffff7e9682f0)
C frame (sp=0xfffffffe69cfe7e0 unextended sp=0xfffffffe69cfe7e0, fp=0xfffffffe69cfe9b0, pc=0xffffffff7e966a24)
C frame (sp=0xfffffffe69cfe9b0 unextended sp=0xfffffffe69cfe9b0, fp=0xfffffffe69cfeb10, pc=0xffffffff7e0ea3cc)
C frame (sp=0xfffffffe69cfeb10 unextended sp=0xfffffffe69cfeb10, fp=0xfffffffe69cfec00, pc=0xffffffff7dd36b84)
C frame (sp=0xfffffffe69cfec00 unextended sp=0xfffffffe69cfec00, fp=0xfffffffe69cfecb0, pc=0xffffffff78000704)
(~Stub::stop_subroutine)
     BufferBlob (0xffffffff78000110) used for StubRoutines (1)

 1 - frame( sp=0xfffffffe69cfecb0, unextended_sp=0xfffffffe69cfecb0, fp=0xfffffffe69cfeff0, pc=0xffffffff78038774)
Test.target
 2 - frame( sp=0xfffffffe69cfeff0, unextended_sp=0xfffffffe69cfeff0, fp=0xfffffffe69cff0f0, pc=0xffffffff78038758)
Test.runThread(Test.java:73)
 3 - frame( sp=0xfffffffe69cff0f0, unextended_sp=0xfffffffe69cff100, fp=0xfffffffe69cff200, pc=0xffffffff780067f8)
vm.mlvm.share.MultiThreadedTest$1.run(MultiThreadedTest.java:32)
 4 - frame( sp=0xfffffffe69cff200, unextended_sp=0xfffffffe69cff210, fp=0xfffffffe69cff300, pc=0xffffffff78007908)
java.lang.Thread.run(Thread.java:729)
register window backtrace from 0x69cfe540:
[0] sp=0x69cfe540 pc=0x0000000000000000 is pointing to unknown location
[1] sp=0x69cfe5f0 pc=0x000000007e6ba618 is pointing to unknown location
[2] sp=0x69cfe6f0 pc=0x000000007e9682e8 is pointing to unknown location
[3] sp=0x69cfe7e0 pc=0x000000007e966a1c is pointing to unknown location
[4] sp=0x69cfe9b0 pc=0x000000007e0ea3c4 is pointing to unknown location
[5] sp=0x69cfeb10 pc=0x000000007dd36b7c is pointing to unknown location
[6] sp=0x69cfec00 pc=0x00000000780006fc is pointing to unknown location
[7] sp=0x69cfecb0 pc=0x000000007803876c is pointing to unknown location
[8] sp=0x69cfeff0 pc=0x0000000078038750 is pointing to unknown location
[9] sp=0x69cff0f0 pc=0x00000000780067f0 is pointing to unknown location
[10] sp=0x69cff200 pc=0x0000000078007900 is pointing to unknown location
[11] sp=0x69cff300 pc=0x0000000078000318 is pointing to unknown location
[12] sp=0x69cff3c0 pc=0x000000007e31de64 is pointing to unknown location
[13] sp=0x69cff5b0 pc=0x000000007e6b3ca4 is pointing to unknown location
[14] sp=0x69cff690 pc=0x000000007e31d5d8 is pointing to unknown location
[15] sp=0x69cff770 pc=0x000000007e31c578 is pointing to unknown location
[16] sp=0x69cff910 pc=0x000000007e31c68c is pointing to unknown location
[17] sp=0x69cffa90 pc=0x000000007e3eba3c is pointing to unknown location
[18] sp=0x69cffbf0 pc=0x000000007e8cac48 is pointing to unknown location
[19] sp=0x69cffd50 pc=0x000000007e8caac0 is pointing to unknown location
[20] sp=0x69cffe60 pc=0x000000007e6a7dc8 is pointing to unknown location
[21] sp=0x69cfff50 pc=0x000000007cdd6ee0 is pointing to unknown location
[22] sp=0x7ff [bogus sp!]ps() = (void)
(dbx) fr 9
0xffffffff780006fc: call debug ! 0xffffffff7dd36958
(dbx) p findpc($pc)
dbx: warning: unknown language, 'c' assumed
dbx: internal warning: don't know how to convert to integral type from
pointer (null)
 base integer $int

"Executing findpc"
StubRoutines::stop_subroutine [0xffffffff78000520, 0xffffffff78000840[ (800 bytes)
findpc($pc) = (void)
(dbx) up
0xffffffff7803876c: call %o5
(dbx) p findpc($pc)
dbx: internal warning: don't know how to convert to integral type from
pointer (null)
 base integer $int

"Executing findpc"
invokedynamic 186 invokedynamic [0xffffffff78038580, 0xffffffff780389e0] 1120 bytes
findpc($pc) = (void)
(dbx)