When running jtreg and JCK tests with ubsan enabled on AIX those 2 issues are reported :

JCK test api/java_awt/Font/TextLayout/DrawTesttestCase2

/priv/jenkins/client-home/workspace/openjdk-jdk-weekly-aix_ppc64-opt/jdk/src/java.desktop/share/native/libfontmanager/DrawGlyphList.c:110:13: runtime error: 3.40282e+38 is outside the range of representable values of type 'int'
#0 0x9000000071a2a90 in setupBlitVector make/src/java.desktop/share/native/libfontmanager/DrawGlyphList.c:110
#1 0x9000000071a386c in Java_sun_java2d_loops_DrawGlyphListAA_DrawGlyphListAA make/src/java.desktop/share/native/libfontmanager/DrawGlyphList.c:357
#2 0xa0001000741df08 (shmid:706742123 +0x741df08)
#3 0xa00010007418298 (shmid:706742123 +0x7418298)
....
#31 0xa00010007418298 (shmid:706742123 +0x7418298)
#32 0xa00010007410838 (shmid:706742123 +0x7410838)
#33 0x900000011cd9788 in JavaCalls::call_helper(JavaValue*, methodHandle const&, JavaCallArguments*, JavaThread*) make/hotspot/src/hotspot/share/runtime/javaCalls.cpp:415
#34 0x900000011cdd218 in os::os_exception_wrapper(void (*)(JavaValue*, methodHandle const&, JavaCallArguments*, JavaThread*), JavaValue*, methodHandle const&, JavaCallArguments*, JavaThread*) make/hotspot/src/hotspot/os/aix/os_aix.cpp:2395
#35 0x900000011a56320 in JavaCalls::call(JavaValue*, methodHandle const&, JavaCallArguments*, JavaThread*) make/hotspot/src/hotspot/share/runtime/javaCalls.cpp:323
#36 0x900000011a56320 in JavaCalls::call_virtual(JavaValue*, Klass*, Symbol*, Symbol*, JavaCallArguments*, JavaThread*) make/hotspot/src/hotspot/share/runtime/javaCalls.cpp:179
#37 0x900000011a55fd8 in JavaCalls::call_virtual(JavaValue*, Handle, Klass*, Symbol*, Symbol*, JavaThread*) make/hotspot/src/hotspot/share/runtime/javaCalls.cpp:185
#38 0x900000013029b98 in thread_entry(JavaThread*, JavaThread*) make/hotspot/src/hotspot/share/prims/jvm.cpp:2748
#39 0x9000000121bf238 in JavaThread::thread_main_inner() make/hotspot/src/hotspot/share/runtime/javaThread.cpp:773
#40 0x9000000121bd034 in JavaThread::run() make/hotspot/src/hotspot/share/runtime/javaThread.cpp:758
#41 0x900000011abbc74 in Thread::call_run() make/hotspot/src/hotspot/share/runtime/thread.cpp:231
#42 0x900000011abad38 in thread_native_entry(Thread*) make/hotspot/src/hotspot/os/aix/os_aix.cpp:682

Seems to be this line
110 FLOOR_ASSIGN(gbv->glyphs[g].x, px + ginfo->topLeftX);


jtreg test java/awt/FontClass/DrawStringWithInfiniteXform.java

/priv/jenkins/client-home/workspace/openjdk-jdk-weekly-aix_ppc64-opt/jdk/src/java.desktop/share/native/libfontmanager/DrawGlyphList.c:123:13: runtime error: NaNQ is outside the range of representable values of type 'int'
    #0 0x9000000071a1840 in setupBlitVector make/src/java.desktop/share/native/libfontmanager/DrawGlyphList.c:123
    #1 0x9000000071a342c in Java_sun_java2d_loops_DrawGlyphList_DrawGlyphList make/src/java.desktop/share/native/libfontmanager/DrawGlyphList.c:326
    #2 0xa0001000741dc08 (shmid:42993186 +0x741dc08)
 ....
    #19 0xa00010007417f98 (shmid:42993186 +0x7417f98)
    #20 0xa00010007410838 (shmid:42993186 +0x7410838)
    #21 0x900000011cd9088 in JavaCalls::call_helper(JavaValue*, methodHandle const&, JavaCallArguments*, JavaThread*) make/hotspot/src/hotspot/share/runtime/javaCalls.cpp:415
    #22 0x900000011cdcb18 in os::os_exception_wrapper(void (*)(JavaValue*, methodHandle const&, JavaCallArguments*, JavaThread*), JavaValue*, methodHandle const&, JavaCallArguments*, JavaThread*) make/hotspot/src/hotspot/os/aix/os_aix.cpp:2396
    #23 0x900000011a560c0 in JavaCalls::call(JavaValue*, methodHandle const&, JavaCallArguments*, JavaThread*) make/hotspot/src/hotspot/share/runtime/javaCalls.cpp:323
    #24 0x900000011a560c0 in JavaCalls::call_virtual(JavaValue*, Klass*, Symbol*, Symbol*, JavaCallArguments*, JavaThread*) make/hotspot/src/hotspot/share/runtime/javaCalls.cpp:179
    #25 0x900000011a55d78 in JavaCalls::call_virtual(JavaValue*, Handle, Klass*, Symbol*, Symbol*, JavaThread*) make/hotspot/src/hotspot/share/runtime/javaCalls.cpp:185
    #26 0x900000013025638 in thread_entry(JavaThread*, JavaThread*) make/hotspot/src/hotspot/share/prims/jvm.cpp:2748
    #27 0x9000000121bd958 in JavaThread::thread_main_inner() make/hotspot/src/hotspot/share/runtime/javaThread.cpp:773
    #28 0x9000000121bb754 in JavaThread::run() make/hotspot/src/hotspot/share/runtime/javaThread.cpp:758
    #29 0x900000011abba14 in Thread::call_run() make/hotspot/src/hotspot/share/runtime/thread.cpp:231
    #30 0x900000011abaad8 in thread_native_entry(Thread*) make/hotspot/src/hotspot/os/aix/os_aix.cpp:683

seems to be this line
123 FLOOR_ASSIGN(gbv->glyphs[g].x, x + ginfo->topLeftX);