Building 

gcc -DHAVE_CONFIG_H -I. -I../../..  -I../../.. -I../../../include -I../../../coregrind -I../../../include -I../../../VEX/pub -I../../../VEX/pub -DVGA_ppc64le=1 -DVGO_linux=1 -DVGP_ppc64le_linux=1 -DVGPV_ppc64le_linux_vanilla=1    -Winline -Wall -Wshadow -Wno-long-long -g -fno-stack-protector   -m64  -Wl,-z,norelro -Winline -Wall -O -g -mregnames -m64 -DHAS_ALTIVEC -maltivec  -MT jm_insns-jm-insns.o -MD -MP -MF .deps/jm_insns-jm-insns.Tpo -c -o jm_insns-jm-insns.o `test -f 'jm-insns.c' || echo './'`jm-insns.c
/tmp/ccub8B9V.s: Assembler messages:
/tmp/ccub8B9V.s:7810: Warning: invalid register expression
/tmp/ccub8B9V.s:7865: Warning: invalid register expression
/tmp/ccub8B9V.s:7882: Warning: invalid register expression
/tmp/ccub8B9V.s:8899: Warning: invalid register expression
/tmp/ccub8B9V.s:8958: Warning: invalid register expression
/tmp/ccub8B9V.s:8975: Warning: invalid register expression
/tmp/ccub8B9V.s:9270: Warning: invalid register expression
/tmp/ccub8B9V.s:9321: Warning: invalid register expression
/tmp/ccub8B9V.s:9338: Warning: invalid register expression
/tmp/ccub8B9V.s:9612: Warning: invalid register expression
/tmp/ccub8B9V.s:9649: Warning: invalid register expression
/tmp/ccub8B9V.s:9666: Warning: invalid register expression
/tmp/ccub8B9V.s:9914: Warning: invalid register expression
/tmp/ccub8B9V.s:9965: Warning: invalid register expression
/tmp/ccub8B9V.s:9982: Warning: invalid register expression
/tmp/ccub8B9V.s:10234: Warning: invalid register expression
/tmp/ccub8B9V.s:10292: Warning: invalid register expression
/tmp/ccub8B9V.s:10309: Warning: invalid register expression
/tmp/ccub8B9V.s:10605: Warning: invalid register expression
/tmp/ccub8B9V.s:10656: Warning: invalid register expression
/tmp/ccub8B9V.s:10673: Warning: invalid register expression
/tmp/ccub8B9V.s:11860: Warning: invalid register expression
/tmp/ccub8B9V.s:11911: Warning: invalid register expression
/tmp/ccub8B9V.s:12397: Warning: invalid register expression
/tmp/ccub8B9V.s:12441: Warning: invalid register expression
/tmp/ccub8B9V.s:12458: Warning: invalid register expression
/tmp/ccub8B9V.s:12849: Warning: invalid register expression
/tmp/ccub8B9V.s:12900: Warning: invalid register expression
/tmp/ccub8B9V.s:12917: Warning: invalid register expression
/tmp/ccub8B9V.s:13197: Warning: invalid register expression
/tmp/ccub8B9V.s:13234: Warning: invalid register expression
/tmp/ccub8B9V.s:13251: Warning: invalid register expression
/tmp/ccub8B9V.s:13721: Warning: invalid register expression
/tmp/ccub8B9V.s:13765: Warning: invalid register expression
/tmp/ccub8B9V.s:13782: Warning: invalid register expression
/tmp/ccub8B9V.s:18346: Warning: invalid register expression
/tmp/ccub8B9V.s:18390: Warning: invalid register expression
/tmp/ccub8B9V.s:18407: Warning: invalid register expression
/tmp/ccub8B9V.s:18832: Warning: invalid register expression
/tmp/ccub8B9V.s:18872: Warning: invalid register expression
/tmp/ccub8B9V.s:18889: Warning: invalid register expression
mv -f .deps/jm_insns-jm-insns.Tpo .deps/jm_insns-jm-insns.Po

The testcase also fails:
jm-vmx:          valgrind   ./jm-insns -a 
*** jm-vmx failed (stdout) ***

The warnings are about mfvscr %r10 and vor %r6.

Which come from the following asm statements:

__asm__ __volatile__ ("mfvscr %0" : "=vr" (tmpvscr));

__asm__ __volatile__ ("vor %0,17,17" : "=vr" (vec_out));

It looks to me that the constraints are wrong on those.
The "=vr" should probably be "=v".