assembly errors with clang

[letrout]

I'm trying to compile tinymembench with clang and hitting errors in x86-sse2 assembly code. I removed all the .func and .endfunc directives since it seems LLVM has no interest in supporting them (as noted in another issue), but it's still complaining about ambiguous or invalid operands. I know next to nothing about assembly, any help on how to move past this would be greatly appreciated.
$ make
/opt/clang7.0.0/bin/clang-7 -O2 -c x86-sse2.S
/tmp/x86-sse2-ab79fe.s:81:9: error: ambiguous operand size for instruction 'add'
add SRC, 64
^~~
/tmp/x86-sse2-ab79fe.s:82:9: error: ambiguous operand size for instruction 'add'
add DST, 64
^~~
/tmp/x86-sse2-ab79fe.s:83:9: error: ambiguous operand size for instruction 'sub'
sub SIZE, 64
^~~~
/tmp/x86-sse2-ab79fe.s:84:5: error: invalid operand for instruction
jg 0b
^
/tmp/x86-sse2-ab79fe.s:97:9: error: ambiguous operand size for instruction 'add'
add SRC, 64
^~~
/tmp/x86-sse2-ab79fe.s:98:9: error: ambiguous operand size for instruction 'add'
add DST, 64
^~~
/tmp/x86-sse2-ab79fe.s:99:9: error: ambiguous operand size for instruction 'sub'
sub SIZE, 64
^~~~
/tmp/x86-sse2-ab79fe.s:100:5: error: invalid operand for instruction
jg 0b
^
/tmp/x86-sse2-ab79fe.s:115:9: error: ambiguous operand size for instruction 'add'
add SRC, 64
^~~
/tmp/x86-sse2-ab79fe.s:116:9: error: ambiguous operand size for instruction 'add'
add DST, 64
^~~
/tmp/x86-sse2-ab79fe.s:117:9: error: ambiguous operand size for instruction 'sub'
sub SIZE, 64
^~~~
/tmp/x86-sse2-ab79fe.s:118:5: error: invalid operand for instruction
jg 0b
^
/tmp/x86-sse2-ab79fe.s:133:9: error: ambiguous operand size for instruction 'add'
add SRC, 64
^~~
/tmp/x86-sse2-ab79fe.s:134:9: error: ambiguous operand size for instruction 'add'
add DST, 64
^~~
/tmp/x86-sse2-ab79fe.s:135:9: error: ambiguous operand size for instruction 'sub'
sub SIZE, 64
^~~~
/tmp/x86-sse2-ab79fe.s:136:5: error: invalid operand for instruction
jg 0b
^
/tmp/x86-sse2-ab79fe.s:150:9: error: ambiguous operand size for instruction 'add'
add SRC, 64
^~~
/tmp/x86-sse2-ab79fe.s:151:9: error: ambiguous operand size for instruction 'add'
add DST, 64
^~~
/tmp/x86-sse2-ab79fe.s:152:9: error: ambiguous operand size for instruction 'sub'
sub SIZE, 64
^~~~
/tmp/x86-sse2-ab79fe.s:153:5: error: invalid operand for instruction
jg 0b
^
/tmp/x86-sse2-ab79fe.s:167:9: error: ambiguous operand size for instruction 'add'
add SRC, 64
^~~
/tmp/x86-sse2-ab79fe.s:168:9: error: ambiguous operand size for instruction 'add'
add DST, 64
^~~
/tmp/x86-sse2-ab79fe.s:169:9: error: ambiguous operand size for instruction 'sub'
sub SIZE, 64
^~~~
/tmp/x86-sse2-ab79fe.s:170:5: error: invalid operand for instruction
jg 0b
^
/tmp/x86-sse2-ab79fe.s:180:9: error: ambiguous operand size for instruction 'add'
add DST, 64
^~~
/tmp/x86-sse2-ab79fe.s:181:9: error: ambiguous operand size for instruction 'sub'
sub SIZE, 64
^~~~
/tmp/x86-sse2-ab79fe.s:182:5: error: invalid operand for instruction
jg 0b
^
/tmp/x86-sse2-ab79fe.s:192:9: error: ambiguous operand size for instruction 'add'
add DST, 64
^~~
/tmp/x86-sse2-ab79fe.s:193:9: error: ambiguous operand size for instruction 'sub'
sub SIZE, 64
^~~~
/tmp/x86-sse2-ab79fe.s:194:5: error: invalid operand for instruction
jg 0b
^
Makefile:17: recipe for target 'x86-sse2.o' failed
make: *** [x86-sse2.o] Error 1
$ echo $CC
/opt/clang7.0.0/bin/clang-7
$ /opt/clang7.0.0/bin/clang-7 --version
clang version 7.0.0 (tags/RELEASE_700/final)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /opt/clang7.0.0/bin
$ uname -a
Linux jluth-desk 4.15.0-38-generic #41-Ubuntu SMP Wed Oct 10 10:59:38 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux