Fails with (apparently due to new gcc toolchain):

gcc -E `if test false = true; then echo '-DASM_UNDERSCORE'; fi` ./vacall-arm.S | grep -v '^ *#line' | grep -v '^#' | sed -e 's,% ,%,g' -e 's,//,@,g' -e 's,\$,#,g' > vacall-arm.s
gcc -x none -c vacall-arm.s
vacall-arm.s: Assembler messages:
vacall-arm.s:3: Warning: ignoring attempt to redefine built-in register 'sl'
vacall-arm.s:4: Warning: ignoring attempt to redefine built-in register 'fp'
vacall-arm.s:5: Warning: ignoring attempt to redefine built-in register 'ip'
vacall-arm.s:6: Warning: ignoring attempt to redefine built-in register 'sp'
vacall-arm.s:7: Warning: ignoring attempt to redefine built-in register 'lr'
vacall-arm.s:8: Warning: ignoring attempt to redefine built-in register 'pc'
vacall-arm.s:80: Error: selected processor does not support `ldfeqs f0,[sp,#20]' in ARM mode
vacall-arm.s:84: Error: selected processor does not support `ldfeqd f0,[sp,#20]' in ARM mode
Makefile:105: recipe for target 'vacall-arm.o' failed
make[1]: *** [vacall-arm.o] Error 1

See also:
https://wiki.debian.org/ArmEabiProblems (search for ffcall)