$ echo "SV.EXTSW *%R47, 3" | ./gas/as-new -mregnames -mlibresoc - -o /tmp/test.o && ./binutils/objdump -dr /tmp/test.o

/tmp/test.o:     file format elf64-powerpcle


Disassembly of section .text:

0000000000000000 <.text>:
   0:   00 38 40 05     .long 0x5403800
   4:   b4 07 6b 7c     extsw   r11,r3