http://ibiblio.org/gferg/ldp/GCC-Inline-Assembly-HOWTO.html
http://gcc.gnu.org/onlinedocs/gcc-4.8.2/gcc/Extended-Asm.html
http://gcc.gnu.org/onlinedocs/gcc-4.8.2/gcc/Constraints.html
+http://drpaulcarter.com/pcasm/
+
+Debugging assembly code with gdb:
+
+gdb ./inline-asm-SIMD-sum
+(gdb) break sum
+(gdb) run
+(gdb) display/i $pc
+(gdb) stepi
+(gdb) stepi