https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70028
Kirill Yukhin <kyukhin at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Last reconfirmed| |2016-03-01 CC| |kyukhin at gcc dot gnu.org Ever confirmed|0 |1 --- Comment #2 from Kirill Yukhin <kyukhin at gcc dot gnu.org> --- Confirmed. The issue is that operand modifier passed in .md file is %k1, which stands for SI mode. It should be 32b reg or 16b memory, i.e. %ebx and WORD.