def : InstAlias<"fdiv{|r}p\t{%st(0), $op|$op, st(0)}", (DIVR_FPrST0 RST:$op)>;
def : InstAlias<"fdiv{r|}p\t{%st(0), $op|$op, st(0)}", (DIV_FPrST0 RST:$op)>;
-// We accept "fnstsw %eax" even though it only writes %ax.
-def : InstAlias<"fnstsw\t{%eax|eax}", (FNSTSW16r)>;
-def : InstAlias<"fnstsw\t{%al|al}" , (FNSTSW16r)>;
-def : InstAlias<"fnstsw" , (FNSTSW16r)>;
+def : InstAlias<"fnstsw" , (FNSTSW16r), 0>;
// lcall and ljmp aliases. This seems to be an odd mapping in 64-bit mode, but
// this is compatible with what GAS does.