Hi BinUtils,

It looks like I may have found a bug in the gcc assembler, where the wrong op codes are being generated.  For all destination registers, the fixed source value gets changed.  For example:

add eax, dword ptr ds:[0x22222222]

Encodes to: 03 04 25 26 22 22 22
 Should be: 03 04 25 22 22 22 22

And,

add rax, qword ptr ds:[0x33333333]

Encodes to: 48 03 04 25 3B 33 33 33
 Should be: 48 03 04 25 33 33 33 33

The change in the address is the size of the data element (dword[4] or qword[8]).  As if it was looking at array_element[1] instead of array_element[0].  The change in the address is also not the size of the instruction in the case of dword.

Thanks,
Tim Reago