https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108539
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
CC| |jakub at gcc dot gnu.org
Resolution|--- |INVALID
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
That is just misunderstanding of the inline asm syntax, please read the
documentation.
"=dl" doesn't mean that _a output is in %dl register, but either in %edx
register or
in any of the index registers (%eax %ebx %ecx %edx %esi %edi %ebp).
"=dh" means either in %edx register or in nowhere (h isn't a valid constraint).
So, when doing RA _b needs to be put into %edx (the low 8 bits of that aka %dl)
and _a into some index register other than %edx.
