Kirill Yukhin <kirill.yuk...@gmail.com> writes: > I'm working on implementation of `mulx` (which is part of BMI2). One > of improvements compared generic `mul` is that it allows to specify > destination registers. > For `mul` we have `A` constraint, which stands for AX:DX pair. > So, is there a possibility to relax such cinstraint and allow any pair > of registers as destination?
Don't change the constraint, just add an alternative. Or use a different insn with an insn predicate. Ian
