On 14/08/2019 08:48, Eric Botcazou wrote:
[Sorry for the delay, I missed your question...]Interesting. Does it work for the general case of a reverse subtract, which I need to handle as wel?Not clear, Visium only uses it for SNE and combined NEG/SNE.
I worked through the logic. I'm pretty sure it will work for any unsigned or equality comparison and for any constant. The general transformation is
(cst uns/eq/op reg) == (~reg uns/eq/op ~cst) R.