On Wed, Feb 04, 2015 at 04:21:43AM -0200, Alexandre Oliva wrote:
> I'm a bit surprised the gimple layer does not even attempt to simplify
> them, but I didn't try to tackle that, since I was not even sure this
> was a useful optimization. After all, how often do we see xor of and of
> xor of and of xor of... in the wild, rather than in pathological
> testcases? :-) But hey, at least the rtl simplification is cheap, so
> why not?
I think we should teach at least VRP to simplify debug stmts similarly how
it simplifies normal comparisons etc. using value ranges, but that would be
stage1 material.
> Regstrapped on x86_64-linux-gnu and i686-pc-linux-gnu. Ok to install?
>
> for gcc/ChangeLog
>
> * simplify-rtx.c (simplify_binary_operation_1): Simplify one
> of two XORs that have an intervening AND or IOR.
Ok, thanks.
Jakub
