On Thu, Oct 05, 2017 at 10:34:26PM +0200, Jakub Jelinek wrote:
> Hi!
>
> In warn_tautological_bitwise_comparison, there is even a comment
> mentioning the fact that the types of the two constants might not be the
> same (it is called with the original arguments before they are promoted
> to common type for the comparison).
>
> On the following testcase, one of the constants was unsigned (because
> it has been converted to that when anded with unsigned variable), while
> the other was signed and wi::to_widest (bitopcst) & wi::to_widest (cst)
> wasn't sign-extended from 32-bit (because bitopcst was unsigned),
> while wi::to_widest (cst) was (because cst was int), so we warned even
> when we shouldn't.
>
> The following patch instead uses the precision of the larger type and
> zero extends from that (because we really don't need to care about bits
> beyond that precision).
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
Looks ok, thanks.
Marek
