David Daney <[EMAIL PROTECTED]> writes: > Andrew Haley wrote: > > Ian Lance Taylor writes: > > > Joe Buck <[EMAIL PROTECTED]> writes: > > > > > I suggest that those who think this is a severe problem are > > the > > > > ones who are highly motivated to work on a solution. An > > > > efficient solution could be tricky: you don't want to disrupt > > > > pipelines, or interfere with optimizations that rely on > > > > recognizing that there is a modulo. > > > > I suspect that the best fix, in the sense of generating the > > best > > > code, would be to do this at the tree level. That will give loop > > > and VRP optimizations the best chance to eliminate the test for -1. > > > Doing it during gimplification would be easy, if perhaps rather > > > ugly. If there are indeed several processors with this oddity, > > > then it would even make a certain degree of sense as a > > > target-independent option. > > x86, x86-64, S/390, as far as I'm aware. > > > > MIPS does *not* seem to suffer from this 'defect', so a target > independent solution that caused MIPS to generate worse code would be > bad.
To be clear, in my opinion, this should always be selected by an option, it should never be default behaviour for any target. Ian