On Thu, Sep 18, 2014 at 8:57 PM, Bernd Schmidt <ber...@codesourcery.com> wrote: > On 09/12/2014 10:04 AM, Richard Biener wrote: >> >> On Thu, Sep 11, 2014 at 6:36 PM, Bernd Schmidt <ber...@codesourcery.com> >> wrote: >>> >>> I strongly disagree. It's the same as for any other integer - there's one >>> sign bit, and since there aren't any other bits, the number of sign bit >>> copies is always exactly 1. >> >> >> I agree about that. But I fail to see what goes wrong with the existing >> code in combine. Maybe the code simply doesn't work for >> GET_MODE_PRECISION != GET_MODE_BITSIZE? > > > I had to debug it again - the patch was a year old. This time I came to the > conclusion that we're just using the wrong mode. We're trying to simplify > (ne:BI (reg:HI x) (const_int 0)), and the code here was using BImode when > calling num_sign_bit_copies for the register - what I think it wants to do > is verify that the operand consists of all zeros or all ones. > > Digging a bit further I noticed that some of the cases around this code have > a mode == GET_MODE (op0) test. These were added by rth in commit 3573fd048, > which added BImode. It looks like this particular case slipped through the > cracks. The easiest way to fix it is the below - bootstrapped and tested on > x86_64-linux, ok if it also works with ptx?
Ok. Thanks, Richard. > > Bernd >
