On Thu, 1 Jul 2021, Michael Matz wrote: > Hello, > > On Thu, 1 Jul 2021, Richard Biener wrote: > > > diff --git a/gcc/gimple-loop-interchange.cc b/gcc/gimple-loop-interchange.cc > > index 43045c5455e..43ef112a2d0 100644 > > --- a/gcc/gimple-loop-interchange.cc > > +++ b/gcc/gimple-loop-interchange.cc > > @@ -1043,8 +1043,11 @@ tree_loop_interchange::valid_data_dependences > > (unsigned i_idx, unsigned o_idx, > > continue; > > > > /* Be conservative, skip case if either direction at i_idx/o_idx > > - levels is not '=' (for the inner loop) or '<'. */ > > - if (dist_vect[i_idx] < 0 || dist_vect[o_idx] <= 0) > > + levels is not '=' or '<'. */ > > + if (dist_vect[i_idx] < 0 > > + || (DDR_REVERSED_P (ddr) && dist_vect[i_idx] > 0) > > + || dist_vect[o_idx] < 0 > > + || (DDR_REVERSED_P (ddr) && dist_vect[o_idx] > 0)) > > Hmm, if DDR_REVERSED_P matters here, then it should matter for all arms. > IOW: < 0 should be tested only when !DDR_REVERSED_P, not always: > > if ((!DDR_REVERSED_P (ddr) && dist_vect[i_idx] < 0) > || (DDR_REVERSED_P (ddr) && dist_vect[i_idx] > 0) > || (!DDR_REVERSED_P (ddr) && dist_vect[o_idx] < 0) > || (DDR_REVERSED_P (ddr) && dist_vect[o_idx] > 0)) > > (what you have effectively written is a condition that allows only 0 when > DDR_REVERSED_P)
True - been fixing bugs too fast I guess. Maybe the 3rd time's the charm then ;) Richard.
