https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80072
--- Comment #8 from rguenther at suse dot de <rguenther at suse dot de> --- On Wed, 22 Mar 2017, jakub at gcc dot gnu.org wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80072 > > --- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> --- > So, found a bug and its bugfix fixes the testcase, but still need to figure > out > what actually was going on, if it was just that we made (correct) assumptions > that constants won't be weirdly sorted, or if there is some other (with this > patch latent) bug. > > --- gcc/tree-ssa-reassoc.c.jj 2017-02-10 09:46:50.000000000 +0100 > +++ gcc/tree-ssa-reassoc.c 2017-03-22 13:13:33.608745625 +0100 > @@ -510,7 +510,7 @@ sort_by_operand_rank (const void *pa, co > > /* Lastly, make sure the versions that are the same go next to each > other. */ > - if ((oeb->rank - oea->rank == 0) > + if (oeb->rank == oea->rank > && TREE_CODE (oea->op) == SSA_NAME > && TREE_CODE (oeb->op) == SSA_NAME) > { > @@ -549,7 +549,7 @@ sort_by_operand_rank (const void *pa, co > } > > if (oeb->rank != oea->rank) > - return oeb->rank - oea->rank; > + return oeb->rank > oea->rank ? 1 : -1; > else > return oeb->id - oea->id; > } > > ->rank is unsigned int, and on the huge testcase it is over 0x7fffffff, so > (int) (oeb->rank > oea->rank) doesn't do what it expects and we happily sort > a SSA_NAME with extra high rank after constants, which e.g. means we can't > merge them together. Ick ;) Patch looks obvious. For clarity the else return oeb->id - oea->id should probably be adjusted similarly (and id made unsigned...).
