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.
