https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102581
--- Comment #8 from Jan Hubicka <hubicka at ucw dot cz> --- Actually, this is shorter patch - we already should notice that one range is contained in other, but we give up too early. Honza diff --git a/gcc/ipa-modref-tree.h b/gcc/ipa-modref-tree.h index 6a9ed5ce54b..8e9b89b3e2c 100644 --- a/gcc/ipa-modref-tree.h +++ b/gcc/ipa-modref-tree.h @@ -110,8 +110,11 @@ struct GTY(()) modref_access_node if (!a.parm_offset_known) return false; /* Accesses are never below parm_offset, so look - for smaller offset. */ - if (!known_le (parm_offset, a.parm_offset)) + for smaller offset. + If access ranges are known still allow merging + when bit offsets comparsion passes. */ + if (!known_le (parm_offset, a.parm_offset) + && !range_info_useful_p ()) return false; aoffset_adj = (a.parm_offset - parm_offset) << LOG2_BITS_PER_UNIT; @@ -618,6 +621,7 @@ private: found = true; if (!found && n->merge (*a, false)) found = restart = true; + gcc_checking_assert (found || !a->merge (*n, false)); if (found) { accesses->unordered_remove (i);