https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69368
--- Comment #72 from rguenther at suse dot de <rguenther at suse dot de> --- On Tue, 23 Feb 2016, Richard Biener wrote: > On Tue, 23 Feb 2016, jakub at gcc dot gnu.org wrote: > > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69368 > > > > --- Comment #70 from Jakub Jelinek <jakub at gcc dot gnu.org> --- > > If you want to go this way, I'd at least key it off DECL_COMMON on the decl. > > And instead of multiplying max_size by 2 perhaps just add BITS_PER_UNIT? > > Works for me. > > > And only if it is equal to size? > > That's already done. Patch as posted passed bootstrap & regtest. Adjusted according to comments but not tested otherwise - please somebody throw at unpatched 416.gamess. Index: gcc/tree-dfa.c =================================================================== --- gcc/tree-dfa.c (revision 233620) +++ gcc/tree-dfa.c (working copy) @@ -617,7 +617,20 @@ get_ref_base_and_extent (tree exp, HOST_ if (maxsize == -1 && DECL_SIZE (exp) && TREE_CODE (DECL_SIZE (exp)) == INTEGER_CST) - maxsize = wi::to_offset (DECL_SIZE (exp)) - bit_offset; + { + maxsize = wi::to_offset (DECL_SIZE (exp)) - bit_offset; + /* If we've seen a variable array ref and the above adjusted + maxsize to size make sure the caller doesn't mistake this + as a non-variable access by adjusting maxsize slightly. + ??? This is strictly pessimizing the case where a + one element array is accessed with a variable index + which should be a rare case in practice but hits legacy + fortran code - see PR69368 for example. */ + if (seen_variable_array_ref + && maxsize == bitsize + && DECL_COMMON (exp)) + maxsize += BITS_PER_UNIT; + } } else if (CONSTANT_CLASS_P (exp)) {
