https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126303
--- Comment #4 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-16 branch has been updated by Jakub Jelinek <[email protected]>: https://gcc.gnu.org/g:0a9e52931016938c35f9944acc870650f3e8492f commit r16-9416-g0a9e52931016938c35f9944acc870650f3e8492f Author: Jakub Jelinek <[email protected]> Date: Mon Jul 27 18:54:37 2026 +0200 fortran: Fix ICE with loops with (deprecated) non-integral iterators [PR126303] do_subscript contains do_sym = dl->ext.iterator->var->symtree->n.sym; if (do_sym->ts.type != BT_INTEGER) continue; check to ignore loops with non-integral iterator. But r15-11154 PR94978 change has added inner_loop_may_be_skipped function and that happily accesses inner loop iterator's step, start and end if EXPR_CONSTANT with mpz_init_set (..., ...value.integer); Now, given the layout of mpfr_t (usually long, int, long, pointer) and mpz_t (usually int, int, pointer), this sometimes just produces silently garbage (e.g. on 64-bit little-endian, where the second int in mpz_t is the most significant 32-bits of _mpfr_prec and so usually 0 and so _mp_size is 0 and nothing is dereferenced: p loop->ext.iterator->step.value.real $1 = {{_mpfr_prec = 24, _mpfr_sign = 1, _mpfr_exp = 1, _mpfr_d = 0x4eac658}} p loop->ext.iterator->step.value.integer $2 = {{_mp_alloc = 24, _mp_size = 0, _mp_d = 0x1}} or it ICEs somewhere in gmp (on 32-bit little-endian, e.g. i686, or big-endian, e.g. s390x), because _mp_size is in that case _mpfr_sign but _mp_d is _mpfr_exp (32-bit little-endian), or _mp_size is least significant part of _mpfr_prec, in both cases non-zero, but _mp_d is not a usable pointer in either case. The following patch fixes that by punting for inner loops with non-integral iterator. 2026-07-27 Jakub Jelinek <[email protected]> PR fortran/126303 * frontend-passes.cc (inner_loop_may_be_skipped): If inner loop iterator is not integral, return true. * gfortran.dg/pr126303.f: New test. Reviewed-by: Jerry DeLisle <[email protected]> (cherry picked from commit 822ce7e451fdbbeeca2df5d8ddbdf6bccc254abb)
