Fortran patch ping (Re: [PATCH] fortran: Fix ICE with loops with (deprecated) non-integral iterators [PR126303])

Hi!

On Mon, Jul 20, 2026 at 09:18:48AM +0200, Jakub Jelinek wrote:
> 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.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk and
> affected release branches (I think 14+, the patch has been backported)?

I'd like to ping this patch
https://gcc.gnu.org/pipermail/fortran/2026-July/064347.html

Thanks.

> 2026-07-20  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.

	Jakub