[Bug fortran/66578] [F2008] Invalid free on allocate(...,source=a(:)) in block

["tkoenig at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66578

--- Comment #9 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
(In reply to Mikael Morin from comment #8)
> diff --git a/gcc/fortran/trans-array.c b/gcc/fortran/trans-array.c
> index fece3ab..0b96de1 100644
> --- a/gcc/fortran/trans-array.c
> +++ b/gcc/fortran/trans-array.c
> @@ -7079,7 +7077,7 @@ gfc_conv_expr_descriptor (gfc_se *se, gfc_expr *expr)
>  	    {
>  	      tmp = gfc_conv_array_lbound (desc, n);
>  	      tmp = fold_build2_loc (input_location, MINUS_EXPR,
> -				     TREE_TYPE (base), tmp, loop.from[dim]);
> +				     TREE_TYPE (base), tmp, from);
>  	      tmp = fold_build2_loc (input_location, MULT_EXPR,
>  				     TREE_TYPE (base), tmp,
>  				     gfc_conv_array_stride (desc, n));

Unfortunately, this does not appear to fix the bug (at least not completely).
I still get an invalid free.
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From: "glisse at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/64130] vrp: handle non zero constant divided by range cannot be zero.
Date: Fri, 19 Jun 2015 06:42:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idd130

--- Comment #6 from Marc Glisse <glisse at gcc dot gnu.org> ---
(In reply to kugan from comment #5)
> I think it should be in from front-end?

?

> Tried fixing it in VRP like:

You don't seem to use ranges at all. This might be the right place to implement
the suggestion from comment #2 (though if it does not use ranges, match.pd
would be better), but for the original optimization, what you want to improve
is the computation of the range of a division. When a has range [0, 4294967295]
we compute for 2305843009213693951 / a the range [0, 2305843009213693951] which
is not optimal, the left bound should be 536870912 not 0. If the good interval
is computed, VRP will automatically fold == 0 to false without extra code. We
already get this right when a has range [1, 4294967295].