Re: [PATCH] Fix middle-end/81737

[Marek Polacek]

On Mon, Aug 07, 2017 at 04:07:49PM +0200, Richard Biener wrote:
> On August 7, 2017 11:09:59 AM GMT+02:00, Marek Polacek <pola...@redhat.com> 
> wrote:
> >On Mon, Aug 07, 2017 at 10:58:09AM +0200, Jakub Jelinek wrote:
> >> On Mon, Aug 07, 2017 at 10:47:51AM +0200, Marek Polacek wrote:
> >> > In my recent change I failed to check whether the type domain
> >> > of a type is non-NULL and this goof causes crashing on this
> >> > testcase.
> >> > 
> >> > Bootstrapped/regtested on x86_64-linux, ok for trunk?
> >> > 
> >> > 2017-08-07  Marek Polacek  <pola...@redhat.com>
> >> > 
> >> >  PR middle-end/81737
> >> >  * fold-const.c (fold_indirect_ref_1): Check type_domain.
> >> > 
> >> >  * gcc.dg/pr81737.c: New test.
> >> 
> >> The old code was assuming size_zero_node if type_domain is NULL
> >> or TYPE_MIN_VALUE is NULL, which is reasonable for C/C++, but indeed
> >might
> >> be wrong perhaps for Fortran or Ada.
> 
> It's how the middle-end defines it, so please restore this behavior (sorry 
> for missing this in the review).  IIRC there are at least one other 'copy' of 
> the folding somewhere.

Sure, this patch should do it:

Bootstrapped/regtested on x86_64-linux, ok for trunk?

2017-08-08  Marek Polacek  <pola...@redhat.com>

        PR middle/81695
        * fold-const.c (fold_indirect_ref_1): Restore original behavior
        regarding size_zero_node.

diff --git gcc/fold-const.c gcc/fold-const.c
index 5a118ca50a1..2c47d1d16a4 100644
--- gcc/fold-const.c
+++ gcc/fold-const.c
@@ -14109,22 +14109,21 @@ fold_indirect_ref_1 (location_t loc, tree type, tree 
op0)
                   && type == TREE_TYPE (op00type))
            {
              tree type_domain = TYPE_DOMAIN (op00type);
-             tree min;
+             tree min = size_zero_node;
              if (type_domain != NULL_TREE
-                 && (min = TYPE_MIN_VALUE (type_domain))
+                 && TYPE_MIN_VALUE (type_domain)
                  && TREE_CODE (min) == INTEGER_CST)
+               min = TYPE_MIN_VALUE (type_domain);
+             offset_int off = wi::to_offset (op01);
+             offset_int el_sz = wi::to_offset (TYPE_SIZE_UNIT (type));
+             offset_int remainder;
+             off = wi::divmod_trunc (off, el_sz, SIGNED, &remainder);
+             if (remainder == 0)
                {
-                 offset_int off = wi::to_offset (op01);
-                 offset_int el_sz = wi::to_offset (TYPE_SIZE_UNIT (type));
-                 offset_int remainder;
-                 off = wi::divmod_trunc (off, el_sz, SIGNED, &remainder);
-                 if (remainder == 0)
-                   {
-                     off = off + wi::to_offset (min);
-                     op01 = wide_int_to_tree (sizetype, off);
-                     return build4_loc (loc, ARRAY_REF, type, op00, op01,
-                                        NULL_TREE, NULL_TREE);
-                   }
+                 off = off + wi::to_offset (min);
+                 op01 = wide_int_to_tree (sizetype, off);
+                 return build4_loc (loc, ARRAY_REF, type, op00, op01,
+                                    NULL_TREE, NULL_TREE);
                }
            }
        }

        Marek