[C++ PATCH] Fix ICE on offsetof with volatile struct and static data member array ref (PR c++/85061)

Jason Merrill jason@redhat.com
Tue Mar 27 19:53:00 GMT 2018


OK.

On Tue, Mar 27, 2018 at 4:54 AM, Jakub Jelinek <jakub@redhat.com> wrote:
> Hi!
>
> The following testcase ICEs, because we assert that we see a COMPOUND_EXPR
> only for static data member in a volatile struct, but as the testcase shows,
> we can see it also if using some component of the static data member.
>
> Fixed by using get_base_address, plus, as the check isn't as cheap as
> before, turn the assert into a checking assert only.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>
> 2018-03-27  Jakub Jelinek  <jakub@redhat.com>
>
>         PR c++/85061
>         * c-common.c (fold_offsetof_1) <case COMPOUND_EXPR>: Assert that
>         get_base_address of the second operand is a VAR_P, rather than the
>         operand itself, and use gcc_checking_assert instead of gcc_assert.
>
>         * g++.dg/ext/builtin-offsetof3.C: New test.
>
> --- gcc/c-family/c-common.c.jj  2018-03-13 00:38:23.809662252 +0100
> +++ gcc/c-family/c-common.c     2018-03-24 15:21:36.171485128 +0100
> @@ -6272,7 +6272,7 @@ fold_offsetof_1 (tree expr, enum tree_co
>      case COMPOUND_EXPR:
>        /* Handle static members of volatile structs.  */
>        t = TREE_OPERAND (expr, 1);
> -      gcc_assert (VAR_P (t));
> +      gcc_checking_assert (VAR_P (get_base_address (t)));
>        return fold_offsetof_1 (t);
>
>      default:
> --- gcc/testsuite/g++.dg/ext/builtin-offsetof3.C.jj     2018-03-26 11:54:54.338627270 +0200
> +++ gcc/testsuite/g++.dg/ext/builtin-offsetof3.C        2018-03-26 11:54:07.992610454 +0200
> @@ -0,0 +1,14 @@
> +// PR c++/85061
> +// { dg-do compile }
> +
> +struct B { int a, b; };
> +struct A
> +{
> +  static int x[2];
> +  static int y;
> +  static B z;
> +};
> +
> +int i = __builtin_offsetof (volatile A, x[0]); // { dg-error "cannot apply 'offsetof' to static data member 'A::x'" }
> +int j = __builtin_offsetof (volatile A, y);    // { dg-error "cannot apply 'offsetof' to static data member 'A::y'" }
> +int k = __builtin_offsetof (volatile A, z.a);  // { dg-error "cannot apply 'offsetof' to a non constant address" }
>
>         Jakub



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