On Tue, 20 Sep 2016, Jakub Jelinek wrote:
> Hi!
>
> fold_builtin_atomic_always_lock_free has an assertion that if the 2nd
> argument isn't INTEGER_CST, it has POINTER_TYPE_P, but additionally for
> casts to void * it looks through the cast. That means though for invalid
> code if an integral expression etc. is converted to pointer, we violate the
> assertion. This patch instead doesn't look through such casts, so
> type_align is effectively alignment of void and thus it considers objects
> insufficiently aligned, but doesn't ICE.
>
> Another approach (incomplete) is what I've attached to the PR - instead of
> prototyping __atomic_{always,is}_lock_free it uses ... and only checks that
> it has 2 arguments and that the last one is a pointer - that way we don't
> have to try to undo implicit cast to void * and know the conversion in there
> is the user conversion. Unfortunately the C++ FE isn't prepared for the
> check_builtin_function_arguments to change the arguments (unlike C).
>
> I've bootstrapped/regtested on x86_64-linux and i686-linux the following
> fix, ok for trunk, or should I invest more time into the other approach?
Ok for trunk. I think the other solution would be to somehow mark the
builtin to not get the (void *) cast applied in the first place ...
(make it varargs?)
Thanks,
Richard.
> 2016-09-19 Jakub Jelinek
>
> PR middle-end/77624
> * builtins.c (fold_builtin_atomic_always_lock_free): Only look through
> cast to void * if the cast is from some other pointer type.
>
> * c-c++-common/pr77624-1.c: New test.
> * c-c++-common/pr77624-2.c: New test.
>
> --- gcc/builtins.c.jj 2016-09-16 22:19:38.0 +0200
> +++ gcc/builtins.c2016-09-19 15:28:41.100412521 +0200
> @@ -5575,8 +5575,10 @@ fold_builtin_atomic_always_lock_free (tr
>end before anything else has a chance to look at it. The pointer
>parameter at this point is usually cast to a void *, so check for that
>and look past the cast. */
> - if (CONVERT_EXPR_P (arg1) && POINTER_TYPE_P (ttype)
> - && VOID_TYPE_P (TREE_TYPE (ttype)))
> + if (CONVERT_EXPR_P (arg1)
> + && POINTER_TYPE_P (ttype)
> + && VOID_TYPE_P (TREE_TYPE (ttype))
> + && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (arg1, 0
> arg1 = TREE_OPERAND (arg1, 0);
>
>ttype = TREE_TYPE (arg1);
> --- gcc/testsuite/c-c++-common/pr77624-1.c.jj 2016-09-19 15:18:09.049394093
> +0200
> +++ gcc/testsuite/c-c++-common/pr77624-1.c2016-09-19 15:41:09.972949880
> +0200
> @@ -0,0 +1,14 @@
> +/* PR middle-end/77624 */
> +/* { dg-do compile } */
> +
> +int
> +foo (int a)
> +{
> + return __atomic_is_lock_free (2, a); /* { dg-warning
> "pointer from integer" "" { target c } } */
> +}/* { dg-error "invalid
> conversion" "" { target c++ } 7 } */
> +
> +int
> +bar (int a)
> +{
> + return __atomic_always_lock_free (2, a); /* { dg-warning "pointer from
> integer" "" { target c } } */
> +}/* { dg-error "invalid
> conversion" "" { target c++ } 13 } */
> --- gcc/testsuite/c-c++-common/pr77624-2.c.jj 2016-09-19 15:18:12.280353292
> +0200
> +++ gcc/testsuite/c-c++-common/pr77624-2.c2016-09-19 15:42:37.441844581
> +0200
> @@ -0,0 +1,26 @@
> +/* PR middle-end/77624 */
> +/* { dg-do compile } */
> +
> +void
> +foo (int *a)
> +{
> + double b = 0;
> + __atomic_is_lock_free (2, a, 2); /* { dg-error "too many arguments" } */
> + __atomic_is_lock_free (2); /* { dg-error "too few arguments" } */
> + __atomic_is_lock_free (2, b); /* { dg-error "incompatible
> type" "" { target c } } */
> + /* { dg-message "expected" "" { target
> c } 10 } */
> + /* { dg-error "convert" "" { target c++
> } 10 } */
> + __atomic_is_lock_free (2, 0);
> +}
> +
> +void
> +bar (int *a)
> +{
> + double b = 0;
> + __atomic_always_lock_free (2, a, 2); /* { dg-error "too many
> arguments" } */
> + __atomic_always_lock_free (2); /* { dg-error "too few arguments" } */
> + __atomic_always_lock_free (2, b); /* { dg-error "incompatible type" "" {
> target c } } */
> + /* { dg-message "expected" "" { target
> c } 22 } */
> + /* { dg-error "convert" "" { target c++
> } 22 } */
> + __atomic_always_lock_free (2, 0);
> +}
>
> Jakub
>
>
--
Richard Biener
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB
21284 (AG Nuernberg)
