Re: [PATCH] libgccjit: Add support for types used by atomic builtins [PR96066] [PR96067]

[David Malcolm <dmalcolm@redhat.com>]

On Mon, 2021-05-17 at 21:02 -0400, Antoni Boucher via Jit wrote:
> Hello.
> This patch fixes the issue with using atomic builtins in libgccjit.
> Thanks to review it.

[...snip...]
 
> diff --git a/gcc/jit/jit-recording.c b/gcc/jit/jit-recording.c
> index 117ff70114c..de876ff9fa6 100644
> --- a/gcc/jit/jit-recording.c
> +++ b/gcc/jit/jit-recording.c
> @@ -2598,8 +2598,18 @@ recording::memento_of_get_pointer::accepts_writes_from (type *rtype)
>      return false;
>  
>    /* It's OK to assign to a (const T *) from a (T *).  */
> -  return m_other_type->unqualified ()
> -    ->accepts_writes_from (rtype_points_to);
> +  if (m_other_type->unqualified ()
> +    ->accepts_writes_from (rtype_points_to)) {
> +      return true;
> +  }
> +
> +  /* It's OK to assign to a (volatile const T *) from a (volatile const T *). */
> +  if (m_other_type->unqualified ()->unqualified ()
> +    ->accepts_writes_from (rtype_points_to->unqualified ())) {
> +      return true;
> +  }

Presumably you need this to get the atomic builtins working?

If I'm reading the above correctly, the new test doesn't distinguish
between the 3 different kinds of qualifiers (aligned, volatile, and
const), it merely tries to strip some of them off.

It's not valid to e.g. assign to a (aligned T *) from a (const T *).

Maybe we need an internal enum to discriminate between different
subclasses of decorated_type?


> +
> +  return false;
>  }
>  
>  /* Implementation of pure virtual hook recording::memento::replay_into
> diff --git a/gcc/testsuite/jit.dg/all-non-failing-tests.h b/gcc/testsuite/jit.dg/all-non-failing-tests.h
> index 4202eb7798b..dfc6596358c 100644
> --- a/gcc/testsuite/jit.dg/all-non-failing-tests.h
> +++ b/gcc/testsuite/jit.dg/all-non-failing-tests.h
> @@ -181,6 +181,13 @@
>  #undef create_code
>  #undef verify_code
>  
> +/* test-builtin-types.c */
> +#define create_code create_code_builtin_types
> +#define verify_code verify_code_builtin_types
> +#include "test-builtin-types.c"
> +#undef create_code
> +#undef verify_code
> +
>  /* test-hello-world.c */
>  #define create_code create_code_hello_world
>  #define verify_code verify_code_hello_world

As with various other patches, this needs to also add a new entry to
the "testcases" array making use of the new
{create|verify}_code_builtin_types functions.

[...snip...]

Hope this is constructive
Dave