Re: PR tree-opt/33614: ICE when optimising a "constant" vector constructor

["Andrew Pinski" <pinskia at gmail dot com>]

On 10/1/07, Richard Sandiford <rsandifo@nildram.co.uk> wrote:

> Index: gcc/gimplify.c
> ===================================================================
> --- gcc/gimplify.c      2007-10-01 23:23:20.000000000 +0100
> +++ gcc/gimplify.c      2007-10-01 23:24:13.000000000 +0100
> @@ -3291,10 +3291,8 @@ gimplify_init_constructor (tree *expr_p,
>                 break;
>               }
>
> -           /* Don't reduce a TREE_CONSTANT vector ctor even if we can't
> -              make a VECTOR_CST.  It won't do anything for us, and it'll
> -              prevent us from representing it as a single constant.  */
> -           break;
> +           TREE_CONSTANT (ctor) = 0;
> +           TREE_INVARIANT (ctor) = 0;
>           }
>
>         /* Vector types use CONSTRUCTOR all the way through gimple

Doing this will loose some optimizations with vectors.  The main
reason why is because &a is not a CONSTANT_CLASS but still can be
constant..

Also can you look at the following testcase (with -O2 -msse):
int t[4];

__attribute__((vector_size(16))) int f(void)
{
__attribute__((vector_size(16))) int t1 = {(int)&t[0], (int)&t[1], (int)&t[2],
(int)&t[3]};
  return t1;
}

And make sure we don't regress.
Right now we get:
f:
        pushl   %ebp
        movdqa  .LC0, %xmm0
        popl    %ebp
        ret
.LC0:
        .long   t
        .long   t+4
        .long   t+8
        .long   t+12
Which is better than what we got in 4.0.2.