Re: [PATCH] make vector CONSTRUCTOR with TREE_CONSTANT true, min invariant

[Andrew Pinski <pinskia at gmail dot com>]

On Tue, 2006-12-19 at 18:57 -0800, Ian Lance Taylor wrote:
> Andrew Pinski <pinskia@gmail.com> writes:
> 
> > We should treat vector CONSTRUCTOR with TREE_CONSTANT set as min
> > invariant since we no longer look into them to gimplify them and they
> > are constants so we should be able to treat them as such now.
> 
> gimplify_init_constructor in gimplify.c finds it necessary to check
> each value.  It seems to me that code like would be required here,
> too.  Which may make it inappropriate.

> In general it seems to me that we should find some way to pass these
> CONSTRUCTORs to build_vector_from_ctor.  It doesn't seem reasonable to
> try to work around the fact that we don't do that.

Yes we check each element for a constant tree but we also don't look
past a TREE_CONSTANT vector CONSTRUCTOR when gimplifing any more:
> /* 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.  */

Which seems like we should make this case still a min invariant as
explained by the above comment which is in gimplify_init_constructor.

Thanks,
Andrew Pinski