RE: [PATCH] Fix PR tree-optimization/58137

[Bernd Edlinger <bernd dot edlinger at hotmail dot de>]

On Tue, 3 Sep 2013 10:38:33, Richard Biener wrote:
> I'd rather go with the simple fix as the issue in forwprop is at least
> latent. We can
> improve on the code-gen as followup where I believe handling of
> POINTER_PLUS_EXPR
> would need to be added (that we avoid POINTER_PLUS_EXPR for vectors is a bug).
> That can be done in a way to cover the vector case properly. Or
> finally properly
> use POINTER_PLUS_EXPR for vectors or make the vectorizer not use pointer
> types but a corresponding unsigned integer type for them (that would also fix
> the original bug of course). Like with (untested)
>
> Index: gcc/tree-vect-stmts.c
> ===================================================================
> --- gcc/tree-vect-stmts.c (revision 202196)
> +++ gcc/tree-vect-stmts.c (working copy)
> @@ -6179,8 +6179,7 @@ get_vectype_for_scalar_type_and_size (tr
> corresponding to that mode. The theory is that any use that
> would cause problems with this will disable vectorization anyway. */
> else if (!SCALAR_FLOAT_TYPE_P (scalar_type)
> - && !INTEGRAL_TYPE_P (scalar_type)
> - && !POINTER_TYPE_P (scalar_type))
> + && !INTEGRAL_TYPE_P (scalar_type))
> scalar_type = lang_hooks.types.type_for_mode (inner_mode, 1);
>
> /* We can't build a vector type of elements with alignment bigger than
>
> actually that would be my preference here ...

this would cause an ICE in test case 20000629-1.c...

So removing the pointer of vectors is not an option.

>>> The real fix is of course to make vector pointer operations properly
>>> use POINTER_PLUS_EXPR ...

Okay I can do what you want, and use POINTER_PLUS_EXPR for
vectors of pointers, and do the constant folding in assocate_pointerplus.
This way we get exactly the same code as before. It may be even possible
that this constant folding can improve something with scalars.

Bootstrapped and regression tested on x86_64-unknown-linux-gnu.

OK for trunk?

Bernd.

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