Re: [PATCH] Fix PR50494

[Jakub Jelinek <jakub at redhat dot com>]

On Wed, Feb 13, 2013 at 01:04:04PM +0100, Richard Biener wrote:
> 2013-02-13  Richard Biener  <rguenther@suse.de>
> 
> 	PR lto/50494
> 	* varasm.c (output_constant_def_1): Get the decl representing
> 	the constant as argument.
> 	(output_constant_def): Wrap output_constant_def_1.
> 	(make_decl_rtl): Use output_constant_def_1 with the decl
> 	representing the constant.
> 	(build_constant_desc): Optionally re-use a decl already
> 	representing the constant.
> 	(tree_output_constant_def): Adjust.

Looks good to me, except formatting nit:

> + /* Like output_constant_def but create a new decl representing the
> +    constant if necessary.  */
> + 
> + rtx
> + output_constant_def (tree exp, int defer)
> + {
> +   return  output_constant_def_1  (exp, NULL_TREE, defer);

Twice too many spaces.

But I'd say we should also add some varasm.c function that
increase_alignment should call for
(TREE_CODE (decl) == VAR_DECL && DECL_IN_CONSTANT_POOL (decl))
vars upon increasing alignment of the decl, which would do something like:
void
adjust_const_pool_alignment (tree decl)
{
  struct constant_descriptor_tree *desc, key;

  gcc_assert (TREE_CODE (decl) == VAR_DECL && DECL_IN_CONSTANT_POOL (decl));
  key.value = DECL_INITIAL (decl);
  key.hash = const_hash_1 (DECL_INITIAL (decl));
  desc = (struct constant_descriptor_tree *)
	 htab_find_with_hash (const_desc_htab, &key, key.hash);
  if (desc && MEM_P (desc) && MEM_ALIGN (desc->rtl) < DECL_ALIGN (decl))
    set_mem_align (desc->rtl, DECL_ALIGN (decl));
}
(completely untested).  Because, if we force the constant to be aligned
more than it would be by default, the RTL optimizers should be told about
that too.

	Jakub