Fix constant folding of SWTCH statements

Hi,
the following testcase from testsuite fails to get switch value folded
to constant before it reach cfgexpand.  The problem is twofold.  First
we require ctor to have TREE_STATIC (for some reason) that is not set by
tree-switch-conversion.c. Secondly we screw up for variables introduced
late because we do not compute varpool_decide_const_value_known.

Fixed thus,
Bootstrapped/regtested x86_64-linux, OK?
Honza
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-optimized" } */
void bar (unsigned int);

void
foo (void)
{
  char buf[1] = { 3 };
  const char *p = buf;
  const char **q = &p;
  unsigned int ch;
  switch (**q)
    {
    case 1:  ch = 5; break;
    case 2:  ch = 4; break;
    case 3:  ch = 3; break;
    case 4:  ch = 2; break;
    case 5:  ch = 1; break;
    default: ch = 0; break;
    }
  bar (ch);
}
/* The switch should be switch converted and later constant propagated.  */
/* { dg-final { scan-tree-dump-not "CSWTCH.1.2" "optimized"} } */

	* tree-switch-conversion.c (build_one_array): Set ctor static flag.
	* varpool.c (varpool_finalize_decl): Set const_value_known.

On Sat, 4 Sep 2010, Jan Hubicka wrote:

> Hi,
> the following testcase from testsuite fails to get switch value folded
> to constant before it reach cfgexpand.  The problem is twofold.  First
> we require ctor to have TREE_STATIC (for some reason) that is not set by
> tree-switch-conversion.c. Secondly we screw up for variables introduced
> late because we do not compute varpool_decide_const_value_known.
> 
> Fixed thus,
> Bootstrapped/regtested x86_64-linux, OK?

Ok.

Thanks,
Richard.

> Honza
> /* { dg-do compile } */
> /* { dg-options "-O2 -fdump-tree-optimized" } */
> void bar (unsigned int);
> 
> void
> foo (void)
> {
>   char buf[1] = { 3 };
>   const char *p = buf;
>   const char **q = &p;
>   unsigned int ch;
>   switch (**q)
>     {
>     case 1:  ch = 5; break;
>     case 2:  ch = 4; break;
>     case 3:  ch = 3; break;
>     case 4:  ch = 2; break;
>     case 5:  ch = 1; break;
>     default: ch = 0; break;
>     }
>   bar (ch);
> }
> /* The switch should be switch converted and later constant propagated.  */
> /* { dg-final { scan-tree-dump-not "CSWTCH.1.2" "optimized"} } */
> 
> 	* tree-switch-conversion.c (build_one_array): Set ctor static flag.
> 	* varpool.c (varpool_finalize_decl): Set const_value_known.
> Index: tree-switch-conversion.c
> ===================================================================
> --- tree-switch-conversion.c	(revision 163808)
> +++ tree-switch-conversion.c	(working copy)
> @@ -518,6 +518,7 @@ build_one_array (gimple swtch, int num, 
>        array_type = build_array_type (value_type, arr_index_type);
>        ctor = build_constructor (array_type, info.constructors[num]);
>        TREE_CONSTANT (ctor) = true;
> +      TREE_STATIC (ctor) = true;
>  
>        decl = build_decl (loc, VAR_DECL, NULL_TREE, array_type);
>        TREE_STATIC (decl) = 1;
> Index: varpool.c
> ===================================================================
> --- varpool.c	(revision 163808)
> +++ varpool.c	(working copy)
> @@ -423,6 +423,7 @@ varpool_finalize_decl (tree decl)
>       there.  */
>    else if (TREE_PUBLIC (decl) && !DECL_COMDAT (decl) && !DECL_EXTERNAL (decl))
>      varpool_mark_needed_node (node);
> +  node->const_value_known |= varpool_decide_const_value_known (node);
>    if (cgraph_global_info_ready)
>      varpool_assemble_pending_decls ();
>  }
> 
>