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Re: [PATCH] Fix PR47286
On Fri, 14 Jan 2011, Michael Matz wrote:
> Hi,
>
> On Fri, 14 Jan 2011, Richard Guenther wrote:
>
> > This fixes points-to analysis of local register variables. We have to
> > assume that you can reach all global vars via them and that everything
> > stored to them escapes.
>
> That is false. We have to assume this for register variables bound to a
> hard-reg, not for normal variables with register storage class.
>
> > --- 413,422 ----
> > ret->is_global_var = (t == NULL_TREE);
> > ret->is_fn_info = false;
> > if (t && DECL_P (t))
> > ! ret->is_global_var = (is_global_var (t)
> > ! /* We have to treat even local register variables
> > ! as escape points. */
> > ! || (TREE_CODE (t) == VAR_DECL && DECL_REGISTER (t)));
>
> You want to check DECL_HARD_REGISTER. The above would also make
>
> register int x;
>
> an escape point, although this is simply a normal local variable that you
> can't take the address of.
I have applied the following (but C doesn't seem to set DECL_HARD_REGISTER
for global reg vars). The ME seems to use DECL_REGISTER and
DECL_HARD_REGISTER in various inconsistent ways btw ...
2011-01-14 Richard Guenther <rguenther@suse.de>
* tree-ssa-structalias.c (new_var_info): Use DECL_HARD_REGISTER.
Index: gcc/tree-ssa-structalias.c
===================================================================
*** gcc/tree-ssa-structalias.c (revision 168783)
--- gcc/tree-ssa-structalias.c (working copy)
*************** new_var_info (tree t, const char *name)
*** 416,422 ****
ret->is_global_var = (is_global_var (t)
/* We have to treat even local register variables
as escape points. */
! || (TREE_CODE (t) == VAR_DECL && DECL_REGISTER (t)));
ret->solution = BITMAP_ALLOC (&pta_obstack);
ret->oldsolution = BITMAP_ALLOC (&oldpta_obstack);
ret->next = NULL;
--- 416,423 ----
ret->is_global_var = (is_global_var (t)
/* We have to treat even local register variables
as escape points. */
! || (TREE_CODE (t) == VAR_DECL
! && DECL_HARD_REGISTER (t)));
ret->solution = BITMAP_ALLOC (&pta_obstack);
ret->oldsolution = BITMAP_ALLOC (&oldpta_obstack);
ret->next = NULL;