Re: [PATCH][RFC] Share variable annotations for globals across functions

[Richard Guenther <rguenther at suse dot de>]

On Thu, 22 May 2008, Richard Guenther wrote:

> 
> This removes the per-function variable annotation code we use for
> global variables.  A scheme like this is only needed if we have aliasing
> computed for multiple functions at a time.  For which we better find
> a different solution.  For PR36291 we have tons of referenced global
> vars (the usual chaining of global data problem) and tons of functions.
> This results in
> 
> tree-dfa.c:153 (create_var_ann) 482008296:30.4%    0: 0.0%  0: 0.0%  43818936:30.6%    5477367
> 
> and a peak memory usage of about 2GB on x86_64 (without checking but with
> mem-stats enabled).  If we share the variable annotations of globals
> this goes down to
> 
> tree-dfa.c:150 (create_var_ann)  206016: 0.0%   15094400: 3.2%  142592: 0.1%   0: 0.0%     241297
> 
> and a peak memory usage of about 1GB.
> 
> Bootstrapped and tested on x86_64-unknown-linux-gnu for C and C++
> (I expect I can remove the tree-ssa-alias.c hunk), full testing will 
> follow.
> 
> Diego, I suppose tuples doesn't change the above picture, so is the
> general idea ok?

Final patch appended.  Bootstrapped and tested on x86_64-unknown-linux-gnu
for all languages including ada.

Ok for mainline?

Thanks,
Richard.

2008-05-22  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/36291
	* tree-flow. h (struct gimple_df): Remove var_anns member.
	* tree-flow-inline.h (gimple_var_anns): Remove.
	(var_ann): Simplify.
	* tree-dfa.c (create_var_ann): Simplify.
	(remove_referenced_var): Clear alias info from var_anns of globals.
	* tree-ssa.c (init_tree_ssa): Do not allocate var_anns.
	(delete_tree_ssa): Clear alias info from var_anns of globals.
	Do not free var_anns.
	(var_ann_eq): Remove.
	(var_ann_hash): Likewise.

Index: gcc/tree-flow-inline.h
===================================================================
*** gcc/tree-flow-inline.h.orig	2008-05-22 21:53:47.000000000 +0200
--- gcc/tree-flow-inline.h	2008-05-22 21:54:39.000000000 +0200
*************** gimple_nonlocal_all (const struct functi
*** 91,104 ****
    return fun->gimple_df->nonlocal_all;
  }
  
- /* Hashtable of variables annotations.  Used for static variables only;
-    local variables have direct pointer in the tree node.  */
- static inline htab_t
- gimple_var_anns (const struct function *fun)
- {
-   return fun->gimple_df->var_anns;
- }
- 
  /* Initialize the hashtable iterator HTI to point to hashtable TABLE */
  
  static inline void *
--- 91,96 ----
*************** var_ann (const_tree t)
*** 192,213 ****
  {
    var_ann_t ann;
  
!   if (!MTAG_P (t)
!       && (TREE_STATIC (t) || DECL_EXTERNAL (t)))
!     {
!       struct static_var_ann_d *sann
!         = ((struct static_var_ann_d *)
! 	   htab_find_with_hash (gimple_var_anns (cfun), t, DECL_UID (t)));
!       if (!sann)
! 	return NULL;
!       ann = &sann->ann;
!     }
!   else
!     {
!       if (!t->base.ann)
! 	return NULL;
!       ann = (var_ann_t) t->base.ann;
!     }
  
    gcc_assert (ann->common.type == VAR_ANN);
  
--- 184,192 ----
  {
    var_ann_t ann;
  
!   if (!t->base.ann)
!     return NULL;
!   ann = (var_ann_t) t->base.ann;
  
    gcc_assert (ann->common.type == VAR_ANN);
  
Index: gcc/tree-dfa.c
===================================================================
*** gcc/tree-dfa.c.orig	2008-05-22 21:53:47.000000000 +0200
--- gcc/tree-dfa.c	2008-05-22 21:54:09.000000000 +0200
*************** var_ann_t
*** 142,174 ****
  create_var_ann (tree t)
  {
    var_ann_t ann;
-   struct static_var_ann_d *sann = NULL;
  
    gcc_assert (t);
    gcc_assert (DECL_P (t));
    gcc_assert (!t->base.ann || t->base.ann->common.type == VAR_ANN);
  
!   if (!MTAG_P (t) && (TREE_STATIC (t) || DECL_EXTERNAL (t)))
!     {
!       sann = GGC_CNEW (struct static_var_ann_d);
!       ann = &sann->ann;
!     }
!   else
!     ann = GGC_CNEW (struct var_ann_d);
! 
    ann->common.type = VAR_ANN;
! 
!   if (!MTAG_P (t) && (TREE_STATIC (t) || DECL_EXTERNAL (t)))
!     {
!        void **slot;
!        sann->uid = DECL_UID (t);
!        slot = htab_find_slot_with_hash (gimple_var_anns (cfun),
! 				        t, DECL_UID (t), INSERT);
!        gcc_assert (!*slot);
!        *slot = sann;
!     }
!   else
!     t->base.ann = (tree_ann_t) ann;
  
    return ann;
  }
--- 142,155 ----
  create_var_ann (tree t)
  {
    var_ann_t ann;
  
    gcc_assert (t);
    gcc_assert (DECL_P (t));
    gcc_assert (!t->base.ann || t->base.ann->common.type == VAR_ANN);
  
!   ann = GGC_CNEW (struct var_ann_d);
    ann->common.type = VAR_ANN;
!   t->base.ann = (tree_ann_t) ann;
  
    return ann;
  }
*************** remove_referenced_var (tree var)
*** 765,772 ****
  
    clear_call_clobbered (var);
    if ((v_ann = var_ann (var)))
!     ggc_free (v_ann);
!   var->base.ann = NULL;
    gcc_assert (DECL_P (var));
    in.uid = uid;
    loc = htab_find_slot_with_hash (gimple_referenced_vars (cfun), &in, uid,
--- 746,765 ----
  
    clear_call_clobbered (var);
    if ((v_ann = var_ann (var)))
!     {
!       /* Preserve var_anns of globals, but clear their alias info.  */
!       if (MTAG_P (var)
! 	  || (!TREE_STATIC (var) && !DECL_EXTERNAL (var)))
! 	{
! 	  ggc_free (v_ann);
! 	  var->base.ann = NULL;
! 	}
!       else
! 	{
! 	  v_ann->mpt = NULL_TREE;
! 	  v_ann->symbol_mem_tag = NULL_TREE;
! 	}
!     }
    gcc_assert (DECL_P (var));
    in.uid = uid;
    loc = htab_find_slot_with_hash (gimple_referenced_vars (cfun), &in, uid,
Index: gcc/tree-ssa.c
===================================================================
*** gcc/tree-ssa.c.orig	2008-05-22 21:53:47.000000000 +0200
--- gcc/tree-ssa.c	2008-05-22 22:41:24.000000000 +0200
*************** uid_decl_map_hash (const void *item)
*** 904,927 ****
    return ((const_tree)item)->decl_minimal.uid;
  }
  
- /* Return true if the uid in both int tree maps are equal.  */
- 
- static int
- var_ann_eq (const void *va, const void *vb)
- {
-   const struct static_var_ann_d *a = (const struct static_var_ann_d *) va;
-   const_tree const b = (const_tree) vb;
-   return (a->uid == DECL_UID (b));
- }
- 
- /* Hash a UID in a int_tree_map.  */
- 
- static unsigned int
- var_ann_hash (const void *item)
- {
-   return ((const struct static_var_ann_d *)item)->uid;
- }
- 
  /* Return true if the DECL_UID in both trees are equal.  */
  
  static int
--- 904,909 ----
*************** init_tree_ssa (struct function *fn)
*** 951,958 ****
  				     		    uid_decl_map_eq, NULL);
    fn->gimple_df->default_defs = htab_create_ggc (20, uid_ssaname_map_hash, 
  				                 uid_ssaname_map_eq, NULL);
-   fn->gimple_df->var_anns = htab_create_ggc (20, var_ann_hash, 
- 					     var_ann_eq, NULL);
    fn->gimple_df->call_clobbered_vars = BITMAP_GGC_ALLOC ();
    fn->gimple_df->addressable_vars = BITMAP_GGC_ALLOC ();
    init_ssanames (fn, 0);
--- 933,938 ----
*************** delete_tree_ssa (void)
*** 998,1006 ****
        set_phi_nodes (bb, NULL);
      }
  
!   /* Remove annotations from every referenced variable.  */
    FOR_EACH_REFERENCED_VAR (var, rvi)
      {
        if (var->base.ann)
          ggc_free (var->base.ann);
        var->base.ann = NULL;
--- 978,993 ----
        set_phi_nodes (bb, NULL);
      }
  
!   /* Remove annotations from every referenced local variable.  */
    FOR_EACH_REFERENCED_VAR (var, rvi)
      {
+       if (!MTAG_P (var)
+ 	  && (TREE_STATIC (var) || DECL_EXTERNAL (var)))
+ 	{
+ 	  var_ann (var)->mpt = NULL_TREE;
+ 	  var_ann (var)->symbol_mem_tag = NULL_TREE;
+ 	  continue;
+ 	}
        if (var->base.ann)
          ggc_free (var->base.ann);
        var->base.ann = NULL;
*************** delete_tree_ssa (void)
*** 1018,1025 ****
    
    htab_delete (cfun->gimple_df->default_defs);
    cfun->gimple_df->default_defs = NULL;
-   htab_delete (cfun->gimple_df->var_anns);
-   cfun->gimple_df->var_anns = NULL;
    cfun->gimple_df->call_clobbered_vars = NULL;
    cfun->gimple_df->addressable_vars = NULL;
    cfun->gimple_df->modified_noreturn_calls = NULL;
--- 1005,1010 ----
Index: gcc/tree-flow.h
===================================================================
*** gcc/tree-flow.h.orig	2008-05-22 21:54:23.000000000 +0200
--- gcc/tree-flow.h	2008-05-22 21:55:22.000000000 +0200
*************** struct gimple_df GTY(())
*** 188,197 ****
  
    struct ssa_operands ssa_operands;
  
-   /* Hashtable of variables annotations.  Used for static variables only;
-      local variables have direct pointer in the tree node.  */
-   htab_t GTY((param_is (struct static_var_ann_d))) var_anns;
- 
    /* Memory reference statistics collected during alias analysis.
       This information is used to drive the memory partitioning
       heuristics in compute_memory_partitions.  */
--- 188,193 ----