Re: IPA merge: Make salias work after SSA form was built

[Jan Hubicka <jh at suse dot cz>]

> Okay, but:

Hi,
thank you for review! Unfortunately I found that it still fails on
verify_ssa on some pass orders on IPA-SSA. The problem is that we still
cache values in addresses_taken bitmap and trust them to be up to date.
This didn't reproduced in my original testing just because I had my
experimental "kill unnecesary datastructures" pass just before the
salias so the bitmaps was all clear at that point.  I don't intend to
submit that pass for mainline, it is basically just an experiment to see
how much memory we waste by caching things, so I would like to fix this
problem too.

Amusingly I didn't found any way to rebuild this bitmap after modifying
statement since tree-ssa-operand just compute it, but never clear the old
values.  Perhaps there is some way to recompute it correctly but at least it
is what I would expect update_stmt to do, so I updated build_ssa_operands
accordingly.

Bootstrapped/regtested i686-linux
OK? (and sorry for duplicated submision)
Honza
	* tree-ssa-alias.c (create_structure_vars): When in SSA, update operand
	caches.
	* tree-ssa-operands.c (build_ssa_operands): Recompute addresses_taken
	bitmap.
Index: tree-ssa-alias.c
===================================================================
*** tree-ssa-alias.c	(revision 120243)
--- tree-ssa-alias.c	(working copy)
*************** create_structure_vars (void)
*** 3188,3193 ****
--- 3188,3245 ----
      }
    htab_delete (used_portions);
    VEC_free (tree, heap, varvec);
+ 
+   /* Update SSA operands of statememnts mentioning varibales we split.  */
+   if (gimple_in_ssa_p (cfun))
+     FOR_EACH_BB (bb)
+       {
+ 	block_stmt_iterator bsi;
+ 	for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
+ 	  {
+ 	    tree stmt = bsi_stmt (bsi);
+ 	    bool update = false;
+ 	    unsigned int i;
+ 	    bitmap_iterator bi;
+ 
+ 	    if (STORED_SYMS (stmt))
+ 	       EXECUTE_IF_SET_IN_BITMAP (STORED_SYMS (stmt), 0, i, bi)
+ 		{
+ 		  tree sym = referenced_var_lookup (i);
+ 		  if (get_subvars_for_var (sym))
+ 		    {
+ 		      update=true;
+ 		      break;
+ 		    }
+ 		}
+ 
+ 	    if (LOADED_SYMS (stmt) && !update)
+ 	       EXECUTE_IF_SET_IN_BITMAP (LOADED_SYMS (stmt), 0, i, bi)
+ 		{
+ 		  tree sym = referenced_var_lookup (i);
+ 		  if (get_subvars_for_var (sym))
+ 		    {
+ 		      update=true;
+ 		      break;
+ 		    }
+ 		}
+ 
+ 	    if (stmt_ann (stmt)->addresses_taken && !update)
+ 	       EXECUTE_IF_SET_IN_BITMAP (stmt_ann (stmt)->addresses_taken,
+ 					 0, i, bi)
+ 		{
+ 		  tree sym = referenced_var_lookup (i);
+ 		  if (get_subvars_for_var (sym))
+ 		    {
+ 		      update=true;
+ 		      break;
+ 		    }
+ 		}
+ 
+ 	    if (update)
+ 	      update_stmt (stmt);
+ 	  }
+       }
+   
    return 0;
  }
  
Index: tree-ssa-operands.c
===================================================================
*** tree-ssa-operands.c	(revision 120243)
--- tree-ssa-operands.c	(working copy)
*************** build_ssa_operands (tree stmt)
*** 2337,2342 ****
--- 2337,2345 ----
       makes no memory references.  */
    ann->has_volatile_ops = false;
    ann->references_memory = false;
+   /* Just clear the bitmap so we don't end up reallocating it over and over.  */
+   if (ann->addresses_taken)
+     bitmap_clear (ann->addresses_taken);
  
    start_ssa_stmt_operands ();
    parse_ssa_operands (stmt);
*************** build_ssa_operands (tree stmt)
*** 2344,2349 ****
--- 2347,2354 ----
    operand_build_sort_virtual (build_vdefs);
    finalize_ssa_stmt_operands (stmt);
  
+   if (ann->addresses_taken && bitmap_empty_p (ann->addresses_taken))
+     ann->addresses_taken = NULL;
    /* For added safety, assume that statements with volatile operands
       also reference memory.  */
    if (ann->has_volatile_ops)