Revert

	2004-09-08  Jie Zhang  <zhangjie@magima.com.cn>

	    * tree-ssa-alias.c (compute_flow_insensitive_aliasing): If type
	    memory tag is call clobbered, so are its aliases.
	    (group_aliases): When two memory tags being grouped, if one is
	    call clobbered, so are the other and its aliases.
	    (add_may_alias): Remove call-clobbering stuff.
	    (replace_may_alias): Likewise.
	    (merge_pointed_to_info): Merge pt_global_mem

From-SVN: r87306

1 files changed, 20 insertions, 27 deletions

diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c
index f00fcc1..cd41fba 100644
--- a/gcc/tree-ssa-alias.c
+++ b/gcc/tree-ssa-alias.c
@@ -924,10 +924,6 @@ compute_flow_insensitive_aliasing (struct alias_info *ai)
 	      num_tag_refs = VARRAY_UINT (ai->num_references, tag_ann->uid);
 	      num_var_refs = VARRAY_UINT (ai->num_references, v_ann->uid);
 
-	      /* If TAG is call clobbered, so is VAR.  */
-	      if (is_call_clobbered (tag))
-		mark_call_clobbered (var);
-
 	      /* Add VAR to TAG's may-aliases set.  */
 	      add_may_alias (tag, var);
 
@@ -1120,29 +1116,8 @@ group_aliases (struct alias_info *ai)
 	  sbitmap_a_and_b (res, tag1_aliases, tag2_aliases);
 	  if (sbitmap_first_set_bit (res) >= 0)
 	    {
-	      size_t k;
-
 	      tree tag2 = var_ann (ai->pointers[j]->var)->type_mem_tag;
 
-	      if (!is_call_clobbered (tag1) && is_call_clobbered (tag2))
-		{
-		  mark_call_clobbered (tag1);
-		  EXECUTE_IF_SET_IN_SBITMAP (tag1_aliases, 0, k,
-		    {
-		      tree var = referenced_var (k);
-		      mark_call_clobbered (var);
-		    });
-		}
-	      else if (is_call_clobbered (tag1) && !is_call_clobbered (tag2))
-		{
-		  mark_call_clobbered (tag2);
-		  EXECUTE_IF_SET_IN_SBITMAP (tag2_aliases, 0, k,
-		    {
-		      tree var = referenced_var (k);
-		      mark_call_clobbered (var);
-		    });
-		}
-
 	      sbitmap_a_or_b (tag1_aliases, tag1_aliases, tag2_aliases);
 
 	      /* TAG2 does not need its aliases anymore.  */
@@ -1639,6 +1614,16 @@ add_may_alias (tree var, tree alias)
     if (alias == VARRAY_TREE (v_ann->may_aliases, i))
       return;
 
+  /* If VAR is a call-clobbered variable, so is its new ALIAS.
+     FIXME, call-clobbering should only depend on whether an address
+     escapes.  It should be independent of aliasing.  */
+  if (is_call_clobbered (var))
+    mark_call_clobbered (alias);
+
+  /* Likewise.  If ALIAS is call-clobbered, so is VAR.  */
+  else if (is_call_clobbered (alias))
+    mark_call_clobbered (var);
+
   VARRAY_PUSH_TREE (v_ann->may_aliases, alias);
   a_ann->is_alias_tag = 1;
 }
@@ -1651,6 +1636,16 @@ replace_may_alias (tree var, size_t i, tree new_alias)
 {
   var_ann_t v_ann = var_ann (var);
   VARRAY_TREE (v_ann->may_aliases, i) = new_alias;
+
+  /* If VAR is a call-clobbered variable, so is NEW_ALIAS.
+     FIXME, call-clobbering should only depend on whether an address
+     escapes.  It should be independent of aliasing.  */
+  if (is_call_clobbered (var))
+    mark_call_clobbered (new_alias);
+
+  /* Likewise.  If NEW_ALIAS is call-clobbered, so is VAR.  */
+  else if (is_call_clobbered (new_alias))
+    mark_call_clobbered (var);
 }
 
 
@@ -1707,8 +1702,6 @@ merge_pointed_to_info (struct alias_info *ai, tree dest, tree orig)
 
   if (orig_pi)
     {
-      dest_pi->pt_global_mem |= orig_pi->pt_global_mem;
-
       /* Notice that we never merge PT_MALLOC.  This attribute is only
 	 true if the pointer is the result of a malloc() call.
 	 Otherwise, we can end up in this situation: