2011-01-25 Richard Guenther <rguenther@suse.de>

	PR tree-optimization/47426
	* tree-ssa-structalias.c (ipa_pta_execute): Make externally
	visible functions results escape.

	* gcc.dg/torture/pr47426-1.c: New testcase.
	* gcc.dg/torture/pr47426-2.c: Likewise.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@169241 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 36 insertions, 7 deletions

diff --git a/gcc/tree-ssa-structalias.c b/gcc/tree-ssa-structalias.c
index a49f14bba13..cf1e817f377 100644
--- a/gcc/tree-ssa-structalias.c
+++ b/gcc/tree-ssa-structalias.c
@@ -4435,12 +4435,14 @@ find_func_aliases (gimple origt)
 	do_structure_copy (lhsop, rhsop);
       else
 	{
+	  enum tree_code code = gimple_assign_rhs_code (t);
+
 	  get_constraint_for (lhsop, &lhsc);
 
-	  if (gimple_assign_rhs_code (t) == POINTER_PLUS_EXPR)
+	  if (code == POINTER_PLUS_EXPR)
 	    get_constraint_for_ptr_offset (gimple_assign_rhs1 (t),
 					   gimple_assign_rhs2 (t), &rhsc);
-	  else if (gimple_assign_rhs_code (t) == BIT_AND_EXPR
+	  else if (code == BIT_AND_EXPR
 		   && TREE_CODE (gimple_assign_rhs2 (t)) == INTEGER_CST)
 	    {
 	      /* Aligning a pointer via a BIT_AND_EXPR is offsetting
@@ -4448,11 +4450,15 @@ find_func_aliases (gimple origt)
 	      get_constraint_for_ptr_offset (gimple_assign_rhs1 (t),
 					     NULL_TREE, &rhsc);
 	    }
-	  else if ((CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (t))
+	  else if ((CONVERT_EXPR_CODE_P (code)
 		    && !(POINTER_TYPE_P (gimple_expr_type (t))
 			 && !POINTER_TYPE_P (TREE_TYPE (rhsop))))
 		   || gimple_assign_single_p (t))
 	    get_constraint_for_rhs (rhsop, &rhsc);
+	  else if (truth_value_p (code))
+	    /* Truth value results are not pointer (parts).  Or at least
+	       very very unreasonable obfuscation of a part.  */
+	    ;
 	  else
 	    {
 	      /* All other operations are merges.  */
@@ -6827,11 +6833,34 @@ ipa_pta_execute (void)
       push_cfun (func);
       current_function_decl = node->decl;
 
-      /* For externally visible functions use local constraints for
-	 their arguments.  For local functions we see all callers
-	 and thus do not need initial constraints for parameters.  */
       if (node->local.externally_visible)
-	intra_create_variable_infos ();
+	{
+	  /* For externally visible functions use local constraints for
+	     their arguments.  For local functions we see all callers
+	     and thus do not need initial constraints for parameters.  */
+	  intra_create_variable_infos ();
+
+	  /* We also need to make function return values escape.  Nothing
+	     escapes by returning from main though.  */
+	  if (!MAIN_NAME_P (DECL_NAME (node->decl)))
+	    {
+	      varinfo_t fi, rvi;
+	      fi = lookup_vi_for_tree (node->decl);
+	      rvi = first_vi_for_offset (fi, fi_result);
+	      if (rvi && rvi->offset == fi_result)
+		{
+		  struct constraint_expr includes;
+		  struct constraint_expr var;
+		  includes.var = escaped_id;
+		  includes.offset = 0;
+		  includes.type = SCALAR;
+		  var.var = rvi->id;
+		  var.offset = 0;
+		  var.type = SCALAR;
+		  process_constraint (new_constraint (includes, var));
+		}
+	    }
+	}
 
       /* Build constriants for the function body.  */
       FOR_EACH_BB_FN (bb, func)