builtins.c (fold_call_expr): Return realret.

2008-04-30  Rafael Espindola  <espindola@google.com>

	* builtins.c (fold_call_expr): Return realret.
	* tree-ssa-threadedge.c
	(record_temporary_equivalences_from_stmts_at_dest): Ignore calls to
	__builtin_object_size.

From-SVN: r134833

gcc/ChangeLog

+2008-04-30  Rafael Espindola  <espindola@google.com>
+
+	* builtins.c (fold_call_expr): Return realret.
+	* tree-ssa-threadedge.c
+	(record_temporary_equivalences_from_stmts_at_dest): Ignore calls to
+	__builtin_object_size.
+
 2008-04-30  Seongbae Park  <seongbae.park@gmail.com>
 
 	* gcc.c (wrapper_string): New variable.

gcc/builtins.c

@@ -10553,6 +10553,7 @@ fold_call_expr (tree exp, bool ignore)
 		  if (CAN_HAVE_LOCATION_P (realret)
 		      && !EXPR_HAS_LOCATION (realret))
 		    SET_EXPR_LOCATION (realret, EXPR_LOCATION (exp));
+		  return realret;
 		}
 	      return ret;
 	    }

gcc/tree-ssa-threadedge.c

@@ -226,6 +226,7 @@ record_temporary_equivalences_from_stmts_at_dest (edge e,
   for (bsi = bsi_start (e->dest); ! bsi_end_p (bsi); bsi_next (&bsi))
     {
       tree cached_lhs = NULL;
+      tree rhs;
 
       stmt = bsi_stmt (bsi);
 
@@ -252,6 +253,32 @@ record_temporary_equivalences_from_stmts_at_dest (edge e,
 	  || TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 0)) != SSA_NAME)
 	continue;
 
+      rhs = GIMPLE_STMT_OPERAND (stmt, 1);
+
+      /* The result of __builtin_object_size depends on all the arguments
+	 of a phi node. Temporarily using only one edge produces invalid
+	 results. For example
+
+	 if (x < 6)
+	   goto l;
+	 else
+	   goto l;
+
+	 l:
+	 r = PHI <&w[2].a[1](2), &a.a[6](3)>
+	 __builtin_object_size (r, 0)
+
+	 The result of __builtin_object_size is defined to be the maximum of
+	 remaining bytes. If we use only one edge on the phi, the result will
+	 change to be the remaining bytes for the corresponding phi argument. */
+
+      if (TREE_CODE (rhs) == CALL_EXPR)
+	{
+	  tree fndecl = get_callee_fndecl (rhs);
+	  if (fndecl && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_OBJECT_SIZE)
+	    continue;
+	}
+
       /* At this point we have a statement which assigns an RHS to an
 	 SSA_VAR on the LHS.  We want to try and simplify this statement
 	 to expose more context sensitive equivalences which in turn may
@@ -259,10 +286,10 @@ record_temporary_equivalences_from_stmts_at_dest (edge e,
 
 	 Handle simple copy operations as well as implied copies from
 	 ASSERT_EXPRs.  */
-      if (TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == SSA_NAME)
-	cached_lhs = GIMPLE_STMT_OPERAND (stmt, 1);
-      else if (TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == ASSERT_EXPR)
-	cached_lhs = TREE_OPERAND (GIMPLE_STMT_OPERAND (stmt, 1), 0);
+      if (TREE_CODE (rhs) == SSA_NAME)
+	cached_lhs = rhs;
+      else if (TREE_CODE (rhs) == ASSERT_EXPR)
+	cached_lhs = TREE_OPERAND (rhs, 0);
       else
 	{
 	  /* A statement that is not a trivial copy or ASSERT_EXPR.