2008-04-30 Richard Guenther <rguenther@suse.de>

	PR tree-optimization/21636
	* tree-ssa-ccp.c (ccp_fold): Handle &p->x with p being a
	constant address.
	(evaluate_stmt): Print the likely value.
	(ccp_visit_stmt): Avoid excessive vertical spacing.

	* gcc.dg/tree-ssa/ssa-ccp-19.c: New testcase.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@134834 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 51 insertions, 1 deletions

diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c
index 6907f0b837b..c6c7a8885f5 100644
--- a/gcc/tree-ssa-ccp.c
+++ b/gcc/tree-ssa-ccp.c
@@ -975,6 +975,38 @@ ccp_fold (tree stmt)
   else if (kind == tcc_reference)
     return fold_const_aggregate_ref (rhs);
 
+  /* Handle propagating invariant addresses into address operations.
+     The folding we do here matches that in tree-ssa-forwprop.c.  */
+  else if (code == ADDR_EXPR)
+    {
+      tree *base;
+      base = &TREE_OPERAND (rhs, 0);
+      while (handled_component_p (*base))
+	base = &TREE_OPERAND (*base, 0);
+      if (TREE_CODE (*base) == INDIRECT_REF
+	  && TREE_CODE (TREE_OPERAND (*base, 0)) == SSA_NAME)
+	{
+	  prop_value_t *val = get_value (TREE_OPERAND (*base, 0));
+	  if (val->lattice_val == CONSTANT
+	      && TREE_CODE (val->value) == ADDR_EXPR
+	      && useless_type_conversion_p (TREE_TYPE (TREE_OPERAND (*base, 0)),
+					    TREE_TYPE (val->value))
+	      && useless_type_conversion_p (TREE_TYPE (*base),
+					    TREE_TYPE (TREE_OPERAND (val->value, 0))))
+	    {
+	      /* We need to return a new tree, not modify the IL or share
+		 parts of it.  So play some tricks to avoid manually
+		 building it.  */
+	      tree ret, save = *base;
+	      *base = TREE_OPERAND (val->value, 0);
+	      ret = unshare_expr (rhs);
+	      recompute_tree_invariant_for_addr_expr (ret);
+	      *base = save;
+	      return ret;
+	    }
+	}
+    }
+
   /* We may be able to fold away calls to builtin functions if their
      arguments are constants.  */
   else if (code == CALL_EXPR
@@ -1210,6 +1242,25 @@ evaluate_stmt (tree stmt)
 
   fold_undefer_overflow_warnings (is_constant, stmt, 0);
 
+  if (dump_file && (dump_flags & TDF_DETAILS))
+    {
+      fprintf (dump_file, "which is likely ");
+      switch (likelyvalue)
+	{
+	case CONSTANT:
+	  fprintf (dump_file, "CONSTANT");
+	  break;
+	case UNDEFINED:
+	  fprintf (dump_file, "UNDEFINED");
+	  break;
+	case VARYING:
+	  fprintf (dump_file, "VARYING");
+	  break;
+	default:;
+	}
+      fprintf (dump_file, "\n");
+    }
+
   if (is_constant)
     {
       /* The statement produced a constant value.  */
@@ -1378,7 +1429,6 @@ ccp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p)
     {
       fprintf (dump_file, "\nVisiting statement:\n");
       print_generic_stmt (dump_file, stmt, dump_flags);
-      fprintf (dump_file, "\n");
     }
 
   if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)