re PR tree-optimization/21636 (Missed ccp optimization)

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.

From-SVN: r134834

4 files changed, 80 insertions, 1 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 043723e..9df335e 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+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.
+
 2008-04-30  Rafael Espindola  <espindola@google.com>
 
 	* builtins.c (fold_call_expr): Return realret.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 53978cc..410b720 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2008-04-30  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/21636
+	* gcc.dg/tree-ssa/ssa-ccp-19.c: New testcase.
+
 2008-04-30  Thomas Koenig  <tkoenig@gcc.gnu.org>
 
 	PR libfortran/35993
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-19.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-19.c
new file mode 100644
index 0000000..ab41822
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-19.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-ccp1" } */
+
+struct f { int i; };
+int g()
+{
+  struct f a, *a1;
+  int *i;
+  a.i = 1;
+  a1 = &a;
+  i = &a1->i;
+  return *i;  /* This should be turned into a.i */
+}
+
+/* { dg-final { scan-tree-dump "= a.i;" "ccp1" } } */
+/* { dg-final { cleanup-tree-dump "ccp1" } } */
diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c
index 6907f0b..c6c7a88 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)