re PR tree-optimization/59047 (wrong code for bitfields at -O3 on x86_64-linux-gnu)

2013-11-08  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/59047
	* tree-predcom.c (ref_at_iteration): Handle bitfield accesses
	properly.

	* gcc.dg/torture/pr59047.c: New testcase.

From-SVN: r204566

gcc/ChangeLog

+2013-11-08  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/59047
+	* tree-predcom.c (ref_at_iteration): Handle bitfield accesses
+	properly.
+
 2013-11-08  Ilya Enkovich  <ilya.enkovich@intel.com>
 
 	* common.opt (fcheck-pointer-bounds): Move to ...

gcc/testsuite/ChangeLog

+2013-11-08  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/59047
+	* gcc.dg/torture/pr59047.c: New testcase.
+
+2013-11-08  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/59038
+	PR tree-optimization/58955
+	* gcc.dg/torture/pr59038.c: New testcase.
+
 2013-11-07  Janus Weil  <janus@gcc.gnu.org>
 
 	PR fortran/58471

gcc/testsuite/gcc.dg/torture/pr59047.c

+/* { dg-do run } */
+
+extern void abort (void);
+
+struct
+{
+  int f0;
+  int f1:1;
+  int f2:2;
+} a = {0, 0, 1};
+
+int b, c, *d, e, f;
+
+int
+fn1 ()
+{
+  for (; b < 1; ++b)
+    {
+      for (e = 0; e < 1; e = 1)
+	{
+	  int **g = &d;
+	  *g = &c;
+	} 
+      *d = 0;
+      f = a.f1;
+      if (f)
+	return 0;
+    }
+  return 0;
+}
+
+int
+main ()
+{
+  fn1 ();
+  if (b != 1)
+    abort ();
+  return 0;
+}

gcc/tree-predcom.c

@@ -1353,10 +1353,24 @@ ref_at_iteration (data_reference_p dr, int iter, gimple_seq *stmts)
   tree addr = fold_build_pointer_plus (DR_BASE_ADDRESS (dr), off);
   addr = force_gimple_operand_1 (addr, stmts, is_gimple_mem_ref_addr,
 				 NULL_TREE);
-  return fold_build2 (MEM_REF, TREE_TYPE (DR_REF (dr)),
-		      addr,
-		      fold_convert (reference_alias_ptr_type (DR_REF (dr)),
-				    coff));
+  tree alias_ptr = fold_convert (reference_alias_ptr_type (DR_REF (dr)), coff);
+  /* While data-ref analysis punts on bit offsets it still handles
+     bitfield accesses at byte boundaries.  Cope with that.  Note that
+     we cannot simply re-apply the outer COMPONENT_REF because the
+     byte-granular portion of it is already applied via DR_INIT and
+     DR_OFFSET, so simply build a BIT_FIELD_REF knowing that the bits
+     start at offset zero.  */
+  if (TREE_CODE (DR_REF (dr)) == COMPONENT_REF
+      && DECL_BIT_FIELD (TREE_OPERAND (DR_REF (dr), 1)))
+    {
+      tree field = TREE_OPERAND (DR_REF (dr), 1);
+      return build3 (BIT_FIELD_REF, TREE_TYPE (DR_REF (dr)),
+		     build2 (MEM_REF, DECL_BIT_FIELD_TYPE (field),
+			     addr, alias_ptr),
+		     DECL_SIZE (field), bitsize_zero_node);
+    }
+  else
+    return fold_build2 (MEM_REF, TREE_TYPE (DR_REF (dr)), addr, alias_ptr);
 }
 
 /* Get the initialization expression for the INDEX-th temporary variable