[PATCH] Fix PR18908 folding bits, fixup integer_all_onesp

[PATCH] Fix PR18908 folding bits, fixup integer_all_onesp

[Richard Guenther]

This fixes the folding bits for PR18908 where we fail to canonicalize
X ^ ~0 as ~X.  Fixed by making integer_all_onesp use TYPE_PRECISION
and by making forwprop also perform this canonicalization.

Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.

Richard.

2011-07-20  Richard Guenther  <rguenther@suse.de>

	PR middle-end/18908
	* tree.c (integer_all_onesp): Use TYPE_PRECISION, not mode precision.
	* tree-ssa-forwprop.c (simplify_bitwise_binary): Remove bogus
	ADDR_EXPR folding.  Canonicalize X ^ ~0 as ~X.

	* gcc.dg/tree-ssa/pr18908.c: New testcase.

Index: gcc/tree.c
===================================================================
*** gcc/tree.c	(revision 176497)
--- gcc/tree.c	(working copy)
*************** integer_all_onesp (const_tree expr)
*** 1759,1767 ****
    if (!uns)
      return 0;
  
!   /* Note that using TYPE_PRECISION here is wrong.  We care about the
!      actual bits, not the (arbitrary) range of the type.  */
!   prec = GET_MODE_BITSIZE (TYPE_MODE (TREE_TYPE (expr)));
    if (prec >= HOST_BITS_PER_WIDE_INT)
      {
        HOST_WIDE_INT high_value;
--- 1759,1765 ----
    if (!uns)
      return 0;
  
!   prec = TYPE_PRECISION (TREE_TYPE (expr));
    if (prec >= HOST_BITS_PER_WIDE_INT)
      {
        HOST_WIDE_INT high_value;
Index: gcc/tree-ssa-forwprop.c
===================================================================
*** gcc/tree-ssa-forwprop.c	(revision 176497)
--- gcc/tree-ssa-forwprop.c	(working copy)
*************** simplify_bitwise_binary (gimple_stmt_ite
*** 1710,1746 ****
    tree def1_arg1, def2_arg1;
    enum tree_code def1_code, def2_code;
  
-   /* If the first argument is an SSA name that is itself a result of a
-      typecast of an ADDR_EXPR to an integer, feed the ADDR_EXPR to the
-      folder rather than the ssa name.  */
-   if (code == BIT_AND_EXPR
-       && TREE_CODE (arg2) == INTEGER_CST
-       && TREE_CODE (arg1) == SSA_NAME)
-     {
-       gimple def = SSA_NAME_DEF_STMT (arg1);
-       tree op = arg1;
- 
-       /* ???  This looks bogus - the conversion could be truncating.  */
-       if (is_gimple_assign (def)
- 	  && CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def))
- 	  && INTEGRAL_TYPE_P (TREE_TYPE (arg1)))
- 	{
- 	  tree opp = gimple_assign_rhs1 (def);
- 	  if (TREE_CODE (opp) == ADDR_EXPR)
- 	    op = opp;
- 	}
- 
-       res = fold_binary_loc (gimple_location (stmt),
- 			     BIT_AND_EXPR, TREE_TYPE (gimple_assign_lhs (stmt)),
- 			     op, arg2);
-       if (res && is_gimple_min_invariant (res))
- 	{
- 	  gimple_assign_set_rhs_from_tree (gsi, res);
- 	  update_stmt (stmt);
- 	  return true;
- 	}
-     }
- 
    def1_code = TREE_CODE (arg1);
    def1_arg1 = arg1;
    if (TREE_CODE (arg1) == SSA_NAME)
--- 1710,1715 ----
*************** simplify_bitwise_binary (gimple_stmt_ite
*** 1861,1866 ****
--- 1830,1846 ----
        update_stmt (stmt);
        return true;
      }
+ 
+   /* Canonicalize X ^ ~0 to ~X.  */
+   if (code == BIT_XOR_EXPR
+       && TREE_CODE (arg2) == INTEGER_CST
+       && integer_all_onesp (arg2))
+     {
+       gimple_assign_set_rhs_with_ops (gsi, BIT_NOT_EXPR, arg1, NULL_TREE);
+       gcc_assert (gsi_stmt (*gsi) == stmt);
+       update_stmt (stmt);
+       return true;
+     }
  
    /* Try simple folding for X op !X, and X op X.  */
    res = simplify_bitwise_binary_1 (code, TREE_TYPE (arg1), arg1, arg2);
Index: gcc/testsuite/gcc.dg/tree-ssa/pr18908.c
===================================================================
*** gcc/testsuite/gcc.dg/tree-ssa/pr18908.c	(revision 0)
--- gcc/testsuite/gcc.dg/tree-ssa/pr18908.c	(revision 0)
***************
*** 0 ****
--- 1,9 ----
+ /* { dg-do compile } */
+ /* { dg-options "-O -fdump-tree-forwprop1" } */
+ 
+ _Bool f3(_Bool *p) { *p ^= 1; }
+ 
+ /* We should be able to canonicalize the above to use bitwise not.  */
+ /* { dg-final { scan-tree-dump "~D" "forwprop1" } } */
+ /* { dg-final { scan-tree-dump-not "\\\^ 1" "forwprop1" } } */
+ /* { dg-final { cleanup-tree-dump "forwprop1" } } */