tree-vrp.c (maybe_set_nonzero_bits): New function.

	* tree-vrp.c (maybe_set_nonzero_bits): New function.
	(remove_range_assertions): Call it.

From-SVN: r204258

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 551b3031ea9d5f6ebaebe3911c85fce4e708e68d..99a5034689791ff9a7e11368c4744eef537d3b22 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,8 @@
 2013-10-31  Jakub Jelinek  <jakub@redhat.com>
 
+       * tree-vrp.c (maybe_set_nonzero_bits): New function.
+       (remove_range_assertions): Call it.
+
        * tree.c (tree_ctz): New function.
        * tree.h (tree_ctz): New prototype.
        * tree-ssanames.h (get_range_info, get_nonzero_bits): Change

diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index a28e9369660520ad6124838ac1e4c349fa28a62c..15cfcb3f5913d0cd9338dd4035e4f3c835cdc3d3 100644 (file)
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -6486,6 +6486,60 @@ all_imm_uses_in_stmt_or_feed_cond (tree var, gimple stmt, basic_block cond_bb)
   return true;
 }
 
+/* Handle
+   _4 = x_3 & 31;
+   if (_4 != 0)
+     goto <bb 6>;
+   else
+     goto <bb 7>;
+   <bb 6>:
+   __builtin_unreachable ();
+   <bb 7>:
+   x_5 = ASSERT_EXPR <x_3, ...>;
+   If x_3 has no other immediate uses (checked by caller),
+   var is the x_3 var from ASSERT_EXPR, we can clear low 5 bits
+   from the non-zero bitmask.  */
+
+static void
+maybe_set_nonzero_bits (basic_block bb, tree var)
+{
+  edge e = single_pred_edge (bb);
+  basic_block cond_bb = e->src;
+  gimple stmt = last_stmt (cond_bb);
+  tree cst;
+
+  if (stmt == NULL
+      || gimple_code (stmt) != GIMPLE_COND
+      || gimple_cond_code (stmt) != ((e->flags & EDGE_TRUE_VALUE)
+                                    ? EQ_EXPR : NE_EXPR)
+      || TREE_CODE (gimple_cond_lhs (stmt)) != SSA_NAME
+      || !integer_zerop (gimple_cond_rhs (stmt)))
+    return;
+
+  stmt = SSA_NAME_DEF_STMT (gimple_cond_lhs (stmt));
+  if (!is_gimple_assign (stmt)
+      || gimple_assign_rhs_code (stmt) != BIT_AND_EXPR
+      || TREE_CODE (gimple_assign_rhs2 (stmt)) != INTEGER_CST)
+    return;
+  if (gimple_assign_rhs1 (stmt) != var)
+    {
+      gimple stmt2;
+
+      if (TREE_CODE (gimple_assign_rhs1 (stmt)) != SSA_NAME)
+       return;
+      stmt2 = SSA_NAME_DEF_STMT (gimple_assign_rhs1 (stmt));
+      if (!gimple_assign_cast_p (stmt2)
+         || gimple_assign_rhs1 (stmt2) != var
+         || !CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (stmt2))
+         || (TYPE_PRECISION (TREE_TYPE (gimple_assign_rhs1 (stmt)))
+                             != TYPE_PRECISION (TREE_TYPE (var))))
+       return;
+    }
+  cst = gimple_assign_rhs2 (stmt);
+  set_nonzero_bits (var, (get_nonzero_bits (var)
+                         & ~tree_to_double_int (cst)));
+}
+
 /* Convert range assertion expressions into the implied copies and
    copy propagate away the copies.  Doing the trivial copy propagation
    here avoids the need to run the full copy propagation pass after
@@ -6566,8 +6620,11 @@ remove_range_assertions (void)
                if (is_unreachable
                    && all_imm_uses_in_stmt_or_feed_cond (var, stmt,
                                                          single_pred (bb)))
-                 set_range_info (var, SSA_NAME_RANGE_INFO (lhs)->min,
-                                 SSA_NAME_RANGE_INFO (lhs)->max);
+                 {
+                   set_range_info (var, SSA_NAME_RANGE_INFO (lhs)->min,
+                                   SSA_NAME_RANGE_INFO (lhs)->max);
+                   maybe_set_nonzero_bits (bb, var);
+                 }
              }
 
            /* Propagate the RHS into every use of the LHS.  */