gcc/vr-values.h

/* Support routines for Value Range Propagation (VRP).
   Copyright (C) 2016-2018 Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.

GCC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

#ifndef GCC_VR_VALUES_H
#define GCC_VR_VALUES_H

/* The VR_VALUES class holds the current view of range information
   for all the SSA_NAMEs in the IL.

   It can be used to hold context sensitive range information during
   a dominator walk or it may be used to hold range information in the
   standard VRP pass as ranges are propagated through the lattice to a
   steady state.

   This information is independent of the range information that gets
   attached to SSA_NAMEs.  A pass such as VRP may choose to transfer
   the global information it produces into global range information that
   gets attached to an SSA_NAME.  It's unclear how useful that global
   information will be in a world where we can compute context sensitive
   range information fast or perform on-demand queries.  */
class vr_values
{
 public:
  vr_values (void);
  ~vr_values (void);

  value_range *get_value_range (const_tree);

  void set_vr_value (tree, value_range *);
  void set_defs_to_varying (gimple *);
  bool update_value_range (const_tree, value_range *);
  tree op_with_constant_singleton_value_range (tree);
  void adjust_range_with_scev (value_range *, struct loop *, gimple *, tree);
  tree vrp_evaluate_conditional (tree_code, tree, tree, gimple *);
  void dump_all_value_ranges (FILE *);

  void extract_range_for_var_from_comparison_expr (tree, enum tree_code,
						   tree, tree, value_range *);
  void extract_range_from_phi_node (gphi *, value_range *);
  void extract_range_basic (value_range *, gimple *);
  void extract_range_from_stmt (gimple *, edge *, tree *, value_range *);

  void vrp_visit_cond_stmt (gcond *, edge *);

  void simplify_cond_using_ranges_2 (gcond *);
  bool simplify_stmt_using_ranges (gimple_stmt_iterator *);

  /* Indicate that propagation through the lattice is complete.  */
  void set_lattice_propagation_complete (void) { values_propagated = true; }

  /* Allocate a new value_range object.  */
  value_range *allocate_value_range (void)
    { return vrp_value_range_pool.allocate (); }

 private:
  void add_equivalence (bitmap *, const_tree);
  bool vrp_stmt_computes_nonzero (gimple *);
  bool op_with_boolean_value_range_p (tree);
  bool check_for_binary_op_overflow (enum tree_code, tree, tree, tree, bool *);
  value_range get_vr_for_comparison (int);
  tree compare_name_with_value (enum tree_code, tree, tree, bool *, bool);
  tree compare_names (enum tree_code, tree, tree, bool *);
  bool two_valued_val_range_p (tree, tree *, tree *);
  tree vrp_evaluate_conditional_warnv_with_ops_using_ranges (enum tree_code,
							     tree, tree,
							     bool *);
  tree vrp_evaluate_conditional_warnv_with_ops (enum tree_code,
						tree, tree, bool,
						bool *, bool *);
  void extract_range_from_assignment (value_range *, gassign *);
  void extract_range_from_assert (value_range *, tree);
  void extract_range_from_ssa_name (value_range *, tree);
  void extract_range_from_binary_expr (value_range *, enum tree_code,
				       tree, tree, tree);
  void extract_range_from_unary_expr (value_range *, enum tree_code,
				      tree, tree);
  void extract_range_from_cond_expr (value_range *, gassign *);
  void extract_range_from_comparison (value_range *, enum tree_code,
				      tree, tree, tree);
  void vrp_visit_assignment_or_call (gimple*, tree *, value_range *);
  void vrp_visit_switch_stmt (gswitch *, edge *);
  bool simplify_truth_ops_using_ranges (gimple_stmt_iterator *, gimple *);
  bool simplify_div_or_mod_using_ranges (gimple_stmt_iterator *, gimple *);
  bool simplify_abs_using_ranges (gimple_stmt_iterator *, gimple *);
  bool simplify_bit_ops_using_ranges (gimple_stmt_iterator *, gimple *);
  bool simplify_min_or_max_using_ranges (gimple_stmt_iterator *, gimple *);
  bool simplify_cond_using_ranges_1 (gcond *);
  bool simplify_switch_using_ranges (gswitch *);
  bool simplify_float_conversion_using_ranges (gimple_stmt_iterator *,
					       gimple *);
  bool simplify_internal_call_using_ranges (gimple_stmt_iterator *, gimple *);

  /* Allocation pools for value_range objects.  */
  object_allocator<value_range> vrp_value_range_pool;

  /* This probably belongs in the lattice rather than in here.  */
  bool values_propagated;

  /* Allocations for equivalences all come from this obstack.  */
  bitmap_obstack vrp_equiv_obstack;

  /* Value range array.  After propagation, VR_VALUE[I] holds the range
     of values that SSA name N_I may take.  */
  unsigned int num_vr_values;
  value_range **vr_value;

  /* For a PHI node which sets SSA name N_I, VR_COUNTS[I] holds the
     number of executable edges we saw the last time we visited the
     node.  */
  int *vr_phi_edge_counts;
};

#define VR_INITIALIZER { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }

extern tree get_output_for_vrp (gimple *);
#endif /* GCC_VR_VALUES_H */