gcc/tree-ssa-propagate.h

   1 /* Data structures and function declarations for the SSA value propagation
   2    engine.
   3    Copyright (C) 2001, 2003, 2004 Free Software Foundation, Inc.
   4    Contributed by Diego Novillo <dnovillo@redhat.com>
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 2, or (at your option)
  11 any later version.
  12
  13 GCC is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING.  If not, write to
  20 the Free Software Foundation, 59 Temple Place - Suite 330,
  21 Boston, MA 02111-1307, USA.  */
  22
  23 #ifndef _TREE_SSA_PROPAGATE_H
  24 #define _TREE_SSA_PROPAGATE_H 1
  25
  26 /* Use the TREE_VISITED bitflag to mark statements and PHI nodes that
  27    have been deemed varying and should not be simulated again.  */
  28 #define DONT_SIMULATE_AGAIN(T)  TREE_VISITED (T)
  29
  30 /* Lattice values used for propagation purposes.  Specific instances
  31    of a propagation engine must return these values from the statement
  32    and PHI visit functions to direct the engine.  */
  33
  34 enum ssa_prop_result {
  35     /* The statement produces nothing of interest.  No edges will be
  36        added to the work lists.  */
  37     SSA_PROP_NOT_INTERESTING,
  38
  39     /* The statement produces an interesting value.  The set SSA_NAMEs
  40        returned by SSA_PROP_VISIT_STMT should be added to
  41        INTERESTING_SSA_EDGES.  If the statement being visited is a
  42        conditional jump, SSA_PROP_VISIT_STMT should indicate which edge
  43        out of the basic block should be marked executable.  */
  44     SSA_PROP_INTERESTING,
  45
  46     /* The statement produces a varying (i.e., useless) value and
  47        should not be simulated again.  If the statement being visited
  48        is a conditional jump, all the edges coming out of the block
  49        will be considered executable.  */
  50     SSA_PROP_VARYING
  51 };
  52
  53
  54 /* Call-back functions used by the value propagation engine.  */
  55 typedef enum ssa_prop_result (*ssa_prop_visit_stmt_fn) (tree, edge *, tree *);
  56 typedef enum ssa_prop_result (*ssa_prop_visit_phi_fn) (tree);
  57
  58 void ssa_propagate (ssa_prop_visit_stmt_fn, ssa_prop_visit_phi_fn);
  59 tree get_rhs (tree);
  60 bool set_rhs (tree *, tree);
  61
  62 #endif /* _TREE_SSA_PROPAGATE_H  */