gcc/doc/gccint/gimple/statement-and-operand-traversals.rst

   1 ..
   2   Copyright 1988-2022 Free Software Foundation, Inc.
   3   This is part of the GCC manual.
   4   For copying conditions, see the copyright.rst file.
   5
   6 .. index:: Statement and operand traversals
   7
   8 .. _statement-and-operand-traversals:
   9
  10 Statement and operand traversals
  11 ********************************
  12
  13 There are two functions available for walking statements and
  14 sequences: ``walk_gimple_stmt`` and ``walk_gimple_seq``,
  15 accordingly, and a third function for walking the operands in a
  16 statement: ``walk_gimple_op``.
  17
  18 .. function:: tree walk_gimple_stmt (gimple_stmt_iterator *gsi,   walk_stmt_fn callback_stmt, walk_tree_fn callback_op, struct walk_stmt_info *wi)
  19
  20   This function is used to walk the current statement in ``GSI``,
  21   optionally using traversal state stored in ``WI``.  If ``WI`` is ``NULL``, no
  22   state is kept during the traversal.
  23
  24   The callback ``CALLBACK_STMT`` is called.  If ``CALLBACK_STMT`` returns
  25   true, it means that the callback function has handled all the
  26   operands of the statement and it is not necessary to walk its
  27   operands.
  28
  29   If ``CALLBACK_STMT`` is ``NULL`` or it returns false, ``CALLBACK_OP`` is
  30   called on each operand of the statement via ``walk_gimple_op``.  If
  31   ``walk_gimple_op`` returns non- ``NULL`` for any operand, the remaining
  32   operands are not scanned.
  33
  34   The return value is that returned by the last call to
  35   ``walk_gimple_op``, or ``NULL_TREE`` if no ``CALLBACK_OP`` is specified.
  36
  37 .. function:: tree walk_gimple_op (gimple stmt,   walk_tree_fn callback_op, struct walk_stmt_info *wi)
  38
  39   Use this function to walk the operands of statement ``STMT``.  Every
  40   operand is walked via ``walk_tree`` with optional state information
  41   in ``WI``.
  42
  43   ``CALLBACK_OP`` is called on each operand of ``STMT`` via ``walk_tree``.
  44   Additional parameters to ``walk_tree`` must be stored in ``WI``.  For
  45   each operand ``OP``, ``walk_tree`` is called as:
  46
  47   .. code-block:: c++
  48
  49     walk_tree (&OP, CALLBACK_OP, WI, PSET)
  50
  51   If ``CALLBACK_OP`` returns non- ``NULL`` for an operand, the remaining
  52   operands are not scanned.  The return value is that returned by
  53   the last call to ``walk_tree``, or ``NULL_TREE`` if no ``CALLBACK_OP`` is
  54   specified.
  55
  56 .. function:: tree walk_gimple_seq (gimple_seq seq,   walk_stmt_fn callback_stmt, walk_tree_fn callback_op, struct walk_stmt_info *wi)
  57
  58   This function walks all the statements in the sequence ``SEQ``
  59   calling ``walk_gimple_stmt`` on each one.  ``WI`` is as in
  60   ``walk_gimple_stmt``.  If ``walk_gimple_stmt`` returns non- ``NULL``, the walk
  61   is stopped and the value returned.  Otherwise, all the statements
  62   are walked and ``NULL_TREE`` returned.