[patch, committed] Remove walk_use_def_chains

[Florian Weimer <fw at deneb dot enyo dot de>]

As preapproved by Richard Biener.  Bootstrapped on
x86_64-debian-linux-gnu.

2013-09-26  Florian Weimer  <fw@deneb.enyo.de>

	* tree-ssa.h (walk_use_def_chains_fn, walk_use_def_chains): Delete.
	* tree-ssa.c (walk_use_def_chains_1, walk_use_def_chains): Delete.
	* doc/tree-ssa.texi (Walking use-def chains): Delete.

Index: gcc/tree-ssa.c
===================================================================
--- gcc/tree-ssa.c	(revision 202947)
+++ gcc/tree-ssa.c	(working copy)
@@ -1347,115 +1347,6 @@
 }
 
 
-/* Internal helper for walk_use_def_chains.  VAR, FN and DATA are as
-   described in walk_use_def_chains.
-
-   VISITED is a pointer set used to mark visited SSA_NAMEs to avoid
-      infinite loops.  We used to have a bitmap for this to just mark
-      SSA versions we had visited.  But non-sparse bitmaps are way too
-      expensive, while sparse bitmaps may cause quadratic behavior.
-
-   IS_DFS is true if the caller wants to perform a depth-first search
-      when visiting PHI nodes.  A DFS will visit each PHI argument and
-      call FN after each one.  Otherwise, all the arguments are
-      visited first and then FN is called with each of the visited
-      arguments in a separate pass.  */
-
-static bool
-walk_use_def_chains_1 (tree var, walk_use_def_chains_fn fn, void *data,
-		       struct pointer_set_t *visited, bool is_dfs)
-{
-  gimple def_stmt;
-
-  if (pointer_set_insert (visited, var))
-    return false;
-
-  def_stmt = SSA_NAME_DEF_STMT (var);
-
-  if (gimple_code (def_stmt) != GIMPLE_PHI)
-    {
-      /* If we reached the end of the use-def chain, call FN.  */
-      return fn (var, def_stmt, data);
-    }
-  else
-    {
-      size_t i;
-
-      /* When doing a breadth-first search, call FN before following the
-	 use-def links for each argument.  */
-      if (!is_dfs)
-	for (i = 0; i < gimple_phi_num_args (def_stmt); i++)
-	  if (fn (gimple_phi_arg_def (def_stmt, i), def_stmt, data))
-	    return true;
-
-      /* Follow use-def links out of each PHI argument.  */
-      for (i = 0; i < gimple_phi_num_args (def_stmt); i++)
-	{
-	  tree arg = gimple_phi_arg_def (def_stmt, i);
-
-	  /* ARG may be NULL for newly introduced PHI nodes.  */
-	  if (arg
-	      && TREE_CODE (arg) == SSA_NAME
-	      && walk_use_def_chains_1 (arg, fn, data, visited, is_dfs))
-	    return true;
-	}
-
-      /* When doing a depth-first search, call FN after following the
-	 use-def links for each argument.  */
-      if (is_dfs)
-	for (i = 0; i < gimple_phi_num_args (def_stmt); i++)
-	  if (fn (gimple_phi_arg_def (def_stmt, i), def_stmt, data))
-	    return true;
-    }
-
-  return false;
-}
-
-
-
-/* Walk use-def chains starting at the SSA variable VAR.  Call
-   function FN at each reaching definition found.  FN takes three
-   arguments: VAR, its defining statement (DEF_STMT) and a generic
-   pointer to whatever state information that FN may want to maintain
-   (DATA).  FN is able to stop the walk by returning true, otherwise
-   in order to continue the walk, FN should return false.
-
-   Note, that if DEF_STMT is a PHI node, the semantics are slightly
-   different.  The first argument to FN is no longer the original
-   variable VAR, but the PHI argument currently being examined.  If FN
-   wants to get at VAR, it should call PHI_RESULT (PHI).
-
-   If IS_DFS is true, this function will:
-
-	1- walk the use-def chains for all the PHI arguments, and,
-	2- call (*FN) (ARG, PHI, DATA) on all the PHI arguments.
-
-   If IS_DFS is false, the two steps above are done in reverse order
-   (i.e., a breadth-first search).  */
-
-void
-walk_use_def_chains (tree var, walk_use_def_chains_fn fn, void *data,
-                     bool is_dfs)
-{
-  gimple def_stmt;
-
-  gcc_assert (TREE_CODE (var) == SSA_NAME);
-
-  def_stmt = SSA_NAME_DEF_STMT (var);
-
-  /* We only need to recurse if the reaching definition comes from a PHI
-     node.  */
-  if (gimple_code (def_stmt) != GIMPLE_PHI)
-    (*fn) (var, def_stmt, data);
-  else
-    {
-      struct pointer_set_t *visited = pointer_set_create ();
-      walk_use_def_chains_1 (var, fn, data, visited, is_dfs);
-      pointer_set_destroy (visited);
-    }
-}
-
-
 /* If necessary, rewrite the base of the reference tree *TP from
    a MEM_REF to a plain or converted symbol.  */
 
Index: gcc/tree-ssa.h
===================================================================
--- gcc/tree-ssa.h	(revision 202947)
+++ gcc/tree-ssa.h	(working copy)
@@ -56,11 +56,6 @@
 extern bool tree_ssa_useless_type_conversion (tree);
 extern tree tree_ssa_strip_useless_type_conversions (tree);
 
-/* Call-back function for walk_use_def_chains().  At each reaching
-   definition, a function with this prototype is called.  */
-typedef bool (*walk_use_def_chains_fn) (tree, gimple, void *);
-extern void walk_use_def_chains (tree, walk_use_def_chains_fn, void *, bool);
-
 extern bool ssa_undefined_value_p (tree);
 extern void execute_update_addresses_taken (void);
 
Index: gcc/doc/tree-ssa.texi
===================================================================
--- gcc/doc/tree-ssa.texi	(revision 202947)
+++ gcc/doc/tree-ssa.texi	(working copy)
@@ -725,33 +725,6 @@
 @end defmac
 
 
-@subsection Walking use-def chains
-
-@deftypefn {Tree SSA function} void walk_use_def_chains (@var{var}, @var{fn}, @var{data})
-
-Walks use-def chains starting at the @code{SSA_NAME} node @var{var}.
-Calls function @var{fn} at each reaching definition found.  Function
-@var{FN} takes three arguments: @var{var}, its defining statement
-(@var{def_stmt}) and a generic pointer to whatever state information
-that @var{fn} may want to maintain (@var{data}).  Function @var{fn} is
-able to stop the walk by returning @code{true}, otherwise in order to
-continue the walk, @var{fn} should return @code{false}.
-
-Note, that if @var{def_stmt} is a @code{PHI} node, the semantics are
-slightly different.  For each argument @var{arg} of the PHI node, this
-function will:
-
-@enumerate
-@item Walk the use-def chains for @var{arg}.
-@item Call @code{FN (@var{arg}, @var{phi}, @var{data})}.
-@end enumerate
-
-Note how the first argument to @var{fn} is no longer the original
-variable @var{var}, but the PHI argument currently being examined.
-If @var{fn} wants to get at @var{var}, it should call
-@code{PHI_RESULT} (@var{phi}).
-@end deftypefn
-
 @subsection Walking the dominator tree
 
 @deftypefn {Tree SSA function} void walk_dominator_tree (@var{walk_data}, @var{bb})