--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/df-core.c	Fri Jul 17 14:47:48 2009 +0900
@@ -0,0 +1,2187 @@
+/* Allocation for dataflow support routines.
+   Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
+   2008 Free Software Foundation, Inc.
+   Originally contributed by Michael P. Hayes 
+             (m.hayes@elec.canterbury.ac.nz, mhayes@redhat.com)
+   Major rewrite contributed by Danny Berlin (dberlin@dberlin.org)
+             and Kenneth Zadeck (zadeck@naturalbridge.com).
+
+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/>.  */
+
+/*
+OVERVIEW:
+
+The files in this collection (df*.c,df.h) provide a general framework
+for solving dataflow problems.  The global dataflow is performed using
+a good implementation of iterative dataflow analysis.
+
+The file df-problems.c provides problem instance for the most common
+dataflow problems: reaching defs, upward exposed uses, live variables,
+uninitialized variables, def-use chains, and use-def chains.  However,
+the interface allows other dataflow problems to be defined as well.
+
+Dataflow analysis is available in most of the rtl backend (the parts
+between pass_df_initialize and pass_df_finish).  It is quite likely
+that these boundaries will be expanded in the future.  The only
+requirement is that there be a correct control flow graph.
+
+There are three variations of the live variable problem that are
+available whenever dataflow is available.  The LR problem finds the
+areas that can reach a use of a variable, the UR problems finds the
+areas that can be reached from a definition of a variable.  The LIVE
+problem finds the intersection of these two areas.  
+
+There are several optional problems.  These can be enabled when they
+are needed and disabled when they are not needed.
+
+Dataflow problems are generally solved in three layers.  The bottom
+layer is called scanning where a data structure is built for each rtl
+insn that describes the set of defs and uses of that insn.  Scanning
+is generally kept up to date, i.e. as the insns changes, the scanned
+version of that insn changes also.  There are various mechanisms for
+making this happen and are described in the INCREMENTAL SCANNING
+section.
+
+In the middle layer, basic blocks are scanned to produce transfer
+functions which describe the effects of that block on the global
+dataflow solution.  The transfer functions are only rebuilt if the
+some instruction within the block has changed.  
+
+The top layer is the dataflow solution itself.  The dataflow solution
+is computed by using an efficient iterative solver and the transfer
+functions.  The dataflow solution must be recomputed whenever the
+control changes or if one of the transfer function changes.
+
+
+USAGE:
+
+Here is an example of using the dataflow routines.
+
+      df_[chain,live,note,rd]_add_problem (flags);
+
+      df_set_blocks (blocks);
+
+      df_analyze ();
+
+      df_dump (stderr);
+
+      df_finish_pass (false);
+
+DF_[chain,live,note,rd]_ADD_PROBLEM adds a problem, defined by an
+instance to struct df_problem, to the set of problems solved in this
+instance of df.  All calls to add a problem for a given instance of df
+must occur before the first call to DF_ANALYZE.
+
+Problems can be dependent on other problems.  For instance, solving
+def-use or use-def chains is dependent on solving reaching
+definitions. As long as these dependencies are listed in the problem
+definition, the order of adding the problems is not material.
+Otherwise, the problems will be solved in the order of calls to
+df_add_problem.  Note that it is not necessary to have a problem.  In
+that case, df will just be used to do the scanning.
+
+
+
+DF_SET_BLOCKS is an optional call used to define a region of the
+function on which the analysis will be performed.  The normal case is
+to analyze the entire function and no call to df_set_blocks is made.
+DF_SET_BLOCKS only effects the blocks that are effected when computing
+the transfer functions and final solution.  The insn level information
+is always kept up to date.
+
+When a subset is given, the analysis behaves as if the function only
+contains those blocks and any edges that occur directly between the
+blocks in the set.  Care should be taken to call df_set_blocks right
+before the call to analyze in order to eliminate the possibility that
+optimizations that reorder blocks invalidate the bitvector.
+
+DF_ANALYZE causes all of the defined problems to be (re)solved.  When
+DF_ANALYZE is completes, the IN and OUT sets for each basic block
+contain the computer information.  The DF_*_BB_INFO macros can be used
+to access these bitvectors.  All deferred rescannings are down before
+the transfer functions are recomputed.
+
+DF_DUMP can then be called to dump the information produce to some
+file.  This calls DF_DUMP_START, to print the information that is not
+basic block specific, and then calls DF_DUMP_TOP and DF_DUMP_BOTTOM
+for each block to print the basic specific information.  These parts
+can all be called separately as part of a larger dump function.
+
+
+DF_FINISH_PASS causes df_remove_problem to be called on all of the
+optional problems.  It also causes any insns whose scanning has been
+deferred to be rescanned as well as clears all of the changeable flags.
+Setting the pass manager TODO_df_finish flag causes this function to
+be run.  However, the pass manager will call df_finish_pass AFTER the
+pass dumping has been done, so if you want to see the results of the
+optional problems in the pass dumps, use the TODO flag rather than
+calling the function yourself.
+
+INCREMENTAL SCANNING
+
+There are four ways of doing the incremental scanning:
+
+1) Immediate rescanning - Calls to df_insn_rescan, df_notes_rescan,
+   df_bb_delete, df_insn_change_bb have been added to most of
+   the low level service functions that maintain the cfg and change
+   rtl.  Calling and of these routines many cause some number of insns
+   to be rescanned.
+
+   For most modern rtl passes, this is certainly the easiest way to
+   manage rescanning the insns.  This technique also has the advantage
+   that the scanning information is always correct and can be relied
+   upon even after changes have been made to the instructions.  This
+   technique is contra indicated in several cases:
+
+   a) If def-use chains OR use-def chains (but not both) are built,
+      using this is SIMPLY WRONG.  The problem is that when a ref is
+      deleted that is the target of an edge, there is not enough
+      information to efficiently find the source of the edge and
+      delete the edge.  This leaves a dangling reference that may
+      cause problems.
+
+   b) If def-use chains AND use-def chains are built, this may
+      produce unexpected results.  The problem is that the incremental
+      scanning of an insn does not know how to repair the chains that
+      point into an insn when the insn changes.  So the incremental
+      scanning just deletes the chains that enter and exit the insn
+      being changed.  The dangling reference issue in (a) is not a
+      problem here, but if the pass is depending on the chains being
+      maintained after insns have been modified, this technique will
+      not do the correct thing.
+
+   c) If the pass modifies insns several times, this incremental
+      updating may be expensive.
+
+   d) If the pass modifies all of the insns, as does register
+      allocation, it is simply better to rescan the entire function.
+
+   e) If the pass uses either non-standard or ancient techniques to
+      modify insns, automatic detection of the insns that need to be
+      rescanned may be impractical.  Cse and regrename fall into this
+      category.
+
+2) Deferred rescanning - Calls to df_insn_rescan, df_notes_rescan, and
+   df_insn_delete do not immediately change the insn but instead make
+   a note that the insn needs to be rescanned.  The next call to
+   df_analyze, df_finish_pass, or df_process_deferred_rescans will
+   cause all of the pending rescans to be processed.
+
+   This is the technique of choice if either 1a, 1b, or 1c are issues
+   in the pass.  In the case of 1a or 1b, a call to df_remove_problem
+   (df_chain) should be made before the next call to df_analyze or
+   df_process_deferred_rescans.
+
+   To enable this mode, call df_set_flags (DF_DEFER_INSN_RESCAN).
+   (This mode can be cleared by calling df_clear_flags
+   (DF_DEFER_INSN_RESCAN) but this does not cause the deferred insns to
+   be rescanned.
+
+   3) Total rescanning - In this mode the rescanning is disabled.
+   However, the df information associated with deleted insn is delete
+   at the time the insn is deleted.  At the end of the pass, a call
+   must be made to df_insn_rescan_all.  This method is used by the
+   register allocator since it generally changes each insn multiple
+   times (once for each ref) and does not need to make use of the
+   updated scanning information.
+
+   It is also currently used by two older passes (cse, and regrename)
+   which change insns in hard to track ways.  It is hoped that this
+   will be fixed soon since this it is expensive to rescan all of the
+   insns when only a small number of them have really changed.
+
+4) Do it yourself - In this mechanism, the pass updates the insns
+   itself using the low level df primitives.  Currently no pass does
+   this, but it has the advantage that it is quite efficient given
+   that the pass generally has exact knowledge of what it is changing.  
+
+DATA STRUCTURES
+
+Scanning produces a `struct df_ref' data structure (ref) is allocated
+for every register reference (def or use) and this records the insn
+and bb the ref is found within.  The refs are linked together in
+chains of uses and defs for each insn and for each register.  Each ref
+also has a chain field that links all the use refs for a def or all
+the def refs for a use.  This is used to create use-def or def-use
+chains.
+
+Different optimizations have different needs.  Ultimately, only
+register allocation and schedulers should be using the bitmaps
+produced for the live register and uninitialized register problems.
+The rest of the backend should be upgraded to using and maintaining
+the linked information such as def use or use def chains.
+
+
+PHILOSOPHY:
+
+While incremental bitmaps are not worthwhile to maintain, incremental
+chains may be perfectly reasonable.  The fastest way to build chains
+from scratch or after significant modifications is to build reaching
+definitions (RD) and build the chains from this.
+
+However, general algorithms for maintaining use-def or def-use chains
+are not practical.  The amount of work to recompute the chain any
+chain after an arbitrary change is large.  However, with a modest
+amount of work it is generally possible to have the application that
+uses the chains keep them up to date.  The high level knowledge of
+what is really happening is essential to crafting efficient
+incremental algorithms.
+
+As for the bit vector problems, there is no interface to give a set of
+blocks over with to resolve the iteration.  In general, restarting a
+dataflow iteration is difficult and expensive.  Again, the best way to
+keep the dataflow information up to data (if this is really what is
+needed) it to formulate a problem specific solution.
+
+There are fine grained calls for creating and deleting references from
+instructions in df-scan.c.  However, these are not currently connected
+to the engine that resolves the dataflow equations.
+
+
+DATA STRUCTURES:
+
+The basic object is a DF_REF (reference) and this may either be a 
+DEF (definition) or a USE of a register.
+
+These are linked into a variety of lists; namely reg-def, reg-use,
+insn-def, insn-use, def-use, and use-def lists.  For example, the
+reg-def lists contain all the locations that define a given register
+while the insn-use lists contain all the locations that use a
+register.
+
+Note that the reg-def and reg-use chains are generally short for
+pseudos and long for the hard registers.
+
+ACCESSING INSNS:
+
+1) The df insn information is kept in an array of DF_INSN_INFO objects.
+   The array is indexed by insn uid, and every DF_REF points to the
+   DF_INSN_INFO object of the insn that contains the reference.
+
+2) Each insn has three sets of refs, which are linked into one of three
+   lists: The insn's defs list (accessed by the DF_INSN_INFO_DEFS,
+   DF_INSN_DEFS, or DF_INSN_UID_DEFS macros), the insn's uses list
+   (accessed by the DF_INSN_INFO_USES, DF_INSN_USES, or
+   DF_INSN_UID_USES macros) or the insn's eq_uses list (accessed by the
+   DF_INSN_INFO_EQ_USES, DF_INSN_EQ_USES or DF_INSN_UID_EQ_USES macros).
+   The latter list are the list of references in REG_EQUAL or REG_EQUIV
+   notes.  These macros produce a ref (or NULL), the rest of the list
+   can be obtained by traversal of the NEXT_REF field (accessed by the
+   DF_REF_NEXT_REF macro.)  There is no significance to the ordering of
+   the uses or refs in an instruction.
+
+3) Each insn has a logical uid field (LUID) which is stored in the
+   DF_INSN_INFO object for the insn.  The LUID field is accessed by
+   the DF_INSN_INFO_LUID, DF_INSN_LUID, and DF_INSN_UID_LUID macros.
+   When properly set, the LUID is an integer that numbers each insn in
+   the basic block, in order from the start of the block.
+   The numbers are only correct after a call to df_analyze.  They will
+   rot after insns are added deleted or moved round.
+
+ACCESSING REFS:
+
+There are 4 ways to obtain access to refs:
+
+1) References are divided into two categories, REAL and ARTIFICIAL.
+
+   REAL refs are associated with instructions.  
+
+   ARTIFICIAL refs are associated with basic blocks.  The heads of
+   these lists can be accessed by calling df_get_artificial_defs or
+   df_get_artificial_uses for the particular basic block.  
+ 
+   Artificial defs and uses occur both at the beginning and ends of blocks.
+
+     For blocks that area at the destination of eh edges, the
+     artificial uses and defs occur at the beginning.  The defs relate
+     to the registers specified in EH_RETURN_DATA_REGNO and the uses
+     relate to the registers specified in ED_USES.  Logically these
+     defs and uses should really occur along the eh edge, but there is
+     no convenient way to do this.  Artificial edges that occur at the
+     beginning of the block have the DF_REF_AT_TOP flag set.
+
+     Artificial uses occur at the end of all blocks.  These arise from
+     the hard registers that are always live, such as the stack
+     register and are put there to keep the code from forgetting about
+     them.
+
+     Artificial defs occur at the end of the entry block.  These arise
+     from registers that are live at entry to the function.
+
+2) There are three types of refs: defs, uses and eq_uses.  (Eq_uses are 
+   uses that appear inside a REG_EQUAL or REG_EQUIV note.)
+
+   All of the eq_uses, uses and defs associated with each pseudo or
+   hard register may be linked in a bidirectional chain.  These are
+   called reg-use or reg_def chains.  If the changeable flag
+   DF_EQ_NOTES is set when the chains are built, the eq_uses will be
+   treated like uses.  If it is not set they are ignored.  
+
+   The first use, eq_use or def for a register can be obtained using
+   the DF_REG_USE_CHAIN, DF_REG_EQ_USE_CHAIN or DF_REG_DEF_CHAIN
+   macros.  Subsequent uses for the same regno can be obtained by
+   following the next_reg field of the ref.  The number of elements in
+   each of the chains can be found by using the DF_REG_USE_COUNT,
+   DF_REG_EQ_USE_COUNT or DF_REG_DEF_COUNT macros.
+
+   In previous versions of this code, these chains were ordered.  It
+   has not been practical to continue this practice.
+
+3) If def-use or use-def chains are built, these can be traversed to
+   get to other refs.  If the flag DF_EQ_NOTES has been set, the chains
+   include the eq_uses.  Otherwise these are ignored when building the
+   chains.
+
+4) An array of all of the uses (and an array of all of the defs) can
+   be built.  These arrays are indexed by the value in the id
+   structure.  These arrays are only lazily kept up to date, and that
+   process can be expensive.  To have these arrays built, call
+   df_reorganize_defs or df_reorganize_uses.  If the flag DF_EQ_NOTES
+   has been set the array will contain the eq_uses.  Otherwise these
+   are ignored when building the array and assigning the ids.  Note
+   that the values in the id field of a ref may change across calls to
+   df_analyze or df_reorganize_defs or df_reorganize_uses. 
+
+   If the only use of this array is to find all of the refs, it is
+   better to traverse all of the registers and then traverse all of
+   reg-use or reg-def chains.
+
+NOTES:
+ 
+Embedded addressing side-effects, such as POST_INC or PRE_INC, generate
+both a use and a def.  These are both marked read/write to show that they
+are dependent. For example, (set (reg 40) (mem (post_inc (reg 42))))
+will generate a use of reg 42 followed by a def of reg 42 (both marked
+read/write).  Similarly, (set (reg 40) (mem (pre_dec (reg 41))))
+generates a use of reg 41 then a def of reg 41 (both marked read/write),
+even though reg 41 is decremented before it is used for the memory
+address in this second example.
+
+A set to a REG inside a ZERO_EXTRACT, or a set to a non-paradoxical SUBREG
+for which the number of word_mode units covered by the outer mode is
+smaller than that covered by the inner mode, invokes a read-modify-write
+operation.  We generate both a use and a def and again mark them
+read/write.
+
+Paradoxical subreg writes do not leave a trace of the old content, so they
+are write-only operations.  
+*/
+
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "rtl.h"
+#include "tm_p.h"
+#include "insn-config.h"
+#include "recog.h"
+#include "function.h"
+#include "regs.h"
+#include "output.h"
+#include "alloc-pool.h"
+#include "flags.h"
+#include "hard-reg-set.h"
+#include "basic-block.h"
+#include "sbitmap.h"
+#include "bitmap.h"
+#include "timevar.h"
+#include "df.h"
+#include "tree-pass.h"
+#include "params.h"
+
+static void *df_get_bb_info (struct dataflow *, unsigned int);
+static void df_set_bb_info (struct dataflow *, unsigned int, void *);
+#ifdef DF_DEBUG_CFG
+static void df_set_clean_cfg (void);
+#endif
+
+/* An obstack for bitmap not related to specific dataflow problems.
+   This obstack should e.g. be used for bitmaps with a short life time
+   such as temporary bitmaps.  */
+
+bitmap_obstack df_bitmap_obstack;
+
+
+/*----------------------------------------------------------------------------
+  Functions to create, destroy and manipulate an instance of df.
+----------------------------------------------------------------------------*/
+
+struct df *df;
+
+/* Add PROBLEM (and any dependent problems) to the DF instance.  */
+
+void
+df_add_problem (struct df_problem *problem)
+{
+  struct dataflow *dflow;
+  int i;
+
+  /* First try to add the dependent problem. */
+  if (problem->dependent_problem)
+    df_add_problem (problem->dependent_problem);
+
+  /* Check to see if this problem has already been defined.  If it
+     has, just return that instance, if not, add it to the end of the
+     vector.  */
+  dflow = df->problems_by_index[problem->id];
+  if (dflow)
+    return;
+
+  /* Make a new one and add it to the end.  */
+  dflow = XCNEW (struct dataflow);
+  dflow->problem = problem;
+  dflow->computed = false;
+  dflow->solutions_dirty = true;
+  df->problems_by_index[dflow->problem->id] = dflow;
+
+  /* Keep the defined problems ordered by index.  This solves the
+     problem that RI will use the information from UREC if UREC has
+     been defined, or from LIVE if LIVE is defined and otherwise LR.
+     However for this to work, the computation of RI must be pushed
+     after which ever of those problems is defined, but we do not
+     require any of those except for LR to have actually been
+     defined.  */ 
+  df->num_problems_defined++;
+  for (i = df->num_problems_defined - 2; i >= 0; i--)
+    {
+      if (problem->id < df->problems_in_order[i]->problem->id)
+	df->problems_in_order[i+1] = df->problems_in_order[i];
+      else
+	{
+	  df->problems_in_order[i+1] = dflow;
+	  return;
+	}
+    }
+  df->problems_in_order[0] = dflow;
+}
+
+
+/* Set the MASK flags in the DFLOW problem.  The old flags are
+   returned.  If a flag is not allowed to be changed this will fail if
+   checking is enabled.  */
+enum df_changeable_flags
+df_set_flags (enum df_changeable_flags changeable_flags)
+{
+  enum df_changeable_flags old_flags = df->changeable_flags;
+  df->changeable_flags |= changeable_flags;
+  return old_flags;
+}
+
+
+/* Clear the MASK flags in the DFLOW problem.  The old flags are
+   returned.  If a flag is not allowed to be changed this will fail if
+   checking is enabled.  */
+enum df_changeable_flags
+df_clear_flags (enum df_changeable_flags changeable_flags)
+{
+  enum df_changeable_flags old_flags = df->changeable_flags;
+  df->changeable_flags &= ~changeable_flags;
+  return old_flags;
+}
+
+
+/* Set the blocks that are to be considered for analysis.  If this is
+   not called or is called with null, the entire function in
+   analyzed.  */
+
+void 
+df_set_blocks (bitmap blocks)
+{
+  if (blocks)
+    {
+      if (dump_file)
+	bitmap_print (dump_file, blocks, "setting blocks to analyze ", "\n");
+      if (df->blocks_to_analyze)
+	{
+	  /* This block is called to change the focus from one subset
+	     to another.  */
+	  int p;
+	  bitmap diff = BITMAP_ALLOC (&df_bitmap_obstack);
+	  bitmap_and_compl (diff, df->blocks_to_analyze, blocks);
+	  for (p = 0; p < df->num_problems_defined; p++)
+	    {
+	      struct dataflow *dflow = df->problems_in_order[p];
+	      if (dflow->optional_p && dflow->problem->reset_fun)
+		dflow->problem->reset_fun (df->blocks_to_analyze);
+	      else if (dflow->problem->free_blocks_on_set_blocks)
+		{
+		  bitmap_iterator bi;
+		  unsigned int bb_index;
+		  
+		  EXECUTE_IF_SET_IN_BITMAP (diff, 0, bb_index, bi)
+		    {
+		      basic_block bb = BASIC_BLOCK (bb_index);
+		      if (bb)
+			{
+			  void *bb_info = df_get_bb_info (dflow, bb_index);
+			  if (bb_info)
+			    {
+			      dflow->problem->free_bb_fun (bb, bb_info);
+			      df_set_bb_info (dflow, bb_index, NULL);
+			    }
+			}
+		    }
+		}
+	    }
+
+	  BITMAP_FREE (diff);
+	}
+      else
+	{
+	  /* This block of code is executed to change the focus from
+	     the entire function to a subset.  */
+	  bitmap blocks_to_reset = NULL;
+	  int p;
+	  for (p = 0; p < df->num_problems_defined; p++)
+	    {
+	      struct dataflow *dflow = df->problems_in_order[p];
+	      if (dflow->optional_p && dflow->problem->reset_fun)
+		{
+		  if (!blocks_to_reset)
+		    {
+		      basic_block bb;
+		      blocks_to_reset =
+			BITMAP_ALLOC (&df_bitmap_obstack);
+		      FOR_ALL_BB(bb)
+			{
+			  bitmap_set_bit (blocks_to_reset, bb->index); 
+			}
+		    }
+		  dflow->problem->reset_fun (blocks_to_reset);
+		}
+	    }
+	  if (blocks_to_reset)
+	    BITMAP_FREE (blocks_to_reset);
+
+	  df->blocks_to_analyze = BITMAP_ALLOC (&df_bitmap_obstack);
+	}
+      bitmap_copy (df->blocks_to_analyze, blocks);
+      df->analyze_subset = true;
+    }
+  else
+    {
+      /* This block is executed to reset the focus to the entire
+	 function.  */
+      if (dump_file)
+	fprintf (dump_file, "clearing blocks_to_analyze\n");
+      if (df->blocks_to_analyze)
+	{
+	  BITMAP_FREE (df->blocks_to_analyze);
+	  df->blocks_to_analyze = NULL;
+	}
+      df->analyze_subset = false;
+    }
+
+  /* Setting the blocks causes the refs to be unorganized since only
+     the refs in the blocks are seen.  */
+  df_maybe_reorganize_def_refs (DF_REF_ORDER_NO_TABLE);
+  df_maybe_reorganize_use_refs (DF_REF_ORDER_NO_TABLE);
+  df_mark_solutions_dirty ();
+}
+
+
+/* Delete a DFLOW problem (and any problems that depend on this
+   problem).  */
+
+void
+df_remove_problem (struct dataflow *dflow)
+{
+  struct df_problem *problem;
+  int i;
+
+  if (!dflow)
+    return;
+
+  problem = dflow->problem;
+  gcc_assert (problem->remove_problem_fun);
+
+  /* Delete any problems that depended on this problem first.  */
+  for (i = 0; i < df->num_problems_defined; i++)
+    if (df->problems_in_order[i]->problem->dependent_problem == problem)
+      df_remove_problem (df->problems_in_order[i]);
+
+  /* Now remove this problem.  */
+  for (i = 0; i < df->num_problems_defined; i++)
+    if (df->problems_in_order[i] == dflow)
+      {
+	int j;
+	for (j = i + 1; j < df->num_problems_defined; j++)
+	  df->problems_in_order[j-1] = df->problems_in_order[j];
+	df->problems_in_order[j-1] = NULL;
+	df->num_problems_defined--;
+	break;
+      }
+
+  (problem->remove_problem_fun) ();
+  df->problems_by_index[problem->id] = NULL;
+}
+
+
+/* Remove all of the problems that are not permanent.  Scanning, LR
+   and (at -O2 or higher) LIVE are permanent, the rest are removable.
+   Also clear all of the changeable_flags.  */
+
+void
+df_finish_pass (bool verify ATTRIBUTE_UNUSED)
+{
+  int i;
+  int removed = 0;
+
+#ifdef ENABLE_DF_CHECKING
+  enum df_changeable_flags saved_flags;
+#endif
+
+  if (!df)
+    return;
+
+  df_maybe_reorganize_def_refs (DF_REF_ORDER_NO_TABLE);
+  df_maybe_reorganize_use_refs (DF_REF_ORDER_NO_TABLE);
+
+#ifdef ENABLE_DF_CHECKING
+  saved_flags = df->changeable_flags;
+#endif
+
+  for (i = 0; i < df->num_problems_defined; i++)
+    {
+      struct dataflow *dflow = df->problems_in_order[i];
+      struct df_problem *problem = dflow->problem;
+
+      if (dflow->optional_p)
+	{
+	  gcc_assert (problem->remove_problem_fun);
+	  (problem->remove_problem_fun) ();
+	  df->problems_in_order[i] = NULL;
+	  df->problems_by_index[problem->id] = NULL;
+	  removed++;
+	}
+    }
+  df->num_problems_defined -= removed;
+
+  /* Clear all of the flags.  */
+  df->changeable_flags = 0;
+  df_process_deferred_rescans ();
+
+  /* Set the focus back to the whole function.  */
+  if (df->blocks_to_analyze)
+    {
+      BITMAP_FREE (df->blocks_to_analyze);
+      df->blocks_to_analyze = NULL;
+      df_mark_solutions_dirty ();
+      df->analyze_subset = false;
+    }
+
+#ifdef ENABLE_DF_CHECKING
+  /* Verification will fail in DF_NO_INSN_RESCAN.  */
+  if (!(saved_flags & DF_NO_INSN_RESCAN))
+    {
+      df_lr_verify_transfer_functions ();
+      if (df_live)
+	df_live_verify_transfer_functions ();
+    }
+
+#ifdef DF_DEBUG_CFG
+  df_set_clean_cfg ();
+#endif
+#endif
+
+#ifdef ENABLE_CHECKING
+  if (verify)
+    df->changeable_flags |= DF_VERIFY_SCHEDULED;
+#endif
+}
+
+
+/* Set up the dataflow instance for the entire back end.  */
+
+static unsigned int
+rest_of_handle_df_initialize (void)
+{
+  gcc_assert (!df);
+  df = XCNEW (struct df);
+  df->changeable_flags = 0;
+
+  bitmap_obstack_initialize (&df_bitmap_obstack);
+
+  /* Set this to a conservative value.  Stack_ptr_mod will compute it
+     correctly later.  */
+  current_function_sp_is_unchanging = 0;
+
+  df_scan_add_problem ();
+  df_scan_alloc (NULL);
+
+  /* These three problems are permanent.  */
+  df_lr_add_problem ();
+  if (optimize > 1)
+    df_live_add_problem ();
+
+  df->postorder = XNEWVEC (int, last_basic_block);
+  df->postorder_inverted = XNEWVEC (int, last_basic_block);
+  df->n_blocks = post_order_compute (df->postorder, true, true);
+  df->n_blocks_inverted = inverted_post_order_compute (df->postorder_inverted);
+  gcc_assert (df->n_blocks == df->n_blocks_inverted);
+
+  df->hard_regs_live_count = XNEWVEC (unsigned int, FIRST_PSEUDO_REGISTER);
+  memset (df->hard_regs_live_count, 0, 
+	  sizeof (unsigned int) * FIRST_PSEUDO_REGISTER);
+
+  df_hard_reg_init ();
+  /* After reload, some ports add certain bits to regs_ever_live so
+     this cannot be reset.  */
+  df_compute_regs_ever_live (true);
+  df_scan_blocks ();
+  df_compute_regs_ever_live (false);
+  return 0;
+}
+
+
+static bool
+gate_opt (void)
+{
+  return optimize > 0;
+}
+
+
+struct rtl_opt_pass pass_df_initialize_opt =
+{
+ {
+  RTL_PASS,
+  "dfinit",                             /* name */
+  gate_opt,                             /* gate */
+  rest_of_handle_df_initialize,         /* execute */
+  NULL,                                 /* sub */
+  NULL,                                 /* next */
+  0,                                    /* static_pass_number */
+  0,                                    /* tv_id */
+  0,                                    /* properties_required */
+  0,                                    /* properties_provided */
+  0,                                    /* properties_destroyed */
+  0,                                    /* todo_flags_start */
+  0                                     /* todo_flags_finish */
+ }
+};
+
+
+static bool
+gate_no_opt (void)
+{
+  return optimize == 0;
+}
+
+
+struct rtl_opt_pass pass_df_initialize_no_opt =
+{
+ {
+  RTL_PASS,
+  "dfinit",                             /* name */
+  gate_no_opt,                          /* gate */
+  rest_of_handle_df_initialize,         /* execute */
+  NULL,                                 /* sub */
+  NULL,                                 /* next */
+  0,                                    /* static_pass_number */
+  0,                                    /* tv_id */
+  0,                                    /* properties_required */
+  0,                                    /* properties_provided */
+  0,                                    /* properties_destroyed */
+  0,                                    /* todo_flags_start */
+  0                                     /* todo_flags_finish */
+ }
+};
+
+
+/* Free all the dataflow info and the DF structure.  This should be
+   called from the df_finish macro which also NULLs the parm.  */
+
+static unsigned int
+rest_of_handle_df_finish (void)
+{
+  int i;
+
+  gcc_assert (df);
+
+  for (i = 0; i < df->num_problems_defined; i++)
+    {
+      struct dataflow *dflow = df->problems_in_order[i];
+      dflow->problem->free_fun (); 
+    }
+
+  if (df->postorder)
+    free (df->postorder);
+  if (df->postorder_inverted)
+    free (df->postorder_inverted);
+  free (df->hard_regs_live_count);
+  free (df);
+  df = NULL;
+
+  bitmap_obstack_release (&df_bitmap_obstack);
+  return 0;
+}
+
+
+struct rtl_opt_pass pass_df_finish =
+{
+ {
+  RTL_PASS,
+  "dfinish",                            /* name */
+  NULL,					/* gate */
+  rest_of_handle_df_finish,             /* execute */
+  NULL,                                 /* sub */
+  NULL,                                 /* next */
+  0,                                    /* static_pass_number */
+  0,                                    /* tv_id */
+  0,                                    /* properties_required */
+  0,                                    /* properties_provided */
+  0,                                    /* properties_destroyed */
+  0,                                    /* todo_flags_start */
+  0                                     /* todo_flags_finish */
+ }
+};
+
+
+
+
+
+/*----------------------------------------------------------------------------
+   The general data flow analysis engine.
+----------------------------------------------------------------------------*/
+
+
+/* Helper function for df_worklist_dataflow.
+   Propagate the dataflow forward. 
+   Given a BB_INDEX, do the dataflow propagation
+   and set bits on for successors in PENDING
+   if the out set of the dataflow has changed. */
+
+static void
+df_worklist_propagate_forward (struct dataflow *dataflow,
+                               unsigned bb_index,
+                               unsigned *bbindex_to_postorder,
+                               bitmap pending,
+                               sbitmap considered)
+{
+  edge e;
+  edge_iterator ei;
+  basic_block bb = BASIC_BLOCK (bb_index);
+
+  /*  Calculate <conf_op> of incoming edges.  */
+  if (EDGE_COUNT (bb->preds) > 0)
+    FOR_EACH_EDGE (e, ei, bb->preds)
+      {								
+        if (TEST_BIT (considered, e->src->index))		
+          dataflow->problem->con_fun_n (e);
+      }								
+  else if (dataflow->problem->con_fun_0)
+    dataflow->problem->con_fun_0 (bb);
+
+  if (dataflow->problem->trans_fun (bb_index))
+    {
+      /* The out set of this block has changed. 
+         Propagate to the outgoing blocks.  */
+      FOR_EACH_EDGE (e, ei, bb->succs)
+        {
+          unsigned ob_index = e->dest->index;
+
+          if (TEST_BIT (considered, ob_index))
+            bitmap_set_bit (pending, bbindex_to_postorder[ob_index]);
+        }
+    }
+}
+
+
+/* Helper function for df_worklist_dataflow.
+   Propagate the dataflow backward.  */
+
+static void
+df_worklist_propagate_backward (struct dataflow *dataflow,
+                                unsigned bb_index,
+                                unsigned *bbindex_to_postorder,
+                                bitmap pending,
+                                sbitmap considered)
+{
+  edge e;
+  edge_iterator ei;
+  basic_block bb = BASIC_BLOCK (bb_index);
+
+  /*  Calculate <conf_op> of incoming edges.  */
+  if (EDGE_COUNT (bb->succs) > 0)
+    FOR_EACH_EDGE (e, ei, bb->succs)
+      {								
+        if (TEST_BIT (considered, e->dest->index))		
+          dataflow->problem->con_fun_n (e);
+      }								
+  else if (dataflow->problem->con_fun_0)
+    dataflow->problem->con_fun_0 (bb);
+
+  if (dataflow->problem->trans_fun (bb_index))
+    {
+      /* The out set of this block has changed. 
+         Propagate to the outgoing blocks.  */
+      FOR_EACH_EDGE (e, ei, bb->preds)
+        {
+          unsigned ob_index = e->src->index;
+
+          if (TEST_BIT (considered, ob_index))
+            bitmap_set_bit (pending, bbindex_to_postorder[ob_index]);
+        }
+    }
+}
+
+
+
+/* This will free "pending". */
+
+static void 
+df_worklist_dataflow_doublequeue (struct dataflow *dataflow,
+			  	  bitmap pending,
+                                  sbitmap considered,
+                                  int *blocks_in_postorder,
+				  unsigned *bbindex_to_postorder)
+{
+  enum df_flow_dir dir = dataflow->problem->dir;
+  int dcount = 0;
+  bitmap worklist = BITMAP_ALLOC (&df_bitmap_obstack);
+
+  /* Double-queueing. Worklist is for the current iteration,
+     and pending is for the next. */
+  while (!bitmap_empty_p (pending))
+    {
+      /* Swap pending and worklist. */
+      bitmap temp = worklist;
+      worklist = pending;
+      pending = temp;
+
+      do
+	{
+	  int index;
+	  unsigned bb_index;
+	  dcount++;
+
+	  index = bitmap_first_set_bit (worklist);
+	  bitmap_clear_bit (worklist, index);
+
+	  bb_index = blocks_in_postorder[index];
+
+	  if (dir == DF_FORWARD)
+	    df_worklist_propagate_forward (dataflow, bb_index,
+					   bbindex_to_postorder,
+					   pending, considered);
+	  else 
+	    df_worklist_propagate_backward (dataflow, bb_index,
+					    bbindex_to_postorder,
+					    pending, considered);
+	}
+      while (!bitmap_empty_p (worklist));
+    }
+
+  BITMAP_FREE (worklist);
+  BITMAP_FREE (pending);
+
+  /* Dump statistics. */
+  if (dump_file)
+    fprintf (dump_file, "df_worklist_dataflow_doublequeue:"
+	     "n_basic_blocks %d n_edges %d"
+	     " count %d (%5.2g)\n",
+	     n_basic_blocks, n_edges,
+	     dcount, dcount / (float)n_basic_blocks);
+}
+
+/* Worklist-based dataflow solver. It uses sbitmap as a worklist,
+   with "n"-th bit representing the n-th block in the reverse-postorder order. 
+   The solver is a double-queue algorithm similar to the "double stack" solver
+   from Cooper, Harvey and Kennedy, "Iterative data-flow analysis, Revisited".
+   The only significant difference is that the worklist in this implementation
+   is always sorted in RPO of the CFG visiting direction.  */
+
+void 
+df_worklist_dataflow (struct dataflow *dataflow,
+                      bitmap blocks_to_consider,
+                      int *blocks_in_postorder,
+                      int n_blocks)
+{
+  bitmap pending = BITMAP_ALLOC (&df_bitmap_obstack);
+  sbitmap considered = sbitmap_alloc (last_basic_block);
+  bitmap_iterator bi;
+  unsigned int *bbindex_to_postorder;
+  int i;
+  unsigned int index;
+  enum df_flow_dir dir = dataflow->problem->dir;
+
+  gcc_assert (dir != DF_NONE);
+
+  /* BBINDEX_TO_POSTORDER maps the bb->index to the reverse postorder.  */
+  bbindex_to_postorder =
+    (unsigned int *)xmalloc (last_basic_block * sizeof (unsigned int));
+
+  /* Initialize the array to an out-of-bound value.  */
+  for (i = 0; i < last_basic_block; i++)
+    bbindex_to_postorder[i] = last_basic_block;
+
+  /* Initialize the considered map.  */
+  sbitmap_zero (considered);
+  EXECUTE_IF_SET_IN_BITMAP (blocks_to_consider, 0, index, bi)
+    {
+      SET_BIT (considered, index);
+    }
+
+  /* Initialize the mapping of block index to postorder.  */
+  for (i = 0; i < n_blocks; i++)
+    {
+      bbindex_to_postorder[blocks_in_postorder[i]] = i;
+      /* Add all blocks to the worklist.  */
+      bitmap_set_bit (pending, i);
+    }
+
+  /* Initialize the problem. */
+  if (dataflow->problem->init_fun)
+    dataflow->problem->init_fun (blocks_to_consider);
+
+  /* Solve it.  */
+  df_worklist_dataflow_doublequeue (dataflow, pending, considered,
+				    blocks_in_postorder,
+				    bbindex_to_postorder);
+
+  sbitmap_free (considered);
+  free (bbindex_to_postorder);
+}
+
+
+/* Remove the entries not in BLOCKS from the LIST of length LEN, preserving
+   the order of the remaining entries.  Returns the length of the resulting
+   list.  */
+
+static unsigned
+df_prune_to_subcfg (int list[], unsigned len, bitmap blocks)
+{
+  unsigned act, last;
+
+  for (act = 0, last = 0; act < len; act++)
+    if (bitmap_bit_p (blocks, list[act]))
+      list[last++] = list[act];
+
+  return last;
+}
+
+
+/* Execute dataflow analysis on a single dataflow problem. 
+
+   BLOCKS_TO_CONSIDER are the blocks whose solution can either be
+   examined or will be computed.  For calls from DF_ANALYZE, this is
+   the set of blocks that has been passed to DF_SET_BLOCKS.  
+*/
+
+void
+df_analyze_problem (struct dataflow *dflow, 
+		    bitmap blocks_to_consider, 
+		    int *postorder, int n_blocks)
+{
+  timevar_push (dflow->problem->tv_id);
+
+#ifdef ENABLE_DF_CHECKING
+  if (dflow->problem->verify_start_fun)
+    dflow->problem->verify_start_fun ();
+#endif
+
+  /* (Re)Allocate the datastructures necessary to solve the problem.  */ 
+  if (dflow->problem->alloc_fun)
+    dflow->problem->alloc_fun (blocks_to_consider);
+
+  /* Set up the problem and compute the local information.  */
+  if (dflow->problem->local_compute_fun)
+    dflow->problem->local_compute_fun (blocks_to_consider);
+
+  /* Solve the equations.  */
+  if (dflow->problem->dataflow_fun)
+    dflow->problem->dataflow_fun (dflow, blocks_to_consider,
+				  postorder, n_blocks);
+
+  /* Massage the solution.  */
+  if (dflow->problem->finalize_fun)
+    dflow->problem->finalize_fun (blocks_to_consider);
+
+#ifdef ENABLE_DF_CHECKING
+  if (dflow->problem->verify_end_fun)
+    dflow->problem->verify_end_fun ();
+#endif
+
+  timevar_pop (dflow->problem->tv_id);
+
+  dflow->computed = true;
+}
+
+
+/* Analyze dataflow info for the basic blocks specified by the bitmap
+   BLOCKS, or for the whole CFG if BLOCKS is zero.  */
+
+void
+df_analyze (void)
+{
+  bitmap current_all_blocks = BITMAP_ALLOC (&df_bitmap_obstack);
+  bool everything;
+  int i;
+  
+  if (df->postorder)
+    free (df->postorder);
+  if (df->postorder_inverted)
+    free (df->postorder_inverted);
+  df->postorder = XNEWVEC (int, last_basic_block);
+  df->postorder_inverted = XNEWVEC (int, last_basic_block);
+  df->n_blocks = post_order_compute (df->postorder, true, true);
+  df->n_blocks_inverted = inverted_post_order_compute (df->postorder_inverted);
+
+  /* These should be the same.  */
+  gcc_assert (df->n_blocks == df->n_blocks_inverted);
+
+  /* We need to do this before the df_verify_all because this is
+     not kept incrementally up to date.  */
+  df_compute_regs_ever_live (false);
+  df_process_deferred_rescans ();
+
+  if (dump_file)
+    fprintf (dump_file, "df_analyze called\n");
+
+#ifndef ENABLE_DF_CHECKING
+  if (df->changeable_flags & DF_VERIFY_SCHEDULED)
+#endif
+    df_verify ();
+
+  for (i = 0; i < df->n_blocks; i++)
+    bitmap_set_bit (current_all_blocks, df->postorder[i]);
+
+#ifdef ENABLE_CHECKING
+  /* Verify that POSTORDER_INVERTED only contains blocks reachable from
+     the ENTRY block.  */
+  for (i = 0; i < df->n_blocks_inverted; i++)
+    gcc_assert (bitmap_bit_p (current_all_blocks, df->postorder_inverted[i]));
+#endif
+
+  /* Make sure that we have pruned any unreachable blocks from these
+     sets.  */
+  if (df->analyze_subset)
+    {
+      everything = false;
+      bitmap_and_into (df->blocks_to_analyze, current_all_blocks);
+      df->n_blocks = df_prune_to_subcfg (df->postorder, 
+					 df->n_blocks, df->blocks_to_analyze);
+      df->n_blocks_inverted = df_prune_to_subcfg (df->postorder_inverted, 
+			                          df->n_blocks_inverted, 
+                                                  df->blocks_to_analyze);
+      BITMAP_FREE (current_all_blocks);
+    }
+  else
+    {
+      everything = true;
+      df->blocks_to_analyze = current_all_blocks;
+      current_all_blocks = NULL;
+    }
+
+  /* Skip over the DF_SCAN problem. */
+  for (i = 1; i < df->num_problems_defined; i++)
+    {
+      struct dataflow *dflow = df->problems_in_order[i];
+      if (dflow->solutions_dirty)
+        {
+          if (dflow->problem->dir == DF_FORWARD)
+            df_analyze_problem (dflow,
+                                df->blocks_to_analyze,
+                                df->postorder_inverted,
+                                df->n_blocks_inverted);
+          else
+            df_analyze_problem (dflow,
+                                df->blocks_to_analyze,
+                                df->postorder,
+                                df->n_blocks);
+        }
+    }
+
+  if (everything)
+    {
+      BITMAP_FREE (df->blocks_to_analyze);
+      df->blocks_to_analyze = NULL;
+    }
+
+#ifdef DF_DEBUG_CFG
+  df_set_clean_cfg ();
+#endif
+}
+
+
+/* Return the number of basic blocks from the last call to df_analyze.  */
+
+int 
+df_get_n_blocks (enum df_flow_dir dir)
+{
+  gcc_assert (dir != DF_NONE);
+
+  if (dir == DF_FORWARD)
+    {
+      gcc_assert (df->postorder_inverted);
+      return df->n_blocks_inverted;
+    }
+
+  gcc_assert (df->postorder);
+  return df->n_blocks;
+}
+
+
+/* Return a pointer to the array of basic blocks in the reverse postorder. 
+   Depending on the direction of the dataflow problem,
+   it returns either the usual reverse postorder array
+   or the reverse postorder of inverted traversal. */
+int *
+df_get_postorder (enum df_flow_dir dir)
+{
+  gcc_assert (dir != DF_NONE);
+
+  if (dir == DF_FORWARD)
+    {
+      gcc_assert (df->postorder_inverted);
+      return df->postorder_inverted;
+    }
+  gcc_assert (df->postorder);
+  return df->postorder;
+}
+
+static struct df_problem user_problem; 
+static struct dataflow user_dflow;
+
+/* Interface for calling iterative dataflow with user defined
+   confluence and transfer functions.  All that is necessary is to
+   supply DIR, a direction, CONF_FUN_0, a confluence function for
+   blocks with no logical preds (or NULL), CONF_FUN_N, the normal
+   confluence function, TRANS_FUN, the basic block transfer function,
+   and BLOCKS, the set of blocks to examine, POSTORDER the blocks in
+   postorder, and N_BLOCKS, the number of blocks in POSTORDER. */
+
+void
+df_simple_dataflow (enum df_flow_dir dir,
+		    df_init_function init_fun,
+		    df_confluence_function_0 con_fun_0,
+		    df_confluence_function_n con_fun_n,
+		    df_transfer_function trans_fun,
+		    bitmap blocks, int * postorder, int n_blocks)
+{
+  memset (&user_problem, 0, sizeof (struct df_problem));
+  user_problem.dir = dir;
+  user_problem.init_fun = init_fun;
+  user_problem.con_fun_0 = con_fun_0;
+  user_problem.con_fun_n = con_fun_n;
+  user_problem.trans_fun = trans_fun;
+  user_dflow.problem = &user_problem;
+  df_worklist_dataflow (&user_dflow, blocks, postorder, n_blocks);
+}
+
+			      
+
+/*----------------------------------------------------------------------------
+   Functions to support limited incremental change.
+----------------------------------------------------------------------------*/
+
+
+/* Get basic block info.  */
+
+static void *
+df_get_bb_info (struct dataflow *dflow, unsigned int index)
+{
+  if (dflow->block_info == NULL)
+    return NULL;
+  if (index >= dflow->block_info_size)
+    return NULL;
+  return (struct df_scan_bb_info *) dflow->block_info[index];
+}
+
+
+/* Set basic block info.  */
+
+static void
+df_set_bb_info (struct dataflow *dflow, unsigned int index, 
+		void *bb_info)
+{
+  gcc_assert (dflow->block_info);
+  dflow->block_info[index] = bb_info;
+}
+
+
+/* Mark the solutions as being out of date.  */
+
+void 
+df_mark_solutions_dirty (void)
+{
+  if (df)
+    {
+      int p; 
+      for (p = 1; p < df->num_problems_defined; p++)
+	df->problems_in_order[p]->solutions_dirty = true;
+    }
+}
+
+
+/* Return true if BB needs it's transfer functions recomputed.  */
+
+bool 
+df_get_bb_dirty (basic_block bb)
+{
+  if (df && df_live)
+    return bitmap_bit_p (df_live->out_of_date_transfer_functions, bb->index);
+  else 
+    return false;
+}
+
+
+/* Mark BB as needing it's transfer functions as being out of
+   date.  */
+
+void 
+df_set_bb_dirty (basic_block bb)
+{
+  if (df)
+    {
+      int p; 
+      for (p = 1; p < df->num_problems_defined; p++)
+	{
+	  struct dataflow *dflow = df->problems_in_order[p];
+	  if (dflow->out_of_date_transfer_functions)
+	    bitmap_set_bit (dflow->out_of_date_transfer_functions, bb->index);
+	}
+      df_mark_solutions_dirty ();
+    }
+}
+
+
+/* Clear the dirty bits.  This is called from places that delete
+   blocks.  */
+static void
+df_clear_bb_dirty (basic_block bb)
+{
+  int p; 
+  for (p = 1; p < df->num_problems_defined; p++)
+    {
+      struct dataflow *dflow = df->problems_in_order[p];
+      if (dflow->out_of_date_transfer_functions)
+	bitmap_clear_bit (dflow->out_of_date_transfer_functions, bb->index);
+    }
+}
+/* Called from the rtl_compact_blocks to reorganize the problems basic
+   block info.  */
+
+void 
+df_compact_blocks (void)
+{
+  int i, p;
+  basic_block bb;
+  void **problem_temps;
+  int size = last_basic_block * sizeof (void *);
+  bitmap tmp = BITMAP_ALLOC (&df_bitmap_obstack);
+  problem_temps = XNEWVAR (void *, size);
+
+  for (p = 0; p < df->num_problems_defined; p++)
+    {
+      struct dataflow *dflow = df->problems_in_order[p];
+
+      /* Need to reorganize the out_of_date_transfer_functions for the
+	 dflow problem.  */
+      if (dflow->out_of_date_transfer_functions)
+	{
+	  bitmap_copy (tmp, dflow->out_of_date_transfer_functions);
+	  bitmap_clear (dflow->out_of_date_transfer_functions);
+	  if (bitmap_bit_p (tmp, ENTRY_BLOCK))
+	    bitmap_set_bit (dflow->out_of_date_transfer_functions, ENTRY_BLOCK);
+	  if (bitmap_bit_p (tmp, EXIT_BLOCK))
+	    bitmap_set_bit (dflow->out_of_date_transfer_functions, EXIT_BLOCK);
+
+	  i = NUM_FIXED_BLOCKS;
+	  FOR_EACH_BB (bb) 
+	    {
+	      if (bitmap_bit_p (tmp, bb->index))
+		bitmap_set_bit (dflow->out_of_date_transfer_functions, i);
+	      i++;
+	    }
+	}
+
+      /* Now shuffle the block info for the problem.  */
+      if (dflow->problem->free_bb_fun)
+	{
+	  df_grow_bb_info (dflow);
+	  memcpy (problem_temps, dflow->block_info, size);
+
+	  /* Copy the bb info from the problem tmps to the proper
+	     place in the block_info vector.  Null out the copied
+	     item.  The entry and exit blocks never move.  */
+	  i = NUM_FIXED_BLOCKS;
+	  FOR_EACH_BB (bb) 
+	    {
+	      df_set_bb_info (dflow, i, problem_temps[bb->index]);
+	      problem_temps[bb->index] = NULL;
+	      i++;
+	    }
+	  memset (dflow->block_info + i, 0, 
+		  (last_basic_block - i) *sizeof (void *));
+
+	  /* Free any block infos that were not copied (and NULLed).
+	     These are from orphaned blocks.  */
+	  for (i = NUM_FIXED_BLOCKS; i < last_basic_block; i++)
+	    {
+	      basic_block bb = BASIC_BLOCK (i); 
+	      if (problem_temps[i] && bb)
+		dflow->problem->free_bb_fun
+		  (bb, problem_temps[i]);
+	    }
+	}
+    }
+
+  /* Shuffle the bits in the basic_block indexed arrays.  */
+
+  if (df->blocks_to_analyze)
+    {
+      if (bitmap_bit_p (tmp, ENTRY_BLOCK))
+	bitmap_set_bit (df->blocks_to_analyze, ENTRY_BLOCK);
+      if (bitmap_bit_p (tmp, EXIT_BLOCK))
+	bitmap_set_bit (df->blocks_to_analyze, EXIT_BLOCK);
+      bitmap_copy (tmp, df->blocks_to_analyze);
+      bitmap_clear (df->blocks_to_analyze);
+      i = NUM_FIXED_BLOCKS;
+      FOR_EACH_BB (bb) 
+	{
+	  if (bitmap_bit_p (tmp, bb->index))
+	    bitmap_set_bit (df->blocks_to_analyze, i);
+	  i++;
+	}
+    }
+
+  BITMAP_FREE (tmp);
+
+  free (problem_temps);
+
+  i = NUM_FIXED_BLOCKS;
+  FOR_EACH_BB (bb) 
+    {
+      SET_BASIC_BLOCK (i, bb);
+      bb->index = i;
+      i++;
+    }
+
+  gcc_assert (i == n_basic_blocks);
+
+  for (; i < last_basic_block; i++)
+    SET_BASIC_BLOCK (i, NULL);
+
+#ifdef DF_DEBUG_CFG
+  if (!df_lr->solutions_dirty)
+    df_set_clean_cfg ();
+#endif
+}
+
+
+/* Shove NEW_BLOCK in at OLD_INDEX.  Called from ifcvt to hack a
+   block.  There is no excuse for people to do this kind of thing.  */
+
+void 
+df_bb_replace (int old_index, basic_block new_block)
+{
+  int new_block_index = new_block->index;
+  int p;
+
+  if (dump_file)
+    fprintf (dump_file, "shoving block %d into %d\n", new_block_index, old_index);
+
+  gcc_assert (df);
+  gcc_assert (BASIC_BLOCK (old_index) == NULL);
+
+  for (p = 0; p < df->num_problems_defined; p++)
+    {
+      struct dataflow *dflow = df->problems_in_order[p];
+      if (dflow->block_info)
+	{
+	  df_grow_bb_info (dflow);
+	  gcc_assert (df_get_bb_info (dflow, old_index) == NULL);
+	  df_set_bb_info (dflow, old_index, 
+			  df_get_bb_info (dflow, new_block_index));
+	}
+    }
+
+  df_clear_bb_dirty (new_block);
+  SET_BASIC_BLOCK (old_index, new_block);
+  new_block->index = old_index;
+  df_set_bb_dirty (BASIC_BLOCK (old_index));
+  SET_BASIC_BLOCK (new_block_index, NULL);
+}
+
+
+/* Free all of the per basic block dataflow from all of the problems.
+   This is typically called before a basic block is deleted and the
+   problem will be reanalyzed.  */
+
+void
+df_bb_delete (int bb_index)
+{
+  basic_block bb = BASIC_BLOCK (bb_index);
+  int i;
+
+  if (!df)
+    return;
+  
+  for (i = 0; i < df->num_problems_defined; i++)
+    {
+      struct dataflow *dflow = df->problems_in_order[i];
+      if (dflow->problem->free_bb_fun)
+	{
+	  void *bb_info = df_get_bb_info (dflow, bb_index);
+	  if (bb_info)
+	    {
+	      dflow->problem->free_bb_fun (bb, bb_info); 
+	      df_set_bb_info (dflow, bb_index, NULL);
+	    }
+	}
+    }
+  df_clear_bb_dirty (bb);
+  df_mark_solutions_dirty ();
+}
+
+
+/* Verify that there is a place for everything and everything is in
+   its place.  This is too expensive to run after every pass in the
+   mainline.  However this is an excellent debugging tool if the
+   dataflow information is not being updated properly.  You can just
+   sprinkle calls in until you find the place that is changing an
+   underlying structure without calling the proper updating
+   routine.  */
+
+void
+df_verify (void)
+{
+  df_scan_verify ();
+#ifdef ENABLE_DF_CHECKING
+  df_lr_verify_transfer_functions ();
+  if (df_live)
+    df_live_verify_transfer_functions ();
+#endif
+}
+
+#ifdef DF_DEBUG_CFG
+
+/* Compute an array of ints that describes the cfg.  This can be used
+   to discover places where the cfg is modified by the appropriate
+   calls have not been made to the keep df informed.  The internals of
+   this are unexciting, the key is that two instances of this can be
+   compared to see if any changes have been made to the cfg.  */
+
+static int *
+df_compute_cfg_image (void)
+{
+  basic_block bb;
+  int size = 2 + (2 * n_basic_blocks);
+  int i;
+  int * map;
+
+  FOR_ALL_BB (bb)
+    {
+      size += EDGE_COUNT (bb->succs);
+    }
+
+  map = XNEWVEC (int, size);
+  map[0] = size;
+  i = 1;
+  FOR_ALL_BB (bb)
+    {
+      edge_iterator ei;
+      edge e;
+
+      map[i++] = bb->index;
+      FOR_EACH_EDGE (e, ei, bb->succs)
+	map[i++] = e->dest->index;
+      map[i++] = -1;
+    }
+  map[i] = -1;
+  return map;
+}
+
+static int *saved_cfg = NULL;
+
+
+/* This function compares the saved version of the cfg with the
+   current cfg and aborts if the two are identical.  The function
+   silently returns if the cfg has been marked as dirty or the two are
+   the same.  */
+
+void
+df_check_cfg_clean (void)
+{
+  int *new_map;
+
+  if (!df)
+    return;
+
+  if (df_lr->solutions_dirty)
+    return;
+
+  if (saved_cfg == NULL) 
+    return;
+
+  new_map = df_compute_cfg_image ();
+  gcc_assert (memcmp (saved_cfg, new_map, saved_cfg[0] * sizeof (int)) == 0);
+  free (new_map);
+}
+
+
+/* This function builds a cfg fingerprint and squirrels it away in
+   saved_cfg.  */
+
+static void
+df_set_clean_cfg (void)
+{
+  if (saved_cfg)
+    free (saved_cfg);
+  saved_cfg = df_compute_cfg_image ();
+}
+
+#endif /* DF_DEBUG_CFG  */
+/*----------------------------------------------------------------------------
+   PUBLIC INTERFACES TO QUERY INFORMATION.
+----------------------------------------------------------------------------*/
+
+
+/* Return first def of REGNO within BB.  */
+
+df_ref 
+df_bb_regno_first_def_find (basic_block bb, unsigned int regno)
+{
+  rtx insn;
+  df_ref *def_rec;
+  unsigned int uid;
+
+  FOR_BB_INSNS (bb, insn)
+    {
+      if (!INSN_P (insn))
+	continue;
+
+      uid = INSN_UID (insn);
+      for (def_rec = DF_INSN_UID_DEFS (uid); *def_rec; def_rec++)
+	{
+	  df_ref def = *def_rec;
+	  if (DF_REF_REGNO (def) == regno)
+	    return def;
+	}
+    }
+  return NULL;
+}
+
+
+/* Return last def of REGNO within BB.  */
+
+df_ref 
+df_bb_regno_last_def_find (basic_block bb, unsigned int regno)
+{
+  rtx insn;
+  df_ref *def_rec;
+  unsigned int uid;
+
+  FOR_BB_INSNS_REVERSE (bb, insn)
+    {
+      if (!INSN_P (insn))
+	continue;
+
+      uid = INSN_UID (insn);
+      for (def_rec = DF_INSN_UID_DEFS (uid); *def_rec; def_rec++)
+	{
+	  df_ref def = *def_rec;
+	  if (DF_REF_REGNO (def) == regno)
+	    return def;
+	}
+    }
+
+  return NULL;
+}
+
+/* Finds the reference corresponding to the definition of REG in INSN.
+   DF is the dataflow object.  */
+
+df_ref 
+df_find_def (rtx insn, rtx reg)
+{
+  unsigned int uid;
+  df_ref *def_rec;
+
+  if (GET_CODE (reg) == SUBREG)
+    reg = SUBREG_REG (reg);
+  gcc_assert (REG_P (reg));
+
+  uid = INSN_UID (insn);
+  for (def_rec = DF_INSN_UID_DEFS (uid); *def_rec; def_rec++)
+    {
+      df_ref def = *def_rec;
+      if (rtx_equal_p (DF_REF_REAL_REG (def), reg))
+	return def;
+    }
+
+  return NULL;
+}
+
+
+/* Return true if REG is defined in INSN, zero otherwise.  */ 
+
+bool
+df_reg_defined (rtx insn, rtx reg)
+{
+  return df_find_def (insn, reg) != NULL;
+}
+  
+
+/* Finds the reference corresponding to the use of REG in INSN.
+   DF is the dataflow object.  */
+  
+df_ref 
+df_find_use (rtx insn, rtx reg)
+{
+  unsigned int uid;
+  df_ref *use_rec;
+
+  if (GET_CODE (reg) == SUBREG)
+    reg = SUBREG_REG (reg);
+  gcc_assert (REG_P (reg));
+
+  uid = INSN_UID (insn);
+  for (use_rec = DF_INSN_UID_USES (uid); *use_rec; use_rec++)
+    {
+      df_ref use = *use_rec;
+      if (rtx_equal_p (DF_REF_REAL_REG (use), reg))
+	return use;
+    } 
+  if (df->changeable_flags & DF_EQ_NOTES)
+    for (use_rec = DF_INSN_UID_EQ_USES (uid); *use_rec; use_rec++)
+      {
+	df_ref use = *use_rec;
+	if (rtx_equal_p (DF_REF_REAL_REG (use), reg))
+	  return use; 
+      }
+  return NULL;
+}
+
+
+/* Return true if REG is referenced in INSN, zero otherwise.  */ 
+
+bool
+df_reg_used (rtx insn, rtx reg)
+{
+  return df_find_use (insn, reg) != NULL;
+}
+  
+
+/*----------------------------------------------------------------------------
+   Debugging and printing functions.
+----------------------------------------------------------------------------*/
+
+
+/* Write information about registers and basic blocks into FILE.
+   This is part of making a debugging dump.  */
+
+void
+df_print_regset (FILE *file, bitmap r)
+{
+  unsigned int i;
+  bitmap_iterator bi;
+
+  if (r == NULL)
+    fputs (" (nil)", file);
+  else
+    {
+      EXECUTE_IF_SET_IN_BITMAP (r, 0, i, bi)
+	{
+	  fprintf (file, " %d", i);
+	  if (i < FIRST_PSEUDO_REGISTER)
+	    fprintf (file, " [%s]", reg_names[i]);
+	}
+    }
+  fprintf (file, "\n");
+}
+
+
+/* Write information about registers and basic blocks into FILE.  The
+   bitmap is in the form used by df_byte_lr.  This is part of making a
+   debugging dump.  */
+
+void
+df_print_byte_regset (FILE *file, bitmap r)
+{
+  unsigned int max_reg = max_reg_num ();
+  bitmap_iterator bi;
+
+  if (r == NULL)
+    fputs (" (nil)", file);
+  else
+    {
+      unsigned int i;
+      for (i = 0; i < max_reg; i++)
+	{
+	  unsigned int first = df_byte_lr_get_regno_start (i);
+	  unsigned int len = df_byte_lr_get_regno_len (i);
+
+	  if (len > 1)
+	    {
+	      bool found = false;
+	      unsigned int j;
+
+	      EXECUTE_IF_SET_IN_BITMAP (r, first, j, bi)
+		{
+		  found = j < first + len;
+		  break;
+		}
+	      if (found)
+		{
+		  const char * sep = "";
+		  fprintf (file, " %d", i);
+		  if (i < FIRST_PSEUDO_REGISTER)
+		    fprintf (file, " [%s]", reg_names[i]);
+		  fprintf (file, "(");
+		  EXECUTE_IF_SET_IN_BITMAP (r, first, j, bi)
+		    {
+		      if (j > first + len - 1)
+			break;
+		      fprintf (file, "%s%d", sep, j-first);
+		      sep = ", ";
+		    }
+		  fprintf (file, ")");
+		}
+	    }
+	  else
+	    {
+	      if (bitmap_bit_p (r, first))
+		{
+		  fprintf (file, " %d", i);
+		  if (i < FIRST_PSEUDO_REGISTER)
+		    fprintf (file, " [%s]", reg_names[i]);
+		}
+	    }
+
+	}
+    }
+  fprintf (file, "\n");
+}
+
+
+/* Dump dataflow info.  */
+
+void
+df_dump (FILE *file)
+{
+  basic_block bb;
+  df_dump_start (file);
+
+  FOR_ALL_BB (bb)
+    {
+      df_print_bb_index (bb, file);
+      df_dump_top (bb, file);
+      df_dump_bottom (bb, file);
+    }
+
+  fprintf (file, "\n");
+}
+
+
+/* Dump dataflow info for df->blocks_to_analyze.  */
+
+void
+df_dump_region (FILE *file)
+{
+  if (df->blocks_to_analyze)
+    {
+      bitmap_iterator bi;
+      unsigned int bb_index;
+
+      fprintf (file, "\n\nstarting region dump\n");
+      df_dump_start (file);
+      
+      EXECUTE_IF_SET_IN_BITMAP (df->blocks_to_analyze, 0, bb_index, bi) 
+	{
+	  basic_block bb = BASIC_BLOCK (bb_index);
+	  
+	  df_print_bb_index (bb, file);
+	  df_dump_top (bb, file);
+	  df_dump_bottom (bb, file);
+	}
+      fprintf (file, "\n");
+    }
+  else 
+    df_dump (file);
+}
+
+
+/* Dump the introductory information for each problem defined.  */
+
+void
+df_dump_start (FILE *file)
+{
+  int i;
+
+  if (!df || !file)
+    return;
+
+  fprintf (file, "\n\n%s\n", current_function_name ());
+  fprintf (file, "\nDataflow summary:\n");
+  if (df->blocks_to_analyze)
+    fprintf (file, "def_info->table_size = %d, use_info->table_size = %d\n",
+	     DF_DEFS_TABLE_SIZE (), DF_USES_TABLE_SIZE ());
+
+  for (i = 0; i < df->num_problems_defined; i++)
+    {
+      struct dataflow *dflow = df->problems_in_order[i];
+      if (dflow->computed)
+	{
+	  df_dump_problem_function fun = dflow->problem->dump_start_fun;
+	  if (fun)
+	    fun(file); 
+	}
+    }
+}
+
+
+/* Dump the top of the block information for BB.  */ 
+
+void
+df_dump_top (basic_block bb, FILE *file)
+{
+  int i;
+
+  if (!df || !file)
+    return;
+
+  for (i = 0; i < df->num_problems_defined; i++)
+    {
+      struct dataflow *dflow = df->problems_in_order[i];
+      if (dflow->computed)
+	{
+	  df_dump_bb_problem_function bbfun = dflow->problem->dump_top_fun;
+	  if (bbfun)
+	    bbfun (bb, file); 
+	}
+    }
+}
+
+
+/* Dump the bottom of the block information for BB.  */ 
+
+void
+df_dump_bottom (basic_block bb, FILE *file)
+{
+  int i;
+
+  if (!df || !file)
+    return;
+
+  for (i = 0; i < df->num_problems_defined; i++)
+    {
+      struct dataflow *dflow = df->problems_in_order[i];
+      if (dflow->computed)
+	{
+	  df_dump_bb_problem_function bbfun = dflow->problem->dump_bottom_fun;
+	  if (bbfun)
+	    bbfun (bb, file); 
+	}
+    }
+}
+
+
+void
+df_refs_chain_dump (df_ref *ref_rec, bool follow_chain, FILE *file)
+{
+  fprintf (file, "{ ");
+  while (*ref_rec)
+    {
+      df_ref ref = *ref_rec;
+      fprintf (file, "%c%d(%d)",
+	       DF_REF_REG_DEF_P (ref) ? 'd' : (DF_REF_FLAGS (ref) & DF_REF_IN_NOTE) ? 'e' : 'u',
+	       DF_REF_ID (ref),
+	       DF_REF_REGNO (ref));
+      if (follow_chain)
+	df_chain_dump (DF_REF_CHAIN (ref), file);
+      ref_rec++;
+    }
+  fprintf (file, "}");
+}
+
+
+/* Dump either a ref-def or reg-use chain.  */
+
+void
+df_regs_chain_dump (df_ref ref,  FILE *file)
+{
+  fprintf (file, "{ ");
+  while (ref)
+    {
+      fprintf (file, "%c%d(%d) ",
+	       DF_REF_REG_DEF_P (ref) ? 'd' : 'u',
+	       DF_REF_ID (ref),
+	       DF_REF_REGNO (ref));
+      ref = DF_REF_NEXT_REG (ref);
+    }
+  fprintf (file, "}");
+}
+
+
+static void
+df_mws_dump (struct df_mw_hardreg **mws, FILE *file)
+{
+  while (*mws)
+    {
+      fprintf (file, "mw %c r[%d..%d]\n", 
+	       (DF_MWS_REG_DEF_P (*mws)) ? 'd' : 'u',
+	       (*mws)->start_regno, (*mws)->end_regno);
+      mws++;
+    }
+}
+
+
+static void 
+df_insn_uid_debug (unsigned int uid, 
+		   bool follow_chain, FILE *file)
+{
+  fprintf (file, "insn %d luid %d",
+	   uid, DF_INSN_UID_LUID (uid));
+
+  if (DF_INSN_UID_DEFS (uid))
+    {
+      fprintf (file, " defs ");
+      df_refs_chain_dump (DF_INSN_UID_DEFS (uid), follow_chain, file);
+    }
+
+  if (DF_INSN_UID_USES (uid))
+    {
+      fprintf (file, " uses ");
+      df_refs_chain_dump (DF_INSN_UID_USES (uid), follow_chain, file);
+    }
+
+  if (DF_INSN_UID_EQ_USES (uid))
+    {
+      fprintf (file, " eq uses ");
+      df_refs_chain_dump (DF_INSN_UID_EQ_USES (uid), follow_chain, file);
+    }
+
+  if (DF_INSN_UID_MWS (uid))
+    {
+      fprintf (file, " mws ");
+      df_mws_dump (DF_INSN_UID_MWS (uid), file);
+    }
+  fprintf (file, "\n");
+}
+
+
+void
+df_insn_debug (rtx insn, bool follow_chain, FILE *file)
+{
+  df_insn_uid_debug (INSN_UID (insn), follow_chain, file);
+}
+
+void
+df_insn_debug_regno (rtx insn, FILE *file)
+{
+  struct df_insn_info *insn_info = DF_INSN_INFO_GET (insn);
+
+  fprintf (file, "insn %d bb %d luid %d defs ",
+	   INSN_UID (insn), BLOCK_FOR_INSN (insn)->index,
+	   DF_INSN_INFO_LUID (insn_info));
+  df_refs_chain_dump (DF_INSN_INFO_DEFS (insn_info), false, file);
+    
+  fprintf (file, " uses ");
+  df_refs_chain_dump (DF_INSN_INFO_USES (insn_info), false, file);
+
+  fprintf (file, " eq_uses ");
+  df_refs_chain_dump (DF_INSN_INFO_EQ_USES (insn_info), false, file);
+  fprintf (file, "\n");
+}
+
+void
+df_regno_debug (unsigned int regno, FILE *file)
+{
+  fprintf (file, "reg %d defs ", regno);
+  df_regs_chain_dump (DF_REG_DEF_CHAIN (regno), file);
+  fprintf (file, " uses ");
+  df_regs_chain_dump (DF_REG_USE_CHAIN (regno), file);
+  fprintf (file, " eq_uses ");
+  df_regs_chain_dump (DF_REG_EQ_USE_CHAIN (regno), file);
+  fprintf (file, "\n");
+}
+
+
+void
+df_ref_debug (df_ref ref, FILE *file)
+{
+  fprintf (file, "%c%d ",
+	   DF_REF_REG_DEF_P (ref) ? 'd' : 'u',
+	   DF_REF_ID (ref));
+  fprintf (file, "reg %d bb %d insn %d flag 0x%x type 0x%x ",
+	   DF_REF_REGNO (ref),
+	   DF_REF_BBNO (ref),
+	   DF_REF_IS_ARTIFICIAL (ref) ? -1 : DF_REF_INSN_UID (ref),
+	   DF_REF_FLAGS (ref),
+	   DF_REF_TYPE (ref));
+  if (DF_REF_LOC (ref))
+    fprintf (file, "loc %p(%p) chain ", (void *)DF_REF_LOC (ref), (void *)*DF_REF_LOC (ref));
+  else
+    fprintf (file, "chain ");
+  df_chain_dump (DF_REF_CHAIN (ref), file);
+  fprintf (file, "\n");
+}
+
+/* Functions for debugging from GDB.  */
+
+void
+debug_df_insn (rtx insn)
+{
+  df_insn_debug (insn, true, stderr);
+  debug_rtx (insn);
+}
+
+
+void
+debug_df_reg (rtx reg)
+{
+  df_regno_debug (REGNO (reg), stderr);
+}
+
+
+void
+debug_df_regno (unsigned int regno)
+{
+  df_regno_debug (regno, stderr);
+}
+
+
+void
+debug_df_ref (df_ref ref)
+{
+  df_ref_debug (ref, stderr);
+}
+
+
+void
+debug_df_defno (unsigned int defno)
+{
+  df_ref_debug (DF_DEFS_GET (defno), stderr);
+}
+
+
+void
+debug_df_useno (unsigned int defno)
+{
+  df_ref_debug (DF_USES_GET (defno), stderr);
+}
+
+
+void
+debug_df_chain (struct df_link *link)
+{
+  df_chain_dump (link, stderr);
+  fputc ('\n', stderr);
+}