1/* CPU mode switching
2   Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2007, 2008,
3   2009 Free Software Foundation, Inc.
4
5This file is part of GCC.
6
7GCC is free software; you can redistribute it and/or modify it under
8the terms of the GNU General Public License as published by the Free
9Software Foundation; either version 3, or (at your option) any later
10version.
11
12GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13WARRANTY; without even the implied warranty of MERCHANTABILITY or
14FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
15for more details.
16
17You should have received a copy of the GNU General Public License
18along with GCC; see the file COPYING3.  If not see
19<http://www.gnu.org/licenses/>.  */
20
21#include "config.h"
22#include "system.h"
23#include "coretypes.h"
24#include "tm.h"
25#include "rtl.h"
26#include "regs.h"
27#include "hard-reg-set.h"
28#include "flags.h"
29#include "real.h"
30#include "insn-config.h"
31#include "recog.h"
32#include "basic-block.h"
33#include "output.h"
34#include "tm_p.h"
35#include "function.h"
36#include "tree-pass.h"
37#include "timevar.h"
38#include "df.h"
39
40/* We want target macros for the mode switching code to be able to refer
41   to instruction attribute values.  */
42#include "insn-attr.h"
43
44#ifdef OPTIMIZE_MODE_SWITCHING
45
46/* The algorithm for setting the modes consists of scanning the insn list
47   and finding all the insns which require a specific mode.  Each insn gets
48   a unique struct seginfo element.  These structures are inserted into a list
49   for each basic block.  For each entity, there is an array of bb_info over
50   the flow graph basic blocks (local var 'bb_info'), and contains a list
51   of all insns within that basic block, in the order they are encountered.
52
53   For each entity, any basic block WITHOUT any insns requiring a specific
54   mode are given a single entry, without a mode.  (Each basic block
55   in the flow graph must have at least one entry in the segment table.)
56
57   The LCM algorithm is then run over the flow graph to determine where to
58   place the sets to the highest-priority value in respect of first the first
59   insn in any one block.  Any adjustments required to the transparency
60   vectors are made, then the next iteration starts for the next-lower
61   priority mode, till for each entity all modes are exhausted.
62
63   More details are located in the code for optimize_mode_switching().  */
64
65/* This structure contains the information for each insn which requires
66   either single or double mode to be set.
67   MODE is the mode this insn must be executed in.
68   INSN_PTR is the insn to be executed (may be the note that marks the
69   beginning of a basic block).
70   BBNUM is the flow graph basic block this insn occurs in.
71   NEXT is the next insn in the same basic block.  */
72struct seginfo
73{
74  int mode;
75  rtx insn_ptr;
76  int bbnum;
77  struct seginfo *next;
78  HARD_REG_SET regs_live;
79};
80
81struct bb_info
82{
83  struct seginfo *seginfo;
84  int computing;
85};
86
87/* These bitmaps are used for the LCM algorithm.  */
88
89static sbitmap *antic;
90static sbitmap *transp;
91static sbitmap *comp;
92
93static struct seginfo * new_seginfo (int, rtx, int, HARD_REG_SET);
94static void add_seginfo (struct bb_info *, struct seginfo *);
95static void reg_dies (rtx, HARD_REG_SET *);
96static void reg_becomes_live (rtx, const_rtx, void *);
97static void make_preds_opaque (basic_block, int);
98
99
100/* This function will allocate a new BBINFO structure, initialized
101   with the MODE, INSN, and basic block BB parameters.  */
102
103static struct seginfo *
104new_seginfo (int mode, rtx insn, int bb, HARD_REG_SET regs_live)
105{
106  struct seginfo *ptr;
107  ptr = XNEW (struct seginfo);
108  ptr->mode = mode;
109  ptr->insn_ptr = insn;
110  ptr->bbnum = bb;
111  ptr->next = NULL;
112  COPY_HARD_REG_SET (ptr->regs_live, regs_live);
113  return ptr;
114}
115
116/* Add a seginfo element to the end of a list.
117   HEAD is a pointer to the list beginning.
118   INFO is the structure to be linked in.  */
119
120static void
121add_seginfo (struct bb_info *head, struct seginfo *info)
122{
123  struct seginfo *ptr;
124
125  if (head->seginfo == NULL)
126    head->seginfo = info;
127  else
128    {
129      ptr = head->seginfo;
130      while (ptr->next != NULL)
131	ptr = ptr->next;
132      ptr->next = info;
133    }
134}
135
136/* Make all predecessors of basic block B opaque, recursively, till we hit
137   some that are already non-transparent, or an edge where aux is set; that
138   denotes that a mode set is to be done on that edge.
139   J is the bit number in the bitmaps that corresponds to the entity that
140   we are currently handling mode-switching for.  */
141
142static void
143make_preds_opaque (basic_block b, int j)
144{
145  edge e;
146  edge_iterator ei;
147
148  FOR_EACH_EDGE (e, ei, b->preds)
149    {
150      basic_block pb = e->src;
151
152      if (e->aux || ! TEST_BIT (transp[pb->index], j))
153	continue;
154
155      RESET_BIT (transp[pb->index], j);
156      make_preds_opaque (pb, j);
157    }
158}
159
160/* Record in LIVE that register REG died.  */
161
162static void
163reg_dies (rtx reg, HARD_REG_SET *live)
164{
165  int regno;
166
167  if (!REG_P (reg))
168    return;
169
170  regno = REGNO (reg);
171  if (regno < FIRST_PSEUDO_REGISTER)
172    remove_from_hard_reg_set (live, GET_MODE (reg), regno);
173}
174
175/* Record in LIVE that register REG became live.
176   This is called via note_stores.  */
177
178static void
179reg_becomes_live (rtx reg, const_rtx setter ATTRIBUTE_UNUSED, void *live)
180{
181  int regno;
182
183  if (GET_CODE (reg) == SUBREG)
184    reg = SUBREG_REG (reg);
185
186  if (!REG_P (reg))
187    return;
188
189  regno = REGNO (reg);
190  if (regno < FIRST_PSEUDO_REGISTER)
191    add_to_hard_reg_set ((HARD_REG_SET *) live, GET_MODE (reg), regno);
192}
193
194/* Make sure if MODE_ENTRY is defined the MODE_EXIT is defined
195   and vice versa.  */
196#if defined (MODE_ENTRY) != defined (MODE_EXIT)
197 #error "Both MODE_ENTRY and MODE_EXIT must be defined"
198#endif
199
200#if defined (MODE_ENTRY) && defined (MODE_EXIT)
201/* Split the fallthrough edge to the exit block, so that we can note
202   that there NORMAL_MODE is required.  Return the new block if it's
203   inserted before the exit block.  Otherwise return null.  */
204
205static basic_block
206create_pre_exit (int n_entities, int *entity_map, const int *num_modes)
207{
208  edge eg;
209  edge_iterator ei;
210  basic_block pre_exit;
211
212  /* The only non-call predecessor at this stage is a block with a
213     fallthrough edge; there can be at most one, but there could be
214     none at all, e.g. when exit is called.  */
215  pre_exit = 0;
216  FOR_EACH_EDGE (eg, ei, EXIT_BLOCK_PTR->preds)
217    if (eg->flags & EDGE_FALLTHRU)
218      {
219	basic_block src_bb = eg->src;
220	rtx last_insn, ret_reg;
221
222	gcc_assert (!pre_exit);
223	/* If this function returns a value at the end, we have to
224	   insert the final mode switch before the return value copy
225	   to its hard register.  */
226	if (EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 1
227	    && NONJUMP_INSN_P ((last_insn = BB_END (src_bb)))
228	    && GET_CODE (PATTERN (last_insn)) == USE
229	    && GET_CODE ((ret_reg = XEXP (PATTERN (last_insn), 0))) == REG)
230	  {
231	    int ret_start = REGNO (ret_reg);
232	    int nregs = hard_regno_nregs[ret_start][GET_MODE (ret_reg)];
233	    int ret_end = ret_start + nregs;
234	    int short_block = 0;
235	    int maybe_builtin_apply = 0;
236	    int forced_late_switch = 0;
237	    rtx before_return_copy;
238
239	    do
240	      {
241		rtx return_copy = PREV_INSN (last_insn);
242		rtx return_copy_pat, copy_reg;
243		int copy_start, copy_num;
244		int j;
245
246		if (INSN_P (return_copy))
247		  {
248		    /* When using SJLJ exceptions, the call to the
249		       unregister function is inserted between the
250		       clobber of the return value and the copy.
251		       We do not want to split the block before this
252		       or any other call; if we have not found the
253		       copy yet, the copy must have been deleted.  */
254		    if (CALL_P (return_copy))
255		      {
256			short_block = 1;
257			break;
258		      }
259		    return_copy_pat = PATTERN (return_copy);
260		    switch (GET_CODE (return_copy_pat))
261		      {
262		      case USE:
263			/* Skip __builtin_apply pattern.  */
264			if (GET_CODE (XEXP (return_copy_pat, 0)) == REG
265			    && (FUNCTION_VALUE_REGNO_P
266				(REGNO (XEXP (return_copy_pat, 0)))))
267			  {
268			    maybe_builtin_apply = 1;
269			    last_insn = return_copy;
270			    continue;
271			  }
272			break;
273
274		      case ASM_OPERANDS:
275			/* Skip barrier insns.  */
276			if (!MEM_VOLATILE_P (return_copy_pat))
277			  break;
278
279			/* Fall through.  */
280
281		      case ASM_INPUT:
282		      case UNSPEC_VOLATILE:
283			last_insn = return_copy;
284			continue;
285
286		      default:
287			break;
288		      }
289
290		    /* If the return register is not (in its entirety)
291		       likely spilled, the return copy might be
292		       partially or completely optimized away.  */
293		    return_copy_pat = single_set (return_copy);
294		    if (!return_copy_pat)
295		      {
296			return_copy_pat = PATTERN (return_copy);
297			if (GET_CODE (return_copy_pat) != CLOBBER)
298			  break;
299			else if (!optimize)
300			  {
301			    /* This might be (clobber (reg [<result>]))
302			       when not optimizing.  Then check if
303			       the previous insn is the clobber for
304			       the return register.  */
305			    copy_reg = SET_DEST (return_copy_pat);
306			    if (GET_CODE (copy_reg) == REG
307				&& !HARD_REGISTER_NUM_P (REGNO (copy_reg)))
308			      {
309				if (INSN_P (PREV_INSN (return_copy)))
310				  {
311				    return_copy = PREV_INSN (return_copy);
312				    return_copy_pat = PATTERN (return_copy);
313				    if (GET_CODE (return_copy_pat) != CLOBBER)
314				      break;
315				  }
316			      }
317			  }
318		      }
319		    copy_reg = SET_DEST (return_copy_pat);
320		    if (GET_CODE (copy_reg) == REG)
321		      copy_start = REGNO (copy_reg);
322		    else if (GET_CODE (copy_reg) == SUBREG
323			     && GET_CODE (SUBREG_REG (copy_reg)) == REG)
324		      copy_start = REGNO (SUBREG_REG (copy_reg));
325		    else
326		      break;
327		    if (copy_start >= FIRST_PSEUDO_REGISTER)
328		      break;
329		    copy_num
330		      = hard_regno_nregs[copy_start][GET_MODE (copy_reg)];
331
332		    /* If the return register is not likely spilled, - as is
333		       the case for floating point on SH4 - then it might
334		       be set by an arithmetic operation that needs a
335		       different mode than the exit block.  */
336		    for (j = n_entities - 1; j >= 0; j--)
337		      {
338			int e = entity_map[j];
339			int mode = MODE_NEEDED (e, return_copy);
340
341			if (mode != num_modes[e] && mode != MODE_EXIT (e))
342			  break;
343		      }
344		    if (j >= 0)
345		      {
346			/* For the SH4, floating point loads depend on fpscr,
347			   thus we might need to put the final mode switch
348			   after the return value copy.  That is still OK,
349			   because a floating point return value does not
350			   conflict with address reloads.  */
351			if (copy_start >= ret_start
352			    && copy_start + copy_num <= ret_end
353			    && OBJECT_P (SET_SRC (return_copy_pat)))
354			  forced_late_switch = 1;
355			break;
356		      }
357
358		    if (copy_start >= ret_start
359			&& copy_start + copy_num <= ret_end)
360		      nregs -= copy_num;
361		    else if (!maybe_builtin_apply
362			     || !FUNCTION_VALUE_REGNO_P (copy_start))
363		      break;
364		    last_insn = return_copy;
365		  }
366		/* ??? Exception handling can lead to the return value
367		   copy being already separated from the return value use,
368		   as in  unwind-dw2.c .
369		   Similarly, conditionally returning without a value,
370		   and conditionally using builtin_return can lead to an
371		   isolated use.  */
372		if (return_copy == BB_HEAD (src_bb))
373		  {
374		    short_block = 1;
375		    break;
376		  }
377		last_insn = return_copy;
378	      }
379	    while (nregs);
380
381	    /* If we didn't see a full return value copy, verify that there
382	       is a plausible reason for this.  If some, but not all of the
383	       return register is likely spilled, we can expect that there
384	       is a copy for the likely spilled part.  */
385	    gcc_assert (!nregs
386			|| forced_late_switch
387			|| short_block
388			|| !(CLASS_LIKELY_SPILLED_P
389			     (REGNO_REG_CLASS (ret_start)))
390			|| (nregs
391			    != hard_regno_nregs[ret_start][GET_MODE (ret_reg)])
392			/* For multi-hard-register floating point
393		   	   values, sometimes the likely-spilled part
394		   	   is ordinarily copied first, then the other
395		   	   part is set with an arithmetic operation.
396		   	   This doesn't actually cause reload
397		   	   failures, so let it pass.  */
398			|| (GET_MODE_CLASS (GET_MODE (ret_reg)) != MODE_INT
399			    && nregs != 1));
400
401	    if (INSN_P (last_insn))
402	      {
403		before_return_copy
404		  = emit_note_before (NOTE_INSN_DELETED, last_insn);
405		/* Instructions preceding LAST_INSN in the same block might
406		   require a different mode than MODE_EXIT, so if we might
407		   have such instructions, keep them in a separate block
408		   from pre_exit.  */
409		if (last_insn != BB_HEAD (src_bb))
410		  src_bb = split_block (src_bb,
411					PREV_INSN (before_return_copy))->dest;
412	      }
413	    else
414	      before_return_copy = last_insn;
415	    pre_exit = split_block (src_bb, before_return_copy)->src;
416	  }
417	else
418	  {
419	    pre_exit = split_edge (eg);
420	  }
421      }
422
423  return pre_exit;
424}
425#endif
426
427/* Find all insns that need a particular mode setting, and insert the
428   necessary mode switches.  Return true if we did work.  */
429
430static int
431optimize_mode_switching (void)
432{
433  rtx insn;
434  int e;
435  basic_block bb;
436  int need_commit = 0;
437  sbitmap *kill;
438  struct edge_list *edge_list;
439  static const int num_modes[] = NUM_MODES_FOR_MODE_SWITCHING;
440#define N_ENTITIES ARRAY_SIZE (num_modes)
441  int entity_map[N_ENTITIES];
442  struct bb_info *bb_info[N_ENTITIES];
443  int i, j;
444  int n_entities;
445  int max_num_modes = 0;
446  bool emited = false;
447  basic_block post_entry ATTRIBUTE_UNUSED, pre_exit ATTRIBUTE_UNUSED;
448
449  for (e = N_ENTITIES - 1, n_entities = 0; e >= 0; e--)
450    if (OPTIMIZE_MODE_SWITCHING (e))
451      {
452	int entry_exit_extra = 0;
453
454	/* Create the list of segments within each basic block.
455	   If NORMAL_MODE is defined, allow for two extra
456	   blocks split from the entry and exit block.  */
457#if defined (MODE_ENTRY) && defined (MODE_EXIT)
458	entry_exit_extra = 3;
459#endif
460	bb_info[n_entities]
461	  = XCNEWVEC (struct bb_info, last_basic_block + entry_exit_extra);
462	entity_map[n_entities++] = e;
463	if (num_modes[e] > max_num_modes)
464	  max_num_modes = num_modes[e];
465      }
466
467  if (! n_entities)
468    return 0;
469
470#if defined (MODE_ENTRY) && defined (MODE_EXIT)
471  /* Split the edge from the entry block, so that we can note that
472     there NORMAL_MODE is supplied.  */
473  post_entry = split_edge (single_succ_edge (ENTRY_BLOCK_PTR));
474  pre_exit = create_pre_exit (n_entities, entity_map, num_modes);
475#endif
476
477  df_analyze ();
478
479  /* Create the bitmap vectors.  */
480
481  antic = sbitmap_vector_alloc (last_basic_block, n_entities);
482  transp = sbitmap_vector_alloc (last_basic_block, n_entities);
483  comp = sbitmap_vector_alloc (last_basic_block, n_entities);
484
485  sbitmap_vector_ones (transp, last_basic_block);
486
487  for (j = n_entities - 1; j >= 0; j--)
488    {
489      int e = entity_map[j];
490      int no_mode = num_modes[e];
491      struct bb_info *info = bb_info[j];
492
493      /* Determine what the first use (if any) need for a mode of entity E is.
494	 This will be the mode that is anticipatable for this block.
495	 Also compute the initial transparency settings.  */
496      FOR_EACH_BB (bb)
497	{
498	  struct seginfo *ptr;
499	  int last_mode = no_mode;
500	  HARD_REG_SET live_now;
501
502	  REG_SET_TO_HARD_REG_SET (live_now, df_get_live_in (bb));
503
504	  /* Pretend the mode is clobbered across abnormal edges.  */
505	  {
506	    edge_iterator ei;
507	    edge e;
508	    FOR_EACH_EDGE (e, ei, bb->preds)
509	      if (e->flags & EDGE_COMPLEX)
510		break;
511	    if (e)
512	      {
513		ptr = new_seginfo (no_mode, BB_HEAD (bb), bb->index, live_now);
514		add_seginfo (info + bb->index, ptr);
515		RESET_BIT (transp[bb->index], j);
516	      }
517	  }
518
519	  for (insn = BB_HEAD (bb);
520	       insn != NULL && insn != NEXT_INSN (BB_END (bb));
521	       insn = NEXT_INSN (insn))
522	    {
523	      if (INSN_P (insn))
524		{
525		  int mode = MODE_NEEDED (e, insn);
526		  rtx link;
527
528		  if (mode != no_mode && mode != last_mode)
529		    {
530		      last_mode = mode;
531		      ptr = new_seginfo (mode, insn, bb->index, live_now);
532		      add_seginfo (info + bb->index, ptr);
533		      RESET_BIT (transp[bb->index], j);
534		    }
535#ifdef MODE_AFTER
536		  last_mode = MODE_AFTER (last_mode, insn);
537#endif
538		  /* Update LIVE_NOW.  */
539		  for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
540		    if (REG_NOTE_KIND (link) == REG_DEAD)
541		      reg_dies (XEXP (link, 0), &live_now);
542
543		  note_stores (PATTERN (insn), reg_becomes_live, &live_now);
544		  for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
545		    if (REG_NOTE_KIND (link) == REG_UNUSED)
546		      reg_dies (XEXP (link, 0), &live_now);
547		}
548	    }
549
550	  info[bb->index].computing = last_mode;
551	  /* Check for blocks without ANY mode requirements.  */
552	  if (last_mode == no_mode)
553	    {
554	      ptr = new_seginfo (no_mode, BB_END (bb), bb->index, live_now);
555	      add_seginfo (info + bb->index, ptr);
556	    }
557	}
558#if defined (MODE_ENTRY) && defined (MODE_EXIT)
559      {
560	int mode = MODE_ENTRY (e);
561
562	if (mode != no_mode)
563	  {
564	    bb = post_entry;
565
566	    /* By always making this nontransparent, we save
567	       an extra check in make_preds_opaque.  We also
568	       need this to avoid confusing pre_edge_lcm when
569	       antic is cleared but transp and comp are set.  */
570	    RESET_BIT (transp[bb->index], j);
571
572	    /* Insert a fake computing definition of MODE into entry
573	       blocks which compute no mode. This represents the mode on
574	       entry.  */
575	    info[bb->index].computing = mode;
576
577	    if (pre_exit)
578	      info[pre_exit->index].seginfo->mode = MODE_EXIT (e);
579	  }
580      }
581#endif /* NORMAL_MODE */
582    }
583
584  kill = sbitmap_vector_alloc (last_basic_block, n_entities);
585  for (i = 0; i < max_num_modes; i++)
586    {
587      int current_mode[N_ENTITIES];
588      sbitmap *del;
589      sbitmap *insert;
590
591      /* Set the anticipatable and computing arrays.  */
592      sbitmap_vector_zero (antic, last_basic_block);
593      sbitmap_vector_zero (comp, last_basic_block);
594      for (j = n_entities - 1; j >= 0; j--)
595	{
596	  int m = current_mode[j] = MODE_PRIORITY_TO_MODE (entity_map[j], i);
597	  struct bb_info *info = bb_info[j];
598
599	  FOR_EACH_BB (bb)
600	    {
601	      if (info[bb->index].seginfo->mode == m)
602		SET_BIT (antic[bb->index], j);
603
604	      if (info[bb->index].computing == m)
605		SET_BIT (comp[bb->index], j);
606	    }
607	}
608
609      /* Calculate the optimal locations for the
610	 placement mode switches to modes with priority I.  */
611
612      FOR_EACH_BB (bb)
613	sbitmap_not (kill[bb->index], transp[bb->index]);
614      edge_list = pre_edge_lcm (n_entities, transp, comp, antic,
615				kill, &insert, &del);
616
617      for (j = n_entities - 1; j >= 0; j--)
618	{
619	  /* Insert all mode sets that have been inserted by lcm.  */
620	  int no_mode = num_modes[entity_map[j]];
621
622	  /* Wherever we have moved a mode setting upwards in the flow graph,
623	     the blocks between the new setting site and the now redundant
624	     computation ceases to be transparent for any lower-priority
625	     mode of the same entity.  First set the aux field of each
626	     insertion site edge non-transparent, then propagate the new
627	     non-transparency from the redundant computation upwards till
628	     we hit an insertion site or an already non-transparent block.  */
629	  for (e = NUM_EDGES (edge_list) - 1; e >= 0; e--)
630	    {
631	      edge eg = INDEX_EDGE (edge_list, e);
632	      int mode;
633	      basic_block src_bb;
634	      HARD_REG_SET live_at_edge;
635	      rtx mode_set;
636
637	      eg->aux = 0;
638
639	      if (! TEST_BIT (insert[e], j))
640		continue;
641
642	      eg->aux = (void *)1;
643
644	      mode = current_mode[j];
645	      src_bb = eg->src;
646
647	      REG_SET_TO_HARD_REG_SET (live_at_edge, df_get_live_out (src_bb));
648
649	      start_sequence ();
650	      EMIT_MODE_SET (entity_map[j], mode, live_at_edge);
651	      mode_set = get_insns ();
652	      end_sequence ();
653
654	      /* Do not bother to insert empty sequence.  */
655	      if (mode_set == NULL_RTX)
656		continue;
657
658	      /* We should not get an abnormal edge here.  */
659	      gcc_assert (! (eg->flags & EDGE_ABNORMAL));
660
661	      need_commit = 1;
662	      insert_insn_on_edge (mode_set, eg);
663	    }
664
665	  FOR_EACH_BB_REVERSE (bb)
666	    if (TEST_BIT (del[bb->index], j))
667	      {
668		make_preds_opaque (bb, j);
669		/* Cancel the 'deleted' mode set.  */
670		bb_info[j][bb->index].seginfo->mode = no_mode;
671	      }
672	}
673
674      sbitmap_vector_free (del);
675      sbitmap_vector_free (insert);
676      clear_aux_for_edges ();
677      free_edge_list (edge_list);
678    }
679
680  /* Now output the remaining mode sets in all the segments.  */
681  for (j = n_entities - 1; j >= 0; j--)
682    {
683      int no_mode = num_modes[entity_map[j]];
684
685      FOR_EACH_BB_REVERSE (bb)
686	{
687	  struct seginfo *ptr, *next;
688	  for (ptr = bb_info[j][bb->index].seginfo; ptr; ptr = next)
689	    {
690	      next = ptr->next;
691	      if (ptr->mode != no_mode)
692		{
693		  rtx mode_set;
694
695		  start_sequence ();
696		  EMIT_MODE_SET (entity_map[j], ptr->mode, ptr->regs_live);
697		  mode_set = get_insns ();
698		  end_sequence ();
699
700		  /* Insert MODE_SET only if it is nonempty.  */
701		  if (mode_set != NULL_RTX)
702		    {
703		      emited = true;
704		      if (NOTE_INSN_BASIC_BLOCK_P (ptr->insn_ptr))
705			emit_insn_after (mode_set, ptr->insn_ptr);
706		      else
707			emit_insn_before (mode_set, ptr->insn_ptr);
708		    }
709		}
710
711	      free (ptr);
712	    }
713	}
714
715      free (bb_info[j]);
716    }
717
718  /* Finished. Free up all the things we've allocated.  */
719  sbitmap_vector_free (kill);
720  sbitmap_vector_free (antic);
721  sbitmap_vector_free (transp);
722  sbitmap_vector_free (comp);
723
724  if (need_commit)
725    commit_edge_insertions ();
726
727#if defined (MODE_ENTRY) && defined (MODE_EXIT)
728  cleanup_cfg (CLEANUP_NO_INSN_DEL);
729#else
730  if (!need_commit && !emited)
731    return 0;
732#endif
733
734  return 1;
735}
736
737#endif /* OPTIMIZE_MODE_SWITCHING */
738
739static bool
740gate_mode_switching (void)
741{
742#ifdef OPTIMIZE_MODE_SWITCHING
743  return true;
744#else
745  return false;
746#endif
747}
748
749static unsigned int
750rest_of_handle_mode_switching (void)
751{
752#ifdef OPTIMIZE_MODE_SWITCHING
753  optimize_mode_switching ();
754#endif /* OPTIMIZE_MODE_SWITCHING */
755  return 0;
756}
757
758
759struct rtl_opt_pass pass_mode_switching =
760{
761 {
762  RTL_PASS,
763  "mode_sw",                            /* name */
764  gate_mode_switching,                  /* gate */
765  rest_of_handle_mode_switching,        /* execute */
766  NULL,                                 /* sub */
767  NULL,                                 /* next */
768  0,                                    /* static_pass_number */
769  TV_MODE_SWITCH,                       /* tv_id */
770  0,                                    /* properties_required */
771  0,                                    /* properties_provided */
772  0,                                    /* properties_destroyed */
773  0,                                    /* todo_flags_start */
774  TODO_df_finish | TODO_verify_rtl_sharing |
775  TODO_dump_func                        /* todo_flags_finish */
776 }
777};
778