	* dbgcnt.def (sched_breakdep): New counter.
	* haifa-sched.c (update_insn_after_change): New static function,
	broken out of haifa_change_pattern.
	(haifa_change_pattern): Call it.
	(dep_t heap vecs): Declare.
	(INSN_COST): Define earlier.
	(next_cycle_replace_deps, next_cycle_apply): New static
	variables.
	(apply_replacement): New static function.
	(recompute_todo_spec): New argument FOR_BACKTRACK.  All callers
	changed.  Handle DEP_REPLACE deps.
	(contributes_to_priority_p): False for replaceable deps.
	(must_restore_pattern_p, restore_pattern): New static functions.
	(schedule_insn): Use them.  Apply replacements for broken deps.
	(struct haifa_saved_data): Add new fields to keep track of
	replacements.
	(save_backtrack_point): Initialize them.
	(undo_replacements_for_backtrack): New static function.
	(restore_last_backtrack_point, free_topmost_backtrack_point):
	Use it and keep track of replacements.
	(perform_replacements_new_cycle, undo_all_replacements): New static
	functions.
	(schedule_block): Call these two as necessary.  Call
	find_modifiable_mems.
	(try_ready): Tweak the assert.  Check for DEP_POSTPONED.
	* sched-deps.c: Include "emit-rtl.h".
	(init_dep_1): Initialize DEP_NONREG, DEP_MULTIPLE and DEP_REPLACE.
	(dep_spec_p): True for DEP_REPLACE deps.
	(mark_as_hard): New static variable.
	(update_dep): Update DEP_NONREG and DEP_MULTIPLE.
	(add_dependence_list): New argument hard.  All callers changed.  Set
	and clear mark_as_hard around function body.
	(add_dependence_list_and_free): Likewise.
	(haifa_note_mem_dep): Set DEP_NONREG.
	(sched_analyze_insn): Switch loop with if statement testing for
	sel_sched_p.
	(struct mem_inc_info): New.
	(attempt_change, parse_add_or_inc, find_inc, find_mem): New static
	functions.
	(find_modifiable_mems): New function.
	* sched-int.h (struct dep_replacement): New.
	(struct _dep): Add replace, nonreg and multiple fields.  Make type and
	cost bitfields.
	(UNKNOWN_DEP_COST): Change to match the bitfield.
	(DEP_NONREG, DEP_MULTIPLE, DEP_REPLACE): New macros.
	(DEP_POSTPONED): New macro.
	(DEP_CANCELLED): Renumber.
	(find_modifiable_mems): Declare.
	(enum SCHED_FLAGS): Add DONT_BREAK_DEPENDENCIES.
	* sched-rgn.c (init_ready_list): Set TODO_SPEC here.
	(new_ready): Don't set HARD_DEP, use DEP_POSTPONED.
	(debug_dependencies): Dump DEP_NONREG and DEP_MULTIPLE.
	* Makefile.in (sched-deps.o): Update dependencies.
	* config/c6x/c6x.c (in_hwloop): New static variable.
	(c6x_set_sched_flags): If it is true, add DONT_BREAK_DEPENDENCIES.
	(hwloop_optimize): Set and clear it around preliminary scheduling
	pass.

Index: gcc/dbgcnt.def
===================================================================
--- gcc/dbgcnt.def	(revision 189284)
+++ gcc/dbgcnt.def	(working copy)
@@ -176,6 +176,7 @@ DEBUG_COUNTER (sched2_func)
 DEBUG_COUNTER (sched_block)
 DEBUG_COUNTER (sched_func)
 DEBUG_COUNTER (sched_insn)
+DEBUG_COUNTER (sched_breakdep)
 DEBUG_COUNTER (sched_region)
 DEBUG_COUNTER (sel_sched_cnt)
 DEBUG_COUNTER (sel_sched_region_cnt)
Index: gcc/haifa-sched.c
===================================================================
--- gcc/haifa-sched.c	(revision 189284)
+++ gcc/haifa-sched.c	(working copy)
@@ -213,6 +213,9 @@ struct common_sched_info_def *common_sch
 #define FEEDS_BACKTRACK_INSN(INSN) (HID (INSN)->feeds_backtrack_insn)
 #define SHADOW_P(INSN) (HID (INSN)->shadow_p)
 #define MUST_RECOMPUTE_SPEC_P(INSN) (HID (INSN)->must_recompute_spec)
+/* Cached cost of the instruction.  Use insn_cost to get cost of the
+   insn.  -1 here means that the field is not initialized.  */
+#define INSN_COST(INSN)	(HID (INSN)->cost)
 
 /* If INSN_TICK of an instruction is equal to INVALID_TICK,
    then it should be recalculated from scratch.  */
@@ -1114,18 +1117,59 @@ cond_clobbered_p (rtx insn, HARD_REG_SET
   return false;
 }
 
+/* This function should be called after modifying the pattern of INSN,
+   to update scheduler data structures as needed.  */
+static void
+update_insn_after_change (rtx insn)
+{
+  sd_iterator_def sd_it;
+  dep_t dep;
+
+  dfa_clear_single_insn_cache (insn);
+
+  sd_it = sd_iterator_start (insn,
+			     SD_LIST_FORW | SD_LIST_BACK | SD_LIST_RES_BACK);
+  while (sd_iterator_cond (&sd_it, &dep))
+    {
+      DEP_COST (dep) = UNKNOWN_DEP_COST;
+      sd_iterator_next (&sd_it);
+    }
+
+  /* Invalidate INSN_COST, so it'll be recalculated.  */
+  INSN_COST (insn) = -1;
+  /* Invalidate INSN_TICK, so it'll be recalculated.  */
+  INSN_TICK (insn) = INVALID_TICK;
+}
+
+DEF_VEC_P(dep_t);
+DEF_VEC_ALLOC_P(dep_t, heap);
+
+/* Two VECs, one to hold dependencies for which pattern replacements
+   need to be applied or restored at the start of the next cycle, and
+   another to hold an integer that is either one, to apply the
+   corresponding replacement, or zero to restore it.  */
+static VEC(dep_t, heap) *next_cycle_replace_deps;
+static VEC(int, heap) *next_cycle_apply;
+
+static void apply_replacement (dep_t, bool);
+static void restore_pattern (dep_t, bool);
+
 /* Look at the remaining dependencies for insn NEXT, and compute and return
    the TODO_SPEC value we should use for it.  This is called after one of
-   NEXT's dependencies has been resolved.  */
+   NEXT's dependencies has been resolved.
+   We also perform pattern replacements for predication, and for broken
+   replacement dependencies.  The latter is only done if FOR_BACKTRACK is
+   false.  */
 
 static ds_t
-recompute_todo_spec (rtx next)
+recompute_todo_spec (rtx next, bool for_backtrack)
 {
   ds_t new_ds;
   sd_iterator_def sd_it;
-  dep_t dep, control_dep = NULL;
+  dep_t dep, modify_dep = NULL;
   int n_spec = 0;
   int n_control = 0;
+  int n_replace = 0;
   bool first_p = true;
 
   if (sd_lists_empty_p (next, SD_LIST_BACK))
@@ -1142,9 +1186,10 @@ recompute_todo_spec (rtx next)
 
   FOR_EACH_DEP (next, SD_LIST_BACK, sd_it, dep)
     {
+      rtx pro = DEP_PRO (dep);
       ds_t ds = DEP_STATUS (dep) & SPECULATIVE;
 
-      if (DEBUG_INSN_P (DEP_PRO (dep)) && !DEBUG_INSN_P (next))
+      if (DEBUG_INSN_P (pro) && !DEBUG_INSN_P (next))
 	continue;
 
       if (ds)
@@ -1159,15 +1204,47 @@ recompute_todo_spec (rtx next)
 	  else
 	    new_ds = ds_merge (new_ds, ds);
 	}
-      if (DEP_TYPE (dep) == REG_DEP_CONTROL)
+      else if (DEP_TYPE (dep) == REG_DEP_CONTROL)
 	{
-	  n_control++;
-	  control_dep = dep;
+	  if (QUEUE_INDEX (pro) != QUEUE_SCHEDULED)
+	    {
+	      n_control++;
+	      modify_dep = dep;
+	    }
+	  DEP_STATUS (dep) &= ~DEP_CANCELLED;
+	}
+      else if (DEP_REPLACE (dep) != NULL)
+	{
+	  if (QUEUE_INDEX (pro) != QUEUE_SCHEDULED)
+	    {
+	      n_replace++;
+	      modify_dep = dep;
+	    }
 	  DEP_STATUS (dep) &= ~DEP_CANCELLED;
 	}
     }
 
-  if (n_control == 1 && n_spec == 0)
+  if (n_replace > 0 && n_control == 0 && n_spec == 0)
+    {
+      if (!dbg_cnt (sched_breakdep))
+	return HARD_DEP;
+      FOR_EACH_DEP (next, SD_LIST_BACK, sd_it, dep)
+	{
+	  struct dep_replacement *desc = DEP_REPLACE (dep);
+	  if (desc != NULL)
+	    {
+	      if (desc->insn == next && !for_backtrack)
+		{
+		  gcc_assert (n_replace == 1);
+		  apply_replacement (dep, true);
+		}
+	      DEP_STATUS (dep) |= DEP_CANCELLED;
+	    }
+	}
+      return 0;
+    }
+  
+  else if (n_control == 1 && n_replace == 0 && n_spec == 0)
     {
       rtx pro, other, new_pat;
       rtx cond = NULL_RTX;
@@ -1181,7 +1258,7 @@ recompute_todo_spec (rtx next)
 	      && PREDICATED_PAT (next) == NULL_RTX))
 	return HARD_DEP;
 
-      pro = DEP_PRO (control_dep);
+      pro = DEP_PRO (modify_dep);
       other = real_insn_for_shadow (pro);
       if (other != NULL_RTX)
 	pro = other;
@@ -1220,7 +1297,7 @@ recompute_todo_spec (rtx next)
 					       PREDICATED_PAT (next));
 	  gcc_assert (success);
 	}
-      DEP_STATUS (control_dep) |= DEP_CANCELLED;
+      DEP_STATUS (modify_dep) |= DEP_CANCELLED;
       return DEP_CONTROL;
     }
 
@@ -1237,11 +1314,12 @@ recompute_todo_spec (rtx next)
      dependencies, so we return HARD_DEP in such a case.  Also fail if
      we have speculative dependencies with not enough points, or more than
      one control dependency.  */
-  if ((n_spec > 0 && n_control > 0)
+  if ((n_spec > 0 && (n_control > 0 || n_replace > 0))
       || (n_spec > 0
 	  /* Too few points?  */
 	  && ds_weak (new_ds) < spec_info->data_weakness_cutoff)
-      || (n_control > 1))
+      || n_control > 0
+      || n_replace > 0)
     return HARD_DEP;
 
   return new_ds;
@@ -1261,10 +1339,6 @@ static rtx last_nondebug_scheduled_insn;
    first unscheduled one.  */
 static rtx nonscheduled_insns_begin;
 
-/* Cached cost of the instruction.  Use below function to get cost of the
-   insn.  -1 here means that the field is not initialized.  */
-#define INSN_COST(INSN)	(HID (INSN)->cost)
-
 /* Compute cost of executing INSN.
    This is the number of cycles between instruction issue and
    instruction results.  */
@@ -1443,6 +1517,9 @@ contributes_to_priority_p (dep_t dep)
 						    DEP_PRO (dep)))
     return false;
 
+  if (DEP_REPLACE (dep) != NULL)
+    return false;
+
   /* If flag COUNT_SPEC_IN_CRITICAL_PATH is set,
      then speculative instructions will less likely be
      scheduled.  That is because the priority of
@@ -2136,6 +2213,31 @@ model_recompute (rtx insn)
   if (print_p)
     fprintf (sched_dump, MODEL_BAR);
 }
+
+/* After DEP, which was cancelled, has been resolved for insn NEXT,
+   check whether the insn's pattern needs restoring.  */
+static bool
+must_restore_pattern_p (rtx next, dep_t dep)
+{
+  if (QUEUE_INDEX (next) == QUEUE_SCHEDULED)
+    return false;
+
+  if (DEP_TYPE (dep) == REG_DEP_CONTROL)
+    {
+      gcc_assert (ORIG_PAT (next) != NULL_RTX);
+      gcc_assert (next == DEP_CON (dep));
+    }
+  else
+    {
+      struct dep_replacement *desc = DEP_REPLACE (dep);
+      if (desc->insn != next)
+	{
+	  gcc_assert (*desc->loc == desc->orig);
+	  return false;
+	}
+    }
+  return true;
+}
 
 /* model_spill_cost (CL, P, P') returns the cost of increasing the
    pressure on CL from P to P'.  We use this to calculate a "base ECC",
@@ -3735,7 +3837,20 @@ schedule_insn (rtx insn)
 
   check_clobbered_conditions (insn);
 
-  /* Update dependent instructions.  */
+  /* Update dependent instructions.  First, see if by scheduling this insn
+     now we broke a dependence in a way that requires us to change another
+     insn.  */
+  for (sd_it = sd_iterator_start (insn, SD_LIST_SPEC_BACK);
+       sd_iterator_cond (&sd_it, &dep); sd_iterator_next (&sd_it))
+    {
+      struct dep_replacement *desc = DEP_REPLACE (dep);
+      rtx pro = DEP_PRO (dep);
+      if (QUEUE_INDEX (pro) != QUEUE_SCHEDULED
+	  && desc != NULL && desc->insn == pro)
+	apply_replacement (dep, false);
+    }
+
+  /* Go through and resolve forward dependencies.  */
   for (sd_it = sd_iterator_start (insn, SD_LIST_FORW);
        sd_iterator_cond (&sd_it, &dep);)
     {
@@ -3749,17 +3864,8 @@ schedule_insn (rtx insn)
 
       if (cancelled)
 	{
-	  if (QUEUE_INDEX (next) != QUEUE_SCHEDULED)
-	    {
-	      int tick = INSN_TICK (next);
-	      gcc_assert (ORIG_PAT (next) != NULL_RTX);
-	      haifa_change_pattern (next, ORIG_PAT (next));
-	      INSN_TICK (next) = tick;
-	      if (sd_lists_empty_p (next, SD_LIST_BACK))
-		TODO_SPEC (next) = 0;
-	      else if (!sd_lists_empty_p (next, SD_LIST_HARD_BACK))
-		TODO_SPEC (next) = HARD_DEP;
-	    }
+	  if (must_restore_pattern_p (next, dep))
+	    restore_pattern (dep, false);
 	  continue;
 	}
 
@@ -3917,6 +4023,16 @@ struct haifa_saved_data
      to 0 when restoring.  */
   int q_size;
   rtx *insn_queue;
+
+  /* Describe pattern replacements that occurred since this backtrack point
+     was queued.  */
+  VEC (dep_t, heap) *replacement_deps;
+  VEC (int, heap) *replace_apply;
+
+  /* A copy of the next-cycle replacement vectors at the time of the backtrack
+     point.  */
+  VEC (dep_t, heap) *next_cycle_deps;
+  VEC (int, heap) *next_cycle_apply;
 };
 
 /* A record, in reverse order, of all scheduled insns which have delay slots
@@ -3973,6 +4089,11 @@ save_backtrack_point (struct delay_pair
 
   save->sched_block = sched_block;
 
+  save->replacement_deps = NULL;
+  save->replace_apply = NULL;
+  save->next_cycle_deps = VEC_copy (dep_t, heap, next_cycle_replace_deps);
+  save->next_cycle_apply = VEC_copy (int, heap, next_cycle_apply);
+
   if (current_sched_info->save_state)
     save->fe_saved_data = (*current_sched_info->save_state) ();
 
@@ -4042,6 +4163,25 @@ toggle_cancelled_flags (bool set)
     }
 }
 
+/* Undo the replacements that have occurred after backtrack point SAVE
+   was placed.  */
+static void
+undo_replacements_for_backtrack (struct haifa_saved_data *save)
+{
+  while (!VEC_empty (dep_t, save->replacement_deps))
+    {
+      dep_t dep = VEC_pop (dep_t, save->replacement_deps);
+      int apply_p = VEC_pop (int, save->replace_apply);
+
+      if (apply_p)
+	restore_pattern (dep, true);
+      else
+	apply_replacement (dep, true);
+    }
+  VEC_free (dep_t, heap, save->replacement_deps);
+  VEC_free (int, heap, save->replace_apply);
+}
+
 /* Pop entries from the SCHEDULED_INSNS vector up to and including INSN.
    Restore their dependencies to an unresolved state, and mark them as
    queued nowhere.  */
@@ -4107,7 +4247,7 @@ unschedule_insns_until (rtx insn)
 	    haifa_change_pattern (con, ORIG_PAT (con));
 	}
       else if (QUEUE_INDEX (con) != QUEUE_SCHEDULED)
-	TODO_SPEC (con) = recompute_todo_spec (con);
+	TODO_SPEC (con) = recompute_todo_spec (con, true);
     }
   VEC_free (rtx, heap, recompute_vec);
 }
@@ -4135,6 +4275,10 @@ restore_last_backtrack_point (struct sch
       targetm.sched.free_sched_context (save->be_saved_data);
     }
 
+  /* Do this first since it clobbers INSN_TICK of the involved
+     instructions.  */
+  undo_replacements_for_backtrack (save);
+
   /* Clear the QUEUE_INDEX of everything in the ready list or one
      of the queues.  */
   if (ready.n_ready > 0)
@@ -4170,7 +4314,7 @@ restore_last_backtrack_point (struct sch
 	{
 	  rtx insn = first[i];
 	  QUEUE_INDEX (insn) = QUEUE_READY;
-	  TODO_SPEC (insn) = recompute_todo_spec (insn);
+	  TODO_SPEC (insn) = recompute_todo_spec (insn, true);
 	  INSN_TICK (insn) = save->clock_var;
 	}
     }
@@ -4187,7 +4331,7 @@ restore_last_backtrack_point (struct sch
 	{
 	  rtx x = XEXP (link, 0);
 	  QUEUE_INDEX (x) = i;
-	  TODO_SPEC (x) = recompute_todo_spec (x);
+	  TODO_SPEC (x) = recompute_todo_spec (x, true);
 	  INSN_TICK (x) = save->clock_var + i;
 	}
     }
@@ -4208,6 +4352,10 @@ restore_last_backtrack_point (struct sch
 
   mark_backtrack_feeds (save->delay_pair->i2, 0);
 
+  gcc_assert (VEC_empty (dep_t, next_cycle_replace_deps));
+  next_cycle_replace_deps = VEC_copy (dep_t, heap, save->next_cycle_deps);
+  next_cycle_apply = VEC_copy (int, heap, save->next_cycle_apply);
+
   free (save);
 
   for (save = backtrack_queue; save; save = save->next)
@@ -4237,7 +4385,14 @@ free_topmost_backtrack_point (bool reset
 	  INSN_EXACT_TICK (pair->i2) = INVALID_TICK;
 	  pair = pair->next_same_i1;
 	}
+      undo_replacements_for_backtrack (save);
     }
+  else
+    {
+      VEC_free (dep_t, heap, save->replacement_deps);
+      VEC_free (int, heap, save->replace_apply);
+    }
+
   if (targetm.sched.free_sched_context)
     targetm.sched.free_sched_context (save->be_saved_data);
   if (current_sched_info->restore_state)
@@ -4258,6 +4413,124 @@ free_backtrack_queue (void)
     free_topmost_backtrack_point (false);
 }
 
+/* Apply a replacement described by DESC.  If IMMEDIATELY is false, we
+   may have to postpone the replacement until the start of the next cycle,
+   at which point we will be called again with IMMEDIATELY true.  This is
+   only done for machines which have instruction packets with explicit
+   parallelism however.  */
+static void
+apply_replacement (dep_t dep, bool immediately)
+{
+  struct dep_replacement *desc = DEP_REPLACE (dep);
+  if (!immediately && targetm.sched.exposed_pipeline && reload_completed)
+    {
+      VEC_safe_push (dep_t, heap, next_cycle_replace_deps, dep);
+      VEC_safe_push (int, heap, next_cycle_apply, 1);
+    }
+  else
+    {
+      bool success;
+
+      if (QUEUE_INDEX (desc->insn) == QUEUE_SCHEDULED)
+	return;
+
+      if (sched_verbose >= 5)
+	fprintf (sched_dump, "applying replacement for insn %d\n",
+		 INSN_UID (desc->insn));
+
+      success = validate_change (desc->insn, desc->loc, desc->newval, 0);
+      gcc_assert (success);
+
+      update_insn_after_change (desc->insn);
+      if ((TODO_SPEC (desc->insn) & (HARD_DEP | DEP_POSTPONED)) == 0)
+	fix_tick_ready (desc->insn);
+
+      if (backtrack_queue != NULL)
+	{
+	  VEC_safe_push (dep_t, heap, backtrack_queue->replacement_deps, dep);
+	  VEC_safe_push (int, heap, backtrack_queue->replace_apply, 1);
+	}
+    }
+}
+
+/* We have determined that a pattern involved in DEP must be restored.
+   If IMMEDIATELY is false, we may have to postpone the replacement
+   until the start of the next cycle, at which point we will be called
+   again with IMMEDIATELY true.  */
+static void
+restore_pattern (dep_t dep, bool immediately)
+{
+  rtx next = DEP_CON (dep);
+  int tick = INSN_TICK (next);
+
+  /* If we already scheduled the insn, the modified version is
+     correct.  */
+  if (QUEUE_INDEX (next) == QUEUE_SCHEDULED)
+    return;
+
+  if (!immediately && targetm.sched.exposed_pipeline && reload_completed)
+    {
+      VEC_safe_push (dep_t, heap, next_cycle_replace_deps, dep);
+      VEC_safe_push (int, heap, next_cycle_apply, 0);
+      return;
+    }
+
+
+  if (DEP_TYPE (dep) == REG_DEP_CONTROL)
+    {
+      if (sched_verbose >= 5)
+	fprintf (sched_dump, "restoring pattern for insn %d\n",
+		 INSN_UID (next));
+      haifa_change_pattern (next, ORIG_PAT (next));
+    }
+  else
+    {
+      struct dep_replacement *desc = DEP_REPLACE (dep);
+      bool success;
+
+      if (sched_verbose >= 5)
+	fprintf (sched_dump, "restoring pattern for insn %d\n",
+		 INSN_UID (desc->insn));
+      tick = INSN_TICK (desc->insn);
+
+      success = validate_change (desc->insn, desc->loc, desc->orig, 0);
+      gcc_assert (success);
+      update_insn_after_change (desc->insn);
+      if (backtrack_queue != NULL)
+	{
+	  VEC_safe_push (dep_t, heap, backtrack_queue->replacement_deps, dep);
+	  VEC_safe_push (int, heap, backtrack_queue->replace_apply, 0);
+	}
+    }
+  INSN_TICK (next) = tick;
+  if (TODO_SPEC (next) == DEP_POSTPONED)
+    return;
+
+  if (sd_lists_empty_p (next, SD_LIST_BACK))
+    TODO_SPEC (next) = 0;
+  else if (!sd_lists_empty_p (next, SD_LIST_HARD_BACK))
+    TODO_SPEC (next) = HARD_DEP;
+}
+
+/* Perform pattern replacements that were queued up until the next
+   cycle.  */
+static void
+perform_replacements_new_cycle (void)
+{
+  int i;
+  dep_t dep;
+  FOR_EACH_VEC_ELT (dep_t, next_cycle_replace_deps, i, dep)
+    {
+      int apply_p = VEC_index (int, next_cycle_apply, i);
+      if (apply_p)
+	apply_replacement (dep, true);
+      else
+	restore_pattern (dep, true);
+    }
+  VEC_truncate (dep_t, next_cycle_replace_deps, 0);
+  VEC_truncate (int, next_cycle_apply, 0);
+}
+
 /* Compute INSN_TICK_ESTIMATE for INSN.  PROCESSED is a bitmap of
    instructions we've previously encountered, a set bit prevents
    recursion.  BUDGET is a limit on how far ahead we look, it is
@@ -4515,6 +4788,30 @@ restore_other_notes (rtx head, basic_blo
   return head;
 }
 
+/* When we know we are going to discard the schedule due to a failed attempt
+   at modulo scheduling, undo all replacements.  */
+static void
+undo_all_replacements (void)
+{
+  rtx insn;
+  int i;
+
+  FOR_EACH_VEC_ELT (rtx, scheduled_insns, i, insn)
+    {
+      sd_iterator_def sd_it;
+      dep_t dep;
+
+      /* See if we must undo a replacement.  */
+      for (sd_it = sd_iterator_start (insn, SD_LIST_RES_FORW);
+	   sd_iterator_cond (&sd_it, &dep); sd_iterator_next (&sd_it))
+	{
+	  struct dep_replacement *desc = DEP_REPLACE (dep);
+	  if (desc != NULL)
+	    validate_change (desc->insn, desc->loc, desc->orig, 0);
+	}
+    }
+}
+
 /* Move insns that became ready to fire from queue to ready list.  */
 
 static void
@@ -5556,6 +5853,9 @@ schedule_block (basic_block *target_bb)
   rtx head = NEXT_INSN (prev_head);
   rtx tail = PREV_INSN (next_tail);
 
+  if ((current_sched_info->flags & DONT_BREAK_DEPENDENCIES) == 0)
+    find_modifiable_mems (head, tail);
+
   /* We used to have code to avoid getting parameters moved from hard
      argument registers into pseudos.
 
@@ -5676,6 +5976,7 @@ schedule_block (basic_block *target_bb)
   /* Loop until all the insns in BB are scheduled.  */
   while ((*current_sched_info->schedule_more_p) ())
     {
+      perform_replacements_new_cycle ();
       do
 	{
 	  start_clock_var = clock_var;
@@ -5892,7 +6193,7 @@ schedule_block (basic_block *target_bb)
 	    /* We normally get here only if we don't want to move
 	       insn from the split block.  */
 	    {
-	      TODO_SPEC (insn) = HARD_DEP;
+	      TODO_SPEC (insn) = DEP_POSTPONED;
 	      goto restart_choose_ready;
 	    }
 
@@ -6003,6 +6304,8 @@ schedule_block (basic_block *target_bb)
 	  gcc_assert (failed);
 
 	  failed_insn = failed->delay_pair->i1;
+	  /* Clear these queues.  */
+	  perform_replacements_new_cycle ();
 	  toggle_cancelled_flags (false);
 	  unschedule_insns_until (failed_insn);
 	  while (failed != backtrack_queue)
@@ -6030,6 +6333,7 @@ schedule_block (basic_block *target_bb)
   if (ls.modulo_epilogue)
     success = true;
  end_schedule:
+  perform_replacements_new_cycle ();
   if (modulo_ii > 0)
     {
       /* Once again, debug insn suckiness: they can be on the ready list
@@ -6069,6 +6373,9 @@ schedule_block (basic_block *target_bb)
 	}
     }
 
+  if (!success)
+    undo_all_replacements ();
+
   /* Debug info.  */
   if (sched_verbose)
     {
@@ -6552,14 +6859,15 @@ try_ready (rtx next)
 
   old_ts = TODO_SPEC (next);
 
-  gcc_assert (!(old_ts & ~(SPECULATIVE | HARD_DEP | DEP_CONTROL))
-	      && ((old_ts & HARD_DEP)
+  gcc_assert (!(old_ts & ~(SPECULATIVE | HARD_DEP | DEP_CONTROL | DEP_POSTPONED))
+	      && (old_ts == HARD_DEP
+		  || old_ts == DEP_POSTPONED
 		  || (old_ts & SPECULATIVE)
-		  || (old_ts & DEP_CONTROL)));
+		  || old_ts == DEP_CONTROL));
 
-  new_ts = recompute_todo_spec (next);
+  new_ts = recompute_todo_spec (next, false);
 
-  if (new_ts & HARD_DEP)
+  if (new_ts & (HARD_DEP | DEP_POSTPONED))
     gcc_assert (new_ts == old_ts
 		&& QUEUE_INDEX (next) == QUEUE_NOWHERE);
   else if (current_sched_info->new_ready)
@@ -6627,7 +6935,7 @@ try_ready (rtx next)
 
   TODO_SPEC (next) = new_ts;
 
-  if (new_ts & HARD_DEP)
+  if (new_ts & (HARD_DEP | DEP_POSTPONED))
     {
       /* We can't assert (QUEUE_INDEX (next) == QUEUE_NOWHERE) here because
 	 control-speculative NEXT could have been discarded by sched-rgn.c
@@ -7647,27 +7955,13 @@ fix_recovery_deps (basic_block rec)
 static bool
 haifa_change_pattern (rtx insn, rtx new_pat)
 {
-  sd_iterator_def sd_it;
-  dep_t dep;
   int t;
 
   t = validate_change (insn, &PATTERN (insn), new_pat, 0);
   if (!t)
     return false;
-  dfa_clear_single_insn_cache (insn);
 
-  sd_it = sd_iterator_start (insn,
-			     SD_LIST_FORW | SD_LIST_BACK | SD_LIST_RES_BACK);
-  while (sd_iterator_cond (&sd_it, &dep))
-    {
-      DEP_COST (dep) = UNKNOWN_DEP_COST;
-      sd_iterator_next (&sd_it);
-    }
-
-  /* Invalidate INSN_COST, so it'll be recalculated.  */
-  INSN_COST (insn) = -1;
-  /* Invalidate INSN_TICK, so it'll be recalculated.  */
-  INSN_TICK (insn) = INVALID_TICK;
+  update_insn_after_change (insn);
   return true;
 }
 
Index: gcc/sched-deps.c
===================================================================
--- gcc/sched-deps.c	(revision 189284)
+++ gcc/sched-deps.c	(working copy)
@@ -38,6 +38,7 @@ along with GCC; see the file COPYING3.
 #include "insn-attr.h"
 #include "except.h"
 #include "recog.h"
+#include "emit-rtl.h"
 #include "sched-int.h"
 #include "params.h"
 #include "cselib.h"
@@ -108,6 +109,9 @@ init_dep_1 (dep_t dep, rtx pro, rtx con,
   DEP_TYPE (dep) = type;
   DEP_STATUS (dep) = ds;
   DEP_COST (dep) = UNKNOWN_DEP_COST;
+  DEP_NONREG (dep) = 0;
+  DEP_MULTIPLE (dep) = 0;
+  DEP_REPLACE (dep) = NULL;
 }
 
 /* Init DEP with the arguments.
@@ -433,6 +437,8 @@ dep_spec_p (dep_t dep)
       if (DEP_TYPE (dep) == REG_DEP_CONTROL)
 	return true;
     }
+  if (DEP_REPLACE (dep) != NULL)
+    return true;
   return false;
 }
 
@@ -471,11 +477,14 @@ static bitmap_head *control_dependency_c
 static bitmap_head *spec_dependency_cache = NULL;
 static int cache_size;
 
+/* True if we should mark added dependencies as a non-register deps.  */
+static bool mark_as_hard;
+
 static int deps_may_trap_p (const_rtx);
 static void add_dependence_1 (rtx, rtx, enum reg_note);
-static void add_dependence_list (rtx, rtx, int, enum reg_note);
+static void add_dependence_list (rtx, rtx, int, enum reg_note, bool);
 static void add_dependence_list_and_free (struct deps_desc *, rtx,
-					  rtx *, int, enum reg_note);
+					  rtx *, int, enum reg_note, bool);
 static void delete_all_dependences (rtx);
 static void chain_to_prev_insn (rtx);
 
@@ -1135,6 +1144,9 @@ update_dep (dep_t dep, dep_t new_dep,
   enum reg_note old_type = DEP_TYPE (dep);
   bool was_spec = dep_spec_p (dep);
 
+  DEP_NONREG (dep) |= DEP_NONREG (new_dep);
+  DEP_MULTIPLE (dep) = 1;
+
   /* If this is a more restrictive type of dependence than the
      existing one, then change the existing dependence to this
      type.  */
@@ -1537,31 +1549,36 @@ add_dependence (rtx con, rtx pro, enum r
 	    fprintf (sched_dump, "making DEP_CONTROL for %d\n",
 		     INSN_UID (real_pro));
 	  add_dependence_list (con, INSN_COND_DEPS (real_pro), 0,
-			       REG_DEP_TRUE);
+			       REG_DEP_TRUE, false);
 	}
     }
 	  
   add_dependence_1 (con, pro, dep_type);
 }
 
-/* A convenience wrapper to operate on an entire list.  */
+/* A convenience wrapper to operate on an entire list.  HARD should be
+   true if DEP_NONREG should be set on newly created dependencies.  */
 
 static void
-add_dependence_list (rtx insn, rtx list, int uncond, enum reg_note dep_type)
+add_dependence_list (rtx insn, rtx list, int uncond, enum reg_note dep_type,
+		     bool hard)
 {
+  mark_as_hard = hard;
   for (; list; list = XEXP (list, 1))
     {
       if (uncond || ! sched_insns_conditions_mutex_p (insn, XEXP (list, 0)))
 	add_dependence (insn, XEXP (list, 0), dep_type);
     }
+  mark_as_hard = false;
 }
 
 /* Similar, but free *LISTP at the same time, when the context
-   is not readonly.  */
+   is not readonly.  HARD should be true if DEP_NONREG should be set on
+   newly created dependencies.  */
 
 static void
 add_dependence_list_and_free (struct deps_desc *deps, rtx insn, rtx *listp,
-                              int uncond, enum reg_note dep_type)
+                              int uncond, enum reg_note dep_type, bool hard)
 {
   rtx list, next;
 
@@ -1570,10 +1587,11 @@ add_dependence_list_and_free (struct dep
      disregarded.  */
   if (deps->readonly || DEBUG_INSN_P (insn))
     {
-      add_dependence_list (insn, *listp, uncond, dep_type);
+      add_dependence_list (insn, *listp, uncond, dep_type, hard);
       return;
     }
 
+  mark_as_hard = hard;
   for (list = *listp, *listp = NULL; list ; list = next)
     {
       next = XEXP (list, 1);
@@ -1581,6 +1599,7 @@ add_dependence_list_and_free (struct dep
 	add_dependence (insn, XEXP (list, 0), dep_type);
       free_INSN_LIST_node (list);
     }
+  mark_as_hard = false;
 }
 
 /* Remove all occurrences of INSN from LIST.  Return the number of
@@ -1746,7 +1765,7 @@ flush_pending_lists (struct deps_desc *d
   if (for_write)
     {
       add_dependence_list_and_free (deps, insn, &deps->pending_read_insns,
-                                    1, REG_DEP_ANTI);
+                                    1, REG_DEP_ANTI, true);
       if (!deps->readonly)
         {
           free_EXPR_LIST_list (&deps->pending_read_mems);
@@ -1755,14 +1774,16 @@ flush_pending_lists (struct deps_desc *d
     }
 
   add_dependence_list_and_free (deps, insn, &deps->pending_write_insns, 1,
-				for_read ? REG_DEP_ANTI : REG_DEP_OUTPUT);
+				for_read ? REG_DEP_ANTI : REG_DEP_OUTPUT,
+				true);
 
   add_dependence_list_and_free (deps, insn,
                                 &deps->last_pending_memory_flush, 1,
-                                for_read ? REG_DEP_ANTI : REG_DEP_OUTPUT);
+                                for_read ? REG_DEP_ANTI : REG_DEP_OUTPUT,
+				true);
 
   add_dependence_list_and_free (deps, insn, &deps->pending_jump_insns, 1,
-				REG_DEP_ANTI);
+				REG_DEP_ANTI, true);
 
   if (!deps->readonly)
     {
@@ -1827,6 +1848,7 @@ haifa_note_mem_dep (rtx mem, rtx pending
 
     init_dep_1 (dep, pending_insn, cur_insn, ds_to_dt (ds),
                 current_sched_info->flags & USE_DEPS_LIST ? ds : 0);
+    DEP_NONREG (dep) = 1;
     maybe_add_or_update_dep_1 (dep, false, pending_mem, mem);
   }
 
@@ -1839,6 +1861,8 @@ haifa_note_dep (rtx elem, ds_t ds)
   dep_t dep = &_dep;
 
   init_dep (dep, elem, cur_insn, ds_to_dt (ds));
+  if (mark_as_hard)
+    DEP_NONREG (dep) = 1;
   maybe_add_or_update_dep_1 (dep, false, NULL_RTX, NULL_RTX);
 }
 
@@ -2343,7 +2367,7 @@ sched_analyze_reg (struct deps_desc *dep
 	      = alloc_INSN_LIST (insn, deps->sched_before_next_call);
 	  else
 	    add_dependence_list (insn, deps->last_function_call, 1,
-				 REG_DEP_ANTI);
+				 REG_DEP_ANTI, false);
 	}
     }
 }
@@ -2499,9 +2523,9 @@ sched_analyze_1 (struct deps_desc *deps,
 	    }
 
 	  add_dependence_list (insn, deps->last_pending_memory_flush, 1,
-			       REG_DEP_ANTI);
+			       REG_DEP_ANTI, true);
 	  add_dependence_list (insn, deps->pending_jump_insns, 1,
-			       REG_DEP_CONTROL);
+			       REG_DEP_CONTROL, true);
 
           if (!deps->readonly)
             add_insn_mem_dependence (deps, false, insn, dest);
@@ -2801,7 +2825,7 @@ sched_analyze_insn (struct deps_desc *de
     /* Avoid moving trapping instructions across function calls that might
        not always return.  */
     add_dependence_list (insn, deps->last_function_call_may_noreturn,
-			 1, REG_DEP_ANTI);
+			 1, REG_DEP_ANTI, true);
 
   /* We must avoid creating a situation in which two successors of the
      current block have different unwind info after scheduling.  If at any
@@ -2818,7 +2842,8 @@ sched_analyze_insn (struct deps_desc *de
 	= alloc_INSN_LIST (insn, deps->sched_before_next_jump);
 
       /* Make sure epilogue insn is scheduled after preceding jumps.  */
-      add_dependence_list (insn, deps->pending_jump_insns, 1, REG_DEP_ANTI);
+      add_dependence_list (insn, deps->pending_jump_insns, 1, REG_DEP_ANTI,
+			   true);
     }
 
   if (code == COND_EXEC)
@@ -2839,7 +2864,7 @@ sched_analyze_insn (struct deps_desc *de
 	 instruction so that reg-stack won't get confused.  */
       if (code == CLOBBER)
 	add_dependence_list (insn, deps->last_function_call, 1,
-			     REG_DEP_OUTPUT);
+			     REG_DEP_OUTPUT, true);
     }
   else if (code == PARALLEL)
     {
@@ -2900,11 +2925,12 @@ sched_analyze_insn (struct deps_desc *de
               EXECUTE_IF_SET_IN_REG_SET (reg_pending_control_uses, 0, i, rsi)
                 {
                   struct deps_reg *reg_last = &deps->reg_last[i];
-                  add_dependence_list (insn, reg_last->sets, 0, REG_DEP_ANTI);
+                  add_dependence_list (insn, reg_last->sets, 0, REG_DEP_ANTI,
+				       false);
                   add_dependence_list (insn, reg_last->implicit_sets,
-				       0, REG_DEP_ANTI);
+				       0, REG_DEP_ANTI, false);
                   add_dependence_list (insn, reg_last->clobbers, 0,
-				       REG_DEP_ANTI);
+				       REG_DEP_ANTI, false);
                 }
             }
 
@@ -2934,9 +2960,9 @@ sched_analyze_insn (struct deps_desc *de
 	    }
 
 	  add_dependence_list (insn, deps->last_pending_memory_flush, 1,
-			       REG_DEP_ANTI);
+			       REG_DEP_ANTI, true);
 	  add_dependence_list (insn, deps->pending_jump_insns, 1,
-			       REG_DEP_ANTI);
+			       REG_DEP_ANTI, true);
 	}
     }
 
@@ -2969,19 +2995,20 @@ sched_analyze_insn (struct deps_desc *de
 	add_dependence (insn, prev, REG_DEP_ANTI);
 
       add_dependence_list (insn, deps->last_function_call, 1,
-			   REG_DEP_ANTI);
+			   REG_DEP_ANTI, false);
 
-      for (u = deps->last_pending_memory_flush; u; u = XEXP (u, 1))
-	if (!sel_sched_p ())
+      if (!sel_sched_p ())
+	for (u = deps->last_pending_memory_flush; u; u = XEXP (u, 1))
 	  add_dependence (insn, XEXP (u, 0), REG_DEP_ANTI);
 
       EXECUTE_IF_SET_IN_REG_SET (reg_pending_uses, 0, i, rsi)
 	{
 	  struct deps_reg *reg_last = &deps->reg_last[i];
-	  add_dependence_list (insn, reg_last->sets, 1, REG_DEP_ANTI);
+	  add_dependence_list (insn, reg_last->sets, 1, REG_DEP_ANTI, false);
 	  /* There's no point in making REG_DEP_CONTROL dependencies for
 	     debug insns.  */
-	  add_dependence_list (insn, reg_last->clobbers, 1, REG_DEP_ANTI);
+	  add_dependence_list (insn, reg_last->clobbers, 1, REG_DEP_ANTI,
+			       false);
 
 	  if (!deps->readonly)
 	    reg_last->uses = alloc_INSN_LIST (insn, reg_last->uses);
@@ -3007,9 +3034,11 @@ sched_analyze_insn (struct deps_desc *de
       EXECUTE_IF_SET_IN_REG_SET (reg_pending_uses, 0, i, rsi)
 	{
 	  struct deps_reg *reg_last = &deps->reg_last[i];
-	  add_dependence_list (insn, reg_last->sets, 0, REG_DEP_TRUE);
-	  add_dependence_list (insn, reg_last->implicit_sets, 0, REG_DEP_ANTI);
-	  add_dependence_list (insn, reg_last->clobbers, 0, REG_DEP_TRUE);
+	  add_dependence_list (insn, reg_last->sets, 0, REG_DEP_TRUE, false);
+	  add_dependence_list (insn, reg_last->implicit_sets, 0, REG_DEP_ANTI,
+			       false);
+	  add_dependence_list (insn, reg_last->clobbers, 0, REG_DEP_TRUE,
+			       false);
 
 	  if (!deps->readonly)
 	    {
@@ -3022,10 +3051,11 @@ sched_analyze_insn (struct deps_desc *de
 	if (TEST_HARD_REG_BIT (implicit_reg_pending_uses, i))
 	  {
 	    struct deps_reg *reg_last = &deps->reg_last[i];
-	    add_dependence_list (insn, reg_last->sets, 0, REG_DEP_TRUE);
+	    add_dependence_list (insn, reg_last->sets, 0, REG_DEP_TRUE, false);
 	    add_dependence_list (insn, reg_last->implicit_sets, 0,
-				 REG_DEP_ANTI);
-	    add_dependence_list (insn, reg_last->clobbers, 0, REG_DEP_TRUE);
+				 REG_DEP_ANTI, false);
+	    add_dependence_list (insn, reg_last->clobbers, 0, REG_DEP_TRUE,
+				 false);
 
 	    if (!deps->readonly)
 	      {
@@ -3060,12 +3090,14 @@ sched_analyze_insn (struct deps_desc *de
 	  EXECUTE_IF_SET_IN_REG_SET (reg_pending_clobbers, 0, i, rsi)
 	    {
 	      struct deps_reg *reg_last = &deps->reg_last[i];
-	      add_dependence_list (insn, reg_last->sets, 0, REG_DEP_OUTPUT);
+	      add_dependence_list (insn, reg_last->sets, 0, REG_DEP_OUTPUT,
+				   false);
 	      add_dependence_list (insn, reg_last->implicit_sets, 0,
-				   REG_DEP_ANTI);
-	      add_dependence_list (insn, reg_last->uses, 0, REG_DEP_ANTI);
+				   REG_DEP_ANTI, false);
+	      add_dependence_list (insn, reg_last->uses, 0, REG_DEP_ANTI,
+				   false);
 	      add_dependence_list (insn, reg_last->control_uses, 0,
-				   REG_DEP_CONTROL);
+				   REG_DEP_CONTROL, false);
 
 	      if (!deps->readonly)
 		{
@@ -3077,13 +3109,16 @@ sched_analyze_insn (struct deps_desc *de
 	  EXECUTE_IF_SET_IN_REG_SET (reg_pending_sets, 0, i, rsi)
 	    {
 	      struct deps_reg *reg_last = &deps->reg_last[i];
-	      add_dependence_list (insn, reg_last->sets, 0, REG_DEP_OUTPUT);
+	      add_dependence_list (insn, reg_last->sets, 0, REG_DEP_OUTPUT,
+				   false);
 	      add_dependence_list (insn, reg_last->implicit_sets, 0,
-				   REG_DEP_ANTI);
-	      add_dependence_list (insn, reg_last->clobbers, 0, REG_DEP_OUTPUT);
-	      add_dependence_list (insn, reg_last->uses, 0, REG_DEP_ANTI);
+				   REG_DEP_ANTI, false);
+	      add_dependence_list (insn, reg_last->clobbers, 0, REG_DEP_OUTPUT,
+				   false);
+	      add_dependence_list (insn, reg_last->uses, 0, REG_DEP_ANTI,
+				   false);
 	      add_dependence_list (insn, reg_last->control_uses, 0,
-				   REG_DEP_CONTROL);
+				   REG_DEP_CONTROL, false);
 
 	      if (!deps->readonly)
 		reg_last->sets = alloc_INSN_LIST (insn, reg_last->sets);
@@ -3098,17 +3133,18 @@ sched_analyze_insn (struct deps_desc *de
 		  || reg_last->clobbers_length > MAX_PENDING_LIST_LENGTH)
 		{
 		  add_dependence_list_and_free (deps, insn, &reg_last->sets, 0,
-						REG_DEP_OUTPUT);
+						REG_DEP_OUTPUT, false);
 		  add_dependence_list_and_free (deps, insn,
 						&reg_last->implicit_sets, 0,
-						REG_DEP_ANTI);
+						REG_DEP_ANTI, false);
 		  add_dependence_list_and_free (deps, insn, &reg_last->uses, 0,
-						REG_DEP_ANTI);
+						REG_DEP_ANTI, false);
 		  add_dependence_list_and_free (deps, insn,
 						&reg_last->control_uses, 0,
-						REG_DEP_ANTI);
-		  add_dependence_list_and_free
-		    (deps, insn, &reg_last->clobbers, 0, REG_DEP_OUTPUT);
+						REG_DEP_ANTI, false);
+		  add_dependence_list_and_free (deps, insn,
+						&reg_last->clobbers, 0,
+						REG_DEP_OUTPUT, false);
 
 		  if (!deps->readonly)
 		    {
@@ -3119,12 +3155,14 @@ sched_analyze_insn (struct deps_desc *de
 		}
 	      else
 		{
-		  add_dependence_list (insn, reg_last->sets, 0, REG_DEP_OUTPUT);
+		  add_dependence_list (insn, reg_last->sets, 0, REG_DEP_OUTPUT,
+				       false);
 		  add_dependence_list (insn, reg_last->implicit_sets, 0,
-				       REG_DEP_ANTI);
-		  add_dependence_list (insn, reg_last->uses, 0, REG_DEP_ANTI);
+				       REG_DEP_ANTI, false);
+		  add_dependence_list (insn, reg_last->uses, 0, REG_DEP_ANTI,
+				       false);
 		  add_dependence_list (insn, reg_last->control_uses, 0,
-				       REG_DEP_CONTROL);
+				       REG_DEP_CONTROL, false);
 		}
 
 	      if (!deps->readonly)
@@ -3139,16 +3177,16 @@ sched_analyze_insn (struct deps_desc *de
 	      struct deps_reg *reg_last = &deps->reg_last[i];
 
 	      add_dependence_list_and_free (deps, insn, &reg_last->sets, 0,
-					    REG_DEP_OUTPUT);
+					    REG_DEP_OUTPUT, false);
 	      add_dependence_list_and_free (deps, insn,
 					    &reg_last->implicit_sets,
-					    0, REG_DEP_ANTI);
+					    0, REG_DEP_ANTI, false);
 	      add_dependence_list_and_free (deps, insn, &reg_last->clobbers, 0,
-					    REG_DEP_OUTPUT);
+					    REG_DEP_OUTPUT, false);
 	      add_dependence_list_and_free (deps, insn, &reg_last->uses, 0,
-					    REG_DEP_ANTI);
+					    REG_DEP_ANTI, false);
 	      add_dependence_list (insn, reg_last->control_uses, 0,
-				   REG_DEP_CONTROL);
+				   REG_DEP_CONTROL, false);
 
 	      if (!deps->readonly)
 		{
@@ -3173,10 +3211,11 @@ sched_analyze_insn (struct deps_desc *de
     if (TEST_HARD_REG_BIT (implicit_reg_pending_clobbers, i))
       {
 	struct deps_reg *reg_last = &deps->reg_last[i];
-	add_dependence_list (insn, reg_last->sets, 0, REG_DEP_ANTI);
-	add_dependence_list (insn, reg_last->clobbers, 0, REG_DEP_ANTI);
-	add_dependence_list (insn, reg_last->uses, 0, REG_DEP_ANTI);
-	add_dependence_list (insn, reg_last->control_uses, 0, REG_DEP_ANTI);
+	add_dependence_list (insn, reg_last->sets, 0, REG_DEP_ANTI, false);
+	add_dependence_list (insn, reg_last->clobbers, 0, REG_DEP_ANTI, false);
+	add_dependence_list (insn, reg_last->uses, 0, REG_DEP_ANTI, false);
+	add_dependence_list (insn, reg_last->control_uses, 0, REG_DEP_ANTI,
+			     false);
 
 	if (!deps->readonly)
 	  reg_last->implicit_sets
@@ -3214,15 +3253,16 @@ sched_analyze_insn (struct deps_desc *de
 	  EXECUTE_IF_SET_IN_REG_SET (&deps->reg_last_in_use, 0, i, rsi)
 	    {
 	      struct deps_reg *reg_last = &deps->reg_last[i];
-	      add_dependence_list (insn, reg_last->uses, 0, REG_DEP_ANTI);
+	      add_dependence_list (insn, reg_last->uses, 0, REG_DEP_ANTI,
+				   true);
 	      add_dependence_list (insn, reg_last->sets, 0,
 				   reg_pending_barrier == TRUE_BARRIER
-				   ? REG_DEP_TRUE : REG_DEP_ANTI);
+				   ? REG_DEP_TRUE : REG_DEP_ANTI, true);
 	      add_dependence_list (insn, reg_last->implicit_sets, 0,
-				   REG_DEP_ANTI);
+				   REG_DEP_ANTI, true);
 	      add_dependence_list (insn, reg_last->clobbers, 0,
 				   reg_pending_barrier == TRUE_BARRIER
-				   ? REG_DEP_TRUE : REG_DEP_ANTI);
+				   ? REG_DEP_TRUE : REG_DEP_ANTI, true);
 	    }
 	}
       else
@@ -3231,19 +3271,21 @@ sched_analyze_insn (struct deps_desc *de
 	    {
 	      struct deps_reg *reg_last = &deps->reg_last[i];
 	      add_dependence_list_and_free (deps, insn, &reg_last->uses, 0,
-					    REG_DEP_ANTI);
+					    REG_DEP_ANTI, true);
 	      add_dependence_list_and_free (deps, insn,
 					    &reg_last->control_uses, 0,
-					    REG_DEP_CONTROL);
+					    REG_DEP_CONTROL, true);
 	      add_dependence_list_and_free (deps, insn, &reg_last->sets, 0,
 					    reg_pending_barrier == TRUE_BARRIER
-					    ? REG_DEP_TRUE : REG_DEP_ANTI);
+					    ? REG_DEP_TRUE : REG_DEP_ANTI,
+					    true);
 	      add_dependence_list_and_free (deps, insn,
 					    &reg_last->implicit_sets, 0,
-					    REG_DEP_ANTI);
+					    REG_DEP_ANTI, true);
 	      add_dependence_list_and_free (deps, insn, &reg_last->clobbers, 0,
 					    reg_pending_barrier == TRUE_BARRIER
-					    ? REG_DEP_TRUE : REG_DEP_ANTI);
+					    ? REG_DEP_TRUE : REG_DEP_ANTI,
+					    true);
 
               if (!deps->readonly)
                 {
@@ -3526,7 +3568,7 @@ deps_analyze_insn (struct deps_desc *dep
       /* For each insn which shouldn't cross a jump, add a dependence.  */
       add_dependence_list_and_free (deps, insn,
 				    &deps->sched_before_next_jump, 1,
-				    REG_DEP_ANTI);
+				    REG_DEP_ANTI, true);
 
       sched_analyze_insn (deps, PATTERN (insn), insn);
     }
@@ -3582,7 +3624,7 @@ deps_analyze_insn (struct deps_desc *dep
          between that insn and this call insn.  */
       add_dependence_list_and_free (deps, insn,
                                     &deps->sched_before_next_call, 1,
-                                    REG_DEP_ANTI);
+                                    REG_DEP_ANTI, true);
 
       sched_analyze_insn (deps, PATTERN (insn), insn);
 
@@ -4476,4 +4518,305 @@ check_dep (dep_t dep, bool relaxed_p)
 }
 #endif /* ENABLE_CHECKING */
 
+/* Holds information about a pair of memory reference and register increment
+   insns which depend on each other, but could possibly be interchanged.  */
+struct mem_inc_info
+{
+  rtx inc_insn;
+  rtx mem_insn;
+
+  rtx *mem_loc;
+  /* A register occurring in the memory address for which we wish to break
+     the dependence.  This must be identical to the destination register of
+     the increment.  */
+  rtx mem_reg0;
+  /* Any kind of index that is added to that register.  */
+  rtx mem_index;
+  /* The constant offset used in the memory address.  */
+  HOST_WIDE_INT mem_constant;
+  /* The constant added in the increment insn.  Negated if the increment is
+     after the memory address.  */
+  HOST_WIDE_INT inc_constant;
+  /* The source register used in the increment.  May be different from mem_reg0
+     if the increment occurs before the memory address.  */
+  rtx inc_input;
+};
+
+/* Verify that the memory location described in MII can be replaced with
+   one using NEW_ADDR.  Return the new memory reference or NULL_RTX.  The
+   insn remains unchanged by this function.  */
+
+static rtx
+attempt_change (struct mem_inc_info *mii, rtx new_addr)
+{
+  rtx mem = *mii->mem_loc;
+  rtx new_mem;
+
+  /* Jump thru a lot of hoops to keep the attributes up to date.  We
+     do not want to call one of the change address variants that take
+     an offset even though we know the offset in many cases.  These
+     assume you are changing where the address is pointing by the
+     offset.  */
+  new_mem = replace_equiv_address_nv (mem, new_addr);
+  if (! validate_change (mii->mem_insn, mii->mem_loc, new_mem, 0))
+    {
+      if (sched_verbose >= 5)
+	fprintf (sched_dump, "validation failure\n");
+      return NULL_RTX;
+    }
+
+  /* Put back the old one.  */
+  validate_change (mii->mem_insn, mii->mem_loc, mem, 0);
+
+  return new_mem;
+}
+
+/* Return true if INSN is of a form "a = b op c" where a and b are
+   regs.  op is + if c is a reg and +|- if c is a const.  Fill in
+   informantion in MII about what is found.
+   BEFORE_MEM indicates whether the increment is found before or after
+   a corresponding memory reference.  */
+
+static bool
+parse_add_or_inc (struct mem_inc_info *mii, rtx insn, bool before_mem)
+{
+  rtx pat = single_set (insn);
+  rtx src, cst;
+  bool regs_equal;
+
+  if (RTX_FRAME_RELATED_P (insn) || !pat)
+    return false;
+
+  /* Result must be single reg.  */
+  if (!REG_P (SET_DEST (pat)))
+    return false;
+
+  if (GET_CODE (SET_SRC (pat)) != PLUS
+      && GET_CODE (SET_SRC (pat)) != MINUS)
+    return false;
+
+  mii->inc_insn = insn;
+  src = SET_SRC (pat);
+  mii->inc_input = XEXP (src, 0);
+
+  if (!REG_P (XEXP (src, 0)))
+    return false;
+
+  if (!rtx_equal_p (SET_DEST (pat), mii->mem_reg0))
+    return false;
+
+  cst = XEXP (src, 1);
+  if (!CONST_INT_P (cst))
+    return false;
+  mii->inc_constant = INTVAL (cst);
+
+  regs_equal = rtx_equal_p (mii->inc_input, mii->mem_reg0);
+
+  if (!before_mem)
+    {
+      mii->inc_constant = -mii->inc_constant;
+      if (!regs_equal)
+	return false;
+    }
+
+  if (regs_equal && REGNO (SET_DEST (pat)) == STACK_POINTER_REGNUM)
+    /* Note that the sign has already been reversed for !before_mem.  */
+    return mii->inc_constant > 0;
+
+  return true;
+}
+
+/* Once a suitable mem reference has been found and the corresponding data
+   in MII has been filled in, this function is called to find a suitable
+   add or inc insn involving the register we found in the memory
+   reference.  */
+
+static bool
+find_inc (struct mem_inc_info *mii, bool backwards)
+{
+  sd_iterator_def sd_it;
+  dep_t dep;
+
+  sd_it = sd_iterator_start (mii->mem_insn,
+			     backwards ? SD_LIST_HARD_BACK : SD_LIST_FORW);
+  while (sd_iterator_cond (&sd_it, &dep))
+    {
+      dep_node_t node = DEP_LINK_NODE (*sd_it.linkp);
+      rtx pro = DEP_PRO (dep);
+      rtx con = DEP_CON (dep);
+      rtx inc_cand = backwards ? pro : con;
+      if (DEP_NONREG (dep) || DEP_MULTIPLE (dep))
+	goto next;
+      if (parse_add_or_inc (mii, inc_cand, backwards))
+	{
+	  struct dep_replacement *desc;
+	  df_ref *def_rec;
+	  rtx newaddr, newmem;
+
+	  if (sched_verbose >= 5)
+	    fprintf (sched_dump, "candidate mem/inc pair: %d %d\n",
+		     INSN_UID (mii->mem_insn), INSN_UID (inc_cand));
+
+	  /* Need to assure that none of the operands of the inc
+	     instruction are assigned to by the mem insn.  */
+	  for (def_rec = DF_INSN_DEFS (mii->mem_insn); *def_rec; def_rec++)
+	    {
+	      df_ref def = *def_rec;
+	      if (reg_overlap_mentioned_p (DF_REF_REG (def), mii->inc_input)
+		  || reg_overlap_mentioned_p (DF_REF_REG (def), mii->mem_reg0))
+		{
+		  if (sched_verbose >= 5)
+		    fprintf (sched_dump,
+			     "inc conflicts with store failure.\n");
+		  goto next;
+		}
+	    }
+	  newaddr = mii->inc_input;
+	  if (mii->mem_index != NULL_RTX)
+	    newaddr = gen_rtx_PLUS (GET_MODE (newaddr), newaddr,
+				    mii->mem_index);
+	  newaddr = plus_constant (GET_MODE (newaddr), newaddr,
+				   mii->mem_constant + mii->inc_constant);
+	  newmem = attempt_change (mii, newaddr);
+	  if (newmem == NULL_RTX)
+	    goto next;
+	  if (sched_verbose >= 5)
+	    fprintf (sched_dump, "successful address replacement\n");
+	  desc = XCNEW (struct dep_replacement);
+	  DEP_REPLACE (dep) = desc;
+	  desc->loc = mii->mem_loc;
+	  desc->newval = newmem;
+	  desc->orig = *desc->loc;
+	  desc->insn = mii->mem_insn;
+	  move_dep_link (DEP_NODE_BACK (node), INSN_HARD_BACK_DEPS (con),
+			 INSN_SPEC_BACK_DEPS (con));
+	  if (backwards)
+	    {
+	      FOR_EACH_DEP (mii->inc_insn, SD_LIST_BACK, sd_it, dep)
+		if (modified_in_p (mii->inc_input, DEP_PRO (dep)))
+		  add_dependence_1 (mii->mem_insn, DEP_PRO (dep),
+				    REG_DEP_TRUE);
+	    }
+	  else
+	    {
+	      FOR_EACH_DEP (mii->inc_insn, SD_LIST_FORW, sd_it, dep)
+		if (modified_in_p (mii->inc_input, DEP_CON (dep)))
+		  add_dependence_1 (DEP_CON (dep), mii->mem_insn,
+				    REG_DEP_ANTI);
+	    }
+	  return true;
+	}
+    next:
+      sd_iterator_next (&sd_it);
+    }
+  return false;
+}
+
+/* A recursive function that walks ADDRESS_OF_X to find memory references
+   which could be modified during scheduling.  We call find_inc for each
+   one we find that has a recognizable form.  MII holds information about
+   the pair of memory/increment instructions.
+   We ensure that every instruction with a memory reference (which will be
+   the location of the replacement) is assigned at most one breakable
+   dependency.  */
+
+static bool
+find_mem (struct mem_inc_info *mii, rtx *address_of_x)
+{
+  rtx x = *address_of_x;
+  enum rtx_code code = GET_CODE (x);
+  const char *const fmt = GET_RTX_FORMAT (code);
+  int i;
+
+  if (code == MEM)
+    {
+      rtx reg0 = XEXP (x, 0);
+
+      mii->mem_loc = address_of_x;
+      mii->mem_index = NULL_RTX;
+      mii->mem_constant = 0;
+      if (GET_CODE (reg0) == PLUS && CONST_INT_P (XEXP (reg0, 1)))
+	{
+	  mii->mem_constant = INTVAL (XEXP (reg0, 1));
+	  reg0 = XEXP (reg0, 0);
+	}
+      if (GET_CODE (reg0) == PLUS)
+	{
+	  mii->mem_index = XEXP (reg0, 1);
+	  reg0 = XEXP (reg0, 0);
+	}
+      if (REG_P (reg0))
+	{
+	  df_ref *def_rec;
+	  int occurrences = 0;
+
+	  /* Make sure this reg appears only once in this insn.  Can't use
+	     count_occurrences since that only works for pseudos.  */
+	  for (def_rec = DF_INSN_USES (mii->mem_insn); *def_rec; def_rec++)
+	    {
+	      df_ref def = *def_rec;
+	      if (reg_overlap_mentioned_p (reg0, DF_REF_REG (def)))
+		if (++occurrences > 1)
+		  {
+		    if (sched_verbose >= 5)
+		      fprintf (sched_dump, "mem count failure\n");
+		    return false;
+		  }
+	    }
+
+	  mii->mem_reg0 = reg0;
+	  return find_inc (mii, true) || find_inc (mii, false);
+	}
+      return false;
+    }
+
+  if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
+    {
+      /* If REG occurs inside a MEM used in a bit-field reference,
+	 that is unacceptable.  */
+      return false;
+    }
+
+  /* Time for some deep diving.  */
+  for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
+    {
+      if (fmt[i] == 'e')
+	{
+	  if (find_mem (mii, &XEXP (x, i)))
+	    return true;
+	}
+      else if (fmt[i] == 'E')
+	{
+	  int j;
+	  for (j = XVECLEN (x, i) - 1; j >= 0; j--)
+	    if (find_mem (mii, &XVECEXP (x, i, j)))
+	      return true;
+	}
+    }
+  return false;
+}
+
+
+/* Examine the instructions between HEAD and TAIL and try to find
+   dependencies that can be broken by modifying one of the patterns.  */
+
+void
+find_modifiable_mems (rtx head, rtx tail)
+{
+  rtx insn;
+  int success_in_block = 0;
+
+  for (insn = head; insn != tail; insn = NEXT_INSN (insn))
+    {
+      struct mem_inc_info mii;
+
+      if (!NONDEBUG_INSN_P (insn) || RTX_FRAME_RELATED_P (insn))
+	continue;
+
+      mii.mem_insn = insn;
+      if (find_mem (&mii, &PATTERN (insn)))
+	success_in_block++;
+    }
+}
+
 #endif /* INSN_SCHEDULING */
Index: gcc/sched-int.h
===================================================================
--- gcc/sched-int.h	(revision 189284)
+++ gcc/sched-int.h	(working copy)
@@ -206,6 +206,18 @@ typedef int dw_t;
 extern enum reg_note ds_to_dk (ds_t);
 extern ds_t dk_to_ds (enum reg_note);
 
+/* Describe a dependency that can be broken by making a replacement
+   in one of the patterns.  LOC is the location, ORIG and NEWVAL the
+   two alternative contents, and INSN the instruction that must be
+   changed.  */
+struct dep_replacement
+{
+  rtx *loc;
+  rtx orig;
+  rtx newval;
+  rtx insn;
+};
+
 /* Information about the dependency.  */
 struct _dep
 {
@@ -215,18 +227,30 @@ struct _dep
   /* Consumer.  */
   rtx con;
 
-  /* Dependency major type.  This field is superseded by STATUS below.
-     Though, it is still in place because some targets use it.  */
-  enum reg_note type;
+  /* If nonnull, holds a pointer to information about how to break the
+     dependency by making a replacement in one of the insns.  There is
+     only one such dependency for each insn that must be modified in
+     order to break such a dependency.  */
+  struct dep_replacement *replace;
 
   /* Dependency status.  This field holds all dependency types and additional
      information for speculative dependencies.  */
   ds_t status;
 
-  /* Cached cost of the dependency.  */
-  int cost;
+  /* Dependency major type.  This field is superseded by STATUS below.
+     Though, it is still in place because some targets use it.  */
+  ENUM_BITFIELD(reg_note) type:6;
+
+  unsigned nonreg:1;
+  unsigned multiple:1;
+
+  /* Cached cost of the dependency.  Make sure to update UNKNOWN_DEP_COST
+     when changing the size of this field.  */
+  int cost:20;
 };
 
+#define UNKNOWN_DEP_COST (-1<<19)
+
 typedef struct _dep dep_def;
 typedef dep_def *dep_t;
 
@@ -235,8 +259,9 @@ typedef dep_def *dep_t;
 #define DEP_TYPE(D) ((D)->type)
 #define DEP_STATUS(D) ((D)->status)
 #define DEP_COST(D) ((D)->cost)
-
-#define UNKNOWN_DEP_COST INT_MIN
+#define DEP_NONREG(D) ((D)->nonreg)
+#define DEP_MULTIPLE(D) ((D)->multiple)
+#define DEP_REPLACE(D) ((D)->replace)
 
 /* Functions to work with dep.  */
 
@@ -1047,7 +1072,11 @@ enum SPEC_TYPES_OFFSETS {
    Therefore, it can appear only in TODO_SPEC field of an instruction.  */
 #define HARD_DEP (DEP_CONTROL << 1)
 
-#define DEP_CANCELLED (HARD_DEP << 1)
+/* Set in the TODO_SPEC field of an instruction for which new_ready
+   has decided not to schedule it speculatively.  */
+#define DEP_POSTPONED (HARD_DEP << 1)
+
+#define DEP_CANCELLED (DEP_POSTPONED << 1)
 
 /* This represents the results of calling sched-deps.c functions,
    which modify dependencies.  */
@@ -1074,7 +1103,8 @@ enum SCHED_FLAGS {
   DO_SPECULATION = USE_DEPS_LIST << 1,
   DO_BACKTRACKING = DO_SPECULATION << 1,
   DO_PREDICATION = DO_BACKTRACKING << 1,
-  SCHED_RGN = DO_PREDICATION << 1,
+  DONT_BREAK_DEPENDENCIES = DO_PREDICATION << 1,
+  SCHED_RGN = DONT_BREAK_DEPENDENCIES << 1,
   SCHED_EBB = SCHED_RGN << 1,
   /* Scheduler can possibly create new basic blocks.  Used for assertions.  */
   NEW_BBS = SCHED_EBB << 1,
@@ -1406,6 +1436,8 @@ extern void dump_region_dot_file (const
 extern void haifa_sched_init (void);
 extern void haifa_sched_finish (void);
 
+extern void find_modifiable_mems (rtx, rtx);
+
 /* sched-deps.c interface to walk, add, search, update, resolve, delete
    and debug instruction dependencies.  */
 
Index: gcc/Makefile.in
===================================================================
--- gcc/Makefile.in	(revision 189284)
+++ gcc/Makefile.in	(working copy)
@@ -3263,7 +3263,7 @@ haifa-sched.o : haifa-sched.c $(CONFIG_H
 sched-deps.o : sched-deps.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) \
    $(RTL_H) $(SCHED_INT_H) $(REGS_H) hard-reg-set.h $(FLAGS_H) insn-config.h \
    $(FUNCTION_H) $(INSN_ATTR_H) $(DIAGNOSTIC_CORE_H) $(RECOG_H) $(EXCEPT_H) cselib.h \
-   ira.h $(PARAMS_H) $(TM_P_H) ira.h $(TARGET_H)
+   ira.h $(PARAMS_H) $(TM_P_H) ira.h $(TARGET_H) $(EMIT_RTL_H)
 sched-rgn.o : sched-rgn.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) \
    $(RTL_H) $(SCHED_INT_H) $(REGS_H) hard-reg-set.h $(FLAGS_H) insn-config.h \
    $(FUNCTION_H) $(INSN_ATTR_H) $(DIAGNOSTIC_CORE_H) $(RECOG_H) $(EXCEPT_H) $(PARAMS_H) \
Index: gcc/sched-rgn.c
===================================================================
--- gcc/sched-rgn.c	(revision 189284)
+++ gcc/sched-rgn.c	(working copy)
@@ -2103,6 +2103,8 @@ init_ready_list (void)
      Count number of insns in the target block being scheduled.  */
   for (insn = NEXT_INSN (prev_head); insn != next_tail; insn = NEXT_INSN (insn))
     {
+      gcc_assert (TODO_SPEC (insn) == HARD_DEP || TODO_SPEC (insn) == DEP_POSTPONED);
+      TODO_SPEC (insn) = HARD_DEP;
       try_ready (insn);
       target_n_insns++;
 
@@ -2126,7 +2128,11 @@ init_ready_list (void)
 
 	for (insn = src_head; insn != src_next_tail; insn = NEXT_INSN (insn))
 	  if (INSN_P (insn))
-	    try_ready (insn);
+	    {
+	      gcc_assert (TODO_SPEC (insn) == HARD_DEP || TODO_SPEC (insn) == DEP_POSTPONED);
+	      TODO_SPEC (insn) = HARD_DEP;
+	      try_ready (insn);
+	    }
       }
 }
 
@@ -2218,11 +2224,11 @@ new_ready (rtx next, ds_t ts)
 		ts = new_ds;
 	      else
 		/* NEXT isn't ready yet.  */
-		ts = (ts & ~SPECULATIVE) | HARD_DEP;
+		ts = DEP_POSTPONED;
 	    }
 	  else
 	    /* NEXT isn't ready yet.  */
-            ts = (ts & ~SPECULATIVE) | HARD_DEP;
+            ts = DEP_POSTPONED;
 	}
     }
 
@@ -2826,7 +2832,9 @@ void debug_dependencies (rtx head, rtx t
 	dep_t dep;
 
 	FOR_EACH_DEP (insn, SD_LIST_FORW, sd_it, dep)
-	  fprintf (sched_dump, "%d ", INSN_UID (DEP_CON (dep)));
+	  fprintf (sched_dump, "%d%s%s ", INSN_UID (DEP_CON (dep)),
+		   DEP_NONREG (dep) ? "n" : "",
+		   DEP_MULTIPLE (dep) ? "m" : "");
       }
       fprintf (sched_dump, "\n");
     }
Index: gcc/config/c6x/c6x.c
===================================================================
--- gcc/config/c6x/c6x.c	(revision 189284)
+++ gcc/config/c6x/c6x.c	(working copy)
@@ -3911,6 +3911,13 @@ c6x_free_sched_context (void *_sc)
   free (_sc);
 }
 
+/* True if we are currently performing a preliminary scheduling
+   pass before modulo scheduling; we can't allow the scheduler to
+   modify instruction patterns using packetization assumptions,
+   since there will be another scheduling pass later if modulo
+   scheduling fails.  */
+static bool in_hwloop;
+
 /* Provide information about speculation capabilities, and set the
    DO_BACKTRACKING flag.  */
 static void
@@ -3922,6 +3929,8 @@ c6x_set_sched_flags (spec_info_t spec_in
     {
       *flags |= DO_BACKTRACKING | DO_PREDICATION;
     }
+  if (in_hwloop)
+    *flags |= DONT_BREAK_DEPENDENCIES;
 
   spec_info->mask = 0;
 }
@@ -5535,9 +5544,11 @@ hwloop_optimize (hwloop_info loop)
 
   reshuffle_units (loop->head);
 
+  in_hwloop = true;
   schedule_ebbs_init ();
   schedule_ebb (BB_HEAD (loop->tail), loop->loop_end, true);
   schedule_ebbs_finish ();
+  in_hwloop = false;
 
   bb = loop->head;
   loop_earliest = bb_earliest_end_cycle (bb, loop->loop_end) + 1;
