Merge from trunk revision 104c05c5284b7822d770ee51a7d91946c7e56d50.

1 files changed, 296 insertions, 295 deletions

diff --git a/gcc/tree-ssa-threadedge.c b/gcc/tree-ssa-threadedge.c
index 5e152e7..2b9a4c3 100644
--- a/gcc/tree-ssa-threadedge.c
+++ b/gcc/tree-ssa-threadedge.c
@@ -49,10 +49,6 @@ static int stmt_count;
 /* Array to record value-handles per SSA_NAME.  */
 vec<tree> ssa_name_values;
 
-typedef tree (pfn_simplify) (gimple *, gimple *,
-			     class avail_exprs_stack *,
-			     basic_block);
-
 /* Set the value for the SSA name NAME to VALUE.  */
 
 void
@@ -65,25 +61,58 @@ set_ssa_name_value (tree name, tree value)
   ssa_name_values[SSA_NAME_VERSION (name)] = value;
 }
 
-/* Initialize the per SSA_NAME value-handles array.  Returns it.  */
-void
-threadedge_initialize_values (void)
+jump_threader::jump_threader (jump_threader_simplifier *simplifier,
+			      jt_state *state)
 {
+  /* Initialize the per SSA_NAME value-handles array.  */
   gcc_assert (!ssa_name_values.exists ());
   ssa_name_values.create (num_ssa_names);
+
+  dummy_cond = gimple_build_cond (NE_EXPR, integer_zero_node,
+				  integer_zero_node, NULL, NULL);
+
+  m_registry = new fwd_jt_path_registry ();
+  m_simplifier = simplifier;
+  m_state = state;
 }
 
-/* Free the per SSA_NAME value-handle array.  */
-void
-threadedge_finalize_values (void)
+jump_threader::~jump_threader (void)
 {
   ssa_name_values.release ();
+  ggc_free (dummy_cond);
+  delete m_registry;
+}
+
+void
+jump_threader::remove_jump_threads_including (edge_def *e)
+{
+  m_registry->remove_jump_threads_including (e);
+}
+
+bool
+jump_threader::thread_through_all_blocks (bool may_peel_loop_headers)
+{
+  return m_registry->thread_through_all_blocks (may_peel_loop_headers);
+}
+
+static inline bool
+has_phis_p (basic_block bb)
+{
+  return !gsi_end_p (gsi_start_phis (bb));
+}
+
+/* Return TRUE for a block with PHIs but no statements.  */
+
+static bool
+empty_block_with_phis_p (basic_block bb)
+{
+  return gsi_end_p (gsi_start_nondebug_bb (bb)) && has_phis_p (bb);
 }
 
 /* Return TRUE if we may be able to thread an incoming edge into
    BB to an outgoing edge from BB.  Return FALSE otherwise.  */
 
-bool
+static bool
 potentially_threadable_block (basic_block bb)
 {
   gimple_stmt_iterator gsi;
@@ -92,9 +121,8 @@ potentially_threadable_block (basic_block bb)
      not optimized away because they forward from outside a loop
      to the loop header.   We want to thread through them as we can
      sometimes thread to the loop exit, which is obviously profitable.
-     the interesting case here is when the block has PHIs.  */
-  if (gsi_end_p (gsi_start_nondebug_bb (bb))
-      && !gsi_end_p (gsi_start_phis (bb)))
+     The interesting case here is when the block has PHIs.  */
+  if (empty_block_with_phis_p (bb))
     return true;
 
   /* If BB has a single successor or a single predecessor, then
@@ -116,16 +144,13 @@ potentially_threadable_block (basic_block bb)
 }
 
 /* Record temporary equivalences created by PHIs at the target of the
-   edge E.  Record unwind information for the equivalences into
-   CONST_AND_COPIES and EVRP_RANGE_DATA.
+   edge E.
 
    If a PHI which prevents threading is encountered, then return FALSE
    indicating we should not thread this edge, else return TRUE.  */
 
-static bool
-record_temporary_equivalences_from_phis (edge e,
-    const_and_copies *const_and_copies,
-    evrp_range_analyzer *evrp_range_analyzer)
+bool
+jump_threader::record_temporary_equivalences_from_phis (edge e)
 {
   gphi_iterator gsi;
 
@@ -152,41 +177,7 @@ record_temporary_equivalences_from_phis (edge e,
       if (!virtual_operand_p (dst))
 	stmt_count++;
 
-      const_and_copies->record_const_or_copy (dst, src);
-
-      /* Also update the value range associated with DST, using
-	 the range from SRC.
-
-	 Note that even if SRC is a constant we need to set a suitable
-	 output range so that VR_UNDEFINED ranges do not leak through.  */
-      if (evrp_range_analyzer)
-	{
-	  /* Get an empty new VR we can pass to update_value_range and save
-	     away in the VR stack.  */
-	  value_range_equiv *new_vr
-			  = evrp_range_analyzer->allocate_value_range_equiv ();
-	  new (new_vr) value_range_equiv ();
-
-	  /* There are three cases to consider:
-
-	       First if SRC is an SSA_NAME, then we can copy the value
-	       range from SRC into NEW_VR.
-
-	       Second if SRC is an INTEGER_CST, then we can just wet
-	       NEW_VR to a singleton range.
-
-	       Otherwise set NEW_VR to varying.  This may be overly
-	       conservative.  */
-	  if (TREE_CODE (src) == SSA_NAME)
-	    new_vr->deep_copy (evrp_range_analyzer->get_value_range (src));
-	  else if (TREE_CODE (src) == INTEGER_CST)
-	    new_vr->set (src);
-	  else
-	    new_vr->set_varying (TREE_TYPE (src));
-
-	  /* This is a temporary range for DST, so push it.  */
-	  evrp_range_analyzer->push_value_range (dst, new_vr);
-	}
+      m_state->register_equiv (dst, src, /*update_range=*/true);
     }
   return true;
 }
@@ -210,8 +201,8 @@ threadedge_valueize (tree t)
 
    Record unwind information for temporary equivalences onto STACK.
 
-   Use SIMPLIFY (a pointer to a callback function) to further simplify
-   statements using pass specific information.
+   Uses M_SIMPLIFIER to further simplify statements using pass specific
+   information.
 
    We might consider marking just those statements which ultimately
    feed the COND_EXPR.  It's not clear if the overhead of bookkeeping
@@ -222,12 +213,8 @@ threadedge_valueize (tree t)
    a context sensitive equivalence which may help us simplify
    later statements in E->dest.  */
 
-static gimple *
-record_temporary_equivalences_from_stmts_at_dest (edge e,
-    const_and_copies *const_and_copies,
-    avail_exprs_stack *avail_exprs_stack,
-    evrp_range_analyzer *evrp_range_analyzer,
-    pfn_simplify simplify)
+gimple *
+jump_threader::record_temporary_equivalences_from_stmts_at_dest (edge e)
 {
   gimple *stmt = NULL;
   gimple_stmt_iterator gsi;
@@ -292,10 +279,7 @@ record_temporary_equivalences_from_stmts_at_dest (edge e,
 	    return NULL;
 	}
 
-      /* These are temporary ranges, do nto reflect them back into
-	 the global range data.  */
-      if (evrp_range_analyzer)
-	evrp_range_analyzer->record_ranges_from_stmt (stmt, true);
+      m_state->record_ranges_from_stmt (stmt, true);
 
       /* If this is not a statement that sets an SSA_NAME to a new
 	 value, then do not try to simplify this statement as it will
@@ -396,7 +380,7 @@ record_temporary_equivalences_from_stmts_at_dest (edge e,
 		    SET_USE (use_p, tmp);
 		}
 
-	      cached_lhs = (*simplify) (stmt, stmt, avail_exprs_stack, e->src);
+	      cached_lhs = m_simplifier->simplify (stmt, stmt, e->src, m_state);
 
 	      /* Restore the statement's original uses/defs.  */
 	      i = 0;
@@ -410,38 +394,22 @@ record_temporary_equivalences_from_stmts_at_dest (edge e,
       if (cached_lhs
 	  && (TREE_CODE (cached_lhs) == SSA_NAME
 	      || is_gimple_min_invariant (cached_lhs)))
-	const_and_copies->record_const_or_copy (gimple_get_lhs (stmt),
-						cached_lhs);
+	m_state->register_equiv (gimple_get_lhs (stmt), cached_lhs);
     }
   return stmt;
 }
 
-static tree simplify_control_stmt_condition_1 (edge, gimple *,
-					       class avail_exprs_stack *,
-					       tree, enum tree_code, tree,
-					       gcond *, pfn_simplify,
-					       unsigned);
-
 /* Simplify the control statement at the end of the block E->dest.
 
-   To avoid allocating memory unnecessarily, a scratch GIMPLE_COND
-   is available to use/clobber in DUMMY_COND.
-
    Use SIMPLIFY (a pointer to a callback function) to further simplify
    a condition using pass specific information.
 
    Return the simplified condition or NULL if simplification could
    not be performed.  When simplifying a GIMPLE_SWITCH, we may return
-   the CASE_LABEL_EXPR that will be taken.
-
-   The available expression table is referenced via AVAIL_EXPRS_STACK.  */
+   the CASE_LABEL_EXPR that will be taken.  */
 
-static tree
-simplify_control_stmt_condition (edge e,
-				 gimple *stmt,
-				 class avail_exprs_stack *avail_exprs_stack,
-				 gcond *dummy_cond,
-				 pfn_simplify simplify)
+tree
+jump_threader::simplify_control_stmt_condition (edge e, gimple *stmt)
 {
   tree cond, cached_lhs;
   enum gimple_code code = gimple_code (stmt);
@@ -485,22 +453,20 @@ simplify_control_stmt_condition (edge e,
       const unsigned recursion_limit = 4;
 
       cached_lhs
-	= simplify_control_stmt_condition_1 (e, stmt, avail_exprs_stack,
-					     op0, cond_code, op1,
-					     dummy_cond, simplify,
+	= simplify_control_stmt_condition_1 (e, stmt, op0, cond_code, op1,
 					     recursion_limit);
 
-      /* If we were testing an integer/pointer against a constant, then
-	 we can use the FSM code to trace the value of the SSA_NAME.  If
-	 a value is found, then the condition will collapse to a constant.
+      /* If we were testing an integer/pointer against a constant,
+	 then we can trace the value of the SSA_NAME.  If a value is
+	 found, then the condition will collapse to a constant.
 
 	 Return the SSA_NAME we want to trace back rather than the full
-	 expression and give the FSM threader a chance to find its value.  */
+	 expression and give the threader a chance to find its value.  */
       if (cached_lhs == NULL)
 	{
 	  /* Recover the original operands.  They may have been simplified
 	     using context sensitive equivalences.  Those context sensitive
-	     equivalences may not be valid on paths found by the FSM optimizer.  */
+	     equivalences may not be valid on paths.  */
 	  tree op0 = gimple_cond_lhs (stmt);
 	  tree op1 = gimple_cond_rhs (stmt);
 
@@ -557,12 +523,12 @@ simplify_control_stmt_condition (edge e,
 		 the label that is proven to be taken.  */
 	      gswitch *dummy_switch = as_a<gswitch *> (gimple_copy (stmt));
 	      gimple_switch_set_index (dummy_switch, cached_lhs);
-	      cached_lhs = (*simplify) (dummy_switch, stmt,
-					avail_exprs_stack, e->src);
+	      cached_lhs = m_simplifier->simplify (dummy_switch, stmt, e->src,
+						   m_state);
 	      ggc_free (dummy_switch);
 	    }
 	  else
-	    cached_lhs = (*simplify) (stmt, stmt, avail_exprs_stack, e->src);
+	    cached_lhs = m_simplifier->simplify (stmt, stmt, e->src, m_state);
 	}
 
       /* We couldn't find an invariant.  But, callers of this
@@ -579,16 +545,14 @@ simplify_control_stmt_condition (edge e,
 
 /* Recursive helper for simplify_control_stmt_condition.  */
 
-static tree
-simplify_control_stmt_condition_1 (edge e,
-				   gimple *stmt,
-				   class avail_exprs_stack *avail_exprs_stack,
-				   tree op0,
-				   enum tree_code cond_code,
-				   tree op1,
-				   gcond *dummy_cond,
-				   pfn_simplify simplify,
-				   unsigned limit)
+tree
+jump_threader::simplify_control_stmt_condition_1
+					(edge e,
+					 gimple *stmt,
+					 tree op0,
+					 enum tree_code cond_code,
+					 tree op1,
+					 unsigned limit)
 {
   if (limit == 0)
     return NULL_TREE;
@@ -623,9 +587,8 @@ simplify_control_stmt_condition_1 (edge e,
 
 	  /* Is A != 0 ?  */
 	  const tree res1
-	    = simplify_control_stmt_condition_1 (e, def_stmt, avail_exprs_stack,
+	    = simplify_control_stmt_condition_1 (e, def_stmt,
 						 rhs1, NE_EXPR, op1,
-						 dummy_cond, simplify,
 						 limit - 1);
 	  if (res1 == NULL_TREE)
 	    ;
@@ -650,9 +613,8 @@ simplify_control_stmt_condition_1 (edge e,
 
 	  /* Is B != 0 ?  */
 	  const tree res2
-	    = simplify_control_stmt_condition_1 (e, def_stmt, avail_exprs_stack,
+	    = simplify_control_stmt_condition_1 (e, def_stmt,
 						 rhs2, NE_EXPR, op1,
-						 dummy_cond, simplify,
 						 limit - 1);
 	  if (res2 == NULL_TREE)
 	    ;
@@ -715,9 +677,8 @@ simplify_control_stmt_condition_1 (edge e,
 	    new_cond = invert_tree_comparison (new_cond, false);
 
 	  tree res
-	    = simplify_control_stmt_condition_1 (e, def_stmt, avail_exprs_stack,
+	    = simplify_control_stmt_condition_1 (e, def_stmt,
 						 rhs1, new_cond, rhs2,
-						 dummy_cond, simplify,
 						 limit - 1);
 	  if (res != NULL_TREE && is_gimple_min_invariant (res))
 	    return res;
@@ -744,7 +705,7 @@ simplify_control_stmt_condition_1 (edge e,
      then use the pass specific callback to simplify the condition.  */
   if (!res
       || !is_gimple_min_invariant (res))
-    res = (*simplify) (dummy_cond, stmt, avail_exprs_stack, e->src);
+    res = m_simplifier->simplify (dummy_cond, stmt, e->src, m_state);
 
   return res;
 }
@@ -891,20 +852,12 @@ propagate_threaded_block_debug_into (basic_block dest, basic_block src)
 
    If it is threadable, add it to PATH and VISITED and recurse, ultimately
    returning TRUE from the toplevel call.   Otherwise do nothing and
-   return false.
-
-   DUMMY_COND, SIMPLIFY are used to try and simplify the condition at the
-   end of TAKEN_EDGE->dest.
-
-   The available expression table is referenced via AVAIL_EXPRS_STACK.  */
+   return false.  */
 
-static bool
-thread_around_empty_blocks (edge taken_edge,
-			    gcond *dummy_cond,
-			    class avail_exprs_stack *avail_exprs_stack,
-			    pfn_simplify simplify,
-			    bitmap visited,
-			    vec<jump_thread_edge *> *path)
+bool
+jump_threader::thread_around_empty_blocks (vec<jump_thread_edge *> *path,
+					   edge taken_edge,
+					   bitmap visited)
 {
   basic_block bb = taken_edge->dest;
   gimple_stmt_iterator gsi;
@@ -914,7 +867,7 @@ thread_around_empty_blocks (edge taken_edge,
   /* The key property of these blocks is that they need not be duplicated
      when threading.  Thus they cannot have visible side effects such
      as PHI nodes.  */
-  if (!gsi_end_p (gsi_start_phis (bb)))
+  if (has_phis_p (bb))
     return false;
 
   /* Skip over DEBUG statements at the start of the block.  */
@@ -946,15 +899,11 @@ thread_around_empty_blocks (edge taken_edge,
 	  if (!bitmap_bit_p (visited, taken_edge->dest->index))
 	    {
 	      jump_thread_edge *x
-		= new jump_thread_edge (taken_edge, EDGE_NO_COPY_SRC_BLOCK);
+		= m_registry->allocate_thread_edge (taken_edge,
+						    EDGE_NO_COPY_SRC_BLOCK);
 	      path->safe_push (x);
 	      bitmap_set_bit (visited, taken_edge->dest->index);
-	      return thread_around_empty_blocks (taken_edge,
-						 dummy_cond,
-						 avail_exprs_stack,
-						 simplify,
-						 visited,
-						 path);
+	      return thread_around_empty_blocks (path, taken_edge, visited);
 	    }
 	}
 
@@ -971,9 +920,7 @@ thread_around_empty_blocks (edge taken_edge,
     return false;
 
   /* Extract and simplify the condition.  */
-  cond = simplify_control_stmt_condition (taken_edge, stmt,
-					  avail_exprs_stack, dummy_cond,
-					  simplify);
+  cond = simplify_control_stmt_condition (taken_edge, stmt);
 
   /* If the condition can be statically computed and we have not already
      visited the destination edge, then add the taken edge to our thread
@@ -996,15 +943,11 @@ thread_around_empty_blocks (edge taken_edge,
       bitmap_set_bit (visited, taken_edge->dest->index);
 
       jump_thread_edge *x
-	= new jump_thread_edge (taken_edge, EDGE_NO_COPY_SRC_BLOCK);
+	= m_registry->allocate_thread_edge (taken_edge,
+					    EDGE_NO_COPY_SRC_BLOCK);
       path->safe_push (x);
 
-      thread_around_empty_blocks (taken_edge,
-				  dummy_cond,
-				  avail_exprs_stack,
-				  simplify,
-				  visited,
-				  path);
+      thread_around_empty_blocks (path, taken_edge, visited);
       return true;
     }
 
@@ -1024,50 +967,27 @@ thread_around_empty_blocks (edge taken_edge,
    limited in that case to avoid short-circuiting the loop
    incorrectly.
 
-   DUMMY_COND is a shared cond_expr used by condition simplification as scratch,
-   to avoid allocating memory.
-
-   STACK is used to undo temporary equivalences created during the walk of
-   E->dest.
-
-   SIMPLIFY is a pass-specific function used to simplify statements.
-
-   Our caller is responsible for restoring the state of the expression
-   and const_and_copies stacks.
-
    Positive return value is success.  Zero return value is failure, but
    the block can still be duplicated as a joiner in a jump thread path,
    negative indicates the block should not be duplicated and thus is not
    suitable for a joiner in a jump threading path.  */
 
-static int
-thread_through_normal_block (edge e,
-			     gcond *dummy_cond,
-			     const_and_copies *const_and_copies,
-			     avail_exprs_stack *avail_exprs_stack,
-			     evrp_range_analyzer *evrp_range_analyzer,
-			     pfn_simplify simplify,
-			     vec<jump_thread_edge *> *path,
-			     bitmap visited)
+int
+jump_threader::thread_through_normal_block (vec<jump_thread_edge *> *path,
+					    edge e, bitmap visited)
 {
-  /* We want to record any equivalences created by traversing E.  */
-  record_temporary_equivalences (e, const_and_copies, avail_exprs_stack);
+  m_state->register_equivs_on_edge (e);
 
   /* PHIs create temporary equivalences.
      Note that if we found a PHI that made the block non-threadable, then
      we need to bubble that up to our caller in the same manner we do
      when we prematurely stop processing statements below.  */
-  if (!record_temporary_equivalences_from_phis (e, const_and_copies,
-					        evrp_range_analyzer))
+  if (!record_temporary_equivalences_from_phis (e))
     return -1;
 
   /* Now walk each statement recording any context sensitive
      temporary equivalences we can detect.  */
-  gimple *stmt
-    = record_temporary_equivalences_from_stmts_at_dest (e, const_and_copies,
-							avail_exprs_stack,
-							evrp_range_analyzer,
-							simplify);
+  gimple *stmt = record_temporary_equivalences_from_stmts_at_dest (e);
 
   /* There's two reasons STMT might be null, and distinguishing
      between them is important.
@@ -1087,8 +1007,7 @@ thread_through_normal_block (edge e,
     {
       /* First case.  The statement simply doesn't have any instructions, but
 	 does have PHIs.  */
-      if (gsi_end_p (gsi_start_nondebug_bb (e->dest))
-	  && !gsi_end_p (gsi_start_phis (e->dest)))
+      if (empty_block_with_phis_p (e->dest))
 	return 0;
 
       /* Second case.  */
@@ -1104,8 +1023,7 @@ thread_through_normal_block (edge e,
       tree cond;
 
       /* Extract and simplify the condition.  */
-      cond = simplify_control_stmt_condition (e, stmt, avail_exprs_stack,
-					      dummy_cond, simplify);
+      cond = simplify_control_stmt_condition (e, stmt);
 
       if (!cond)
 	return 0;
@@ -1135,12 +1053,13 @@ thread_through_normal_block (edge e,
 	  if (path->length () == 0)
 	    {
               jump_thread_edge *x
-	        = new jump_thread_edge (e, EDGE_START_JUMP_THREAD);
+		= m_registry->allocate_thread_edge (e, EDGE_START_JUMP_THREAD);
 	      path->safe_push (x);
 	    }
 
 	  jump_thread_edge *x
-	    = new jump_thread_edge (taken_edge, EDGE_COPY_SRC_BLOCK);
+	    = m_registry->allocate_thread_edge (taken_edge,
+						EDGE_COPY_SRC_BLOCK);
 	  path->safe_push (x);
 
 	  /* See if we can thread through DEST as well, this helps capture
@@ -1151,12 +1070,7 @@ thread_through_normal_block (edge e,
  	     visited.  This may be overly conservative.  */
 	  bitmap_set_bit (visited, dest->index);
 	  bitmap_set_bit (visited, e->dest->index);
-	  thread_around_empty_blocks (taken_edge,
-				      dummy_cond,
-				      avail_exprs_stack,
-				      simplify,
-				      visited,
-				      path);
+	  thread_around_empty_blocks (path, taken_edge, visited);
 	  return 1;
 	}
     }
@@ -1225,49 +1139,27 @@ edge_forwards_cmp_to_conditional_jump_through_empty_bb_p (edge e)
   return true;
 }
 
-/* We are exiting E->src, see if E->dest ends with a conditional
-   jump which has a known value when reached via E.
-
-   DUMMY_COND is a shared cond_expr used by condition simplification as scratch,
-   to avoid allocating memory.
-
-   CONST_AND_COPIES is used to undo temporary equivalences created during the
-   walk of E->dest.
+/* We are exiting E->src, see if E->dest ends with a conditional jump
+   which has a known value when reached via E.  If so, thread the
+   edge.  */
 
-   The available expression table is referenced vai AVAIL_EXPRS_STACK.
-
-   SIMPLIFY is a pass-specific function used to simplify statements.  */
-
-static void
-thread_across_edge (gcond *dummy_cond,
-		    edge e,
-		    class const_and_copies *const_and_copies,
-		    class avail_exprs_stack *avail_exprs_stack,
-		    class evrp_range_analyzer *evrp_range_analyzer,
-		    pfn_simplify simplify)
+void
+jump_threader::thread_across_edge (edge e)
 {
   bitmap visited = BITMAP_ALLOC (NULL);
 
-  const_and_copies->push_marker ();
-  avail_exprs_stack->push_marker ();
-  if (evrp_range_analyzer)
-    evrp_range_analyzer->push_marker ();
+  m_state->push (e);
 
   stmt_count = 0;
 
-  vec<jump_thread_edge *> *path = new vec<jump_thread_edge *> ();
+  vec<jump_thread_edge *> *path = m_registry->allocate_thread_path ();
   bitmap_clear (visited);
   bitmap_set_bit (visited, e->src->index);
   bitmap_set_bit (visited, e->dest->index);
 
   int threaded;
   if ((e->flags & EDGE_DFS_BACK) == 0)
-    threaded = thread_through_normal_block (e, dummy_cond,
-					    const_and_copies,
-					    avail_exprs_stack,
-					    evrp_range_analyzer,
-					    simplify, path,
-					    visited);
+    threaded = thread_through_normal_block (path, e, visited);
   else
     threaded = 0;
 
@@ -1275,12 +1167,9 @@ thread_across_edge (gcond *dummy_cond,
     {
       propagate_threaded_block_debug_into (path->last ()->e->dest,
 					   e->dest);
-      const_and_copies->pop_to_marker ();
-      avail_exprs_stack->pop_to_marker ();
-      if (evrp_range_analyzer)
-	evrp_range_analyzer->pop_to_marker ();
       BITMAP_FREE (visited);
-      register_jump_thread (path);
+      m_registry->register_jump_thread (path);
+      m_state->pop ();
       return;
     }
   else
@@ -1290,7 +1179,6 @@ thread_across_edge (gcond *dummy_cond,
 	 through the vector entries.  */
       gcc_assert (path->length () == 0);
       path->release ();
-      delete path;
 
       /* A negative status indicates the target block was deemed too big to
 	 duplicate.  Just quit now rather than trying to use the block as
@@ -1302,10 +1190,7 @@ thread_across_edge (gcond *dummy_cond,
       if (threaded < 0)
 	{
 	  BITMAP_FREE (visited);
-	  const_and_copies->pop_to_marker ();
-          avail_exprs_stack->pop_to_marker ();
-	  if (evrp_range_analyzer)
-	    evrp_range_analyzer->pop_to_marker ();
+	  m_state->pop ();
 	  return;
 	}
     }
@@ -1331,10 +1216,7 @@ thread_across_edge (gcond *dummy_cond,
     FOR_EACH_EDGE (taken_edge, ei, e->dest->succs)
       if (taken_edge->flags & EDGE_COMPLEX)
 	{
-	  const_and_copies->pop_to_marker ();
-          avail_exprs_stack->pop_to_marker ();
-	  if (evrp_range_analyzer)
-	    evrp_range_analyzer->pop_to_marker ();
+	  m_state->pop ();
 	  BITMAP_FREE (visited);
 	  return;
 	}
@@ -1346,41 +1228,29 @@ thread_across_edge (gcond *dummy_cond,
 	    || (taken_edge->flags & EDGE_DFS_BACK) != 0)
 	  continue;
 
-	/* Push a fresh marker so we can unwind the equivalences created
-	   for each of E->dest's successors.  */
-	const_and_copies->push_marker ();
-	avail_exprs_stack->push_marker ();
-	if (evrp_range_analyzer)
-	  evrp_range_analyzer->push_marker ();
+	m_state->push (taken_edge);
 
 	/* Avoid threading to any block we have already visited.  */
 	bitmap_clear (visited);
 	bitmap_set_bit (visited, e->src->index);
 	bitmap_set_bit (visited, e->dest->index);
 	bitmap_set_bit (visited, taken_edge->dest->index);
-        vec<jump_thread_edge *> *path = new vec<jump_thread_edge *> ();
+	vec<jump_thread_edge *> *path = m_registry->allocate_thread_path ();
 
 	/* Record whether or not we were able to thread through a successor
 	   of E->dest.  */
-        jump_thread_edge *x = new jump_thread_edge (e, EDGE_START_JUMP_THREAD);
+	jump_thread_edge *x
+	  = m_registry->allocate_thread_edge (e, EDGE_START_JUMP_THREAD);
 	path->safe_push (x);
 
-        x = new jump_thread_edge (taken_edge, EDGE_COPY_SRC_JOINER_BLOCK);
+	x = m_registry->allocate_thread_edge (taken_edge,
+					      EDGE_COPY_SRC_JOINER_BLOCK);
 	path->safe_push (x);
-	found = thread_around_empty_blocks (taken_edge,
-					    dummy_cond,
-					    avail_exprs_stack,
-					    simplify,
-					    visited,
-					    path);
+	found = thread_around_empty_blocks (path, taken_edge, visited);
 
 	if (!found)
-	  found = thread_through_normal_block (path->last ()->e, dummy_cond,
-					       const_and_copies,
-					       avail_exprs_stack,
-					       evrp_range_analyzer,
-					       simplify, path,
-					       visited) > 0;
+	  found = thread_through_normal_block (path,
+					       path->last ()->e, visited) > 0;
 
 	/* If we were able to thread through a successor of E->dest, then
 	   record the jump threading opportunity.  */
@@ -1390,47 +1260,36 @@ thread_across_edge (gcond *dummy_cond,
 	    if (taken_edge->dest != path->last ()->e->dest)
 	      propagate_threaded_block_debug_into (path->last ()->e->dest,
 						   taken_edge->dest);
-	    register_jump_thread (path);
+	    m_registry->register_jump_thread (path);
 	  }
 	else
-	  delete_jump_thread_path (path);
+	  path->release ();
 
-	/* And unwind the equivalence table.  */
-	if (evrp_range_analyzer)
-	  evrp_range_analyzer->pop_to_marker ();
-	avail_exprs_stack->pop_to_marker ();
-	const_and_copies->pop_to_marker ();
+	m_state->pop ();
       }
     BITMAP_FREE (visited);
   }
 
-  if (evrp_range_analyzer)
-    evrp_range_analyzer->pop_to_marker ();
-  const_and_copies->pop_to_marker ();
-  avail_exprs_stack->pop_to_marker ();
+  m_state->pop ();
 }
 
-/* Examine the outgoing edges from BB and conditionally
-   try to thread them.
-
-   DUMMY_COND is a shared cond_expr used by condition simplification as scratch,
-   to avoid allocating memory.
-
-   CONST_AND_COPIES is used to undo temporary equivalences created during the
-   walk of E->dest.
+/* Return TRUE if BB has a single successor to a block with multiple
+   incoming and outgoing edges.  */
 
-   The available expression table is referenced vai AVAIL_EXPRS_STACK.
+bool
+single_succ_to_potentially_threadable_block (basic_block bb)
+{
+  int flags = (EDGE_IGNORE | EDGE_COMPLEX | EDGE_ABNORMAL);
+  return (single_succ_p (bb)
+	  && (single_succ_edge (bb)->flags & flags) == 0
+	  && potentially_threadable_block (single_succ (bb)));
+}
 
-   SIMPLIFY is a pass-specific function used to simplify statements.  */
+/* Examine the outgoing edges from BB and conditionally
+   try to thread them.  */
 
 void
-thread_outgoing_edges (basic_block bb, gcond *dummy_cond,
-		       class const_and_copies *const_and_copies,
-		       class avail_exprs_stack *avail_exprs_stack,
-		       class evrp_range_analyzer *evrp_range_analyzer,
-		       tree (*simplify) (gimple *, gimple *,
-					 class avail_exprs_stack *,
-					 basic_block))
+jump_threader::thread_outgoing_edges (basic_block bb)
 {
   int flags = (EDGE_IGNORE | EDGE_COMPLEX | EDGE_ABNORMAL);
   gimple *last;
@@ -1439,14 +1298,8 @@ thread_outgoing_edges (basic_block bb, gcond *dummy_cond,
      outgoing edges, then we may be able to thread the edge, i.e., we
      may be able to statically determine which of the outgoing edges
      will be traversed when the incoming edge from BB is traversed.  */
-  if (single_succ_p (bb)
-      && (single_succ_edge (bb)->flags & flags) == 0
-      && potentially_threadable_block (single_succ (bb)))
-    {
-      thread_across_edge (dummy_cond, single_succ_edge (bb),
-			  const_and_copies, avail_exprs_stack,
-			  evrp_range_analyzer, simplify);
-    }
+  if (single_succ_to_potentially_threadable_block (bb))
+    thread_across_edge (single_succ_edge (bb));
   else if ((last = last_stmt (bb))
 	   && gimple_code (last) == GIMPLE_COND
 	   && EDGE_COUNT (bb->succs) == 2
@@ -1460,14 +1313,162 @@ thread_outgoing_edges (basic_block bb, gcond *dummy_cond,
       /* Only try to thread the edge if it reaches a target block with
 	 more than one predecessor and more than one successor.  */
       if (potentially_threadable_block (true_edge->dest))
-	thread_across_edge (dummy_cond, true_edge,
-			    const_and_copies, avail_exprs_stack,
-			    evrp_range_analyzer, simplify);
+	thread_across_edge (true_edge);
 
       /* Similarly for the ELSE arm.  */
       if (potentially_threadable_block (false_edge->dest))
-	thread_across_edge (dummy_cond, false_edge,
-			    const_and_copies, avail_exprs_stack,
-			    evrp_range_analyzer, simplify);
+	thread_across_edge (false_edge);
+    }
+}
+
+jt_state::jt_state (const_and_copies *copies,
+		    avail_exprs_stack *exprs,
+		    evrp_range_analyzer *evrp)
+{
+  m_copies = copies;
+  m_exprs = exprs;
+  m_evrp = evrp;
+}
+
+// Record that E is being crossed.
+
+void
+jt_state::push (edge)
+{
+  if (m_copies)
+    m_copies->push_marker ();
+  if (m_exprs)
+    m_exprs->push_marker ();
+  if (m_evrp)
+    m_evrp->push_marker ();
+}
+
+// Pop to the last pushed state.
+
+void
+jt_state::pop ()
+{
+  if (m_copies)
+    m_copies->pop_to_marker ();
+  if (m_exprs)
+    m_exprs->pop_to_marker ();
+  if (m_evrp)
+    m_evrp->pop_to_marker ();
+}
+
+// Record an equivalence from DST to SRC.  If UPDATE_RANGE is TRUE,
+// update the value range associated with DST.
+
+void
+jt_state::register_equiv (tree dst, tree src, bool update_range)
+{
+  if (m_copies)
+    m_copies->record_const_or_copy (dst, src);
+
+  /* If requested, update the value range associated with DST, using
+     the range from SRC.  */
+  if (m_evrp && update_range)
+    {
+      /* Get new VR we can pass to push_value_range.  */
+      value_range_equiv *new_vr = m_evrp->allocate_value_range_equiv ();
+      new (new_vr) value_range_equiv ();
+
+      /* There are three cases to consider:
+
+	 First if SRC is an SSA_NAME, then we can copy the value range
+	 from SRC into NEW_VR.
+
+	 Second if SRC is an INTEGER_CST, then we can just set NEW_VR
+	 to a singleton range.  Note that even if SRC is a constant we
+	 need to set a suitable output range so that VR_UNDEFINED
+	 ranges do not leak through.
+
+	 Otherwise set NEW_VR to varying.  This may be overly
+	 conservative.  */
+      if (TREE_CODE (src) == SSA_NAME)
+	new_vr->deep_copy (m_evrp->get_value_range (src));
+      else if (TREE_CODE (src) == INTEGER_CST)
+	new_vr->set (src);
+      else
+	new_vr->set_varying (TREE_TYPE (src));
+
+      /* This is a temporary range for DST, so push it.  */
+      m_evrp->push_value_range (dst, new_vr);
+    }
+}
+
+// Record any ranges calculated in STMT.  If TEMPORARY is TRUE, then
+// this is a temporary equivalence and should be recorded into the
+// unwind table, instead of the global table.
+
+void
+jt_state::record_ranges_from_stmt (gimple *stmt, bool temporary)
+{
+  if (m_evrp)
+    m_evrp->record_ranges_from_stmt (stmt, temporary);
+}
+
+// Record any equivalences created by traversing E.
+
+void
+jt_state::register_equivs_on_edge (edge e)
+{
+  if (m_copies && m_exprs)
+    record_temporary_equivalences (e, m_copies, m_exprs);
+}
+
+jump_threader_simplifier::jump_threader_simplifier (vr_values *v)
+{
+  m_vr_values = v;
+}
+
+// Return the singleton that resolves STMT, if it is possible to
+// simplify it.
+//
+// STMT may be a dummy statement, not necessarily in the CFG, in which
+// case WITHIN_STMT can be used to determine the position in the CFG
+// where STMT should be evaluated as being in.
+
+tree
+jump_threader_simplifier::simplify (gimple *stmt,
+				    gimple *within_stmt,
+				    basic_block,
+				    jt_state *)
+{
+  if (gcond *cond_stmt = dyn_cast <gcond *> (stmt))
+    {
+      simplify_using_ranges simplifier (m_vr_values);
+      return simplifier.vrp_evaluate_conditional (gimple_cond_code (cond_stmt),
+						  gimple_cond_lhs (cond_stmt),
+						  gimple_cond_rhs (cond_stmt),
+						  within_stmt);
+    }
+  if (gswitch *switch_stmt = dyn_cast <gswitch *> (stmt))
+    {
+      tree op = gimple_switch_index (switch_stmt);
+      if (TREE_CODE (op) != SSA_NAME)
+	return NULL_TREE;
+
+      const value_range_equiv *vr = m_vr_values->get_value_range (op);
+      return find_case_label_range (switch_stmt, vr);
+    }
+   if (gassign *assign_stmt = dyn_cast <gassign *> (stmt))
+    {
+      tree lhs = gimple_assign_lhs (assign_stmt);
+      if (TREE_CODE (lhs) == SSA_NAME
+	  && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
+	      || POINTER_TYPE_P (TREE_TYPE (lhs)))
+	  && stmt_interesting_for_vrp (stmt))
+	{
+	  edge dummy_e;
+	  tree dummy_tree;
+	  value_range_equiv new_vr;
+	  m_vr_values->extract_range_from_stmt (stmt, &dummy_e, &dummy_tree,
+						&new_vr);
+	  tree singleton;
+	  if (new_vr.singleton_p (&singleton))
+	    return singleton;
+	}
     }
+   return NULL;
 }