re PR middle-end/63155 (memory hog)

2018-10-05  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/63155
	* tree-ssa-ccp.c (ccp_propagate::visit_phi): Avoid excess
	vertical space in dumpfiles.
	* tree-ssa-propagate.h
	(ssa_propagation_engine::process_ssa_edge_worklist): Remove.
	* tree-ssa-propagate.c (cfg_blocks_back): New global.
	(ssa_edge_worklist_back): Likewise.
	(curr_order): Likewise.
	(cfg_blocks_get): Remove abstraction.
	(cfg_blocks_add): Likewise.
	(cfg_blocks_empty_p): Likewise.
	(add_ssa_edge): Add to current or next worklist based on
	RPO index.
	(add_control_edge): Likewise.
	(ssa_propagation_engine::process_ssa_edge_worklist): Fold
	into ...
	(ssa_propagation_engine::ssa_propagate): ... here.  Unify
	iteration from CFG and SSA edge worklist so we process
	everything in RPO order, prioritizing forward progress
	over iteration.
	(ssa_prop_init): Allocate new worklists, do not dump
	immediate uses.
	(ssa_prop_fini): Free new worklists.

From-SVN: r264869

gcc/ChangeLog

 2018-10-05  Richard Biener  <rguenther@suse.de>
 
+	PR tree-optimization/63155
+	* tree-ssa-ccp.c (ccp_propagate::visit_phi): Avoid excess
+	vertical space in dumpfiles.
+	* tree-ssa-propagate.h
+	(ssa_propagation_engine::process_ssa_edge_worklist): Remove.
+	* tree-ssa-propagate.c (cfg_blocks_back): New global.
+	(ssa_edge_worklist_back): Likewise.
+	(curr_order): Likewise.
+	(cfg_blocks_get): Remove abstraction.
+	(cfg_blocks_add): Likewise.
+	(cfg_blocks_empty_p): Likewise.
+	(add_ssa_edge): Add to current or next worklist based on
+	RPO index.
+	(add_control_edge): Likewise.
+	(ssa_propagation_engine::process_ssa_edge_worklist): Fold
+	into ...
+	(ssa_propagation_engine::ssa_propagate): ... here.  Unify
+	iteration from CFG and SSA edge worklist so we process
+	everything in RPO order, prioritizing forward progress
+	over iteration.
+	(ssa_prop_init): Allocate new worklists, do not dump
+	immediate uses.
+	(ssa_prop_fini): Free new worklists.
+
+2018-10-05  Richard Biener  <rguenther@suse.de>
+
 	* tree-core.h (tree_block::abstract_flag): Remove.
 	(tree_block::block_num): Make full 32bits.
 	* tree.def (BLOCK): Remove docs about BLOCK_ABSTRACT.

gcc/tree-ssa-ccp.c

@@ -1119,7 +1119,7 @@ ccp_propagate::visit_phi (gphi *phi)
       if (dump_file && (dump_flags & TDF_DETAILS))
 	{
 	  fprintf (dump_file,
-	      "\n    Argument #%d (%d -> %d %sexecutable)\n",
+	      "\tArgument #%d (%d -> %d %sexecutable)\n",
 	      i, e->src->index, e->dest->index,
 	      (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
 	}

gcc/tree-ssa-propagate.c

@@ -108,51 +108,26 @@
      [3] Advanced Compiler Design and Implementation,
 	 Steven Muchnick, Morgan Kaufmann, 1997, Section 12.6  */
 
-/* Worklist of control flow edge destinations.  This contains
+/* Worklists of control flow edge destinations.  This contains
    the CFG order number of the blocks so we can iterate in CFG
-   order by visiting in bit-order.  */
+   order by visiting in bit-order.  We use two worklists to
+   first make forward progress before iterating.  */
 static bitmap cfg_blocks;
+static bitmap cfg_blocks_back;
 static int *bb_to_cfg_order;
 static int *cfg_order_to_bb;
 
-/* Worklist of SSA edges which will need reexamination as their
+/* Worklists of SSA edges which will need reexamination as their
    definition has changed.  SSA edges are def-use edges in the SSA
    web.  For each D-U edge, we store the target statement or PHI node
-   UID in a bitmap.  UIDs order stmts in execution order.   */
+   UID in a bitmap.  UIDs order stmts in execution order.  We use
+   two worklists to first make forward progress before iterating.  */
 static bitmap ssa_edge_worklist;
+static bitmap ssa_edge_worklist_back;
 static vec<gimple *> uid_to_stmt;
 
-/* Return true if the block worklist empty.  */
-
-static inline bool
-cfg_blocks_empty_p (void)
-{
-  return bitmap_empty_p (cfg_blocks);
-}
-
-
-/* Add a basic block to the worklist.  The block must not be the ENTRY
-   or EXIT block.  */
-
-static void
-cfg_blocks_add (basic_block bb)
-{
-  gcc_assert (bb != ENTRY_BLOCK_PTR_FOR_FN (cfun)
-	      && bb != EXIT_BLOCK_PTR_FOR_FN (cfun));
-  bitmap_set_bit (cfg_blocks, bb_to_cfg_order[bb->index]);
-}
-
-
-/* Remove a block from the worklist.  */
-
-static basic_block
-cfg_blocks_get (void)
-{
-  gcc_assert (!cfg_blocks_empty_p ());
-  int order_index = bitmap_first_set_bit (cfg_blocks);
-  bitmap_clear_bit (cfg_blocks, order_index);
-  return BASIC_BLOCK_FOR_FN (cfun, cfg_order_to_bb [order_index]);
-}
+/* Current RPO index in the iteration.  */
+static int curr_order;
 
 
 /* We have just defined a new value for VAR.  If IS_VARYING is true,
@@ -182,8 +157,15 @@ add_ssa_edge (tree var)
 	       & EDGE_EXECUTABLE))
 	continue;
 
-      if (prop_simulate_again_p (use_stmt)
-	  && bitmap_set_bit (ssa_edge_worklist, gimple_uid (use_stmt)))
+      if (!prop_simulate_again_p (use_stmt))
+	continue;
+
+      bitmap worklist;
+      if (bb_to_cfg_order[gimple_bb (use_stmt)->index] < curr_order)
+	worklist = ssa_edge_worklist_back;
+      else
+	worklist = ssa_edge_worklist;
+      if (bitmap_set_bit (worklist, gimple_uid (use_stmt)))
 	{
 	  uid_to_stmt[gimple_uid (use_stmt)] = use_stmt;
 	  if (dump_file && (dump_flags & TDF_DETAILS))
@@ -211,7 +193,11 @@ add_control_edge (edge e)
 
   e->flags |= EDGE_EXECUTABLE;
 
-  cfg_blocks_add (bb);
+  int bb_order = bb_to_cfg_order[bb->index];
+  if (bb_order < curr_order)
+    bitmap_set_bit (cfg_blocks_back, bb_order);
+  else
+    bitmap_set_bit (cfg_blocks, bb_order);
 
   if (dump_file && (dump_flags & TDF_DETAILS))
     fprintf (dump_file, "Adding destination of edge (%d -> %d) to worklist\n",
@@ -318,33 +304,6 @@ ssa_propagation_engine::simulate_stmt (gimple *stmt)
     }
 }
 
-/* Process an SSA edge worklist.  WORKLIST is the SSA edge worklist to
-   drain.  This pops statements off the given WORKLIST and processes
-   them until one statement was simulated or there are no more statements
-   on WORKLIST.  We take a pointer to WORKLIST because it may be reallocated
-   when an SSA edge is added to it in simulate_stmt.  Return true if a stmt
-   was simulated.  */
-
-void
-ssa_propagation_engine::process_ssa_edge_worklist (void)
-{
-  /* Process the next entry from the worklist.  */
-  unsigned stmt_uid = bitmap_first_set_bit (ssa_edge_worklist);
-  bitmap_clear_bit (ssa_edge_worklist, stmt_uid);
-  gimple *stmt = uid_to_stmt[stmt_uid];
-
-  /* We should not have stmts in not yet simulated BBs on the worklist.  */
-  gcc_assert (gimple_bb (stmt)->flags & BB_VISITED);
-
-  if (dump_file && (dump_flags & TDF_DETAILS))
-    {
-      fprintf (dump_file, "\nSimulating statement: ");
-      print_gimple_stmt (dump_file, stmt, 0, dump_flags);
-    }
-
-  simulate_stmt (stmt);
-}
-
 
 /* Simulate the execution of BLOCK.  Evaluate the statement associated
    with each variable reference inside the block.  */
@@ -422,6 +381,7 @@ ssa_prop_init (void)
 
   /* Worklists of SSA edges.  */
   ssa_edge_worklist = BITMAP_ALLOC (NULL);
+  ssa_edge_worklist_back = BITMAP_ALLOC (NULL);
 
   /* Worklist of basic-blocks.  */
   bb_to_cfg_order = XNEWVEC (int, last_basic_block_for_fn (cfun) + 1);
@@ -431,9 +391,7 @@ ssa_prop_init (void)
   for (int i = 0; i < n; ++i)
     bb_to_cfg_order[cfg_order_to_bb[i]] = i;
   cfg_blocks = BITMAP_ALLOC (NULL);
-
-  if (dump_file && (dump_flags & TDF_DETAILS))
-    dump_immediate_uses (dump_file);
+  cfg_blocks_back = BITMAP_ALLOC (NULL);
 
   /* Initially assume that every edge in the CFG is not executable.
      (including the edges coming out of the entry block).  Mark blocks
@@ -479,9 +437,11 @@ static void
 ssa_prop_fini (void)
 {
   BITMAP_FREE (cfg_blocks);
+  BITMAP_FREE (cfg_blocks_back);
   free (bb_to_cfg_order);
   free (cfg_order_to_bb);
   BITMAP_FREE (ssa_edge_worklist);
+  BITMAP_FREE (ssa_edge_worklist_back);
   uid_to_stmt.release ();
 }
 
@@ -796,21 +756,62 @@ ssa_propagation_engine::ssa_propagate (void)
 {
   ssa_prop_init ();
 
-  /* Iterate until the worklists are empty.  */
-  while (! cfg_blocks_empty_p ()
-	 || ! bitmap_empty_p (ssa_edge_worklist))
+  curr_order = 0;
+
+  /* Iterate until the worklists are empty.  We iterate both blocks
+     and stmts in RPO order, using sets of two worklists to first
+     complete the current iteration before iterating over backedges.  */
+  while (1)
     {
-      /* First simulate whole blocks.  */
-      if (! cfg_blocks_empty_p ())
+      int next_block_order = (bitmap_empty_p (cfg_blocks)
+			      ? -1 : bitmap_first_set_bit (cfg_blocks));
+      int next_stmt_uid = (bitmap_empty_p (ssa_edge_worklist)
+			   ? -1 : bitmap_first_set_bit (ssa_edge_worklist));
+      if (next_block_order == -1 && next_stmt_uid == -1)
 	{
-	  /* Pull the next block to simulate off the worklist.  */
-	  basic_block dest_block = cfg_blocks_get ();
-	  simulate_block (dest_block);
+	  if (bitmap_empty_p (cfg_blocks_back)
+	      && bitmap_empty_p (ssa_edge_worklist_back))
+	    break;
+
+	  if (dump_file && (dump_flags & TDF_DETAILS))
+	    fprintf (dump_file, "Regular worklists empty, now processing "
+		     "backedge destinations\n");
+	  std::swap (cfg_blocks, cfg_blocks_back);
+	  std::swap (ssa_edge_worklist, ssa_edge_worklist_back);
 	  continue;
 	}
 
-      /* Then simulate from the SSA edge worklist.  */
-      process_ssa_edge_worklist ();
+      int next_stmt_bb_order = -1;
+      gimple *next_stmt = NULL;
+      if (next_stmt_uid != -1)
+	{
+	  next_stmt = uid_to_stmt[next_stmt_uid];
+	  next_stmt_bb_order = bb_to_cfg_order[gimple_bb (next_stmt)->index];
+	}
+
+      /* Pull the next block to simulate off the worklist if it comes first.  */
+      if (next_block_order != -1
+	  && (next_stmt_bb_order == -1
+	      || next_block_order <= next_stmt_bb_order))
+	{
+	  curr_order = next_block_order;
+	  bitmap_clear_bit (cfg_blocks, next_block_order);
+	  basic_block bb
+	    = BASIC_BLOCK_FOR_FN (cfun, cfg_order_to_bb [next_block_order]);
+	  simulate_block (bb);
+	}
+      /* Else simulate from the SSA edge worklist.  */
+      else
+	{
+	  curr_order = next_stmt_bb_order;
+	  bitmap_clear_bit (ssa_edge_worklist, next_stmt_uid);
+	  if (dump_file && (dump_flags & TDF_DETAILS))
+	    {
+	      fprintf (dump_file, "\nSimulating statement: ");
+	      print_gimple_stmt (dump_file, next_stmt, 0, dump_flags);
+	    }
+	  simulate_stmt (next_stmt);
+	}
     }
 
   ssa_prop_fini ();

gcc/tree-ssa-propagate.h

@@ -94,9 +94,7 @@ class ssa_propagation_engine
  private:
   /* Internal implementation details.  */
   void simulate_stmt (gimple *stmt);
-  void process_ssa_edge_worklist (void);
   void simulate_block (basic_block);
-
 };
 
 class substitute_and_fold_engine