[patch] Stay in cfglayout mode until after cse2

Steven Bosscher stevenb.gcc@gmail.com
Tue Mar 13 21:16:00 GMT 2007


Hi,

This patch postpones going out of cfglayout mode until after cse2.
It will probably stay there for a while, because combine is totally
unprepared for cfglayout mode right now.  Paolo Bonzini has fixes
for this on the dataflow branch, but until that branch is merged,
we'll have to go out of cfglayout mode before combine.

The next hurdle will be regmove.  I'm hoping a Google Summer of
Code student will re-implement regmove (with my help if required)...

This patch has been bootstrapped&tested on i686-pc-linux-gnu.
OK for the trunk?

Thanks,

Gr.
Steven

	* tracer.c (tracer): Don't take FLAGS argument.  Assert we are
	in cfglayout mode.  Don't go into and out of cfglayout mode.
	Link the blocks in the order of the constructed traces.
	(rest_of_handle_tracer): Adjust call to tracer.
	* loop-init.c (rtl_loop_init): Assert we are in cfglayout mode.
	Don't go into cfglayout mode.
	(rtl_loop_done): Don't go out of cfglayout mode.
	* cfglayout.c (relink_block_chain): New function, split out from...
	(fixup_reorder_chain): ...here.  Remove redundant checking.
	(cfg_layout_finalize): Don't clear the header, footer, and aux
	fields here, move the code to do so to relink_block_chain.  Likewise
	for free_original_copy_tables.
	* rtl.h (tracer): Update prototype.
	* bb-reorder.c (reorder_basic_blocks): Don't take FLAGS argument.
	Assert we are in cfglayout mode.  Don't go into and out of cfglayout
	mode.  Use relink_block_chain to serialize the CFG according to the
	new basic block order.  Move targetm.cannot_modify_jumps_p check from
	here...
	(gate_handle_reorder_blocks): ...to here.
	(duplicate_computed_gotos): Move targetm.cannot_modify_jumps_p check
	from here...
	(gate_duplicate_computed_gotos): ...to here.
	(rest_of_handle_reorder_blocks): Don't see if anything has changed,
	something always changes when going into and out of cfglayout mode.
	Perform an expensive cfg cleanup while going into cfglayout mode.
	Always update liveness information on HAVE_conditional_execution
	targets.  Reserialize the basic blocks and go out of cfglayout mode.
	* reg-stack.c: Include cfglayout.h.
	(rest_of_handle_stack_regs): Go into and out of cfglayout mode around
	the call to reorder_basic_blocks.
	* basic-block.h (reorder_basic_blocks): Update prototype.
	(relink_block_chain): New prototype.
	* passes.c (pass_outof_cfg_layout_mode): Move after cse2.

Index: tracer.c
===================================================================
--- tracer.c	(revision 122857)
+++ tracer.c	(working copy)
@@ -357,24 +357,25 @@ layout_superblocks (void)
     }
 }
 
-/* Main entry point to this file.  FLAGS is the set of flags to pass
-   to cfg_layout_initialize().  */
+/* Main entry point to this file.  */
 
 void
-tracer (unsigned int flags)
+tracer (void)
 {
+  gcc_assert (current_ir_type () == IR_RTL_CFGLAYOUT);
+
   if (n_basic_blocks <= NUM_FIXED_BLOCKS + 1)
     return;
 
-  cfg_layout_initialize (flags);
   mark_dfs_back_edges ();
   if (dump_file)
     dump_flow_info (dump_file, dump_flags);
   tail_duplicate ();
   layout_superblocks ();
+  relink_block_chain (/*stay_in_cfglayout_mode=*/true);
+  
   if (dump_file)
     dump_flow_info (dump_file, dump_flags);
-  cfg_layout_finalize ();
 
   /* Merge basic blocks in duplicated traces.  */
   cleanup_cfg (CLEANUP_EXPENSIVE);
@@ -392,7 +393,7 @@ rest_of_handle_tracer (void)
 {
   if (dump_file)
     dump_flow_info (dump_file, dump_flags);
-  tracer (0);
+  tracer ();
   reg_scan (get_insns (), max_reg_num ());
   return 0;
 }
Index: loop-init.c
===================================================================
--- loop-init.c	(revision 122857)
+++ loop-init.c	(working copy)
@@ -171,12 +171,11 @@ struct tree_opt_pass pass_loop2 =
 static unsigned int
 rtl_loop_init (void)
 {
+  gcc_assert (current_ir_type () == IR_RTL_CFGLAYOUT);
+  
   if (dump_file)
     dump_flow_info (dump_file, dump_flags);
 
-  /* Initialize structures for layout changes.  */
-  cfg_layout_initialize (0);
-
   loop_optimizer_init (LOOPS_NORMAL);
   return 0;
 }
@@ -204,17 +203,9 @@ struct tree_opt_pass pass_rtl_loop_init 
 static unsigned int
 rtl_loop_done (void)
 {
-  basic_block bb;
-
   loop_optimizer_finalize ();
   free_dominance_info (CDI_DOMINATORS);
 
-  /* Finalize layout changes.  */
-  FOR_EACH_BB (bb)
-    if (bb->next_bb != EXIT_BLOCK_PTR)
-      bb->aux = bb->next_bb;
-  cfg_layout_finalize ();
-
   cleanup_cfg (CLEANUP_EXPENSIVE);
   delete_trivially_dead_insns (get_insns (), max_reg_num ());
   reg_scan (get_insns (), max_reg_num ());
Index: cfglayout.c
===================================================================
--- cfglayout.c	(revision 122858)
+++ cfglayout.c	(working copy)
@@ -634,13 +634,83 @@ reemit_insn_block_notes (void)
   reorder_blocks ();
 }
 
+
+/* Link the basic blocks in the correct order, compacting the basic
+   block queue while at it.  This also clears the visited flag on
+   all basic blocks.  If STAY_IN_CFGLAYOUT_MODE is false, this function
+   also clears the basic block header and footer fields.
+
+   This function is usually called after a pass (e.g. tracer) finishes
+   some transformations while in cfglayout mode.  The required sequence
+   of the basic blocks is in a linked list along the bb->aux field.
+   This functions re-links the basic block prev_bb and next_bb pointers
+   accordingly, and it compacts and renumbers the blocks.  */
+
+void
+relink_block_chain (bool stay_in_cfglayout_mode)
+{
+  basic_block bb, prev_bb;
+  int index;
+
+  /* Maybe dump the re-ordered sequence.  */
+  if (dump_file)
+    {
+      fprintf (dump_file, "Reordered sequence:\n");
+      for (bb = ENTRY_BLOCK_PTR->next_bb, index = NUM_FIXED_BLOCKS;
+	   bb;
+	   bb = bb->aux, index++)
+	{
+	  fprintf (dump_file, " %i ", index);
+	  if (get_bb_original (bb))
+	    fprintf (dump_file, "duplicate of %i ",
+		     get_bb_original (bb)->index);
+	  else if (forwarder_block_p (bb)
+		   && !LABEL_P (BB_HEAD (bb)))
+	    fprintf (dump_file, "compensation ");
+	  else
+	    fprintf (dump_file, "bb %i ", bb->index);
+	  fprintf (dump_file, " [%i]\n", bb->frequency);
+	}
+    }
+
+  /* Now reorder the blocks.  */
+  prev_bb = ENTRY_BLOCK_PTR;
+  bb = ENTRY_BLOCK_PTR->next_bb;
+  for (; bb; prev_bb = bb, bb = bb->aux)
+    {
+      bb->prev_bb = prev_bb;
+      prev_bb->next_bb = bb;
+    }
+  prev_bb->next_bb = EXIT_BLOCK_PTR;
+  EXIT_BLOCK_PTR->prev_bb = prev_bb;
+
+  /* Then, clean up the aux and visited fields.  */
+  FOR_ALL_BB (bb)
+    {
+      bb->aux = NULL;
+      bb->il.rtl->visited = 0;
+      if (!stay_in_cfglayout_mode)
+	bb->il.rtl->header = bb->il.rtl->footer = NULL;
+    }
+
+  /* Maybe reset the original copy tables, they are not valid anymore
+     when we renumber the basic blocks in compact_blocks.  If we are
+     are going out of cfglayout mode, don't re-allocate the tables.  */
+  free_original_copy_tables ();
+  if (stay_in_cfglayout_mode)
+    initialize_original_copy_tables ();
+  
+  /* Finally, put basic_block_info in the new order.  */
+  compact_blocks ();
+}
+
+
 /* Given a reorder chain, rearrange the code to match.  */
 
 static void
 fixup_reorder_chain (void)
 {
-  basic_block bb, prev_bb;
-  int index;
+  basic_block bb;
   rtx insn = NULL;
 
   if (cfg_layout_function_header)
@@ -654,9 +724,7 @@ fixup_reorder_chain (void)
   /* First do the bulk reordering -- rechain the blocks without regard to
      the needed changes to jumps and labels.  */
 
-  for (bb = ENTRY_BLOCK_PTR->next_bb, index = NUM_FIXED_BLOCKS;
-       bb != 0;
-       bb = bb->aux, index++)
+  for (bb = ENTRY_BLOCK_PTR->next_bb; bb; bb = bb->aux)
     {
       if (bb->il.rtl->header)
 	{
@@ -684,8 +752,6 @@ fixup_reorder_chain (void)
 	}
     }
 
-  gcc_assert (index == n_basic_blocks);
-
   NEXT_INSN (insn) = cfg_layout_function_footer;
   if (cfg_layout_function_footer)
     PREV_INSN (cfg_layout_function_footer) = insn;
@@ -838,42 +904,7 @@ fixup_reorder_chain (void)
 	}
     }
 
-  /* Put basic_block_info in the new order.  */
-
-  if (dump_file)
-    {
-      fprintf (dump_file, "Reordered sequence:\n");
-      for (bb = ENTRY_BLOCK_PTR->next_bb, index = NUM_FIXED_BLOCKS;
-	   bb;
-	   bb = bb->aux, index++)
-	{
-	  fprintf (dump_file, " %i ", index);
-	  if (get_bb_original (bb))
-	    fprintf (dump_file, "duplicate of %i ",
-		     get_bb_original (bb)->index);
-	  else if (forwarder_block_p (bb)
-		   && !LABEL_P (BB_HEAD (bb)))
-	    fprintf (dump_file, "compensation ");
-	  else
-	    fprintf (dump_file, "bb %i ", bb->index);
-	  fprintf (dump_file, " [%i]\n", bb->frequency);
-	}
-    }
-
-  prev_bb = ENTRY_BLOCK_PTR;
-  bb = ENTRY_BLOCK_PTR->next_bb;
-  index = NUM_FIXED_BLOCKS;
-
-  for (; bb; prev_bb = bb, bb = bb->aux, index ++)
-    {
-      bb->index = index;
-      SET_BASIC_BLOCK (index, bb);
-
-      bb->prev_bb = prev_bb;
-      prev_bb->next_bb = bb;
-    }
-  prev_bb->next_bb = EXIT_BLOCK_PTR;
-  EXIT_BLOCK_PTR->prev_bb = prev_bb;
+  relink_block_chain (/*stay_in_cfglayout_mode=*/false);
 
   /* Annoying special case - jump around dead jumptables left in the code.  */
   FOR_EACH_BB (bb)
@@ -1179,8 +1210,6 @@ break_superblocks (void)
 void
 cfg_layout_finalize (void)
 {
-  basic_block bb;
-
 #ifdef ENABLE_CHECKING
   verify_flow_info ();
 #endif
@@ -1195,19 +1224,8 @@ cfg_layout_finalize (void)
 
 #ifdef ENABLE_CHECKING
   verify_insn_chain ();
-#endif
-  FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
-  {
-    bb->il.rtl->header = bb->il.rtl->footer = NULL;
-    bb->aux = NULL;
-    bb->il.rtl->visited = 0;
-  }
-
-#ifdef ENABLE_CHECKING
   verify_flow_info ();
 #endif
-
-  free_original_copy_tables ();
 }
 
 /* Checks whether all N blocks in BBS array can be copied.  */
Index: rtl.h
===================================================================
--- rtl.h	(revision 122857)
+++ rtl.h	(working copy)
@@ -2259,7 +2259,7 @@ extern bool expensive_function_p (int);
 /* In cfgexpand.c */
 extern void add_reg_br_prob_note (rtx last, int probability);
 /* In tracer.c */
-extern void tracer (unsigned int);
+extern void tracer (void);
 
 /* In var-tracking.c */
 extern unsigned int variable_tracking_main (void);
Index: bb-reorder.c
===================================================================
--- bb-reorder.c	(revision 122857)
+++ bb-reorder.c	(working copy)
@@ -1889,20 +1889,17 @@ verify_hot_cold_block_grouping (void)
    the set of flags to pass to cfg_layout_initialize().  */
 
 void
-reorder_basic_blocks (unsigned int flags)
+reorder_basic_blocks (void)
 {
   int n_traces;
   int i;
   struct trace *traces;
 
-  if (n_basic_blocks <= NUM_FIXED_BLOCKS + 1)
-    return;
+  gcc_assert (current_ir_type () == IR_RTL_CFGLAYOUT);
 
-  if (targetm.cannot_modify_jumps_p ())
+  if (n_basic_blocks <= NUM_FIXED_BLOCKS + 1)
     return;
 
-  cfg_layout_initialize (flags);
-
   set_edge_can_fallthru_flag ();
   mark_dfs_back_edges ();
 
@@ -1930,10 +1927,11 @@ reorder_basic_blocks (unsigned int flags
   FREE (traces);
   FREE (bbd);
 
+  relink_block_chain (/*stay_in_cfglayout_mode=*/true);
+
   if (dump_file)
     dump_flow_info (dump_file, dump_flags);
 
-  cfg_layout_finalize ();
   if (flag_reorder_blocks_and_partition)
     verify_hot_cold_block_grouping ();
 }
@@ -1976,6 +1974,8 @@ insert_section_boundary_note (void)
 static bool
 gate_duplicate_computed_gotos (void)
 {
+  if (targetm.cannot_modify_jumps_p ())
+    return false;
   return (optimize > 0 && flag_expensive_optimizations && !optimize_size);
 }
 
@@ -1990,9 +1990,6 @@ duplicate_computed_gotos (void)
   if (n_basic_blocks <= NUM_FIXED_BLOCKS + 1)
     return 0;
 
-  if (targetm.cannot_modify_jumps_p ())
-    return 0;
-
   cfg_layout_initialize (0);
 
   /* We are estimating the length of uncond jump insn only once
@@ -2198,6 +2195,8 @@ partition_hot_cold_basic_blocks (void)
 static bool
 gate_handle_reorder_blocks (void)
 {
+  if (targetm.cannot_modify_jumps_p ())
+    return false;
   return (optimize > 0);
 }
 
@@ -2206,34 +2205,39 @@ gate_handle_reorder_blocks (void)
 static unsigned int
 rest_of_handle_reorder_blocks (void)
 {
-  bool changed;
   unsigned int liveness_flags;
+  basic_block bb;
 
   /* Last attempt to optimize CFG, as scheduling, peepholing and insn
      splitting possibly introduced more crossjumping opportunities.  */
   liveness_flags = (!HAVE_conditional_execution ? CLEANUP_UPDATE_LIFE : 0);
-  changed = cleanup_cfg (CLEANUP_EXPENSIVE | liveness_flags);
+  cfg_layout_initialize (CLEANUP_EXPENSIVE | liveness_flags);
 
   if (flag_sched2_use_traces && flag_schedule_insns_after_reload)
     {
       timevar_push (TV_TRACER);
-      tracer (liveness_flags);
+      tracer ();
       timevar_pop (TV_TRACER);
     }
 
   if (flag_reorder_blocks || flag_reorder_blocks_and_partition)
-    reorder_basic_blocks (liveness_flags);
+    reorder_basic_blocks ();
   if (flag_reorder_blocks || flag_reorder_blocks_and_partition
       || (flag_sched2_use_traces && flag_schedule_insns_after_reload))
-    changed |= cleanup_cfg (CLEANUP_EXPENSIVE | liveness_flags);
+    cleanup_cfg (CLEANUP_EXPENSIVE | liveness_flags);
 
   /* On conditional execution targets we can not update the life cheaply, so
      we deffer the updating to after both cleanups.  This may lose some cases
      but should not be terribly bad.  */
-  if (changed && HAVE_conditional_execution)
+  if (HAVE_conditional_execution)
     update_life_info (NULL, UPDATE_LIFE_GLOBAL_RM_NOTES,
 		      PROP_DEATH_NOTES);
 
+  FOR_EACH_BB (bb)
+    if (bb->next_bb != EXIT_BLOCK_PTR)
+      bb->aux = bb->next_bb;
+  cfg_layout_finalize ();
+
   /* Add NOTE_INSN_SWITCH_TEXT_SECTIONS notes.  */
   insert_section_boundary_note ();
   return 0;
Index: reg-stack.c
===================================================================
--- reg-stack.c	(revision 122857)
+++ reg-stack.c	(working copy)
@@ -167,6 +167,7 @@
 #include "recog.h"
 #include "output.h"
 #include "basic-block.h"
+#include "cfglayout.h"
 #include "varray.h"
 #include "reload.h"
 #include "ggc.h"
@@ -3197,8 +3198,17 @@ rest_of_handle_stack_regs (void)
                        | (flag_crossjumping ? CLEANUP_CROSSJUMP : 0))
           && (flag_reorder_blocks || flag_reorder_blocks_and_partition))
         {
-          reorder_basic_blocks (0);
-          cleanup_cfg (CLEANUP_EXPENSIVE | CLEANUP_POST_REGSTACK);
+	  basic_block bb;
+
+	  cfg_layout_initialize (0);
+
+	  reorder_basic_blocks ();
+	  cleanup_cfg (CLEANUP_EXPENSIVE | CLEANUP_POST_REGSTACK);
+
+	  FOR_EACH_BB (bb)
+	    if (bb->next_bb != EXIT_BLOCK_PTR)
+	      bb->aux = bb->next_bb;
+	  cfg_layout_finalize ();
         }
     }
   else 
Index: basic-block.h
===================================================================
--- basic-block.h	(revision 122857)
+++ basic-block.h	(working copy)
@@ -929,7 +929,7 @@ extern bool control_flow_insn_p (rtx);
 extern rtx get_last_bb_insn (basic_block);
 
 /* In bb-reorder.c */
-extern void reorder_basic_blocks (unsigned int);
+extern void reorder_basic_blocks (void);
 
 /* In dominance.c */
 
@@ -976,6 +976,7 @@ unsigned bb_dom_dfs_out (enum cdi_direct
 
 extern edge try_redirect_by_replacing_jump (edge, basic_block, bool);
 extern void break_superblocks (void);
+extern void relink_block_chain (bool);
 extern void check_bb_profile (basic_block, FILE *);
 extern void update_bb_profile_for_threading (basic_block, int, gcov_type, edge);
 extern void init_rtl_bb_info (basic_block);
Index: passes.c
===================================================================
--- passes.c	(revision 122858)
+++ passes.c	(working copy)
@@ -666,7 +666,6 @@ init_optimization_passes (void)
       NEXT_PASS (pass_gcse);
       NEXT_PASS (pass_jump_bypass);
       NEXT_PASS (pass_rtl_ifcvt);
-      NEXT_PASS (pass_outof_cfg_layout_mode);
       NEXT_PASS (pass_tracer);
       /* Perform loop optimizations.  It might be better to do them a bit
 	 sooner, but we want the profile feedback to work more
@@ -685,6 +684,7 @@ init_optimization_passes (void)
       NEXT_PASS (pass_web);
       NEXT_PASS (pass_cse2);
       NEXT_PASS (pass_rtl_fwprop_addr);
+      NEXT_PASS (pass_outof_cfg_layout_mode);
       NEXT_PASS (pass_life);
       NEXT_PASS (pass_combine);
       NEXT_PASS (pass_if_after_combine);



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