final.c (compute_alignments): New function.

	* final.c (compute_alignments): New function.
	(init_insn_lengths): Do not care label_align.
	(LABEL_ALIGN_AFTER_BARRIER): Default to 1.
	(LABEL_ALIGN_AFTER_BARRIER_MAX_SKIP): Default to 0.
	(JUMP_ALIGN, JUMP_ALIGN_MAX_SKIP): New.
	(shorted_branches): Realloc label_align array; do
	not call init_insn_lengths; Do not care about loop alignments.
	* output.h (compute_alignments): Declare.
	* toplev.c (rest_of_compilation): Call compute_alignments.
	* tm.texi (JUMP_ALIGN, JUMP_ALIGN_MAX_SKIP): Document.

	* predict.c (block_info_def): Add npredecesors, remove nvisited;
	change visited to tovisit.
	(propagate_freq): Use faster traversing algorithm.
	(estimate_loops_at_level, estimate_bb_frequencies): Change visited
	to tovisit; reverse meaning.

	* predict.c (struct block_info_def): Remove nvisited.
	(propagate_freq): Use EDGE_DFS_BACK to detect irreducible regions.
	(estimate_bb_frequencies): Call mark_dfs_back_edges.

From-SVN: r45042

1 files changed, 123 insertions, 52 deletions

diff --git a/gcc/final.c b/gcc/final.c
index ec57842..ed4b6ff 100644
--- a/gcc/final.c
+++ b/gcc/final.c
@@ -643,11 +643,6 @@ static struct label_alignment *label_align;
 void
 init_insn_lengths ()
 {
-  if (label_align)
-    {
-      free (label_align);
-      label_align = 0;
-    }
   if (uid_shuid)
     {
       free (uid_shuid);
@@ -791,11 +786,19 @@ get_attr_length (insn)
 #endif
 
 #ifndef LABEL_ALIGN_AFTER_BARRIER
-#define LABEL_ALIGN_AFTER_BARRIER(LABEL) align_jumps_log
+#define LABEL_ALIGN_AFTER_BARRIER(LABEL) 1
 #endif
 
 #ifndef LABEL_ALIGN_AFTER_BARRIER_MAX_SKIP
-#define LABEL_ALIGN_AFTER_BARRIER_MAX_SKIP (align_jumps-1)
+#define LABEL_ALIGN_AFTER_BARRIER_MAX_SKIP 0
+#endif
+
+#ifndef JUMP_ALIGN
+#define JUMP_ALIGN(LABEL) align_jumps_log
+#endif
+
+#ifndef JUMP_ALIGN_MAX_SKIP
+#define JUMP_ALIGN_MAX_SKIP (align_jumps-1)
 #endif
 
 #ifndef ADDR_VEC_ALIGN
@@ -946,6 +949,88 @@ insn_current_reference_address (branch)
 }
 #endif /* HAVE_ATTR_length */
 
+void
+compute_alignments ()
+{
+  int i;
+  int log, max_skip, max_log;
+
+  if (label_align)
+    {
+      free (label_align);
+      label_align = 0;
+    }
+
+  max_labelno = max_label_num ();
+  min_labelno = get_first_label_num ();
+  label_align = (struct label_alignment *)
+    xcalloc (max_labelno - min_labelno + 1, sizeof (struct label_alignment));
+
+  /* If not optimizing or optimizing for size, don't assign any alignments.  */
+  if (optimize || optimize_size)
+    return;
+
+  for (i = 0; i < n_basic_blocks; i++)
+    {
+      basic_block bb = BASIC_BLOCK (i);
+      rtx label = bb->head;
+      int fallthru_frequency = 0, branch_frequency = 0, has_fallthru = 0;
+      edge e;
+
+      if (GET_CODE (label) != CODE_LABEL)
+	continue;
+      max_log = LABEL_ALIGN (label);
+      max_skip = LABEL_ALIGN_MAX_SKIP;
+
+      for (e = bb->pred; e; e = e->pred_next)
+	{
+	  if (e->flags & EDGE_FALLTHRU)
+	    has_fallthru = 1, fallthru_frequency += EDGE_FREQUENCY (e);
+	  else
+	    branch_frequency += EDGE_FREQUENCY (e);
+	}
+
+      /* There are two purposes to align block with no fallthru incomming edge:
+	 1) to avoid fetch stalls when branch destination is near cache boundary
+	 2) to improve cache effciency in case the previous block is not executed
+	    (so it does not need to be in the cache).
+
+	 We to catch first case, we align frequently executed blocks.
+	 To catch the second, we align blocks that are executed more frequently
+	 than the predecesor and the predecesor is likely to not be executed
+	 when function is called.  */
+
+      if (!has_fallthru
+	  && (branch_frequency > BB_FREQ_MAX / 10
+	      || (bb->frequency > BASIC_BLOCK (i - 1)->frequency * 10
+		  && (BASIC_BLOCK (i - 1)->frequency
+		      <= ENTRY_BLOCK_PTR->frequency / 2))))
+	{
+	  log = JUMP_ALIGN (label);
+	  if (max_log < log)
+	    {
+	      max_log = log;
+	      max_skip = JUMP_ALIGN_MAX_SKIP;
+	    }
+	}
+      /* In case block is frequent and reached mostly by non-fallthru edge,
+	 align it.  It is most likely an first block of loop.  */
+      if (has_fallthru
+	  && branch_frequency + fallthru_frequency > BB_FREQ_MAX / 10
+	  && branch_frequency > fallthru_frequency * 5)
+	{
+	  log = LOOP_ALIGN (label);
+	  if (max_log < log)
+	    {
+	      max_log = log;
+	      max_skip = LOOP_ALIGN_MAX_SKIP;
+	    }
+	}
+      LABEL_TO_ALIGNMENT (label) = max_log;
+      LABEL_TO_MAX_SKIP (label) = max_skip;
+    }
+}
+
 /* Make a pass over all insns and compute their actual lengths by shortening
    any branches of variable length if possible.  */
 
@@ -983,21 +1068,34 @@ shorten_branches (first)
 
 #endif
 
-  /* We must do some computations even when not actually shortening, in
-     order to get the alignment information for the labels.  */
-
-  init_insn_lengths ();
-
   /* Compute maximum UID and allocate label_align / uid_shuid.  */
   max_uid = get_max_uid ();
 
-  max_labelno = max_label_num ();
-  min_labelno = get_first_label_num ();
-  label_align = (struct label_alignment *)
-    xcalloc ((max_labelno - min_labelno + 1), sizeof (struct label_alignment));
-
   uid_shuid = (int *) xmalloc (max_uid * sizeof *uid_shuid);
 
+  if (max_labelno != max_label_num ())
+    {
+      int old = max_labelno;
+      int n_labels;
+      int n_old_labels;
+
+      max_labelno = max_label_num ();
+
+      n_labels = max_labelno - min_labelno + 1;
+      n_old_labels = old - min_labelno + 1;
+
+      label_align = (struct label_alignment *) xrealloc
+	(label_align, n_labels * sizeof (struct label_alignment));
+
+      /* Range of labels grows monotonically in the function.  Abort here
+         means that the initialization of array got lost.  */
+      if (n_old_labels > n_labels)
+	abort ();
+
+      memset (label_align + n_old_labels, 0,
+	      (n_labels - n_old_labels) * sizeof (struct label_alignment));
+    }
+
   /* Initialize label_align and set up uid_shuid to be strictly
      monotonically rising with insn order.  */
   /* We use max_log here to keep track of the maximum alignment we want to
@@ -1023,6 +1121,14 @@ shorten_branches (first)
       else if (GET_CODE (insn) == CODE_LABEL)
 	{
 	  rtx next;
+	  
+	  /* Merge in alignments computed by compute_alignments.  */
+	  log = LABEL_TO_ALIGNMENT (insn);
+	  if (max_log < log)
+	    {
+	      max_log = log;
+	      max_skip = LABEL_TO_MAX_SKIP (insn);
+	    }
 
 	  log = LABEL_ALIGN (insn);
 	  if (max_log < log)
@@ -1074,41 +1180,6 @@ shorten_branches (first)
 		break;
 	      }
 	}
-      /* Again, we allow NOTE_INSN_LOOP_BEG - INSN - CODE_LABEL
-	 sequences in order to handle reorg output efficiently.  */
-      else if (GET_CODE (insn) == NOTE
-	       && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
-	{
-	  rtx label;
-	  int nest = 0;
-
-	  /* Search for the label that starts the loop.
-	     Don't skip past the end of the loop, since that could
-	     lead to putting an alignment where it does not belong.
-	     However, a label after a nested (non-)loop would be OK.  */
-	  for (label = insn; label; label = NEXT_INSN (label))
-	    {
-	      if (GET_CODE (label) == NOTE
-		  && NOTE_LINE_NUMBER (label) == NOTE_INSN_LOOP_BEG)
-		nest++;
-	      else if (GET_CODE (label) == NOTE
-		       && NOTE_LINE_NUMBER (label) == NOTE_INSN_LOOP_END
-		       && --nest == 0)
-		break;
-	      else if (GET_CODE (label) == CODE_LABEL)
-		{
-		  log = LOOP_ALIGN (label);
-		  if (max_log < log)
-		    {
-		      max_log = log;
-		      max_skip = LOOP_ALIGN_MAX_SKIP;
-		    }
-		  break;
-		}
-	    }
-	}
-      else
-	continue;
     }
 #ifdef HAVE_ATTR_length