[committed] Print estimate usage and estimation error with --devel-trace

[committed] Print estimate usage and estimation error with --devel-trace

[Tom de Vries]

Hi,

Be verbose in --devel-trace about using estimates, and print actual DIE count
together with estimation error.

Changes for low-mem mode:
...
 $ dwz cc1 -o 1 --devel-trace
 Compressing cc1
+Using die count estimate 10138840 to decide whether to count DIEs: yes
 Counting DIEs
 Hit low-mem die-limit
 Compressing cc1 in low-mem mode
 htab: off_htab allocation
       size: 131071
+Die count: 10188941, 100.49% of estimate
 htab: off_htab post-parsing
       size: 16777213
       elements (incl. deleted): 6536209, occupancy: 0.389588
       elements (excl. deleted): 1760770, occupancy: 0.104950
       searches: 47219770, collisions: 0.134397
 htab: off_htab final
       size: 16777213
       elements (incl. deleted): 6536209, occupancy: 0.389588
       elements (excl. deleted): 1760770, occupancy: 0.104950
       searches: 75171859, collisions: 0.310610
...

Changes for regular mode:
...
 $ dwz cc1 -o 1 --devel-trace -lnone
 Compressing cc1
+Using die count estimate 10138840 to decide whether to count DIEs: no
+Using die count estimate 10138840 for off_htab allocation
 htab: off_htab allocation
       size: 16777213
+Die count: 10188941, 100.49% of estimate
 htab: off_htab post-parsing
       size: 16777213
       elements: 10188941, occupancy: 0.607308
       searches: 27075041, collisions: 0.207744
 htab: off_htab final
       size: 16777213
       elements: 10188941, occupancy: 0.607308
       searches: 34256212, collisions: 0.206357
...

Committed to trunk.

Thanks,
- Tom

Print estimate usage and estimation error with --devel-trace

2019-11-28  Tom de Vries  <tdevries@suse.de>

	* dwz.c (off_htab_add_die): Print when using estimate.
	(read_debug_info): Same. Also keep ndies count for op_multifile.  Print
	total die count, and estimation error.

---
 dwz.c | 43 ++++++++++++++++++++++++++++++++++---------
 1 file changed, 34 insertions(+), 9 deletions(-)

diff --git a/dwz.c b/dwz.c
index e4b2548..3c886d6 100644
--- a/dwz.c
+++ b/dwz.c
@@ -1335,11 +1335,21 @@ off_htab_add_die (dw_cu_ref cu, dw_die_ref die, unsigned int *die_count)
 	{
 	  size_t nr_dies;
 	  if (die_count && *die_count != 0)
-	    nr_dies = *die_count;
+	    {
+	      nr_dies = *die_count;
+	      if (tracing)
+		fprintf (stderr, "Using die count %zu for off_htab"
+			 " allocation\n", nr_dies);
+	    }
 	  else if (die_count_method == none)
 	    nr_dies = 0;
 	  else if (die_count_method == estimate)
-	    nr_dies = estimated_nr_dies;
+	    {
+	      nr_dies = estimated_nr_dies;
+	      if (tracing)
+		fprintf (stderr, "Using die count estimate %zu for off_htab"
+			 " allocation\n", nr_dies);
+	    }
 	  else
 	    assert (false);
 
@@ -5118,13 +5128,20 @@ read_debug_info (DSO *dso, int kind, unsigned int *die_count)
   unsigned int estimated_nr_dies = estimate_nr_dies ();
   if (kind == DEBUG_INFO
       && multifile_mode == 0
-      && die_count_method == estimate
-      && (estimated_nr_dies > max_die_limit
-	  || estimated_nr_dies > low_mem_die_limit))
+      && die_count_method == estimate)
     {
-      int try_ret = try_debug_info (dso);
-      if (try_ret != 0)
-	return try_ret;
+      bool do_count = (estimated_nr_dies > max_die_limit
+		       || estimated_nr_dies > low_mem_die_limit);
+      if (tracing)
+	fprintf (stderr, "Using die count estimate %u to decide whether to"
+		 " count DIEs: %s\n", estimated_nr_dies,
+		 do_count ? "yes" : "no");
+      if (do_count)
+	{
+	  int try_ret = try_debug_info (dso);
+	  if (try_ret != 0)
+	    return try_ret;
+	}
     }
 
   if (likely (!fi_multifile && kind != DEBUG_TYPES))
@@ -5383,8 +5400,8 @@ read_debug_info (DSO *dso, int kind, unsigned int *die_count)
 		  ret = 2;
 		  goto fail;
 		}
-	      ndies++;
 	    }
+	  ndies++;
 	  if (unlikely (low_mem_phase1))
 	    die = &die_buf;
 	  else if (parent == NULL
@@ -5740,6 +5757,14 @@ read_debug_info (DSO *dso, int kind, unsigned int *die_count)
       return 0;
     }
 
+  if (tracing)
+    {
+      if (op_multifile)
+	fprintf (stderr, "Die count: %u\n", ndies);
+      else
+	fprintf (stderr, "Die count: %u, %.2f%% of estimate\n", ndies,
+		 (double)ndies / ((double)estimated_nr_dies / 100));
+    }
   if (tracing)
     htab_report (off_htab, "off_htab post-parsing");
   if (die_count)