free empty blocks at the end of GC

[ghc-hetmet.git] / rts / sm / GC.c

diff --git a/rts/sm/GC.c b/rts/sm/GC.c
index cb2f040..97b32b6 100644 (file)
--- a/rts/sm/GC.c
+++ b/rts/sm/GC.c
@@ -410,7 +410,7 @@ GarbageCollect ( rtsBool force_major_gc )
   {
       gc_thread *thr;
       step_workspace *ws;
-      bdescr *prev;
+      bdescr *prev, *next;
 
       for (t = 0; t < n_gc_threads; t++) {
          thr = gc_threads[t];
@@ -418,37 +418,50 @@ GarbageCollect ( rtsBool force_major_gc )
           // not step 0
           for (s = 1; s < total_steps; s++) {
               ws = &thr->steps[s];
-              // Not true?
-              // ASSERT( ws->scan_bd == ws->todo_bd );
-              ASSERT( ws->scan_bd ? ws->scan_bd->u.scan == ws->scan_bd->free : 1 );
 
               // Push the final block
-              if (ws->scan_bd) { push_scanned_block(ws->scan_bd, ws); }
-              
+              if (ws->todo_bd) { 
+                  push_scanned_block(ws->todo_bd, ws);
+              }
+
+              ASSERT(gct->scan_bd == NULL);
               ASSERT(countBlocks(ws->scavd_list) == ws->n_scavd_blocks);
               
-              prev = ws->part_list;
-              for (bd = ws->part_list; bd != NULL; bd = bd->link) {
+              prev = NULL;
+              for (bd = ws->scavd_list; bd != NULL; bd = bd->link) {
                   bd->flags &= ~BF_EVACUATED;   // now from-space 
                   ws->step->n_words += bd->free - bd->start;
                   prev = bd;
               }
               if (prev != NULL) {
-                  prev->link = ws->scavd_list;
-              }
-              for (bd = ws->scavd_list; bd != NULL; bd = bd->link) {
-                  bd->flags &= ~BF_EVACUATED;   // now from-space 
-                  ws->step->n_words += bd->free - bd->start;
-                  prev = bd;
+                  prev->link = ws->step->blocks;
+                  ws->step->blocks = ws->scavd_list;
+              } 
+              ws->step->n_blocks += ws->n_scavd_blocks;
+
+              prev = NULL;
+              for (bd = ws->part_list; bd != NULL; bd = next) {
+                  next = bd->link;
+                  if (bd->free == bd->start) {
+                      if (prev == NULL) {
+                          ws->part_list = next;
+                      } else {
+                          prev->link = next;
+                      }
+                      freeGroup(bd);
+                      ws->n_part_blocks--;
+                  } else {
+                      bd->flags &= ~BF_EVACUATED;       // now from-space 
+                      ws->step->n_words += bd->free - bd->start;
+                      prev = bd;
+                  }
               }
-              prev->link = ws->step->blocks;
-              if (ws->part_list != NULL) {
+              if (prev != NULL) {
+                  prev->link = ws->step->blocks;
                   ws->step->blocks = ws->part_list;
-              } else {
-                  ws->step->blocks = ws->scavd_list;
               }
               ws->step->n_blocks += ws->n_part_blocks;
-              ws->step->n_blocks += ws->n_scavd_blocks;
+
               ASSERT(countBlocks(ws->step->blocks) == ws->step->n_blocks);
               ASSERT(countOccupied(ws->step->blocks) == ws->step->n_words);
          }
@@ -1011,8 +1024,6 @@ alloc_gc_thread (int n)
         ASSERT(s == ws->step->abs_no);
         ws->gct = t;
         
-        ws->scan_bd = NULL;
-
         ws->todo_bd = NULL;
         ws->buffer_todo_bd = NULL;
         
@@ -1341,8 +1352,6 @@ init_collected_gen (nat g, nat n_threads)
 
            ws = &gc_threads[t]->steps[g * RtsFlags.GcFlags.steps + s];
 
-           ws->scan_bd = NULL;
-
            ws->todo_large_objects = NULL;
 
             ws->part_list = NULL;
@@ -1405,15 +1414,11 @@ init_uncollected_gen (nat g, nat threads)
                stp->n_blocks -= 1;
                 stp->n_words -= ws->todo_bd->free - ws->todo_bd->start;
                ws->todo_bd->link = NULL;
-
-               // this block is also the scan block; we must scan
-               // from the current end point.
-               ws->scan_bd = ws->todo_bd;
-               ws->scan_bd->u.scan = ws->scan_bd->free;
+               // we must scan from the current end point.
+               ws->todo_bd->u.scan = ws->todo_bd->free;
            } 
            else
            {
-               ws->scan_bd = NULL;
                ws->todo_bd = NULL;
                alloc_todo_block(ws,0);
            }
@@ -1442,6 +1447,7 @@ init_gc_thread (gc_thread *t)
 {
     t->static_objects = END_OF_STATIC_LIST;
     t->scavenged_static_objects = END_OF_STATIC_LIST;
+    t->scan_bd = NULL;
     t->evac_step = 0;
     t->failed_to_evac = rtsFalse;
     t->eager_promotion = rtsTrue;