Re: [patch] Accelerate blocks sorting

[Jan Kratochvil <jan.kratochvil@redhat.com>]

On Mon, 22 Jun 2009 21:26:37 +0200, Tom Tromey wrote:
> Yeah.  It isn't the return, but the splitting.

I see it now, thanks for looking it up.

Checked-in.


Thanks,
Jan


http://sourceware.org/ml/gdb-cvs/2009-06/msg00135.html

--- src/gdb/ChangeLog	2009/06/22 18:17:01	1.10619
+++ src/gdb/ChangeLog	2009/06/22 19:50:10	1.10620
@@ -1,4 +1,10 @@
-2009-05-07  Sami Wagiaalla  <swagiaal@redhat.com>
+2009-06-22  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
+	PR gdb/9988:
+	* buildsym.c (block_compar): New function.
+	(end_symtab): Replace the bubble sort by a qsort based code.
+
+2009-06-22  Sami Wagiaalla  <swagiaal@redhat.com>
 
 	* MAINTAINERS (Write After Approval): Add self.
 
--- src/gdb/buildsym.c	2009/06/17 18:41:50	1.71
+++ src/gdb/buildsym.c	2009/06/22 19:50:10	1.72
@@ -899,6 +899,19 @@
     }
 }
 
+/* Helper function for qsort.  Parametes are `struct block *' pointers,
+   function sorts them in descending order by their BLOCK_START.  */
+
+static int
+block_compar (const void *ap, const void *bp)
+{
+  const struct block *a = *(const struct block **) ap;
+  const struct block *b = *(const struct block **) bp;
+
+  return ((BLOCK_START (b) > BLOCK_START (a))
+	  - (BLOCK_START (b) < BLOCK_START (a)));
+}
+
 /* Finish the symbol definitions for one main source file, close off
    all the lexical contexts for that file (creating struct block's for
    them), then make the struct symtab for that file and put it in the
@@ -952,32 +965,28 @@
      OBJF_REORDERED is true, then sort the pending blocks.  */
   if ((objfile->flags & OBJF_REORDERED) && pending_blocks)
     {
-      /* FIXME!  Remove this horrid bubble sort and use merge sort!!! */
-      int swapped;
-      do
-	{
-	  struct pending_block *pb, *pbnext;
+      unsigned count = 0;
+      struct pending_block *pb;
+      struct block **barray, **bp;
+      struct cleanup *back_to;
 
-	  pb = pending_blocks;
-	  pbnext = pb->next;
-	  swapped = 0;
+      for (pb = pending_blocks; pb != NULL; pb = pb->next)
+	count++;
 
-	  while (pbnext)
-	    {
-	      /* swap blocks if unordered! */
+      barray = xmalloc (sizeof (*barray) * count);
+      back_to = make_cleanup (xfree, barray);
 
-	      if (BLOCK_START (pb->block) < BLOCK_START (pbnext->block))
-		{
-		  struct block *tmp = pb->block;
-		  pb->block = pbnext->block;
-		  pbnext->block = tmp;
-		  swapped = 1;
-		}
-	      pb = pbnext;
-	      pbnext = pbnext->next;
-	    }
-	}
-      while (swapped);
+      bp = barray;
+      for (pb = pending_blocks; pb != NULL; pb = pb->next)
+	*bp++ = pb->block;
+
+      qsort (barray, count, sizeof (*barray), block_compar);
+
+      bp = barray;
+      for (pb = pending_blocks; pb != NULL; pb = pb->next)
+	pb->block = *bp++;
+
+      do_cleanups (back_to);
     }
 
   /* Cleanup any undefined types that have been left hanging around