From: Ken Brown <kbrown@cornell.edu>
Date: Tue, 4 Mar 2014 19:02:49 +0000 (-0500)
Subject: Further follow-up to last change in gmalloc.c.
X-Git-Tag: emacs-24.3.90~288
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=94a089b5f873837a369a176c114430e0fd0bee05;p=emacs.git

Further follow-up to last change in gmalloc.c.

* src/gmalloc.c (aligned_alloc): Clarify the code by making `adj'
represent the actual adjustment needed for alignment.
---

diff --git a/src/ChangeLog b/src/ChangeLog
index 8aa6379ee7e..2f599191548 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2014-03-04  Ken Brown  <kbrown@cornell.edu>
+
+	* gmalloc.c (aligned_alloc): Clarify the code by making `adj'
+	represent the actual adjustment needed for alignment.
+
 2014-03-04  Eli Zaretskii  <eliz@gnu.org>
 
 	* gmalloc.c (aligned_alloc): Don't allocate more memory than
diff --git a/src/gmalloc.c b/src/gmalloc.c
index 9fd62407285..977abbdbbbd 100644
--- a/src/gmalloc.c
+++ b/src/gmalloc.c
@@ -1597,34 +1597,34 @@ aligned_alloc (size_t alignment, size_t size)
 
   /* Figure out how much we will need to pad this particular block
      to achieve the required alignment.  */
-  adj = (uintptr_t) result % alignment;
-  if (adj == 0)
-    adj = alignment;
+  adj = alignment - (uintptr_t) result % alignment;
+  if (adj == alignment)
+    adj = 0;
 
-  if (adj != 1)
+  if (adj != alignment - 1)
     {
       do
 	{
 	  /* Reallocate the block with only as much excess as it
 	     needs.  */
 	  free (result);
-	  result = malloc (size + alignment - adj);
+	  result = malloc (size + adj);
 	  if (result == NULL)	/* Impossible unless interrupted.  */
 	    return NULL;
 
 	  lastadj = adj;
-	  adj = (uintptr_t) result % alignment;
-	  if (adj == 0)
-	    adj = alignment;
+	  adj = alignment - (uintptr_t) result % alignment;
+	  if (adj == alignment)
+	    adj = 0;
 	  /* It's conceivable we might have been so unlucky as to get
 	     a different block with weaker alignment.  If so, this
 	     block is too short to contain SIZE after alignment
 	     correction.  So we must try again and get another block,
 	     slightly larger.  */
-	} while (adj < lastadj);
+	} while (adj > lastadj);
     }
 
-  if (adj != alignment)
+  if (adj != 0)
     {
       /* Record this block in the list of aligned blocks, so that `free'
 	 can identify the pointer it is passed, which will be in the middle
@@ -1648,7 +1648,7 @@ aligned_alloc (size_t alignment, size_t size)
       if (l != NULL)
 	{
 	  l->exact = result;
-	  result = l->aligned = (char *) result + alignment - adj;
+	  result = l->aligned = (char *) result + adj;
 	}
       UNLOCK_ALIGNED_BLOCKS ();
       if (l == NULL)