From: DRC <dcommander@users.sourceforge.net>
Date: Wed, 13 Jun 2012 01:23:09 +0000 (+0000)
Subject: Eliminate the use of the MASKMOVDQU instruction, to speed up decompression performanc... 
X-Git-Tag: 1.2.90~58
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=66fe68b0b28ec18000f6a863bb9ad59c56ce81d7;p=libjpeg-turbo

Eliminate the use of the MASKMOVDQU instruction, to speed up decompression performance by 10x on AMD Bobcat embedded processors (and ~5% on AMD desktop processors.)


git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@836 632fc199-4ca6-4c93-a231-07263d6284db
---

66fe68b0b28ec18000f6a863bb9ad59c56ce81d7
diff --cc ChangeLog.txt
index d4808e8,e80ac6c..5453869
--- a/ChangeLog.txt
+++ b/ChangeLog.txt
@@@ -34,9 -19,13 +34,16 @@@ calling conventions
  images (specifically, images in which the component count was erroneously set
  to a large value) would cause libjpeg-turbo to segfault.
  
 -[5] Worked around a severe performance issue with "Bobcat" (AMD Embedded APU)
 +[8] Extended the TurboJPEG Java API so that it can be used to decompress a
 +JPEG image into an arbitrary position in a large output buffer.
 +
++[9] Worked around a severe performance issue with "Bobcat" (AMD Embedded APU)
+ processors.  The MASKMOVDQU instruction, which was used by the libjpeg-turbo
+ SSE2 SIMD code, is apparently implemented in microcode on AMD processors, and
+ it is painfully slow on Bobcat processors in particular.  Eliminating the use
+ of this instruction improved performance by an order of magnitude on Bobcat
+ processors and by a small amount (typically 5%) on AMD desktop processors.
+ 
  
  1.2.0
  =====