From patchwork Tue Jun 28 09:29:06 2011
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Subject: {patch tree-ssa-math-opts]: Change searching direction for bswap
Date: Mon, 27 Jun 2011 23:29:06 -0000
From: Kai Tietz <ktietz@redhat.com>
X-Patchwork-Id: 102343
Message-Id: <557542071.809365.1309253346481.JavaMail.root@zmail06.collab.prod.int.phx2.redhat.com>
To: Richard Guenther <richard.guenther@gmail.com>
Cc: gcc-patches@gcc.gnu.org

Oh, missed to fill comment.

Thanks,
Kai


Index: gcc-head/gcc/tree-ssa-math-opts.c
===================================================================
--- gcc-head.orig/gcc/tree-ssa-math-opts.c
+++ gcc-head/gcc/tree-ssa-math-opts.c
@@ -1821,7 +1821,11 @@ execute_optimize_bswap (void)
     {
       gimple_stmt_iterator gsi;

-      for (gsi = gsi_after_labels (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+      /* We scan for bswap patterns reverse for making sure we get
+        widest match.  As bswap pattern matching doesn't handle
+        previously inserted smaller bswap replacements as sub-
+        patterns, the wider variant wouldn't be detected.  */
+      for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi); gsi_prev (&gsi))
         {
          gimple stmt = gsi_stmt (gsi);
          tree bswap_src, bswap_type;