{patch tree-ssa-math-opts]: Change searching direction for bswap

[Kai Tietz]

Hello,

this is the separated patch for issues noticed by doing type-sinking on 
bitwise-operations.  The tests exposed that bswap pattern-matching searches 
from top to down for each BB. As it replaces the found match for a bswap in 
tree, but doesn't know about handling its inserted builtin-swap on 
pattern-matching for wider-mode bswap, search failed.
By reversing search order within BB from last to first, this issue can be fixed.

ChangeLog

2011-06-27  Kai Tietz  <kti...@redhat.com>

        * tree-ssa-math-opts.c (execute_optimize_bswap): Search
        within BB from last to first.

Bootstrapped and regression-tested for x86_64-pc-linux-gnu. Ok for apply?

Regards,
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
@@ -1820,8 +1820,10 @@ execute_optimize_bswap (void)
   FOR_EACH_BB (bb)
     {
       gimple_stmt_iterator gsi;
-
+/*
       for (gsi = gsi_after_labels (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ */
+      for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi); gsi_prev (&gsi))
         {
          gimple stmt = gsi_stmt (gsi);
          tree bswap_src, bswap_type;