This is a small optimization, the reversed order of the walk of 
update_cache_list queue.
The queue is pushed in Pre-order/NLR, reversing the order will reduce how many 
times we
need to go through the loop as we update the nodes which might have a link back 
to another
one first.

Bootstrapped and tested on x86_64-linux-gnu.

gcc/ChangeLog:

        * cfgexpand.cc (vars_ssa_cache::operator()): Reverse the order of the 
going
        through the update list.

Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
---
 gcc/cfgexpand.cc | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/gcc/cfgexpand.cc b/gcc/cfgexpand.cc
index 2b27076658f..0e76d340d26 100644
--- a/gcc/cfgexpand.cc
+++ b/gcc/cfgexpand.cc
@@ -804,9 +804,11 @@ vars_ssa_cache::operator() (tree name)
   bool changed;
   do {
     changed = false;
-    for (auto &e : update_cache_list)
+    unsigned int i;
+    std::pair<tree,tree> *e;
+    FOR_EACH_VEC_ELT_REVERSE (update_cache_list, i, e)
       {
-       if (update (e.second, e.first))
+       if (update (e->second, e->first))
          changed = true;
       }
   } while (changed);
-- 
2.43.0

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