# HG changeset patch
# User rkennke
# Date 1535744132 -7200
#      Fri Aug 31 21:35:32 2018 +0200
# Node ID 084797df87610fa89e9ccacaa5fa12b6c220d7d2
# Parent  83b0f4662e36b7f813410cdfa45a534e29638110
Add flag to switch between WB and RB-based acmp

diff --git a/src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.cpp b/src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.cpp
--- a/src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.cpp
+++ b/src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.cpp
@@ -773,7 +773,7 @@
 }
 
 Node* ShenandoahBarrierSetC2::cmpoop_cmp(GraphKit* kit, Node* a, Node* b) const {
-  if (ShenandoahAcmpBarrier && ShenandoahVerifyOptoBarriers) {
+  if (ShenandoahAcmpBarrier && (ShenandoahVerifyOptoBarriers || ShenandoahWBAcmpBarrier)) {
     a = kit->access_resolve_for_write(a);
     b = kit->access_resolve_for_write(b);
   }
@@ -801,7 +801,7 @@
   untaken_branch = kit->gvn().transform(untaken_branch);
 
   assert(taken_memory == NULL && untaken_memory == NULL, "unexpected memory inputs");
-  if (!UseShenandoahGC || !ShenandoahAcmpBarrier || ShenandoahVerifyOptoBarriers) {
+  if (!ShenandoahAcmpBarrier || ShenandoahVerifyOptoBarriers || ShenandoahWBAcmpBarrier) {
     return;
   }
   if (taken_branch->is_top() || untaken_branch->is_top()) {
diff --git a/src/hotspot/share/gc/shenandoah/shenandoah_globals.hpp b/src/hotspot/share/gc/shenandoah/shenandoah_globals.hpp
--- a/src/hotspot/share/gc/shenandoah/shenandoah_globals.hpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoah_globals.hpp
@@ -328,6 +328,9 @@
   diagnostic(bool, ShenandoahAcmpBarrier, true,                             \
           "Turn on/off acmp barriers in Shenandoah")                        \
                                                                             \
+  diagnostic(bool, ShenandoahWBAcmpBarrier, false,                          \
+          "Emit WB based acmp barrier, otherwise RB based acmp barrier")    \
+                                                                            \
   diagnostic(bool, ShenandoahCloneBarrier, true,                            \
           "Turn on/off clone barriers in Shenandoah")                       \
                                                                             \