src/hotspot/share/opto/shenandoahSupport.cpp

rev 47953 : Implement flag to generate write-barriers without membars.

@@ -646,14 +646,16 @@
 }
 
 Node* ShenandoahWriteBarrierNode::evacuation_in_progress_test_ctrl(Node* iff) {
   assert(is_evacuation_in_progress_test(iff), "bad input");
   Node* c = iff;
+  if (ShenandoahWriteBarrierMemBar) {
   do {
     assert(c->in(0)->is_Proj() && c->in(0)->in(0)->is_MemBar(), "where's the mem bar?");
     c = c->in(0)->in(0);
   } while (c->adr_type() != TypeRawPtr::BOTTOM);
+  }
   return c->in(0);
 }
 
 bool ShenandoahBarrierNode::dominates_memory_impl(PhaseGVN* phase,
                                                   Node* b1,

@@ -3530,10 +3532,11 @@
   debug_only(gc_state_adr_type = phase->C->get_adr_type(gc_state_idx));
 
   Node* gc_state = new LoadUBNode(ctrl, raw_mem, gc_state_addr, gc_state_adr_type, TypeInt::BYTE, MemNode::unordered);
   phase->register_new_node(gc_state, ctrl);
 
+  if (ShenandoahWriteBarrierMemBar) {
   Node* mb = MemBarNode::make(phase->C, Op_MemBarAcquire, Compile::AliasIdxRaw);
   mb->init_req(TypeFunc::Control, ctrl);
   mb->init_req(TypeFunc::Memory, raw_mem);
   phase->register_control(mb, loop, ctrl);
   Node* ctrl_proj = new ProjNode(mb,TypeFunc::Control);

@@ -3548,18 +3551,22 @@
   ctrl_proj = new ProjNode(mb,TypeFunc::Control);
   phase->register_control(ctrl_proj, loop, mb);
   wb_mem = new ProjNode(mb,TypeFunc::Memory);
   phase->register_new_node(wb_mem, mb);
 
-  Node* evacuation_in_progress = new AndINode(gc_state, phase->igvn().intcon(ShenandoahHeap::EVACUATION));
-  phase->register_new_node(evacuation_in_progress, ctrl_proj);
+    ctrl = ctrl_proj;
+  }
+
+  Node* evacuation_in_progress = gc_state;
+  evacuation_in_progress = new AndINode(gc_state, phase->igvn().intcon(ShenandoahHeap::EVACUATION));
+  phase->register_new_node(evacuation_in_progress, ctrl);
   Node* evacuation_in_progress_cmp = new CmpINode(evacuation_in_progress, phase->igvn().zerocon(T_INT));
-  phase->register_new_node(evacuation_in_progress_cmp, ctrl_proj);
+  phase->register_new_node(evacuation_in_progress_cmp, ctrl);
   Node* evacuation_in_progress_test = new BoolNode(evacuation_in_progress_cmp, BoolTest::ne);
-  phase->register_new_node(evacuation_in_progress_test, ctrl_proj);
-  evacuation_iff = new IfNode(ctrl_proj, evacuation_in_progress_test, PROB_UNLIKELY(0.999), COUNT_UNKNOWN);
-  phase->register_control(evacuation_iff, loop, ctrl_proj);
+  phase->register_new_node(evacuation_in_progress_test, ctrl);
+  evacuation_iff = new IfNode(ctrl, evacuation_in_progress_test, PROB_UNLIKELY(0.999), COUNT_UNKNOWN);
+  phase->register_control(evacuation_iff, loop, ctrl);
 
   assert(is_evacuation_in_progress_test(evacuation_iff), "Should match the shape");
   assert(is_gc_state_load(gc_state), "Should match the shape");
 
   evac_not_in_progress = new IfFalseNode(evacuation_iff);

@@ -3969,10 +3976,11 @@
 
 void ShenandoahWriteBarrierNode::move_evacuation_test_out_of_loop(IfNode* iff, PhaseIdealLoop* phase) {
   // move test and its mem barriers out of the loop
   assert(is_evacuation_in_progress_test(iff), "inconsistent");
 
+  if (ShenandoahWriteBarrierMemBar) {
   IdealLoopTree *loop = phase->get_loop(iff);
   Node* loop_head = loop->_head;
   Node* entry_c = loop_head->in(LoopNode::EntryControl);
   IdealLoopTree *entry_loop = phase->get_loop(entry_c);
 

@@ -4043,13 +4051,25 @@
     }
     c = next;
   }
 
   assert(phase->is_dominator(phase->get_ctrl(load->in(MemNode::Address)), entry_c), "address not out of loop?");
+  } else {
+    IdealLoopTree *loop = phase->get_loop(iff);
+    Node* loop_head = loop->_head;
+    Node* entry_c = loop_head->in(LoopNode::EntryControl);
+
+    Node* load = iff->in(1)->in(1)->in(1);
+    assert(load->Opcode() == Op_LoadUB, "inconsistent");
+    Node* mem_ctrl = NULL;
+  }
 }
 
 void ShenandoahWriteBarrierNode::backtoback_evacs(IfNode* iff, IfNode* dom_if, PhaseIdealLoop* phase) {
+  if (!ShenandoahWriteBarrierMemBar) {
+    return;
+  }
   // move all mem barriers from this evac test to the dominating one,
   // removing duplicates in the process
   IdealLoopTree *loop = phase->get_loop(dom_if);
   Node* c1 = iff->in(0);
   Node* mb1 = NULL;