# HG changeset patch
# Parent  0bb101fbeb10f30b5bec553e8764fb921785210c
changeset:   59269:3567a8e78430
tag:         tip
parent:      59261:fc072587a25c
user:        roland
date:        Wed May 13 14:20:30 2020 +0200
summary:     Remove null-handling in LRB expansion

diff -r 0bb101fbeb10 src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.cpp
--- a/src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.cpp	Wed May 13 09:36:12 2020 +0000
+++ b/src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.cpp	Wed May 13 20:43:12 2020 +0200
@@ -483,14 +483,14 @@
 
 const TypeFunc* ShenandoahBarrierSetC2::shenandoah_load_reference_barrier_Type() {
   const Type **fields = TypeTuple::fields(2);
-  fields[TypeFunc::Parms+0] = TypeInstPtr::NOTNULL; // original field value
+  fields[TypeFunc::Parms+0] = TypeOopPtr::BOTTOM; // original field value
   fields[TypeFunc::Parms+1] = TypeRawPtr::BOTTOM;   // original load address
 
   const TypeTuple *domain = TypeTuple::make(TypeFunc::Parms+2, fields);
 
   // create result type (range)
   fields = TypeTuple::fields(1);
-  fields[TypeFunc::Parms+0] = TypeInstPtr::NOTNULL;
+  fields[TypeFunc::Parms+0] = TypeOopPtr::BOTTOM;
   const TypeTuple *range = TypeTuple::make(TypeFunc::Parms+1, fields);
 
   return TypeFunc::make(domain, range);
diff -r 0bb101fbeb10 src/hotspot/share/gc/shenandoah/c2/shenandoahSupport.cpp
--- a/src/hotspot/share/gc/shenandoah/c2/shenandoahSupport.cpp	Wed May 13 09:36:12 2020 +0000
+++ b/src/hotspot/share/gc/shenandoah/c2/shenandoahSupport.cpp	Wed May 13 20:43:12 2020 +0200
@@ -919,76 +919,6 @@
   }
 }
 
-Node* ShenandoahBarrierC2Support::clone_null_check(Node*& c, Node* val, Node* unc_ctrl, PhaseIdealLoop* phase) {
-  IdealLoopTree *loop = phase->get_loop(c);
-  Node* iff = unc_ctrl->in(0);
-  assert(iff->is_If(), "broken");
-  Node* new_iff = iff->clone();
-  new_iff->set_req(0, c);
-  phase->register_control(new_iff, loop, c);
-  Node* iffalse = new IfFalseNode(new_iff->as_If());
-  phase->register_control(iffalse, loop, new_iff);
-  Node* iftrue = new IfTrueNode(new_iff->as_If());
-  phase->register_control(iftrue, loop, new_iff);
-  c = iftrue;
-  const Type *t = phase->igvn().type(val);
-  assert(val->Opcode() == Op_CastPP, "expect cast to non null here");
-  Node* uncasted_val = val->in(1);
-  val = new CastPPNode(uncasted_val, t);
-  val->init_req(0, c);
-  phase->register_new_node(val, c);
-  return val;
-}
-
-void ShenandoahBarrierC2Support::fix_null_check(Node* unc, Node* unc_ctrl, Node* new_unc_ctrl,
-                                                Unique_Node_List& uses, PhaseIdealLoop* phase) {
-  IfNode* iff = unc_ctrl->in(0)->as_If();
-  Node* proj = iff->proj_out(0);
-  assert(proj != unc_ctrl, "bad projection");
-  Node* use = proj->unique_ctrl_out();
-
-  assert(use == unc || use->is_Region(), "what else?");
-
-  uses.clear();
-  if (use == unc) {
-    phase->set_idom(use, new_unc_ctrl, phase->dom_depth(use));
-    for (uint i = 1; i < unc->req(); i++) {
-      Node* n = unc->in(i);
-      if (phase->has_ctrl(n) && phase->get_ctrl(n) == proj) {
-        uses.push(n);
-      }
-    }
-  } else {
-    assert(use->is_Region(), "what else?");
-    uint idx = 1;
-    for (; use->in(idx) != proj; idx++);
-    for (DUIterator_Fast imax, i = use->fast_outs(imax); i < imax; i++) {
-      Node* u = use->fast_out(i);
-      if (u->is_Phi() && phase->get_ctrl(u->in(idx)) == proj) {
-        uses.push(u->in(idx));
-      }
-    }
-  }
-  for(uint next = 0; next < uses.size(); next++ ) {
-    Node *n = uses.at(next);
-    assert(phase->get_ctrl(n) == proj, "bad control");
-    phase->set_ctrl_and_loop(n, new_unc_ctrl);
-    if (n->in(0) == proj) {
-      phase->igvn().replace_input_of(n, 0, new_unc_ctrl);
-    }
-    for (uint i = 0; i < n->req(); i++) {
-      Node* m = n->in(i);
-      if (m != NULL && phase->has_ctrl(m) && phase->get_ctrl(m) == proj) {
-        uses.push(m);
-      }
-    }
-  }
-
-  phase->igvn().rehash_node_delayed(use);
-  int nb = use->replace_edge(proj, new_unc_ctrl);
-  assert(nb == 1, "only use expected");
-}
-
 void ShenandoahBarrierC2Support::test_in_cset(Node*& ctrl, Node*& not_cset_ctrl, Node* val, Node* raw_mem, PhaseIdealLoop* phase) {
   Node* old_ctrl = ctrl;
   PhaseIterGVN& igvn = phase->igvn();
@@ -1198,80 +1128,15 @@
             continue;
           }
 
-          phase->igvn().replace_input_of(u, 1, val);
-          phase->igvn().replace_input_of(lrb, ShenandoahLoadReferenceBarrierNode::ValueIn, u);
-          phase->set_ctrl(u, u->in(0));
-          phase->set_ctrl(lrb, u->in(0));
-          unc = u->in(0)->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
-          unc_ctrl = u->in(0);
-          val = u;
-
-          for (DUIterator_Fast jmax, j = val->fast_outs(jmax); j < jmax; j++) {
-            Node* u = val->fast_out(j);
-            if (u == lrb) continue;
-            phase->igvn().rehash_node_delayed(u);
-            int nb = u->replace_edge(val, lrb);
-            --j; jmax -= nb;
-          }
-
-          RegionNode* r = new RegionNode(3);
-          IfNode* iff = unc_ctrl->in(0)->as_If();
-
-          Node* ctrl_use = unc_ctrl->unique_ctrl_out();
-          Node* unc_ctrl_clone = unc_ctrl->clone();
-          phase->register_control(unc_ctrl_clone, loop, iff);
-          Node* c = unc_ctrl_clone;
-          Node* new_cast = clone_null_check(c, val, unc_ctrl_clone, phase);
-          r->init_req(1, new_cast->in(0)->in(0)->as_If()->proj_out(0));
-
-          phase->igvn().replace_input_of(unc_ctrl, 0, c->in(0));
-          phase->set_idom(unc_ctrl, c->in(0), phase->dom_depth(unc_ctrl));
-          phase->lazy_replace(c, unc_ctrl);
-          c = NULL;;
-          phase->igvn().replace_input_of(val, 0, unc_ctrl_clone);
-          phase->set_ctrl(val, unc_ctrl_clone);
-
-          IfNode* new_iff = new_cast->in(0)->in(0)->as_If();
-          fix_null_check(unc, unc_ctrl_clone, r, uses, phase);
-          Node* iff_proj = iff->proj_out(0);
-          r->init_req(2, iff_proj);
-          phase->register_control(r, phase->ltree_root(), iff);
-
-          Node* new_bol = new_iff->in(1)->clone();
-          Node* new_cmp = new_bol->in(1)->clone();
-          assert(new_cmp->Opcode() == Op_CmpP, "broken");
-          assert(new_cmp->in(1) == val->in(1), "broken");
-          new_bol->set_req(1, new_cmp);
-          new_cmp->set_req(1, lrb);
-          phase->register_new_node(new_bol, new_iff->in(0));
-          phase->register_new_node(new_cmp, new_iff->in(0));
-          phase->igvn().replace_input_of(new_iff, 1, new_bol);
-          phase->igvn().replace_input_of(new_cast, 1, lrb);
-
-          for (DUIterator_Fast imax, i = lrb->fast_outs(imax); i < imax; i++) {
-            Node* u = lrb->fast_out(i);
-            if (u == new_cast || u == new_cmp) {
-              continue;
-            }
-            phase->igvn().rehash_node_delayed(u);
-            int nb = u->replace_edge(lrb, new_cast);
-            assert(nb > 0, "no update?");
-            --i; imax -= nb;
-          }
-
-          for (DUIterator_Fast imax, i = val->fast_outs(imax); i < imax; i++) {
-            Node* u = val->fast_out(i);
-            if (u == lrb) {
-              continue;
-            }
-            phase->igvn().rehash_node_delayed(u);
-            int nb = u->replace_edge(val, new_cast);
-            assert(nb > 0, "no update?");
-            --i; imax -= nb;
-          }
-
-          ctrl = unc_ctrl_clone;
-          phase->set_ctrl_and_loop(lrb, ctrl);
+          Node* iff = u->in(0)->in(0);
+          Node* bol = iff->in(1)->clone();
+          Node* cmp = bol->in(1)->clone();
+          cmp->set_req(1, lrb);
+          bol->set_req(1, cmp);
+          phase->igvn().replace_input_of(iff, 1, bol);
+          phase->set_ctrl(lrb, iff->in(0));
+          phase->register_new_node(cmp, iff->in(0));
+          phase->register_new_node(bol, iff->in(0));
           break;
         }
       }
@@ -1424,20 +1289,6 @@
     Node* raw_mem_for_ctrl = fixer.find_mem(ctrl, NULL);
 
     IdealLoopTree *loop = phase->get_loop(ctrl);
-    CallStaticJavaNode* unc = lrb->pin_and_expand_null_check(phase->igvn());
-    Node* unc_ctrl = NULL;
-    if (unc != NULL) {
-      if (val->in(ShenandoahLoadReferenceBarrierNode::Control) != ctrl) {
-        unc = NULL;
-      } else {
-        unc_ctrl = val->in(ShenandoahLoadReferenceBarrierNode::Control);
-      }
-    }
-
-    Node* uncasted_val = val;
-    if (unc != NULL) {
-      uncasted_val = val->in(1);
-    }
 
     Node* heap_stable_ctrl = NULL;
     Node* null_ctrl = NULL;
@@ -1447,7 +1298,7 @@
 
     enum { _heap_stable = 1, _not_cset, _evac_path, _null_path, PATH_LIMIT };
     Node* region = new RegionNode(PATH_LIMIT);
-    Node* val_phi = new PhiNode(region, uncasted_val->bottom_type()->is_oopptr());
+    Node* val_phi = new PhiNode(region, val->bottom_type()->is_oopptr());
     Node* raw_mem_phi = PhiNode::make(region, raw_mem, Type::MEMORY, TypeRawPtr::BOTTOM);
 
     // Stable path.
@@ -1456,50 +1307,22 @@
 
     // Heap stable case
     region->init_req(_heap_stable, heap_stable_ctrl);
-    val_phi->init_req(_heap_stable, uncasted_val);
+    val_phi->init_req(_heap_stable, val);
     raw_mem_phi->init_req(_heap_stable, raw_mem);
 
-    Node* reg2_ctrl = NULL;
-    // Null case
-    test_null(ctrl, val, null_ctrl, phase);
-    if (null_ctrl != NULL) {
-      reg2_ctrl = null_ctrl->in(0);
-      region->init_req(_null_path, null_ctrl);
-      val_phi->init_req(_null_path, uncasted_val);
-      raw_mem_phi->init_req(_null_path, raw_mem);
-    } else {
-      region->del_req(_null_path);
-      val_phi->del_req(_null_path);
-      raw_mem_phi->del_req(_null_path);
-    }
-
     // Test for in-cset.
     // Wires !in_cset(obj) to slot 2 of region and phis
     Node* not_cset_ctrl = NULL;
-    test_in_cset(ctrl, not_cset_ctrl, uncasted_val, raw_mem, phase);
+    test_in_cset(ctrl, not_cset_ctrl, val, raw_mem, phase);
     if (not_cset_ctrl != NULL) {
-      if (reg2_ctrl == NULL) reg2_ctrl = not_cset_ctrl->in(0);
       region->init_req(_not_cset, not_cset_ctrl);
-      val_phi->init_req(_not_cset, uncasted_val);
+      val_phi->init_req(_not_cset, val);
       raw_mem_phi->init_req(_not_cset, raw_mem);
     }
 
-    // Resolve object when orig-value is in cset.
-    // Make the unconditional resolve for fwdptr.
-    Node* new_val = uncasted_val;
-    if (unc_ctrl != NULL) {
-      // Clone the null check in this branch to allow implicit null check
-      new_val = clone_null_check(ctrl, val, unc_ctrl, phase);
-      fix_null_check(unc, unc_ctrl, ctrl->in(0)->as_If()->proj_out(0), uses, phase);
-
-      IfNode* iff = unc_ctrl->in(0)->as_If();
-      phase->igvn().replace_input_of(iff, 1, phase->igvn().intcon(1));
-    }
-
     // Call lrb-stub and wire up that path in slots 4
     Node* result_mem = NULL;
 
-    Node* fwd = new_val;
     Node* addr;
     if (ShenandoahSelfFixing) {
       VectorSet visited(Thread::current()->resource_area());
@@ -1532,9 +1355,9 @@
         }
       }
     }
-    call_lrb_stub(ctrl, fwd, addr, result_mem, raw_mem, lrb->is_native(), phase);
+    call_lrb_stub(ctrl, val, addr, result_mem, raw_mem, lrb->is_native(), phase);
     region->init_req(_evac_path, ctrl);
-    val_phi->init_req(_evac_path, fwd);
+    val_phi->init_req(_evac_path, val);
     raw_mem_phi->init_req(_evac_path, result_mem);
 
     phase->register_control(region, loop, heap_stable_iff);
@@ -1546,20 +1369,6 @@
 
     ctrl = orig_ctrl;
 
-    if (unc != NULL) {
-      for (DUIterator_Fast imax, i = val->fast_outs(imax); i < imax; i++) {
-        Node* u = val->fast_out(i);
-        Node* c = phase->ctrl_or_self(u);
-        if (u != lrb && (c != ctrl || is_dominator_same_ctrl(c, lrb, u, phase))) {
-          phase->igvn().rehash_node_delayed(u);
-          int nb = u->replace_edge(val, out_val);
-          --i, imax -= nb;
-        }
-      }
-      if (val->outcnt() == 0) {
-        phase->igvn()._worklist.push(val);
-      }
-    }
     phase->igvn().replace_node(lrb, out_val);
 
     follow_barrier_uses(out_val, ctrl, uses, phase);
@@ -3328,26 +3137,3 @@
   // No need for barrier found.
   return true;
 }
-
-CallStaticJavaNode* ShenandoahLoadReferenceBarrierNode::pin_and_expand_null_check(PhaseIterGVN& igvn) {
-  Node* val = in(ValueIn);
-
-  const Type* val_t = igvn.type(val);
-
-  if (val_t->meet(TypePtr::NULL_PTR) != val_t &&
-      val->Opcode() == Op_CastPP &&
-      val->in(0) != NULL &&
-      val->in(0)->Opcode() == Op_IfTrue &&
-      val->in(0)->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none) &&
-      val->in(0)->in(0)->is_If() &&
-      val->in(0)->in(0)->in(1)->Opcode() == Op_Bool &&
-      val->in(0)->in(0)->in(1)->as_Bool()->_test._test == BoolTest::ne &&
-      val->in(0)->in(0)->in(1)->in(1)->Opcode() == Op_CmpP &&
-      val->in(0)->in(0)->in(1)->in(1)->in(1) == val->in(1) &&
-      val->in(0)->in(0)->in(1)->in(1)->in(2)->bottom_type() == TypePtr::NULL_PTR) {
-    assert(val->in(0)->in(0)->in(1)->in(1)->in(1) == val->in(1), "");
-    CallStaticJavaNode* unc = val->in(0)->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
-    return unc;
-  }
-  return NULL;
-}
diff -r 0bb101fbeb10 src/hotspot/share/gc/shenandoah/c2/shenandoahSupport.hpp
--- a/src/hotspot/share/gc/shenandoah/c2/shenandoahSupport.hpp	Wed May 13 09:36:12 2020 +0000
+++ b/src/hotspot/share/gc/shenandoah/c2/shenandoahSupport.hpp	Wed May 13 20:43:12 2020 +0200
@@ -63,9 +63,6 @@
   static void call_lrb_stub(Node*& ctrl, Node*& val, Node* load_addr, Node*& result_mem, Node* raw_mem, bool is_native, PhaseIdealLoop* phase);
   static void test_in_cset(Node*& ctrl, Node*& not_cset_ctrl, Node* val, Node* raw_mem, PhaseIdealLoop* phase);
   static void move_gc_state_test_out_of_loop(IfNode* iff, PhaseIdealLoop* phase);
-  static Node* clone_null_check(Node*& c, Node* val, Node* unc_ctrl, PhaseIdealLoop* phase);
-  static void fix_null_check(Node* unc, Node* unc_ctrl, Node* new_unc_ctrl, Unique_Node_List& uses,
-                             PhaseIdealLoop* phase);
   static void merge_back_to_back_tests(Node* n, PhaseIdealLoop* phase);
   static bool identical_backtoback_ifs(Node *n, PhaseIdealLoop* phase);
   static void fix_ctrl(Node* barrier, Node* region, const MemoryGraphFixer& fixer, Unique_Node_List& uses, Unique_Node_List& uses_to_ignore, uint last, PhaseIdealLoop* phase);
@@ -254,7 +251,6 @@
   virtual bool cmp( const Node &n ) const;
 
   bool is_redundant();
-  CallStaticJavaNode* pin_and_expand_null_check(PhaseIterGVN& igvn);
 
 private:
   bool needs_barrier(PhaseGVN* phase, Node* n);